Laboratory trials to evaluate carbon dioxide as a potential behavioral control method for invasive red swamp (Procambarus clarkii) and rusty crayfish (Faxonius rusticus).
Few effective strategies are available to control invasive crayfishes. Carbon dioxide (CO2) acts as a behavioral deterrent for invasive fishes and could be a useful crayfish control tool. The objective of this laboratory study was to quantify CO2 concentrations that caused red swamp crayfish (RSC; Procambarus clarkii) and rusty crayfish (RYC; Faxonius rusticus) avoidance behavior, altered emergence behavior, and caused loss of equilibrium. Behavioral endpoints were quantified under light and dark conditions and at 10 and 24 °C. Avoidance responses from both species varied widely. Under light conditions, 35 mg/L CO2 was needed to induce the first avoidance shuttle in both crayfish species at 10 °C. CO2 concentrations of 42 mg/L for RYC and 46 mg/L for RSC were required for first shuttle at 24 °C. The first avoidance shuttle was induced at 37 mg/L CO2 for RYC and 54 mg/L CO2 for RSC at 10 °C in the dark. At 24 °C, 44 mg/L CO2 was required for first shuttle for both species. Less CO2 was needed to cause the last avoidance shuttle in RYC compared to RSC at both temperatures and under both lighting conditions. RSC emergence occurred at 418 ± 77 mg/L CO2, and loss of equilibrium occurred for both species at 1,231 ± 201 mg/L CO2. RYC appeared to be more sensitive than RSC to CO2, but behavior did not differ among light and water temperature treatments. These results demonstrate that CO2 alters crayfish behavior. The CO2 concentrations identified during this study may inform field testing to develop CO2 as a potential control tool for invasive crayfishes.