Effect of Copper and Lead in Freshwater Mollusc Corbicula sp.

Laboratory experiments were carried out on adult freshwater bivalve Corbicula sp. to assess mortality and behavioral changes when exposed to two heavy metals copper (Cu) and lead (Pb). In this study acute toxicity tests of 24 – 96 hours were conducted to determine the different lethal concentrations of the metals. The mortality was recorded after every 24, 48, 72, and 96 hours. The criteria of death were white mucus secretion, immobilization and lack of response to touching of the body parts, floating on the surface of the water, and valves remain open. During the study behavioral changes were also observed. The median lethal concentration (LC50) values at 24, 48, 72, and 96 h of Cu were found to be 75.949, 37.172, 21.651, and 14.884 mg L-1, and of Pb were 1029.741, 323.714, 269.906, and 236.108 mg L-1, respectively for Corbicula sp. The implications of these findings on the occurrence of this species in various freshwater ecosystems of Barak Valley is discussed.