Cascading Trophic Interactions in Lake Ecosystems: Effects on Bacteria and Their Consumers

异养微生物加工了水生生态系统初级产品的很大一部分。这项研究将研究食物网的相互作用如何控制微生物的生产力。圣母大学环境研究中心正在进行全湖实验，通过控制鱼类数量来改变浮游生物食物网。本项目将研究异养微生物群落的响应。计划操作的效果将是减少浮游动物生物量和增加浮游植物生物量和生产力。据推测，细菌、原生动物、细菌生产和对细菌的放牧都将增加对这些操作的反应。微生物活性的增强也将导致水体总呼吸速率的提高。将测量生物量、生产力、异养微生物的放牧以及群落呼吸，以在生态系统尺度上检验这些假设。食物网对异养微生物的直接和间接影响将在圈闭实验和模型研究中进一步研究。该研究结果将对湖泊生物动态的基本认识具有重要意义，并可能适用于湖泊管理的新策略。

Heterotrophic microorganisms process a substantial portion of the primary production of aquatic ecosystems. This research will examine how food web interactions control microbial productivity. Whole lake experiments are being conducted at the University of Notre Dame Environmental Research Center that manipulate fish populations that in turn modify the planktonic food web. This project will study the response of the heterotrophic microbial community. The effect of planned manipulations will be to decrease zooplankton biomass and increase phytoplankton biomass and productivity. It is hypothesized that bacteria, protozoa, bacterial production, and grazing on bacteria will all increase in response to these manipulations. The enhanced microbial activity in the manipulated lakes will also lead to higher rates of total water column respiration. Measurements of the biomass, productivity, grazing by heterotrophic microbes as well as community respiration will be made to test these hypotheses at the ecosystem scale. The direct and indirect effects of the food web on heterotrophic microbes will be further examined in enclosure experiments and modeling studies. Results from this study will likely be of major significance in terms of the basic understanding of the biotic dynamics of lakes and may be applicable to new strategies for lake management.