0Spatial and temporal relationships between the invasive snail Bithynia tentaculata and submersed aquatic vegetation in Pool 8 of the Upper Mississippi River

Abstract

Bithynia tentaculata is an invasive snail that was first reported in Lake Michigan in 1871 and has since been rapidly spreading through the waters of the U.S. This invasion has been extremely problematic in the Upper Mississippi River, specifically Navigation Pools 7 and 8, as this area serves as part of the major migratory flyway. As an intermediate host for several exotic trematode parasites, B. tentaculata is associated with severe regional waterfowl mortality. This study was designed to assess the abundance and distribution of B. tentaculata relative to submersed aquatic vegetation (SAV) as it provides nesting and food resources for migrating waterfowl. Temporal changes at specific locations were assessed from 2007 to 2015 using the rake score method of the Long-Term Resource Monitoring Program to survey vegetation and snail densities. Data suggest that B. tentaculata densities have nearly quadrupled since 2007 despite minor changes in vegetation abundance, distribution, and composition. Understanding the spatial distribution of B. tentaculata in relation to other habitat features, including submersed vegetation, and quantifying any further changes in the abundance and distribution of B. tentaculata over time will be important for understanding the potential locations and magnitude of risks of disease transmission to waterfowl.