Effects of the Intensity of Land-Use Changes on Taxonomic and Functional Diversity of Fish in a Neotropical Floodplain

Human activities impacting freshwater ecosystems, such as land use and cover changes, are recognized as serious threats to freshwater biodiversity, with fish communities being severely impacted. However, the implications of land-use changes on taxonomic and functional diversity for many communities and ecosystems, notably floodplains, remain poorly understood. We explored the relationship between land-use changes and the taxonomic and functional diversity, using fish assemblages of the upper Paraná River floodplain as a study model, over a 20-years period (2000–2019). We predicted that human influence, such as the anthropogenic area and the intensity of landscape change, would harm fish community. Using data from surveys from two subsystems, we applied a generalized and linear mixed model to explain the effects of land-use variation (area and intensity of gain and loss of anthropogenic category) on taxonomic and functional diversity of fish species. Our results showed that the rapid and intense changes of anthropogenic areas led to decreases in taxonomic and functional metrics of the fish community. These findings are particularly relevant since it is considered that the functions supplied by a community are strongly dependent on the wide range of functional traits, and their loss might anticipate the loss of ecosystem services. Furthermore, our study shows the need of taking into account not just the simple composition of land use and cover when considering human influences, but also the intensity of landscape changes through time, reinforcing the need to pay special attention to these environments.