Fishes of the Taquari-Antas river basin (Patos Lagoon basin), southern Brazil Becker, FG.a*, De Fries, LCC.b, Ferrer, J.b, Bertaco, VA.b, Luz-Agostinho, KDG.c, Silva, JFP.d, Cardoso, AR.e, Lucena, ZMS.f and Lucena, CAS.f aLaboratório de Ecologia de Paisagem, Departamento de Ecologia, Universidade Federal do Rio Grande do Sul – UFRGS, Av. Bento Gonçalves, 9500, Setor 4, Prédio 43422, CP 15007, CEP 91501-970, Porto Alegre, RS, Brazil bLaboratório de Ictiologia, Departamento de Zoologia, Universidade Federal do Rio Grande do Sul – UFRGS, Av. Bento Gonçalves, 9500, Setor 4, Prédio 43435, CEP 91501-970, Porto Alegre, RS, Brazil cLimnobios Consultoria em Ambientes Aquáticos, Av. Pioneiro Alicio Arantes Campolina, 1223A, CEP 87020-750, Maringá, PR, Brazil dJPSBIO Consultoria Ambiental, Estrada Francisca de Oliveira Vieira, 796, CEP 91780-050, Porto Alegre, RS, Brazil eSetor de Ictiologia, Museu de Ciências Naturais, Fundação Zoobotânica do Rio Grande do Sul, Av. Dr. Salvador França, 1427, CEP 90690-000, Porto Alegre, RS, Brazil fSetor de Ictiologia, Museu de Ciências e Tecnologia, Pontifícia Universidade Católica do Rio Grande do Sul – PUCRS, Av. Ipiranga, 6681, CP 1424, CEP 90619-900, Porto Alegre, RS, Brazil *e-mail: [email protected] Received November 29, 2011 – Accepted March 23, 2012 – Distributed February 28, 2013 (With 4 figures) Abstract The aquatic habitats of the Taquari-Antas river basin (in the Patos Lagoon basin, southern Brazil) are under marked environmental transformation because of river damming for hydropower production. In order to provide an information baseline on the fish fauna of the Taquari-Antas basin, we provide a comprehensive survey of fish species based on primary and secondary data. We found 5,299 valid records of fish species in the basin, representing 119 species and 519 sampling sites. There are 13 non-native species, six of which are native to other Neotropical river basins. About 24% of the total native species are still lacking a taxonomic description at the species level. Three native long-distance migratory species were recorded (Leporinus obtusidens, Prochilodus lineatus, Salminus brasiliensis), as well as two potential mid-distance migrators (Parapimelodus nigribarbis and Pimelodus pintado). Although there is only one officially endangered species in the basin (S. brasiliensis), restricted range species (21.7% of total species) should be considered in conservation efforts. Keywords: ichthyofauna, biodiversity, survey, neotropical, Rio Grande do Sul. Peixes da bacia do rio Taquari-Antas (sistema da Laguna dos Patos), sul do Brasil Resumo Os ambientes aquáticos da Bacia do rio Taquari-Antas (Bacia da Laguna dos Patos, sul do Brasil) vêm sofrendo considerável transformação, principalmente em razão da implantação de barragens para geração de energia elétrica. Com o objetivo de estabelecer um diagnóstico amplo da ictiofauna da Bacia do Taquari-Antas, realizou-se um inventário das espécies dessa bacia a partir de dados primários e secundários. Foram obtidos 5.299 registros válidos de espécies de peixe na bacia, representando 119 espécies e 519 localidades amostradas. Ocorrem, na bacia, 13 espécies não nativas, seis das quais são oriundas de outras bacias neotropicais. Cerca de 24% de todas as espécies carecem de descrição taxonômica no nível específico. Foram registradas três espécies nativas migradoras de longa distância (Leporinus obtusidens, Prochilodus lineatus e Salminus brasiliensis) e duas potenciais migradoras de média distância (Parapimelodus nigribarbis e Pimelodus pintado). O fato de uma espécie ser oficialmente reconhecida como ameaçada na bacia (S. brasiliensis) e a grande proporção de espécies de distribuição restrita (21,7% do total) devem ser levados em consideração nos esforços de conservação. Palavras-chave: ictiofauna, biodiversidade, inventário, neotropical, Rio Grande do Sul. 1. Introduction The Brazilian freshwater fish fauna is extremely diverse, in the southeastern and southern regions, where land use with more than 2,500 valid species distributed through change, pollution and damming for hydroelectricity are the several habitat types and river systems, and there is a growing main factors affecting fish conservation (Agostinho et al., number of new species being described (Buckup et al., 2008; Barletta et al., 2010). This continuous process of 2007). However, river basins in Brazil are becoming environmental change threatens the existence of fish species increasingly transformed by human activities, particularly and their habitats, therefore conservation planning and Braz. J. Biol., 2013, vol. 73, no. 1, p. 79-90 