Abstract:

This work is the most comprehensive survey of the Laranjinha River´s fishes, a tributary of the Cinzas River, Paranapanema River basin. Throughout its course, there is only a low-height dam, including a transposition system located 98 km from its mouth. The sampling was carried out in nine locations, from the source to the mouth, with six field incursions in each location, using different fishing gear. A total of 11,924 fish were collected, distributed in seven orders, 27 families, and 100 species. The most representative order in the number of species was Siluriformes, followed by Characiformes. As for the families, Loricariidae comprised 21% and Characidae 14% of species richness. Phalloceros harpagos was the species with the highest absolute abundance, representing 11.3% of the total, followed by Hypostomus ancistroides with 9.8%. However, considering the average abundance and frequency of occurrence, Hypostomus ancistroides was the most abundant species, followed by Hypostomus cf. paulinus, Psalidodon aff. paranae and Phalloceros harpagos. Among the collected species, the Apteronotus acidops, Brycon orbygnianus, Brycon nattereri, Crenicichla jupiaensis, and Rhinelepis aspera were classified as endangered on the most recent IUCN Red List. Also, from the total sampled fish, 9.8% are considered non-native species. Among the native species recorded, 10 species are large migratory species, which indicates that the Laranjinha River is a route for spawning and maintenance of species diversity in the middle Paranapanema River. Therefore, the Laranjinha River is a heritage of fish diversity and deserves special attention in its preservation.

Keywords:
Checklist; fish diversity; freshwater; upper Paraná River

Resumo:

Este é o levantamento mais abrangente de peixes do rio Laranjinha, um afluente do rio das Cinzas, bacia do rio Paranapanema. Ao longo de sua rota, existe apenas uma pequena barragem com um sistema de transposição localizado 98 km de sua nascente. A amostragem foi realizada em nove locais, desde a nascente até a foz, com seis incursões de campo em cada local, com o auxílio de diferentes artes de pesca. Foram coletados 11.924 indivíduos, distribuídos em sete ordens, 27 famílias e 100 espécies. A ordem mais representativa foi Siluriformes, seguida por Characiformes. Quanto às famílias, Loricariidae compôs 21% e Characidae 14% da riqueza de espécies. Phalloceros harpagos foi a espécie com maior abundância absoluta, representando 11,3% do total, seguida por Hypostomus ancistroides, com 9,8%. No entanto, considerando a abundância média e a frequência de ocorrência, Hypostomus ancistroides foi a espécie mais abundante, seguida por Hypostomus cf. paulinus, Psalidodon aff. paranae e Phalloceros harpagos. Entre as espécies coletadas, Apteronotus acidops, Brycon orbygnianus, Brycon nattereri, Crenicichla jupiaensis e Rhinelepis aspera estão listadas em categorias de ameaça na Lista Vermelha da IUCN mais recente. Além disso, do total de indivíduos amostrados, 9,8% são considerados espécies não nativas. Entre as espécies nativas registradas, 10 espécies são migratórias de grande porte, o que indica que o rio Laranjinha é uma rota de desova e manutenção da diversidade de espécies no médio rio Paranapanema. Portanto, o rio Laranjinha é um patrimônio da diversidade de peixes e merece atenção especial em sua preservação.

Palavras-chave:
Água doce; alto rio Paraná; diversidade de peixes; lista de espécies

Introduction

In the last few decades, human actions have caused numerous environmental changes, which emphasizes the need to know the local biodiversity, in order to reduce harmful activities. To this extend, the creation of inventories contribute to the discovery and description of new species before their extinction, also contributing to the creation of new records, to the knowledge about geographical distribution, the documentation of non-native species, the defininition of biogeographic patterns, and the establishment of suitable conservation strategies (Costello et al. 2011COSTELLO, D.M., TIEGS, S.D., & LAMBERTI, G.A. 2011. Do non-native earthworms in Southeast Alaska use streams as invasional corridors in watersheds harvested for timber?. Biological Invasions. 13(1):177-187., Ota et al. 2015OTA, R.R., DA GRAÇA, W.J., & PAVANELLI, C.S. 2015. Neotropical Siluriformes as a model for insights on determining biodiversity of animal groups. PloS one. 10(7):e0132913., Frota et al. 2019FROTA, A., OLIVEIRA, R.C.D., BENEDITO, E. & GRAÇA, W.J. 2019. Ichthyofauna of headwater streams from the rio Ribeira de Iguape basin, at the boundaries of the Ponta Grossa Arch, Paraná, Brazil. Biota Neotropica. 19(1):e20180666.).

