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UBC Theses and Dissertations

Contaminant exposure in marine foraging river otters from Victoria, British Columbia, Canada Nelson, Caitlin Jean


Past industrial activities on Southern Vancouver Island, British Columbia, Canada have resulted in localized polychlorinated biphenyl (PCB) contamination in the near shore marine environment. The ecological impacts of new and residual contaminants on wildlife species in this area are unknown. North American river otters (Lontra canadensis) are ideal biological indicators for aquatic ecosystem health and can be useful monitors for environmental and anthropogenic stressors on wildlife. Non-invasive scat sampling is an effective tool for studying aspects of river otter ecology without disrupting their natural behavior. Interpretation of river otter data derived from scat however can be limited without validation with live animal data. By combining scat sampling with live animal sampling I was able to compare the two sources of data to assess the effectiveness of non-invasive techniques. I investigated (i) home range analysis and spatial patterns through radio-telemetry to inform (ii) an assessment of environmental contaminant exposure and potential adverse health effects. Fixed kernel home range estimates revealed limited ranges, localized exposure and potential small scale population structuring. This indicates that only the river otters inhabiting the contaminated sites are being exposed to high levels of PCBs. Mean PCB concentrations in river otter blood and feces were significantly higher in harbour sites relative to the rest of the study area. Contaminant patterns between the two sample types were comparable and support the use of non-invasive sampling for investigating environmental contamination. Non-invasive hormone measures were used as indicators for contaminant related effects. Although there were differences between harbour and non-harbour sites, it is not clear the patterns were associated with contaminants.

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