Mitochondrial D-loop nucleotide diversity in Astyanax (Osteichthyes, Characidae) from the upper Paraná and upper Paraguay River basins.

The morphological discrimination between the species Astyanax altiparanae and A. asuncionensis of the upper Paraná River and Paraguay River basins, respectively, has always been difficult. Two D-loop haplogroups of A. altiparanae are known, one with the presence (AltoPR) or the absence (AltoPR-D) of a 32-bp block similar to that in A. asuncionensis. We examined these samples to characterize A. altiparanae and verify whether A. asuncionensis occurred in the upper Paraná River prior to the submergence of the Sete Quedas Falls when Itaipu reservoir was impounded. D-loop sequences were analyzed in A. altiparanae of the upper Paraná and Iguaçu Rivers and those of A. asuncionensis of the upper Paraguay River. The haplogroup AltoPR was found at all sites of the upper Paraná and Iguaçu Rivers, whereas AltoPR-D occurred in the Itaipu reservoir, floodplain and in the Tietê and Grande Rivers. Two haplogroups of A. asuncionensis were identified and both did not have the 32-bp block. However, AltoPR and AltoPR-D differed from one another in 5.1% of their bases and between 8.9 and 12.5% with regard to the haplogroups of the upper Paraguay basin. Further, AltoPR-D occurred in the Grande River upstream the Marimbondo Falls and other older reservoirs than Itaipu. The results reject the hypothesis of the establishment of A. asuncionensis and suggest that the haplogroup AltoPR-D existed in the upper Paraná River before the impounding of the Itaipu reservoir. Moreover, morphological similarity and high genetic variation within the altiparanae/asuncionensis group suggest the existence of a cryptic species complex.

Effects of the hydrological regime on the ichthyofauna of riverine environments of the Upper Paraná River floodplain.

In this work, spatial and temporal variations in the diversity (species richness and Simpson's Diversity Index) and abundance (indexed by the capture per unit effort--CPUE; total and for reproductive groups) of fish from three rivers (Baía, Ivinheima and Paraná) located in a floodplain of the Upper Paraná River basin were analyzed over a period of 20 years (1987-2007). In addition, we evaluated the relationships of these ecological attributes with variations in the hydrologic regime, considering the possible effects of natural (climatic events) and artificial (discharge control by dams) disturbances. Annual variations in hydrometric attributes were calculated using PULSO software and daily water level data. We applied analysis of covariance to determine the relationships between ecological and hydrometric attributes, the latter summarized in axes of a principal component analysis. Lower values of the fish assemblage attributes (diversity and abundance) were registered in the Paraná River. Species richness, total CPUE and CPUE of long-distance migratory species were positively related to the duration of the floods and the connectivity of the area. Variations in the annual hydrological cycle and their effects on fish assemblage appear to be affected by extreme natural (ENSO) and artificial (discharge control by dams) events.

Effects of the hydrological regime on the ichthyofauna of riverine environments of the Upper Paraná River floodplain / Efeitos do regime hidrológico sobre a ictiofauna de ambientes fluviais da planície de inundação do Alto Rio Paraná

In this work, spatial and temporal variations in the diversity (species richness and Simpson's Diversity Index) and abundance (indexed by the capture per unit effort - CPUE; total and for reproductive groups) of fish from three rivers (Baía, Ivinheima and Paraná) located in a floodplain of the Upper Paraná River basin were analyzed over a period of 20 years (1987-2007). In addition, we evaluated the relationships of these ecological attributes with variations in the hydrologic regime, considering the possible effects of natural (climatic events) and artificial (discharge control by dams) disturbances. Annual variations in hydrometric attributes were calculated using PULSO software and daily water level data. We applied analysis of covariance to determine the relationships between ecological and hydrometric attributes, the latter summarized in axes of a principal component analysis. Lower values of the fish assemblage attributes (diversity and abundance) were registered in the Paraná River. Species richness, total CPUE and CPUE of long-distance migratory species were positively related to the duration of the floods and the connectivity of the area. Variations in the annual hydrological cycle and their effects on fish assemblage appear to be affected by extreme natural (ENSO) and artificial (discharge control by dams) events.

