| Mercury levels in a species of Lake Erie game fish are increasing after two decades of steady decline, scientists report. The joint study by researchers from the Ontario and federal government and the University of Toronto is the most comprehensive to date on mercury levels in Great Lakes fish, and was published in the journal ACS Environmental Science & Technology. An analysis of the nearly 6,000 samples of lake trout and walleye collected from the lakes between the 1970s and 2007 showed that concentrations in the fish steadily declined in that period in the upper Great Lakes — Superior and Huron. But between 1990 and 2007, despite a levelling off of mercury concentrations in Lake Ontario walleye, contamination increased in Lake Erie walleye. Researchers hypothesize that the invasions of dreissenid mussels and round goby fish in the ecosystem contributed to the rise in Lake Erie mercury concentrations. High levels of mercury can potentially cause adverse health effects if affected fish are consumed. via Mercury levels increasing in popular species of Lake Erie game fish. | 
