Jaclyn Franceschini (Honours thesis, 2019)

Project description: Every winter, salt deicers are used on Ontario roadways and sidewalks to increase traction and reduce accidents. However, road salt can leach into freshwater ecosystems and expose aquatic organisms to elevated salt concentrations. This study investigated the impacts of increased salinity from road salt application on the community structure and diversity of freshwater zooplankton, a group known to be sensitive to changes in salinity. I hypothesized that increased salinities would result in a shift towards halotolerant species in the community and would lead to a reduction in zooplankton species richness, abundance, and diversity. I ran a six week field mesocosm experiment on the shore of Sturgeon Lake to test the effects of elevated sodium chloride (NaCl) levels. Elevated salinity levels did not significantly affect diversity, and there were no clear shifts in species composition associated with salinity. However, elevated salinity levels resulted in a significant decrease in zooplankton species richness and abundance. When the relationships between salinity, richness, and abundance are put into the context of current chloride trends, my results suggest that salinity increases are unlikely to cause any significant changes in Sturgeon Lake zooplankton communities over the next century. Further studies will need to examine how other types of freshwater organisms (e.g. phytoplankton) respond to increased salinity, but my results suggest that the risks of road salt contamination for Ontario lakes may have been exaggerated in recent media coverage.

Jaclyn’s thesis