The use of transplanted Venerupis decussata to evaluate the pollution of heavy metals and tributyltin in marinas

Live specimens of the clam Venerupis decussata were suspended in seawater o f the Mazagon Marina, located in a heavy metal polluted area at the mouth o f Huelva Estuary (SW Spain). Clams were preserved in plastic cages and subs amples were recovered every 5 days over a period of 40 days. Water from the marina was sampled every two days during the time course of the experiment . Clams and water were analyzed for metals and organotins. Results showed t he accumulation of Mn, Cu, Fe, V, Zn and tributyltin in the bivalves reachi ng an equilibrium with the surrounding water. Bioconcentration factors rang ed from 10(2) (for V) to 4x10(3) (for Cu). Clams also accumulated Al and Pb but a steady state was not reached. A first-order kinetic model was applie d to the data and results indicated that rates of accumulation differed in relation to clam size class. Clam mortality increased during the experiment and was total after 42 days which was attributed to the high concentration of Cu in seawater.