Assessing the impacts of rusty crayfish (Orconectes rusticus) on submergent macrophytes in a north-temperate US lake using electric fences

Electric "fences" were used along with hand removal to experimentally reduce rusty crayfish (Orconectes rusticus) densities in a lake. The goals of this experiment were to determine the impacts of crayfish on three macrophytes species, Potamogelon amplifolius, P. richardsonii and Elodea canadensis and to assess the effectiveness of our electric fences. While future enhancements of our experimental design will be more effective in lakes, we were able to significantly reduce crayfish densities in electric plots compared to non-electric control plots using the electric fence method. Even at reduced densities, crayfish had a large selective impact on the macrophytes. Potamogeton richardsonii and E. canadensis were eliminated within a matter of days in the control plots and within 3 wk in the electric plots. P. amplifolius, on the other hand, survived in both plots; although crayfish reduced shoot and root dry weight in the non-electric control plots. Our results have implications for future macrophyte restoration efforts.