STUDIES ON THE STANDARDIZATION OF GROWTH REQUIREMENTS OF MANGROVES FOR ASSESSING THE PROBABILITY OF SITES FOR AFFORESTATION Thesis submitted to the University of Calicut in partial fulfillment of the requirements for the award of the degree of DOCTOR OF PHILOSOPHY IN BOTANY by NEETHU G. PILLAI DIVISION OF ENVIRONMENTAL SCIENCE DEPARTMENT OF BOTANY UNIVERSITY OF CALICUT KERALA - 673 635, INDIA OCTOBER 2017 UNIVERSITY OF CALICUT DEPARTMENT OF BOTANY Division of Environmental Science P.O. Calicut University, Tenhipalam Malappuram District, Kerala – 673 635 Contact: 09447956226 Dr. C.C. Harilal Mail: ccharilal22@gmail.com Associate Professor CERTIFICATE This is to certify that the thesis entitled “Studies on the standardization of growth requirements of mangroves for assessing the probability of sites for afforestation”, submitted to the University of Calicut by Mrs. Neethu G. Pillai, in partial fulfillment of the award of the degree of Doctor of Philosophy in Botany is a bonafide record of the research work carried out by her under my guidance and supervision. No part of the present work has formed the basis for the award of any other degree or diploma, previously. University of Calicut Dr. C. C. Harilal 31st October 2017 (Supervising Teacher) DECLARATION The thesis entitled “Studies on the standardization of growth requirements of mangroves for assessing the probability of sites for afforestation”, submitted by me in partial fulfillment of the requirements for the award of the degree of Doctor of Philosophy in Botany of the University of Calicut is an original research work carried out by me under the guidance and supervision of Dr. C.C. Harilal, Assistant Professor, Department of Botany, University of Calicut. No part of the work formed the basis for the award of any other degree or diploma of any University. University of Calicut Neethu G. Pillai 31st October 2017 ACKNOWLEDGEMENT Completion of this doctoral research was accomplished with the support of many. I would like to take this opportunity to thank all the persons who have made it possible for me to commence and complete this task. I remember them for their efforts, cooperation and collaboration that have worked towards the successes of this study. First of all, I am extremely privileged to place on record my deep sense of gratitude to my supervising guide, Dr. C.C. Harilal, Assistant professor, Department of Botany, University of Calicut, for patiently taking me through this research work. He has been a source of inspiration and support throughout the course of my research work. This feat was possible only because of the valuable guidance and scholarly inputs provided by him. I owe him a lot for providing constant encouragement and invaluable time in all the stages of my research. I wish to place on record my gratitude to Prof. (Dr). Santhosh Nampy, Head, Department of Botany, Prof. (Dr). John E. Thoppil, Prof. (Dr). K.M Jayaraman, Prof (Dr). M. Sabu (former heads), for providing various facilities during the tenure of my work. Dr. K.V. Mohanan, Professor, Department of Botany and Director, Interuniversity centre for Plant Biotechnology, University of Calicut is greatly acknowledged for his timely help in the statistical analysis of my research work. The valuable suggestions from Dr. P. Manimohan, Professor, Department of Botany, University of Calicut as Doctoral Committee member is greatly acknowledged. I wish to thank all the faculty members of Department of Botany, University of Calicut, for their valuable support. It is my pleasure to put on record the support and friendliness I have enjoyed from Miss Karthika S. Menon, Mr. Sajith U and Mrs. Shilna E.P. The timely help rendered by Dr. Hidayathulla R.M., is greatly acknowledged. I owe special thanks to my fellow researchers Mrs. Rathy M.C., Mrs. Snisha S., Dr. Ajayan K.V, Mrs Bindhumol G.P., Mrs Sheeja K.M., Mrs Jasmine P.J. and Mr. Hareesh for their companionship, inspiring advice, continuous encouragement and well-timed support. I wish to thank all the office staff, Department of Botany, University of Calicut for their help during the course of my work. Special thanks to Dr. Prakasan, Librarian, Department of Botany for extending the Library facilities. I thank Mr. Ayyappan, staff, Kadalundi – Vallikkunnu community Reserve, Malappuram and the officials of Ayiramthengu Government fish farm, Kollam, for facilitating my field collections. I am sincerely grateful to Mrs. Soorya, Dr. Aswani, Mrs. Fabeena, and Mrs Ambili for their timely help during my field studies and sample collections. Words make me fail to express my feelings of gratitude to my beloved Amma, my husband Syam Krishnan, daughter Vedhika, my in- laws and all other members of my family, who stood by me in all the tough times during my research work. It was their prayers, love and innumerable sacrifices that fuelled my journey through these research work. I deeply miss my father, who is not with me to share this joy. Above all, I owe it all to Almighty God for granting me the wisdom, health and strength to undertake this research task and its completion. Neethu G. Pillai Dedicated to My Beloved Family CONTENTS Title Page No I. General introduction 1-14 II. Chapter 1 15-48 Extent and diversity of mangroves in Kerala Introduction 15 Review of Literature 18 Materials and Methods 24 Results and Discussion 26 Summary and Conclusion 46 III. Chapter 2 Standardization studies on the growth sustaining 49-189 attributes of selected mangrove species Introduction 49 Review of Literature 53 Materials and Methods 59 Results and Discussion 85 Summary and Conclusion 187 IV. Chapter 3 Delineation of sites for mangrove afforestation in 190-241 Kerala Introduction 190 Review of Literature 193 Materials and Methods 197 Results and Discussion 207 Summary and Conclusion 240 V. General Conclusion 242-244 VI. References 245-266 LIST OF TABLES Table No. Title Page No 1.1 District wise extent of mangrove patches in Kerala 27 1.2 Extent of mangroves along different districts of Kerala 32 1.3 Mangrove cover changes in km2 36 1.4 Diversity of true mangrove species in different districts of 38 Kerala 1.5 True mangrove species of Kerala identified in the present 43 study 2.1 Study sites for selected mangrove species 60 2.2 Physico- chemical characteristics of water samples from 86 habitats of Avicennia officinalis 2.3 Physico- chemical characteristics of water samples from 90 habitats of Bruguiera cylindrica 2.4 Physico- chemical characteristics of water samples from 95 habitats of Excoecaria agallocha 2.5 Physico- chemical characteristics of water samples from 100 habitats of Rhizophora mucronata 2.6 Physico- chemical characteristics of water samples from 104 habitats of Sonneratia alba 2.7 Physico- chemical characteristics of sediment samples 119 from habitats of Avicennia officinalis 2.8 Physico- chemical characteristics of sediment samples 121 from habitats of Bruguiera cylindrica 2.9 Physico- chemical characteristics of sediment samples 124 from habitats of Excoecaria agallocha 2.10 Physico- chemical characteristics of sediment samples 127 from habitats of Rhizophora mucronata 2.11 Physico- chemical characteristics of sediment samples 130 from habitats of Sonneratia alba 2.12 Textural classes of sediments noticed along mangrove 138 habitats under study 2.13 Description of each sediment class noticed in the present 138 study 2.14 Climatological attributes experienced along the habitats of 140 Avicennia officinalis 2.15 Climatological attributes experienced along the habitats of 141 Bruguiera cylindrica 2.16 Climatological attributes experienced along the habitats of 143 Excoecaria agallocha 2.17 Climatological attributes experienced along the habitats of 144 Rhizophora mucronata 2.18 Climatological attributes experienced along the habitats of 146 Sonneratia alba 2.19 Range of environmental attributes influencing the growth 151 of selected mangrove species 2.20 Comparative study of locations and seasons of Avicennia 160 officinalis with respect to water and sediment quality 2.21 Comparative study of locations and seasons of Bruguiera 165 cylindrica with respect to water and sediment quality 2.22 Comparative study of locations and seasons of Excoecaria 169 agallocha with respect to water and sediment quality 2.23 Comparative study of locations and seasons of Rhizophora 174 mucronata with respect to water and sediment quality 2.24 Comparative study of locations and seasons of Sonneratia 178 alba with respect to water and sediment quality 3.1 Details of study area falling in Trivandrum district 198 3.2 Details of study area falling in Kollam district 199 3.3 Details of study area falling in Alleppey district 200 3.4 Details of study area falling in Ernakulam district 201 3.5 Details of study area falling in Thrissur district 202 3.6 Details of study area falling in Malappuram district 203 3.7 Details of study area falling in Kozhikode district 204 3.8 Details of study area falling in Kannur district 205 3.9 Details of study area falling in Kasaragod district 206 3.10 Results on the physico-chemical characterization of water 208 samples along different locations in Trivandrum district 3..11 Results on the physico-chemical characterization of 209 sediment samples along different locations in Trivandrum district 3.12 Results on the physico-chemical characterization of water 211 samples along different locations in Kollam district 3.13 Results on the physico-chemical characterization of 211 sediment samples along different locations in Kollam district 3.14 Results on the physico-chemical characterization of water 213 samples along different locations in Alleppey district 3.15 Results on the physico-chemical characterization of 214 sediment samples along different locations in Alleppey district 3.16 Results on the physico chemical characterization of water 216 samples along different locations in Ernakulam district 3.17 Results on the physico chemical characterization of 217 sediment samples along different locations in Ernakulam district 3.18 Results on the physico-chemical characterization of water 219 samples along different locations in Thrissur district 3.19 Results on the physico-chemical characterization of 220 sediment samples along different locations in Thrissur district 3.20 Results on the physico-chemical characterization of water 222 samples along different locations in Malappuram district 3.21 Results on the physico chemical characterization of 223 sediment samples along different locations in Malappuram district 3.22 Results on the physico chemical characterization of water 225 samples along different locations in Kozhikode district 3.23 Results on the physico chemical characterization of 226 sediment samples along different locations in Kozhikode district 3.24 Results on the physico-chemical characterization of water 228 samples along different locations in Kannur district 3.25 Results on the physico chemical characterization of 229 sediment samples along different locations in Kannur district 3.26 Results on the physico-chemical characterization of water 231 samples along different locations in Kasaragod district 3.27 Results on the physico-chemical characterization of 232 sediment samples along different locations in Kasaragod district 3.28 Details of moderately ideal, ideal and perfectly ideal sites 234 for mangrove afforestation along all the districts under study 3.29 Textural classes of soil / sediment samples along all the 237 sites along 9 districts of Kerala ABBREVIATIONS µm : Micromolar µmol/l : Micromole per litre CaCO3 : Calcium carbonate cm : Centimeter Cmol/kg : Centimole per kilogram CRZ : Coastal Regulatory Zone DO : Dissolved oxygen EDTA : Ethylenediaminetetraacetic acid g : Gram g/kg : Gram per kilogram ha : Hectare HCl : Hydrochloric acid hrs : Hours KCl : Potassium Chloride Kg/ha : Kilo gram per hectare km : Kilometer km2 : Square kilometer m : Meter Mg/g : Milligram per gram Mg/kg : Milligram per kilo gram Mg/l : Milligram per litre ml : Milli litre mm : Millimolar mms : Millimeter per second mS : Milli seimens nm : Nanometer NTU : NephelometricTurbidity Unit o C : Degree Celsius pm : Picomolar ppt : Parts per thousand psu : Practical Salinity Unit GENERAL INTRODUCTION Mangroves are considered as one of the most specialized ecological assemblages of halophytic plants acting as a transient zone between land and ocean. They comprise of taxonomically diverse shrubs and trees, distributed along tropical and sub tropical environments having specific habitats such as shores, estuaries, tidal creeks, backwaters, lagoons, marshes, mudflats and even at upstream points where water remains saline ( Qasim, l998). Mangrove trees are highly adapted with aerial roots, viviparous seeds and salt exclusion/excretion mechanisms (Tomlinson, 1986; Hogarth, 2007). This enables them to cope up with periodic immersion and exposure to the tide, fluctuating salinity, and low oxygen concentrations in the water and sediments and sometimes high temperatures (Hogarth, 2007). The peculiar adaptation of the trees with aerial and salt-filtering roots and salt-excreting leaves enable them to occupy the saline wetlands, where other plant life cannot survive. Both climate and environment are known to play prominent role in the survival of mangroves (Gilman et al., 2008). Among the climatic factors, temperature fluctuations, humidity percentage, total annual rainfall, regular wind flow, radiation and sedimentation along with upstream water supply also play very dominant role in the growth and establishment of mangroves (Kathiresan and Bingham, 2001). Mangroves prefer a humid climate and fresh water inflow that brings in abundant nutrients and silt. They grow luxuriantly in alluvial soil and are plentiful in broad, sheltered, low lying coastal plains where topographic gradients are small and tidal amplitudes are large. Repeatedly flooded and well drained soils support good mangrove growth and high species diversity (Azariah et al., 1992) and they grow poorly in stagnant water (Gopal and Krishnamoorthy, 1993). Their distribution is strongly affected by temperature (Duke, 1992), moisture (Saenger and Snedaker, 1993) and large scale currents (De Lange and De Lange, 1994). Studies have 1 revealed that the most favorable temperature range for mangrove plants is between 20°C and 35°C (www.niobioinformatics.in). It has also been reported that, annual average temperatures below 5°C and above 35°C are detrimental to the growth of mangroves (Alongi, 2002). Development of mangrove patches depends on the hydrological, sedimentological and ecological features of the area. Accordingly six mangrove types are recognized worldwide and they include over wash forests, fringe forests, riverine forests, basin forests, scrub and hammock forests (Lugo and Snedaker, 1974). Over wash mangroves occur on low elevation islands and peninsulas which are characterized by inundation on all high tides. Fringe forests dominate sheltered shorelines and are commonly a part of allowing sediments and organic debris. They are also inundated by high tides. Riverine forests develop in embayment downstream of rivers with ample water flow. It is a productive one, occurred by seasonal flooding. Basin mangrove forests are located in the river/tidal drainages, where there is a reduced tidal inundation. Scrub mangrove forests are seen along the flat coastal fringes by forming dwarf mangrove settings. Hammock mangrove forests are similar to the basin type, except that they occur in more elevated sites than the other five. If the mangrove system is having regular flooding and is in rhythm with tidal conditions, riverine forests, which are the most productive one, will establish. Mangrove forests are unique functional ecosystems having much social, economic and biological importance. They are among one of the most productive ecosystems of the world as they provide important ecosystem supplies and services to human society as well as coastal and marine systems (Bouillon et al., 2003; FAO, 2007). These habitats interact with a wide array of aquatic or terrestrial flora and fauna, enabling their growth and establishment. They serve as habitat for a variety of organisms and are an excellent breeding and nursing grounds for marine and pelagic organisms such as juvenile fish, shellfish, reptiles, crabs etc. (Giri et al., 2011). They also serve as food, medicine, fuel and building materials for local communities (Sasidhar and Rao, 2015). 2 The proximity of mangrove habitats to the coastline makes them efficient water filters of pollutants and contaminants, thus improving water quality. The production of a more-or-less continuous input of dead leaf material to the surrounding bodies of water provides the basic food input to the detritus food web, which is the basis of secondary production in mangrove-linked estuaries. As a nutrient filter and synthesizer of organic matter, mangroves create a living buffer between land and sea (Tomlinson, 1986; Macintosh and Ashton, 2002). Together with sea grass meadows and salt marshes, mangroves are recognized as one of the key ‘blue carbon’ habitats. They are the most carbon-rich forests in the tropics, able to sequester 6 to 8 tonnes of carbon dioxide equivalent per hectare per year. This rate is two to four times greater than global rates observed in mature tropical forests (Murray et al., 2011). Most of the carbon stored by mangroves is in the form of below-ground biomass (Alongi, 2014). Covering only 0.1% of the earth’s continental surface, the forests account for 11% of the total input of terrestrial carbon into the ocean (Jennerjahn and Ittekot, 2002) and 10% of the terrestrial dissolved organic carbon (DOC) to the ocean (Dittmar et al., 2006). The ability of mangroves to sequester and store huge amounts of carbon plays an important role in global carbon budgets and in the process of mitigating climate change. Mangroves are considered to play an important role in controlling coastal hydrodynamics and sediment movements (Boto, 1992; Eong, 1993). As mangroves are bordered by shallow sea water, they are protected from direct wave action. Mangrove cover act as an effective protector against the assault of coastal events and its ferocity than any of the artificial structures. Roots of mangrove trees and plants bind and stabilize the substrate sediment. They prevent shoreline erosion by acting as a buffer zone and catch alluvial materials, thus stabilizing land elevation through sediment accretion that balances sediment loss (Krauss et al., 2003). All such properties reveal their pivotal role in coastal protection, reducing the risk of damage from erosion, natural ecological disasters and calamities such as tsunamis, hurricanes etc. (Guebas et al., 2005; Alongi, 2008). 3 Mangroves are mainly found between the Tropic of Cancer and the Tropic of Capricorn, covering majority of the tropical and subtropical coastlines, worldwide (Saenger, 2002). Global distribution of mangroves largely lies between latitudes 30ºN and 30ºS (Giri et al., 2011). FAO (2007) estimated that mangroves cover an area of 12 to 20 million hectares. The world’s mangroves are distributed mainly in Asia (42%), followed by Africa (21%), North and Central America (15%), Oceania (12%) and South America (10%).Though the world’s mangrove forests are spread across 118 countries and territories, one third of them are spread in just 15 countries (FAO, 2007). Distribution status of mangroves in 2010 revealed that they occur in 123 countries and territories globally, constituting a total of 1, 52,000 km2 (Spalding et al., 2010). 73 mangrove species were also reported, including some hybrid species. The list included both true mangroves and mangrove associates. Another statistical report proposed by Giri et al. (2011) revealed the existence of 1, 37,760 km2 of mangrove forests in 118 countries and territories. Recent reports on the distribution of mangroves show that they are found in 105 nations globally (Hamilton and Casey, 2016). Although mangroves have been distributed across different nations, the top 10 mangrove holding nations possess approximately 52% of the global mangrove stock. Indonesia alone holds 26 – 29 % (Hamilton and Casey, 2016). The largest continuous area of mangrove forest is situated in-and-around the Sundarbans National Park in India and the Sundarbans Mangrove Forests in Bangladesh, both recognized by UNESCO as World Heritage Sites (UNESCO, 2016). The mangrove distribution status in Asia shows that, they are mainly distributed in Bangladesh, Indonesia, Pakistan, Srilanka, Philippines and India. India has been reported for holding the fourth largest mangrove cover in the world (Mandal et al., 1995). Including the island territories, India has a total of 7,516.6 km coastline. Of these, 6,749 km2 areas were occupied by mangrove forest (Naskar and Mandal, 1999). There are several reports with the Ministry of Environment and Forest, Government of India, stating the status of mangroves in the country. “Status Report on 4 Mangroves of India in 1987 and report of the Inter alia Forest Survey of India stated that, within the 7,500 km coastalline, India supports 4, 87,100 ha of mangrove wetlands, in that nearly 56.7% i.e. 2, 75,800 ha is spread along the east coast region and 23.5% (1, 14,700 ha) in the west coast region and the remaining 19.8% (96,600 ha) in Andaman and Nicobar islands (MoEF, 1987). Among the Indian mangroves, the Sundarbans of West Bengal is the largest one. It is followed by the Andaman and Nicobar Islands. The mangroves of the above two localities together accounts for 80% of the total Indian mangroves (MoEF, 1987). The remaining mangroves are scattered in Maharashtra, Gujarat, Orissa, Goa, Andhra Pradesh, Tamil Nadu, Karnataka and Kerala. According to a status report of the Government of India publication, the total area of the mangroves in India has been reckoned at about 6,740 km2. This covers about 7% of the world mangroves (Krishnamurthy, 1987) and 8% of the Indian coastline (Untawale, 1987). Of the total area of mangroves, about 60% is along the east coast (Bay of Bengal), 27% is along the west coast (Arabian Sea) and the remaining 13% is in the Andaman and Nicobar Islands. These mangrove habitats (69o - 89.5oE longitude and 7o - 23oN latitude) comprise three distinct zones: east coast habitats having a coast line of about 2700 km, facing Bay of Bengal, west coast habitats with a coast line of about 3000 km, facing Arabian sea, and Island Territories with about 1816.6 km coastline. The state of West Bengal has the maximum cover (2,097 km2), followed by Gujarat (1,103 km2) and the Andaman and Nicobar Islands (604 km2) (FAO, 2007; FSI, 2009). However, a recent assessment shows that India has a total mangrove cover of only 4,628 km². This accounts for 0.14% of the country’s land area, 3% of the global mangrove area, and 8% of Asia’s mangroves (FSI, 2013). Reports show that Indian mangroves comprise of 59 species in 41 genera and 29 families. Of these, 34 species coming under 25 genera and 21 families belong to west coast. About 16 mangrove species are reported from Gujarat coast, 20 from Maharashtra, 14 from Goa and 10 species from Karnataka (Singh et al., 2012). 5 In Kerala, the mangrove cover has been distributed along the upper reaches of estuaries, lagoons, backwaters and creeks (Mohanan, 1997). It has been reported that, the extent of mangroves of Kerala is 2,502 ha out of which, 1,189 ha belongs to the state and 1,313 ha is under private ownership (Vidyasagaran and Madhusoodanan, 2014). Kannur district occupies maximum extent of mangroves (1,100 ha) followed by Ernakulam (600 ha) and Kasaragod (315 ha) and minimum extent was represented by three districts namely Malappuram (26 ha), Thiruvanthapuram (28 ha) and Thrissur (30 ha) (Vidyasagaran and Madhusoodanan, 2014). The major patches of mangroves are also distributed in places like Veli, Asraamam, Ashtamudi, Keeryad Island, Chetwai, Vypeen Island, Mallikkad, Kumarakom, Pathiramanal, Edakkad, Pappinissery, Kunhimangalam, Chittarai and in several other small patches across the State (Suma, 1995). A total of 15 pure mangroves species and about 33 semi mangrove species were recorded from different parts of the State (Vidyasagaran and Madhusoodanan, 2014). The important species found are Aegiceras corniculatum, Avicennia marina, Avicennia officinalis, Bruguiera cylindrica, B. gymnorhiza , B. sexangula , Ceriops tagal, Excoecaria agallocha, E. indica , Kandelia candel, Lumnitzera racemosa, Rhizophora apiculata, R. mucronata, Sonneratia alba and S. caseolaris (Banerjee, 1989). The mangrove ecosystem is one of the most productive ecosystems on the globe, despite being one of the most threatened. In spite of the ecological and economical importance, mangroves are being widely destroyed at a mean rate of 1-2 per cent per year (Duke et al., 2007; FAO, 2007) and rate of loss may be as high as 8 per cent per year in some developing countries (Polidoro et al., 2010). Nature as well as man is responsible for the destruction of mangrove ecosystem (Valiela et al., 2001). Natural processes such as storms, cyclones, hurricanes, tides, sea level changes, drought, floods etc can be detrimental to the existence of mangroves. The mangroves may or may not tolerate the sea level rise depending on the tide level (Mc Kee et al., 2007), species composition, sediment accretion rate etc. 6 Global warming and eutrophication also plays havoc to the mangrove population. By 2025, due to global warming and green house effect, temperature is expected to increase by 0.5-0.9oC, resulting in sea level rise by 3-12 cm (Watson et al., 2001). This may induce changes in soil chemistry and structure as well as variation in communities of flora and fauna. Bacteria, viruses, fungi, boring insects and crustaceans which feed on mangrove propagules are other natural agents bringing destruction to mangroves. High rates of sedimentation can also prove to be fatal to mangrove habitats by initiating changes in the biogeochemistry of the environment and smothering the pnuematophores (Ellis et al., 2004). The greatest threat to mangroves is through human activities. Vast tracts of mangroves have been converted to shrimp farms or agricultural fields, in addition to construction for residential and recreational purposes. Clear cutting of mangrove forests for timber contributes to changes in mangrove forests. This can lead to major modifications of soil properties of mangrove forests; disturb the watershed level (Dai et al., 2001) and loss of soil nutrients. Urbanization often resulted in increased sedimentation in coastal waters, which destroys the flora and fauna of mangrove ecosystem. Since mangroves are usually close to human habitats, they are used as dumping grounds for sewage and other domestic wastes. Land use changes result in increased nutrient and toxic material loading into water bodies which may pose unacceptable ecological risk to coastal ecosystems including mangroves (Bouillon, 2003). Terrestrial run offs containing fertilizers, pesticides, effluents carried by rivers containing trace metals, organic toxicants such as poly nuclear hydrocarbons, polychlorinated biphenyls, oil spills and petroleum hydrocarbons pose great threat to mangroves (Zhang et al., 2014). Over the last century, there has been extensive loss and degradation of mangrove habitats due to coastal development, pollution, aquaculture and logging for timber and fuel wood. It is estimated that since 1970, 28% of mangrove habitats have been directly displaced by commercial aquaculture (Hamilton, 2013). But the greatest loss has been noticed in the period from 1980 to 1990 (Valiela et al., 2001). 7 From 2000 to 2012, the global mangrove deforestation rate was between 0.16% and 0.39% annually but as high as 3.58% to 8.08% in Southeast Asia (Hamilton and Casey, 2016). The most recent and comprehensive global assessment of mangrove distribution was conducted by Richards and Friess (2016) and provided a high- resolution global database of mangrove loss. According to the International Union for Conservation of Nature and Natural resources (IUCN) Red List criteria categories of endangered species, up to 11 mangrove plants species are at high risk of extinction (Polidoro et al., 2010). Estimates show that 11 out of 70 mangrove species (16%) which were assessed will have to be placed on the IUCN Red List. The Atlantic and Pacific coasts of Central America, where as many as 40 percent of mangrove species are considered threatened, are particularly affected (www.iucnredlist.org.). The fauna also have more than 40% of mangrove-endemic vertebrates that are globally threatened (Luther and Greenberg, 2009). The depletion of mangroves is a cause of serious environmental and economic concern to many developing countries. In the last 50 years, between 30% and 50% of the mangrove forests have disappeared, this loss is continuing and in some places, it is even accelerating. The rate of coastal ecosystems annual loss is 4-times the rate of tropical forest loss (Copertino, 2011). The continuing degradation and depletion of this vital resource will reduce not only terrestrial and aquatic production and wildlife habitats, but more importantly, the environmental stability of coastal forests that provide protection to inland agricultural crops and villages will become seriously impaired. Of the remaining mangrove stands, it is estimated that 52% are degraded due to shrimp/fish culture, 26% due to forest use, and 11% due to freshwater diversion. As a result, mangroves and the species that depend on them are at an elevated risk of extinction. At the present rate of loss, the world faces a real risk of losing the services provided by mangroves entirely in the next 100 years (Duke, 2007). 8 Rates of mangrove degradation vary significantly between countries, often due to differences in environmental policies, legislation, and management. For example, although total mangrove loss in many of the Asian and Pacific regions between 1980 and 2005 is estimated as being consistent with the global rate of 20 per cent, East African and Australian regions loss was less than 10 per cent over the same period (Spalding et al., 2010). Mangrove cover in Sri Lanka experienced deforestation rates of only 0.1 per cent between 1975 and 2005 (Giri et al., 2007), while rate of loss in both the Philippines and Honduras have been increasing since the 1990s because of promotion of shrimp farming and aquaculture (Mc Owen et al., 2016). Indian mangroves have a long history that received attention right from the 17 century itself. Inspite of their immense role in protecting human resource as well as biodiversity, these unique mangrove habitats have been facing tremendous threats due to indiscriminate exploitation for multiple uses like fodder, fuel wood, timber for building material, alcohol, paper, charcoal and medicine (Upadhyay et al., 2002). Reports show that almost all the mangrove areas in India are severely degraded with reduced or negligible vegetation cover (Wilkie et al., 2003). Maximum decline in the mangrove cover has been noticed from the period 1980-2000. This fact was evidenced by a higher decline of 80% in the Pichavaram mangroves of South East Coast of India (Selvam et al., 2010; Sahu et al., 2015). Reports also show that, more than 33% of the Indian mangrove areas have been lost within the last 15 years. Of this, east coast area has lost about 28%, west coast area about 44% and Andaman & Nicobar Islands about 32% (Jagtap et al., 1993; Naskar, 2004). The uncontrolled exploitation and degradation of mangroves in most of the tropical countries have called for an urgent need of implementing conservation and management strategies. In addition, awareness concerning economic, social, and ecological values of mangroves has led to an increase in the number of initiatives to protect and restore mangrove areas (Valiela et al., 2001; FAO, 2007). Considering their value for the environment and coastal communities, mangrove conservation should become a priority and efforts must be invested to find new and successful methods for conserving mangrove ecosystems (Bosold, 2012). 9 Mangroves are considered as wastelands by general public. This has been the reason for their wide destruction along different parts of the world. Environmental education and awareness campaigns are necessary for preserving mangrove areas. Involvement of local government or non government educational institutions in terms of conducting awareness programs and comprehension of mangrove ecosystem restoration goals and methods have to be ensured with active participation from all stake holders within the community. For the proper management of mangrove areas, stress should be given for mangrove biodiversity conservation and ecosystem restoration. Scientists from different parts of the world have recognized and realized that these vulnerable ecosystems are threatened and endangered. Various international organizations like UNESCO, UNDP, IUCN and WWF have shown active interest in the restoration of mangroves (Nasker and Guhabakshi, 1989). Silvicultural techniques like regeneration, restoration and afforestation of mangroves can very well reverse the issues of degradation. Mangrove conservation requires a collaborated research involving natural, social and inter-disciplinary approaches. In order to formulate long term conservation strategies, consideration of factors such as monitoring of growth conditions, socio-economic dependency and biodiversity are indispensable (Kiran and Ramachandra, 1999). Restoration is defined as the return from a disturbed or totally altered condition to a previously existing natural or altered condition by some human action (Lewis, 1990). Mangrove ecosystems are often cited as being responsive to differences in soil salinity, frequency of tidal inundation, sedimentation, soil chemistry, freshwater influx and groundwater availability. This is said to have led to significant variations noted in mangrove community structure and function, even within small geographic ranges (Ravichandran, 2002). The restoration program should be sensibly designed in such a way that, mass afforestation of the native species and elimination of undesirable species are carried out. Restoration sometimes requires reconstruction of the physical conditions, chemical adjustment of the soil and water, biological manipulation, reintroduction of native flora and fauna, etc. (Zedler, 1996). The use 10 of biotechnological interventions to produce improved mangrove plantlets (e.g., faster growing plants) could improve the success rate of restoration (Lewis and Brown, 2014). The drastic decline in global mangrove cover and the on-going elimination of mangrove habitats have led both governmental and non-governmental organizations to formulate policies and actions (Giri et al., 2011). Mangrove conservation measures range from traditional approaches, including creation of designated areas protected from clearing and legislation restricting or prohibiting their degradation. In some countries mangroves of states or regions are protected through legislation, limiting or prohibiting mangrove clearing. Legislation of such kind includes Brazil’s Federal Forestry Code, which has been interpreted to prohibit the use of any components of mangrove trees or plants (Webber and Good body, 1998). Mangrove habitats are protected by multiple international conventions and programs. In 2009, the convention on wetlands namely “Ramsar Convention on Wetlands of International importance” has been conducted in which the member countries ensured the maintenance of ecological characteristics along with conservation of mangroves. This movement has resulted in the protection of 278 Ramsar mangrove sites in 68 countries (Webber and Good body, 1998). Other attempts to protect mangroves on an international context included ‘World Heritage sites’ designated by UNESCO, protecting around 26 mangrove habitats. Man and the Biosphere Programme sites of UNESCO have also been involved in the protection of mangrove habitats (Spalding et al., 2010). Protection of mangrove habitat across the world has also been achieved by establishing marine protected areas, including national parks and marine reserves. Examples of national parks that protect mangroves include mangroves national park in the Democratic Republic of Congo, Parc Marin de Moheli of Comoros, Kakadu national park of Australia, Bastimientos island national park of Panama, Kiunga biosphere reserve of Kenya, Everglades national park of United States of America, Sirinat national park of Thailand and Subterranean national park of Philippines. 11 Upon considering the ecosystem service values of mangroves and their decline, various non-governmental organizations are engaged in education about the conservation and restoration of mangroves. These include organizations with projects around the world such as the Mangrove Action Project, Western Indian Ocean (WIO) Mangrove Network, the Mangrove Alliance and Mangrove Watch (Webber and Good body, 1998). In addition to these, there do exist some local and regional agencies for the protection of mangroves (Carter et al., 2015). Some countries such as Cuba and Ecuador have invested significant resources and are testing new approaches to mangrove conservation through engagement of local communities in natural resource governance (Gravez et al., 2013; Lugo et al., 2014). The emerging movements to conserve mangrove habitats include Payment for Ecosystem Services (PES) and Reducing Emissions from Deforestation and forest Degradation (REDD+). Such approaches may provide novel strategies for mangrove conservation in countries that lack sufficient resources for conservation and management (Locatelli et al., 2014). In India strategies pertaining to the conservation and reforestation of mangroves have initiated along the Central West coast. This was mainly with the intention of creating awareness among public regarding the significance of mangroves, control of intertidal mud banks, new avenues for forestry and social forestry activities, biomass increase along the estuaries to enhance biological productivity and to improve bird and animal life (Untawale, 1996). Mangrove forests have been categorized as ecologically sensitive areas by Government of India under the Environment (Protection) Act, 1986. Restriction for development activities and disposal of wastes in these areas have also put forwarded by the CRZ Notification, 1991. Ministry had made a plan-scheme for conservation and management of mangroves and coral reefs in 1986 and constituted a National Committee to advise the Government on relevant policies and programs (Anon, 1997). The national Committee recommends intensive conservation for 15 mangrove areas in the country (Anon, 1997; Jagtap et al., 2002). Creation of buffer zones that limit 12 the anthropogenic activities around the demarcated corridor of the wetland has been considered as the most important management strategy for mangroves (Castelle et al., 1994). Buffer zone might be consisting of diverse vegetation along the perimeter of water body, preferably an indigenous one serving as trap for sediments, nutrients, metals and other pollutants, reducing human impacts by limiting easy access and acting as a barrier to invasion of weeds and other stress inducing activities (Stockdale, 1991). Some of the states in India with long coastlines adopted different strategies for the conservation of mangroves. After many years of wide spread destruction and degradation, significant efforts have been made in recent years by the State Government and the International agencies to restore and regenerate the mangrove stock in Gujarat (Singh et al., 2012). The Gujarat Forestry Development Project implemented in 2007 for a period of 8 years have also significantly focused on restoration involving mangrove plantation along the coastal regions such as forest areas of eastern tribal belt of the state, reserved grasslands in Rajkot district, mangroves in Kori Creek, Kutch Coast, Marine National Park in Jamnagar Division (Viswanath et al., 2011). Conservation strategies in Goa state included the implementation of the Act in 1984 as Daman and Diu Preservation of Trees that restricted the cutting of 15 species of mangrove trees (Notification No. 8/ 10/ 83- FOR dated 11.09.1990). In Kerala, the most vital approach towards the conservation of mangroves relied on awareness among the public. Novel concepts like mangrove resort and conservation through eco-tourism have also been put forwarded towards the protection of mangroves (George and Fernandez, 1994). Pappinissery mangrove theme park is such an ecotourism project on the banks of Valapattanam river, Kannur. For the prevention and deterioration of mangrove environments of Kerala, better co- ordination among various government agencies are also inevitable. Considering many of the ecosystem services and other aspects along coastal environments, mangrove conservation should become a priority and effort must be invested to find out new and successful methods for their afforestation. Reports 13 show that worldwide, the extent of mangrove forests are alarmingly degrading day by day. Similar trends have been noticed along most of the coastal states in India and Kerala is not an exception. A comprehensive approach in terms of research on various aspects of mangrove eco system of Kerala should be given utmost priority for their effective conservation and restoration. Advanced research with respect to diversity, distribution, growth sustaining attributes (water and sediment) of mangroves may aid in the process of formulating proper afforestation strategies along diverse shoreline environments of Kerala and elsewhere. In the above context, present study has been attempted to evaluate the current status of diversity and extent of mangroves in Kerala, standardization of their growth sustaining conditions and assessing different sites for their probability of afforestation. For the better understanding of above facts, results of the present study are depicted in three chapters. Chapter 1 is dealing with extent and diversity of mangroves in Kerala; Chapter 2 with standardization studies on growth parameters of selected mangrove species and Chapter 3 with delineation of sites for mangrove afforestation. 14 CHAPTER 1 EXTENT AND DIVERSITY OF MANGROVES IN KERALA Introduction The mangroves are intertidal plant formations of tropics and subtropics, which are adapted to grow in the saline environments. They are unique in their location, structure and function. These are comparatively one of the well-studied ecosystems throughout the world and have been received attention of researchers from different fields of science. Mangroves belong to diverse group, which may not be closely related in a phylogenetic sense, but may have many special characteristics in common (Chapman, 1975). This evergreen flora comprising of shrubs as well as arborescent species with forestry importance is confined to a few families. They can be classified into four categories; (i) mangroves of moist region (ii) mangroves of sub- humid region (iii) mangroves of semi-arid region and (iv) mangroves of arid region (Anon, 1984; Singh, 2000). Different authors have classified mangroves and associated vegetation into different categories. According to Basha (1992), the mangrove vegetation possesses many structural and physiological peculiarities and is composed of species with strongly marked characteristics, grouped as ‘True mangroves’. Avicennia, Rhizophora etc. are grouped under this category. There are also plants with less strongly marked characteristics, which are grouped as ‘Semi mangroves’ by Transley and Fritch (1905). Examples for semi mangrove species are Achrostichum. There is yet another group, which grow in saline soils fringing the mangrove areas, but thrive on the land which does not get inundated with brackish water even during high tides. They can withstand some amount of brackish water stagnation only for a very short period. These can be grouped as ‘non- mangroves’ or ‘mangrove associates’, which grow near mangrove locations (Basha, 1992). Derris trifoliate, Cerebra odollum are examples of semi mangrove species. 15 The Indian mangroves are one of the major forests of the South East Asia. In India, the total area of mangroves is estimated to be 6,740 km2 (MoEF, 1987), which is about 7% of the world’s mangrove area. The extent of mangroves along the east coast of India is larger than those along the west coast. West Bengal has the biggest mangrove formation and about 4,200 km2 area support mangroves (Basha, 1992). The mangrove ecosystem of the Sundarbans (West Bengal) comprises about 65% and the remaining 35% are distributed in the Bay islands (Andaman and Nicobar islands) and coast lines of eight other states (Blasco, 1975). Indian mangroves are diverse with 125 species, comprising of 39 mangroves and 86 mangrove associates. About 56% of the world’s mangrove species occur in India with mangrove associates as 30 tree species, 24 shrubs, 18 herbs, 6 climbers, four grasses and 4 epiphytes. The species diversity is highest in Orissa (101 species) followed by West Bengal (92 species) and Andaman and Nicobar islands (91 species) (Kathiresan, 2010). Mangroves in Kerala are highly fragmented and confined mostly to the estuaries of major rivers, lagoons, backwaters and creeks along the coastal belt. Mohanan (1997) estimated that, mangroves in Kerala coast are less than 50 km2, existing in discrete and isolated patches with a total of 32 mangrove species. It has been reported that the extent of mangroves of Kerala is 2502 ha, of which 1189 ha belongs to the State and 1313 ha under private ownership (Vidyasagaran and Madhusoodanan, 2014). The major patches of mangroves in Kerala are distributed in Veli, Asraamam, Ashtamudi, Keeryad Island, Chetwai, Vypeen Island, Mallikkad, Kumarakom, Pathiramanal, Edakkad, Pappinissery, Kunhimangalam, Chithari and in several other small patches across the State (Suma, 1995). Kannur district reported maximum extent of mangroves (1100 ha) followed by Ernakulam (600 ha) and Kasaragod (315 ha) and minimum extent with three districts namely Malappuram (26 ha), Thiruvananthapuram (28 ha) and Thrissur (30 ha) (Vidyasagaran and Madhusoodanan, 2014). The dominant species are Acanthus ilicifolius, Avicennia marina, Avicennia officinalis, Bruguiera cylindrica, B. gymnorhiza, B. parviflora, Ceriops tagal, Rhizophora apiculata, R. mucronata and Sonneratia caseolaris (Banerjee, 1989). 16 In the last two decades, mangrove populations have witnessed annual loss between 0.16 and 0.39% globally due to various anthropogenic activities (Hamilton and Casey, 2016). In many areas of the world, mangrove deforestation is contributing to decline in fisheries, degradation of clean water supplies, erosion and land subsidence. At least 40% of the animal species that are restricted to mangrove habitats and have previously been assessed under IUCN categories and criteria are at elevated risk of extinction due to extensive habitat loss. Similarly decline in species diversity is also reported in many geographical regions owing to various anthropogenic stresses. It has been reported that Kerala coast once supported about 700 sq.km of mangroves and presently it has been dwindled to a considerable extent. Mangrove ecosystems are receiving increasing attention in Kerala, but still lack updated information on their diversity and extent for deriving strategic plans for conservation / afforestation. The present study has been carried out to assess the extent and diversity of mangrove ecosystems in the heterogeneous environments of Kerala with a view to conserve their existing habitats from further degradation. 17 Review of Literature Numerous attempts have been carried out worldwide on the extent and diversity of mangroves. Some of the most important ones on a global, national and regional context are summarized below. The greatest extent of mangrove species is found in the Indo-Malaysian region (Chapman, 1975) and thus, it can be considered as the cradle of evolution of mangrove vegetation. There are about 60-100 species of mangroves totally present in the world coming under 30 genera and more than 20 different families (Singh et al., 1987). Studies on their status and distribution in Asia reports that they are distributed mainly in Bangladesh, Indonesia, Pakistan, Srilanka, Philippines and India (Naskar and Mandal, 1999). Earlier reports reveal that globally mangroves cover an area of 12 to 20 million hectares, of which, about one-third is found in Asia (42%), followed by Africa (21%), North and Central America (15%), Oceania (12%) and South America (10%). It has also been reported that 15 countries behold one third of the total global mangroves (FAO, 2007). Later, the total area of mangroves in the year 2000 was 2 estimated to be 1, 37,760 km in 118 countries in the tropical and subtropical regions of the world (Giri et al., 2011). Spalding et al. (2010) revealed the World Atlas of Mangroves, covering 123 countries, constituting a total area of 1, 52,000 km2. The lists included both true mangroves and mangrove associates. Distribution status by Hamilton and Casey (2016) showed that mangroves are found in 105 nations globally; of which 10 nations possess approximately 52%. Higher percentage of global mangrove cover was noted in Indonesia (26-29%). The Sundarbans National Park in India and the Sundarbans Mangrove Forests in Bangladesh have been known to possess the world’s largest continuous stretch of mangrove forest (UNESCO, 2016). India has been reported for holding the fourth largest mangrove cover in the world. 60 species of mangroves belonging to 41 genera and 29 families have been reported (Blasco, 1975). Blasco (1977) reported 58 mangrove species in the Indian territories, 18 while Rao (1986) listed 60 species from 41 genera and 29 families. Studies have reported that the country occupies an area of about 7% of the world mangroves (Krishnamurthy, 1987) and 8% of the Indian coastline (Untawale, 1987). Status report on mangroves of India in 1987 and report of the Inter alia Forest Survey of India stated that, within the 7,500 km coastal line, India supports 4, 87,100 ha of mangrove wetlands, in that nearly 56.7% is spread along the east coast, 23.5% along the west coast and the remaining 19.8% in Andaman and Nicobar islands (MoEF, 1987). The report has also stated that Sundarbans of West Bengal and Andaman and Nicobar Islands together occupy 80% of the total Indian mangroves. Rest of the mangrove flora have been distributed along some of the coastal states such as Maharashtra, Gujarat, Orissa, Goa, Andhra Pradesh, Tamil Nadu, Karnataka and Kerala (MoEF, 1987). Banerjee et al. (1989) reported 59 species including true mangroves and associates belonging to 41 genera and 29 families. Comprehensive studies reported the existence of 32 true mangrove species in India (Singh et al., 2012; Singh and Garge, 1993). Dagar et al. (1993) and Jagtap et al. (1993) reported 36 and 50 species of true mangroves from India. Later in 1999 it has reported that including the island territories, India has a total of 7,516.6 km coastline. Of these, 6,749 km2 areas were occupied by mangrove forest (Naskar and Mandal, 1999). Studies with respect to species distribution revealed varied statistics as some of them included true mangroves whereas others included both true mangroves and mangrove associates. Naskar (2004) has reported 85 species of mangroves / mangrove associates that were common to the Indian coasts. Studies have also reported that, there are 55 species of true mangroves in India and majority are coming under the families Acanthaceae, Avicenniaceae, Meliaceae and Rhizophoraceae (Vidyasagaran and Gopikumar, 2006). Detailed account on the diversity of Indian mangroves has been given by Mandal and Naskar (2008). The total extent of mangroves has been classified in to 3 groups as ‘Major mangroves,’ Mangrove associates,’ and ‘Back mangal’. From a total of 12 habitats, 82 species of mangroves belonging to 52 genera and 36 families have been 19 reported. Using the total number of families, genera and species, relative mangrove diversity has also been calculated. Among different habitats studied, maximum value for relative mangrove diversity has been reported from Sundarbans and minimum from Lakshadweep Atoll (Mandal and Naskar, 2008). According to a status report of the Government of India publication, the total area of the mangroves in India was reckoned at about 6,740 km2. Of the total area of mangroves, about 60% is along the east coast (Bay of Bengal), 27% is along the west coast (Arabian Sea) and the remaining 13% is in the Andaman and Nicobar Islands (FSI, 2009). An overview on the status of biodiversity and distribution of Indian mangroves revealed that there are 59 species in 41 genera and 29 families. 34 species belonging to 21 families have been noticed as unique species along the west coast and the east coast comprised of 25 species. The most important species distributed along west coast were Sonneratia caseolaris, Suaeda fruticosa, Urochondra setulose etc. Distribution status with respect to different states revealed 16 species from Gujarat, 20 species from Maharashtra, 14 species from Goa and 10 species from Karnataka (Singh et al., 2012). Based on preliminary surveys, an updated checklist of true mangrove species falling along Andaman and Nicobar Islands has been reported (Goutham-Bharathi et al., 2014). Visits to selected locations during the period 2009 to 2013 revealed the occurrence of 25 true mangrove species belonging to 10 families and 14 genera. The study also highlighted the need for periodic evaluation of the extent and status of mangroves towards their better management and conservation (Goutham et al., 2014). Mangrove forests have been considerably diminishing as most of the areas are taken for various agricultural and developmental purposes. It was reported that during the last century, Indian coastline has lost 40% of its mangrove cover (Brahma and Mukherjee, 2016). In this background, studies have been conducted to assess the extent of mangroves in India with special reference to Lothian Island Wildlife Sanctuary in Sundarbans. Including 16 true mangrove species and 14 mangrove 20 associates a total of 30 species have been reported from the area. The study has pointed out the need for conserving mangrove ecosystems in terms of effective governance structures, better education and awareness building in local communities (Brahma and Mukherjee, 2016). The preceding literature presented a scattered idea regarding the extent and diversity of mangroves from different districts of Kerala. Bourdillon (1908) reported Brugueira gymnorhiza and Rhizophora species from Kollam district. Rao and Sastry (1974) and Thomas (1962) reported 5 mangrove species such as Acanthus ilicifolius, Avicennia officinalis, Bruguiera gymnorhiza, Rhizophora apiculata and R. mucronata under 4 genera and 3 families from Veli backwaters, Trivandrum. The species Acanthus ilicifolius has been reported from Kollam district (Blasco, 1975). The total extent of mangrove cover in Kerala has undergone drastic changes over a period of time. Kerala once had a total mangrove cover of 700 km2 and has dwindled to 16.71 km2 (Basha, 1991). According to him, the entire mangrove flora of the state has been distributed among different districts like Trivandrum (23 ha), Kollam (58 ha), Alleppey (90 ha), Kottayam (80 ha), Ernakulam (260ha), Thrissur (21 ha), Malappuram (12 ha), Kozhikkode (293 ha), Kannur (755 ha) and Kasaragod (79 ha). Later on Kurien, et al., (1994) has reported that the mangrove cover of the state is only 1,095 ha. Studies by Suma (1995) revealed that the major patches of mangroves in Kerala are distributed in places like Veli, Asraamam, Ashtamudi, Keeryad Island, Chetwai, Vypeen Island, Mallikkad, Kumarakom, Pathiramanal, Edakkad, Pappinissery, Kunhimangalam and Chittarai and in several other small patches across the State. Reports by Mohanan (1997) revealed that the total extent of mangroves in Kerala has been distributed along the upper reaches of estuaries, lagoons, backwaters and creeks were coming to a tune of 4200 ha. Sunil (2000) reported the most important mangroves species of Alleppey district as Acanthus ilicifolius, Aegiceras corniculatum, Avicennia marina, A. officinalis, Bruguiera cylindrica, B. gymnorhiza, Excoecaria agallocha, E. indica, Kandelia 21 candel, Lumnitzera racemosa, Rhizophora apiculata, R. mucronata and Sonneratia apetalae, coming under 9 genera and 7 families. Detailed descriptions on the mangroves of Kerala have been furnished by Anupama and Sivadasan (2004). The study as a whole reported 15 true mangroves and 49 mangrove associates from the entire Kerala coast. The true mangrove species were coming under 9 genera and 7 families. The study revealed detailed notes on all the true mangrove species along with their updated nomenclature and distribution (Anupama and Sivadasan, 2004). Radhakrishnan et al. (2006) reported the occurrence of 7 species of mangroves from Kozhikode district such as Acanthus ilicifolius, Aegiceras corniculatum, Avicennia marina, Excoecaria agallocha, Kandelia candel, Rhizophora mucronata and Sonneratia caseolaris. Thekkumbad island of Kannur district has been studied for the total area covered diversity and population structure of mangroves. Using plot quadrat method, a total of 11 true mangroves and 6 associates have been reported. The most dominant species recorded from the area were Rhizophora mucronata, Bruguiera cylindrica, Sonneratia alba and Excoecaria agallocha (Sreeja and Khaleel, 2010). Compared to other districts, floristic diversity of mangroves in Kannur is very high. Diversity studies from Kannur district revealed 12 species of mangroves under 9 genera, belonging to 7 families. The most important family reported was Rhizophoraceae with four species (Vidyasagaran et al., 2011). Diversity, distribution and abundance of mangroves from Poyya backwaters of Thrissur district reported a total of 9 species; of which 4 were true mangroves and remaining 5 were associates. The true mangrove species reported were Aegiceras corniculatum, Avicennia officinalis, Acanthus ilicifolius, and Excoecaria agallocha. The mangrove associates reported were Derris uliginosa, Clerodendron inerme, Sphaeranthus indicus, Achrostichum aureum, Mariscus javanicus and Cyperus species (Saritha and Tessy, 2011). Studies conducted at Kumbalam Island of Ernakulam district revealed the status of mangroves in the area from the year 2010. A total of 17 species including 7 22 true mangroves, 2 semi mangroves and 8 mangrove associates have been reported from the area (Ram and Shaji, 2013). It has been reported that the extent of mangroves of Kerala is 2,502 ha, out of which, 1,189 ha belongs to the state and 1,313 ha is under private ownership (Vidyasagaran and Madhusoodanan, 2014). Kannur district occupies maximum extent of mangroves (1,100 ha), followed by Ernakulam (600 ha) and Kasaragod (315 ha) and minimum extent was represented by three districts namely Thrissur (30 ha), Thiruvanthapuram (28 ha) and Malappuram (26 ha). A total of 15 pure mangroves species and about 33 semi mangrove species were recorded from different parts of the state. The important species found were Aegiceras corniculatum, Avicennia marina, Avicennia officinalis, Bruguiera cylindrica, B. gymnorhiza, B. sexangula, Ceriops tagal, Excoecaria agallocha, E. indica, Kandelia candel, Lumnitzera racemosa, Rhizophora apiculata, R. mucronata, Sonneratia alba and S. caseolaris (Vidyasagaran and Madhusoodanan, 2014). Studies at Kadalundi- Vallikkunnu community reserve of Malappuram- Kozhikode districts revealed the occurrence of 7 species of mangroves under 5 families. The most important species recorded from the area was Avicennia officinalis followed by Rhizophora mucronata, Excoecaria agallocha and Sonneratia alba (Rahees et al., 2014). A total of 11 species of true mangroves and 6 mangrove associates have been reported from the Ashtamudi estuary of Kollam district (Sumesh et al., 2014). Survey pertaining to the distribution, abundance and plant diversity of the left over mangroves along the 10 coastal districts of Kerala has been carried out. The results revealed a total of 24 species of mangroves belonging to 15 genera and 9 families (Mini et al., 2014). 