Collaborative Research: Trophic Structure and the Stoichiometry of Nitrogen and Phosphorus in the Pelagic Food Web

生态学家越来越意识到， 能源和化学元素的储存和加工 生态系统受到环境组成的强烈影响 生态系统中的生态群落。 在湖泊中， 大量的“顶级捕食者”（即食鱼鱼类，如 低音）可以对系统的所有级别产生强烈的影响， 包括植物生产者的丰富性和生产力， 化学元素的循环。 这是因为掠夺性 鱼会吃掉以南极洲为食的鱼，比如小鱼， 影响食草性消费者（浮游动物）。 最后， 浮游动物既能调节植物生产者的数量 （浮游植物）和分解者（细菌）和再循环营养物质。 该项目的重点是食物网结构对 微生物关键营养元素的相对有效性 生长（氮和磷）。 它测试了一个 最近发展起来的基于生理学的理论， 了解不同的浮游动物物种如何再生氮 和食物中的磷 通过改变动力学 这些食草性浮游动物中， 影响氮磷循环。 设在 加拿大实验湖区的主要研究方法 将涉及对营养物质的实验操作， 湖泊大型围隔中的浮游动物以及整个湖泊 操纵食物网结构（通过引进派克， 这两个湖泊缺乏这种食鱼物种）。 这些研究 直接应用于理解 控制生态系统中的元素循环;这些过程发挥 在直接社会的各个领域发挥关键作用，包括 全球气候变化， 环境恶化和供水恶化。

Ecologists are increasingly realizing that patterns of storage and processing of energy and chemical elements in ecosystems are strongly influenced by the composition of the ecological communities present in the ecosystem. In lakes, the abundance of "top predators" (i.e. fish-eating fish species like bass) can have strong effects on all levels of the system, including the abundance and productivity of plant producers and the cycling of chemical elements. This occurs because predatory fish consume plankton-feeding fish, like minnows, which in turn influence herbivorous consumers (zooplankton). Finally, zooplankton both regulate the abundance of plant producers (phytoplankton) and decomposers (bacteria) and recycle nutrients. This project focusses on the effects of food web structure on the relative availability of nutrient elements critical for microbial growth (nitrogen and phosphorus). It tests the predictions of a recently-developed, physiologically-based theory designed to understand how different zooplankton species regenerate nitrogen and phosphorus present in their food. By altering the dynamics of these herbivorous zooplankton, fish predation can therefore influence the cycling of nitrogen and phosphorus. Based at the Experimental Lakes Area in Canada, the main research approaches will in involve experimental manipulations of nutrients and zooplankton in large enclosures in lakes as well as whole-lake manipulations of food-web structure (via introduction of pike to two lakes which lack such a fish-eating species). THese studies have direct application to understanding the processes controlling elemental cycling in ecosystems; such processes play a critical role in various areas of direct societal, including global climate change, the dynamics of contaminants in the environment, and degradation of water supplies.