Wednesday, June 6, 2007 - 8:45 AM
165

Fishes and Floods in Prairie Streams

Katie N. Bertrand1, Justin N. Murdock1, Keith B. Gido1, Walter K. Dodds1, and Matt R. Whiles2. (1) Division of Biology, Kansas State University, 116 Ackert Hall, Manhattan, KS 66506, (2) Department of Zoology and Center for Ecology, Southern Illinois University, Life Science II, Carbondale, IL 62901

Climate change in the Great Plains may lead to less frequent, more severe precipitation events and may alter the disturbance regime of streams.  Because these changes will likely accompany changes in species composition, it is important to understand how their interaction influences stream ecosystem structure and function.  Using experimental streams and a natural stream, we tested the interactive effects of flood frequency and two functional groups of fishes (benthic grazers and water column omnivores) on stream ecosystem processes.  Simulated flooding of experimental streams exported a large proportion of algae, detritus and invertebrates from these systems.  Both groups of fishes affected recovery of ecosystem processes by stimulating primary production following floods.  However, some of these effects were transient or dependent on flood frequency.  In the natural stream, post-flood recovery was not influenced by fish treatment, rather ecosystem processes varied with position in the watershed, and recovery progressed similar to experimental streams treated with a single flood.  We hypothesize differences in response to fish treatments was because field enclosures did not account for nutrient remineralization by fishes.  Overall, fishes and floods dually control prairie stream ecosystems, and our research suggests that the link between structural and functional changes is highly context dependent.