8 species have been reported from the family Rhizophoraceae. The other families and number of species reported were Acanthaceae (4 species), Myrsinaceae (1 species), Combretaceae (1 species), Malvaceae (1 species), Pteridaceae (1 species), Euphorbiacea (2 species), Lythraceae (3 species) and Arecaceae (3 species). The study highlights the significance and services of the ecosystem as a whole and suggests the urgent need for protecting them in terms of massive afforestation practices (Mini et al., 2014). 23 Diversity and phyto-sociological characteristics of mangroves from six locations of Kollam district has been reported. The study revealed 12 species of mangroves belonging to 8 genera and 6 families in which Rhizophoraceae and Avicenniaceae were the most predominant families. Results of the density and other diversity indices revealed that the most common species recorded was Avicennia officinalis followed by A. marina (Vijayan et al., 2015). The diversity and distribution of mangroves from Kannur district for the period of 2015-16 have been reported by Vaiga and Sincy (2016). From Vellikkeel, 7 species of true mangroves, 4 species of semi mangroves and 7 species of mangrove associates have been reported. 10 species of true mangroves, 3 semi mangroves and 7 mangrove associates have also been reported from Ezhome area. The study concluded that most of the mangrove area within the district has been facing tremendous threats from the public. A review of the literature revealed that studies pertaining to the extent and diversity of mangroves confining to the coast of Kerala is either fragmentary or outdated in nature. Comprehensive database pertaining to their extent and diversity is required for establishing ideal strategies for conservation reliable methods for afforestation. In this perspective, the present study has been outlined to assess the extent and diversity of mangrove ecosystems confining to heterogeneous coastal environments of Kerala. Materials and Methods Study area The state of Kerala (8o 18’ and 12o 48’ N and longitudes 74o 52' and 77o 22' E) is bounded by Karnataka in the North, Tamil Nadu in the South and East and the Arabian Sea in the West. The width of the State varies between 15 and 120 km. The coastal belt extends up to 580 km in length, with a long stretch of back waters, estuaries and river deltas and a series of lagoons running parallel to the sea. Owing to the Western Ghats along the eastern side (wind ward side) and Arabian Sea along the western side, the topography of the state is highly diversified with highland, 24 midland and coastal plain. Most of the rivers of Kerala originate from the highland area, characterized by the Western Ghats. The midlands, lying between the mountains and the lowlands are made up of undulating hills and valleys that serve as an area for intensive cultivation. The coastal area is made up of numerous shallow lagoons, river deltas, backwaters and shores of the Arabian Sea. Though small in size, the state is affluent in water sources. 44 rivers traverse the land, of which 41 are west-flowing and 3 are east-flowing. Apart from these 44 rivers, their tributaries and countless number of rivulets and streams crisscross the land and make them green and fertile. The State is situated in the humid tropics, where the main climatic factor is the rainfall. Kerala's rains are mostly the result of seasonal monsoons. The average annual rainfall of the State is 240 cm, of which 65-70% is received during south- west monsoon (June-August), 18-22% during north-east monsoon (October- December) and remaining as pre monsoon showers. Heavy rainfall coupled with tropical climate is responsible for higher humidity of approximately 70 % throughout the year. The mean annual temperature is 27o C. The average minimum temperature ranges from 19o-20oC whereas, average maximum temperature from 270- 370C. The varied topographical features, high precipitation and geological conditions have favored the formation of diverse vegetation groups, from high altitude shola forests on the high ranges to the coastal mangrove forests. Administratively, the state is divided into 14 districts. Of these, districts like Idukki, Pathanamthitta, Palakkad and Wayanad are falling in the highland area and are not having a coastal plain. All other districts have coastlines, having diverse types of vegetation, including mangroves. The present study envisages evaluation of the extent and diversity of mangroves confining to the 10 districts of Kerala, which include Trivandrum, Kollam, Alleppey, Kottayam, Ernakulam, Thrissur, Malappuram, Kozhikode, Kannur and Kasaragod. Methodology Extensive literature survey has been carried out to have an idea about their habitats, together with a collection of earlier reports on their extent and diversity in the 25 coastal environments of Kerala. Accordingly field visits were carried out to these mangrove habitats confining to 10 districts of Kerala. Specimens were collected from different locations and their identification was carried out following standard mangrove identification guidebook, ‘Mangroves in India – Identification manual’ by Banerjee et al. (1989) and also with the help of experts. Representative specimens were preserved. Similarly, the mangrove patches distributed along different districts under study were categorized into homogeneous and heterogeneous types. The assemblage of true mangrove species along with their associates in a particular area were grouped as homogeneous mangrove population, while patches of true mangroves along with mangrove associates and other vegetation were categorized as heterogeneous mangrove population. Coordinates of mangrove habitats were worked out using a GPS and mangrove area with respect to each district has been evaluated using toposheets and Google map imageries. Both homogenous and heterogeneous patches were separately measured to find out the total extent in square kilometers. Results and Discussion Consolidation of data pertaining to the current status on the extent and diversity of mangroves is a pre requisite for the selection of any strategy for the conservation of existing or the introduction of newer population. In this direction, the present study has been carried out to assess the extent and diversity of mangrove ecosystems confining to 10 districts of Kerala. District wise extent of mangroves in hectares / square kilo meters and their percentage to the total mangrove cover of the State is depicted in Table 1.1 and 1.2 respectively. 26 Table 1.1. District wise extent of mangrove patches in Kerala. Total extent in Sl. Mangrove Extent (ha) 2 Location (km ) No Homogenous Heterogeneous Total Trivandrum District 1. Akkulam - Veli 7.628444 4.92336 12.551804 0.1255 2. Poovar 1.201513 1.950117 3.151630 0.0315 3. Uchakkada 0.017168 - 0.017168 0.0002 4. Puthiyathura 0.096991 0.700350 0.797341 0.0079 5. Kottukal 0.099236 - 0.099236 0.0009 6. Adimalathura 0.259014 - 0.259014 0.0026 7. Vizhinjam 0.014711 - 0.014711 0.0002 8. Thiruvallom 5.321500 4.827689 10.149189 0.1015 9. Edayar -Poonthura 0.424184 - 0.424184 0.4242 Total 15.062761 12.401516 27.464277 0.2746 Kollam District 10. Paravur 0.313207 4.219016 4.532223 0.0453 11. Kalakkode 0.327387 1.182936 1.510323 0.0151 12. Onninmoodu 0.177036 0.001174 0.178210 0.0018 13. Bhoothakkulam 0.394560 - 0.394560 0.0039 14. Ayiramthengu 5.847678 - 5.847678 0.0585 15. Oachira 0.082951 - 0.082951 0.0008 16. Shaktikulangara 15.272060 7.339282 22.611342 0.2261 17. Neendakara 3.447457 - 3.447457 0.0345 18. Ashtamudi 1.066141 - 1.066141 0.0107 19. Perumon 0.149522 0.901315 1.050837 0.0105 20. Thekkumbhagom - 2.391093 2.391093 0.0239 21. Chavara - 0.186698 0.186698 0.0019 22. Munroe island 1.233865 - 1.233865 0.0123 23. Asraamam 1.183758 4.645034 6.828792 0.0683 24. Azheekkal 1.609925 - 1.609925 0.0161 Total 27.105547 20.866548 52.972095 0.5297 Alleppey District 25. Azheekkal 0.776385 - 0.776385 0.0078 26. Valiyazheekkal 3.783586 2.981934 6.765520 0.0677 27. Kandalloor 1.271858 1.882454 3.154312 0.0315 28. Perumpally 0.010541 - 0.010541 0.0001 29. Mullasseril 0.383270 - 0.383270 0.0038 30. Keerikkad 0.059945 1.498759 1.558704 0.0156 31. Arattupuzha 0.225867 - 0.225867 0.0023 32. Puthiyavila 0.039430 0.190175 0.229605 0.0023 33. Muthukulam 0.582634 2.872550 3.455184 0.0346 34. Ramapuram - 0.459792 0.459792 0.0046 35. Chingoli 0.090292 - 0.090292 0.0009 36. Nangiarkulangara - 0.107198 0.107198 0.0011 37. Karthikappally 0.115249 - 0.115249 0.0012 38. Harippad 0.120767 - 0.120767 0.0012 39. Perumpalam - 2.396408 2.396408 0.0239 27 40. Pathiramanal island 2.471841 - 2.471841 0.0247 41. Thankey 0.866303 1.457920 2.324223 0.0232 42. Vayalar 1.241332 2.816479 4.057811 0.0406 43. Valamangalam North 6.147551 6.961954 13.109505 0.1311 44. Thuravur Thekku 1.545206 1.983196 3.528402 0.0353 45. Kodamthuruthu 4.299972 2.169306 6.469278 0.0647 46. Kuthiathode 3.242565 - 3.242565 0.0324 47. Eramalloor 12.500859 16.128475 28.629334 0.2863 48. Kaithavalappu 3.140598 6.532150 9.672748 0.0967 49. Aroor 11.629718 5.681956 17.311674 0.1731 Total 48.71394 55.120706 103.834646 1.0383 Kottayam District 50. Kumaranalloor 5.967512 4.987557 10.955069 0.1096 51. Nattassery 5.425619 3.544014 8.969633 0.0897 52. Choottuveli 1.678164 - 1.678164 0.0168 53. Nagampadam 1.782108 3.311871 5.093979 0.0509 54. Kanjikkuzhi - 0.920370 0.920370 0.0092 55. Keezhukunnu - 0.704752 0.704752 0.0070 56. Kalathipady - 3.756028 3.756028 0.0376 57. Vadavathoor 8.970006 1.316505 10.286511 0.1029 58. Poovanthuruthu 10.821003 - 10.821003 0.1082 59. Kaduvakkulam 3.732499 - 3.732499 0.0373 60. Kollad 5.095399 - 5.095399 0.0510 61. Panachikkadu - 3.251433 3.251433 0.0325 62. Chozhiakkad 2.433232 - 2.433232 0.0243 63. Kumarakom 10.563218 20.199589 30.762807 0.3076 Total 56.46876 41.992119 98.4609 0.9846 Ernakulam District 64. Chellanam 3.006008 2.731752 5.73776 0.0574 65. Kannamali 0.243164 0.248395 0.491559 0.0049 66. Kandakkadavu 0.052681 - 0.052681 0.0005 67. Pazhangad 0.456357 0.662327 1.118684 0.0112 68. Kumbalangi 0.894757 1.940362 2.835119 0.0284 69. Cheriakadavu 2.856128 - 2.856128 0.0286 70. Mundamveli 4.466231 5.172010 9.638241 0.0964 71. Kattiparambu 0.370742 - 0.370742 0.0037 72. Karuvelipady 1.412494 1.893061 3.305555 0.0331 73. Veli- Kochi 5.536089 5.585651 11.12174 0.1112 74. Mattancherry - 0.775301 0.775301 0.0078 75. Kunnumpuram 0.693331 - 0.693331 0.0069 Fort Kochi, Jawahar 76. 3.025151 - 3.025151 0.0303 park Thamaraparambu, 77. 1.494012 - 1.494012 0.0149 Fort Kochi 78. Kumbalam 7.401797 2.007154 9.408951 0.0941 79. Willington island 7.036808 12.921685 19.958493 0.1996 80. Panangad 1.042186 0.936355 1.978541 0.0198 81. Madavana 0.193311 1.198379 1.39169 0.0139 82. Nettoor 7.798867 9.163901 16.962768 0.1696 28 83. Puthuvypin 89.429313 12.995115 102.424428 1.0242 84. Murikumpadam 5.110346 2.790738 7.901084 0.0790 85. Valappu 8.95082 5.579373 14.530193 0.1453 86. Malippuram - 1.030023 1.030023 0.0103 87. Elamkunnapuzha 2.946826 2.492637 5.439463 0.0544 88. Njarackal 1.659706 1.102762 2.762468 0.0276 89. Nayarambalam 1.699621 2.664618 4.364239 0.0436 90. Sathar island 1.674117 - 1.674117 0.0167 91. Munambam 0.586015 0.325813 0.911828 0.0091 92. Pallipuram 0.586616 0.075048 0.661664 0.0066 93. Cherai 0.231925 - 0.231925 0.0023 94. Ayyampilly 0.247196 - 0.247196 0.0025 95. Vypin 0.484587 - 0.484587 0.0048 96. Nedungad 0.724406 - 0.724406 0.0072 97. Valiyakadamakudy 0.188992 0.609413 0.798405 0.0080 98. Kottuvally 0.545107 0.312438 0.857545 0.0086 99. Kedamangalam 0.069970 - 0.069970 0.0007 100. Ernakulam 35.891752 276.693412 312.585164 3.1259 101. Gothuruth 0.48973 - 0.48973 0.0049 102. Chathedom 0.222977 - 0.222977 0.0022 103. Puthenvelikkara 1.09907 - 1.09907 0.0110 104. Edakkunnu 6.778119 - 6.778119 0.0678 105. Palissery 13.843178 - 13.843178 0.1384 106. Pallimalipady 0.695229 5.915043 6.610272 0.0661 107. Vengoor 22.862794 10.022375 32.885169 0.3289 108. Mangalavanam 2.439453 - 2.439453 0.0244 Total 267.437979 426.845141 615.283120 6.1528 Thrissur District 109. Azhikode 0.164948 - 0.164948 0.0017 110. Kodungallur 0.181586 - 0.181586 0.0018 111. Anapuzha 0.47732 0.224865 0.702185 0.0070 112. Chanda Nagar 0.093403 - 0.093403 0.0009 113. Kavinagar 0.329166 - 0.329166 0.0033 114. Mathilakam 0.270521 - 0.270521 0.0027 115. Perinjanam 0.896566 0.322433 1.218999 0.0122 116. Vadanappally 0.523641 - 0.523641 0.0052 117. Manalur 0.764281 - 0.764281 0.0076 118. Chettuvai 6.510775 2.940348 9.451123 0.0945 119. Mullassery - 0.327618 0.327618 0.0033 120. Ayanikkad - 0.293864 0.293864 0.0029 121. Chavakkad 1.428346 0.498284 1.92663 0.0193 122. Poyya 5.501876 1.120398 6.622274 0.0662 123. Pallipuram 3.12118 - 3.12118 0.0312 124. Chenthuruthy - 1.826916 1.826916 0.0183 125. Kombathukadavu 7.25925 - 7.25925 0.0726 126. Chakkamkandam 1.663806 - 1.663806 0.0166 127. Blangad 0.668339 - 0.668339 0.0067 128. Thrissur 2.971368 - 2.971368 0.0297 Total 33.148805 7.554726 40.703531 0.4070 29 Malappuram District 129. Ponnani 1.251754 0.437909 1.689663 0.0169 130. Malappuram 0.967873 0.712248 1.680121 0.0168 131. Veliancode 1.361774 0.71653 2.078304 0.0208 132. Malappuram 0.967873 0.712248 1.680121 0.0168 133. Thavalakulam - 0.385546 0.385546 0.0039 134. Beeyam 0.452704 - 0.452704 0.0045 135. Puthuponnani 0.420663 - 0.420663 0.0042 136. Tavanur 0.873704 - 0.873704 0.0087 137. Mangalam 7.017804 0.412155 7.429959 0.0743 138. Triprangode 1.192038 - 1.192038 0.0119 139. Purathur 0.51798 1.107084 1.625064 0.0163 140. Koottayi 2.434402 - 2.434402 0.0243 141. Tirur 1.130865 0.426823 1.557688 0.0156 142. Palathingal 1.018511 - 1.018511 0.0102 143. Anangadi 0.886409 - 0.886409 0.0089 144. Kadalundi 10.346335 - 10.346335 0.1035 145. Balathiruthi 2.621499 - 2.621499 0.0262 Total 32.918591 3.800018 36.718609 0.3672 Kozhikode District 146. Kadalundi 8.213445 - 8.213445 0.0821 147. Feroke 4.315825 - 4.315825 0.0432 148. Chelembra 1.358132 - 1.358132 0.0136 149. Sarovaram biopark 17.065138 - 17.065138 0.1707 150. Kuruvattoor 3.628640 - 3.628640 0.0363 151. Kottooli 4.119521 - 4.119521 0.0412 152. Malaparamba 0.510675 - 0.510675 0.0051 153. Velur west - 1.720911 1.720911 0.0172 154. Atholi - 2.778702 2.778702 0.0278 155. Ulliyeri 10.828369 - 10.828369 0.1083 156. Mannankavu 3.628527 - 3.628527 0.0363 157. Arikkulam - 4.756577 4.756577 0.0476 158. Maniyur 2.114330 - 2.11433 0.0211 159. Iringal 0.834364 - 0.834364 0.0083 160. Azhiyur 7.023100 - 7.023100 0.0702 161. Payyoli 4.379777 - 4.379777 0.0438 162. Thekkepuram 1.082589 - 1.082589 0.0108 163. Payyanakkal 1.283695 - 1.283695 0.0128 164. Kallai 4.717977 - 4.717977 0.0472 165. Azhchavattam 0.505164 - 0.505164 0.0051 166. Thiruvannur 0.530882 - 0.530882 0.0053 167. Odumbra 1.444049 - 1.444049 0.0144 168. Nallalam 0.683540 - 0.683540 0.0068 169. Cheruvennur 8.482533 - 8.482533 0.0848 170. Kozhikkode 14.553373 7.122649 21.676022 0.2168 171. Koottayi 0.896581 - 0.896581 0.0090 172. Mahe,Puducherry 2.150383 - 2.150383 0.0215 Total 104.350609 16.378839 120.729448 1.2073 Kannur District 30 173. Kokkapuram,Chalil 0.135299 - 0.135299 0.0014 174. Pattiam 0.380572 - 0.380572 0.0038 175. Eranholi - 2.310792 2.310792 0.0231 176. Palayad 15.190857 - 15.190857 0.1519 177. Pinarayi 6.982656 - 6.982656 0.0698 178. Melur 3.835016 - 3.835016 0.0384 179. Kunduchira 4.77715 - 4.77715 0.0478 180. Chonadam 8.058994 - 8.058994 0.0806 181. Koduvally 6.678762 - 6.678762 0.0668 182. Thalassery 15.632793 - 15.632793 0.1563 183. Dharmadom 15.213152 12.391306 22.604458 0.2260 184. Muzhuppilangad 24.374663 1.949701 26.324364 0.2632 185. Edakkad 13.592886 - 13.592886 0.1359 186. Nadal 10.361687 - 10.361687 0.1036 187. Azhikode South 10.481565 - 10.481565 0.1048 188. Kadankode 1.766004 - 1.766004 0.0177 189. Kattampally 9.887925 - 9.887925 0.0989 190. Azhikkal 1.121476 - 1.121476 0.0112 191. Valapattanam 15.31957 - 15.31957 0.1532 192. Azhikode North 4.190798 - 4.190798 0.0419 193. Pappinisseri 25.979863 - 25.979863 0.2598 194. Mattool 3.446462 - 3.446462 0.0345 195. Madakkara 13.620580 - 13.620580 0.1362 196. Thekkumbad 8.071152 7.236124 15.307276 0.1531 197. Cherukunnu 4.851336 5.422163 10.273499 0.1027 198. Muttil 10.70575 7.019283 17.725033 0.1773 199. Payil island 3.587666 - 3.587666 0.0359 200. Ezhome 22.18455 4.784542 26.969092 0.2697 201. Muthukuda 14.318986 - 14.318986 0.1432 202. Narikode 1.234545 - 1.234545 0.0123 203. Payyannur 21.965911 - 21.965911 0.2197 204. Kavvayi 15.211589 - 15.211589 0.1521 205. South Thrikkaripur 5.999580 13.119900 19.11948 0.1912 206. Peringadi 15.214815 - 15.214815 0.1521 207. Padannakkara 5.179541 - 5.179541 0.0518 208. Kariyad 1.1805628 - 1.1805628 0.0118 209. Punnol, New mahe 1.262873 - 1.262873 0.0126 210. Pallithazhe 1.620177 - 1.620177 0.0162 211. Keezhathoor 2.426456 - 2.426456 0.0242 212. Mavilayil 8.336698 2.854263 11.190961 0.1119 213. Kunhimangalam 28.5467864 - 28.5467864 0.2855 214. North Thrikkaripur 6.341315 - 6.341315 0.0634 215. Vellur 9.045433 - 9.045433 0.0905 216. Kannur 183.401864 86.429671 269.831535 2.6983 Total 602.927485 143.517745 746.445230 7.4645 Kasaragod District 217. Madakkal 1.18173 - 1.18173 0.0118 218. South Thrikkaripur 20.796795 4.865676 25.66247 0.2566 219. Edayilekkadu 3.520208 - 3.520208 0.0352 31 220. Thrikkaripur 0.133095 - 0.133095 0.0013 221. Padne 0.294753 - 0.294753 0.0029 222. Kokkal 0.815911 - 0.815911 0.0082 223. Udumbumthala 0.037283 - 0.037283 0.0004 224. kaithakkad 2.820422 - 2.820422 0.0282 225. Kanhangad 0.086232 - 0.086232 0.0009 226. Chithari 1.082473 - 1.082473 0.0108 227. Karakkunnu 0.327534 - 0.327534 0.0033 228. Alakkode 3.378275 - 3.378275 0.0338 229. Keezhur 3.127838 - 3.127838 0.0313 230. Kudlu - 1.262766 1.262766 0.0126 231. Mogral puthur 7.591862 - 7.591862 0.0759 232. Kumbla 44.520961 - 44.520961 0.4452 233. Arikady 8.490294 - 8.490294 0.0849 234. Shiriya 5.063362 - 5.063362 0.0506 235. Mangal pady - 0.954388 0.954388 0.0095 Total 103.269028 7.08283 110.351858 1.1035 Table 1.2. Extent of mangroves along different districts of Kerala Current extent Existing percentage (%) Sl. No District (km2) 1. Trivandrum 0.275 1.41 2. Kollam 0.530 2.71 3. Alappuzha 1.038 5.32 4. Kottayam 0.985 5.04 5. Ernakulam 6.153 31.50 6. Thrissur 0.407 2.08 7. Malappuram 0.367 1.88 8. Kozhikkode 1.207 6.18 9. Kannur 7.465 38.22 10. Kasaragod 1.104 5.65 Total 19.531 32 Data pertaining to the present status of mangroves in the 10 districts of Kerala revealed that, Trivandrum district occupy 0.275 km2 (1.41%) of mangrove population, which is inclusive of 0.151 km2 of homogeneous and 0.124 Km2 heterogeneous mangrove population. Of the 9 locations studied, Akkulam - Veli region occupied the largest mangrove area (0.126 km2) whereas, Vizhinjam has been noticed for least mangrove population (0.0002 km2). Mohanan (1997) reported a total of 15 ha of mangrove population in Trivandrum district, whereas Vidyasagaran and Madhusoodanan (2014) reported the existence of 0. 28km2. A significant increase in area has been noticed in the district compared to 1997. However, comparing the present data with latest reports (2014), a slight decrease in area has been noticed. The reason for this decline can be attributed to the enhanced land clearance activities at Vizhinjam, in connection with towards the construction of harbor. Mangrove areas of 0.530 km2 (2.71%), inclusive of 0.2711 km2 of mangrove patches and 0.2087 km2 of mixed patches are reported in Kollam district. Here, the highest mangrove area is reported from the Shakthikulangara region (0.226 km2) and the lowest area from Oachira (0.008 km2). Previous reports by Basha (1991) showed 0.58 km2 of mangrove patch in Kollam district. Thus, comparing earlier reports, a noticeable decline along the coastal plains of the district has been noticed. In the present study, the extent of mangrove areas in Alleppey district was estimated to be 1.038 km2 (5.32%) with 0.487 km2 of homogenous and 0.551 km2 of heterogeneous mangrove patches. Eramalloor and Perumpally have been noticed as the areas with higher and lower mangrove patches with 0.286 km2 and 0.0001 km2, respectively. Basha in 1991 reported a total of 0.90 km2 in the district. Upon comparing with the earlier reports, considerable increase in the total area of mangroves has been noticed. Similarly, Kottayam district occupied 0.985 km2 (5.04%) of mangrove areas with 0.565 km2 of homogeneous and 0.420 km2 of heterogeneous population. Among the 14 locations studied, Kumarakom has occupied maximum area with 0.308 km2 and Keezhukunnu with a lowest area of 0.007 km2. Previous reports revealed that the district of Kottayam occupied only 33 0.80 km2 of mangrove forests (Basha, 1991). Thus it can be concluded that upon comparing with previous reports, significant increase had happened to the total area of mangrove patches in Kottayam district. Ernakulam district has been noticed to occupy 6.153 km2 (31.50%) of mangrove areas, which are inclusive of 2.67 km2 of homogeneous and 4.27 km2 of heterogeneous patches. Puthuvypin occupied the largest stretch (1.02 km2), while Kandakkadavu reported the smallest (0.0005 km2). In 2014, Vidyasagaran and Madhusoodanan reported an extent of 6 km2 from the district. Upon comparing with the earlier reports it can be stated that, the total area of mangrove patches within Ernakulam district has grown further to show an increase of 0.153 km2. As Ernakulam is a fast developing district of the state, significant attention has been given for the conservation of its mangroves. Increased awareness on the importance of mangrove among people, especially those who live along the coastal region have contributed to the prevention of cutting of mangrove trees for recreational purposes. Also the interventions of some of the non-governmental organization have resulted in the establishment of local bodies to conserve and restore mangrove ecosystems. In the present survey, a total of 0.407 km2 (2.08%) mangrove forest has been identified from Thrissur district, including 0.332 km2 homogeneous and 0.076 km2 heterogeneous patches. Among different locations studied, Chettuvai reported the largest area (0.095 km2) and Chanda Nagar reported the smallest patch with 0.001 km2. Kurien et al. (1994) reported the existence of 0.41 km2 of mangroves in the district. A total of 0.30 km2 were reported by Vidyasagaran and Madhusoodanan in 2014. Thus upon comparing with reports of 1994, no significant change has been noticed in the total area of mangroves, whereas a marginal increase has been noticed as compared to the data published in 2014. A total area of 0.367 km2 (1.88%) mangrove habitats has been reported from the district of Malappuram. The homogeneous and heterogeneous patches reported were 0.329 km2 and 0.038 km2 respectively. Out of 17 locations studied, Kadalundi- Vallikkunnu region is reported for higher extent (0.104 km2) and Thavalakulam for lower (0.004 km2). Earlier report by Vidyasagaran and Madhusoodanan (2014) 34 recorded a total of 0.26 km2 mangrove forest from the district. Thus, compared to previous studies, the present study reported an increase of 0.10 km2 in the total mangrove cover of the district. The district of Kozhikode has been noticed for a total of 1.207 km2 (6.18%) mangrove forests including both homogeneous (1.044 km2) and heterogeneous (0.164 km2) patches. Mangrove areas of Sarovaram bio park, Kottooli occupied the largest area (0.171 km2) and Azhchavattam region occupied the smallest patch within the district. Mohanan in 1997 reported 2.0 km2 of mangrove areas from the district. Kannur district showed the existence of a total of 7.465 km2 (38.22%) mangrove cover, which is inclusive of 6.029 km2 homogeneous and 1.435 km2 heterogeneous patch. Among the numerous healthy patches, Kunhimangalam possesses the highest area of 0.286 km2 and Chalil with least area of 0.001 km2. Vaiga and Sincy (2016) reported 7.55 km2 of mangrove forest from the district. Upon comparing the present estimate with the recent report (2016), the total mangrove cover of the district has been dwindled by around 0.1 km2. The coastal population has grown as a result of increased returns from fishing. Land clearance for the construction of new sea ports, extension of existing sea ports and establishment of industrial units near the coast has also contributed to the depletion of mangrove cover in the district. Kasaragod district occupies a total area of 1.104 km2 (5.65%) of mangroves, with both homogeneous (1.033 km2) and heterogeneous (0.071 km2) patches. Kumbala has been reported for holding largest area of mangroves (0.445 km2) and Udumbumthala for a smallest patch with a size of 0.0004 km2. Mohanan (1997) reported 0.50 km2 of mangroves in the district. Upon comparing the data with previous reports, it can be stated that the mangrove cover of the district has considerably increased for about 0.604 km2. This might be due to the intense afforestation activities conducted both at government and non-government level. 35 The present survey estimates the total extent of mangroves in Kerala to a tune of 19.53 km2. It has also been highlighted that, out of 10 districts studied, Kannur district occupies maximum mangrove cover with 7.465 km2, which is coming around 38.22% of the total extent of the State. This is followed by Ernakulam district with 6.153 km2 (31.50%). Minimum extent was represented by Trivandrum district with 0.275 km2 (1.41%). In the present study, attempts have been carried out to compare the results with earlier authentic reports. The most reliable studies on the district wise and total extent of mangroves in Kerala has been carried out by Basha in 1991. He reported that the total mangrove cover of the State is 16.71 Km2. Upon comparing the present results with these reports (Basha, 1991), significant changes were noticed within 25 years with respect to the district wise and state wise extent of mangroves in Kerala. The observations concerning the extent of mangroves in the present study in comparison with earlier studies (Basha, 1991) is given in Table 1.3. Table 1.3. Mangrove cover changes in km2 Current extent Basha Changes between 1991 – 2016 (2016) (1991) (25 years) District km2 km2 km2 Trivandrum 0.275 0.23 +0.045 Kollam 0.530 0.58 -0.050 Alleppey 1.038 0.90 +0.138 Kottayam 0.985 0.80 +0.185 Ernakulam 6.153 2.60 +3.553 Thrissur 0.407 0.21 +0.197 Malappuram 0.367 0.12 +0.247 Kozhikode 1.207 2.93 -1.723 Kannur 7.465 7.55 -0.085 Kasaragod 1.104 0.79 +0.314 Total 19.531 16.71 +2.821 ‘+’ indicates increasing trend and ‘-’ indicates decreasing trend The results revealed that most of the districts are reported with increase in the total mangrove area. Trivandrum (+0.045 km2), Alleppey (+0.138 km2), Kottayam (+0.185 km2), Ernakulam (+3.553 km2), Thrissur (0.197 km2), Malappuram (+0.247 km2) and Kasaragod (+0.314 km2) districts have been reported for increase in the 36 total mangrove cover during last 25 years. The districts with decline in total mangrove cover during last 25 years were Kollam (-0.050 km2), Kozhikode (-1.723 km2) and Kannur (-0.085 km2). Thus, upon comparing the results of the present study with that of Basha (1991), an increasing mangrove cover of about 2.821 km2 within the last 25 years is noted. This increase might be due to an increase in awareness on the importance of mangroves among public. Also there were contributions from the part of governmental and non- governmental organizations. The incidence of Asian tsunami in 2004 and Hurricane Katrina in 2005 have also contributed towards the enhanced awareness on mangroves as their contribution in preventing coastal erosion and subsequent inundation was significant. Among all the districts under study, Kollam (-0.050 km2), Kozhikode (-1.723 km2) and Kannur (-0.085 km2) showed a decreasing trend of mangrove cover with respect to the report of Basha (1991). The study reveals that the mangroves in these districts have shrunken considerably to few patches, mainly in Dharmadom, Nadakkavu, Edakkad, Pappinisseri, Valapattanam, Muzhappilangad, Kunhimangalam, Pazhayangadi, Kavvayi, Thalassery and Ezhimala of Kannur district, Kottooli, Koduvally, Kallai and Kadalundi of Kozhikkode district and Asraamam and Shaktikulangara of Kollam district. The year wise declines in the total mangrove cover of these districts are 0.002 km2/yr, 0.069 km2/yr and 0.003 km2/yr respectively. High extent of degradation in the total mangrove cover has been noticed in Kozhikode district. The year wise mangrove declining rate of Kozhikode district is alarming, indicating the fact that the remaining mangrove patches will be degraded within the next 20 years. Along with the extent, diversity assessment of mangroves confining to Kerala has been worked out and reported. Field studies have been carried out in all the 10 districts for the collection and identification of mangrove species. Each district has been reported with different number of mangroves. The results are depicted in Table 1.4. 37 Table 1.4. Diversity of true mangrove species in different districts of Kerala Sl. No of No Species Family species 1. Trivandrum District 1. Aegiceras corniculatum (L.) Blanco Myrsinaceae 2. Avicennia officinalis L. Avicenniaceae 3. Bruguiera cylindrica (L.) Blume 4. Bruguiera gymnorhiza (L.) Savi. 10 species Rhizophoraceae 5. Rhizophora apiculata Blume under 7 6. Rhizophora mucronata Lam. genera and 6 7. Excoecaria agallocha L. families Euphorbiaceae 8. Excoecaria indica L. 9. Lumnitzera racemosa Willd. Combretaceae 10. Sonneratia caseolaris (L.)Engl. Sonneratiaceae 2. Kollam District 1. Aegiceras corniculatum (L.) Blanco Myrsinaceae 2. Avicennia marina (Forssk.) Vierh. Avicenniaceae 3. Avicennia officinalis L. 4. Bruguiera cylindrica (L.) Blume 5. Bruguiera gymnorhiza (L.) Savi. 6. Bruguiera sexangula (Lour.) Poir. 14 species 7. Ceriops tagal (Pers.) C. B. Rob. Rhizophoraceae under 9 8. Kandelia candel (L.) Druce genera and 6 9. Rhizophora apiculata Blume families 10. Rhizophora mucronata Lam. 11. Excoecaria agallocha L. Euphorbiaceae 12. Excoecaria indica L. 13. Lumnitzera racemosa Willd. Combretaceae 14. Sonneratia caseolaris (L.)Engl. Sonneratiaceae 3. Alleppey District 1. Aegiceras corniculatum (L.) Blanco Myrsinaceae 2. Avicennia marina (Forssk.) Vierh. Avicenniaceae 3. Avicennia officinalis L. 4. Bruguiera cylindrica (L.) Blume 10 species 5. Bruguiera gymnorhiza (L.) Savi. under 7 6. Kandelia candel (L.) Druce Rhizophoraceae genera and 5 7. Rhizophora apiculata Blume families 8. Rhizophora mucronata Lam. 9. Excoecaria agallocha L. Euphorbiaceae 10. Sonneratia caseolaris (L.)Engl. Sonneratiaceae 4. Kottayam District 1. Avicennia marina (Forssk.) Vierh. 7 species Avicenniaceae 2. Avicennia officinalis L. under 5 3. Bruguiera sexangula (Lour.) Poir. Rhizophoraceae genera and 4 38 4. Rhizophora apiculata Blume families 5. Rhizophora mucronata Lam. 6. Excoecaria agallocha L. Euphorbiaceae 7. Sonneratia caseolaris (L.)Engl. Sonneratiaceae 5. Ernakulam District 1. Aegiceras corniculatum (L.) Blanco Myrsinaceae 2. Avicennia marina (Forssk.) Vierh. Avicenniaceae 3. Avicennia officinalis L. 4. Bruguiera cylindrica (L.) Blume 11 species 5. Bruguiera gymnorhiza (L.) Savi. under 7 6. Kandelia candel (L.) Druce Rhizophoraceae genera and 5 7. Rhizophora apiculata Blume families 8. Rhizophora mucronata Lam. 9. Excoecaria agallocha L. Euphorbiaceae 10. Sonneratia alba Sm. Sonneratiaceae 11. Sonneratia caseolaris (L.)Engl. 6. Thrissur District 1. Aegiceras corniculatum (L.) Blanco Myrsinaceae 2. Avicennia officinalis L. Avicenniaceae 7 species 3. Bruguiera cylindrica (L.) Blume under 6 4. Kandelia candel (L.) Druce Rhizophoraceae genera and 4 5. Rhizophora apiculata Blume families 6. Rhizophora mucronata Lam. 7. Excoecaria agallocha L. Euphorbiaceae 7. Malappuram District 1. Aegiceras corniculatum (L.) Blanco Myrsinaceae 2. Avicennia marina (Forssk.) Vierh. Avicenniaceae 3. Avicennia officinalis L. 4. Bruguiera cylindrica (L.) Blume 10 species 5. Bruguiera sexangula (Lour.) Poir. under 7 Rhizophoraceae 6. Kandelia candel (L.) Druce genera and 5 7. Rhizophora mucronata Lam. families 8. Excoecaria agallocha L. Euphorbiaceae 9. Sonneratia alba Sm. Sonneratiaceae 10. Sonneratia caseolaris (L.)Engl. 8. Kozhikkode District 1. Aegiceras corniculatum (L.) Blanco Myrsinaceae 2. Avicennia marina (Forssk.) Vierh. Avicenniaceae 3. Avicennia officinalis L. 10 species 4. Bruguiera cylindrica (L.) Blume under 7 5. Kandelia candel (L.) Druce Rhizophoraceae genera and 5 6. Rhizophora apiculata Blume families 7. Rhizophora mucronata Lam. 8. Excoecaria agallocha L. Euphorbiaceae 9. Sonneratia alba Sm. Sonneratiaceae 39 10 Sonneratia caseolaris (L.)Engl. 9. Kannur District 1. Aegiceras corniculatum (L.) Blanco Myrsinaceae 2. Avicennia marina (Forssk.) Vierh. Avicenniaceae 3. Avicennia officinalis L. 4. Bruguiera cylindrica (L.) Blume 5. Bruguiera sexangula (Lour.) Poir. 12 species 6. Kandelia candel (L.) Druce Rhizophoraceae under 8 7. Rhizophora apiculata Blume genera and 6 8. Rhizophora mucronata Lam. families 9. Excoecaria agallocha L. Euphorbiaceae 10. Lumnitzera racemosa Willd. Combretaceae 11. Sonneratia alba Sm. Sonneratiaceae 12. Sonneratia caseolaris (L.)Engl. 10. Kasaragod District 1. Aegiceras corniculatum (L.) Blanco Myrsinaceae 2. Avicennia marina (Forssk.) Vierh. Avicenniaceae 3. Avicennia officinalis L. 4. Bruguiera cylindrica (L.) Blume 10 species 5. Kandelia candel (L.) Druce under Rhizophoraceae 6. Rhizophora apiculata Blume 7genera and 7. Rhizophora mucronata Lam. 5 families 8. Excoecaria agallocha L. Euphorbiaceae 9. Sonneratia alba Sm. Sonneratiaceae 10. Sonneratia caseolaris (L.)Engl. Trivandrum district possessed 10 true mangrove species, which include Aegiceras corniculatum, Avicennia officinalis, Bruguiera cylindrica, B. gymnorhiza, Excoecaria agallocha, E. indica, Lumnitzera racemosa, Rhizophora apiculata, R. mucronata and Sonneratia caseolaris. The number of species was found to be the same as reported by Mini et al. (2014). However, Thomas (1962) and Vidyasagaran and Madhusoodanan (2014) reported 5 and 4 species of mangroves respectively from the district. Upon comparing with earlier reports, the present study reported considerably higher number of mangrove species from the district. Kollam district has been reported with maximum species diversity of 14 true mangrove species. Species such as Aegiceras corniculatum, Avicennia marina, A. officinalis, B. sexangula, Excoecaria agallocha, E. indica, Kandelia candel, Lumnitzera racemosa, Rhizophora apiculata, R. mucronata and Sonneratia 40 caseolaris were scattered sporadically in different parts of the district. Vishal and Vidyasagaran (2014) have reported 12 true mangrove species from the district. The present result indicated an increase in the number of species. Alleppey district is reported with 10 mangrove species such as Aegiceras corniculatum, Avicennia marina, A. officinalis, Bruguiera cylindrica, B. gymnorhiza, Excoecaria agallocha, Kandelia candel, Rhizophora apiculata, R. mucronata and Sonneratia caseolaris. Sunil (2000), Vidyasagaran and Madhusoodanan (2014) and Mini et al. (2014) have reported 12 true mangrove species from the district. Comparison of the present result with these reports indicated a decline in the number of true mangrove species. 7 true mangrove species such as Avicennia marina, A. officinalis, B. sexangula, Excoecaria agallocha, Rhizophora apiculata, R. mucronata and S. caseolaris are sparsely distributed along different locations of Kottayam district. Marginal decline in the number of species has been noticed as compared to the reports revealed 8 species by Mini et al. (2014). However, as compared to the reports with 5 species of mangroves by Vidyasagaran and Madhusoodanan (2014), the present study described a higher number. True mangrove species such as Aegiceras corniculatum, Avicennia marina, A. officinalis, Bruguiera cylindrica, B. gymnorhiza, Excoecaria agallocha, Kandelia candel, Rhizophora apiculata, R. mucronata, Sonneratia alba and S. caseolaris were the 11 species distributed in the Ernakulam district. Upon comparing with the reports of Mini et al (2014), the present study described a lesser number of true mangrove species from the district. However, the study reported higher number of species as compared to the reports of Kurian (1984), Sunilkumar (1993) and Vidyasagaran and Madhusoodanan (2014). Thrissur district is characterized by 7 mangrove species such as Aegiceras corniculatum, Avicennia officinalis, Bruguiera cylindrica, Excoecaria agallocha, Kandelia candel, Rhizophora apiculata and R. mucronata. Considerable decline in the total number of true mangrove species has been noticed as compared to the reports (11 species) of Mini et al. (2014). 41 Malappuram district has been reported with 10 mangrove species such as Aegiceras corniculatum, Avicennia marina, A. officinalis, Bruguiera cylindrica, B. sexangula, Excoecaria agallocha, Kandelia candel, Rhizophora mucronata, Sonneratia alba and S. caseolaris. Radhakrishnan et al. (2006), Vidyasagaran et al. (2014) and Mini et al. (2014) reported 2, 8 and 9 species of true mangrove species from the district. As compared to all these reports, the present study reported a higher number of species. Kozhikkode district was also with 10 true mangrove species such as Aegiceras corniculatum, Avicennia marina, A. officinalis, Bruguiera cylindrica, Excoecaria agallocha, Kandelia candel, Rhizophora apiculata, R. mucronata, Sonneratia alba and S. caseolaris. Radhakrishnan et al. (2006) reported 7 and Vidyasagaran and Madhusoodanan (2014) reported 9 species of true mangroves from the district. The present result indicated that the species diversity confined to the district has increased. Kannur has been reported for a maximum of 12 true mangrove species such as Aegiceras corniculatum, Avicennia marina, A. officinalis, Bruguiera cylindrica, , B. sexangula, Excoecaria agallocha, Kandelia candel, Lumnitzera racemosa, Rhizophora apiculata, R. mucronata, Sonneratia alba and S. caseolaris. Radhakrishnan et al. (2006) and Vidyasagaran et al. (2014) reported 7 and 11 species of true mangrove species from the district. The present result revealed a higher number of species as compared to these reports and is similar to the reports of Mini et al. (2014). Kasaragod was reported with 10 true mangrove species such as Aegiceras corniculatum, Avicennia marina, A. officinalis, Bruguiera cylindrica, Excoecaria agallocha, Kandelia candel, Rhizophora apiculata, R. mucronata, Sonneratia alba and S. caseolaris. The study described similar number of species as compared to the reports of Vidyasagaran and Madhusoodanan (2014). However, as compared to the reports by Mini et al. (2014) with 12 species, the species diversity of the district has presently decreased. 42 Consolidation of the above observation revealed the existence of 15 true mangrove species falling under 9 genera and 6 families in the state of Kerala (Plate 1.1). The details regarding their scientific name, vernacular name (Malayalam), family and recent IUCN status are depicted in Table 1.5. Table 1.5. True mangrove species of Kerala identified in the present study Sl. Vernacular Name IUCN Scientific Name Family No (Malayalam) Category Aegiceras corniculatum 1. Pookandal Myrsinaceae LC (L.) Blanco Avicennia marina 2. Cheru uppatti Avicenniaceae LC (Forssk.) Vierh. 3. Avicennia officinalis L. Uppatti, Uppootti Avicenniaceae LC Bruguiera cylindrica 4. Kuttikandal Rhizophoraceae LC (L.) Blume Bruguiera gymnorhiza 5. Penakandal Rhizophoraceae LC (L.) Savi. Bruguiera sexangula 6. Swarnakandal Rhizophoraceae LC (Lour.) Poir. Ceriops tagal (Pers.) C. 7. Manjakandal Rhizophoraceae LC B. Rob. Excoecaria agallocha 8. Kannampotti, Kammatti Euphorbiaceae LC L. 9. Excoecaria indica L. Kandal Euphorbiaceae DD Kandelia candel (L.) Ezhuthanikandal, 10. Rhizophoraceae LC Druce Nallakandal Lumnitzera racemosa 11. Kadakandal Combretaceae LC Willd. Rhizophora apiculata 12. Vallikandal, Peekandal Rhizophoraceae LC Blume Rhizophora mucronata 13. Pranthankandal Rhizophoraceae LC Lam. 14. Sonneratia alba Sm. Nakshathrakandal Sonneratiaceae LC Sonneratia caseolaris 15. Chakkarakandal Sonneratiaceae LC (L.)Engl.  IUCN Red list of threatened species version 2017-2 (www.iucnredlist.org)  LC – Least Concern (A taxon is Least Concern when it has been evaluated against the criteria and does not qualify for critically endangered, 43 endangered, vulnerable or near threatened. Widespread and abundant taxa are included in this category).  DD – Data Deficient (Appropriate data on abundance and distribution are lacking). Inquiries on the true mangrove species of Kerala revealed that, the state is endowed with 15 True mangrove species as a whole. They are Aegiceras corniculatum, Avicennia marina, A. officinalis, Bruguiera cylindrica, B. gymnorhiza, B. sexangula, Ceriops tagal, Excoecaria agallocha, E. indica, Kandelia candel, Lumnitzera racemosa, Rhizophora apiculata, R. mucronata, Sonneratia alba and S. caseolaris belonging to the families Myrsinaceae, Avicenniaceae, Euphorbiaceae, Rhizophoraceae, Combretaceae and Sonneraceaceae. Among different families reported, Rhizophoraceae possesses the maximum number of species (7) followed by Avicenniaceae (2 species), Euphorbiaceae (2 species), Sonneraceaceae (2 species), Combretaceae (1 species) and Myrsinaceae (1 species). 14 mangrove species reported in this study are coming under Least Concern (LC) Category of IUCN. The species Excoecaria indica is coming under the Data deficient category. The study revealed that, even though the existing mangrove areas are highly localized, the species diversity of these mangroves confining to the coast of Kerala is comparatively rich. Though there is a technical increase in the extent of mangroves, most of the major mangrove growing areas are under drastic pressure. Various reasons have been identified during the present investigation and that can be summarized as follows. Invasion of mangrove areas by human population is one of the main reason, in which most of the mangrove areas has been removed either partially or completely for various purposes. Unscientific developmental activities like construction of concrete walls and other retaining structures around the mangrove areas or filling/ reclamation of these areas hinder the entry of tidal water into the mangrove areas and hamper its expansion. Over exploitation of mangrove resources like cutting of mangroves for fire wood, cattle feed, etc. by the local people, also damaged this fragile ecosystem. Removal of mud from the banks of backwaters by local people for household purposes together with plantation activities has also been noticed as 44 factors leading to threat on mangroves. Waste disposal also affected the mangroves to a large extent. The policies framed by the government to encourage tourism and other recreational activities in the coastal environments have also contributed adversely to the conservation of mangroves and other marine biodiversity. Above all, lack of awareness among the public regarding the importance of mangroves is a major problem associated with mangrove conservation and protection. Ezhimala- Kunhimangalam region is highly affected with fishing related activities, sand mining, coir retting etc. Valapattanam mangroves are pressurized by pollution from wastes like slaughter house, domestic sewage, carcasses of animals, reclamation and coconut husk retting. Encroachment and unscientific construction activities are the main reasons of destruction in Chetwai and Ashtamudi mangroves. Mangalavanam mangroves are stressed by land encroachment, pollution due to dumping of cement bags and other wastes. Cutting of mangrove trees for fuel wood and other construction activities, draining and filling of the areas are threats at Puthuvypin region. Significant measures have to be adopted for protecting / uplifting the mangrove habitats of Kerala. Special enforcement cell should be placed to take legal actions through the departments concerned for mangrove area protection. Identification of private owned mangrove areas through field surveys and their acquisition by the government has to be carried out for better protection. The developmental activities that are harmful to mangrove population should be subjected to regular examination by a joint committee involving panchayath authorities, local people representatives and scientists. Creation of awareness regarding the importance of mangroves and mangrove habitats need to be given top priority. Since the survival of this eco system is very important for the well-being of all coupled flora and fauna, intensive and extensive conservation and ecosystem reinstatement programmes should be undertaken without delay. Conservation of these worth preserving pieces of nature’s gift is highly insistent because tomorrow may be too late. 45 Summary and Conclusion Mangroves are one among the most productive and biologically important ecosystem on this planet, providing vital ecosystem goods and services. Besides all these imperative services provided, these fragile ecosystems are under tremendous pressure. It has been reported that Kerala coast once supported about 700 sq.km of mangroves and presently it has been dwindled to a considerable extent. Mangrove ecosystems are receiving increasing attention in Kerala, but still lack updated information on their diversity and extent for deriving strategic plans for conservation / afforestation. The present study has been carried out to assess the extent and diversity of mangrove ecosystems in the heterogeneous environments of Kerala with a view to conserve their existing habitats from further degradation. Thorough literature survey and frequent field visits were carried out to elucidate the extent and diversity of mangroves confining to the coastal environments of Kerala. GPS survey has been carried out and the total area under mangrove cover (both homogenous and heterogenous) was estimated in square kilometers using Google map imageries. For the assessment of species diversity, collection of the true mangrove species has also been carried out from all the districts under study. The collected species were identified with the help of standard manuals and experts. All the specimens were preserved for future reference. The present survey estimated the total extent of mangroves in Kerala as 19.531 km2. It has also been highlighted that out of 10 districts studied, Kannur district occupied highest mangrove cover with 7.465 km2 which is coming around 38.22 % of the total extent within the state. This is followed by Ernakulam district with 6.153 km2 (31.5%). Minimum extent has been reported from Trivandrum district with 0.275 Km2 (1.41%). Attempts have been carried out to compare the results with earlier authentic reports. Upon comparing the results of the present study with that of Basha (1991), an increasing mangrove cover of about 2.821 km2 within the last 25 years is noted. This 46 increase might be due to an increase in awareness on the importance of mangroves among public. Also there were contributions from the part of governmental and non- governmental organizations in the area of mangrove introduction. The incidence of Asian tsunami in 2004 and Hurricane Katrina in 2005 have also contributed towards the enhanced awareness on mangroves as their contribution in preventing coastal erosion and subsequent inundation was significant. Most of the districts are reported with increase in the total mangrove area. Trivandrum (0.045 km2), Alleppey (0.138 km2), Kottayam (0.185 km2), Ernakulam (3.553 km2), Thrissur (0.197 km2), Malappuram (0.247 km2) and Kasaragod (0.314 km2) districts have been reported for increase in the total mangrove cover during last 25 years. The districts with decline in total mangrove cover during last 25 years were Kollam (0.050 km2), Kozhikode (1.723 km2) and Kannur (0.085 km2). Among all the districts under study, Kollam, Kozhikode and Kannur showed a decreasing trend of mangrove cover with respect to the report of Basha (1991). The year wise decline in the total mangrove cover of these districts are 0.002 km2/yr, 0.069 km2/yr and 0.003 km2/yr respectively. High extent of degradation in the total mangrove cover has been noticed in Kozhikode district. The year wise mangrove declining rate of Kozhikode district is alarming, indicating the fact that the remaining mangrove patches will be degraded within the next 20 years. Attempts were also carried out to study the diversity of true mangrove species in Kerala. Mangrove specimens were collected and identified following standard manuals and with the help of experts. The results revealed that, the state is endowed with 15 True mangrove species as a whole. They are Aegiceras corniculatum, Avicennia marina, Avicennia officinalis, Bruguiera cylindrica, B. gymnorhiza, B. sexangula, Ceriops tagal, Excoecaria agallocha, E. indica, Kandelia candel, Lumnitzera racemosa, Rhizophora apiculata, R. mucronata, Sonneratia alba and S. caseolaris under the families Myrsinaceae, Avicenniaceae, Euphorbiaceae, Rhizophoraceae, Combretaceae and Sonneraceaceae. Among different families reported, Rhizophoraceae possesses the maximum number of species (7) followed by Avicenniaceae (2 species), Euphorbiaceae (2 species), Sonneraceaceae (2 47 species), Combretaceae (1 species) and Myrsinaceae (1 species). The study revealed that, even though the existing mangrove areas are highly localized, the species diversity is comparatively rich. The study concluded that, though there is a technical increase in the extent of mangroves, drastic degradation have been undergoing in many of the urbanized and semi urbanized areas especially in Kozhikode and Kannur districts. The study also suggested that, if this unsystematic destruction proceeds unchecked, the mangrove patches may completely wiped out within few years. Since the survival of this eco system is very important for the well being of all coupled flora and fauna, intensive and extensive conservation and ecosystem reinstatement programmes should be undertaken without delay. Conservation of these worth preserving pieces of nature’s gift is highly insistent because tomorrow may be too late. 48 CHAPTER 2 STANDARDIZATION STUDIES ON THE GROWTH SUSTAINING ATTRIBUTES OF SELECTED MANGROVE SPECIES Introduction Mangrove forests play a very important role in coastal ecosystems located at the interface between land and sea along tropical and subtropical regions of the world. Such transition zones are influenced by waves, tides and thereby varying levels of environmental conditions. Many factors that strongly influence the establishment of mangroves in heterogeneous habitats, which include geographical features, wave action, tide action, rainfall, freshwater runoff, erosion/sedimentation rates, aridity, salinity, nutrient inputs, soil/ sediment quality etc. (Kjerfve et al., l999). Waves, tides and rainfall affect water circulation by generating turbulence, longitudinal mixing and trapping of coastal water, influencing the rate of erosion and deposition of sediments on which mangroves grow (Duke et al., 1998). Morphological and ecophysiological characteristics and adaptations of mangrove trees include aerial roots, viviparous embryos, tidal dispersal of propagules, rapid rates of canopy production, frequent absence of an understorey, absence of growth rings, wood with narrow, densely distributed vessels, highly efficient nutrient retention mechanisms, and the ability to cope with salt and to maintain water and carbon balance. Subtle variations in key environmental factors have resulted in further adaptations not only among species, but also between individuals of the same species living in different conditions. Differences in climate, geomorphology, hydrodynamic disturbances and sedimentation regime have created differential incentives for root characteristics such as strength, retention of oxygen, nutrient acquisition, and resilience to sedimentation. 49 All mangrove plant species do not have the same ability to tolerate soil salinity, nutrient, wave energy and flooding (anaerobic) conditions that vary within as well as among mangrove areas. Depending on the water and soil nutrient conditions and also the extent to which the area is protected from high energy waves; mangrove species occupy different localities in an inter-tidal area, forming diverse zones of vegetation. Each zone is composed of either one or a few species of mangroves that can tolerate its environmental conditions. Knowledge on mangrove zonation therefore is essential to determine suitable candidate species for planting. Several studies have been conducted to elucidate the nutrient enrichment of mangrove wetlands. Salinity of water and soil organic matter has been reported to have the most significant influence on the proliferation of mangroves (Clough, l984; Kathiresan and Thangam, 1990). Salinity plays a pivotal role in the species distribution, productivity and growth of mangrove forests (Twilley and Chen, 1998). Changes in salinity are normally controlled by climate, hydrology, rainfall, topography and tidal flooding. Most of the mangroves prefer brackish to saline waters for their growth. Freshwater discharge or terrestrial runoff, on the other hand, greatly favors mangrove colonization; it supplies nutrients and leaches the soil, thus keeping soil salinity within a tolerable range (Thom, 1967). It has been reported that, establishment of mangrove forests are more abundant along areas wherein a lower salinity persists (Kathiresan et al., 1996). At conditions of higher salinity, mangroves spend more energy to maintain water balance and ion concentration rather than for primary production and growth (Clough, l984). Reports also shows that mangroves can tolerate salinities of higher ranges than any other plants. Different species of mangroves are reported to grow in a wider range of salinity conditions and there have been variations within the same genus. Salinity tolerances of some species of mangroves reported are Rhizophora mucronata (30ppm), R. apiculata (15 ppm), Sonneratia alba (2 -18 ppm) and S. lanceolata (2 ppm) (Ball and Pidsley, 1995; Kathiresan et al., 1996). 