Environmental diagnosis of water quality in situ and ex situ in streams in Upper Paraná River Basin, Brazil

The aim of this study was to (i) evaluate water quality using limnological parameters in three streams belonging to the Ivinhema River basin, (ii) investigate the composition and structure of the landscape around the locations sampled and their possible contribution to changes in water quality, (iii) investigate genotoxicity in fish in situ as environmental bioindicators, and (iv) evaluate the cytotoxic and genotoxic potential of water through bioassays in animal and plant models. A total of seven fish species were sampled in situ as bioindicators of environmental toxicogenetic damage: Astyanax fasciatus, Astyanax lacustris, Cyphocharax modestus, Moenkhausia forestii, Piabina argentea, Psellogrammus kennedyi, and Hypostomus ancistroides. Four types of nuclear and one cytoplasmic alteration were observed, with nuclear invagination being the most frequent. Animal bioassays showed five types of nuclear and one cytoplasmic alteration. In the plant bioassay, a reduction in germination and cell division was observed, indicating the cytotoxic and genotoxic effects of the water for Allium cepa cells. Thus, genotoxic alterations in fish and plant bioassays may reflect the different types of land use and cover around streams and the conversion of forest fragments into agricultural areas, mainly due to the expansion of sugarcane crops. The evaluation of the toxicogenetic status of the three streams is essential to emphasize the need to create projects to recover the native vegetation cover, which would improve the quality of the habitat and ensure the permanence of native species.

UNA NUEVA ESPECIE DE TRINIBACULUM (MONOGENEA: DACTYLOGYRIDAE) PARÁSITO DE LAS BRANQUIAS DE ASTYANAX FASCIATUS (CUVIER, 1819) (CHARACIFORMES: CHARACIDAE) EN UN RÍO NEOTROPICAL, ESTADO DE SÃO PAULO, BRASIL

Una nueva especie de Monogenea Trinibaculum pinctiarum n. sp. fue reportada parasitando las branquias de Astyanax fasciatus, conocido popularmente como "lambarí de rabo rojo", capturado en el río Paranapanema, reservatorio Jurumirim, São Paulo, Brasil. La nueva especie se asigna al género Trinibaculum por la presentación de una barra ventral doble y la apertura vaginal dextrolateral. Esta es la segunda especie, junto con T. altiparanae, perteneciente a este género que parasita las branquias de los peces del género Astyanax. Esta especie se parece con T. altiparanae en las partes del haptor y la presencia de la vagina distal con el bulbo, pero difiere por tener: (1) un órgano copulador masculino enrollado, (2) pieza accesoria en forma de pinza, (3) proceso posteroventral ausente en la barra dorsal, (4) ganchos con el pulgar deprimido. La filogenia hipotética de especies de Trinibaculum (Índice de Consistencia = 87%, Índice de Retención = 80%, longitud = 16) sobre la base de 13 series de transformación es (Trinibaculum rotundus (T. brazilensis (T. altiparanae, Trinibaculum pinctiarum n. sp.))). Esta hipótesis se corrobora con la actual filogenia de los peces characiformes. Además en este estudio se presenta una nueva clave de identificación para las especies del género Trinibaculum basada en caracteres morfológicos.

UHE MACHADINHO E ICTIOFAUNA: IMPACTOS AO LONGO DOS DEZ PRIMEIROS ANOS APÓS A SUA CONSTRUÇÃO

O objetivo deste trabalho foi investigar as alterações ocorridas na assembleia de peixes ao longo dos dez anos subsequentes à formação do reservatório da UHE de Machadinho, região do Alto Rio Uruguai. Para tal, realizaram-se coletas com periodicidade sazonal entre 2002 e 2011. Ao total, foram capturados 41.168 indivíduos, distribuídos em 7 ordens, 21 famílias, 43 gêneros e 65 espécies. A ictiofauna do reservatório foi dominada por espécies oportunistas, sedentárias e de pequeno porte, sobretudo lambaris e mandis - Astyanax fasciatus e Parapimelodus valenciennis – que somaram mais de 48% dos indivíduos capturados. Quanto à biomassa, o piscívoro Acestrorhynchus pantaneiro foi a espécie mais capturada, possivelmente favorecido pelo aumento populacional de espécies forrageiras. A presença de espécies migradoras foi rara, refletindo a ausência de trechos lóticos bem estruturados para garantir os diferentes habitats necessários para que estas espécies completem seu ciclo de vida. De uma forma geral, as curvas de k-dominância indicaram uma comunidade de peixes moderadamente perturbada ao longo de todo período de estudo. Quanto às mudanças temporais, a análise de agrupamento indicou alterações graduais da ictiofauna: evidentes reflexos dos impactos iniciais causados pelo barramento já no ano de 2002; nova desestabilização da assembleia causada por fatores abióticos em 2006; tendência de estabilização no reservatório nos últimos cinco anos monitorados.

