Effects of temperature on uptake of aqueous metals by blue mussels Mytilus edulis from Arctic and temperate waters

Arctic waters are contaminated with metals and radionuclides from diverse sources. Here we present experimental results evaluating the bioaccumulation of dissolved metals by the mussel Mytilus edulis, widely used as a food source and also as a bioindicator of coastal contamination. We used radioisotopes to determine the uptake and excretion of Ag, Am, Cd, Co and Zn by M. edulis collected from both Arctic and temperate waters at 2 and 12 degrees C. For both mussel populations, uptake rates (k(u)) of Cd, Co and Zn were 50 to 60% slower at 2 degrees C than at 12 degrees C, mainly attributable to differences in mussel filtration rates at these temperatures, whereas uptake of Ag and Am was not affected by temperature. For both populations, the first-order loss constant for all metals from the slowest exchanging pool (k(e)) was 20 to 50% smaller at 2 degrees C than at 12 degrees C. As well, the loss of Cd and Zn was significantly slower in the temperate mussels than in Arctic mussels. Because temperature had similar effects on uptake and efflux, the concentration factor for all metals from water (CFW = k(u)/k(e)) did not vary significantly between temperatures, but CFW values for Cd and Zn in temperate mussels were 15-fold and 2.6-fold higher, respectively, than in Arctic mussels. Thus, while temperature does not exert a major influence on net bioaccumulation of aqueous metal by M. edulis, Arctic mussels may accumulate dissolved Cd and Zn to a lesser degree than temperate mussels.