79 Becker, FG. et al. prioritization require information on species composition high degree of endemism for fishes of the Jacuí headwaters and distribution in relatively large areas. In Brazil, surveys (21.7%), which include the Taquari-Antas headwaters. for improving the knowledge base on freshwater fishes Luz-Agostinho et al. (2010) found 70 species in the mid- are frequently called for (Vari and Malabarba, 1998; stretch of the Taquari-Antas and several tributaries, and Agostinho et al., 2005, 2008; Buckup et al., 2007). also report baseline information on the reproduction and In this paper, we present the results of a fish species feeding of several species. survey in the Taquari-Antas river basin (26.470 km2), in Our main objective is to present a comprehensive southern Brazil. This region has been historically affected by survey of the fish species of the Taquari-Antas basin. We urban, industrial and agricultural activities, although there used primary data from our own field collections, but also are several relatively less affected areas of Atlantic forest compiled a large amount of secondary data, including samples and natural grasslands. In the early 2000s, river damming from several different habitats. In particular, we aimed at for hydropower generation became an additional cause of producing a species list that is the best approximation of the environmental transformation. By the end of 2010, there actual species composition in the studied area, and where were 26 hydroelectric power plants (from <1 MW to 130 taxonomic consistence and uncertainties are objectively MW) in operation or under construction in the Taquari- pointed out. We also assessed the fish fauna in terms of Antas basin, with more than 80 sites under examination non-native species, conservation status, general spatial for potentially new dams (data from the Rio Grande do Sul distribution patterns, species with restricted geographical State Foundation for Environment Protection – FEPAM, distribution, and migratory species. and from the Brazilian electric power authority database, ANEEL/SIGEL). In the lower Taquari river there is also 2. Material and Methods a canal lock for navigation, which can be considered the first obstacle for upstream fish migration. 2.1. Study area In spite of a relatively large number of recent taxonomic studies and fish sampling across the Taquari-Antas basin, The Taquari-Antas basin is situated in southern Brazil a consolidated overview of the fish species composition (state of Rio Grande do Sul) and is one of the main sub- and distribution is lacking. Studies providing a wider basins of the Patos Lagoon basin (Figure 1), which is a large perspective of the Taquari-Antas fishes were only recently drainage flowing into the Atlantic Ocean and is one of the published (Malabarba et al., 2009; Luz-Agostinho et al., freshwater ecoregions recognized by Abell et al. (2008). 2010), however their scope was limited to specific regions It is a 7th order river basin (Strahler, 1957; stream network within the watershed. Malabarba et al. (2009) surveyed map at 1:250.000 scale) with a total area of 26.470 km2. the fishes from the high basaltic plateau, including the The Antas river, as the main river is called in the upper headwaters of the Taquari-Antas and Caí rivers (both in section of the basin, flows from a high basaltic plateau the Patos Lagoon basin) and of Pelotas and Canoas rivers (ca. 800 to 1200 m a.s.l) through deeply incised valleys (upper Uruguay river basin). They found 46 species and a until the lowlands, where it is known as Taquari river. Figure 1. Geographic location of the Taquari-Antas basin within the Patos Lagoon basin. 80 Braz. J. Biol., 2013, vol. 73, no. 1, p. 79-90 Fishes of the Taquari-Antas river The lowlands flow through terrains formed by alluvial specimens in scientific collections. We also excluded deposits in elevations between 20 m to 100 m a.s.l. The any record with a geographic location that could not be main river channel, from headwaters to the confluence unequivocally determined to be within the Taquari-Antas with Jacuí river, is ca. 400 km long and the mean annual basin. The taxonomic classification follows Reis et al. flow is 606 m3.s-1 (Rio Grande do Sul, 2007). (2003a), except for the use of Labriformes (Wiley and Johnson, 2010). 