Local contamination, and not feeding preferences, explains elevated PCB concentrations in Labrador ringed seals (Pusa hispida).
Polychlorinated biphenyls (PCBs) in high trophic level species typically reflect the contributions of myriad sources, such that source apportionment is rarely possible. The release of PCBs by a military radar station into Saglek Bay, Labrador contaminated the local marine food web. For instance, while heavier (higher chlorinated) PCB profiles in some ringed seals (Pusa hispida) were previously attributed to this local source, differences in feeding preferences among seals could not be ruled out as a contributing factor. Herein, similar fatty acid profiles between those seals with 'local' PCB profiles and those with 'long-range' or background profiles indicate little support for the possibility that differential feeding ecologies underlay the divergent PCB profiles. Ringed seals appeared to feed predominantly on zooplankton (Mysis oculata and Themisto libellula), followed by the dusky snailfish (Liparis gibbus), arctic cod (Boreogadus saida), and shorthorn sculpin (Myoxocephalus scorpius). Principal components analysis (PCA) and PCB homolog profiles illustrated the extent of contamination of the Saglek food web, which had very different (and much heavier) PCB profiles than those food web members contaminated by 'long-range' sources. Locally contaminated prey had PCB levels that were higher (2- to 544-fold) than prey contaminated by 'long-range' sources and exceeded wildlife consumption guidelines for PCBs. The application of multivariate analyses to two distinct datasets, including PCB congeners (n=50) and fatty acids (n=65), afforded the opportunity to clearly distinguish the contribution of locally-released PCBs to a ringed seal food web from those delivered via long-ranged transport. Results from the present study strongly suggest that habitat use rather than differences in prey selection is the primary mechanism explaining the divergent PCB patterns in Labrador ringed seals.
Department of Biochemistry and Microbiology, P.O. Box 1700, Stn CSC, University of Victoria, Victoria, British Columbia V8W 2Y2, Canada; Raincoast Conservation Foundation, P.O. Box 2429, Sidney, British Columbia V8L 3Y3, Canada; Environmental Sciences Group, Royal Military College of Canada, P.O. Box 17000 Stn Forces, Kingston, Ontario K7K 7B4, Canada. Electronic address: tanya@raincoast.org.
Tanya M
TM
Brown
Department of Biology, 1355 Oxford Street, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada.
Sara J
SJ
Iverson
Great Lakes Institute of Environmental Research, University of Windsor, 401 Sunset Avenue, Windsor, Ontario N9B 3P4, Canada.
Aaron T
AT
Fisk
Institute of Ocean Sciences, Fisheries and Oceans Canada, 9860 West Saanich Road, P.O. Box 6000, Sidney, British Columbia V8L 4B2, Canada.
Robie W
RW
Macdonald
Department of Biochemistry and Microbiology, P.O. Box 1700, Stn CSC, University of Victoria, Victoria, British Columbia V8W 2Y2, Canada.
Caren C
CC
Helbing
Environmental Sciences Group, Royal Military College of Canada, P.O. Box 17000 Stn Forces, Kingston, Ontario K7K 7B4, Canada.
Ken J
KJ
Reimer
D000818:Animals; D017753:Ecosystem; D004784:Environmental Monitoring; D020387:Food Chain; D009523:Newfoundland and Labrador; D011078:Polychlorinated Biphenyls / Q000378:metabolism*; D046048:Seals, Earless / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000378:metabolism*
D014874:Water Pollutants, Chemical; D011078:Polychlorinated Biphenyls
Diet; Fatty acids; Labrador; Polychlorinated biphenyls; Pusa hispida