Title: Science to assist policy decisions regarding the prevention of invasive species: testing the survival and growth of quagga mussel in Lake Tahoe Subtheme 2a: Understanding the impacts of aquatic invasive species Principal Investigator and Dr. Sudeep Chandra Receiving Institution Department of Natural Resources and Environmental Science University of Nevada- Reno,1000 Valley Road/ MS 186 Reno, Nevada 89512 Phone: 775-784-6221;FAX: 775-784-4530, [email protected] Co-Principal Investigator <add Dr. Kumud Acharya more rows as needed> Division of Hydrologic Science, Desert Research Institute 755 E. Flamingo Rd. Las Vegas, NV 89119 Phone: 702-862 5371;Fax: 702-862 5427, [email protected] Agency Collaborator < include Ted Thayer Tahoe Regional Planning Agency, PO Box 5310, Stateline, any agency personnel who will NV 89449 Phone number: (775) 588-5301 Fax: (775) 588-4527 be directly involved in the [email protected] Steve Chilton US Fish and Wildlife Service, Nevada project, if applicable, and add Fish and Wildlife Office P.O. Box 5310 Stateline, NV 89449 Phone more rows as needed> number: (775) 589-5265; Fax: (775) 588-4527 [email protected] Kim Boyd and Dave Roberts Tahoe Resource Conservation District, 870 Emerald Bay Road South Lake Tahoe, California 96150 Phone: (530) 543 -1501; Fax: (530) 543-1660, [email protected] Grants Contact Person Shelley Chase University of Nevada- Reno Office of Sponsored Projects/MS 325 Reno, NV 89557 Phone: 775-784-4040 Fax: 775-784-6680 Email: [email protected] Funding requested: $ 413,377.26 Total cost share (value of $ financial and in-kind contributions): Title Page (1 page maximum) II. Proposal Narrative (up to 7 pages, single-spaced, 10 point font minimum) a. Project abstract (1 paragraph summary for public distribution) Quagga and zebra mussels are establishing in western waterways with large densities in the Colorado Aqueduct system and established populations in North Central California. This invasion is already having profound ecological and economic impacts in these ecosystems. There is a debate amongst scientists and managers on whether the current models that predict the distribution of Dreissenid mussels are accurate. Recently for example veligers have been detected in Colorado lakes some of which have low calcium levels. Furthermore, a study in Lake George (NY) suggests that adult mussels are able to grow under low calcium conditions however the veliger recruitment determined from settlement bioassays is likely limiting. Thus, what will determine a source versus sink population may not be entirely clear and deserves some attention for Western waters. A previous study using Lake Tahoe water suggests by the PI suggests that adult quagga mussel fed low calcium, low algal biomass water may survive for greater than 50 days. Reproductive analysis showed that there was some evidence of gamete development in these mussels, but findings were inconclusive as to whether mussel populations can maintain themselves in Lake Tahoe conditions. Survival from the veliger stage to adult stage is key in the establishment of dreissenid mussels in any water body—this indicates the ability for species establishment after introduction. Current knowledge suggests that Lake Tahoe can support adult mussels for s short period of time however, whether juveniles, and thus a reproducing population can sustain is currently unknown. The proposed research will directly assess the habitat suitability of Lake Tahoe and its watershed to support the establishment of quagga mussel by testing the survivability of veliger to sub-adult stage using Lake Tahoe water. This information will be important for supporting the current efforts related to inspection and washing of boats entering Lake Tahoe. b. Justification statement: explain the relationship between the proposal and the subtheme(s) Quagga and zebra mussels are establishing in western waterways (CA, NZ, AZ, UT, CO) with great densities in the Colorado Aqueduct system, and Lake Mead, NV-AZ in particular. This invasion is already having profound ecological and economic impacts--dam operators have spent millions removing mussels from penstocks (BOR 2009) and quagga mussel clearly dominates benthic invertebrate communities (Wittmann, Chandra et al. 2009). When quagga mussel establish, they can dominate and alter the ecology of lakes, impacting all trophic levels. In Lake Huron, salmon, alewife, zoo- and phytoplankton populations have declined after the establishment of quagga mussels, causing an energy shift from pelagic to benthic zones. This impact has resulted in a $19 million yr-1 decrease in revenue for sport fisheries in Lake Huron (Michigan DNR 2008). In Green Bay, Lake Michigan, dreissenids may be increasing phytoplankton biomass and