Influência do ciclo hidrológico na dieta e estrutura trófica da ictiofauna do Rio Cuiabá, Pantanal Mato-Grossense

Abstract

ABSTRACT. Influence of the hydrological cycle on the diet and trophic structure of the ichthyofauna from the Cuiabá River, Pantanal of Mato Grosso, Brazil. This paper evaluate the influence of the hydrological cycle on the diet and trophic structure of the ichthyofauna from the Pantanal. Samplings were carried out monthly between March 2000 and February 2001, in the Cuiabá River and the Chacororé Lagoon. Analysis of the stomach contents of 58 species determined eight trophic categories. Species of the piscivore, detritivore and lepidophage trophic categories presented little variation in the intake food items and, therefore, they did not contribute to the variation in the composition of the diet in both environments, independently of the hydrological cycle. The effects of the flood pulse were more pronounced in the numerical abundance and biomass of detritivore and omnivore trophic categories and were depended on the environment for piscivore, invertivore, and insectivore. Apparently, specificity of the food items along with the probable high availability of food resources in the studied environments contributed to the low variation due to the hydrological seasonality in the trophic organization of the ichthyofauna. By the increment of the hydrological connectivity, the flood pulse of the Cuiabá River allows the exchange of organisms throughout the system, thus determining the variability in the structure of the trophic categories. KEYWORDS.Feeding, trophic structure, flood pulse, Neotropical fishes. RESUMO.Este estudo teve como objetivo avaliar a influência do ciclo hidrológico sobre a dieta e estrutura trófica da ictiofauna no Pantanal. Foram realizadas amostragens mensais entre março de 2000 e fevereiro de 2001, no rio Cuiabá e na lagoa Chacororé. A análise dos conteúdos estomacais de 58 espécies permitiu o reconhecimento de oito categorias tróficas. Peixes das categorias piscívora, detritívora e lepidófaga foram os que apresentaram menor variação na composição da dieta em ambos os ambientes, independente do período hidrológico. Os efeitos do pulso de inundação foram pronunciados na abundância numérica e na biomassa das categorias detritívora e omnívora, enquanto variações nestes parâmetros apresentaram-se relacionadas ao tipo de ambiente para as categorias piscívora, invertívora e insetívora. Os resultados sugeriram que tanto a especialização por alguns itens alimentares quanto a provável elevada disponibilidade de recursos alimentares nos ambientes investigados contribuíram para o fraco efeito do ciclo hidrológico na organização trófica da ictiofauna. Através do aumento da conectividade hidrológica, o pulso de inundação do rio Cuiabá possibilita o deslocamento dos organismos pelo sistema, que deve determinar a variabilidade na estrutura das categorias tróficas. PALAVRAS-CHAVE.Alimentação, estrutura trófica, pulso de inundação, peixes neotropicais.Estudos sobre alimentação da ictiofauna permitem reconhecer categorias tróficas distintas e inferir sobre a estrutura e o grau de importância dos diferentes níveis...

Use of food resources by small fish species in Neotropical rivers: responses to spatial and temporal variations

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Feeding patterns, trophic structure and damming rivers effect: studies applied in freshwater environments in the Brazilian semi-arid region

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Feeding and body condition of an invasive fish species under different environmental conditions

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