The effluents discharged from the Thermal Power Station at Tuticorin, caused various physicochemical and biological changes in the Bay waters. The preliminary survey indicated that the temperature of the water was high upto 2 km from the discharging point. Upto 1.5 km there were no vegetation and from 0.5 to 2.5 km distance, dead shells could only be collected. The scarcity of the biota revealed the ill effects of the fly ash deposits and turbidity coupled with enhanced temperature in the Bay waters of Tuticorin.