cyanobacteria concentrations due to selective feeding (DeStasio et al. 2008). Dreissenid mussel invasions have the potential to cause possible biomass shifts from pelagic to benthic communities and may have impacts on lake fisheries and water quality (Umek et al. 2009). If quagga mussel were to establish in Lake Tahoe, it is likely they could have similar impacts on this ecosystem. Similar to Mead, Tahoe is an oligotrophic lake with low food availability. Unlike Lake Mead, Tahoe’s calcium levels are low and place Lake Tahoe in the low risk category for establishment based on published establishment models for dreissenids (Whittier et al. 2008, Cohen and Weinstein 2001). Recent detections of quagga veligers in low calcium reservoirs in Colorado (Table 1) challenges these previously held notions of minimum thresholds for mussel survivability and once again raise the question of whether detections in low calcium waters are source or sink populations. Previous studies in 2008-09 carried out by the University of Nevada- Reno and University of California- Davis showed that adult quagga mussel collected in Lake Mead and maintained in a laboratory setting with low calcium, low chlorophyll Lake Tahoe water can survive for greater than 50 days (Chandra et al. 2009). Reproductive analysis showed that there was some evidence of gamete development in these mussels, but findings were inconclusive as to whether mussel populations can maintain themselves in Lake Tahoe conditions. Survival from the veliger stage to adult stage is key in the establishment of dreissenid mussels in any water body—this indicates the ability for species establishment after introduction. Current knowledge suggests that Lake Tahoe can support adult mussels, whether juveniles, and thus a reproducing population can sustain is currently unknown. The proposed research will directly assess the habitat suitability of Lake Tahoe and its watershed to support the establishment of quagga mussel by testing the impacts Lake Tahoe conditions on the survivability of veligers to sub-adult stage. c. Concise background and problem statement The introduction of non-native species is a leading threat to biodiversity and function of freshwater ecosystems (Sala et al. 2000). A major introduction pathway for aquatic invasive species to North America has been ship ballast water releases into the Laurentian Great Lakes and coastal waters. Once established, species can extend their range through natural waterways via passive or active transport. The long distance spread of these species far beyond neighboring watersheds increases over time predominantly due to human recreational activity (e.g. boating, fishing) (Johnstone et al. 1985, Padilla et al. 1996, Johnson et al. 2001, Leung et al. 2006). Invasive dreissenid zebra (Dreissena polymorpha) and quagga (Dreissena rostriformis bugensis) mussels (zebra and quagga) in particular have altered the ecology of lakes and rivers by coupling pelagic and benthic trophic pathways, increasing offshore clarity, stimulating benthic production and altering biodiversity (Makarewicz et al. 1999, Bially and MacIssac 2000, Ricciardi et al. 1998). In recent years there has been a western range expansion in North America for a number of aquatic invasive species such as New Zealand mudsnail (Potamopyrgus antipodarum), dreissenid mussel species, and crayfish (Procambarus clarki). This spread has been of increasing concern to aquatic ecosystem managers in the western U.S. due to the high level of endemism in their waters (Sada and Vinyard 2002) as well as high costs often associated with the prevention, monitoring and control of introduced species. The Southern Nevada Water Authority for example has spent approximately $32 million (until 2009) to manage quagga biomass impacts on the water intake infrastructure of Lake Mead, a recently invaded reservoir in the western U.S. (Peggy Roefer, Southern Nevada Water Authority, pers. communication). While it is clear that many of these species can be viably transported to water bodies, the physiochemical characteristics of these water bodies that are necessary for successful invasive establishment are poorly understood. Dreissenid mussels have already invaded the mid-western and eastern regions of North America, with zebra mussels (Dreissena polymorpha) discovered in the Great Lakes region of North America in the mid-1980’s (Hebert et al. 1989) and quagga mussels found there in 1992 (May and Marsden 1992, Mills et al. 1993). The quagga mussel first appeared in western U.S. in Lake Mead, AZ-NV in early 2007 (Stokstad et al. 2007) and has subsequently been found in other major western impoundments including Lakes Powell and Mohave. These recent invasions have spurred efforts to determine invasion risk posed by