50 Mangrove plants may grow in different types of soils; therefore their vegetation, species composition and structure may vary considerably at the global, regional and local scales (Vilarrubia, 2000). The ecosystem showed analogous patterns of variability in the sources of organic carbon in surface sediments. The sedimentary organic matter depends on factors like algal mats, roots, tidal fluctuations, rate of change in decomposition and the maturity of the forest (Middelburg et al., 1997). Root systems of some species are probably better as anchorage while those of others are better as means to acquire nutrients from the sediment, or oxygen from the air. For instance, stilt or prop roots of Rhizophora offer support to tall trees to withstand the forces of strong winds (Field, 1995). Some mangrove species are able to respond to inundation or sedimentation. The stilt roots of Rhizophora are capable of elongating up to eight meters (Santisuk 1983). From the observation of Aksornkoae (1975), it was found that the height of aerial roots of Rhizophora in a high tidal area was greater than that in a short tidal area. Additionally, pneumatophores of Avicennia have limited height of less than 30 cm and develop little secondary thickening. In the case of Sonneratia, the pneumatophores are taller because they have a much longer period of development and the highest length ever found was three meters (Tomlinson 1986). Therefore, Avicennia trees are not likely to survive under abrupt sediment accretion of more than 30 cm. The uncontrolled exploitation and degradation of mangroves in most of the tropical countries have called for an urgent need of implementing conservation and management strategies. Mangrove conservation requires a collaborated research involving natural, social and inter-disciplinary approaches. Afforestation of mangroves seems to be a promising solution for the restoration of degraded habitats. Selection of ideal and adaptable species is the most vital prerequisite towards successful afforestation/ restoration of mangroves. Different criteria followed for the selection of an ideal species for afforestation activities are; planting purpose, adaptability, occurrence, availability of mature propagules, size of propagules and zoning pattern of species (Macintosh et al., 2012). The following criteria are also followed for the selection of mangrove species. (i) Regeneration of mangroves (ii) 51 coastal protection against tidal waters, erosion and cyclones (iii) protection of lagoons and estuaries (iv) dyke protection along the sea and aquaculture farms and (v) introduction to new mudflats. According to Kathiresan (1994, 2011), among the Kerala mangroves, Aegiceras corniculatum can be used for regeneration of mangroves and introduction to new mudflats. Avicennia officinalis and Avicennia marina are known to satisfy all the above criteria. Bruguiera cylindrica can be utilized for the purpose of protection of lagoons and estuaries whereas; Bruguiera gymnorhiza and Ceriops tagal can be used for dyke protection along the sea and aquaculture farms. Excoecaria agallocha can be introduced for regeneration of mangroves and dyke protection along the sea and aquaculture farms. Kandelia candel can be included in the afforestation practices of coastal protection against tidal waters, erosion and cyclones and protection of lagoons and estuaries. Rhizophora apiculata and R. mucronata satisfies all the planting purposes except regeneration of mangroves. Sonneratia alba can be used for coastal protection against tidal waters, erosion and cyclones and protection of lagoons and estuaries. S. caseolaris can be included in protection of lagoons and estuaries and dyke protection along the sea and aquaculture farms. It is evident from the literature that, the growth conditions of mangroves differs in heterogeneous habitats. Also the selection of mangroves to specific habitats is dependent on their ecosystem services. Basically, any afforestation or restoration endeavors of mangroves primarily require reliable information on ecology, hydrology and sedimentology that control the successful growth of the targeted mangrove species. Thus, it can be stated that among all such vital attributes, water and sediment quality are known to have supreme influence on the growth of mangroves (Thom, 1967). In light of this, the present investigation was carried out with the objective of evaluating the hydrogeochemical, sedimentological and climatological conditions ideal for the growth and establishment of selected mangrove species in pursuit of their utilization for species specific afforestation practices. 52 Review of Literature Among various inputs, water and sediment are known to have supreme influence on the growth and development of mangroves. On regional and global level, many studies have been reported on the growth supporting attributes of mangroves. Soil characteristics and vegetation of mangrove forest of Sunderban in India has been reported by Frith et al. (1976). The results revealed that the pH of soil was fluctuating within acidic to alkaline range. Studies on the ecology of estuarine mangroves of Goa revealed nutrients, especially inorganic phosphate, exhibiting an inverse correlation with sediment load (Untawale and Parulakar, 1976). Studies pertaining to the physico-chemical attributes of soil from mangrove ecosystems of Sunderban forest revealed that pH is an important determinant of mangrove proliferation. It has also been reported that the soil pH of the ecosystem was ranging from 7.9 to 8.4 (Matilal, 1986). Influence of temperature, salinity, sediment nitrogen, phosphorous and potassium on rooting of Rhizophora mucronata was studied and reported by Kathiresan et al (1996). The results revealed that, temperature and salinity were maximum during summer and minimum during monsoon months. The sediment nitrogen, phosphorous and potassium were noticed to be higher during pre monsoon and lower during monsoon months. Monthly assessment of the physico-chemical characteristics of the water in Muthupettai mangrove ecosystem were carried out for a period of 2 years. The ranges of different parameters such as air temperature (27-35°C), surface water temperature (26-33°C), salinity (20-38‰), pH (7.1 to 8.7), dissolved oxygen (3.1 to 6.35 mg L-1), nitrate-NO (15 to 14.17 μM), nitrite-N (0.09 to 3.58 μM), silicate-Si (0.6 to -19.86 μM), phosphate-P (0.07 to 10.3 μM) and particulate organic carbon (1.46 to 85.43 mg/l) were reported (Paramasivam and Kannan, 2005). Assessment of the physico-chemical and biological characteristics of the mangrove waters, south of Chennai has been carried out and reported. The ranges of various 53 parameters studied were water temperature (22 to 33°C), salinity (2 to 29.5%), dissolved oxygen (3.8 to 8.2 mg/l), pH (7.2 to 9.2), nitrate (9.2 to 27.3 pM) and inorganic phosphate (1.6 to 28.9 pM). The study concluded that seasonal mean values of most of the parameters recorded at both the stations were found to be high during the summer and low during the monsoon season (Ajith Kumar et al., 2006). Physicochemical attributes of soil along the mangrove habitats of Andaman islands have been reported. The range of various parameters reported was pH (4.1 to 6.7), organic carbon (14.1 to 24.6 mg/g), clay (19 to 27 %) and total nitrogen (2.01 to 2.81 mg/g). The range of various elements such as Potassium (1.12 to 1.35 Cmol/ kg), Calcium (6.7 to 7.9 Cmol/ kg), Magnesium (3.2 to 3.8 Cmol/ kg) and Sodium (8.2 to 12.7 Cmol/ kg) have also been reported (Ghoshal et al., 2009). Studies have been conducted to evaluate the seasonal variations in physico-chemical characteristics of Pichavaram mangroves, southeast coast of India. Attributes such as temperature, salinity, pH, dissolved oxygen and nutrients like nitrate, nitrite, inorganic phosphate and reactive silicate have been assessed from various sites within the habitat for a period of 2 years. The ranges of all the parameters reported were surface water temperatures (26 to 37oC), salinity (3.0 to 33.0%), dissolved oxygen (2.4 to 5.0 mg/l), nitrates (9.50 to 32.12 mM) and phosphates (0.73 to 2.36 mM). The role of various parameters studied on the proliferation of mangroves has also been discussed (Ashok Prabhu et al., 2008). Both water and sediment in arid zone mangroves of Kachchh-Gujarat have been subjected to physico-chemical characterization for a period of one year to elucidate their seasonal variations (Saravanakumar et al., 2008). Variation among almost all the attributes studied has been noticed. Surface water temperatures (17 to 370C), sediment temperatures (18.4 to 370 C), salinity (34.0 to 44 ppm), and the pH in water and sediment ranged between 7.0 and 8.9 and 6.29 and 8.45 respectively. The ranges of other nutrients reported were nitrate (0.23 to 7.26 microM), nitrite (0.04 to 0.87 microM), phosphate (0.13 to 3.12 microM) and reactive silicate (4.23 to 19.02 microM), total organic carbon (0.29% to 2.56%), total inorganic phosphorus (0.12 mg/g to 1.97 mg/g) and total nitrogen (0.02 mg/g to 1.95 mg/g). All the three 54 stations studied were reported for sediment texture, which ranged in terms of % of sand, clay and silt as 0.26 to 19.2; 7.6 to 47 and 47 to 87.4 % respectively. The texture triangle studies have revealed that the nature of soil in all the locations studied were silty loam, silty clay and silty clay loam (Saravanakumar et al., 2008). Studies were carried out to assess the seasonal variations in physico-chemical attributes of water and sediment samples from Pondicherry mangroves along southeast coast of India (Satheeshkumar and Anisa Khan, 2009). The range of various attributes reported were atmospheric and surface water temperatures (17.9 to 41.7 and 16.66 to 37.91 respectively), annual rainfall and relative humidity (1.1 to 808 mm and 37 to 100% respectively), salinity (6.36 to 36.77ppt), dissolved oxygen (3.45 to 5.49 mg/l), pH (7.11 to 8.52), electrical conductivity (26.65 to 52 ms ), sulphide (2.76 to 47.16 mg/l), soil parameters such as sand (63.69 to 87.31%), silt (9.89 to 29.32 %), clay (3.06 to 17.98 %) and organic matter (0.94 to 3.94 %). Positive correlation has been noticed between growth of mangroves and attributes like pH, temperature, salinity, sand, silt, clay and organic matter (Satheeshkumar and Anisa Khan, 2009). Krishna Mohan et al. (2012) studied the water quality of Bhavanapadu mangrove habitats of north coastal Andhra Pradesh. Samples were collected from three locations in the post monsoon season to elucidate various physico-chemical parameters of water. The result revealed that, there have been considerable variations in the parameters such as pH, EC and TDS and nutrients like NO3 and PO4. Yang et al. (2013) reported the response of mangroves to sedimentary patterns in the mangrove habitats of north Island of New Zealand. Vegetation and sediment characteristics were studied across seasons for a period of one year. Low ranges of pH were reported from all the locations. The ranges of total organic carbon of the sediments were reported to be higher from all the sites. The study also reported that the two parameters determined the growth of mangroves. Rahman et al. (2013) reported the quality parameter of water within the world’s largest mangrove forest located at Sundarbans, Bangladesh. The ranges of the 55 important water quality attributes reported were dissolved oxygen (6.0 to 7.33 mg/l), TSS (10.8 to 19.7 g/l), TDS (3.5 to 53.3 g/l), chloride (12.5 to 4672 mg/l), sulphate (9.02 to 968.3 mg/l), magnesium (4.86 to 583.2 mg/l), sodium (329 to 8839 mg/l) and potassium (45.15 to 992.0 mg/l). The study as a whole reported that the water quality parameters of the river were acceptable for the growth of mangroves during rainy season. However, moderate to high values of these parameters appeared for winter and summer seasons were not found to influence the growth of mangroves (Rahman et al., 2013). Diverse mangrove habitats along the southeast coast of India have been subjected to studies pertaining to various physico-chemical parameters. Assessment of temperature, pH, salinity, dissolved oxygen and nutrients, that can influence the growth of mangrove species were worked out. The ranges of some of the important attributes reported were atmospheric temperature 25.0 to 29.9°C, water temperature 26.0 to 30.2°C, salinity 24.0 to 34.0 ppt, water pH 7.4 to 8.2, turbidity 43.0 to 260.0 NTU, TDS 82.0 to 522.0 mg/l, total phosphorus 1.32 to 2.893 μmol/l and total nitrogen 5.123 to 38.916 μmol/l (Srilatha et al., 2013). Distribution status of nutrients on a seasonal basis has been studied at the Rupsha- Passur tidal river system of the Sundarbans mangrove forest, Bangladesh. Different ranges of parameters such as nitrate, phosphate, sulphate have been reported. Sulphate was coming in the range 7.301 to 126.92 mg/l. Likewise, phosphate (0.314 to 1.347 mg/l) and nitrate (0.083 and 1.233 mg/l) were also fluctuated. The study also reported that semidiurnal tidal activity has resulted in daily fluctuations in nutrient concentrations and other physicochemical properties of water (Rahaman et al., 2014). Studies have been carried out to evaluate the hydrogeochemical attributes on mangrove forests at Pichavaram, South India. Water samples were collected during pre-monsoon and post-monsoon seasons to evaluate the role of rain and seawater in the hydro-geochemical processes. To define the variations and the genetic origin of chemical parameters of water in mangrove ecosystem, geochemical model, WATEQ4F involving Piper diagram and multivariate statistical methods of data 56 analysis were jointly used. Grouping of waters on the Piper diagram showed a common composition and origin. Further results revealed that pre and post monsoon samples mainly contained Na–Cl and Ca–Cl water type, indicating a significant contribution of cations and anions from terrestrial and marine inputs in the mangrove ecosystem (Kumar et al., 2015). Studies pertaining to the physico-chemical attributes of water within the east Godavari mangrove ecosystem, Andhra Pradesh have been carried out and reported. Monthly analysis of influential water quality parameters were analyzed for a period of two years. The results revealed the ranges of all parameters studied, such as temperature (26 to 33.80C), pH (7.15 to 8.5), salinity (0 to 24 ppt), dissolved oxygen (4 to 7.8 mg/l), ammonia (0.05 to 1.2 mg/l), alkalinity (80 to 340 mg/l), nitrite (0.01 to 1mg/l), hardness (110 to 3500 mg/l), calcium (80 to 250 mg/l) and magnesium (180 to 450 mg/l) (Jarugulla and Krishna, 2017). Restoration of mangroves are greatly depend on physico-chemical properties of sediments and it also mediates the nutrient recycling. Sahoo et al. (2017) studied the physico-chemical parameters of sediment in the mangrove habitats of Odisha, India. Sediment samples were collected from 5 locations and analyzed. The ranges of some of the important sediment characters reported were pH (4.32 to 8.77), salinity (0.39 to 4.63 PSU) and organic carbon (6.7 to 51.86 mg/g). In Kerala, several studies have been conducted to elucidate the role of various physico chemical attributes of water and sediment on the growth of mangroves. Physico - chemical characteristics of Cochin backwaters and its implications on the growth of mangroves have been reported by Sreedharan and Salih (1974). Seasonal variation in the hydrographic conditions of mangrove areas of Cochin backwaters have been reported by Balakrishnan and Shynamma (1976). Chapman (1977) reported the role of temperature as an important determinant of growth and proliferation of different mangrove species. The extreme high levels of organic carbon, phosphorus and nitrogen from the sediment of Cochin back waters and their positive impact on the establishment of mangroves have been reported (Sankaranarayanan et al., 1979). 57 Studies have been carried out to evaluate the physico - chemical parameters of mangrove habitats from the backwaters of Thrissur district. Among different sites, all the parameters were noticed to be fluctuating during different seasons. The range of various parameters reported were pH (7.03 to 7.34), temperature (25 to 310C) and total hardness (30 to 52 mg/ l). The ranges of salinity during pre monsoon and monsoon seasons were 19.88 to 31.24 ppt and 19.88 to 28.4 ppt respectively (Saritha and Tessy, 2011). Detailed study on the mangrove ecosystems of Kerala with respect to their water quality parameters has been conducted and reported. Seasonality based collection of water has been carried out from 5 natural habitats of mangroves. The mean values of all the parameters studied with respect to pre monsoon, monsoon and post monsoon seasons were pH (7.20 to 8, 7.81 to 8.05 and 7.1 to 7.4), salinity (29.31 to 35.97 psu, 0.24 to 26.64 psu and 4.26 to 9.25 ppt ), alkalinity (121.25 to 167.33 mg/l, 22.31 to 83.42 mg/l and 44.55 to 79.20 mg/l), total nitrogen (10.26 to 102.78 μM, 124.78 to 188.38 μM and 34.55 to 63.69 μM), total phosphorous (1.53 to 6.65 μM, 10.04 to 22.88 μM and 2.96 to 8.61 μM), calcium (148.37 to 453.13 mg/l, 8.02 to 108.27 mg/l and 21.78 to 172.51 mg/l), magnesium (616.65 to 1362.8 mg/l, 8.63 to 621.09 mg/l and 65.44 to 540.23 mg/l), sodium (4000 to 7400 mg/l, 50 to 2600 mg/l and 434 to 2523 mg/l), potassium (160 to 320 mg/l, 3.3 to 130 mg/l and 18 to 105 mg/l ) and sulphate (1700 to 4166.67 mg/l, 12 to 966.67 mg/l and 235.24 to 1086.5 mg/l). The study reported that the five locations showed variations with respect to different water quality parameters, which has resulted in changes in mangrove cover and its diversity (Manju et al, 2012). Physico- chemical characterization of water samples from the Ayiramthengu mangrove habitats of Kollam district has been carried out and reported. The results revealed that pH of soil ranged from slight to strong acidic (5.4 to 6.1), EC from 1.72 to 2.14 mS/m. Slight difference in temperature among the sites has also been noticed. Slightly alkaline, high DO, medium hardness and highly saline water, along with other components of a typical mangrove ecosystem has also been reported (Praseetha and Rajani, 2015). 58 Growth sustaining conditions of mangrove species along selected shoreline environments of Malappuram district, Kerala has been worked out and reported. Both water and sediment samples were estimated for their physico chemical attributes. Accordingly, tolerance limit of various water and sediment quality attributes towards the growth of mangrove species were estimated (Shilna et al., 2016). Though studies have been carried out globally and nationally on the physico chemical aspects of marine, estuarine and back water sediment and water samples on the growth of mangroves, there is a paucity of information on the physico chemical characteristics of growth sustaining conditions from the mangrove ecosystems of Kerala. Also there is a dearth of information on the specific growth requirements of selected mangrove species from the coastal environments of Kerala. In this light, an attempt has been carried out to assess the growth requirements of selected mangrove species and to assess the key factors responsible for their growth and establishment in heterogeneous coastal environments of Kerala. Such information is likely to give way for the conservation and management of existing mangrove habitats of Kerala and also to formulate strategies for their introduction in ideal environments falling in the coastal stretch of Kerala. Materials and Methods Successful restoration/afforestation practices of mangroves require reliable information on their growth supporting conditions. The present study has been carried out to evaluate various geo environmental and climatological parameters responsible for the growth of selected mangrove species. Evaluation of the physico- chemical characteristics of water and soil / sediment along with climatological attributes associated with specific mangrove species were worked out monthly for a period of one year for deriving conclusions regarding their growth requirements. The details regarding mangrove species, study area, sampling of specimens and methods of analysis are summarized in the following sessions. 59 Heterogeneous natural habitats confining to the coastal environments of Kerala have been selected for assessing the growth sustaining conditions of 5 true mangrove species; Avicennia officinalis, Bruguiera cylindrica, Excoecaria agallocha, Rhizophora mucronata and Sonneratia alba. Three sampling sites have been fixed for each mangrove species at varying locations (Figure 2.1). The physico chemical characteristics of sediment and water samples from three heterogeneous locations were monitored monthly for each mangrove species for a period of one year. The details of mangrove species selected and habitats monitored are given in Table 2.1. Table 2.1. Study sites for selected mangrove species. Sl. Location District Latitude Longitude No: (i) Avicennia officinalis S1. Kumbalam Ernakulam 9⁰54'15.68"N 76⁰18'46.59"E S2. Kadalundi Malappuram 11⁰07'42.49"N 75⁰49'53.31"E S3. Thekkumbad Kannur 11⁰58'00.10"N 75⁰17'49.27"E (ii) Bruguiera cylindrica S4 Ayiramthengu Kollam 9⁰07'28.93"N 76⁰28'39.18"E S5 Kadalundi Malappuram 11⁰07'53.40"N 75⁰49'45.79"E S6 Thekkumbad Kannur 11⁰58'00.12"N 75⁰17'50.14"E (iii) Excoecaria agallocha S7 Ayiramthengu Kollam 9⁰07'28.71"N 76⁰28'38.89"E S8 Kumbalam Ernakulam 9⁰54'15.02"N 76⁰18'45.49"E S9 Thekkumbad Kannur 11⁰58'00.71"N 75⁰17'49.79"E (iv) Rhizophora mucronata S10 Ayiramthengu Kollam 9⁰07'28.74"N 76⁰28'39.44"E S11 Kumbalam Ernakulam 9⁰54'22.16"N 76⁰18'42.21"E S12 Thekkumbad Kannur 11⁰58'02.87"N 75⁰17'45.38"E (v) Sonneratia alba S13 Kadalundi 1 Malappuram 11⁰07'35.14"N 75⁰49'51.77"E S14 Kadalundi 2 Malappuram 11⁰07'35.42"N 75⁰49'50.72"E S15 Thekkumbad Kannur 11⁰58'04.32"N 75⁰17'45.38"E Details of mangrove species selected are as follows: 60 a) Avicennia officinalis L. (Avicenniaceae) Avicennia officinalis (Plate 2.1) is a fast growing shrub / tree, mostly found in the lower intertidal estuarine zones. It is a shade intolerant species, grows on soft, recently consolidated mud banks; with a maximum pore water salinity tolerance limit that of hypersaline conditions (Tomlinson, 1986). Habit: Greatly branched, medium sized, evergreen trees to 10 m high, with occasional stilt roots; radial cable roots producing numerous pneumatophores which are whitish brown in color; brownish grey or whitish grey smooth stem barks, pale brown or pale green colored terate and glabrous twigs with conspicuous and swollen nodes. Leaves: Simple and exstipulate leaves possess pale - green petiole with deep basal groove which are covered with dark or black marginal hairs. Opposite and decussate, 3- 10 x 2.5 – 5 cm, ovate, broadly elliptic - obovate, cuneate at base and obtuse at apex, glabrous above, silvery white tomentose beneath, coriaceous shiny green above; midrib prominent beneath with inconspicuous lateral veins. Inflorescence: Terminal or axillary compound spikes in which flowers are decussately arranged in dense capitates units, each with 10 – 12 flowers; fragrant, sessile, bisexual and slightly zygomorphic flowers; bracts and bracteoles persistent in the fruit; Brownish green persistent calyx, 5 unequal sepals with slight union at base; Gamopetalous corolla with thick, fleshy yellow petals fused basically to form a tube, glabrous within and dense silvery pubescent outside. Epipetalous stamens, as many as and alternating with corolla lobes, very short filaments fused basically with corolla lobes; basifixed, bilobed, longitudinally dehiscing anthers; superior ovary, imperfectly locular with 4 ovules which are pendulous. Fruit: Grayish green or yellowish green mango shaped fruit with persistent bract, bracteoles and calyx. Broad, flattened and apex pointed with persistent stylar beak. One seeded; seed shows incipient vivipary. (Mature capsule open by two valves, releasing the propagule on to the ground and the propagule develop into young plant within a few days). 61 Flowering and Fruiting: April – November. The present study monitored three natural habitats of Avicennia officinalis falling in the coastal stretch of Kerala, such as Kumbalam 1 of Ernakulam district (9⁰54'15.68"N: 76⁰18'46.59"E), Kadalundi 1 of Malappuram district (11⁰07'42.49"N: 75⁰49'53.31"E) and Thekkumbad 1 of Kannur district (11⁰58'00.10"N: 75⁰17'49.27"E). b) Bruguiera cylindrica (L.) Blume (Rhizophoraceae) Bruguiera cylindrica (Plate 2.2) is a shade tolerant species (Robertson and Alongi, 1992), found in the downstream and intermediate estuarine zones of mid-intertidal region. The species is widespread and common within its range including some marine and coastal protected areas. Habit: Greatly branched, medium sized to tall evergreen trees to 6m high, with occasionally buttressed stem base, underground cable roots producing numerous knee roots; greyish, lenticellate, cracked smooth stem barks; bronze or occasionally green colored terate and glabrous twigs with conspicuous nodes and stipular scars. Leaves: 4 – 13 x 2 – 5.5 cm, simple, stipulate, petiolate, opposite and decussate leaves possess two reddish colored overlapping stipules and reddish colored, terate petiole; elliptic to elliptic oblong or ovate- lanceolate, cuneate at base and acute at apex, reddish green colored above, pale green beneath; prominent midrib beneath with inconspicuous lateral veins. Inflorescence: Unbranched three flowered axillary cyme, rarely cyme branched to form upto six flowers, with sessile flowers usually; inconspicuous bracts and connate bracteoles form a stubby ring on which the flowers rest; greenish white calyx with basally fused sepals form prominent calyx tubes, which are smooth, glabrous and enclosing the ovary, calyx lobes are fleshy and persistent in fruit. Petals are as many as and alternating with the calyx lobes, free, shortly stalked, white colored, turning brown after anthesis and these longitudinally folded petals enclosing a pair of stamens. Stamens double the number of petals and free, but seen 62 in groups of two. Each group of stamens possesses filaments of unequal length. Anthers are basifixed, long, mucronata and bilobed, dehiscing longitudinally. Ovary is semi inferior with 2 locules, the ovules in each locule is 2 with pendulous placentation. Fruit: Drupe; Ovoid in shape with reddish green, glabrous, persistent calyx lobes reflects at maturity. One seeded; seed exhibiting vivipary. (Mature viviparous seedlings fall on the ground and develop into a young plant within a few days). Flowering and Fruiting: December – October. The present investigation focused on three natural habitats of Bruguiera cylindrica, which include Ayiramthengu 1 of Kollam district (9007'28.93"N: 76028'39.18"E), Kadalundi 2 of Malappuram district (11⁰07'53.40"N: 75⁰49'45.79"E) and Thekkumbad 2 of Kannur district (11⁰58'00.12"N: 75⁰17'50.14"E). c) Excoecaria agallocha L. (Euphorbiaceae) Excoecaria agallocha (Plate 2.3) is a small to medium sized back mangrove species and often exploits open areas along with some marine and coastal protected regions. This species is widespread, common and can be decidiuous in cooler/drier areas. Coastal development has created some localized threats and decline in overall population has been reported. Habit: Small to Medium sized trees with 10 m high, much branched dioecious trees with milky latex, sometimes, branching is from the base, hence shrubby with a bushy appearance; many superficial lateral roots are spreading, intermingling and exposed during low tides, a prominent main root is absent; greyish to pale brown stem barks with smooth lenticels; brownish green or occasionally green, terate and glabrous twigs. Leaves: alternate, 3 – 13 x 1.5 – 5 cm, spirally arranged, simple, stipulate and petiolate; minute stipules as lateral triangular scales present on each side of the petiole; terate and green petiole with ovate, ovate- elliptic, or ovate – oblong, cuneate or obtuse and with a pair of glands at base, shiny green colored above, 63 turning red before shedding, pale green beneath; prominent midrib beneath with 8 – 14 pairs lateral veins. Inflorescence: Unisexual, axillary, pale green, initiated as catkin like structures within the leaf bearing portion of the shoot. Male spikes of 3.5 – 12.5 cm long, 2 – 3 together in an axil with a series of spirally arranged bracts; each bract subtending 1 male flower; one bracteole each present on either side of the flower; Male flowers almost sessile, cream colored; 3 tepals, narrow and lanceolate; 3 yellow stamens; anthers are long, basifixed to almost versatile, bilobed, dehiscing longitudinally; Female inflorescence is a raceme, 4 – 8 cm long, usually shorter than the male inflorescence; shortly pedicellate female flowers are with the inflorescence. Bract and bracteoles is present, superior ovary with 3 locules, ovules 1 in each locule, pendulous. Fruit: capsule of 4 – 6 x 8 – 12 mm, depressed globose, crustaceous, 3 celled. Flowering and Fruiting: November – February. The present study was carried out in three heterogeneous natural habitats of Excoecaria agallocha, falling in Ayiramthengu 2 of Kollam district (9⁰07'28.71"N: 76⁰28'38.89"E), Kumbalam 2 of Ernakulam district (9⁰54'15.02"N: 76⁰18'45.49"E) and Thekkumbad 3 of Kannur district (11⁰58'00.71"N: 75⁰17'49.79"E). d) Rhizophora mucronata Lam. (Rhizophoraceae) Rhizophora mucronata (Plate 2.4) is a widespread common mangrove species (along marine and coastal protected areas) found in the intermediate to upstream estuarine zone in the lower to mid-intertidal region and more to the seaward side. This species tolerates a maximum salinity of 40 ppt and the salinity for optimal growth has been reported as 8-33 ppt (Robertson and Alongi, 1992). This is a fast- growing, hardy species that is easily propagated and is one of the preferred species for restoration programs. Habit: Greatly branched small evergreen trees to 8 m high, profusely spread branches; trunk and lower branches supported by numerous lenticellate, corky, 64 profusely looping stilt roots and prop roots; Brown and longitudinally fissured stem bark. Leaves: 10 - 15 x 5 – 9 cm, simple, stipulate, petiolate, opposite and decussate, elliptic to ovate; dark green above and pale green beneath with numerous black dots; interpetiolar, pale green with pinkish tinge on stipules; petiole cuneate at base and mucronate at apex, green above, pale green beneath; prominent midrib beneath with 8 pairs of lateral veins. Inflorescence: axillary cymes, opposite, decussate, dichotomously or trichotomously branched or unbranched, 2 - 4 flowered, main peduncle upto 3 – 5 cm long. Flowers 2.5 cm long, 1.5 cm across, sessile, bracteate; bract small, connate; bracteoles 2, connate; yellowish white calyx enclosing the base of the pistil; lobes 4, thick, fleshy; petals 4, white lanceolate, densely white hairy along the margin; 8 free stamens, free, sessile, 4 stamens opposite to the petals and 4 to the calyx tubes; semi inferior, 2 loculed ovary, ovules 2 in each locule, pendulous in placentation. Fruit: 5 –7 cm long, ovoid or conoid, brown pericarp, reflexed calyx lobes, 1 seeded. (Mature viviparous seedlings fall on the ground and develop into a young plant within a few days). Flowering and Fruiting: Mostly throughout the year. The present investigation was carried out in three natural habitats of Rhizophora mucronata, which include Ayiramthengu 3 of Kollam district (9⁰07'28.74"N: 76⁰28'39.44"E), Kumbalam 3 of Ernakulam district (9⁰54'22.16"N: 76⁰18'42.21"E) and Thekkumbad 4 of Kannur district (11⁰58'02.87"N: 75⁰17'45.38"E). e) Sonneratia alba Sm. (Sonneratiaceae) Sonneratia alba (Plate 2.5) is a widespread and common species found in the low- intertidal zone. It is intolerant of long periods of freshwater, and prefers high salinity. It is a pioneering species that is fast growing, but has low seed-viability. In the low intertidal zone, it can be the dominant species along with A. marina, forming 65 a tree line along the seaward margin of its range. It prefers soils of consolidated mud and sand. Habit: Greatly branched small evergreen trees to 9 m high; radial cable roots are with pneumatophores, 75 x 0.8 cm, straight, stout, conical, outer thin layer flaky, yellowish – brown; cracked brown bark; swollen nodes with 2 lateral pairs of circular glands. Leaves: 4.5 - 11 x 3 – 9 cm, simple, opposite, broadly elliptic, ovate or sub orbicular; lateral nerves looped near the margin forming intramarginal nerve, estipulate; white or pink petiole, cuneate at base and obtuse at apex. Flowers: White flowers, to 6.5 – 8 cm, in terminal axillary or leaf opposed clusters of 2 or 3, rarely solitary; calyx green outside, white within ; calyx cup angular, lobs oblong, thick, persistent; petals linear, white with reddish tinge towards apex, membraneous, glabrous; numerous white thread like, free stamens inflexed in bud; reniform anthers; style coiled in bud. Fruit: a drupe, to 4 cm across, green, flattened above with reflexed calyx and style with a depression around the stylar base. Smooth pericarp; many seeded. Flowering and Fruiting: Feb-July. The present investigation focused on three heterogeneous natural habitats of Sonneratia alba in Kerala, such as Kadalundi 3 (11⁰07'35.14"N: 75⁰49'51.77"E) and Kadalundi 4 of Malappuram district (11⁰07'35.42"N: 75⁰49'50.72"E) and Thekkumbad 5 (11⁰58'04.32"N: 75⁰17'45.38"E) of Kannur district. Sample Collection and Analysis In order to standardize the growth sustaining conditions of selected mangrove species, samples of water and soil / sediment were collected from three heterogeneous natural habitats for each mangrove species. Samples were collected on a monthly basis from all the locations under study, for a period of one year from June 2013 to May 2014. The surface water samples from mangrove habitats were 66 collected in sampling bottles and were brought to laboratory for the analysis of various parameters like pH, turbidity, total solids, total dissolved solids, total suspended solids, salinity, resistivity, conductivity, acidity, alkalinity, total hardness, calcium, magnesium, chloride, sulphate, sodium, total nitrogen, phosphorous and potassium. All the parameters were analyzed following standard procedures (Trivedy et al., 1987 and APHA, 2005) as given below. a) pH (Electrometric method) pH of the collected water samples were measured electrometrically using a pH meter (Systronics, MK IV). b) Turbidity (Nephelometric method) Turbidity of samples was determined by Nephelometric method using a Digital Nephelometer (Systronics, Model 341). The results are presented in NTU. c) Total solid (TS) (Gravimetric method) Total solid content measure the amount of all kinds of solids (suspended, dissolved, volatile, etc.) in water. Total solids can be determined as the residue left after evaporation of the unfiltered sample. For the present study, evaporating dishes of suitable size were taken and weighed. 100 ml of respective unfiltered water samples were taken and evaporated to dryness in an oven. After evaporation, the samples were heated at 103ºC for 1 hour in a hot air oven (Rotek, Model 07253). These were then cooled in a desiccator and weighed. Total solids (mg/l) were estimated, following the equation: Total solid, mg/L = (a - b) x 1000 x 1000 v Where, a = Final weight of the dish in g. b = Initial weight of the dish in g. v = volume of sample evaporated in ml 67 d) Total Dissolved Solid (TDS) (Gravimetric method) Total dissolved solids measure various kinds of minerals present in water. It can be determined as the residue left after evaporation of the filtered sample. Evaporating dishes of suitable size were taken and weighed. 100 ml of respective samples were filtered through Whatmann filter paper and evaporated to dryness in an oven. After evaporation, the samples were heated at 103ºC for 1 hour in a hot air oven (Rotek, Model 07253). These were then cooled in a desiccator and weighed. Total dissolved solids (mg/l) were estimated by the following equation: Total dissolved solid, mg/L = (a - b) x 1000 x 1000 v Where, a = Final weight of the dish in g. b = Initial weight of the dish in g. v = volume of sample evaporated in ml e) Total Suspended Solids (TSS) (Gravimetric method) TSS indicates the suspended impurities present in water and in most of the cases, they are of organic in nature. TSS is the difference between TS and TDS present in water. Total Suspended Solids (mg/l) were calculated by the following equation: TSS = TS – TDS f) Salinity Salinity is the measure of all the salts dissolved in water and is usually measured in parts per thousand (ppt). Salinity in the present study was measured using Eutech Cyber Scan Series water sample analyzer (Eutech PCD, 650). The results are represented in ppt. 68 g) Resistivity Electrical resistivity was measured using Eutech cyber scan series water sample analyzer (Eutech PCD, 650). The results are presented in ohms (Ω). h) Electrical Conductivity Electrical Conductivity (EC) is a measurement of the dissolved materials in an aqueous solution, which relates to the ability of the material to conduct electrical current through it. EC was measured using Eutech cyber scan series water sample analyzer (Eutech PCD, 650). The results are depicted in milli Siemens (mS) per unit area. i) Acidity (Titrimetric method) It is measure of the aggregate property of water to react with a strong base at a particular pH. In natural waters, the most important attribute that imparts acidity are carbon dioxide. Reagents 1. 0.05N Sodium hydroxide 2. Phenolphthalein indicator Procedure To 100 ml of water sample in conical flask, added few drops of Phenolphthalein indicator and mixed well. The contents were titrated against 0.05N Sodium hydroxide taken in the burette. The end point was noticed at the appearance of pink color. Acidity was calculated as: Acidity, mg/L = (ml x N) of NaOH x 1000 x 44 ml sample j) Total alkalinity (Titrimetric method) Alkalinity of the water is the capacity to neutralize a strong acid and is characterized by the presence of all hydroxyl ions. The free hydroxyl groups impart alkalinity in 69 natural waters. Such ions are also formed in water due to the hydrolysis of salts such as carbonates and bicarbonates. Reagents: 1. 0.1N Hydrochloric acid 2. 0.1N Sodium Carbonate 3. Methyl orange indicator Procedure: 100ml of water sample was taken in conical flask and added 2-3 drops of methyl orange indicator. Mixed well and titrated the contents against 0.1N HCl taken in the burette. The end point was noted as color change from yellow to pink. Total alkalinity as CaCO3, mg/L = (ml x N) of HCl x 1000 x 50 ml sample k) Total hardness (Titrimetric method) Both cations and anions are responsible for hardness of water. The important cations imparting hardness in water are calcium and magnesium. Anions like carbonates, bicarbonates and sulphates are the major anions imparting hardness to water. Reagents 1. 0.01 M EDTA solution 2. Buffer solution- Mixture of Ammonium chloride, Ammonium hydroxide and disodium EDTA. 3. Eriochrome Black T indicator Procedure To 50 ml of water sample in conical flask, added 1 ml of buffer solution. This was followed by 100 mg of Eriochrome Black T indicator and mixed well. Development 70 of a wine red color was noticed. The contents were then titrated against EDTA solution taken in the burette. The end point was noticed as color change from wine red to blue. Total Hardness as CaCO3, mg/L = ml EDTA used x 1000 ml sample l) Calcium (Titrimetric method) Calcium is one of the most abundant elements imparting the hardness to the natural water. At high pH, much of the quantities may get precipitated as CaCO3. Reagents 1. 0.01M EDTA solution 2. 1N Sodium hydroxide 3. Murexide indicator- Mixture of 0.2 g ammonium purpurate and 100g of NaCl. Procedure 50 ml of sample was taken in a conical flask; added 2 ml sodium hydroxide solution and approximately 100 mg of Murexide indicator to it. Development of a pink color was observed. Titrated the solution against 0.01 M EDTA, until the color changed to purple. Calcium mg/L = ml EDTA used x 400.8 ml sample m) Magnesium (Titrimetric method) Magnesium is also one of the important cations imparting hardness to the water, but its concentration remains generally lower. Reagents 71 1. 0.01M EDTA solution 2. Buffer solution- Mixture of Ammonium chloride, Ammonium hydroxide and disodium EDTA 3. Eriochrome Black T indicator 4. 1N Sodium hydroxide 5. Murexide indicator- Mixture 0.2 g ammonium purpurate and 100g of NaCl. Procedure Magnesium is determined as the difference between Ca + Mg titration and the titration alone for calcium. In the present study, titrated a constant volume of sample for calcium and also for total hardness, found out the volume of EDTA used for both the titrations separately. Magnesium mg/L = (y – x) x 400.8 ml sample x 1.645 Where, x = EDTA used for calcium determination y = EDTA used for total hardness (Ca + Mg) n) Chloride (Argentometric method) Chlorides are present in all natural waters. Sewage discharges into the water bodies will enhance the chloride content. Reagents 1. 0.02 N Silver nitrate 2. 5% potassium chromate solution 72 Procedure To 50 ml of water sample, added 2 ml of 5% potassium chromate solution and mixed well. Titrated the contents against 0.02 N Silver nitrate solution taken in the burette. Appearance of reddish brown color persisting for 30 seconds was noted as the end point. Chloride, mg/L = (ml x N) of AgNO3 x 1000 x 35.45 ml sample o) Sulphate (Turbidimetric method) Sulphate is a naturally occurring anion found in almost all kinds of water bodies. It may undergo transformation to sulphur or hydrogen sulphide, depending largely upon the redox potential of the water. It also imparts hardness to water to a certain extent. Reagents 1. Conditioning reagent- mixed 50 ml of glycerol to the solution prepared by mixing 75 g of NaCl, 30 ml concentrated HCl, 100 ml 95% ethyl or isopropyl alcohol in 300 ml distilled water. 2. Barium chloride 3. Standard sulphate solution- Dissolved 0.1479 g of anhydrous Na2SO4 in distilled water to prepare 1 litre of solution and the solution contains 100 mg of sulphate. Procedure To 100 ml of clear sample, added 5 ml of conditioning reagent and stirred well. Added about one spatula of BaCl2 crystals and stirred for 1 minute. Optical density was measured with a spectrophotometer at 420 nm, exactly after 4 minutes and found out the sulphate concentration from the standard graph. 73 p) Sodium (Flame photometric method) Sodium is an important cation occurring naturally in water and domestic sewage is one of the most important sources of sodium to the fresh waters. Sodium with chlorides and sulphates make the water unpalatable. Reagents 1. Stock sodium solution (1000mg/L) - dissolved 2.542 g NaCl in distilled water to make 1 litre of solution. 2. Intermediate sodium solution (100mg/L) – Dilute the stock solution to 10 times. 3. Standard sodium solution (10 mg/L) - Dilute the intermediate solution further 10 times. Procedure The concentration of sodium present in the sample was estimated by using Flame Photometer (Systronics, 128). The instrument was calibrated with a higher and lower concentration of standard sodium solution. All the samples were analyzed in the instrument and the results are obtained in ppm concentration. q) Total Nitrogen (Kjeldahl Method) The nitrogen content of water is one of the measures used to evaluate its purity. Kjeldahl method is the most common, reliable and economical method for nitrogen estimation. Reagents 1. Catalyst mixture – Mixture of Sodium sulphate and Cupric sulphate in 5 : 1 ratio 2. Concentrated Sulphuric acid 3. 40% NaOH 74 4. 0.32% Potassium permanganate 5. 4% Boric acid 6. Mixed indicators - Methyl red and Bromo-cresol green (1:2) 7. 0.1 N HCl Procedure Nitrogen content of the samples were analyzed using an automated nitrogen estimation system (KELPLUS, ELITE=EX (VA). The principle followed for estimating the nitrogen content of the sample is Kjeldahl method. Analysis was carried out as per the manual of the instrument given below. a) Digestion In order to digest the water sample, 2 spatula of catalyst mixture and 10 ml of concentrated sulphuric acid was added to 10 ml of sample and subjected to digestion within the infra digestion unit of the Kelplus nitrogen estimating system. The sample attained a green color, when it was fully digested. The samples were allowed to cool and diluted with distilled water for further analysis. b) Distillation The diluted sample was placed in the distillation system for ammonia recovery using ammonia trapping solution (Boric acid and mixed indicator). c) Titration After trapping all ammonia present, the resultant solution was titrated against 0.1 N HCl for estimating the total nitrogen content. Total nitrogen was estimated using the formula; % Nitrogen = 14.01x (ml titrant – ml blank) x N x 100 Sample volume x1000 75 r) Total Phosphorous (Stannous chloride method) Phosphorous mostly occurs as phosphates in natural waters. It is necessary for the growth of organisms and can be the nutrient that confines primary productivity to a water body. Phosphorous estimation generally includes two steps; (a) conversion of any form of phosphorous to dissolved orthophosphates and (b) spectrophotometric determination of the orthophosphate. The first step is accomplished through persulphate oxidation technique and the second one through stannous chloride method. Reagents 1. Sulfuric acid solution- added 300 ml of concentrated sulfuric acid to about 600 ml of distilled water. Cooled and diluted to 1 litre with distilled water. 2. Ammonium molybdate solution - Dissolved 25 g of (NH4)6Mo7O24. 4H2O in 175 ml of distilled water. Added 280 ml of concentrated sulfuric acid slowly to 400 ml of distilled water. Cooled and added molybdate solution to the acid solution and diluted to 1 liter. 3. Stannous chloride solution: Dissolved 2.5 g of fresh SnCl2-2H2O in 100 ml of glycerol. Heated in water bath and stirred with a glass rod to hasten dissolution. 4. Potassium persulfate as the analytic reagent. Procedure 1 ml of sulfuric acid solution and 0.4 g of potassium persulfate was added to 50 ml of sample and boiled gently for 30 minutes until a volume of 10 ml was reached. Diluted the sample to 50 ml with distilled water. 2 ml of ammonium molybdate solution and 3 drops of stannous chloride solution were added to the sample and mixed well. Kept the samples for another 10 – 12 minutes and measured the optical density at 690 nm. 76 Compared the values with a calibration curve, using distilled water as blank. The concentration of phosphorous from the standard graph was calculated. s) Potassium (Flame photometric method) Potassium is also a naturally occurring element in water, but its concentrations remains quite lower than sodium, calcium and magnesium. Reagents 1. Stock potassium solution (1000mg/L) - dissolved 1.907 g KCl in distilled water to make 1 litre of solution. 2. Intermediate sodium solution (100mg/L) – Diluted the stock solution to 10 times. 3. Standard sodium solution (10 mg/L) - Diluted the intermediate solution further to 10 times. Procedure The concentration of potassium present in the sample was estimated using Flame Photometer (Systronics, 128). The instrument was calibrated with a higher and lower concentration of standard potassium stock solutions. All the samples were analyzed in the instrument and the results are reported in ppm concentration. Similar to water samples, soil / sediment samples from respective habitats were collected using a clean plastic spatula. Each sample was packed in a clean polythene bag, tightly closed and kept in an icebox. The collected samples were brought to laboratory for the analysis of various quality parameters like pH, moisture percentage, organic carbon, total nitrogen, total phosphorous, potassium, sodium and textural percentages of sand, silt and clay. All the parameters were analyzed following standard procedures (Jackson, 1973; Trivedy et al., 1987 and Subramanyam and Sambamurthy, 2002). 77 a) pH pH is a good measure of acidity and alkalinity of a soil- water suspension and provides basic information about the chemical nature of soil. In order to determine the pH of soil/ sediment, a suspension was prepared (1:5 ratio) with distilled water and the pH was measured electrometrically using a pH meter (Systronics, MK IV). b) Moisture percentage Soil moisture content is determined by drying a known quantity of soil sample in an electric oven at 105oC to 110 oC and finding out the loss of weight. Procedure 10 g of sediment sample was taken in a clean, dry and pre weighed non corrodible air tight container and kept it in an electric oven at 105oC for about 8 hours. Removed the container, allowed to cool and weighed it out quickly. Moisture % is then calculated as: Moisture % = (a1 – a) - (b – a) (a1 – a) Initial weight of the container = a Weight of the container + sample = a1 Initial weight of the sample = (a1 – a) Final weight of the container with sample = b Final weight of the sample = (b – a) c) Organic carbon Organic carbon is the measure of total carbon in the soil / sediment sample. In the present study, organic carbon was estimated by a semi-quantitative method - Hydrogen Peroxide (H2O2) digestion method (Schumacher, 2002). Semi-quantitative methods are based upon the indiscriminant removal of all organic matter followed by gravimetric determination of sample weight loss. The hydrogen peroxide (H2O2) digestion method destroys the organic matter in the sample through oxidation. 78 Reagents 1. 30% Hydrogen peroxide Procedure A known volume of hydrogen peroxide (30%) was added to 20 g of sediment sample continually, until the sample frothing ceases. Once the digestion process was completed, the sample was dried at 105OC, cooled in a desiccator, and weighed. Organic carbon percentage was determined gravimetrically as follows: Organic carbon % = [(a1- a) - (c – a)] x 100 (a1- a) Initial weight of beaker = a Weight of beaker + sample = a1 Wet weight of sample = (a1- a) Final weight of beaker + sample = c Dry weight of sample = (c – a) d) Total Nitrogen (Kjeldahl method) Kjeldahl method is the most common, reliable and economical method for nitrogen estimation. It is being carried out as follows: Reagents 1. Catalyst mixture – Mixture of Sodium sulphate and Cupric sulphate in 5 : 1 ratio 2. Concentrated Sulphuric acid 3. 40% NaOH 4. 0.32% Potassium permanganate 79 5. 4% Boric acid 6. Mixed indicators - Methyl red and Bromo-cresol green (1:2) 7. 0.1 N HCl Procedure Nitrogen content of the samples were analysed using an automated nitrogen estimation system (KELPLUS, ELITE=EX (VA). The principle followed was Kjeldahl method. Analysis was carried out following the manual of the instrument. The method Kjeldahl includes three phases. a) Digestion In order to digest the sediment sample, 2 spatula of catalyst mixture and 10 ml of concentrated sulphuric acid was added to 1.0 g of sample and subjected to digestion within the infra digestion unit of the Kelplus nitrogen estimating system. The sample attained a milky white color, when it gets completely digested. Allowed the samples to cool and diluted for further analysis. d) Distillation The diluted sample was placed in the distillation system for ammonia recovery using ammonia trapping solution (Boric acid and mixed indicators). e) Titration After trapping all the ammonia, the resultant solution was titrated against 0.1 N HCl for estimating the total nitrogen content. Total nitrogen was estimated using the formula; % Nitrogen = 14.01x (ml titrant – ml blank) x N x 100 Sample volume x1000 80 e) Total Phosphorous Phosphorous estimation generally includes two steps; (a) conversion of any form of phosphorous to dissolved orthophosphates and (b) colorimetric determination of the orthophosphate. Here, the first step is accomplished with persulphate oxidation technique and the second is with the stannous chloride method. Reagents 1. Nitric acid (Concentrated) 2. Perchloric acid 3. Sulphuric acid (5%) 4. Ammonium molybdate solution - dissolved 25 g of (NH4)6Mo7O24. 4H2O in 175 ml of distilled water. Add 280 ml of concentrated sulfuric acid slowly while stirring to 400 ml of distilled water. Cool. Add the molybdate solution to the acid solution and dilute to 1 liter. 5. Stannous chloride solution: dissolved 2.5 g of fresh SnCl2-2H2O in 100 ml of glycerol. Heated in water bath and stirred with a glass rod to hasten dissolution. Procedure Added 2 ml of Nitric acid and 2 ml Perchloric acid to 0.5 g air dried sediment sample. Heated gently upto dryness and allowed it to cool for some time. 21 ml of 5 % sulphuric acid was added to the sample and boiled for 15 minutes. After cooling, filtered the content through Whatman no: 44 filter paper and made up the volume to 250 ml with distilled water. 2 ml of ammonium molybdate solution and 3 drops of stannous chloride solution was added to 50 ml of acid digested sample and mixed well. Kept the samples for another 10 – 12 minutes and measured the optical density at 690 nm. 81 Compared the values with a calibration curve using distilled water as blank and found out the phosphorous concentration from the standard graph.(Standard graph prepared by following the same procedure for the sample, anhydrous KH2PO4 was used to prepare the stock solution). f) Potassium (Flame photometric method) Potassium estimation in sediment sample generally includes two procedural steps; acid digestion technique and flame photometric analysis. Reagents 1. Stock potassium solution (1000mg/L) - dissolved 1.907 g KCl in distilled water to make 1 litre of solution. 2. Intermediate sodium solution (100mg/L) – Diluted the stock solution to 10 times. 3. Standard sodium solution (10 mg/L) - Diluted the intermediate solution further 10 times. 4. Nitric acid 5. Perchloric acid 6. 5% Sulphuric acid Procedure The concentration of potassium present in the acid digested sample was estimated using Flame Photometer (Systronics, 128). The instrument was calibrated with a higher and lower concentration of standard stock potassium solution. Analysis was carried out, following the instruction manual and the results are represented in ppm levels. 82 g) Sodium (Flame photometric method) Estimation of sodium in sediment sample is generally accomplished with the acid digestion technique and the flame photometric analysis. Reagents 1. Stock sodium solution (1000mg/L) - dissolved 2.542 g NaCl in distilled water to make 1 litre of solution. 2. Intermediate sodium solution (100mg/L) – Diluted the stock solution to 10 times. 3. Standard sodium solution (10 mg/L) - Diluted the intermediate solution further to 10 times. 4. Nitric acid 5. Perchloric acid 6. Sulphuric acid 5% Procedure The concentration of sodium present in the acid digested sample was estimated by Flame Photometer (Systronics, 128). The instrument was calibrated with a higher and lower concentration of standard sodium stock solutions. Samples were analyzed and the results were obtained in ppm concentration. h) Textural analysis (International Pipette Method) Relative proportion of the soil particles of various sizes is an important physical parameter which determines texture of the soil. Larger particles help in providing the physical support to the plants, while smaller size particles determine the capacity of soil to hold water and availability of nutrients. 83 Reagents 1. Hydrogen peroxide (6%) 2. HCl (5N) Procedure 20 g each of air dried soil / sediment sample was transferred in to a 500 ml beaker. Slowly added 60 ml of Hydrogen peroxide (6%) till the frothing ceased. Added 200 ml of 5N HCl and kept overnight. Filtered the contents through Whatman No. 50 filter paper. Washed the soil residue with water and transferred to a 1000 ml measuring cylinder, volume was made up to 1000 ml mark with water. The contents were shaken thoroughly and kept undisturbed till the settling time is over. After the stipulated time for clay and silt, 20 ml of suspension was pipette out from a depth of 10 cm and transferred to a pre weighed clean porcelain dish. Evaporate and dried the suspension at 105oC in a hot air oven. Cooled the dish in a desiccator and determined the weight of clay and silt separately. After attained the settling time for sand, drained the water as much as possible and transferred the content of sand in to a pre weighed porcelain dish and subjected to dryness. Cooled in a desiccator and weighed. % of Clay = Weight of clay x 100 Weight of sample taken % Sand = Weight of sand x 100 Weight of sample taken % Silt = 100 – (% Clay + % Sand) The estimated percentages of sand, silt and clay were used to determine the textural class of the soil. Data on various climatological attributes like atmospheric maximum temperature; atmospheric minimum temperature, Total Rainfall (MMS) and Relative Humidity (%) with respect to all the sites and period of study were procured from India 84 Meteorological Department, Government of India. The results of all analyses were depicted in the following sections. Statistical analysis Statistical analysis in the case of relevant data was carried out using two way ANOVA without replications using Microsoft Excel Software and Significance level of 5% was taken as the level of significance. Results and Discussion Many ecological factors strongly influence the growth and development of mangroves (Kjerfve et al., l999). Among them, water and sediment quality are known to have supreme influence (Thom, 1967). The growth requirements of mangroves are also species specific. The present investigation focus on an evaluation of the hydrogeochemical, sedimentological and climatological factors influencing the growth and establishment of five mangrove species (Avicennia officinalis, Bruguiera cylindrica, Excoecaria agallocha, Rhizophora mucronata and Sonneratia alba) growing along their natural habitats in the coastal environments of Kerala. The mean values of all water quality parameters together with their standard deviation from habitats containing Avicennia officinalis, Bruguiera cylindrica, Excoecaria agallocha, Rhizophora mucronata and Sonneratia alba are depicted in Tables 2.2 - 2.6, respectively. 