Nesse trabalho foi avaliada a variação espaço-temporal na diversidade (riqueza de espécies e Índice de Diversidade de Simpson) e abundância (indexada pela captura por unidade de esforço - CPUE; total e por grupo reprodutivo) de espécies de peixes de três rios (Baía, Ivinheima e Paraná), localizados na planície de inundação do Alto Rio Paraná, ao longo de 20 anos (1987-2007). Ainda, avaliamos as relações desses atributos ecológicos (diversidade e abundância) à variação anual do regime hidrológico, considerando a influência de distúrbios naturais (eventos climáticos) e artificiais (regulação hidrológica por barragens). Para representar a variação anual do regime hidrológico de cada rio, foram utilizados os atributos hidrométricos calculados pelo programa PULSO, a partir de medidas do nível hidrométrico diário. Análise de covariância foi aplicada para avaliar a relação entre os atributos ecológicos das assembléias de peixes e a variação no regime hidrológico, esta sumarizada em eixos de uma análise de componentes principais. A riqueza de espécies, a CPUE total e a de migradores de longa distância foram relacionadas positivamente à duração das cheias e conectividade, sendo que o Rio Paraná apresentou os menores valores médios desses atributos. Dessa forma, as variações constatadas no ciclo hidrológico anual e seus reflexos sobre a estrutura das assembléias de peixes do rio Paraná parecem decorrer do efeito combinado de eventos naturais (El Niño - ENSO) e artificiais (controle da vazão pelas barragens).

Ichthyofauna from the Emas National Park region: composition and structure.

The relationship between habitats and the ichthyofauna composition in the Parque Nacional das Emas (PNE) and adjacent areas (the Araguaia and Sucuriú rivers) are provided and could be applied in determining the Park's future zoning. Samples of the ichthyofauna and limnological parameters were obtained during both dry (September 1999) and wet (December 1999) seasons. Ichthyofauna collections resulted in the capture of 4,740 specimens of 22 species. The most abundant species in the Araguaia River during the two sampling seasons were Astyanax sp. 2 and Hasemania sp. In the Sucuriú River and PNE, Astyanax scabripinnis cf. paranae and Hoplias aff. malabaricus were the most frequent species. The largest number of species and diversity index were recorded for the Araguaia River. However, sound management policies require more detailed studies on the fish communities of the Cerrado biome.

Ichthyofauna from the Emas National Park region: composition and structure

Com o objetivo de obter informações básicas para o futuro zoneamento do Parque Nacional das Emas (PNE), foram realizadas amostragens ictiofaunísticas e de parâmetros limnólógicos durante o período de seca (setembro/1999) e de chuvas (dezembro/1999) em estações de coletas localizadas no interior do Parque e em áreas adjacentes (rios Araguaia e Sucuriú). Foram capturados 4.740 indivíduos, distribuídos em 22 espécies. Entre as espécies mais abundantes destacam-se Astyanax sp. 2 e Hasemania sp. no rio Araguaia e Astyanax scabripinnis cf. paranae e Hoplias aff. malabaricus no rio Sucuriú e PNE. A maior diversidade de espécies foi constatada para o rio Araguaia. Entretanto, para que medidas de manejo possam ser tomadas de forma criteriosa, estudos ecológicos mais detalhados das comunidades de peixes do cerrado devem ser conduzidos.

Ichthyofauna from the Emas National Park region: composition and structure

The relationship between habitats and the ichthyofauna composition in the Parque Nacional das Emas (PNE) and adjacent areas (the Araguaia and Sucuriú rivers) are provided and could be applied in determining the Park's future zoning. Samples of the ichthyofauna and limnological parameters were obtained during both dry (September 1999) and wet (December 1999) seasons. Ichthyofauna collections resulted in the capture of 4,740 specimens of 22 species. The most abundant species in the Araguaia River during the two sampling seasons were Astyanax sp. 2 and Hasemania sp. In the Sucuriú River and PNE, Astyanax scabripinnis cf. paranae and Hoplias aff. malabaricus were the most frequent species. The largest number of species and diversity index were recorded for the Araguaia River. However, sound management policies require more detailed studies on the fish communities of the Cerrado biome.

