Thursday, May 29, 2008 - 10:45 AM
532

Disturbance and species displacement: Differential tolerance to stream drying and desiccation between native and invasive crayfishes

Eric R. Larson, School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA 98195, Daniel D. Magoulick, USGS, Arkansas Cooperative Fish and Wildlife Research Unit, Department of Biological Sciences, University of Arkansas, Fayetteville, AR 72701, Clinton Turner, University of Arkansas for Medical Sciences, Little Rock, AR 72205, and Kelly H. Laycock, Department of Biological Sciences, Tennessee Technological University, Cookeville, TN 38505.

Crayfish are among the most threatened freshwater taxa in the world and invasive crayfish are the primary cause of native crayfish declines. Most research has emphasized biotic interactions as the mechanism of native crayfish displacement by invasive crayfish, but crayfish occupy stochastic environments and the role of disturbance in facilitating crayfish invasion and displacement is understudied. We evaluated tolerance to stream drying between a native and invasive crayfish as a potential explanatory mechanism for distributional patterns of these species. The native crayfish Orconectes eupunctus was less tolerant of desiccation than the invasive crayfish Orconectes neglectus, with all native crayfish expiring within two days of isolation from water while some individuals of the invasive crayfish survived for nearly two weeks. Under simulated stream drying in mesocosms, O. eupunctus experienced a significant reduction in survival relative to a no drying control while O. neglectus did not. Correlative field sampling demonstrated a significant negative relationship between O. eupunctus abundance and summer low flows at upstream sites, while O. neglectus densities were not affected by stream drying. These results demonstrate the potential importance of abiotic disturbance in crayfish species displacement and illustrate the need for further research into interactions between disturbance and species invasion.


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