Ecologia trófica de Astyanax bimaculatus (Linnaeus, 1758) e Psalidodon fasciatus (Cuvier, 1819) na bacia do rio Jaguaribe, Ceará, Brasil

Abstract

Studying the trophic interactions of an animal is very important to understand the biology of the species, and the ecosystem it inhabits. Therefore, this work aimed to characterize the diet of two species present in the Jaguaribe river basin, in Ceará state: (Astyanax bimaculatus and Psalidodon fasciatus), describing their food preference during dry and rainy periods in the region. For this, the Degree of Repletion of each analyzed stomach was observed. Then, the Proportional V olume and the Frequency of Occurrence were calculated for all items found in the stomachs of both species and the values obtained were used to calculate the Food Importance Index. The Morisita Index was also calculated to test the similarity between diets in the wet and dry seasons. There was a high incidence of semi-digested material for A. bimaculatus, during the dry season, which made its identification impossible; however , the items sediment and terrestrial insects stand out. In the rainy season, their food preference for the allochthonous plant material item was observed. In relation to P . fasciatus, preference was detected for the allochthonous item insect in the dry season, while in the flood season, preference was registered for the autochthonous item filamentous algae. The values obtained showed that both species have a wide food spectrum, with changes in food preference throughout the year , characterizing omnivorous and opportunistic diets, as observed in other studies.