Alimentação e análise morfológica de quatro espécies de peixes (Astyanax altiparanae, Parauchenipterus galeatus, Serrasalmus marginatus e Hoplias aff. malabaricus) na planície de inundação do alto rio Paraná, Brasil.

Abstract

The species was set in two trophic guilds - insectivores (Astyanax altiparanae Garutti & Britski, 2000, Parauchenipterus galeatus (Linnaeus, 1766) and piscivores (Serrasalmus marginatus Valenciennes, 1847 and Hoplias aff. malabaricus (Bloch, 1794). The first two, although consumers of insects, explored different alimentary groups, standing out the Hymenoptera to A. altiparanae and Coleoptera to P. galeatus. Serrasalmus marginatus and H. aff. malabaricus consumed mainly fishes, however just pieces of preys were more often found in the first specie stomach content and whole fishes in the second one. The morphology of the digestive tract was important to do inferences as how the predators obtain and use food resources. Astyanax altiparanae exhibited characteristics that allowed it to obtain food in several compartments of the water column according to mouth position and the type of food explored associated with characteristics as teeth, gill rakers and pyloric cecum. Also P. galeatus consumed food resources that are available in all aquatic compartments, however the characteristics to capture, to manipulate and to absorb food differed, being evidenced the importance of teeth plates and pharyngeal teeth. Serrasalmus marginatus and H. aff. malabaricus although resembling each other in many aspects of the digestive tract morphology they differed in the strategies to capture preys. It still stands out, as one of the several mechanisms to avoid the prey escape when already inside the digestive tract structures, the presence of striated muscle in the initial portion of the H. aff. malabaricus stomach.