Abstract:

The Paranapanema River is an important, extensively explored tributary of the Upper Paraná River basin. The fish fauna of the Paranapanema River has been investigated since the 1990s; however, no study has characterized the richness of fish species throughout the basin, including the main channel of the river, marginal lagoons, its tributaries, and sub-tributaries. Thus, we performed a review with 90 independent studies conducted at the upper, middle, and lower sections of the basin. We recorded 225 species, of which 165 were native, and 60 were non-native. We found that 77% of the species within the basin are composed by Siluriformes and Characiformes. Cichliformes had a significant number of non-native species established in impoundment sections of the basin. Incidence-Based Estimators (Bootstrap and Chao 2) demonstrated that the richness of native species is still underestimated. Some native (e.g., Hypostomus ancistroides) and non-native species (e.g., Plagioscion squamosissimus) are widely distributed in the basin, while others had a more restricted distribution. Among the registered species, the family Bryconidae had the highest number of representatives with threatened conservation status. In addition, we observed that the Capivara Reservoir and its tributaries were the most sampled regions, with the majority of studies performed in the Lower Paranapanema basin. The species richness recorded in large tributaries, such as Tibagi, Cinzas, Congonhas, and Pirapó rivers is critical for maintaining the fish fauna in the Paranapanema River. Our contribution may be used to support management actions and conservation strategies, as well as to indicate regions in the basin that need to be better inventoried.

Keywords:
freshwater; Neotropical region; species inventory; Upper Paraná River

Resumo:

O rio Paranapanema é um importante tributário, amplamente explorado da bacia do Alto rio Paraná. A fauna de peixes do rio Paranapanema vem sendo investigada desde a década de 1990; no entanto, nenhum estudo caracterizou a riqueza de espécies de peixes em toda a bacia, incluindo o canal principal do rio, lagoas marginais, seus tributários e sub-tributários. Assim, realizamos uma revisão com 90 estudos independentes conduzidos nas regiões superior, média e inferior da bacia. Foram registradas 225 espécies, das quais 165 eram nativas e 60 eram não nativas. Verificamos que 77% das espécies dentro da bacia são compostas por Siluriformes e Characiformes. Cichliformes apresentou um número significativo de espécies não nativas estabelecidas em áreas de represamento da bacia. Estimadores de riqueza baseados em incidência (Bootstrap e Chao 2) demonstraram que a riqueza de espécies nativas ainda é subestimada. Algumas espécies nativas (e.g., Hypostomus ancistroides) e não nativas (e.g., Plagioscion squamosissimus) estão amplamente distribuídas na bacia, enquanto outras tem sua distribuição mais restrita. Entre as espécies registradas, a família Bryconidae obteve o maior número de representantes com status de conservação ameaçado. Além disso, observamos que o reservatório de Capivara e seus afluentes foram as regiões mais amostradas, sendo a maioria dos estudos realizados na bacia do baixo Paranapanema. A riqueza de espécies registrada em grandes afluentes, como os rios Tibagi, Cinzas, Congonhas e Pirapó, é fundamental para a manutenção da ictiofauna no rio Paranapanema. Nossa contribuição pode ser usada para apoiar ações de manejo e estratégias de conservação, bem como para indicar regiões na bacia que precisam ser melhor inventariadas.

Palavras-chave:
água doce; região Neotropical; inventário de espécies; Alto rio Paraná

Introduction

South America has the greatest diversity of freshwater fish fauna in the world, with a high taxonomic, phylogenetic, and functional variety (Barletta et al. 2010BARLETTA, M., JAUREGUIZAR, A.J., BAIGUN, C., FONTOURA, N.F., AGOSTINHO, A.A., ALMEIDA-VAL, V.M., VAL, A.L., TORRES, R.A., JIMENES-SEGURA, L.F., GIARRIZZO, T., FABRÉ, N.N., BATISTA, V.S., LASSO, C., TAPHORN, D.C., COSTA, M.F., CHAVES, P.T., VIEIRA, J.P. & CORRÊA, M.F. 2010. Fish and aquatic habitat conservation in South America: a continental overview with emphasis on neotropical systems. J. Fish. Biol. 76(9):2118-2176., Reis et al. 2016REIS, R.E., ALBERT, J.S., DI DARIO, F., MINCARONE, M.M., PETRY, P. & ROCHA, L.A. 2016. Fish biodiversity and conservation in South America. J. Fish Biol. 89:12-47., Vitule et al. 2017VITULE, J.R.S., AGOSTINHO, A.A., AZEVEDO-SANTOS, V.M., DAGA, V.S., DARWALL, W.R.T., FITZGERALD, D.B., FREHSE, F.A., HOEINGHAUS, D.J., LIMA-JUNIOR, D.P., MAGALHÃES, A.L.B., ORSI, M.L., PADIAL, A.A., PELICICE F.M., PETRERE JR., M., POMPEU, P.S. & WINEMILLER, K.O. 2017. We need better understanding about functional diversity and vulnerability of tropical freshwater fishes. Biodivers. Conserv. 26(3):757-762.). Such diversity is sheltered mainly in the Amazon (Santos & Ferreira 1999SANTOS, G.M. & FERREIRA, E.J.G. 1999. Peixes da bacia amazônica. In: Estudos ecológicos de comunidades de peixes tropicais (R.H. Lowe-McConnell, eds). Edusp, São Paulo, p.345-373.), and Paraná (Brea & Zucol 2011BREA, M. & ZUCOL, A.F. 2011. The Paraná-Paraguay basin: geology and paleoenvironments. In Historical biogeography of Neotropical freshwater fishes (J.S. Albert & R.E. Reis, eds). Berkeley CA: University of California Press, p.69-87.) river basins. The Upper Paraná River basin is one of most studied basins in terms of fish fauna (Agostinho et al. 2007aAGOSTINHO, A.A., GOMES, L.C., PELICICE, F.M. 2007a. Ecologia e manejo de recursos pesqueiros em reservatórios do Brasil. Maringá: Eduem.), being composed of between 270 to 310 species (Agostinho et al. 2007bAGOSTINHO, A.A., PELICICE, F.M., PETRY, A.C., GOMES, L.C. & JÚLIO JÚNIOR, H.F. 2007b. Fish diversity in the upper Paraná River basin: habitats, fisheries, management and conservation. Aquat. Ecosyst. Health Manag. 10(2):174-86., Langeani et al. 2007LANGEANI, F., CASTRO, R.M.C., OYAKAWA, O.T., SHIBATTA, O.A., PAVANELLI, C.S. & CASATTI, L. 2007. Diversidade da ictiofauna do Alto Rio Paraná: composição atual e perspectivas futuras. Biota Neotrop. 7(3): 181-197 http://www.biotaneotropica.org.br/v7n3/pt/abstract?article+bn03407032007 (último acesso em 27/08/2018).
http://www.biotaneotropica.org.br/v7n3/p... ). The Upper Paraná River basin is the second largest basin in South America (Lowe-McConnell 1999LOWE-McCONNELL, R.H. 1999. Estudos ecológicos de comunidades de peixes tropicais. Tradução de Anna Emília A. M. Vazzoler; Angelo Antonio Agostinho; Patrícia T. M. Cunningham São Paulo: EDUSP.) and is composed of sub-basins originating in the Brazilian states of Goiás, Minas Gerais, São Paulo, Mato Grosso do Sul, and Paraná. The basin is constituted from the confluence of major tributaries, such as the Paranaíba, Grande, Tietê, and Paranapanema rivers.

