Seasonal changes in the structure of river fish communities in temperate Japan depicted using quantitative eDNA metabarcoding

Understanding fish communities contributes to various fields ranging from theoretical ecology to fisheries management. In rivers flowing from mountainous to urban areas and showing seasonal variations in water temperatures, fish community structure may be spatiotemporally affected by natural and anthropogenic factors. We investigated the spatial and seasonal dynamics of fish communities in the Isazu River (17.9 km) and its tributary, Ikeuchi River, in temperate Japan, using the eDNA metabarcoding method. We detected 78 fish operational taxonomic units across four seasons at 12 sites along the river length. The fish community differed significantly among different seasons and sites, aligning with the distance from the river mouth. In particular, the eDNA concentrations (copies/L) of major fishery resources and endangered fish species varied among different seasons and sites, which may reflect species migration patterns. The river hosts a spatiotemporally dynamic fish community that provi..., , # Seasonal changes in the structure of river fish communities in temperate Japan depicted using quantitative eDNA metabarcoding

Dataset DOI: [10.5061/dryad.tx95x6b88](10.5061/dryad.tx95x6b88)

## Description of the data and file structure

This supplementary dataset provides the data and R code used to generate figures and conduct statistical analyses for the study on the spatio-temporal variation of river fish communities in the Isazu and Ikeuchi Rivers.

The file \"Isazu2023_All_final_withNA_NCed.csv\" contains eDNA copy numbers (copies/μL) of detected fish species at each site (st.1–st.12) and in each season (spring, summer, fall, and winter).

The file \"Environmental_information_Isazu_eDNA_St_All_240810_ed_withNA2.csv\" includes environmental variables such as water temperature and a water quality index.

The R script \"eDNA_Isazu_dryad.R\" describes the procedures for generating the figures and conducting the statistical analyses presented in the study.

### Files and variables

#### F...,