Dinâmica alimentar da piranha vermelha Pygocentrus nattereri KNER, 1858, do lago da hidrelétrica de Tucuruí, no período chuvoso.

Abstract

Studies on the feeding dynamics of carnivorous fish species are of paramount importance for understanding the trophic conditions of the ecosystems in which they live, especially when dealing with a dammed environment. The objective of this work was to describe the digestive tract of red piranha and to analyze the food diversity that makes up the diet of this species. The study area comprises the Tucuruí hydroelectric lake. From December 2017 to January 2019, five samples were taken. Of the 100 individuals of red piranhas, the total length, the degree of stomach fullness, the degree of food digestibility and the contents were identified and weighed. The red piranha presented the digestive tract similar to carnivorous fish. Among the analyzed stomachs 27% of the stomachs were empty, 63% half full and 10% full. The red piranha had a carnivore habit with a strong tendency to piscivore due to the large percentage of fish found in its stomach content, an item observed for all its life stages, but it was also possible to identify other items that make up the species' food, such as insects. and shrimp, in addition to the observation of vegetation (pieces of branches and leaves) accidentally ingested in the prey attack. This diversity of items can be justified by the collection period that comprises the majority in the rainy season, that is, the reservoir water level rises, causing greater dispersion of fish that would serve as food for the piranha, thus, piranhas move to the vegetated shores in search of food and mild temperatures in flooded forests. Therefore, no lake in the Tucuruí hydroelectric dam (UHE) has an important relationship between red piranha feeding and flooding of marginal forests, due to the recording of analyzed images that contain insects in the vegetation.