The Paranapanema River - one of the most important tributaries of the left margin of the Paraná River (Maack 2002MAACK, R. 2002. Geografia física do estado do Paraná. 3 ed: Imprensa Oficial do Paraná., Duke Energy 2008DUKE ENERGY, 2008. Peixes do rio Paranapanema. Horizonte Geográfico, 2ª Ed. São Paulo.) - hosts a significant part of this diversity, as evidenced by several fish inventories and ecological studies performed on its main course (Carvalho et al. 1998CARVALHO, E.D., DA SILVA, V.F.B., FUGIHARA, C.Y., HENRY, R. & FORESTI, F. 1998. Diversity of fish species in the River Paranapanema Jurumirim Reservoir transition region (São Paulo, Brazil). Italian J. Zool. 65:325-330., Pelicice et al. 2005PELICICE, F., AGOSTINHO, A.A. & THOMAZ, S.M. 2005. Fish assemblages associated with Egeria in a tropical reservoir: investigating the effects of plant biomass and diel period. Acta Oecologica. 27:9-16., Britto & Carvalho 2006BRITTO, S.G.C. & CARVALHO, E.D. 2006. Ecological attributes of fish fauna in the Taquaruçu reservoir, Paranapanema River (upper Paraná, Brazil): composition and spatial distribution. Acta Limnol. Bras. 18(4):377-388., Orsi 2010ORSI, M. L. 2010. Estratégias reprodutivas de peixes da região média-baixa do rio Paranapanema, Reservatório de Capivara. Blucher Acadêmico, São Paulo., Orsi & Britton 2014ORSI, M.L. & BRITTON, J.R. 2014. Long-term changes in the fish assemblage of a neotropical hydroelectric reservoir. J. Fish Biol., 84(6):1964-1970., Pelicice et al. 2018PELICICE, F. M., AZEVEDO-SANTOS, V.M., ESGUÍCERO, A.L.H., AGOSTINHO, A.A. & ARCIFA, M.S. 2018. Fish diversity in the cascade of reservoirs along the Paranapanema River, southeast Brazil. Neotrop. Ichthyol. 16(2):e170150.), tributaries, and sub-tributaries (Castro et al. 2003CASTRO, R.M.C., CASATTI, L., SANTOS, H.F., FERREIRA, K.M., RIBEIRO, A.C., BENINE, R.C., DARDIS, G.Z.P., MELO, A.L.A., STOPIGLIA, R., ABREU, T.X., BOCKMANN, F.A., CARVALHO, M., GIBRAN, F.Z. & LIMA, F.C.T. 2003. Estrutura e composição da ictiofauna de riachos do Rio Paranapanema, sudeste e sul do Brasil. Biota Neotrop. 3(1): 1-31 http://www.biotaneotropica.org.br/v3n1/pt/abstract?article+BN01703012003 (último acesso 09/09/2018)
http://www.biotaneotropica.org.br/v3n1/p... , Cerqueira & Smith 2015CERQUEIRA, V.L.A. & SMITH, W.S. 2015. Composição ictiofaunística do Rio Turvo, Pilar do Sul, São Paulo, Brasil. J. Health Sci. Inst. 33(1):7-14., Vidotto-Magnoni et al. 2015VIDOTTO-MAGNONI, A.P., GARCIA, D.A.Z., COSTA, A.D.A., SOUZA, J.G., YABU, M.H.S., ALMEIDA, F.S. & ORSI, M.L. 2015. Ichthyofauna of streams of the Lower Paranapanema River basin, state of Paraná, Brazil. Check List, 11(5):1756, Rosa et al. 2016ROSA, R.R., CAETANO, D.L.F., BELLAY, S., MORAES, V.R. & VIEIRA, F.E.G. 2016. Diversidade de peixes de tributários do reservatório de Chavantes, PR, bacia do alto rio Paraná. Biotemas. 29(2):33-43.). Past works suggest that species compilations from the Paranapanema River alone vary from 155 (Duke Energy 2008DUKE ENERGY, 2008. Peixes do rio Paranapanema. Horizonte Geográfico, 2ª Ed. São Paulo.) to 161 (Pelicice et al. 2018PELICICE, F. M., AZEVEDO-SANTOS, V.M., ESGUÍCERO, A.L.H., AGOSTINHO, A.A. & ARCIFA, M.S. 2018. Fish diversity in the cascade of reservoirs along the Paranapanema River, southeast Brazil. Neotrop. Ichthyol. 16(2):e170150.).

This novel study investigates the richness of fish species throughout the Paranapanema River basin, including its main channel, marginal lagoons, tributaries, and sub-tributaries. An accurate assessment of the species within this ecosystem is a necessary step towards the maintenance of its biodiversity (Cudmore-Vokey & Crossma 2000CUDMORE-VOKEY, B. & CROSSMAN, E. J. 2000. Checklists of the fish fauna of the Laurentian Great Lakes and their connecting channels. Can. MS Rpt. Fish. Aquat. Sci.). To gain the most benefit from previous surveys, updates are needed to indicate changes over time. These changes can include the establishment of species (both native and introduced), introductions that are not established (Garcia et al. 2018GARCIA, D. A. Z., BRITTON, J. R., VIDOTTO-MAGNONI, A. P., & ORSI, M. L. 2018. Introductions of non-native fishes into a heavily modified river: rates, patterns and management issues in the Paranapanema River (Upper Paraná ecoregion, Brazil). Biol. Inv. 20(5): 1229-1241.), and species that become extirpated or extinct. Thus, an updated fish inventory on the Paranapanema River basin is fundamental to optimize its management in relation to low impact actions, resources conservation, and recovering degraded ecosystems (Melo 2008MELO, AS. 2008. O que ganhamos 'confundindo' riqueza de espécies e equabilidade em um índice de diversidade? Biota Neotrop. 8(3):21-27. http://www.biotaneotropica.org.br/v8n3/pt/abstract?article+bn00108032008 (último acesso em 07/09/2018)
http://www.biotaneotropica.org.br/v8n3/p... ). Therefore, we aimed to complement the knowledge of the fish fauna diversity present in the Paranapanema basin through a compilation of all survey studies and species descriptions from all aquatic environments. Our study may help the understanding of the richness and distribution of species present along the basin.

Material and Methods

1. Study area

The Paranapanema River headwater is located within the state of São Paulo, municipality of Capão Bonito, is protected by the State Parks of Intervales and Carlos Botelho. The basin has an area of 106.500 km² and crosses 247 municipalities, 115 in the state of São Paulo, and 132 in the state of Paraná (ANA 2016AGENCIA NACIONAL DE ÁGUAS (ANA), 2016. Plano Integrado de Recursos Hídricos da Unidade de Gestão de Recursos Hídricos Paranapanema. Agencia Nacional das Águas - Brasília.). Its waters run for approximately 930 km inland to the west until draining into the left margin of the Paraná River. Starting the mouth of the river Itararé, the Paranapanema forms a border (330 km) between the states of São Paulo and Paraná. According to Sampaio (1944)SAMPAIO, T. 1944. Relato sobre os estudos efetuados nos rios Itapetininga e Paranapanema. Revista do Instituto de Geografia e Geologia, 2:30-81., its course is divided into three main sections: the Upper, Middle, and Lower Paranapanema. The Upper Paranapanema constitutes a 180 km extension from its headwater until the confluence with the Apiaí-Guaçu River, this, together with the Itapetininga River, are the main tributaries of this stretch. The Middle Paranapanema is a 328 km extension from the Apiaí-Guaçu mouth to the Salto Grande Dam. The Lower Paranapanema comprises of a 421 km stretch from the Salto Grande Dam, to its mouth in the Paraná River, also known as Pontal do Paranapanema (Figure 1).