The fishes of the upper Paraná River basin are the most studied in Brazil. The basin has more than 310 fish 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 Neotropica. 7(3):1-17.), a number currently outdated, considering new records and the recent discovery of new species (e.g. Frota et al. 2016FROTA, A., DEPRÁ, G.D.C., PETENUCCI, L.M. & GRAÇA, W.J. 2016. Inventory of the fish fauna from Ivaí River basin, Paraná State, Brazil. Biota Neotropica. 16(3): e20150151., Froehlich et al. 2017FROEHLICH, O., CAVALLARO, M., SABINO, J., SÚAREZ, Y.R., & VILELA, M.J.A. 2017. Checklist da ictiofauna do estado de Mato Grosso do Sul, Brasil. Iheringia, Série Zoologia. 107: e2017151., Cavalli et al. 2018CAVALLI, D., FROTA, A., LIRA, A.D., GUBIANI, É.A., MARGARIDO, V.P. & GRAÇA, W.J.D. 2018. Update on the ichthyofauna of the Piquiri River basin, Paraná, Brazil: a conservation priority area. Biota Neotropica. 18(2):e20170350., Ota et al. 2018OTA, R.R., DEPRÁ, G.D.C., GRAÇA, W.J.D. & PAVANELLI, C.S. 2018. Peixes da planície de inundação do alto rio Paraná e áreas adjacentes: revised, annotated and updated. Neotropical Ichthyology. 16(2):e170094[1]- e170094[111]., Jarduli et al. 2020JARDULI, L. R., GARCIA, D. A. Z., VIDOTTO-MAGNONI, A. P., CASIMIRO, A. C. R., VIANNA, N. C., ALMEIDA, F. S. D., JEREP, F.C. & ORSI, M. L. 2020. Fish fauna from the Paranapanema River basin, Brazil. Biota Neotropica. 20(1).). The Paranapanema River, a major tributary of the upper Paraná River, is currently fragmented by several hydroelectric dams (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 Limnologica Brasiliensia. 18(4):377-388.), and therefore, its dam-free tributaries are of great importance for the maintenance of fish species (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, Série Zoológica. 95(3):319-325., Silva et al. 2017SILVA, J.C., ROSA, R.R., GALDIOLI, E.M., SOARES, C.M., DOMINGUES, W.M., VERÍSSIMO, S. & BIALETZKI, A. 2017. Importance of dam-free stretches for fish reproduction: the last remnant in the Upper Paraná River. Acta Limnologica Brasiliensia, 29:e16., Galindo et al. 2019GALINDO, B.A., FERREIRA, D.G., APOLINÁRIO-SILVA, C., TERRA, M.C., APRÍGIO, N.G., OTA, R.R., Ohara, W.M., ALMEIDA, F.S & SOFIA, S.H. 2019. Genetic diversity and population structure of Brycon nattereri (Characiformes: Bryconidae): a Neotropical fish under threat of extinction. Neotropical Ichthyology. 17(1):e180071., Lansac-Tôha et al. 2019LANSAC-TÔHA, F.M., HEINO, J., QUIRINO, B.A., MORESCO, G.A., PELÁEZ, O., MEIRA, B.R., RODRIGUES, L.C., JATI, S., LANSAC-TÔHA, F.A. & VELHO, L. F. M. 2019. Differently dispersing organism groups show contrasting beta diversity patterns in a dammed subtropical river basin. Science of The Total Environment, 691, 1271-1281.). Besides, the Cinzas River is an important tributary of the Paranapanema River basin, which is the main watercourse of the region known as “Norte Pioneiro” (Pioneer North) of the Paraná state, and it is essential for maintaining ichthyofauna biodiversity of the Capivara reservoir (Vianna & Nogueira 2008VIANNA, N.C. & NOGUEIRA, M.G. 2008. Ichthyoplankton and limnological factors in the Cinzas River - an alternative spawning site for fishes in the middle Paranapanema River basin, Brazil. Acta Limnologica Brasiliensia. 20:139-151., Orsi 2010ORSI, M.L. 2010. Estratégias reprodutivas de peixes da Região média-baixa do Rio Paranapanema, Reservatório de Capivara. São Paulo. Blucher Acadêmico. p.115.).

Fish inventories were carried out in the Paranapanema River tributaries, including the Cinzas, Jaguariaíva and Tibagi rivers (e.g., Shibatta et al. 2002SHIBATTA, O.A., ORSI, M.L., BENNEMANN, S.T. & SILVA-SOUZA, A.T. 2002. Diversidade e distribuição de peixes na bacia do rio Tibagi; p.403-423, in: MEDRI, M.E., BIANCHINI, E., SHIBATTA, O.A. & PIMENTA. J.A. A bacia do rio Tibagi. Londrina., 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 Neotropica. 3(1):1-31., Cetra et al. 2012CETRA, M., BARRELLA, W., NETO, F.L., 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., Cionek et al. 2012CIONEK, V.M., SACRAMENTO, P.A., ZANATTA, N., OTA, R.P., CORBETTA, D.F. & BENEDITO, E. 2012. Fishes from first order streams of lower Paranapanema and Ivaí rivers, upper Paraná River basin, Paraná, Brazil. Check List. 8(6):1158-1162, Costa et al. 2013COSTA, A.D.A., FERREIRA, D.G., SILVA, W.F., ZANATTA, A.S., SHIBATTA, O.A., & GALINDO, B.A. 2013. Fishes (Osteichthyes: Actinopterygii) from the Penacho stream, upper Paraná River basin, Paraná State, Brazil. Check List. 9(3):519-523., 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, Série Zoológica. 95(3):319-325., Cetra et al. 2016CETRA, M., MATTOX, G.M.T., FERREIRA, F.C., GUINATO, R.B., SILVA, F.V. & PEDROSA, M. 2016. Headwater stream fish fauna from the Upper Paranapanema River basin. Biota Neotropica. 16(3): e20150145., Frantine-Silva et al. 2015FRANTINE-SILVA, W., FERREIRA, D.G., NASCIMENTO, R.H.C., FRACASSO, J.F., CONTE, J.E., RAMOS, F.P., CARVALHO, S. & GALINDO, B.A. 2015. Genetic analysis of five sedentary fish species in middle Laranjinha River (upper Paraná River basin): A case study. Genetics and Molecular Research. 14(4):18637-18649., Almeida et al. 2018ALMEIDA, F.S., FRANTINE-SILVA, W., LIMA, S.C., GARCIA, D.A.Z. & ORSI, M.L. 2018. DNA barcoding as a useful tool for identifying non-native species of freshwater ichthyoplankton in the neotropics. Hydrobiologia. 817(1):111-19., Jerep & Shibatta 2017JEREP, F.C. & SHIBATTA, O.A. 2017. A new species of Bryconamericus (Characidae: Stevardiinae: Diapomini) from the upper rio Paraná basin, Brazil. Neotropical Ichthyology. 15(3):e170028., Claro-García et al. 2018CLARO-GARCÍA, A., ASSEGA, F.M. & SHIBATTA, O.A. 2018. Diversity and distribution of ichthyofauna in streams of the middle and lower Tibagi river basin, Paraná, Brazil. Check List. 14:43., Frota et al. 2020FROTA, A., OTA, R.R., DEPRÁ, G.C., GANASSIN, M.J.M & GRAÇA, W.J. 2020. A new inventory for fishes of headwater streams from the rio das Cinzas and rio Itararé basins, rio Paranapanema system, Paraná, Brazil. Biota Neotropica. 20(1): e20190833., Jarduli et al. 2020JARDULI, L. R., GARCIA, D. A. Z., VIDOTTO-MAGNONI, A. P., CASIMIRO, A. C. R., VIANNA, N. C., ALMEIDA, F. S. D., JEREP, F.C. & ORSI, M. L. 2020. Fish fauna from the Paranapanema River basin, Brazil. Biota Neotropica. 20(1)., Garcia et al. 2020GARCIA, T.D., OTA, R.R., FERREIRA, D.G., NASCIMENTO, R.H., GALINDO, B.A., PEREIRA, L.S., & ZANATTA, A.S. 2020. Distribution of Siluriformes in a river under the influence of a small hydroelectric power plant of the Paraná River Basin, Brazil. Iheringia. Série Zoologia. 110: e2020005.). However, a comprehensive checklist of the Laranjinha River ichthyofauna has not been published yet, except for a small streams (e.g., Costa et al. 2013COSTA, A.D.A., FERREIRA, D.G., SILVA, W.F., ZANATTA, A.S., SHIBATTA, O.A., & GALINDO, B.A. 2013. Fishes (Osteichthyes: Actinopterygii) from the Penacho stream, upper Paraná River basin, Paraná State, Brazil. Check List. 9(3):519-523.), and the scientific knowledge of its fish species remains unknown. Furthermore, projects of Small Hydropower Plants (SHPs) are being developed, which represents a potential threat to the species of this river (Galindo et al. 2019GALINDO, B.A., FERREIRA, D.G., APOLINÁRIO-SILVA, C., TERRA, M.C., APRÍGIO, N.G., OTA, R.R., Ohara, W.M., ALMEIDA, F.S & SOFIA, S.H. 2019. Genetic diversity and population structure of Brycon nattereri (Characiformes: Bryconidae): a Neotropical fish under threat of extinction. Neotropical Ichthyology. 17(1):e180071.). Thus, this study aimed to provide the first inventory of the Laranjinha River fish fauna.

