Variações na dieta de Astyanax lineatus (Characiformes: Characidae) de acordo com a cobertura do solo em riachos da bacia do rio Formoso, bacia do rio Paraguai

Abstract

Changes in land cover may influence stream structures, food resource availability and fish diet. The aim of this study was to define the diet of Astyanax lineatus in streams of the Formoso river watershed and to verify possible differences in diet in relation to land cover and use. The sampling were taken from 20 streams in the Formoso river watershed (Mato Grosso do Sul state) between January and May 2016. To classify land cover and use, 500 m circular buffers were made, creating three distinct stream groups: Forest, Pasture and Urban. The food items were analyzed according to the volumetric and occurrence frequency methods and the diet was characterized through the Food Index (IAi%). The species diet was characterized through order analysis (NMDS) and the differences between the species diet were tested through PERMANOVA and pair-wise tests. The general diet of A. lineatus was classified as omnivorous as they consume similar amounts of plants and insects. The species exhibited significant differences in diet between the different stream groups. In the Forest group, the species exhibited an omnivorous diet as it consumed the Plant, Land Insect and Aquatic Insect proportionally. In the Pasture streams the diet was characterized as herbivorous and in the Urban streams the species exhibited an insectivorous diet, as they consumed mainly Land and Aquatic Insect. The present study provided information about A. lineatus feeding and its feeding flexibility before different land cover, opening the chance to better understand the relationship between species of stream fish and the changes that terrestrial environments are going through.