Alimentação e ecomorfologia de duas espécies de piranhas (Characiformes: Characidae) do lago de Viana, estado do Maranhão, Brasil

Abstract

RESUMOSerrasalmus aff. brandtii e Pygocentrus nattereri são duas espécies de piranhas comuns no Lago de Viana, um lago formado a partir das inundações do Rio Pindaré, tributário da margem esquerda do Rio Mearim. Uma amostra composta por 249 exemplares destas espécies foi estudada a fim de identificar a composição da dieta e as estratégias alimentares empregadas pelas duas. Os peixes foram coletados trimestralmente durante um ano, entre março de 1998 e março de 1999, usando redes de emalhar e tarrafas. A composição qualitativa da dieta foi analisada com uso do método de freqüência de ocorrência. As estratégias alimentares empregadas pelas espécies foram inferidas através do método gráfico de Costello (1990), modificado por Amundsen et al. (1996). Os resultados indicaram que peixes foi o item encontrado com maior freqüência nos estômagos de ambas as espécies, seguido de matéria vegetal, com maior participação na dieta de P. nattereri. Os recursos peixes e vegetais tenderam a apresentar relações inversas quando comparados com as diferentes classes de comprimento. A análise gráfica da dieta de P. nattereri e S. aff. brandtii sugere que a maioria dos indivíduos utiliza vários recursos simultaneamente. Uma análise multivariada de índices ecomorfológicos indicou que as espécies são segregadas com relação à habilidade natatória, posição ocupada na coluna d'água e tamanho relativo das presas. PALAVRAS-CHAVEEstratégia alimentar, Serrasalminae, ecomorfologia, água doce tropical.Feeding and ecomorphology of two species of piranhas (Characiformes: Characidae) from the Viana Lake, Maranhão state, Brazil. ABSTRACT Serrasalmus aff. brandtii and Pygocentrus nattereri are two species of piranhas, both common in the Viana Lake, which is formed by the flooding waters of the Pindaré River, a tributary of the left bank of the Mearim River.A sample composed of 249 specimens of these species was studied in order to identify diet composition and feeding strategies employed by the two species. The piranhas were captured thrimonthly, during one year from March 1998 to March 1999 using gill and fishing nets of different mesh sizes. The qualitative composition of the diet was analysed through the frequency of occurrence method. The feeding strategies employed by the piranhas were inferred using the graphic method of Costello (1990), modified by Amundsen et al. (1996). The results indicated that fish was the main food item in the stomach contents of the two species, followed by plant material, more in the P. nattereri.

Resource partitioning and ecomorphological variation in two syntopic species of Lebiasinidae (Characiformes) in an Amazonian stream

“…Since the niche is multidimensional, resource partitioning may be not experienced in the type of consumed preys, but in other dimensions like prey size, different use of space and/ or phenotypic characteristics that allow subtle differences in the use of available resources (Esteves and Aranha 1999;Piorski et al 2005;Brazil-Sousa et al 2009). Furthermore, when considering average values of resource use within a population we ignore the fact that the individuals composing the same population may use different resources, minimizing an apparent competition between species.…”

“…The following morphological measurements were quantified following Piorski et al (2005) and Mazzoni et al (2010) Resource partitioning and ecomorphological variation in two syntopic species of Lebiasinidae (Characiformes) in an Amazonian stream ACTA AMAZONICA (consuming few items in large quantities), indicate a high influence of the between-phenotype component in the niche width of both species (Figure 2). Hymenoptera (especially Formicidae) was the only item consumed by a little more than 50% of the population of C. nigrofasciata, but in low abundance (Figure 2a).…”

“…Resource partitioning in neotropical fish communities has been well documented (Corrêa et al 2009;Silva et al 2012) and often related to ecomorphological and/ or behavioral differences that influence the use of space (micro-habitat) and food resources (Piorski et al 2005;Lima et al 2008;Brazil-Sousa et al 2009). Morphological features might be indicators of species life habits, types of resource use or adaptations to occupy the environment (Gatz 1979).…”

“…Thus, it can be expected that these species, especially when syntopic, exhibit differences in resource use that might minimize competition (Herder and Freyhof 2006). For example, in the size of consumed prey, use of microhabitats and feeding strategy (Esteves and Aranha 1999;Piorski et al 2005;Brazil-Sousa et al 2009). …”

Morphological differentiation among migratory fish species from the Paraná River basin

“…Studies on morphology of Neotropical freshwater fish are restricted to the comparison between morphology and diet (Piorski et al 2005, Teixeira & Bennemann 2007, morphological variations under different environmental conditions (Monteiro & Neves 2003), and ecomorphology of fish from streams (Casatti & Castro 2006, Ferreira 2007. However, studies on the morphology associated with swimming performance for the Neotropical fish species are non-existent, with only information available for two migratory species, Leporinus reinhardti and Pimelodus maculatus, on swimming speeds and determination of swimming performance in the studies conducted by Santos et al (2007Santos et al ( , 2008.…”