Zebra Mussels: Enhancement of Copper Toxicity by High Temperature and Its Relationship with Respiration and Metabolism

Increase in water temperature from an ambient of 15 °C to 20 and 25 °C increased the respiration rate in zebra mussels, Dreissena polymorpha, by 50 and 175%, respectively, and increased the toxicity of copper; a 48‐hour lethal concentration to kill 50% of the organisms (LC50) of 775 μg/L at 20 °C decreased to 238 μg/L at 25 °C, and a 96‐hour LC50 of 487 μg/L at 20 °C reduced to 107 μg/L at 25 °C. The oxygen consumption rate in the presence of 150 μg/L copper decreased by 16% at 20 °C and by 50% at 25 °C. Thus, high temperatures may increase the toxicity of copper, and possibly other metals, to zebra mussels. Similar increases in heavy metal toxicity may also accompany global warming, which is expected to raise surface water temperature by 2 to 3 °C. Such temperature and heavy metal combinations may also be useful in designing field trials to control this nuisance species.