Understanding causes of algal blooms in nutrient-poor lakes within the Precambrian Shield: Evaluating the role of climatic change

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The frequency, intensity and geographic extent of algal blooms have increased in recent decades in marine and freshwater environments, threatening aquatic ecosystems and the services they provide. Until recently, much of the freshwater research on algal blooms has focused on events caused by blue-green algae (i.e., cyanobacteria), which commonly bloom following nutrient enrichment from human activities. However, in nutrient-poor lakes that are common to the Canadian Shield, recent evidence shows that taste and odour events caused by chrysophyte algae are also increasing. My students and I will explore the possible link between climate change and the increased occurrence of chrysophyte blooms in Canadian Shield lakes. Using a combination of high-frequency measurements, long-term data from intensively-studied lakes in south-central Ontario, and information preserved in lake sediments, we will explore the relationship between climatic variability, the physical structure of lakes, and the types and amount of algae that exist. Specifically, we will: 1) Model the historical, and predict the future, thermal structure of lakes on the southern Canadian Shield; 2) Determine the climate-related factors that regulate algae communities during the transition period from winter to spring, an important time of year for chrysophyte algae; and 3) Assess how climatic and environmental changes over centuries and millennia have affected chrysophyte algae in the past. Ultimately, the knowledge from these studies may be used to build models that predict the likelihood of algal blooms occurring in the future. The predictions will form an important component of future risk assessments and climate change adaptation plans.