Carbon Dioxide Toxicity to Zebra Mussels (Dreissena polymorpha) is Dependent on Water Chemistry

Carbon dioxide (CO₂) is gaining interest as a tool to combat aquatic invasive species, including zebra mussels (Dreissena polymorpha). However, the effects of water chemistry on CO₂ efficacy are not well described. We conducted five trials in which we exposed adult zebra mussels to a range of CO₂ in water with adjusted total hardness and specific conductance. We compared dose-responses and found differences in lethal concentration to 50% of organisms (LC50) estimates ranging from 108.3 to 179.3 mg/L CO₂ and lethal concentration to 90% of organisms (LC90) estimates ranging from 163.7 to 216.6 mg/L CO₂. We modeled LC50 and LC90 estimates with measured water chemistry variables from the trials. We found sodium (Na⁺) concentration to have the strongest correlation to changes in the LC50 and specific conductance to have the strongest correlation to changes in the LC90. Our results identify water chemistry as an important factor in considering efficacious CO₂ concentrations for zebra mussel control. Additional research into the physiological responses of zebra mussels exposed to CO₂ may be warranted to further explain mode of action and reported selectivity. Further study could likely develop a robust and relevant model to refine CO₂ applications for a wider range of water chemistries. Environ Toxicol Chem 2024;43:1312-1319. Published 2024. This article is a U.S. Government work and is in the public domain in the USA. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.