Pacific Southwest Research Station

Development of a Risk Model to Determine the Expansion and Potential Environmental Impacts of Asian Clams in Lake Tahoe

Full title: Development of a risk model to determine the expansion and potential environmental impacts of Asian clams in Lake Tahoe

Lead Researchers: Sudeep Chandra, University of Nevada at Reno; Marion Wittmann and Geoff Schladow, University of California at Davis

Abstract

In the last 40 years many private and public resources have been expended to restore Lake Tahoe’s fragile ecosystem and water clarity. Recently, the expansion of an invasive species, the Asian clam, was documented in the southeastern part of the lake. Further, this summer there were dense, filamentous algal blooms co-located with Asian clam beds. These blooms occurred in less than 10 meters of water and were detected by local homeowners, residents and lake visitors and reported to local agencies. The rapid expansion of Asian clam in one year combined with the demonstrated potential to alter the ecology of the lake via unprecedented levels of algal biomass in the near shore represents a major new threat to Lake Tahoe. This proposal is motivated by concerns of agency staff requests for assistance in developing control methods, predicting likely future locations for clam colonization, and assessing the impact of clams on both a local and entire-lake scale. The invasion of Asian clam in a high elevation, oligotrophic, coldwater lake is unique; most introduced species in Lake Tahoe show various life history adjustments and/or phenotypic plasticities compared to other populations in North America. The early detection of this common invader in Lake Tahoe allows for critical research at the beginning stages of an invasion in a rare environment. This research will greatly contribute to invasive species research literature as well as to management within the basin. The major objectives of this project proposal are to advance the state of the science for freshwater bivalve invasion, and to develop a longer-term risk assessment of Asian clam growth, spread and impact.