Trace Elements in Sea Ducks of the Alaskan Arctic Coast: Patterns of Variation Among Species, Sexes, and Ages.

ABSTRACT

Climate change and increasing industrialization in the Arctic call for the collection of reference data for assessing changes in contaminant levels. For migratory birds, measuring and interpreting changes in trace element burdens on Arctic breeding areas require insights into factors such as sex, body size, or wintering area that may modify patterns independently of local exposure. In the Alaskan Arctic, we determined levels of trace elements in liver and kidney of common eiders (Somateria mollissima) and long-tailed ducks (Clangula hyemalis) from the Prudhoe Bay oil field and of king eiders (S. spectabilis) and threatened spectacled eiders (S. fischeri) and Steller's eiders (Polystica stelleri) from near the town of Barrow. Small-bodied Steller's eiders and long-tailed ducks from different locations had similarly low levels of selenium (Se), cadmium (Cd), and copper (Cu), perhaps reflecting high mass-specific rates of metabolic depuration during long spring migrations through areas of low exposure. In larger species, Se, Cd, and Cu concentrations were higher in adults than juveniles suggesting that these elements were acquired in nonbreeding marine habitats. Adult male spectacled eiders had exceptionally high Se, Cd, and Cu compared with adult females, possibly because of depuration into eggs and longer female occupancy of nonmarine habitats. Adult female common eiders and juvenile long-tailed ducks at Prudhoe Bay had high and variable levels of Pb, potentially due to local exposure. Explanations for substantial variations in Hg levels were not apparent. Further research into reasons for differing element levels among species and sexes will help clarify the sources, pathways, and risks of exposure.