The river otter: A biological monitor for environmental contamination in Victoria Harbour
In collaboration with Environment Canada and the BC Ministry Environment, UBC graduate student, Cait Nelson, investigated contaminant exposure in coastal river otter from Victoria, British Columbia, (Thesis available online by clicking here). Victoria Harbour is a known hot spot for persistent organic pollutants and there is ongoing concern that contaminants in the marine environment could be negatively affecting the wildlife in the area. River otters were therefore selected as a biological monitor to investigate the potential impacts. As a top predator river otters have a critical role in maintaining ecosystem integrity but they are also most vulnerable to the high concentrations of contaminants at the top of the food chain.
One aspect of this study was to explore the use of non-invasive sampling techniques to both monitor environmental contamination and to characterize population level impacts. Fecal (scat) samples were collected from latrine sites along the coastline and analyzed using a multidisciplinary approach by splitting samples for various analyses. Contaminant levels measured in feces were compared to levels measured in blood samples from live captured animals. These results demonstrated that the contaminants measured in feces were representative of the levels in circulation. There were significant spatial patterns that indicated localized contaminant exposure. Contaminant levels measured in animals inhabiting the harbour were significantly greater than levels in animals from the surrounding area. These spatial patterns were also evident when radio telemetry data from individual animals indicated that only a few number of otters were using the harbour because of limited movement and small home ranges.
In an attempt to characterize any physiological effects, hormone metabolites were measured in the feces to determine if there was a correlation between contaminant levels and steroid or thyroid hormone responses. The non-invasive hormone measures illustrated biologically meaningful responses to environmental factors, such as breeding and temperature, but did not correlate to the contaminant levels.