Fecal glucocorticoids and anthropogenic injury and mortality in North Atlantic right whales Eubalaena glacialis

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2017-11-30
Authors
Rolland, Rosalind M.
McLellan, William A.
Moore, Michael J.
Harms, Craig A.
Burgess, Elizabeth A.
Hunt, Kathleen E.
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DOI
10.3354/esr00866
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Keywords
North Atlantic right whale
Stress
Glucocorticoids
Fecal hormones
Entanglement
Abstract
As human impacts on marine ecosystems escalate, there is increasing interest in quantifying sub-lethal physiological and pathological responses of marine mammals. Glucocorticoid hormones are commonly used to assess stress responses to anthropogenic factors in wildlife. While obtaining blood samples to measure circulating hormones is not currently feasible for free-swimming large whales, immunoassay of fecal glucocorticoid metabolites (fGCs) has been validated for North Atlantic right whales Eubalaena glacialis (NARW). Using a general linear model, we compared fGC concentrations in right whales chronically entangled in fishing gear (n = 6) or live-stranded (n = 1), with right whales quickly killed by vessels (n = 5) and healthy right whales (n = 113) to characterize fGC responses to acute vs. chronic stressors. fGCs in entangled whales (mean ± SE: 1856.4 ± 1644.9 ng g-1) and the stranded whale (5740.7 ng g-1) were significantly higher than in whales killed by vessels (46.2 ± 19.2 ng g-1) and healthy whales (51.7 ± 8.7 ng g-1). Paired feces and serum collected from the live-stranded right whale provided comparison of fGCs in 2 matrices in a chronically stressed whale. Serum cortisol and corticosterone in this whale (50.0 and 29.0 ng ml-1, respectively) were much higher than values reported in other cetaceans, in concordance with extremely elevated fGCs. Meaningful patterns in fGC concentration related to acute vs. chronic impacts persisted despite potential for bacterial degradation of hormone metabolites in dead whales. These results provide biological validation for using fGCs as a biomarker of chronic stress in NARWs.
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© The Author(s), 2017. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Endangered Species Research 34 (2017): 417-429, doi:10.3354/esr00866.
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Endangered Species Research 34 (2017): 417-429
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