Data Release: Temperature-related responses of invasive (Dreissena polymorpha) and native mussels (Order: Unionida) to elevated carbon dioxide

Control technology for dreissenid mussels (Dreissena polymorpha and D. bugensis) currently relies heavily on chemical molluscicides that can be both costly and ecologically harmful. There is a need to develop more environmentally neutral control tools to manage dreissenid mussels, particularly in cooler water. Previously, carbon dioxide (CO2) showed selective toxicity for Zebra mussels, relative to unionids, when applied in cool water (12 °C). Carp-Carbon Dioxide (carbon dioxide, CO2) is registered as a pesticide by the U.S. Environmental Protection Agency (EPA) for deterrence of Asian carp and to control aquatic nuisance species when applied under ice (USEPA 2019). The current registration would allow the use of CO2 to kill Zebra mussels in water bodies during periods of ice cover, but first efficacious treatment regimes in cold water need to be determined. We compared toxicity endpoints (lethal concentrations, time to lethality) and behavioral responses of Zebra mussels (gaping, attachment) and juveniles (burial) of two unionid species (Plain pocketbook, Lampsilis cardium) and Fragile papershell (Leptodea fragilis) to CO2 across a temperature range to determine treatment scenarios that had the greatest efficacy to invasive mussels and safety margin to native mussels. We found CO2 treatment regimens at all three temperatures that were efficacious to Zebra mussels and caused minimal mortality of unionid. At 5 °C, Plain pocketbook survived 96 h exposure to the highest PCO2 treatment (139 atm). At 20 °C, the 96 h LC10 for Plain pocketbook (173 atm PCO2, 95% confidence interval CL 147 – 198 atm) was significantly higher than the LC99 for Zebra mussels (118 atm PCO2, CL 109 – 127 atm). Lethal time to 99% mortality (LT99) of Zebra mussels in PCO2 ~ 110 – 120 atm ranged from 100 h at 20 °C to 300 h at 5 °C. Mean survival of unionids exceeded 85% in LT99 CO2 treatments at all temperatures. Seasonal behaviors of native mussels are also considered to assess the potential risk of a CO2 treatment to unionids. Short-term infusion of 100 to 200 atm PCO2 at a range of water temperatures could reduce biofouling by Zebra mussels.