SHORT-TERM EFFECTS OF METALS ON THE FILTRATION-RATE OF THE ZEBRA MUSSEL DREISSENA-POLYMORPHA

In order to study the short-term ecotoxicity of metals to the freshwater mussel Dreissena polymorpha, the effects of Cu, Zn and Cd on the filtration rate of this mussel were determined in laboratory experiments. Filtration rate was chosen as the endpoint, because it is a sensitive sublethal parameter compared to mortality and it is an important parameter given the ecological role D. polymorpha fulfills. The filtration rate was calculated from the decrease in algal concentration, fed to mussels in aquaria, containing different metal concentrations. The EC50 for Cu (41 mug litre-1) was lower than for Cd (388 mug litre-1) and Zn (1350 mug litre-1). The NOEC(accumulation) for the essential metal Zn was higher than for the essential metal Cu. Cadmium, a nonessential metal, was accumulated at all elevated water concentrations, so the NOEC(accumulation) was the concentration in the control water (<0.2 mug litre-1). All (no) effect concentrations found in this study were above the quality criteria set for metal concentrations in Dutch surface water, suggesting that the zebra mussel is sufficiently protected by these quality criteria.