NWT RESEARCH DATABASE

Regions: North Slave Region

Tags: physical sciences, contaminants, aquatic ecosystems, mining impacts, fish habitat, algae

Objective(s): To assessing how multiple environmental stressors impact aquatic habitats in subarctic shield terrain.

Project Description: This licence has been issued for the scientific research application No.5531. The overarching objective of this program is to take an ecosystem approach to assessing how multiple environmental stressors impact aquatic habitats in subarctic shield terrain. There are three central activities that will be undertaken with this license and they are designed to address the specific objectives below: 1) to understanding the seasonal evolution of harmful algae blooms in Jackfish and the drivers that lead to bloom conditions; 2) to assess the impact of aerator installation on the biological and chemical recovery of Frame Lake; and, 3) to evaluate the role of physical lakes conditions (depth, mixing regime) on the recovery of lakes from legacy mining pollution. Understanding the seasonal evolution of harmful algae blooms in Jackfish and the drivers that lead to bloom conditions: Monthly water chemistry will be collected in Jackfish Lake as well as samples for phytoplankton community composition. Water samples for cyanbacteria analysis will be collected at lower frequency (~ every 3 months) during winter and bi-weekly in summer. Sediment samples will be collected to assess the amount and form of phosphorous stored in lake sediments. Assessing the impact of aerator installation on the biological and chemical recovery of Frame Lake: Monthly water chemistry will be collected through the water column in Frame Lake, as well as samples for phytoplankton and zooplankton community composition. These data will help us to understand seasonal changes in the lake. These measurements will be made before and after the installation of the aerator to assess the impact of aerator installation. The monthly sampling will be complemented by additional direct measurements of oxygen conditions in the lake and within the sediments, as well as the collection of lake sediment samples for experimental incubation. Frame Lake will be instrumented with dissolved oxygen loggers in the two main basins of the lake to track depletion of oxygen under ice, before and after installation of the aerator. Evaluating the role of physical lakes conditions (depth, mixing regime) on the recovery of lakes from legacy mining pollution: Monthly or bi-monthly water samples will be collected from each of the study lakes (that span a range of physical conditions). Water samples will be analyzed for nutrients, major ions, and metals to assess how differences in lake morphology influence the cycling of legacy mining contaminants in the lake. The research team will supplement the water sampling with sediment collection to assess the amount and form of legacy contaminants in the sediments of each lake. The lakes will also be instrumented with dissolved oxygen and temperature loggers to track changes in the physical conditions of the lakes through the year. Project plans will be discussed at annual meetings with the relevant community government organizations, industry, and government agencies. Established relationships include: Northwest Territories Power Corporation, Diavik Diamond Mine, Yellowknives Dene First Nation, North Slave Metis Alliance, the City of Yellowknife, and the Department of Environment and Natural Resources. Project results will be communicated through funding reports to Cumulative Impact Monitoring Program, annual meetings with project partners, and conference presentations. All of the data collected in this project will be made publicly available at the end of the project through the Aurora Research Institute The fieldwork for this study will be conducted from May 20, 2023 to December 31, 2023.