Trophic ecology of tadpoles in floodplain wetlands: combining gut contents, selectivity, and stable isotopes to study feeding segregation of syntopic species

Abstract

Little consensus exists on the role of food partitioning in the organization of tadpole assemblages. We studied trophic ecology of syntopic tadpoles through the analysis of gut contents, selectivity, and stable isotopes to assess the occurrence of food partitioning in tadpole assemblages. Tadpoles (n = 194) were collected in three wetlands and corresponded to four species: Elachistocleis bicolor (Eb), Scinax nasicus (Sn), Physalaemus albonotatus (Pa), and Dendropsophus sp. (D); and belonged to four ecomorphological groups (EMGs): suspension feeders (Eb), nektonic (Sn), benthic (Pa) and macrophagous (D). Sn, and Pa showed low selective diet and a wider trophic spectrum than Eb and D, which mainly consumed one or two food categories. Diet overlap was higher between Sn and Pa. Still, Sn and Pa presented some differences in the food resources consumed. Stable isotopes analysis showed that Eb, Sn, and Pa had a lower trophic position than D, explained by the high contribution of animal food oligochaete in D diet, in contrast to the importance of algae in the diet of Eb, Sn, and Pa. Diet specialization of some species, combined with the low dietary and isotopic overlap among the ecomorphological groups, suggests that trophic partitioning facilitates coexistence of syntopic tadpoles.