Material and Methods

Study area

The Laranjinha River is entirely situated in the northeastern portion of the state of Paraná, and it is the main tributary of the left bank of the Cinzas River, which pours to the left bank of the middle Paranapanema River (Figure 1 and 2). The headwater is in the municipality of Ventania (24°14’43.43”S; 50°14’32.78”W), at 984 m of altitude, and the mouth is situated 4 km from the town of Itambaracá (23°01’03.51”S; 50°24’22.68”W), at 348 m of altitude. The Laranjinha River, with its meanders, extends through 350 km long, and it is situated in the sedimentary basin of the state of Paraná, with its source and mouth in the second and third plateaus, respectively (Santos et al. 2006SANTOS, L.J.C., OKA-FIORI, C., CANALI, N.E., FIORI, A.P., SILVEIRA, C.T.D., SILVA, J.M.F.D. & ROSS, J.L.S. 2006. Mapeamento geomorfológico do Estado do Paraná. Revista Brasileira de Geomorfologia. 7:03-12.). Between the years 1956 and 1960, a Small Hydropower Plant (SHP) was built 98 km from the mouth of the river. This dam never went into operation, and in 2006, a fish pass system was built in it (Schwartz 2006SCHWARTZ, W. 2006. Meio Ambiente Finalmente, a escada de peixes no Laranjinha Demorou sete anos para ficar pronta e será ‘’inaugurada’’ na piracema que se aproxima. Folha de Londrina. Outubro, 27 de 2006.; Figure 2G).

Figure 1
Map of the points sampled along the Laranjinha river (black circles). The green rectangle represents the Capivara reservoir, and the yellow rectangle represents the Canoas I reservoir, both on the Paranapanema River basin.

Figure 2
Partial view of collection points along the Laranjinha River, illustrating the environments and marginal vegetation. Points near source (a-c), points in the middle portion (d-f), and places near the mouth (g-i).

Data collection

Nine sites for sampling were distributed from the source to the mouth of the Laranjinha River (Figures 1 and 2; Table 1). Six collections were carried out in each site, with the aid of different fish gears (seines, gill nets, cast nets and sieves), from October 2010 to April 2012. The collections were authorized by SISBIO (Sistema de Autorização e Informação em Biodiversidade), Ministério do Meio Ambiente, under the nº 23315-1.

After the capture of the fish, the specimens were anesthetized with 10% benzocaine. This substance promotes a reduction in gill ventilation due to the depression of spinal respiratory centers, promoting a decrease in blood flow through the gills (Mattson & Riple 1989MATTSON, N.S. & RIPLE, T.H. 1989. Metomidate, a better anesthetic for cod (Gadus morhua) in comparison with benzocaine, MS-222, chlorobutanol, and phenoxyethanol. Aquaculture. 83(1-2):89-94.; Tytler & Hawkins 1981TYTLER, P. & HAWKINS, A.D. 1981. Vivisection, anaesthetics and minor surgery. In: Hawkins, A.D. (Editor). Aquarium Systems. Academic Press. p. 247-278.). After performing the opercular movements, the fish were fixed in 10% formalin and preserved in 70% ethanol in the Laboratório de Genética e Conservação of the Universidade Estadual do Norte do Paraná (GECON/UENP-CCP) and identified in species-level. The validity of the species was checked using Fricke et al. (2019)FRICKE, R., ESCHMEYER, W.N. & VAN DER LAAN, R. 2020. Catalog of fishes: genera, species, references. Disponível em: (http://researcharchive.calacademy.org/research/ichthyology/catalog/fishcatmain.asp). Access: March 23th, 2020.
http://researcharchive.calacademy.org/re... , and the classification was based using Van der Laan et al. (2020)VAN DER LAAN, R., ESCHMEYER, W. N. & FRICKE, R. 2020. Family-group names of recent fishes. Zootaxa. 3882(1)230. Disponível em: (https://www.calacademy.org/scientists/catalog-of-fishes-classification/). Access: March 23th, 2020.
https://www.calacademy.org/scientists/ca... . The species were identified following Ota et al. (2018)OTA, R.R., DEPRÁ, G.D.C., GRAÇA, W.J.D. & PAVANELLI, C.S. 2018. Peixes da planície de inundação do alto rio Paraná e áreas adjacentes: revised, annotated and updated. Neotropical Ichthyology. 16(2):e170094[1]- e170094[111]., Jarduli et al. (2020)JARDULI, L. R., GARCIA, D. A. Z., VIDOTTO-MAGNONI, A. P., CASIMIRO, A. C. R., VIANNA, N. C., ALMEIDA, F. S. D., JEREP, F.C. & ORSI, M. L. 2020. Fish fauna from the Paranapanema River basin, Brazil. Biota Neotropica. 20(1)., Terán et al. (2020)TERÁN, G. E., BENITEZ, M. F. & MIRANDE, J. M. 2020. Opening the Trojan horse: phylogeny of Astyanax, two new genera and resurrection of Psalidodon (Teleostei: Characidae). Zoological Journal of the Linnean Society. p. 1-18., and in the lack of information about the species from the authors before mentioned, personal communication with specialists took place (i.e., FC Jerep, CDCM de Santana, CAM Oliveira and CH Zawadzki).