Food ecology and presence of microplastic in the stomach content of neotropical fish in an urban river of the upper Paraná River Basin

Plastic is a useful material; but along with its benefits also come several disadvantages. One of these is the consequences of the improper discarding of plastic in the environment and its eventual fragmentation into microplastics. Plastic can reach rivers and affect their biota as microparticles from its degradation. The entry of plastic into the food chain occurs by the consumption of fish or other organisms. Furthermore, persistent organic pollutants can accumulate, and the consumption of materials containing plastic pollutants can cause several physiological problems in animals. Such pollutants can reach man when water or fish is consumed. There are numerous studies in the marine environment that show that microplastics significantly interfere with marine biota; but there are relatively few studies addressing this topic in freshwater environments. This work characterized the diet of the most abundant fish species in an urban river of the Upper Paraná Brazil Watershed, investigating the occurrence of microplastic. As much as the studied river suffers from urban river syndrome, a wide variety of food consumed by fish was found. The stomach content of 220 individuals belonging to fourteen species was analyzed. In the stomach content analysis, 16 types of food items were found, most of them autochthonous. The species analyzed were grouped into four trophic categories, with iliophage as dominant one. The presence of microplastics was found in 2% of the studied individuals, two individuals of the species Rhamdia quelen, one specimen of Hoplosternum littorale and one specimen of Astyanax fasciatus.

Detection of natural hybridization and delimitation of two closely related operational taxonomic units of the Astyanax fasciatus (Teleostei: Characidae) complex through integrative approaches

Astyanax is a species-rich, non-monophyletic genus composed of several supraspecific taxa that are poorly delimited. The Astyanax fasciatus complex is one of these taxa and shows high taxonomic complexity. To elucidate the evolutionary history of the A. fasciatus complex from southern South America, we conducted cytogenetic, molecular and morphological analyses in specimens from the Uruguay River basin. Cytogenetic characters demonstrated two closely related operational taxonomic units: Astyanax sp. 1 (8m+22sm+10st+6a), Astyanax sp. 2 (8m+24sm+10st+4a) and natural hybrids (8m+23sm+8st+5a). 5S ribosomal DNA sites were found in two pairs of m chromosomes and one pair of a chromosomes in Astyanax sp. 1, two pairs of a chromosomes and one pair of m chromosomes in Astyanax sp. 2, and three m chromosomes and three a chromosomes in hybrids. As51 sites were found in three chromosomes in Astyanax sp. 1 and in five chromosomes in Astyanax sp. 2 and hybrids. Mitochondrial sequence analyses did not separate the two units and hybrids. Morphological analyses revealed differences between Astyanax sp. 2 and hybrids. This secondary contact with gene flow between lineages that diverged long ago might slow or reverse the differentiation/speciation process. These results help us to understand the evolutionary history of this highly complex clade of Astyanax in southern South America.

A new species of Creptotrematina (Trematoda: Allocreadiidae) from characid fishes of Brazil: morphological and molecular data

A new species of Creptotrematina Yamaguti, 1954 was collected from characid fishes, Astyanax fasciatus (Cuvier, 1819) and Astyanax lacustris Lucerna & Soares, 2016 from the Batalha River in the State of Sao Paulo, Brazil. The new species most closely resembles Creptotrematina aguirrepequenoi, but differs by the elongated shape of vitelline follicles, the extension of these follicles in the posterior end of body and the fact that they are not confluent. The morphological differences were confirmed through molecular data. Three specimens were sequenced, and molecular analyses were based on the internal transcribed spacers 2 and D1–D3 domains of the 28S ribosomal RNA gene. The obtained topologies showed the new species as a sister taxon of C. aguirrepequenoi, a species originally described from Astyanax mexicanus in Mexico, and later found in Astyanax aeneus in Costa Rica. Isolates of the new species are reciprocally monophyletic, and genetic distance values are similar to those observed in other species pairs within Allocreadiidae. These findings corroborate that the genus Creptotrematina is mostly a parasite of characids, and widely extended across the Americas, with representative species occurring between Argentina and northern Mexico.