The authors investigated the spatial and temporal variability of concentrations of Fe, Mn, Zn, Cu, Pb, Cd, and Ni in soft tissues of mytilids of Amur Bay, an aquatory [underwater territory] subjected to a considerable anthropogenic load. It was shown that the mytilids' trace-element composition is controlled mostly by the contents of metals in abiotic components of the ecosystem and by the filtration rate. It was discovered that from May to October metals are accumulated in accordance with the rate of delivery of material from dry, land. In this case, the scale of seasonal variability is greater in silted and polluted biotopes. However, in the areas of maximum pollution the accumulation of metals is limited, due to a reduction in the filtration rate.