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

Studies on feeding ecology of fishes are important to understand the relationship between species and environmental seasonal variations. In tropical rivers, these relationships are mainly modeled by hydrological patterns. Thereby, this study aimed to assess the influence of fluviometric variation and life stage (juveniles and adults) in the feeding ecology of Serrasalmus gouldingi in the lower Anapu River region, located in Eastern Amazon, Para, Brazil. Specimens were collected bimonthly, considering four different hydrological periods. We assessed the diet composition, feeding intensity and niche breadth of the species. Thirty-two dietary items were identified and grouped into ten categories. A total of 279 stomachs were analyzed, showing a predominance of fish fragments, followed by fruits and seeds. The diet composition of S. gouldingi differed only between drought and flood season, although it did not differ between juveniles and adults. An increase in feeding intensity was recorded during the rise in the water level, with a lower feeding intensity observed during transitional season. Serrasalmus gouldingi showed lower niche breadth during flood season, attributed to the high consumption of fruits and seeds, presenting an omnivorous diet with high tendency towards piscivory. Although less evident than in other Amazon watersheds, the flood pulse in the lower Anapu River region is an important factor influencing the feeding ecology of the species.Original Abstract: Estudos sobre ecologia trofica dos peixes sao importantes ferramentas para compreensao das relacoes entre as especies e as variacoes sazonais no ambiente. Em rios tropicais essas relacoes sao modeladas principalmente por variacoes hidrologicas. Sendo assim, o objetivo presente estudo e avaliar a influencia variacao fluviometrica e do estagio de vida (juvenis e adultos) na ecologia alimentar de Serrasalmus gouldingi na regiao do baixo Rio Anapu, Amazonia Oriental, Para, Brasil. Os especimes foram amostrados bimensalmente considerando quatro periodos hidrologicos distintos. Nos avaliamos a composicao da dieta, intensidade alimentar e amplitude de nicho da especie. Foram identificados trinta e dois itens alimentares agrupados em dez categorias. Um total de 279 estomagos foi analisado, registrando um predominio no consumo de fragmento de peixes seguido por frutos e sementes. A composicao na dieta de S. gouldingi diferiu apenas entre os periodos de seca e cheia, nao diferindo entre juvenis e adulto