Feeding and biological differences induce wide variation in legacy persistent organic pollutant concentrations among toothed whales and polar bear in the Arctic

Adam F Pedersen; Rune Dietz; Christian Sonne; Robert J Letcher; Anna M Roos; Malene Simon; Aqqalu Rosing-Asvid; Steven H Ferguson; Melissa A McKinney

doi:10.1016/j.scitotenv.2023.168158

Feeding and biological differences induce wide variation in legacy persistent organic pollutant concentrations among toothed whales and polar bear in the Arctic

Sci Total Environ. 2023 Oct 27:168158. doi: 10.1016/j.scitotenv.2023.168158. Online ahead of print.

Authors

Adam F Pedersen¹, Rune Dietz², Christian Sonne², Robert J Letcher³, Anna M Roos⁴, Malene Simon⁵, Aqqalu Rosing-Asvid⁶, Steven H Ferguson⁷, Melissa A McKinney⁸

Affiliations

¹ Department of Natural Resource Sciences, McGill University, Sainte-Anne-de-Bellevue, QC H9X 3V9, Canada. Electronic address: adam.pedersen@mail.mcgill.ca.
² Department of Ecoscience, Arctic Research Centre, Aarhus University, Roskilde DK-4000, Denmark.
³ Ecotoxicology and Wildlife Health Division, Environment and Climate Change Canada, National Wildlife Research Centre, Carleton University, Ottawa, ON K1A 0H3, Canada.
⁴ Greenland Climate Research Centre, Greenland Institute of Natural Resources, Nuuk GL-3900, Greenland; Department of Environmental Research and Monitoring, Swedish Museum of Natural History, 104 05 Stockholm, Sweden.
⁵ Greenland Climate Research Centre, Greenland Institute of Natural Resources, Nuuk GL-3900, Greenland.
⁶ Department of Birds and Mammals, Greenland Institute of Natural Resources, Nuuk GL-3900, Greenland.
⁷ Arctic Aquatic Research Division, Fisheries and Oceans Canada, Winnipeg, MB R3T 2N6, Canada.
⁸ Department of Natural Resource Sciences, McGill University, Sainte-Anne-de-Bellevue, QC H9X 3V9, Canada.

PMID: 39491187
DOI: 10.1016/j.scitotenv.2023.168158

Abstract

Polar bear and toothed whales in the Arctic exhibit orders of magnitude differences in concentrations of legacy persistent organic pollutants (POPs), which may be attributed to comparisons made across regions and different time frames. These interspecific differences could be influenced by variations in biological susceptibility, including differences in xenobiotic biotransformation between polar bear, from the order Carnivora, and toothed whales, from the order Artiodactyla, as well as ecological factors, such as variation in feeding patterns. Here, we analyzed samples from subsistence-harvested toothed whales and polar bear in East Greenland collected between 2012 and 2021 and quantitatively compared interspecific differences in blubber/adipose polychlorinated biphenyl (PCB) and organochlorine (OC) pesticide concentrations. We further determined fatty acid (FA) signatures as dietary tracers to evaluate how feeding patterns influence POP concentrations relative to the influence of biological differences between taxa. Killer whale exhibited the highest mean concentrations of ΣPCBs (57.0 ± 14.0 mg/kg lw), Σdichlorodiphentlytrichloroethanes (ΣDDTs; 55.7 ± 13.1), and Σchlordanes (ΣCHLs; 23.1 ± 5.6 mg/kg lw), while polar bear showed the second highest concentrations for ΣPCBs (12.5 ± 1.3 mg/kg lw), but comparable or even lower levels of all OCs relative to narwhal and pilot whale. Linear models using FA patterns as explanatory variables for POP concentrations demonstrated that, for ΣPCBs, diet differences explained most of the variation. Conversely, biological differences explained more of the variation for most OCs, especially for DDT, for which polar bear showed the lowest concentrations despite feeding on similarly high trophic position prey as killer whale. This novel quantitative comparison confirms that significant differences in legacy POP concentrations occur among Arctic marine mammal predators. Furthermore, the drivers of these differences are contaminant-specific, with feeding patterns primarily influencing PCB concentrations, taxa-specific biological characteristics (e.g., in xenobiotic biotransformation capacity) affecting DDT concentrations, and both factors contributing to variations in other OCs.

Keywords: Fatty acids; Killer whale; Long-finned pilot whale; Narwhal; POPs; Polar bear.