Meeting Abstract
Orconectes rusticus is a prolific invasive crayfish species that has invaded a broad geographic range and has displaced several crayfish species. Previous studies have investigated the differences in life stages and physical characteristics of Orconectes sanbornii and Orconectes rusticus but did not include individual foraging behavior in their comparisons. A better understanding of the behavior of O. rusticus is needed to understand why it is such a successful invader. In Ohio streams O. rusticus has been displacing O. sanbornii in a major portion of its natural range. Here we tested whether native O. sanbornii were displaced by invasive O. rusticus through superior foraging and whether foraging behavior changed in the presence of a model fish predator. We used depletable food patches of chicken liver to compare the foraging behavior of native O. sanbornii and invasive and native populations of O. rusticus under high, low or no predation risk. We then measured the remaining food concentrations in each patch after a 24-hour period as an indication of giving up density (GUD). We found that there was no significant effect of predation risk on the GUD of either species. However, O. sanbornii left significantly lower GUDs on average than either native or invasive populations of O. rusticus. Which suggests that O. sanbornii is a more active forager than O. rusticus. Our research indicates that the invasion mechanism that O. rusticus employs to displace O. sanbornii is not exploitative foraging but rather an unidentified mechanism. Gaining a better understanding and being able to better identify the mechanisms of species invasions can lead to better and more effective management of invasive species in the future.