In recent past, the drainage area of the Paranapanema River basin was predominantly covered by Atlantic Rainforest and Brazilian Savannah biomes (Sampaio 1944SAMPAIO, T. 1944. Relato sobre os estudos efetuados nos rios Itapetininga e Paranapanema. Revista do Instituto de Geografia e Geologia, 2:30-81., Huek & Seibert 1972HUECK, K., & SEIBERT, P. 1972. Vegetationskarte von Sudamerika:(mapa de la vegetacion de America del Sur). Stuttgart: G. Fischer (viii) 71p.). However, following deforestation, the basin is now an agricultural region, with margins generally surrounded by narrow and degraded riparian forest (Castro et al. 2003CASTRO, R.M.C., CASATTI, L., SANTOS, H.F., FERREIRA, K.M., RIBEIRO, A.C., BENINE, R.C., DARDIS, G.Z.P., MELO, A.L.A., STOPIGLIA, R., ABREU, T.X., BOCKMANN, F.A., CARVALHO, M., GIBRAN, F.Z. & LIMA, F.C.T. 2003. Estrutura e composição da ictiofauna de riachos do Rio Paranapanema, sudeste e sul do Brasil. Biota Neotrop. 3(1): 1-31 http://www.biotaneotropica.org.br/v3n1/pt/abstract?article+BN01703012003 (último acesso 09/09/2018)
http://www.biotaneotropica.org.br/v3n1/p... ). Throughout the entire basin, the only significant and continuous forests fragments along its margins are the Intervales, Carlos Botelho, and the Morro do Diabo State Parks (Inventário Florestal do Estado de São Paulo 1993INVENTÁRIO FLORESTAL DO ESTADO DE SÃO PAULO. 1993. Instituto Florestal, Governo do Estado de São Paulo e Secretaria do Meio Ambiente, São Paulo.).

2. Data Collection

A list of species was generated from an extensive search of available scientific literature about the Paranapanema River basin. This list included species descriptions, inventories, and ecological studies. We performed searches between April to September 2018 in online databases (Web of Science, Scopus, Scielo, and Google Scholar), private libraries, and cross-reference searches using the keyword 'Paranapanema', combined with the keywords 'fish', 'survey', 'ichthyofauna', 'fish fauna', and 'diversity'. All different types of aquatic environments were considered in our search, including reservoirs, rivers, streams, marginal lagoons, and fish ladders. The survey resulted in 90 studies, comprising 74 articles, nine book chapters, two books, and five Ph.D. theses published between 1995 to 2018. Subregions were hierarchically delimited according to the main tributaries of the Paranapanema River basin, as assessed by the studies inventoried herein. Some studies investigated more than one site, resulting in our samples covering 57 subregions (Table 1).

Taxonomic classification and species naming were determined following the studies from Eschmeyer & Fong (2018)ESCHMEYER, W.N., FRICKE, R. & VAN DER LAAN, R. 2018. Catalog of fishes: genera, species, references. http://researcharchive.calacademy.org/research/ichthyology/catalog/fishcatmain.asp (último acesso em 11/10/2018)
http://researcharchive.calacademy.org/re... and Eschmeyer et al. (2018)ESCHMEYER WN, FONG JD (2018). Species by family/subfamily. http://researcharchive.calacademy.org/research/ichthyology/catalog/SpeciesByFamily.asp. (último acesso em 11/10/2018)
http://researcharchive.calacademy.org/re... . Updates on species identification, valid names, and new combinations were performed when necessary. A list of species that have had their taxonomic status modified over the past years has been provided in Table 3. Unprecise species identification recorded as 'sp.' or 'spp.' were not considered in the study. The species identification was not checked for all surveyed literature. The conservation status of the species was derived from works by Mikich & Bérnils (2004)MIKICH, S. B., & BÉRNILS, R. S. 2004. Livro vermelho da fauna ameaçada no Estado do Paraná. Instituto ambiental do Paraná. for the state of Paraná, Bressan et al. (2009)BRESSAN, P.M., KIERULFF, M.C.M. & SUGIEDA, A.M. 2009. Fauna ameaçada de extinção no Estado de São Paulo. São Paulo: Fundação Parque Zoológico de São Paulo, Secretaria do Meio Ambiente. and ALESP (2014)ASSEMBLEIA LEGISLATIVA DO ESTADO DE SÃO PAULO (ALESP). 2014. Decreto Nº 60.133, de 7 de fevereiro de 2014: As espécies da fauna silvestre ameaçadas de extinção, as quase ameaçadas e as deficientes de dados para avaliação no Estado de São Paulo e dá providências correlatas. for the state of São Paulo; and ICMBio (2014ICMBio. 2014. Portaria MMA nº 445, de 17 de dezembro de 2014. Disponível em http://www.icmbio.gov.br/portal/images/stories/bidiversidade/faunabrasileira/avaliacao-do-risco/PORTARIA_N%C2%A_445_DE_17_DE_ DEZEMBRO _DE_2014.pdf (último acesso em 20/09/2018)
http://www.icmbio.gov.br/portal/images/s... , 2018)ICMBio. Instituto Chico Mendes de Conservação da Biodiversidade. 2018. Livro Vermelho da Fauna Brasileira Ameaçada de Extinção: Volume VI - Peixes. In: Instituto Chico Mendes de Conservação da Biodiversidade (Org.). Livro Vermelho da Fauna Brasileira Ameaçada de Extinção. Brasília: ICMBio. 1232p. for Brazil. Threat categories were defined according to Gärdenfors et al. (2001)GÄRDENFORS, U., C. HILTON-TAYLOR, G. M. MACE & J. P. RODRIGUEZ. 2001. The application of IUCN red list criteria at regional levels. Cons. Biol. 15(5):1206-1212..

