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特性至关重要。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，这威胁到生态系统的功能和提供有价值的服务。大量的研究着眼于个体环境压力源（如营养物质、温度）对生态系统功能的影响，尽管通常是在单个尺度上，如个体或群落。我们预测社区和生态系统对多个共同发生的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，这对生态系统管理来说是有问题的，因为压力源经常相互作用，这样它们的综合影响大于（或小于）每个压力源的简单总和。尽管管理目标是针对生态系统水平，但很少有研究调查个体生活史反应是否会扩大到生态系统功能的变化。******我提出的研究通过测试预测生态系统功能变化的两种方法来解决这一挑战；1)从关键物种的生活史响应放大预测生态系统功能；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，以安大略省湖泊的5个重要环境压力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。我们关注浮游动物是因为它们可以控制藻类数量（与饮用水质量有关），并为更高营养水平（与渔业有关）提供能量。浮游动物群落是多尺度实验的理想选择，因为它们的繁殖时间短，可以在实验室条件下作为个体生长，也可以在野外条件下在多样化的多营养群落中生长，并且它们对环境压力具有一定的耐受性。******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，代替几乎不可能完成的实验评估生态系统对每种可能压力源组合的反应的任务。这将有助于管理者和决策者优先保护有价值的生态系统服务。该研究项目将培养3名博士、3名硕士、1名PDF和至少15名理学士，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、沟通和协作。这些都是环境领域急需的技能，但也可以转移到其他需要批判性思维、定量分析能力、沟通能力和强大领导能力的职业中。* * * * *

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. *****