Thursday, May 29, 2008 - 11:30 AM
535

Predation and stream drying differentially affect survival and habitat use of a native and invasive crayfish

Daniel D. Magoulick, USGS, Arkansas Cooperative Fish and Wildlife Research Unit, Department of Biological Sciences, University of Arkansas, Fayetteville, AR 72701, Eric R. Larson, School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA 98195, Kelly H. Laycock, Department of Biological Sciences, Tennessee Technological University, Cookeville, TN 38505, and John P. Ludlam, Department of Biological Sciences, University of Arkansas, Fayetteville, AR 72701.

Both predation and disturbance may contribute to the displacement of native crayfishes by invasive crayfish.  In the Ozark Mountains, the native crayfish Orconectes eupunctus has been displaced by the invasive crayfish Orconectes neglectus and we hypothesized that stream drying and predation interact as mechanisms responsible for this displacement.  Using stream mesocosms, we determined whether drying (wet/dry) and predation (smallmouth bass present/absent) interacted to affect survival and refuge use by O. eupunctus and O. neglectus.  Orconectes eupunctus survival showed no drying by predation interaction, but survival was significantly reduced by bass presence regardless of drying treatment.  Orconectes neglectus survival showed a significant drying by predation interaction with no effect of drying when bass were absent, but survival increased significantly in dry treatments when bass were present.  In wet treatments O. neglectus used shallow habitat regardless of bass presence, whereas bass presence caused O. eupunctus to shift from deep to shallow habitats.  In dry treatments O. neglectus used both habitats evenly regardless of bass presence, whereas O. eupunctus used deep habitats in dry treatments exposing them to increased predation by bass.  Disturbance and predation may interact to affect displacement of native species by invasive species.


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