Blooms of cyanobacteria (‘blue-green algae’) in aquatic ecosystems negatively impact biodiversity and are a human health concern. My PhD research advanced our understanding of the environmental factors leading to blooms of toxic cyanobacteria in lakes.
First, I discovered that microcystins, potent liver toxins produced by cyanobacteria, are prevalent in water bodies across Canada, but only under particular nutrient conditions, which I suggested could be used as a screening tool by lake managers. Given the health risk that these toxins pose to humans, publication of my work in the Canadian Journal of Fisheries & Aquatic Sciences resulted in national media coverage.
Second, I demonstrated that lake sediments release bioavailable nutrients that support growth and toxin production in a common cyanobacterial species; this work was published in the International Journal of Limnology in collaboration with Israeli scientists.
Third, I showed how low iron in sediments and discontinuous mixing in lakes together create ideal conditions for cyanobacterial blooms, thereby revealing an important mechanism potentially underlying the increasing dominance of cyanobacteria in shallow lakes. This paper is in press for publication in Limnology & Oceanography.
Fourth, I conducted a large-scale manipulation experiment in a hypereutrophic lake in Alberta, which demonstrated that iron additions inhibit phosphorus release from sediments, decrease algal biomass, discourage the dominance of cyanobacteria, and reduce microcystin levels.
This research confirmed that iron treatment can be an effective remediation strategy for managing algal blooms, and more broadly, the work established the importance of iron in influencing the trophic status of lakes.