WASTE management strategies adopted in India have failed to keep pace with the industrial growth and urbanization. This has resulted in the accumulation of contaminants with a consequent loss in coastal marine biodiversity, for the past few decades. Estimates indicate that Mumbai city itself discharges around 2200 MLD of waste to the coastalwaters. Similar is the case with some of the major cities such as Chennai, Kolkata and Visakhapatnam and the industrial areas of Gujarat, Pondicherry and Orissa, where the coastal and estuarine waters remain in degraded condition.

The responses of estuarine and marine organisms to waste input are manifold, but can mainly be classified on four levels of biological organization, i.e. cellular, organismal, population and community basis (Table 1). The earliest detectable changes inside the cell, in response to toxic environmental chemicals (xenobiotics), involve subcellular organelles such as lysosomes, endoplasmic reticulum and mitochondria. Significant impact to pollution exposure at cellular level are the specific biochemical responses, such as production of cytochrome P450-mediated system of mixed function oxygenation of organic compounds, antioxidants and metal-binding proteins, as also genetic changes.

Pollution along the Indian coast

 Many pollution impacts on marine communities can be traced directly to the industrialized centres, which release an array of chemical contaminants to effluent systems. Others are more difficult to delineate because they are largely derived from contaminants supplied by diffused source such as run-off from land and atmospheric fallout. Of even greater concern have been the adverse environmental effects associated with waste-disposal activities, particularly sewage sludge and dredged spoil dumping, oil spills and leakages as well as municipal and industrial waste-water discharges. 

These wastes often contain a wide range of contaminants such as petroleum hydrocarbons, chlorinated hydrocarbons and heavy metals. Some of the previous studies in the Arabian Sea have shown that the petroleum hydrocarbons ranged from 1.8 to 11.1 mg/l in water, 1.84 to 5.81 mg/g dry wt in sediments and 0.33 to 3.67 mg/g wet wt in fish, total DDT in zooplankton samples in the Arabian Sea varied from 0.083 to 0.563 mg/l. In the coastal waters off Mumbai, which receive large amounts of domestic and industrial waste, the Hg content fluctuated between 0.12 to 1.4 mg/l, in sediments from 0.08 to 0.36 mg/g dry wt and in fish muscle at Thana Creek from 0.217 to 0.512 mg/g wet wt. Also, off Karwar (Karnataka) Hg was recorded as high as 2.68 mg/l in water and 1.32 mg/g dry wt in sediment.

Eutrophication of estuarine waters often culminates into anaerobiosis, toxic algal blooms, mass kills of benthic and epibenthic organisms and change in the abundance and diversity patterns of fish. But the extent to which contaminants enter the biotic components and interact with communities in terms of its physiological and biochemical concerns is a problem under investigation.