The effect of storm event on detection the species diversity of insects using environmental dna meta-barcoding

Environmental DNA (eDNA) is a powerful and easy methods to discover species diversity in aquatic environments. Although various environmental factors can change eDNA analysis results, a few reports explained the effects of rains including storms have on eDNA analysis and were not enough to understand the effect of rain on eDNA detection. In this study, we investigated aquatic organism biodiversity in Tendani Creek (Hiruzen Experimental Forest, Tottori University, Maniwa, Japan) using eDNA collected before and after a storm as a strong disturbance event on river water. We collected water samples on the days before and after typhoon Talim passed on 17 September 2017. Next-generation sequencing sequenced the Cytochrome Oxidase I region for Insecta. Sequence data were identified as putative source organisms. As a result, we found a drastically higher number of operational taxonomic units (OTUs) and species after the storm than before it. This can relate to the transportation of organic matter from the land by rainwater and to the resuspension of sedimented organic matter from riverbed disturbance. On the other hand, the detection rate of aquatic species decreased after the storm. This meant that rainwater diluted DNA from aquatic species. Although the post-storm eDNA can reflect biodiversity not only in water but also on land, the pre-storm eDNA is suitable for biological monitoring in the aquatic environment.