Ecologia do movimento da ictiofauna em riachos brasileiros

Abstract

The movement of fish in streams is a fundamental process for maintaining the biodiversity of freshwater ichthyofauna in continental aquatic environments. In Brazil, despite the recognized megadiversity of fish utilizing streams throughout their life histories, studies on movement patterns remain scarce. The first chapter of this dissertation reviews the available literature on fish movement in Brazilian streams, identifying two main patterns: the predominance of upstream movement in pelagic species, associated with egg and larval drift, and non-directional leptokurtic dispersal in benthic species. Research efforts are concentrated in coastal zones, relying predominantly on low-cost methods such as spatiotemporal distribution analyses, while advanced technologies like telemetry remain underutilized. The second chapter investigates a specific spatial pattern, the "larger fish upstream" pattern, in a stream fish community in South America. Historical size distribution data revealed that four species consistently exhibit the larger fish upstream pattern, primarily driven by the distance upstream. Species with pelagic or lithopelagic reproductive strategies support the hypothesis that upstream movement is essential for population stability. The findings of this dissertation highlight the importance of maintaining the integrity and connectivity of streams for the conservation of both exclusive stream ichthyofauna and adjacent aquatic environments.