The record of Poecilia reticulata Peters 1859 and Imparfinis schubarti (Gomes 1956) were based on Costa et al. (2013)COSTA, A.D.A., FERREIRA, D.G., SILVA, W.F., ZANATTA, A.S., SHIBATTA, O.A., & GALINDO, B.A. 2013. Fishes (Osteichthyes: Actinopterygii) from the Penacho stream, upper Paraná River basin, Paraná State, Brazil. Check List. 9(3):519-523.. Non-native species were based in 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. Revista brasileira de Zoologia. 16(2):557-560., Lobón-Cerviá & Bennemann (2000)LOBÓN-CERVIÁ, J. & BENNEMANN, S. 2000. Temporal trophic shifts and feeding diversity in two sympatric, neotropical, omnivorous fishes: Astyanax bimaculatus and Pimelodus maculatus in Rio Tibagi (Paraná, Southern Brazil). Archiv für Hydrobiologie. 285-306., 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 Neotropica. 7(3):1-17., Júlio-Júnior et al. (2009)JÚLIO-JÚNIOR, H.F., TÓS, C.D., AGOSTINHO, A.A. & PAVANELLI, C.S. 2009. A massive invasion of fish species after eliminating a natural barrier in the upper rio Paraná basin. Neotropical Ichthyology. 7(4):709-718., Britton & 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. Reviews in Fish Biology and Fisheries. 22(3):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., Ota et al. (2018)OTA, R.R., DEPRÁ, G.D.C., GRAÇA, W.J.D. & PAVANELLI, C.S. 2018. Peixes da planície de inundação do alto rio Paraná e áreas adjacentes: revised, annotated and updated. Neotropical Ichthyology. 16(2):e170094[1]- e170094[111]., 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. and Jarduli et al. (2020)JARDULI, L. R., GARCIA, D. A. Z., VIDOTTO-MAGNONI, A. P., CASIMIRO, A. C. R., VIANNA, N. C., ALMEIDA, F. S. D., JEREP, F.C. & ORSI, M. L. 2020. Fish fauna from the Paranapanema River basin, Brazil. Biota Neotropica. 20(1). (Table 2). Vouchers of all species were deposited in the Museu de Zoologia of the Universidade Estadual de Londrina (MZUEL). The abundances of orders, families, and species were conducted using the Statistica 7.0 software (StatSoft Inc. 2011STATSOFT, Inc. 2011. STATISTICA (data analysis software system).). The Kendeigh index of abundance (1944) of each species was calculated as KI = √FO.M; where KI is the abundance index, and FO is the frequency of occurrence calculated as the number of sites where the species were captured, and divided by the total number of sites multiplied by 100, and M is the mean number of specimens of each species. The classification of species was done by sorting the values in descending order. The dominance index and evenness were calculated with the program PAST v. 2.17c (Hammer et al. 2001HAMMER, M., YAROSLAVSKY, A.N. & SCHWEITZER, D. 2001. A scattering phase function for blood with physiological haematocrit. Physics in Medicine & Biology. 46(3):65.).

Results

A total of 11.934 specimens were collected, comprising seven orders, 27 families, and 100 species (Table 2; Appendix 1 - 5). Among these, the most representative order was Siluriformes (44.5%), followed by Characiformes (38.6%), Gymnotiformes (6.9%), and Cichliformes (5.9%). Cyprinodontiformes, Cypriniformes, and Synbranchiformes were represented by only one specimen each. Regarding the families, Loricariidae had 20 species (21%) and Characidae 16 species (14%). Together, these families showed the highest species richness (representing 35% of total richness), followed by Pimelodidae and Anostomidae, both composed of eight species each (8%), Heptapteridae and Cichlidae, both with six species each (6%), and Bryconidae with four species (4%; Figure 3).

Figure 3
Percentage composition of representative families of the ichthyofauna from the Laranjinha River, Upper Parana River basin, Paraná State, Brazil.

Among the sampling sites, A and B showed the lowest number of species (five species each), while sampling site I had a higher number of species (64 species). There is a progressive tendency of species richness from the source to the mouth (r² = 0.964). The dominance (D) is higher in the upper Laranjinha River (sites A, B, and C showing D = 0.49, 0.42, and 0.54, respectively), and this dominance drops expressively on the sites D (0.12) until I (0.05).

The highest absolute abundance was observed in Phalloceros harpagos Lucinda 2008 (11.3%), Hypostomus ancistroides (Ihering 1911) (9.8%), Hypostomus cf. paulinus (Ihering 1905) (8.4%), Psalidodon aff. paranae (6.9%), Hypostomus cf. strigaticeps (Regan 1908) (6.7%), and Astyanax lacustris (Lütken 1875) (5.3%; Table 2). Concerning the frequency of occurrence, the most frequent species of Laranjinha River were Psalidodon aff. paranae (FO = 88.8%), Hoplias gr. malabaricus, Astyanax lacustris, Psalidodon bockmanni (Vari & Castro 2007), Rhamdia quelen (Quoy & Gaimard 1824), Hypostomus ancistroides, Hypostomus cf. paulinus, and Hypostomus topavae (Godoy 1969) (FO = 77.7%). The classification of species from Kendeigh abundance index highlights the following ranking: Hypostomus ancistroides, Hypostomus cf. paulinus, Psalidodon aff. paranae, Phalloceros harpagos Lucinda 2008, Hypostomus cf. strigaticeps, and Astyanax lacustris. Among these species, Psalidodon aff. paranae and Phalloceros harpagos were frequent and dominant in the headwater region (sites A, B, and C), while the others were frequent downstream those sites.

From all recorded species, 9.8% were non-native: Aphyocharax cf. dentatus Eigenmann & Kennedy 1903, Apteronotus cf. caudimaculosus Santana 2003, Cyprinus carpio Linnaeus 1758, Hyphessobrycon eques (Steindachner 1882), Loricariichthys platymetopon Isbrücker & Nijssen 1979, Metynnis lippincottianus (Cope 1870), Oreochromis niloticus (Linnaeus 1758), Poecilia reticulata Peters 1859, Pterygoplichthys ambrosettii (Holmberg 1893), Sorubim lima (Bloch & Schneider 1801), and Triportheus nematurus (Kner, 1858). Of these species, two were exotic: Cyprinus carpio, which is a carp from Asia, and Oreochromis niloticus, know as Nile-tilapia, from Africa.

