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华的频率、强度和地理范围都在增加，威胁着水生生态系统及其提供的服务。直到最近，大部分关于藻华的淡水研究都集中在蓝绿藻（即蓝藻）引起的事件上，蓝绿藻通常是在人类活动的营养富集后爆发的。然而，在加拿大地盾常见的营养贫乏的湖泊中，最近的证据表明，由绿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地盾湖泊中越来越多的绿藻爆发之间的可能联系。我们将结合高频测量、来自安大略省中南部湖泊的长期深入研究数据以及保存在湖泊沉积物中的信息，探索气候变化、湖泊物理结构和存在的藻类类型和数量之间的关系。具体而言，我们将：1)模拟加拿大地盾南部湖泊的历史和未来热结构；2)确定冬春过渡时期（一年中绿藻生长的重要时期）调节藻类群落的气候相关因子；3)评估过去几个世纪和几千年的气候和环境变化是如何影响绿藻的。最终，从这些研究中获得的知识可以用来建立模型，预测未来发生藻华的可能性。这些预测将成为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.