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

体型庞大、寿命长的鱼类有时主宰着水生食物网。它们的崛起导致了小型鱼类数量的减少，无脊椎动物数量的增加，以及藻类的高浓度，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和营养物质可得性的变化，这些变化限制了许多湖泊的生产力。通常情况下，顶级捕食者的数量和它们所维持的食物网结构似乎是稳定的，可以持续多年。然而，稳定顶级捕食者优势种群的因素尚未得到很好的理解。研究人员将调查从陆地运输的物质，包括溶解的以及像叶子这样的大颗粒，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。调查人员将把从1984年以来从研究湖泊收集的数据存档，并向公众开放。在这个项目的过程中，将有多名学生接受培训，研究结果将通过博客发布给公众。从1984年到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。其他实验研究了陆生有机物对许多消费者的生产的贡献，包括大型长寿鱼类。然而，到目前为止，每个实验都是单独分析的。需要对全套实验进行综合评价，以确定陆生有机质在食物网格局中的作用以及食物网对收获、放养和养分富集的响应。更具体地说，整个湖泊实验的现有数据将用于调查：(1)营养物、陆源溶解有机质（DOM）和陆源有机质消费同化对草食性浮游动物生物量和大型食草动物捕食能力的交互作用；(2)陆源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)营养物、陆源溶解有机质和食物网结构对全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、公开的数据库，其中包含32年来整个湖泊的实验数据，培训学生使用大规模实验数据，并创建博客文章，向一般读者展示研究结果。

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.