85 Table 2.2. Physico- chemical characteristics of water samples from habitats of Avicennia officinalis. PRE MONSOON MONSOON POST MONSOON Seasonal Seasonal Seasonal Annual Mar Apr May Mean± Jun Jul Aug Sep Mean+ Oct Nov Dec Jan Mean+ Mean+ SD SD SD SD Water pH 6.88 ± 6.7 ± 7.095 ± 6.55 6.71 7.03 6.56 7.29 6.38 6.57 6.79 6.89 6.91 7.79 6.8917 ± 0.397 0.307 0.403 0.466 7.745 ± 8.16 7.899 7.67 7.91 ± 0.200 6.99 7.07 7.64 7.02 7.18 ± 0.308 7.49 7.62 7.97 7.9 7.6116 ± 0.397 0.228 7.805 ± 5.523± 7.35 ± 7.61 xx xx xx 6.98 5.73 3.86 6.8 7.41 7.71 7.48 6.8422 ± 1.302 0.276 1.570 0.388 7.44 ± 7.305 ± 7.35 ± 6.775 ± 7.113 ± 6.583 ± 5.817 ± 7.027 ± 7.307± 7.53 ± 7.723 ± 0.818 0.841 0.453 0.304 0.160 0.971 1.709 0.401 0.376 0.552 0.218 Turbidity (NTU) 4.2 ± 17.575± 4.825± 2.8 2.1 10.6 24.9 12.7 16.4 16.3 3.4 5.3 5 5.6 8.8667 ± 7.354 4.311 5.178 0.981 16.25 ± 23.475 ± 12.5± 17.4083 ± 15.8 29.9 5.1 19.1 11.9 4.9 58 26.3 5.8 10.5 7.4 10.248 23.736 9.405 15.134 2.95 ± 12 ± 8.975± 8.6444 ± 2.4 xx xx xx 22.4 12.9 0.7 5.1 16.1 10.9 3.8 0.778 10.878 5.665 7.354 7± 16 ± 7.85 ± 22 ± 15.67 ± 11.4± 25 ± 11.6± 9.067 ± 8.8 ± 5.6 ± 7.624 19.658 3.889 4.101 5.845 5.895 29.624 12.759 6.096 3.297 1.8 T.S (mg/l) 19750 ± 750 ± 11700 ± 10733.333 ± 25800 25200 5400 1000 1000 800 200 4800 2800 16800 22400 9666.954 378.594 9439.633 10769.092 42400 ± 3800 ± 25500 ± 23900 ± 41800 42200 43200 1800 1200 8600 3600 7400 14800 39600 40200 588.7846 3358.571 16901.676 18798.356 42300 ± 800 ± 35500 ± 25444.444 ± 42200 xx xx xx 600 200 1600 25800 44400 44000 27800 141.421 721.110 10080.344 19686.995 12666.67 20666.67 33466.67 30133.33 36600 ± 33700 ± 24300 ± 1400 ± 933.33 ± 3200 ± 1800 ± ± ± ± ± 9355.213 12020.815 26728.636 565.685 305.505 4686.150 1708.801 11447.853 21411.523 14600.457 9126.518 T.D.S (ppt) 18.4 ± 0.4 ± 10.9 ± 9.9± 23.0 24.4 5.2 1.0 0.2 0.2 0.2 4.6 2.2 16.2 20.6 8.910 0.4 8.899 10.136 40.65 ± 3.3 ± 24.8 ± 22.916 7 ± 41.4 39.6 39.8 1.2 0.6 8.4 3.0 7.2 14.2 39.0 38.8 1.112 3.550 16.530 18.272 20.3333 ± 41.6± 0.467 ± 24.6 ± 42.0 xx xx xx 0.4 0.2 0.8 24.6 43.4 2.8 27.6 19.364 0.566 0.306 16.710 35.467 ± 22.5 ± 1.1 ± 0.4 ± 2.93± 1.333 ± 12.133 ± 19.933 ± 19.333 ± 32 ± 10.748 29 ± 9.180 10.801 24.466 0.141 0.2 4.734 1.474 10.874 21.190 18.302 T.S.S (mg/l) 1350 ± 350 ± 800 ± 833.3333 ± 2800 800 200 0 800 600 0 200 600 600 1800 1123.981 412.311 692.820 839.1915 400 2600 3400 1750± 600 600 0 600 450 ± 200 600 600 1400 700 ± 966.6667 ± 86 1482.116 300 503.322 1019.2094 700 ± 333.33 ± 10900 ± 5111.1111 ± 200 xx xx xx 200 0 800 1200 1000 41200 200 707.107 416.333 20204.620 13541.459 1133.33 ± 1700± 1800 ± 300 ± 533.33 ± 200 ± 466.67 ± 533.33 ± 733.33 ± 14133.33 ± 1133.33 ± 1446.836 1272.792 2262.742 424.264 305.501 346.410 416.333 577.350 230.940 23440.421 832.666 Salinity (ppt) 15.852 ± 0.498 ± 9.729 ± 8.6928 ± 20.65 19.97 4.807 0.699 0.762 0.195 0.334 4.233 2.213 14.27 18.2 7.450 0.276 7.726 8.654 34.8 ± 2.874 ± 21.358 ± 19.6773 ± 35.42 35.39 34.73 1.234 0.831 6.807 2.623 6.582 12.8 32.18 33.87 0.824 2.732 13.726 15.507 34.755 ± 0.421 ± 26.5575 ± 19.6669 ± 34.98 xx xx xx 0.216 0.05 0.996 11.31 33.69 38.05 23.18 0.318 0.505 11.928 16.523 30.35 ± 27.68 ± 19.769 ± 0.9665 ± 0.603 ± 2.3507 ± 1.318 ± 7.375 ± 16.234 ± 28.167 ± 25.083 ± 8.403 10.904 21.159 0.378 0.337 3.86 1.178 3.605 16.017 12.388 8.007 Resistivity (Ω) 53.733 ± 1344.1 ± 112.97 ± 503.6017 ± 30.91 31.75 117.4 723.8 671.6 2520 1461 131.1 243.5 42.75 34.54 42.479 862.832 97.381 769.471 19.263± 330.495 ± 43.61 ± 131.1225 ± 19.03 19.03 19.22 420.6 608.4 84.98 208 86.7 47.52 20.52 19.7 0.35 231.396 31.501 191.476 19.31 ± 6000.67 ± 29.5775 ± 2017.6589 ± 19.28 xx xx xx 2244 10790 4968 53.18 19.68 17.71 27.74 0.042 4365.585 16.322 3699.783 23.073 ± 68.31 ± 572.2 ± 1174.67 ± 4464.99 ± 2212.33 ± 90.327 ± 103.57 ± 26.993 ± 27.327 ± 25.39 ± 8.994 6.788 69.424 214.395 926.609 5611.293 2467.342 39.086 121.983 13.718 7.4286 Conductivity (mS) 24.693 ± 0.9655 ± 15.652 ± 13.77 ± 31.62 30.78 8.339 1.348 1.456 0.389 0.669 7.455 4.024 22.83 28.3 11.010 0.519 11.746 13.231 50.7825 ± 5.02825 ± 32.2975 ± 29.369 51.41 51.37 50.8 2.325 1.61 11.48 4.698 11.27 20.6 47.66 49.66 0.868 4.499 19.291 ±22.193 50.585 ± 0.2407 ± 39.6525 ± 28.9447 ± 50.71 xx xx xx 0.435 0.091 0.196 18.38 49.74 55.23 35.26 0.177 0.176 16.494 24.195 44.58 ± 41.075 ± 29.57 ± 1.8365 ± 1.167 ± 3.987 ± 1.854 ± 12.368 ± 24.788 ± 41.907 ± 37.74 ± 11.229 14.559 30.025 0.691 0.639 6.491 2.474 5.545 23.144 16.949 10.894 Acidity (Mg/l) 36.85 ± 12.1± 18.7 ± 22.55 ± 88 26.4 13.2 22 8.8 6.6 11 17.6 8.8 22 26.4 34.523 6.840 7.5144 21.741 35.2 ± 16.5 ± 32.23 ± 27.9767 ± 30.8 30.8 44 8.8 8.8 26.4 22 66 1.32 17.6 44 6.223 9.071 28.5681 18.1392 44 ± 29.33 ± 36.3 ± 35.6889 ± 39.6 xx xx xx 13.2 48.4 26.4 26.4 52.8 22 44 6.223 17.782 14.537 13.9911 52.8 ± 28.6 ± 15.4 ± 10.267 ± 27.133 ± 19.8 ± 36.667 ± 20.973 ± 20.533 ± 38.133 28.6 ± 3.111 30.80 21.779 9.334 2.540 20.910 7.932 25.782 27.815 2.540 ±10.161 Alkalinity (Mg/l) 170 ± 95 ± 131.25 ± 132.0833± 210 200 120 130 50 110 90 175 100 120 130 42.426 34.157 31.721 45.898 170 ± 172.5 ± 160.8333 ± 200 160 150 70 120 160 340 170 100 150 140 140 ± 29.439 21.603 117.580 66.121 215 ± 113.333 ± 177.5 ± 164.4444 ± 230 xx xx xx 150 120 70 150 170 160 230 21.213 40.415 35.940 51.505 213.33 ± 180 ± 135 ± 100 ± 106.67 ± 130 ± 166.7 ± 165 ± 123.33 ± 143.33 ± 166.67 ± 87 15.275 28.284 21.213 42.426 51.316 26.458 150.444 13.229 40.415 20.817 55.076 Hardness (Mg/l) 3425 ± 1690.5 ± 1786.167 ± 4300 4540 1100 740 136 38 58 243 ± 334.02 150 92 2740 3780 1583.951 1861.523 1872.344 7190 ± 272.25 ± 3010 ± 3490.75 ± 6980 7620 7280 340 145 300 304 280 440 4500 6820 333.267 86.719 3203.852 3414.501 7060 ± 42 ± 3304 ± 3051.333 ± 7060 xx xx xx 46 26 54 406 910 6900 5000 0 14.422 3158.970 3344.774 6113.3 ± 6080 ± 4190 ± 540± 109 ± 121.333 ± 138.7 ± 278.67 ± 480.67 ± 4713.3 ± 5200 ± 1570.902 2177.889 4369.920 282.843 54.745 154.846 143.197 128.005 410.514 2088.189 1529.837 Calcium (Mg/l) 276.345 ± 37.148 ± 139.79 151.094± 352.44 320.4 144.18 120.15 12.42 6.4 9.62 59.32 27.25 184.23 288.36 91.912 55.390 ±119.984 132.436 482.605 ± 32.653 ± 268.38 ± 261.217 ± 440.56 448.56 552.69 56.07 12.82 24.85 36.87 80.16 152.3 392.49 448.56 51.234 18.443 179.601 215.509 492.615 ± 10.957 ± 440.64 ± 308.963± 528.66 xx xx xx 13.63 8.82 10.42 152.3 344.69 464.58 801 50.975 2.450 272.506 280.318 174.75 ± 440.553 ± 384.48 ± 348.44 88.11 12.957 ± 13.357 ± 18.97 ± 97.26 ± 347.1 ± 512.64 ± 159.906 88.11 90.623 ±288.860 ±45.311 0.617 10.027 15.507 48.791 145.582 262.259 Magnesium (Mg/l) 343.026 ± 665.875 ± 36.595 ± 326.608 ± 832.65 910.56 180.16 107.12 25.58 5.4 8.28 0.49 5.84 555.1 745 377.323 331.219 47.854 381.447 1455.9 ± 46.455 ± 569.723 ± 690.693 ± 1426.7 1582.5 1436.4 48.69 27.53 57.99 51.61 19.48 14.61 857 1387.8 88.183 13.201 673.967 703.719 1419.4 ± 536.6 ± 555.101 ± 1397.5 xx xx xx 2.92 0.97 6.82 3.57 ± 2.979 6.33 12.17 1397.5 730.4 30.971 667.063 684.092 1218.95 ± 1246.53 ± 808.28 ± 77.905 ± 18.677 ± 21.453 ± 22.237 ± 8.767 ± 10.873 ± 936.53 ± 954.4 ± 334.864 475.133 888.296 41.316 13.681 31.719 25.449 9.727 4.527 426.795 375.406 Chloride (Mg/l) 14377.5 ± 1519.4 ± 8108.2 ± 8001.7 ± 16330 21300 6390 4402 710 525.4 440.2 2896.8 2982 11857 14697 6226.853 1925.03 6080.088 7192.611 27441.5 ± 2765.45 ± 15566.75± 15257.9 ± 22720 23856 40186 3834 724.2 4544 1959.6 4260 10295 18460 29252 8510.034 1743.668 10821.135 12778.04 25134 ± 293.467 ± 20678.75± 14873.711 ± 26980 xx xx xx 255.6 326.6 298.2 13490 27335 25347 16543 2610.638 35.736 6705.241 11857.436 22010 ± 22578± 23288 ± 4118 ± 563.27 ± 1798.67 ± 899.3 ± 6882.27 ± 13537.33 ± 18554.67 ± 20164 ± 5360.382 1807.365 23897.38 401.637 266.542 2379.605 920.959 5762.915 12496.067 6745.498 7924.376 Sulphate (Mg/l) 76.5 ± 3.625 ± 37.375 ± 115 105 35 6 4 2 2.5 27.5 15 42 43.5 32 ± 13.435 39.442 1.797 38.154 88.75 ± 18.625 ± 46.25 ± 51.208 ± 105 126 63 12 7.5 32 23 34 53 51 47 32.066 11.041 8.539 35.229 90.25± 4.083 ± 52.75 ± 44.861 ± 120 xx xx xx 4 2.75 5.5 53 53 57 48 42.073 1.377 3.686 37.370 9 ± 113.33 ± 115.5± 49 ± 5.167 ± 12.25 ± 10.33 ± 38.167 ± 40.333 ± 46.167 ± 4.24 50 ± 7.549 7.638 14.849 19.799 2.021 17.108 11.072 13.251 21.939 2.363 88 Sodium (ppt) 9.713 ± 1.326± 5.991 ± 5.677 ± 14 12.8 0.65 4.6 0.475 0.21 0.02 3.115 1.4 6.4 13.05 6.134 2.191 5.1428 5.624 24.45 ± 2.59 ± 14.764 ± 13.935 ± 23.55 24.3 20.4 4.05 0.595 3.885 1.83 4.835 8.37 20.55 25.3 3.797 1.67 9.729 10.852 27.15 ± 0.188 ± 26.444 ± 17.849 ± 24.65 xx xx xx 0.265 0.15 0.15 6.825 54.6 27.8 16.55 3.536 0.066 20.635 18.351 20.733 ± 18.55 ± 10.525 ± 4.325 ± 1.415 ± 0.667 ± 4.925 ± 21.457 ± 18.25 ± 18.3 ± 0.445±0.167 5.857 8.132 13.965 0.389 2.139 1.010 1.857 28.914 10.884 6.310 Nitrogen (mg/l) 45.5± 42.25 ± 89.75 ± 59.167 ± 42 28 42 42 39 38 50 70 160 80 49 17.616 5.439 48.582 35.334 56.417 ± 40.25± 31± 42 42 35 42 28 34 20 70 196 91 35 98 ± 69.297 47.910 3.5 9.310 52.5 ± 73.333 ± 72.5± 68.333 ± 49 xx xx xx 35 140 45 80 98 56 56 4.950 57.951 20.421 32.860 44.333 ± 38.5± 42 ± 34 ± 70.667 ± 38.33 ± 73.333 ± 151.33 ± 75.667 ± 46.667 35 ± 4.042 14 9.900 0 5.568 60.078 16.073 5.774 49.572 17.898 ±10.69 Phosphorous (mg/l) 12.5 ± 22.043 ± 12 12 23.5 13 60 70 8 37.8 ± 31.79 9.5 24.5 0.5 29 15.9 ± 13.21 8.59 21.91 35.0 ± 10.5 ± 20.8 ± 22.08 ± 3 4.5 17.5 0.5 4 25 12.5 4.0 6 70 3 53.73 10.9 32.86 34.99 106.3 ± 27.8 ± 8.0 ± 36.44 ± 100 xx xx xx 40 42.5 1.0 0.5 1.5 14 16 8.84 23.27 8.13 42.67 8.25± 20.5± 6.75± 45.8± 7.2 ± 4.7 ± 10.7 ± 28.2 ± 16.0 ± 38.3 ± 53.59 34.7 ± 28.38 5.30 4.24 8.84 22.68 5.8 4.54 4.54 36.85 13.0 Potassium (mg/l) 1832.5 ± 513.75 ± 385 ± 910.417 ± 6400 700 150.0 1800 10 210 35 20 25 95 1400 1683.380 862.104 677.532 1828.762 5297.5 ± 1413.75 ± 2605± 3105.417 ± 20550 0 400.0 1650 0 3885 120 1830 35 185 8370 5549.816 1810.651 3928.407 6015.647 7412.5 ± 68.333 ± 1481.25 3252.727± 27800 450 100.0 xx 25 150 30 150 30 285 5460 7624.979 70.770 ±2654.55 8296.386 18250 ± 383.33 ± 216.67 ± 1725 ± 11.667 ± 1415 ± 61.67 ± 666.67 ± 188.33 ± 5076.67 ± 30 ± 5 10883.82 354.730 160.728 106.066 12.583 2139.29 50.58 1009.57 95.044 3500.78 89 Table 2.3. Physico- chemical characteristics of water samples from habitats of Bruguiera cylindrica. PRE MONSOON MONSOON POST MONSOON Seasonal Annual Seasonal Seasonal Apr May Mean ± Jun Jul Aug Sep Oct Nov Dec Jan Mean ± Mean ± Mean ± SD SD SD SD Water pH 7.665 ± 7.095 ± 7.65 ± 7.47 7.72 7.06 7.47 6.96 6.91 7.04 7.57 7.64 7.66 7.73 0.419 0.256 0.066 ± 0.379 7.953 ± 7.395 ± 7.9 ± 7.7492 ± 7.75 7.81 7.13 7.15 8.23 7.07 7.61 7.98 8 8.01 0.215 0.558 0.194 0.420 7.505 ± 6.423 ± 7.463 ± 7.1256 ± xx xx xx 6.81 6.23 6.23 6.59 7.04 7.62 8.6 0.332 0.335 0.868 0.776 7.735 ± 0.021 7.435 ± 0.53 7.3 ± 0.240 6.973 ± 0.170 7.123 ± 1.017 6.78 ± 0.477 7.257 ± 0.578 7.553 ± 0.476 7.76 ± 0.209 8.113 ± 0.444 Turbidity (NTU) 6.975 ± 4.725 ± 9.25 ± 6.983 + 3.4 7 4 7.7 2.1 5.1 5.5 12.1 15.4 4 5.258 2.339 5.403 4.551 17.4 ± 21.675 ± 22.9 ± 20.658 + 26.1 22.8 25.7 23.7 1.7 35.6 18.2 14.3 44.4 14.7 8.983 14.297 14.44 11.861 2.75 ± 4.267 ± 5.95 ± 4.678 + xx xx xx 3.6 4.6 4.6Ta 12.3 3.4 4.5 3.6 1.626 0.577 4.260 3.004 14.75 ± 16.051 14.9 ± 11.172 14.85 ± 15.344 11.667 ± 10.621 2.8 ± 1.572 15.1 ± 17.755 12 ± 6.355 9.933 ± 5.764 21.433 ± 20.623 7.433 ± 6.296 T.S (mg/l) 23166.67 34200 ± 6000 ± 29300 ± 33400 23200 12800 1000 4000 6200 20400 21400 36000 39400 ± 7984.999 5009.325 9806.8 14682.29 25933.33 45400 ± 5000 ± 27400 ± 42600 42600 2200 3800 11600 2400 12400 18800 38400 40000 ± 4156.922 4457.204 13889.08 18991.35 26555.56 45800 ± 1200 ± 35950 ± xx xx xx 2200 400 1000 2000 40000 51200 50600 ± 3676.955 916.515 23210.56 24119.03 38000 ± 32900 ± 7500 ± 5333.33 ± 26733.33 ± 41866.67 ± 43333.33 ± 2333.33 ± 1404.754 3200 ± 2690.725 11600 ± 9226.05 6505.382 13717.87 7495.332 5717.808 11562.58 8171.495 6300.265 T.D.S (ppt) 32.85 ± 5.65 ± 28.05 ± 22.183 31.2 22.6 12.4 1.0 3.2 6.0 19.4 19.6 34.6 38.6 7.743 4.943 10.007 ± 14.27 37.85 ± 4.15 ± 26.95 ± 22.983 ± 39.4 24.0 2.0 2.0 10.6 2.0 12.2 18.8 38.4 38.4 9.497 4.3 13.493 17.157 90 45.7 ± 1.667 ± 34.55 ± 26.067 ± xx xx xx 2.0 2.0 1.0 1.6 40.0 47.0 49.6 3.818 0.577 22.338 23.337 35.3 ± 5.798 23.3 ± 0.99 7.2 ± 7.354 1.667 ± 0.578 5.267 ± 4.658 3 ± 2.646 11.067 ± 8.954 26.133 ± 12.016 40 ± 6.353 42.2 ± +6.409 T.S.S (mg/l) 1350 ± 350 ± 1250 ± 983.333 ± 2200 600 400 0 800 200 1000 1800 1400 800 869.866 341.565 443.471 715.838 7550 ± 850 ± 450 ± 2950 ± 3200 18600 200 1800 1000 400 200 0 0 1600 7680.929 718.7953 772.442 5288.15 100 ± 733.33 ± 1400 ± 888.889 ± xx xx xx 2000 200 0 400 0 4200 1000 141.421 1101.514 1911.369 1403.96 666.67 ± 2700 ± 707.107 9600 ± 12727.92 300 ± 141.421 1266.67 ± 1101.514 200 ± 200 533.33 ± 416.333 600 ± 1039.23 1866.67 ± 2138.535 1133.33 ± 416.333 416.333 Salinity (ppt) 28.028 ± 5.152 ± 22.888 ± 18.689 ± 28.39 18.5 10.73 1.043 4.412 4.422 16.99 17.92 25.92 30.72 6.656 4.045 6.583 11.538 51.095 ± 6.618 ± 35.188 ± 30.967 ± 51.72 51.07 1.596 6.582 14.91 3.382 17.55 25.9 47.31 49.99 0.782 5.901 15.952 21.177 37.35 ± 0.295 ± 28.49 ± 21.061 ± xx xx xx 0.098 0.394 0.394 1.139 32.81 38.69 41.32 0.198 0.171 18.578 19.623 40.055 ± 16.497 34.785 ± 23.031 6.163+6.459 2.574+3.503 6.572+7.495 2.733+2.091 11.893+9.318 25.543+7.451 37.307+10.762 40.677+9.651 Resistivity (Ω) 24.4 ± 200.41 ± 29.36 ± 84.723 ± 23.07 33.88 55.74 490.8 127.5 127.6 36.25 34.88 24.84 21.47 6.452 196.531 7.317 133.658 19.128 ± 207.938 ± 33.428 ± 86.831 ± 18.9 19.11 328.8 148.3 65.65 289 55.78 37.75 20.64 19.54 0.296 122.449 17.075 110.481 17.995 ± 2514.67 ± 127.498 ± 898.887 ± xx xx xx 5030 1256 1258 456 20.16 17.35 16.48 0.092 2178.343 219.007 1635.489 192.27 ± 483.05 ± 182.677 ± 20.985 ± 2.949 26.495 ± 10.444 1889.7 ± 2724.966 558.2 ± 611.392 30.93 ± 9.437 20.943 ± 3.754 19.163 ± 2.516 193.083 670.108 236.9063 Conductivity (mS) 41.833± 8.717 ± 34.94 ± 28.496 ± 42.39 28.84 17.53 1.995 7.676 7.666 26.96 28.04 39.24 45.52 9.066 6.456 8.976 16.67 51.095 ± 6.961± 35.188 ± 31.081 ± 51.72 51.07 2.971 6.582 14.91 3.382 17.55 25.9 47.31 49.99 0.782 5.54 15.952 21.007 54.3 ± 0.583 ± 41.586 ± 30.744 ± xx xx xx 0.194 0.779 0.777 2.143 48.49 56.38 59.33 0.198 0.337 26.69 28.387 47.055 ± 6.597 39.955 ± 15.719 10.251 ± 10.295 2.924 ± 3.294 7.788 ± 7.066 3.942 ± 3.478 15.551 ± 12.529 34.143 ± 12.471 47.643 ± 8.575 51.613 ± 7.047 Acidity (Mg/l) 91 33+ 20.35+ 34.65+ 29.333 + 35.2 39.6 22 8.8 22 28.6 48.4 24.2 35.2 30.8 5.680 8.305 10.221 10.031 30.8+ 23.65+ 31.24+ 28.563 + 26.4 39.6 13.2 28.6 35.2 17.6 48.4 1.76 26.4 48.4 6.221 10.062 22.222 13.64 57.2+ 30.8+ 39.6+ 40.578 + xx xx xx 17.6 44 30.8 44 57.2 35.2 22 6.223 13.2 14.813 15.365 30.8 ± 6.223 39.6+0 17.6+6.223 18.333+9.920 33.733+11.073 25.67+7.07 46.933+2.54 27.72+27.887 32.267+5.081 33.733+13.442 Alkalinity (Mg/l) 175 ± 153.75+ 152.5 ± 160.417 ± 190 160 130 150 205 130 160 130 160 160 31.091 35.444 15 27.998 160 ± 143.75+ 182.5 ± 162.083 ± 160 160 80 225 150 120 270 110 140 210 8.165 61.288 71.822 52.2 450+ 270 xx xx 170 ± 0 xx 90 200 1060 180 200 180 180 185 ± 10 531.131 ± 298.035 175 ± 21.213 160 ± 0 105 ± 35.355 155 ± 67.639 185 ± 30.414 436.67 ± 539.846 203.33 ± 58.595 146.67 ± 47.258 160 ± 20 183.33 ± 25.166 Hardness (Mg/l) 5875 ± 906.5 ± 3065 ± 3282.17 ± 6100 3920 2760 128 364 374 740 680 4880 5960 1369.708 1240.885 2754.941 2741.46 7110 ± 316.5 ± 1980.5 ± 3135.67 ± 7260 7380 460 330 240 236 340 800 62 6720 247.386 105.051 3174.289 3447.724 6830 ± 53.333 ± 3587.5 ± 3130 xx xx xx 30 68 62 170 800 5200 8180 1173.797 20.429 3792.127 ± 3555.53 1610 ± 6680 ± 820.244 5650 ± 2446.589 162.67 ± 152.975 224 ± 148.647 224 ± 156.346 416.67 ± 292.632 760 ± 69.282 3380.67 ± 2878.5 6953.3 ± 1128.243 1626.346 Calcium (Mg/l) 412.505 ± 126.598 ± 328.483 ± 289.195 ± 400.5 352.4 304.38 23.25 138.68 40.08 192.38 200.4 376.47 544.68 46.494 128.994 167.305 168.718 544.665 ± 34.553 ± 288.423 ± 289.213 ± 480.6 768.9 40.05 34.07 36.84 27.25 120.24 208.42 392.49 432.54 150.251 5.447 148.645 243.933 508.635 ± 16.167 ± 486.87 ± 334.806 ± xx xx xx 6.01 18.44 24.05 28.86 300.6 496.62 1121.4 5.664 9.232 464.469 371.638 172.215 ± 64.653 ± 440.55 ± 56.639 560.65 ± 294.51 21.11 ± 14.152 30.46 ± 8.483 113.827 ± 81.948 236.47 ± 55.68 421.86 ± 65.238 699.54 ± 369.619 186.91 64.766 Magnesium (Mg/l) 1179.6± 143.768± 546.568± 623.312 ± 1241.7 740.1 486.93 17.05 4.38 66.71 63.3 43.82 959.25 1119.9 306.564 230.351 573.097 572.688 1399.92± 56.075± 680.478± 712.159 ± 1475.4 1329.3 87.65 59.69 36.06 40.9 9.74 68.17 1270.9 1373.1 60.234 23.388 742.324 693.053 1353.7± 3.18± 577.488± 558.543± xx xx xx 3.65 5.4 0.49 23.86 12.17 964.12 1309.8 289.207 2.489 661.275 669.587 1358.55±165.251 1034.7±416.627 287.29±282.334 26.797±29.264 15.28±18.003 36.03±33.377 32.3±27.76 41.387±28.079 1064.757±178.54 1267.6±131.77 92 Chloride (Mg/l) 19081.25± 4529.8± 13188.25± 12266.43± 19028 13348 10082 994 3976 3067.2 9230 12141 11005 20377 4079.206 3906.179 4939.945 7370.04 13144.68 24234.67± 3139.975± 14831.9± 25560 24282 3266 2279.1 5396 1618.8 5722.6 10508 19880 23217 ± 1349.623 1649.304 8113.131 9949.87 459.133± 17182± 11833.93± xx xx 24566 xx 269.8 426 681.6 1917 22436 24140 20235 207.89 10301.45 11850.96 22294±4618.821 18815±7731.506 6674±4819.64 1180.967±1017.614 3266±2559.941 1789.2±1201.894 5623.2±3657.513 15028.33±6466.979 18341.67±6701.262 21276.33±1682.166 Sulphate (Mg/l) 77.75± 23.625± 52.125± 51.167 ± 126 62 38.5 8.5 25 22.5 45.5 43 60 60 32.17 12.291 9.15 29.655 90± 25± 49.25± 54.75 128 63 15 30 36 19 42 57 51 47 33.357 9.695 6.344 ±33.537 89.25± 6.1667± 50± 44.111 + xx xx xx 2 10 6.5 30 49 60 61 40.659 4.01 14.399 36.82 127±1.414 62.5±0.707 26.75+±16.617 13.5±14.654 23.667±13.051 16±8.411 39.167±8.129 49.667±7.024 57±5.196 56±7.81 Sodium (ppt) 20.613± 2.816± 16.435± 13.288 ± 20.9 11.7 4.7 0.71 2.715 3.14 10.92 11.02 21.4 22.4 6.422 1.643 6.324 9.267 25.138± 18.199± 15.523 ± 24.65 23.55 4 2.555 5.035 1.34 3.2325±1.621 6.425 10.47 21.8 34.1 1.465 12.439 11.604 28.85± 0.108± 22.143± 16.289 ± xx xx xx 0.05 0.13 0.145 0.875 31.1 26.55 30.05 1.344 0.051 14.312 15.225 22.775±2.652 17.625±8.379 4.35±0.495 1.105±1.298 2.627±2.454 1.542±1.508 6.073±5.032 17.53±11.755 23.25±2.865 28.85±5.942 Nitrogen (mg/l) 47.25± 32± 104.75± 61.333 ± 42 49 35 27 41 25 80 210 80 49 6.702 7.394 71.672 49.986 26.5± 77.25± 48.583 ± 42 42 42±0 35 15 32 24 80 110 63 56 8.963 24.047 25.914 41± 30.75± 90± 55.091 ± 39 xx xx 17 34 42 91 140 49 80 7.211 12.767 37.78 35.43 41±1.732 45.5±4.95 33.333±0 19.667±6.429 35.667±4.726 30.333±10.116 83.667±6.351 153. 33±51.316 64±15.524 61.667±16.258 93 Phosphorous (mg/l) 5.85± 58.0± 15.38± 26.4 1.5 0.3 21.5 3.0 170 50 9.0 5.0 12.0 25 19.5 10.45 77.53 8.73 ± 47.44 73.0± 47.13± 6.15± 42.09 102.5 55 19.5 58.0 60 65 5.5 5.0 9.5 0.1 10 44.05 27.91 4.62 ± 39.67 108.75± 23.83± 7.0± 35.23 105 xx xx xx 15 32.5 24.0 14.0 7.5 0.09 6.5 5.3 8.75 5.69 ± 42.8 69.7±59.05 27.65±38.68 20.5±1.41 30.5±38.89 81.7±79.74 49.17±16.27 12.8±9.83 8.0+5.2 9.7+2.26 8.4+14.38 12.0+6.73 Potassium (mg/l) 300± 363.75± 272.5± 312.083± 250 0 700 1300 0 70 85 460 380 100 150 291.548 625.265 174.619 373.786 237.5± 518.75± 448.75± 401.667 ± 300 200 100 1800 75 185 15 295 350 300 850 110.868 857.063 268.65 488.836 252.5± 211.667 ± 300 xx xx 425± 176.777 xx 20 10 15 15± 5 10 100 350 550 245 230.516 283.33±28.868 100±141.421 400±424.264 1550±353.553 31.67±38.837 88.33±88.929 38.33±40.415 255±227.651 276.667±153.731 250±132.288 516.667±351.189 94 Table 2.4. Physico- chemical characteristics of water samples from habitats of Excoecaria agallocha. PRE MONSOON MONSOON POST MONSOON Seasonal Seasonal Seasonal Annual Apr May Mean± Jun Jul Aug Sep Mean± Oct Nov Dec Jan Mean± Mean± SD SD SD SD Water pH 7.59± 6.99± 7.588± 7.389± 7.73 6.81 7.34 6.9 6.73 6.99 7.57 7.46 7.55 7.77 0.529 0.257 0.131 0.431 6.945± 6.67± 7.115± 6.91 6.98 6.97 7.07 7.22 6.4 5.99 6.7 6.83 7.22 7.71 0.155 0.577 0.454 ± 0.436 7.28± 5.73± 7.268± 6.758 ± xx xx xx 6.81 5.32 5.06 6.6 7.03 8.31 7.13 0.269 0.944 0.732 1.014 7.263±0.638 7.355±0.53 6.89±0.113 7.205±0.191 6.977±0.216 6.15±0.738 6.013±0.965 6.957±0.534 7.107±0.322 7.693±0.559 7.537±0.354 Turbidity (NTU) 5.125± 3.675± 14.65± 7.817 ± 2.6 9.1 5.3 2.9 2.1 4.4 8.1 9.7 36.7 4.1 3.186 1.443 14.888 9.468 4.625± 13.45± 10.55± 9.542 ± 5.9 7 26.9 9 4.1 13.8 3.7 7 9.9 21.6 2.334 9.802 7.79 7.678 3± 3.7± 8.5± 5.678 ± xx xx xx 7.1 2.5 1.5 13 9.6 2.9 8.5 1.131 2.987 4.196 4.029 2.867±0.907 4.25±2.334 8.05±1.485 16.1±15.27 6.333±3.121 2.9±1.058 6.567±6.423 8.267±4.652 8.767±1.531 16.5±17.84 11.4±9.103 T.S (mg/l) 35850± 5050± 29600± 23500 ± 36000 26200 10200 3600 1800 4600 20200 23000 37000 38200 6859.3 3623.534 9320.944 15260.53 10433.33 19450± 1150± 10700± 21800 8200 1800 800 1000 1000 5000 3000 13200 21600 ± 7569.016 443.471 8501.765 9814.214 44700± 333.33± 28700± 22800 ± xx xx xx 400 200 400 1800 40400 44600 28000 1555.635 115.470 19268.28 21589.81 35533.33±10545.77 28900±10040.92 17200±12727.92 6000±5939.697 1600±1743.56 1000±800 2000±2271.563 9000±9830.565 22133.33±18715.06 31600±16381.7 29266.67±8372.176 T.D.S (ppt) 34.8± 4.85± 28.45± 22.7 ± 34.6 25.0 10.2 3.4 1.8 4.0 19.8 21.8 34.8 37.4 6.995 3.686 8.934 14.831 0.85± 10.55± 9.867 ± 20.8 7.8 18.2±6.965 1.0 0.6 1.0 0.8 5.0 2.8 13.0 21.4 0.192 8.458 9.367 41.4± 0.267± 26.8± 21.2 ± xx xx xx 0.2 0.2 0.4 1.4 39.4 38.6 27.8 5.94 0.116 17.74 20.111 32.733±9.521 27.7±9.758 16.4±12.162 5.6±6.505 1.4±1.744 1±0.8 1.733±1.973 8.733±9.752 21.33±18.305 28.8±13.815 28.867±8.053 95 T.S.S (mg/l) 1050± 200± 1150± 800 ± 1400 1200 0 200 0 600 400 1200 2200 800 574.456 282.843 772.442 687.552 1250± 300± 150± 566.667 ± 1000 400 800 200 0 200 0 200 200 200 680.686 346.41 100 648.542 1600 3300± 66.667± 1900± xx xx xx 200 0 0 400 1000 6000 200 ±2626.785 4384.062 115.47 2754.39 2800±3218.695 1200±282.843 800±565.686 400±565.686 200±0 0±0 266.67±305.505 266.667±230.94 800±529.15 2800±2946.184 400±346.41 Salinity (ppt) 28.97± 4.465± 23.768± 19.067 ± 29.7 20.08 8.285 3.268 3.164 3.142 17.66 19.17 26.86 31.38 6.135 2.547 6.48 12.03 15.9133± 0.79± 8.884± 8.529 ± 18.12 6.713 1.050 0.744 0.87 0.494 4.137 2.277 11.51 17.61 6.195 0.234 7.053 8.106 37.135± 0.102± 23.092± 18.55 ± xx xx xx 0.1289 0.131 0.045 0.538 32.74 35.04 24.05 0.106 0.049 15.763 17.818 23.91±8.188 13.397±9.452 4.6675±5.116 1.38±1.664 1.389±1.581 1.227±1.674 7.445±9.028 18.062±15.262 24.47±11.946 24.347±6.89 Resistivity (Ω) 23.39± 146.5± 28.32± 66.07 22.12 31.4 70.6 168.4 173.1 173.9 35.4 32.64 24.1 21.14 5.432 50.658 6.786 ±65.219 46.255± 693.575± 114.333± 284.721 ± 34.59 85.67 489.1 683.5 587.7 1014 135 234.7 52.06 35.57 26.314 227.884 91.281 329.615 18.045± 6609.67± 249.025± 2317.91 ± xx xx xx 3809 3750 12270 930.2 20.13 19.05 26.72 0.021 4902.08 454.129 4056.43 28.355±8.818 58.535±38.375 279.85±295.924 1553.633±1970.112 1503.6±1956.453 4485.97±6754.245 366.867±490.396 95.823±120.433 31.737±17.781 27.81±7.277 Conductivity (mS) 43.263± 7.73± 36.083± 29.025 ± 44.2 31.19 13.85 5.8 5.65 5.62 27.61 29.91 40.55 46.26 8.341 4.081 8.821 17.363 25.03± 1.514± 14.433± 13.659 ± 28.27 11.42 1.998 1.431 1.663 0.964 7.241 4.17 18.82 27.5 9.159 0.434 10.757 12.464 54.175± 0.199± 34.41± 27.399 ± xx xx xx 0.257 0.261 0.079 1.051 48.58 51.42 36.59 0.092 0.104 23.15 26.119 44.657±11.925 36.235±11.264 21.305±13.98 7.924±8.381 2.496±2.921 2.525±2.796 2.221±2.977 11.967±13.896 27.553±22.299 36.93±16.599 36.783±9.382 Acidity (Mg/l) 37.95± 28.6± 37.4± 34.65 30.8 48.4 26.4 35.2 35.2 17.6 44 30.8 48.4 26.4 9.736 8.425 10.474 ± 9.755 34.1± 23.1± 24.2± 27.133 ± 39.6 30.8 22 11 30.8 28.6 22 17.6 22 35.2 9.756 8.891 7.621 9.49 50.6± 22± 46.75± 39.356 ± xx xx xx 17.6 30.8 17.6 48.4 63.8 8.8 66 9.334 7.621 26.484 21.456 35.2±6.222 39.6±12.445 24.2±3.111 21.267±12.51 32.267±2.54 21.267±6.351 38.133±14.144 37.4±23.797 26.4±20.163 42.533±20.79 96 Alkalinity (Mg/l) 172.083 180± 163.75± 172.5± 150 190 120 130 215 190 210 130 200 150 ± 21.603 46.075 38.6221 34.076 122.083 157.5± 97.5± 111.25± 180 170 100 60 160 70 85 90 130 140 ± 20.616 45 27.8014 39.969 150.556 195± 110± 158.75± xx xx xx 100 100 130 160 165 150 160 ± 21.213 17.321 6.2915 35.920 166.667±23.094 165±21.213 180±14.142 110±14.142 96.667±35.119 158.33±57.518 130±60 151.67±62.915 128.33±37.528 160±36.06 150±10 Hardness (Mg/l) 3279.667 5960± 769± 3110± 6000 4400 2200 282 316 278 700 640 4940 6160 ± 1124.752 954.152 2861.258 2782.29 1736.917 3460± 258.75± 1492± ± 3860 1400 700 115 154 66 180 68 2300 3420 1411.099 296.361 1645.111 1789.164 3124.89 7560± 50.667± 3213± xx xx xx 36 94 22 102 850 6600 5300 ± 141.421 38.175 3219.184 3514.90 6433.33±1617.694 4930±1513.209 2900±2121.32 1450±1060.66 144.33±125.596 188±114.839 122±136.88 327.33±325.087 519.33±404.724 4613.33±2168.533 4960±1401.285 Calcium (Mg/l) 273.321 410.513± 102.783± 306.667± 392.49 320.4 256.32 49 51.3 54.51 213.23 236.47 352.44 424.53 ± 69.33 102.383 99.407 157.128 130.838 232.303± 40.048± 120.163± 264.33 120.2 120.15 10.42 19.2 10.42 46.49 25.65 176.22 232.29 ± 79.271 53.562 100.125 109.603 580.725± 6.945± 304.14± 266.538± xx xx xx 7.214 7.21 6.41 6.81 320.64 416.52 472.59 141.598 0.463 207.912 263.387 485.94±188.59 328.41±90.623 220.3±141.563 188.235±96.287 22.211±23.255 25.903±22.797 23.78±26.688 88.843±109.534 194.25±151.959 315.06±124.435 376.47±127.155 Magnesium (Mg/l) 632.381 1201.428± 124.905+ 570.81+ 1222.2 876.47 379.81 39.47 45.77 34.57 40.9 12.17 988.47 1241.7 + 233.037 169.999 637.029 588.34 343.348 701.18± 38.653+ 290.21+ 779.09 267.81 97.39 21.68 25.8 9.74 15.58 0.97 452.85 691.44 + 296.27 39.746 339.862 370.431 598.789 1487.57± 8.1167+ 597.403+ xx xx xx 4.39 18.5 1.46 20.69 12.17 1353.67 1003.08 + 51.647 9.111 685.957 710.721 1270.79±291.141 1000.645±313.326 572.14±430.388 238.6+199.701 21.847+17.541 30.023+14.117 15.257+17.231 25.723+13.389 8.437+6.466 931.66+453.089 978.74+275.936 97 Chloride (Mg/l) 13107.78 20412.5+ 3983.1+ 14927.75+ 19312 16614 8520 2130 2485 2797.4 8804 12780 17395 20732 + 3037.55 3036.864 5224.614 7959.909 7669.775 12283+ 1652.525+ 9073.8+ 13490 6816 4686 617.7 908.8 397.6 3280.2 2485 9372 21158 + 3772.143 2033.125 8623.512 6849.184 13166.84 25702+ 379.533+ 16489.75+ xx xx xx 227.2 568 343.4 1349 25205 23075 16330 + 602.455 173.25 10779.44 12237.16 5474.525 16401+4116.776 11715+6928.232 6603+2711.047 991.633+1005.003 1320.6+1022.696 1179.467+1401.433 4477.733+3869.085 13490+11376.63 16614+6884.804 19406.67+2672.972 Sulphate (Mg/l) 78.375+ 24.875+ 54+ 52.417+ 128 62.5 36 20.5 20 23 47 46 63 60 33.089 7.532 8.756 29.271 69+ 5.688+ 31.125+ 35.27+ 63 41 9 4.25 5 4.5 26.5 16 38.5 43.5 33.892 2.23 12.352 33.082 87+ 3.5+ 47.75+ 41.722 + xx xx xx 3 7 0.5 23.5 50.5 57 60 36.77 3.279 16.646 36.799 31.565 95.5+45.962 51.75+15.203 22.5+19.092 9.25+9.763 10.67+8.145 9.333+12.004 32.33+12.79 37.5+18.755 52.833+12.77 54.5+9.526 Sodium (ppt) 22.538+ 2.36+ 18.01+ 14.303 + 21.65 13.95 2.75 2.38 1.98 2.33 11.72 12.27 19.9 28.15 6.317 0.315 7.722 10.426 15.45+ 1.086+ 8.804+ 8.447 + 15.65 3.7 3.25 0.36 0.45 0.285 3.055 2.01 6.6 23.55 9.853 1.444 10.025 9.594 26.9+ 0.373+ 18.048+ 14.123+ xx xx xx 0.075 0.95 0.095 0.34 29.8 23.4 18.65 1.414 0.5 12.658 13.409 18.65+4.243 8.825+7.248 3+0.354 0.938+1.257 1.127+0.78 0.903+1.239 5.038+5.944 14.693+14.053 16.633+8.864 23.45+4.751 98 Nitrogen (mg/l) 69.75 38.5+ 84+ 86.75+ 49.0 28.0 35.0 42.0 35.0 220.0 39.0 91.0 130.0 70.0 56.0 + 9.037 90.712 32.222 55.531 44.75+ 67.75+ 81.25+ 64.583 + 42.0 42.0 49.0 35.0 22.0 175.0 39.0 80.0 140.0 56.0 49.0 3.403 71.867 41.355 46.108 42+ 53+ 81.75+ 63.333 + 35.0 xx xx xx 22.0 98.0 39.0 98.0 110.0 70.0 49.0 9.9 39.887 27.524 31.898 42+7 35+9.9 42+9.9 38.5+4.95 26.33+7.506 164.333+61.696 39+0 89.667+9.074 126.67+15.275 65.333+8.083 51.333+4.042 Phosphorous (mg/l) 18.24 41.3+ 6.55+ 6.875+ 80 60 25 0.7 4.0 12.5 9.0 4.0 11.5 4.0 8.0 + 35.6 5.23 3.61 25.43 20.2 16.3+ 37.875+ 6.525+ 1 6 23 4.0 85 47.5 15.0 1.5 15.0 0.6 9.0 + 15.73 36.44 6.79 25.09 75.0+ 48.833+ 21.625+ 42.56 + 40 xx xx xx 80 60.0 6.5 1.5 75.5 5.5 4.0 49.5 38.00 35.96 40.61 40.33+39.5 33.0+38.18 24.0+1.41 2.35+2.34 56.33+45.4 40 +24.62 10.17+4.37 2.33+1.44 34.0+35.98 3.37+2.51 7.0+2.65 Potassium (mg/l) 325+ 426.25+ 410+ 387.083 + 400.0 100.0 450.0 1550.0 60.0 40.0 55.0 470.0 520.0 150.0 500.0 155.456 749.215 174.547 412.478 387.5+ 431.25+ 228.75+ 349.167+ 200.0 50.0 900.0 1700.0 5.0 5.0 15.0 85.0 30.0 500.0 300.0 370.53 845.847 215.111 503.433 375+ 67.5+ 120 + 250.0 xx xx xx 15.0 20.0 25.0 20+ 5 20.0 100.0 150.0 0 176.777 69.941 164.716 283.333+104.08 75+35.355 675+318.198 1625+106.066 26.667+29.297 21.667+17.559 31.667+20.817 191.667+243.225 216.667+265.016 266.667+202.073 266.667+251.661 99 Table 2.5. Physico- chemical characteristics of water samples from habitats of Rhizophora mucronata. PRE MONSOON MONSOON POST MONSOON Seasonal Seasonal Seasonal Annual Apr May Mean+ Jun Jul Aug Sep Mean+ Oct Nov Dec Jan Mean+ Mean+ SD SD SD SD Water pH 7.383 7.595+ 6.98+ 7.575+ 7.74 6.88 7.43 7.01 6.4 7.08 7.33 7.3 7.91 7.76 + 0.481 0.428 0.306 0.477 7.108+ 6.717+ 7.157+ 6.994 + 7.11 7.07 6.95 7.18 6.48 6.26 6.83 6.91 7.13 7.76 0.052 0.421 0.421 0.374 7.74+ 5.652+ 7.74+ 6.98+ 7.31 xx 7.64 7.1 3.97 3.9 7.34 7.93 7.89 7.8 0.375 1.995 0.272 1.534 7.387+0.322 6.975+0.134 7.34+0.353 7.097+0.085 5.617+1.426 5.747+1.651 7.166+0.291 7.38+0.514 7.643+0.444 7.773+0.023 Turbidity (NTU) 5.875+ 7.7+ 15.475+ 9.683 + 3.2 9.4 4 12.4 7.1 7.3 11.6 25.6 9.4 15.3 3.699 3.478 7.175 6.322 5.35+ 12.45+ 4.45+ 7.417 + 5.6 11.5 21.2 5.3 12.6 10.7 6.6 5.5 3.1 2.6 4.453 6.602 1.912 5.679 18.733+ 21.025+ 23.6+ 21.3364 + 35.3 xx 60.3 12.7 0.6 10.5 10.5 30.9 25.3 27.7 14.492 26.707 9.029 16.869 14.7+17.88 10.45+1.484 28.5+28.851 10.133+4.188 6.767+6.006 9.5+1.907 9.567+2.624 20.667+13.399 12.6+11.44 15.2+12.55 T.S (mg/l) 4450+ 30150+ 23533.33 36000+ 38600 25600 10000 1800 3600 2400 3774.91 20800 22200 37000 40600 10111.8 + 6964.673 7 7 15807.09 14400+ 21250+ 500+ 12050 + 25800 6200 600 400 400 600 13200 2200 17000 25200 9551.26 10055.02 115.47 11565.19 5 39933.33 6500+ 38100+ 27109.09 39200 xx + 22200 2600 400 800 10510.3 16200 56000 41600 38600 16457.2 + 702.376 1 2 19545.92 34533.33+7569.23 15900+13717.8 10933.33+10830. 1600+1113.55 1466.667+1847.52 1266.667+986.57 16733.33+3827.96 26800+27193.3 31866.67+13078.7 34800+8373.76 6 7 2 3 1 6 7 8 4 9 T.D.S (ppt) 34.9+ 3.65+ 29.15+ 22.567+ 36.0 25.6 9.6 1.2 2.6 1.2 19.8 20.6 37.0 39.2 6.378 4.021 10.378 15.68 20.2+ 0.4+ 13.5+ 11.367 + 23.6 6.0 0.6 0.2 0.4 0.4 9.8 2.0 17.0 25.2 9.514 0.163 9.917 11.193 39.267+ 6.35+ 34.45+ 25.546+ 39.2 xx 22.2 2.2 0.4 0.6 15.8 45.8 37.6 38.6 0.702 10.597 12.958 17.882 32.933+8.239 15.8+13.859 10.8+10.85 1.2+1 1.133+1.270 0.733+0.416 15.133+5.033 22.8+21.982 30.533+11.724 34.333+7.915 100 T.S.S (mg/l) 1100+ 800+ 1000+ 966.667 + 2600 0 400 600 1000 1200 1000 1600 0 1400 1113.553 365.148 711.805 727.803 1050+ 100+ 900+ 683.33+ 2200 200 0 200 0 200 3400 200 0 0 1112.055 115.470 1669.331 1136.048 666.666+ 1563.636 150+ 3650+ 0 xx 7 0 400 0 200 400 10200 4000 0 + 191.485 4722.641 1154.701 3122.586 1006.64 1333.333+2309.40 1600+1400 100+141.421 133.333+230.94 400+200 333.333+577.35 533.333+577.35 1600+1587.451 4000+5414.795 466.667+808.29 1 Salinity (ppt) 28.875+ 4.137+ 23.765+ 18.927+ 29.77 19.67 8.339 1.965 3.129 3.116 17.57 19.13 27.22 31.15 6.33 2.853 6.489 12.194 17.37+ 0.409+ 11.679+ 9.819 + 20.93 5.241 0.467 0.598 0.327 0.247 8.537 1.85 15.05 21.28 8.094 0.155 8.367 9.547 34.83+ 5.46+ 27.112+ 21.343+ 35.62 xx 18.8 1.592 0.708 0.743 12.72 30.01 32.72 33 0.703 8.902 9.689 14.86 28.773+7.395 12.455+10.202 9.202+9.196 1.385+0.706 1.388+1.519 1.3687+1.533 12.942+4.520 16.996+14.2 24.996+9.042 28.477+6.31 Resistivity (Ω) 173.392 23.52+ 28.232+ 75.048 + 22.09 31.98 70.17 273.3 174.4 175.7 + 35.47 32.56 23.73 21.17 5.725 6.862 84.722 82.951 1344.55 49.125+ 105.983+ 499.885 + 30.32 107.7 1062 833.2 1506 1977 + 68.94 284.3 40.76 29.93 39.053 120.01 681.066 505.757 440.142 19.203+ 27.337+ 175.23+ 18.83 xx 33.47 327.8 714 685.3 + 47.12 21.92 20.17 20.14 0.323 13.214 274.747 323.06 798.133+669.77 112.9267+148.50 23.747+5.921 69.84+53.542 388.547+583.516 478.1+308.73 946+928.517 50.51+16.99 28.22+11.004 23.7467+5.379 4 9 Conductivity (mS) 43.137+ 7.166+ 36.187+ 28.83+ 44.28 30.55 13.93 3.576 5.595 5.566 27.54 29.99 41.1 46.12 8.665 4.606 8.869 17.677 27.051+ 1.079+ 18.579+ 15.57 + 32.25 9.077 1.998 1.176 0.648 0.495 14.22 3.438 23.99 32.67 11.996 0.678 12.597 14.499 50.88+ 8.7622+ 40.6+ 31.826+ 51.76 xx 29.27 2.984 1.369 1.426 20.71 44.6 48.49 48.6 0.762 13.692 13.389 21.508 42.763+9.843 19.813+15.183 15.066+13.671 2.578+1.250 2.537+2.672 2.495+2.699 20.823+6.66 26.009+20.867 37.86+12.567 42.463+8.571 Acidity (mg/l) 42.9+ 24.2+ 37.4+ 34.833+ 39.6 61.6 17.6 13.2 48.4 17.6 57.2 26.4 30.8 35.2 13.138 16.266 13.680 15.409 29.7+ 12.1+ 28.6+ 23.467 + 39.6 13.2 13.2 13.2 8.8 13.2 26.4 17.6 30.8 39.6 16.993 2.2 9.159 13.177 33.4 35.2+ 24.75+ 40.7+ 44 xx 26.4 11 26.4 35.2 48.4 39.6 30.8 44 + 11.641 10.061 7.514 11.253 101 41.066+2.54 37.4+34.224 19.067+6.721 12.467+1.270 27.867+19.84 22+11.641 44+15.864 27.8667+11.0731 30.8+0 39.6+4.4 Alkalinity (mg/l) 155+ 192.5+ 167.5+ 171.667 + 140 170 140 250 220 160 200 180 140 150 12.909 51.234 27.537 35.118 140+ 90+ 106.25+ 112.083 + 140 150 140 80 80 60 95 80 100 150 8.165 34.641 30.379 32.714 190+ 92.5+ 155+ 141.818+ 280 xx 110 120 40 100 110 180 170 160 78.102 35.939 31.091 60.302 186.67+80.829 160+14.142 130+17.32 150+88.881 113.333+94.516 106.667+50.332 135+56.789 146.667+57.735 136.667+35.118 153.333+5.773 Hardness (mg/l) 3273.333 5950+ 725+ 3145+ 5980 4140 2100 228 276 296 720 680 4980 6200 + 1278.071 917.110 2866.886 2808.766 3595+ 158.5+ 1804+ 1852.5 + 4200 1140 440 100 60 34 260 56 2900 4000 1664.242 189.619 1954.744 1988.906 3660.182 7360+ 1058+ 3487.5+ 7200 xx 3800 270 80 82 390 700 6140 6720 + 260 1830.17 3408.297 3366.064 1310.31 5793.333+1508.68 138.667+119.35 4673.333+1641.62 2640+2121.32 2113.333+1680.04 199.33+88.551 137.33+139.489 456.667+237.135 478.667+366.176 5640+1443.884 6 3 5 Calcium (mg/l) 100.553 406.51+ 305.865+ 270.975+ 408.51 312.4 264.33 35.27 56.11 46.5 + 210.02 228.46 360.45 424.53 69.939 103.664 158.807 109.516 250.313+ 30.037+ 152.012+ 144.120+ 288.36 96.12 92.12 11.22 9.6 7.21 100.2 19.24 216.27 272.34 103.692 41.421 113.901 125.676 480.6+ 88.22+ 323.48+ 280.781+ 472.59 xx 304.38 23.65 12.83 12.02 144.29 260.52 416.52 472.59 21.192 144.204 149.402 201.405 204.26+152.93 389.82+93.526 220.276+112.779 23.38+12.027 26.18+25.970 21.91+21.43 151.503+55.264 169.407+131.032 331.08+103.305 389.82+104.54 3 Magnesium (mg/l) 1201.475 115.408 579.81+ 632.23+ 1207.6 818.0 + 350.59 34.11 33.11 43.82 + 47.72 26.78 993.34 1251.4 635.348 593.851 270.104 156.862 723.088+ 20.34+ 346.815+ 363.414+ 847.26 219.1 51.13 17.54 8.8 3.89 2.43 1.95 574.58 808.3 344.516 21.288 409.218 410.008 1499.767 203.975 652.493+ 720.47+ 1465.7 xx + 740.13 51.41 11.7 12.66 + 7.3 12.17 1241.7 1348.8 743.481 704.304 72.020 357.915 518.55+423.48 249.769 1173.52+310.625 380.617+345.48 34.353+16.936 17.87+13.277 20.123+20.985 19.15+24.861 13.633+12.479 936.54+337.167 1136.167+288.087 6 Chloride (mg/l) 3976+ 15957.25 13566.92 20767.5+ 18460 18602 8946 2002.2 2343 2612.8 3322.73 9940 12638 19241 22010 + + 2990.72 9 5616.746 8272.571 102 1395.15 7931.717 13276.5+ + 9123.5+ 14200 5964 3976 639 553.8 411.8 5112 2130 11857 17395 + 5003.213 1723.11 6853.002 6847.36 7 4331+ 19010.25 15323.09 25063+ 25205 xx 14626 1093.4 766.8 837.8 6864.76 9088 19738 23430 23785 + + 122.975 6 6863.262 10511.9 19288.33+5549.06 12283+8936.41 9182.667+5328.94 1244.867+694.10 1287.467+1167.36 8046.667+2576.95 21063.33+3298.50 4488.188 1221.2+977.327 11502+8858.797 18176+5859.544 4 6 3 7 9 1 9 Sulphate (mg/l) 78.75+ 22.125+ 52.75+ 51.208+ 129 62 36 13 17.5 22 47 44 60 60 33.5 9.953 8.460 30.608 82.75+ 2.875+ 35.25+ 40.291 + 120 41 5 2 2.5 2 39.5 13.5 42 46 41.08 1.436 14.745 41.157 78.667+ 22.25+ 52.75+ 48.727 + 60.5 xx 54 14 11 10 43 50.5 57 60.5 31.465 21.234 7.708 30.115 103.167+37.223 51.5+14.849 31.667+24.785 9.667+6.658 10.333+7.522 11.333+10.066 43.167+3.752 36+19.754 53+9.643 55.5+8.231 Sodium (ppt) 21.075+ 1.815+ 17.18+ 13.356 + 22.05 11.95 1.6 1.18 2.08 2.4 10.82 12.85 19.4 25.65 6.520 0.536 6.729 9.972 13.05+ 1.215+ 8.887+ 7.717 + 16.55 0.8 4.5 0.265 0.015 0.08 5.46 1.69 11.75 16.65 8.319 2.192 6.633 7.642 15.33 24.916+ 3.301+ 20.167+ 23.15 xx 11.15 1.215 0.36 0.48 8.97 22 21.65 28.05 + 1.704 5.246 8.022 11.088 20.583+3.536 6.375+7.884 5.75+4.896 0.886+0.538 0.818+1.106 0.987+1.24 8.417+2.722 12.18+10.171 17.6+5.189 23.45+6.01 Nitrogen (mg/l) 38.5+ 55.5+ 75.25+ 56.417 + 35 42 35 22 130 35 56 140 42 63 4.041 50.043 44.040 38.242 49+ 58+ 69.75+ 58.917 + 42 63 42 19 130 41 70 80 80 49 9.899 49.159 14.614 28.684 46.667+ 77.25+ 94.75+ 75.272+ 49 xx 42 22 220 25 120 168 63 28 4.041 95.573 61.824 65.490 42+7 52.5+14.849 39.667+4.041 21+1.732 160+51.961 33.667+8.082 82+33.645 129.333+44.959 61.667+19.035 46.667+17.616 Phosphorous (mg/l) 65.38+ 25.88+ 13.125+ 34.79+ 75 24 62.5 7.0 30 4.0 5 16 19.5 12.0 39.1 27.04 6.22 34.156 68.5+ 38.68+ 8.875+ 38.68+ 26.5 20 0.7 110 35 9.0 1.0 9 2.5 23 52.41 49.74 10.04 45.8 91.67+ 26.25+ 11.5+ 38.73 + 60.0 xx 10.5 3.0 87.5 4 3.5 18.5 15.0 9.0 27.88 40.97 6.62 43.26 53.83+24.83 22.0+2.83 24.57+33.22 40+60.66 50.83+31.85 5.67+2.89 3.17+2.021 14.5+4.92 12.33+8.81 14.67+7.37 103 Potassium (mg/l) 312.5+ 426.25+ 390+ 376.25 + 150.0 650.0 1550.0 25.0 45.0 85.0 440.0 570.0 50.0 500.0 268.871 749.581 232.808 436.109 362.5+ 461.25+ 127.5+ 317.083+ 100.0 1100.0 1800.0 0 20.0 25.0 220.0 40.0 250.0 0 492.231 892.565 125.797 555.920 300+ 308.75+ 342.5+ 318.636 + 150.0 xx 1200.0 35.0 0 0 320.0 500.0 50.0 500.0 180.277 594.395 212.661 355.57 133.333+28.867 875+318.198 1516.667+301.385 20+18.027 21.667+22.546 36.667+43.684 326.667+110.151 370+287.923 116.667+115.47 333.333+288.675 Table 2.6. Physico- chemical characteristics of water samples from habitats of Sonneratia alba. PRE MONSOON MONSOON POST MONSOON Seasonal Seasonal Seasonal Annual Apr May Mean+ Jun Jul Aug Sep Mean+ Oct Nov Dec Jan Mean+ Mean+ SD SD SD SD Water pH 7.987 + 8.04 7.85 7.935 7.51 6.97 8.3 8.32 7.775 8.46 8.57 8.01 7.97 8.252 0.458 7.954+ 8.07 8.31 8.23 7.67 7.01 6.93 8.45 7.515 7.73 8.54 8.03 8.17 8.117 0.526 7.013+ 7.35 6.98 7.66 xx 7.06 6.06 6.02 6.38 6.39 6.89 7.12 6.97 6.842 0.710 7.82+0.407 7.713+0.675 7.59+0.113 7.013+0.045 7.096+1.12 7.596+1.367 7.527+1.049 8+0.961 7.72+0.519 7.703+0.642 Turbidity (NTU) 15.6+ 29.6 11.6 16.1 8.4 12.2 4.2 37.6 15.6 41.1 6.4 6.6 6.3 15.1 12.94 14.275+ 32.8 4.5 14.025 5 12.6 14.4 53.9 21.475 14 6.7 4.6 4 7.325 15.004 12.2 2.2 20.3 7.35 xx 11.4 2.9 3.4 5.9 21.2 28.4 29.9 7.6 21.775 + 10.776 21.533+16.819 12.133+7.913 6.7+2.404 12.067+0.611 7.167+6.297 31.633+25.773 25.433+14.037 13.833+12.616 13.7+14.065 5.967+1.823 104 T.S (mg/l) 25966.67+ 42200 43200 42800 7000 400 9000 9200 6400 13600 19800 40000 41400 28700 17437.86 25916.67+ 41600 41800 42900 9200 600 400 18200 7100 8200 19200 39800 43800 27750 18254.46 28836.36+ 42800 49400 43950 xx 1400 800 1600 1266.67 27400 24200 43600 42400 34400 19133.18 503.322 42200+600 44800+4044.75 8100+1555.635 800+529.15 3400+4853.864 9666.667+8309.834 16400+9901.515 21066.67+2730.079 41133.33+2138.535 42533.33+1205.543 T.D.S (ppt) 25.283+ 42.0 42.2 42.1 6.4 0.2 7.2 8.4 5.55 13.6 18.6 39.8 40.8 28.2 17.5 25.033+ 40.4 41.6 41.65 8.4 0.4 0.4 16.6 6.45 8.2 19.0 39.8 41.0 27 17.765 27.673+ 38.0 49.0 41.8 xx 1.2 0.8 1.4 1.133 26.2 22.2 43.0 42.4 33.45 18.628 0.642 40.133+2.013 44.267+4.11 7.4+1.414 0.6+0.529 2.8+3.815 8.8+7.607 16+9.236 19.933+1.973 40.867+1.847 41.4+0.871 T.S.S (mg/l) 683.33+ 200 1000 700 600 200 1800 800 850 0 1200 200 600 500 611.753 883.33+ 1200 200 1250 800 200 0 1600 650 0 200 0 2800 750 1032.062 1163.636+ 4800 400 2150 xx 200 0 200 133.333 1200 2000 600 0 950 1430.575 832.666 2066.667+2419.366 533.33+416.333 700+141.421 200+0 600+1039.23 866.67+702.376 400+692.82 1133.333+901.85 266.6667+305.505 1133.333+1474.223 Salinity (ppt) 20.789+ 35.11 34.71 34.865 5.425 0.299 0.448 8.32 3.623 12.07 16.9 32.26 34.28 23.877 14.844 21.617+ 35 34.5 35.09 7.156 0.419 8.074 11.68 6.832 7.107 16.49 32.97 35.15 22.929 14.194 24.562 + 35.68 38.5 35.807 xx 0.847 0.813 0.792 0.817 22 33.64 33.71 35.15 31.125 15.788 0.792 35.263+0.365 35.903+2.251 6.290+1.224 0.521+0.288 3.112+4.301 6.93+5.575 13.725+7.583 22.343+9.785 32.98+0.725 34.86+0.502 105 Resistivity (Ω) 260.368+ 19.02 19.15 19.165 104.3 1634 1113 69.97 730.317 50.02 36.49 20.47 19.51 31.622 532.327 134.413+ 19.07 19.28 19.042 80.67 1174 72.83 51.14 344.66 81.46 37.52 20.08 19.09 39.537 328.379 184.233+ 18.71 17.49 18.702 xx 599.3 629.6 635.5 621.466 29.02 19.77 19.59 18.98 21.84 280.969 18.933+0.195 18.64+0.998 92.485+16.708 1135.767+518.408 605.143+520.516 252.203+332.078 53.5+26.392 31.26+9.964 20.046+0.441 19.193+0.279 Conductivity (mS) 31.065+ 51.39 50.97 50.972 9.374 0.599 0.878 13.94 6.197 19.5 26.81 47.76 50.03 36.025 21.278 32.39+ 51.25 50.71 51.307 12.11 0.833 13.44 19.1 11.372 12.02 26.12 48.7 51.13 34.492 20.105 36.235+ 52.24 55.87 52.3575 xx 1.634 1.553 1.538 1.575 33.65 49.38 49.86 51.55 46.11 22.938 51.626+0.535 52.516+2.907 10.742+1.934 1.022+0.542 5.290+7.065 11.526+9.026 21.723+10.985 34.103+13.234 48.773+1.052 50.9033+0.784 Acidity (Mg/l) 29.443+ 48.4 35.2 45.1 8.8 11 30.8 13.2 15.95 22 3.52 26.4 57.2 27.28 19.701 24.09 52.8 26.4 31.9 15.4 6.6 8.8 17.6 12.1 39.6 3.08 22 48.4 28.27 + 16.1 47 52.8 70.4 50.6 xx 15.4 30.8 30.8 25.667 61.6 74.8 35.2 66 59.4 + 20.121 51.333+2.54 44+23.282 12.1+4.667 11+4.4 23.467+12.701 20.533+9.159 41.067+19.84 27.133+41.281 27.867+6.721 57.2+8.8 Alkalinity (Mg/l) 171.25+ 160 170 182.5 70 85 180 140 118.75 280 120 180 270 212.5 67.289 171.667+ 270 190 200 80 160 80 160 120 250 100 180 250 195 63.794 172.727+ 200 220 220 xx 60 140 120 106.667 140 180 210 170 175 54.2385 55.075 210+55.6776 193.333+25.166 75+7.071 101.667+52.041 133.333+50.332 140+20 223.333+73.71 133.333+41.633 190+17.32 230+52.915 Hardness (Mg/l) 3679.917+ 7220 8760 7440 1140 69 200 440 462.25 370 880 4580 6720 3137.5 3436.343 3675.25+ 7040 6840 6925 1560 96 67 520 560.75 280 880 6200 6800 3540 3275.315 4053.818+ 7720 8000 7475 xx 146 32 130 102.667 484 900 6200 6800 3596 3594.697 7326.667+352.325 7866.667+966.919 1350+296.984 103.6667+39.068 99.667+88.636 363.333+205.993 378+102.235 886.666+11.547 5660+935.307 6773.333+46.188 106 Calcium (Mg/l) 290.926+ 456.57 496.6 490.6075 80.1 13.63 40.08 106.6 60.102 134.67 216.43 488.61 448.56 322.0675 207.41 280.282 448.56 456.6 480.6075 144.18 16.03 12.42 134.7 76.832 84.17 200.4 424.53 424.53 283.4075 + 198.113 301.797+ 464.58 528.7 480.61 xx 15.23 10.42 9.62 11.756 160.32 320.64 448.56 432.54 340.515 210.601 456.57+8.01 493.967+36.122 112.14+45.311 14.963+1.222 20.973+16.577 83.64+65.624 126.386+38.744 245.823+65.287 453.9+32.372 435.21+12.235 Magnesium (Mg/l) 719.1+ 1480.3 1830.9 1513.15 228.86 8.53 24.36 42.36 76.028 8.28 82.78 818.04 1363.4 568.125 718.942 724.435 + 1441.3 1387.8 1393.85 292.16 13.64 8.77 44.79 89.84 17.04 92.52 1251.4 1397.5 689.615 680.402 803.525+ 1597.1 1626.4 1527.75 xx 26.31 1.46 25.81 17.86 20.45 24.35 1236.8 1392.6 668.55 757.403 1506.233+81.072 1615.033+221.768 260.51+44.759 16.16+9.154 11.53+11.696 37.653+10.328 15.257+6.277 66.55+36.869 1102.08+246.094 1384.5+18.436 Chloride (Mg/l) 16385.62+ 23998 30672 25347 5964 383.4 5964 4118 4107.35 6958 10650 19880 41322 19702.5 12576.02 15460.25+ 23430 25560 24672.5 6674 461.5 404.7 4828 3092.05 4316.8 10863 20022 39263 18616.2 12495.2 16918.7+ 26270 27406 25489 xx 681.6 795.2 809.4 762.06 15265 21158 22720 22720 20465.75 104848.48 901.821 24566+1502.787 27879.33+2588.662 6319+502.045 508.833+154.632 2387.967+3103.084 3251.8+2144.764 8846.6+5713.22 14223.67+6006.253 20874+1600.259 34435+10197.59 Sulphate (Mg/l) 55.125+ 127 63 89.125 31.5 2 36 41 27.625 43.5 57 48 46 48.625 32.993 53.083+ 126 63 89.5 38.5 3 2.5 44 22 36 57 51 47 47.75 35.934 50.59+ 60.5 63 75.625 xx 9 8.5 5.5 7.667 57 53.5 60 60.5 57.75 32.673 104.5+38.108 63+0 35+4.949 4.667+3.785 15.667+17.862 30.167+21.414 45.5+10.641 55.833+2.020 53+6.245 51.1667+8.0984 Sodium (ppt) 14.923+ 25.55 29.65 27 0.01 0.075 0.002 0.61 0.174 8.12 11.67 22.55 28.05 17.597 12.617 14.999+ 23.9 26.15 25.375 0.45 0.135 4.735 8.17 3.372 5.33 11.32 23.8 24.55 16.25 10.855 19.912+ 26.8 26.9 26.225 xx 0.475 0.465 0.67 0.536 12.77 46.8 24.3 28.65 28.13 14.695 25.417+1.454 27.567+1.842 0.23+0.3111 0.228+0.215 1.73+2.609 3.15+4.347 8.74+3.758 23.263+20.384 23.55+0.901 27.083+2.214 107 Nitrogen (mg/l) 98.917+ 63.0 56.0 47.25 28.0 38.0 140.0 490.0 174 80.0 110.0 70.0 42.0 75.5 127.6825 56+ 56.0 35.0 42 42.0 14.0 120.0 34.0 52.5 98.0 98.0 42.0 56.0 73.5 32.1106 56.091+ 42.0 42.0 40.25 xx 22.0 110.0 39.0 57 63.0 70.0 110.0 42.0 71.25 29.5752 53.667+10.692 44.333+10.692 35+9.899 24.667+12.22 123.333+15.275 187.667+261.840 80.333+17.502 92.667+20.526 74+34.176 46.667+8.082 Phosphorous (mg/l) 33.08+ 62.5 17 49.5 62.5 50 35 3 37.625 11 3 3.5 31 12.125 30.37 39.77+ 5.5 15 57.68 77.5 40 25 1.5 36 4 65 13.5 20 25.625 38.87 32.36+ 25 25.5 63.88 xx 15 30 20 21.667 3 7.5 10 15 8.875 35.77 31+28.97 19.17+5.58 70+10.61 35+18.03 30.0+50.0 8.17+10.28 6+4.36 25.17+34.57 9+5.07 22+8.19 Potassium (mg/l) 350.83+ 100.0 100.0 237.5 1600.0 10.0 20.0 220.0 462.5 290.0 520.0 150.0 450.0 352.5 427.88 346.25+ 0 400.0 250 1650.0 15.0 170.0 260.0 523.75 120.0 440.0 200.0 300.0 265 434.694 292.727+ 150.0 450.0 337.5 xx 10.0 0 0 3.333 560.0 500.0 300.0 500.0 465 223.297 76.376 83.333+76.376 316.667+189.296 1625+35.355 11.667+2.886 63.333+92.915 160+140 323.333+221.885 486.667+41.633 216.667+76.376 416.667+104.083 108 As far as the pH of water confining to the habitat of Avicennia officinalis is concerned, higher annual average was noticed at Kadalundi 1 of Malappuram district (7.612 ± 0.397), followed by Kumbalam 1 of Ernakulam district (6.892 ± 0.397) and Thekkumbad 1 of Kannur district (6.842 ±1.302). With respect to Bruguiera cylindrica, highest pH was recorded at Kadalundi 2 of Malappuram district (7.749 ± 0.420) followed by Ayiramthengu 1 of Kollam district (7.470 ± 0.379) and Thekkumbad 2 of Kannur district (7.126 ± 0.776). Among the study sites of Excoecaria agallocha, higher pH was recorded at Ayiramthengu 2 (7.389 ± 0.431), followed by Kumbalam 2 (6.91 ± 0.436) and lower at Thekkumbad 3(6.758 ± 1.014). Results on the annual mean pH of Rhizophora mucronata habitats revealed higher pH at Ayiramthengu 3(7.383 ± 0.477) followed by Kumbalam 3(6.994 ± 0.374) and Thekkumbad 4(6.981 ± 1.534). With respect to Sonneratia alba, higher pH was noticed at Kadalundi 3 (7.988 ± 0.459) followed by Kadalundi 4 (7.954 ± 0.527) and Thekkumbad 5 (7.014 ± 0.710). Results of the annual mean turbidity of water along the habitat of Avicennia officinalis showed a highest value of 17.408 ± 15134 NTU at Kadalundi 1, 8.867 ± 7.354 NTU at Kumbalam1 and 8.644 ± 7.354 NTU at Thekkumbad 1. Highest annual average of turbidity with respect to Bruguiera cylindrica was noticed at Kadalundi 2 (20.658±11.861 NTU) followed by Ayiramthengu 1(6.983 ±4.551 NTU) and Thekkumbad 2(4.678 ±3.004 NTU). As far as the turbidity of water confining to the habitat of Excoecaria agallocha is concerned, higher annual average was noticed at Kumbalam 2 (9.542 ± 7.678 NTU) followed by Ayiramthengu 2, (7.817 ± 9.468 NTU) and Thekkumbad 3 (5.678 ± 4.029 NTU). Among the habitats of Rhizophora mucronata, Thekkumbad 4 was reported for highest annual mean turbidity of 21.336 ± 16.869 NTU followed by Ayiramthengu 3(9.683 ± 6.323 NTU) and Kumbalam 3(7.417 ± 5.680 NTU). ). With respect to Sonneratia alba, highest turbidity was noted at Kadalundi 3 (15.6 ± 12.94 NTU) followed by Kadalundi 4 (14.275 ± 15.004 NTU) and Thekkumbad 5 (12.2 ±10.776 NTU). 109 Results of total solids (TS) of water confining to the habitat of Avicennia officinalis revealed higher annual average at Thekkumbad 1 (25444.4 ± 19686.9 mg/l) followed by Kadalundi 1 (23900 ± 18798.4 mg/l) and Kumbalam 1 (10733.3 ± 10769.1 mg/l). With respect to Bruguiera cylindrica, highest TS was noted at Thekkumbad 2 (26555.6 ± 24119.03 mg/l) followed by Kadalundi 2 (25933.3 ± 18991.35 mg/l) and Ayiramthengu 1 (23166.7 ± 14682.29 mg/l). Among the study sites of Excoecaria agallocha, Ayiramthengu 2 was noticed for highest value of TS (23500 ± 15260.5 mg/l) followed by Thekkumbad 3 (22800 ± 21589.8 mg/l) and Kumbalam 2 (10433.3 ± 9814.2 mg/l). Data on the annual mean TS with respect to Rhizophora mucronata revealed higher values at Thekkumbad 4 (27109.1 ± 19545.9 mg/l) followed by Ayiramthengu 3 (23533.3 ± 15807.1 mg/l) and Kumbalam 3 (12050.0 ± 11565.2 mg/l). Studies on the habitats of Sonneratia alba showed higher value of TS at Thekkumbad 5 (28836.4 ± 19133.2 mg/l) followed by Kadalundi 3 (25966.7 ± 17437.9 mg/l) and Kadalundi 4 (25916.7 ± 18254.5 mg/l). As far as the total dissolved solids (TDS) of water confining to the habitat of Avicennia officinalis is concerned, higher annual average was noticed at Kadalundi 1 of Malappuram district (22.917 ± 18.272 ppt) followed by Thekkumbad 1 of Kannur district (20.333 ± 19.364 ppt) and Kumbalam 1 of Ernakulam district (9.9 ± 10.136 ppt). In the case of Bruguiera cylindrica, highest TDS was noted at Thekkumbad 2 (26.067 ± 23.34 ppt) followed by Kadalundi 2 (22.983 ± 17.157 ppt) and Ayiramthengu 1 (22.183 ± 14.27 ppt). As far as the TDS of water confining to the habitat of Excoecaria agallocha is concerned, higher annual average was noticed at Ayiramthengu 2 (22.7 ± 14.83 ppt) followed by Thekkumbad 3 (21.2 ± 20.11 ppt) and Kumbalam 2 (9.867 ± 9.367 ppt). Among the habitats of Rhizophora mucronata, Thekkumbad 4 was recorded with higher annual mean of TDS (25.546 ± 17.882 ppt) followed by Ayiramthengu 3 (22.567 ± 15.687 ppt) and Kumbalam 3 (11.367 ± 11.193 ppt). With respect to Sonneratia alba, highest TDS was noted at Thekkumbad 5 of Kannur district (27.673 ± 18.628 ppt) followed by Kadalundi 4 (25.283 ± 17..500 ppt) and Kadalundi 3 of Malappuram district (25.033 ± 17.765 ppt). 110 Total suspended solids (TSS) of water confining to the habitats of Avicennia officinalis showed a higher annual average value at Thekkumbad 1 (5111.11 ± 13541.46 mg/l) followed by Kadalundi 1 (966.67 ± 1019.21 mg/l) and Kumbalam 1 (833.33 ± 839.192 mg/l). With respect to Bruguiera cylindrica, highest TSS was noted at Kadalundi 2 (2950 ± 5288.15 mg/l) followed by Ayiramthengu1 (983.33 ± 715.84 mg/l) and Thekkumbad 2 (888.89 ± 1403.96 mg/l). Among the study sites of Excoecaria agallocha, Thekkumbad 3 was noticed for higher TSS (1600 ± 2626.79 mg/l) followed by Ayiramthengu 2 (800 ± 687.55 mg/l) and Kumbalam 2 (566.67 ± 648.54 mg/l). TSS with respect to Rhizophora mucronata showed a higher annual mean (1563.64 ± 3122.59 mg/l) at Thekkumbad 4 followed by Ayiramthengu 3 (966.67 ± 727.80 mg/l) and Kumbalam 3 (683.33 ± 1136.05 mg/l). The study areas of Sonneratia alba showed a higher TSS at Thekkumbad 5(1163.64 ± 1430.58 mg/l) followed by Kadalundi 4 (883.33 ± 1032.06 mg/l) and Kadalundi 3 (683.33 ± 611.75 mg/l). As far as the acidity of water confining to the habitat of Avicennia officinalis is concerned, higher annual average was noticed at Thekkumbad 1 (35.689 ± 13.99 mg/l) followed by Kadalundi 1 (27.977 ± 18.139 mg/l) and Kumbalam 1 (22.55 ± 21.74 mg/l). With respect to Bruguiera cylindrica, highest acidity was noted at Thekkumbad 2 (40.578 ± 15.365 mg/l) followed by Ayiramthengu 1 (29.333 ± 10.03 mg/l) and Kadalundi 2 (28.563 ± 13.64 mg/l). Among the study sites of Excoecaria agallocha, higher acidity was noticed at Thekkumbad 3 (39.356 ± 21.456 mg/l) followed by Ayiramthengu 2 (34.65 ± 9.755 mg/l) and Kumbalam 2 (27.133 ± 9.49 mg/l). With respect to Rhizophora mucronata, annual mean acidity was higher at Ayiramthengu 3 (34.833 ± 15.41 mg/l) followed by Thekkumbad 4 (33.4 ± 11.25 mg/l) and Kumbalam 3 (23.467 ± 13.18 mg/l). The study areas of Sonneratia alba showed a higher acidity at Thekkumbad 5 (47 ± 20.122 mg/l) followed by Kadalundi 3 (29.443 ± 19.702 mg/l) and Kadalundi 4 (24.09 ± 16.100 mg/l). 111 Results of the annual average alkalinity confining to the habitats of Avicennia officinalis revealed a higher value at Thekkumbad 1 of (164.444 ± 51.505 mg/l) followed by Kadalundi 1 (160.833 ± 66.121 mg/l) and Kumbalam 1 (132.083 ± 45.898 mg/l). In the case of Bruguiera cylindrica, highest mean alkalinity was noted at Thekkumbad 2 (270.0 ± 298.035 mg/l) followed by Kadalundi 2 (162.083 ± 52.2 mg/l) and Ayiramthengu 1 (160.417 ± 27.998 mg/l). As far as the alkalinity of water confining to the habitat of Excoecaria agallocha is concerned, higher annual average was noticed at Ayiramthengu 2 (172.083 ± 34.076 mg/l) followed by Thekkumbad 3 of (150.556 ± 35.920 mg/l) and Kumbalam 2 (122.083 ± 39.969 mg/l). Among the habitats of Rhizophora mucronata, Ayiramthengu 3 (171.667 ± 35.119 mg/l) was noticed for higher value followed by Thekkumbad 4 (141.818 ± 60.302 mg/l) and Kumbalam 3 (112.083 ± 32.715 mg/l). With respect to Sonneratia alba, highest alkalinity was noted at Thekkumbad 5 (172.727 ± 54.239 mg/l) followed by Kadalundi 4 (171.667 ± 63.794 mg/l) and Kadalundi 3 (171.667 ± 63.794 mg/l). Hardness of water confining to the habitat of Avicennia officinalis showed higher annual average values at Kadalundi 1 (3490.75± 3414.5 mg/l) followed by Thekkumbad 1 (3051.33 ± 3344.77 mg/l) and Kumbalam 1 (1786.17 ± 1872.34 mg/l). With respect to Bruguiera cylindrica, highest hardness was noted at Ayiramthengu 1 (3282.17 ± 2741.46 mg/l) followed by Kadalundi 2 (3135.67± 3447.72 mg/l) and Thekkumbad 2 (31300 ± 3555.53 mg/l). In the case of Excoecaria agallocha, hardness showed a higher value at Ayiramthengu 2 (3279.67 ± 2782.29 mg/l) followed by Thekkumbad 3 (3124.89 ± 3514.9 mg/l) and Kumbalam 2 (1736.92 ± 1789.16 mg/l). Among the habitats of Rhizophora mucronata, the annual mean hardness was higher at Thekkumbad 4 (3660.18 ± 3366.06 mg/l) followed by Ayiramthengu 3 (3273.33 ± 2808.77 mg/l) and Kumbalam 3 (1852.5 ± 1988.9 mg/l). The study areas of Sonneratia alba showed a higher hardness at Thekkumbad 5 (4053.82 ± 3594.7 mg/l) followed by Kadalundi 3 (3679.92 ± 3436.34 mg/l) and Kadalundi 4 (3675.25 ± 3275.32 mg/l). 112 Annual average value of calcium confining to the habitats of Avicennia officinalis was higher at Thekkumbad 1 (308.96 ± 280.96 mg/l) followed by Kadalundi 1 (261.22 ± 215.51 mg/l) and Kumbalam 1 (151.09 ± 132.44 mg/l). With respect to Bruguiera cylindrica, highest calcium was noted at Thekkumbad 2 (334.806 ± 371.638 mg/l) followed by Kadalundi 2 (289.213 ± 243.933 mg/l) and Ayiramthengu 1(289.195 ± 243.933 mg/l). In the case of Excoecaria agallocha, higher annual average of calcium was noticed at Ayiramthengu 2 (273.321 ± 157.128 mg/l) followed by Thekkumbad 3 (266.538 ± 263.387 mg/l) and Kumbalam 2 (130.838 ± 109.603 mg/l). Higher annual mean value of calcium with respect to the habitats of Rhizophora mucronata was reported at Thekkumbad 4 (280.78 ± 201.41 mg/l) followed by Ayiramthengu 3 (270.976 ± 158.808 mg/l) and Kumbalam 3 (144.12 ± 125.68 mg/l). With respect to Sonneratia alba, highest calcium was noted at Thekkumbad 5 (301.797 ± 210.601 mg/l) followed by Kadalundi 3 (290.926 ± 207.41 mg/l) and Kadalundi 4 (280.28 ± 198.11 mg/l). As far as the magnesium of water confining to the habitat of Avicennia officinalis is concerned, higher annual average was noticed at Kadalundi 1 (690.693 ± 703.72 mg/l) followed by Thekkumbad 1 (555.101 ± 684.09 mg/l) and Kumbalam 1 (343.026 ± 377.323 mg/l). With respect to Bruguiera cylindrica, highest magnesium content was noted at Kadalundi 2 (712.159 ± 693.05 mg/l) followed by Ayiramthengu 1 (623.312 ± 572.688 mg/l) and Thekkumbad 2 (558.543 ± 669.587 mg/l). Among the habitats of Excoecaria agallocha, Ayiramthengu 2 showed higher magnesium (632.381 ± 588.34 mg/l) followed Kumbalam 2 (598.789 ± 710.721 mg/l) and Thekkumbad 3 (343.348 ± 370.431 mg/l). In the case of Rhizophora mucronata, the annual mean content of magnesium was higher at Thekkumbad 4 (720.47 ± 704.30 mg/l) followed by Ayiramthengu 3 (632.231 ± 593.85 mg/l) and Kumbalam 3 (363.41 ± 410.01 mg/l). The study areas of Sonneratia alba showed a higher magnesium at Thekkumbad 5 (803.526 ± 757.404 mg/l) followed by Kadalundi 4 (724.435 ± 680.40 mg/l) and Kadalundi 3 (719.101 ± 718.94 mg/l). 113 In the present investigation, the annual average value of chloride confining to the habitat of Avicennia officinalis was higher at Kadalundi 1 (15257.9 ± 12778.04 mg/l) followed by Thekkumbad 1 (14873.71 ± 11857.44 mg/l) and Kumbalam 1(8001.7 ± 7192.61 mg/l). Highest annual average value of chloride with respect to Bruguiera cylindrica was noted at Kadalundi 2 (13144.68 ± 9949.87 mg/l) followed by Ayiramthengu 1 (12266.43 ± 7370.04 mg/l) and Thekkumbad 2 (11833.93 ± 11850.96 mg/l). As far as the chloride of water confining to the habitat of Excoecaria agallocha is concerned, annual average was higher at Thekkumbad 3 of Kannur district (13166.84 ± 12237.16 mg/l) followed by Ayiramthengu 2 (13107.78 ± 7959.91 mg/l) and Kumbalam 2 (7669.78 ± 6849.18 mg/l). With respect to Rhizophora mucronata the annual mean chloride was higher at Thekkumbad 4 (15323.09 ± 10511.9 mg/l) followed by Ayiramthengu 3 (13566.92 ± 8272.57 mg/l) and Kumbalam 3 (7931.71 ± 6847.36 mg/l). In the case of Sonneratia alba, highest chloride was noted at Thekkumbad 5 (16918.7 ± 10848.48 mg/l) followed by Kadalundi 3 (16385.617 ± 12576.02 mg/l) and Kadalundi 4 (15460.25 ± 12495.2 mg/l). Among different habitats of Avicennia officinalis, higher annual average values of sulphate was noticed at Kadalundi 1 (51.208 ± 35.229 mg/l) followed by Thekkumbad 1 (44.861 ± 37.370 mg/l) and Kumbalam 1 (37.375 ± 38.154 mg/l). With respect to Bruguiera cylindrica, highest sulphate was noted at Kadalundi 2 (54.75 ± 33.537 mg/l) followed by Ayiramthengu 1 (51.167 ± 29.655 mg/l) and Thekkumbad 2 (44.111 ± 36.82 mg/l). In the case of Excoecaria agallocha, higher sulphate was noticed at Ayiramthengu 2 (52.417 ± 29.271 mg/l) followed by Thekkumbad 3 (41.722 ± 36.799 mg/l) and Kumbalam 2 (35.271 ± 33.082 mg/l). In the case of Rhizophora mucronata, the annual mean sulphate was higher at Ayiramthengu 3 (51.208 ± 30.61 mg/l) followed by Thekkumbad 4 (48.727 ± 30.12 mg/l) and Kumbalam 3 (40.292 ± 41.158 mg/l). The study sites of Sonneratia alba showed a higher sulphate at Kadalundi 3 (55.125 ± 32.99 mg/l) followed by Kadalundi 4 (53.083 ± 35.94 mg/l) and Thekkumbad 5 (50.591 ± 32.673 mg/l). 