Effects of carbon dioxide on juveniles of the freshwater mussel (Lampsilis siliquoidea [Unionidae])

Diane L. Waller, Michelle R. Bartsch, Kim T. Fredricks, Lynn A. Bartsch, Susan M. Schleis, Sheldon H. Lee

Carbon dioxide 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. We evaluated lethal and sublethal responses of juvenile Fatmucket (Lampsilis siliquoidea) mussels to carbon dioxide at levels (43-269 mg/L, mean concentration) that bracket concentrations effective for deterring carp movement. The 28-d LC50 value (lethal concentration to 50% of the mussels) was 87.0 mg/L (95% confidence interval, CI 78.4-95.9) and at 16-d post-exposure was 76.0 mg/L (95% CI 62.9-90.3). A proportional hazards regression model predicted that juveniles could not survive CO2 concentrations >160 mg/L for more than 2 wk or >100 mg/L CO2 for more than 30 d. Mean shell growth was significantly lower for mussels that survived carbon dioxide treatments. Growth during the post-exposure period did not differ among treatments, indicating recovery of the mussels. Carbon dioxide also caused shell pitting and erosion. Behavioral effects of carbon dioxide included movement of mussels to the substrate surface and narcotization in the highest concentrations. Mussels in the 110 mg/L, mean CO2 treatment had the most movements in the first 3 d of exposure. If carbon dioxide is infused continuously as a fish deterrent, concentrations below 76 mg/L are recommended to prevent juvenile mussel mortality and shell damage. Mussels may survive and recover from brief exposure to higher concentrations. This article is protected by copyright. All rights reserved.