Meeting Abstract
P1.14 Thursday, Jan. 3 Determination of the chronic upper thermal limit for Lake Mead quagga mussels (Dreissena rostriformis bugensis() and the preliminary evaluation of pressurized hot water treatment in controlling the spread of zebra mussels (Dreissena polymorpha) MORSE, J.T.; Univ. of Texas, Arlington jmorse@uta.edu
The invasive quagga mussel, Dreissena rostriformis bugensis, was recently discovered in Lake Mead (AZ/NV). This is the first reported population of dreissenids in the western U.S. which has reawakened questions regarding both their thermal limits and how to control their spread. This work establishes the chronic upper thermal tolerance of Lake Mead quagga mussels. Mussels were acclimated to 20°C for two weeks prior to testing at a range of temperatures (20°C-33°C) maintained for a period of 28 days. The upper thermal critical limit for Lake Mead quagga mussels appears to be near 28°C, with only 6% survivorship after 28 days. Temperatures above 28°C experienced 100% mortality by 28 days while temperatures below 28°C experienced progressively lower mortality. Because dreissenids are transported overland on trailered boats, pressurized hot-water boat washes have been suggested as a means of controlling their spread although the effectiveness of this technique has not been thoroughly evaluated. Thus we determined the effectiveness of hot-water spray in killing adult zebra mussels, Dreissena polymorpha, by spraying groups of mussels with water of 6 different temperatures (20°C, 40°C, 50°C, 60°C, 70°C and 80°C) for either 5 or 10 seconds at a rate of 0.2gpm through a small (1mm2) fan-shaped nozzle. Zebra mussels sprayed for 5 seconds required 80°C water to guarantee 100% mortality while mussels sprayed for 10 seconds required only 60°C water to guarantee complete eradication. These studies characterize the thermal limits of quagga mussels in the western U.S. and provide guidelines to insure the effectiveness of hot water sprays to clean boats.
