OPUS: Collaborative Research: Analysis of Cross-Boundary Fluxes, Trophic Cascades and Ecosystem Stability Based on 32 Years of Whole-Lake Experiments

体型大、寿命长的鱼类有时在水生食物网中占主导地位。它们的优势地位导致小型鱼类数量减少，无脊椎动物数量增加，藻类高度集中，包括在营养丰富的湖泊中形成有毒水华的有毒物种。这些变化伴随着湖泊生产力的变化和限制许多湖泊生产力的营养物质的可用性。通常，顶级掠食者的数量和它们所实施的食物网结构似乎是稳定的，持续多年。 然而，稳定优势种群的顶级捕食者的因素还没有得到很好的理解。研究人员将调查从陆地运输的物质，包括溶解的以及树叶等大颗粒，是否有助于支持顶级捕食者的生产，从而稳定它们在湖泊食物网中的主导地位。 研究人员将对自1984年以来从研究湖泊收集的数据进行存档，并向公众提供。多名学生将在该项目的过程中接受培训，这项研究的结果将通过博客文章向公众传达。1984-2015年，研究人员在一系列湖泊中进行了一系列实验，研究了食物网的稳定性和变化，以应对捕食者的收获和放养以及营养物质的富集。 其他实验研究了陆地有机物对许多消费者，包括大型长寿鱼类的生产的贡献。然而，到目前为止，各个实验都是单独分析的。需要对整套实验进行全面评价，以确定陆地有机物在食物网格局中的作用以及食物网对收获、储存和养分富集的反应。更具体地说，来自全湖实验的现有数据将用于调查：（1）营养物质、陆地溶解有机物（DOM）和陆地有机物的消费者同化的相互作用（外来）对食草浮游动物生物量和大型食草动物抵御捕食的能力，（2）陆地猎物对湖泊食物网稳定性和恢复力以及营养级联强度的影响;（3）营养盐、陆地DOM和食物网结构对整个生态系统呼吸的调节。 除了对基础科学的贡献之外，该项目还将创建一个在线的，公开的32年全湖实验数据数据库，培训学生使用大规模实验数据，并创建博客文章，为普通观众展示研究结果。

Large-bodied, long-lived fishes sometimes dominate aquatic food webs. Their rise to dominance causes declines in abundance of small-bodied fishes, rise in abundance of invertebrates, and high concentrations of algae, including noxious species that form toxic blooms in nutrient-rich lakes. These modifications are accompanied by changes in lake productivity and availability of nutrients that limit the productivity in many lakes. Often the populations of top predators and the food web structure that they enforce appear to be stable, persisting for many years. However, the factors that stabilize dominant populations of top predators are not well understood. The researchers will investigate if material transported from land, including dissolved as well as large particles such as leaves, help to support the production of top predators and thereby stabilize their dominance in lake food webs. The investigators will archive data collected from the study lakes since 1984 and make them available to the public. Multiple students will be trained during the course of this project and the findings from this study will be communicated to the public through blog postings. The investigators in a series of experiments from 1984-2015 in a suite of lakes investigated stability and change in food webs in response to predator harvest and stocking as well as nutrient enrichment. Other experiments studied the contributions of terrestrial organic matter to production of many consumers including large-bodied long-lived fishes. So far, however, the individual experiments have been analyzed separately. A comprehensive evaluation of the full set of experiments is needed to determine the role of terrestrial organic matter in food web patterns and the response of food webs to harvest, stocking and nutrient enrichment. More specifically, existing data from whole lake experiments will be used to investigate: (1) the interactive effects of nutrients, terrestrial dissolved organic matter (DOM), and consumer assimilation of terrestrial organic matter (allochthony) on the biomass of herbivorous zooplankton and the capacity of large-bodied grazers to withstand predation, (2) the effects of terrestrial prey on the stability and resilience of lake food webs and the strength of trophic cascades, and (3) the regulation of whole-ecosystem respiration by nutrients, terrestrial DOM, and food web structure. Beyond this contribution to basic science, the project will create an online, publicly-available database of data from the 32 years of whole lake experiments, train students in the use of large-scale experimental data, and create blog posts that present results of the research for a general audience.