2.2. Species records We assessed the species conservation status according We determined the fish species of the Taquari-Antas to the endangered species list of Rio Grande do Sul basin from primary and secondary data. Primary data were (Reis et al., 2003b) and the Brazilian list of endangered obtained by sampling fish assemblages at several localities fish species (Instrução Normativa do Ministério do Meio across the study area during 2010. Secondary data were Ambiente nº 05, 21 de maio de 2004). To determine species obtained by reviewing and validating records from the with restricted geographical ranges (<10.000 km2 sensu largest and most regionally representative fish collections Nogueira et al., 2010), we used data from our survey and (Museu de Ciências Naturais da Fundação Zoobotânica do primary literature, rather than assuming a priori only the Rio Grande do Sul, MCN; Museu de Ciências e Tecnologia species listed by Nogueira et al. (2010). We considered as da Pontifícia Universidade Católica do Rio Grande do Sul, migratory those species mentioned by Luz-Agostinho et al. MCP; Department of Zoology of Universidade Federal do (2010). Any species whose natural distribution does not Rio Grande do Sul, UFRGS). Additionally, we reviewed include the Patos Lagoon basin was considered as non- species records from scientific publications and technical native. We also described the general distribution pattern environmental reports available at FEPAM. of species across the main geomorphological sections The fish records compiled comprise samples obtained of the Taquari-Antas basin (Lowlands, Mid-slopes, and by several different fishing techniques (gill nets, seine nets, Plateau). Species were classified as typical of a section cast nets, dip nets and electrofishing) and encompassed when >70% of their records were included in only one several habitat types (small streams to large rivers, reservoirs section. Species occurring in all sections and with more and small wetlands). than 30% records in at least two sections were considered to be well distributed across the Taquari-Antas basin. 2.3. Geographical coordinates of species records After compiling the fish record database for the whole 3. Results Taquari-Antas basin, we found three types of geographic We obtained 5,299 valid presence records of fish location data: (a) descriptions of the sampling site geographic species in the Taquari-Antas basin, representing 119 species location without geographic coordinates (found mostly in (including non-native species; Table 1) and 519 sampling museum records and in bibliographic sources), (b) geographic sites (Figure 2). The total number of species (119) was coordinates that had been obtained in the field, using GPS determined only after a validation process on a preliminary receivers and (c) geographic coordinates from unknown listing of 266 nominal taxa obtained from the secondary sources. In the first case, we approximated geographic data. Most sampling sites (43.3%) were located in higher coordinates on the basis of the site descriptions or site elevation areas of the plateau, while the remaining were locations pictured in maps included in the bibliographic situated in the slopes between the lowlands and the plateau sources, using a geographic information system ArcGis (32%) and in the lowlands (24.7%) (Figure 2). (ESRI) and the digital version of the official 1:50.000 There were records for 13 non-native species (10.9% cartographic database of Rio Grande do Sul (Hasenack of the total number of species), six of which are native and Weber, 2010). This cartographic database includes the to other Neotropical river basins (Table 2). About 25% stream network, roads, cities and detailed toponymy, and of the total native species are still lacking a taxonomic is usually used by researchers for field navigation and for description at the species level. Several of the recorded describing sampling site locations. Information about the species have a relatively limited geographical distribution datum associated with geographic coordinates was rare in (Table 2), including only the Taquari-Antas basin, or the database, therefore we assumed WGS84 for all records. the Taquari-Antas and adjacent neighboring watersheds (Upper Uruguay, Sinos, and Caí river, and the headwaters 2.4. Taxonomic validation of small coastal watersheds). Only Salminus brasiliensis is Fish samples collected by the authors were identified officially listed as a threatened species (Reis et al., 2003b). or validated by taxonomy specialists. Voucher specimens At least six migratory species were recorded in the of all species can be found in at least one of the reviewed Taquari-Antas basin: the long distance migrants Leporinus museum collections (MCN, MCP, UFRGS). Species obtusidens, Prochilodus lineatus, Salminus brasiliensis, records from secondary sources (museum databases and the mid-distance migrants Parapimelodus nigribarbis