Stable isotope proxies for evaluating biodiversity in stream biota

Differences in δ13C and δ15N values in stream biota are caused by several environmental conditions. Variations in abundance, species richness and the assemblage structure of stream biota are also caused by several environmental conditions. Hence, abundance, species richness and the assemblage structure of stream biota are expected to be strongly correlated with the differences in value of stable isotopes. In this study, the gaps in δ13C and δ15N between periphyton and charr are discussed in terms of the abundance, genus richness, and assemblage of benthic invertebrates at each site. Gaps in δ13C between periphyton and charr were strongly correlated with some aspects of mountainous area and the genus richness of benthic invertebrates at each site. The gaps in δ15N between periphyton and charr were strongly correlated with the abundance and assemblage structure of benthic invertebrates at the location tested. The δ13C values of predators were correlated with some aspects of mountainous area and the assemblage structure of the benthic invertebrates. The δ15N values of predators were correlated with genus richness and the assemblage structure of the benthic invertebrates. These results suggest that the value gaps in δ13C and δ15N can be used to assess biodiversity and could provide indices for estimating the biodiversity in a stream.