A review of forestry’s impacts on methylmercury in aquatic ecosystems and recommendations for best management practices in Ontario’s boreal forest

Abstract

Mercury contamination in freshwater fish of Northern Ontario is exceeding levels safe for consumption and is negatively impacting remote communities. This literature review examines the impacts of specific forest operations on mercury contamination to aquatic communities. Literature was reviewed from online sources using peer reviewed journal articles that contained relevant information to mercury cycling or impacts of forest operations. The studies found that forest harvesting and site preparation were responsible for increasing soil concentrations of methylmercury (MeHg) between 100-500%. There were not subsequent changes in aquatic mercury concentrations if hydrological connections between soils and water were minimized. Fire reduced overall mercury concentrations in the soil and lessened the impact of site disturbance on aquatic mercury concentrations. Current management practices in Ontario are insufficient at preventing significant mercury contamination to freshwater ecosystems. Incorporating more modern technology and harvesting practices, and management strategies that minimize movement of mercury from forest soils to waters should be the focus of future management directions.