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

We compiled data on fish fauna of the Ivaí River basin from recent specialised literature, standardised sampling and records of species deposited in fish collections. There were 118 fish species of eight orders and 29 families. Of these, 100 species are autochthonous (84.8%), 13, allochthonous (11.0%) and five, exotic (4.2%). The main causes for the occurrence of non-native species are escapes from aquaculture, introduction for fishing purposes and the construction of the Itaipu hydroelectric plant. The predominance of small and medium-sized Characiformes and Siluriformes, including 13 species new to science, accounts for approximately 11.0% of all species and 13.0% of all native species. About 10.2% of all species and 12.0% of all native species are endemic to the upper stretch of the Ivaí River, isolated by numerous waterfalls in tributary rivers and streams. The Ivaí River basin is subjected to various anthropogenic interferences such as pollution, eutrophication, siltation, construction of dams, flood control, fisheries, species introduction and release of fingerlings. These activities raise concerns about biodiversity of Brazilian inland waters especially regarding the fish fauna; the basin of the Ivaí River already has species classified in categories of extinction risk: Brycon nattereri and Apareiodon vladii (Vulnerable) and Characidium heirmostigmata and Steindachneridion scriptum (Endangered). The high species richness of native fish, endemism of some, high environmental heterogeneity, high risk of extinction and lack of knowledge of several other species along with the eminent human activities raise the need to enrich the scientific knowledge for future conservation efforts for the studied basin.


Introduction
Of the Brazilian basins, the Paraná River basin is the second largest drainage area after the Amazon basin (Stevaux et al. 1997, Galves et al. 2009).According to Agostinho et al. (2007), the upper section of the Paraná River is the most investigated with regards to Brazilian freshwater fish.This stretch covers water systems that cross the states of Goiás, Minas Gerais, São Paulo, Mato Grosso do Sul and Paraná.
In the latter, it extends to the upstream region of the city of Guaíra, formerly Sete Quedas, now submerged by the Itaipu lake.
Studies on fish of the upper Paraná River basin have increased in recent years but are still mainly concentrated in basins of the São Paulo State (Langeani et al. 2007).Although these authors have surveyed the number of species with records in the upper Paraná River basin and totaled 310 valid species and 50 likely new species, a study performed by Galves et al. (2009) on the fish fauna surveys of the main tributaries of the upper Paraná River basin indicated a gap of these studies in relation to the Ivaí River basin, which is an important left bank tributary of the Paraná River, in the Paraná State.
There are only few surveys on fish fauna in the Ivaí River basin, especially for the tributaries, Barra Bonita River (Maier et al. 2008), Bonito River (Viana et al. 2013), some streams located in the Perobas Biological Reserve (Delariva & Silva 2013) and a first-order stream in the municipality of Marialva (Araújo et al. 2011); and there are few genetic studies with some species of Loricariidae (Zawadzki et al. 2004, Portela-Castro et al. 2007, Paiva et al. 2013) or ecological studies (Luiz et al. 2003, Luiz et al. 2005) and description of new species (Graça & Pavanelli 2008, Roxo et al. 2014, Tencatt et al. 2014, Zawadzki et al. 2016) with fish of this basin.
This study aims to provide a compilation of data on the diversity of the fish fauna of the Ivaí River basin from recent specialised literature, standardised sampling and records of species deposited in fish collections.In addition, endemism and threats to the species are discussed.

