The book documents the spatio-temporal distribution of heavy metals in biotic and abiotic components with reference to hydrological characteristics of Adyar estuarine systems, Chennai. The variations in heavy metals such as copper, lead, zinc, cadmium, manganese and iron content were measured in water and sediments were mapped using Arc view GIS software. It also provides information on the Bioaccumulation of heavy metals and its associated histological perturbations in various tissues of Mugil cephalus. Temporal variation clearly indicated that the fish showed more metal accumulation during monsoon and post monsoon seasons. Though the animals exhibited severe lesions in their vital organs, it did not lead to any lethal outcome, but it should be monitored carefully to predict the genetic level modifications due to xenobiotics. Heavy metals accumulated in the biotic and abiotic components also displayed an alarming trend. Hence, It can be concluded that the untreated waste water discharged directly and indirectly into the waterways of Adyar estuary led to a reduction in waste assimilative capacity of the estuarine waters.