Correlates of fish and aquatic macrophyte beta diversity in the upper Paraná river floodplain

Abstract

We investigated correlates of long-term temporal variation in the beta diversity of macrophytes, sedentary fish, and migratory fish communities in the Upper Paraná River floodplain. Two metrics of among-site variation in community composition were calculated in up to 45 sampling periods over 12 years for each biological group. We then tested the following beta diversity correlates: richness and proportion of non-native species, ecosystem productivity proxies, environmental heterogeneity, and hydrological regime proxies. Despite the uncertainty regarding the best model, we found that environmental heterogeneity was the most consistent predictor of beta diversity variation. Non-native species (richness or proportional abundance), productivity, and hydrology were not consistently correlated with beta diversity. However, models results suggest that the likely intensification of threats caused by oligotrophication, non-native species spread, and damming may trigger the effects of these predictors. Thus, we suggest that continuation of the long-term ecological study in the Upper Paraná River floodplain is key to our better understanding of the role of these processes in beta diversity variation.