and non-taxonomic bibliographic sources) have been subject Pimelodus pintado, and the non-native Acestrorhynchus to nomenclature actualization (e.g., Astyanax alburnus pantaneiro. The migratory species were represented by few to Cyanocharax alburnus, cf. Malabarba and Weitzman, locality records (except for Pimelodus pintado, Figure 3), 2003; Pimelodus maculatus to Pimelodus pintado, cf. and were mostly limited to the mid- and lower sections of Azpelicueta et al., 2008). Museum specimens were the rivers, downstream the Cachoeirão rapids, except for examined only when the actual presence of a species in one record of Leporinus obtusidens at the Tainhas river the Taquari-Antas basin depended exclusively on the valid (see Figure 3). Pimelodus pintado was the most widely identification of a particular sample. We did not consider distributed migratory species with several records upstream as valid any record with dubious taxonomic identification the Cachoeirão and in upper parts of the main tributaries and that could not be validated by examining vouchers of the Antas river (Prata, Carreiro and Guaporé rivers). Braz. J. Biol., 2013, vol. 73, no. 1, p. 79-90 81 Becker, FG. et al. Table 1. Fish species of the Taquari-Antas river basin (Patos Lagoon basin), southern Brazil. Taxon Origin Comments ATHERINIFORMES Atherinopsidae Odontesthes humensis Native Odontesthes sp. Native CHARACIFORMES Anostomidae Leporinus obtusidens Native Schizodon jacuiensis Native Acestrorhynchidae Acestrorhynchus pantaneiro Non-native This species is native to the Paraná-Paraguay (Menezes, 2007). It is presently found as a non-native species in the Patos Lagoon basin (see Saccol and Pereira et al., 2006). Characidae Aphyocharax anisitsi Non-native This species is native to the Paraná-Paraguay (Souza-Lima, 2007). Presently it is found as a non-native species in the Patos Lagoon basin. Astyanax sp. aff. fasciatus Native Nomenclature follows Melo and Buckup (2006) Astyanax brachypterygium Native Restricted to headwater streams in high elevation (>1000 m). It is not exclusive from the Taquari-Antas basin (Bertaco and Malabarba, 2001) Astyanax cremnobates Native Restricted to headwater streams in high elevation (>1000 m). It is not endemic to the Taquari-Antas basin (Bertaco and Malabarba, 2001) Astyanax eigenmanniorum Native Astyanax henseli Native Astyanax jacuhiensis Native Astyanax laticeps Native Astyanax obscurus Native Astyanax sp.1 Native Undescribed species found across the Jacuí river basin (Upper Patos Lagoon basin) (V. A. Bertaco) Astyanax sp.2 Native Undescribed species found across found across the Jacuí, Uruguay e Tramandaí river basins (V. A. Bertaco) Astyanax sp.3 Native Undescribed species found only in the higher tributaries of the Taquari- Antas basin (V. A. Bertaco) Astyanax sp.4 Native Undescribed species found only in the Carreiro river and its tributaries (Taquari-Antas basin) (V. A. Bertaco). Bryconamericus ecai Native This species is known only from its type locality and is endemic to the Taquari-Antas basin (Silva, 2004) Bryconamericus iheringii Native Bryconamericus patriciae Native Charax stenopterus Native Cheirodon ibicuhiensis Native Cheirodon interruptus Native Cyanocharax alburnus Native Cyanocharax Native dicropotamicus Diapoma speculiferum Native Diapoma thauma Native Known only from the Taquari-Antas and Sinos river basins (Menezes and Ribeiro, 2010) Heterocheirodon jacuiensis Native Hyphessobrycon igneus Native This species was usually identified as H. bifasciatus, which does not occur in the Patos Lagoon basin (F. L. Barros, personal communication to C.A.S. Lucena; Carvalho, 2011) Hyphessobrycon luetkenii Native Hypobrycon sp. Native New species under description by L. R. Malabarba and J. Pezzi da Silva 82 Braz. J. Biol., 2013, vol. 73, no. 1, p. 79-90 Fishes of the Taquari-Antas river Table 1. Continued... Taxon Origin Comments Oligosarcus jacuiensis Native Oligosarcus jenynsii Native Oligosarcus robustus Native Oligosarcus sp. Native Potentially a new species (N. A. Menezes, personal communication to C. A. S. Lucena). We found one record for O. brevioris (MCP18700), however the data on the collection site is ambiguous and insufficient to validate the occurrence of this species in the Taquari-Antas basin Pseudocorynopoma doriae Native Salminus brasiliensis Native Serrapinnus calliurus Native Crenuchidae Characidium gr. zebra Native Characidium orientale Native Characidium pterostictum Native Characidium tenue Native Curimatidae Cyphocharax spilotus Non-native This species was known only for the Uruguay river and lower Paraná basin, however it has been recently