The non-native species were classified according to the possible cause of occurrence in the Paranapanema River basin (the introduction vector). These were: (1) fish stocking via sport-angling, (2) bait, live-bait fishes used in sport angling; (3) fish farming, escapes from fish farms; (4) biological control, primarily mosquito control; (5) Itaipu Dam, invasion of non-native fish upstream following flooding of the natural biogeographic barrier of the Sete Quedas Falls between the Medium and Upper Paraná River regions; and (6) the aquarium trade. The identification of the introduction vector was based in CESP (1997)CESP. 1997. Produção de alevinos, povoamento/repovoamento nos reservatórios da CESP, CPFL e outros. Companhia Energética de São Paulo, São Paulo., Orsi & Agostinho (1999)ORSI, M.L. & AGOSTINHO, A.A. 1999. Introdução de espécies de peixes por escapes acidentais de tanques de cultivo em rios da bacia do rio Paraná, Brasil. Ver. Bras. Zool. 16(2):557-560, Bennemann et al. (2000)BENNEMANN, S.T., SHIBATTA, O.A. & GARAVELLO, J.C. 2000. Peixes do rio Tibagi: uma abordagem ecológica. Londrina: Editoral UEL., Graça & Pavanelli (2007)GRAÇA, W.J. & PAVANELLI, C.S. 2007. Peixes da planície de inundação do alto rio Paraná e áreas adjacentes. Eduem, Maringá., Langeani et al. (2007)LANGEANI, F., CASTRO, R.M.C., OYAKAWA, O.T., SHIBATTA, O.A., PAVANELLI, C.S. & CASATTI, L. 2007. Diversidade da ictiofauna do Alto Rio Paraná: composição atual e perspectivas futuras. Biota Neotrop. 7(3): 181-197 http://www.biotaneotropica.org.br/v7n3/pt/abstract?article+bn03407032007 (último acesso em 27/08/2018).
http://www.biotaneotropica.org.br/v7n3/p... , Júlio Júnior et al. (2009)JÚLIO JÚNIOR, H.F., DEI TÓS, C., AGOSTINHO, A.A., PAVANELLI, C.S. 2009. A massive invasion of fish species after eliminating a natural barrier in the upper rio Paraná basin. Neotrop. Ichthyol. 7(4):709-718., Pelicice & Agostinho (2009)PELICICE, F.M. & AGOSTINHO, A.A. 2009. Fish fauna destruction after the introduction of a non-native predator (Cichla kelberi) in a Neotropical reservoir. Biol. Invasions. 11:1789-1801., Britton and Orsi (2012)BRITTON, J.R. & ORSI, M.L. 2012. Non-native fish in aquaculture and sport fishing in Brazil: economic benefits versus risks to fish diversity in the upper River Paraná basin. Rev. Fish Biol. Fish. 22:555-565., Ortega et al. (2015)ORTEGA, J.C.G., JÚLIO JR, H.F., GOMES, L.C. & AGOSTINHO, A.A. 2015. Fish farming as the main driver of fish introductions in Neotropical reservoirs. Hydrobiologia. 746:147-158., Azevedo-Santos et al. (2016)AZEVEDO-SANTOS, V.M., VITULE, J.R.S., GARCÍA-BERTHOU, E., PELICICE, F.M. & SIMBERLOFF, D. 2016. Misguided strategy for mosquito control. Science. 351:675., and Ota et al. (2018)OTA, R.R., DEPRÁ, G.C., GRAÇA, W.J. & PAVANELLI, C.S. 2018. Peixes da planície de inundação do alto rio Paraná e áreas adjacentes: revised, annotated and updated. Neotrop Ichthyol. 16(2):e170094..

3. Data Analysis

The total taxonomic richness was assessed using species accumulation curves. Non-parametric Incidence-Based Estimators: Bootstrap (Smith & van Belle 1984SMITH, E.P. & VAN BELLE, G. 1984. Nonparametric estimation of species richness. Biometrics 40: 119-129.) and Chao 2 (Chao 1984CHAO, A. 1984. Non-parametric estimation of the number of classes in a population. Scand. J. Stat. 11: 265-270.), were used to obtain estimates of native species richness from Paranapanema River basin, considering the species presence/absence distribution in the subregions. For this analysis, we used the EstimateS 9.1 software (Colwell 2006COLWELL, R.K. 2006. EstimateS: estimate s biodiverty estimator software. Version 9.1. http://viceroy.eeb.uconn.edu/estimates/index.html. (último acesso em 11/10/2018)
http://viceroy.eeb.uconn.edu/estimates/i... ). For generating the map of Paranapanema River basin and their regions, the Quantum GIS 2.18 software was employed (QGIS Development Team 2018QGIS Development Team. 2018. QGIS Geographic Information System. Open Source Geospatial Foundation Project. Accessed at http://qgis.osgeo.org (último acesso em 10/09/2018)
http://qgis.osgeo.org... ).

Results

The compilation of 90 studies resulted in the identification of 10 orders, 40 families, 118 genera, and 225 species within the Paranapanema River basin. Of these, 165 species were identified as native, while 60 were non-native species introduced into the basin through several vectors (Table 2). Siluriformes (91 species) and Characiformes (83 species) represented the most species-rich orders, accounting together for 77% of all species from the basin. Cichliformes were the third species-rich order with 20 species found. The families with the highest number of species in the basin were Loricariidae (39 species), and Characidae (33 species), followed by Cichlidae (20 species), Anostomidae (16 species) and Pimelodidae (13 species).

Hypostomus was the richest genus with 16 identified species (four of which were non-native) distributed along the basin. Most species of this genus were present in the Tibagi River with 13 species, followed by Cinzas River (10 species), and finally Paranapanema River (Capivara Reservoir) and Pirapó River both with eight species. The next richest genera were Astyanax (eight species), Leporinus, and Crenicichla (both with six species each). Among the non-native species, the genus Cichla had five species, all introduced due to fish stocking for recreational fishing. There were no records of Cichla on the Upper Paranapanema River (Table 2).

The most common native species, widely distributed in the Paranapanema River basin, were Astyanax lacustris and Hypostomus ancistroides - present in 43 subregions - followed by Rhamdia quelen (34 subregions), Hoplias cf. malabaricus (33), Geophagus brasiliensis (30), Astyanax aff. fasciatus (29) and Steindachnerina insculpta (24). A comprehensive summarized list of species, with their current taxonomic status, are shown in Table 3.

In the Paranapema River basin, 22 species were classified as being threatened (Table 2), with the family Bryconidae having the highest number of threatened species in the basin. Brycon nattereri and Brycon orbignyanus are considered Critically Endangered in the state of São Paulo (Table 2). Brycon nattereri was found only in the Tibagi and Cinzas rivers (Lower Paranapanema), and Brycon orbignyanus was also found only in two tributaries - the Cinzas, and Ribeirão dos Veados rivers of the Middle Paranapanema. Salminus brasiliensis is considered Vulnerable in Brazil and state of Paraná (only in the Lower Paranapanema). Members of Pimelodidae, such as the migratory catfishes Steindachneridion scriptum and Zungaro jahu are also Endangered in the state of São Paulo, and Vulnerable in the state of Paraná. Other species that are Critically Endangered in at least one of the lists are Piaractus mesopotamicus (Serrasalmidae) and Crenicichla jupiaensis (Cichlidae), which were found only in the Cinzas River (Table 1).

The most widely distributed non-native species were Plagioscion squamosissimus, present in 17 subregions, and Oreochromis niloticus which was registered in 16 subregions in the three primary areas of the basin. In the lower area, the Tibagi River was the subregion with the greatest diversity of non-native species (29 species), followed by the Rosana Reservoir (19 species), Cinzas River (17 species), and the Capivara Reservoir (16 species). In the middle area, the non-native species were concentrated in Salto Grande (15 species), and Jurumirim reservoirs (15 species). In the Upper Paranapanema River, only four non-native species were recorded: Misgurnus anguillicaudatus, Cyprinus carpio, Satanoperca pappaterra and Poecilia vivipara.

When considering only the species native to the Paranapanema basin (165 species) which occurred in each of the 57 subregions, the accumulation curve tended to stabilize (Figure 2), but non-parametric estimators indicated that the total richness of native species to the basin is underestimated (Bootstrap = 182.29 ± 0.00, Chao-2 = 223.98 ± 25.43). Our compilation from the studies represents 74% (Chao-2) and 91% (Bootstrap) of the native species estimated for the basin.