114 Annual average values of sodium confining to the habitat of Avicennia officinalis was higher at Thekkumbad 1 (17.849 ± 18.35 ppt) followed by Kadalundi 1 (13.935 ± 10.852 ppt) and Kumbalam 1 (5.677 ± 5.624 ppt). With respect to Bruguiera cylindrica, the annual average value of sodium was highest at Thekkumbad 2 (16.289 ± 15.225 ppt) followed by Kadalundi 2 (15.523 ± 11.604 ppt) and Ayiramthengu 1 (13.288 ± 9.267 ppt). Higher annual average values of sodium with respect to Excoecaria agallocha was noticed at Ayiramthengu 2 (14.303 ± 10.426 ppt) followed by Thekkumbad 3 (14.123 ± 13.409 ppt) and Kumbalam 2 (8.447 ± 9.594 ppt). The habitats of Rhizophora mucronata has been noticed with higher annual mean sodium of 15.33 ± 11.088 ppt at Thekkumbad 4 followed by Ayiramthengu 3 (13.357 ± 9.97 ppt) and Kumbalam 3 (7.718 ± 7.642 ppt). With respect to Sonneratia alba, highest sodium was noted at Thekkumbad 5 (19.912 ± 14.7 ppt) followed by Kadalundi 4 (14.999 ± 10.86 ppt) and Kadalundi 3 (14.924 ± 12.62 ppt). As far as the nitrogen content of water confining to the habitat of Avicennia officinalis is concerned, higher annual average was noticed at Thekkumbad 1 (68.333 ± 32.86 mg/l) followed by Kumbalam 1 (59.167 ± 35.334 mg/l) and Kadalundi 1(56.417 ± 47.91 mg/l). With respect to Bruguiera cylindrica, highest nitrogen content was noted at Ayiramthengu 1 (61.333 ± 49.99 mg/l) followed by Thekkumbad 2 (55.091 ± 35.43 mg/l) and Kadalundi 2 (48.583 ± 25.91 mg/l). In the case of Excoecaria agallocha, higher nitrogen was reported at Ayiramthengu 2 (69.75 ± 55.531 mg/l) followed by Kumbalam 2 (64.583 ± 46.108 mg/l) and Thekkumbad 3 (63.333± 31.9 mg/l). Among different habitats of Rhizophora mucronata studied, annual mean nitrogen was higher at Thekkumbad 4 (75.273 ± 65.49 mg/l) followed by Kumbalam 3 (58.92 ± 28.69 mg/l) and Ayiramthengu 3 (56.417 ± 38.242 mg/l). The study sites of Sonneratia alba showed a higher value of nitrogen at Kadalundi 3 (98.917 ± 127.683 mg/l) followed by Thekkumbad 5 (56.091 ± 29.58 mg/l) and Kadalundi 4 (56.0 ± 32.11 mg/l). 115 Phosphorous content of water confining to the habitat of Avicennia officinalis showed higher annual average values at Thekkumbad 1 (36.4 ± 42.7 mg/l) followed by Kadalundi 1 (22.08 ± 35 mg/l) and Kumbalam 1 (22.04 ± 21.9 mg/l). With respect to Bruguiera cylindrica, highest phosphorous was noted at Kadalundi 2 (42.1 ± 39.7 mg/l) followed by Thekkumbad 2 (35.2 ± 42.8 mg/l) and Ayiramthengu 1 (26.4 ± 47.4 mg/l). Among the study sites of Excoecaria agallocha, higher phosphorous was recorded at Thekkumbad 3 with 42.6 ± 40.6 mg/l followed by Kumbalam 2 (20.2 ± 25.1 mg/l) and Ayiramthengu 2 (18.2 ± 25.4 mg/l). In the case of Rhizophora mucronata, Thekkumbad 4 was noticed for higher annual mean phosphorous (38.73 ± 43.26 mg/l) followed by Kumbalam 3 (38.68 ± 45.8 mg/l) and Ayiramthengu 3 (34.8 ± 34.0 mg/l). With respect to Sonneratia alba, higher phosphorous was recorded at Kadalundi 4 (39.8 ± 38.9 mg/l) followed by Kadalundi 3 (33.1 ± 30.4 mg/l) and Thekkumbad 5 (32.4 ± 35.8 mg/l). Annual mean values of potassium confining to the habitats of Avicennia officinalis was higher at Thekkumbad 1 (3252.73 ± 8296.39 mg/l) followed by Kadalundi 1 (3105.42 ± 6015.65 mg/l) and Kumbalam 1 (910.42 ± 1828.76 mg/l). Among the sites with respect to Bruguiera cylindrica, the annual average value of potassium was noted to be higher at Kadalundi 2 (401.67 ± 488.8 mg/l) followed by Ayiramthengu 1 (312.083 ± 373.79 mg/l) and Thekkumbad 2 (211.67 ± 230.52 mg/l). As far as the potassium concentration of water confining to the habitat of Excoecaria agallocha is concerned, higher annual average was noticed at Ayiramthengu 2 (387.08 ± 412.48 mg/l) followed by Kumbalam 2 (349.17 ± 503.43 mg/l) and Thekkumbad 3 (120.0 ± 164.7 mg/l). The habitat of Rhizophora mucronata is with an annual mean level of potassium of 376.25 ± 436.11 mg/l at Ayiramthengu 3 followed by Thekkumbad 4 (318.64 ± 355.57 mg/l) and Kumbalam 3 (317.08 ± 555.92 mg/l). With respect to Sonneratia alba, highest potassium level was noted at Kadalundi 3 (350.83 ± 427.88 mg/l), followed by Kadalundi 4 (346.25 ± 434.69 mg/l) and Thekkumbad 5 (292.73 ± 223.3 mg/l). 116 Salinity of water confining to the habitats of Avicennia officinalis showed higher annual average at Kadalundi 1 (19.678 ± 15.507 ppt) followed by Thekkumbad 1 (19.667 ± 16.523ppt) and Kumbalam 1 (8.693 ± 8.654 ppt). With respect to Bruguiera cylindrica, highest salinity was noted at Kadalundi 2 (30.967 ± 21.061 ppt) followed by Thekkumbad 2 (21.061 ± 19.623 ppt) and Ayiramthengu 1 (18.689 ± 11.538 ppt). In the case of study areas of Excoecaria agallocha, Ayiramthengu 2 was recorded for higher salinity (19.067 ± 12.03 ppt) followed by Thekkumbad 3 (18.55 ± 17.818 ppt) and lower salinity of 8.529 ± 8.106 ppt at Kumbalam 2. In the habitats of Rhizophora mucronata, higher mean salinity of 21.344 ± 14.86 ppt was noted at Thekkumbad 4 followed by Ayiramthengu 3 (18.927 ± 12.19 ppt) and Kumbalam 3 (9.82 ± 9.55 ppt). With respect to the study sites of Sonneratia alba, higher salinity was recorded at Thekkumbad 5 (24.562 ± 15.788 ppt) followed by Kadalundi 4 (21.617 ± 14.19 ppt) and Kadalundi 3 (20.789 ± 14.85 ppt). As far as the resistivity of water confining to the habitat of Avicennia officinalis is concerned, higher annual average was noticed at Thekkumbad 1 (2017.66 ± 3699.78 Ω) followed by Kumbalam 1 (503.602 ± 769.47 Ω) and Kadalundi 1 (131.123 ± 191.48 Ω). With respect to Bruguiera cylindrica, highest resistivity was noted at Thekkumbad 2 (898.886 ± 1635.49 Ω) followed by Kadalundi 2 (86.831 ± 110.48 Ω) and Ayiramthengu 1 (84.723 ± 133.658 Ω). Higher values of resistivity with respect to Excoecaria agallocha was noticed at Thekkumbad 3 (2317.91 ± 4056.43 Ω) followed by Kumbalam 2 (284.721 ± 329.615 Ω) and Ayiramthengu 2 (66.07 ± 65.22 Ω). Among the habitats of Rhizophora mucronata, annual mean resistivity was higher at Kumbalam 3 (499.886 ± 681.07 Ω) followed by Thekkumbad 4 (175.23 ± 274.75 Ω) and Ayiramthengu 3 (75.048 ± 84.72 Ω). The study sites of Sonneratia alba showed a higher resistivity at Kadalundi 3 (260.368 ± 532.33 Ω) followed by Thekkumbad 5 (184.237 ± 280.97 Ω) and Kadalundi 4 (134.413 ± 328.38 Ω). Annual average values of conductivity of water confining to the habitat of Avicennia officinalis was higher at Kadalundi 1 (29.369 ± 22.193 mS) followed by Thekkumbad 1 (28.945 ± 24.195 mS) and Kumbalam 1 (13.77 ± 13.23 mS). With 117 respect to Bruguiera cylindrica, highest conductivity was noted at Kadalundi 2 (31.081 ± 21.007 mS) followed by Thekkumbad 2 (30.744 ± 28.39 mS) and Ayiramthengu 1 (28.496 ± 16.67 mS). In the case of Excoecaria agallocha, higher conductivity was recorded at Ayiramthengu 2 with 29.025 ± 17.36 mS followed by Thekkumbad 3 (27.40 ± 26.12 mS) and lower at Kumbalam 2 (13.659 ± 12.464 mS). Among different habitats of Rhizophora mucronata, the annual mean conductivity was higher at Thekkumbad 4 (31.826 ± 21.51 mS) followed by Ayiramthengu 3 (28.831 ± 17.68 mS) and Kumbalam 3 (15.570 ± 14.5 mS). With respect to the species Sonneratia alba, higher conductivity was recorded at Thekkumbad 5 (36.236 ± 22.938 mS) followed by Kadalundi 4 (32.390 ± 20.105 mS) and Kadalundi 3 (31.065 ± 21.279 mS). Similar to water samples, soil / sediment samples were collected on a monthly basis for a period of one year from the respective mangrove habitats confining to the coast of Kerala and were subjected to the analysis of pH, moisture percentage, organic carbon, total nitrogen, total phosphorous, potassium, sodium and textural percentage of sand, silt and clay by standard instruments and procedures (Subramanyam and Sambamurthy, 2002; Trivedy et al., 1987 and Jackson, 1973). The results of sediment quality parameters together with their standard deviation are depicted in Tables 2.7 – 2.11. 118 Table 2.7. Physico- chemical characteristics of sediment samples from habitats of Avicennia officinalis. PRE MONSOON MONSOON POST MONSOON Seasonal Seasonal Seasonal Annual Mar Apr May Mean+ Jun Jul Aug Sep Mean+ Oct Nov Dec Jan Mean+ Mean+ SD SD SD SD Sediment pH 7.33 + 6.645 + 5.762+ 6.62 7.25 7.33 5.01 7.54 7.27 6.76 4.25 6.04 6.2 6.56 6.487 + 0.993 0.318 1.137 1.031 7.37 + 7.31 + 8.002+ 8.32 7.42 7.37 7.55 6.9 7.69 7.1 8.06 7.82 7.8 8.33 7.712+ 0.465 0.499 0.371 0.248 7.51 + 5.962+ 6.562+ 7.23 7.34 7.51 7.07 6.73 5.97 4.08 6.39 6.13 6.57 7.16 6.632 + 0.952 0.117 1.336 0.437 7.39 + 7.34 + 7.40 + 6.54 + 7.1 + 6.98 + 5.98 + 6.2 + 6.66 + 6.86 + 7.35 + 0.861 0.085 0.094 1.349 0.427 0.896 1.654 1.909 1.002 0.837 0.9 Moisture (%) 13.05 + 13.15 + 13.47 + 13.220 + 12.06 10.5 16.27 13.43 14.05 4.97 20.15 20.05 13.58 10.96 9.28 2.445 6.239 4.731 4.288 9.96 + 10.805+ 7.46 + 8.89 8.67 14.49 10.45 10.14 9.19 13.44 9.45 7.28 5.83 7.26 9.406+ 2.506 3.057 1.836 1.493 9.9 + 15.915 + 10.78 + 12.197 + 11.06 12.43 9.04 10.27 14.76 18.94 19.69 12.29 10.88 6.48 13.465 2.348 4.343 3.054 4.108 10.67 + 10.53 + 13.27+ 11.38 + 12.98 + 11.03 + 17.76+ 13.93+ 10.58+ 7.76 + 10.01+ 1.620 1.880 3.767 1.774 2.487 7.165 3.748 5.487 3.160 2.793 3.164 Sand % 77.225 + 75.75 + 82.375 + 78.45 + 85.7 52.2 80.3 63.5 62.1 93.5 83.9 88.7 66.9 79.5 94.4 17.215 15.469 12.004 13.935 85.75 + 72.275 + 93.325 + 83.783 + 97.6 81.6 84 89.3 71.3 51.4 77.1 94.8 91.5 91.8 95.2 8.085 15.809 1.944 13.027 93.025 + 77.575 + 91.275 + 87.291 + 90 94 95.9 99 75 74.5 61.8 88.7 92.2 93.4 90.8 2.5198 15.534 2.018 10.987 91.1 + 75.933 + 86.73 + 83.93 + 69.47 + 74.27 + 90.73 + 83.53 + 88.23 + 93.467 + 73.13 + 21.083 6.025 21.468 8.151 18.348 6.642 11.319 3.521 14.409 7.605 2.343 Silt % 0.125 + 0.425 + 0.875 + 0.1 0.1 0.1 0.3 0.3 0.4 0.7 0.2 0.7 2.5 0.1 0.475 + 0.673 0.05 0.189 1.1147 0.75 + 0.5 0.2 0.3 0.275 + 0.170 0.1 0.5 1.2 1.2 0.3 0.2 0.2 0.1 0.2 + 0.0816 0.408 + 0.394 0.544 0.3 + 0.1 + 0.4 0.3 0.4 0.2 0.1 0.6 0.7 0.4 + 0.294 0.1 0.1 0.1 0.1 0.266 + 0.214 0.141 0 0.1 + 0.33 + 0.2 + 0.267 + 0.2 + 0.3 + 0.733 + 0.867 + 0.2 + 0.33 + 0.933 + 1.69967E- 0.208 0.1 0.152 0.1 0.2 0.416 0.288 0.1 0.321 1.357 17 119 Clay % 22.65 + 23.825 + 21.075 + 14.2 47.7 19.6 36.2 37.6 6.1 15.4 11.1 32.4 18 5.5 16.75 + 12.514 17.241 15.578 13.947 13.975 + 26.975 + 15.808 + 1.9 18.2 15.7 10.6 28.2 47.4 21.7 4.9 8.3 8 4.7 6.475 + 13.999 8.249 15.434 12.759 6.675 + 22.025 + 8.625 + 12.441 + 9.6 5.7 3.7 0.8 24.9 24.9 37.5 11.2 7.7 6.5 9.1 2.543 15.346 11.607 10.857 8.567 + 23.867 + 13 + 15.867 + 30.23 + 26.13 + 24.87 + 9.067 + 16.133 + 10.833 + 6.433 + 6.214 21.565 8.286 18.278 6.589 20.677 11.385 3.608 14.09 6.251 2.343 Organic carbon (g/kg) 57 8 29 38.75 96 21 24 71 53+36.688 12.5 6 1.5 30 12.5 + 12.5 34.75+29.776 12.25 + + 9.5 1 16 8.125 23 16 9 1 22 43 24 36.6 31.4 + 10.08 17.258+13.227 9.43 29 11.3 18 19.45 17 5 53 47 30.5 + 23.173 1 17 2 60 20 + 27.65 23.317+19.943 31.833+ 6.767+5.26 21+ 7 45.333+43.981 14+8.185 28.667+22.368 39.67+35.572 11.833+10.516 22+19 9.167+12.848 42.2+15.764 23.876 Total Nitrogen (mg/kg) 4290 + 9605 + 2937.5 5610.833 + 4580 3260 4200 5500 6180 18840 7900 3500 3500 3450 1300 783.581 6238.961 +1091.9210 4488.08 5625 + 5120 + 3977.5 + 4907.5 + 5100 5950 5600 4950 5380 3300 6850 4350 2980 4100 4480 379.692 1460.798 683.4410 1125.531 3395 + 1995 + 2269.167 + 1330 9800 1120 1400 1400 2380 2800 1050 1190 1400 2030 1417.5+432.9261 4271.147 708.119 2432.109 3670 3950 6336.7 + 3640 + 4320 + 8173.3 + 5850+ 2556.7 + 2983.3 + 2603.3 + + + 2966.667+1713.427 3287.101 2291.899 2560.234 9249.05 2693.047 1211.789 1409.196 1665.723 2043.11 2225.421 Total Phosphorous (mg/kg) 23.3 + 19.6 + 15.4 + 28 18.2 28 32.9 9.8 11.2 24.5 18.2 14.7 18.9 9.8 19.43 + 7.59 5.46 11.07 4.16 9.6 + 11.6 + 7.9 + 7.7 8.4 14 8.4 15.4 7.7 14.7 7 7 10.5 7 9.68+3.18 2.94 4.06 1.75 19.4 + 28 + 22 + 22.4 18 19 18 22.5 32.8 38.5 13.2 27 20 28 23.12 +7.22 2.09 9.37 6.89 19.4+ 14.9+ 19.8 + 15.9 + 17.2 + 12.8+ 16.2+ 16.6+ 14.9+ 20.3+7.09 25.9+11.96 10.48 5.60 12.35 6.36 13.59 5.61 10.09 5.2 11.40 Potassium (Mg/kg) 86.25 + 58.05 + 22.375+ 55.558 + 113 163 9 130 39.8 37.5 24.9 3.4 26.1 46 14 66.45 48.411 18.277 51.780 108 + 57.975 + 63.025 + 76.333 + 42 91 240 87.5 47.1 35.5 61.8 29.1 70 80 73 90.314 22.433 23.001 55.296 63.5 + 30.35 + 87.5 + 69 89 62 62.5 12 26.8 20.1 66 64 113 107 60.45 + 35.577 22.752 22.271 26.108 74.67 + 114.33 + 103.7 + 93.33 + 32.967 + 33.267 + 35.6 + 32.83 + 53.367 + 79.67 + 64.67 + 35.8376 42.158 121.0055 34.126 18.5209 5.6889 22.8164 31.4665 23.8034 33.5012 47.0567 120 Sodium (ppt) 0.452 + 0.292 + 0.282 + 0.436 0.867 0.178 0.445 0.106 0.561 0.057 0.08 0.076 0.528 0.443 0.342 + 0.250 0.296 0.248 0.237 0.539 + 0.238 + 0.512 + 0.401 0.797 0.528 0.415 0.127 0.289 0.120 0.132 0.491 0.742 0.682 0.429 + 0.234 0.180 0.141 0.274 1.008 + 2.025 + 0.662 1.884 0.752 0.077 0.042 0.120 0.293 0.133 + 0.111 0.108 0.697 5.46 1.834 1.055 + 1.522 0.585 2.399 0.499 + 1.183 + 0.486 + 0.313 + 0.092 + 0.323 + 0.157 + 0.107 + 0.421 + 2.243 + 0.986 + 0.141 0.608 0.289 0.204 0.044 0.222 0.122 0.025 0.316 2.787 0.743 Table 2.8. Physico- chemical characteristics of sediment samples from habitats of Bruguiera cylindrica PRE MONSOON MONSOON POST MONSOON Seasonal Seasonal Seasonal Annual Apr May Mean+ Jun Jul Aug Sep Mean+ Oct Nov Dec Jan Mean+ Mean+ SD SD SD SD Sediment pH 6.453+ 6.655+ 7.438+ 6.848+ 5.7 7.07 6.71 5.92 6.9 7.09 7.13 7.22 7.71 7.69 0.959 0.514 0.305 0.738 7.74+ 7.17+ 7.658+ 7.522 + 7.74 7.77 8.21 6.72 6.65 7.1 7.51 7.59 7.92 7.61 0.049 0.721 0.180 0.469 7.08+ 6.288+ 7.18+ 6.849 + 6.68 6.65 6.9 6.65 5.7 5.9 6.58 7.19 7.88 7.07 0.479 0.577 0.536 0.637 6.707+1.02 7.163+0.565 7.273+0.816 6.43+0.443 6.417+0.633 6.7+0.69 7.07+0.467 7.333+0.222 7.837+0.111 7.457+0.337 Moisture % 7.117 6.462+ 7.206+ 7.682+ 6.67 3.81 9.997 6.45 3.48 8.897 8.9 8.56 7.79 5.48 + 2.597 2.892 1.54 2.245 9.85 9.342+ 12.537+ 7.67+ 8.42 8.48 12.33 15.43 11.67 10.72 8.28 6.71 6.29 9.4 + 1.338 2.038 1.436 2.575 10.342+ 13.912+ 10.332+ 11.529 + 10.36 14.13 12.89 11.81 16.38 14.57 12.94 10.38 8.41 9.6 2.685 1.998 1.917 2.675 8.48+1.845 8.807+5.1677 11.739+1.534 11.23+4.518 10.51+6.527 11.4+2.896 10.04+2.530 8.55+1.835 7.497+1.090 8.16+2.323 121 Sand % 79.4+ 84.4+ 94.425+ 86.075 + 68.4 92.8 63.5 84.3 95.4 94.4 90.3 95.7 98.7 93 14.861 14.807 3.603 12.89 82.75+ 77+ 86.325+ 82.025 + 85.8 81.5 89.3 58.7 76.9 83.1 89 87.4 91.3 77.6 2.538 13.208 6.032 8.681 85.8+ 91.7+ 83.025+ 86.841 + 87.4 74.7 99 86.2 88.9 92.7 90.6 94.7 69.7 77.1 8.485 5.549 11.638 8.902 80.53+10.538 83+9.1428 83.93+18.348 76.4+15.358 87.067+9.385 90.07+6.092 89.97+0.850 92.6+4.531 86.567+15.068 82.567+9.03 Silt % 0.175+ 0.8+ 0.25+ 0.408 + 0.1 0.1 0.3 0.1 1.8 1.0 0.5 0.3 0.1 0.1 0.15 0.770 0.191 0.512 0.15+ 0.55+ 0.3+ 0.333 + 0.3 0.1 0.1 0.1 1.5 0.5 0.7 0.3 0.1 0.1 0.1 0.66 0.282 0.416 0.3+ 0.625+ 0.375+ 0.433 + 0.3 0.4 0.2 0.4 1.1 0.8 0.4 0.2 0.8 0.1 0.141 0.403 0.3096 0.3114 0.233+0.115 0.2+0.173 0.2+0.1 0.2+0.1732 1.467+0.351 0.767+0.251 0.53+0.152 0.267+0.057 0.33+0.404 0.1+1.7E-17 Clay % 20.425+ 14.8+ 5.325+ 13.516 + 31.5 7.1 36.2 15.6 2.8 4.6 9.2 4 1.2 6.9 14.763 15.348 3.477 13.013 17.1+ 22.45+ 13.375+ 17.641 + 13.9 18.4 10.6 41.2 21.6 16.4 10.3 12.3 8.6 22.3 2.619 13.283 6.139 8.684 13.9+ 7.675+ 16.6+ 12.725 + 12.3 24.9 0.8 13.4 10 6.5 9 5.1 29.5 22.8 8.48 5.379 11.472 8.867 19.233+ 16.8+ 15.867+ 23.4+ 11.467+ 9.167+ 9.5+ 7.133+ 13.1+ 17.33+ 10.653 9.007 18.278 15.454 9.485 6.335 0.7 4.508 14.676 9.039 Organic carbon (g/kg) 21.833+ 1.1 5.5 14.15 11 2 5 13 7.75 52 9.4 34 79 43.6 24.135 10.4 1 31.1 3 33 32 8 19 12 22 1 8 10.75 20.283+20.09 22.3 155 48.2 8 4 22 35 17.25 30 6 16 6 14.5 26.65+26.65 11.267+10.63 53.833+87.64 7.333+4.04 13+17.35 19.667+13.65 18.667+14.36 31.333+20.03 12.467+8.43 17+16.52 31+41.58 122 Total Nitrogen (mg/kg) 1032.5 787.5+ 630+ 816.667 + 700 630 + 630 1190 630 700 630 630 700 560 270.354 57.154 455.937 759.050 1872.5 1470+ 1295+ 1545.83 + 1400 1820 1890 2380 1750 1470 + 1400 1260 980 1540 370.405 239.095 395.37 380.733 1522.5 1592.5 1382.5 1499.166 1470 2870 + 2590 1260 1540 980 + 1400 1260 770 2100 + + 941.536 703.201 549.325 683.553 543.72 1190+425.79 1773.3+1120.72 1703.3+993.24 1610.0+667.75 1306.7+ 1050+389.743 1143.3+444.55 816.67+145.71 1400+779.48 1050+363.73 3 9 3 7 595.343 5 9 6 7 Total Phosphorous (mg/kg) 12.2+ 11.8+ 10.5+ 11.48 + 11 14.5 7.5 13 12 14.5 16.8 12 1.2 12 2.047 3.01 6.6 4.01 71.5+ 60.6+ 42.0+ 58.02 + 58 77 61.5 61.8 74.5 44.5 39.5 46.8 20 61.8 10.49 12.31 17.37 17.7 24.6+ 28.3+ 20.1+ 24.34 + 25 38.5 43 21 33.8 15.5 14.5 19.2 9.2 37.5 10.234 12.43 12.3 11.1 31.3+24.13 43.3+31.53 37.3+27.44 31.9+26.17 40.1+31.72 24.8+17.04 23.6+13.82 26+18.37 10.1+9.44 37.1+24.90 Potassium (Mg/kg) 36.525 47.25+ 61.4+ 48.391 + 69 21 107.5 9.9 15.5 13.2 + 14.1 32.5 80 119 20.694 47.385 38.137 47.372 101.75 44.475 74.525 73.583 + 230 78 + 70 35.8 56 16.1 + 18.6 60.5 84 135 + 58.882 87.248 23.556 48.55 118.25 34.325 55.125 69.233 + 194 212 + 92.5 21.4 12.7 10.7 + 8.5 89 94 29 + 70.238 98.1372 39.0605 42.876 28.067+24.23 60.667+28.25 164.33+84.5 103.7+98.052 90+18.874 22.367+12.977 13.33+2.702 13.73+5.059 86+7.211 94.33+57.143 1 0 Sodium (ppt) 0.48+ 0.175+ 0.373+ 0.342 + 0.626 0.752 0.535 0.026 0.09 0.047 0.091 0.279 0.862 0.26 0.265 0.241 0.336 0.288 0.683+ 0.209+ 0.577+ 0.489 + 1.674 0.102 0.33 0.126 0.306 0.074 0.069 0.466 0.832 0.942 0.684 0.128 0.394 0.468 0.677 1.046+ 0.161+ 0.824+ 2.81 0.433 0.47 0.089 0.039 0.046 0.032 0.852 1.077 1.335 + 1.178 0.207 0.563 0.794 1.703+1.092 0.429+0.325 0.445+0.104 0.081+0.05 0.145+0.141 0.056+0.016 0.064+0.029 0.532+0.292 0.924+0.133 0.846+0.543 123 Table 2.9. Physico- chemical characteristics of sediment samples from habitats of Excoecaria agallocha. PRE MONSOON MONSOON POST MONSOON Seasonal Annual Seasonal Seasonal Apr May Mean+ Jun Jul Aug Sep Oct Nov Dec Jan Mean+ Mean+ Mean+ SD SD SD SD Sediment pH 7.55+ 6.708+ 7.483+ 7.246 + 7.03 7.71 7.14 6.57 6.42 6.7 7.1 7.52 7.89 7.42 0.347 0.310 0.325 0.497 7.618+ 6.295+ 7.545+ 7.152 + 6.81 7.44 7.72 7.2 6.16 4.1 7.4 7.03 7.81 7.94 0.625 1.6 0.413 1.119 7.603+ 6.095+ 6.218+ 6.638 + 7.29 7.11 7.06 6.7 5.37 5.25 6.45 5.63 6.48 6.31 0.47 0.919 0.398 0.918 7.043+0.24 7.42+0.3 7.306+0.36 6.823+0.332 5.983+0.546 5.35+1.302 6.983+0.485 6.727+0.980 7.393+0.79 7.223+0.832 Moisture % 9.91+ 8.52+ 8.232+ 8.887 + 7.23 11.81 7.81 7.09 9.34 9.84 9.69 7.86 7.79 7.59 2.185 1.286 0.978 1.612 8.45+ 12.15+ 12.75+ 11.117 + 10.08 3.27 8.67 15.38 11.03 13.52 13.92 12.48 8.94 15.66 5.977 2.925 2.853 4.271 8.515+ 13.242+ 12.795+ 11.517 + 7.76 7.27 6.05 12.6 22.08 12.24 13.09 13.45 11.58 13.06 1.562 6.614 0.829 4.211 8.357+1.515 7.45+4.272 7.51+1.335 11.69+4.219 14.15+6.919 11.87+1.868 12.233+2.241 11.263+2.987 9.437+1.943 12.103+4.119 Sand % 95.675+ 88.7+ 86.7+ 90.358 + 96.7 96.6 93.1 86.5 97.9 77.3 86.4 86.1 92.3 82 1.664 8.921 4.238 6.596 82.925+ 88.025+ 78.95+ 83.3 + 95.9 72.2 88.6 78.6 91.6 93.3 61.7 81.8 92.6 79.7 13.046 6.577 12.813 10.865 92.875+ 83.875+ 81.775+ 86.175 + 88.3 90.4 85.3 84.2 75.2 90.8 89.7 78.6 92.6 66.2 4.439 6.464 12.009 9.021 93.633+4.636 86.4+12.682 89+3.915 83.1+4.063 88.23+11.718 87.13+8.607 79.267+15.302 82.167+3.763 92.5+0.173 75.967+8.536 124 Silt % 0.575 0.2+ 1.2+ 0.325+ 0.1 0.3 0.2 1.9 1.3 1.4 0.2 0.8 0.2 0.1 + 0.115 0.716 0.320 0.622 0.383 0.125+ 0.875+ 0.15+ 0.1 0.1 0.1 1.5 0.9 1.0 0.1 0.2 0.1 0.2 + 0.05 0.579 0.057 0.474 0.2+ 0.875+ 1.875+ 0.983 + 0.3 0.2 0.1 2.6 0.5 0.3 0.1 0.5 6.7 0.2 0.081 1.161 3.221 1.928 0.167+0.115 0.2+0.1 0.133+0.057 2+0.556 0.9+0.4 0.9+0.556 0.133+0.0577 0.5+0.3 2.33+3.782 0.167+0.057 Clay % 4.125+ 10.1+ 12.975+ 9.066 + 3.2 3.1 6.7 11.6 0.8 21.3 13.4 13.1 7.5 17.9 1.604 8.674 4.259 6.4028 16.95+ 11.1+ 20.9+ 16.317 + 4 27.7 11.3 19.9 7.5 5.7 38.2 18 7.3 20.1 13.070 6.314 12.8232 10.954 6.925+ 15.25+ 16.35+ 12.842 + 11.4 9.4 14.6 13.2 24.3 8.9 10.2 20.9 0.7 33.6 4.393 6.502 14.154 9.526 6.2+4.521 13.4+12.778 10.867+3.967 14.9+4.403 10.867+12.106 11.97+8.239 20.6+15.325 17.33+3.942 5.167+3.869 23.867+8.5 Organic carbon (g/kg) 35.108+71.5 0.4 24 12.725 10.5 3 4.9 23 10.35 18 36 15 260 82.25 3 1 9 9.75 15 37.5 19 15 21.625 31 16 15 22.5 21.125 17.5+10.4 29.242+33.3 18.7 14.5 11.975 28 5.5 84 10 31.875 20 12 33 110.5 43.875 5 15.333+19.2 6.7+10.4 15.83+7.59 17.833+9.09 35.967+42.19 16+6.56 23+7 21.333+12.86 21+10.39 131+120.07 4 Total Nitrogen (mg/kg) 858.113 823.09+ 682.99+ 788.063 + 700.5 910.65 1050.75 700.5 840.6 840.6 + 630.45 700.5 630.45 770.55 144.411 67.0678 137.286 144.411 1418.51 1541.11 1593.6+ 1517.754 + 1190.85 1260.9 + 840.6 2521.8 1471.05 1331 + 2311.65 1471.05 980.7 1611.15 549.717 531.249 458.903 707.465 2189.06 1873.95 823.09+ + 1628.7 + 840.6 980.7 770.55 980.7 3572.55 2172 + 700.5 2451.75 2311.65 3292.35 144.411 1082.75 1072.88 1289.63 8 910.65+252.56 1050.75+185.3 887.3+145.820 1961.4+1430.4 1447.9+673.34 1214.2+951.06 1541.1+877.72 1307.6+886.99 1891.35+1284.0 1401+980.7 8 34 7 61 97 4 4 2 38 125 Total Phosphorous (mg/kg) 15.35+ 18.25+ 12.575+ 15.39 + 15.2 21 12 16 14.6 30.4 14.2 11 9.5 15.6 5.93 8.27 2.81 6.01 36.8+ 37.95+ 54.6+ 43.12 + 27 42 26.8 33.2 51.8 40 52.8 45.5 50.5 69.6 7.47 10.69 10.45 12.18 15.5+ 26.7+ 28.675+ 23.6 + 22 19 8.2 17.2 58.2 23.2 9.5 38.5 12.2 54.5 6.12 21.89 21.62 17.47 21.4+ 5.92 27.3+12.74 15.67+9.83 22.1+ 9.60 41.5+23.54 31.2+8.43 25.5+ 23.76 31.7+ 18.24 24.1+ 22.93 46.6+ 27.86 Potassium (mg/kg) 42.25+ 42.4+ 39.875+ 41.508 + 76.0 26.0 112.5 24.4 10.9 21.8 26.5 57.0 47.0 29.0 22.779 47.097 14.619 28.394 29.75+ 41.725+ 34+ 35.158 + 30.0 16.0 127.5 23.3 15.9 0.2 66.0 31.0 32.0 7.0 25.953 57.988 24.262 35.890 67.25+ 40.075+ 63.05+ 56.792 + 138.0 75.0 117.5 12.8 25.0 5.0 5.2 79.0 120.0 48 52.747 52.268 48.548 47.983 81.33+54.197 39+31.575 119.17+7.637 20.17+6.403 17.27+7.148 9.0+11.342 32.57+30.850 55.67+24.027 66.33+47.078 28+20.518 Sodium (ppt) 0.364+ 0.1755+ 0.408+ 0.315+ 0.707 0.168 0.507 0.0902 0.0441 0.0603 0.258 0.281 0.511 0.583 0.239 0.222 0.163 0.217 0.3198+ 0.1710+ 0.533+ 0.341+ 0.672 0.071 0.4975 0.0947 0.0476 0.0443 0.443 0.573 0.548 0.568 0.254 0.218 0.061 0.236 0.69+ 0.1851+ 0.446+ 0.440+ 1.355 0.621 0.595 0.0812 0.0561 0.008 0.027 0.501 1.177 0.082 0.456 0.275 0.530 0.448 0.242+ 0.911+ 0.286+ 0.5333+ 0.088+ 0.0493+ 0.0375+ 0.451+ 0.745+ 0.411+ 0.208 0.384 0.29 0.054 0.006 0.006 0.026 0.152 0.374 0.285 126 Table 2.10. Physico- chemical characteristics of sediment samples from habitats of Rhizophora mucronata. PRE MONSOON MONSOON POST MONSOON Seasonal Seasonal Seasonal Annual Mean+ Apr May Mean + Jun Jul Aug Sep Mean + Oct Nov Dec Jan Mean + SD SD SD SD Sediment pH 7.468 + 7.4825 + 7.58 + 7.51 + 7.15 7.27 7.12 7.37 7.64 7.8 7.03 7.4 7.81 8.08 0.303 0.299 0.461 0.332 7.135 + 6.625 + 6.875 + 6.878 + 7.05 6.92 7 7.46 5.64 6.4 6.03 7.11 7.3 7.06 0.246 0.787 0.572 0.567 6.945 + 6.2025 + 6.142+ 6.43 + 6.79 7.36 7.54 7.03 5.19 5.05 6.26 5.77 6.42 6.12 0.327 1.268 0.276 0.796 6.997+0.185 7.183+0.232 7.22+0.283 7.287+0.226 6.157+1.304 6.417+1.375 6.44+0.523 6.76+0.869 7.177+0.703 7.087+0.980 Moisture (%) 7.092 + 7.957 + 7.702 + 7.584 + 11.16 1.06 6.47 8.83 8.19 8.34 9.39 7.46 8.29 5.67 4.288 1.028 1.568 2.473 18.632+ 12.491 + 9.815 + 13.646 + 16.17 21.65 9.85 12.99 12.096 15.03 13.55 10.55 9.94 5.22 4.849 2.146 3.445 5.076 9.953 9.97 + 10.765 + 9.122 + 8.33 11.23 10.78 9.13 10.08 13.07 10.83 8.87 7.12 9.67 + 1.276 1.678 1.558 1.538 11.887+3.970 11.31+10.295 9.03+2.268 10.317+2.32 10.12+1.953 12.15+3.439 11.257+2.112 8.96+1.547 8.45+1.416 6.853+2.449 Sand % 91.5 + 93.625 + 86.3 + 90.475 + 95.5 92.9 92.4 93.5 96.8 91.8 91 91.1 76.2 86.9 5.119 2.23 7.011 5.678 80.75+ 62.95 + 80.45 + 74.717 + 83.6 81.6 80.3 52.2 52.6 66.7 89.3 68.6 82.6 81.3 2.402 13.388 8.642 12.098 52.2 56.075+ 43.85 + 56.675 + 44.7 38.8 36.1 38.5 75.2 25.6 53.5 55 57.6 60.6 + 16.773 21.637 3.117 15.657 74.6+26.56 71.1+28.537 69.6+29.636 61.4+28.630 74.867+22.101 61.37+33.420 77.933+21.177 71.567+18.231 72.133+12.986 76.267+13.853 127 Silt % 0.233 0.2 + 0.25 + 0.25 + 0.3 0.2 0.2 0.1 0.3 0.4 0.5 0.3 0.1 0.1 + 0.081 0.129 0.191 0.130 0.275 0.15 + 0.25 + 0.425 + 0.3 0.1 0.1 0.5 0.3 0.1 0.8 0.2 0.1 0.6 + 0.1 0.191 0.330 0.237 0.433 0.275 + 0.875 + 0.15 + 0.1 0.1 0.4 0.3 2.2 0.6 0.1 0.2 0.2 0.1 + 0.35 0.892 0.057 0.6 0.233+0.115 0.133+0.057 0.233+0.152 0.3+0.2 0.933+1.097 0.367+0.251 0.467+0.351 0.233+0.057 0.133+0.057 0.267+0.288 Clay % 8.3 + 6.125 + 13.45 + 9.291 + 4.2 6.9 7.4 6.4 2.9 7.8 8.5 8.6 23.7 13.0 5.132 2.229 7.148 5.724 19.125 19.1 + 36.8 + 25.008 + 16.1 18.3 19.6 47.3 47.1 33.2 9.9 31.2 17.3 18.1 + 2.481 13.230 12.11 8.856 55.275 43.175 43.65 + 47.367 + 55.2 61.1 63.5 61.2 22.6 73.8 + 46.4 44.8 42.2 39.3 + 16.998 15.912 22.461 3.109 25.167+26.681 28.77+28.575 30.167+29.5 38.3+28.487 24.2+22.143 38.27+33.29 21.6+21.488 28.2+18.285 27.73+12.930 23.467+13.947 Organic carbon (g/kg) 1.5 13 40.125 18 5 2 2 6.75 18 8 36 35 24.25 23.708+ 26.35 0.8 7 21.2 15 67 24 29 33.75 34 0.5 20 2 14.125 23.025+21.709 0.5 50.5 27.75 30 34 28 2.5 23.625 6 37 3 5 12.75 21.375+20.01 0.933+0.513 23.5+23.57 21+7.94 35.333+31.02 18+14 11.167+15.45 19.333+14.05 15.167+19.28 19.667+16.50 14+18.25 Total Nitrogen (mg/kg) 805.575 875.64 682.99 788.067 + 840.6 1120.8 + 700.5 1050.8 910.65 840.6 + 700.5 630.45 700.5 700.5 + 166.648 232.329 145.84 35.025 1138.33 2206.6 1033.24 1459.38 + 1120.8 1260.9 + 1751.25 3362.4 1681.2 2031.45 + 1541.1 1120.8 770.55 700.5 + 719.245 88.1278 785.268 385.275 1576.15 1821.3 1681.23 1692.89 + 1401.0 2171.6 + 2241.6 1541.1 1471.05 2031.45 + 1401.0 2101.5 1891.4 1331 + 364.399 406.471 375.056 375.050 1120.8+280.2 1517.77+570.552 1564.45+787.348 1984.8+1217.992 1354.3+398.321 1634.5+687.537 1214.2+450.358 1284.25+749.022 1120.82+668.263 910.67+364.019 128 Total Phosphorous (mg/kg) 23.25 + 14.5 + 26.1 + 21.28 + 30.5 30.5 18 14.5 12 13.5 11.5 14.5 63.2 15.2 8.99 2.55 24.79 14.76 52.4 51.6 + 53.5 + 52.1 + 45.5 55 66 35 58.6 54.5 54.6 57.2 20.2 76.2 + 9.91 13.24 23.31 14.95 57.5 61.9 + 57.3 + 53.3 + 59.2 59.5 55.5 32.5 81 60 66 61.8 20 65.5 + 6.66 19.89 22.3 16.40 45.1+14.36 48.3+15.61 46.5+25.23 27.3+ 11.18 50.5+35.20 42.7+25.41 44.0+ 28.75 44.5+26.08 35+24.88 52.3+32.57 Potassium (Mg/kg) 33.825 47.075 61.5 + 47.467 + 110.0 59.0 100.0 14.6 11.8 8.9 + 22.3 71.0 70.0 25.0 + 40.087 36.191 44.178 27.074 72 + 48.5 + 76.7 + 65.733 + 149.0 49.0 100.0 37.3 30.1 26.6 28.8 63.0 94.0 121.0 52.012 34.621 39.765 40.768 185.25 128.7 + 462.8 + 258.917+ 224.0 240.0 + 117.5 57.1 114.7 225.5 93.2 150.0 1400.0 208.0 70.281 626.55 363.987 54.817 161+57.939 116+107.503 105.83+10.103 36.33+21.266 52.2+54.894 87+120.27 48.1+39.192 94.67+48.086 521.33+761.042 118+91.536 Sodium (ppt) 0.439 + 0.166 + 0.353 + 0.319+ 0.782 0.195 0.477 0.086 0.056 0.044 0.116 0.052 0.657 0.588 0.279 0.208 0.313 0.272 0.343 + 0.172 + 0.347 + 0.283 + 0.872 0.077 0.51 0.105 0.029 0.046 0.087 0.025 0.672 0.601 0.37 0.227 0.337 0.299 0.552 0.664 + 0.112 + 0.878 + 0.947 0.516 0.18 0.087 0.099 0.081 0.586 0.608 1.122 1.197 + 0.22 0.046 0.326 0.395 0.867+0.082 0.263+0.227 0.389+0.181 0.093+0.010 0.062+0.035 0.057+0.02 0.263+0.279 0.229+0.329 0.817+0.264 0.795+0.347 129 Table 2.11. Physico- chemical characteristics of sediment samples from habitats of Sonneratia alba. PRE MONSOON MONSOON POST MONSOON Seasonal Seasonal Seasonal Annual Apr May Mean+ Jun Jul Aug Sep Mean+ Oct Nov Dec Jan Mean+ Mean+ SD SD SD SD Sediment pH 7.955 8.272+ 7.502+ 8.09+ 8.29 8.05 8.41 6.69 6.75 8.16 7.74 8.04 8.26 8.32 + 0.162 0.909 0.262 0.607 8.145+ 7.645+ 8.28+ 8.023 + 8.11 7.87 8.27 6.95 7.08 8.28 8.7 8.1 8.25 8.07 0.219 0.729 0.29 0.512 7.167+ 5.795+ 7.16+ 6.707 + 7.54 7.6 6.77 6.74 4.66 5.01 6.4 7.32 7.57 7.35 0.471 1.117 0.518 0.963 7.98+0.391 7.84+0.226 7.817+0.909 6.793+0.13 6.163+1.312 7.15+1.854 7.613+1.155 7.82+0.434 8.027+0.395 7.913+0.503 Moisture (%) 9.455+ 12.31+ 9.635+ 10.467 + 7.2 13.71 12.67 13.97 11.97 10.63 12.43 10.19 7.37 8.55 2.9 1.393 2.193 2.448 8.08+ 10.427+ 9.637+ 9.381 + 9.12 8.91 7.85 10.99 12.18 10.69 8.78 14.17 7.52 8.08 1.164 1.834 3.065 2.211 10.752+ 9.482+ 9.845+ 10.026+ 9.38 10.73 9.29 10.61 10.28 7.75 10.89 10.2 10.56 7.73 1.777 1.284 1.437 1.478 8.57+1.19 11.117+2.423 9.937+2.474 11.857+1.84 11.477+1.041 9.69+1.68 10.7+1.832 11.52+2.295 8.483+1.8 8.12+0.411 Sand % 85.1+ 85.525+ 90.25+ 86.958+ 79.4 68.6 81.6 86.2 80.6 93.7 93.8 84.9 93.8 88.5 13.578 5.970 4.354 8.433 89.175+ 77.925+ 85.25+ 84.116+ 74.7 96.3 82.6 78.3 57.1 93.7 98.5 56.0 96.1 90.4 10.059 15.324 19.793 14.906 73.4+ 79.125+ 73.6+ 75.375+ 62.8 72.7 87.0 84.2 50.9 94.4 53.9 82.5 85.0 73.0 8.830 19.302 14.114 13.597 72.3+8.556 79.2+14.950 83.73+2.872 82.9+4.107 62.867+15.667 93.93+0.404 82.067+24.506 74.467+16.037 91.633+5.858 83.967+9.544 Silt % 0.3+ 0.85+ 0.15+ 0.433+ 0.4 0.2 0.2 2.4 0.4 0.4 0.3 0.1 0.1 0.1 0.115 1.037 0.1 0.631 0.3+ 1+ 0.175+ 0.491 + 0.5 0.2 0.1 2.7 0.5 0.7 0.3 0.1 0.1 0.2 0.141 1.160 0.095 0.72 0.2+ 0.8+ 0.775+ 0.591+ 0.4 0.1 0.1 1.8 0.8 0.5 0.3 2.6 0.1 0.1 0.141 0.725 1.22 0.799 0.433+0.0577 0.167+0.057 0.133+0.057 2.3+0.4583 0.567+0.208 0.533+0.152 0.3+0 0.933+1.443 0.1+1.7E-17 0.133+0.057 130 Clay % 14.6+ 13.675+ 9.6+ 12.625+ 20.2 31.2 18.2 11.4 19.2 5.9 5.9 15 6.1 11.4 13.601 6.235 4.409 8.455 15.4 10.525+ 21.075+ 14.6+ 24.8 3.5 17.3 19 42.4 5.6 1.2 43.9 3.8 9.5 + 9.917 15.414 19.838 14.8171 26.375+ 20.075+ 25.625+ 24.025+ 36.8 27.2 12.9 14 48.3 5.1 45.8 14.9 14.9 26.9 8.794 19.229 14.591 13.733 27.267+8.570 20.63+14.972 16.133+2.836 14.8+3.862 36.633+15.383 5.533+0.404 17.633+24.506 24.6+16.714 8.267+5.858 15.933+9.544 Organic carbon (g/kg) 5 4.5 3.375 5.5 26 7.1 29 16.9 32 5 16 115 42 20.758+31.64 5 77 29.25 2 23 7 37 17.25 32 1.5 32.5 27.5 23.375 23.292+21.55 1.2 62 24.175 11 13 15 17 14 19 35 12.5 9.5 19 19.058+15.73 3.733+2.19 47.83+38.27 6.167+4.54 20.667+6.81 9.7+4.6 27.67+10.1 27.667+7.5 13.833+18.4 20.333+10.7 50.667+56.44 Total Nitrogen (mg/kg) 700.5+ 1138.31+ 665.48+ 834.763+ 560.4 1260.9 1050.75 1401.0 1401.0 700.5 560.4 910.65 560.4 630.45 379.392 335.339 166.752 357.75 542.89+ 1068.26+ 753.04+ 788.063+ 700.5 420.3 1190.85 1260.9 1120.8 700.5 560.4 1260.9 560.4 630.45 119.633 251.758 340.181 321.876 409.79+ 1033.24+ 770.55+ 737.86+ 770.55 630.45 910.65 770.55 1050.75 1401.0 630.45 770.55 700.5 980.7 340.56 270.547 151.325 359.294 677.15+107.003 770.55+437.462 1050.75+140.1 1144.15+331.043 1190.85+185.334 934+404.433 583.75+40.443 980.7+252.568 607.1+80.886 747.2+202.216 Total Phosphorous (mg/kg) 48.8+ 45.9+ 29.8+ 41.48+ 55.6 66 44.5 62 39.6 37.5 25 26.1 22.5 45.5 14.7 11.13 10.59 14.13 39.7+ 45.2+ 28.0+ 37.64+ 50.2 27 42.2 61.5 53.8 23.2 13.2 52.1 16 30.8 10.01 16.66 17.81 15.67 39+ 30.3+ 20.2+ 29.82+ 22 38 24.5 28.8 15.8 52 18 18 21.2 23.5 13.90 15.46 2.68 13.58 42.6+18.04 43.7+20.11 37.1+10.94 50.8+19.03 36.4+19.20 37.6+14.40 18.7+5.93 32.1+17.82 19.9+3.44 33.3+11.21 Potassium (Mg/kg) 63.25 65+ 51.75+ 73+ 75.0 116.0 77.5 84.5 18.5 26.5 44.0 127.0 71.0 50.0 + 40.307 34.052 37.815 35.115 44.5+ 53.075+ 72.125+ 56.567+ 92.0 32.0 97.5 59.5 28.8 26.5 24.5 134.0 73.0 57.0 31.764 33.218 45.920 36.008 100+ 36.2+ 96.25+ 77.483 + 129.0 104.0 40.0 44.3 14.7 45.8 47.0 119.0 122.0 97.0 50.206 14.542 34.673 44.779 98.667+27.610 84+45.431 71.667+29.190 62.767+20.298 20.667+7.295 32.93+11.142 38.5+12.2168 126.67+7.505 88.667+28.884 68+25.357 131 Sodium (ppt) 0.441+ 0.357+ 0.622+ 0.473+ 0.707 0.511 0.28 0.233 0.822 0.094 0.3435 0.792 0.712 0.642 0.224 0.319 0.195 0.255 0.449 0.443+ 0.271+ 0.633+ 0.857 0.294 0.3875 0.249 0.1355 0.311 0.2805 0.772 0.737 0.742 + 0.276 0.106 0.235 0.250 0.652+ 0.084+ 0.769+ 0.501+ 0.982 0.488 0.1675 0.0762 0.0214 0.069 0.2815 0.902 1.052 0.842 0.237 0.061 0.337 0.381 0.849+0.137 0.431+0.119 0.278+0.11 0.186+0.095 0.326+0.433 0.158+0.133 0.302+0.036 0.822+0.07 0.834+0.189 0.742+0.1 132 As far as sediment pH confining to the habitats of Avicennia officinalis is concerned, higher annual average was noticed at Kadalundi 1 of Malappuram district (7.713 ± 0.466), followed by Thekkumbad 1 of Kannur district (6.633 ± 0.953) and Kumbalam 1 of Ernakulam district (6.488 ± 0.994). With respect to Bruguiera cylindrica, highest pH was noted at Kadalundi 2 (7.523 ± 0.469) followed by Thekkumbad 2 (6.85 ± 0.637) and Ayiramthengu 1 (6.848 ± 0.739). In the case of Excoecaria agallocha, higher pH was recorded at Ayiramthengu 2 (7.247 ± 0.497) followed by Kumbalam 2 (7.153 ± 1.12) and a lower pH of 6.638 ± 0.919 at Thekkumbad 3. The annual mean pH with respect to the habitats of Rhizophora mucronata was higher at Ayiramthengu 3 (7.51 ± 0.332) followed by Kumbalam 3 (6.878 ± 0.568) and Thekkumbad 4 (6.43 ± 0.80). With respect to Sonneratia alba, mean pH was higher at Kadalundi 4 (8.023 ± 0.513) followed by Kadalundi 3 (7.955 ± 0.608) and Thekkumbad 5 (6.708 ± 0.964). Annual average of moisture percentage of sediment confining to the habitat of Avicennia officinalis was higher at Kumbalam 1 (13.221 ± 4.288 %) followed by Thekkumbad 1 (12.197 ± 4.108 %) and Kadalundi 1 (9.407 ± 2.507 %). With respect to Bruguiera cylindrica, highest moisture percentage was noted at Thekkumbad 2 (11.529 ± 2.675 %) followed by Kadalundi 2 (9.85 ± 2.575 %) and Ayiramthengu 1 (7.117 ± 2.246 %). In the case of Excoecaria agallocha, higher moisture percentage was noticed at Thekkumbad 3 with 11.518 ± 4.212 % followed by Kumbalam 2 (11.117 ± 4.271 %) and lower at Ayiramthengu 2 (8.888 ± 1.612 %). Among the habitats of Rhizophora mucronata, Kumbalam 3 was noted for higher annual mean of moisture percentage (13.646 ± 5.077 %) followed by Thekkumbad 4 (9.953 ± 1.538%) and Ayiramthengu 3 (7.584 ± 2.474 %). With respect to Sonneratia alba higher moisture percentage was recorded at Kadalundi 3 (10.467 ± 2.448 %) followed by Thekkumbad 5 (10.027 ± 1.479 %) and Kadalundi 4 (9.382 ± 2.211 %). Among the habitats of Avicennia officinalis, the annual average of organic carbon content was higher at Kumbalam 1 (34.75 ± 29.78 g/kg) followed Thekkumbad 1 (21.37 ± 19.94 g/kg) and Kadalundi 1 (17.93 ± 12.57 g/kg). With respect to 133 Bruguiera cylindrica, highest organic carbon was noted at Thekkumbad 2 (26.65 ± 41.72 g/kg), followed by Ayiramthengu 1 (21.83 ± 24.14 g/kg) and Kadalundi 2 (20.28 ± 20.09 g/kg). In the case of Excoecaria agallocha, higher organic carbon was noticed at Ayiramthengu 2 (35.11 ± 71.53 g/kg) followed by Thekkumbad 3 (29.24 ± 33.35 g/kg) and lower value at Kumbalam 2 (17.5 ± 10.41 g/kg). Among the habitats of Rhizophora mucronata, annual mean organic carbon was noticed to be higher at Kumbalam 3 (23.03 ± 21.71 g/kg) followed by Thekkumbad 4 (21.38 ± 21.71 g/kg) and Ayiramthengu 3 (17.33 ± 18.15 g/kg). With respect to the habitats of Sonneratia alba, higher organic carbon was recorded at Kadalundi 4 (23.29 ± 21.56 g/kg) followed by Kadalundi 3 (20.38 ± 31.87 g/kg) and Thekkumbad 5 (19.06 ± 15.73 g/kg). As far as the nitrogen content of sediment confining to the habitat of Avicennia officinalis is concerned, higher annual average was noticed at Kumbalam 1 (5610.83 ± 4488.08 mg/kg) followed by Kadalundi 1 (4907.5 ± 1125.5 mg/kg) and Thekkumbad 1 (2269.17 ± 2432.11 mg/kg). With respect to Bruguiera cylindrica, highest nitrogen content was noted at Kadalundi 2 (1545.83 ± 395.37 mg/kg) followed by Thekkumbad 2 (1499.167 ± 683.55 mg/kg) and Ayiramthengu 1 (816.67 ± 455.937 mg/kg). Among the habitats of Excoecaria agallocha, higher nitrogen was recorded at Thekkumbad 3 (1628.7 ± 1072.88 mg/kg) followed by Kumbalam 2 (1517.75 ± 531.249 mg/kg) and lower nitrogen of 788.06 ± 137.29 mg/kg at Ayiramthengu 2. The annual mean value of nitrogen with respect to the habitats of Rhizophora mucronata was higher at Thekkumbad 4 (1692.89 ± 364.40 mg/kg) followed by Kumbalam 3 (1459.38 ± 719.245 mg/kg) and Ayiramthengu 3 (788.067 ± 166.648 mg/kg). With respect to the study sites of Sonneratia alba, higher nitrogen was noticed at Kadalundi 3 (834.763 ± 357.758 mg/kg) followed by Kadalundi 4 (788.063 ± 321.877 mg/kg) and Thekkumbad 5 (737.86 ± 359.295 mg/kg). Considering the phosphorous content of sediments confining to the habitat of Avicennia officinalis, higher annual average was noticed at Thekkumbad 1 (0.231 ± 0.072 mg/kg) followed by Kumbalam 1 (0.194 ± 0.076 mg/kg) and Kadalundi 1 134 (0.097 ± 0.032 mg/kg). With respect to Bruguiera cylindrica, highest phosphorous was noted at Kadalundi 2 (0.5802 ± 0.177 mg/kg) followed by Thekkumbad 2 (0.2434 ± 0.111 mg/kg) and Ayiramthengu 1 (0.1148 ± 0.0401 mg/kg). Among the habitats of Excoecaria agallocha, higher mean of phosphorous was noticed at Kumbalam 2 (0.431 ± 0.122 mg/kg) followed by Thekkumbad 3 (0.236 ± 0.175 mg/kg) and lower at Ayiramthengu 2 (0.154 ± 0.060 mg/kg). The annual mean phosphorous value with respect to the habitats of Rhizophora mucronata was higher at Thekkumbad 4 (0.575 ± 0.15 mg/kg) followed by Kumbalam 3 (0.524 ± 0.15 mg/kg) and Ayiramthengu 3 (0.213 ± 0.148 mg/kg). In the case of Sonneratia alba, higher phosphorous value was recorded at Kadalundi 3 (0.415 ± 0.141 mg/kg) followed by Kadalundi 4 (0.376 ± 0.157 mg/kg) and Thekkumbad 5 (0.298 ± 0.136 mg/kg). Higher annual mean value of potassium with respect to Avicennia officinalis was noticed at Kadalundi 1 (76.333 ± 55.296 mg/kg), followed by Thekkumbad 1 (60.45 ± 35.5778 mg/kg) and Kumbalam 1 (55.558 ± 51.78 mg/kg). In the case of Bruguiera cylindrica, annual mean potassium level was noticed at Kadalundi 2 (73.583 ± 58.88 mg/kg) followed by Thekkumbad 2 (69.233 ± 70.238 mg/kg) and Ayiramthengu 1 (48.392 ± 38.137 mg/kg). As far as the potassium concentration of sediment confining to the habitat of Excoecaria agallocha is concerned, higher annual average was noticed at Thekkumbad 3 (56.792 ± 47.98 mg/l) followed by Ayiramthengu 2 (41.508 ± 28.39 mg/l) and Kumbalam 2 (35.158 ± 35.89 mg/l). Higher annual mean value of potassium with respect to Rhizophora mucronata was noticed at Thekkumbad 4 (258.917 ± 363.99 mg/l) followed by Kumbalam 3 (65.733 ± 40.77 mg/l) and Ayiramthengu 3 (47.467 ± 36.19 mg/l). With respect to Sonneratia alba, highest potassium level was noted at Thekkumbad 5 (77.483 ± 44.78 mg/l) followed by Kadalundi 3 (63.25 ± 35.12 mg/l) and Kadalundi 4 (56.567 ± 36.01 mg/l). With respect to Avicennia officinalis, higher mean sodium was noticed at Thekkumbad 1 (1.055 ± 1.523 ppt) followed by Kadalundi 1 (0.43 ± 0.24 ppt) and Kumbalam 1 of Ernakulam district (0.342 ± 0.25 ppt). Upon considering the sediment sodium concentration along the habitats of Bruguiera cylindrica, highest 135 annual average was noted at Thekkumbad 2(0.677 ± 0.794 ppt) followed by Kadalundi 2(0.490 ± 0.469 ppt) and Ayiramthengu 1(0.342 ± 0.289 ppt). As far as the sediment sodium confining to the habitat of Excoecaria agallocha is concerned, higher annual average was noticed at Thekkumbad 3 (0.441 ± 0.48 ppt) followed by Kumbalam 2 (0.341 ± 0.236 ppt) and Ayiramthengu 2 (0.316 ± 0.218 ppt). In the case of Rhizophora mucronata, annual mean sodium was higher at Thekkumbad 4 (0.552 ± 0.396 ppt) followed by Ayiramthengu 3 (0.319 ± 0.272 ppt) and Kumbalam 3 (0.287 ± 0.299 ppt). ). With respect to Sonneratia alba, highest sodium was noted at Thekkumbad 5 (0.502 ± 0.381 ppt) followed by Kadalundi 3 (0.474 ± 0.256 ppt) and Kadalundi 4 (0.449 ± 0.251 ppt). The result of the textural characteristics revealed that, higher annual mean sand percentage with respect to Avicennia officinalis was noticed at Thekkumbad 1 (87.292 ± 10.987 %) followed by Kadalundi 1 (83.783 ± 13.027%) and Kumbalam 1 (78.45 ± 13.935 %). With respect to Bruguiera cylindrica, highest percentage of sand was noted at Thekkumbad 2 (86.842 ± 8.902 %) followed by Ayiramthengu 1 (86.075 ± 12.89 %) and Kadalundi 2 (82.025 ± 8.681 %). Among various habitats of Excoecaria agallocha, higher sand % was noticed at Ayiramthengu 2 with 90.358 ± 6.596 % followed by 86.175 ± 9.022 % at Thekkumbad 3 and a lower of 83.3 ± 10.865 % at Kumbalam 2. In the case of Rhizophora mucronata, annual mean sand % was higher at Ayiramthengu 3 (90.475 ± 5.678 %) followed by Kumbalam 3 (74.717 ± 12.098 %) and Thekkumbad 4 (52.2 ± 15.658 %). With respect to Sonneratia alba, higher sand % was noticed at Kadalundi 3 (86.958 ± 8.434 %) followed by Kadalundi 4 (84.117 ± 14.907 %) and Thekkumbad 5 (75.375 ± 13.597 %). Results of silt % of sediment confining to the habitat of Avicennia officinalis revealed that, higher annual average was noticed at Kumbalam 1 (0.475 ± 0.673 %) followed by Kadalundi 1 (0.408 ± 0.394 %) and Thekkumbad 1 (0.267 ± 0.215 %). With respect to Bruguiera cylindrica, highest silt % was noted at Thekkumbad 2 (0.408 ± 0.513 %) followed by Ayiramthengu 1 (0.433 ± 0.311 %) and Kadalundi 2 (0.333 ± 0.416 %). Among the habitats of Excoecaria agallocha, higher silt % was noted at Thekkumbad 3 with 0.983 ± 1.928 % followed by 0.572 ± 0.623 % at Ayiramthengu 2 and a lower of 0.383 ± 0.475 % at Kumbalam 2. In the case of Rhizophora mucronata, the annual mean silt % was higher at Thekkumbad 4 (0.433 136 ± 0.601 %) followed by Kumbalam 3 (0.275 ± 0.238 %) and Ayiramthengu 3 (0.233 ± 0.130 %). With respect to Sonneratia alba, higher silt % was noted at Thekkumbad 5 (0.592 ± 0.799 %) followed by Kadalundi 4 (0.492 ± 0.720 %) and Kadalundi 3 (0.433 ± 0.632 %). Among various habitats of Avicennia officinalis, the annual mean clay % was higher at Kumbalam 1 of Ernakulam district (21.075 ± 13.947 %) followed by Kadalundi 1 of Malappuram district (15.808 ± 12.759%) and Thekkumbad 1 of Kannur district (12.442 ± 10.858 %). With respect to Bruguiera cylindrica, highest clay % was noted at Kadalundi 2 (17.642 ± 8.684 %) followed by Ayiramthengu 1 (13.642 ± 13.013 %) and Thekkumbad 2 (12.725 ± 8.868 %). In the case of Excoecaria agallocha, higher clay % was recorded at Kumbalam 2 with 16.317 ± 10.954 % followed by 12.842 ± 9.526 % at Thekkumbad 3 and lower of 9.067 ± 6.403 % at Ayiramthengu 2. The annual mean clay % with respect to Rhizophora mucronata was higher at Thekkumbad 4 (47.367 ± 15.912 %) followed by Kumbalam 3 (25.008 ± 12.11 %) and Ayiramthengu 3 (9.292 ± 5.724 %). With respect to Sonneratia alba, higher clay % was recorded at Thekkumbad 5 (24.025 ± 13.734 %) followed by Kadalundi 4 (15.4 ± 14.817 %) and Kadalundi 3 (12.625 ± 8.456 %). Soil texture is the relative proportion of various particles that make up the soil. The texture of soil is a qualitative classification technique used both in the field and laboratory. As a qualitative tool, it is fast, simple and effective to assess the physical characteristics of soils. The soils/ sediments distributed along the natural habitats of mangrove species Avicennia officinalis, Bruguiera cylindrica, Excoecaria agallocha, Rhizophora mucronata and Sonneratia alba were subjected to textural analysis. Based on the objective, the estimated percentages of sand, silt and clay were used to determine the textural class of the soil. This was achieved through the triangular textural diagram, proposed by the United States Department of Agriculture (USDA). Based on the physical composition, the textural classes were indicated as sand, loamy sands, sandy loams, loam, silt loam, silt, sandy clay loam, clay loam, silty clay loam, sandy clay, silty clay and clay. Subclasses of sand were subdivided into coarse sand, sand, fine sand and very fine sand. Subclasses of loamy sands and sandy loams, which were based on sand size, were named similarly (USDA, 1993). 137 In the present study, physical characterization of sand / sediment confining to the natural habitats of 5 mangrove species has been carried out to evaluate the annual average value of % sand, % silt and % clay. Accordingly all the sediment samples have been categorized into different classes (Plate 2.6). The results obtained are depicted in Table 2.12 – 2.13. Table 2.12. Textural classes of sediments noticed along mangrove habitats under study Textural class Site Avicennia Bruguiera Excoecaria Rhizophora Sonneratia officinalis cylindrica agallocha mucronata alba Sandy Clay 1. Loamy Sand Sand Sand Loamy Sand Loam Sandy Clay 2. Sandy Loam Sandy Loam Sandy Loam Sandy Loam Loam Sandy Clay 3. Loamy Sand Loamy Sand Loamy Sand Sandy Clay Loam Table 2.13. Description of each sediment class noticed in the present study Sl. Soil / Description No. sediment class 1 Sand A total of 25 percent or more very coarse, coarse, and medium sand, a total of less than 25 percent very coarse and coarse sand, and less than 50 percent fine sand and less than 50 percent very fine sand 2 Loamy sand A total of 25 percent or more very coarse, coarse, and medium sand and a total of less than 25 percent very coarse and coarse sand, and less than 50 percent fine sand and less than 50 percent very fine sand 3 Sandy loam A total of 30 percent or more very coarse, coarse, and medium sand, but a total of less than 25 percent very coarse and coarse sand and less than 30 percent fine sand and less than 30 percent very fine sand; or a total of 15 percent or less very coarse, coarse, and medium sand, less than 30 percent fine sand and less than 30 percent very fine sand with a total of 40 percent or less fine and very fine sand 4 Sandy clay 20 to 35 percent clay, less than 28 percent silt, and more than 45 loam percent sand 138 The species Avicennia officinalis was growing in the textural classes of Sandy Clay Loam, Sandy Loam and Loamy Sand. As far as Bruguiera cylindrica concerned, Loamy Sand and Sandy Loam were suitable for their growth. Sand, Sandy Loam and Loamy Sand are suitable for the establishment of Excoecaria agallocha. Rhizophora mucronata mostly preferred Sand, Sandy Clay Loam and Sandy Clay. The sediment classes observed with respect to the species Sonneratia alba were Loamy Sand, Sandy Loam and Sandy Clay Loam. Upon considering the annual mean values of textural characteristics with respect to the sites under study, all the mangrove species were noticed to prefer a particular class of sediment. All the 5 species under study have shown maximum growth and proliferation along such sediment habitats. The ideal sediment class in which each mangrove species has shown a consistent growth are Avicennia officinalis (Sandy Loam), Bruguiera cylindrica (Loamy Sand), Excoecaria agallocha (Loamy Sand), Rhizophora mucronata (Sandy Clay Loam) and Sonneratia alba (Sandy Loam). Data pertaining to climatological attributes like atmospheric maximum – minimum temperature (0C), Total Rainfall (MMS) and Relative Humidity (%) with respect to all the locations under study has been collected and reported. The results are represented in the following tables (Table 2.14 – 2.18). 139 Table 2.14. Climatological attributes experienced along the habitats of Avicennia officinalis. POST MONSOON Season PRE MONSOON MONSOON Seasonal Seasonal Seasonal Annual Station Feb Mar Apr May Mean+ Jun Jul Aug Sep Mean+ Oct Nov Dec Jan Mean+ Mean+ SD SD SD SD Atmospheric Maximum Temperature (0C) 33.8 + 31.1+ 32.1 + 32.325 + S1 32.8 34.1 34.3 33.9 32.5 30.5 30.8 30.6 31.1 32.2 32.3 32.8 0.670 0.941 0.716 1.353 34.1 + 29.4 + 31.9 + 31.792+ S2 33.5 34.8 34.6 33.3 30.9 28.0 29.1 29.7 30.4 32.0 32.2 33.0 0.759 1.209 1.089 2.185 34.9 + 29.9 + 32.8 + 32.516+ S3 34.2 35.4 35.5 34.3 32.0 28.0 28.9 30.6 31.2 33.2 33.3 33.6 0.695 1.780 1.096 2.424 Monthly 33.5 + 34.77+ 34.8 + 33.83+ 3.18 + 28.83 + 29.6 + 30.3 + 30.9 + 32.47+ 32.6 + 33.13+ Mean+ 0.7 0.65 0.624 0.503 0.818 1.443 1.044 0.519 0.435 0.642 0.638 0.416 SD Atmospheric Minimum Temperature (0C) 24.5 + 23.4 + 22.575 + 23.492 + S1 22.8 24.2 25.7 25.3 24.5 22.1 23.0 24.0 22.8 23.3 22.0 22.2 1.298 1.067 0.591 1.242 24.9 + 23.0 + 22.5 + 23.275 + S2 23.2 25.1 26.1 25.2 23.9 22.4 22.8 23.0 23.1 23.4 21.6 21.9 1.219 0.634 0.883 1.373 24.0 + 23.675 + 24.358 + S3 23.9 25.2 26.9 25.7 25.4 + 1.24 24.6 23.4 23.9 24.0 24.1 24.7 22.7 23.2 0.492 0.896 1.158 Monthly 23.3 + 24.83+ 26.23+ 25.4 + 24.33 + 22.63 + 23.23 + 23.67+ 23.33 + 23.8 + 22.1 + 22.43+ Mean+ 0.556 0.550 0.611 0.264 0.378 0.680 0.585 0.577 0.680 0.781 0.556 0.680 SD Total Rainfall (MMS) 99.6 + 431.6 + 152.6 + 227.942+ S1 5.0 21.8 54.9 316.8 412.8 718.7 318.8 276.1 331.1 197.3 82.0 0.0 146.26 199.736 143.91 213.299 58.2 + 537.0 + 71.6 + 222.25 + S2 1.0 0.0 41.9 189.7 477.9 974.5 340.8 354.7 139.0 131.7 9.1 6.7 89.846 298.12 73.65 286.323 73.7 + 590.7 + 84.2 + 249.533+ S3 4.9 0.0 23.1 266.9 565.3 1131.6 389.9 276.1 286.2 49.8 0.0 0.6 129.166 379.7 136.71 335.385 Monthly 3.63 + 7.27 + 39.97+ 257.8+ 485.33+ 941.6 + 349.83+ 302.3+ 252.1 + 126.27 + 30.37+ 2.43 + Mean+ 2.281 12.586 15.988 64.037 76.521 208.407 36.401 45.38 100.487 73.9 44.947 3.707 SD Relative Humidity % at 0830hrs 78.5 + 90.3 + 78.5 + 82.417 + S1 76 78 79 81 88 93 89 91 85 81 76 72 2.082 2.217 5.686 6.694 75.8 + 89.0 + 78.8 + 81.167 + S2 75 74 76 78 88 92 89 87 86 83 72 74 1.708 2.160 6.801 7.056 140 75.5 + 92.8 + 74.0 + 80.75 + S3 76 72 75 79 91 97 92 91 87 76 65 68 2.887 2.872 9.832 10.48 Monthly 75.67+ 74.67+ 76.67+ 79.33+ 89.0 + 94.0 + 90.0 + 89.67+ 80.0 + 71.0 + 71.33+ Mean+ 86.0 + 1.0 0.577 3.055 2.082 1.528 173 2.646 1.732 2.309 3.606 5.568 3.055 SD Relative Humidity % at 1730hrs 69.0 + 82.5 + 66.8 + 72.75 S1 63 65 74 74 81 84 81 84 75 73 62 57 5.831 1.732 8.655 +9.126 62.0 + 65.5 + 68.917 + S2 56 57 65 70 77 86 77 77 79.3 + 4.5 76 73 58 55 6.683 10.535 10.414 66.5+ 86.8+ 71.3+ 74.833 + S3 64 63 67 72 83 94 86 84 82 74 63 66 4.041 4.992 8.539 10.616 Monthly 61.0 + 61.67+ 68.67+ 72.0 + 80.33 + 88.0 + 81.33+ 81.67+ 77.67 + 73.33+ 61.0 + 59.33+ Mean+ 4.358 4.163 4.725 2.0 3.055 5.291 4.509 4.041 3.785 0.577 2.645 5.859 SD Table 2.15. Climatological attributes experienced along the habitats of Bruguiera cylindrica. Season PRE MONSOON MONSOON POST MONSOON Seasonal Seasonal Seasonal Station Feb Mar Apr May Mean+ Jun Jul Aug Sep Mean+ Oct Nov Dec Jan Mean+ Annual SD SD SD Mean+ SD Atmospheric Maximum Temperature (0C) 35.5 + 30.7 + 32.7 + 33.0 + S4 35.5 36.6 36.1 33.7 32.2 28.9 30.5 31.1 32.0 32.9 32.3 33.6 1.265 1.376 0.707 2.305 34.1 + 29.4 + 31.9 + 31.8 + S5 33.5 34.8 34.6 33.3 30.9 28.0 29.1 29.7 30.4 32.0 32.2 33.0 0.759 1.209 1.089 2.185 34.9 + 29.9 + 32.8 + 32.5 + S6 34.2 35.4 35.5 34.3 32.0 28.0 28.9 30.6 31.2 33.2 33.3 33.6 0.695 1.780 1.096 2.424 Monthly 34.4 + 35.6 + 35.4 + 33.77 + 28.3 + 29.5 + 30.47 + 31.2 + 32.7 + 32.6 + 33.4 + Mean+ 31.7 + 0.7 1.014 0.916 0.755 0.503 0.52 0.872 0.709 0.8 0.625 0.608 0.346 SD Atmospheric Minimum Temperature (0C) 22.0 + 22.9 + 21.5 + 22.1 + S4 20.4 21.5 23.0 23.2 22.9 22.9 23.1 22.5 22.3 22.4 20.9 20.5 1.322 0.251 0.967 1.036 24.9 + 23.0 + 22.5 + 23.5 + S5 23.2 25.1 26.1 25.2 23.9 22.4 22.8 23.0 23.1 23.4 21.6 21.9 1.219 0.634 0.883 1.373 25.4 + 24.0 + 23.7 + 24.4 + S6 23.9 25.2 26.9 25.7 24.6 23.4 23.9 24.0 24.1 24.7 22.7 23.2 1.24 0.492 0.895 1.158 141 Monthly 22.5 + 23.93 + 25.33 + 24.7 + 23.8 + 23.27 + 23.17 + 23.17 + 23.5 + 21.73 + 21.87 + Mean+ 22.9 + 0.5 1.852 2.107 2.059 1.322 0.854 0.568 0.763 0.901 1.153 0.907 1.35 SD Total Rainfall (MMS) 178.9 + 311.0 + 180.0 + 223.3 + S4 12.2 42.6 265.8 395.1 279.4 463.4 187.8 313.4 412.2 287.5 19.5 0.6 183.176 114.613 202.828 167.778 58.2 + 537.0 + 71.6 + 222.3 + S5 1.0 0.0 41.9 189.7 477.9 974.5 340.8 354.7 139.0 131.7 9.1 6.7 89.846 298.120 73.65 286.3232 73.7 + 590.7 + 84.2 + 249.5 + S6 4.9 0.0 23.1 266.9 565.3 1131.6 389.9 276.1 286.2 49.8 0.0 0.6 129.166 379.698 136.706 335.385 Monthly 314.73 6.03 + 14.2 + 110.27 + 283.9 + 440.87 + 856.5 + 306.17 + 279.13 + 156.33 + 9.53 + 2.63 + Mean+ + 5.685 24.595 135.023 103.749 146.503 349.379 105.407 136.737 120.749 9.757 3.521 SD 39.317 R.H% at 0830hrs 84.3 + 91.8 + 86.1 + S4 80 79 88 90 92 96 91 88 88 85 83 73 82.3 + 6.5 5.560 3.304 6.416 75.8 + 89.0 + 81.2 + S5 75 74 76 78 88 92 89 87 86 83 72 74 78.8 + 6.8 1.707 2.160 7.056 75.5 + 92.8 + 74.0 + 80.8 + S6 76 72 75 79 91 97 92 91 87 76 65 68 2.886 2.872 9.831 10.48 Monthly 77.0 + 75.0 + 79.67 + 82.33 + 90.33 + 95.0 + 90.67 + 88.67+ 87.0 + 81.33 + 73.33+ 71.67+ Mean+ 2.645 3.605 7.234 6.658 2.081 2.645 1.527 2.081 1.0 4.725 9.073 3.214 SD R.H% at 1730hrs 66.8 + 80.0 + 68.8 + 71.8 + S4 55 57 75 80 84 84 76 76 76 75 71 53 12.606 4.618 10.72 10.844 62.0 + 65.5 + 68.9 + S5 56 57 65 70 77 86 77 77 79.3 + 4.5 76 73 58 55 6.683 10.535 10.413 66.5 + 86.8 + 71.3 + 74.8 + S6 64 63 67 72 83 94 86 84 82 74 63 66 4.041 4.991 8.539 10.615 Monthly 58.33+ 59.0 + 69.0 + 74.0 + 81.33 + 88.0 + 79.67 + 79.0 + 78.0 + 74.0 + 64.0 + 58.0 + Mean+ 4.932 3.464 5.291 5.291 3.785 5.291 5.507 4.358 3.464 1.0 6.557 7.0 SD 142 Table 2.16. Climatological attributes experienced along the habitats of Excoecaria agallocha. Season PRE MONSOON MONSOON POST MONSOON Annual Station Feb Mar Apr May Seasonal Jun Jul Aug Sep Seasonal Oct Nov Dec Jan Seasonal Mean+ Mean+ Mean+ Mean+ SD SD SD SD Atmospheric Maximum Temperature (0C) 35.5 + 30.7 + 32.7 + 32.95 + S7 35.5 36.6 36.1 33.7 32.2 28.9 30.5 31.1 32.0 32.9 32.3 33.6 1.265 1.376 0.707 2.305 33.8 + 31.1 + 32.1 + 32.333 + S8 32.8 34.1 34.3 33.9 32.5 30.5 30.8 30.7 31.1 32.2 32.3 32.8 0.670 0.925 0.716 1.342 34.9 29.9 + 32.8 + 32.516 + S9 34.2 35.4 35.5 34.3 32.0 28.0 28.9 30.6 31.2 33.2 33.3 33.6 0.695 1.780 1.096 2.424 Monthly 34.17 + 35.37 + 35.3 + 33.97 + 32.23 + 29.13 + 30.07 + 30.8 + 31.43 + 32.77 + 32.63 + 33.33 + Mean+ 1.350 1.25 0.916 0.305 0.251 1.266 1.021 0.264 0.493 0.513 0.577 0.461 SD Atmospheric Maximum Temperature (0C) 22.0 + 22.9 + 21.5 + 22.133 + S7 20.4 21.5 23.0 23.2 22.9 22.9 23.1 22.5 22.3 22.4 20.9 20.5 1.322 0.251 0.967 1.036 24.5 + 23.2 + 22.6 + 23.425 + S8 22.8 24.2 25.7 25.3 24.5 22.1 23.0 23.2 22.8 23.3 22.0 22.2 1.298 0.989 0.59 1.234 25.4 + 24.0 + 23.7 + 24.358+ S9 23.9 25.2 26.9 25.7 24.6 23.4 23.9 24.0 24.1 24.7 22.7 23.2 1.242 0.492 0.895 1.158 Monthly 22.37 + 23.63 + 25.2 + 24.73 + 24.0 + 22.8 + 23.33 + 23.23+ 23.07 + 23.47 + 21.87 + 21.97 + Mean+ 1.789 1.914 1.997 1.342 0.953 0.655 0.493 0.750 0.929 1.159 0.907 1.365 SD Total Rainfall (MMS) 223.2917 178.9 + 311.0 + 180.0 + S7 12.2 42.6 265.8 395.1 279.4 463.4 187.8 313.4 412.2 287.5 19.5 0.6 + 183.176 114.612 202.828 167.778 99.6+ 418.3 + 152.6 + 223.508 + S8 5.0 21.8 54.9 316.8 412.8 718.7 318.8 222.9 331.1 197.3 82.0 0.0 146.26 214.749 143.911 212.759 73.7+ 590.7+ 84.2 + 249.533 + S9 4.9 0.0 23.1 266.9 565.3 1131.6 389.9 276.1 286.2 49.8 0.0 0.6 129.166 379.698 136.706 335.385 Monthly 7.37 + 21.47 + 114.6 + 326.27 + 419.17 + 771.23 + 298.83 + 270.8 + 343.17 + 178.2 + 33.83 + 0.4 + Mean+ 4.186 21.302 131.904 64.622 143.056 337.183 102.518 45.482 63.86 119.996 42.837 0.346 SD 143 R.H% at 0830hrs 84.3 + 91.8 + 82.3 + 86.083 + S7 80 79 88 90 92 96 91 88 88 85 83 73 5.56 3.304 6.5 6.416 78.5 + 89.3 + 78.5 + 82.083 + S8 76 78 79 81 88 93 89 87 85 81 76 72 2.081 2.629 5.686 6.316 75.5 + 92.8 + 74.0 + 80.75 + S9 76 72 75 79 91 97 92 91 87 76 65 68 2.8868 2.8723 9.831 10.480 Monthly 77.33 76.33 80.67 + 83.33 + 90.33 + 95.33 + 90.67 + 88.67 + 86.67 + 80.67 + 74.67 + 71.0 + Mean+ +2.309 +3.785 6.658 5.859 2.081 2.081 1.527 2.081 1.527 4.509 9.073 2.645 SD R.H% at 1730hrs 66.8 + 80.0 + 68.8 + 71.833 + S7 55 57 75 80 84 84 76 76 76 75 71 53 12.606 4.618 10.719 10.844 69.0 + 81.5 + 66.8 + 72.416+ S8 63 65 74 74 81 84 81 80 75 73 62 57 5.831 1.732 8.655 8.743 66.5 + 86.8 + 71.3 + 74.833 + S9 64 63 67 72 83 94 86 84 82 74 63 66 4.041 4.991 8.539 10.615 Monthly 60.67 + 61.67 + 72.0 + 75.33 + 82.67 + 87.33 + 77.67 + 65.33 + 58.67 Mean+ 81.0 + 5 80.0 + 4 74.0 + 1 4.932 4.163 4.358 4.163 1.527 5.773 3.785 4.932 +6.658 SD Table 2.17. Climatological attributes experienced along the habitats of Rhizophora mucronata. Season PRE MONSOON MONSOON POST MONSOON Seasonal Seasonal Seasonal Annual Feb Mar Apr May Mean+ Jun Jul Aug Sep Mean+ Oct Nov Dec Jan Mean+ Mean+ Station SD SD SD SD Atmospheric Maximum Temperature (0C) 35.5 + 30.7 + 32.7 + 32.95 + S10 35.5 36.6 36.1 33.7 32.2 28.9 30.5 31.1 32.0 32.9 32.3 33.6 1.265 1.376 0.707 2.305 31.1 + 33.8 + 32.1 + 32.333 + S11 32.8 34.1 34.3 33.9 32.5 30.5 30.8 30.7 0.925 31.1 32.2 32.3 32.8 0.670 0.716 1.342 34.9 + 29.9 + 32.8 + 32.516 + S12 34.2 35.4 35.5 34.3 32.0 28.0 28.9 30.6 31.2 33.2 33.3 33.6 0.695 1.780 1.096 2.424 Monthly 34.17 + 35.37 + 35.3 + 33.97 + 32.23 + 29.13 + 30.07 + 30.8 + 31.43 + 32.77 + 32.63 + 33.33 + Mean+ 1.350 1.250 0.916 0.305 0.251 1.266 1.021 0.264 0.493 0.513 0.577 0.461 SD 144 Atmospheric Minimum Temperature (0C) 22.0 + 22.9 + 21.5 + 22.133 + S10 20.4 21.5 23.0 23.2 22.9 22.9 23.1 22.5 22.3 22.4 20.9 20.5 1.322 22.85 0.967 1.036 24.5 + 23.2 + 22.6 + 23.425 + S11 22.8 24.2 25.7 25.3 24.5 22.1 23.0 23.2 22.8 23.3 22.0 22.2 1.298 23.2 0.590 1.235 25.4 + 24.0 + 23.7 + 24.358 + S12 23.9 25.2 26.9 25.7 24.6 23.4 23.9 24.0 24.1 24.7 22.7 23.2 1.242 23.975 0.895 1.158 Monthly 25.2 + 22.37 + 23.63 + 24.73 + 24.0 + 22.8 + 23.33 + 23.23 + 23.07 + 23.47 + 21.87 + 21.97 + Mean+ 1.997 1.789 1.914 1.342 0.953 0.655 0.493 0.750 0.929 1.159 0.907 1.365 SD Total Rainfall (MMS) 178.9 + 311.0 + 180.0 + 223.292 + S10 12.2 42.6 265.8 395.1 279.4 463.4 187.8 313.4 412.2 287.5 19.5 0.6 183.176 114.612 202.828 167.778 99.6 + 418.3 + 152.6 + 223.508 + S11 5.0 21.8 54.9 316.8 412.8 718.7 318.8 222.9 331.1 197.3 82.0 0.0 146.26 214.749 143.911 212.759 73.7 + 590.7 + 84.2 + 249.533 + S12 4.9 0.0 23.1 266.9 565.3 1131.6 389.9 276.1 286.2 49.8 0.0 0.6 129.166 379.698 136.706 335.385 Monthly 419.17 + 7.37 + 21.47 + 114.6 + 326.27 + 771.23 + 298.83 + 270.8 + 343.17 + 178.2 + 33.83 + 0.4 + Mean+ 143.056 4.186 21.302 131.904 64.622 337.183 102.518 45.482 63.860 119.995 42.837 0.346 SD R.H% at 0830hrs 84.3 + 91.8 + 82.3 + 86.083 + S10 80 79 88 90 92 96 91 88 88 85 83 73 5.560 3.304 6.5 6.416 78.5 + 89.3 + 78.5 + 82.083 + S11 76 78 79 81 88 93 89 87 85 81 76 72 2.081 2.63 5.686 6.316 75.5 + 92.8 + 74.0 + 80.75 + S12 76 72 75 79 91 97 92 91 87 76 65 68 2.886 2.872 9.832 10.480 Monthly 80.67 + 77.33 + 76.33 + 83.33 + 90.33 + 95.33 + 90.67 + 88.67 + 86.67 + 80.67 + 74.67 + 71.0 + Mean+ 6.658 2.309 3.786 5.859 2.081 2.081 1.527 2.081 1.527 4.509 9.073 2.645 SD R.H% at 1730hrs 66.8 + 80.0 + 68.8 + 71.833 + S10 55 57 75 80 