Rocky Terrain: The Impacts of Substrate Type on Crayfish Escape Velocity and Physiological Fitness

Crayfish are keystone species and ecological indicators of health in freshwater ecosystems. The invasive red swamp crayfish (Procambarus clarkii) is a habitat generalist species that can thrive in diverse environments, which has contributed to its rapid spread and competitive advantage to native crayfish. While there is multiple documentation of the ecological effects of these invasive species, not much is known on how specific habitat features influence their fitness, or their ability to perform work in their environment (whether through predatory/prey interaction, reproductive success, or resource procurement). In this study, we investigate whether different ground substrates (control, sandy, rocky, and mixed) affect the crayfish’s fitness as determined by the velocity of their tail flip response. Individual crayfish were tested in three separate trials by inducing a tail flip response using a light tactile stimulation and recorded with a high-speed camera. Velocity(body length per second) was calculated using video analysis software (Veriner Co) . Preliminary results indicate that these crayfish exhibit higher escape velocities on gravel compared to control and sand substrates. Trials conducted on sand and mixed substrates exhibited reduced visible speed in their escape performance, thus suggesting substrate dependent limitations. These findings partially contrast to our expectations that a habitat generalist would perform similarly across all environments. The results suggest that maybe even habitat generalists may experience behavioral constraints according to habitat structure. Understanding how substrate types influence escape performance could elucidate how different environments affect the crayfish’s ability to escape predators, which led to their survival and invasive success.