Cyanobacteria and cyanotoxin trends: determining historical and contemporary relationships with eutrophication and climate warming

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Freshwaters around the world are experiencing algal blooms which directly and indirectly are affecting aquatic ecosystems, the services they provide and even human health. Cyanobacterial (blue-green algal) blooms are of particular concern because they often contain toxins that can affect wildlife, livestock, domestic animals and humans. In Canada there appears to be an increasing incidence of cyanobacterial blooms in lakes, at least in Ontario and Quebec, however, this could simply be due to better reporting since most lakes and rivers have minimal long-term monitoring. Furthermore, there is a strong possibility that these trends are and will be aggravated by climate warming. This project aims to identify, through a combination of empirical, experimental and paleolimnological studies, the environmental triggers of cyanobacterial dominance and, in particular, the drivers of potentially toxigenic cyanobacteria. This will entail a comprehensive synthesis of literature and unpublished data bases to determine whether there is a common nutrient threshold for cyanobacteria dominance or whether this threshold differs across regions and in response to climate variables. Paleolimnological studies in four regions of Canada will help determine when cyanobacterial blooms began and what factors led to their onset. The persistence in lake sediments of the most common cyanotoxins (the hepatotoxic microcystins) will be determined and their use as a potential indicator of past toxic blooms will be examined. Environmental agencies from federal and provincial departments as well as local municipalities are among the supporting organizations for this project.