title: Regional contamination versus regional dietary differences: understanding geographic variation in brominated and chlorinated contaminant levels in polar bears.
abstract: The relative contribution of regional contamination versus dietary differences to geographic variation in polar bear (Ursus maritimus) contaminant levels is unknown. Dietary variation between Alaska, Canada, East Greenland, and Svalbard subpopulations was assessed by muscle nitrogen and carbon stable isotope (δ(15)N, δ(13)C) and adipose fatty acid (FA) signatures relative to their main prey (ringed seals). Western and southern Hudson Bay signatures were characterized by depleted δ(15)N and δ(13)C, lower proportions of C(20) and C(22) monounsaturated FAs and higher proportions of C(18) and longer chain polyunsaturated FAs. East Greenland and Svalbard signatures were reversed relative to Hudson Bay. Alaskan and Canadian Arctic signatures were intermediate. Between-subpopulation dietary differences predominated over interannual, seasonal, sex, or age variation. Among various brominated and chlorinated contaminants, diet signatures significantly explained variation in adipose levels of polybrominated diphenyl ether (PBDE) flame retardants (14-15%) and legacy PCBs (18-21%). However, dietary influence was contaminant class-specific, since only low or nonsignificant proportions of variation in organochlorine pesticide (e.g., chlordane) levels were explained by diet. Hudson Bay diet signatures were associated with lower PCB and PBDE levels, whereas East Greenland and Svalbard signatures were associated with higher levels. Understanding diet/food web factors is important to accurately interpret contaminant trends, particularly in a changing Arctic.
authors.affiliation: Ecotoxicology and Wildlife Health Division, Science and Technology Branch, Environment Canada, Ottawa, Ontario K1A 0H3, Canada. melissaamckinney@gmail.com
authors.forename: Melissa A
authors.initials: MA
authors.lastname: McKinney
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Letcher
authors.forename: Jon
authors.initials: J
authors.lastname: Aars
authors.forename: Erik W
authors.initials: EW
authors.lastname: Born
authors.forename: Marsha
authors.initials: M
authors.lastname: Branigan
authors.forename: Rune
authors.initials: R
authors.lastname: Dietz
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Evans
authors.forename: Geir W
authors.initials: GW
authors.lastname: Gabrielsen
authors.forename: Derek C G
authors.initials: DC
authors.lastname: Muir
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Peacock
authors.forename: Christian
authors.initials: C
authors.lastname: Sonne
mesh_terms: D000413:Alaska; D000818:Animals; D017605:Bromine Compounds / Q000378:metabolism*; D002170:Canada; D017606:Chlorine Compounds / Q000378:metabolism*; D004032:Diet / Q000706:statistics & numerical data; D004784:Environmental Monitoring; D004785:Environmental Pollutants / Q000378:metabolism*; D005260:Female; D005411:Flame Retardants / Q000378:metabolism; D006116:Greenland; D055768:Halogenated Diphenyl Ethers / Q000378:metabolism; D011078:Polychlorinated Biphenyls / Q000378:metabolism; D013538:Svalbard; D001503:Ursidae / Q000378:metabolism*
chemical_list: D017605:Bromine Compounds; D017606:Chlorine Compounds; D004785:Environmental Pollutants; D005411:Flame Retardants; D055768:Halogenated Diphenyl Ethers; D011078:Polychlorinated Biphenyls