Estrutura da ictiofauna do rio Bonito, bacia hidrográfica do rio Ivaí, sistema alto rio Paraná, Brasil

Abstract

The ichthyofauna diversity of the Ivaí river basin is largely underestimated. The present study aimed to characterize the fish fauna of the Bonito River, a tributary to the Ivaí River, upper Paraná river basin, in relation to richness, diversity and constancy. It was established three sampling sites along the longitudinal gradient of the river: headwater, medium stretch and mouth, at the point near the confluence to Ivaí river. Three collection expeditions were made in each site. Gill nets of different meshes, cast nets and traps were used. The ichthyofauna of the Bonito river was composed by 23 species, divided into nine families and three orders. Among the sampled species, three were possible new records for the upper Paraná river basin and 12 for the Ivaí river basin. The highest species richness was recorded in the lower stretch, where 20 species were found. In the middle section of the river, seven species were collected and just one species was captured at headwater. In the lower stretch it was also obtained the greatest diversity and lower species dominance. Additionally, in the lower Bonito river most of the species were incidental, whereas in the middle section five species were constant and only one was accessory. The middle section had the most dominant species, Hypostomus aff. ancistroides. The altitudinal gradient seems to determine the pattern of species distribution, delimiting the assemblages along longitudinal gradient of the river. O clima predominante é o subtropical úmido mesotérmico de temperatura média anual de 20 °C, com precipitação média anual de 1.600 a 1.700 mm. O rio Bonito está inserido nas unidades geológicas de formação da Serra Geral, Pirambóia, Botucatu e Formação Rio do Rastro. Seu curso corre no sentido leste do município de Turvo e desemboca ao norte, na margem esquerda do rio Ivaí (Viana et al. 2008).O rio Bonito apresenta na maior parte de seu curso ambientes de correnteza rápida a moderada, com profundidade média próxima a 1,5 m, alternado por remansos e poções com profundidades um pouco superiores. O substrato do rio é rochoso, com pouca deposição de sedimentos, na maior parte constituída de galhos, pequenos troncos e matéria particulada, predominantemente retidos nas margens.Uma das características deste rio é o desnível observado entre os trechos superior (1.002 m), médio (790 m) e inferior (461 m), com presença de quedas de água durante seu percurso, sendo uma delas localizada entre os trechos inferior e médio, com altura superior a 80 m. Com relação ao uso e ocupação das margens, na região da cabeceira a principal atividade é a agricultura, que tem contribuído para a destruição da vegetação ripária e o assoreamento do rio. É evidente a instabilidade das margens com muitas áreas descobertas, com erosão transportando grandes quantidades de sedimento das áreas de cultivo que se depositam no leito do rio. Os principais tipos de ocupação nos trechos médio e inferior são a pecuária e a agricultura. O trecho médio apresenta uma elevada diversidade de habitats, no en...

Fish species (Osteichthyes: Actinopterygii) from two tributaries of the Rio do Peixe basin, Tupã municipality, São Paulo state, Brazil

“…In terms of richness the two most diverse Neotropical families (Characidae and Loricariidae) (Reis et al 2003) had representatives at all sites and also showed the greatest number of collected specimens, a pattern also found by other studies on the upper Rio Paraná basin fish fauna (e.g., Maier et al 2008;Castro et al 2004;Oyakawa & Menezes 2011;Delariva & da Silva 2013;Viana et al 2013;Frota et al 2016). …”

Inventory of the fish fauna from Ivaí River basin, Paraná State, Brazil

“…Also contributing to the pollution of its waters, the area comprises virtually no conservation units and little riparian vegetation due to the intensive use of the soil for agriculture and cattle raising (Paraná 2010). These activities greatly contribute to the siltation of the waterbodies, which was observed in the sites sampled herein and by Viana et al (2013), and lead to destruction of native vegetation that provide important food items in the diet of some species.…”

“…As already highlighted by Viana et al (2013) in their study of the Bonito River, backwaters separated by rapids typically bear a wide variety of microhabitats. Those environments favour species with greater ability to stay in the water column (e.g., Astyanax and Bryconamericus), as well as benthic species equipped with spines that allow them to attach to rocks and resist the water flow (e.g., loricariids and Trichomycterus).…”

“…2 and Trichomycterus sp. 3 in the studies of Maier et al (2008), Araújo et al (2011), Delariva & Silva (2013 and Viana et al (2013), which are deposited in the fish collection of Nupélia, were re-examined and identified as Trichomycterus davisi (Haseman, 1911). In addition, some species recorded in the collections analysed were re-examined and identifications were rectified, namely: Hypostomus aspilogaster (Cope, 1894) is Hypostomus ancistroides (Ihering, 1911) Thomaz et al (2015) and Hisonotus insperatus Britski & Garavello, 2003 and H. oliveirai to Curculionichthys by Roxo et al (2015).…”

“…There are only few surveys on fish fauna in the Ivaí River basin, especially for the tributaries, Barra Bonita River (Maier et al 2008), Bonito River (Viana et al 2013), some streams located in the Perobas Biological Reserve (Delariva & Silva 2013) and a first-order stream in the municipality of Marialva (Araújo et al 2011); and there are few genetic studies with some species of Loricariidae (Zawadzki et al 2004, Portela-Castro et al 2007, Paiva et al 2013 or ecological studies (Luiz et al 2003, Luiz et al 2005) and description of new species (Graça & Pavanelli 2008, Roxo et al 2014, Tencatt et al 2014, Zawadzki et al 2016) with fish of this basin.…”