摘要

This study investigated the feeding habits of Serrapinnus microdon andS. calliurus and possible seasonal differences (rainy and dry seasons) in the utilization of food. The fish were collected monthly in Cancela stream, in the basin of the Manso/Cuiab芍 rivers in the State of Mato Grosso, from March 2003 to February 2004. Both speciespreferentially consumed resources of autochthonous origin, independently of the season. The diet of S. microdon was basically composed by immature forms of aquatic insects, with Chironomidae and Ephemeroptera predominating during the entire study period, thus showing a restricted diet (Ba = 0.27 in the rainy season, and 0.29 in the dry season). For S. calliurus, aquatic insects (especially Ephemeroptera) were equally important, but algae and detritus were also prominent depending on the season, showing a less specialized diet (Ba = 0.44 in the rainy season, and Ba = 0.48 in the dry season). Both fish species presented a benthivorous feeding habit; however, everything indicates that they live together without competition, because the food on which they depend is widely available. Serrapinnus calliurus was susceptible to seasonal changes in the availability of food resources. Este estudo teve por objetivo investigar o h芍bito alimentar de Serrapinnus microdon e S. calliurus e poss赤veis diferen as sazonais (esta es de chuva e seca) na utiliza o do alimento. Os peixes foram coletados mensalmente no riacho Cancela, bacia dos rios Manso/Cuiab芍, Estado do Mato Grosso, entre mar o de 2003 e fevereiro de 2004. Ambas as esp谷cies consumiram preferencialmente recursos de origem aut車ctone, independente da esta o considerada. A dieta de S. microdonfoi composta essencialmente por formas imaturas de insetos aqu芍ticos, detacando-se Chironomidae e Ephemeroptera durante todo o per赤odo de estudos, apresentando, assim, uma dieta restrita (Ba = 0,27 na chuva e 0,29 na seca). Para S. calliurus inseto aqu芍tico (especialmente Ephemeroptera) foi igualmente importante, mas destacaram-se tamb谷malgas e detrito, dependendo da esta o considerada, apresentando dieta menos especializada (Ba = 0,44 na chuva e Ba = 0,48 na seca). Ambas apresentaram h芍bito alimentar bent赤voro, por谷m, tudo indica que convivam sem competi o, uma vez que o alimento do qual dependem 谷 amplamente dispon赤vel. Serrapinnus calliurus mostrou-se mais suscept赤vel 角s altera es sazonais na disponibilidade dos recursos alimentares.

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