The Lower Paranapanema was the region with the highest species richness (146 native and 51 non-native species) (Figure 3). Most of its richness was in the Tibagi River which presented 158 species, followed by Cinzas (114 species), Pirapó (76 species) and Congonhas (63 species) rivers respectively. Of these, 79 occurred only in the Lower Paranapanema as a medium to large sized native species including Brycon nattereri, Salminus brasiliensis, Megalonema platanum, Pimelodus paranaenses, Pinirampus pirinampu, Pseudoplatystoma corruscans, Zungaro jahu, and Pseudopimelodus mangurus.

The middle region presented 103 native and 27 non-native species, with 75 native species recorded to the Salto Grande Reservoir alone. Some of these were recorded only within the middle region, such as Characidium fasciatum, Leporellus pictus, and Odontostilbe avanhandava. In the Upper Paranapanema, 61 species (57 of which are native) were recorded (Figure 3), with the majority of them being small to medium size species, such as Characidium oiticicai, Isbrueckerichthys duseni and Phalloceros reisi. Most of the species in this region (45 species) were collected in headwater streams.

A majority of the investigated studies were performed within the lower region of the Paranapanema River (56 studies), comprising 61% of those reviewed. The Capivara Reservoir and its direct tributaries presented 32 studies, most of them concentrated in the Tibagi River (29 studies). The Rosana Reservoir and tributaries were the second most studied subregion (17 studies). In the Middle Paranapanema 20 studies were conducted, with the Jurumirim Reservoir and its tributaries (11 studies) being the most studied site. The Upper Paranapanema was the least investigated region (seven studies), five of which were species inventories, and two were new species descriptions for Astyanax biotae in 2004 and Neoplecostomus selenae in 2008.

Discussion

The number of species identified by our study (225) is significantly higher than reports conducted exclusively in reservoirs, which recorded 155 (Duke Energy 2008DUKE ENERGY, 2008. Peixes do rio Paranapanema. Horizonte Geográfico, 2ª Ed. São Paulo.) and 161 species (Pelicice et al. 2018PELICICE, F. M., AZEVEDO-SANTOS, V.M., ESGUÍCERO, A.L.H., AGOSTINHO, A.A. & ARCIFA, M.S. 2018. Fish diversity in the cascade of reservoirs along the Paranapanema River, southeast Brazil. Neotrop. Ichthyol. 16(2):e170150.) for the Paranapanema River, respectively. Here, we have used both basin-wide surveys (i.e., from reservoirs and fish ladders and free-flowing stretches including tributaries, streams, and marginal lagoons), as well as species descriptions to more comprehensively evaluate the species diversity of the region. The accumulation curve indicated that a majority of the native species (165) were represented and we estimate that the total richness would be between 182 and 223 species of native fish in the basin, a higher value than predicted by Pelicice et al. (2018)PELICICE, F. M., AZEVEDO-SANTOS, V.M., ESGUÍCERO, A.L.H., AGOSTINHO, A.A. & ARCIFA, M.S. 2018. Fish diversity in the cascade of reservoirs along the Paranapanema River, southeast Brazil. Neotrop. Ichthyol. 16(2):e170150. (125 to 132).

The most species-rich genus in this study, Hypostomus, is widely distributed in the rivers of the Paraná-Paraguay system (Weber 2003WEBER, C. (2003) Subfamily Hypostominae (Armored catfishes). In Check List of the Freshwater Fishes of South and Central America (Reis, R. E., Kullander, S. O. & Ferraris, C. J. Jr., eds), Porto Alegre: EDIPUCRS. p.351-372.). The armored catfish species of Hypostomus are known for living in clear running water on the rocky bottoms of mostly large South American rivers (Garavello & Garavello, 2004GARAVELLO, J. C., & GARAVELLO, J. P. 2004. Spatial distribution and interaction of four species of the catfish genus Hypostomus Lacépède with bottom of Rio São Francisco, Canindé do São Francisco, Sergipe, Brazil (Pisces, Loricariidae, Hypostominae). Braz. J. of Biol. 64(3B):103-141.). Within the genus, the species Hypostomus ancistroides is a common and widely distributed species, occurring throughout the Upper Paraná River system from where it was initially described (Weber 2003WEBER, C. (2003) Subfamily Hypostominae (Armored catfishes). In Check List of the Freshwater Fishes of South and Central America (Reis, R. E., Kullander, S. O. & Ferraris, C. J. Jr., eds), Porto Alegre: EDIPUCRS. p.351-372.). Astyanax lacustris is also widely distributed, and along with its congeners, is the most diversified of the Characidae, comprising more than a hundred species widely distributed and abundant in the Brazilian watersheds. This extensive distribution indicates that the genus probably has significant ecological importance and adaptive plasticity (Orsi et al. 2004ORSI, M. L., CARVALHO, E. D., & FORESTI, F. 2004. Biologia populacional de Astyanax altiparanae Garutti & Britski (Teleostei, Characidae) do médio rio Paranapanema, Paraná, Brasil. Rev. Bras. Zool. 21(2):207-218.).

The highest richness was recorded for the orders Siluriformes and Characiformes, as usually found in the Neotropical region (Lowe-McConnell 1999LOWE-McCONNELL, R.H. 1999. Estudos ecológicos de comunidades de peixes tropicais. Tradução de Anna Emília A. M. Vazzoler; Angelo Antonio Agostinho; Patrícia T. M. Cunningham São Paulo: EDUSP.). Cichliformes were the third most species-rich order in the basin, though mainly by the presence of non-native species. Among them, the genus Cichla, which was introduced to the basin in 1999 (Orsi & Agostinho 1999ORSI, M.L. & AGOSTINHO, A.A. 1999. Introdução de espécies de peixes por escapes acidentais de tanques de cultivo em rios da bacia do rio Paraná, Brasil. Ver. Bras. Zool. 16(2):557-560) to provide fish stocking for sport-angling, stands out with five introduced species. The species of this group benefit from lentic environments (Franco et al. 2018FRANCO, A.C.S., SANTOS, L.N., PETRY, A.C. & GARCÍA-BERTHOU, E. 2018. Abundance of invasive peacock bass increases with water residence time of reservoirs in southeastern Brazil. Hydrobiologia. 817:155-166.) provided by the reservoirs of the Paranapanema River. This scenario can be observed in other basins of the Upper Paraná River (Langeani et al. 2007LANGEANI, F., CASTRO, R.M.C., OYAKAWA, O.T., SHIBATTA, O.A., PAVANELLI, C.S. & CASATTI, L. 2007. Diversidade da ictiofauna do Alto Rio Paraná: composição atual e perspectivas futuras. Biota Neotrop. 7(3): 181-197 http://www.biotaneotropica.org.br/v7n3/pt/abstract?article+bn03407032007 (último acesso em 27/08/2018).
http://www.biotaneotropica.org.br/v7n3/p... ). Many non-native species are more abundant in lentic environments, especially those of the family Cichlidae (Langeani et al. 2007LANGEANI, F., CASTRO, R.M.C., OYAKAWA, O.T., SHIBATTA, O.A., PAVANELLI, C.S. & CASATTI, L. 2007. Diversidade da ictiofauna do Alto Rio Paraná: composição atual e perspectivas futuras. Biota Neotrop. 7(3): 181-197 http://www.biotaneotropica.org.br/v7n3/pt/abstract?article+bn03407032007 (último acesso em 27/08/2018).
http://www.biotaneotropica.org.br/v7n3/p... , Franco et al. 2018FRANCO, A.C.S., SANTOS, L.N., PETRY, A.C. & GARCÍA-BERTHOU, E. 2018. Abundance of invasive peacock bass increases with water residence time of reservoirs in southeastern Brazil. Hydrobiologia. 817:155-166.). Regarding non-native fishes, there still appears to be no consensus on the exact number of species, with previous studies having reported 47 (Garcia et al. 2018GARCIA, D. A. Z., BRITTON, J. R., VIDOTTO-MAGNONI, A. P., & ORSI, M. L. 2018. Introductions of non-native fishes into a heavily modified river: rates, patterns and management issues in the Paranapanema River (Upper Paraná ecoregion, Brazil). Biol. Inv. 20(5): 1229-1241.), and 50 (Pelicice et al. 2018PELICICE, F. M., AZEVEDO-SANTOS, V.M., ESGUÍCERO, A.L.H., AGOSTINHO, A.A. & ARCIFA, M.S. 2018. Fish diversity in the cascade of reservoirs along the Paranapanema River, southeast Brazil. Neotrop. Ichthyol. 16(2):e170150.) non-native species in the basin.

