Effects of carbon dioxide on juveniles of the freshwater mussel ( Lampsilis siliquoidea [Unionidae])
Carbon dioxide (CO 2 ) has shown promise as a tool to control movements of invasive Asian carp, but its effects on native freshwater biota have not been well studied. The authors evaluated lethal and sublethal responses of juvenile fatmucket ( Lampsilis siliquoidea ) mussels to CO 2 at levels (43–269 mg/L, mean concentration) that bracket concentrations effective for deterring carp movement. The 28-d lethal concentration to 50% of the mussels was 87.0 mg/L (95% confidence interval [CI] 78.4–95.9) and at 16-d postexposure, 76.0 mg/L (95% CI 62.9–90.3). A proportional hazards regression model predicted that juveniles could not survive CO 2 concentrations >160 mg/L for more than 2 wk or >100 mg/L CO 2 for more than 30 d. Mean shell growth was significantly lower for mussels that survived CO 2 treatments. Growth during the postexposure period did not differ among treatments, indicating recovery of the mussels. Also, CO 2 caused shell pitting and erosion. Behavioral effects of CO 2 included movement of mussels to the substrate surface and narcotization at the highest concentrations. Mussels in the 110 mg/L mean CO 2 treatment had the most movements in the first 3 d of exposure. If CO 2 is infused continuously as a fish deterrent, concentrations <76 mg/L are recommended to prevent juvenile mussel mortality and shell damage. Mussels may survive and recover from brief exposure to higher concentrations.