Ten long-distance migratory species were recorded in the Laranjinha River basin: Brycon orbygnianus (Valenciennes 1850), Megaleporinus obtusidens (Valenciennes 1837), Piaractus mesopotamicus (Holmberg 1887), Pinirampus pirinampu (Spix & Agassiz 1829), Prochilodus lineatus (Valenciennes 1837), Pseudoplatystoma corruscans (Spix & Agassiz 1829), Rhinelepis aspera Spix & Agassiz 1829, Salminus brasiliensis (Cuvier 1816), and Salminus hilarii Valenciennes 1850. Additionally, Leporinus friderici (Bloch 1794), Pimelodus maculatus Lacepède 1803, Rhamdia quelen, and Schizodon nasutus Kner 1858, which are considered short-migratory species, were also recorded herein (Agostinho et al. 2007AGOSTINHO, A.A., GOMES, L.C. & PELICICE, F.M. 2007. Ecology and management of fish resources in reservoirs in Brazil. Eduem., Oliveira et al. 2015OLIVEIRA, A.G., SUZUKI, H.I., GOMES, L.C. & AGOSTINHO, A.A. 2015. Interspecific variation in migratory fish recruitment in the Upper Paraná River: effects of the duration and timing of floods. Environmental Biology of Fishes. 98(5):1327-1337.).

Among the collected species, Apteronotus acidops Triques 2011, Brycon orbygnianus, Brycon nattereri Günther 1864, Crenicichla jupiaensis Britski & Luengo 1968, and Rhinelepis aspera Spix & Agassiz 1829 are classified as endangered in the most recent IUCN Red List. It is worth mentioning that two species are possibly new to science, Piabarchus aff. stramineus (sensuFrota et al., 2016FROTA, A., DEPRÁ, G.D.C., PETENUCCI, L.M. & GRAÇA, W.J. 2016. Inventory of the fish fauna from Ivaí River basin, Paraná State, Brazil. Biota Neotropica. 16(3): e20150151.), and Eigenmannia sp.

