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Seasonal variation and diversity of fishes of the Cambará river, Uruguay Basin

The aim of this study was to analyze the ictiofaun of Cambará River, Uruguay Basin, as well as the body dimensions of the organisms. The work was accomplished in two stretches of Cambará River (2nd order) in Cruz Alta, RS. To the accomplishment of this research were performed identifications of individuals captured in May, September and November 2009 and February 2010 by using of gillnets, which remained in water for 24 hours, being checked every eight hours (1:00 and 9:00 AM and 5:00 P.M.). Besides the gillnets, were also used trawl (mesh 1.0 mm), and fishing rods. The fish collected were cataloged and fixed in formaldehyde at 10.0% and then conserved in alcohol 70.0%. In total, 420 individuals were identified, with a richness of 26 species and eight families. The species were classified in: constant (23.08%), accessory (42.31%) and accidental (34.61%). Loricariidae (nine species and 156 individuals) and Characidae (seven species and 136 individuals) were the most typical. Among individuals collected are highlighted as more abundant: Hemiancistrus fuliginosus (89), Astyanax eigenmanniorum (50), and Rhamdia aff. quelen (44). One recorded species was of large mien (Hoplias lacerdae, with 164.92 g total weight and 23.40 cm total length), five medium sized species (98.55-164.92 g total weight and 19.56-21.50 cm total length) and 20 small species (less than 57.79 g total weight and 17.38 cm total length). The diversity was higher in hotter months, mainly between 1:00 and 9:00 A.M. The collector curve showed that still exist species of fish for being collected in Cambará River. Concluding that despite of the existence of environmental impacts in the stretch of study, it showed satisfactory diversity and richness, influenced by factors like heterogeneity of habitats and supply of allochthonouss material, as well as intrinsic factors (activity and reproduction) to the present species.

Ictiofaunistic; Uruguay Basin; richness; constancy of occurrence

Instituto Virtual da Biodiversidade | BIOTA - FAPESP Departamento de Biologia Vegetal - Instituto de Biologia, UNICAMP CP 6109, 13083-970 - Campinas/SP, Tel.: (+55 19) 3521-6166, Fax: (+55 19) 3521-6168 - Campinas - SP - Brazil