Impacto antrópico na dieta do cágado-de-barbicha, Phrynops geoffroanus (Testudines, Chelidae) no rio Uberabinha, Uberlândia, Minas Gerais

Abstract

The Testudines are a major component of food webs in rivers, although it is still a rare observation of turtles feeding in natural conditions. The neotropical species have broad dietary habits that include various items of terrestrial and aquatic origin, with the composition of the diet varies with availability of food resources. From May to October 2011 we captured a total of 110 specimens of P. geoffroanus in River Uberabinha into three distinct areas and also captured the potential prey. The collection of items ingested was performed by stomach flushing and the collection of potential prey was made with a pitfall traps for prey to land, network D to capture aquatic macroinvertebrates and Covo trap for fish. The dietary items were fixed, marked, separated into categories (animal, vegetable, anthropogenic, non-food) and their volumes were measured. To verify if the different areas affect the diet, we held an Analysis of Variance (ANOVA) factorial. One of the areas (area 2) was not included in statistical tests because the large discrepancy between the number of females and males captured. Considering the diet as a whole, there was no significant difference between areas 1 and 3 (F=3,342, p=0,068), but when analyzed separately for each food item categories, the specimens of the area 1 consumed more aquatic vertebrates and fewer items of anthropogenic origin when compared with specimens of area 3 (F=65,419, p<0,01). With regard to gender, there was no statistical difference in area 1 (F=0,561, p= 0,454), but there was in area 3 (F= 9,410, p=0,02), while females consumed a greater volume of items of anthropogenic origin than males (F= 34,276, p<0,001). The diverse diet and adaptation to environments impacted demonstrate that P. geoffroanus is a species with high plasticity. However, the use of non-food items, first recorded for the species, in large quantities and / or size may compromise their survival.