Resumo
Taunayia bifasciata (Eigenmann & Norris, 1900) is a small catfish that inhabits headwater streams of the Tietê and Paraíba do Sul river basins, southeastern Brazil, being restricted to the Atlantic rain forest. The species is found on lists of threatened species of Brazil and the state of São Paulo. Despite that, there is no literature information about the biology of the species. In the present study we endeavored to collect data on the biology of T. bifasciata. A total of 37 specimens were captured in two streams, Piracuama and Oliveiras. Of those, 22 were females, 14 were males and 1 specimen was immature. Adults with mature gonads were captured in all samples excepting the last, suggesting that T. bifasciata has a long reproductive season. The average fecundity was 319 oocytes/female (range 173-504), with diameters ranging from 0.183 to 2.135 mm. Seven different food items were found in the stomach contents of our subjects. Terrestrial insects and immature Plecoptera were the most frequent and most important food items in the diet of T. bifasciata
Resumo
Taunayia bifasciata (Eigenmann & Norris, 1900) is a small catfish that inhabits headwater streams of the Tietê and Paraíba do Sul river basins, southeastern Brazil, being restricted to the Atlantic rain forest. The species is found on lists of threatened species of Brazil and the state of São Paulo. Despite that, there is no literature information about the biology of the species. In the present study we endeavored to collect data on the biology of T. bifasciata. A total of 37 specimens were captured in two streams, Piracuama and Oliveiras. Of those, 22 were females, 14 were males and 1 specimen was immature. Adults with mature gonads were captured in all samples excepting the last, suggesting that T. bifasciata has a long reproductive season. The average fecundity was 319 oocytes/female (range 173-504), with diameters ranging from 0.183 to 2.135 mm. Seven different food items were found in the stomach contents of our subjects. Terrestrial insects and immature Plecoptera were the most frequent and most important food items in the diet of T. bifasciata
Resumo
Taunayia bifasciata (Eigenmann & Norris, 1900) is a small catfish that inhabits headwater streams of the Tietê and Paraíba do Sul river basins, southeastern Brazil, being restricted to the Atlantic rain forest. The species is found on lists of threatened species of Brazil and the state of São Paulo. Despite that, there is no literature information about the biology of the species. In the present study we endeavored to collect data on the biology of T. bifasciata. A total of 37 specimens were captured in two streams, Piracuama and Oliveiras. Of those, 22 were females, 14 were males and 1 specimen was immature. Adults with mature gonads were captured in all samples excepting the last, suggesting that T. bifasciata has a long reproductive season. The average fecundity was 319 oocytes/female (range 173-504), with diameters ranging from 0.183 to 2.135 mm. Seven different food items were found in the stomach contents of our subjects. Terrestrial insects and immature Plecoptera were the most frequent and most important food items in the diet of T. bifasciata
Resumo
The aim of this work was to study the diet of the scienid fishes Menticirrhus americanus and Cynoscion jamaicensis. The degree of association between the diets of the two species was investigated, since both species coexist in the southeastern coast of Brazil. The food preference degree method (GPA) was employed to stomachs with level 3 of repletion. The stomachs of 306 specimens were analyzed, being 233 of M. americanus and 73 of C. jamaicensis. The food items found in the stomachs of M. americanus were crustaceans, fishes, polychaets, and mollusks. Fishes and crustaceans were found in the stomachs of C. jamaicensis. The use of the same food items by the two species can contribute for an indicative of feeding overlap. The food preference of M. americanus for crustaceans and of C. jamaicensis for fishes can minimize this overlap, making possible a coexistence of these scienid in the study area. The obtained result is in accordance with the characteristics regarding mouth position and foraging sites used by both species: M. americanus has sub-terminal mouth and forages on the bottom, whereas in C. jamaicensis, the mouth is terminal, making it possible to forage in the upper of the water column.
O objetivo deste trabalho foi estudar a alimentação dos cienídeos Menticirrhus americanus e Cynoscion jamaicensis e verificar o grau de associação de suas dietas, visto que ambas as espécies coexistem no litoral sudeste do Brasil. O método do grau de preferência alimentar (GPA) foi aplicado aos estômagos com grau de repleção 3. Foram analisados os estômagos de 306 exemplares, sendo 233 de M. americanus e 73 de C. jamaicensis. Os itens alimentares encontrados nos estômagos de M. americanus foram crustáceos, peixes, poliquetas e moluscos e naqueles de C. jamaicensis, peixes e crustáceos. O consumo de iguais itens alimentares pelas duas espécies pode ter contribuído para o indicativo de sobreposição alimentar. A preferência alimentar de Menticirrhus americanus por crustáceos e de Cynoscion jamaicensis por peixes pode minimizar tal sobreposição, possibilitando a coexistência desses cienídeos na área estudada. Os resultados apresentados vão ao encontro das informações relativas ao posicionamento da abertura bucal e ao local em que o alimento é explorado: M. americanus apresenta boca subterminal e alimenta-se no fundo, enquanto, em C. jamaicensis, a boca é terminal, possibilitando a exploração de alimento no estrato superior da coluna dágua.
Resumo
The aim of this work was to study the diet of the scienid fishes Menticirrhus americanus and Cynoscion jamaicensis. The degree of association between the diets of the two species was investigated, since both species coexist in the southeastern coast of Brazil. The food preference degree method (GPA) was employed to stomachs with level 3 of repletion. The stomachs of 306 specimens were analyzed, being 233 of M. americanus and 73 of C. jamaicensis. The food items found in the stomachs of M. americanus were crustaceans, fishes, polychaets, and mollusks. Fishes and crustaceans were found in the stomachs of C. jamaicensis. The use of the same food items by the two species can contribute for an indicative of feeding overlap. The food preference of M. americanus for crustaceans and of C. jamaicensis for fishes can minimize this overlap, making possible a coexistence of these scienid in the study area. The obtained result is in accordance with the characteristics regarding mouth position and foraging sites used by both species: M. americanus has sub-terminal mouth and forages on the bottom, whereas in C. jamaicensis, the mouth is terminal, making it possible to forage in the upper of the water column.
O objetivo deste trabalho foi estudar a alimentação dos cienídeos Menticirrhus americanus e Cynoscion jamaicensis e verificar o grau de associação de suas dietas, visto que ambas as espécies coexistem no litoral sudeste do Brasil. O método do grau de preferência alimentar (GPA) foi aplicado aos estômagos com grau de repleção 3. Foram analisados os estômagos de 306 exemplares, sendo 233 de M. americanus e 73 de C. jamaicensis. Os itens alimentares encontrados nos estômagos de M. americanus foram crustáceos, peixes, poliquetas e moluscos e naqueles de C. jamaicensis, peixes e crustáceos. O consumo de iguais itens alimentares pelas duas espécies pode ter contribuído para o indicativo de sobreposição alimentar. A preferência alimentar de Menticirrhus americanus por crustáceos e de Cynoscion jamaicensis por peixes pode minimizar tal sobreposição, possibilitando a coexistência desses cienídeos na área estudada. Os resultados apresentados vão ao encontro das informações relativas ao posicionamento da abertura bucal e ao local em que o alimento é explorado: M. americanus apresenta boca subterminal e alimenta-se no fundo, enquanto, em C. jamaicensis, a boca é terminal, possibilitando a exploração de alimento no estrato superior da coluna dágua.