Diet of Acanthochelys spixii and Hydromedusa tectifera (Chelidae) in the southern Brazil

Abstract

Data about the diet of the freshwater turtles Acanthochelys spixii and Hydromedusa tectifera from southern Brazil populations remain little known.  In this context, the digestive tract of 21 A. spixii and 20 of H. tectifera individuals from three municipalities in the state of Rio Grande do Sul, Brazil were examined. The food items were identified at the lowest possible taxonomic level, quantified, and conserved in ethanol 70°GL. The frequency of occurrence (F %) and volume percentage (V %) were estimated, as well as the food importance index (IAi %). The range of the trophic niche and the feeding strategy of both species were analyzed. The diet of A. spixii and H. tectifera was compared through the Mann-Whitney test (P < 0.05). Both species presented a generalist food strategy, consuming mainly insects, represented by Hemiptera, Odonata, Coleoptera, and Diptera. There was no significant difference in the volume of items consumed by both species (Mann-Whitney test, z =-0.387, P = 0.69). Concerning the trophic niche range, we observed low values for both species, it was of 0.41 for A. spixii and 0.39 for H. tectifera suggesting a more restricted diet with uniformity in food consumption, however, we highlight that a more restricted diet does not suggest a trophic specialization, because the availability of food items have variation in time and space. The study contributed information on the diet of species in the region, generating data that can be used in programs for the conservation of species and their habitats.