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Presented at the NABS Annual meeting, Pittsburgh, Pennsylvania, 2002
in Conservation Ecology
PREDICITNG THE COMMUNITY EFFECTS OF INVASIONS OF RUSTY CRAYFISH (ORCONECTES RUSTICUS) IN SOUTHERN ILLINOIS STREAMS USING LABORATORY COMPETITION TRIALS.
W.L. Perry and K. Szela. Department of Biology, Illinois State University, Normal, Illinois 61790-4120
Crayfish biodiversity in North America is the greatest in the world, but many populations occupy small ranges and are at risk of extinction. A major threat to this biodiversity results from nonindigenous species, particularly crayfishes such as the rusty crayfish (Orconectes rusticus). O. rusticus has colonized many lakes and streams of eastern North America primarily because of their use as bait. O. rusticus has been introduced into Illinois and may colonize tributaries in southern Illinois where several threatened and endangered species, O. illinoiensis, O. indianesis, O. kentuckiensis, O. stannardi, and O. placidus, occupy limited ranges. Competitive differences between crayfishes have been shown to be a primary mechanism explaining the success of invading crayfishes. We used short-term laboratory experiments to test for competitive differences between O. rusticus and the resident species in size and sex matched trials for food and shelter. O. rusticus were competitively dominant to resident crayfishes (P<0.05). No competitive differences were observed among male O. illinoiensis, O. indianesis, and O. placidus (P>0.05). Female O. placidus, however, were competitively dominant to O. illinoiensis and O. indianesis in preliminary trials. Our results suggest O. rusticus has the potential to displace these endangered species through competition in southern Illinois.
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