Discussion

The results presented in this study showed a high diversity of fishes (100 species) among the fish collected in the Laranjinha River. Such results follow the pattern found in the Neotropical regions, showing the dominance of Siluriformes and Characiformes (Agostinho et al. 1997AGOSTINHO, A.A., JÚLIO-JR, H.F., GOMES, L.C., BINI, L.M. & AGOSTINHO, C.S. 1997. Composição, abundância e distribuição espaço-temporal da ictiofauna, p. 179-208. In. VAZZOLER, A.E.A.M., AGOSTINHO, A.A. & HAHN, N.S. (Eds.). A planície de inundação do alto rio Paraná: aspectos físicos, biológicos e socioeconômicos. EDUEM. p. 460., Lowe-McConnell 1999, Jarduli et al. 2020JARDULI, L. R., GARCIA, D. A. Z., VIDOTTO-MAGNONI, A. P., CASIMIRO, A. C. R., VIANNA, N. C., ALMEIDA, F. S. D., JEREP, F.C. & ORSI, M. L. 2020. Fish fauna from the Paranapanema River basin, Brazil. Biota Neotropica. 20(1).). Furthermore, among Paranapanema River tributaries, the number of species is lower if compared to the Tibagi River basin, where 158 species were registered (Lobón-Cerviá & Bennemann 2000AGOSTINHO, A.A., THOMAZ, S.M. & GOMES, L.C. 2005. Conservation of the biodiversity of Brazil’s inland waters. Conservation Biology. 19(3):646-652., Bennemann et al. 2006BENNEMANN, S.T., Capra, L.G., Galves, W. & Shibatta, O.A. 2006. Dinâmica trófica de Plagioscion squamosissimus (Perciformes, Sciaenidae) em trechos de influência da represa Capivara (rios Paranapanema e Tibagi). Iheringia. Série Zoologia. 96(1):115-119., 2011BENNEMANN, S.T., GALVES, W. & CAPRA, L.G. 2011. Recursos alimentares utilizados pelos peixes e estrutura trófica de quatro trechos no reservatório Capivara (Rio Paranapanema). Biota Neotropica. 11(1):63-71., Shibatta & Cheida 2003SHIBATTA, O.A. & CHEIDA, C.C. 2003. Composição em tamanho dos peixes (Actinopterygii, Teleostei) de ribeirões da bacia do rio Tibagi, Paraná, Brasil. Revista Brasileira de Zoologia. 20(3):469-473., 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, Série Zoológica. 95(3):319-325., Oliveira & Bennemann et al. 2005OLIVEIRA, D.C.D., & BENNEMANN, S.T. 2005. Ictiofauna, recursos alimentares e relações com as interferências antrópicas em um riacho urbano no sul do Brasil. Biota Neotropica. 5(1):95-107., Jerep et al. 2006JEREP, F.C. SHIBATTA, O.A. PEREIRA, E.H. & OYAKAWA, O.T. 2006. Two new species of Isbrueckerichthys Derijst, 1996 (Siluriformes: Loricariidae) from the rio Paranapanema basin, Brazil. Zootaxa. 1372(1):53-68., Sant’Anna et al. 2006SANT’ANNA, J.F.M., ALMEIDA, M.C., VICARI, M.R., SHIBATTA, O.A. & ARTONI, R.F. 2006. Levantamento rápido de peixes em uma lagoa marginal do rio Imbituva na bacia do Alto rio Tibagi, Paraná, Brasil. Publicatio. UEPG Ciências Biológicas e da Saúde. 12(1):39-46, Shibatta et al. 2002SHIBATTA, O.A., ORSI, M.L., BENNEMANN, S.T. & SILVA-SOUZA, A.T. 2002. Diversidade e distribuição de peixes na bacia do rio Tibagi; p.403-423, in: MEDRI, M.E., BIANCHINI, E., SHIBATTA, O.A. & PIMENTA. J.A. A bacia do rio Tibagi. Londrina., 2006aSHIBATTA, A.O., ORSI, M.L. & ARTONI, R.F. 2006a. Estratégia reprodutiva dos peixes do Parque Estadual de Vila Velha. In: Peixes do Parque Estadual de Vila Velha: aspectos da história natural, da biologia evolutiva e da conservação (R.F. Artoni & O.A. Shibatta, eds). Editora UEPG, Ponta Grossa, p.67-77., 2006bSHIBATTA, O.A., ORSI, M.L. & BENNEMANN, S.T. 2006b. Os peixes do Parque Estadual Mata dos Godoy. In: Ecologia do Parque Estadual Mata do Godoy (J.M. Torezan, org). Ed. Itedes, Londrina. p.156-167., 2007SHIBATTA, O.A., GEALH, A.M. & BENNEMANN, S.T. 2007. Ictiofauna dos trechos alto e médio da bacia do rio Tibagi, Paraná, Brasil. Biota Neotropica. 7:125-134., 2008SHIBATTA, O.A., BENNEMANN, S.T., MORI, H. & SILVA, D.F. 2008. Riqueza biológica e ecológica dos peixes do Ribeirão Varanal. In: A flora e a fauna do Ribeirão Varanal: um estudo da biodiversidade do Paraná (S.T. Bennemann, O.A. Shibatta, A.O.D. Vieira, eds) Londrina, EDUEL, p.77-97., Galves et al. 2007GALVES, W., SHIBATTA, O.A. & JEREP, F.C. 2007. Fish, Taquara river basin, northern of the state of Paraná, Brazil. Check List. 3(3):253-259., Vieira & Shibatta 2007VIEIRA, D.B. & SHIBATTA, O.A. 2007. Peixes como indicadores da qualidade ambiental do ribeirão Esperança, município de Londrina, Paraná, Brasil. Biota Neotropica. 7(1):bn01407012007., Orsi 2010ORSI, M.L. 2010. Estratégias reprodutivas de peixes da Região média-baixa do Rio Paranapanema, Reservatório de Capivara. São Paulo. Blucher Acadêmico. p.115., Raio & Bennemann 2010RAIO, C.B. & BENNEMANN, S.T. 2010. A ictiofauna da bacia do rio Tibagi e o projeto de construção da UHE Mauá, Paraná, Brasil. Semina: Ciências Biológicas e da Saúde. 31(1):15-20., Garcia et al. 2014GARCIA, D.A.Z., COSTA, A.D.A., LEME, G.L.A. & ORSI, M.L. 2014. Biology of black bass Micropterus salmoides (Lacepède, 1802) fifty years after the introduction in a small drainage of the Upper Paraná River basin, Brazil. Biodiversitas. 15(2):180-185., 2015GARCIA, D.A.Z., HERNANDES, M.C., SILVA-SOUZA, Â.T. & ORSI, M.L. 2015. Establishment of non-native predator (Pisces, Erythrinidae) in a tributary of the Upper Paraná River basin, south Brazil. Neotrop. Biol. Conserv. 10(3):177-181., Silva et al. 2015SILVA, J.C., ROSA, R.R., GALDIOLI, E.M., SOARES, C.M., DOMINGUES, W.M., VERÍSSIMO, S. & BIALETZKI, A. 2017. Importance of dam-free stretches for fish reproduction: the last remnant in the Upper Paraná River. Acta Limnologica Brasiliensia, 29:e16., Frantine-Silva et al. 2015FRANTINE-SILVA, W., FERREIRA, D.G., NASCIMENTO, R.H.C., FRACASSO, J.F., CONTE, J.E., RAMOS, F.P., CARVALHO, S. & GALINDO, B.A. 2015. Genetic analysis of five sedentary fish species in middle Laranjinha River (upper Paraná River basin): A case study. Genetics and Molecular Research. 14(4):18637-18649., Almeida et al. 2018ALMEIDA, F.S., FRANTINE-SILVA, W., LIMA, S.C., GARCIA, D.A.Z. & ORSI, M.L. 2018. DNA barcoding as a useful tool for identifying non-native species of freshwater ichthyoplankton in the neotropics. Hydrobiologia. 817(1):111-19., Jerep & Shibatta 2017JEREP, F.C. & SHIBATTA, O.A. 2017. A new species of Bryconamericus (Characidae: Stevardiinae: Diapomini) from the upper rio Paraná basin, Brazil. Neotropical Ichthyology. 15(3):e170028., Claro-Garcia et al. 2018), and to the Cinzas River, with 114 species (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, Série Zoológica. 95(3):319-325., Vianna & Nogueira, 2008VIANNA, N.C. & NOGUEIRA, M.G. 2008. Ichthyoplankton and limnological factors in the Cinzas River - an alternative spawning site for fishes in the middle Paranapanema River basin, Brazil. Acta Limnologica Brasiliensia. 20:139-151., Orsi 2010ORSI, M.L. 2010. Estratégias reprodutivas de peixes da Região média-baixa do Rio Paranapanema, Reservatório de Capivara. São Paulo. Blucher Acadêmico. p.115., Bennemann et al. 2011BENNEMANN, S.T., GALVES, W. & CAPRA, L.G. 2011. Recursos alimentares utilizados pelos peixes e estrutura trófica de quatro trechos no reservatório Capivara (Rio Paranapanema). Biota Neotropica. 11(1):63-71., Costa et al. 2013COSTA, A.D.A., FERREIRA, D.G., SILVA, W.F., ZANATTA, A.S., SHIBATTA, O.A., & GALINDO, B.A. 2013. Fishes (Osteichthyes: Actinopterygii) from the Penacho stream, upper Paraná River basin, Paraná State, Brazil. Check List. 9(3):519-523., Frantine-Silva et al. 2015FRANTINE-SILVA, W., FERREIRA, D.G., NASCIMENTO, R.H.C., FRACASSO, J.F., CONTE, J.E., RAMOS, F.P., CARVALHO, S. & GALINDO, B.A. 2015. Genetic analysis of five sedentary fish species in middle Laranjinha River (upper Paraná River basin): A case study. Genetics and Molecular Research. 14(4):18637-18649., Almeida et al. 2018ALMEIDA, F.S., FRANTINE-SILVA, W., LIMA, S.C., GARCIA, D.A.Z. & ORSI, M.L. 2018. DNA barcoding as a useful tool for identifying non-native species of freshwater ichthyoplankton in the neotropics. Hydrobiologia. 817(1):111-19.).

It is noteworthy that the most frequent species of Laranjinha River was Psalidodon aff. paranae, captured in eight sites. The higher abundance were in the uppermost site A, and along the downstream, the number of specimens decreased until site H, which corroborate the hypothesis that this species has a preference regarding the headwater region (Britski 1972BRITSKI, H.A. 1972. Peixes de água doce do Estado de São Paulo, p. 79-108. In: Comissão Interestadual da Bacia Paraná-Uruguai, Poluição e piscicultura. Sistemática. Faculdade de Saúde Pública USP e Instituto de Pesca.), but it is not restricted to that. Psalidodon aff. paranae is an insectivorous species, feeding mainly of allochthonous resources from the riparian forest. However, it can gather enough food resources from environments with different levels of degradation (Ferreira et al. 2012Ferreira, A., Gerhard, P. & Cyrino, J.E.P. 2012. Diet of Astyanax paranae (Characidae) in streams with different riparian land covers in the Passa Cinco River basin, southern Brazil. Iherngia, Série Zoologia 10:80-87.).

