Elsevier

Environmental Pollution

Volume 238, July 2018, Pages 306-316
Environmental Pollution

River otters (Lontra canadensis) “trapped” in a coastal environment contaminated with persistent organic pollutants: Demographic and physiological consequences

https://doi.org/10.1016/j.envpol.2018.03.035Get rights and content
Under a Creative Commons license
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Highlights

  • River otters in contaminated harbours are exposed to exceedingly high levels of PCB.

  • We found significant positive correlations between concentrations of PCBs and of thyroid and sex hormones.

  • Otters showed restricted home ranges, as they did not venture out of the contaminated area.

  • DNA genotyping analysis provided no evidence that the harbour otters were in an ecological trap.

Abstract

Productive coastal and estuarine habitats can be degraded by contaminants including persistent organic pollutants (POPs) such as PCBs, dioxins, and organochlorine insecticides to the extent of official designation as contaminated sites. Top-predatory wildlife may continue to use such sites as the habitat often appears suitable, and thus bioaccumulate POPs and other contaminants with potential consequences on their health and fitness. Victoria and Esquimalt harbours are located on southern Vancouver Island, British Columbia (BC) and are federally designated contaminated sites due mainly to past heavy industrial activities, such as from shipyards and sawmills. We collected scat samples from river otters (Lontra canadensis) throughout an annual cycle, and combined chemical analysis with DNA genotyping to examine whether the harbour areas constituted a contaminant-induced ecological trap for otters. We confirmed spatial habitat use by radio telemetry of a subsample of otters. Fifteen percent of otter scat contained PCB concentrations exceeding levels considered to have adverse effects on the reproduction of mink (Neovison vison), and there were significant positive correlations between concentrations of PCBs and of thyroid (T3) and sex (progesterone) hormones in fecal samples. Radio telemetry data revealed that otters did not show directional movement away from the harbours, indicating their inability to recognize the contaminated site as a degraded habitat. However, analysis and modeling of the DNA genotyping data provided no evidence that the harbour otters formed a sink population and therefore were in an ecological trap. Despite the highly POP-contaminated habitat, river otters did not appear to be adversely impacted at the population level. Our study demonstrates the value of combining chemical and biological technologies with ecological theory to investigate practical conservation problems.

Keywords

River otter
Persistent organic pollutants
Fecal DNA genotyping
Hormone response
Ecological trap
Coastal contaminated sites

Cited by (0)

1

Andrew Huang present address: Canadian Wildlife Service, Environment and Climate Change Canada, Delta, BC, Canada.

2

Daniel Guertin present address: British Columbia Ministry of Forests, Lands, Natural Resource Operations and Rural Development, Victoria, BC, Canada.