Long-term changes in Wolf Lake (Sudbury region, Ontario) situated in Mi’iangan Zaagagan Preserve: a proposed Indigenous conservation area

Over a century of large-scale mining and smelting in Sudbury (Ontario, Canada) has impacted nearby aquatic ecosystems. While considerable research exists on Sudbury-area lakes, few studies focus on lands important to Indigenous communities. Wolf Lake, located ~50 km northeast of Sudbury, acidified in the 1960s from long-range acidic deposition from regional smelters. While emission reductions ca. 1970s have been tracked through water chemistry monitoring, baseline conditions remain unknown. Using indicators preserved in lake sediments, we examined long-term effects of acidic emissions and other stressors on Wolf Lake’s aquatic biota. After peak atmospheric emissions, reconstructed lake water pH dropped to ~5.1, with concurrent decreases in sediment chlorophyll a (chl a) and dissolved organic carbon (DOC). These changes coincided with elevated sediment metal levels. Recent sediments show partial recovery, with pH, DOC, and chl a returning towards pre-disturbance levels. However, sediment metal levels remain high, and diatom assemblages have not fully recovered. Understanding these changes offers management insights for the Wahnapitae First Nation’s proposal for an Other Effective area-based Conservation Measure designation for Wolf Lake.