In this study, 60 non-native fish species were registered in the Paranapanema River basin. In addition to the actual number of introduced species, the Paranapanema River basin can be considered the most invaded of the Upper Paraná River basin (Ortega et al. 2015ORTEGA, J.C.G., JÚLIO JR, H.F., GOMES, L.C. & AGOSTINHO, A.A. 2015. Fish farming as the main driver of fish introductions in Neotropical reservoirs. Hydrobiologia. 746:147-158., Garcia et al. 2018GARCIA, D. A. Z., BRITTON, J. R., VIDOTTO-MAGNONI, A. P., & ORSI, M. L. 2018. Introductions of non-native fishes into a heavily modified river: rates, patterns and management issues in the Paranapanema River (Upper Paraná ecoregion, Brazil). Biol. Inv. 20(5): 1229-1241.). Among the non-native species, 30 species occurred within the Paranapanema River (and Upper Paraná) after the flooding of the Sete Quedas Falls (Júlio Jr. et al. 2009JÚLIO JÚNIOR, H.F., DEI TÓS, C., AGOSTINHO, A.A., PAVANELLI, C.S. 2009. A massive invasion of fish species after eliminating a natural barrier in the upper rio Paraná basin. Neotrop. Ichthyol. 7(4):709-718.), 16 species were introduced for restocking, nine species due to the aquarium trade, seven by escapes from fish farms, five by live-bait fish used in sport angling, and one for biological control. Among the most distributed non-native species in the basin, P. squamosissimus was introduced by stocking, while O. niloticus often escapes from fish farms (Ortega et al. 2015ORTEGA, J.C.G., JÚLIO JR, H.F., GOMES, L.C. & AGOSTINHO, A.A. 2015. Fish farming as the main driver of fish introductions in Neotropical reservoirs. Hydrobiologia. 746:147-158.). The introduction of non-native species, compounded by other anthropic actions, threaten the richness of fish species present in this critical basin (Pelicice & Agostinho 2009PELICICE, F.M. & AGOSTINHO, A.A. 2009. Fish fauna destruction after the introduction of a non-native predator (Cichla kelberi) in a Neotropical reservoir. Biol. Invasions. 11:1789-1801., Garcia et al. 2018GARCIA, D. A. Z., BRITTON, J. R., VIDOTTO-MAGNONI, A. P., & ORSI, M. L. 2018. Introductions of non-native fishes into a heavily modified river: rates, patterns and management issues in the Paranapanema River (Upper Paraná ecoregion, Brazil). Biol. Inv. 20(5): 1229-1241.).

