Trophic Dynamics of a Changing Zooplankton Community

这是对密歇根湖生态系统的一个案例研究。该研究计划的基本目标是通过对大规模自然扰动的调查，提高对食物网络关系、生产力和招聘过程的理解。最近，一种捕食性无脊椎动物入侵了劳伦斯五大湖，这种捕食性无脊椎动物以前从未在北极洲出现过，改变了中等营养水平的生态系统食物网。随后，浮游动物物种组成和一些鱼类物种的补充成功发生了变化。这些变化可能是相互关联的。入侵的捕食者到达密歇根湖的过程已经被记录下来，第一次食物网的变化已经被量化，并建立了可以判断变化的背景和基线条件。来自密歇根湖的结果促使人们对华盛顿湖的历史数据进行了新的审查，这是最重要的模拟研究之一，并发现营养物质在生态系统层面产生的结果与食物网变化产生的结果截然不同。自从食肉动物Bythotrephes和Leptodora引入以来，密歇根湖的食物网的结构发生了很大的变化。在捕食者到来之前，该湖正在进行研究，继续研究其食物链动态和群落结构将为水生生态系统适应其食物网中的主要扰动提供重要的见解。大湖生态系统的封闭性质使其成为进行此类调查的理想地点。

This is a case study of the Lake Michigan ecosystem. The basic goal of the research program has been to improve understanding of food web relations, productivity and recruitment processes through the investigation of large-scale natural perturbations. Recent invasion of the laurentian Great Lakes by a predatory invertebrate never before present in the Nearctic has altered ecosystem food webs at a middle trophic level. Changes have subsequently occurred in zooplankton species composition, and in recruitment success of some fish species. These changes may be linked. The arrival of the invading predator in Lake Michigan has been documented, the first food web changes have been quantified, and the background, baseline conditions against which changes can be judged have been established. The results from Lake Michigan prompted a new examination of historical data from Lake Washington, one of the most important analog studies, and yielded the discovery that nutrients produce distinctly different results at the ecosystem level than do food web changes. %%% The structure of the food web of Lake Michigan has changed substantially since the introduction of the predators Bythotrephes and Leptodora. The lake was under study before the predators arrived, and continued examination of its food chain dynamics and community structure will provide important insight on the adjustment of aquatic ecosystems to major perturbations in their food webs. The contained nature of the Great Lake ecosystem makes it an ideal site for such an investigation.