Contrasting Patterns of Pomacea maculata Establishment and Dispersal in an Everglades Wetland Unit and a Central Florida Lake

Abstract

The spread of non-native species raises concerns about native species displacement, while other negative effects on native species (e.g., habitat degradation) should also be considered. The highly invasive non-native apple snail Pomacea maculata has raised such concerns as it has become established in a wide range of aquatic systems worldwide. While monitoring native Florida P. paludosa populations in Lake Tohopekaliga (LTOHO) from 2001 to 2009 and in Water Conservation Area 3A (WCA3A, Everglades) from 2006 to 2015, we opportunistically documented the establishment and distribution of P. maculata. We estimated snail densities and recorded egg cluster presence in three study sites (12 total plots, LTOHO) and 137 sites (WCA3). On LTOHO, native snails were absent or at very low densities prior to finding P. maculata. Few snails of either species were found in high-stem-density vegetation of the littoral zone. Pomacea maculata immigration into the littoral zone occurred following managed vegetation removal, and Hydrilla verticillata proliferation in LTOHO likely contributed to the spread of P. maculata. We found both native and non-native apple snail species in many WCA3A sites following P. maculata invasion. We initially found the non-native snail in two sites in southern WCA3A; they were mostly restricted to within three kilometers of initial sites over the next four years. Overall plant community compositions in LTOHO and WCA3A appeared less impacted than expected based on previous reports of P. maculata invasions.