Abstract:The aims of this study were to survey the stream fishes of Parque Nacional de Brasília, Federal District, and identify its community structure variation. We sampled streams in the Bananal and Santa Maria/Torto subbasins at Upper Paraná River. Lotic systems in this region are well preserved, as indicated by environmental integrity and the maintenance of native biological components. A total of 8,614 individuals were collected belonging to four orders, nine families, and twenty-eight species (being 11 new to science). The predominant order was Characiformes, followed by Siluriformes. Poecilia reticulata was the only nonnative fish specie found. Astyanax sp. and Hyphessobrycon balbus displayed widest spatial distribution. The most abundant species was Knodus moenkhausii with 64.5% of individuals. Highest fish richness and abundance were found in the wider and deeper stretches.

The aim of this study was to determine the trophic structure of the fish community in the Bananal stream subbasin, which belongs to a well-preserved Cerrado area (Brazilian Savanna) in Brasília National Park, Brazil. We also evaluated the influence of environmental variations in the diet of fish species. Four samples were taken in each 30 m long established transect, two in the rainy season and two in the dry season. A total of 1,050 stomachs of the 13 most abundant species were analyzed. A total of 36 food items were consumed, where 24 were autochthonous, 8 allochthonous, and 4 of undetermined origin. Non-metric multidimensional scaling (NMDS) analysis, in addition to the results of frequency of occurrence and abundance charts, was used to determine four groups of feeding guilds: detritivores, omnivores (tending toward herbivory and invertivory), invertivores and piscivores. Around 69% of the volume of resources consumed was allochthonous, which proves the importance of the resources provided by riparian vegetation. The contribution of autochthonous and allochthonous items in the diet differed due to seasonality for Aspidoras fuscoguttatus, Astyanax sp., Characidium xanthopterum, Hyphessobrycon balbus, Kolpotocheirodon theloura, Moenkhausia sp., Phalloceros harpagos, and Rivulus pictus. Despite the Cerrado climate characteristics, there was no significant influence of season on the fish diet. The absence of seasonal variation and the predominance of allochthonous items in the fish diet are probably associated with the presence of riparian vegetation, which acts as a transition area in the Cerrado biome and provides resources for the aquatic fauna. This work shows the importance of studies in non-disturbed areas considered here as a source of information concerning the biology of fish species and as a guide for direct conservation policies on the management of aquatic resources, recovery of damaged areas and determination of priority areas for conservation.O presente estudo foi desenvolvido com o objetivo de determinar a estrutura trófica da comunidade de peixes da sub-bacia do ribeirão Bananal pertencente a uma área bem preservada de Cerrado no Parque Nacional de Brasília. Além disso, buscou-se verificar a influência das variações ambientais na dieta das espécies. Em cada trecho de 30 m de extensão foram realizadas quatro amostragens, duas no período seco e duas no período chuvoso. Foram analisados 1050 estômagos pertencentes às 13 espécies mais abundantes encontradas. No total, foram consumidos 36 itens alimentares sendo 24 autóctones, oito alóctones e quatro de origem indeterminada. A análise de escalonamento multidimensional não-métrico (NMDS), juntamente com os resultados dos gráficos de freqüência de ocorrência e abundância, agrupou as espécies em quatro guildas: detritívoros, onívoros (com tendência à herbivoria e invertivoria), invertívoros e piscívoros. Cerca de 69% dos recursos consumidos pelos indivíduos foram de origem alóctone, o que evidencia a importância dos recursos advindos das matas de galeria...

Planktonic Turbellaria are of common occurrence in both natural and man-made lakes in Brazil . Experiments were performed in 1987 and 1989 to determine which zooplankton species are consumed by predatory Mesostoma sp. from three natural lakes in the Rio Doce Valley . Experiments were also performed in 1989 with a yet unidentified flatworm from Barra Bonita reservoir . Both predators consumed Daphnia and Ceriodaphnia at a high rate: 4 individuals per day in the case of Mesostoma sp., a large species and 1 .5 ind day -' in the case of the smaller species from Barra Bonita reservoir . Consumption of copepod nauplii, copepodids and adults was much lower, and Ostracoda were not consumed at all . Experiments on food selectivity showed a clear preference by the flatworms for cladocerans .In the lakes studied, flatworms are heavily preyed upon by larvae of Chaoborus and by Mesocyclops species .Turbellaria densities in the natural lakes were around 300 individuals per cubic meter, whereas in Barra Bonita reservoir, 1000 individuals per cubic meter was a mean value in a fifteen days study .

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