Community and ecosystem dynamics of north temperate shallow lakes during the Anthropocene

内陆沃茨为人类提供了许多重要的服务（例如，农业沃茨、维持生物多样性的生境和娱乐场所），但这些生态系统在压力之下很容易发生变化。特别是浅水湖泊，当压力稍微增加时，会突然从清澈的水状态变成浑浊的状态。然而，浅水湖泊的突然变化并不总是被观察到，环境和生态条件仍然存在相当大的不确定性，使这些系统容易突然变化。 越来越多的理论和观测数据描述了压力的微小变化如何导致生态系统状态的突然转变，这被称为关键转变。然而，需要对时间序列和新的实地实验进行综合分析，以回答挥之不去的问题，包括哪些因素的组合使生态系统容易受到状态突变的影响？这些非线性动力学有多普遍？通过对大型数据集的实验和分析的新组合，我将量化浅水湖泊在不同时间尺度上对多种压力源的反应。我还将在大量的户外实验池塘中确定关键转变的触发因素。这项工作建立在我以前的NSERC发现资助的基础上，我的团队研究了沉积物档案，以记录温带浅水湖泊过去的生态变化，并进行了湖泊调查，以促进我们对这些生态系统的结构和功能的理解。 在过去几年中，有人认为，我们整个地球可能正在接近一个关键的转变。目前，要检验这些“全球关键转型”论点的有效性即使不是不可能，也是极其困难的，因为对于这种变化如何在浅水湖等较小、易处理的生态系统中发挥作用仍然存在疑问。我的研究旨在阐明温带浅水湖泊如何应对过去200年来人类活动带来的加速变化，并为保护优先事项和行动提供信息。如果我们对这些问题的认识没有重大进展，我们将对我们环境的突然变化及其后果毫无准备。

Inland waters provide humanity with numerous important services (e.g., waters for agriculture, habitats for sustaining biodiversity and sites for recreation) but these ecosystems become vulnerable to change under pressure. Shallow lakes, in particular, can change abruptly from a clear-water state to a turbid state when exposed to minor increases in stress. Yet, abrupt changes in shallow lakes are not always observed and considerable uncertainty remains about the environmental and ecological conditions that render these systems susceptible to changing suddenly. There is a growing body of theory and observational data describing how minor changes in stress cause sudden ecosystem state shifts, which are referred to as critical transitions. However, synthetic analyses of time series and new field experiments are needed to answer lingering questions, including which combination of factors make ecosystems vulnerable to abrupt changes in state? and, how common are these nonlinear dynamics? Through a novel blend of experiments and analyses of large datasets, I will quantify how shallow lakes have responded to multiple stressors over different time scales. I will also identify triggers of critical transitions in a large array of outdoor experimental ponds. This work builds upon my previous NSERC Discovery grant, where my team studied sediment archives to develop records of past ecological changes in temperate shallow lakes and conducted lake surveys to advance our understanding of the structure and functioning of these ecosystems. In the past few years, it has been argued that our entire planet may be approaching a critical transition. It is currently extremely difficult, if not impossible, to test the validity of these “global critical transition” arguments given that there are still questions about how such changes operate in smaller, tractable ecosystems like shallow lakes. My research is designed to elucidate how temperate shallow lakes have responded to the accelerating rate of change introduced by human activities over the past ~200 years and to inform conservation priorities and actions. Without serious advancement in our knowledge of these issues, we will remain unprepared for sudden changes in our environment and their consequences.