Key Aquatic Primary Producers Track the Impacts of Metal Pollution and Local Land-Use Changes in Climatically Sensitive Subarctic Lakes Around the City of YellowknifeTuesday, November 20, 2018 - 11:40 to 11:59 Theatre 2
Very little long-term environmental monitoring information is available on the ecological impacts of anthropogenic activities on climatically-sensitive northern aquatic environments. Fortunately, lake sediments preserve the remains of many sensitive biological and geochemical indicators that can be used to hindcast past environmental conditions. We are using the paleolimnological approach to understand the long-term biological consequences of 20th century gold mining activities around the City of Yellowknife. Specifically, we aim to 1) establish the pre-disturbance biological conditions (i.e. prior to mining activities), 2) examine the response to metal pollution and local land-use changes, and 3) determine if biological recovery has occurred since the cessation of gold mining activities. To achieve these goals, we examined sedimentary diatom (microscopic siliceous algae) assemblages in radiometrically dated sediment cores from a suite of lakes around Yellowknife. Our data provide strong evidence that the primary producers from lakes around Yellowknife have been altered by mining operations, as well as local land-use changes, over the past ~100 years. Despite the closure of the mining activities, the biota of these lakes have not returned to pre-disturbance conditions, as the contaminant concentrations are still high at some sites. The timing and nature of the biological changes in these lakes affected by multiple environmental stressors highlight the interactive effects of industrial contaminants, local land-use changes, and climate warming on the algal assemblages in climatically-sensitive subarctic regions.