Frank H. Rigler Award LecturE

Dr. Shelley Arnott

is the 2025 recipient of the Frank Rigler Award, the highest honour given by the Society of Canadian Limnologists.

Dr. Shelley Arnott, Queens University, Professor, Department of Biology

Dr. Shelley Arnott is an aquatic ecologist whose research spans fundamental to applied outcomes. She uses field and laboratory experiments, in combination with synoptic lake surveys and analyses of long-term data to understand the impacts of environmental change on lake communities. She has investigated processes influencing ecological recovery from regional acidification, and much of her current research is focused on understanding how multiple environmental stressors, including climate change, invasive species, calcium decline, and salinization, shape community responses. She collaborates extensively with government, university, and NGO researchers and has led several international projects to assess variation in responses to environmental change across regions/countries. 

Ecological context shapes zooplankton response to salinization

Human activities are increasing ion concentrations in freshwater ecosystems beyond natural inputs arising from geological weathering and precipitation. In regions that experience cold winters, the application of de-icing salts consisting primarily of NaCl, is causing increased salt concentrations of lakes and rivers near roads and urban centres. We found evidence that aquatic biodiversity can be impacted at chloride concentrations below national water quality guidelines, but there is high variation in response among sites. We explored ecological drivers of this variation and found that water hardness, food quality and quantity, and species interactions can mediate responses of plankton to increasing salt concentrations. Variation in responses among lakes may also be driven by high genetic variation in physiological tolerance of salt-sensitive species. Additional stressors, including heat waves can influence short-term physiological responses, and can interact with salinization even when the stressors are temporally decoupled. These results suggest that management solutions such as region-specific water quality guidelines may be an effective way to reduce biodiversity loss. Alternative ‘eco-friendly’ de-icing salts have been suggested for use in salt-vulnerable areas, but they require further testing before wide-scale use because our studies indicate similar or higher toxicity than rock salt (NaCl).