In the upper region of Laranjinha River, Phalloceros harpagos, a native species, was the most abundant one, being dominant in the site C. The value of dominance index (D=0.54) and evenness (E=0.17) of that site, reflected the disturbance in the observed environment. Biological features of P. harpagos like constant reproduction (Wolff et al. 2007WOLFF, L.L., ERICSSON, H.R, VIANA, D. & ZALESKI, D. 2007. Population structure of Phalloceros caudimaculatus (Hensel, 1868) (Cyprinodontiformes, Poeciliidae) collected in a brook in Guarapuava, PR. Brazilian Archives of Biology and Technology. 50(3):417-423.), adaptability, tolerance to heat, variations in salinity (Nascimento & Gurgel 2000NASCIMENTO, R.S.S. & GURGEL, H.D.C.B. 2000. Estrutura populacional de Poecilia vivipara Bloch & Schneider, 1801 (Atheriniformes, Poeciliidae) do rio Ceará-Mirim-Rio Grande do Norte. Acta Scientiarum. Biological Sciences. 22:415-422.), and high trophic plasticity (Casatti et al. 2009CASATTI, L., FERREIRA, C.P. & LANGEANI, F. 2009. A fish-based biotic integrity index for assessment of lowland streams in southeastern Brazil. Hydrobiologia. 623:173-189., Rocha et al. 2009ROCHA, F.C., CASATTI, L. & PEREIRA, D.C. 2009. Structure and feeding of a stream fish assemblage in Southeastern Brazil: evidence of low seasonal influences. Acta Limnologica Brasiliensia. 21(1):123-134.) may be related to the success of the species at that location. This species has a wide geographical distribution (Thomaz et al. 2019THOMAZ, A. T., CARVALHO, T. P., MALABARBA, L. R. & KNOWLES, L. L. 2019. Geographic distributions, phenotypes, and phylogenetic relationships of Phalloceros (Cyprinodontiformes: Poeciliidae): Insights about diversification among sympatric species pools. Molecular phylogenetics and Evolution. 132:265-274.), which may also be related to its ecological plasticity.

Hypostomus ancistroides, H. cf. paulinus, and H. cf. strigaticeps were abundant and frequent from C to I sites. A factor that possibly has favored these rheophilic species is the presence of running water in the Laranjinha River (Cecilio et al. 1997CECILIO, E.B., AGOSTINHO, A.A., JÚLIO-JÚNIOR, H.F. & PAVANELLI, C.S. 1997. Colonização ictiofaunística do reservatório de Itaipu e áreas adjacentes. Revista Brasileira de Zoologia. 14:1-14.; Garcia et al. 2020GARCIA, T.D., OTA, R.R., FERREIRA, D.G., NASCIMENTO, R.H., GALINDO, B.A., PEREIRA, L.S., & ZANATTA, A.S. 2020. Distribution of Siluriformes in a river under the influence of a small hydroelectric power plant of the Paraná River Basin, Brazil. Iheringia. Série Zoologia. 110: e2020005.). Several species of Hypostomus were collected in running waters showing a substrate with pebbles and rocks (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). Brazilian Journal of Biology. 64(3B):103-141.; Perez-Junior & Garavello 2007PEREZ-JUNIOR, O.R. & GARAVELLO, J.C. 2007. Ictiofauna do ribeirão do Pântano, afluente do rio Mogi-Guaçu, bacia do alto rio Paraná, São Paulo, Brasil. Iheringia. Série Zoologia. 97(3):328-335.), but in Laranjinha River these species also occur in some places with a sand bottom. Hypostomus ancistroides, the most abundant of these species, had higher abundance in the site C, which decreased until site I, and such data demonstrates that this species is the least rheophilic one among congeners.

In general, the non-native fish species recorded in this study were introduced from other drainages in Brazil. All these species are associated with human activities like aquarium trade (possibly Aphyocharax cf. dentatus, Apteronotus albifrons, Hyphessobrycon eques and Poecilia reticulata), fish ladders (possibly Metynnis lippincottianus, Pterygoplichthys ambrosetti and Triportheus nematurus), fish farming (certainly Cyprinus carpio, Oreochromis niloticus and Sorubim lima), and control of insect larvae (possibly Poecilia reticulata). It is worth mentioning that among these non-native species, two of them are considered exotic (Cyprinus carpio and Oreochromis niloticus). These records are alarming, as C. carpio is known to promote bioturbation by continually revolving the sediment (Ritvo et al. 2004RITVO, G. KOCHBA, M. & AVNIMELECH, Y. 2004. The effects of common carp bioturbation on fishpond bottom soil. Aquaculture. 242(4):345-356.). However, only two individuals were sampled, being exclusive on site G, an area surrounded by pastures and agriculture. On the other hand, O. niloticus was more abundant and widely distributed, being sampled in five sites, which corresponds to an area surrounded by pasture and agriculture, and specifically in site B with the discharge of effluents. In addition, this species changes the environment due to the excess of nitrogen excreta, thus favoring the proliferation of algae, which decreases light and dissolved oxygen (Britton et al. 2007BRITTON, J.R., BOAR, R.R., GREY, J., FOSTER, J., LUGONZO, J. & HARPER, D.M. 2007. From introduction to fishery dominance: the initial impacts of the invasive carp Cyprinus carpio in Lake Naivasha, Kenya, 1999 to 2006. Journal of Fish Biology. 71:239-257., Vicente & Fonseca-Alves 2013VICENTE, I.S.T. & FONSECA-ALVES, C.E. 2013. Impact of introduced Nile tilapia (Oreochromis niloticus) on non-native aquatic ecosystems. Pakistan Journal of Biological Sciences. 16(3):121-126.). Besides that, Poecilia reticulata was registered by Costa et al. (2013)COSTA, A.D.A., FERREIRA, D.G., SILVA, W.F., ZANATTA, A.S., SHIBATTA, O.A., & GALINDO, B.A. 2013. Fishes (Osteichthyes: Actinopterygii) from the Penacho stream, upper Paraná River basin, Paraná State, Brazil. Check List. 9(3):519-523. in the study of the Penacho stream, a small tributary on the right bank of the Laranjinha River that flows into the Cinzas River. The high abundance of P. reticulata indicates an instability of the environment, including factors such as the lack of food resources for other species and the low level of dissolved oxygen (De Souza & Tozzo 2013DE SOUZA, F. & TOZZO, R. A. 2013. Poecilia reticulata Peters 1859 (Cyprinodontiformes, Poeciliidae) como possível bioindicador de ambientes degradados. Revista Meio Ambiente e Sustentabilidade. 3(2):162-175.).