found also in the Patos Lagoon basin (e.g., Flores-Lopes et al., 2010; Luz-Agostinho et al., 2010) Cyphocharax voga Native Steindachnerina biornata Native Erythrinidae Hoplias lacerdae Non-native Its original distribution includes the Ribeira do Iguape and Uruguay river basins (Oyakawa and Mattox, 2009). Its introduction in the Patos Lagoon basin has possibly resulted from escapement from small fishing ponds and fish culture facilities Hoplias aff. malabaricus Native Prochilodontidae Prochilodus lineatus Native CLUPEIFORMES Clupeidae Platanichthys platana Native Engraulididae Lycengraulis grossidens Native CYPRINIFORMES Cyprinidae Ctenopharingodon idella Non-native Native from Asia, this species has been introduced for aquaculture activities Cyprinus carpio Non-native Native from Asia, this species has been introduced for aquaculture activities Hypophthalmichthys nobilis Non-native Native from Asia, this species has been introduced mainly for aquaculture activities CYPRINDONTIFORMES Anablepidae Jenynsia eirmostigma Native Endemic to high elevation streams in the Basaltic Plateau where the headwa- ters of the Antas and Upper Uruguay rivers are situated (Malabarba et al., 2009) Poecilidae Cnesterodon brevirostratus Native Restricted to small streams and wetlands in high elevation areas; it is not endemic to the Taquari-Antas basin (Malabarba et al., 2009) Cnesterodon sp. Native Undescribed species. Occurs in small streams at high elevation areas; probably not endemic to the Taquari-Antas basin (Malabarba et al., 2009) Phalloceros caudimaculatus Native Braz. J. Biol., 2013, vol. 73, no. 1, p. 79-90 83 Becker, FG. et al. Table 1. Continued... Taxon Origin Comments GYMNOTIFORMES Gymnotidae Gymnotus aff. carapo Native Albert and Crampton (2003) restricted the distribution of Gymnotus carapo to the Amazon and Orinoco basins, coastal rivers of the Guianas and the Parnaíba and Itapicuru rivers in northeastern Brazil. There are undescribed species in the Patos Lagoon basin, including the one in the Taquari-Antas basin. It is possibly a new species in the G. carapo group Gymnotus chimarrao Native Sternopygidae Eigenmannia trilineata Native LABRIFORMES Cichlidae Australoheros sp. Native Undescribed species (Rican and Kullander (2006) Australoheros taura Native Endemic to the Taquari-Antas basin (Ottoni and Cheffe, 2009) Crenicichla lepidota Native Crenicichla punctata Native Geophagus brasiliensis Native Gymnogeophagus gymnogenys Native Gymnogeophagus labiatus Native Oreochromis niloticus Non-native Introduced for aquaculture, it has escaped or sometimes intentionally released in natural waters PERCIFORMES Centrarchidae Micropterus salmoides Non-native Native to North America, this species was intentionally introduced in the 1980s for sport fishing in fish ponds and streams (Malabarba et al., 2009) Sciaenidae Pachyurus bonariensis Non-native This species is native to the Paraná-Paraguay (Casatti, 2003). It is presently found as a non-native species in the Patos Lagoon basin (see Dufech and Filaho, 2007). SALMONIFORMES Salmonidae Onchorynchus mykiss Non-native Native to North America, this species was intentionally introduced in the 1980s for sport fishing in high elevation streams (Malabarba et al., 2009) SILURIFORMES Aspredinidae Bunocephalus erondinae Native Pseudobunocephalus Native iheringii Auchenipteridae Glanidium sp. Native Comparative studies of the lower Jacuí populations are needed to determine whether this is a new species. Geographically, the closer species is G. catharinensis Miranda-Ribeiro, from Tubarão river, in the state Santa Catarina, southern Brazil Trachelyopterus lucenai Non-native Its original distribution includes the Uruguay river and Patos Lagoon basins. This species was not mentioned in Akama and Sarmento-Soares (2007) because it was considered a synonym of Parauchenipterus porosus (Eigenmann and Eigenmann, 1888) in Akama (2004). Callichthyidae Corydoras paleatus Native Hoplosternum littorale Native Heptapteridae Heptapterus mustelinus Native Heptapterus sp. Native Pimelodella australis Native Rhamdella eriarcha Native 84 Braz. J. Biol., 2013, vol. 73, no. 1, p. 79-90 Fishes of the Taquari-Antas river Table 1. Continued... Taxon Origin Comments Rhamdia quelen Native We keep the use of Rhamdia quelen until conclusive studies about the populations of this genus are available Ictaluridae Ictalurus punctatus Non-native This north-american catfish was introduced in fish ponds for fish production and escaped into natural waters Loricariidae Ancistrus brevipinnis Native Ancistrus sp. Native Eurycheilichthys sp. 1 Native Undescribed species, with distribution