ALBERT

Description: An understanding of the adaptability of belugas (Delphinapterus leucas) to changing ice conditions is required to interpret and predict possible changes in habitat selection in response to projected loss of sea ice throughout the circumpolar Arctic. We analyzed beluga observations made during spring aerial surveys for ringed seals conducted from 1975 to 1979 in the eastern Beaufort Sea. Despite interannual variability in the extent and distribution of sea ice, belugas consistently selected areas with water depths of 200-500 m and heavy ice concentrations (8/10 to 10/10) while areas of open water to light ice concentrations (0/10 to 1/10) were not selected. Belugas were also found in proximity to regions with 〉0.5 degrees seafloor slope which include the continental slope and other areas with the potential for oceanographic upwellings. In most years (4 of 5), fast-ice edges and coastal areas were not selected. In the lightest ice year analyzed, belugas showed less specificity in habitat selection as their distribution expanded and shifted shoreward to fast-ice edges. The observed distribution is discussed in terms of predator-prey relationships particularly with reference to beluga feeding on polar cod (Boreogadus saida). More research is required to examine and compare possible changes in distribution since the late 1970s and to investigate the factors driving the patterns described.

Description: Adipose tissue was sampled from the western Hudson Bay (WHB) subpopulation of polar bears at intervals from 1991 to 2007 to examine temporal trends of PCB and OCP levels both on an individual and sum-contaminant basis. We also determined levels and temporal trends of emerging polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCD), polybrominated biphenyls (PBBs) and other current-use brominated flame retardants. Over the 17-year period, sum DDT (and p,p'-DDE, p,p'-DDD, p,p'-DDT) decreased (-8.4%/year); alpha-hexachlorocyclohexane (alpha-HCH) decreased (-11%/year); beta-HCH increased ( + 8.3%/year); and sum PCB and sum chlordane (CHL), both contaminants at highest concentrations in all years (〉1 ppm), showed no distinct trends even when compared to previous data for this subpopulation dating back to 1968. Some of the less persistent PCB congeners decreased significantly (-1.6%/year to -6.3%/year), whereas CB153 levels tended to increase (+ 3.3%/year). Parent CHLs (c-nonachlor, t-nonachlor) declined, whereas non-monotonic trends were detected for metabolites (heptachlor epoxide, oxychlordane). sum chlorobenzene, octachlorostyrene, sum mirex, sum MeSO2-PCB and dieldrin did not significantly change. Increasing sum PBDE levels (+13%/year) matched increases in the four consistently detected congeners, BDE47, BDE99, BDE100 and BDE153. Although no trend was observed, total-(alpha)-HBCD was only detected post-2000. Levels of the highest concentration brominated contaminant, BB153, showed no temporal change. As long-term ecosystem changes affecting contaminant levels may also affect contaminant patterns, we examined the influence of year (i.e., aging or "weathering" of the contaminant pattern), dietary tracers (carbon stable isotope ratios, fatty acid patterns) and biological (age/sex) group on congener/metabolite profiles. Patterns of PCBs, CHLs and PBDEs were correlated with dietary tracers and biological group, but only PCB and CHL patterns were correlated with year. DDT patterns were not associated with any explanatory variables, possibly related to local DDT sources. Contaminant pattern trends may be useful in distinguishing the possible role of ecological/diet changes on contaminant burdens from expected dynamics due to atmospheric sources and weathering.