1. Report on USFWS Contracted WRP Research Project Assessment of the Potential for Zebra Mussel Invasion of Waters in the Western United States via Saltatory Dispersal and Evolution of Increased Thermal Tolerance Dr. Robert F. McMahon Professor of Biology and Dean of the Honors College John A. Morse Graduate Research Assistant The University of Texas at Arlington Box 19222 Arlington, Texas 76019 11 September 2007 UT Arlington

2. Research Objectives ●Compare the acute and chronic upper thermal limits of zebra mussel populations from a warm southwestern habitat and cooler northeastern habitat ●Use data to assess development of physiologically resistant (thermally tolerant) races of zebra mussels in isolated southwestern populations ●Comparing genetic fingerprints (Amplified Fragment Length Polymorphisms or AFLP) of isolated zebra mussel populations and comparing them with samples from potential source populations ●Use data to examine how mussel dispersal patterns from one drainage system to another

3. Results Chronic Thermal Tolerance ●Mussel samples collected from Lake Oologah, Oklahoma (2206, 2007), and Saratoga Lake (2006) and Hedges Lake (2007) in New York ●Acclimated in the laboratory for over two weeks to 5°, 10°, 15°, 20°, 25° and 30°C ●Subsamples held concurrently for up to 28 days at temperatures of 28°C, 29°, 30°, 31°, 32°, 33° and 34°C ●Samples checked daily for mortality ●Dead individuals removed

4. 0 10 20 30 40 50 60 70 80 90 100 25°C30°C Acclimation Temperature % Mortality OklahomaNew York Mortality after 28 days at 29°C in zebra mussels acclimated to 25° and 30°C (2006)

5. 28-Day Chronic Thermal Test Results 2007 Numbers above bars represents the time (in days) to achieve 100% mortality 14 166.5264.51935.5211.50.5 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 27°C28°C29°C30°C31°C32°C33°C34°C Test Temp % Mortality NYOK

6. Temperature (°C) 0 5 10 15 20 25 30 35 JulAugSepOctNovDecJanFebMarAprMayJun Month Oologah Lake Water Temperature 2006 2007

7. Mortality after 28 days at 29°C in Lake Oologah zebra mussels acclimated to 20°, 25° and 30°C in 2006 and 2007

8. Lake Mead Quagga Mussel Research

9. Size Distributions of Quagga Mussels in Lake Mead

10. 28 Day Mortality for Lake Mead Quagga Mussels Exposed to 20°C – 33°C Numbers above bars represent the approximate number of days to reach 100% mortality. 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% % Mortality 20d5d2d1/2d1/4 d 20°C21°C22°C23°C24°C25°C26°C27°C28°C29°C30°C31°C32°C33°C Temperature (°C) StarvedFed

11. 35 Lake Mead Temperature Profile at Sentinel Island 0 5 10 15 20 25 30 Temperature (°C) 1/1/2006 2/1/2006 2/26/20063/26/2006 4/23/2006 5/21/2006 6/18/20067/16/20068/13/20069/10/2006 10/8/2006 11/5/200612/3/2006 1/1/20072/1/2007 Date 1m 6m 12m 15m20m30m50m80m

12. Isolated Water Bodies Sampled ISOLATED WATERS Water BodyStateComments Oologah Lake (after Aug. 2006)OKObtained Oologah Lake (before Aug. 2006)OKObtained El DoradoKSObtained White RiverAKCollection planned Ossawinnamakee LakeMNPossible collection Saratoga LakeNYObtained Hedges LakeNYObtained Ballston LakeNYObtained Base LakeNECollection planned Lake of the OzarksMOObtained Diamond LakeMIObtained Detroit RiverMIObtained Wolf LakeILObtained Mosquito Creek ReservoirOHObtained Milbrook QuarryVAObtained Lake Mead*NVObtained NON-ISOLATED WATERS Water BodyStateComments Mohawk RiverNYObtained Lake Michigan**MIObtained Lake Erie**OHObtained Lake Ontario*NYObtained St. Lawrence River*NYCollection planned Upper MississippiCollection planned Lower MississippiLACollection planned

13. Preliminary Conclusions ●Zebra mussels from Lake Oologah, Oklahoma are not more thermally tolerant than those from Saratoga or Hedges Lake in New York ●No evidence for selection of elevated thermal limits ●The incipient (long-term) upper thermal limit of zebra mussels Lake Mead qugga mussels appears to be ≈ 28°C regardless of latitude in North America ●The Lake Oologah, Oklahoma, zebra mussel population experienced near 100% extirpation during August 2006 and 2007 when water temperature rose above 28°C ●No evidence of selection for elevated thermal limits ●Lakes exceeding a surface temperature of 28°C for extended periods in the summer are unlikely to harbor zebra or quagga mussels ●Quagga mussels were first introduced to Lake Mead in 2003 or 2004 ●Temperature profiles can be use to estimate the susceptibility of southwestern water bodies to zebra mussel invasion ●Lake Mead and the Lower Colorado River Lakes are susceptible to quagga and zebra mussel invasion ●Molecular analysis of the origins of isolated zebra mussel introductions will be completed by December 2006