Concentrations of mercury and polychlorinated biphenyls in blood of Southern Beaufort Sea polar bears (Ursus maritimus) during spring: variations with lipids and stable isotope (15N, 13C) values
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abstract
Polar bears ( Ursus maritimus Phipps, 1774) are exposed to heavy metal and lipophilic contaminants that are known to bioaccumulate and biomagnify. Few studies concurrently report both chemical classes in the same individuals and are thus unable to assess drivers of observed tissue concentrations, and the potential adverse biological responses to combined exposures. We examined blood concentrations of mercury (Hg) and the sum of seven polychlorinated biphenyls (7PCB) from free-ranging Southern Beaufort Sea polar bears to assess which factors contributed to variations among cohorts (adult males, adult females, young) during spring. Concentrations of Hg ranged from 10.3 to 228.0ng/g wet mass, but mean concentrations were similar between males and females independent of age. Concentrations of 7PCB (range 2.0132.8ng/g wet mass) were greater among females and young than among males. Toxicant concentrations were related to packed cell 15N, an estimate of trophic position, after the inclusion of packed cell 13C. Concentrations of 7PCB were also positively correlated with concentrations of neutral lipids (triglycerides and free fatty acids) and inversely correlated to body condition indices. Elevated concentrations of toxicants and lower body condition indices in females and young compared with males may be a sentinel to a changing arctic environment. Further assessment of the potential adverse health impacts of contaminants and nutritional stress in these cohorts is warranted.
