Abstract-Mangrove ecosystem, an unique, fragile, highly productive ecosystem in the sea-land interphase, is the conglomerations of plants, animals and microorganismsacclimatized in the fluctuating environment of tropical intertidal zone. Thisecosystem is a highly valued ecosystem in terms of economy, environment and ecology.Mangrove ecosystem of Sundarbans, India, (between 210 32’ – 220 40’ north andbetween 880 85’ – 890 00’ east) a World Heritage Site, is a unique tidalwetland from the point of view of its biodiversity and ecology. This tidaldominated deltaic complex is the largest of its kind and covers an area of1,000,000 ha of land and water, the major part (60%) of which is situated inBangladesh while the remaining western portion (40%) lies within India. Themighty Indian river, the Ganges and its associated estuaries like Muriganga,Saptamukhi, Bidyadhari, Haribhanga, Matla, Thakuran etc open into the Bay ofBengal having a north – south direction of water flow. The silt and loamcarried by these estuaries were deposited on the salt marsh eventually leading tothe formation of mosaic of 102 deltaic islands of which 54 have been reclaimedfor human habitation. A number of geomorphological and resultant hydrologicalchanges have contributed for shapping and reshapping of this estuarine complexmaking it a very dynamic system. This ecosystem (representing worlds’ one ofthe most productive ecosystem) harbours thousand of flora and fauna in itsdiversified habitats and niche. The biodiversity includes true mangrove plants(34 species) and their associate plant species (40), 150 species of algae,163species of fungi, 32 species of lichen, 250 species of fishes, 7 species ofamphibian, 59 species of reptiles, around 200 species of birds, 39 species ofmammals,
besidesnumerous species of phytoplankton, zooplankton, ichthyoplankton, benthos, soilinhabiting micro arthropods and mangrove plants dependant insects. Speciescomposition, and their distributional pattern, population dynamics andcommunity structure of different groups of fauna
experiencewide range of changes spatially and temporally because of the prevailingfluctuating environmental condition. Temperature, rainfall and tidal mixingmostly make this environment unstable with a wide range of variation of majorecological parameters like salinity, pH, dissolved oxygen, nutrients, turbidityetc. from east to west in different periods of year. This ecosystem maintainsrural economy by providing timber, fuel wood, faunal resources like fishes,honey etc and protects coast from soil erosion, buffer cyclone, stormes etc,mitigates flood and maintain estuarine flow. However, the biodiversity andbasic fabric of ecosystem functioning are being threatened because of severalreasons like reclamation of deltaic island for human use, deforestation,erosion and unwanted accretion, salinity invasion, nonjudicious exploitation offishes, floral and other faunal components, ecotourism, bioinvation andpollution. Further the impact of global climate change has aggreviated theproblem. The paper discusses the biodiversity conservation strategies which arebeing adopted giving due importance to the success and failure of previousones.
Keywords: Mangrove Ecosystem,Sundarbans, Biodiversity, Deltaic Island, Conservation