restricted to the Taquari-Antas basin; it is known only from the Fão river (R. E. Reis, personal communication) Eurycheilichthys sp. 2 Native Undescribed species, potentially endemic to the Taquari-Antas basin (see Reis and Carvalho, 2007) Eurycheilichthys sp. 3 Native Undescribed species, with geographical distribution restricted to the Taquari-Antas basin; it is known only from the Prata river (R. E. Reis, personal communication) Eurycheilichthys sp. 4 Native Undescribed species, with geographical distribution restricted to the Taquari-Antas basin; it is known only from the upper Guaporé river (R.E. Reis, personal communication) Eurycheilichthys sp. 5 Native Undescribed species, potentially endemic to the Taquari-Antas basin (see Reis and Carvalho, 2007) Eurycheilichthys sp. 6 Native Undescribed species, potentially endemic to the Taquari-Antas basin (see Reis and Carvalho, 2007) Eurycheilichthys sp. 7 Native Undescribed species, potentially endemic to the Taquari-Antas basin (see Reis and Carvalho, 2007) Hemiancistrus punctulatus Native Hisonotus armatus Native Hisonotus carreiro Native Endemic to the Taquari-Antas basin (Carvalho and Reis, 2011) Hisonotus prata Native Endemic to the Taquari-Antas basin (Carvalho and Reis, 2011) Hisonotus vireo Native Hypostomus aspilogaster Native Hypostomus commersonii Native Loricariichthys anus Native Pareiorhaphis hystrix Native Rineloricaria baliola Native Rineloricaria cadeae Native Rineloricaria malabarbai Native Rineloricaria Native microlepidogaster Rineloricaria strigilata Native Pimelodidae Parapimelodus nigribarbis Native Pimelodus pintado Native Pseudopimelodidae Microglanis cottoides Native Trichomycteridae Homodiaetus anisitsi Native Ituglanis sp. Native First record of this genus in the Patos Lagoon basin (J. Ferrer) Scleronema sp. Native Scleronema sp. is known only from two records in the Taquari-Antas basin; it is different from other species known in Rio Grande do Sul Trichomycterus sp.1 Native Undescribed species, potentially endemic to the Taquari-Antas basin; known only from the Turvo and Prata sub-basins (J. Ferrer) Trichomycterus sp.2 Native Undescribed species (J. Ferrer) Trichomycterus sp.3 Native Undescribed species (J. Ferrer) Braz. J. Biol., 2013, vol. 73, no. 1, p. 79-90 85 Becker, FG. et al. Table 1. Continued... Taxon Origin Comments Trichomycterus sp.4 Native Undescribed species (J. Ferrer) Trichomycterus tropeiro Native Endemic to the headwaters of the Taquari-Antas basin (Ferrer and Malabarba, 2011), it occurs only in elevations > 1000 m SYNBRANCHIFORMES Synbranchidae Synbranchus marmoratus Native Table 2. Proportion of non-native species and proportion of restricted range species occurring in the Taquari-Antas basin. Restricted range species have total geographical distribution of less than 10.000 km2 (sensu Nogueira et al., 2010). Non-native species (geographic origin) n % total species Neotropical (South America) 6 5.1 Other regions (Asia, North America, Africa) 7 5.9 Total 13 10.9 Restricted range species n % (total native species) Distribution in the Taquari-Antas and adjacent river basins 7 6.6 Endemic or potentially endemic to the Taquari Antas basin1 16 15.1 Total (restricted distribution) 23 21.7 1Distribution status of undescribed species needs confirmation from further studies. The fish fauna of the Taquari-Antas presents a relatively the MCN, MCP and UFRGS. From 2000 to 2011, several clear distribution pattern across the three geomorphological new species occurring in the basin were described (e.g, sections of the basin (Figure 4). Most species (58%) are Silva, 2004; Rodriguez and Reis, 2008; Carvalho et al., typically distributed in lowland rivers and streams, but 2008; Carvalho and Reis, 2009; Cognato et al., 2009; Ottoni about half of these species had at least a few records and Cheffe, 2009; Menezes and Ribeiro, 2010; Ferrer and (<30% of total specific records) in the Mid-slope valleys Malabarba, 2011; Menezes and Weitzman, 2011), but there and in the Plateau. A typical fish fauna is also found are few studies and publications on ecology, reproductive in the Plateau (20% of total native species), including biology or conservation (Guadagnin et al., 1998; Majolo, 16 species for which all records were located in this 2005; Alves and Fontoura, 2009; Hirschmann et al., 2008; geomorphological section. In the transition between Luz-Agostinho et al., 2010). the Plateau and the Lowlands - i.e., the Mid-slopes The number of species in the Taquari-Antas basin section - there is an overlap in the distribution of lowland represents ca. 65% of the total number of known species for the