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Pacific walrus diet across 4000 years of changing sea ice conditions

Published online by Cambridge University Press:  14 March 2019

Casey T. Clark Open the ORCID record for Casey T. Clark [Opens in a new window] ,
Lara Horstmann ,
Anne de Vernal ,
Anne M. Jensen  and
Nicole Misarti
Casey T. Clark*
Affiliation:
Water and Environmental Research Center, University of Alaska Fairbanks, 1764 Tanana Loop, Fairbanks, Alaska 99775-5860, USA College of Fisheries and Ocean Sciences, University of Alaska Fairbanks, 2150 Koyukuk Drive, Fairbanks, Alaska 99775-7220, USA
Lara Horstmann
Affiliation:
College of Fisheries and Ocean Sciences, University of Alaska Fairbanks, 2150 Koyukuk Drive, Fairbanks, Alaska 99775-7220, USA
Anne de Vernal
Affiliation:
Centre de Recherché en Géochimie et Géodynamique (Geotop), Université du Québec à Montréal, P.O. Box 8888, Succursale Centre-Ville, Montréal, Québec H3C 3P8, Canada
Anne M. Jensen
Affiliation:
UIC Science LLC, P.O. Box 577, Utqiaġvik, Alaska 99723, USA University of Alaska Museum, University of Alaska Fairbanks, 1962 Yukon Drive, Fairbanks, Alaska 99775, USA
Nicole Misarti
Affiliation:
Water and Environmental Research Center, University of Alaska Fairbanks, 1764 Tanana Loop, Fairbanks, Alaska 99775-5860, USA
*
*Corresponding author e-mail address: ctclark@alaska.edu
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Abstract

Declining sea ice is expected to change the Arctic's physical and biological systems in ways that are difficult to predict. This study used stable isotope compositions (δ13C and δ15N) of archaeological, historic, and modern Pacific walrus (Odobenus rosmarus divergens) bone collagen to investigate the impacts of changing sea ice conditions on walrus diet during the last ~4000 yr. An index of past sea ice conditions was generated using dinocyst-based reconstructions from three locations in the northeastern Chukchi Sea. Archaeological walrus samples were assigned to intervals of high and low sea ice, and δ13C and δ15N were compared across ice states. Mean δ13C and δ15N values were similar for archaeological walruses from intervals of high and low sea ice; however, variability among walruses was greater during low-ice intervals, possibly indicating decreased availability of preferred prey. Overall, sea ice conditions were not a primary driver of changes in walrus diet. The diet of modern walruses was not consistent with archaeological low sea ice intervals. Rather, the low average trophic position of modern walruses (primarily driven by males), with little variability among individuals, suggests that trophic changes to this Arctic ecosystem are still underway or are unprecedented in the last ~4000 yr.

Keywords

Pacific walrusSea iceArcticClimate changeStable isotopesHistorical ecologyPaleoecologyChukchi SeaBering Sea
Type
Research Article
Information
Quaternary Research , Volume 108: PESAS , July 2022 , pp. 26 - 42
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Copyright
Copyright © University of Washington. Published by Cambridge University Press, 2019

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