The Herpetological Journal

pp. 217-229

Authors: Anna B. Vassilieva, Artem Y. Sinev & Alexei V. Tiunov

Abstract: Trophic differentiation of tadpoles of four anuran species (Hoplobatrachus rugulosus, Microhyla fissipes, M. heymonsi,
Polypedates megacephalus) with different oral morphologies was studied in temporary ponds in a monsoon tropical forest in
southern Vietnam. All tadpole species were found to be omnivorous, including filter-feeding microhylids. Both gut contents analysis and stable isotope analysis provided enough evidence of resource partitioning among coexisting species. Gut contents analysis supported the expected partitioning of food resources by tadpoles with different oral morphologies and showed differences in the food spectra of filter-feeding and grazing species. Stable isotope analysis revealed more complex trophic niche segregation among grazers, as well as amongst filter-feeders. Tadpole species differed mainly in δ13C values, indicating a dependency on carbon sources traceable to either of aquatic or terrestrial origins. Furthermore, tadpoles with generalised grazing oral morphology (P. megacephalus) can start feeding as suspension feeders and then shift to the rasping mode. Controlled diet experiment with P. megacephalus larvae showed a diet-tissue isotopic fractionation of approximately 1.9‰ and 1.2‰ for Δ13C and Δ15N, respectively. In natural habitats, the difference in δ13C and δ15N values between body tissues and gut contents of four tadpole species averaged 2.8‰ and 1.0‰, respectively.

Keywords: Amphibia, aquatic food web, Cat Tien National Park, Microhylidae, mouthparts, Southeast Asia, stable isotopes, trophic shift