THE ASSIMILATION OF CONTAMINANTS FROM SUSPENDED SEDIMENT AND ALGAE BYTHE ZEBRA MUSSEL, DREISSENA-POLYMORPHA

Since their invasion into the Great Lakes, zebra mussels, Dreissena po lymorpha, have increased the water clarity in Lake St. Clair and Lake Erie due to their extensive particle filtration. Because these particl es contain sorbed contaminants, the potential for contaminant accumula tion from both suspended sediment and algae were examined. Sediment or algae were dosed with selected radiolabeled polycyclic aromatic hydro carbon congeners and/or hexachlorobiphenyl (HCBP). Assimilation effici encies were measured and depended on food quality. Zebra mussels, 17 /- 2 mm long, assimilated 58.3 +/- 13.5 % of the pyrene and 44.7 +/- 5 .8 % of the benzo(a)pyrene (BaP) from sediment particles with a partic le clearance rate of 493 -897 ml/g tissue/h. However, assimilation eff iciencies were 91.7 +/- 3.7 % for pyrene, 91.9 +/- 1.4 % for BaP, 96.6 +/- 1.4 % for chrysene, and 97.7 +/- 0.5 % for HCBP from suspended al gae. Algal particle clearance rates for the mussels ranged from 47 -14 3 ml/g tissue/h. Thus, zebra mussels efficiently accumulated non-polar contaminants sorbed to algae, while a smaller fraction of the sedimen t-associated contaminant was bioavailable. Furthermore, the contaminan ts sorbed onto suspended sediment particles were quickly removed from the water and deposited as pseudofeces. The pseudofeces production was positively correlated with filtration rate and suspended particle con centrations. Published by Elsevier Science Ltd.