Elemental Homeostasis at the Individual, Guild and Ecosystem Levels

与周围环境相比，SternerDEB 9815597组织的内部营养含量往往更不变。这种现象，即动态平衡，是生态化学计量学的核心因素。在水生生态系统中，浮游动物的营养物质含量比它们所消费的浮游植物表现出更小的变异性。在这个项目中，将通过实验室和实地调查相结合的方式，在种群、社区和生态系统层面上检查营养物质的动态平衡。实验室实验将重点放在五种浮游动物上，这些浮游动物是因为它们的营养成分广泛而被挑选出来的。动物将被喂以不同营养比例的食物，并将评估动物反应的时间尺度。在实地项目中，将对明尼苏达州60个湖泊的食物资源、浮游动物和鱼类的营养化学进行比较，这些湖泊代表着一个南北倾斜的湖群。据推测，化学变化将减少从藻类到鱼类的湖泊食物链的上游。该项目将测试不同栖息地的营养水平之间的正负相关性。

SternerDEB 9815597Organisms tend to be more invariant in the internal nutrient content that their surrounding environments. This phenomenon, homeostasis, is a central factor in ecological stoichiometry. In aquatic ecosystems, zooplankton exhibit substantially less variability in their nutrient content than the phytoplankton that they consume. In this project, nutrient homeostasis will be examined at the population, community and ecosystem level using a combination of laboratory and field investigations. Laboratory experiments will focus on five species of zooplankton chosen for their wide range of nutrient contents. Animals will be fed food with different nutrient ratios and the time scales of animal response will be evaluated. In field projects, the nutrient chemistry of food resources, zooplankton and fishes will be compared across a set of 60 lakes in Minnesota representing a north-south cline. It is hypothesized that chemical variability will decrease moving up the lakes' food chains from algae to fish. The project will test for a combination of positive and negative correlations across trophic levels in the different habitats.