Meeting Abstract
Invasive crayfish can have a competitive advantage over native crayfish due to increased activity (defined as time spent outside of cover) in invaded environments, allowing for the acquisition of greater resources. We conducted an ex situ study to determine if total exposure time (a proxy for activity and defined as time spent outside of shelter regardless of behavior) and behavior (i.e., walking; immobile) differed between native spiny-cheek crayfish (Orconectes limosus) and invasive rusty crayfish (Orconectes rusticus) from the Susquehanna River drainage in Pennsylvania. We conducted the study in raceways modified to simulate a typical stream within the Susquehanna River drainage, inclusive of a native, nocturnal predator, the eastern hellbender (Cryptobranchus alleganiensis alleganiensis). We recorded video in each raceway and collected data from the video including total exposure time and duration of walking and immobile crayfish behaviors. There were no significant nocturnal differences between crayfish species in total exposure time (w=13668, df=338, p=0.44), walking behavior (t=0.4478, df=160, p=0.65), or immobile behavior (t=-1.5687, df=176, p=0.11), suggesting both species behave similarly at night. Diurnally, rusty crayfish had significantly greater total exposure time (w=235.5, df=70, p<0.01) and spent significantly more time walking (t=-4.4424, df=30, p<0.01) and immobile (t=-4.350, df=37, p<0.01) than spiny-cheek crayfish. This suggests invasive rusty crayfish may have an indirect competitive advantage over native spiny-cheek crayfish due to differences in diurnal behavior.
