Behavioral Responses of the Northern Crayfish (Faxonius virilis) to Physical Presence and Chemical Cue from the Invasive Rusty Crayfish (F. rusticus)

Invasive species have the potential to extirpate native species and disrupt ecosystems. The rusty crayfish (Faxonius rusticus) has invaded many freshwater environments outside its native range. Compared to native crayfish, rusty crayfish are typically larger, grow and reproduce at an accelerated rate, are more effective at evading predators, and dominate in contests for food and shelter. Research on the different mechanisms by which rusty crayfish affect native crayfish may help us anticipate or interpret the impacts of invasions in our region. We investigated how non-native rusty crayfish affect the behavior of northern crayfish (Faxonius virilis), a common resident species in New Hampshire. We quantified the movement of northern crayfish when exposed to either the physical presence of rusty crayfish or their chemical cues at three different water temperatures. Northern crayfish reduced their movement speed in the presence of the chemical cue from rusty crayfish at all three temperatures, and they increased their overall distance moved in the presence of both the visual and chemical cue (compared to the control) at the highest temperature. These results suggest that an important component of the invasion mechanism for rusty crayfish may be altering the behavioral dynamics of native crayfish