Invasive Hydrilla verticillata impacts native aquatic plants at family and species levels

This study examines how the invasion of Hydrilla verticillata affects native submerged macrophytes in the Rosana Reservoir, focusing on its impact at both species and family levels. The research analyzed data on the presence and absence of aquatic macrophytes in both invaded and non-invaded sites before and after the introduction of H. verticillata. Our findings indicate that H. verticillata alters the probability of occurrence of native species through both competitive suppression and facilitation. For the Hydrocharitaceae family and the species Egeria najas, the presence of H. verticillata decreased their probability of occurrence in invaded sites. In contrast, the probability of occurrence of the Characeae family, along with Nitella furcata and Chara guairensis, increased in post-invasion conditions within invaded sites. This suggests that non-native plants can have divergent impacts on native species, with some being negatively affected while others may benefit. These results highlight that invasive species can have divergent effects, influencing species and family-level interactions in aquatic ecosystems. Additionally, the influence of native species richness on the probability of occurrence of different species and families was found to be affected by the presence or absence of H. verticillata. Overall, the research underscores the importance of assessing the impact of non-native species not only at the species level but also in terms of their broader effects on native species families and ecosystems.