The occurrence of several species with some degree of threat and restricted distribution indicates that biodiversity conservation in the Paranapanema River is a highly relevant issue. Past studies have shown Bryconidae populations are in decline, with few occurrences in the basin (ICMBio 2018ICMBio. Instituto Chico Mendes de Conservação da Biodiversidade. 2018. Livro Vermelho da Fauna Brasileira Ameaçada de Extinção: Volume VI - Peixes. In: Instituto Chico Mendes de Conservação da Biodiversidade (Org.). Livro Vermelho da Fauna Brasileira Ameaçada de Extinção. Brasília: ICMBio. 1232p.). Meanwhile, Brycon nattereri and B. orgbignyanus are critically endangered in the state of São Paulo but occur in the rivers Tibagi, Cinzas, and Ribeirão dos Veados (Mikich & Bérnils 2004MIKICH, S. B., & BÉRNILS, R. S. 2004. Livro vermelho da fauna ameaçada no Estado do Paraná. Instituto ambiental do Paraná., Bressan et al. 2009BRESSAN, P.M., KIERULFF, M.C.M. & SUGIEDA, A.M. 2009. Fauna ameaçada de extinção no Estado de São Paulo. São Paulo: Fundação Parque Zoológico de São Paulo, Secretaria do Meio Ambiente., ALESP 2014ASSEMBLEIA LEGISLATIVA DO ESTADO DE SÃO PAULO (ALESP). 2014. Decreto Nº 60.133, de 7 de fevereiro de 2014: As espécies da fauna silvestre ameaçadas de extinção, as quase ameaçadas e as deficientes de dados para avaliação no Estado de São Paulo e dá providências correlatas.). Also, the occurrence of Piaractus mesopotamicus and Crenicichla jupiaensis in the Cinzas River highlights the importance of dam-free tributaries for the maintenance of native species in the basin (Nunes et al. 2015NUNES, D.M.F., MAGALHÃES, A.L.B., WEBER, A.A., GOMES, R.L.Z., NORMANDO, F.T., SANTIAGO, K.B., RIZZO, E & BAZZOLI, N., 2015. Influence of a large dam and importance of an undammed tributary on the reproductive ecology of the threatened fish matrinxã Brycon orthotaenia Günther, 1864 (Characiformes: Bryconidae) in southeastern Brazil. Neotrop. Ichthyol. 13(2):317-324., Marques et al. 2018MARQUES, H., DIAS, J.H.P., PERBICHE-NEVES, G., KASHIWAQUI, E.A.L. & RAMOS, I.P. 2018. Importance of dam-free tributaries for conserving fish biodiversity in Neotropical reservoirs. Biol. Conserv. 224:347-354.). Salminus brasiliensis, Steindachneridion scriptum, and Zungaru jahu - three long distances migratory species - have a low occurrence within this study. This decline in migratory species is demonstrated in several previous works (Okada et al. 2005OKADA, E.K., AGOSTINHO, A.A., & GOMES, L.C. 2005. "Spatial and temporal gradients in artisanal fisheries of a large Neotropical reservoir, the Itaipu Reservoir, Brazil." Can. J. Fis. Aq. Sci. 62(3): 714-724., Godinho & Kynard 2008GODINHO, A. L. & KYNARD, B. 2008. Migratory fishes of Brazil: life history and fish passage needs. River. Res. Applic. 25:702-712., Pelicice & Agostinho 2008PELICICE, F.M. & AGOSTINHO, A.A. 2008. Fish-passage facilities as ecological traps in large Neotropical rivers. Conserv. Biol. 1(22):180-88.; Pompeu et al. 2012POMPEU, P.S., AGOSTINHO, A.A. & PELICICE, F.M. 2012. Existing and future challenges: the concept of successful fish passage in South America. River Res. Appl. 28(4):504-12., Orsi et al. 2016ORSI, M.L., ALMEIDA, F.S., SWARÇA, A.C., CLARO-GARCÍA, A., VIANNA, N.C., GARCIA, D.A.Z. & BIALETZKI, A. 2016. Ovos, larvas e juvenis dos peixes da Bacia do Rio Paranapanema uma avaliação para a conservação. Assis, SP: Triunfal Gráfica e Editora, Duke Energy.). The Cascade reservoir system along the Paranapanema River interrupts long-distance migration and creates unsuitable environments for migratory fish resulting from the presence of lentic areas and flow regulation (Agostinho et al. 2003AGOSTINHO, A.A., GOMES, L.C., SUZUKI, H.I., & JÚLIO JR., H.F. 2003. Migratory fishes of the Upper Paraná River basin, Brazil. In: Migratory Fishes of South America: Biology, Fisheries and Conservation Status (J. Carolsfeld, B. Harvey, C. Ross & A. Baer, eds.). Victoria, World Fisheries Trust, the World Bank and the International Development Research Centre. 19-99., Agostinho et al. 2008AGOSTINHO, A.A., PELICICE, F.M. & GOMES, L.C. 2008. Dams and the fish fauna of the Neotropical region: impacts and management related to diversity and fisheries. Braz. J. Biol. 68(4):1119-1132., Pelicice et al. 2018PELICICE, F. M., AZEVEDO-SANTOS, V.M., ESGUÍCERO, A.L.H., AGOSTINHO, A.A. & ARCIFA, M.S. 2018. Fish diversity in the cascade of reservoirs along the Paranapanema River, southeast Brazil. Neotrop. Ichthyol. 16(2):e170150.). Among the species with restricted distribution, we found several small species that inhabit small streams of headwaters, namely Characidium fasciatum (Carvalho et al. 2005aCARVALHO, E.D., MARCUS, L.R., FORESTI, E. & SILVA, V.E.B. 2005a. Fish assemblage attributes in a small oxbow lake (Upper Paraná river basin, São Paulo state, Brazil): species composition, diversity and ontogenetic stage. Acta Limnol. Bras. 17(1):45-56.), Planaltina spp. (Brandão et al. 2009BRANDÃO, H., VIDOTTO-MAGNONI, A.P., RAMOS, I.P. & CARVALHO, E.D. 2009. Assessment of the ichthyofauna in sites under the influence of Salto Grande Reservoir (Middle Paranapanema River, SP/PR, Brazil). Acta Limnol. Bras. 21(4):451-463., Deprá et al. 2018DEPRÁ, G.C., GRAÇA, W.J.D., PAVANELLI, C.S., AVELINO, G.S. & OLIVEIRA, C. 2018. Molecular phylogeny of Planaltina Böhlke (Characidae: Stevardiinae) and comments on the definition and geographic distribution of the genus, with description of a new species. PLoS ONE. 13(5): e0196291.), Characidium oiticicai (Cetra et al. 2012CETRA, M., BARRELLA, W.A., LANGEANI NETO, F., MARTINS, A.G., MELLO, B.J. & ALMEIDA, R.S. 2012. Fish fauna of headwater streams that cross the Atlantic Forest of south São Paulo state. Check List 8(3):421-425.), Metynnis mola, Hyphessobrycon bifasciatus (Arcifa & Esguícero 2012ARCIFA, M.S. & ESGUÍCERO, A.L.H. 2012. The fish fauna in the fish passage at the Ourinhos Dam, Paranapanema River. Neotrop. Ichthyol. 10(4):715-722.), Isbrueckerichthys alipionis (Martins & Barrella 2008MARTINS, A.G. & BARRELLA, W. 2008. Peixes da Serra de Paranapiacaba. REB. 1(1):16-35.), Paraloricaria vetula (Barrella & Petrere Jr. 2003BARRELLA, W. & PETRERE JR, M. 2003. Fish community alterations due to pollution and damming in Tietê and Paranapanema rivers (Brazil). River Res. Appl. 19(1):59-76.), Neoplecostomus botucatu (Roxo et al. 2012ROXO, F.F., OLIVEIRA, C. & ZAWDZKI, C.H. 2012. Three new species of Neoplecostomus (Teleostei: Siluriformes: Loricariidae) from the Upper Rio Paraná basin of southeastern Brazil. Zootaxa. 3233:1-21.), and Cnesterodon hypselurus (Silva et al. 2015SILVA, J.F.M, JEREP, F.C., & BENNEMANN, S.T. 2015. New record and distribution extension of the endangered freshwater fish Cnesterodon hypselurus (Cyprinodontiformes: Poeciliidae) in the upper Paraná River basin, Brazil. Check List. 11(6):1811.). These species present a high degree of endemism and restricted geographic distribution, while having no commercial value and being highly dependent on riparian vegetation for food, reproduction, and shelter. They are more likely to have their conservation threatened because theses species tend to pass their entire life cycles in geographically restricted areas (Castro and Menezes, 1998CASTRO, R.M.C. & MENEZES, N.A. 1998. Estudo diagnóstico da diversidade de peixes do Estado de São Paulo. In Biodiversidade do Estado de São Paulo, Brasil: Síntese do conhecimento ao final do século XX, vertebrados (R.M.C. Castro, ed.). WinnerGraph, São Paulo, p .1-13., Castro et al. 2003CASTRO, R.M.C., CASATTI, L., SANTOS, H.F., FERREIRA, K.M., RIBEIRO, A.C., BENINE, R.C., DARDIS, G.Z.P., MELO, A.L.A., STOPIGLIA, R., ABREU, T.X., BOCKMANN, F.A., CARVALHO, M., GIBRAN, F.Z. & LIMA, F.C.T. 2003. Estrutura e composição da ictiofauna de riachos do Rio Paranapanema, sudeste e sul do Brasil. Biota Neotrop. 3(1): 1-31 http://www.biotaneotropica.org.br/v3n1/pt/abstract?article+BN01703012003 (último acesso 09/09/2018)
http://www.biotaneotropica.org.br/v3n1/p... ).

