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St. Louis River estuary as possible Dreissena veliger source to western Lake Superior.
Citation:
Barge, J., C. Hatzenbuhler, A. Cotter, J. Hoffman, C. Meredith, G. Peterson, S. Okum, E. Pilgrim, B. Wiechman, AND A. Trebitz. St. Louis River estuary as possible Dreissena veliger source to western Lake Superior. Upper Midwest Invasive Species Virtual Conference, Duluth, MN, November 02 - 06, 2020. https://doi.org/10.23645/epacomptox.13138586
Impact/Purpose:
The early-detection monitoring survey described in this poster was motivated by a request for help from the National Park Service (NPS) in understanding the distribution and potential impacts of Dreissenid (zebra and quagga) mussels in waters surrounding the Apostle Island National Lakeshore. This work was conducted under SSWR research area 3.01A-2.1, and builds on previous EPA/ORD case studies concerning early-detection monitoring strategies. Outcomes from this research will include development of more refined and robust sampling strategies for non-native species in different coastal systems across the Great Lakes, advancement of DNA-based tools for conducting such monitoring, and providing a baseline for future biological assessment in NPS waters.
Description:
Dreissena mussels have been established in the St. Louis River (SLR), the largest tributary to Lake Superior since 1989. Dreissena are readily transported via ballast water and boat hull attachment, so their lack of establishment in Lake Superior was thought due to inhospitable physiochemical conditions. That notion was challenged by recent Dreissena finds in the Apostle Islands (APIS) region located ~100 km east of the SLR. Motivated by concerns surrounding these finds, the U.S. EPA in 2017 conducted an intensive survey of APIS waters (100 sites, DNA & traditional sampling methods) aimed at understanding Dreissena prevalence and distribution. We did not find any settled Dreissena but did find low densities of planktonic veligers at 44% of sites and detected Dreissena DNA in biofilm collected from passive samplers. Since these finds were primarily on the western side of APIS and the SLR is the only substantial Dreissena population in the region, we wondered whether these veligers were spawned within APIS or transported there from the SLR by long-shore currents. We followed up in 2019 with a study designed to assess this possibility by examining changes in veliger detections, densities, and size along the SLR to APIS gradient. This effort consisted of 8 locations where we sampled plankton and eDNA, each collected 3 times 2 weeks apart, and deployed passive samplers for the duration of the survey. All samples were tested for Dreissena DNA using qPCR (zebra and quagga specific marker), while planktonic tows were enumerated. This poster will summarize findings from the 2017 effort and present results from the 2019 effort.
URLs/Downloads:
DOI: St. Louis River estuary as possible Dreissena veliger source to western Lake Superior.