Diet of tadpoles of Physalaemus biligonigerus (Leiuperidae) from agricultural ponds in the central region of Argentina

The intensification of agriculture has led an important loss of natural habitats, with significant consequences for biodiversity. In this sense, the studies on anuran amphibian tadpoles inhabiting these environments are relevant, because the larval stage is a phase of population regulation. The aim of this study was to analyze the diet in Physalaemus biligonigerus tadpoles, an anuran species widely distributed in South America and that inhabit agroecosystems. Three sites were sampled; two agroecosystems with different alteration degrees (AG1 and AG2) and an uncultured (SM) third place. The captured tadpoles were anesthetized, fixed and preserved in formaldehyde (10%). Subsequently, the complete intestine was removed and analyzed for food items under a binocular microscope. The diet in P. biligonigerus tadpoles has a dominance of algae Bacillariophyceae, mainly in agroecosystems, due to the presence of the genera Navicula, Nitzschia and Gomphonema. There was a considerable abundance of the Gomphonema genus in the AG2 site. In addition, in the AG1 site several non-diatom algae were particularly abundant in the diet, such as the genera Euglena, Oedogonium and Chaetophora. In the SM site, the non-diatom genus Oscillatoria was well represented in the diet. Tadpoles inhabiting the site with abundant crop and livestock (AG1) ingested a significantly smaller amount of food. The presence of certain algae associated with eutrophic environments could indicate some pollution in agroecosystems (AG1 and AG2). Larval diet is suggested as a potential bioindicator of environmental health for these areas