Trophic interactions in the Zoige Alpine wetland on the eastern edge of the Qinghai-Tibetan Plateau inferred by stable isotopes

The Zoige wetland ecosystem of the eastern edge of the Qinghai-Tibetan Plateau is the largest plateau peat bog worldwide and an important biodiversity conservation centre in China. Nevertheless, limited information is available about this Alpine wetland aquatic ecosystem, including its food-web structure and complexity. In this study, we analysed the trophic interactions among dominant organisms in the food web of this Alpine wetland aquatic ecosystem and assessed the importance of allochthonous and autochthonous carbon sources during the wet season using delta C-13 and delta N-15 analysis. The results supported the hypothesis that the food web of the Zoige Alpine wetland is largely maintained by allochthonous carbon sources rather than autochthonous food sources during the wet season when the allochthonous resource availability is relatively high. The food web contains approximately three trophic levels, and Schizopygopsis pylzovi (a genus of cyprinid fish) is the top predator. Intermediate trophic positions, including zooplankton and macroinvertebrates, represent the primary animal community in the food web. The allochthonous carbon sources are transferred to the food web via these macroinvertebrates (e.g., Ecdyonurus sp. and Sigara substriata). Although our findings show a low biodiversity in the Zoige wetland during the wet season, the trophic redundancy in the food-web structure could support the stability of the Zoige Alpine wetland aquatic ecosystem.