Collaborative Research: Food-Chain Length in Streams-Testing the Role of Ecosystem Size, Resource Availability and Disturbance

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Collaborative Research: Food-Chain Length in Streams-Testing the Role of Ecosystem Size, Resource Availability and Disturbance.Sabo, John L.Arizona State UniversityA critical determinant of community structure and ecosystem function is food-chain length, a measure of the number of times energy and materials are transferred from the bottom to the top of a food web. Food-chain length affects community structure by altering trophic interactions, influences ecosystem functions, and, in part, determines the concentration of contaminants in top predators, including many fish that humans eat. Food-chain length is also strongly affected by human activities through, e.g., harvesting activities and habitat fragmentation. Despite the central place of food-chain length in ecology, relatively little is known about the factors controlling this fundamental food web property. This project focuses on how ecosystem size, resource availability and disturbance govern food-chain length in food webs found in river ecosystems. To address this question, the project will compare data collected from 40+ rivers across North America, using existing data sets as well as making new field measurements and applying stable isotope techniques to estimate food-chain length. A deeper understanding of food-chain length in streams will help elucidate the complex linkages between ongoing and accelerating human environmental changes on important societal concerns such as contaminant concentrations, biodiversity, and carbon cycling. This project will support the collaboration of three new faculty members during the crucial early phase of their careers, train a postdoctoral fellow, one graduate student, and several undergraduates in cross-disciplinary research, and conduct a hands on K-12 outreach effort in local high schools using stream food webs as a tool for representing ecological complexity and for teaching an appreciation of the importance of biodiversity.