Relative importance of local and landscape variables on fish assemblages in streams of Brazilian savanna

Understanding variability in the composition of aquatic assemblages requires a multiscale perspective, since processes operating at different spatial scales (from regional to local) drive the community assembly. Here, the relative importance of environmental variables on fish species composition in streams of the Brazilian savanna (Cerrado) is assessed and quantified at local and landscape scales. The importance of both local and landscape environmental variables in structuring fish assemblages was supported. Local variables explained a substantially higher amount of variance of fish assemblages than landscape variables. However, the shared explanation indicate that landscape variables had a complementary effect. The streams sampled were mostly headwaters at similar altitudes and with similar watershed sizes, so the sensitivity of the fish assemblages, even to small landscape gradients, is highlighted. Maintaining these important instream habitat characteristics close to natural conditions seems to be essential for conserving stream fish species, and for this, the landscape context should be taken into account. Considering the near-pristine condition of the streams studied, these findings can be used as a reference for further studies addressing the effects of human modifications on stream fish biodiversity of the Cerrado.