Contribuição dos cladóceros como fonte de alimento para os peixes que ocorrem na planície de inundação do Rio Turvo
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Data
2016-08-05
Autores
Paternina, Angélica Maria Otero [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Na presente Tese, foi avaliada a contribuição dos cladóceros como fonte de alimento para os peixes, em seis lagoas marginais da planície de inundação do Rio Turvo- SP em três períodos do ciclo hidrológico da região - seca, intermediário e chuvosa. Para esta avaliação foram analisadas a contribuição dos cladóceros na dieta dos peixes, a composição dos cladóceros no ambiente e as taxas populacionais em cultivo das espécies de cladóceros mais consumidos pelos peixes. Desta forma, os resultados deste estudo são aqui apresentados, organizados em três capítulos: no Capitulo 1, foi estudada a composição e abundância de cladóceros das lagoas marginais, onde foram identificadas 37 espécies de cladóceros, sendo a família Chydoridae a mais representativa, com 16 espécies. Moina minuta foi à espécie que mostrou os maiores valores de abundância relativa nos três períodos estudados. A densidade média dos Cladocera não mostrou diferenças significativas entre os períodos avaliados. No Capitulo 2, foi analisada a dieta dos peixes e os resultados mostraram um amplo espectro alimentar, com um total de 15 itens consumidos, sendo que os cladóceros mostraram uma contribuição de 1 a 6% na dieta dos peixes; foram identificadas 28 espécies de cladóceros no conteúdo estomacal, constituídas principalmente por aquelas da família Chydoridae. O consumo de cladóceros variou significativamente entre os períodos, as espécies Macrothrix paulensis, Chydorus sp., e Alona sp., foram as mais consumidas no período seco, já no período intermediário as espécies Moina minuta e Bosmina tubicen predominaram nos estômagos e, no período chuvoso Diaphanosoma sp. foi a mais consumida. Os peixes consumiram cladóceros independente do habitat que ocupavam indicando que a ictiofauna presente nas lagoas aproveita a disponibilidade deste recurso. No Capitulo 3 foram avaliadas as taxas de crescimento de três espécies de cladócera Diaphanosoma birgei, Moina minuta e Macrothrix paulensis, as quais estavam presentes na dieta dos peixes e nas lagoas marginais. A espécie M. paulensis mostrou os melhores resultados no cultivo, com elevadas densidades, biomassa e produção secundária, e altas taxas de fecundidade. Já a espécie M. minuta apresentou o menor tempo na primeira reprodução e na frequência reprodutiva. A espécie M. paulensis pelas características apresentadas nas taxas de crescimento apresentam características favoráveis para produção de biomassa para alimentação de peixes. Com este estudo podemos concluir que os cladóceros podem representar importante item na dieta dos peixes em lagoas marginais e que estes não parecem selecionar as espécies de cladóceros, mas as consomem de acordo com a disponibilidade. Uma das espécies de cladócero bastante consumida pelos peixes, Macrothrix paulensis apresenta elevado potencial para cultivo para produção e biomassa.
This thesis is dedicated to assess the contribution of cladocerans as a food source to fish in six oxbow lakes of the floodplain in Turvo River -SP in three periods of the hydrological cycle of the region: drought, intermediate, and rainy. In this assessment, the contribution of cladocerans in the fish’s diet was analyzed, the composition of the cladocerans in the environment, and the population rate farming of the species of cladocerans most consumed by the fish. So, the results of this study are presented herein organized in three sections: in Section 1, the composition and abundance of cladocerans in oxbow lakes were studied, and 37 species of cladocerans were identified, being the Chydoridae family the most representative, amounting to 16 species. Moina minuta was the species that showed the highest values of relative abundance in the three periods studied. The average density of Cladocera has not presented substantial differences between the assessed periods. In Section 2, the fish’s diet was analyzed and the results showed a wide food range, amounting to 15 consumed items, and the cladocerans showed a contribution from 1 to 6% in fish’s diet; 28 species of cladocerans were identified in the stomach content, comprised mainly by those of the Chydoridae family. The consumption of cladocerans varied substantially between periods. The following species – Macrothrix paulensis, Chydorus sp., e Alona sp., were the most consumed in the drought period. In the intermediate period, Moina minuta and Bosmina tubicen were the species that prevailed in stomachs. Finally, in the rainy period, Diaphanosoma sp. was the most consumed. Fish consumed cladocerans regardless the habitat they were located, suggesting that the fish fauna present in the lakes exploits the availability of this resource. In Section 3, the growth rate of three species of cladocerans, Diaphanosoma birgei, Moina minuta, and Macrothrix paulensis, were assessed; they were present in fish’s diet and in oxbow lakes. The species M. paulensis showed the best results in the farming, with high densities, biomass, and secondary production, in addition to high fertility rates. On the other hand, the species M. minuta showed the lowest time in the first reproduction and in the reproductive frequency. The species M. paulesnsis, for the characteristics presented in growth rates, presents favorable features for the biomass production in fish feeding. With this study, we can conclude that cladocerans represent an important item in fish’s diet in oxbow lakes, and they do not seem to select species of cladocerans, but they consume them according to the availability. One of the species of cladocerans largely consumed by fish, Macrothrix paulensis, presents a high potential in the farming for production and biomass.
This thesis is dedicated to assess the contribution of cladocerans as a food source to fish in six oxbow lakes of the floodplain in Turvo River -SP in three periods of the hydrological cycle of the region: drought, intermediate, and rainy. In this assessment, the contribution of cladocerans in the fish’s diet was analyzed, the composition of the cladocerans in the environment, and the population rate farming of the species of cladocerans most consumed by the fish. So, the results of this study are presented herein organized in three sections: in Section 1, the composition and abundance of cladocerans in oxbow lakes were studied, and 37 species of cladocerans were identified, being the Chydoridae family the most representative, amounting to 16 species. Moina minuta was the species that showed the highest values of relative abundance in the three periods studied. The average density of Cladocera has not presented substantial differences between the assessed periods. In Section 2, the fish’s diet was analyzed and the results showed a wide food range, amounting to 15 consumed items, and the cladocerans showed a contribution from 1 to 6% in fish’s diet; 28 species of cladocerans were identified in the stomach content, comprised mainly by those of the Chydoridae family. The consumption of cladocerans varied substantially between periods. The following species – Macrothrix paulensis, Chydorus sp., e Alona sp., were the most consumed in the drought period. In the intermediate period, Moina minuta and Bosmina tubicen were the species that prevailed in stomachs. Finally, in the rainy period, Diaphanosoma sp. was the most consumed. Fish consumed cladocerans regardless the habitat they were located, suggesting that the fish fauna present in the lakes exploits the availability of this resource. In Section 3, the growth rate of three species of cladocerans, Diaphanosoma birgei, Moina minuta, and Macrothrix paulensis, were assessed; they were present in fish’s diet and in oxbow lakes. The species M. paulensis showed the best results in the farming, with high densities, biomass, and secondary production, in addition to high fertility rates. On the other hand, the species M. minuta showed the lowest time in the first reproduction and in the reproductive frequency. The species M. paulesnsis, for the characteristics presented in growth rates, presents favorable features for the biomass production in fish feeding. With this study, we can conclude that cladocerans represent an important item in fish’s diet in oxbow lakes, and they do not seem to select species of cladocerans, but they consume them according to the availability. One of the species of cladocerans largely consumed by fish, Macrothrix paulensis, presents a high potential in the farming for production and biomass.
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Palavras-chave
Zooplâncton, Lagoas marginais, Predação, Taxas de crescimento, Zooplankton