Dietary plasticity and broad North Atlantic origins inferred from bulk and amino acid-specific δ 15 N and δ 13 C favour killer whale range expansions into Arctic waters.

Autor: Matthews CJD; Arctic Aquatic Research Division, Fisheries and Oceans Canada, 501 University Crescent, Winnipeg, Manitoba, Canada., Yarnes CT; Stable Isotope Facility, University of California, Davis, California, USA., Lefort KJ; Fisheries and Oceans Canada, St John's, Newfoundland, Canada., Edkins TL; Arctic Aquatic Research Division, Fisheries and Oceans Canada, 501 University Crescent, Winnipeg, Manitoba, Canada., Kiszka JJ; Institute of Environment, Department of Biological Sciences, Florida International University, North Miami, Florida, USA., Ferguson SH; Arctic Aquatic Research Division, Fisheries and Oceans Canada, 501 University Crescent, Winnipeg, Manitoba, Canada.
Jazyk: angličtina
Zdroj: The Journal of animal ecology [J Anim Ecol] 2024 Aug; Vol. 93 (8), pp. 1049-1064. Date of Electronic Publication: 2024 Jul 02.
DOI: 10.1111/1365-2656.14123
Abstrakt: Killer whales (Orcinus orca) occur seasonally in the eastern Canadian Arctic (ECA), where their range expansion associated with declining sea ice have raised questions about the impacts of increasing killer whale predation pressure on Arctic-endemic prey. We assessed diet and distribution of ECA killer whales using bulk and compound-specific stable isotope analysis (CSIA) of amino acids (AA) of 54 skin biopsies collected from 2009 to 2020 around Baffin Island, Canada. Bulk ECA killer whale skin δ 15 N and δ 13 C values did not overlap with potential Arctic prey after adjustment for trophic discrimination, and instead reflected foraging history in the North Atlantic prior to their arrival in the ECA. Adjusted killer whale stable isotope (SI) values primarily overlapped with several species of North Atlantic baleen whales or tuna. Amino acid (AA)-specific δ 15 N values indicated the ECA killer whales fed primarily on marine mammals, having similar glutamic acid δ 15 N-phenylalanine δ 15 N (δ 15 N Glx-Phe ) and threonine δ 15 N (δ 15 N Thr ) as mammal-eating killer whales from the eastern North Pacific (ENP) that served as a comparative framework. However, one ECA whale grouped with the fish-eating ENP ecotype based δ 15 N Thr . Distinctive essential AA δ 13 C of ECA killer whale groups, along with bulk SI similarity to killer whales from different regions of the North Atlantic, indicates different populations converge in Arctic waters from a broad source area. Generalist diet and long-distance dispersal capacity favour range expansions, and integration of these insights will be critical for assessing ecological impacts of increasing killer whale predation pressure on Arctic-endemic species.
(© 2024 The Author(s). Journal of Animal Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society.)
Databáze: MEDLINE
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