Bioaccumulation of pollutants in Galapagos sea lions and marine mammals from British Columbia, Canada

Bioaccumulation is a key criterion to assess and manage commercial chemicals and pollutants recognized internationally in the United Nations Stockholm Convention for Persistent Organic Pollutants, the Registration, Evaluation, Authorization and Restriction of Chemicals Program in the European Union, the Toxic Substances Control Act in the USA and nationally the Canadian Environmental Protection Act. Bioaccumulation is the process by which chemical concentrations achieve high levels in wildlife and humans, which can cause health effects and elevated health risks. To assess the degree of bioaccumulation and health effects of persistent organic pollutants in marine mammals, field studies of the bioaccumulation and health effects of these pollutants were conducted in a remote marine environment (Galapagos Islands, Ecuador) and in local marine ecosystems of British Columbia, Canada. The main findings of this work indicate that a number of persistent organic pollutants, including PCBs, DDTs and several other organochlorine pesticides biomagnify in Galapagos sea lions but are generally below concentrations associated with known effects. An increase in DDT concentrations was observed in Galapagos sea lions from 2005 to 2008, which may be related to the renewed use of DDT in malaria affected regions endorsed by the World Health Organization in 2006. PCB and PBDE concentrations were higher in Steller sea lions than in Galapagos sea lions. PCBs in Steller sea lions exceeded immunotoxic and endocrine disruption thresholds. To provide science-based tools for the management of pollutants, a bioaccumulation model for marine mammals was developed and tested. The model was applied to derive sediment target values for sediment remediation and for the derivation of ocean disposal permits in British Columbia. The application of the model shows that current sediment quality guidelines in Canada are not protective of the health of killer whales and Steller sea lions. Based on the model results, I recommend values that can be used as a basis for the derivation of sediment quality criteria for the protection of marine mammals in British Columbia. The findings support environmental management plans to mitigate chemical stressors of marine mammalian ecosystems in the Galapagos Islands and British Columbia.