Time-series transition of the community structure of aquatic insects at middle domain of Natori river basin in Miyagi Prefecture as revealed by eDNA metabarcoding analysis.

The time-series change of the community structure of aquatic insects were investigated using environmental DNA eDNA metabarcoding analysis and a conventional Surber net sampling method. Field sampling was conducted from May to December in 2016 once per month at 2 sites located middle domain of the Hirose River and the Natori River in the Natori river basin, Miyagi prefecture, Japan. DNA extracted from river water samples were processed in metabarcoding targeting the cytochrome oxidase subunit 1 gene in mitochondrial DNA, and 8 taxonomic orders of aquatic insects Ephemeroptera, Plecoptera, Trichoptera, Diptera, Coleoptera, Odonata, Hemiptera were detected through bioinformatics process. Collected insects by a surber-net sampling were identified morphologically at family level to compare with eDNA outputs. As a result, the member of taxa in communities were mostly composed by Ephemeroptera and Diptera families and the trend of time-series change of taxa richness were consistent between two methods. Furthermore, the taxa that many individuals were collected by a surber-net sampling tended to obtain a large number of sequence reads in eDNA analysis. In addition, community structures by relative abundance from eDNA metabarcoding and the conventional method showed the same transition pattern after a flood disturbance, i.e. the ratio of swimmers increased immediately after the disturbance and the ratio of crawlers increased later. Our results showed that eDNA metabarcoding targeting aquatic insects can describe the time-series transition of the community structure using relative abundance based on the number of sequence reads even though taxa members and taxa richness were not same with a conventional sampling method.