Environmental and behavioral changes may influence the exposure of an Arctic apex predator to pathogens and contaminants

Todd C Atwood,Steven Hennager,Camila K Cerqueira-Cézar,Jitender P Dubey,Matthew Mccollum,Andrew M Ramey,Pauline Nol,Colleen Duncan,Jack Rhyan,Oliver C H Kwok,Kelly A Patyk,Melissa A Mckinney

doi:10.1038/s41598-017-13496-9

Abstract

Recent decline of sea ice habitat has coincided with increased use of land by polar bears (Ursus maritimus) from the southern Beaufort Sea (SB), which may alter the risks of exposure to pathogens and contaminants. We assayed blood samples from SB polar bears to assess prior exposure to the pathogens Brucella spp., Toxoplasma gondii, Coxiella burnetii, Francisella tularensis, and Neospora caninum, estimate concentrations of persistent organic pollutants (POPs), and evaluate risk factors associated with exposure to pathogens and POPs. We found that seroprevalence of Brucella spp. and T. gondii antibodies likely increased through time, and provide the first evidence of exposure of polar bears to C. burnetii, N. caninum, and F. tularensis. Additionally, the odds of exposure to T. gondii were greater for bears that used land than for bears that remained on the sea ice during summer and fall, while mean concentrations of the POP chlordane (ΣCHL) were lower for land-based bears. Changes in polar bear behavior brought about by climate-induced modifications to the Arctic marine ecosystem may increase exposure risk to certain pathogens and alter contaminant exposure pathways.

Highlights

Environmental conditions such as climate and landscape structure can influence the occurrence and spread of pathogens
Polar bears that use land in summer and fall may increase their cumulative risk of exposure to infectious agents and contaminants to include those primarily associated with terrestrial habitats
We investigated risk factors influencing the seroprevalence of Brucella spp., Coxiella burnetii, Toxoplasma gondii, Francisella tularensis, and Neospora caninum among polar bears from Alaska’s southern Beaufort Sea

Summary

Introduction

Environmental conditions such as climate and landscape structure can influence the occurrence and spread of pathogens. Environmental changes that alter the bio-climatic envelope of host and/or vector communities can modify infection dynamics resulting in new foci of transmission or novel sources of zoonotic infectious agents[6]. From 1989–2008, near-surface temperatures in the Arctic increased at a rate of 1.6 °C per decade in autumn, while sea ice extent declined at a rate of −7.9% per decade[7] Concurrent with those environmental changes has been the emergence, re-emergence, and spread of various pathogens associated with Arctic wildlife[8,9,10]. We investigated risk factors influencing the seroprevalence of Brucella spp., Coxiella burnetii, Toxoplasma gondii, Francisella tularensis, and Neospora caninum among polar bears from Alaska’s southern Beaufort Sea. The focal zoonotic agents included in this study vary in geographic distribution, routes of transmission, and effects on wildlife. By characterizing exposure risks to a suite of pathogens and POPs with different historical distributions and routes of transmission/exposure during a period of environmental change, we can gain insight into emerging health risks for polar bears and other Arctic wildlife species

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Conclusion