Abstract
ABSTRACT Studies on the composition of fish diet and on how species exploit food resources are especially relevant in tropical freshwater systems, where dietary plasticity is a commonly used strategy. In this study, we analysed the food spectrum and the environmental, seasonal and ontogenetic variations in the diet of a characid species [Hemigrammus marginatus Ellis, 1911 (Characidae)] in the region of the Upper Contas River, in the Diamantina Plateau, Brazil. We verified an omnivorous/invertivorous and opportunistic food habit, with predominance of insects and microcrustaceans, followed by filamentous algae. Seasonality did not alter the food resources used by the species. However, differences were detected in the dominant categories when comparing the two sampled rivers, as well as in the food consumption throughout the development of the species. These data increase the knowledge about the biology of H. marginatus and allow understanding the influence of the characteristics of the rivers and their surroundings in the trophic ecology of the species, as our findings have shown that, although insects have been expressive in both studied localities, microcrustaceans exhibit a greater relative importance in the more lentic environment, which is probably related to the variation in the availability of these resources in the environment.
Highlights
From the analysis of the stomach content of 338 specimens of Hemigrammus marginatus, 183 of which were captured in the Contas River and 155 in the Água Suja River, we verified the consumption of a wide variety of food items
Food categories in which the items found in the stomachs of specimens of Hemigrammus marginatus Ellis, 1911 in drainages of the Upper Contas River, Diamantina Plateau, Brazil, were classified
Our analyses allowed the identification of a varied food spectrum for Hemigrammus marginatus of the Upper Contas River, with a diet based on autochthonous items mainly of animal origin, besides algae, detritus and sediment, so that the species, in general, was characterized as omnivorous/ invertivorous and opportunistic
Summary
Analisamos o espectro alimentar e as variações ambientais, sazonais e ontogenéticas na dieta de uma espécie de caracídeo [Hemigrammus marginatus Ellis, 1911 (Characidae)] na região do Alto Rio de Contas, na Chapada Diamantina, Brasil. The items used as food resource by the fish are quite diverse, differing in type (animal, plant or detritus/ sediment) and origin (autochthonous or allochthonous), and their availability in the aquatic environments is variable (Bennemann et al, 2005) This variation is influenced by the characteristics of the water body and its surrounding and can occur seasonally and/or spatially, mainly as a function of the longitudinal gradient of the watercourse (Vannote et al, 1980; Esteves & Aranha, 1999; Gomiero & Braga, 2005). This area is notable for sheltering several endemic species, such as Hyphessobrycon brumado Zanata & Camelier 2010, Trichomycterus tete Barbosa & Costa 2011, a probable new species of Nematocharax (Barreto et al, 2016), and Hasemania piatan Zanata & Serra 2010, being the latter considered endangered due to anthropic impacts (Silva et al, 2016)
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