Regulation of Heterotrophic Microbial Processes in Lake Ecosystems

纽约植物园生态系统研究所异养微生物负责生态系统中生物生产力和生物地球化学循环的主要部分。然而，对微生物过程的调控却知之甚少。该项目将研究水生生态系统的两个关键特性--初级生产力和食物网络结构--如何调节异养微生物的生物量、呼吸和生产力，包括细菌、鞭毛原生动物和纤毛原生动物。这项研究将利用已经由美国国家科学基金会资助的全湖实验。四个湖泊的食物网将被操纵，以增强浮游性或食鱼性鱼类的优势。其中两个有替代食物网的湖泊的营养负荷将增加，以提高浮游植物的初级生产力和生物量。佩斯和科尔假设，异养微生物过程在水生生态系统中是一个相对保守的特征。这些实验中异养微生物过程的变化主要是初级生产力和浮游植物生物量变化的结果，其次是浮游植物群落结构变化的结果。为了加强实验结果的普遍适用性，这些假设将通过对20个湖泊的细菌生产力和生物量的比较研究来验证。模拟和逆向食物网模型将被用来研究食物网结构和初级生产的可变性如何影响微生物过程，以及微生物过程的可变性如何影响系统的其他组成部分。佩斯和科尔都是多产的年轻科学家。这项研究得到了极好的制度支持。

New York Botanical Garden, Institute of Ecosystem Studies Heterotrophic microorganisms are responsible for a major portion of the biological productivity and biogeochemical cycling in ecosystems. Regulation of microbial processes, however, is poorly understood. This project will examine how two key properties of aquatic ecosystems, primary production and food web structure, regulate the biomass, respiration, and productivity of heterotrophic microbes including bacteria, flagellated protozoans and ciliated protozoans. This research will take advantage of whole lake experiments already funded by NSF. Food webs in four lakes will be manipulated to enhance dominance by either planktivorous or piscivorous fish. Nutrient loading in two of these lakes with alternative food webs will be increased to elevate phytoplankton primary production and biomass. Pace and Cole hypothesize that heterotrophic microbial processes are a relatively conservative feature in aquatic ecosystems. Changes in heterotrophic microbial processes in these experiments will be primarily a result of changes in primary production and phytoplankton biomass and secondarily a result of changes in phytoplankton community structure. To strengthen the general applicability of the experimental results, these hypotheses will be tested by a comparative study of bacterial productivity and biomass in 20 lakes. Simulation and inverse food web models will be used to examine how variability in food web structure and primary production influences microbial processes and how variability in microbial processes influence other components of the system. Pace and Cole are productive young scientists. The institutional support for this research is excellent.