We analyzed for selenium (Se) and heavy metals in greater scaups (Aythya marila) and surf scoters (Melanitta perspicillata) collected from southern San Francisco Bay in March and April 1982. There were no differences (P > 0.05) between species for liver concentrations of silver (Ag), mercury (Hg), or lead (Pb). Copper (Cu) (P < 0.001) and zinc (Zn) (P < 0.01) levels were higher in scaups, whereas Se was higher in scoters (P < 0.001). Chromium (Cr) and nickel (Ni) occurred in < 50% of the samples, and there was no difference (P > 0.05) between the 2 species. The geometric mean cadmium (Cd) concentration in scoter kidneys (24.6 ppm, dry wt) was higher than in scaups (15.5 ppm) (0.1 > P > 0.05). Liver concentrations of Hg and Se were correlated (P < 0.01). The toxicological significance of some elements in these species is not known. However, Se levels in scoters (34.4 ppm, dry wt) were similar to those in livers of dabbling ducks (Anas spp.) in the nearby San Joaquin Valley where reproduction was impaired severely.
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Selenium and heavy metals in San Francisco Bay diving ducks