| Quagga and zebra mussels (Dreissena rostriformis bugensis and Dreissena polymorpha) are two invasive species introduced via ballast water discharged by large oceanic cargo ships to the North American Great Lakes in the late 1980s. Once established, the mussels spread quickly. In January 2007, D. rostriformis bugensis was discovered in Lake Mead, NV-AZ, and in that same year, mussels were confirmed further south on the Colorado River in Lakes Mojave and Havasu. Dreissenids clog water intake pipes, water filtration systems, and electric generating plants. The mussels also ruin boat motors, damage recreational equipment, and once established in the reservoir, routine maintenance is necessary to avoid further damage. Prevention is the most cost effective and environmentally protective tool against the further spread of dreissenids. Preventive measures include decontaminating vessels and gear that could transport the mussels, thus restricting the transport and subsequent release of these potentially harmful species. Decontaminating methods examined in this dissertation include high pressure, hot-water sprays and chemical applications. The aim of this research is to evaluate three techniques for preventing the further spread of dreissenids: 1) high pressure water sprays to remove dreissenids from watercraft, 2) hot-water spray to kill D. polymorpha, and 3) use of quaternary ammonium compounds, Quat(TM) 128 and Quat(TM) 256 for decontaminating wildland firefighting equipment. Using 3000 psi of water to remove dreissenids from watercraft is accomplished at a faster rate when the vessel has been out of the water for at least one week in the summer and two weeks in the winter compared to being fresh out of the water (week 0). D. polymorpha were exposed to hot-water sprays at 20, 40, 50, 54, 60, 70, and 80°C for 1, 2, 5, 10, 20, 40, 80, and 160 s. Sprays at 54°C for 10 s were shown to be 100% lethal. The effectiveness of Quat(TM) 128 and Quat(TM) 256 on killing adult dreissenids was examined over time at four concentrations: 0, 1%, 3%, and 5%. The results of the study show that all treatment groups of Quat(TM) 256 are 100% lethal to adult dreissenids within 36 h. Dreissenid veligers were also examined over time at different concentrations of Quat(TM) 128 and Quat(TM) 256: 0.25%, 0.5%, and 0.75%; 0.1%, 0.25%, and 0.5%, respectively, at different water temperatures: 2, 16, and 30°C, and at different ambient temperatures: 2, 15, 30, and 43°C. Given all the factors of chemical toxicity, water temperature, and ambient temperature, 40 min exposure time to 0.25% Quat(TM) 128 or 0.1% Quat(TM) 256 induced 100% mortality in dreissenid veligers. This project will provide baseline data that will be used to draft standard and effective decontamination protocols for watercraft and wildland firefighting equipment exposed to dreissenids throughout the country and in particular in the western U.S. |