The occurrence of 13 medium- to large-size migratory fishes highlights the importance of Laranjinha River for the maintenance of the diversity and viability of the ichthyofauna of the middle Paranapanema River. Other studies also highlight the Cinzas River basin and the Laranjinha River as migratory routes to the fish fauna from the Capivara dam (Dias et al. 2004DIAS, J.H., BRITTO, S.G.C., VIANNA, N.C. & GARAVELLO, J.C. 2004. Biological and ecological aspects of Pinirampus pirinampu (Spix, 1829) Siluriformes, Pimelodidae. Capivara reservoir, Paranapanema River Southern Brazil. Acta Limnologica Brasileira 16:293-304., Lopes et al. 2007LOPES, C.M., ALMEIDA, F.S., ORSI, M.L., BRITTO, S.G.D.C., SIROL, R.N. & SODRÉ, L.M.K. 2007. Fish passage ladders from Canoas Complex-Paranapanema River: evaluation of genetic structure maintenance of Salminus brasiliensis (Teleostei: Characiformes). Neotropical Ichthyology. 5(2):131-138., Vianna & Nogueira 2008VIANNA, N.C. & NOGUEIRA, M.G. 2008. Ichthyoplankton and limnological factors in the Cinzas River - an alternative spawning site for fishes in the middle Paranapanema River basin, Brazil. Acta Limnologica Brasiliensia. 20:139-151., Orsi 2010ORSI, M.L. 2010. Estratégias reprodutivas de peixes da Região média-baixa do Rio Paranapanema, Reservatório de Capivara. São Paulo. Blucher Acadêmico. p.115.). As the Laranjinha River has only a little dam, including a fish pass system built in it, it extends a long stretch without dams, enabling migratory fish species to use its free-flowing stretches to complete their reproductive cycles. Long-distance migratory species with high commercial value have been using tributaries of rivers intensely affected by dams as migratory routes (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. Brazilian Journal of Biology. 68(4):1119-1132.). The pressure caused by power plant dam constructions is intense in freshwater systems (Agostinho et al. 2005AGOSTINHO, A.A., THOMAZ, S.M. & GOMES, L.C. 2005. Conservation of the biodiversity of Brazil’s inland waters. Conservation Biology. 19(3):646-652.), because the transformation of lotic areas into lentic ones interrupts the displacement of migratory fish (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. Brazilian Journal of Biology. 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.). The impact is not restricted to migratory species, and it also impairs the local fauna that depends on the tributaries for the viability of spawning and survival of early life stages (Oliveira et al. 2015OLIVEIRA, A.G., SUZUKI, H.I., GOMES, L.C. & AGOSTINHO, A.A. 2015. Interspecific variation in migratory fish recruitment in the Upper Paraná River: effects of the duration and timing of floods. Environmental Biology of Fishes. 98(5):1327-1337.). Studying the dynamics of eggs and larvae in the Cinzas River, Vianna & Nogueira (2008)VIANNA, N.C. & NOGUEIRA, M.G. 2008. Ichthyoplankton and limnological factors in the Cinzas River - an alternative spawning site for fishes in the middle Paranapanema River basin, Brazil. Acta Limnologica Brasiliensia. 20:139-151., found that the fishes of the middle Paranapanema River use this tributary to spawn. In general, biological communities are under heavy pressure due to environmental instability caused by habitat fragmentation and loss of natural environments, which affect species abundance and richness (Pusey & Arthington 2003PUSEY, B.J. & ARTHINGTON, A.H. 2003. Importance of the riparian zone to the conservation and management of freshwater fish: a review. Marine and freshwater Research. 54(1):1-16., Di Giulio et al. 2009DI GIULIO, M., HOLDEREGGER, R. & TOBIAS, S. 2009. Effects of habitat and landscape fragmentation on humans and biodiversity in densely populated landscapes. Journal of environmental management. 90(10):2959-2968., Shandas & Alberti, 2009SHANDAS, V. & ALBERTI, M. 2009. Exploring the role of vegetation fragmentation on aquatic conditions: Linking upland with riparian areas in Puget Sound lowland streams. Landscape and Urban Planning. 90(1-2):66-75.).

Furthermore, the conservation of the Laranjinha River is essential to preserve the species already categorized as threatened by extinction in the IUCN’s Red List (Apteronotus acidops, Brycon orbygnianus and Crenicichla jupiaensis as Endangered; Brycon nattereri as Vulnerable; and Rhinelepis aspera as Near Threatened) (ICMBio 2018ICMBio 2018. Red Book of Threatened Brazilian Fauna. Disponível em: < https://www.nationalredlist.org/livro-vermelho-da-fauna-brasileira-ameacada-de-extincao-2018-red-book-of-threatened-brazilian-fauna-portuguese>. December 18th, 2019.
https://www.nationalredlist.org/livro-ve... ). The fact that some of these fish appear on a list of endangered species is concerning and it reinforces that the focused area needs appropriate conservation strategies (Simic et al. 2007SIMIC, V., SIMIC, S., PAUNOVIC, M. & CAKIC, P. 2007. Model of the assessment of the critical risk of extinction and the priorities of protection of endangered aquatic species at the national level. Biodiversity Conservation. 16:2471-2493.). Studies on B. nattereri reinforce the importance of Laranjinha River conservation, since this migratory and threatened species has been able to maintain a satisfactory population genetic diversity due to the quality of that environment (Galindo et al. 2019GALINDO, B.A., FERREIRA, D.G., APOLINÁRIO-SILVA, C., TERRA, M.C., APRÍGIO, N.G., OTA, R.R., Ohara, W.M., ALMEIDA, F.S & SOFIA, S.H. 2019. Genetic diversity and population structure of Brycon nattereri (Characiformes: Bryconidae): a Neotropical fish under threat of extinction. Neotropical Ichthyology. 17(1):e180071.).

Finally, the Laranjinha River is a heritage of fish diversity due to the presence of large numbers of species (among migratory, threatened, and new species to science). Thus, it deserves special attention regarding its preservation.

Acknowledgments

Our thanks to the “ Universidade Estadual do Norte do Paraná - UENP/PROPG/EDITORA UENP” for the partial support provided

Supplementary Material

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Appendix 1

Appendix 2

Appendix 3

Appendix 4

Appendix 5

References

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