Effects of Catchment Land Use on Stream Fish Assemblages in the Brazilian Savanna
Paulo S. Pompeu, Cecília G. Leal, Débora R. Carvalho, Nara T. Junqueira, Miriam A. Castro, and Robert M. Hughes
Abstract.—The Brazilian savanna (Cerrado) is a biome of global importance with great endemism and environmental heterogeneity, but it is highly threatened and overexploited. Such a set of conditions is a key aspect of freshwater biodiversity and a challenge to our understanding of species-rich regions. Therefore, we investigated the fish diversity patterns and the effects of different land uses on fish assemblage structure in 155 Cerrado stream sites in four hydrological units. We assessed catchment land use and cover upstream of each sample site, where fish were sampled once during the dry season. Stream fish diversity patterns and the effects of different land uses on assemblage structure differed among the four hydrologic units, and in the region as a whole, but high values of beta diversity due to species turnover were consistently observed. We observed low explanation of land use in relation to fish assemblage structure, probably because of the high level of species turnover and large number of rare species. For some units, the most-correlated land uses were anthropogenic, and alien species were positively related to anthropogenic impacts. Our analysis highlights the importance of the heterogeneous composition of the fish fauna in Brazilian savanna streams and the significance of shifting towards protecting or properly managing whole basins and drainage networks.