Patos Lagoon basin (160 species, including species and headwater species, with few typical species 35 undescribed species; Malabarba et al., 2009). The (9.5% of total species). Only 12.4% of all native species number of native species in physiographically similar and were relatively common in the three geomorphological geographically close river basins varies from 51 (Pardinho sections (e.g., Bryconamericus iheringii, Characidium river, Patos Lagoon basin; Ribeiro and Köhler, 2007) to pterostictum, Geophagus brasiliensis, Gymnotus aff. carapo, 79 (Maquiné river, in the Tramandaí river system; F. G. Hyphessobrycon luetkenii, Phalloceros caudimaculatus). Becker, unpublished data) and 89 (Sinos river, Patos Lagoon basin; Leal et al., 2009). However, a proper comparison 4. Discussion is not possible because these studies used distinct survey According to our survey, knowledge about the fishes methods and because the studied watersheds vary in total of the Taquari-Antas basin was relatively poor until the area and ecological integrity. late 1990s, and consisted of several records in museum The proportion of undescribed species in the Taquari- databases (the oldest record in the examined collections Antas is relatively large (23.6%) and similar to estimates for dates from 1977; 62% of the collection records were the whole Patos Lagoon and Uruguay river basins (21.9% sampled after 1999), and descriptions of species with and 22.2%, respectively; Malabarba et al., 2009). It is geographical distributions that included the region (e.g., particularly important to note that part of these undescribed Malabarba, 1989; Buckup, 1993; Malabarba and Mahler species are small headwater fish (e.g. Eurycheilichthys Junior, 1998; Cardoso and Malabarba, 1999). In the late and Trichomycterus), with potentially small geographic 1990s, fish sampling was intensified as part of baseline ranges, reinforcing the previous observations of a highly studies for environmental impact assessments (EIA), which underestimated diversity in the region (Malabarba et al., are demanded by the State and Federal environmental 2009). As noted by Ferrer and Malabarba (2011), all the agencies (FEPAM and IBAMA) in Brazil. Vouchers of highly endemic species described to the basaltic highlands most of these samples are now kept in the fish collections of (which include the Taquari-Antas mid-slope rivers and 86 Braz. J. Biol., 2013, vol. 73, no. 1, p. 79-90 Fishes of the Taquari-Antas river Figure 2. Locations of fish sample sites (n = 519; circles may represent more than one site) in the Taquari-Antas basin, and position of the hydroelectric power plants (>0.5 MW) in operation or in different construction stages in early 2011 (black squares). Arrows indicate the three main dams in the basin (UHE = hydroelectric power plant). Figure 3. Records of migratory species in the Taquari-Antas basin. The Cachoeirão is a short stretch of the main channel of the Antas river with strong rapids and used to be considered a possible obstacle to several species. It is presently situated between the Castro Alves and Monte Claro dams. Braz. J. Biol., 2013, vol. 73, no. 1, p. 79-90 87 Becker, FG. et al. headwater streams) have been discovered and described in Antas basin, in face of the high potential for increase in the last 20 years. It is also interesting that some undescribed the number of dams for hydroelectric power production species of Astyanax are widely distributed across adjacent and for land transformation (forestry and agriculture) in river basins, but at least two are potentially endemic to the upper sections of the basin. areas within the Taquari-Antas basin. The non-native species represented a relevant proportion The main distribution of the migratory species in the (10.9%) of the total species registered in the basin, however Antas river seems to be limited upstream by the strong information on their abundance, population dynamics rapids known as “Cachoeirão”, as previously noted by and on their impacts on the native biota is still lacking. Luz-Agostinho et al. (2010). However, these species About half of the non-native species are original from were represented by few records in our survey (except for non-Neotropical regions; some of these were introduced P. pintado) and were not effectively sampled before the in fish ponds for aquaculture production and escaped construction of the main dams in the Antas river (14 de into natural habitats (e.g. Cyprinus carpio, Ictalurus Julho, Monte Claro and Castro Alves, in the early 2000s; punctatus and Oreochromis niloticus), while others were Figure 3). The “dourado”, Salminus