Food Web Responses to Environmental Productivity and Predation

食肉动物可以有积极和消极的影响， 人口。 积极的影响可能是直接的，也可能涉及 食物网中的其他物种。 营养素是如何影响 生产可能会与食肉动物的影响， 营养水平尚未调查。 实验 在这四个食物网中， 营养水平和5个蝾螈捕食水平， 75个户外生态系统的阵列。 这四个食物网的区别在于 蛙幼虫和水蚤的出现。 社区 浮游动物，浮游植物， 将监测沿岸的甲壳类和附着生物。 是 预测这些生物对捕食的反应， 营养水平在很大程度上取决于食物的结构 网。 这将是第一个测试这种 预测。 这些调查应该提供关键的 了解自然变化的见解丰富的 生物和预测社区的反应 富营养化和捕食强度的变化。

Carnivores can have positive as well as negative effects on populations. Positive effects may be direct or they may involve other species in the food web. How nutrients that affect production might interact with a carnivore's impact on lower trophic levels has not been investigated. Experiments are proposed in which four food webs will be exposed to up to 5 levels of nutrients and 5 levels of predation by newts in an array of 75 outdoor mesocosms. The four food webs will differ in the occurrence of Rana larvae and Daphnia. Community development and production of zooplankton, phytoplankton, littoral crustaceans and periphyton will be monitored. It is predicted that the responses of these organisms to predation and nutrient levels will depend strongly on the structure of food webs. This will be the first experiment to test such predictions. These investigations should provide critical insights for understanding natural variation in the abundance of organisms and in predicting the responses of communities to eutrophication and changes in predation intensity.