Coupling contaminants with demography: effects of lead and selenium in Pacific common eiders.
We coupled intensive population monitoring with collection of blood samples from 383 nesting Pacific common eiders (Somateria mollisima v-nigrum) at two locations in Alaska (USA) from 2002 to 2004. We investigated annual, geographic, and within-season variation in blood concentrations of lead and selenium; compared exposure patterns with sympatrically nesting spectacled eiders (Somateria fischeri); and examined relationships with clutch size, egg viability, probability of hatching, and apparent survival of adult females. Lead concentrations were elevated in 3.6% of females, and all individuals exhibited elevated selenium, most (81%) at concentrations associated with death in captive waterfowl. Blood lead and selenium concentrations varied both within and among site-years and were lower than those of spectacled eiders. During incubation, blood lead concentrations in females increased significantly (possibly via re-release of stored lead from bone), whereas selenium concentrations decreased (likely because of natural excretion). Probability of a nest containing at least one nonviable egg was positively related to blood selenium in hens, but adverse effects in other life-history variables were not supported. Although reproduction appeared to be sensitive to selenium toxicity, our data suggest that high rates of nonviability are unlikely in this population and that selenium-related reductions to clutch size would be inconsequential at the scale of overall population dynamics. We conclude that Pacific common eiders and other wild marine birds likely have higher selenium tolerances than freshwater species and that interspecific differences in exposure levels may reflect differences in reproductive strategies.
Department of Biology and Wildlife, University of Alaska, Fairbanks, 211 Irving I, Fairbanks, Alaska 99775, USA. heather_wilson@fws.gov
Heather M
HM
Wilson
Paul L
PL
Flint
Abby N
AN
Powell
D000818:Animals; D004372:Ducks; D004785:Environmental Pollutants / Q000097:blood*; D005260:Female; D007854:Lead / Q000097:blood*; D008297:Male; D013058:Mass Spectrometry; D012643:Selenium / Q000097:blood*; D016019:Survival Analysis
D004785:Environmental Pollutants; D007854:Lead; D012643:Selenium