The Tibagi River basin is the most studied region of the Paranapanema River. Together with the Cinzas River, the Tibagi assists in the maintenance of species of the Paranapanema River (Shibatta et al. 2002SHIBATTA, O.A., ORSI, M.L., BENNEMANN, S.T. & SILVA-SOUZA, Â.T. 2002. Diversidade e distribuição de peixes na bacia do rio Tibagi. In: A bacia do rio Tibagi (M.E. Medri, E. Bianchini, O.A. Shibatta & J. A. Pimenta, eds.). Londrina, p.403-423., Hoffmann et al. 2005HOFFMANN, A.C., ORSI, M.L. & SHIBATTA, O.A. 2005. Diversidade de peixes do reservatório da UHE Escola Engenharia Mackenzie (Capivara), rio Paranapanema, bacia do alto rio Paraná, Brasil, e a importância dos grandes tributários na sua manutenção. Iheringia Sér. Zool. 95(3):319-325., Shibatta et al. 2007SHIBATTA, O.A., GEALH, A.M. & BENNEMANN, S.T. 2007. Ictiofauna dos trechos alto e médio da bacia do rio Tibagi, Paraná, Brasil. Biota Neotrop. 7(2) http://www.biotaneotropica.org.br/v7n2/pt/abstract?article+bn02107022007 (último acesso 08/09/2018).
http://www.biotaneotropica.org.br/v7n2/p... ). However, it is noteworthy that studies of universities near these sub-basins, such as Universidade Estadual de Londrina, and Universidade Estadual de Maringá have likely contributed to the highest number of species survey data in these rivers. In the Middle Paranapanema, studies carried out by the Universidade Estadual Paulista within the Jurumirim and Chavantes reservoirs have been especially valuable. Conversely, the Upper Paranapanema region was investigated to a lesser extent. The region is characterized by numerous streams, which are underexplored and serve as shelters for smaller species (Langeani et al. 2007LANGEANI, F., CASTRO, R.M.C., OYAKAWA, O.T., SHIBATTA, O.A., PAVANELLI, C.S. & CASATTI, L. 2007. Diversidade da ictiofauna do Alto Rio Paraná: composição atual e perspectivas futuras. Biota Neotrop. 7(3): 181-197 http://www.biotaneotropica.org.br/v7n3/pt/abstract?article+bn03407032007 (último acesso em 27/08/2018).
http://www.biotaneotropica.org.br/v7n3/p... ). The previous description of new species in the Upper Paranapanema River (Castro & Vari, 2004CASTRO, R.M.C., & VARI, R.P. 2004. Astyanax biotae, a new species of stream fish from the Rio Paranapanema basin, upper Rio Parana system, southeastern Brazil (Ostariophysi: Characiformes: Characidae) Proc. Biol. Soc. Wash. 117(3):330-338., Zawadzki et al. 2008ZAWADZKI, C.H., PAVANELLI, C.S & LANGEANI, F. 2008. Neoplecostomus (Teleostei: Loricariidae) from the upper Rio Paraná basin, Brazil, with description of three new species. Zootaxa 1757:31-48.), coupled with a general lack of studies for this region, suggests that there is still great potential for new descriptions in the headwaters of the tributaries (Buckup et al. 2007BUCKUP, P.A., MENEZES, N.A., & GHAZZI, M.S.A. 2007. Catálogo das espécies de peixes de água doce do Brasil (Vol. 1). Rio de Janeiro: Museu Nacional. p.1-195., Langeani et al. 2007LANGEANI, F., CASTRO, R.M.C., OYAKAWA, O.T., SHIBATTA, O.A., PAVANELLI, C.S. & CASATTI, L. 2007. Diversidade da ictiofauna do Alto Rio Paraná: composição atual e perspectivas futuras. Biota Neotrop. 7(3): 181-197 http://www.biotaneotropica.org.br/v7n3/pt/abstract?article+bn03407032007 (último acesso em 27/08/2018).
http://www.biotaneotropica.org.br/v7n3/p... ). More importantly, there are also species that have a threatened conservation status, such as Isbrueckerichthys duseni, as well as the high percentage of species for which there is little to no scientific knowledge (Castro et al. 2003CASTRO, R.M.C., CASATTI, L., SANTOS, H.F., FERREIRA, K.M., RIBEIRO, A.C., BENINE, R.C., DARDIS, G.Z.P., MELO, A.L.A., STOPIGLIA, R., ABREU, T.X., BOCKMANN, F.A., CARVALHO, M., GIBRAN, F.Z. & LIMA, F.C.T. 2003. Estrutura e composição da ictiofauna de riachos do Rio Paranapanema, sudeste e sul do Brasil. Biota Neotrop. 3(1): 1-31 http://www.biotaneotropica.org.br/v3n1/pt/abstract?article+BN01703012003 (último acesso 09/09/2018)
http://www.biotaneotropica.org.br/v3n1/p... ), reinforcing Castro & Menezes (1998)CASTRO, R.M.C. & MENEZES, N.A. 1998. Estudo diagnóstico da diversidade de peixes do Estado de São Paulo. In Biodiversidade do Estado de São Paulo, Brasil: Síntese do conhecimento ao final do século XX, vertebrados (R.M.C. Castro, ed.). WinnerGraph, São Paulo, p .1-13. recommendation to prioritize scientific exploration of streams and headwaters in these regions.

Despite the significant richness of fish species known, the region of the Paranapanema River has the highest population density in Brazil (ANA 2016AGENCIA NACIONAL DE ÁGUAS (ANA), 2016. Plano Integrado de Recursos Hídricos da Unidade de Gestão de Recursos Hídricos Paranapanema. Agencia Nacional das Águas - Brasília.) as a result of electricity production, agribusiness, industry, and water supply (Novaes & Carvalho 2013NOVAES, J.L.C. & CARVALHO, E.D. 2013. Analysis of artisanal fisheries in two reservoirs of the upper Paraná River basin (Southeastern Brazil). Neotrop. Ichthyol. 11(2):403-412.) occurring in the area. Additionally, it is also used as a source of livelihood for riverside communities (Agostinho et al. 2007bAGOSTINHO, A.A., PELICICE, F.M., PETRY, A.C., GOMES, L.C. & JÚLIO JÚNIOR, H.F. 2007b. Fish diversity in the upper Paraná River basin: habitats, fisheries, management and conservation. Aquat. Ecosyst. Health Manag. 10(2):174-86., 2016AGOSTINHO, A.A., GOMES, L.C., SANTOS, N.C.L., ORTEGA, J.C.G. & PELICICE, F.M. 2016. Fish assemblages in Neotropical reservoirs: colonization patterns, impacts and management. Fish Res. 173(1):26-36.). The conservation of fish fauna is one of the greatest challenges faced today (Cerqueira & Smith 2015CERQUEIRA, V.L.A. & SMITH, W.S. 2015. Composição ictiofaunística do Rio Turvo, Pilar do Sul, São Paulo, Brasil. J. Health Sci. Inst. 33(1):7-14.). It must be emphasized that, despite the importance of developing the country through the exploitation basin's resources, maintenance of its biodiversity is just as crucial.

Tributaries where threatened fishes occur should remain un-dammed (e.g., Tibagi, Cinzas, Pirapó, and Congonhas rivers) to protect such species. Many of these endangered species migrate from long distances and present population decline mainly due to the damming of the mainstem (Agostinho et al 2003AGOSTINHO, A.A., GOMES, L.C., SUZUKI, H.I., & JÚLIO JR., H.F. 2003. Migratory fishes of the Upper Paraná River basin, Brazil. In: Migratory Fishes of South America: Biology, Fisheries and Conservation Status (J. Carolsfeld, B. Harvey, C. Ross & A. Baer, eds.). Victoria, World Fisheries Trust, the World Bank and the International Development Research Centre. 19-99.). Furthermore, the number of non-native fish species in the Paranapanema River basin is alarming. Urgent actions should be taken to promote awareness and educate the population about the environmental, social, and economic risks caused by these invasive species.

Conservation actions must be carried out by all who depend on the resources of the Paranapanema River Basin, including the appropriate use of water, reduction of fertilizers, and agrochemicals, since the preservation of sources, headwaters, tributaries, and the riparian vegetation relied upon by various species of aquatic fauna. Our findings may be used to support management actions and conservation strategies, and to identify regions within the basin that require better inventories or conservation status updates of its species.

Acknowledgments

To the agreement P&D/ANEEL/CTG: Development and application of an innovative program for the conservation and recovery of the Paranapanema River fish restocking. Project No. 11218 UEL/FAUEL; LRJ and DAZG postdoctoral scholarship and financial support. The authors thank UNIFIO and UEL (Programa de Pós-Graduação em Ciências Biológicas, BAV/CCB). FCJ is supported by CNPq (process 453850/2014-6); APVM and DAZG supported by CNPq (process 455580/2014-6).

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