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

Area of Science:

• Aquatic Ecology
• Environmental DNA (eDNA) Metabarcoding
• Fisheries Science

Background:

• Fish community structure is crucial for ecological understanding and fisheries management.
• Riverine ecosystems are influenced by natural and anthropogenic factors, leading to spatiotemporal variations.
• Seasonal temperature shifts in rivers impact fish community dynamics.

Purpose of the Study:

• To investigate the spatial and seasonal dynamics of fish communities in the Isazu River and its tributary.
• To assess the influence of environmental factors on fish community structure using eDNA metabarcoding.
• To understand the distribution patterns of fishery and endangered fish species.

Main Methods:

• Utilized environmental DNA (eDNA) metabarcoding for fish detection.
• Sampled 12 sites across 17.9 km of the Isazu River and its tributary over four seasons.
• Analyzed 78 fish operational taxonomic units (OTUs) and eDNA concentrations (copies/L).

Main Results:

• Detected 78 fish OTUs, with significant differences in community structure across seasons and sites.
• Fish community composition correlated with the distance from the river mouth.
• eDNA concentrations of key fishery and endangered species varied seasonally and spatially, suggesting migration patterns.

Conclusions:

• The Isazu River supports a spatiotemporally dynamic fish community.
• eDNA concentrations provide valuable insights into fish distribution and migration in response to environmental factors.
• Findings contribute to theoretical ecology and fisheries management by elucidating complex ecological relationships.