Spatial distribution of two invasive freshwater snails and environmental correlates of the mollusc community abundance, a case study in Chile

Invasive species can produce negative effects on native species. We studied the densities of Physa acuta and Potamopyrgus antipodarum, two invasive freshwater snails in Chile, and analyzed the relationship between environmental parameters and the relative abundances of the mollusc community in several ecosystems. Densities of both species were studied in three habitat types (stones, smooth sediment, and vegetation) in the Consuelo Stream, Coquimbo Region. Densities of Potamopyrgus antipodarum were significantly higher on stones, while Physa acuta showed no significant differences between habitats. A canonical correspondence analysis (CCA) demonstrated that both Physa acuta and Potamopyrgus antipodarum were related to oxidation-reduction potential but not to salinity. The results also showed that native mollusc fauna is sparsely represented in the study area, possibly due to the presence of these invaders, although drought, water pollution, and other unstudied anthropogenic factors may also be involved.