Freshwater fishes are highly variable in their concentrations of mercury, even within a region.  Some of the among-system differences can be explained by the biological traits of the fish (growth, diet, lifespan), and the chemical, geological, and physical characteristics of the systems.  However, human activities such as reservoir creation, electricity generation, and gold mining also result in both locally contaminated areas and increases in the global cycling of mercury to remote locations. High dietary exposure to the organic form of mercury, methylmercury, is known to affect the nervous system and reproduction in fish-eating wildlife and humans, and the fish themselves. As the Minamata Convention to reduce the global trade, use and emissions of mercury comes into force, we should see declines in mercury in fish and reductions in risks to fish consumers but the rate of this decline is unclear. This presentation will describe the local through global processes that drive mercury in fish, how this contaminant may respond to climate change, and what we still do not understand about its fate in freshwaters.  I will describe our comparisons of lake ecosystems from the Arctic and temperate regions of Canada and put this research into a global context.

This project is funded by the Fish and Wildlife Compensation Program on behalf of its program partners BC Hydro, the Province of BC, First Nations and the public, who work together to conserve and enhance fish and wildlife impacted by existing BC Hydro dams.