Com o objetivo de obter informações básicas para o futuro zoneamento do Parque Nacional das Emas (PNE), foram realizadas amostragens ictiofaunísticas e de parâmetros limnólógicos durante o período de seca (setembro/1999) e de chuvas (dezembro/1999) em estações de coletas localizadas no interior do Parque e em áreas adjacentes (rios Araguaia e Sucuriú). Foram capturados 4.740 indivíduos, distribuídos em 22 espécies. Entre as espécies mais abundantes destacam-se Astyanax sp. 2 e Hasemania sp. no rio Araguaia e Astyanax scabripinnis cf. paranae e Hoplias aff. malabaricus no rio Sucuriú e PNE. A maior diversidade de espécies foi constatada para o rio Araguaia. Entretanto, para que medidas de manejo possam ser tomadas de forma criteriosa, estudos ecológicos mais detalhados das comunidades de peixes do cerrado devem ser conduzidos.

Diversity and genetic distance in populations of Steindachnerina in the upper Paraná river floodplain of Brazil.

Whereas four species of the genus Steindachnerina occur in the Paraná river basin, S. insculpta was the only endemic species of the region under analysis, which is the third lower section of the upper Paraná river. Among other factors, this species has been characterised by the absence of spots in the basal region of the dorsal fin. However, various specimens with this characteristic appeared in the region after the construction of the Itaipu Hydroelectric Plant in 1982. An analysis of the genetic variability of Steindachnerina populations with or without spots is provided. Specimens were collected in different sites of the floodplain of the upper Paraná river and samples were compared by random amplified polymorphic DNA (RAPD) technique and morphological analyses. Ninety-eight amplified loci with nine random primers were analysed in 19 specimens of each phenotype. Data for genetic distance showed great divergences between the two phenotypes and indicate two different species. Spotted specimens may be identified as S. brevipinna, found in the region downstream Sete Quedas Falls. The species must have overcome the geographical barrier during the building of the Itaipu hydroelectric dam that submerged the waterfalls and which became an obstacle between the upper and middle Paraná river some 150 km downstream. Since phenotypes do not share dominant alleles, absence of gene flow has been suggested.

Dental development and ontogenetic diet shifts of Roeboides paranensis pignalberi (osteichthyes, Characinae) in pools of the upper Rio Paraná floodplain (state of Paraná, Brazil).

Species of the characid genus Roeboides are known for their habit of tearing off and ingesting scales from other fishes. Specimens of Roeboides paranensis were taken monthly from March 1992 through February 1993 in five pools of the upper Rio Paraná floodplain and in one site in the Rio Paraná itself, with the aim of relating the dental development to ontogenetic diet shifts. Between 15-22 mm SL, fish had teeth with hypertrophied bases (mammiform) that moved to the outside of the mouth in both maxillas. During ontogeny, the diet shifted, with the smallest individuals eating more microcrustaceans and the larger ones eating more scales. Lepidophagy is non-obligatory, because the ingestion of insects and other invertebrates occurred at all sizes. Spatial variation in diet was large, however diet similarity was great for Roeboides from three floodplain pools that had similar proportions of the main diet categories.

[Cytologic diagnosis of stomach neoplasms]. / Contributo alla diagnosi citologica delle neoplasie gastriche

Personal experience in the cytological diagnosis of gastric neoplasis acquired in a series of 104 patients is presented. Three false positives were detected in 29 cases of supposed malignancy and 11 false negatives in 75 patients with tumours thought to be benign. Cytology often proved the determining factor in the planning of surgery, while in some instances it also gave an indication of the histological type involved.