Combined impacts of temperature and trophic cascades in mountain lakes

能量和营养的供应以及食肉或草食动物的数量在生态系统中发挥着重要作用，而气候变化引起的温度或降水变化可能会放大或抑制生态系统。气候与生态过程之间的这种相互作用很难理清，因为生物体通过进化或迁移作出的反应是渐进的、长期的。未来的气候变化改变了营养物和捕食者的作用，可能会损害生态系统为社会提供宝贵服务的能力。气候变化如何改变生态相互作用的不确定性对预测地球生态系统的未来状态提出了巨大挑战。这个项目研究了加州山区湖泊的淡水生物和生态系统如何随着温度和鳟鱼的存在而变化。鱼类强烈地影响它们的猎物，并改变湖泊、陆地和大气之间的物质流动。利用围隔实验和全湖调查，本项目将研究鱼类和温度对湖泊生态地球化学过程的相互影响。此外，研究人员还将研究湖泊生物对环境变化的进化反应如何缓冲种群，使它们能够在不断变化的环境中持续存在。该项目的结果将有助于了解湖泊生态系统如何应对气候变化和捕食者丰度，以及湖泊生态系统是否可以继续以未来环境和社会重要的方式发挥作用。气候和捕食对湖泊生态系统的影响迄今为止一直是孤立研究的。本项目研究了非本地捕食性鱼类（鳟鱼）对沿着海拔（1200米至3300米）的热跃层在内华达州山脉的湖泊生态系统的结构的影响。还将研究重要浮游动物类群的种间和种内形态特征变化，以确定捕食者和沿着自然渐变带变暖的累积影响。此外，研究人员还将测试营养级联和温度对系统代谢、有机物处理和湖泊与大气之间碳通量的相互作用。一个现场的中尺度生态系统移植实验将测试的假设，选择的历史，鱼类和高温缓冲社区对变暖和营养级联通过生态和进化过程相结合。本科生和研究生以及博士后研究员将通过这笔赠款进行培训。该项目的结果直接应用于气候变化中的水资源管理，研究人员将与包括国家公园管理局在内的各种机构分享项目结果。

The supply of energy and nutrients and the numbers of predatory or herbivorous animals play important roles in ecosystems that may be magnified or dampened by changes in temperature or precipitation due to climate change. Such interactions between climate and ecological processes are challenging to disentangle because of gradual, long-term responses of organisms through evolution or migration. Future climate change that alters the roles of nutrients and predators may compromise the capacity of ecosystems to provide valuable services to society. Uncertainty about how climate change alters ecological interactions presents a great challenge to forecasting the future state of the earth's ecosystems. This project examines how freshwater organisms and ecosystems in California mountain lakes change with temperature and the presence of trout that have been stocked for fishing. Fish strongly affect their prey and alter the flow of materials between lakes, the land and the atmosphere. Using mesocosm experiments and whole lake surveys, this project will study the interactive effects of fish and temperature on lake biogeochemical processes. In addition, the researchers will study how evolutionary responses by lake organisms to environmental changes might buffer populations, allowing them to persist in a changing environment. Results from this project will aid in understanding how lake ecosystems respond to changing climate and predator abundance, and whether lake ecosystems can continue to function in ways that are important in the environment and for society in the future.Effects of climate and predation on lake ecosystems have so far been studied in isolation. This project examines the impact of non-native predatory fish (trout) on the structure of lake ecosystems along an elevational (1200m to 3300m) thermal cline in the Sierra Nevada mountains. Interspecific and intraspecific morphological trait variation of important zooplankton taxa will also be studied to determine the cumulative impacts of predators and warming along a natural cline. In addition, the researchers will test the interactive effects of trophic cascades and temperature on system metabolism, processing of organic matter and carbon flux between lakes and the atmosphere. A field mesocosm transplant experiments will test the hypothesis that a history of selection by fish and high temperatures buffers communities against warming and trophic cascades through a combination of ecological and evolutionary processes. Undergraduate and graduate students and a postdoctoral researcher will be trained through this grant. Results from this project have direct applications to water resource management in a changing climate, and the researchers will share project findings with a variety of agencies, including the National Park Service.