Study area
A dense drainage network with many tributaries composes the watershed of the Ivaí River, the second largest in the Paraná State, located at the geographical coordinates 22º56'17' ' -25º35'27'' S and 50º44'17'' -53º41'43'' W (Destefani 2005).The Ivaí River is a left bank tributary of the Paraná River in the Paraná State and has 35,845 km 2 drainage area, which is approximately 685 km in length (Maack 1981).This river is formed in the municipality of Ivaí by the confluence of the rivers Patos and São João (Santos et al. 2008), both in the State Park of Serra da Esperança, on the border between the second and third plateau of the Paraná State (Maack 1981).
The Ivaí River basin has different geological and geomorphological characteristics, since it runs through different lithologies and drains distinct morphological and topographical environments (Destefani 2005).In this way, this author has defined three sections for the basin considering the geology, geomorphology, topography and slope: upper, middle and lower stretches (Figure 1).
The upper section is the longest with about 440 km and has the highest slopes of the whole basin, especially from the source of the Patos River until its confluence with the São João River; also there are rapids and waterfalls due to the type of geological substrate formed by sedimentary rocks, which, according to Maack (1981), promote a stepped relief formed by ridges.By crossing the slope of the Serra da Esperança, the Ivaí River enters the third plateau and flows upon basaltic rocks, giving rise to the middle section, which is approximately 170 km.In this section, the slope is much smaller, with a less energetic relief; there are small and shallow waterfalls as well as important rapids as the Ferro and Índio rapids, intercalated by backwaters of gentle slope (Destefani 2005).The lower section is the floodplain and is approximately 164 km in length.Therein, the river flows over sandstones of the Caiuá formation and of alluvial sediments, with a very small slope of 20 meters until flowing into the Paraná River (Destefani 2005).
Other studies show some physical characteristics of each part of the Ivaí River basin, such as altitude, temperature and rainfall.Paiva (2008) stated that the altitude in the upper section of this basin has, on average, 800 m, but it can reach up to 1,250 m, in the middle stretch, the average altitude is 500 meters, and in the lower reaches, 250 m, on average.Ichiba (2006) reports the average annual temperatures for each section of the basin: 18ºC for the upper reaches, 20ºC in the middle and 22ºC in the lower reaches.The research of Sousa (2006) determined the average annual rainfall for the same sections: 1,800 mm for the upper reaches, 1,600 mm in the middle and 1,400 mm for the lower reaches.

Database
The list of species for the Ivaí River basin was developed by consulting the material deposited in the fish collections of the Universidade Estadual de Londrina, Londrina (MZUEL); Museu de Zoologia da Universidade de São Paulo, São Paulo (MZUSP); Museu de História Natural Capão da Imbuia, Curitiba (MHNCI), Museu de Ciências e Tecnologia da PUCRS, Porto Alegre (MCP) and the Coleção Ictiológica do Nupélia, Maringá (NUP), which are available at http:// splink.cria.org.br.This list was compared with the species listed for the upper Paraná River basin in Langeani et al. (2007).Species with doubtful occurrence or identification were reviewed by experts.
To complement the information, recent collections were conducted under the permission #14028-1 (Sistema de Informação e Autorização em Biodiversidade -Sisbio, Instituto Chico Mendes de Conservação da Biodiversidade) in 21 streams of the upper reaches of the basin, the region with the lowest number of samples.The origin of each species was determined according to by Langeani et al. (2007), in which autochthonous species are native to the upper Paraná River basin, the allochthonous species were introduced from other basins belonging to the Neotropical region and the exotic were introduced from other continents.The origin of each species were obtained from Reis et al. (2003), Langeani et al. (2007), Graça & Pavanelli (2007) and Julio Júnior et al. (2009), which compile data of several long-term studies carried out by the Nupélia -Universidade Estadual de Maringá.
Threat level was determined in accordance with the Portaria do Ministério do Meio Ambiente Nº 445, of December 17 th , 2014 and changed by Nº 98, of April 28 th , 2015, which recognize species of fish and aquatic invertebrates of Brazilian fauna threatened with extinction classified in the following categories: Extinct in the Wild (EW), Critically Endangered (CR), Endangered (EN) and Vulnerable (VU).For endemism determinations, some species were considered as restricted to the basin by Graça & Pavanelli (2008), Roxo et al. (2014), Tencatt et al. (2014), Zawadzki et al. (2016) and personal communications from Cláudio H. Zawadzki (UEM); other species were considered endemic by means of analysis and comparison of data obtained with comparative material from adjacent basins.

Results
There were 118 fish species registered in the Ivaí River basin (Table 1) belonging to eight orders and 29 families (Table 2).The most species-rich orders are Siluriformes and Characiformes (Table 1), with 51 and 48 species, respectively (Table 2).Together, they represent 83.9% of all species registered.The richest families are Loricariidae and Characidae with, respectively, 24 and 20 species (Table 2), representing approximately 37.2% of the species.

