Heightened immune system function in polar bears using terrestrial habitats

Physiological and Biochemical Zoology
By: , and 



Climate change is altering the distribution of some wildlife species while warming temperatures are facilitating the northward expansion of pathogens, potentially increasing disease risk. Melting of Arctic sea ice is causing polar bears (Ursus maritimus) of the Southern Beaufort Sea (SBS) to increasingly spend summer on land, where they may encounter novel pathogens. Here, we tested whether SBS polar bears on shore during summer exhibited greater immune system activity than bears remaining on the sea ice. In addition, we tested whether the type of immune response correlated with body condition, because adaptive responses (slowly-developing defenses against specific pathogens) often require less energy than innate responses (rapid defenses not based on pathogen identity). After accounting for body condition, we found that polar bears on shore exhibited higher total white blood cell counts, neutrophils, and monocytes than bears on the ice, suggesting greater infections. Lymphocytes, eosinophils, basophils and globulins did not differ. C-reactive protein, an indicator of inflammation, also did not differ between habitats. Body condition was associated with variables indicative of both innate and adaptive immunity, suggesting that neither response was uniquely limited by energy resources. Our data indicate that as more polar bears spend longer periods of time on shore, they may experience more infections. We encourage continued health monitoring of this species and studies of the long-term fitness consequences from disease.

Publication type Article
Publication Subtype Journal Article
Title Heightened immune system function in polar bears using terrestrial habitats
Series title Physiological and Biochemical Zoology
DOI 10.1086/698996
Volume 92
Issue 1
Year Published 2019
Language English
Publisher University of Chicago Press
Contributing office(s) Alaska Science Center Biology MFEB
Description 11 p.
First page 1
Last page 11
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