Trophic ecology of two piranha species, Pygocentrus nattereri and Serrasalmus marginatus (Characiformes, Characidae), in the floodplain of the Negro River, Pantanal

Abstract

Aim: This study aimed to evaluate influence of hydrological variation, ontogeny and interspecific variation in the feeding activity and diet composition for P. nattereri and S. marginatus in floodplain of Negro River, South Pantanal. Methods: The samples were taken with the use of gillnets and cast nets of different sizes, from October/2005 to August/2008. Results: We sampled 748 specimens, 442 of P. nattereri and 306 of S. marginatus. We identified 31 items in the dry and 14 in the flood season for P. nattereri, and 29 items in the dry and eight in the flood season for S. marginatus. For both species, fish was the predominant food item in both seasons. The PERMANOVA results showed that the diet varied significantly between the two species (p<0.001), during ontogenetic development (p<0.001) and seasonally (p=0.024). The ancova results suggests that the intensity of food intake was higher in the dry season (p<0.001) for both species. The niche breadth varied only between studied species with S. marginatus presenting higher niche breadth than P. nattereri. Conclusion: Piranhas feed more during dry season, probably because in this period food is more varied and abundant, due to the concentration of fish in the main river channel. There were ontogenetic changes in the diet, with no feeding overlap between the two species, probably because of differences in preference for some items and differences in feeding behavior displayed during hunting attacks.Keywords: Serrasalminae, diet, feeding overlap, trophic ontogeny, Nhecolândia.Resumo: Objetivos: Este trabalho tem como objetivo avaliar a influência da variação hidrológica, da ontogenia e da variação interespecífica na atividade alimentar e composição da dieta de P. nattereri e S. marginatus na planície de inundação do Rio Negro, Pantanal Sul. Métodos: As amostragens foram realizadas com o uso de redes de espera e tarrafas com diversas malhagens no período de outubro/2005 e agosto/2008. Resultados: Foram coletados um total de 748 indivíduos, 442 de P. nattereri e 306 indivíduos de S. marginatus. Identificamos 31 itens alimentares no período da seca e 14 na cheia para P. nattereri e 29 itens alimentares no período da seca e oito na cheia para S. marginatus. Para ambas as espécies, peixes foi o item predominante em ambas as estações. Os resultados da PERMANOVA mostraram que a dieta variou significativamente entre as espécies (p<0,001), durante o desenvolvimento ontogenético (p<0,001) e sazonalmente (p=0,024). Os resultados da ANCOVA sugerem que a intensidade da tomada de alimento foi maior na estação seca (p<0,001), para ambas as espécies. A amplitude de nicho 382 Ferreira, FS. et al.Acta Limnologica Brasiliensia variou entre as espécies estudadas, S. marginatus apresentou uma amplitude de nicho maior do que P. nattereri. Conclusão: As piranhas se alimentam mais durante a seca, provavelmente porque neste período o alimento é mais variado e abundante, devido a concentração de peixes no canal principal do rio. Houve mudanças ontogenéticas na dieta, sem sobreposiç...

Fish and amphibians as bat predators

“…In Nearctic region, northernmost observation of fish predation on bats came from Ruby Mountains region (40°40'N, 115°31'W), Nevada, USA, where Oncorhynchus mykiss (Salmonidae) was preying upon dead or injured Myotis lucifugus (Vespertilionidae) (Borell & Ellis 1934). Most southward records from southern hemisphere were reBrought to you by | MIT Libraries Authenticated Download Date | 5/9/18 4:05 PM corded in Rio Negro Farm (19°35'S, 56°15'W), Pantanal, Brazil, where several unidentified bat individuals were found in the stomach of Pygocentrus nattereri (Serrasalmidae) (Ferreira et al 2014). In the Old World, two Pteropus sp.…”

Feeding ecology of Serrapinnus notomelas (Characiformes: Cheirodontinae) in small forest streams in the Machado River basin, Rondônia, Brazil

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Feeding ecology of Serrasalmus gouldingi (Characiformes: Serrasalmidae) in the lower Anapu River region, Eastern Amazon, Brazil

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