Variation in heavy metals concentration in the edible oyster Crassostrea madrasensis, clam Polymesoda erosa and grey mullet Liza aurata from coastline of India

Abstract

Seven trace metals Zinc (Zn), Iron (Fe), Manganese (Mn), Lead (Pb), Nickel (Ni), Cobalt (Co) and Cadmium (Cd) variation and (or) accumulation in mullet fish L. aurata, edible bivalve oyster C. madrasensis from Gosthany estuary, east coast and edible clam Polymesoda erosa from Mandovi estuary, West coast of India have been studied by Atomic Absorption Spectrophotometry (AAS). Overall trend in bioaccumulation was revealed with the following decreasing order Zn more than Fe more than Mn more than Pb more than Ni more than Co more than Cd. Among all the metals Fe showed highest percentage (79.5) in clam followed by Zn (65.95) in oyster, which suggest and indicates that bivalve accumulates higher metal concentrations compared to fish. Four metals viz, Fe, Ni, Co and Mn showed high accumulation in gills of Mullet Liza aurata which is 10 times higher compared to muscle tissue, where as Pb and Zn were high in Oyster. 85 percent of the metals studied showed high concentration in gills. This study indicates the factors like feeding habits, habitat, size and regulatory ability plays important role in metal bioaccumulation shown by two different ecological nitches.