Niches of marine mammals in the European Arctic

Type Article
Date 2022-03
Language English
Author(s) Mackenzie KirsteenORCID1, 2, 3, Lydersen C.1, Haug T.2, Routti H.1, Aars J.1, Andvik C.M.4, Borgå K.4, Fisk A.T.5, Meier S.6, Biuw M.2, Lowther A.D.1, Lindstrøm U.2, 7, Kovacs K.M.1
Affiliation(s) 1 : Norwegian Polar Institute, Fram Centre, Hjalmar Johansens Gate 14, Tromsø 9007, Norway
2 : Institute of Marine Research, Fram Centre, Hjalmar Johansens Gate 14, Tromsø 9007, Norway
3 : Ifremer, HMMN, Centre Manche Mer du Nord, 150 Quai Gambetta BP 699 62321, Boulogne-sur-Mer, France
4 : University of Oslo, Kristine Bonnevies hus, Blindernvn. 31, Oslo 0371, Norway
5 : Great Lakes Institute for Environmental Research, University of Windsor, 401 Sunset Ave., Windsor, ON N9B 3P4, Canada
6 : Institute of Marine Research, Nordnesgaten 50, Bergen 5005, Norway
7 : Department of Arctic and Marine Biology, Arctic University of Norway, Tromsø, Norway
Source Ecological Indicators (1470-160X) (Elsevier BV), 2022-03 , Vol. 136 , P. 108661 (9p.)
DOI 10.1016/j.ecolind.2022.108661
WOS© Times Cited 9
Keyword(s) Marine mammal community, Arctic marine ecosystem, Ecological niche metrics, Trophic sources, Trophic gradient, Niche partitioning
Abstract

The Arctic is warming rapidly, with concomitant sea ice losses and ecosystem changes. The animals most vulnerable to Arctic food web changes are long-lived and slow-growing such as marine mammals, which may not be able to adapt rapidly enough to respond to changes in their resource bases. To determine the current extent and sources of these resource bases, we examined isotopic and trophic niches for marine mammals in the European Arctic using skin carbon (δ13C) and nitrogen (δ 15N) stable isotope (SI) compositions from 10 species: blue, fin, humpback, minke, sperm and white whales, bearded and ringed seals, walruses and polar bears, and dietary fatty acids (FAs) in polar bears, walruses and most of the whale species listed here. SI values showed clear species separation by trophic behaviour and carbon sources. Bearded seals, walruses and white whales had the smallest isotopic niches; these species are all resident High Arctic species and are likely to be particularly vulnerable to changes in Arctic ecosystems. We found clear separation between FA groupings driven by pelagic, benthic and planktonic/algal sources: pelagic FAs in all whales, benthic FAs in walruses, and copepod/algae/dinoflagellate FAs in polar bears, with some polar bear compositions approaching those of the whales and walruses. There is strong niche partitioning between study species with minimal functional redundancy, which could impact Arctic ecosystem structure and connectivity if populations of these large nutrient vectors are reduced or lost.

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