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Marine Ecology Progress Series

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MEPS 728:163-182 (2024)  -  DOI:

Comparison of feeding niches between Arctic and northward-moving sub-Arctic marine mammals in Greenland

Haley Land-Miller1, Anna M. Roos2,3, Malene Simon2, Rune Dietz4, Christian Sonne4, Sara Pedro5, Aqqalu Rosing-Asvid6, Frank F. Rigét2,4, Melissa A. McKinney1,*

1Department of Natural Resource Sciences, McGill University, Sainte-Anne-de-Bellevue, QC H9X 3V9, Canada
2Greenland Climate Research Centre, Greenland Institute of Natural Resources, PO Box 570, Nuuk 3900, Greenland
3Department of Environmental Research and Monitoring, Swedish Museum of Natural History, 10405 Stockholm, Sweden
4Department of Ecoscience, Arctic Research Centre, Aarhus University, Frederiksborgvej 399, Roskilde 4000, Denmark
5Department of Biology, Université Laval, Québec City, QC G1V 0A6, Canada
6Department of Birds and Mammals, Greenland Institute of Natural Resources, PO Box 570, Nuuk, 3900, Greenland
*Corresponding author:

ABSTRACT: The climate change-induced northward movement of sub-Arctic marine mammals increases their range overlap and interactions with native Arctic species. We compared feeding patterns of 11 marine mammal species (4 Arctic and 7 sub-Arctic) in Greenland using stable isotope ratios and fatty acid signatures, and also assessed the effects of lipid extraction on stable isotope ratios. Lipid extraction showed limited increases in δ13C, intermediate effects on δ15N, and significant depletion of δ34S in muscle of some marine mammals. Arctic and sub-Arctic species differed in stable isotope ratios, indicating some use of separate food resources, while likely also reflecting baseline isotopic variation. Proportions of some of the most abundant fatty acids (20:1n9, 22:1n11, 20:5n3, 22:6n3) varied between Arctic and sub-Arctic species, indicating that sub-Arctic species rely mostly on a pelagic food web, while Arctic species exploit an ice-associated and benthic food web, although the sub-Arctic harp and hooded seals and Arctic narwhal showed opposite patterns. Sub-Arctic species had the largest niche breadths, implying diet flexibility and potential to adapt to further changes. Overall patterns in dietary tracers demonstrate separation of feeding niches between most Arctic and sub-Arctic marine mammals, but potential niche overlap and shared food resources for some species. Sub-Arctic seal species overlap the feeding niches of native Arctic species the most of all range-shifters, and of Arctic species, narwhal appear to be the most vulnerable to niche overlap and potential food competition with northward-shifting species.

KEY WORDS: Foraging · Niche breadth · Whale · Seal · Lipid extraction · 13C · 15N · 34S · Stable isotopes · Fatty acids

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Cite this article as: Land-Miller H, Roos AM, Simon M, Dietz R and others (2024) Comparison of feeding niches between Arctic and northward-moving sub-Arctic marine mammals in Greenland. Mar Ecol Prog Ser 728:163-182.

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