A ictiofauna do interflúvio Purus-Madeira e os fatores estruturantes em múltiplas escalas

Abstract

The goal of this study was to increase our knowledge about the stream-fish fauna of PurusMadeira Interfluve and evaluate the main ecological gradients that act in the assemblages structuring, incorporating both spatial and temporal scales. In the first chapter we present a checklist of streamfish of Purus-Madeira Interfluve, built up from new expeditions to difficult-to-access drainages and also by incorporating the previously listed records for the region. The final list consisted of 184 species, of which 43 were only collected in our samples and five genera represent new records for the Madeira River basin. The number of species recorded is higher than those usually found in other stream studies in the Amazon and suggests that this region harbor a biodiversity whose structuring factors still need to be better understood. In the second chapter we seek to understand how the taxonomic and functional diversity patterns of stream fish assemblages are influenced by local and landscape variables. Our results indicate that, at large spatial scales, distance to large rivers is more important than distance among sites and local conditions in explaining functional and taxonomic diversity of fish assemblages and more isolated streams tend to have fewer species and less functional diversity. In the third chapter, we analyze the interannual variation in the composition of fish assemblages of 11 intermittent streams of the Purus-Madeira Interfluvie. The composition of the assemblages was quite variable between years, however the streams more connected with the floodplain presented more stable assemblages and shared more species between years, while the most distant assemblages present high species substitution over the analyzed period. Our results provides a clue that these assemblages are structured both by stochastic processes of dispersion and local extinction, and by the recruitment dynamics of the floodplain.