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Marine Ecology Progress Series

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MEPS 471:283-291 (2012)  -  DOI:

Composition and temporal variation in the diet of beluga whales, derived from stable isotopes

Marianne Marcoux1,2,*, Bailey C. McMeans3, Aaron T. Fisk3, Steven H. Ferguson1

1Fisheries and Oceans Canada, 501 University Crescent, Winnipeg, Manitoba R3T 2N6, Canada
2Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen AB24 2TZ, UK
3Great Lakes Institute for Environmental Research, University of Windsor, Windsor, Ontario N9B 3P4, Canada

ABSTRACT: The diet of individuals within a species commonly differs among sex and age classes because of differences in energy requirements and physiological needs. Belugas Delphinapterus leucas show a high level of sexual habitat segregation and dimorphism that could result in differences in diet between the sexes. Here, we used stable isotopes of carbon (δ13C) and nitrogen (δ15N) from muscle and skin samples of 88 belugas, and likely prey species, to investigate how beluga diet in Cumberland Sound (Nunavut, Canada) varied between sexes, among age classes, and over time from 1982 to 2009. Based on linear mixed-effects models, older belugas had higher δ13C and δ15N than younger individuals of both sexes, suggesting that older individuals feed on more benthic, higher trophic-position prey than younger individuals. We also found a strong, decreasing trend in both δ13C and δ15N values over time, indicating either a temporal shift in beluga diet or an ecosystem-wide change in isotope values. Based on stable isotope mixing models performed on belugas sampled since 2000, both males and females fed primarily on Arctic cod Boreogadus saida and capelin Mallotus villosus. The latter is a recent invader to this ecosystem, which could explain the temporal shift in stable isotopes of the Cumberland Sound belugas.

KEY WORDS: Marine mammal · Monodontidae · Arctic · Time series

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Cite this article as: Marcoux M, McMeans BC, Fisk AT, Ferguson SH (2012) Composition and temporal variation in the diet of beluga whales, derived from stable isotopes. Mar Ecol Prog Ser 471:283-291.

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