Impacts of aqueous extracts of tree leaves on the aquatic snail Potamopyrgus antipodarum: exploring the roles of leaf habit and geographic origin

Abstract

The introduction of exotic tree species with dissimilar leaf habits or distinctive chemical composition into native communities may cause impacts on aquatic organisms, yet the relative influence of leaf habit and geographic origin on those impacts remain poorly understood. In this study, we experimentally explored the ecotoxicological effects of aqueous leaf litter extracts from 15 tree species differing in leaf habit (deciduous vs evergreen) and geographic origin (exotics vs natives in Spain) on the mortality and behavior of the aquatic snail Potamopyrgus antipodarum (Gray, 1843). Snails were exposed for 7 days to three leaf extract concentrations of each tree species. No mortality effects were observed at any concentration. In contrast, the behavioral responses of snails were negatively affected at the highest concentration, showing increased reaction time and reduced speed. These responses were species-specific and associated with leaf habit and chemical composition of extracts rather than geographic origin. Leaf extracts from deciduous trees caused a greater slowing down of snails than extracts from evergreen trees. Overall, our results indicate that leaf litter impacts on Potamopyrgus antiporadrum depend more on tree species identity and leaf habit than on native or exotic status, highlighting the importance of leaf traits when assessing ecotoxicological risks in freshwater ecosystems.