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Ecological niche modelling (ENM) has been used to quantify the potential occurrence of species, by identifying the main environmental factors that determine the presence of species across geographical space. We provide a large-scale survey of the distribution of ostracod species in South America, by using the domains of 25 river basins. From 221 known ostracod species, we estimate the potential distribution of 61 species, using ENM. Ten clusters of potential distribution patterns were found. Clusters 8 and 9 grouped most of the species, which presented high similarity of niche between them. Heterocypris paningi Brehm, 1934 (group 1) obtained higher niche variability. The minimum temperatures of the coldest month and the mean elevation of the river basin were most important to predict the potential distribution of ostracods of most groups. South America has a complex pattern of elevation, which affects species distributions indirectly through changes in local factors. For instance, the Andes mountains might impose a barrier for ostracod distribution in the southern part of South America because of the low temperatures and precipitation. The ENM indicated that some regions and/or basins of South America might be susceptible to the entry of several ostracod species, presently absent, including non-native species.

Made available in DSpace on 2019-10-06T16:17:07Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-06-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Climate change threatens freshwater fish by severely modifying water quality and hydrological dynamics, hence altering the species distribution. We assessed the climate change effects on the geographical distribution of Salminus brasiliensis, a keystone species of economic interest in the La Plata River basin. Using ecological niche models, we estimated the species range in the present time and assessed the range shift phenomena through climatically suitable areas in the future. We also quantified the predictive uncertainty from niche models, atmosphere–ocean general circulation models, and carbon emission scenarios. Our predictions indicated a great range contraction of S. brasiliensis in the future. The south-central portion of the basin should retain the climate refuge function for the species at 2050. Nonetheless, the segregation of this climate refuge in two smaller parts was predicted at the end of the century. Our study also revealed that the greatest source of uncertainty in forecasts of species range shifts arises from using alternative niche algorithms in modeling process. Our results contribute to more effective measures for conservation of S. brasiliensis, thus helping to ensure the ecosystem processes and socioeconomic activities in the basin dependent on this species. Programa de Pós-graduação em Ecologia de Ambientes Aquáticos Continentais. Núcleo de Pesquisas em Limnologia Ictiologia e Aquicultura - Nupelia Universidade Estadual de Maringá (UEM), Av. Colombo 5790 Programa de Pós-graduação em Ecologia – Universidade Federal de Juiz de Fora Instituto de Ciências Biológicas- ICB, Campus Universitário, Bairro São Pedro Departamento de Zoologia Instituto de Biociências de Rio Claro Universidade Estadual Júlio Mesquita Filho – UNESP Programa de Pós-Graduação em Ecologia e Evolução Universidade Federal de Goiás Universidade Estadual de Mato Grosso do Sul – UEMS Departamento de Zoologia Instituto de Biociências de Rio Claro Universidade Estadual Júlio Mesquita Filho – UNESP CNPq: 141371/2016-1

This study investigated the assemblages attributes (composition, abundance, richness, diversity and evenness) and the most representative genera of Odonata, Anisoptera at Água Boa and Perobão Streams, Iguatemi River basin, Brazil. Both are first order streams with similar length that are impacted by riparian forest removal and silting. Quarterly samplings were conducted from March to December 2008 in the upper, intermediate and lower stretch of each stream. The Mantel test was used to check the influence of spatial autocorrelation on the Odonata composition. Spatial variations in the composition were summarized by the Principal Coordinates Analysis (PCoA) using Mantel test residuals. The effects of spatial correlation on richness and abundance were investigated by the spatial correlogram of Moranʼs I coefficients. The most representative genera in each stream were identified by the Indicator Value Method. The spatial variations in the attributes of the assemblages were assessed using analysis of variance of null models. We collected 500 immature individuals of 23 genera and three families. Among the attributes analyzed only the composition and abundance showed significant spatial differences, with the highest mean abundance found in the Perobão Stream. Miathyria and Zenithoptera were the indicator genera of the Água Boa Stream and Erythrodiplax, Libellula, Macrothemis, Progomphus and Tramea were the indicator genera of the Perobão Stream.

The genus Astyanax is relatively common and encompasses various similar taxa forming a highly complex group that is difficult to precisely delimit. The present study aims to analyze cytogenetically and morphologically specimens of A. altiparanae belonging to distinct populations of the Iguatemi River Basin, Mato Grosso do Sul State, Brazil, for a better understanding of the evolutionary processes in this fish group. This study analysed 32 specimens of Astyanax altiparanae from Iguatemi River basin, MS, Brazil: 24 from the Agua Boa stream and 8 from the Santa Maria stream. All specimens showed a diploid number equal to 50 chromosomes with differences in the karyotypic formula and types of chromosomes bearing the NOR between the two localities. The constitutive heterochromatin showed interstitial markings evident in the region of some chromosomes in both populations. In the morphometric analysis, the first three axes were retained for interpretation which together explained 81% of variance, showing morphometric distinction between populations. Chromosomal and morphometric data obtained may be useful for taxonomic and phylogenetic studies in this group of fish.

