Coastal Ecosystems are the world's rich storehouse of biological diversity. Mangroves considered as Green Sentinels of the Coasts are among the world?s most productive ecosystems. Indian Sundarbans is located at the apex of Bay of Bengal is noted for its rich floral and faunal diversity and the only mangrove tiger-land in the world and consists of largest mangrove concentration. The approach used in this book is that an investigation of seasonal sampling of ecological settings for the central sector of Indian Sundarbans including water quality, mangrove species with its capacity and accumulation of trace metals in water and oysters species. This study marked significant spatial variation in metal level amongst the species, water quality and ecological condition which may be due to variations in environmental conditions. The result pointed out that highly urbanization, industrialization & unplanned tourism, a negative impact has been exerted on the positive health of the aquatic system in and around the Indian Sundarbans that becoming threat for the existence of floral and faunal biodiversity.