Neotropical invaders: a review of the most impactful non-native aquatic macrophytes

Abstract

Abstract: Aim Many macrophyte species have become invasive and cause severe ecological and economic impacts on aquatic ecosystems. In this review, we synthesize the main determinants of invasion by the principal macrophyte species in the Neotropics that originated from other continents, as well as their ecological impacts on these ecosystems. Methods We conducted a systematic review using the Web of Science and Scopus databases. Results The three most frequently studied non-native species introduced from other continents in Neotropical ecosystems were Hydrilla verticillata (hydrilla), Urochloa arrecta (African signalgrass), and Hedychium coronarium (white ginger). The success of these species is explained by a combination of traits that facilitate dispersal and colonization, together with rapid growth rates and tolerance to a wide range of abiotic conditions. Environmental factors such as drought, nutrient availability, and shading are important determinants of their success, although their influence varies among species. Biotic resistance provided by native species was identified as an important factor that reduces the ecosystem invasibility by all three species. We found evidence of impacts on native macrophyte populations and communities, as well as on invertebrates, fish, and birds. All three species caused changes in community composition, while reductions in native species diversity were most pronounced for African signalgrass and white ginger. African signalgrass accumulates extremely high biomass, eliminating native macrophytes and fish and altering ecosystem properties. For these reasons, it can be considered the most impactful of the three species. Conclusions All three species cause significant impacts on Neotropical ecosystems, and efforts to prevent their spread and establishment should be prioritized. Management practices that include preventing dispersal, maintaining ecosystem integrity and native biodiversity, and implementing direct control at small spatial scales may help achieve effective control of these invasive species.