Sampling trends and non-native fish species in brazilian streams: a synthesis of the ecological knowledgement

Abstract

Stream environments have characteristics which make them at once both important for biodiversity and human wellbeing, and highly threatened by human activities, which has attracted the attention of researchers. But, despite the high proportion of endangered freshwater fish species, very few management and conservation actions explicitly for Brazilian stream fishes have been effectively established. However, studies have argued that communication among scientists, policy-makers and society at large can be significantly improved through systematic review and synthesis of existing studies. Here we did systematic review of papers about fish stream assemblages in Brazil to detect trends in sampling protocolos and evaluated sampling effort in studied basins (Chapter 1). Further, we assessed the effect-size of non-native fish species on fish assemblages on Paraná basin (Chapter 2). We showed that studies of assemblage fish stream deployed a variety of sampling methods, but we found a growing trend towards the use of the electrofishing, sampling stream lengths of 50 meters, and over duration of 60 minutes. Our results highlight that regional species pools (gamma diversity) are still underestimated in all analyzed basins. The results of manuscript 2 found that non-native fish species are coexisting with native species at higher native richness streams in Paraná basin. We also show that the greater functional diversity in streams with nonnative species was explained by the richness of native species rather than the richness of non-native species, corroborating with the clear results of niche overlap between native and non-native fish species. This study highlights that further surveys and taxonomic revisions of stream fishes are still paramount in most regions and point out to importance of more fish sampling effort surveys in Brazilian streams. We reinforce the importance of standardization in sampling protocols among studies to needed a make the necessary stream conservation advances in Brazil. Moreover, we also conclude that area with higher native fish species at Paraná basin could be focus of management of fish invasion and conservation efforts. Finally, we agree that researches should work collaboratively through data sharing, interinstitucional projects and exchange of researches to overcome challenges in the freshwater fish research in Brazil.