ICHTHYOFAUNA OF TRIBUTARY STREAMS OF THE CINZAS RIVER BASIN, PARANAPANEMA RIVER, BRAZIL

Abstract

Streams are environments that are very affected by human activities such as pollution, deforestation of riparian forests and introduction of exotic species. In this context, it is important to know its biodiversity for monitoring and conservation. The present study inventoried the fish fauna of three tributary streams of the Jacarezinho River (Cinzas River basin, Paranapanema River) with different environmental characteristics: Água dos Anjos, Monjolinho and Ubá streams. Quarterly collections were performed in the period between October 2012 and July 2013 at the headwaters, in the middle and at the mouth of each stream, using electrofishing. We analyzed the parameters of species richness, total abundance, relative abundance, capture constancy, rarefaction curves of Coleman, and richness estimators ACE and ICE. We captured a total of 7102 individuals, distributed in six orders, 12 families and 33 species. The most abundant order was Characiformes (76.15 %), while the most abundant species were: Bryconamericus iheringii (39.5 %), Astyanax bockmanni (19.36 %), and Geophagus brasiliensis (7.52 %). The highest species richness was found in Água dos Anjos stream (26), followed by Monjolinho stream (25), and the Ubá stream (15). We recorded the occurrence of four non-native species (Bryconamericus exodon, Gymnotus inaequilabiatus, Poecilia reticulata and Oreochromis niloticus), which represent a risk to the biodiversity of the studied streams. The Ubá stream was considered the most conserved, but the presence of P. reticulata shows that it has also suffered from anthropic impacts. This non-native species is constantly associated to degraded environments, mainly when it occurs in high abundance. Our results suggest that the fish assemblages studied present different structures, probably due to the interaction among historical, abiotic, biotic, and anthropic factors. This study has been carried out for the first time in the Cinzas River basin and can help provide theoretical input for the elaboration of monitoring and conservation plans.