Fish from urban tributaries to the Vermelho River , upper Paraguay River Basin , Mato Grosso , Brazil

The fish fauna of urban streams is still poorly known, it difficult to assess the effects of urbanization expansion on fish species composition, for this reason the aim of this study was to provide a checklist of species that compose the ichthyofauna of six urban streams, tributaries to the Vermelho River, upper Paraguay River Basin, Rondonópolis, Mato Grosso State, Brazil. The samples were performed with seine nets on a spatial gradient of 75 m, and with sieves for a period of 15 minutes in each site. A total of 56 species belonging to five orders, Characiformes, Siluriformes, Gymnotiformes, Cyprinodontiformes, and Perciformes, 21 families and 44 genera were sampled. The most common species were Astyanax asuncionensis Géry, 1972, Astyanax abramis (Jenyns, 1842), Odontostilbe pequira (Steindachner, 1882), Odontostilbe paraguayensis Eigenmann & Kennedy, 1903, Characidium zebra Eigenmann, 1909 and Hypostomus sp. This checklist brings additional knowledge on fish that inhabit tributaries to the major rivers of northern Pantanal.


INTRODUCTION
The Brazilian Cerrado has been exposed to a major process of urbanization (Sano et al. 2010) and many of the waterways cross urban centers, suffering the impact of human occupation, which is characterized by constant discharge of effluents produced from anthropogenic activities (Paul and Meyer 2001).Among other effects, urbanization leads to habitat degradation, resulting in the reduction of the most sensitive species and in an increased abundance of more resistant species (Cunico et al. 2006), as well as greater susceptibility to invasive species (Domingos et al. 2013).Unfortunately, the fish fauna from urban streams still is poorly known (Felipe and Suárez 2010), making it difficult to assess the effects of urbanization expansion on fish species composition.Despite the fragility of these streams front of negative influences of anthropic activities (Oliveira and Bermann 2005) in Brazil publications on the ichthyofauna of small streams in Cerrado areas are still rare when compared with what is known about the fish fauna from the main channel of large river basins and their larger tributaries (MMA 2007).
The Vermelho River has several tributaries which flow through the city of Rondonópolis that are subject to the impacts of urbanization (Loverde-Oliveira and Figueiredo 1999) because the drainage area is located in one of the most important regions of the brazilian agribusiness in the central-west of the country where the large-scale agriculture and agricultural products processing industries create a huge possibility of impacts over the fish fauna.
Considering that the knowledge of the fish species from waterways that run through urban environments are important to understand the ecology and conservation of the region, besides indicating the degradation state of the streams under study.For these reasons the aim of this study was to provide the first list of species of fish that inhabit the urban streams of the city of Rondonópolis.

MATERIALS AND METHODS
The study was conducted in six urban streams, tributaries to the Vermelho/São Lourenço Rivers (Upper Paraguay River Basin), in Rondonópolis, Mato Grosso State (Figure 1).These streams are tributaries to the rivers that form the northern Pantanal floodplain.
Seine nets were used in the spatial gradient of 75 m and sieves for a period of 15 minutes in each site.The cumulative curve of species (Figure 2) was performed in Vegan package (Oksanen et al. 2011) include in R project (R Development Core Team 2011).
Fish caught were kept in 10% formalin, packed in plastic bags and preserved in 70% alcohol.Fish were collected under the license of the Secretaria Estadual de Meio Ambiente do Estado de Mato Grosso (SEMA) (Process numbers 018/2010, 513997/2010).Specimens were identified to the lowest possible taxonomic level based on Britski et al. 2007, Benine et al. 2009and Costa 2011.We checked spelling of all scientific 29 species from nine families.Among the families recorded, Characidae had the greatest number of taxa (n=22).The order Siluriformes was represented by 16 species of five families.Gymnotiformes was represented by six species of five families.Cyprinodontiformes by one family with one species and Perciformes by one family with four species (Table 1).

RESULTS
The fish fauna was composed by 56 species from a sample of 5,038 individuals, belonging to five orders Characiformes, Siluriformes, Gymnotiformes, Cyprinodontiformes and Perciformes, 21 families and 44 genera (Table 1).Species richness in the sampling station showed variation between 17 and 33 taxa/sample.The lowest value of species richness was found in the Lourencinho stream and the greatest richness was recorded in both Lajeadinho and Macaco streams (Table 1).The species richness did not differ between rural and urban sections or periods.The species diversity on average was reduced and similar (<1 bits ind -1 ) in both periods and sampling locations.
According to the collector curve (Figure 2) the streams were relatively well sampled, because the species richness reached the level of stabilization, however, it does not mean that one or more species could not still be collected.
The orders Characiformes and Siluriformes were predominant in terms of number of species, regardless of the period or sampling site.Characiformes was represented by

DISCUSSION
Other studies in the Cerrado region (Lemes and Garutti 2002;Verissimo et al. 2005;Aquino et al. 2009;Machado et al. 2011;Casatti et al. 2013) obtained the same results regarding the predominance of the orders Characiformes followed by Siluriformes.These authors emphasized that, in streams, the family Characidae stands out for having the greatest number of species, corroborating the results found in the urban streams of Rondonópolis.The fish inventory conducted by Castro and Vizzoto (2013) in the Vermelho River, the main river into which flow the streams included in this study, confirmed the predominance of Characiformes in large rivers of the Upper Paraguay River Basin.
The diversity and composition of fish from streams is not fully known (Casatti 2001), however the predominance of Characiformes and Siluriformes in lotics reflects its greater representation in the neotropical ichthyofauna of freshwater systems (Lowe-McConnell 1999;Castro 1999) (Britski et al. 2007;Teresa et al. 2010;Pacheco et al. 2012) and Uruguay Basin (Teixeira- de Mello et al. 2011).
Even in the case of streams within urban stretches, species richness was considered relatively high, representing 21% of the species (n=269) described for the Pantanal (Britski et al. 2007) and stated for the Upper Paraguay River Basin (Yzel et al. 2007;Polaz et al. 2014), to the basin of the Paraguay and Paraná rivers (Cionek et al. 2012).This rich fish community composition associated with dominance of small individuals (Oliveira et al. 2014) corroborate with the considerations of Castro (1999) which highlights the small size of the fish, the relatively high degree of endemism and the occupation of very specific microhabitats as factors that further accentuate the need to establish strategies for the conservation of streams.Thus, since urbanization pressure in this region is large, this checklist is essential to support the adoption of mitigating measures for reducing the impact of environmental degradation and thus ensure that these streams continue to support a diverse ichthyofauna.

Figure 2 .
Figure 2. Species accumulation curve (solid line) and confidence interval (dotted line) for the sampled streams in the Vermelho River basin.

Table 1 .
Checklist of fish species recorded in each stream, with occurrence of taxa per stream.The streams are represented by A = Arareau, E = Escondidinho, LA = Lajeadinho, Q = Queixada, LO = Lourencinho, M = Macaco.