Assessing the effects of application time and temperature on the efficacy of hot-water sprays to mitigate fouling by Dreissena polymorpha (zebra mussels Pallas)

Abstract

Dreissenid mussel (Dreissena polymorpha, Dreissena rostriformis bugensis) expansion into the Western US has renewed interest in hot-water spray mitigation of mussel fouling on boat hulls, trailers, and other equipment. However, the efficacy of hot-water sprays to mitigate dreissenid fouling has not been experimentally assessed. Emersed, adult D. polymorpha were exposed to low-pressure, hot-water sprays at 40, 50, 60, 70, and 80°C for 1, 5, or 10 s. Sprays at ≥60°C for 10 s or 80°C at ≥5 s were 100% lethal. In contrast, 1–10 s exposures did not induce 100% mortality at ≤50°C. The results indicate that mitigation of D. polymorpha fouling, especially in areas protected from the hydraulic impacts of high-pressure sprays requires spray temperatures of > 80°C applied for >5 s or no less than 60°C applied for >10 s. Thus, presently recommended spray temperatures of ≥60°C may not be 100% effective unless applied for >10 s.

Keywords:

• Dreissena polymorpha
• zebra mussel
• thermal treatment
• hot-water spray
• trailered boat
• acute thermal tolerance

Acknowledgements

Dr Daniel P. Molloy of the New York State Museum kindly collected specimens of zebra mussels from Hedges Lake and arranged for their overnight shipment to the laboratory at The University of Texas at Arlington. Dr Robert F. McMahon of The University of Texas at Arlington and Dr David K. Britton of the US Fish and Wildlife Service reviewed and made valuable suggestions for improvement of a prior draft of the manuscript.