Name
I’ll be dammed: Beaver ponds decrease methylmercury concentrations in Taiga Plains waters
Description
Canadian Beavers commonly build dams and create ponds which alter both the flow, and the chemical properties of water. In mercury-rich areas, the conditions created in the pond may alter the delivery of toxic mercury forms to downstream ecosystems. The goal of this research is to determine whether beaver ponds in the Taiga Plains are acting as methylmercury production hotspots, and to determine which water chemistry changes correlate with methylmercury concentration changes between the inflow and the outflow of beaver ponds. I sampled the inflow and outflow of 20 beaver ponds throughout the Taiga Plains in June and August of 2022 to determine whether methylmercury concentrations are being changed by the conditions created by the pond, and what those conditions are. Overall, beaver ponds in the study region act as methylmercury sinks during low-flow periods, with lower methylmercury concentrations in the outflow than the inflow. Longer residence time and higher dissolved oxygen concentration are correlated with greater decreases to methylmercury concentration. The findings will allow land managers to determine appropriate courses of action for beaver management as the population increases, and support well-informed water quality risk assessments as the landscape continues to change.