Fish fauna of the Pelotas River, Upper Uruguay River, southern Brazil

Rosilene Luciana Delariva,Gilmar Baumgartner,Dirceu Baumgartner,Mayara Pereira Neves

doi:10.1590/1676-0611-bn-2018-0638

Rosilene Luciana Delariva, Gilmar Baumgartner + Show 2 more

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https://doi.org/10.1590/1676-0611-bn-2018-0638

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Abstract

Abstract: The fish fauna of the Pelotas River, in the Upper Uruguay ecoregion of southern Brazil was inventoried. Samplings were performed quarterly between August 2013 and May 2014 at 14 sites in the Pelotas River and its tributaries, using gill nets of different mesh sizes, sein nets, cast nets and electrofishing. In total, 7,745 specimens were recorded, comprising 46 species, belonging to 13 families and five orders. Approximately 80% of the species belonged to the orders Characiformes and Siluriformes, as well as the families Characidae and Loricariidae, which included a greater number of species. Of the total species, 24% were endemic to the Upper Uruguay River, four were identified only at the genus level and none was considered non-native. Approximately, half of the 98 species previously recorded for the Upper Uruguay basin were also detected in this study. The tributaries of the Pelotas River exhibited different faunas with five exclusive species. Thirty species were present in both the tributaries and the main channel. In addition, higher species richness, as well as the presence of larger-sized species were observed in the main channel. Many of the species not restricted to the Upper Uruguay River have already been reported as part of the Taquari-Antas River fauna. However, the local biodiversity of this region is under several threats, such as land use and installation of small hydroelectric plants. These results highlight the importance of the conservation of plateau/upland rivers, especially in the Upper Uruguay ecoregion, which shows a peculiar fish fauna and endemism.

Highlights

The Pelotas River originates in the Serra Geral Formation, on the border between the states of Santa Catarina and Rio Grande do Sul, southern Brazil, and, along with the Canoas River forms the Uruguay River
The highest species richness was observed in the drainage of the Pelotas and the Canoas rivers (Uruguay River basin- 60 species), compared to the basins of the Caí and the Taquari-Antas rivers (Jacuí River basin- 46 species)
The species richness recorded at each sites ranged from 8 to 28, totaling 46 species

Summary

Introduction

The Pelotas River originates in the Serra Geral Formation, on the border between the states of Santa Catarina and Rio Grande do Sul, southern Brazil, and, along with the Canoas River forms the Uruguay River In this region, due to the geomorphological characteristics of the Serra Geral Formation, there is a considerable slope, where the river flows over steep and rocky terrain marked by narrow channels with rapids and falls (Feow 2018). The climate of the ecoregion is characterized by rainfall well distributed throughout the year (humid subtropical – Cfa) (Köppen 1936), unlike that of other ecoregions of the La Plata basin, and marked by the absence of flood pulse, floodplains and marginal lakes These characteristics are strong environmental filters in the selection of species, which, together with other biogeographic factors, favor a peculiar fauna. The increase in the construction of hydroelectric dams and agro-industrial activities has implications for the biodiversity, affecting different trophic levels of fish assemblages (Becker et al 2013, Jorgensen et al 2013, Schork & Zaniboni-Filho 2017)

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