This study uses species distribution modeling and physiological and functional traits to predict the impacts of climate change on native freshwater fish in the Murray-Darling Basin, Australia. We modelled future changes in taxonomic and functional diversity in 2050 and 2080 for two scenarios of carbon emissions, identifying areas of great interest for conservation. Climatic-environmental variables were used to model the range of 23 species of native fish under each scenario. The consensus model, followed by the physiological filter of lethal temperature was retained for interpretation. Our study predicts a severe negative impact of climate change on both taxonomic and functional components of ichthyofauna of the Murray-Darling Basin. There was a predicted marked contraction of species ranges under both scenarios. The predictions showed loss of climatically suitable areas, species and functional characters. There was a decrease in areas with high values of functional richness, dispersion and uniqueness. Some traits are predicted to be extirpated, especially in the most pessimistic scenario. The climatic refuges for fish fauna are predicted to be in the southern portion of the basin, in the upper Murray catchment. Incorporating future predictions about the distribution of ichthyofauna in conservation management planning will enhance resilience to climate change.

We described the spatial distribution of fish trophic groups in the Água Boa Stream, MS, Brazil. Specimens were caught using electrofishing in the upper, intermediate and lower stretches of the stream, between March and November 2008. We analyzed 415 stomach contents of 24 species. Detritus/sediment and aquatic invertebrates were the main exploited resources. Ordination analysis categorized the species in six trophic groups. Aquatic invertivores showed the highest richness (10 species), followed by detritivores (08 species), omnivores (03 species), terrestrial invertivores (03 species), algivores (02 species) and herbivore (01 species). Three trophic groups occurred in the upper stretch, six in the intermediate and five in the lower. Detritivores, omnivores and algivores showed the highest density, while detritivores and aquatic invertivores presented the highest biomass. Autochthonous resources were particularly important to the studied fish fauna, especially aquatic invertebrates, so, conservation actions reducing the simplification of the habitat by silting and recovering the riparian forest are essential to maintain the ichthyofauna of the Água Boa Stream.

This study aimed to evaluate population abundance patterns and the main events in the reproductive cycle of Loricariichthys platymetopon at Saraiva Lagoon, Ilha Grande National Park, MS-PR, Brazil. Monthly samplings were conducted from October 2004 to September 2005 in three sections of the lagoon: entrance, middle and end, which resulted in the capture of 175 individuals. Spatial and temporal variation in abundance was obtained through CPUE (number of captured individuals/1000 m² of gillnets in 12 hours). The reproductive tactics considered were: duration, time and location of spawning, oocyte diameter and fecundity. The highest relative abundance was recorded in February, in the middle section of the lagoon, and the reproductive period lasted from September to February. The prevalence of females with spent ovaries and at rest in the following months indicated that reproductive activity ceased during autumn and winter. We observed that reproduction was high at the end section of the lagoon. The recorded mean oocyte diameter was 1.67 (SD ± 0.76) mm, mean absolute fecundity was 962.1 (SD ± 382.48) oocytes, and relative fecundity was 7.60 (SD ± 2.25) oocytes/g and 5.13 (SD ± 0.75) oocytes/cm. These tactics, probably are related to the settlement of L. platymetopom in Saraiva Lagoon, as well as in the different biotopes of the Upper Paraná River floodplain. Este estudo avaliou os padrões de abundância populacional e os principais eventos do ciclo reprodutivo de Loricariichthys platymetopon na lagoa Saraiva, Parque Nacional de Ilha Grande, MS-PR, Brasil. Foram realizadas amostragens mensais de outubro de 2004 a setembro de 2005 em três regiões: entrada, meio e final da lagoa, o que resultou na captura de 175 indivíduos. A variação espaço-temporal na abundância foi avaliada através da CPUE (nº de indivíduos capturados/1000 m² rede em 12 h de exposição). As táticas reprodutivas avaliadas foram duração, época e local de desova, diâmetro de ovócitos e fecundidade. A maior abundância relativa foi registrada em fevereiro, na região média da lagoa e o período reprodutivo estendeu-se de setembro a fevereiro. A prevalência de fêmeas com ovários esgotados e em repouso nos meses subseqüentes indicou que a atividade reprodutiva cessou no outono e inverno. Observou-se que a reprodução foi acentuada na região final da lagoa. O diâmetro médio de ovócitos registrado foi 1,67 (SD ± 0,76) mm, a fecundidade absoluta média 962,1 (SD ± 382,48) ovócitos e a fecundidade relativa 7,60 (SD ± 2,25) ovócitos/g e 5,13 (SD ± 0,75) ovócitos/cm. Essas táticas muito provavelmente, devem estar relacionadas à ocupação da lagoa Saraiva por L. platymetopom, bem como de outros biótopos da planície de inundação do alto rio Paraná.

