The impacts of century-old, arsenic-rich, mine tailings on multitrophic level biological assemblages in lakes from the Cobalt, Ontario, Canada region

The combination of silver mining and lack of environmental regulations in the early 1900s resulted in a legacy of century-old, arsenic-rich mine tailings around Cobalt, Ontario, Canada. In order to examine the impacts that arsenic has had on aquatic ecosystems in the region, diatom, cladoceran, chironomid, and zooplankton assemblages from lakes along a gradient of surface water arsenic contamination (0.4 - 1,113 µg/L) were sampled. Our results show that present-day arsenic concentration is not a significant driver of biotic community change across the study lakes, suggesting that other variables are more important in the structuring of the biological community in this region. These results suggest that while legacy contamination has greatly increased arsenic concentration beyond the acceptable guideline for aquatic life (5 µg/L), variability in lake morphometry among the study lakes and other environmental factors appear more influential in the structuring of aquatic ecosystems in Cobalt, Ontario, Canada.