Examining Seasonality of Zooplankton Communities and Water Quality in Yellowknife Area Lakes, Northwest Territories

• Main Author: Andreola, Nicole
• Format: Text
• Language: English
• Published: Scholars Commons @ Laurier 2024
• Subjects: Environmental Monitoring; Northwest Territories; Yellowknife
• Online Access: https://scholars.wlu.ca/etd/2664; https://scholars.wlu.ca/context/etd/article/3820/viewcontent/Andreola_Thesis_Final.pdf

Frame Lake, located in Yellowknife, Northwest Territories, is one of the city's main attractions. Unfortunately, urbanization and eutrophication have led to a decline in water quality in the lake. Eutrophication has caused a buildup of organic matter in sediments on the bottom of the lake, which can cause a high oxygen demand when processed by aerobic bacteria. Dissolved oxygen levels are high during the summer, but ice shields the lake from gas exchange with the atmosphere, leading to winter anoxia. This oxygen depletion makes it impossible for sensitive aquatic life, such as fish, to survive in the lake over the winter. One possible solution to winter anoxia is to install a hypolimnetic aerator to exchange oxygen between the lake's deep layers and the atmosphere. Past studies show that aeration will improve dissolved oxygen levels, and it may help break down accumulated organic matter and reduce nutrient levels in the water column. As part of a remediation project funded by Rio-Tinto Diamond Mines, a hypolimnetic aerator will be installed on Frame Lake in early summer 2024. To evaluate the effects of the aerator installation on the lake, data on the natural variability in water quality and biota in Frame Lake and comparable lakes within the region is necessary. The objectives for my thesis were to examine seasonal variability in water quality and zooplankton communities in Frame Lake and two reference lakes, and to examine the relationships between water quality and zooplankton communities in those lakes to assess if aeration might lead to chemical or biological improvements in Frame Lake. I collected monthly water quality and zooplankton samples from Frame Lake and two reference lakes between March 2022 – November 2024. My results showed seasonal fluctuations in pH, conductivity, and dissolved oxygen in my study lakes, and confirmed that Frame Lake experiences anoxia once the ice cover forms. In addition, nutrient and conductivity levels were higher in Frame Lake than in the two reference lakes. Zooplankton ...