Victoria Goodfellow (Honours thesis, 2021)

Project description: Climate change is resulting in permafrost thaw across Canada’s Arctic, causing changes in water quality in northern lakes. Chironomids are some of the most abundant macroinvertebrates in northern lakes and represent an important food source for fish. Studies in other regions indicate that chironomids can be affected by water quality variables that are expected to change in response to permafrost thaw, such as calcium, total suspended solids (TSS), and pH. The goal of my study was to examine how chironomid communities in Arctic lakes might respond to water quality changes associated with permafrost thaw. I used samples of chironomid larvae that were collected from 20 lakes in the Gwich’in and Inuvialuit regions of the Northwest Territories and identified the larvae to the subfamily level. I then constructed multiple regression models to determine the environmental characteristics most strongly associated with differences in the abundance of chironomid subfamilies among my lakes. My multiple regression analysis for the four most abundant chironomid subfamilies - Chironominae, Orthocladiinae, Tanypodinae, Diamesinae - explained between 33-69% of the variation in abundance among lakes. Interestingly, the most parsimonious models contained variables expected to be affected by permafrost thaw, including TSS, calcium, turbidity, chlorophyll-a, and total phosphorus. I used data from the literature to determine the potential responses of lake water quality to permafrost thaw, along with my multiple regression models to examine how changes in water quality related to permafrost thaw might influence chironomids. Projections based on my models suggest that Chironominae abundance will significantly decrease while Diamesinae, Orthocladiinae and Tanypodinae will increase in abundance. Further research will be needed to determine if changes in the relative abundance of chironomids may affect food webs in Arctic lakes.

Victoria’s thesis