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

Aquatic ecosystems in northern Ontario (Canada) have been widely studied
for responses to anthropogenic activities. Specifically, the adverse
effects from metal smelting has cause atmospheric deposition of acidic and
metal pollution. Sudbury (Ontario) has been considerable researched for
the effects of century long large-scale mining and smelting operations;
however, local Indigenous freshwater resources have been largely ignored.
Wolf Lake, located ~50 km northeast of Sudbury, is a culturally important
site to the Wahnapitae First Nation and local community, providing many
ecosystem services. Given its significance, the lake and surrounding old
growth red pine (Pinus resinosa) forest is being proposed as
an Other Effective area-based Conservation Measure. To determine
pre-disturbance conditions to inform management decisions for the proposed
conservation site, paleo-ecotoxicological approaches were applied. Here we
use a multi-proxy approach of water chemistry records and sedimentary
metals, chlorophyll a, dissolved organic carbon, and diatom assemblages
from a dated sediment core to reconstruct long-term changes in Wolf Lake.
A 40-year water chemistry dataset was analyzed from the Ministry of
Environment, Conservation and Parks to reconstruct long-term lake water
metal concentrations against sedimentary metal concentrations. Sedimentary
metal concentrations were used to plot against threshold and probable
effect concentrations and calculate enrichment factors. Chlorophyll
a values were used to infer paleoproduction while dissolved
organic carbon was used to infer past lake water conditions. The diatom
assemblage was applied to a regional transfer function to estimate past
lake water pH. Results indicated that Wolf Lake experienced lake
water acidification and metal pollution linked to atmospheric deposition
and complete recovery has yet to occur.