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Presented at the NABS Annual meeting, Pittsburgh, Pennsylvania, 2002
in Disturbance Ecology III
DO INTERMITTENT STREAMS FUNCTION AS REFUGIA FOR CRAYFISH?
D.D. Magoulick1 and C.A. Flinders2. 1U.S.G.S., Arkansas Cooperative Fish and Wildlife Research Unit, Department of Biological Sciences, University of Arkansas, Fayetteville, AR 72701, 2Patrick Center for Environmental Research, Academy of Natural Sciences, Philadelphia, PA 19103
Drought and summer drying can be important disturbance events in many small streams leading to intermittent or isolated habitats. We sampled riffle, run, and pool macrohabitats in 15 intermittent and 21 permanent streams in the Spring River watershed (Ozark Plateau) of northern Arkansas and southern Missouri to determine the effects of flow regime on crayfish community structure as it pertains to crayfish macrohabitat selection, species composition and richness, and density. Crayfish densities were significantly greater in intermittent than in permanent streams, whereas crayfish species richness did not differ significantly between the two stream types. Densities of Orconectes marchandi and O. punctimanus were significantly greater in intermittent than in permanent streams, whereas densities of O. ozarkae and Cambarus hubbsi did not differ significantly between the two stream types. There was a significant relationship between crayfish relative abundance and abiotic environmental variables for permanent, but not intermittent streams. In permanent streams, substrate diversity and percent gravel were the most important factors in determining crayfish abundance. Reduced predation risk in intermittent streams, along with morphological and behavioral adaptations of crayfish species, are likely explanations for observed patterns. Results suggest that intermittent streams may function as refugia for some species and size classes of crayfish.
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