title: Sea ice-associated decline in body condition leads to increased concentrations of lipophilic pollutants in polar bears (Ursus maritimus) from Svalbard, Norway.
abstract: Global climate changes are magnified in the Arctic and are having an especially dramatic effect on the spatial and temporal distribution and the thickness traits of sea ice. Decline of Arctic sea ice may lead to qualitative and/or quantitative changes in diet and reduced body condition (i.e. adipose tissue stores) of ice-associated apex predators such as polar bears (Ursus maritimus). This may further affect their tissue concentrations of lipophilic pollutants. We determined how variations in adipose tissue stores associated to both breeding status and spatial changes in sea ice conditions and diet influence concentrations and biotransformation of lipophilic persistent organic pollutants (POPs). We collected 112 blood and fat samples from female polar bears (Ursus maritimus) of different breeding status (alone, with cubs of the year, or with yearlings) during two seasons (April and September) in 2012 and 2013 at three locations of Svalbard, Norway, with contrasted sea ice conditions. We inferred diet from nitrogen and carbon stable isotope ratios in red blood cells and fatty acid composition in adipose tissue. Relative to diet, body condition, which was negatively related to sea ice extent at both temporal and spatial scales, was the most important predictor for concentrations of POPs in plasma and fat, whereas diet showed a minor influence. Additionally, fatter females were more efficient at biotransforming PCBs than were leaner ones. Breeding status influenced the concentrations of less lipophilic compounds such as β-hexachlorocyclohexane, which were lower in females with yearlings, probably due to excretion into milk and subsequent offloading to young. In conclusion, our results indicate that declining sea ice indirectly leads to increased concentrations of lipophilic pollutants in polar bears mediated through reduced feeding opportunities and declining body condition rather than changes in diet composition.
authors: Norwegian Polar Institute, Fram Centre, Tromsø, Norway. Electronic address: tartu.sabrina@gmail.com.
authors: Sabrina
authors: S
authors: Tartu
authors: Norwegian Polar Institute, Fram Centre, Tromsø, Norway; UiT-The Arctic University of Norway, Department of Arctic and Marine Biology, Tromsø, Norway.
authors: Sophie
authors: S
authors: Bourgeon
authors: Norwegian Polar Institute, Fram Centre, Tromsø, Norway.
authors: Jon
authors: J
authors: Aars
authors: Norwegian Polar Institute, Fram Centre, Tromsø, Norway.
authors: Magnus
authors: M
authors: Andersen
authors: Norwegian University of Life Science, Campus Adamstua, Oslo, Norway; York University, Faculty of Environmental Studies, Toronto, ON, Canada.
authors: Anuschka
authors: A
authors: Polder
authors: York University, Faculty of Environmental Studies, Toronto, ON, Canada.
authors: Gregory W
authors: GW
authors: Thiemann
authors: University of Alaska Anchorage, Department of Biological Sciences, Anchorage, AK, USA; University Center in Svalbard, Longyearbyen, Svalbard, Norway.
authors: Jeffrey M
authors: JM
authors: Welker
authors: Norwegian Polar Institute, Fram Centre, Tromsø, Norway.
authors: Heli
authors: H
authors: Routti
mesh_terms: D000273:Adipose Tissue / Q000737:chemistry; D000818:Animals; D001110:Arctic Regions; D004785:Environmental Pollutants / Q000032:analysis*; D005260:Female; D057232:Global Warming; D046448:Ice Cover; D010949:Plasma / Q000737:chemistry; D013538:Svalbard; D001503:Ursidae
chemical_list: D004785:Environmental Pollutants
keywords: Arctic; Biotransformation; Energy stores; Global warming; Legacy POPs; Maternal transfer