Functional and trophic diversity of tropical headwater stream communities inferred from carbon, nitrogen and hydrogen stable isotope ratios

Tropical freshwaters support an immense diversity of fishes and invertebrates but are understudied in comparison to temperate systems. This is especially true headwater streams, as only a small number studies has assessed the trophic dynamics underpinning food web structure these streams. We used stable isotopes carbon, nitrogen hydrogen determine resource use dominant invertebrate guild seven streams Eastern Western Thailand, functional each community using isotope metrics. Benthic (95% credibility interval: 37–85%) (39–79%) obtained most their resources from autochthonous sources stream allochthonous specialists were evident community. observed increase isotopic associated with increasing size, this was primarily driven by range ratios endmembers rather than diversity. Maximum position did size. The snakehead, Channa gachua, enriched 2H relative all other fishes, possibly reflecting facultative air breathing species. Fish communities analysed filled variety niches, predominantly fuelled primary production.