The genus Eigenmannia belongs to the family Sternopygidae, a monophyletic group of Neotropical electrogenic fish. Eigenmannia trilineata from Iguatemi River basin were analyzed using classical cytogenetic techniques. Chromosomes of this species of Eigenmannia presented a X1X1X2X2 : X1X2Y sex chromosome system, with 2n=31chromosomes for the males and 2n=32 for the females, where the Y is metacentric chromosome originated from Robertsonian translocation. The NORs are located interstitially on the long arm of chromosome pair 10. Constitutive heterochromatin is distributed in very conspicuous blocks at the juxtacentromeric regions acrocentrics chromosomes in the males and females, including the unique large metacentric neo-Y in the males also presented a juxtacentromeric block. The chromosomal data obtained may be useful for the taxonomy and phylogenetic studies in this fish group.

Characidae is one of the predominant fish groups in the Neotropical region with approximately 30 highly diversified subfamilies, probably not representing a monophyletic group. Three Characidae species from the Iguatemi River Basin (Mundo Novo, MS, Brazil) were analyzed: Astyanax bockmanni with 2n=50 chromosomes (6m+20sm+8st+16a), Bryconamericus stramineus with 2n=52 chromosomes (6m+10sm+16st+20a) and Piabina argentea with 2n=52 chromosomes (6m+24sm+12st+10a), all the species showing no differences between male and female karyotypes. The Ag-NORs were located in only a single chromosome pair in the three species. The chromosomal data obtained may be useful for the taxonomy and phylogenetic studies in these fish groups.

This study evaluated the influence of the flood regime of the Cuiaba River on the reproductive dynamics of fish species with different reproductive strategies. Sampling was carried out at ten sites in the basin, between March 2000 and April 2004. The reproductive strategies evaluated were long-distance migrant (LM), short-distance migrant (SM), sedentary with parental care (PC) and sedentary or SM with internal fertilization (IF). Period, duration and intensity of floods were the flooding attributes considered. Duration and time of spawning were evaluated using the index of reproductive activity (IRA), and inferences concerning reproductive allocation were based on the analysis of gonad weight. Reproductive success was evaluated based on the annual catch of young-of-the-year of each species. Reproductive dynamics and flood regime were closely correlated; the reproductive peaks of fishes using all four strategies always preceded flood peaks. Intense floods favoured gonadal development of LM and PC, but were less important for IF. In relation to juvenile survival, the occurrence of floods appeared to be crucial for the strategies of LM, PC and IF, because such floods increased fish survival in the period of initial development. In contrast, SM appeared to be less dependent on floods for reproduction. These results indicate that, except for SM, floods have an important role in the recruitment of species using other reproductive strategies, and influence spawning success as well as juvenile survival. Copyright © 2008 John Wiley & Sons, Ltd.

The present study explored the interaction between the upriver migration of fish and the blockage of their migration routes by dam construction. Specifically, we studied (i) the capacity of migratory fish to locate alternative routes in the presence of an obstacle, and (ii) the behavior of the fish after they were artificially transferred to the reservoir. With the use of the mark-recapture technique (tagging), the study was carried out near Porto Primavera Dam (UHE Engenheiro Sérgio Motta) between 1994 and 1999, a period prior to the closure of the floodgates and the installation and operation of the fish pass facilities. The fish were caught in the dam forebay downstream, marked with LEA type tags, and released upstream (5113 individuals; 14 species) and downstream (1491; 12) from the dam. The recaptures were carried out by local professional and amateur fishermen. A total of 188 individuals (2.8%) were recaptured, mostly the curimba Prochilodus lineatus. Nearly half of the recaptures downstream occurred in tributaries, especially in the Paranapanema River, indicating that in the presence of an obstacle the fish are able to locate alternative migration routes. The remainder stayed in the main channel of the Paraná River, at a mean distance of less than 50 km from the release point. Of the fish released upriver from the dam, approximately half were recaptured downriver. Although the river was only partly dammed, the movement of the fish downriver suggests that they became disoriented after being transferred. Those that remained upriver avoided the reservoir and moved, rather rapidly, toward the lotic stretches farther upstream. From these results it is clear that, in the course of the decision process in installing fish passes, it is necessary to take into account the existence of spawning and nursery areas downriver and upriver from the reservoir. O presente estudo visa explorar a interação entre a migração ascendente de peixes e a obstrução de vias migratórias, pela construção de barragens. Especificamente, foi estudada (i) a capacidade de peixes migradores em localizar rotas alternativas na presença de um obstáculo, e (ii) o comportamento dos peixes após serem transpostos artificialmente para o reservatório. Com o uso da técnica de marcação e recaptura, o estudo foi desenvolvido nas imediações da barragem da hidrelétrica de Porto Primavera, entre 1994 e 1999, período anterior à instalação e operação de mecanismos de transposição. Os peixes foram capturados a jusante, nas imediações da barragem, receberam marcas do tipo "LEA" e foram liberados a montante (5113 indivíduos; 14 espécies) e a jusante (1491; 12) da barragem, sendo as recapturas realizadas por pescadores profissionais e amadores da região. No total, foram recapturados 188 indivíduos (2,8%), a maioria de curimba Prochilodus lineatus. Praticamente metade das recapturas de jusante ocorreram em tributários, especialmente no rio Paranapanema, indicando que na presença de um obstáculo os peixes são capazes de localizar rotas alternativas de migração. O restante permaneceu na calha do rio Paraná, a uma distância média inferior a 50 km do ponto de soltura. Dos peixes liberados a montante da barragem, aproximadamente metade foi recapturado a jusante. Embora o rio estivesse parcialmente barrado na ocasião, a movimentação de peixes em direção a jusante sugere desorientação após a transposição. Aqueles que permaneceram a montante evadiram o reservatório rumo a trechos superiores (lóticos) mais distantes, desempenhando grandes velocidades. Com estes resultados fica claro que no processo decisório sobre a implantação de mecanismos de transposição é preciso considerar a existência de áreas de desova e desenvolvimento inicial a jusante e montante do reservatório.

