Relação entre variáveis ambientais e a estrutura da comunidade de peixes em córregos das bacias do Rio das Mortes e do rio Xingu – MT, Brasil

Abstract

As variáveis ambientais podem determinar e estruturar a composição da fauna de peixes. Estudos que comparem diferenças entre variáveis físicas e químicas da água entre bacias hidrográficas próximas são escassos. Este artigo teve por objetivo verificar quais variáveis limnológicas estão relacionadas à distribuição das espécies de peixes em duas bacias hidrográficas. Para tanto, foram amostrados 20 córregos, divididos entre as bacias do Rio das Mortes e do rio Xingu. Em cada ponto foram medidos um total de 8 variáveis ambientais. Os peixes foram coletados com rede de arrasto. A riqueza total foi de 57 espécies, sendo 29 da bacia do rio Xingu, 35 do Rio das Mortes e 7 espécies comuns a ambas as bacias. As análises demonstraram que os córregos dessas duas bacias têm características limnológicas e fauna distintas. Os córregos da bacia do rio Xingu tiveram menores valores de pH que podem ter sido influenciados pelas elevadas taxas de decomposição orgânica. Os córregos do Rio das Mortes apresentaram valores mais elevados de matéria em suspensão e clorofila, provavelmente ocasionadas pela maior degradação dos córregos e menores níveis de cobertura vegetal.

Streams fish from Upper Araguaia and Middle Rio da Mortes basin, Brazil: generating subsidies for preservation and conservation of this critical natural resource

“…The average stream fish species richness observed in our study streams was 15 species, like the value found in other stream fish studies in this ecoregion (Melo et al 2004, Matos et al 2013, Barbosa et al 2019, Oliveira et al 2020). However, our data showed a wide variance in the number of species per stream.…”

“…Considering the high fish species endemicity within these basins, there is a significant likelihood that many of these species identified only up to the genera level are new species. Previous studies on stream fish in these basins have also found similar patterns, with a great number of species not yet described ( Melo et al 2004, Matos et al 2013, Jarduli et al 2014, Oliveira et al 2020. This large number of species to be described is one of the most important knowledge gaps in biodiversity (Linnean shortfalls) that needs to be addressed (Hortal et al 2015).…”

Influence of different types of margins in the fish assemblage from an urban river

“…The result of the many characteristics of habitats, which influence the patterns of composition and diversity of fish communities, such as environmental filters, the availability of resources, and the complexity of habitats (Felipe and Súarez, 2010), are aspects that contribute to installation and development of fish species. Araújo and Tejerina-Garro (2009) and Matos et al (2013) showed that the structuring and distribution of the fish community may be more associated with the physical and structural characteristics of the environment, favouring the occurrence of species; however, when these are destroyed or altered, more sensitive fish species can be removed locally, contributing to the installation of more tolerant species.…”

Fish fauna in tributaries of the Suiá-Miçú River (upper Xingu river basin), in the Cerrado-Amazon transition zone, eastern state of Mato Grosso, Brazil

“…Our results highlight the importance of preservation of the integrity of headwaters ecosystems. However, the rapid environmental change observed in this region for agriculture or livestock has affected the water quality of the streams , Matos et al 2013. Furthermore, this represents a threat to the biodiversity of this ecoregion putting many species at risk of disappearing before they are described.…”