O efeito da mata ciliar na ecologia trófica de Mimagoniates microlepis(Steindachner, 1877) em um riacho de Mata Atlântica

Abstract

The objective of this study was to compare the diet of young and adult Mimagoniates microlepis in two sites from Rio do Gato, with different canopy cover densities. Samples were taken in Cachoeiras de Macacu, Rio de Janeiro. Environmental parameters like river depth and width, current speed, canopy density and substrate composition were measured. Fish were collected by electrofishing during dry and wet seasons. Intestinal Coefficient (Qi) was measured and stomachs were removed for content analysis. Food item categories were evaluated by the Alimentary Index (IAi), and diet similarities between sites and seasons were determined based on IAiby a cluster UPGMA analysis with Bray-Curtis distances. Each category was classified by origin, as alochthonous, autochthonous or detritus in order to determine the importance of these classes in each site. 82 specimens were captured, 29 from the open site and 53 from the closed site. Young were captured in the closed site only. The largest category variety was observed in the closed site, and in this site there were no differences between seasons, whereas in the open site the species diet was different between seasons. The population s average Intestinal Coefficient was 0.41, and there was a significant reduction in average Qi to 0.31 in the open site during dry season. Alochthonous insects was the main food category eaten by young and adults, but young fish also consumed autochthonous larvae. There were no differences between male and female diets. These results confirm our hypotheses and agree with those of other studies with this species