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Tuesday, January 30 • 11:20am - 11:40am
ASIAN CARP & OTHER AQUATIC INVASIVES: Battle of the Claws: Competition Between Two Non-native Crayfish Species in the Chicago Region and Potential Spread of Red Swamp Crayfish Throughout the Great Lakes Region

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AUTHORS. Erin O'Shaughnessey, Dr. Reuben Keller - Loyola University Chicago

ABSTRACT. Non-native crayfish species pose a serious threat to aquatic ecosystems. They have been shown to decrease macroinvertebrate density and diversity, displace native crayfish, and alter fish communities, damaging sport fish populations. We have identified a reproducing population of red swamp crayfish (Procambarus clarkii)in the Chicago region that overlaps with a population of rusty crayfish (Orconectes rusticus), a previous and widely distributed invader across the Great Lakes region. The competitive interactions between these species, both of which have large ecosystem impacts, may provide a guide to impacts if P. clarkii continues to spread. We used competition assays to examine interactions between the two species. Size matched individuals collected from the overlapping populations were used to examine interspecific competition for food (n=21 trials) and shelter (n=23). O. rusticus were more likely to spend time in the shelter during the trial period (n=13/23) than P. clarkii (n=4/23). P. clarkii ate the food in more of the food competition trials (n=14/21) and did so more quickly (average time to consumption of 58.21 minutes) when compared to the trials in which O. rusticus ate the food (n=7/21, 81.40 minutes). We used field tethering experiments to examine predation differences between P. clarkii and O. rusticus at two different sites within their overlapping range. Both P. clarkii (n=21/60 vs. n= 18/63)and O. rusticus (n= 10/41 vs. 3/37) were predated on more at Wilmette Harbor than at the North Shore Channel. The success of P. clarkii in the field, combined with our experimental results, indicate that this new invader may be competitively dominant and capable of spreading into freshwater ecosystems where O. rusticus is well established. If this occurs, the total impact of crayfish in rivers and lakes across the Great Lakes region is likely to grow with the potential to cause widespread ecosystem changes.

Tuesday January 30, 2018 11:20am - 11:40am CST