Chemosensory behavior and temperature preferences of northern crayfish (Faxonius virilis) and rusty crayfish (Faxonius rusticus)
Invasive crayfish can alter aspects of the behavior of native crayfish with consequences that are yet to be fully understood. Crayfish respond to water temperature and chemosensory cues as they navigate, forage, find mates, and encounter predators. Given the disruptive effects invasive species can directly have on native species, it is important to also establish how cues from non-native species may affect the sensory landscape and alter behavior of native species even in the absence of physical contact. We collected a resident species in New Hampshire, the northern crayfish (Faxonius virilis), and quantified the effects of cues (alarm substances and physical presence) from the non-native rusty crayfish (Faxonius rusticus) on its activity. We also quantified the temperature preferences of both species and tested for any interactive effects of temperature and rusty crayfish cues on the behavior of northern crayfish. We found that these two species differed in their temperature preference, with northern crayfish preferring a warmer temperature than the rusty crayfish. The alarm cue from rusty crayfish altered the behavior of northern crayfish, inducing them to move more slowly. We also found that temperature affected how northern crayfish reacted to rusty crayfish cues in terms of movement distance. Our findings suggest that chemosensory cues from non-native crayfish may have an effect on resident species during an invasion process. Future investigation into population- and region- specific chemosensory-induced behavioral changes in native crayfish species is warranted.