ASSESSMENT OF DIURNAL VARIATIONS OF RIVERINE FISH COMMUNITY USING THE QUANTITATIVE METHOD OF ENVIRONMENTAL DNA METABARCODING

Abstract

 Freshwater fish is one of the major taxonomic groups in river ecosystems and is used as an indicator of river ecosystem health. The knowledge on the distribution and diversity of freshwater fish is essential to develop river management for the conservation of freshwater fishes. In this study, we evaluated the diurnal variations of eDNA concentrations for freshwater fish species in the Saba River, Yamaguchi Prefecture, Japan using environmental DNA (eDNA) quantitative metabarcoding (qMiFish) that enables the quantitative assessment of multiple fish species from water samples. The results showed that the species number, fish community composition, and eDNA concentrations did not significantly differ between daytime and nighttime. These results suggest that researchers can quantitatively understand the fish community compositions from eDNA data by conducting only daytime water sampling in the river. Furthermore, the eDNA concentrations of some fish species have changed between daytime and nighttime, indicating that qMiFish may be able to capture the eDNA dirnal variations with the fish activities.