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

近几十年来，海洋和淡水环境中藻类水华爆发的频率、强度和地理范围都有所增加，威胁到水生生态系统及其提供的服务。直到最近，对藻类水华的大部分淡水研究都集中在蓝藻(即蓝藻)引起的事件上，蓝藻通常是在人类活动的营养丰富后发生水华的。然而，在加拿大盾常见的营养贫乏的湖泊中，最近的证据表明，由金藻引起的味道和气味事件也在增加。我和我的学生将探索气候变化与加拿大屏蔽湖金藻水华增多之间的可能联系。利用高频测量、来自安大略省中南部密集研究的湖泊的长期数据以及湖泊沉积物中保存的信息，我们将探索气候变异性、湖泊的物理结构以及存在的藻类类型和数量之间的关系。具体地说，我们将：1)模拟加拿大南部地盾湖泊的历史和预测热结构；2)确定在从冬季到春季的过渡期(一年中的重要季节)调节藻类群落的气候相关因素；以及3)评估数百年来的气候和环境变化对过去黄藻的影响。最终，来自这些研究的知识可能被用来建立预测未来发生藻类水华的可能性的模型。这些预测将构成未来风险评估和气候变化适应计划的重要组成部分。

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.