In this study, we identified and characterized the hydrographic attributes related to the success of recruitment of migratory fishes in the Upper Paraná River floodplain. To achieve our objectives, we analyzed inter-annual variations in the abundance of young-of-the-year (YOY; index of recruitment) of six migratory species and their relations with hydrographic attributes. Recruitment was related to the intensity, duration (in different fluviometrical levels), elasticity, number of pulses, greater uninterrupted overflow and delay of the floods (all obtained using the PULSO software). Collections of fish were conducted in the period between January 1987 and November 2007 in distinct environments (river channels, secondary channels and connected and disconnected floodplain lakes) distributed along three subsystems (Paraná, Baía and Ivinheima). Relations between recruitment and the attributes of interest were determined through analysis of covariance. In the studied period, the highest abundances of YOY were registered in 2007, followed by 1992, 1993, 2005 and 1988. The abundance of YOY was positively correlated with an intensity of high water levels (potamophase) and the duration of potamophase 1 and negatively with the duration of low water levels (limnophase) and a delay of flood. Higher hydrometric levels (540 and 610 cm for Paraná and 325 and 450 cm for Ivinheima) and greatest uninterrupted overflow presented different relations (significant interactions) among subsystems, but all with positive effects on recruitment. Results evidenced that recruitment responded better when floods started in January with potamophase intensities above 610 cm and water levels above 450 cm over a period of 50 days and repeated every two years (or > 610 cm for 38 days and repeated every two or three years). Therefore, artificial control of the floods at intervals of two or three years by manipulating the discharge of dams located upstream from the floodplain in a way that promotes potamophases with the potential to ensure recruitment of migratory species may become an important tool for conservation of migratory fish species in the floodplain.

This work aimed to determine which population features were important to the colonization process of Astyanax altiparanae in the Corumbá Reservoir. The species presented wide spatial-temporal distribution, caught in all months and sites. Higher CPE values were recorded upstream from the reservoir during the filling phase. In this phase, reproductive activity was intense upstream and moderate in the tributaries. However, a fall in abundance of juveniles was observed after the formation of the reservoir. Among the most relevant population features to grant a successful colonization were wide geographic distribution, ability to occupy and spawn in lentic habitats and feeding flexibility.O presente trabalho visa entender quais as características populacionais envolvidas no processo de colonização do Astyanax altiparanae no reservatório de Corumbá. As amostragens foram mensais, de março/1996 a fevereiro/2000, compreendendo as fases pré ((Março/1996-Agosto/1996), enchimento (Setembro/1996-Fevereiro/1997) e pós enchimento (Março/1997-Fevereiro/2000), em 11 estações. A abundância foi obtida através da captura por unidade de esforço (CPUE). As variações espaciais e temporais na reprodução foram determinadas através do índice de atividade reprodutiva. A espécie apresentou ampla distribuição espaço temporal, sendo capturada em todos os meses e locais. Os maiores valores de CPUE foram registrados a montante, durante a fase de enchimento. Al��m disso, nesta fase, a reprodução foi muito intensa a montante do reservatório e moderada nos tributários. Entretanto, constatou-se uma queda na abundância de jovens após a formação do reservatório. Dentre as características populacionais mais relevantes para a colonização, destacam-se a ampla distribuição geográfica, habilidade de ocupar e reproduzir em habitats lênticos, além da flexibilidade alimentar.