brasiliensis, probably released directly into streams and rivers for sport fishing used to be present in upper reaches of the basin, as suggested (the black bass, Micropterus salmoides, and the rainbow by occurrence data determined by Alves and Fontoura (2009) trout, Onchorynchus mykiss, particularly in streams of the from interviews with fishermen. The migratory status of basaltic plateau). Results from a fish monitoring program Pimelodus pintado is still not well established (Alves and with extensive sampling between 2002-2009 indicated that Fontoura, 2009), but its reproductive behavior could be non-native species occur only in low abundances in the similar to Pimelodus maculatus. The latter species migrates mid-lower Taquari-Antas, and evidence for reproductive for long-distances, but is abundant in serially impounded populations has been indirectly suggested only for C. carpio rivers, as the Tietê and Grande rivers (Agostinho et al., (Luz-Agostinho et al., 2010). Some of the Neotropical 2007), probably being able to reproduce in shorter free non-natives were probably unintentionally introduced river stretches (Agostinho et al., 2003). via inter-basin man-made connections resulting from land We registered a high proportion of species with small management for agriculture (rice fields), and eventually geographical ranges (ca. 10000 km2 in range, following dispersed rapidly and reached high abundances in different Nogueira et al., 2010), either endemic to the Taquari-Antas parts of the Patos Lagoon basin (e.g. Pachyurus bonariensis basin or not (Table 2). These numbers were based on and Trachelyopterus lucenai, see Becker, 2002; Saccol- recent publications (see Table 1) and on-going taxonomic Pereira et al., 2006; Becker et al., 2007; Dufech and Fialho, investigations (J. Ferrer; V. A. Bertaco; R. E. Reis), and add 2007). We found museum records (MCP) for Tilapia another 11 species to those already listed by Nogueira et al. rendalli collected in fish ponds in the late 1970s, however (2010). Most of these species occur in the upper portions of there was no record of this species in natural waters at the the basin (only in the Plateau or also in the Mid-slopes and Taquari-Antas basin. valleys), as Eurycheilichthys spp. and Trichomycterus spp.. Considering the results of the present inventory, At least one species is known only from its type locality conservation in the Taquari-Antas basin should consider (Bryconamericus ecai, Silva, 2004) despite the extensive at least the following three components of the fish fauna. sampling in the basin. Because restricted range species One aspect is to protect habitat for migratory fish (including are potentially more susceptible to environmental impacts the endangered Salminus brasiliensis), which can only be and to extinction, they should be considered as targets for accomplished if some rivers receive no more dams. An assessments in conservation planning and environmental example is the Guaporé river, which seems to function as licensing. This is particularly relevant in the Taquari- an alternative reproductive area after the damming of the Taquari-Antas river (Luz-Agostinho et al., 2010). A second point is the protection or restoration of streams and rivers containing restricted range and endemic species, which requires an effort for formal description of these species and their geographical ranges. The third point is taking action to prevent the escapement of non-native species from fish ponds or their deliberate in natural waters, particularly where restricted range and endemic species are present. Acknowledgements – We would like to thank Marco A. Azevedo for providing access to the the MCN collection records and to Luiz Roberto Malabarba and João Paulo Miranda for providing access to the UFRGS fish collection database. Adriano Cunha (Biolaw) kindly provided information on several fish records from the studied region. Dolores Pineda and Sílvia Pagel provided access to data from the environmental database of FEPAM. Ana Luiza Matte and Bruna Arbo Meneses Figure 4. Percent distribution of native fish species (n = 105) helped in data management and in checking the geographical in the main geomorphological sections of the Taquari-Antas coordinates of fish records. Collections made by F. G. Becker basin. In All sections, we included species occurring in the were made under authorization of the Instituto Brasileiro do three geomorphological sections and with more than 30% Meio Ambiente e dos Recursos Naturais Renováveis (IBAMA; records in at least two of them. License n. 1870068). 88 Braz. J. Biol., 2013, vol. 73, no. 1, p. 79-90