A multi-scale approach to identifying the ecological impact of co-occurring environmental stressors

淡水资源对加拿大的经济和文化认同至关重要。安大略省超过70%的饮用水来自地表水，加拿大各地的休闲渔业为当地经济贡献了83亿美元。尽管如此，人类活动正在极大地改变淡水栖息地的物种组成，威胁到生态系统的功能和提供有价值的服务。大量研究着眼于个体环境应激源(如营养物质、温度)对生态系统功能的影响，尽管往往是单一尺度的，例如个人或社区。我们预测社区和生态系统对多个共生压力源的反应的能力非常有限，因为很少有研究考虑多个压力源，这对生态系统管理是有问题的，因为压力源经常相互作用，使它们的综合影响大于(或小于)每个压力源的简单总和。更少的研究考察个体生活史的反应是否与生态系统功能的变化有关，尽管管理目标是针对生态系统层面的。 我提出的研究通过测试两种预测生态系统功能变化的方法来应对这一挑战：1)根据关键物种的生活史响应来预测生态系统功能，以及2)基于物种或功能多样性等群落特征预测生态系统功能。我们将进行多尺度实验并开发模型，使用安大略省湖泊中的5个重要环境应激源对这些方法进行批判性评估：增加氯化物(来自道路盐)、减少钙、营养负荷、升高温度和非本地物种的传播。我们重点关注浮游动物，因为它们可以控制藻类种群(与饮用水质量相关)，并为更高的营养水平(与渔业相关)提供能量。浮游动物群落是多尺度实验的理想选择，因为它们世代时间短，可以在实验室条件下作为个体生长，也可以在野外条件下作为个体生长，并且它们对环境应激源表现出一系列的耐受性。 我们的研究将为科学家和管理者提供预测多种压力源对群落结构和生态系统功能的影响的工具，而不是通过实验评估生态系统对每种可能的压力源组合的反应。这将有助于管理者和政策制定者优先保护有价值的生态系统服务。该研究计划将培训3名博士、3名硕士、1名PDF和至少15名理科学生，内容涉及生态毒理学、实地研究、分类学、实验设计、统计分析、生理建模、交流和协作。这些技能在环境领域备受追捧，但也会转移到其他需要批判性思维、量化技能、沟通和强大领导力的职业。

Freshwater resources are critical to Canada's economy and cultural identity. Over 70% of the drinking water in Ontario comes from surface waters, and recreational fisheries across Canada contribute $8.3 billion to local economies. Despite this, human activities are dramatically altering species composition in freshwater habitats, which threatens ecosystem function and the provision of valuable services. An abundance of research has looked at the impact of individual environmental stressors (e.g., nutrients, temperature) on ecosystem function, although often at a single scale, e.g., individual or community. Our ability to predict community and ecosystem response to multiple, co-occurring stressors is significantly limited because few studies consider multiple stressors, which is problematic for ecosystem management because stressors often interact such that their combined effect is greater (or less) than the simple sum of each stressor. Even fewer studies examine whether individual life history responses scale up to changes in ecosystem function, despite management targets aimed at the ecosystem level. My proposed research addresses this challenge by testing two approaches for predicting changes in ecosystem function; 1) scaling up from life history responses in key species to predict ecosystem function, and 2) predicting ecosystem function based on community traits such as species or functional diversity. We will conduct multi-scale experiments and develop models to critically evaluate these approaches using 5 important environmental stressors in Ontario lakes; increasing chloride (from road salt), decreasing calcium, nutrient loading, increasing temperature and the spread of non-native species. We focus on zooplankton because they can control algal populations (relevant for drinking water quality) and provide energy for higher trophic levels (relevant for fisheries). Zooplankton communities are ideal for multi-scale experiments because they have short generation times, can be grown as individuals under laboratory conditions as well as in diverse, multi-trophic communities under field conditions, and they exhibit a range of tolerances to environmental stressors. Our research will provide scientists and managers tools for predicting the impact of multiple stressors on community structure and ecosystem function, in lieu of the almost impossible task of experimentally evaluating ecosystem response to every possible stressor combination. This will help managers and policy-makers prioritize conservation of valuable ecosystem services. This research program will train 3 PhD, 3 MSc, 1 PDF and at least 15 BSc students in ecotoxicology, field studies, taxonomy, experimental design, statistical analyses, physiological modelling, communication, and collaboration. These are highly sought skills in environmental fields, but also transfer to other careers that require critical thinking, quantitative skills, communication, and strong leadership.