WP5 Wildlife Ecotoxicology
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() Polybrominated diphenyl ethers (PBDEs) and organochlorine pesticides in salmon-eating grizzly bears of British Columbia.

Christensen, J1, 2, MacDuffee, M2, Whiticar, M2, Ross, P1, 1 Fisheries and Oceans Canada, Sidney, BC, Canada2 University of Victoria, Victoria, BC, Canada

ABSTRACT- The coastal grizzly bears (Ursus arctos horribilis) of British Columbia (BC, Canada) rely heavily on salmon returning from the Pacific Ocean, whereas interior bears generally do not have access to this marine-derived food source. Since salmon have been shown to accumulate persistent organic pollutants (POPs) from the North Pacific Ocean, we hypothesized that salmon consumption by grizzly bears would be reflected by an increase in their POP burden. To test this hypothesis we collected hair and fat tissue from grizzlies at various locations around BC to compare salmon-eating (coastal) grizzlies to non-salmon-eating (interior) grizzlies. We characterized the feeding habits for each bear sampled by measuring the stable isotopic signature of C13 and N15 in hair. The positive relationship between C13 and N15 isotopic ratios suggests that the majority of the meat portion of the diet of coastal grizzlies is coming from salmon, rather than from terrestrial or freshwater sources. By contrast, stable isotope ratios revealed that interior bears have an almost exclusive vegetarian diet. We found a positive relationship between C13 and N15 isotope ratios and most OC pesticide and PBDE congener concentrations in bear tissue. However, the coastal grizzly PBDE congener profile (47 > 209 > 99 > 100 > 153 > 28/33) differed from that of interior grizzly (209 > 47 > 99 > 100 > 153 > 154), likely reflecting differences in source, transport, fate and trophic transfer functions between two structurally different food webs. Our results indicate that Pacific salmon represent a vector that delivers both OC pesticides and PBDEs to BC coastal grizzly bears.

Key words: PBDE, Ursus arctos horribilis, organochlorines, isotopes

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