Population biology of Trichomycterus sp. (Siluriformes, Trichomycteridae) in Passa Cinco stream, Corumbataí River sub-basin, São Paulo State, southeastern Brazil
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Data
2009-08-01
Autores
Rondineli, GR. [UNESP]
Carmassi, AL. [UNESP]
Braga, Francisco Manoel de Souza [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Instituto Internacional de Ecologia
Resumo
O objetivo deste trabalho foi caracterizar a população de Trichomycterus sp. do rio Passa Cinco com relação à estrutura em comprimento, proporção sexual, dieta e aspectos reprodutivos de acordo com os períodos de seca e cheia e gradiente longitudinal, bem como analisar sua condição corporal na dimensão temporal. Seis amostragens, fazendo uso do equipamento de pesca elétrica, foram realizadas em três pontos distintos do Rio Passa Cinco, contemplando trechos de ordem dois, três e quatro nos meses de maio, julho, setembro e novembro de 2005 e janeiro e março de 2006. Foram capturados 341 indivíduos, sendo: 203 machos, 99 fêmeas e 39 imaturos. O menor indivíduo capturado, um exemplar imaturo, apresentou 28 mm de comprimento padrão e o maior, um macho, 85 mm. Não houve variação significativa nos graus de repleção e de gordura acumulada na cavidade visceral dos exemplares analisados entre os períodos considerados. Onze diferentes itens alimentares foram encontrados nos conteúdos estomacais. Considerando todo o período de amostragem, larvas de Diptera foram um item preferencial e os demais itens ingeridos, ocasionais. Os testes de Spearman e Friedman não encontraram diferenças significativas na dieta de Trichomycterus sp. entre períodos e pontos amostrais, respectivamente. A fecundidade absoluta média foi de 73 ovócitos, sendo a desova do tipo parcelada. Tanto os machos quanto as fêmeas de Trichomycterus sp. apresentaram diferenças significativas em suas condições corporais nos períodos considerados e, no período de cheia, os peixes apresentaram melhores condições.
The aim of this work was to characterise the population of Trichomycterus sp. in Passa Cinco stream, regarding length structure, sex ratio, diet and reproductive aspects, in accordance with drought and rainy season periods and longitudinal gradient, as well as to analyse its corporal condition in a temporal dimension. Six samplings were accomplished with the use of electric fishing equipment in three different sites in Passa Cinco stream, contemplating sites of order two, three and four, during the months of May, July, September and November of 2005; and January and March of 2006. Three hundred and forty one individuals were captured, composed of 203 males, 99 females and 39 immatures. The smallest captured individual, an immature, presented 28 mm of standard length and the largest, a male, 85 mm. There was not significant variation in repletion degree and accumulated fat in the visceral cavity of the individuals analysed during the considered periods. Eleven different food items were found in the stomach contents. Considering the whole sampling period, immature Diptera was a preferential item and other items were found as occasionally ingested. Spearman and Friedman tests did not find significant differences in the diet of Trichomycterus sp. in the periods and sampling sites, respectively. The average of absolute fecundity was of 73 oocytes, and the parceled type of spawning was performed. Both males and females of Trichomycterus sp. presented significant differences in their corporal conditions in the considered periods, and in the rainy season, these fishes were in better condition.
The aim of this work was to characterise the population of Trichomycterus sp. in Passa Cinco stream, regarding length structure, sex ratio, diet and reproductive aspects, in accordance with drought and rainy season periods and longitudinal gradient, as well as to analyse its corporal condition in a temporal dimension. Six samplings were accomplished with the use of electric fishing equipment in three different sites in Passa Cinco stream, contemplating sites of order two, three and four, during the months of May, July, September and November of 2005; and January and March of 2006. Three hundred and forty one individuals were captured, composed of 203 males, 99 females and 39 immatures. The smallest captured individual, an immature, presented 28 mm of standard length and the largest, a male, 85 mm. There was not significant variation in repletion degree and accumulated fat in the visceral cavity of the individuals analysed during the considered periods. Eleven different food items were found in the stomach contents. Considering the whole sampling period, immature Diptera was a preferential item and other items were found as occasionally ingested. Spearman and Friedman tests did not find significant differences in the diet of Trichomycterus sp. in the periods and sampling sites, respectively. The average of absolute fecundity was of 73 oocytes, and the parceled type of spawning was performed. Both males and females of Trichomycterus sp. presented significant differences in their corporal conditions in the considered periods, and in the rainy season, these fishes were in better condition.
Descrição
Palavras-chave
dieta, reprodução, fecundidade, condição corporal, diet, reproduction, fecundity, corporal condition
Como citar
Brazilian Journal of Biology. Instituto Internacional de Ecologia, v. 69, n. 3, p. 925-934, 2009.