Floods shape biological communities in streams by modifying food web characteristics. This study will: (1) identify relationships between floods and the flow of carbon, nitrogen, and phosphorous in stream food webs, and (2) evaluate how risk of predation interacts with high and low levels of flooding to control the cycling of these elements. Measurement of water flow and movement of the streambed will be used to quantify intensity and frequency of floods, and sampling of organisms will provide information on invertebrate densities and their elemental composition. Risk of predation will be manipulated in whole streams by adding chemical cues of predatory fish. This research is designed to improve our understanding of factors influencing elemental cycling in natural systems by integrating the traditionally disparate fields of organismal biology, community ecology, and ecosystem ecology. Results will be useful for responsible management of freshwater resources, which are under pressure worldwide to meet increasing human demands. Natural flow regimes to which organisms are adapted are often altered by humans, and global climate change threatens to intensify modifications. Results from this study should improve the ability to predict and mitigate consequences for river food webs, which have direct societal and economic importance.