Discussion
The ichthyofauna of the Ivaí River basin, comprised of 118 species, has an alpha diversity superior to that of all other river systems confined to the Paraná State.There are 110 species in the Tibagi River basin (Shibatta et al. 2002), 76 in the Pirapó River basin (Pagotto et al. 2012), 62 in the Piquiri River basin (Gubiani et al. 2006), 54 in the Jordão River basin (Frota et al. in prep.) and 48 in the Areia river basin (Frota et al. in prep.).The Iguaçu River basin, another important system in the Paraná State, although not completely comprised in it, lacks a complete inventory, but Baumgartner et al. (2012) found in its lower stretch 106 species, an amount similar to that of the Ivaí River as a whole.Other comparable systems within the upper Paraná River basin for which inventories are available show similar species richness.The Mogi Guaçu River has about 135 species (Meschiatti & Arcifa 2009, Oliveira et al. 2009), and the Corumbá Reservoir and its influence area, 119 (Pavanelli et al. 2007).The upper Paraná floodplain harbors 182 fish species, a number considerably higher than that observed in the Ivaí River basin, but that region also presents a higher habitat diversity (Graça & Pavanelli 2007).
In the headwaters of the Ivaí River, there is a predominance of small and medium-sized (15 cm or less in length) Characiformes and Siluriformes.As already highlighted by Viana et al. (2013) in their study of the Bonito River, backwaters separated by rapids typically bear a wide variety of microhabitats.Those environments favour species with greater ability to stay in the water column (e.g., Astyanax and Bryconamericus), as well as benthic species equipped with spines that allow them to attach to rocks and resist the water flow (e.g., loricariids and Trichomycterus).On the other hand, higher-order waterbodies have greater water volume and light incidence, which result in increased primary production and greater availability of resources (Ferreira et al. 2010).Thus, the lower reaches of the Ivaí River basin bear large-sized pelagic (e.g., the characiforms Salminus and Leporinus) and benthic (e.g., the siluriforms Pseudoplatystoma and Steindachneridion) species.
In addition, higher-order streams offer a wider array of food items, which allows the coexistence of several trophic guilds ranging from detritivores and planktivores to piscivores, also contributing to their species richness (Ferreira et al. 2010).
The proportion of new species in relation to the total observed in the Ivaí River basin (11.0%) is close to the 14.4% reported by Langeani et al. (2007) for the entire upper Paraná River.Of the new species from the Ivaí River, only five are not endemic, and have already been recognized as so in previous studies performed in other river systems (e.g., Graça & Pavanelli 2007).That shows how poorly known the Ivaí River basin is and that the sampling of low-order streams can reveal unknown species even in a relatively well-sampled river basin such as that of the upper Paraná River.The identification of areas of endemism is extremely important considering that they compose basic geographic units that allow understanding of the evolution of complex regional biota (Morrone 1994) and that should be prioritised for biodiversity conservation (Löwenberg-Neto & Carvalho 2004).Historical biogeography may explain this endemism as a result of speciation processes caused by the emergence of geographic barriers mainly in the upper reaches of the basin, located on the Serra da Esperança.Maack (1981) stated that this mountain range is part of the Triassic-Jurassic relief and corresponds, among other basins, to areas draining the headwaters of the Ivaí River.The sandy and clayey rocks of the geological formations that underlie the Serra da Esperança, combined with the dense drainage network, allow the development of a very uneven relief, with altitudes up to 1,200 m (Maack 1981).Thus, tectonism imposed deformations to the basis, forming some local inflections on the ground, as the Ponta Grossa Arch, and had close relationship with the basaltic effusion in the Mesozoic.Because of these orogenetic features, in that region there are numerous waterfalls, some over 50 meters high, such as Saltos São João and São Francisco (Maack 1981).According to Ribeiro (2006), the formation of some of the Paraná State river basins was strongly affected by the origin of the Ponta Grossa Arch, which may have had an influence on speciation processes.
According to IUCN (2012), the categories Vulnerable and Endangered contain species to which the best available evidence indicates they are at, respectively, high and very high risk of extinction in the wild.Environments with species listed in these categories should be prioritized in terms of conservation.It is therefore important to create more Conservation Units and National Plans that focus the full protection of these sites, such as stretches of the upper Ivaí River basin where most records of Characidium heirmostigmata (Endangered), Apareiodon vladii and Brycon nattereri (vulnerable) were made.Additionally, for many species there is no adequate information to assess, directly or indirectly, the risk of extinction, therefore more studies are necessary to determine a more appropriate threat