84 84 76 76 76 75 71 53 12.606 4.618 10.719 10.845 69.0 + 81.5 + 66.8 + 72.417 + S11 63 65 74 74 81 84 81 80 75 73 62 57 5.831 1.732 8.655 8.743 66.5 + 86.8 + 71.3 + 74.833 + S12 64 63 67 72 83 94 86 84 82 74 63 66 4.041 4.991 8.539 10.615 Monthly 60.67 + 61.67 + 72.0 + 75.33 + 82.67 + 87.33 + 80.0 + 77.67 + 65.33 + 58.67 + Mean+ 81.0 + 5.0 74.0 + 1.0 4.932 4.163 4.358 4.163 1.527 5.773 4.0 3.785 4.932 6.658 SD 145 Table 2.18. Climatological attributes experienced along the habitats of Sonneratia alba Season PRE MONSOON MONSOON POST MONSOON Feb Mar Apr May Seasonal Jun Jul Aug Sep Seasonal Oct Nov Dec Jan Seasonal Annual Mean+ Mean+ Mean+ Mean+ Station SD SD SD SD Atmospheric Maximum Temperature (0C) 32.95 35.5 + 30.7 + 32.7 + S13 35.5 36.6 36.1 33.7 32.2 28.9 30.5 31.1 32.0 32.9 32.3 33.6 + 1.265 1.376 0.707 2.305 31.791 34.1 + 29.4 + 31.9 + S14 33.5 34.8 34.6 33.3 30.9 28.0 29.1 29.7 30.4 32.0 32.2 33.0 + 0.759 1.209 1.089 2.185 32.516 34.9 + 29.9 + 32.8+ S15 34.2 35.4 35.5 34.3 32.0 28.0 28.9 30.6 31.2 33.2 33.3 33.6 + 0.695 1.780 1.096 2.424 Monthly 34.4 + 35.6 + 35.4 + 33.77 + 28.3 + 29.5 + 30.47 + 31.2 + 32.7 + 32.6 + 33.4 + Mean+ 31.7 + 0.7 1.014 0.916 0.755 0.503 0.519 0.871 0.709 0.8 0.624 0.608 0.346 SD Atmospheric Minimum Temperature (0C) 22.9 + 22.133 22.0 + 21.5 + S13 20.4 21.5 23.0 23.2 22.9 22.9 23.1 22.5 0.251 22.3 22.4 20.9 20.5 + 1.322 0.967 1.036 23.0 + 23.475 24.9 + 22.5 + S14 23.2 25.1 26.1 25.2 23.9 22.4 22.8 23.0 0.634 23.1 23.4 21.6 21.9 + 1.219 0.883 1.373 24.358 25.4 + 24.0 + 23.7 + S15 23.9 25.2 26.9 25.7 24.6 23.4 23.9 24.0 24.1 24.7 22.7 23.2 + 1.242 0.492 0.895 1.158 Monthly 25.33 + 22.5 + 23.93 + 24.7 + 23.8 + 22.9 + 23.27 + 23.17 + 23.17 + 23.5 + 21.73 + 21.87 + Mean+ 2.059 1.852 2.107 1.322 0.854 0.5 0.568 0.763 0.901 1.153 0.907 1.350 SD Total Rainfall (MMS) 223.291 178.9 + 311.0 + 180.0 + S13 12.2 42.6 265.8 395.1 279.4 463.4 187.8 313.4 412.2 287.5 19.5 0.6 + 183.176 114.612 202.828 167.778 222.25 58.2 + 537.0 + 71.6 + S14 1.0 0.0 41.9 189.7 477.9 974.5 340.8 354.7 139.0 131.7 9.1 6.7 + 89.846 298.120 73.650 286.323 73.7 + 590.7 + 84.2 + 249.533 S15 4.9 0.0 23.1 266.9 565.3 1131.6 389.9 276.1 286.2 49.8 0.0 0.6 129.166 379.698 136.706 + 146 335.385 Monthly 314.73 6.03 + 14.2 + 110.27 + 283.9 + 440.87 + 856.5 + 306.17 + 279.13 + 156.33 + 9.53 + 2.63 + Mean+ + 5.685 24.595 135.023 103.749 146.503 349.379 105.407 136.737 120.749 9.757 3.521 SD 39.317 R.H% at 0830hrs 86.083 84.3 + 91.8 + 82.3 + S13 80 79 88 90 92 96 91 88 88 85 83 73 + 5.560 3.304 6.5 6.416 75.8 + 89.0 + 78.8 + 81.166+ S14 75 74 76 78 88 92 89 87 86 83 72 74 1.707 2.160 6.8 7.056 75.5 + 92.8 + 74.0 + 80.75 + S15 76 72 75 79 91 97 92 91 87 76 65 68 2.886 2.872 9.831 10.48 Monthly 77.0 + 75.0 + 79.67 + 82.33+ 90.33 + 95.0 + 90.67 + 88.67 + 87.0 + 81.33 + 73.33 + 71.67 + Mean+ 2.645 3.605 7.234 6.658 2.081 2.645 1.527 2.081 1 4.725 9.073 3.214 SD R.H% at 1730hrs 66.8 + 80.0 + 68.8 + 71.833 + S13 55 57 75 80 84 84 76 76 76 75 71 53 12.606 4.618 10.719 10.844 62.0 + 79.3 + 65.5 + 68.916+ S14 56 57 65 70 77 86 77 77 76 73 58 55 6.683 4.5 10.535 10.413 66.5 + 86.8 + 71.3 + 74.833+ S15 64 63 67 72 83 94 86 84 82 74 63 66 4.041 4.991 8.539 10.615 Monthly 58.33 59.0 + 69.0 + 74.0 + 81.33 + 88.0 + 79.67 + 79.0 + 78.0 + 74.0 + 64.0 + 58.0 + Mean+ +4.932 3.464 5.291 5.291 3.785 5.291 5.507 4.358 3.464 1 6.557 7 SD 147 With respect to habitats of Avicennia officinalis, atmospheric maximum temperature showed a higher annual mean value at Thekkumbad 1 (32.517 ± 2.424 oC) followed by Kumbalam 1 (32.325 ± 1.354 oC) and Kadalundi 1 (31.792 ±2.185 oC). In the case of Bruguiera cylindrica, higher atmospheric maximum temperature was noticed at Ayiramthengu 1 (33.0 ±2.305 oC) followed by Thekkumbad 2 (32.5 ±2.424 oC) and Kadalundi 2 (31.8 ±2.185 oC). Atmospheric maximum temperature with respect to Excoecaria agallocha was higher at Ayiramthengu 2 (32.95 ±2.305 oC) followed by Thekkumbad 3 (32.517 ±2.424 oC) and Kumbalam 2 (32.333 ±1.343 oC). Among the habitats of Rhizophora mucronata, atmospheric maximum temperature showed higher annual mean value at Ayiramthengu 3 (32.95 ±2.305 oC) followed by Thekkumbad 4 (32.517 ±2.424 oC) and Kumbalam 3 (32.333 ±1.343 oC). In the case of Sonneratia alba, higher atmospheric temperature was noticed at Kadalundi 3 (32.95 ±2.305 oC) followed by Thekkumbad 5 (32.517 ±2.424 oC) and Kadalundi 4 (31.792 ±2.185 oC). As far the habitats of Avicennia officinalis is concerned, atmospheric minimum temperature was higher at Thekkumbad 1 (24.358 ± 1.159 oC) followed by Kumbalam 1 (23.492 ± 1.243 oC) and Kadalundi 1 (23.275 ±1.373 oC). In the case of Bruguiera cylindrica, higher atmospheric minimum temperature was noticed at Thekkumbad 2 (24.4 ±1.159 oC) followed by Kadalundi 2 (23.5 ±1.373 oC) and Ayiramthengu 1 (22.1 ±1.037 oC). Among the habitats of Excoecaria agallocha higher annual mean atmospheric minimum temperature was noticed at Thekkumbad 3 (24.358 ±1.159 oC) followed by Kumbalam 2 (23.425 ±1.235 oC) and Ayiramthengu 2 (22.133 ±1.037 oC). With respect to Rhizophora mucronata, higher value was noted at Thekkumbad 4 (24.358 ±1.159 oC) followed by Kumbalam 3 (23.425 ±1.235 oC) and Ayiramthengu 3 (22.133 ±1.037 oC). Among the habitats of Sonneratia alba, Thekkumbad 5 (24.358 ±1.159 oC) was noticed for higher value followed by Kadalundi 4 (23.475 ±1.373 oC) and Kadalundi 3 (22.133 ±1.037 oC). Among the habitats of Avicennia officinalis, higher mean total rainfall was noted at Thekkumbad 1 (249.533 ± 335.385 MMS) followed by Kumbalam 1 (227.942 ± 213.3 MMS) and Kadalundi 1 (222.25 ± 286.32 MMS). With respect to Bruguiera 148 cylindrica, higher total rainfall was noticed at Thekkumbad 2 (249.5 ± 335.385 MMS) followed by Ayiramthengu 1 (223.3 ± 167.78 MMS) and Kadalundi 2 (222.3 ± 286.32 MMS). In the case of Excoecaria agallocha, higher annual mean total rainfall was experienced at Thekkumbad 3 (249.533 ± 335.39 MMS) followed by Kumbalam 2 (223.508 ± 212.76 MMS) and Ayiramthengu 2 (223.292 ± 167.778 MMS). Among the habitats of Rhizophora mucronata, Thekkumbad 4 (249.533 ± 335.39 MMS) was noted for higher total rainfall followed by Kumbalam 3 (223.508 ± 212.76 MMS) and Ayiramthengu 3 (223.292 ± 167.778 MMS). With respect to Sonneratia alba, higher mean total rainfall was recorded at Thekkumbad 5 (249.533 ± 335.385 oC) followed by Kadalundi 3 (223.292 ± 167.778 oC) and Kadalundi 4 (222.25 ± 286.32 oC). Upon assessing the relative humidity (0830 hrs) along the habitats of Avicennia officinalis, higher annual average was noticed at Kumbalam 1 (82.417 ± 6.694 %) followed by Kadalundi 1 (81.167 ± 7.056 %) and Thekkumbad 1 (80.75 ± 10.481 %). With respect to Bruguiera cylindrica, highest value was noted at Ayiramthengu 1 (86.1 ± 6.417 %) followed by Kadalundi 2 (81.2 ± 7.056 %) and Thekkumbad 2 (80.8 ± 10.481 %). In the case of Excoecaria agallocha, higher mean value was noted at Ayiramthengu 2 with 86.083 ± 6.417 %, followed by 82.083 ± 6.317 % at Kumbalam 2 and lower of 80.75 ± 10.481 % at Thekkumbad 3. Among the habitats of Rhizophora mucronata, higher annual mean was recorded at Ayiramthengu 3 with 86.083 ± 6.417 %, followed by 82.083 ± 6.317 % at Kumbalam 3 and lower of 80.75 ± 10.481 % at Thekkumbad 4. With respect to Sonneratia alba, higher mean relative humidity was noticed at Kadalundi 3 (86.083 ± 6.417 %) followed by Kadalundi 4 (81.167 ± 7.056 %) and Thekkumbad 5 (80.75 ± 10.481 %). The relative humidity (1730 hrs) with respect to the habitats of Avicennia officinalis showed higher annual mean at Thekkumbad 1 (74.833 ± 10.616 %) followed by Kumbalam 1 (72.75 ± 9.127 %) and Kadalundi 1 (68.917 ± 10.414 %). With respect to Bruguiera cylindrica, highest value was noted at Thekkumbad 2 (74.8 ± 10.616 %) followed by Ayiramthengu 1 (71.8 ± 10.845 %) and Kadalundi 2 (68.9 ± 10.414 %). In the case of Excoecaria agallocha, higher relative humidity was noticed at 149 Thekkumbad 3 with 74.833 ± 10.6158 % followed by 72.417 ± 8.743 % at Kumbalam 2 and lower value of 71.833 ± 10.845 % at Ayiramthengu 2. Among the habitats of Rhizophora mucronata, higher annual mean relative humidity was recorded at Thekkumbad 4 with 74.833 ± 10.6158 % followed by 72.417 ± 8.743 % at Kumbalam 3 and lower value of 71.833 ± 10.845 % at Ayiramthengu 3. With respect to Sonneratia alba higher relative humidity was recorded at Thekkumbad 5 (74.833 ± 10.616 %) followed by Kadalundi 3 (71.833 ± 10.845 %) and Kadalundi 4 (68.917 ± 10.414 %). Upon compiling all the above results, it can be stated that, even though the mangroves are growing in a wider range of environmental conditions, each species has its own range of tolerance to different hydrogeochemical, sedimentological and climatological attributes along their natural habitats. In the present investigation, the range of environmental attributes influencing the growth of selected mangrove species has been categorized into tolerance range and augmented range. Tolerance range is the ideal range, at which a particular species can flourish well along their natural environmental settings and the augmented range is the range that is acquired by adapting to an uncertain environmental condition. The range of various environmental attributes influencing the growth of mangrove species under study are depicted in the Table 2.19. 150 Table 2.19. Range of environmental attributes influencing the growth of selected mangrove species Sl Parameters Avicennia officinalis Brugueira cylindrica Excoecaria agallocha Rhizophora mucronata Sonneratia alba No: Tolerance Augmented Tolerance Augmented Tolerance Augmented Augmented Tolerance Augmented Tolerance range range range range range range range range range range 1. Hydrological attributes 1. pH 6.84–7.61 3.86-8.16 7.12–7.75 6.23-8.6 6.75–7.39 5.06-8.31 6.98–7.38 3.9-7.93 7.013–7.988 6.02-8.57 2. Turbidity (NTU) 8.64– 7.41 0.7-29.9 4.67–20.66 1.7-44.4 5.677–9.54 1.5-26.9 7.41–21.336 0.6-60.3 12.2–15.6 2.2-53.9 10,733.33– 23,166.67– 10,433.3– 25,916.6– 3. TS (mg/l) 200-44,400 400-51400 200-45800 12050–27,109.09 400-56,000 400-49,400 25,444.44 26,555.56 23,500.0 28,836.36 4. TDS (ppt) 9.9–22.92 0.2-42.0 22.18–26.067 1-49.6 9.86–22.7 0.2-45.6 11.36–25.546 0.2-45.8 25.03–27.673 0.2-49.0 833.33– 683.33– 5. TSS (mg/l) 0-41,200 888.89–2,950.0 0-18,600 566.67–1600.0 0-6000 683.33–1,563.64 0-10,200 0-4800 5111.11 1,163.63 6. Acidity (mg/l) 22.55– 35.69 1.32-88.0 28.56–40.58 1.76-61.6 27.13–39.356 11-63.8 23.46–34.833 8.8-61.6 24.09–47.0 3.08-74.8 7. Alkalinity (mg/l) 132.08–164.44 50-340 160.417–270.0 80-1060 122.08–172.08 60-215 112.08–171.67 40-280 171.25–172.73 60-280 1,786.17– 3,130.0– 1736.91– 3,675.25– 8. Hardness (mg/l) 26-7,620 30-8180 22-7660 1,852.5–3,660.18 34-7,660 32-8760 3,490.75 3,282.17 3279.67 4,053.82 151.09– 9. Calcium (mg/l) 6.4-801 289.19–334.81 6.01-1121.4 130.83–273.32 6.41-680.85 144.12–280.782 7.21-504.63 280.28–301.80 9.62-520.65 308.963 Magnesium 343.02– 719.10– 10. 0.49-1582.5 558.54–712.16 0.49-1558.2 343.34–598.78 0.97-1524.09 363.41–720.47 1.95-1582.5 1.46-1830.9 (mg/l) 690.693 803.526 8,001.7– 11,833.93– 7669.78 – 7931.72– 15,460.25–16, 11. Chloride (mg/l) 255.6-40,186 426-25,560 227.2-26,128 411.8-25,205 383.4-41,322 15,257.9 13,144.68 13166.84 15,323.09 918.7 12. Sulphate (mg/l) 37.375–51.21 2.0-126 44.11–54.75 2-128 35.27–52.41 0.5-128 40.29–51.208 2-129 50.59–55.125 2-127 13. Sodium (ppt) 5.677–17.85 0.02-54.6 13.28–16.29 0.05-34.1 8.44–14.30 0.075-29.8 7.71–15.33 0.015-27.4 14.92–19.912 0.01-46.8 14. Nitrogen (mg/l) 56.42 – 68.33 20-196 48.58–61.33 15-210 63.33–69.75 22-220 56.41–75.273 19-220 56.0–98.917 14-490 Phosphorous 15. 22.0– 36.4 5.0-60.0 26–42.1 0.09-115 18.2–42.6 0.2-110 34–38.7 0.7-117.5 32.3–39.8 1.5-115 (mg/l) 910.42– 16. Potassium (mg/l) 0-27800 211.66–401.67 0-1800 120.0–387.08 0-1700 317.08–376.25 0-1800 292.72–350.83 0-1650 3,252.73 17. Salinity (ppt) 8.693–19.677 0.05-38.05 18.68–30.97 0.098-51.72 8.52–19.067 0.045-37.21 9.82–21.344 0.247-35.62 20.78–24.56 0.299-38.5 131.12– 18. Resistivity (Ω) 17.71-10790 84.72–898.89 16.48-5030 66.07–2317.91 18.06-12,270 75.04–499.886 18.83-1977 134.41–260.37 17.49-1634 2,017.66 19. Conductivity 13.77–29.37 0.091-55.23 28.49–31.081 0.194-59.33 13.65–29.025 0.0795-54.24 15.57–31.826 0.495-51.76 31.065–36.236 0.5996-55.87 2. Sedimentological attributes 20. pH 6.63–7.71 4.08-8.33 6.84–7.523 5.57-8.21 6.63–7.247 4.1-8.16 6.43–7.51 5.05-8.08 6.708–8.02 4.66-8.7 21. Moisture % 9.40–13.22 4.97-20.15 7.11–11.529 3.48-16.38 8.88–11.518 4.25-16.2 7.58–13.646 1.06-23.61 9.38–10.467 6.62-14.17 Organic carbon 22. 17.9–34.75 1.0-96 20.28–26.65 10-155 17.5–35.1 0.4-110.5 17.3–23.03 0.5-67 19.06–23.29 0.5-77 (g/kg) Total nitrogen 2,269.16– 816.66– 737.86– 23. 1050-18840 560-2870 788.06–1628.7 630.45-3572.55 788.067–1692.89 630.45-3362.4 112.08-1401.0 (mg/kg) 5,610.83 1545.83 834.763 Total 24. 9.7–23.1 7-38.5 11.4–58.0 12-82 15.4–43.1 8.2-69.6 21.3–57.5 11.5-76.2 29.8–41.5 13.2-66 phosphorous 151 (mg/kg) Potassium 25. 55.55–76.33 3.4-240 48.39–73.583 8.5-230 35.158–56.792 0.2-138 47.467–258.92 8.9-1,400 56.567–77.483 14.7-139 (mg/kg) 26. Sodium (ppt) 0.34–1.055 0.0775-1.884 0.34–0.677 0.0263-1.674 0.316–0.44 0.0441-1.355 0.28–0.55 0.0255-0.947 0.449–0.502 0.2815-1.052 27. Sand % 78.45–87.29 51.4-99 82.025–86.842 58.7-99 83.3–90.358 61.7-97.9 52.2–74.72 25.6-96.8 75.375–86.958 50.9-98.5 28. Silt % 0.26–0.475 0.1-1.2 0.333–0.433 0.1-1.8 0.38-0.983 0.1-6.7 0.233–0.433 0.1-2.2 0.433–0.592 0.1-2.7 29. Clay % 12.44–21.075 0.8-47.7 12.725–17.642 0.8-36.2 9.067–16.317 0.7-38.2 9.292–47.367 2.9-73.8 12.625–24.025 1.2-48.3 3. Climatological attributes Atm.Max.Temp 30. o 31.79–32.52 28-35.5 31.8–33.0 28-36.6 32.33–32.95 28-36.6 32.33–32.95 28-36.6 31.79–32.95 28-36.6 ( C) Atm.Min.Temp 31. o 23.275–24.36 21.6-26.9 22.1–24.4 20.4-26.9 22.133–24.358 20.4-26.9 22.13–24.258 20.4-26.9 22.13–24.358 20.4-26.9 ( C) Total rainfall 222.25– 223.29– 222.25– 32. 0-565.3 222.3–249.5 0-1131.6 0-1131.6 223.29–249.533 0-1131.6 0-565.3 (MMS) 249.533 249.533 249.533 R.H % at 0830 33. 80.75–82.42 65-93 80.8–86.1 65-97 80.75–86.083 65-97 80.75–86.083 65-97 80.75–86.083 65-97 hrs R.H % at 1730 68.917– 34. 68.92–74.833 55-94 68.9–74.8 53-94 71.833–74.833 53-94 71.833–74.833 53-94 53-94 hrs 714.833 152 Mangrove ecosystems are under the influence of both marine and freshwater influxes and have developed various physiological adaptations to overcome changes in environmental conditions (Tomlinson, 1986). In the present investigation, considering tolerance range to water pH, Avicennia officinalis can flourish in the range of 6.842 to 7.612, while it has got an augmented pH range of 3.86-8.16. The tolerance range of Bruguiera cylindrica and Excoecaria agallocha were 7.126 to 7.749 and 6.758 to 7.39 respectively whereas, their augmented tolerance range were 6.23 to 8.6 and 5.06 to 8.31 respectively. Hydrological pH range in the habitat of Rhizophora mucronata is 6.981 to 7.383 (augmented range; 3.9 to7.93) and that of Sonneratia alba is 7.014 to 7.988 (augmented range; 6.02 to 8.57). All the ranges are comparable with those reported in earlier studies. Paramasivam and Kannan, 2005, in their studies on the Muthupettai mangrove ecosystem, showed the range of hydrological pH in mangrove area as 7.1-8.7 and in 2012, Manju et al., studied the entire mangrove ecosystems of Kerala and reported the water pH as 7.1 – 8.05. Recently, in 2016, Shilna et al. reported the annual mean pH of water associated with five mangrove species in Malappuram district of Kerala to be 7.34. The ideal tolerance range of Avicennia officinalis to turbidity is 8.644 to 17.408 NTU (augmented range; 0.7 to 29.9 NTU), and that of Bruguiera cylindrica is 4.678 to 20.658 NTU (1.7 to 44.4 NTU). Tolerance range of 5.678 to 9.542 NTU and augmented range of 1.5 to 26.9 NTU for turbidity is noted for Excoecaria agallocha. Rhizophora mucronata can tolerate the water turbidity of 7.417 to 21.336 NTU while, Sonneratia alba can tolerate the turbidity level from 12.2 to 15.6 NTU. A higher range (43 to 260 NTU) has been reported by Srilatha et al. (2013) whereas, values of almost similar range (10.43 NTU) has been reported by Shilna et al. (2016). Tolerance range of Avicennia officinalis to total solids is 10733.33 to 25444.44 mg/l (augmented range; 200 to 44,400 mg/l) and that of Bruguiera cylindrica is 23166.67 to 26555.56 mg/l (augmented range; 400 to 51400 mg/l). 10433.3 to 23500 mg/l and 12050 to 27109.09 mg/l are the tolerance limits of Excoecaria agallocha and Rhizophora mucronata respectively. Sonneratia alba are with a tolerance range of 25916.6 to 28836.36 mg/l and an augmented range of 400 to 49,400 mg/l. The values are comparable with some of the earlier reports in which 153 the annual average of water turbidity level reported was 47200 mg/l (Alshawafi et al., 2016). Avicennia officinalis possesses a tolerance range of 9.9 to 22.916 ppt of TDS and 833.33 to 5111.11 mg/l of TSS respectively, and their augmented ranges are 0.2 to 42.0 ppt and 0 to 41,200 mg/l. Likewise, Bruguiera cylindrica has a tolerance range of 22.183 to 26.067 ppt and 888.89 to 2950 mg/l respectively. Excoecaria agallocha is with a range of tolerance 9.867 to 22.7 ppt and 566.67 to 1600 mg/l respectively towards TDS and TSS. 11.367 to 25.546 ppt and 683.33 to 1563.64 mg/l are the tolerance range of Rhizophora mucronata towards TDS and TSS. Sonneratia alba have a tolerance range of 25.033 to 27.673 ppt of TDS (augmented range; 0.2 to 49.0 ppt) and 683.33 to 1163.63 mg/l TSS (augmented range; 0 to 4800 mg/l). TDS values of similar range have also been reported by other researchers (Alshawafi et al., 2016 and Shilna et al., 2016). The ranges of tolerance of acidity for Avicennia officinalis, Brugueira cylindrica, Excoecaria agallocha, Rhizophora mucronata and Sonneratia alba are 22.55 to 35.69 mg/l, 28.563 to 40.578 mg/l, 27.133 to 39.356 mg/l, 23.467 to 34.833 mg/l and 24.09 to 47 mg/l respectively and that of alkalinity are 132.08 to 164.44 mg/l, 160.417 to 270.0 mg/l, 122.083 to 172.083 mg/l, 112.083 to 171.667 mg/l and 171.25 to 172.727 mg/l respectively. The augmented ranges of acidity and alkalinity for the species are (1.32 to 88.0, 1.76 to 61.6, 11 to 63.8, 8.8 to 61.6 and 3.08 to 74.8 mg/l) and (50 to 340, 80 to 1060, 60 to 215, 40-280 and 60 to 280) respectively. In 2016, Shilna et al., reported the annual range of acidity and alkalinity of the mangrove area with all the selected mangrove species as 8.24 mg/l and 100.79 mg/l respectively and in 2012, Manju et al., reported the annual alkalinity of 77.91 mg/l from the mangrove ecosystems of Kerala. The tolerance range of Avicennia officinalis towards hardness is 1,786.17 to 3,490.75 mg/l and that of Brugueira cylindrica is 3130 to 3282.17 mg/l. 1736.917 to 3279.667 mg/l and 1852.5 to 3660.182 mg/l are the tolerance ranges of Excoecaria agallocha and Rhizophora mucronata towards hardness and that of Sonneratia alba is 3675.25 to 4053.82 mg/l. Avicennia officinalis has also a tolerance range of 154 151.09 to 308.963 mg/l and 343.026 to 690.693 mg/l towards calcium and magnesium. Brugueira cylindrica possesses the tolerance range within 289.195 to 334.806 mg/l to calcium and 558.543 to 712.159 mg/l to magnesium. The tolerance range of Excoecaria agallocha to calcium and magnesium are 130.838 to 273.321 mg/l and 343.348 to 598.789 mg/l respectively. Rhizophora mucronata can tolerate calcium and magnesium within the range of 144.121 to 280.782 mg/l and 363.414 to 720.47 mg/l respectively. The tolerance range of Sonneratia alba towards calcium and magnesium are 280.283 to 301.797 and 719.101 to 803.526 mg/l. According to Shilna et al. (2016), the annual average of calcium and magnesium from the mangrove area are 429.63 mg/l and 850.33 mg/l, and that of entire Kerala mangrove ecosystem was 127.61 mg/l and 473.13 mg/l respectively (Manju et al., 2012). Avicennia officinalis, Brugueira cylindrica, Excoecaria agallocha, Rhizophora mucronata and Sonneratia alba have the tolerance range of 8001.7 to 15257.9 mg/l, 11833.93 to 13144.68 mg/l, 7669.78 to 13166.84 mg/l, 7931.72 to 15323.09 mg/l and 15460.25 to 16918.7 mg/l respectively towards chloride. The range of tolerances towards sulphate and sodium by the species are 37.375 to 51.208 mg/l and 5.677 to 17.849 ppt, 44.111 to 54.75 mg/l and 13.288 to 16.289 ppt, 35.27 to 52.42 mg/l and 8.447 to 14.303 ppt, 40.292 to 51.208 mg/l and 7.718 to 15.33 ppt and 50.591 to 55.125 mg/l and 14.924 to 19.912 ppt respectively. The augmented ranges of Avicennia officinalis, Brugueira cylindrica, Excoecaria agallocha, Rhizophora mucronata and Sonneratia alba towards sulphate are 2.0 to 126, 2 to 128, 0.5 to 128, 2 to 129 and 2 to 127 mg/l respectively. In 2012, Manju et al., reported the annual average of sulphate and sodium from mangrove ecosystems of Kerala as 1308.03 mg/l and 2525 mg/l respectively. Shilna et al. (2016) has also reported the annual average of chloride, sulphate and sodium from the mangrove ecosystem of all the species under study along Malappuram district of Kerala as 11199.33 mg/l, 874.05 mg/l and 8640.33 mg/l respectively. The tolerance and augmentation ranges of Avicennia officinalis towards nitrogen, phosphorous and potassium are 56.417 to 68.333 (20 to 196) mg/l, 22.0 to 36.4 (0.5 to 60) mg/l and 910.42 to 3252.73 (0 to 27800) mg/l respectively and that of 155 Brugueira cylindrica are 48.583 to 61.333 (15 to 210) mg/l, 26.4 to 42.1 (0.09 to 115) mg/l and 211.667 to 401.667 (0 to 1800) mg/l respectively. Excoecaria agallocha and Rhizophora mucronata have range of tolerance towards N, P, K as (63.33 to 69.75 mg/l, 18.2 to 42.6 mg/l and 120.0 to 387.08 mg/l) and (56.417 to 75.273 mg/l, 34.8 to 38.7 mg/l and 317.083 to 376.25 mg/l) respectively. Sonneratia alba has tolerance and augmented range towards N, P and K as 56 to 98.917 (14 to 490) mg/l, 32.4 to 39.8 (1.5 to 115) mg/l and 292.73 to 350.83 (0 to 1650) mg/l respectively. Nitrogen, Phosphorous and Potassium are the major nutrients in the mangrove sediments studied and reported from various natural mangrove habitats of Kerala and the annual average values reported were 88.35 μM, 9.61 μM and 105.38 mg/l respectively (Manju et al., 2012). Avicennia officinalis has a wider range of tolerance to salinity (8.693 to 19.677 ppt), resistivity (131.123 to 2017.66 Ω) and conductivity (13.77 to 29.37 mS). The augmented ranges were 0.05 to 38.05 ppt, 17.71 to 10790 Ω and 0.091 to 55.23 mS respectively. The range of tolerance of Brugueira cylindrica, Excoecaria agallocha, Rhizophora mucronata and Sonneratia alba towards salinity, resistivity and conductivity are (18.689 to 30.967 ppt, 84.723 to 898.886 Ω and 28.496 to 31.081 mS), (8.529 to 19.067 ppt, 66.07 to 2314.91 Ω and 13.659 to 29.025 mS), (9.82 to 21.34 ppt, 75.048 to 499.886 Ω and 15.570 to 31.826 mS) and (20.789 to 24.562 ppt, 134.413 to 260.368 Ω and 31.065 to 36.236 mS) respectively. Salinity plays a pivotal role in the species distribution, productivity and growth of mangrove forests (Twilley and Chen, 1998). The annual average of salinity reported from the mangrove ecosystems of Kerala was 16.09 ppt (Manju et al., 2012). Studies have also been reported that mangrove ecosystems with mangrove species Avicennia officinalis, Brugueira cylindrica, Excoecaria agallocha, Rhizophora mucronata and Sonneratia alba has an annual average values of salinity, resistivity and conductivity as 15.803.67 ppt, 1591.67 Ω and 23.684 m S respectively (Shilna et al., 2016). 156 Mangrove plants may grow in different types of soils; therefore their vegetation, species composition and structure may vary considerably at the global, regional and local scales (Vilarrubia, 2000). Upon compiling the sedimentological requirements, the range of tolerance to sediment pH by Avicennia officinalis, Bruguiera cylindrica, Excoecaria agallocha, Rhizophora mucronata and Sonneratia alba were 6.633 to 7.713, 6.848 to7.523, 6.638 to 7.247, 6.43 to 7.51 and 6.708 to 8.023 respectively. Tolerance range to moisture percentage and organic carbon concentration of the species (9.407 to 13.221, 7.117 to 11.529, 8.888 to 11.518, 7.584 to 13.646 and 9.382 to 10.467%), (1.793 to 3.475, 2.028 to 2.665, 1.75 to 3.511, 1.733 to 2.303 and 1.906 to 2.329 g/kg) are reported respectively. The augmented ranges of organic carbon concentration of the species are 1.0 to 96, 10 to 155, 0.4 to 110.5, 0.5 to 67 and 0.5 to 77 g/kg respectively. Saravanakumar et al. (2008) reported the range of organic carbon from the mangrove ecosystem of Kachchh - Gujarat as 2.9 to 25.6 g/kg. The distribution of total organic carbon closely followed the distribution of sediment type i.e., as sediment is low in clay content, the total organic carbon content is also low and as the clay content increased, the total organic carbon content also increased (Reddy and Hariharan, 1986). Various studies have also reported that, soil organic carbon and pH are the major factors having most significant influence on the growth and establishment of mangroves (Clough, l984 and Yang et al., 2013). The tolerance and augmented range of Avicennia officinalis to sediment Nitrogen, Phosphorous and Potassium is 2269.16 to 5610.83 (1050 to 18840) mg/kg, 9.7 to 23.1 (7 to 38.5) mg/kg and 55.558 to 76.333 (3.4 to 240) mg /kg respectively and that of Bruguiera cylindrica is 816.667 to 1545.83 (560 to 2870) mg/kg, 11.5 to 58.0 (12 to 82) mg/kg and 48.392 to 73.583 (8.5 to 230) mg/kg respectively. The range of tolerance of Excoecaria agallocha and Rhizophora mucronata are (788.063 to 1628.7, 15.4 to 43.1 and 35.158 to 56.792 mg/kg) and (788.067 to 1692. 89, 21.3 to 57.5 and 47.467 to 258.917 mg/kg) respectively. The augmented ranges are (630.45 to 3572.55, 8.2 to 69.6 and 0.2 to 138) and (630.45 to 3362.4, 11.5 to 76.2 and 8.9 to 1400) respectively. Sonneratia alba has a tolerance range of 737.86 to 834.763, 29.8 to 41.5 and 56.567 to 77.483 mg/kg respectively towards Nitrogen, Phosphorous and Potassium. A recent study carried out in the mangrove ecosystem of Ayiramthengu, 157 Kerala possessing all the 5 mangrove species reported range of P and K as 29.5 to 57.9 Kg/ha and 231 to 440 Kg/ha respectively. Study conducted in the mangrove areas of Karankadu mangrove forest, Tamil nadu, showed a range of N, P and K as 78320 to 102500 mg/kg, 2500 to 3480 mg/kg and 79000 to 92000 mg/kg (Saseeswari et al., 2015). Avicennia officinalis has a tolerance range of 0.342 to 1.055 ppt towards sediment sodium, and that of 78.45 to 87.29%, 0.267 to 0.475 % and 12.442 to 21.075 % towards sand %, silt % and clay % respectively. Bruguiera cylindrica shows a tolerance range of 0.342 to 0.677 ppt towards sodium and 82.025 to 86.842, 0.333 to 0.433 and 12.725 to 17.642 % respectively towards sand, silt and clay percentages. The tolerance range of Excoecaria agallocha towards sodium is 0.316 to 0.441 ppt and that of sand, silt and clay percentages are 83.3 to 90.358, 0.383 to 0.983 and 9.067 to 16.317 % respectively. The tolerance range of Rhizophora mucronata towards sodium is 0.287 to 0.552 ppt and that of sand, silt and clay percentages are 52.2 to 74.717, 0.233 to 0.433 and 9.292 to 47.367 % respectively. Sonneratia alba has a tolerance range of 0.449 to 0.502 ppt towards sodium and 75.375 to 86.958, 0.433 to 0.592, and 12.625 to 24.025% respectively towards sand, silt and clay percentages. More or less similar results have been reported by Saravanakumar et al. (2008). The study reported sediment textures ranges in terms of % of sand, clay and silt as 0.26-19.2, 7.6-47 and 47-87.4 % respectively. The texture triangles studies have revealed that the nature of soil in all the locations studied were silty loam, silty clay and silty clay loam. From the climatological observations, it can clearly be stated that the mangrove species has its own range of tolerance to different climatic attributes also. The tolerance range of atmospheric temperature maximum and minimum of the selected species include; Avicennia officinalis (31.792 to 32.517 and 23.275 to 24.358 oC), Brugueira cylindrica (31.8 to 33.0 and 22.1 to 24.4oC), Excoecaria agallocha (32.333 to 32.95 and 22.133 to 24.358oC), Rhizophora mucronata (32.333 to 32.95 and 22.133 to 24.358oC) and Sonneratia alba (31.792 to 32.95 and 22.133 to 24.358oC). 158 The tolerance and augmented ranges of total rainfall at which the mangrove species are proliferated well in the study areas are Avicennia officinalis (222.25 to 249.533 and 0 to 565.3 MMS), Bruguiera cylindrica (222.3 to 249.5 and 0 to 1131.6 MMS), Excoecaria agallocha (223.29 to 249.533 and 0 to 1131.6 MMS), Rhizophora mucronata (223.292 to 249.533 and 0 to 1131.6 MMS) and Sonneratia alba (222.25 to 249.533 and 0 to 565.3 MMS). The relative humidity percentage at 0830 hrs and 1730 hrs of Avicennia officinalis (80.75 to 82.417 and 68.917 to 74.833 %); Bruguiera cylindrica (80.8 to 86.1 % and 68.9 to 74.8 %), Excoecaria agallocha (80.75 to 86.083 and 71.833 to 74.833 %), Rhizophora mucronata (80.75 to 86.083 and 71.833 to 74.833 %) and Sonneratia alba (80.75 to 86.083 and 68.917 to 74.833 %) are reported. In general, mangroves are inimitable intertidal ecosystems with unique features, having own adaptations to cope up with extreme environmental conditions. Present study mainly focused on the range of tolerance of selected mangrove species to varying levels of environmental attributes. The results clearly indicated that, in addition to the ideal range of tolerance, each mangrove species acquire an additional capability to acclimatize with disturbed surroundings through its adaptation potentialities. This added range in addition to the tolerance range is depicted in the present investigation as ‘augmented range’. The present investigation along with the earlier success stories recommended following at least two major criteria in the subsequent afforestation endeavors; (i) species specific afforestation and (ii) site specific afforestation. Both of them are inter-dependable, because in species specific afforestation, the site selection depends on the tolerance range of the specific species and in the site specific afforestation activities, species selection is based on the characteristics of the site. In other words, the ‘tolerance range’ of a species with respect to the site is a mandatory requirement towards including them in afforestation purposes whereas the ‘augmented range’ gains significance only after the acclimatization of the species in the new area. Thus the study emphasizes that all 159 the afforestation/ restoration practices of mangroves must be either species or site specific. STATISTICAL ANALYSIS Physico chemical attributes of both water and sediment along selected habitats of 5 mangrove species were further analyzed statistically to find out the discrepancy among different sites and seasons. Seasonal and site specific mean values of each parameters were subjected to two way ANOVA and found out the variations among the locations as well as the seasons. Such variations in each parameter with respect to sites and seasons were considered towards elucidating each of their influence on the growth of mangrove species. Accordingly, the most vital physico chemical attributes of water and sediment that are likely to influence the growth of each mangrove species can be enumerated. Since a uniform pattern of climatological conditions has been experienced along all the locations under study, statistical analysis for elucidating each of their influence on mangrove growth was not attempted. The observations are depicted in the following tables (Table 2.20 – 2.24). Table 2.20. Comparative study of locations and seasons of Avicennia officinalis with respect to water and sediment quality Sl No Source of Variation Average F- value WATER ANALYSIS pH 1 Kumbalam 1 6.891667 2 Kadalundi 1 NS7.512333 1.119 3 Thekkumbad 1 6.892667 1 Pre monsoon 7.432333 2 Monsoon 2.610 NS6.467667 3 Post monsoon 7.396667 Turbidity 1 Kumbalam 1 8.866667 2 Kadalundi 1 17.40833 8.034 * 3 Thekkumbad 1 7.975 1 Pre monsoon 7.8 2 Monsoon *17.68333 8.793 3 Post monsoon 8.766667 Total solids 1 Kumbalam 1 10733.33 3.899 NS 160 2 Kadalundi 1 23900 3 Thekkumbad 1 26200 1 Pre monsoon 34816.67 2 Monsoon 1783.333 15.928* 3 Post monsoon 24233.33 Total Dissolved solids 1 Kumbalam 1 9.9 2 Kadalundi 1 22.91667 4.140 NS 3 Thekkumbad 1 22.22233 1 Pre monsoon 33.55 2 Monsoon 1.389 20.141* 3 Post monsoon 20.1 TSS 1 Kumbalam 1 833.333 2 Kadalundi 1 966.667 0.755 NS 3 Thekkumbad 1 3977.777 1 Pre monsoon 1266.667 2 Monsoon 377.777 0.919 NS 3 Post monsoon 4133.333 Salinity (ppt) 1 Kumbalam 1 8.693 2 Kadalundi 1 19.677 4.091 NS 3 Thekkumbad 1 20.578 1 Pre monsoon 28.469 2 Monsoon 1.2643 17.874* 3 Post monsoon 19.215 Resistivity (Ω) 1 Kumbalam 1 503.601 2 Kadalundi 1 131.123 0.972 NS 3 Thekkumbad 1 2016.519 1 Pre monsoon 30.769 2 Monsoon 2558.422 2.051 NS 3 Post monsoon 62.053 Conductivity (mS) 1 Kumbalam 1 13.77017 2 Kadalundi 1 29.36967 4.044 NS 3 Thekkumbad 1 30.15957 1 Pre monsoon 42.02033 2 Monsoon 2.078067 19.686* 3 Post monsoon 29.201 Acidity 1 Kumbalam 1 22.55 2 Kadalundi 1 27.97667 3 Thekkumbad 1 36.54333 7.944 * 1 Pre monsoon 38.68333 2 Monsoon 19.31 3 Post monsoon 29.07667 14.976* Alkalinity 1 Kumbalam 1 132.0833 1.228 NS 161 2 Kadalundi 1 160.8333 3 Thekkumbad 1 168.611 1 Pre monsoon 185 2 Monsoon 126.9443 2.841 NS 3 Post monsoon 149.5833 Hardness 1 Kumbalam 1 1786.167 2 Kadalundi 1 3490.75 2.338 NS 3 Thekkumbad 1 3468.667 1 Pre monsoon 5891.667 2 Monsoon 185.75 20.018* 3 Post monsoon 2668.167 Calcium 1 Kumbalam 1 151.0943 2 Kadalundi 1 261.2127 2.457 NS 3 Thekkumbad 1 314.7373 1 Pre monsoon 417.1883 2 Monsoon 26.91933 13.875* 3 Post monsoon 282.9367 Magnesium 1 Kumbalam 1 343.026 2 Kadalundi 1 690.693 2.032 NS 3 Thekkumbad 1 653.190 1 Pre monsoon 1180.392 2 Monsoon 28.873 18.798* 3 Post monsoon 477.644 Chloride (Mg/l) 1 Kumbalam 1 8001.7 2 Kadalundi 1 15257.9 2.919 NS 3 Thekkumbad 1 15368.74 1 Pre monsoon 22317.67 2 Monsoon 1526.106 18.146* 3 Post monsoon 14784.57 Sulphate (Mg/l) 1 Kumbalam 1 8001.7 2 Kadalundi 1 15257.9 2.919 NS 3 Thekkumbad 1 15368.74 1 Pre monsoon 22317.67 2 Monsoon 1526.106 18.146* 3 Post monsoon 14784.57 Sodium (ppt) 1 Kumbalam 1 5.677 2 Kadalundi 1 13.935 3.014 NS 3 Thekkumbad 1 17.927 1 Pre monsoon 20.438 7.620* 2 Monsoon 1.368 3 Post monsoon 15.733 Nitrogen (mg/l) 1 Kumbalam 1 59.167 0.244 NS 162 2 Kadalundi 1 56.417 3 Thekkumbad 1 66.111 1 Pre monsoon 46.083 2 Monsoon 48.861 5.052 NS 3 Post monsoon 86.75 Phosphorous (mg/l) 1 Kumbalam 1 22.067 2 Kadalundi 1 22.1 0.642 NS 3 Thekkumbad 1 47.367 1 Pre monsoon 51.267 2 Monsoon 25.367 1.056 NS 3 Post monsoon 14.9 Potassium (mg/l) 1 Kumbalam 1 910.417 2 Kadalundi 1 3105.417 1.806 NS 3 Thekkumbad 1 2987.361 1 Pre monsoon 4847.5 2 Monsoon 665.277 5.813 NS 3 Post monsoon 1490.417 SEDIMENT ANALYSIS pH 1 Kumbalam 1 6.579333 2 Kadalundi 1 7.561 2.002 NS 3 Thekkumbad 1 6.6785 1 Pre monsoon 7.403333 2 Monsoon 6.639167 1.138 NS 3 Post monsoon 6.776333 Moisture % 1 Kumbalam 1 13.22333 2 Kadalundi 1 9.408333 3.268 NS 3 Thekkumbad 1 12.19833 1 Pre monsoon 10.97 2 Monsoon 13.29 1.808 NS 3 Post monsoon 10.57 Sand % 1 Kumbalam 1 78.45 2 Kadalundi 1 83.783 2.690 NS 3 Thekkumbad 1 87.292 1 Pre monsoon 85.333 2 Monsoon 75.20 6.928 NS 3 Post monsoon 88.992 Silt% 1 Kumbalam 1 0.475 2 Kadalundi 1 0.408 0.356 NS 3 Thekkumbad 1 0.267 1 Pre monsoon 0.233 2 Monsoon 0.525 0.670 NS 3 Post monsoon 0.392 Clay % 163 1 Kumbalam 1 23.433 2 Kadalundi 1 22.642 1.977 NS 3 Thekkumbad 1 16.908 1 Pre monsoon 14.433 2 Monsoon 24.275 5.035 NS 3 Post monsoon 24.275 Organic carbon(g/kg) 1 Kumbalam 1 33.41667 2 Kadalundi 1 20.30267 0.593 NS 3 Thekkumbad 1 24.60567 1 Pre monsoon 25.10833 2 Monsoon 31.91667 0.384 NS 3 Post monsoon 21.3 Nitrogen(mg/kg) 1 Kumbalam 1 5610.833 2 Kadalundi 1 4907.5 3 Thekkumbad 1 2269.167 2.261 NS 1 Pre monsoon 4436.667 2 Monsoon 5573.333 3 Post monsoon 2777.5 1.440 NS Phosphorous(mg/kg) 1 Kumbalam 1 19.433 2 Kadalundi 1 9.7 3 Thekkumbad 1 23.133 12.893* 1 Pre monsoon 17.433 2 Monsoon 19.733 3 Post monsoon 15.1 1.437 NS Potassium(mg/kg) 1 Kumbalam 1 55.558 2 Kadalundi 1 76.333 0.479 NS 3 Thekkumbad 1 60.45 1 Pre monsoon 85.917 2 Monsoon 48.792 1.526 NS 3 Post monsoon 57.633 Sodium (ppt) 1 Kumbalam 1 0.342 2 Kadalundi 1 0.430 1.686 NS 3 Thekkumbad 1 1.055 1 Pre monsoon 0.666 2 Monsoon 0.221 1.466 NS 3 Post monsoon 0.940 *: Significant at 5% level; NS: not significant (critical value of F at 5% level for 3 locations x 3 seasons = 6.944). 164 Table 2.21. Comparative study of locations and seasons of Bruguiera cylindrica with respect to water and sediment quality Sl No Source of Variation Average F- value WATER ANALYSIS pH 1 Ayiramthengu 1 7.470 2 Kadalundi 2 7.749 9.762* 3 Thekkumbad 2 7.130 1 Pre monsoon 7.708 2 Monsoon 6.971 17.508* 3 Post monsoon 7.671 Turbidity 1 Ayiramthengu 1 6.983 2 Kadalundi 2 20.658 82.892* 3 Thekkumbad 2 4.322 1 Pre monsoon 9.042 2 Monsoon 10.222 3.761 NS 3 Post monsoon 12.700 Total solids 1 Ayiramthengu 1 23166.67 2 Kadalundi 2 25933.33 0.563 NS 3 Thekkumbad 2 27650.00 1 Pre monsoon 41800.00 2 Monsoon 4066.667 41.447* 3 Post monsoon 30883.33 Total Dissolved solids 1 Ayiramthengu 1 22.183 2 Kadalundi 2 22.983 1.136 NS 3 Thekkumbad 2 27.306 1 Pre monsoon 38.800 2 Monsoon 3.822 49.409* 3 Post monsoon 29.850 TSS 1 Ayiramthengu 1 983.333 2 Kadalundi 2 2950.00 0.742 NS 3 Thekkumbad 2 744.443 1 Pre monsoon 3000.00 2 Monsoon 644.443 0.807 NS 3 Post monsoon 1033.333 Salinity (ppt) 1 Ayiramthengu 1 18.689 2 Kadalundi 2 30.967 3.852 NS 3 Thekkumbad 2 22.045 1 Pre monsoon 38.824 2 Monsoon 4.022 30.726* 3 Post monsoon 28.855 Resistivity (Ω) 165 1 Ayiramthengu 1 84.723 2 Kadalundi 2 86.831 1.124 NS 3 Thekkumbad 2 886.721 1 Pre monsoon 20.508 2 Monsoon 974.339 1.526 NS 3 Post monsoon 63.429 Conductivity (mS) 1 Ayiramthengu 1 28.497 2 Kadalundi 2 31.081 0.333 NS 3 Thekkumbad 2 32.156 1 Pre monsoon 49.076 2 Monsoon 5.420 47.926* 3 Post monsoon 37.238 Acidity 1 Ayiramthengu 1 29.33333 2 Kadalundi 2 28.56333 3 Thekkumbad 2 42.53333 4.882* 1 Pre monsoon 40.33333 2 Monsoon 24.93333 3 Post monsoon 35.16333 4.863* Alkalinity 1 Ayiramthengu 1 160.4167 2 Kadalundi 2 161.9167 1.198 NS 3 Thekkumbad 2 268.3333 1 Pre monsoon 168.3333 2 Monsoon 249.1667 0.643 NS 3 Post monsoon 173.1667 Hardness 1 Ayiramthengu 1 3282.167 2 Kadalundi 2 3135.667 0.161 NS 3 Thekkumbad 2 3490.278 1 Pre monsoon 6605.00 2 Monsoon 425.444 48.949* 3 Post monsoon 2877.667 Calcium 1 Ayiramthengu 1 289.195 2 Kadalundi 2 289.214 0.273 NS 3 Thekkumbad 2 337.224 1 Pre monsoon 488.602 2 Monsoon 59.106 17.446* 3 Post monsoon 367.925 Magnesium 1 Ayiramthengu 1 623.312 2 Kadalundi 2 712.155 0.758 NS 3 Thekkumbad 2 644.789 1 Pre monsoon 1311.073 2 Monsoon 67.674 137.250* 3 Post monsoon 601.509 166 Chloride (Mg/l) 1 Ayiramthengu 1 12266.43 2 Kadalundi 2 14068.85 0.448 NS 3 Thekkumbad 2 14069.04 1 Pre monsoon 22627.31 2 Monsoon 2709.636 41.776* 3 Post monsoon 15067.38 Sulphate (Mg/l) 1 Ayiramthengu 1 51.167 2 Kadalundi 2 54.750 0.458 NS 3 Thekkumbad 2 48.472 1 Pre monsoon 85.667 2 Monsoon 18.264 52.520* 3 Post monsoon 50.458 Sodium (ppt) 1 Ayiramthengu 1 13.288 1.198 NS 2 Kadalundi 2 15.523 3 Thekkumbad 2 17.034 1 Pre monsoon 24.867 2 Monsoon 2.052 47.262* 3 Post monsoon 18.926 Nitrogen (mg/l) 1 Ayiramthengu 1 61.333 2 Kadalundi 2 48.583 2.862 NS 3 Thekkumbad 2 53.917 1 Pre monsoon 43.417 2 Monsoon 29.750 71.304* 3 Post monsoon 90.667 Phosphorous (mg/l) 1 Ayiramthengu 1 26.410 2 Kadalundi 2 42.093 0.246 NS 3 Thekkumbad 2 46.527 1 Pre monsoon 62.533 2 Monsoon 42.987 1.583 NS 3 Post monsoon 9.510 Potassium (mg/l) 1 Ayiramthengu 1 312.083 2 Kadalundi 2 401.667 0.670 NS 3 Thekkumbad 2 230.833 1 Pre monsoon 320.833 2 Monsoon 299.167 0.017 NS 3 Post monsoon 324.583 SEDIMENT ANALYSIS pH 1 Ayiramthengu 1 6.849 2 Kadalundi 2 7.523 4.243 NS 3 Thekkumbad 2 6.849 1 Pre monsoon 7.091 3.652 NS 2 Monsoon 6.704 167 3 Post monsoon 7.425 Moisture % 1 Ayiramthengu 1 7.117 2 Kadalundi 2 9.850 7.290* 3 Thekkumbad 2 11.530 1 Pre monsoon 8.716 2 Monsoon 11.219 3.270 NS 3 Post monsoon 8.562 Sand % 1 Ayiramthengu 1 86.075 2 Kadalundi 2 82.025 0.511 NS 3 Thekkumbad 2 86.84167 1 Pre monsoon 82.65 2 Monsoon 84.36667 0.553 NS 3 Post monsoon 87.925 Silt% 1 Ayiramthengu 1 0.408 2 Kadalundi 2 0.333 0.867 NS 3 Thekkumbad 2 0.433 1 Pre monsoon 0.208 2 Monsoon 0.658 17.867* 3 Post monsoon 0.308 Clay % 1 Ayiramthengu 1 13.517 2 Kadalundi 2 17.642 0.536 NS 3 Thekkumbad 2 12.725 1 Pre monsoon 17.142 2 Monsoon 14.975 0.562 NS 3 Post monsoon 11.7667 Organic carbon(g/kg) 1 Ayiramthengu 1 21.833 2 Kadalundi 2 20.283 0.107 NS 3 Thekkumbad 2 26.650 1 Pre monsoon 31.150 2 Monsoon 14.667 0.661 NS 3 Post monsoon 22.950 Nitrogen(mg/kg) 1 Ayiramthengu 1 816.667 2 Kadalundi 2 1545.833 16.894* 3 Thekkumbad 2 1499.167 1 Pre monsoon 1341.667 2 Monsoon 1417.500 2.741 NS 3 Post monsoon 1102.500 Phosphorous(mg/kg) 1 Ayiramthengu 1 11.50 2 Kadalundi 2 58.033 28.344* 3 Thekkumbad 2 24.333 1 Pre monsoon 36.10 1.928 NS 2 Monsoon 33.567 168 3 Post monsoon 24.20 Potassium(mg/kg) 1 Ayiramthengu 1 48.392 2 Kadalundi 2 NS73.583 1.130 3 Thekkumbad 2 69.233 1 Pre monsoon 89.083 2 Monsoon NS38.442 3.994 3 Post monsoon 63.683 Sodium (ppt) 1 Ayiramthengu 1 0.343 2 Kadalundi 2 0.490 3.397 NS 3 Thekkumbad 2 0.677 1 Pre monsoon 0.736 2 Monsoon 0.182 10.011* 3 Post monsoon 0.591 *: Significant at 5% level; NS: not significant (critical value of F at 5% level for 3 locations x 3 seasons = 6.944). Table 2.22. Comparative study of locations and seasons of Excoecaria agallocha with respect to water and sediment quality Sl No Source of Variation Average F- value WATER ANALYSIS pH 1 Ayiramthengu 2 7.389 2 Kumbalam 2 6.910 2.436NS 3 Thekkumbad 3 6.759 1 Pre monsoon 7.272 2 Monsoon 6.463 5.238 NS 3 Post monsoon 7.324 Turbidity 1 Ayiramthengu 2 7.817 2 Kumbalam 2 9.542 1.110 NS 3 Thekkumbad 3 5.067 1 Pre monsoon 4.250 2 Monsoon 6.942 2.704 NS 3 Post monsoon 11.233 Total solids 1 Ayiramthengu 2 23500 2 Kumbalam 2 10433.33 3.789 NS 3 Thekkumbad 3 24577.78 1 Pre monsoon 33333.33 2 Monsoon 2177.777 15.390* 3 Post monsoon 23000.0 169 Total Dissolved solids 1 Ayiramthengu 2 22.7 2 Kumbalam 2 9.867 4.121 NS 3 Thekkumbad 3 22.823 1 Pre monsoon 31.467 2 Monsoon 1.989 16.822* 3 Post monsoon 21.933 TSS 1 Ayiramthengu 2 800.00 2 Kumbalam 2 566.667 2.080 NS 3 Thekkumbad 3 1755.556 1 Pre monsoon 1866.667 2 Monsoon 188.889 3.691 NS 3 Post monsoon 1066.667 Salinity (ppt) 1 Ayiramthengu 2 19.068 2 Kumbalam 2 8.529 3.643 NS 3 Thekkumbad 3 20.110 1 Pre monsoon 27.339 2 Monsoon 1.786 14.967* 3 Post monsoon 18.581 Resistivity (Ω) 1 Ayiramthengu 2 66.07 2 Kumbalam 2 284.721 1.083 NS 3 Thekkumbad 3 2292.247 1 Pre monsoon 29.230 2 Monsoon 2483.248 1.387 NS 3 Post monsoon 130.559 Conductivity (mS) 1 Ayiramthengu 2 29.025 2 Kumbalam 2 13.659 3.690 NS 3 Thekkumbad 3 29.595 1 Pre monsoon 40.823 2 Monsoon 3.148 16.621* 3 Post monsoon 28.309 Acidity 1 Ayiramthengu 2 34.650 2 Kumbalam 2 27.133 2.585 NS 3 Thekkumbad 3 39.783 1 Pre monsoon 40.883 2 Monsoon 24.567 4.496 NS 3 Post monsoon 36.117 Alkalinity 1 Ayiramthengu 2 172.083 2 Kumbalam 2 122.083 6.247 NS 3 Thekkumbad 3 154.583 1 Pre monsoon 177.50 2 Monsoon 123.75 5.543 NS 3 Post monsoon 147.50 170 Hardness 1 Ayiramthengu 2 3279.667 2 Kumbalam 2 1736.917 2.555 NS 3 Thekkumbad 3 3607.889 1 Pre monsoon 5660.00 2 Monsoon 359.472 18.118* 3 Post monsoon 2605.00 Calcium 1 Ayiramthengu 2 273.321 2 Kumbalam 2 130.838 2.444 NS 3 Thekkumbad 3 297.27 1 Pre monsoon 407.847 2 Monsoon 49.925 9.690* 3 Post monsoon 243.657 Magnesium 1 Ayiramthengu 2 632.381 2 Kumbalam 2 343.3477 2.529 NS 3 Thekkumbad 3 697.6966 1 Pre monsoon 1130.059 2 Monsoon 57.2249 20.736* 3 Post monsoon 486.141 Chloride (Mg/l) 1 Ayiramthengu 2 13107.78 2 Kumbalam 2 7669.775 2.646 NS 3 Thekkumbad 3 14190.43 1 Pre monsoon 19465.83 2 Monsoon 2005.053 17.072* 3 Post monsoon 13497.1 Sulphate (Mg/l) 1 Ayiramthengu 2 52.41667 2 Kumbalam 2 35.27083 3.375 NS 3 Thekkumbad 3 46.08333 1 Pre monsoon 78.125 2 Monsoon 11.35417 50.045* 3 Post monsoon 44.29167 Sodium (ppt) 1 Ayiramthengu 2 14.303 2 Kumbalam 2 8.447 3.429 NS 3 Thekkumbad 3 15.107 1 Pre monsoon 21.629 2 Monsoon 1.273 27.938* 3 Post monsoon 14.954 Nitrogen (mg/l) 1 Ayiramthengu 2 69.75 2 Kumbalam 2 64.583 3 Thekkumbad 3 58.917 1.028 NS 1 Pre monsoon 41.75 2 Monsoon 68.25 3 Post monsoon 83.25 15.457* 171 Phosphorous (mg/l) 1 Ayiramthengu 2 18.242 2 Kumbalam 2 20.233 3.038 NS 3 Thekkumbad 3 48.486 1 Pre monsoon 44.200 2 Monsoon 31.086 2.843 NS 3 Post monsoon 11.675 Potassium (mg/l) 1 Ayiramthengu 2 387.083 2 Kumbalam 2 349.167 2.385 NS 3 Thekkumbad 3 154.167 1 Pre monsoon 362.500 2 Monsoon 292.500 0.619 NS 3 Post monsoon 235.417 SEDIMENT ANALYSIS pH 1 Ayiramthengu 2 7.247 2 Kumbalam 2 7.153 1.901 NS 3 Thekkumbad 3 6.639 1 Pre monsoon 7.590 2 Monsoon 6.366 6.712 NS 3 Post monsoon 7.082 Moisture % 1 Ayiramthengu 2 8.888 2 Kumbalam 2 11.117 1.577 NS 3 Thekkumbad 3 11.518 1 Pre monsoon 8.958 2 Monsoon 11.304 1.414 NS 3 Post monsoon 11.259 Sand % 1 Ayiramthengu 2 90.358 2 Kumbalam 2 83.300 2.578 NS 3 Thekkumbad 3 86.175 1 Pre monsoon 90.492 2 Monsoon 86.867 3.298 NS 3 Post monsoon 82.475 Silt% 1 Ayiramthengu 2 0.575 2 Kumbalam 2 0.383 0.858 NS 3 Thekkumbad 3 0.983 1 Pre monsoon 0.175 2 Monsoon 0.983 1.619 NS 3 Post monsoon 0.783 Clay % 1 Ayiramthengu 2 9.067 2 Kumbalam 2 16.317 2.693 NS 3 Thekkumbad 3 12.842 1 Pre monsoon 9.333 2.864 NS 2 Monsoon 12.150 172 3 Post monsoon 16.742 Organic carbon(g/kg) 1 Ayiramthengu 2 35.108 2 Kumbalam 2 17.500 0.580 NS 3 Thekkumbad 3 29.242 1 Pre monsoon 21.283 2 Monsoon 49.083 2.745 NS 3 Post monsoon 11.483 Nitrogen(mg/kg) 1 Ayiramthengu 2 788.064 2 Kumbalam 2 1517.740 3.724 NS 3 Thekkumbad 3 1628.700 1 Pre monsoon 1021.563 2 Monsoon 1424.391 1.144 NS 3 Post monsoon 1488.550 Phosphorous(mg/kg) 1 Ayiramthengu 2 15.392 2 Kumbalam 2 43.117 13.315* 3 Thekkumbad 3 23.625 1 Pre monsoon 22.550 2 Monsoon 27.633 1.454 NS 3 Post monsoon 31.95 Potassium(mg/kg) 1 Ayiramthengu 2 41.508 2 Kumbalam 2 35.158 3 Thekkumbad 3 56.792 3.212 NS 1 Pre monsoon 46.417 2 Monsoon 41.4 3 Post monsoon 45.642 0.190 NS Sodium (ppt) 1 Ayiramthengu 2 0.316 2 Kumbalam 2 0.341 0.815 NS 3 Thekkumbad 3 0.441 1 Pre monsoon 0.458 2 Monsoon 0.178 5.007 NS 3 Post monsoon 0.463 *: Significant at 5% level; NS: not significant (critical value of F at 5% level for 3 locations x 3 seasons = 6.944). 173 Table 2.23. Comparative study of locations and seasons of Rhizophora mucronata with respect to water and sediment quality Sl No Source of Variation Average F- value WATER ANALYSIS pH 1 Ayiramthengu 3 7.383 2 Kumbalam 3 6.995 0.480NS 3 Thekkumbad 4 7.044 1 Pre monsoon 7.481 2 Monsoon 6.450 3.835 NS 3 Post monsoon 7.491 Turbidity 1 Ayiramthengu 3 9.683 2 Kumbalam 3 7.417 9.634* 3 Thekkumbad 4 21.119 1 Pre monsoon 9.986 2 Monsoon 13.725 1.043 NS 3 Post monsoon 14.508 Total solids 1 Ayiramthengu 3 23533.33 2 Kumbalam 3 12050 9.182* 3 Thekkumbad 4 28177.78 1 Pre monsoon 32394.44 2 Monsoon 3816.667 31.161* 3 Post monsoon 27550 Total Dissolved solids 1 Ayiramthengu 3 22.567 2 Kumbalam 3 11.367 9.745* 3 Thekkumbad 4 26.689 1 Pre monsoon 31.456 2 Monsoon 3.467 33.863* 3 Post monsoon 25.700 TSS 1 Ayiramthengu 3 966.6667 2 Kumbalam 3 683.333 0.468 NS 3 Thekkumbad 4 1488.889 1 Pre monsoon 938.889 2 Monsoon 350.00 1.601 NS 3 Post monsoon 1850.00 Salinity (ppt) 1 Ayiramthengu 3 18.92767 2 Kumbalam 3 9.819667 10.719* 3 Thekkumbad 4 22.468 1 Pre monsoon 27.026 2 Monsoon 3.336 38.021* 3 Post monsoon 20.85333 174 Resistivity (Ω) 1 Ayiramthengu 3 75.048 2 Kumbalam 3 499.886 1.325 NS 3 Thekkumbad 4 162.228 1 Pre monsoon 30.616 2 Monsoon 652.695 3.272 NS 3 Post monsoon 53.851 Conductivity (mS) 1 Ayiramthengu 3 28.831 2 Kumbalam 3 15.570 12.183* 3 Thekkumbad 4 33.414 1 Pre monsoon 40.357 2 Monsoon 5.669 46.316* 3 Post monsoon 31.789 Acidity 1 Ayiramthengu 3 34.833 2 Kumbalam 3 23.467 12.955* 3 Thekkumbad 4 33.550 1 Pre monsoon 35.933 2 Monsoon 20.350 26.438* 3 Post monsoon 35.567 Alkalinity 1 Ayiramthengu 3 171.667 2 Kumbalam 3 112.083 2.190 NS 3 Thekkumbad 4 145.833 1 Pre monsoon 161.667 2 Monsoon 125.00 0.825 NS 3 Post monsoon 142.917 Hardness 1 Ayiramthengu 3 3273.333 2 Kumbalam 3 1852.500 6.193 NS 3 Thekkumbad 4 3968.500 1 Pre monsoon 5635.000 2 Monsoon 647.167 33.307* 3 Post monsoon 2812.167 Calcium 1 Ayiramthengu 3 270.976 2 Kumbalam 3 144.121 10.108* 3 Thekkumbad 4 297.433 1 Pre monsoon 379.141 2 Monsoon 72.937 35.872* 3 Post monsoon 260.453 Magnesium 1 Ayiramthengu 3 632.231 2 Kumbalam 3 363.414 3 Thekkumbad 4 785.412 5.418 NS 1 Pre monsoon 1141.443 2 Monsoon 113.241 3 Post monsoon 526.373 31.780* 175 Chloride (Mg/l) 1 Ayiramthengu 3 13566.92 2 Kumbalam 3 7931.717 9.641* 3 Thekkumbad 4 16134.75 1 Pre monsoon 19702.33 2 Monsoon 3234.05 39.028* 3 Post monsoon 14697.00 Sulphate (Mg/l) 1 Ayiramthengu 3 51.208 2 Kumbalam 3 40.292 2.121 NS 3 Thekkumbad 4 51.222 1 Pre monsoon 80.056 2 Monsoon 15.750 55.138* 3 Post monsoon 46.917 Sodium (ppt) 1 Ayiramthengu 3 13.357 6.539 NS 2 Kumbalam 3 7.718 3 Thekkumbad 4 16.129 1 Pre monsoon 19.681 2 Monsoon 2.110 29.889* 3 Post monsoon 15.412 Nitrogen (mg/l) 1 Ayiramthengu 3 56.417 2 Kumbalam 3 58.917 4.369 NS 3 Thekkumbad 4 72.889 1 Pre monsoon 44.722 2 Monsoon 63.583 17.198* 3 Post monsoon 79.917 Phosphorous (mg/l) 1 Ayiramthengu 3 34.795 2 Kumbalam 3 38.685 0.494 NS 3 Thekkumbad 4 43.14 1 Pre monsoon 75.183 2 Monsoon 30.27 30.616* 3 Post monsoon 11.167 Potassium (mg/l) 1 Ayiramthengu 3 376.25 2 Kumbalam 3 317.083 0.297 NS 3 Thekkumbad 4 317.083 1 Pre monsoon 325.00 2 Monsoon 398.75 0.827 NS 3 Post monsoon 286.667 SEDIMENT ANALYSIS pH 1 Ayiramthengu 3 7.510 2 Kumbalam 3 6.878 13.740* 3 Thekkumbad 4 6.430 1 Pre monsoon 7.183 2.174 NS 2 Monsoon 6.770 176 3 Post monsoon 6.866 Moisture % 1 Ayiramthengu 3 7.585 2 Kumbalam 3 13.647 3.8681* 3 Thekkumbad 4 9.953 1 Pre monsoon 11.899 2 Monsoon 10.405 0.944 NS 3 Post monsoon 8.881 Sand % 1 Ayiramthengu 3 90.475 2 Kumbalam 3 74.717 23.013* 3 Thekkumbad 4 52.200 1 Pre monsoon 76.108 2 Monsoon 66.808 1.533 NS 3 Post monsoon 74.475 Silt% 1 Ayiramthengu 3 0.233 2 Kumbalam 3 0.275 0.556 NS 3 Thekkumbad 4 0.433 1 Pre monsoon 0.208 2 Monsoon 0.458 0.837 NS 3 Post monsoon 0.275 Clay % 1 Ayiramthengu 3 9.292 2 Kumbalam 3 25.008 23.069* 3 Thekkumbad 4 47.367 1 Pre monsoon 23.683 2 Monsoon 32.733 1.474 NS 3 Post monsoon 25.250 Organic carbon(g/kg) 1 Ayiramthengu 3 23.708 2 Kumbalam 3 23.025 0.0275 NS 3 Thekkumbad 4 21.375 1 Pre monsoon 29.692 2 Monsoon 21.375 0.791 NS 3 Post monsoon 17.042 Nitrogen(mg/kg) 1 Ayiramthengu 3 23.708 2 Kumbalam 3 23.025 0.028 NS 3 Thekkumbad 4 21.375 1 Pre monsoon 29.692 2 Monsoon 21.375 0.791 NS 3 Post monsoon 17.042 Phosphorous(mg/kg) 1 Ayiramthengu 3 21.283 2 Kumbalam 3 *52.400 51.151 3 Thekkumbad 4 57.500 1 Pre monsoon NS45.583 0.486 177 2 Monsoon 41.767 3 Post monsoon 43.833 Potassium(mg/kg) 1 Ayiramthengu 3 47.467 2 Kumbalam 3 NS65.733 4.133 3 Thekkumbad 4 258.917 1 Pre monsoon 106.250 2 Monsoon 70.342 1.251 NS 3 Post monsoon 195.525 Sodium (ppt) 1 Ayiramthengu 3 0.319 2 Kumbalam 3 NS0.287 2.114 3 Thekkumbad 4 0.551 1 Pre monsoon 0.482 2 Monsoon 0.150 4.304 NS 3 Post monsoon 0.526 *: Significant at 5% level; NS: not significant (critical value of F at 5% level for 3 locations x 3 seasons = 6.944). Table 2.24. Comparative study of locations and seasons of Sonneratia alba with respect to water and sediment quality Sl No Source of Variation Average F- value WATER ANALYSIS pH 1 Kadalundi 3 7.988 2 Kadalundi 4 7.9548 9.455* 3 Thekkumbad 5 6.961 1 Pre monsoon 7.942 2 Monsoon 7.222 3.808NS 3 Post monsoon 7.738 Turbidity 1 Kadalundi 3 15.6 2 Kadalundi 4 14.275 3 Thekkumbad 5 11.675 0.194 NS 1 Pre monsoon 12.492 2 Monsoon 14.325 3 Post monsoon 14.733 0.070 NS Total solids 1 Kadalundi 3 25966.67 2 Kadalundi 4 25916.67 0.031 NS 3 Thekkumbad 5 26538.89 1 Pre monsoon 43216.67 98.449* 2 Monsoon 4922.223 178 3 Post monsoon 30283.33 Total Dissolved solids 1 Kadalundi 3 25.283 2 Kadalundi 4 25.033 0.014 NS 3 Thekkumbad 5 25.461 1 Pre monsoon 41.850 2 Monsoon 4.378 110.679* 3 Post monsoon 29.550 TSS 1 Kadalundi 3 683.333 2 Kadalundi 4 883.333 0.385 NS 3 Thekkumbad 5 1077.778 1 Pre monsoon 1366.667 2 Monsoon 544.444 1.834 NS 3 Post monsoon 733.333 Salinity (ppt) 1 Kadalundi 3 20.789 2 Kadalundi 4 21.617 0.179 NS 3 Thekkumbad 5 22.583 1 Pre monsoon 35.254 2 Monsoon 3.758 58.252* 3 Post monsoon 25.977 Resistivity (Ω) 1 Kadalundi 3 260.369 2 Kadalundi 4 134.414 0.916 NS 3 Thekkumbad 5 220.670 1 Pre monsoon 18.970 2 Monsoon 565.482 21.511* 3 Post monsoon 31.000 Conductivity (mS) 1 Kadalundi 3 31.065 2 Kadalundi 4 32.391 0.130 NS 3 Thekkumbad 5 33.348 1 Pre monsoon 51.546 2 Monsoon 6.381 53.884* 3 Post monsoon 38.876 Acidity 1 Kadalundi 3 29.443 2 Kadalundi 4 24.090 6.422 NS 3 Thekkumbad 5 45.222 1 Pre monsoon 42.533 2 Monsoon 17.906 9.231* 3 Post monsoon 38.317 Alkalinity 1 Kadalundi 3 171.250 2 Kadalundi 4 171.667 0.049 NS 3 Thekkumbad 5 167.222 1 Pre monsoon 200.833 18.416* 2 Monsoon 115.139 179 3 Post monsoon 194.167 Hardness 1 Kadalundi 3 3679.917 2 Kadalundi 4 3675.250 0.021 NS 3 Thekkumbad 5 3724.556 1 Pre monsoon 7280.00 2 Monsoon 375.2223 336.792* 3 Post monsoon 3424.50 Calcium 1 Kadalundi 3 290.926 2 Kadalundi 4 280.283 0.158 NS 3 Thekkumbad 5 277.627 1 Pre monsoon 483.942 2 Monsoon 49.564 153.375* 3 Post monsoon 315.330 Magnesium 1 Kadalundi 3 719.101 2 Kadalundi 4 724.435 0.053 NS 3 Thekkumbad 5 738.053 1 Pre monsoon 1478.250 2 Monsoon 61.243 282.331* 3 Post monsoon 642.097 Chloride (Mg/l) 1 Kadalundi 3 16385.62 2 Kadalundi 4 15460.25 0.474 NS 3 Thekkumbad 5 15572.27 1 Pre monsoon 25169.50 2 Monsoon 2653.822 255.366* 3 Post monsoon 19594.82 Sulphate (Mg/l) 1 Kadalundi 3 55.125 2 Kadalundi 4 53.083 0.733 NS 3 Thekkumbad 5 47.014 1 Pre monsoon 84.750 2 Monsoon 19.097 44.391* 3 Post monsoon 51.375 Sodium (ppt) 1 Kadalundi 3 14.924 2 Kadalundi 4 14.999 0.638 NS 3 Thekkumbad 5 18.297 1 Pre monsoon 26.200 2 Monsoon 1.361 29.220* 3 Post monsoon 20.659 Nitrogen (mg/l) 1 Kadalundi 3 98.917 2 Kadalundi 4 56.00 1.253 NS 3 Thekkumbad 5 56.167 1 Pre monsoon 43.167 1.364 NS 2 Monsoon 94.500 180 3 Post monsoon 73.417 Phosphorous (mg/l) 1 Kadalundi 3 33.083 2 Kadalundi 4 39.768 0.774 NS 3 Thekkumbad 5 31.474 1 Pre monsoon 57.020 2 Monsoon 31.764 17.476* 3 Post monsoon 15.542 Potassium (mg/l) 1 Kadalundi 3 350.833 2 Kadalundi 4 346.250 0.146 NS 3 Thekkumbad 5 268.611 1 Pre monsoon 275.00 2 Monsoon 329.861 0.130 NS 3 Post monsoon 360.833 SEDIMENT ANALYSIS pH 1 Kadalundi 3 7.955 2 Kadalundi 4 8.023 23.787* 3 Thekkumbad 5 6.708 1 Pre monsoon 7.862 2 Monsoon 6.981 10.983* 3 Post monsoon 7.843 Moisture % 1 Kadalundi 3 10.467 2 Kadalundi 4 9.382 0.599 NS 3 Thekkumbad 5 10.027 1 Pre monsoon 9.429 2 Monsoon 10.740 0.961 NS 3 Post monsoon 9.706 Sand % 1 Kadalundi 3 86.958 2 Kadalundi 4 84.100 4.609 NS 3 Thekkumbad 5 75.375 1 Pre monsoon 82.558 2 Monsoon 80.858 0.164 NS 3 Post monsoon 83.017 Silt% 1 Kadalundi 3 0.433 2 Kadalundi 4 0.492 3 Thekkumbad 5 0.592 0.320 NS 1 Pre monsoon 0.267 2 Monsoon 0.883 3 Post monsoon 0.367 5.471 NS Clay % 1 Kadalundi 3 12.625 2 Kadalundi 4 15.400 4.705 NS 3 Thekkumbad 5 24.025 1 Pre monsoon 17.167 0.096 NS 181 2 Monsoon 18.275 3 Post monsoon 16.608 Organic carbon(g/kg) 1 Kadalundi 3 20.758 2 Kadalundi 4 23.292 0.083 NS 3 Thekkumbad 5 19.058 1 Pre monsoon 18.933 2 Monsoon 16.050 0.730 NS 3 Post monsoon 28.125 Nitrogen(mg/kg) 1 Kadalundi 3 834.763 2 Kadalundi 4 788.063 0.699 NS 3 Thekkumbad 5 737.860 1 Pre monsoon 551.060 2 Monsoon 1079.937 21.539* 3 Post monsoon 729.690 Phosphorous(mg/kg) 1 Kadalundi 3 41.50 2 Kadalundi 4 37.633 7.671* 3 Thekkumbad 5 29.833 1 Pre monsoon 42.50 2 Monsoon 40.467 17.583* 3 Post monsoon 26.00 Potassium(mg/kg) 1 Kadalundi 3 63.25 2 Kadalundi 4 56.567 0.950 NS 3 Thekkumbad 5 77.483 1 Pre monsoon 69.833 2 Monsoon 47.00833 2.433 NS 3 Post monsoon 80.45833 Sodium (ppt) 1 Kadalundi 3 0.473 2 Kadalundi 4 0.449 0.107 NS 3 Thekkumbad 5 0.502 1 Pre monsoon 0.512 2 Monsoon 0.237 7.555* 3 Post monsoon 0.675 *: Significant at 5% level; NS: not significant (critical value of F at 5% level for 3 locations x 3 seasons = 6.944). Upon analyzing the results, in the case of Avicennia officinalis, the mean pH has ranged from 6.89 and 7.5 between 3 habitats. With respect to different seasons, it varied from 6.46 to 7.43. However, results of statistical analysis showed that variations in pH among sites and also between seasons were not significant. In the case of Bruguiera cylindrica, the mean water pH varied from 7.13 to 7.749 among 182 sites and 6.97 to 7.67 among seasons. Upon statistical analysis, average water pH with respect to B. cylindrica showed significant variations both between sites and seasons. In the case of Excoecaria agallocha and Rhizophora mucronata, the mean water pH showed no significant variation between locations and seasons. However, with respect to Sonneratia alba the variations in mean water pH was significant among the locations and not significant between seasons. As far as mean turbidity of water is concerned, significant variation between sampling locations and seasons were noticed in the case of Avicennia officinalis. On the other hand, in the case of Excoecaria agallocha and Sonneratia alba, the mean turbidity values did not show any significant variation between sites and seasons. With respect to Bruguiera cylindrica and Rhizophora mucronata, the variations in turbidity were significant between locations, but not significant among seasons. Significant variations in the total solids (TS) and total dissolved solids (TDS) of water confining to the habitats of Avicennia officinalis, Bruguiera cylindrica, Excoecaria agallocha and Sonneratia alba were noticed among different seasons. However, the variations among sites were not statistically significant. In the case of Rhizophora mucronata, significant variation in mean TS and TDS were noticed both between locations and seasons. Total suspended solids (TSS) did not show any significant variation between sites and seasons with respect to all the five mangrove species. In the case of Rhizophora mucronata, mean salinity and conductivity showed significant variation among different seasons and locations. With respect to all other species, the variation was significant only among seasons. The variations in mean resistivity were not significant among sites and seasons with respect to all the species except Sonneratia alba wherein, significant variation was noticed among seasons. Results of the analysis of chemical attributes of water revealed that, the mean acidity with respect to Avicennia officinalis, Bruguiera cylindrica and Rhizophora mucronata was significantly varied between the three sites and the three seasons under study. In the case of Sonneratia alba variations in mean acidity was 183 significant only between seasons whereas, no significant variation among sites and seasons were noticed in the case of Excoecaria agallocha. Significant variation in mean alkalinity between seasons has been noticed in the case of Sonneratia alba. However, in the case of all other species no significant variation in mean alkalinity has been noticed between different seasons and sites. Variation in mean values of hardness, calcium, magnesium and chloride between different seasons has been noticed in the case of all mangrove species except Rhizophora mucronata. But the variations between different sites were not significant. In the case of R. mucronata, calcium and chloride showed significant variations between sites and seasons. The variations in mean sulphate concentration were not significant among locations of all the five mangrove species under study, where as significant variations were noticed between seasons. Sodium concentration with respect to 5 mangrove species showed significant variation among seasons. In the case of Avicennia officinalis and Sonneratia alba, results of the statistical analysis revealed no significant variation in mean nitrogen concentration between locations and seasons. With respect to Bruguiera cylindrica, Excoecaria agallocha and Rhizophora mucronata, significant variation in mean nitrogen was noticed between seasons whereas, the variations between sites were not significant. Significant variation in mean phosphorous concentration has been noticed between seasons in the case of R. mucronata and S. alba, whereas the variations between sites were not significant. With respect to A. officinalis, B. cylindrica and E. agallocha, variations in mean phosphorous were not significant both among different sites and seasons. In the case of all five species of mangroves, no significant variation in mean potassium level has been noticed among different sites and seasons. Results of statistical analysis of sediment quality attributes revealed no significant variation in mean pH between different season and sites in the case Avicennia officinalis, Bruguiera cylindrica and Excoecaria agallocha. With respect to Sonneratia alba, significant variation in pH among sites and also between seasons 184 were noticed. Variations in sediment pH with respect to Rhizophora mucronata were significant between sites and not significant among seasons. The mean moisture percentage did not show any significant variation among sites and seasons in the case of Avicennia officinalis, Excoecaria agallocha and Sonneratia alba whereas, significant variations between sites were noticed in the case of Bruguiera cylindrica and Rhizophora mucronata. The textural percentage (sand, silt and clay) did not show any significant variations among different locations and seasons with respect to A. officinalis, E. agallocha and S. alba. Significant variations in mean silt % between seasons were noticed in the case of B. cylindrica. In the case of R. mucronata, mean sand and clay % showed significant variation among different locations. As far as the mean sediment organic carbon with respect to all the five species concerned, no significant variations have been noticed among different sites and seasons under study. The variation in the average nitrogen content was not significant among different sites and seasons in the case of Avicennia officinalis, Excoecaria agallocha and Rhizophora mucronata. Significant variations in mean nitrogen between the locations in the case of Bruguiera cylindrica and between seasons in the case of Sonneratia alba have also been noticed. Significant variations in mean phosphorous concentration between locations have been noticed in the case of all species, except S. alba whereas, the variations between seasons were not significant. With respect to S. alba, variations in mean phosphorous concentration were significant between different sites and seasons. In the case of all the five mangrove species, mean potassium level did not show any significant variations between different locations and seasons. With respect to Bruguiera cylindrica and Sonneratia alba, significant variations in mean sodium level have been noticed between different seasons. No significant variations in sodium among different sites and seasons have been noticed in the case of Avicennia officinalis, Excoecaria agallocha and Rhizophora mucronata. 