Influence of spatial and environmental factors on the structure of a zooplankton metacommunity in an intermittent river

Hydrological disconnection in intermittent rivers is known to increase β-diversity by limiting the dispersal of species and decreasing environmental similarity between sites. Knowledge of the mechanisms driving variation within and between local communities helps elucidate the role of environmental and spatial processes responsible for community composition at multiple scales in intermittent rivers. In this study, we investigated the spatial and environmental patterns of zooplankton β-diversity in an intermittent river in a semiarid region in Brazil. We hypothesized that (1) the zooplankton metacommunity is determined primarily by turnover, and (2) the structure of the zooplankton metacommunity is more heavily influenced by environmental than spatial factors. Our samples yielded 46 taxa of rotifers and cladocerans. β-taxonomic diversity was high, with a predominance of turnover compared with nestedness. The partitioning analysis showed that environmental and spatial processes had a significant influence on the distribution of zooplankton species, but the former had the greatest explanatory power. In the redundancy analysis, high values of temperature, oxygen and submersed macrophytes were significantly correlated with species variation. The observed β-diversity values closely reflected the turnover pattern, whereas Cladocera and Rotifera diverged between predictive processes. Our results highlight the importance of adopting appropriate conservation measures for intermittent river networks as a whole.