DISSERTATION RESEARCH: Food Webs in Space: The Interplay Between Dispersal and Trophic Interactions

营养相互作用(捕食者对猎物的消耗)定义了食物网中能量和营养的流动。许多参与营养相互作用的生物也能够在适宜栖息地的区域之间移动(分散)。例如，捕食者在吃了一块栖息地的猎物后，可能会分散到另一块栖息地，然后再吃更多的猎物。生物的这种扩散可能会通过改变斑块内种群的大小来影响营养相互作用的结果。同时，营养相互作用可能会影响种群大小，从而决定可在斑块中分散的有机体数量。因此，营养相互作用和扩散很可能共同决定了局部(斑块内)和区域(斑块间)尺度上食物网的结构和动态。这项研究使用了缅因州阿普雷诺尔岛的一个淡水岩池系统，以确定扩散和营养相互作用如何结合起来影响当地和区域的食物网动态。简单的岩石池塘食物网由浮游植物、食草性浮游动物和捕食性水虫(毛毛虫)组成。先前的研究表明，毛滴虫的捕食强烈地影响了当地的食物网，并且毛滴虫能够在岩石池中扩散。将使用现场实验来量化旋毛虫对岩石池塘食物网的局部和地区性扩散影响。建立了一个特定的数学模型来预测实验的结果，该模型将扩展到其他生态系统，以确定扩散对当地和区域食物网动态的一般影响。本研究结合理论和实证方法，增加对空间结构在食物网动态中的作用的理解。因此，这项研究的结果将为保护和管理受到栖息地碎片化威胁的生态系统提供参考。该项目支持一名研究生的论文研究，并为本科生提供机会，作为多所大学实习计划的一部分，参与实地研究。结果将通过科学出版物和演示文稿、本科课程讲座以及向当地高中生、教师和普通公众进行宣传来广泛传播。

Trophic interactions (the consumption of prey by predators) define the flow of energy and nutrients in food webs. Many organisms involved in trophic interactions are also able to move (disperse) among areas of suitable habitat. For example, after eating a prey item in one patch of habitat, a predator may disperse to another habitat patch before consuming additional prey. Such dispersal of organisms may affect the outcome of trophic interactions by altering the size of populations within patches. At the same time, trophic interactions may influence population sizes, and thus determine the number of organisms available to disperse among patches. As a result, trophic interactions and dispersal likely combine to dictate the structure and dynamics of food webs at the local (within-patch) and regional (among-patch) scales. This study uses a system of freshwater rock pools on Appledore Island, Maine to determine how dispersal and trophic interactions combine to influence local and regional food-web dynamics. The simple rock-pool food web consists of phytoplankton, herbivorous zooplankton, and a predatory water bug (Trichocorixa). Previous research shows that predation by Trichocorixa strongly affects local food webs and that Trichocorixa is capable of dispersing among rock pools. A field experiment will be used to quantify the local and regional effects of dispersal by Trichocorixa on the rock-pool food web. A specific mathematical model has been developed to predict the outcomes of this experiment, and this model will be extended to other ecosystems in order to determine the general effects of dispersal on local and regional food-web dynamics.This study combines theoretical and empirical approaches to increase understanding of the role of spatial structure in food-web dynamics. As such, results of this research will inform the conservation and management of ecosystems threatened by habitat fragmentation. This project supports the dissertation research of one graduate student and provides the opportunity for an undergraduate to be involved in field research as part of a multi-university internship program. Results will be disseminated broadly through scientific publications and presentations, lectures to undergraduate courses, and outreach to local high school students, teachers, and the general public.