185 The study as a whole revealed that, in the case of Avicennia officinalis no significant variation in water quality attributes like pH, total suspended solids, resistivity, alkalinity, nitrogen, phosphorous and potassium and also with respect to sedimentological attributes like pH, moisture %, organic carbon, nitrogen, potassium, sodium, sand, silt and clay % between different sites and seasons have been noticed (Figure 2.2). The habitats of Bruguiera cylindrica is unswerving in their water quality attributes such as resistivity, alkalinity, phosphorous and potassium; and also sedimentological characteristics like sediment pH, sand %, clay %, organic carbon and potassium (Figure 2.3). The heterogeneous habitats of the mangrove species Excoecaria agallocha showed stability in their water quality attributes such as pH, turbidity, total suspended solids, resistivity, acidity, alkalinity, phosphorous and potassium and also with respect to sedimentological characteristics such as pH, moisture %, sand, silt, clay %, organic carbon, nitrogen, potassium and sodium (Figure 2.4). Likewise, the habitats of Rhizophora mucronata showed steadiness with respect to water quality parameters such as pH, TSS, resistivity, alkalinity and potassium and also in sedimentological characteristics such as silt %, organic carbon, nitrogen, potassium and sodium without any significant variation (Figure 2.5). The habitats of Sonneratia alba under study maintained uniformity with respect water quality attributes such as turbidity, TSS, nitrogen, potassium and sedimentological attributes such as moisture %, sand, silt, clay %, organic carbon and potassium (Figure 2.6). From the above observations, it can be concluded that all the five mangrove species under study; Avicennia officinalis, Bruguiera cylindrica, Excoecaria agallocha, Rhizophora mucronata and Sonneratia alba have their own growth sustaining conditions along different habitats in Kerala. The physico-chemical attributes of both water and sediment that showed no significant variations between sites and seasons can be confirmed as the growth promoting factors for each mangrove species under study. The ranges with respect to all such attributes have been confirmed as ideal for the sustenance of each species and confirmed as their tolerance range. Even though each species has its own specific growth 186 requirements, existence along habitats with varied water and sediment quality attributes highlights their ability to survive in such conditions. These varied ranges can be confirmed as the augmented range acquired by each species towards their growth and survival. Thus, the study as a whole reports the capability of all the five species of mangroves to cope up with different hydrogeochemical and sedimentological conditions in terms of tolerance range or augmented range, as stated in Table 2.19. Summary and Conclusion Afforestation of mangroves seems to be a promising solution for the restoration of lost ecosystems. Successful restoration/afforestation practices of mangroves require reliable information on their growth sustaining conditions. The present study has been carried out to evaluate the environmental factors (water, soil / sediment and climate) determining the growth of selected mangrove species (Avicennia officinalis, Bruguiera cylindrica, Excoecaria agallocha, Rhizophora mucronata and Sonneratia alba) along heterogeneous habitats of Kerala. The natural habitats selected for mangroves include Kumbalam 1 of Ernakulam district (9⁰54'15.68"N: 76⁰18'46.59"E), Kadalundi 1 of Malappuram district (11⁰07'42.49"N: 75⁰49'53.31"E) and Thekkumbad 1 of Kannur district (11⁰58'00.10"N: 75⁰17'49.27"E) (Avicennia officinalis), Ayiramthengu 1 of Kollam district (9007'28.93"N: 76028'39.18"E), Kadalundi 2 of Malappuram district (11⁰07'53.40"N: 75⁰49'45.79"E) and Thekkumbad 2 of Kannur district (11⁰58'00.12"N: 75⁰17'50.14"E), (Bruguiera cylindrica), Ayiramthengu 2 of Kollam district (9⁰07'28.71"N: 76⁰28'38.89"E), Kumbalam 2 of Ernakulam district (9⁰54'15.02"N: 76⁰18'45.49"E) and Thekkumbad 3 of Kannur district (11⁰58'00.71"N: 75⁰17'49.79"E) (Excoecaria agallocha), Ayiramthengu 3 of Kollam district (9⁰07'28.74"N: 76⁰28'39.44"E), Kumbalam 3 of Ernakulam district (9⁰54'22.16"N: 76⁰18'42.21"E) and Thekkumbad 4 of Kannur district (11⁰58'02.87"N: 75⁰17'45.38"E). (Rhizophora mucronata) and Kadalundi 3 (11⁰07'35.14"N: 75⁰49'51.77"E) and Kadalundi 4 of Malappuram district (11⁰07'35.42"N: 75⁰49'50.72"E) and Thekkumbad 5 (11⁰58'04.32"N: 75⁰17'45.38"E) of Kannur district (Sonneratia alba). 187 Both surface water and sediment/soil samples were collected on a monthly basis from all the locations under study for a period of one year. The collected samples were brought to laboratory and analyzed for various quality attributes following standard procedures. Characterization of sediment samples using textural triangle have also been worked out. Data on various climatological attributes with respect to all the sites and period of study were procured from India Meteorological Department, Government of India. Results of water, sediment and climatological attributes revealed that all the parameters were fluctuating between various sites and seasons. The mean annual range of all the parameters was calculated with respect to the study sites of different mangrove species. The mean values of both water and sediment characteristics were further analyzed statistically to find out the variations among different sites and seasons. Two-way ANOVA has revealed the number of most vital physico chemical attributes of water and sediment, that are likely to influence the growth of each mangrove species. The results as a whole revealed that between different sites and seasons, no significant variations have been noticed in water quality attributes like pH, total suspended solids, resistivity, alkalinity, nitrogen, phosphorous, potassium and sedimentological attributes like pH, moisture %, organic carbon, nitrogen, potassium, sodium, sand, silt and clay % of sites having Avicennia officinalis. The habitats of Bruguiera cylindrica is unswerving in their water quality attributes such as resistivity, alkalinity, phosphorous and potassium; and also sedimentological characteristics like sediment pH, sand %, clay %, organic carbon and potassium. The heterogeneous habitats of the mangrove species Excoecaria agallocha showed stability in their water quality attributes such as pH, turbidity, total suspended solids, resistivity, acidity, alkalinity, phosphorous and potassium and also in sedimentological characteristics such as pH, moisture %, sand, silt, clay %, organic carbon, nitrogen, potassium and sodium. Likewise, the habitats of Rhizophora mucronata showed steadiness with respect to water quality parameters such as pH, TSS, resistivity, alkalinity and potassium and also in sedimentological characteristics such as silt %, organic carbon, nitrogen, potassium and sodium without any significant variation. The habitats of Sonneratia alba under study 188 maintained consistency with respect water quality attributes such as turbidity, TSS, nitrogen, potassium and sedimentological attributes such as moisture %, sand, silt, clay %, organic carbon and potassium. From the above observations, it can be concluded that all the five mangrove species have their own growth sustaining conditions along different habitats in Kerala. The physico-chemical attributes of both water and sediment that showed no significant variations between sites and seasons can be confirmed as the growth promoting factors for each mangrove species under study. The range of all such attributes has been confirmed as ideal for the sustenance of each species and confirmed it as their tolerance range. Even though each species has its own specific growth requirements, existence along habitats with varied water and sediment quality attributes highlights their ability to survive in such conditions. These varied ranges can be confirmed as the augmented range acquired by each species towards their growth and survival. Thus, the study as a whole reports the capability of all the five species of mangrove to cope up with different hydrological and sedimentological conditions in terms a tolerance range or augmented range. Results of the textural characterization of sediments revealed the ideal sediment class on which each mangrove species showed lushness of growth. These include Sandy Loam (Avicennia officinalis and Sonneratia alba), Loamy Sand (Bruguiera cylindrica and Excoecaria agallocha) and Sandy Clay Loam (Rhizophora mucronata). The present investigation concluded that the criteria to be followed in the afforestation of mangroves need to be (i) species specific and (ii) site specific. The study also proposed that, the ‘tolerance range’ of a species with respect to the site is a mandatory requirement towards including them in afforestation purposes whereas the ‘augmented range’ is not a natural one; it is gradually acquired after the acclimatization of the species in the new area. In conclusion, the study emphasized that all the afforestation/ restoration practices of mangroves must be either species or site specific. 189 CHAPTER 3 DELINEATION OF SITES IDEAL FOR MANGROVE AFFORESTATION IN THE COASTAL ENVIRONMENTS OF KERALA Introduction Mangrove forest along the coastal environments of tropical and subtropical countries have great significance as they function towards the sustenance of broader range of living being including human. The uncontrolled exploitation and degradation of mangroves in most of the tropical countries have called for an urgent need of implementing conservation and management strategies. The drastic decline in global mangrove cover and the continued elimination of mangrove habitats have led many of the governmental and non-governmental organizations to formulate policies and actions (Giri et al., 2011). Protection of mangrove habitat across the world has also been achieved by establishing marine protected areas, including national parks and marine reserves. In India strategies pertaining to the conservation and reforestation of mangroves have initiated along the Central West coast. This was mainly with the intention of creating awareness among public regarding the significance of mangroves, control of intertidal mud banks, new avenues for forestry and social forestry activities, biomass increase along the estuaries to enhance biological productivity and to improve bird and animal life (Untawale, 1996). In Kerala, the most vital approach towards the conservation of mangroves relied on awareness among the public. Novel concepts like mangrove resort and conservation through eco-tourism have also been put forwarded towards the protection of mangroves (George and Fernandez, 1994). For the conservation of mangrove environments of Kerala, better co-ordination among various government agencies are also inevitable. Silvicultural techniques like regeneration, restoration and afforestation of mangroves can very well reverse the issues of degradation. Mangrove conservation requires a 190 collaborated research involving natural, social and inter-disciplinary approaches. In order to formulate long term conservation strategies, consideration of factors such as monitoring of growth conditions, socio-economic dependency and biodiversity are indispensable (Kiran and Ramachandra, 1999). Other aspects to be covered for proper management of mangrove ecosystems are study of geomorphology, freshwater input, toxic elements, structure and composition of mangrove ecosystem using remote sensing data, aerial photography etc. Restoring mangroves is often recommended when the ecosystem has been modified to such an extent that it cannot regenerate naturally. Although restoration frequently emphasizes planting as the primary method, mangroves can regenerate naturally if the normal tidal hydrology is restored and the supply of seeds or propagules of mangroves from adjacent stands re-established. If hydrology is normal, but the influx of seeds or propagules is disrupted, then mangroves can be successfully established by planting. Alternatively, when the hydrology is disrupted but the availability of seeds or propagules is normal, then mangroves can be established by hydrological restoration (Kathiresan, 2011). Planting of mangroves is largely confined to two types: i) direct planting of seeds or propagules in the muddy areas; and ii) planting of seedlings obtained from nurseries. In the first type, propagules can be used directly as long as they are plentiful. The second can be adopted for seeds that are available seasonally and in small quantities. In this type, nurseries are developed in the upper parts of intertidal areas, using polythene bags, for 6–12 months. The plants are then transplanted in the field according to their zoning patterns. Direct planting of propagules is often unsuccessful if the area is exposed, with unfavorable climatic conditions or strong waves or if propagule-eating crabs are abundant. In such areas, nursery seedlings should be used. Mangrove ecosystems are often cited as being responsive to differences in soil salinity, frequency of tidal inundation, sedimentation, soil chemistry, freshwater influx and groundwater availability. This is said to have led to significant variations noted in mangrove community structure and function, even within small geographic 191 ranges (Ravichandran, 2002). The restoration program should be sensibly designed in such a way that, mass afforestation of the native species and elimination of undesirable species are carried out. Restoration sometimes requires reconstruction of the physical conditions, chemical adjustment of the soil and water, biological manipulation, reintroduction of native flora and fauna, etc. (Zedler, 1996). Different mangrove species have different requirements. Some are more tolerant to salt than others. Other factors, which affect their distribution, include wave energy, soil oxygen level, drainage and differing nutrient levels, where one species finds its preferred conditions, it tends to become dominant. This leads to zonation among mangroves. The existence of more or less distinct zones, each dominated by different mangrove species is usually evident in well-developed mangals. Mangrove zonation however, is more often manifested as a mosaic that varies with the complex of physical, chemical and biological interaction occurring in a particular area. Species selection is critical for successful restoration of mangroves. Selection can be based on criteria such as planting purpose, adaptability, occurrence, availability of mature propagules, size of propagules, and zoning pattern of species. Mangrove species selection can be based on species that occur naturally in the locality. It is also necessary to collect data on the historical occurrence of species. Site selection for restoration should be based on criteria such as tidal amplitude, soil conditions, light conditions, sedimentation, pollution status, and weed and pest problems (Kathiresan, 1994). Most of the mangrove restoration programs focused on the mangrove species, their regeneration potential and also on the method of afforestation. A comprehensive approach in terms of research on various aspects of mangrove eco system of Kerala should be given utmost priority for their effective conservation and restoration. Restoration in terms of afforestation requires detailed comprehension on mangroves with respect to their current status, diversity, threats and growth sustaining conditions. Even though there are a wide variety of restoration techniques, in order to fit restoration efforts with the local physical and ecological settings and selecting the right species and right locations are very important. 192 As physico- chemical attributes of both water and sediment are a major entity towards the growth and proliferation of mangroves, their comprehension with respect to the targeted afforestation area is very much important. Assessment of the feasibility of the area prior to planting practices will reduce the risk of adaptability of species to such habitats and thereby cut short financial mobilizations to a greater extent. In this background, the present study has been undertaken for the demarcation of ideal sites for afforestation of selected mangrove species along the inland shoreline environments of Kerala. Review of Literature The present study is an attempt to delineate regions falling in the coastal environments of Kerala, which are ideal for species specific introduction of mangroves. This is achieved through the standardization of growth requirements of selected mangrove species from heterogeneous coastal environments (as attempted in Chapter 2) and thereby identifying specific habitats ideal for mangrove afforestation through strategic analysis of key inputs required for mangrove establishment. Description on previous attempts in the area of mangrove restoration carried out globally and also on the prospects of other afforestation strategies carried out is summarized below. Afforestation of mangroves on exposed mud flats, seaward of an eroding shoreline in Malaysia using the species Avicennia officinalis has been reported. The study concluded that factors such as strong wave actions, high soil salinity, barnacle infestation, prolonged inundation and lack of tidal flow were adversely affecting the survival and growth of mangrove plants (Chan et al., 1988). The successful afforestation along a larger area in Bangladesh employing direct planting of Rhizophora mucronata and Rhizophora apiculata has been reported (Saenger and Siddiqi, 1993). For stabilizing coastal areas, forest department of Bangladesh carried out afforestation programmes along selected coastal areas of the country. The species selected for the study were Sonneratia apetala and Avicennia officinalis and planting has been done in a total area of 320 ha. The study reported that, 193 afforestation of both the species along these sites was highly successful and further contributed to plan large scale programs (Saenger and Siddiqi, 1993). Afforestation using seedlings of Avicennia marina, Rhizophora mucronata and Sonneratia caseolaris along the newly formed mud flats of southern Thailand have been conducted and reported. Monthly assessment of the growth performances of all the species revealed that, both A. marina and S. caseolaris were unable to develop and died in eight months after planting. Severe infestation by barnacles and frequent immersion in seawater during high tide were the reason for seedling mortality. Among the three species, R. mucronata showed more resistance to these conditions (Angsupanich and Havanond, 1996). Studies on the re-plantation of mangroves in the seedling stage along the coastal environments of Thailand reported that, even though the afforestation practices conducted in a large area, the success rate of establishment was low as the species used were in the seedling stage (Platong, 1998). Natural regeneration potential of 11 species of mangrove has been reported in Bangladesh. Among different species, the species showed higher regeneration and lushness of growth were Sonneratia apetala, followed by Bruguiera sexangula, Avicennia officinalis, Excoecaria agallocha and Ceriops decandra (Haque et al., 2000). Study conducted in Thailand reported success stories of mangrove afforestation. Here, planting has been carried out on mud flats along a larger area and majority of the species showed enhanced growth rates (Erftemeijer and Lewis, 1999). Studies on the assessment of the hydrology of natural mangrove ecosystems has been carried out in USA to implement strategies for the protection of existing mangroves and to achieve successful and cost-effective ecological restoration (Lewis, 2005). Mangrove species prefer almost uniform environmental condition for their growth and establishment. This fact is evidenced by studies conducted along coastline of Tamil Nadu, India. The sites for afforestation have been selected after careful study on soil quality, species suitability, natural recruitment, land elevation, water sources, grazing effect and land-use. More than 10,000 mangrove seedlings have been 194 planted. It was reported that survival rate of the propagules varied in accordance with water and soil characteristics. The study concluded that, more emphasis should be given for monitoring different locations prior to afforestation (Balaji and Gross, 2006). Restoration of mangroves along the coastal environments of Peninsular Malaysia have been conducted and reported. Afforestation of Rhizophora apiculata seedlings were carried out within an already established cover of Avicennia marina forest. The results revealed that most of the planted seedlings died due to inadequate light and high soil salinity (Ong, 2007). With the objective of protecting the shoreline from coastal erosion, R. apiculata seedlings grown in PVC tubes were planted on the mud flats seaward of an existing mangrove forest of mainly A. marina. The result revealed that most of the seedlings had disappeared within a week. The study has concluded that, mangroves cannot survive on exposed low-elevation tidal flats (Ong, 2008). Mangrove planting along a fishpond area in mangrove arboretum belonging to agriculture and marine services of Indonesia has been carried out and reported (Kusmana, 2010). A simple technique called, ‘guludan’ was applied for the afforestation practices. True mangrove seedlings of Rhizophora mucronata / Avicennia marina were used and parameters such as stem diameter and height, carbon content, growth and survival rate were assessed. The study highlighted the possibilities of using this technique along other areas wherein, already applied techniques using either large cans-filled soil or bamboo basket which were always failed for growing mangrove seedlings (Kusmana, 2010). Studies on afforestation of mangroves and their regeneration potential along forest ranges of Bangladesh has been conducted and reported. The mangrove species used were Sonneratia apetala, Excoecaria agallocha, Avicennia officinalis, Ceriops decandra and Bruguiera sexangula. The results revealed that, the species regeneration were significantly higher for S. apetala followed by E.agallocha, A. officinalis, C. decandra and then B. sexangula. The study as a whole reported that in 195 accordance with species ecology and adaptability to the sites along the coast, their afforestation will show varied growth, regeneration and density (Uddin et al., 2013). Surveillance on water quality in pursuit of mangrove afforestation along the coastal and inland aquatic environments of Malappuram District, Kerala have been conducted and reported. Collection of water samples were carried out from 38 locations representing diverse habitats during pre-monsoon, monsoon and post-monsoon seasons. On the basis of salinity and related attributes, high salt tolerant species like Avicennia marina, A. officinalis, Rhizophora mucronata and Aegiceras corniculatum were found to be ideal for afforestation in 10 sites. Low salt tolerant species like Sonneratia caseolaris and Excoecaria agallocha were noted to be ideal for planting in 8 sites. Species like S. alba, which showed a tolerance limit over a wider range has been found ideal for afforestation in 14 selected sites. However medium salt tolerant species like R. apiculata, Bruguiera gymnorhiza and B. cylindrica were found to be unfit for afforestation in any of the sites studied. The study reported that on the basis of tolerance limit of mangrove species to salinity, 11 inland and estuarine aquatic environments of Malappuram District were ideal for afforestation during all seasons of the year (Shilna et al., 2016). Studies have been undertaken to demarcate regions ideal for the introduction of mangrove species of Rhizophora and Bruguiera in the core and buffer areas of Kadalundi community reserve, falling in Kozhikode and Malappuram districts of Kerala, India. During pre monsoon and monsoon season, collection of sediment and water samples was carried out for analytical purposes. The results revealed that, the water samples possessed higher concentrations of salinity, chloride and hardness in pre-monsoon than monsoon season. With respect to the sediment samples, organic carbon and percentage clay content were noted to be higher in both seasons. It has also been reported that, pre monsoon season is ideal for afforestation of both Rhizophora and Bruguiera species. Based on water and sediment quality, the possibilities of afforestation along all the zones under study have also been reported (Harilal et al., 2017). 196 All the above studies were carried out on mangroves, either with the intension of introduction or restoration. Even though there were success stories, majority of cases reported setbacks in afforestation / restoration, which can either be due to inadequate knowledge on the physico chemical and environmental setting of the area poised for afforestation or due to lack of knowledge on the growth requirements of mangrove species selected for afforestation. As physico- chemical attributes of both water and sediment are influential on the growth and establishment of mangroves, consolidation of database on the above aspects need to be considered prior to any afforestation / restoration programme. In this context, the present study has been attempted to elucidate regions ideal for species specific mangrove afforestation in the coastal environments falling in 9 districts of Kerala through strategic analysis of the key factors (hydrogeochemical and sedimentological) responsible for the growth of mangroves in the areas proposed for afforestation. This will reduce the risk associated with direct afforestation efforts as the present practice will give prior indices regarding the feasibility of a site for afforestation with respect to a designated species. Materials and Methods The present investigation was an attempt to delineate sites ideal for species specific mangrove afforestation along the heterogeneous coastal environments of Kerala. The afforestation possibilities of selected mangrove species were assessed based on their range of tolerance to various hydrogeochemical and sedimentological characteristics as determined in Chapter II. Similarly, for assessing the supportive nature of habitats, the physico-chemical characteristics of both water and sediments associated with such habitats were assessed and compared with those of the tolerance range of selected mangrove species. Altogether 19 habitats falling in Trivandrum and 18 habitats each in Kollam, Alleppey, Ernakulam, Thrissur, Malappuram, Kozhikode, Kannur and Kasaragod districts of Kerala (Figure 3.1 to 3.9) were worked out. Details of districts, together with the specification of sites selected are given below: 197 1) Trivandrum Trivandrum is the capital district of Kerala with a total geographic area of 2192 sq. km. Major physiographic unit comprises of midland, together with coastal low lands and high lands. The terrain is characterized by geological formations like crystalline and alluvium. The land use pattern shows both forest cover and agricultural lands. Important soil types in the district are red loam, alluvium, brown hydromorphic soil and lateritic soil. The climate experienced in the district is tropical monsoon with a normal annual rainfall of 2035mm. The mean maximum air temperature and humidity experienced in the district are 34ºC and 90% respectively (CGWB 2013). Table 3.1. Details of study area falling in Trivandrum district Location ID. Location Name Latitude Longitude TVM 1 Edayar 8o26'27.26"N 76 o 57'9.46"E TVM 2 Munnattumukku 8 o 26'30.53"N 76 o 57'13.45"E TVM 3 Manamel 8 o 25'55.38"N 76 o 57'28.55"E TVM 4 Panathura 8 o 25'3.55"N 76 o 57'48.37"E TVM 5 Pachallur 8o 25'18.94"N 76 o 57'36.46"E TVM 6 Thottumukku 8 o 25'30.61"N 76 o 57'34.99"E TVM 7 Vallappura 8 o 24'30.28"N 76 o 58'11.56"E TVM 8 Vattappara 8 o 24'20.97"N 76 o 58'16.62"E TVM 9 Madhavapuram 8 o 30'49.30"N 76 o 53'25.27"E TVM 10 Kayikkara kadavu 8 o 35'49.56"N 76 o 49'44.05"E TVM 11 Kundavila 8 o 36'2.88"N 76 o 49'28.85"E TVM 12 MurukkumPuzha Kadavu 8 o 36'34.96"N 76 o 49'22.73"E TVM 13 Kadinamkulam 8 o 36'17.50"N 76 o 49'13.97"E TVM 14 Vadakkevila 8 o 36'41.78"N 76 o 48'55.95"E TVM 15 Perumathura 8 o 37'22.57"N 76 o 48'8.94"E TVM 16 Kottaram Thuruth 8 o 37'35.69"N 76 o 48'4.61"E TVM 17 Thazhampally 8 o 38'15.25"N 76 o 47'3.74"E TVM 18 Anchuthengu 8 o 38'39.13"N 76 o 46'44.52"E TVM 19 Chambavu 8 o 39'55.60"N 76 o 45'49.27"E 2) Kollam Kollam district has a total geographic area of 2491 sq. km with coastal plain, mid land and high land as important physiographic units. The terrain is highly complex 198 with geological formations such as recent alluvium, sub-recent laterite, tertiary sedimentary formations, archaean crystallines and forest loam. The major soil types are laterite, brown hydromorphic, grayish onattukara and coastal riverine alluvium. The district experiences a tropical humid climate with definite southwest and northeast monsoon seasons. The normal annual rainfall available in the district is 2428mm. The annual mean maximum temperature and humidity are 36.4ºC and 89% respectively (CGWB 2013). Table 3.2. Details of study area falling in Kollam district Location ID. Location Name Latitude Longitude KLM 1 Kappil 8o46'28.50"N 76o40'47.24"E KLM 2 Edava 8o47'0.50"N 76o40'20.66"E KLM 3 Kurumandal 8o49'12.32"N 76o39'34.41"E KLM 4 Pozhikkara 8o48'56.73"N 76o39'3.88"E KLM 5 Mukkam 8o49'2.46"N 76o38'47.92"E KLM 6 Kochuthoppu 8o50'23.17"N 76o37'46.31"E KLM 7 Adhichamamthoppu 8o50'46.16"N 76o37'29.61"E KLM 8 Sasthamthodi 8 o 50'12.76"N 76o38'19.14"E KLM 9 Neeravil 8 o 55'21.63"N 76o35'17.05"E KLM 10 MadathilKayalvaaram 8 o 55'39.97"N 76o33'43.88"E KLM 11 Velithuruth 8 o 57'9.37"N 76o32'43.58"E KLM 12 Ponmana 9o0'42.95"N 76o31'18.16"E KLM 13 Kozhikkode 9o1'36.41"N 76o31'9.43"E KLM 14 Kochochira 9o2'15.41"N 76o30'32.06"E KLM 15 Cheriyazheekkal 9o3'32.35"N 76o30'0.94"E KLM 16 Alappadu 9o3'46.57"N 76o29'49.83"E KLM 17 Srayikkad 9o5'42.87"N 76o28'58.69"E KLM 18 Pancharathopp 9o7'17.98"N 76o28'13.07"E 3) Alleppey Alleppey is one among the most established coastal district of Kerala, holding a total area of 1,414 sq.km. There is no reserved forest in the district. The major physiographic units in the district are low land (coastal plain) and mid land. The land 199 use pattern shows built up lands, agriculture lands, water bodies and waste lands of which agriculture land constitutes the major share. There are 4 distinct soil types; coastal alluvium, riverine alluvium, brown hydromorphic soil and lateritic soil. Geological formations like sub-recent laterites and tertiary sediments are distributed along the south east part of the district. The district experiences both tropical humid climate and imperious summer with intermittent seasonal rainfall. The average rainfall accounts for about 2965.4 mm. The mean annual maximum temperature and humidity experienced in the district are 30.7ºC and 87% respectively (CGWB 2013). Table 3.3. Details of study area falling in Alleppey district Location ID. Location Name Latitude Longitude ALP 1 Valiyazheekkal 1 9o8'21.64"N 76o27'44.51"E ALP 2 Valiyazheekkal 2 9o8'14.5"N 76o27'45.9"E ALP 3 Tharayilkkadav 9o9'14.82"N 76o27'20.44"E ALP 4 Arattupuzha 9o10'13.98"N 76o27'26.56"E ALP 5 Kandallur 9o9'53.80"N 76o27'48.76"E ALP 6 Manivelikkadav 9o8'56.44"N 76o28'6.58"E ALP 7 Muthukulam 9o12'7.06"N 76o26'32.30"E ALP 8 Mahadevikaad 9o14'52.17"N 76o25'23.89"E ALP 9 Pulikkeril 9 o16'32.46"N 76o24'17.97"E ALP 10 Kumarakodi 9o18'2.05"N 76o23'45.86"E ALP 11 Thottappally 9o18'41.89"N 76o23'2.21"E ALP 12 Purakkad 9o19'19.60"N 76o23'16.82"E ALP 13 Kannattakkadav 9o21'23.18"N 76o22'57.85"E ALP 14 Ottamasseri 9o42'25.96"N 76o17'27.31"E ALP 15 Arattuvazhi 9o43'39.50"N 76o17'19.41"E ALP 16 Andakaranazhi 9o44'29.21"N 76o17'14.90"E ALP 17 Pattanakkadu 9o44'48.69"N 76o17'8.08"E ALP 18 Kuthuthodu 9o46'36.11"N 76o17'11.59"E 4) Ernakulam Ernakulam district is spanning to an area of 3068 Sq. km. The total area can be divided into three distinct units, namely high land, midland and coastal plain. The major soil types of the district are coastal alluvium, riverine alluvium, brown hydromorphic soil and lateritic soil in which lateritic soil covers the major area. The land use pattern of the district comprises of forests, cultivable land, waste land, uncultivable land and cultivable waste land in which cultivable land constitute the 200 major part followed by forests. The district experiences a wet monsoon type climate with substantial raining during north east and southwest monsoon seasons. The normal average annual rainfall obtained in the district is 3359.2 mm. The annual mean values of climatological attributes like maximum temperature and humidity experienced in the districts are 31.4ºC and 88% respectively (CGWB 2013). Table 3.4. Details of study area falling in Ernakulam district Location ID. Location Name Latitude Longitude EKM 1 Kumbalangi 9o52'26.20"N 76o17'31.22"E EKM 2 Illikkal 9o52'59.54"N 76o17'24.48"E EKM 3 Padasekharam road 9o53'47.59"N 76 o17'12.84"E EKM 4 Vyasapuram 9o55'31.61"N 76o16'45.67"E EKM 5 Marambally 9o55'43.79"N 76o16'20.81"E EKM 6 Ponnarimangalam 10o0'5.07"N 76o15'38.24"E EKM 7 Mulavukadu 10o0'41.78"N 76o15'25.50"E EKM 8 Moolambilli 10o2'24.55"N 76o15'33.25"E EKM 9 Kothad Island 10o2'59.78"N 76o16'17.91"E EKM10 Chathanad 10o4'31.47"N 76o14'22.60"E EKM 11 Palliyakkal 10o5'17.94"N 76o14'5.69"E EKM 12 Kadakkara 10o6'8.68"N 76o13'23.13"E EKM 13 Karuthala west 10o8'34.86"N 76o11'7.58"E EKM 14 Pallippuram 10o9'4.50"N 76o10'55.29"E EKM 15 Cherai 10o9'13.47"N 76o10'49.84"E EKM 16 Mosco road 10o9'42.79"N 76o10'32.37"E EKM 17 Munambam 10o10'42.31"N 76o10'11.44"E EKM 18 Munambam-pallippuram 10o10'14.81"N 76o10'11.47"E 5) Thrissur Thrissur district is located in the central part of Kerala with a total geographic area of 3032 Sq. km, representing 7% of the total area of the state. The geomorphologic categorization include low land (coastal planes and Kole land), mid land and high land. The major soil is of lateritic type. Other types such as brown hydromorphic, river alluvium, coastal soil and forest loam are also present. Archaean crystalline formation, tertiary formation, sub-recent laterite and recent riverine alluvium are the important geological formations within the terrain. The climatic pattern comprises of 4 definite seasons including hot summer, cool winter, northeast and southwest 201 monsoon. The mean annual rainfall experienced in the district is 3198.133 mm. The annual mean maximum atmospheric temperature and relative humidity in the district are 36.2 oC and 93% respectively (CGWB 2013). Table 3.5. Details of study area falling in Thrissur district Location ID. Location Name Latitude Longitude TSR 1 Poochakkadav 10o11'17.22"N 76 o 10'2.27"E TSR 2 Azheekkode 10 o 11'37.95"N 76 o 9'56.98"E TSR 3 Marthoma Nagar 10 o 11'26.15"N 76 o 10'41.20"E TSR 4 Methala 10 o 11'39.11"N 76 o 10'54.53"E TSR 5 Idamukk 10 o 11'41.74"N 76 o 11'26.50"E TSR 6 Kuzhivathkadav 10 o 14'11.44"N 76 o 12'5.63"E TSR 7 Vayalar 10 o 14'30.65"N 76 o 11'58.13"E TSR 8 Ala-Gothuruth 10 o 15'3.93"N 76 o 11'31.99"E TSR 9 Veluthakadav 10 o 15'2.21"N 76o10'47.31"E TSR 10 Muttichur kadav 10 o 26'32.25"N 76o6'3.49"E TSR 11 Meenkadav 10 o 29'59.78"N 76o4'26.16"E TSR 12 Orumanayur 10 o 34'7.13"N 76o2'6.36"E TSR 13 Ayodyanagar 10 o 33'44.09"N 76o2'21.65"E TSR 14 Kundukadav 10 o 33'16.46"N 76o2'35.67"E TSR 15 Moonnamkall 10 o 32'23.08"N 76o2'51.89"E TSR 16 Chiplimad 10 o 31'20.39"N 76o2'17.90"E TSR 17 Banglamkadav 10 o 30'59.68"N 76o2'29.63"E TSR 18 Pulikkakadav 10 o 31'20.83"N 76o3'57.79"E 6) Malappuram Malappuram district constitutes 9.13 % of the total area of the state of Kerala and has a total cover of 3550 sq.km. Three physiographic units of the districts are low land, mid land and high land, of which mid land constitutes the major area. The important soil types are laterite, brown hydromorphic, coastal and river alluvium and forest loam. The climate of the district is generally humid with definite dry or wet seasons, with adequate rainfall in the northeast and southwest monsoon seasons. Normal annual average rainfall is 2793.3 mm. Annual average values of climatological attributes like maximum temperature and relative humidity experienced in the districts are 31.8 oC and 92% respectively (CGWB 2013). 202 Table 3.6. Details of study area falling in Malappuram district Location ID. Location Name Latitude Longitude MPM1 Pariyapuram 1 11o0'30.611"N 75o51'58.367"E MPM2 Pariyapuram 2 11o0'39.587"N 75o51'56.063"E MPM3 Pariyapuram 3 11o0'33.348"N 75o51'49.320"E MPM4 Pariyapuram 4 11o0'44.099"N 75o51'54.785"E MPM5 Poorappuzha Bridge 11o1'2.322"N 75o52'10.319"E MPM6 Mangalam Bridge 10o50'39.726"N 75o54'22.5"E MPM7 Koottayi 10o50'35.520"N 75o54'19.343"E MPM8 Purathur 10o48'21.192"N 75o55'6.000"E MPM9 Murikkummadu 10o48'13.902"N 75o55'3.965"E MPM10 Purathur boat jetty 10o48'7.266"N 75o55'8.867"E MPM11 Chamravattom Kadav 10o49'1.2"N 75o57'14.3994"E MPM12 Puthuponnani Bridge East 10o44'24"N 75o56'23.9994"E MPM13 Puthuponnani Bridge west 10o44'31.2"N 75o56'16.8"E MPM14 Puthuponnani Munambam 10o43'58.8"N 75o56'13.1994"E MPM15 Thayyilakkadavu 11o5'28.530"N 75o52'29.639"E MPM16 Olipram kadavu 11o7'41.651"N 75o51'50.981"E MPM17 Kottakkadavu 11o8'15.594"N 75o50'27.930"E MPM18 Kottappadi 11o8'18.942"N 75o50'29.969"E 7) Kozhikode Kozhikode district has a total geographical area of 2344 sq.km. The physiographic units of the districts are low land that stretches along the coastal plane, mid land with rolling or undulating terrain and high land. The important soil types of the district are alluvial, laterite and forest loam. The most common soil is of lateritic type and is distributed mainly along the mid lands. The district experiences tropical monsoon climate with 4 distinct seasons. Tropical rainfall of both southwest and northeast monsoon is contributing to an average annual rainfall of 3698 mm. The average annual maximum temperature and humidity experienced in the district are 30.5 oC and 91% respectively (CGWB 2013). 203 Table 3.7. Details of study area falling in Kozhikode district Location ID. Location Name Latitude Longitude KKD 1 Chaliyam 11o9'39.743"N 75o48'33.473"E KKD 2 Beypore 11o10'4.745"N 75o48'31.067"E KKD 3 Chalappuram 11o14'19.494"N 75o47'36.180"E KKD 4 Thekkeppuram 11o14'2.154"N 75o46'55.643"E KKD 5 Elathur 11o21'14.195"N 75o44'27.701"E KKD 6 Korappuzha 11o21'21.456"N 75o44'28.853"E KKD 7 Puthiyottilkadavu 11o20'57.887"N 75o44'45.071"E KKD 8 Venkalam 11o21'54.984"N 75o44'53.748"E KKD 9 Kooniyil kadavu 11o23'3.216"N 75o44'36.150"E KKD 10 Aanappara 11o22'20.910"N 75o44'48.186"E KKD 11 Cheliya 11o25'31.427"N 75o44'12.443"E KKD 12 Nelliyadikadavu 11o29'0.258"N 75o41'23.171"E KKD 13 Puthuppanam 11o34'14.274"N 75o35'46.596"E KKD 14 Kuttiyammal 11o34'47.297"N 75o35'23.856"E KKD 15 Puramkara 11o35'16.854"N 75o35'3.413"E KKD 16 Mooradu 11o33'49.446"N 75o36'35.615"E KKD 17 Kottakkal 11o34'7.625"N 75o35'34.824"E KKD 18 Iringal 11o33'55.229"N 75o35'56.988"E 8) Kannur Kannur district has a total areal extent of 2966 sq.km. Physiographically, the district has low lands, mid land with undulating terrain of laterite formation and high lands with rugged terrains. The major soil types in the districts are laterite, brown hydromorphic, coastal and river alluvium and forest loam. There are several geological formations like gneiss, schist, charnockite and coastal alluvium. The district experiences a wet climate with heavy rainfall in the southwest and northeast monsoon. The average annual rainfall, maximum temperature and relative humidity experienced in the district are 3438 mm, 23.9 oC and 88 % respectively (CGWB 2013). 204 Table 3.8. Details of study area falling in Kannur district Location Location Name Latitude Longitude ID. KNR1 Kavumbhagom 11o45'37.28"N 75o29'23.64"E KNR2 Thiruvangad 11o45'55.24"N 75o29'20.54"E KNR3 Nettur 11o46'5.25"N 75o29'0.24"E KNR4 Koduvalli 11o45'57.46"N 75o28'33.07"E KNR5 Meenthalapeedika 11o46'4.55"N 75o28'14.33"E KNR6 Moythupaalam 11o46'43.60"N 75o27'40.14"E KNR7 Mundambalam 11o47'38.56"N 75o27'33.03"E KNR8 Kulamkadav 11o48'14.44"N 75o27'31.20"E KNR9 Valapattanam 11o55'39.19"N 75o21'33.58"E KNR10 Keeriyad 11o55'45.99"N 75o21'17.15"E KNR11 Kadavath 11o55'50.11"N 75o21'5.86"E KNR12 Port road 11o55'47.26"N 75o19'44.15"E KNR13 Kappakkadav 11o56'22.28"N 75o19'19.88"E KNR14 Iranav 11o57'25.91"N 75o18'55.39"E KNR15 Mattool south 11o57'28.57"N 75*17'57.81"E KNR16 Aaruthengu 11o58'39.52"N 75*17'8.44"E KNR17 Sidhikkabad 11o58'54.84"N 75*17'1.96"E KNR18 Badikkad 12o0'31.99"N 75*15'44.39"E 9) Kasaragod Kasaragod is the northernmost district of Kerala with a geographical area of 1992 sq.km. The three distinct physiographic units of the districts are coastal plains, midland and high land. The midlands contain rugged terrain with lateritic, colluvium and alluvium deposits. Lateritic, brown hydromorphic, alluvial and forest loam are important soil types of the district of which lateritic soil have a wider coverage. The climate in the district is that of typical Kerala with heavy rain in the monsoon. The average annual rainfall experienced in the district is 3500 mm. Climatological attributes like maximum temperature and relative humidity has annual average values of 31.3 oC and 90% respectively (CGWB 2013). 205 Table 3.9. Details of study area falling in Kasaragod district Location Location Name Latitude Longitude ID. KSD1 Udumbumthala 12o6'21.19"N 75o10'25.15"E KSD2 Mothakkadav 12o6'30.52"N 75o10'23.43"E KSD3 Kaikkottukadav 12o6'58.20"N 75o10'17.29"E KSD4 Vellapp 12o7'56.42"N 75o9'53.16"E KSD5 Idayilekkadu Island 12o8'24.82"N 75o8'58.04"E KSD6 Ayittikkadav 12o8'55.04"N 75o9'15.64"E KSD7 Thekkekkadu 12o10'14.16"N 75o8'48.43"E KSD8 Padanna kadappuram 12o10'5.58"N 75o8'36.02"E KSD9 Mattummal 12o10'37.50"N 75o8'35.03"E KSD10 Ori 12o11'11.01"N 75o8'16.30"E KSD11 Ori kadav 12o11'51.22"N 75o7'54.01"E KSD12 Orkkalam 12o13'5.55"N 75o7'12.16"E KSD13 Madakkara,Thuruthi 12o13'8.13"N 75o7'52.04"E KSD14 Orcha 12o14'47.35"N 75o7'13.33"E KSD15 Chithari 12o22'4.00"N 75o3'32.60"E KSD16 Kappil 12o25'37.16"N 75o0'51.97"E KSD17 Keeyoor Kadavath 12o28'20.47"N 75o0'8.93"E KSD18 Chemanad 12o29'56.58"N 74o59'58.24"E Collection of both water and sediment samples were carried out from all the 163 locations falling in 9 districts. Entire collection was carried out during post monsoon season, which is characteristic in having higher concentration of all elements under target. Also this season is reported to be ideal for the introduction of most of the mangrove species. All the collected samples were subjected to physico-chemical analysis either on spot or in the laboratory, following standard methods (APHA, 2005 and Trivedy et al., 1987). The physico chemical parameters analyzed for water samples include pH, turbidity, total solids, total dissolved solids, total suspended solids, salinity, resistivity, conductivity, acidity, alkalinity, total hardness, magnesium, calcium, chloride, sulphate, sodium, total nitrogen, phosphorous and potassium. Similarly, sediment samples were subjected to the analysis of pH, moisture percentage, textural percentage of sand, silt and clay, organic carbon, total nitrogen, phosphorous, potassium and sodium following standard methods (Trivedy et al., 1987 and Jackson, 1973). Analytical procedures followed for both water and sediment samples are depicted in Chapter 2. 206 The tolerance range of mangrove species towards different physico-chemical parameters have been taken into account for assessing the most significant growth determinants of each mangrove species. The numbers of sites possessing all these attributes or a share were treated as ideal sites for afforestation of respective mangrove species. Based on these, different classes of sites have been described. Sites possessing 0-20% growth sustaining attributes of any mangrove species was treated as A, 21-40 % as B, 41-60% as C, 61-80% as D and 81-100% as E. Sites under category A were treated as non-ideal, B as moderately ideal, C as ideal, D and E are respectively as perfectly ideal and exemplarily ideal for afforestation of mangrove species. Results and Discussion An initiative of mangrove afforestation is yet to make a successful leap in the state of Kerala. The present investigation has been carried out to delineate the sites for species specific mangrove afforestation along the coastal districts of Kerala, which include Trivandrum, Kollam, Alleppey, Ernakulam, Thrissur, Malappuram, Kozhikode, Kannur and Kasaragod, based on hydrogeochemical and sedimentological characteristics. The tolerance range of mangrove species towards different physico-chemical parameters have been taken in to account for assessing the most significant growth determinant of each species. The numbers of sites possessing all or a share of these attributes were treated as ideal sites for the introduction of respective mangrove species. The results on the physico chemical characterization of water and sediment samples from 19 locations (TVM 1 to TVM 19) of Trivandrum district for delineating regions ideal for mangrove introduction are given in Tables 3.10 – 3.11. 207 Table 3.10. Results on the physico-chemical characterization of water samples along different locations in Trivandrum district Sl TVM TVM TVM TVM TVM TVM TVM TVM TVM TVM TVM TVM TVM TVM TVM TVM TVM TVM N Parameters TVM 9 1 2 3 4 5 6 7 8 10 11 12 13 14 15 16 17 18 19 o 1 pH 9.55 8.74 6.84 7.36 9.14 9.29 8.16 8.82 7.59 8.11 7.88 7.26 8.05 7.53 8.69 8.77 8.98 7.91 8.81 Turbidity 2 0 0.1 0.2 0.1 0.2 0.2 0.1 0.1 0.1 0 0 0 0 0 0 0.1 0.1 0.1 0.1 (NTU) 1394 3 T.S (mg/l) 860 660 840 900 900 980 840 680 860 4160 5660 11100 6920 6660 15520 9320 7840 8260 0 4 T.D.S (ppt) 0.3151 0.0697 0.0979 0.2256 0.1964 0.2452 0.1527 0.2378 0.2285 2.327 3.594 7.04 4.458 4.244 10.56 9.597 8.955 4.818 5.039 5 T.S.S (mg/l) 544.9 590.3 742.1 674.4 703.6 734.8 687.3 442.2 631.5 1833 2066 4060 2462 2416 4960 4343 365 3022 3221 6 Acidity (mg/l) 26.4 8.8 13.2 30.8 13.2 13.2 17.6 13.2 19.8 13.2 8.8 13.2 17.6 13.2 11 11 8.8 8.8 8.8 7 Salinity(ppt) 0.309 0.071 0.097 0.221 0.192 0.24 0.15 0.225 0.233 2.508 3.95 8.316 5.081 4.809 12.69 11.45 10.24 5.484 5.748 Conductivity(m 8 0.615 0.1362 0.1912 0.4401 0.3837 0.4794 0.2991 0.4641 0.4491 4.549 7.026 13.74 8.714 8.31 20.63 18.8 16.9 9.418 9.866 S) Resistivity 9 1590 7178 5108 2221 2548 2039 3270 2104 2173 214.6 139.3 71.15 112.2 117.8 47.31 52.04 57.78 103.6 99.19 (Ω) Alkalinity 10 190 90 60 130 100 110 100 90 110 120 80 120 100 90 150 110 160 80 90 (mg/l) Hardness 11 28 8 20 20 26 22 16 8 20 60 76 164 100 96 228 210 134 110 112 (mg/l) 12 Calcium(mg/l) 5.607 5.607 5.607 4.806 6.408 5.607 4.005 4.005 4.806 8.01 5.607 12.816 9.612 9.612 18.423 16.02 12.015 8.811 8.811 Magnesium 41.38 13 3.409 0.974 1.461 1.948 2.435 1.948 1.461 1.948 1.948 9.739 15.095 32.137 18.503 17.529 44.311 25.32 21.425 21.912 (mg/l) 9 Chloride 14 362.1 305.3 355 312.4 355 404.7 347.9 284 369.2 1846 2655.4 5041 1966.7 2896.8 6177 6958 3180.8 3550 3805.6 (mg/l) Sulphate 15 10 2 0.1 5.5 2.3 1 3 3 4.8 15.5 63 65.5 134 119 122 156 155 137 127 (mg/l) 16 Sodium (ppt) 4.56 0.0274 0.0071 0.1505 0.0867 0.1295 0.0403 0.0448 0.1172 1.78 1.48 6.625 3.585 2.49 7.37 6.72 5.635 3.21 3585 Potassium 333.48 269.00 253.99 152.99 194.01 178.99 226.50 231.51 175.4.8 328.51 315.49 288.98 301.50 310.49 611.01 613.0 563.50 307.99 305.48 17 (mg/l) 4 8 4 8 4 9 6 1 1 8 8 8 0 3 6 1 9 1 8 Phosphorous 18 87.5 28.5 165.0 112.0 69.0 52.0 12.5 142.0 26.5 59.0 60.5 15.0 145.0 99.5 122.5 23.5 21.0 4.0 35.0 (mg/l) 19 Nitrogen (mg/l) 49 42 35 42 28 35 42 42 56 42 42 42 28 35 42 35 49 42 42 208 Table 3.11. Results on the physico-chemical characterization of sediment samples along different locations in Trivandrum district Sl TVM TVM TVM TVM TVM TVM TVM TVM TVM TVM TVM TVM TVM TVM TVM TVM TVM TVM TVM Parameters No 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 1 pH 4.78 6.75 4.28 3.94 4.98 5.68 6.06 5.71 7.33 6.09 5.7 4.57 3.19 3.75 6.47 3.77 8.48 6.54 5.14 2 Moisture % 6.8 8.2 9 12.6 8.3 5.5 1.8 21 5.8 3.8 15.8 7.5 9.8 5.5 6.3 16.5 12.3 5.9 6.9 3 Sand % 96.3 73.2 84.1 79.0 94.0 90.2 92.1 91.1 87.3 99.7 93.1 85.7 94.1 90.8 90.4 92.6 90.2 90.3 73.8 4 Silt % 0.1 0.2 0.2 0.3 01 01 0.1 0.1 0.1 0.1 0.1 0.2 0.1 0.1 0.2 0.1 0.1 0.1 0.5 5 Clay % 3.6 26.6 15.7 20.7 5.9 9.7 7.8 8.8 12.6 0.2 6.8 14.1 5.8 9.1 9.4 7.3 9.7 9.6 25.7 Organic carbon 6 8.0 10.0 18.5 23.45 23.5 76.0 38.0 90.0 16.5 25.0 38.0 18.0 27.0 19.5 18.5 24.5 73.5 8.0 7.5 (g/kg) 7 Nitrogen (mg/kg) 1260 1890 1050 3080 630 350 560 840 2940 5600 490 1750 2450 770 1050 630 420 420 560 Phosphorous 8 54.5 57.0 44.5 55.0 31.5 22.5 19.5 34.5 55.0 16.0 6.0 48.0 30.0 10.5 12.5 13.5 14.0 11.0 17.0 (mg/kg) 9 Potassium(mg/l) 2.502 10.01 10.01 15.01 20.02 12.51 0 10.01 0 10.01 10.01 15.01 7.51 20.02 10.01 15.01 10.01 12.51 2.502 10 Sodium (ppt) 0.045 0.005 0.0675 0.1425 0.0275 0.0175 0.0525 0.0475 0.07 0.1125 0.09 0.45 0.1075 0.1025 0.2525 0.2925 0.135 0.0775 0.145 209 Upon analyzing the growth requirements of mangrove species with those of site characteristics, sites noted to be ideal (Plate 3.1) for mangrove afforestation in Thiruvananthapuram district were Manamel (TVM 3) for Excoecaria agallocha and Sonneratia alba, Panathura (TVM 4) and Kundavila (TVM 11) for Avicennia officinalis and Murukkumpuzha Kadavu (TVM 12) for E. agallocha and Rhizophora mucronata. Locations noted to be moderately ideal were Edayar (TVM 1) for Bruguiera cylindrica; Munnattumukku (TVM 2) and Thazhampally (TVM 17) for A. officinalis, B. cylindrica and E. agallocha; Manamel, Kayikkara kadavu (TVM 10) and Kottaram thuruth (TVM 16) for A. officinalis, B. cylindrica and R. mucronata; Panathura for E. agallocha, R. mucronata and S. alba; Thottumukku (TVM 6) for E. agallocha; Madhavapuram (TVM 9) for B. cylindrica and S. alba; Kundavila for B. cylindrica and R. mucronata; Murukkumpuzha Kadavu for A. officinalis, B. cylindrica and S. alba; Kadinamkulam (TVM 13) for A. officinalis;. Vadakkevila (TVM 14) for A. officinalis, E. agallocha and R. mucronata; Perumathura (TVM 15) for B. cylindrica; Anchuthengu (TVM 18) for A. officinalis and E. agallocha and Chambavu (TVM 19) for A. officinalis, R. mucronata and S. alba. The results on the physico-chemical characteristics of water / sediment samples from 18 locations of Kollam district are depicted in Tables 3.12-3.13. 