Heavy metal concentration in oyster <i>Crassostrea madrasensis</i> (Bivalvia/Anisomyaria) from the Uppanar, Vellar and Kaduviar estuaries of southeast coast of India

211-216Spatial and temporal variation in concentration of essential elements Cu and Zn and non-essential elements Cd and Pb in the whole body and organs namely gill, mantle and adductor muscle of oyster Crassostrea madrasensis were studied over a two year period. The Cu and Zn level were highest in the tissues of oysters in Kaduviar estuary. Cd and Pb concentrations were similar in all the estuaries. Metal levels in the tissues were in the order of gill > mantle > adductor muscle. Seasonal variation of tissue metal concentration was observed, with higher levels during the monsoon and lower levels in summer. Metal levels in the oyster was in the order of Zn > Cu > Pb > Cd. This order reflects the metal levels in the ambient medium