Elemental Homeostasis at the Individual, Guild and Ecosystem Levels

生物体内的营养成分往往比它们周围的环境更不稳定。这种现象，即体内平衡，是生态化学计量学的一个核心因素。在水生生态系统中，浮游动物在营养成分上的变异性比它们所消耗的浮游植物要小得多。在这个项目中，将利用实验室和实地调查相结合的方法，在种群、群落和生态系统水平上检查营养稳态。实验室实验将集中在五种浮游动物上，因为它们的营养成分范围很广。研究人员将给动物喂食不同营养比例的食物，并评估动物反应的时间尺度。在实地项目中，将比较明尼苏达州60个湖泊的食物资源、浮游动物和鱼类的营养化学成分，这些湖泊代表着南北倾斜。据推测，从藻类到鱼类，湖泊食物链上游的化学变化将会减少。该项目将在不同栖息地的营养水平上测试正相关和负相关的组合。

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.