210 Table 3.12. Results on the physico-chemical characterization of water samples along different locations in Kollam district Sl KLM KLM KLM KLM KLM KLM Parameters KLM 1 KLM 2 KLM 3 KLM 4 KLM 5 KLM 6 KLM 7 KLM 8 KLM 9 KLM 10 KLM 11 KLM 18 No: 12 13 14 15 16 17 1 pH 8.21 8.27 8.1 7.93 8.02 8.64 7.73 10.19 9.27 8.51 8.57 9.16 7.6 7.38 7.6 7.33 8.46 8.27 2 Turbidity(NTU) 0 0 0.1 0 0 0 0.1 0.3 0 0 0 0.1 0 0.1 0 0 0 0.1 3 T.S (mg/l) 15200 3200 8200 10600 11600 6600 1600 8400 8400 24200 20200 4000 400 600 3000 2800 8400 21800 4 T.D.S (ppt) 11.57 2.422 6.221 8.376 6.557 4.995 0.9032 6.384 6.582 17.42 15.09 3.339 0.3249 0.3588 2.691 1.976 6.739 15.9 5 T.S.S (mg/l) 3630 778 1979 2224 5043 1605 696.8 2016 1818 6780 5110 661 75.1 241.2 309 824 1661 5900 6 Acidity (mg/l) 17.6 6.6 8.8 11 11 17.6 22 15.4 13.2 17.6 8.8 8.8 8.8 8.8 13.2 8.8 17.6 17.6 7 Salinity(ppt) 14.05 2.608 7.16 9.882 7.564 5.647 0.9321 7.362 7.626 22.38 19.12 3.727 0.3225 0.3509 2.904 2.093 7.821 19.94 8 Conductivity(mS) 22.64 4.735 12.16 16.37 12.82 9.766 1.766 12.47 12.83 34.05 29.49 6.533 0.6353 0.7002 5.27 3.863 13.18 31.09 9 Resistivity(Ω) 43.19 206.3 80.47 59.72 76.34 100.1 553.6 78.44 75.8 28.75 33.16 149.7 1519 1396 185.5 253.2 74.19 31.43 10 Alkalinity (mg/l) 140 100 70 90 80 120 110 160 140 180 150 140 70 70 90 80 110 140 11 Hardness(mg/l) 262 50 134 188 142 114 30 142 140 390 336 82 12 30 60 48 142 350 12 Calcium(mg/l) 20.025 4.806 9.612 13.617 10.413 8.01 4.806 12.015 12.015 25.632 24.03 9.612 4.806 4.806 6.408 4.806 9.612 24.831 13 Magnesium(mg/l) 51.615 9.252 26.781 37.494 28.242 22.886 4.382 27.268 26.781 79.37 67.196 14.121 0 4.382 10.712 8.765 28.729 70.118 14 Chloride(mg/l) 8108.2 1760.8 4473 5964 4671.8 3521.6 695.8 4657.6 4813.8 13646.2 8406.4 2229.4 340.8 369.2 2002.2 1320.6 3422.2 10735.2 15 Sulphate(mg/l) 180 98 180 180 180 159 31 174 153 180 180 97 22 8 94 151 138 170 16 Sodium (ppt) 13.15 0.42 1.5 3.26 2.14 2.18 3.385 5.66 2.24 19.8 14.25 1.005 4.235 9.92 5.26 6.82 1.05 15.05 298.02 681.98 672.01 641.98 17 Potassium(mg/l) 578.015 323.513 641.983 632.9.9 636.001 637.995 333.484 636.001 331.011 575.98 318.00 338.49 662.02 556.26 0 2 2 3 18 Phosphorous(mg/l) 45.0 50.0 8.0 40.0 95.0 10.0 90.0 950.0 450.0 6.0 3.0 5.0 3.0 1500 5.0 5.0 3.0 40.0 19 Nitrogen (mg/l) 42 42 35 35 42 35 42 35 49 28 35 35 35 42 42 28 28 42 Table 3.13. Results on the physico-chemical characterization of sediment samples along different locations in Kollam district Sl KLM KLM KLM KLM KLM KLM KLM Parameters KLM 1 KLM 2 KLM 3 KLM 4 KLM 5 KLM 6 KLM 7 KLM 8 KLM 11 KLM 13 KLM 18 No: 9 10 12 14 15 16 17 1 pH 4.2 4.33 5.53 8.71 8.3 7.59 3.39 6.31 4.72 8.85 6.94 7.12 4.01 7.63 7.61 6.41 7.05 3.85 2 Moisture % 8.5 9.6 12.3 15.5 5.2 3.8 8.7 5.3 11.5 8.8 7.7 6.85 7.55 12.5 8.8 6.3 7.5 5.2 3 Sand % 87.0 92.3 93.3 87.7 97.7 64.4 97.7 89.7 85.1 85.2 80.0 93.4 69.8 70.1 88.3 56.3 97.6 86.2 4 Silt % 0.1 0.1 0.1 0.1 0.2 0.2 0.1 0.1 0.3 0.3 0.3 0.1 0.1 0.1 0.1 0.1 0.2 0.1 5 Clay % 12.9 7.6 6.6 12.2 2.1 35.4 2.2 10.2 14.8 14.7 19.7 6.5 30.1 29.8 11.6 43.6 2.2 13.7 6 Organic carbon (g/kg) 73 53.5 2.5 78 5 25 4 12 63.5 39 10.5 3.5 8.5 12 11 15 13.5 15 7 Nitrogen (mg/kg) 1540 630 560 420 560 630 1470 770 1610 910 490 490 560 490 630 420 420 560 8 Phosphorous (mg/kg) 26 12.5 18 31.5 14.5 34 41 57.5 72 26 43.5 9.5 19.5 30.5 26.8 35 28 38.5 9 Potassium(mg/kg) 22.48 24.99 20.02 17.52 17.52 5.01 10.01 0 15.01 7.51 7.51 17.52 12.51 7.51 2.50 195.89 0 15.01 0.232 10 Sodium (ppt) 0.2725 0.0875 0.0525 0.0625 0.14 0.27 0.19 0.2875 0.45 0.5325 0.3875 0.045 0.1 0.45 0.185 0.1475 0.4025 5 211 In Kollam district, KLM 9 (Kochuthoppu) and KLM 16 (Alappadu) were noted to be ideal for afforestation of Avicennia officinalis. KLM 8 (Sasthamthodi) was noted to be ideal for Bruguiera cylindrica and KLM18 (Pancharathopp) for Excoecaria agallocha. Also, the other ideal sites for afforestation were KLM 9 (Neeravil) for A. officinalis and E. agallocha and KLM 10 (Madathilkayalvaaram) for B. cylindrica and Rhizophora mucronata (Plate 3.2) The moderately ideal sites for afforestation were Kappil (KLM 1) for Avicennia officinalis, Bruguiera cylindrica, Excoecaria agallocha and Rhizophora mucronata; Edava (KLM 2) for B. cylindrica, E. agallocha, R. mucronata and Sonneratia alba; Pozhikkara (KLM 4) and Cheriyazheekkal (KLM 15) for A. officinalis and B. cylindrica; Adhichamamthoppu (KLM 7) and Ponmana (KLM 12) for B. cylindrica, E. agallocha and R. mucronata; Madathilkayalvaaram for A. officinalis, E. agallocha and S. alba; Sasthamthodi for R. mucronata ; Neeravil for B. cylindrica and R. mucronata; Kochochira (KLM 17) for A. officinalis and E. agallocha; Alappadu for A. officinalis and Srayikkad (KLM 17) for R. mucronata. 18 study sites were selected in Alleppey district for assessing the possibility of mangrove afforestation. The physico-chemical characteristics of water and sediment samples worked out in this regard are depicted in Tables 3.14 - 3.15. 212 Table 3.14. Results on the physico-chemical characterization of water samples along different locations in Alleppey district Sl ALP ALP ALP ALP ALP ALP ALP ALP ALP ALP Parameters ALP 2 ALP 4 ALP 6 ALP 8 ALP 9 ALP 12 ALP 14 ALP 15 No: 1 3 5 7 10 11 13 16 17 18 1 pH 8.26 8.16 8.64 8.6 8.19 8.09 7.2 7 6.65 6.62 7.23 6.62 6.47 7.8 8.2 7.15 7.79 7.23 Turbidity 2 0.1 0.5 0 1.2 0 0 0 0 0 0 0 0 0 0 0 0.1 0 0.1 (NTU) 3 T.S (mg/l) 24800 26000 24600 12000 19400 16000 7000 6400 600 600 5000 400 800 6800 11000 9800 12200 18600 4 T.D.S (ppt) 17.3 17.46 16.56 9.073 13.49 11.52 5.277 4.796 0.5544 0.3697 3.945 0.3865 0.7843 5.336 8.172 6.869 9.207 13.39 5 T.S.S (mg/l) 7500 8540 8040 2927 5910 4480 1723 1604 45.6 230.3 1055 13.5 15.7 1464 2828 2931 2993 5210 6 Salinity(ppt) 21.88 22.1 20.81 10.78 16.92 13.98 6.004 5.495 0.55 0.3625 4.374 0.3794 0.7912 6.177 9.593 7.951 10.96 16.46 7 Resistivity(Ω) 28.93 28.63 30.18 55.22 37.04 43.51 94.8 104.3 901.9 1352 126.7 1294 637.5 93.52 61.22 72.79 54.25 37.35 Conductivity 8 33.82 34.12 32.42 17.72 26.39 22.52 10.32 9.373 1.084 0.7241 7.712 0.7556 1.533 10.43 15.98 13.43 18 26.18 (mS) 9 Acidity (mg/l) 17.6 17.6 13.2 30.8 22 13.2 8.8 17.6 13.2 13.2 13.2 13.2 17.6 30.8 26.4 48.4 26.4 30.8 10 Alkalinity (mg/l) 150 190 170 330 100 110 100 100 60 70 120 80 60 200 210 200 210 160 11 Hardness(mg/l) 420 432 400 200 308 258 115 110 16 16 92 16 25 128 178 164 204 306 12 Calcium(mg/l) 28.035 28.836 27.234 15.219 20.025 19.224 8.01 8.811 4.806 4.005 7.209 4.005 5.607 13.617 14.418 12.816 18.423 20.826 13 Magnesium(mg/l) 85.213 87.647 80.83 39.441 62.814 51.128 23.129 21.425 0.974 1.461 18.016 1.461 2.678 22.886 34.572 32.137 38.467 61.84 12297. 14 Chloride(mg/l) 14413 10408.6 7810 9883.2 9528.2 5168.8 3280.2 568 454.4 2840 1533.6 695.8 3692 8292.8 4842.2 6645.6 9641.8 2 15 Sulphate(mg/l) 180 177 153 131 152 148 127 118 21.5 9 102 16.5 31 120 136 131 138 145 16 Nitrogen (mg/l) 42 28 35 42 42 28 28 28 28 35 28 28 28 35 28 28 28 35 Phosphorous 17 2.0 52 5.0 54 4.5 4.5 2.0 2.5 2.0 2.0 0.4 13.5 1.0 51.5 49.0 57.0 28.5 31.5 (mg/l) Potassium 335.9. 18 585.99 573.0 681.98 627.9 591.00 625.99 646.99 657.00 677.02 681.98 314.01 338.49 662.00 283.01 290.51 651.99 590.99 (mg/l) 9 19 Sodium (ppt) 12.47 13.35 9.57 4.26 12.07 5.41 0.54 1.81 9.42 9.92 2.33 4.41 3.735 4.46 7.725 6.335 0.57 11.17 213 Table 3.15. Results on the physico-chemical characterization of sediment samples along different locations in Alleppey district Sl ALP ALP ALP ALP ALP ALP ALP ALP ALP ALP ALP ALP ALP Parameters ALP 2 ALP 9 ALP 11 ALP 14 ALP 15 No: 1 3 4 5 6 7 8 10 12 13 16 17 18 1 pH 9.02 7.85 3.84 7.89 7.81 8.47 5.95 8.49 5.58 5.98 9.02 5.54 5.96 8.49 9.05 8.53 8.23 7.54 2 Moisture % 3.2 16.5 9.5 21.5 13.8 8.8 6.3 3.2 4.6 15.2 3.5 1.55 6.6 11.6 2.3 9.8 6.5 2.3 3 Sand % 87.0 87.4 96.2 89.3 89.1 84.4 97.3 87.1 78.6 46.6 96.0 71.2 78.0 96.5 92.4 73.9 91.1 84.0 4 Silt % 0.2 0.5 0.2 0.2 0.3 0.2 0.1 0.3 0.1 0.2 0.1 0.2 0.2 0.1 0.2 0.2 0.3 0.6 5 Clay % 12.8 12.1 3.6 10.5 10.6 15.4 2.6 12.6 21.3 53.2 3.9 28.6 21.8 3.4 7.4 25.9 8.6 15.4 Organic carbon 6 1.9 88 9.8 94 9.0 1.4 2.8 0.04 0.13 328.7 30.0 0.5 23.7 4.25 0.96 10.5 27.0 0.22 (g/kg) Nitrogen 7 420 1890 910 1750 490 490 490 560 910 2730 420 1890 1750 560 770 700 2170 1680 (mg/kg) Phosphorous 8 19.5 94.5 43.0 93.5 22.5 19.0 14.5 12.0 21.5 45.5 21.5 59.5 58.0 74.5 29.5 86.0 55.0 62.0 ( mg/kg ) Potassium 9 10.01 87.51 7.51 55.01 20.02 17.52 0 2.50 2.50 7.51 0 0 0 47.51 2.50 32.49 15.01 12.51 (mg/kg) 10 Sodium (ppt) 0.5625 1.04 0.585 0.6225 0.46 0.675 0.2575 0.2625 0.235 0.27 0.2925 0.25 0.275 0.34 0.3075 0.5775 0.4575 0.5025 214 In Alleppey district, the ideal sites for afforestation of different mangrove species were ALP 8 (Mahadevikaad), ALP 11 (Thottappally) and ALP 14 (Ottamasseri) for Rhizophora mucronata; ALP 13 (Kannattakkadav) for Sonneratia alba; ALP 16 (Andakaranazhi) and ALP 17 (Pattanakkadu) for Avicennia officinalis and ALP 18 (Kuthuthodu) for A. officinalis, Excoecaria agallocha and Bruguiera cylindrica (Plate 3.3). Moderately ideal sites for afforestation were noted to be Manivelikkadav (ALP 6) and Kannattakkadav for Avicennia officinalis and Bruguiera cylindrica; Valiyazheekkal 1 (ALP 1) for Rhizophora mucronata; Valiyazheekkal 2 (ALP 2) for A. officinalis; Arattupuzha (ALP 4), Kandallur (ALP 5), Mahadevikaad and Thottappally for Excoecaria agallocha and A. officinalis; Tharayilkkadav (ALP 3) and Kuthuthodu for R. mucronata; Pulikkeril (ALP 9) for A. officinalis; Arattuvazhi (ALP 15) and Andakaranazhi () for B. cylindrica; Ottamasseri for E. agallocha and Pattanakkadu (ALP 17) for R. mucronata. Considering Ernakulam district, 18 sites were selected and the results on the physico-chemical characterization of both water and sediment samples are depicted in Tables 3.16 – 3.17. 215 Table 3.16. Results on the physico chemical characterization of water samples along different locations in Ernakulam district Sl EKM EKM EKM EKM EKM EKM EKM EKM EKM EKM EKM EKM EKM EKM Parameters EKM 1 EKM 6 EKM 8 EKM 16 No: 2 3 4 5 7 9 10 11 12 13 14 15 17 18 1 pH 7.03 6.69 7.35 7.27 7.27 7.28 7.47 6.98 6.44 6.92 7.25 7.53 7.33 7.95 8.04 7.93 7.71 7.02 2 Turbidity(NTU) 0.1 0.2 0.9 0.5 0.4 0.1 0.2 0.1 0.1 0.1 0.1 0.1 0.1 0 0 0.1 0.2 0.1 3 T.S (mg/l) 5000 5200 7800 6600 5400 9200 7600 2000 800 4600 5200 4800 6400 16000 17600 19400 24800 21600 4 T.D.S (ppt) 3.936 3.111 6.092 5.146 4.464 7.529 6.531 1.687 0.7788 4.002 4.259 4.645 6.226 12.68 12.67 14.8 16.55 17.56 5 T.S.S (mg/l) 1064 2089 1708 1454 936 1671 1069 313 21.2 598 941 155 174 3320 4930 4600 8250 4040 6 Salinity(ppt) 4.372 3.44 6.981 5.891 5.036 8.868 7.605 1.786 0.798 4.505 4.836 5.234 7.166 15.56 15.57 18.54 22.52 20.91 7 Conductivity(mS) 7.694 6.082 11.89 10.06 8.728 14.72 12.74 3.303 1.523 7.82 8.321 9.098 12.17 24.78 24.75 28.94 32.35 34.33 8 Resistivity(Ω) 127 160.7 82.24 97.07 112.3 66.43 76.55 296 642 124.9 117.4 107.5 80.27 39.45 39.5 33.77 30.19 28.5 9 Acidity (mg/l) 17.6 74.8 13.2 48.4 57.2 11 11 11 35.2 13.2 13.2 8.8 17.6 11 13.2 8.8 8.8 26.4 10 Alkalinity (mg/l) 70 110 90 190 230 80 90 70 70 100 120 100 140 130 160 130 120 160 11 Hardness(mg/l) 80 79 141 116 103 168 142 46 26 87 90 103 134 283 284 332 400 378 12 Calcium(mg/l) 8.01 5.607 12.015 9.612 9.612 11.214 12.015 4.806 4.806 8.01 8.01 8.01 10.413 16.821 20.826 23.229 24.03 25.632 13 Magnesium(mg/l) 14.698 15.852 27.025 22.399 19.234 34.085 27.268 8.278 3.409 16.312 17.043 20.208 26.294 58.675 56.484 66.709 82.778 76.448 10337. 12609. 14 Chloride(mg/l) 2840 4160.6 7440.8 3479 3053 5310.8 4515.6 1235.4 681.6 2840 4458.8 3223.4 4245.8 10408.6 12240.4 13376.4 6 6 15 Sulphate(mg/l) 117 98 135 120 114 137 135 67.5 30.5 115 119 123 133 151 151 156 157.5 157.5 16 Sodium (ppt) 3.48 4.21 2.2 0.07 1.96 0.53 0.15 6.97 9.77 2.46 2.51 0.72 0.59 4.41 10.47 12.57 6.57 14.45 641.98 651.99 651.99 651.99 681.98 656.99 656.99 656.99 630.99 620.98 17 Potassium(mg/l) 662.00 662.00 656.99 672.012 656.997 597.995 587.986 575.982 3 3 3 3 2 7 7 7 6 6 Total 18 8.0 45.5 12.5 109.5 140.0 4.0 6.0 0.03 0.03 9.5 3.5 0.03 12.5 14.5 6.0 4.5 6.0 15.0 Phosphorous(mg/l) Total Nitrogen 19 42 28 35 28 35 21 28 28 28 21 21 21 35 21 28 21 28 21 (mg/l) 216 Table 3.17. Results on the physico chemical characterization of sediment samples along different locations in Ernakulam district Sl EKM EKM EKM EKM EKM EKM EKM EKM EKM EKM EKM EKM EKM EKM EKM EKM EK Parameters EKM 1 No: 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 M 18 1 pH 6.44 5.76 5.98 6.4 6.69 8.14 6.95 2.87 2.46 6.05 6.74 6.67 7.58 4.29 8.1 8.03 8.5 8.3 2 Moisture % 5.5 13.2 5.2 21.8 8.6 3.3 5.5 8.3 11.5 5.9 3.2 7.36 5.5 12.3 7.5 9.6 13.6 8.6 3 Sand % 64.3 67.2 68.5 45.9 37.3 86.9 57.6 70.3 70.0 97.5 93.2 78.3 86.2 87.7 94.7 82.1 80.8 92.4 4 Silt % 0.2 0.4 0.3 0.1 0.1 0.1 0.1 0.1 0.1 0.2 0.2 0.2 0.1 0.1 0.2 0.3 0.1 0.1 5 Clay % 35.5 32.4 31.2 54.0 62.6 13.0 42.3 29.6 29.9 2.3 6.6 21.5 13.7 12.2 5.1 17.6 19.1 7.5 Organic carbon 6 235.8 421.6 1.03 511.1 597.8 70.2 183.3 90.7 170 0.37 0.26 51.2 47.2 66.4 28.0 75.0 88.4 41.5 (g/kg) 7 Nitrogen (mg/kg) 2590 2590 1470 2310 2590 840 1540 2310 3290 770 420 2450 1330 770 1470 840 560 420 Total Phosphorous 8 117.5 136 35 130 151 92.0 58.8 80 64 34 31 98.5 83.5 51.0 36.0 46.5 79.0 31.0 (mg/kg) 9 Potassium(mg/kg) 60.61 20.02 62.52 27.49 15.01 60.02 47.51 79.99 77.5 69.99 72.49 39.99 45.00 37.5 60.02 32.49 7.51 57.52 0.317 10 Sodium (ppt) 0.0075 0.185 0.17 0.5475 0.6375 0.1125 0.2275 0.055 0.025 0.005 0.015 0.07 0.145 0.6 0.1375 0.4 0.6625 5 217 The result showed that the ideal sites in Alleppey district for mangrove introduction were EKM 3 (Padasekharam road), EKM 10 (Chathanad) and EKM 11(Palliyakkal) for Rhizophora mucronata; Kumbalangi (EKM 1) for Avicennia officinalis and Karuthala west (EKM 13) for Bruguiera cylindrica (Plate 3.4). Moderately ideal sites towards the afforestation of all the 5 species (Avicennia officinalis, Bruguiera cylindrica, Excoecaria agallocha, Rhizophora mucronata and Sonneratia alba) under study were Ponnarimangalam (EKM 6) and Mosco road (EKM 16). Illikkal (EKM 2), Marambally (EKM 5) and Munambam pallippuram (EKM 18) for 4 species (A. officinalis, B. cylindrica, E. agallocha and R. mucronata); Vyasapuram (EKM 4) and Cherai (EKM 15) moderately ideal for the three species (A. officinalis, B. cylindrica and R. mucronata) have also been reported. The other moderately ideal sites were Padasekharam road and Palliyakkal for A. officinalis, B. cylindrica and E. agallocha; Karuthala west and Pallippuram (EKM 14) for A. officinalis and E. agallocha; Mulavukadu (EKM 7) for R. mucronata; Kothad Island (EKM 9) and Munambam (EKM 17) for A. officinalis; Moolambilli (EKM 8) for R. mucronata; Kadakkara (EKM 12) for B. cylindrica; Chathanad (EKM 10) for B. cylindrica and Kumbalangi (EKM 1) for E. agallocha and S. alba. As far as Thrissur district is concerned, 18 sites were selected and the physic- chemical analysis of water and sediment samples from all the sites were carried out. The results are depicted in Tables 3.18 – 3.19. 218 Table 3.18. Results on the physico-chemical characterization of water samples along different locations in Thrissur district Sl TSR TSR TSR TSR TSR TSR TSR TSR TSR TSR TSR Parameters TSR 5 TSR 6 TSR 7 TSR 8 TSR 9 TSR 16 TSR 17 No: 1 2 3 4 10 11 12 13 14 15 18 1 pH 7.41 7.38 7.02 7.17 7.16 6.62 7.14 7.01 6.93 6.85 7.11 7.13 7.27 7.1 7.7 8.02 7.75 7.61 Turbidity 2 1.2 0.1 1.2 0.2 1.2 0.5 0.9 0.3 0.2 0.2 0.1 0.1 0.1 0.1 0.1 0.6 1.2 0.2 (NTU) 3 T.S (mg/l) 15200 16400 16200 4400 15600 7200 8800 4400 1400 600 5000 13400 16600 18400 23400 39200 42600 18400 4 T.D.S (ppt) 9.675 10.48 10.37 2.642 9.105 4.842 5.807 2.844 1.047 0.1607 3.088 8.863 10.41 12.06 14.87 25.4 25.59 12.49 5 T.S.S (mg/l) 5525 5920 5830 1758 6495 2358 2993 1556 353 439.3 1912 4537 6190 6340 8530 13800 17010 5910 6 Salinity(ppt) 11.68 12.74 12.63 2.875 10.93 5.508 6.684 3.1 1.08 0.1576 3.389 10.64 12.63 14.83 18.72 33.85 34.13 15.37 Conductivity 7 18.92 20.52 20.27 5.164 17.8 9.471 11.36 5.554 2.046 0.3143 6.042 17.32 20.37 23.62 29.07 49.68 50.03 24.41 (mS) Resistivity 8 51.74 47.72 48.26 189.1 55.01 103.4 86.1 176.1 478 3105 161.9 56.29 47.94 41.46 33.58 19.68 19.55 40.06 (Ω) 9 Acidity (mg/l) 8.8 22 17.6 28.6 17.6 41.8 17.6 17.6 13.2 17.6 8.8 17.6 13.2 13.2 13.2 15.4 22 8.8 10 Alkalinity (mg/l) 160 180 150 180 170 120 140 130 115 50 90 100 120 130 120 200 190 130 Hardness 11 215 233 230 70 216 102 130 72 28 14 70 196 227 268 336 580 620 282 (mg/l) Calcium 12 15.219 16.821 15.219 7.209 16.02 9.612 10.413 7.209 4.005 4.806 7.209 14.418 16.02 20.025 23.229 40.851 40.851 19.224 (mg/l) Magnesium 13 43.093 46.502 46.745 12.66 42.85 18.99 25.32 13.147 4.382 0.487 12.66 38.954 45.528 53.075 67.683 116.376 126.115 56.971 (mg/l) Chloride 14 6816 7369.8 5949.8 1917 6432.6 3464.8 4451.7 2030.6 781 355 2300.4 6390 9230 8662 10437 17508.6 17068.4 11005 (mg/l) Sulphate 15 155.5 151 161 93 164 130 138 103 44 18.5 109 149 158 163 149 156 145 155 (mg/l) Sodium 16 34.1 26.05 29.3 46.35 32.35 41.85 34.6 45.35 50.35 52.6 45.6 30.05 26.4 28.55 14.2 5.65 6.95 6.45 (ppt) Potassium 17 336.00 333.49 336.00 340.99 335.99 338.50 336.00 340.99 340.99 343.50 340.99 336.00 333.49 335.99 331.00 326.00 328.49 328.49 (mg/l) 18 Phosphorous(mg/l) 15.5 27.5 24.0 34.0 82.5 31.5 21.5 4.5 3.5 3.5 0.5 13.5 12.5 7.5 3.5 25.7 20.5 5.0 Total Nitrogen 19 28 28 28 21 35 35 35 42 35 28 28 42 35 35 49 35 35 35 (mg/l) 219 Table 3.19. Results on the physico-chemical characterization of sediment samples along different locations in Thrissur district Sl TSR TSR TSR TSR TSR TSR TSR TSR No: Parameters TSR 1 TSR 2 TSR 3 TSR 4 5 TSR 6 TSR 7 TSR 8 TSR 9 TSR 10 11 12 TSR 13 14 15 16 17 18 1 pH 8.51 7.32 7.76 7.44 7.76 6.67 5.54 7.45 5.76 5.57 7.62 7.72 6.76 6.58 5.66 6.57 8.16 5.26 2 Moisture % 6.3 8.2 9.2 7.35 5.32 8.6 4.58 6.28 12.4 9.6 5.6 7.1 6.8 9.12 6.35 8.5 7.25 5.5 3 Sand % 97.2 89.1 81.4 89.0 76.7 69.8 92.3 94.3 81.1 85.1 87.8 78.7 57.5 80.0 75.1 95.8 81.8 59.2 4 Silt % 0.1 0.1 0.1 0.1 0.1 0.2 0.3 0.1 0.4 0.1 0.1 0.1 0.1 0.1 0.2 0.2 0.1 0.1 5 Clay % 2.7 10.8 18.5 10.9 23.2 30.0 7.4 5.6 18.5 14.8 12.1 21.2 42.4 19.9 24.7 4.0 18.1 40.7 6 Organic carbon (g/kg) 9.4 4.4 20.2 12.5 7.1 18.3 9.8 5.1 28.7 14.8 8.8 13.0 41.8 11.1 16.4 4.4 9.0 28.6 7 Nitrogen (mg/kg) 560 1120 1330 630 490 1260 770 420 1330 910 700 910 1120 770 840 560 630 1260 8 Phosphorous (mg/kg) 46.5 42.0 78.5 67.5 53.5 85.0 83.5 14.5 52.5 46.5 75.2 46.0 80.0 55.0 40.0 80.0 54.5 40.0 9 Potassium(mg/kg) 5.01 2.50 22.48 5.01 39.99 22.48 12.51 57.52 12.51 2.50 5.01 27.49 2.50 32.49 34.99 34.99 20.02 24.99 10 Sodium (ppt) 0.415 0.36 0.275 0.21 0.3975 0.255 0.365 0.25 0.355 0.3025 0.31 0.2 0.5275 0.575 0.44 0.94 0.69 0.745 220 Kuzhivathkadav (TSR 6), Vayalar (TSR 7) and Ala-Gothuruth (TSR 8) of Thrissur district were noted to be perfectly ideal sites for the afforestation of Rhizophora mucronata. Azheekkode and Methala were the ideal sites for Bruguiera cylindrica and Excoecaria agallocha. Marthoma Nagar was the ideal site for Avicennia officinalis, E. agallocha, R. mucronata and Sonneratia alba. Kuzhivathkadav and Vayalar were the ideal sites for E. agallocha. Ala-Gothuruth and Banglamkadav were ideal for B. cylindrica. Veluthakadav was ideal for A. officinalis, B. cylindrica and R. mucronata. Muttichur kadav, Ayodyanagar and Moonnamkall were ideal for R. mucronata whereas, Kundukadav was ideal for both A. officinalis and R. mucronata (Plate 3.5). The moderately ideal sites for afforestation were Kuzhivathkadav (TSR 6), Vayalar (TSR 7) and Chiplimad (TSR 16) for A. officinalis and B. cylindrica; Poochakkadav (TSR 1) for B. cylindrica, E. agallocha and R. mucronata; Azheekkode (TSR 2) and Methala (TSR 4) for A. officinalis and R. mucronata; Marthoma Nagar (TSR 3) for B. cylindrica; Idamukk (TSR 5) for B. cylindrica, E. agallocha, R. mucronata and S. alba; Ala-Gothuruth (TSR 8) for A. officinalis and E. agallocha; Veluthakadav (TSR 9) and Kundukadav (TSR 14) for E. agallocha and S. alba; Muttichur kadav (TSR 10) for A. officinalis, B. cylindrica, E. agallocha and S. alba; Meenkadav (TSR 11) for A. officinalis, B. cylindrica, E. agallocha and R. mucronata; Orumanayur (TSR 12) for A. officinalis, R. mucronata and S. alba; Ayodyanagar (TSR 13) for E. agallocha; Moonnamkall (TSR 15) for A. officinalis, E. agallocha and S. alba; Banglamkadav (TSR 17) for A. officinalis and S. alba and Pulikkakadav (TSR 18) for A. officinalis, E. agallocha and R. mucronata. 18 sites were selected for assessing the physico-chemical characteristics of water and sediment samples from Malappuram district for elucidating the possibilities of mangrove afforestation. The results are depicted in Tables 3.20 – 3.21. 221 Table 3.20. Results on the physico-chemical characterization of water samples along different locations in Malappuram district Sl MPM MPM MPM MPM MPM MPM MPM MPM MPM MPM MPM MPM No Parameters MPM 1 MPM 2 MPM 3 MPM 6 MPM 7 MPM 8 4 5 9 10 11 12 13 14 15 16 17 18 : 1 pH 7.94 7.91 7.83 7.84 7.58 7.4 7.61 8 7.96 7.42 7.73 7.51 7.91 8 7.14 7.42 7.81 7.78 Turbidity 2 0.1 0 1 0 0.1 1.1 31.4 37 34.8 13.3 2.4 0.1 7 3.2 0.4 1 1.6 2 (NTU) 3 T.S (mg/l) 41800 42000 42000 41800 42400 36800 37600 42400 43400 41200 9800 43000 45600 44000 40400 42600 43000 45400 4 T.D.S (ppt) 24.62 24.16 24.86 23.91 24.18 20.86 21.54 24.22 24.15 23.67 5.724 24.54 25.05 24.98 22.83 24.64 25.48 25.29 5 T.S.S (mg/l) 17180 17840 17140 17890 18220 15940 16060 18180 19250 17530 4076 18460 20550 19020 17570 17960 17520 20110 6 Salinity(ppt) 32.72 31.78 32.82 31.34 32.28 27.29 28.07 31.8 32.03 31.12 6.544 32.78 33.48 32.97 30.04 32.76 33.96 34 7 Conductivity(mS) 48.13 47.28 48.61 46.78 47.27 40.73 42.11 47.35 47.2 46.2 11.19 48.05 48.98 48.83 44.64 48.03 49.81 49.43 8 Resistivity(Ω) 20.33 20.66 20.12 20.91 20.67 23.96 23.24 20.64 20.73 21.16 87.35 20.34 19.97 19.99 21.87 20.32 19.64 19.77 9 Acidity (mg/l) 35.2 39.6 39.6 35.2 35.2 30.8 57.2 57.2 39.6 57.2 17.6 35.2 30.8 26.4 35.2 30.8 26.4 26.4 10 Alkalinity (mg/l) 140 130 150 150 150 150 250 170 160 160 110 160 150 150 130 150 150 160 11 Hardness(mg/l) 600 700 602 592 592 518 550 620 390 720 130 392 410 620 356 600 638 630 12 Calcium(mg/l) 38.448 40.05 39.249 37.647 36.045 34.443 34.443 37.647 40.857 39.249 11.214 42.453 39.249 40.851 34.443 36.846 40.05 43.25 121.24 151.43 126.11 13 Magnesium(mg/l) 122.706 146.079 122.706 122.22 105.177 112.968 128.063 70.118 24.883 69.631 75.961 65.736 123.68 130.984 127.08 6 5 5 14 Chloride(mg/l) 14200 19738 14200 17750 19312 17040 18034 19738 20945 19028 5325 13348 21016 20590 11644 19525 20164 20590 15 Sulphate(mg/l) 180 167 180 180 160 160 160 158 154 156 130 158 158 156 156 156 154 152 16 Sodium (ppt) 17.4 8.75 8.55 9 14.8 2.3 10.3 11 18.5 7.75 36.35 14 28.05 23.9 8.9 22.65 3.8 22.55 323.501 323.501 323.50 17 Potassium(mg/l) 320.99 320.99 328.49 323.50 320.99 318.00 323.50 338.50 320.99 314.00 316.49 323.50 315.50 328.49 316.49 7 7 7 Total 18 Phosphorous(mg/ 0.6 2.0 1.5 1.5 0.03 6.0 49.5 25.0 7.5 58.0 2.0 6.0 0.9 3.5 0.03 0.5 0.45 0.5 l) Total Nitrogen 19 28 28 28 28 28 28 35 35 28 35 21 35 35 35 28 28 21 35 (mg/l) 222 Table 3.21. Results on the physico chemical characterization of sediment samples along different locations in Malappuram district Sl MPM MPM MPM MPM MPM MPM MPM MPM MPM MPM MPM MPM MPM MPM MPM MPM MPM Parameters MPM 5 No: 1 2 3 4 6 7 8 9 10 11 12 13 14 15 16 17 18 1 pH 6.16 5.3 5.1 4.9 6.13 6.46 6.78 6.45 6.34 6.83 6.76 5.26 6.4 6.33 6.69 6.92 7.73 7.21 2 Moisture % 5.26 6.12 9.5 12.5 8.5 6.5 6.84 9.8 8.7 12.58 7.4 11.1 7.8 6.85 12.5 8.5 7.6 9.6 3 Sand % 78.3 89.2 64.3 46.3 81.7 81.7 80.4 58.4 87.4 70.4 89.2 87.8 88.8 89.8 73.9 72.8 61.0 79.3 4 Silt % 0.1 0.1 0.1 0.1 0.2 0.2 0.2 0.1 0.1 0.2 0.2 0.1 0.1 0.1 0.1 0.2 0.1 0.2 5 Clay % 21.6 10.7 35.6 53.6 18.1 18.1 19.4 41.5 12.5 29.4 10.6 12.1 11.1 10.1 26.0 27.0 38.9 20.5 Organic carbon 6 14.77 19.03 11.15 39.8 9.2 18.89 16.59 17.49 11.58 37.11 2.32 36.17 21.0 5.66 17.28 42.86 16.39 26.06 (g/kg) 7 Nitrogen (mg/kg) 560 1120 1540 1260 700 1050 700 700 490 840 350 560 560 420 630 1750 1680 1190 Total 8 Phosphorous 13.5 28.0 62.0 23.5 29.0 59.5 62.5 93.0 50.5 62.5 76.5 0.495 66.0 86.0 61.0 45.5 45.5 60.0 (mg/kg) Potassium 9 2.5 5.00 2.5 39.99 0 20.02 24.99 22.48 5.01 37.5 0 12.51 10.01 0 17.52 39.99 52.51 50.01 (mg/kg) 10 Sodium (ppt) 0.115 0.0325 0.0175 0.235 0.068 0.0725 0.04 0.0075 0.078 0.0825 0.065 0.105 0.008 0.075 0.06 0.38 0.4375 0.3675 223 In Malappuram district, Kottappadi (MPM 18) is the most ideal site for afforestation of all the five mangrove species. Mangalam Bridge side (MPM 6), Purathur boat jetty (MPM 10) and Kottakkadavu (MPM 17) were ideal for Rhizophora mucronata whereas, Koottayi (MPM 7) and Murikkummadu (MPM 9) were ideal for Bruguiera cylindrica. Puthuponnani east (MPM 12) was ideal for B. cylindrica and Excoecaria agallocha whereas, Pariyapuram 2 (MPM 2) was ideal for E. agallocha (Plate 3.6). Poorappuzha Bridge side was (MPM 5) noted to be moderately ideal for all the five species. Other moderately ideal afforestation sites were Olipram kadavu (MPM 16) for A. officinalis, B. cylindrica ,S. alba, E. agallocha and R. mucronata; Purathur boat jetty (MPM 10), Chamravattom Kadav (MPM 11) and Kottakkadavu (MPM 17) for A. officinalis, B. cylindrica and E. agallocha; Pariyapuram 3 (MPM 3) , Pariyapuram 4 (MPM 4) and Puthuponnani west (MPM 13) for E. agallocha and R. mucronata; Purathur (MPM 8) for B. cylindrica; Thayyilakkadavu (MPM 15) for A. officinalis; Pariyapuram 1 (MPM 1) and Puthuponnani east (MPM 12) for S. alba and A. officinalis; Murikkummadu (MPM 9) and Puthuponnani Munambam (MPM 14) for E. agallocha; Pariyapuram 2 (MPM 2) for B. cylindrica and R. mucronata; Mangalam bridge (MPM 6) for A. officinalis, E. agallocha and S. alba and Koottayi (MPM 7) for A. officinalis and S. alba. For assessing the possibilities of mangrove afforestation, physico-chemical analysis of water and sediment samples from 18 sites in Kozhikode district has been carried out. The results are depicted in Tables 3.22 – 3.23. 224 Table 3.22. Results on the physico chemical characterization of water samples along different locations in Kozhikode district Sl KKD KKD KKD KKD KKD KKD KKD KKD KKD KKD KKD KKD KKD KKD KKD KKD No Parameters KKD 16 KKD 17 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 : 18 1 pH 7.91 7.98 7.95 7.86 7.71 8 8.03 7.95 7.9 7.97 7.83 7.24 7.98 7.3 7.97 7.83 8.03 7.8 Turbidity 2 1.6 0.9 4 2.1 2.1 2.1 2.0 5.6 6 4.8 3.4 1.2 2.8 8.9 6 2.4 4 1.8 (NTU) 3 T.S (mg/l) 42800 41800 36600 41800 41400 41000 41600 42800 41800 44000 33400 20600 34800 38400 38400 28600 35400 34600 4 T.D.S (ppt) 26.59 26.41 23.51 26.22 26.2 26.56 26.2 26.11 25.55 25.77 21.24 15.41 22.51 25.26 25.11 19.11 23.57 21.9 5 T.S.S (mg/l) 16210 15390 13090 15580 15200 14440 15400 16690 16250 18230 12160 5190 12290 13140 13290 9490 11830 12700 Salinity 6 35.45 35.22 30.84 35.09 35.2 35.75 34.79 35.05 34.2 34.36 27.69 19.31 29.5 33.2 33.27 24.5 31.22 28.44 (ppt) Conductivity( 7 52.13 51.63 45.98 51.34 51.22 51.84 51.21 51.05 50.07 50.38 41.54 30.12 44.01 49.18 49.17 37.36 46 42.8 mS) Resistivity 8 18.8 18.94 21.27 19.02 19.08 18.83 19.09 19.14 19.53 19.39 23.53 32.43 22.21 19.86 19.92 26.2 21.19 22.87 (Ω) Acidity 9 17.6 26.4 26.4 26.4 30.8 17.6 17.6 35.2 22 13.2 22 17.6 22 30.8 30.8 22 17.6 17.6 (mg/l) Alkalinity 10 160 150 250 160 160 170 150 170 150 160 150 90 140 190 200 200 160 120 (mg/l) Hardness 11 570 626 462 600 618 460 526 540 494 564 450 274 480 474 560 588 458 384 (mg/l) Calcium 12 42.453 33.642 32.04 38.448 36.846 28.035 36.045 35.244 25.632 29.637 20.826 16.821 25.632 38.448 34.443 24.03 27.234 26.43 (mg/l) Magnesium( 131.95 128.06 106.15 110.04 119.29 101.28 115.40 13 112.968 93.004 122.706 94.951 104.69 96.9 56.484 92.03 128.55 94.951 77.42 mg/l) 8 3 1 6 8 2 2 Chloride 21143. 17210. 11473. 19468. 20149. 20206. 18048. 14 22365 22010 18460 22720 21797 21300 22720 21087 21300 15449.6 19198.4 (mg/l) 8 4 6 2 8 6 2 Sulphate 15 170 164 161 161 156 159 170 163 161 163 159 152 156 156 159 156 156 156 (mg/l) 16 Sodium (ppt) 21.24 21.34 18.54 20.44 11.72 21.34 21.34 21.24 17.44 17.04 15.48 13.24 17.54 23.14 20.04 15.84 15.24 17.54 Potassium 126.01 103.99 133.99 133.99 133.99 153.99 1519.8 1179.9 17 163.985 126.019 279.96 879.99 209.7 819.93 859.97 660.01 620.01 879.99 ( mg/l) 9 8 6 6 6 9 2 9 Total 18 Phosphorous( 30.0 10.5 17.5 4.5 8.0 16.0 3.5 35.0 2.5 3.5 0.03 0.04 3.5 120.0 15.5 2.5 1.0 1.0 mg/l) Total 19 Nitrogen 35 35 42 28 28 21 35 42 28 21 28 28 35 42 35 28 28 28 (mg/l) 225 Table 3.23. Results on the physico chemical characterization of sediment samples along different locations in Kozhikode district Sl KKD KKD KKD KKD KKD KKD KKD KKD KKD KKD KKD KKD KKD KKD KKD KKD KKD KKD Parameters No: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 1 pH 7.33 8.15 6.6 6.94 7.55 7.64 7.93 7.4 7.31 7.11 7.21 6.7 7.19 7.65 6.66 7.26 7.89 7.64 2 Moisture % 6.3 5.4 21.36 15.8 6.8 5.4 8.9 7.5 2.5 25.8 6.8 5.7 3.9 11.5 27.3 8.9 5.6 9.5 3 Sand % 93.2 85.9 66.7 80.6 75.4 79.3 67.7 32.4 81.7 62.2 76.0 79.3 76.5 73.1 58.0 50.9 54.8 53.3 4 Silt % 0.2 0.4 0.2 0.2 0.4 0.1 0.1 0.1 0.1 0.1 0.2 0.1 0.1 0.1 0.2 0.3 0.1 0.1 5 Clay % 6.6 13.7 33.1 19.2 24.2 20.6 32.2 67.5 18.2 37.7 23.8 20.6 23.4 26.8 41.8 48.8 45.1 46.6 Organic 6 carbon 1.97 3.29 91.58 12.77 22.74 5.31 35.73 48.2 8.68 98.26 26.76 4.41 0.98 12.62 22.36 155.46 111.26 125.96 (gm/kg) Nitrogen 7 560 840 2240 840 840 420 700 2940 840 1401 1470 770 630 910 1820 1540 1401 1680 (mg/kg) Total 8 Phosphorous 32.5 42.0 63.5 39.5 60.5 28.0 38.5 70 55.5 69.5 54.5 32.5 35.0 14.5 68.2 74.5 89.5 130.5 (mg/kg) Potassium( 9 17.52 24.99 39.99 10.01 22.48 2.50 12.51 149.99 34.99 60.02 60.02 0 2.50 25.02 67.49 52.51 69.99 74.99 mg/kg) 10 Sodium (ppt) 0.7125 0.1075 0.4325 0.1425 0.1775 0.025 0.145 1.2325 0.235 0.5725 0.1675 0.1725 0.0625 0.215 0.5375 0.4325 0.66 0.52 226 Elathur (KKD 5) and Cheliya (KKD 11) of Kozhikode district were noted to be ideal for the afforestation of Bruguiera cylindrica (Plate 3.6). Also, these two sites were moderately ideal for all the other 4 species. Kooniyil kadavu (KKD 9) and Nelliyadikadavu (KKD 12) were moderately ideal for Avicennia officinalis. The other moderately ideal sites were Beypore (KKD 2) for all the 5 species under study; Thekkeppuram (KKD 4) and Aanappara (KKD 10) for A. officinalis, B. cylindrica ,S. alba, E. agallocha and R. mucronata; Chaliyam for Avicennia officinalis and B. cylindrica; Venkalam (KKD 8) for B. cylindrica and E. agallocha; Kuttiyammal (KKD 14) for A. officinalis and E. agallocha; Puramkara (KKD 15) for A. officinalis, B. cylindrica and R. mucronata; Mooradu (KKD 16) for B. cylindrica, E. agallocha and R. mucronata; Kottakkal (KKD 17) for B. cylindrica and R. mucronata; Puthiyottilkadavu (KKD 7) for E. agallocha and Iringal (KKD 18) for R. mucronata. 18 sites were selected for assessing the physico chemical characteristics of water and sediments in the district of Kannur to elucidate the possibilities of mangrove afforestation. The results are depicted in Tables 3.24 – 3.25. 227 Table 3.24. Results on the physico-chemical characterization of water samples along different locations in Kannur district Sl KNR KNR KNR KNR KNR KNR KNR KNR KNR KNR KNR KNR KNR KNR KNR KNR KNR No Parameters KNR 18 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 : 17 1 pH 7.27 7.14 7.41 7.75 7.94 7.69 7.39 7.15 7.08 7.1 7.54 7.5 7.62 7.88 8.04 7.78 7.19 7.54 Turbidity(NT 2 0.1 1.2 0.1 0.3 0.3 0.1 1 1.2 0.6 0.5 0.1 1.2 0.1 0 0.2 0.1 0.7 0.2 U) 3 T.S (mg/l) 21000 24600 26600 28400 35800 45600 25400 17400 17400 16600 21200 25400 23000 33400 34400 27600 25800 20200 4 T.D.S (ppt) 14.58 17.19 18.14 18.91 23.66 17.09 15.89 12.34 12.4 11.76 13.78 17.1 15.73 19.55 22.13 17.81 17.59 13.45 5 T.S.S (mg/l) 6420 7410 8460 9490 12140 28510 9510 5060 5000 4840 7420 8300 7270 13850 12270 9790 8210 6750 6 Salinity(ppt) 18.29 21.8 23.28 24.23 31.18 21.76 20.15 15.21 15.29 14.4 17.19 21.82 19.85 25.2 28.88 22.76 22.42 16.68 Conductivity 7 28.5 33.53 35.43 36.96 46.25 33.42 31.07 24.1 24.25 22.98 26.94 33.43 30.76 38.22 43.27 34.82 34.38 26.3 (mS) Resistivity 8 34.32 29.14 27.53 26.45 21.14 29.2 31.42 40.58 40.31 42.53 36.29 29.24 31.78 25.57 22.63 28.09 28.45 37.16 (Ω) 9 Acidity (mg/l) 19.8 26.4 17.6 13.2 17.6 17.6 22 13.2 110 13.2 13.2 8.8 13.2 17.6 13.2 13.2 22 17.6 Alkalinity 10 120 130 130 130 170 140 140 110 400 140 130 160 130 120 130 160 160 140 (mg/l) Hardness 11 332 390 427 440 370 388 350 280 272 270 296 386 346 446 526 416 420 307 (mg/l) Calcium 12 22.428 25.632 29.637 34.443 38.448 27.234 24.03 20.826 18.423 18.423 22.428 26.433 24.03 30.438 34.443 28.035 27.234 21.627 (mg/l) Magnesium 107.12 13 67.196 79.37 85.943 86.187 66.71 77.91 70.605 55.51 55.023 54.536 58.432 77.91 69.631 90.082 84.239 85.7 61.6 (mg/l) 5 Chloride 14 11289 12993 13774 14910 18886 14058 12638 9088 9301 8946 10863 13064 13135 15691 18602 20235 13632 10579 (mg/l) Sulphate 15 156 159 157 157 159 155 155 151 145 148 153 156 155 158 160 156 158 153 (mg/l) 16 Sodium (ppt) 14.85 16.9 22.3 4 10.92 29.65 12.85 11.17 8.17 10.12 10.07 10.7 13.55 2.1 22.3 15.05 8.07 11.77 Potassium 580.98 587.98 601.00 603.00 606.01 603.00 328.49 582.98 326.00 17 331.00 333.49 323.50 601.06 336.00 316.49 578.0 615.9 596.001 (mg/l) 7 6 6 0 1 0 7 1 2 Total 18 Phosphorous( 7.5 7.5 0.6 3.0 4.5 4.0 11.0 7.0 29.5 5.5 3.5 18.0 4.5 2.5 0.1 5.5 21.0 0.02 mg/l) Total Nitrogen 19 28 28 28 28 21 21 28 21 42 28 21 28 35 28 28 21 21 21 (mg/l) 228 Table 3.25. Results on the physico chemical characterization of sediment samples along different locations in Kannur district Sl KNR KNR KNR KNR KNR KNR KNR KNR KNR KNR KNR KNR KNR Parameters KNR 11 KNR 12 KNR 13 KNR 15 KNR 18 No: 1 2 3 4 5 6 7 8 9 10 14 16 17 1 pH 8.56 5.31 7.53 7.76 8.76 8.53 8.1 7 7.36 7.28 4.99 8.5 8.65 8.51 8.6 7.55 6.83 7.7 2 Moisture % 5.5 16.9 8.6 12.9 8.5 5.7 15.5 19.2 9.56 8.54 5.6 7.9 8.2 18.5 6.35 15.8 21.3 5.25 3 Sand % 82.7 59.7 62.3 47.9 87.0 53.4 61.3 71.3 77.8 94.9 83.4 89.1 91.0 85.6 91.6 83.4 66.6 89.9 4 Silt % 0.3 0.3 0.1 0.2 0.1 0.7 0.2 0.3 0.4 0.1 0.2 0.1 6.8 0.5 0.5 0.6 1.7 0.1 5 Clay % 17.0 40.0 37.6 51.9 12.9 45.9 38.5 28.4 21.8 5.0 16.4 10.8 2.2 13.9 7.9 16.0 31.7 10.0 Organic carbon 6 1.5 299.3 62.3 94.1 55.1 8.14 91.7 151.8 102.8 8.02 9.8 12.2 6.7 31 6.22 51.6 175.7 30.7 (g/kg) Nitrogen 7 1401 3990 1330 1750 770 560 2310 1750 1960 840 560 630 560 490 700 1680 2450 700 (mg/kg) Total 8 Phosphorous 71.5 44.5 46.2 80.0 109.5 51.0 85.5 53.5 72.0 63.0 51.0 41.0 85.0 41.0 38.0 61.0 78.0 41.0 (mg/kg) Potassium 9 32.49 55.01 39.99 20.02 0 5.01 34.99 47.51 7.51 2.50 15.01 15.01 5.01 5.01 10.01 5.01 47.51 5.01 (mg/kg ) 10 Sodium (ppt) 0.2425 0.3 0.16 0.21 0.035 0.06 0.41 0.2225 0.015 0.015 0.2375 0.2175 0.0575 0.06 0.0475 0.375 0.475 0.065 229 The results revealed that, Thiruvangad (KNR 2) was the ideal site for afforestation of for Excoecaria agallocha and Rhizophora mucronata. Aaruthengu (KNR16) and Valapattanam (KNR 9) were noticed to be ideal for Bruguiera cylindrica and Avicennia officinalis respectively (Plate 3.7). Kavumbhagom (KNR 1) and Sidhikkabad (KNR 17) were moderately ideal for all the species except Sonneratia alba. Mundambalam (KNR 7), Keeriyad (KNR 10) and Aaruthengu were moderately ideal for A. officinalis, E. agallocha and R. mucronata. The other moderately ideal sites were Thiruvangad and Kadavath (KNR 11) for A. officinalis and B. cylindrical; Nettur (KNR 3) for B. cylindrica, E. agallocha and R. mucronata; Koduvalli (KNR 4) for A. officinalis and R. mucronata; Meenthalapeedika (KNR 5) for B. cylindrica and E. agallocha; Kulamkadav (KNR 8) for A. officinalis, B. cylindrica and R. mucronata; Iranav (KNR 14) for B. cylindrica, E. agallocha and Sonneratia alba; Valapattanam for B. cylindrica and Sonneratia alba; Port road (KNR 12) for B. cylindrica and E. agallocha and Badikkad (KNR 18) for A. officinalis. As far as Kasaragod district is concerned, 18 sites were selected and the physico chemical analysis of water and sediment from all the sites has been carried out. The results are depicted in the following Tables 3.26 – 3.27. 230 Table 3.26. Results on the physico-chemical characterization of water samples along different locations in Kasaragod district Sl KSD KSD KSD KSD KSD KSD KSD KSD No Parameters KSD 1 KSD 2 KSD 3 KSD 5 KSD 7 KSD 8 KSD 9 KSD 12 KSD 16 KSD 18 4 6 10 11 13 14 15 17 : 1 pH 7.64 7.67 7.36 7.8 7.82 8.1 7.6 7.85 7.68 7.87 8 7.7 7.54 6.96 7.18 6.66 7.37 6.63 Turbidity 2 0.1 0.1 0 0 0 0.4 0.1 0.1 0 0.1 0.5 0.1 0.1 0 0 0.1 0.6 0 (NTU) 3 T.S (mg/l) 24000 24200 24200 26200 26600 28400 28400 34000 28800 32600 35800 20200 27600 5000 9400 200 12600 2600 4 T.D.S (ppt) 17.05 17 16.67 17.89 19.04 19.35 19.62 23.31 20.02 22.11 23.72 14.44 19 3.824 7.201 0.1108 9.326 2.259 5 T.S.S (mg/l) 6950 7200 7530 8310 7560 9050 8780 10690 8780 10490 12080 5760 8600 1176 2199 89.2 3274 341 Salinity 6 21.76 21.64 21.24 22.89 24.64 25.04 25.42 30.81 25.99 29.05 31.5 18.15 24.59 4.276 8.471 0.1103 11.1 2.443 (ppt) Conductivity 7 33.33 33.24 32.64 34.98 37.19 37.83 38.35 45.6 39.14 43.27 46.38 28.23 37.22 7.475 14.08 0.2158 18.23 4.416 (mS) 8 Resistivity(Ω) 29.33 29.42 29.97 27.95 26.26 25.87 25.48 21.45 24.98 22.61 21.05 34.64 26.28 130.9 69.48 4689 53.75 221.5 9 Acidity (mg/l) 17.6 22 17.6 15.4 19.8 17.6 26.4 22 35.2 22 17.6 11 22 8.8 13..2 17.6 13.2 17.6 10 Alkalinity (mg/l) 140 130 130 130 150 150 170 140 170 150 210 100 140 50 70 50 100 60 Hardness 11 200 392 336 418 445 260 273 368 480 528 372 324 452 87 166 8 216 54 (mg/l) Calcium 12 36.846 32.04 31.239 29.637 32.841 35.244 32.841 42.453 34.443 38.448 37.647 24.03 32.841 8.01 13.617 0.801 16.02 8.01 (mg/l) Magnesium 105.17 13 26.294 75.961 62.814 83.752 88.378 41.876 46.502 63.788 95.925 67.683 64.275 90.082 16.312 32.137 1.461 42.85 8.278 (mg/l) 7 Chloride 14 13135 13774 12567 13490 14129 15194 15123 17963 14981 19525 17750 11573 14910 3337 6248 994 7810 2769 (mg/l) Sulphate 15 166 160 158 152 152 154 140 155 151 155 155 149 151 114 136 12.5 144 92 (mg/l) 16 Sodium (ppt) 14.25 12.57 15.35 5.85 15.55 3.6 11.72 1.4 10.92 12.57 17.3 11.42 0.94 3.46 14.85 9.12 6.08 5.68 Potassium 578.01 696.99 575.98 568.00 592.99 646.99 646.98 662.00 575.98 625.99 17 328.49 323.50 601.06 696.97 815.86 592.91 681.982 672.012 (mg/l) 5 7 2 2 1 9 8 2 2 1 Total 18 Phosphorous 1.0 0.02 0.03 2.5 2.5 0.35 5.0 11.0 8.0 5.0 6.5 1.5 3.0 0.05 0.8 0.03 20.0 0.05 (mg/l) Total Nitrogen 19 28 35 21 42 21 28 28 21 28 21 35 21 21 28 28 28 35 28 (mg/l) 231 Table 3.27. Results on the physico-chemical characterization of sediment samples along different locations in Kasaragod district Sl KSD KSD KSD KSD KSD KSD KSD KSD KSD KSD KSD KSD KSD KSD KSD KSD KSD Parameters KSD 6 No: 1 2 3 4 5 7 8 9 10 11 12 13 14 15 16 17 18 1 pH 5.1 4.47 6.32 5.52 8.35 7.58 2.84 8.34 8.08 8.83 8.48 8.66 7.5 3.87 6.73 5.82 7.78 6.93 2 Moisture % 7.75 5.25 8.35 4.8 9.6 24.8 6.8 9.25 6.39 25.8 12.6 18.2 12.5 8.9 6.4 7.5 8.45 6.5 3 Sand % 92.6 93.6 90.8 85.4 86.0 80.9 89.5 95.0 83.1 9.4 93.4 79.0 37.7 73.9 47.5 83.2 79.3 84.2 4 Silt % 0.2 0.1 0.1 0.1 0.1 0.2 0.1 0.1 0.1 0.1 0.1 0.1 0.6 0.1 0.3 0.1 0.2 0.1 5 Clay % 7.2 6.3 9.1 14.5 13.9 18.9 10.4 4.9 16.8 8.5 6.5 20.9 61.7 2.0 52.2 16.7 20.5 15.7 Organic carbon 6 13.3 5.3 8.1 9.0 11.04 4.31 26.44 12.66 13.88 5.3 11.79 6.23 41.61 11.33 31.72 25.22 9.0 19.2 (g/kg) 7 Nitrogen (mg/kg) 630 560 700 560 700 420 770 1540 1120 420 560 560 1540 700 1470 910 700 1401 Total Phosphorous 8 15.5 12.8 12.5 8.5 18.0 13.0 28.0 64.0 42.0 14.5 23.5 36.5 105.5 32.0 48.0 41.0 37.8 37.5 (mg/kg) 9 Potassium(mg/kg) 12.51 7.51 10.01 15.01 2.50 12.51 22.48 7.51 20.02 2.50 5.01 2.50 64.98 2.50 22.48 0 5.01 15.01 10 Sodium (ppt) 0.2975 0.19 0.22 0.3175 0.1325 0.27 0.225 0.08 0.1275 0.0275 0.045 0.0425 0.45 0.235 0.47 0.2 0.29 0.3925 232 The results revealed that sites Chithari (KSD 15) and Keeyoor Kadavath (KSD 17) were ideal for Excoecaria agallocha and Avicennia officinalis respectively whereas, Chemanad (KSD 18) was ideal for Bruguiera cylindrica and Excoecaria agallocha (Plate 3.7). Udumbumthala (KSD 1) and Keeyoor Kadavath were moderately ideal for Rhizophora mucronata. The other moderately ideal sites noticed were Kaikkottukadav (KSD 3) for E. agallocha; Idayilekkadu Island (KSD 5), Thekkekkadu (KSD 7) and Mattummal (KSD 9) for Avicennia officinalis, B. cylindrica and E. agallocha; Madakkara (KSD 13) for R. mucronata; Vellapp (KSD 4) for B. cylindrica, E. agallocha, R. mucronata and S. alba; Ayittikkadav (KSD 6) for A. officinalis, B. cylindrica, R. mucronata and S. alba; Orcha (KSD 14) for A. officinalis, E. agallocha and R. mucronata; Chithari () for A. officinalis and R. mucronata; Kappil (KSD 16) for B. cylindrica and E. agallocha and Chemanad for A. officinalis, R. mucronata and S. alba. A consolidation of sites ideal for species specific mangrove introduction are given in Table 3.28. 233 Table 3.28. Details of moderately ideal, ideal and perfectly ideal sites for mangrove afforestation along all the districts under study Trivandrum Number of sites Avicennia Bruguiera Excoecaria Rhizophora Sonneratia Class officinalis cylindrica agallocha mucronata alba A 5 10 9 10 14 B 11 9 7 8 4 C 3 0 3 1 1 D 0 0 0 0 0 E 0 0 0 0 0 Kollam Number of sites Avicennia Bruguiera Excoecaria Rhizophora Sonneratia Class officinalis cylindrica agallocha mucronata alba A 6 6 8 6 15 B 11 10 8 9 3 C 1 2 2 3 0 D 0 0 0 0 0 E 0 0 0 0 0 Alleppey Number of sites Avicennia Bruguiera Excoecaria Rhizophora Sonneratia Class officinalis cylindrica agallocha mucronata alba A 6 10 11 9 17 B 9 7 6 5 0 C 3 1 1 3 1 D 0 0 0 1 0 E 0 0 0 0 0 Ernakulam Number of sites Avicennia Bruguiera Excoecaria Rhizophora Sonneratia Class officinalis cylindrica agallocha mucronata alba A 2 4 7 4 15 B 15 13 11 9 3 C 1 1 0 5 0 234 D 0 0 0 0 0 E 0 0 0 0 0 Thrissur Number of sites Avicennia Bruguiera Excoecaria Rhizophora Sonneratia Class officinalis cylindrica agallocha mucronata alba A 3 5 3 2 10 B 12 8 10 7 7 C 3 5 5 6 1 D 0 0 0 3 0 E 0 0 0 0 0 Malappuram Number of sites Avicennia Bruguiera Excoecaria Rhizophora Sonneratia Class officinalis cylindrica agallocha mucronata alba A 8 7 2 6 13 B 9 7 13 8 4 C 1 4 3 4 1 D 0 0 0 0 0 E 0 0 0 0 0 Kozhikode Number of sites Avicennia Bruguiera Excoecaria Rhizophora Sonneratia Class officinalis cylindrica agallocha mucronata alba A 8 8 9 9 15 B 10 8 9 9 3 C 0 2 0 0 0 D 0 0 0 0 0 E 0 0 0 0 0 Kannur Number of sites Avicennia Bruguiera Excoecaria Rhizophora Sonneratia Class officinalis cylindrica agallocha mucronata alba A 7 7 8 9 16 B 10 10 9 8 2 C 1 1 1 1 0 235 D 0 0 0 0 0 E 0 0 0 0 0 Kasaragod Number of sites Avicennia Bruguiera Excoecaria Rhizophora Sonneratia Class officinalis cylindrica agallocha mucronata alba A 9 10 8 10 15 B 8 7 8 8 3 C 1 1 2 0 0 D 0 0 0 0 0 E 0 0 0 0 0 A: not ideal, B: moderately ideal, C: ideal, D: perfectly ideal and E: exemplarily ideal From all the results, it can be concluded that, three sites each in Trivandrum, Alleppey and Thrissur; one site each in Kollam, Ernakulam, Malappuram, Kannur and Kasaragod districts are ideal for the afforestation of Avicennia officinalis. Bruguiera cylindrica was noticed to be ideal for afforestation along five sites in Thrissur, four sites in Malappuram, two sites each in Kollam and Kozhikode and one site each in Alleppey, Ernakulam, Kannur and Kasaragod districts. The species Excoecaria agallocha was found to be ideal for afforestation along five sites in Thrissur, three sites each in Trivandrum and Malappuram, two sites each in Kollam and Kasaragod and one site each in Kannur and Alleppey districts. With respect to Rhizophora mucronata, six sites in Thrissur, five sites in Ernakulam, four sites in Malappuram, three sites each in Alleppey and Kollam and one site each in Trivandrum and Kannur districts were found ideal for afforestation. Three sites in Thrissur and one site in Alleppey districts were found to be perfectly ideal for the introduction of Rhizophora mucronata. The species Sonneratia alba was found to be ideal for afforestation along one site each in Trivandrum, Alleppey, Thrissur and Kollam districts. Thus, out of 163 sites studied the numbers of perfectly ideal, ideal and moderately ideal sites for the afforestation of different mangrove species have been worked out. From the results it can be concluded that, 4 sites are perfectly ideal for the 236 introduction of Rhizophora mucronata. The numbers of ideal sites for the afforestation of different species are 14 sites for Avicennia officinalis, 17 sites each for Bruguiera cylindrica and Excoecaria agallocha, 18 sites for Rhizophora mucronata and 4 sites for Sonneratia alba. Similarly, 95 moderately ideal sites for the introduction of Avicennia officinalis, 79 for Bruguiera cylindrica, 81 for Excoecaria agallocha, 71 for Rhizophora mucronata and 29 for Sonneratia alba have also been noticed. Based on the textural classes of soil/sediment preferred by various mangrove species (Plate 3.8), attempt has also been carried out to demarcate ideal sites for mangrove afforestation. The sediment classes worked out for each site along 9 districts under study are depicted in Table 3.29. Table 3.29. Textural classes of soil / sediment samples along all the sites along 9 districts of Kerala Sl Textural Class No: TVM KLM ALP EKM TSR MPM KKD KNR KSD Sandy Loamy Loamy Sandy Sandy 1. Sand Sand clay Sand Sand sand sand clay loam loam Sandy Sandy Loamy Loamy Loamy Loamy Sandy 2. clay Sand clay Sand sand sand sand sand clay loam loam Sandy Sandy Sandy Sandy Sandy Sandy 3. Sand Sand clay clay Sand loam loam clay clay loam loam Sandy Loamy Loamy Sandy Loamy Sandy Sandy Sandy Loamy 4. clay sand sand clay sand clay loam clay sand loam Sandy Sandy Loamy Sandy Loamy Loamy 5. Sand Sand Clay clay clay sand loam sand sand loam loam Sandy Sandy Sandy Sandy Loamy Sandy Sandy Sandy 6. Sand clay clay clay loam sand loam clay loam loam loam Sandy Sandy Sandy Sandy Loamy 7. Sand Sand Sand Sand clay clay loam clay sand loam Sandy Sandy Loamy Loamy Sandy 8. Sand clay Sand Clay clay Sand sand sand clay loam loam 237 Sandy Sandy Sandy Loamy Loamy Sandy Loamy Sandy Sandy 9. clay clay clay sand sand loam sand loam loam loam loam loam Sandy Loamy Sandy Loamy Sandy 10. Sand Sand clay Sand Sand sand clay sand clay loam Sandy Sandy Loamy Loamy Sandy 11. Sand Sand Sand clay Sand loam sand sand loam loam Sandy Sandy Sandy Sandy Sandy Loamy Loamy Loamy 12. Sand clay clay clay clay clay sand sand sand loam loam loam loam loam Sandy Sandy Sandy Loamy Sandy Loamy 13. Sand clay clay clay Sand Clay sand clay sand loam loam loam Sandy Sandy Loamy Sandy Loamy Loamy Loamy 14. Sand clay Sand clay sand loam sand sand sand loam loam Sandy Sandy Loamy Sandy Sandy 15. Sand Sand Sand clay clay Sand sand clay clay loam loam Sandy Sandy Sandy Sandy Sandy Sandy Sandy 16. Sand clay Sand clay clay loam clay loam loam loam loam Sandy Sandy Sandy Sandy Sandy Sandy 17. Sand Sand Sand clay clay loam loam clay clay loam loam Sandy Loamy Sandy Sandy Sandy Loamy Sandy 18. Sand Sand clay sand loam clay clay sand loam loam Sandy 19. clay - - - - - - - - loam Upon comparing the present result with standard textural class preferred by each mangrove species, the sites ideal for their afforestation have been demarcated. Accordingly the most ideal sites for the afforestation of Avicennia officinalis and Sonneratia alba were Manamel of Trivandrum district, Velithuruth of Kollam district, Manivelikkadav and Kuthuthodu of Alleppey district, Mosco road and Munambam of Ernakulam district, Marthoma Nagar, Veluthakadav, Kundukadav and Banglamkadav of Thrissur district, Poorappuzha Bridge side, Mangalam Bridge side and Koottayi of Malappuram district, Thekkeppuram of Kozhikkode district, Kavumbhagom, Kadavath, Aaruthengu of Kannur district, and Ayittikkadav, Mattummal, Kappil and Chemanad of Kasaragod district. 238 Studies based on textural analysis revealed that, the most ideal sites for the afforestation of Bruguiera cylindrica and Excoecaria agallocha were Madhavapuram and Murukkumpuzha Kadavu of Trivandrum district; Kappil, Pozhikkara, Sasthamthodi, Neeravil, MadathilKayalvaaram, Cheriyazheekkal and Pancharathopp of Kollam district; Valiyazheekkal 1, Valiyazheekkal2, Arattupuzha, Kandallur and Mahadevikaad of Alleppey district; Ponnarimangalam, Karuthala west and Pallippuram, of Ernakulam district; Methala, Muttichur kadav and Meenkadav of Thrissur district; Pariyapuram 2, Chamravattom Kadav, Puthuponnani east, Puthuponnani west and Puthuponnani Munambam of Malappuram district; Beypore of Kozhikkode district; Meenthalapeedika, Port road, Iranav and Badikkad of Kannur district; Vellapp, Idayilekkadu Island, Thekkekkadu and Orcha of Kasaragod district. The most ideal sites noted for the afforestation of Rhizophora mucronata were Munnattumukku, Panathura and chambavu of Trivandrum district; Kochochira of Kollam district; Pulikkeril, Purakkad, Kannattakkadav, Andakaranazhi of Alleppey district; Illikkal, Padasekharam road, Moolambilli, Kothad Island and Kadakkara of Ernakulam district; Idamukk, Kuzhivathkadav, Orumanayur and Moonnamkall of Thrissur district; Pariyapuram 1, Thayyilakkadavu, Olipram kadavu and Kottappadi of Malappuram district; Chalappuram, Elathur, Korappuzha, Cheliya, Nelliyadikadavu, Puthuppanam and Kuttiyammal of Kozhikode district; Kulamkadav, Valapattanam and Sidhikkabad of Kannur district; Orkkalam and Keeyoor Kadavath of Kasaragod district. On the basis of different textural classes, sites ideal for afforestation of different mangrove species have been demarcated. The results were comparable with that elucidated on the basis of hydrological and sedimentological aspects. All these sites possessed significant share of growth determining attributes of different mangrove species. Thus it can be concluded that out of 163 sites studied, 21 sites each for Avicennia officinalis and Sonneratia alba; 34 sites each for Bruguiera cylindrica and Excoecaria agallocha; 30 sites for Rhizophora mucronata can be treated as the most ideal sites for the afforestation of such species along 9 districts of Kerala. 239 Summary and Conclusion Strategic restoration / afforestation of mangroves require detailed comprehension on their growth sustaining conditions. As physico- chemical attributes of both water and sediment contribute to the growth and establishment of mangroves, consolidation of database concerning these attributes with respect to the area targeted for afforestation is very much significant. Assessment of the feasibility of an area prior to planting practices will reduce the risk of adaptability of species to such habitats and thereby cut short financial mobilizations to a greater extent. In this background, the present study has been undertaken for the demarcation of ideal sites for afforestation of selected mangrove species along the inland shoreline environments of Kerala. The afforestation possibilities of selected mangrove species were assessed based on their range of tolerance to various hydrogeochemical and sedimentological characteristics as determined in Chapter II. Collection of both water and sediment samples were carried out from 163 locations falling in 9 districts of Kerala such as Trivandrum, Kollam, Alleppey, Ernakulam, Thrissur, Malappuram, Kozhikode, Kannur and Kasaragod. Entire collection was carried out during post monsoon season, which is characteristic in having higher concentration of all elements under target. The tolerance range of mangrove species towards different physico-chemical parameters have been taken into account for assessing the most significant growth determinants of each mangrove species. The number of sites possessing all these attributes or a share was treated as ideal sites for afforestation of respective mangrove species. Based on these, different classes of sites have been described. Sites possessing 0-20% growth sustaining attributes of any mangrove species was treated as A, 21-40 % as B, 41-60% as C, 61-80% as D and 81-100% as E. Sites under category A were treated as non-ideal, B as moderately ideal, C as ideal, D as perfectly ideal and E as exemplarily ideal for afforestation of mangrove species. 240 The results revealed that, three sites each in Trivandrum, Alleppey and Thrissur; one site each in Kollam, Ernakulam, Malappuram, Kannur and Kasaragod districts are ideal for the afforestation of Avicennia officinalis. Bruguiera cylindrica was noticed to be ideal for afforestation along five sites in Thrissur, four sites in Malappuram, two sites each in Kollam and Kozhikode and one site each in Alleppey, Ernakulam, Kannur and Kasaragod districts. The species Excoecaria agallocha was found to be ideal for afforestation along five sites in Thrissur, three sites each in Trivandrum and Malappuram, two sites each in Kollam and Kasaragod and one site each in Kannur and Alleppey districts. With respect to Rhizophora mucronata, six sites in Thrissur, five sites in Ernakulam, four sites in Malappuram, three sites each in Alleppey and Kollam and one site each in Trivandrum and Kannur districts were found ideal for afforestation. Three sites in Thrissur and one site in Alleppey districts were found to be perfectly ideal for the introduction of Rhizophora mucronata. The species Sonneratia alba was found to be ideal for afforestation along one site each in Trivandrum, Alleppey, Thrissur and Kollam districts. Thus it can be concluded that, out of 163 sites studied, 4 sites are perfectly ideal for the introduction of Rhizophora mucronata. The numbers of ideal sites for the afforestation of different species include 14 sites for Avicennia officinalis, 17 sites each for Bruguiera cylindrica and Excoecaria agallocha, 18 sites for Rhizophora mucronata and 4 sites for Sonneratia alba. Similarly, 95 moderately ideal sites for the introduction of Avicennia officinalis, 79 for Bruguiera cylindrica, 81 for Excoecaria agallocha, 71 for Rhizophora mucronata and 29 for Sonneratia alba have also been noticed. Based on the textural classes of soil/sediment preferred by various mangrove species, attempt has also been carried out to demarcate ideal sites for mangrove afforestation. The results were comparable with that elucidated on the basis of hydrogeochemical and sedimentological aspects. All these sites possessed significant share of growth determining attributes of different mangrove species. Thus it can be concluded that out of 163 sites studied, 21 sites each for Avicennia officinalis and Sonneratia alba; 34 sites each for Bruguiera cylindrica and Excoecaria agallocha; 30 sites for Rhizophora mucronata can be treated as the most ideal sites for the afforestation of such species along 9 districts of Kerala. 241 GENERAL CONCLUSION Mangroves are one among the most productive and biologically important ecosystem on this planet, providing unique and vital ecosystem services. Besides all these imperative services provided, these fragile ecosystems are under tremendous pressure. In this context, the present study has been carried out to assess the ecology, extent and diversity of mangrove ecosystems in the coastal environments of Kerala (Chapter I). A survey has been carried out in this regard, which estimated the total extent to be 19.531 Km2. It has also been highlighted that, out of 10 districts studied, Kannur district occupied maximum mangrove cover with 7.465 Km2 which is around 38.22 % of the total extent, within the state. This is followed by Ernakulam district with 6.153 Km2 (31.50 %). Minimum extent has been reported from Trivandrum district with 0.275 Km2 (1.41 %). Upon comparing the results of the present study with that of Basha (1991), there is a positive mangrove cover change of about 2.821 km2 within the last 25 years. Among all the districts under study, Kollam (0.050 km2), Kozhikode (1.723 km2) and Kannur (0.085 km2) showed a decreasing trend of mangrove cover. The study reveals that the mangroves in these districts have shrunken considerably to few patches, mainly in Dharmadom, Nadakkavu, Edakkad, Pappinisseri, Valapattanam, Muzhappilangad, Kunhimangalam, Pazhayangadi, Kavvayi, Thalassery and Ezhimala of Kannur district; Kottooli, Koduvally, Kallai and Kadalundi of Kozhikkode district and Asraamam and Shaktikulangara of Kollam district. High extent of degradation in the total mangrove cover has been noticed in the Kozhikode district. The year wise mangrove declining rate of Kozhikode district (0.069 Km2/yr) is alarmingly indicating the fact that, the remaining mangrove patches will be degraded within the next 20 years. Attempt has also been carried out to study true mangrove species of Kerala. The results revealed that, the state is endowed with 15 True mangrove species as a 242 whole. They are Aegiceras corniculatum, Avicennia marina, Avicennia officinalis, Bruguiera cylindrica, B. gymnorhiza, B. sexangula, Ceriops tagal, Excoecaria agallocha, E. indica, Kandelia candel, Lumnitzera racemosa, Rhizophora apiculata, R. mucronata, Sonneratia alba and S. caseolaris under the families Myrsinaceae, Avicenniaceae, Euphorbiaceae, Rhizophoraceae, Combretaceae and Sonneraceaceae. Among different families reported, Rhizophoraceae possesses the maximum number of species (7) followed by Avicenniaceae (2 species), Euphorbiaceae (2 species), Sonneraceaceae (2 species), Combretaceae (1 species) and Myrsinaceae (1 species). The study revealed that, even though the existing mangrove areas are highly localized, the species diversity is comparatively rich. This indicated the existence of diversified group of mangroves in Kerala. Even though there was positive mangrove cover change in the State as a whole, drastic degradation has been undergoing in many of the urbanized and semi urbanized areas especially in Kozhikode and Kannur districts. If this unsystematic destruction proceeds unchecked, the mangrove patches may completely wiped out within few years. Since the survival of this eco system is very important for the well being of all coupled flora and fauna, intensive and extensive conservation should be undertaken without delay. Afforestation of mangroves seems to be a promising solution for the restoration of lost ecosystems. Successful restoration/afforestation practices of mangroves require reliable comprehension on their specific growth sustaining circumstances. In pursuit of this, the present study has been carried out to evaluate the physico-chemical characteristics of water and sediment along with climatological attributes determining the growth and establishment of selected mangrove species Avicennia officinalis, Bruguiera cylindrica, Excoecaria agallocha, Rhizophora mucronata and Sonneratia alba along heterogeneous natural habitats in Kerala (Chapter II). The study stated that the ‘tolerance range’ of a species with respect to the site is a mandatory requirement towards including them in afforestation purposes whereas the ‘augmented range’ gains significance only after the acclimatization of the species in the new area. In conclusion, the study emphasized that all the 243 afforestation/ restoration practices of mangrove must be either species or site specific. The study also consolidated the tolerance and augmented range of Avicennia officinalis, Bruguiera cylindrica, Excoecaria agallocha, Rhizophora mucronata and Sonneratia alba with respect to hydrogeochemical and sedimentological characteristics. Attempts were also carried out to demarcate the sites ideal for species specific afforestation along the inland coastline environments of Kerala. Altogether163 sites falling under 9 coastal districts of Kerala such as Trivandrum, Kollam, Alleppey, Ernakulam, Thrissur, Malappuram, Kozhikode, Kannur and Kasaragod were selected. The tolerance range of mangroves species towards different physico- chemical parameters have been taken in to account to assess the most significant growth determinants of each mangrove species. The numbers of sites possessing all these attributes or a share were treated as ideal sites for afforestation of respective mangrove species. 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