Bioaccumulation of trace metals in the copepod Calanoides acutus from the Weddell Sea (Antarctica): comparison of two-compartment and hyperbolic toxicokinetic models.

Bioaccumulation of Cd, Co, Cu, Ni, Pb and Zn in the Antarctic calanoid copepod Calanoides acutus (Giesbrecht, 1902) was investigated during a cruise of RV 'Polarstern' to the Weddell Sea. Main goals were to provide information on accumulation strategies of the organisms tested and to verify toxicokinetic models as a predictive tool. Except for Cd, the organisms accumulated metals upon exposure. It was possible to estimate significant model parameters of two-compartment and hyperbolic models. These models were successfully verified in a second toxicokinetic uptake study. The model verification was extended in a third uptake study with increasing external metal dosing. We found a linear increase of net uptake with external waterborne metal exposures up to 80 microg Pb l(-1), with excellent predictions of the two-compartment model. For Co both models give reasonable predictions up to 20 microg Co l(-1). Regarding Cu, Ni and Zn only hyperbolic model predictions were in good agreement with measured values up to 150 microg Cu l(-1), 80 microg Ni l(-1) and 290 microg Zn l(-1). Due to a decrease of Cd body burden in the experiments, only the hyperbolic model was applicable, leading to reliable predictions up to 20 microg Cd l(-1). These concentrations largely determine the range for which these models may serve as a predictive tool.