Current Velocity, Temperature, and Stress: Factors affecting movement and prevalence of White Spot Syndrome virus in Procambarus clarkii (Red Swamp Crayfish)

Abstract

Red swamp crayfish (Procambarus clarkii) have invaded ecosystems worldwide and are potential carriers of white spot syndrome virus (WSSV). We monitored the prevalence of WSSV under a natural thermal regime in wild populations of P. clarkii and tested whether stress associated with laboratory studies could trigger WSSV virulence. Proportion of WSSV in wild populations peaked at 22.3℃ but prevalence could remain low even at optimal temperatures. Stress associated with internal insertion of PIT Tags did not trigger increased WSSV count or virulence in laboratory animals. We then used PIT-tagged animals to investigate the relationship between current velocity and rheotaxis in P. clarkii. We found weak evidence for positive rheotaxis at low current velocities and strong evidence for negative rheotaxis at higher velocities. Results suggest that high current velocities may limit the spread of invasive P. clarkii in lotic systems and may be useful to increase trapping efficiency in invaded systems.