classification.Agostinho et al. (2005) provided alarming data on the habitat conditions of Brazilian freshwater species and listed the main causes of biodiversity loss: pollution, eutrophication, siltation, construction of dams, flood control, fisheries and species introduction.This is also true for the Ivaí River basin (Affonso et al. 2015).In its drainage area, there are nearly one million inhabitants, of which only 36% have domestic sewage treatment (Paraná 2010).Also contributing to the pollution of its waters, the area comprises virtually no conservation units and little riparian vegetation due to the intensive use of the soil for agriculture and cattle raising (Paraná 2010).These activities greatly contribute to the siltation of the waterbodies, which was observed in the sites sampled herein and by Viana et al. (2013), and lead to destruction of native vegetation that provide important food items in the diet of some species.
Hydropower enterprises threaten fish biodiversity by controlling the hydrological regime and changing the longitudinal distribution of the species (Petry et al. 2011).This affects the reproductive success of the migratory species by influencing the timing, duration and intensity of floods and droughts (Pelicice et al. 2015).In the last few years, several projects for building hydroelectric plants of different proportions in the Ivaí River basin have been put forward.Those projects were received with apprehension not only by ecologists (Affonso et al. 2015), but also by communities that would be directly affected by their implantation.By demonstrating that the number of new, endemic and threatened species in the Ivaí River is greater than previously imagined, the present paper reinforces the need to promote popular manifestations against those dams.
Although overfishing is not a major problem in the Ivaí River basin, sport fishing contributes to the accidental or intentional introduction of species.In that basin, escapes from fish farms and invasion from the lower Paraná River basin also contribute to the presence of non-native species.Among the ones observed in the Ivaí River basin, few have been studied for their potential of invasion and possible antagonistic interactions with native species.That is the case of Plagioscion squamosissimus, which has been demonstrated to consume the same food items as other piscivores in the upper Paraná flodplain and thus, to be a probable competitor (Pereira et al. 2015).Similar studies are not available for Micropterus salmoides, but the fact that this species is also a piscivore indicate that it also has a potential to affect negatively native species from the Ivaí River.This calls for a close observation upon invasive species, as in the study of Pelicice & Agostinho (2009), who reported on the relationship between the expansion of Cichla kelberi Kullander & Ferreira in the Rosana Reservoir and the decline of fish communities associated with macrophyte stands.Although this species is absent from the Ivaí River Basin, a similar threat may be posed by M. salmoides and P. squamosissimus.
An activity that has become quite common in the Ivaí River is the careless release of thousands of fingerlings of the species of sport fishes, e.g.Leporinus spp., Piaractus mesopotamicus, Pseudoplatystoma spp., Prochilodus spp.and Salminus spp.Although welcomed by the population, this practice is stated by Agostinho et al. (2007) as frequently inefficient (because the river was devoid of its ancestral capacity of supporting large fish populations) or even harmful to the natural populations.It potentially causes loss of genetic diversity and of important alleles selected along many years by their advantages to the survival of the species in that particular habitat, as well as introduction of new pathogens and parasites (Agostinho et al. 2010).Thus, until those actions are carried out based on a large body of knowledge on the life history and population genetics of the species that are being reintroduced, they will continue to be no more than a waste of public money and an additional threat to the native species, as well as a deceiving electoral strategy.
From the results obtained, it becomes evident the need for efforts to preserve the Ivaí River basin, given its high environmental heterogeneity, high species richness, endemism and high risk of extinction of some species.In addition, the lack of information on biology and ecology of various species and the eminent human activities that affect much of the waterbodies in the basin, raise the need for continuity of studies on fish fauna in this basin.

Figure 1 .
Figure 1.Map of the Ivaí River basin, showing the most thoroughly sampled sites (green dots).Each dot may correspond to more than one collection site.Limits between upper, medium and lower sections are represented by red triangles.

Figure 3 .
Figure 3. Graphic showing the percentages of the origins of species in the Ivaí River basin.

Table 1 .
Ichthyofauna from the Ivaí River basin: species, voucher specimens, origin of each species, threat level and endemism.The symbol # refers to species added to the list due to personal observation.The asterisk (*) represents endemic species.

Table 2 .
Number of species in the Ivaí River basin, sorted by Order and Family.