Thermal tolerance and the response of freshwater communities to multiple stressors

加拿大人管理着比世界上任何其他国家都多的内陆水体，这是我们通过《加拿大水法》承诺保护的独特资源。然而，淡水生态系统面临着许多威胁，包括与分水岭土地使用有关的污染，以及由于定向气候变化和更频繁的热浪而导致的水域变暖。预测这些威胁对淡水生物多样性的影响需要评估其相互作用的影响，即单独行动和联合行动时的影响。我的研究计划将理清气候变暖和农业污染对加拿大淡水动物(浮游生物和鱼类)的交互影响。我之前的研究表明，农业污染在淡水生态系统中造成广泛的生态和进化影响，群落获得和失去物种，种群随着分水岭土地使用而进化(改变其特征)。我现在要问的是，这些变化是否会让社区对气候变暖的容忍度提高或降低。我的研究计划围绕三个目标展开。首先，使用大数据方法，我的团队将估计数百种湖泊浮游生物和鱼类的耐热性。然后，我们将使用两个大型标准化调查，对浮游动物(加拿大全国664个湖泊)和鱼类(魁北克768个湖泊)进行调查，这些调查来自不同分水岭土地利用(从原始到高度农业)的湖泊，并量化这些湖泊中动物的“平均耐热性”。其次，我们将依靠最先进的实验设施，在98个实验池塘中将浮游生物群落暴露在农业污染之下。我们将进行一项独特的大规模实验，基于野外数据，将浮游生物暴露在两种不同的农业污染梯度中。我们将跟踪生态和进化反应，然后将社区暴露在一个实验性但现实的热浪事件中，以测试污染是否影响了热耐力。最后，我们将从不同流域土地利用的湖泊中采集浮游动物和鱼的样本，并用已建立的生理测试来测量它们的耐热性。这将使我们能够确定在原始和受污染的地点发现的(同一物种)种群在耐热性方面是否存在差异。作为一个整体，该计划将评估农业土地利用和气候变化是否可能对湖泊动物产生相加或相互作用(对抗或协同)的影响。这些信息将使我们能够更好地预测和管理加拿大湖泊的生物多样性变化，这些湖泊面临着气候变暖和流域农业集约化的问题。

Canadians are the stewards of more inland water bodies than any other country in the world, a unique resource we have committed to preserve via the Canada water act. Yet, freshwater ecosystems face a number of threats that include pollution linked to watershed land use, and warming waters due to directional climate change and more frequent heat waves. Predicting impacts of these threats on freshwater biodiversity requires an assessment of their interactive effects, namely their impact when acting individually and when acting in combination. My research program will disentangle the interactive effects of climate warming and agricultural pollution on freshwater animals (plankton and fish) in Canada. My previous research has shown that agricultural pollution causes widespread ecological and evolutionary effects in freshwater ecosystems, with communities gaining and losing species and with populations evolving (changing their traits) in response to watershed land use. I will now ask whether these changes make communities more or less tolerant of a warming climate. My research program is centered around three objectives. First, using a 'big data' approach, my team will estimate the thermal tolerance of hundreds of species of lake plankton and fish. We will then use two large standardized surveys of zooplankton (664 lakes across Canada) and fish (768 lakes in Québec) from lakes that differ in watershed land use (from pristine to highly agricultural) and quantify the 'mean thermal tolerance' of animals in these lakes. Second, we will rely on a state-of-the-art experimental facility to expose plankton communities to agricultural pollution in 98 experimental ponds. We will conduct a unique large-scale experiment, exposing plankton to two gradients of agricultural pollution based on field data. We will track ecological and evolutionary responses, and then expose communities to an experimental but realistic heat wave event to test whether pollution influenced thermal tolerance. Finally, we will sample zooplankton and fish from lakes that differ in watershed land use and measure their thermal tolerance with established physiological assays. This will allow us to determine whether populations (of the same species) found in pristine vs. polluted sites differ in their thermal tolerance. As a whole, this program will assess whether agricultural land use and climate change are likely to have additive or interactive (antagonistic or synergistic) effects on lake animals. This information will allow us to better predict and manage biodiversity change in Canadian lakes facing a warming climate and intensifying agriculture in their watersheds.