Accumulation, Metabolism, and Food-Chain Transfer of Chlorinated and Brominated Contaminants in Subadult White Whales (Delphinapterus leucas) and Narwhals (Monodon monoceros) From Svalbard, Norway

Abstract

The concentrations and patterns of polychlorinated biphenyls (PCBs), chlorinated pesticides, and polybrominated diphenyl ethers (PBDEs) were studied in white whales (Delphinapterus leucas) and narwhals (Monodon monoceros) from Svalbard, Norway. In addition, their main food items were included in the study. In the whales, a broad range of pollutants was found in relatively high concentrations. PCBs and pesticides were approximately 3000 and 8000 ng/g lipid, respectively, for white whales and three times higher for narwhals. PBDEs 47 were approximately 70 ng/g lipid for white whales and 170 ng/g lipid for narwhals. Compared with other marine mammals from the same area, contaminant levels are among the highest levels ever measured. These high levels are likely in part because of a decreased capacity to metabolize contaminants. Metabolic indices indicated that most compounds accumulate to the same degree in white whales and narwhals, but for some toxaphenes and chlordanes, narwhals might have a decreased metabolism and consequently a higher accumulation. The three-times-higher contaminant levels in blubber of narwhals was further explained by substantially higher contaminant levels in their more benthic diet. The high levels and broad pattern of accumulating pollutants make white whales and narwhals excellent indicators for a wide range of contaminants in the Arctic.

Accumulation and transfer of contaminants in killer whales (Orcinus orca) from Norway: Indications for contaminant metabolism

“…Similar to most chlordanes, the MI below 1 for DDE indicates that this DDT metabolite might be broken down to some degree in killer whales, a similar result as was found in white whales [19]. Differences in HOC patterns between herring and whales and low MIs suggested that most chlordanes, except trans-nonachlor, can be metabolized in killer whales.…”

“…This most likely is linked to their main food source, herring, which showed 10 to 15 times higher HOC levels than, for example, polar cod from Svalbard [19], the dominant food from the white whales. This most likely is linked to their main food source, herring, which showed 10 to 15 times higher HOC levels than, for example, polar cod from Svalbard [19], the dominant food from the white whales.…”

“…If calculated based on whole animals, biomagnification factor and MI have been shown to be very similar [37]. Compared to white whales from Svalbard [19], the MIs in killer whales suggested a similar accumulation for persistent PCB from group I and IIIB, i.e., MI was approximately one in both species, indicating accumulation similar to PCB 153. Nevertheless, due to their close geographic association with the herring schools year-round, it is widely assumed that by far the main part of the killer whales' diet consists of herring [12,13].…”

“…Approximately 0.5 to 1 g of the samples was used and analyzed as described previously [19]. Whale blubber and fish samples were analyzed for PCBs (32 congeners), toxaphenes (6 congeners), dichlorodiphenyldichloro-ethylene (DDE), chlordanes, and PBDEs (10 congeners).…”

METABOLIC TRANSFORMATION SHAPES POLYCHLORINATED BIPHENYL AND POLYBROMINATED DIPHENYL ETHER PATTERNS IN BELUGA WHALES (DELPHINAPTERUS LEUCAS)

“…Our metabolic index results confirm the metabolism of BDEs 28 and 47 and the lack of metabolism for BDE 183 but show a high metabolic capacity for most other congeners. Similar studies have consistently reported metabolic index values below 1 for most PBDE congeners in marine mammals, including beluga, narwhal ( Monodon monoceros ), killer whales ( Orcinus orca ), ringed seals ( Pusa hispida ), and polar bears ( Ursus maritimus ) . This discrepancy suggests that either time constraints in the in vitro tests result in an underestimation of BDE metabolism or estimating congener‐specific metabolism of PBDEs in free‐ranging marine mammals is problematic due to the complexities and non–steady state of this contaminant in Arctic marine food webs.…”