Type of Presentation

Oral

Session Title

General contaminant toxicology in aquatic and terrestrial species

Comments

Past industrial activities on Southern Vancouver Island, British Columbia, have resulted in localized polychlorinated biphenyl (PCB) contamination in the near shore marine environment. Previous studies have shown that PCB levels are particularly high in North American river otters (Lontra canadensis) residing in industrial/urban harbours, with some individuals displaying concentrations above the critical level of exposure. When an animal’s foraging area is more centralized in a contaminated area, their exposure risk concomitantly increases, which potentially leads to adverse health effects such as disruption of the endocrine system. Here, we investigated the degree of connectivity between otters in a contaminated (Victoria/Esquimalt Harbour) and two relatively uncontaminated areas (Oak Bay and Metchosin) by determining their home range and spatial movement through radio-telemetry. We also used scat and live animal sampling for three analysis: (i) evaluating subpopulation structure using multi-locus microsatellite genotyping; (ii) measuring concentrations of PCB, polybrominated diphenyl ether (PBDE), and organochchlroine pesticides; and (iii) assessing thyroid and reproductive hormone levels. Fixed kernel estimates revealed limited home range, with little to no overlap among otters of all three sites. Microsatellite analysis showed substantial genetic distance between the contaminated harbours and the uncontaminated Metchosin area (FST = 0.054). Mean PCB concentrations in otter blood and feces were significantly higher in harbours (38.94 and 6.35mg/kg lw, respectively) relative to Oak Bay (1.83 and 0.84mg/kg lw) and Metchosin (3.23 and 0.85mg/kg lw). Although there were differences in hormone measures among the sites, it is not clear whether the patterns were associated with contaminants. We conclude that in the harbour area, otters’ chronic exposure to PCB was attributed to their small home ranges and restricted gene flow with the adjacent uncontaminated sites. River otters are ideal biological indicators for aquatic ecosystem health and can be useful monitors for environmental and anthropogenic stressors on wildlife.

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Contaminant exposure in marine foraging river otters from Southern Vancouver Island, British Columbia

2016SSEC