Data from: Environmental DNA reveals quantitative patterns of fish biodiversity in large rivers despite its downstream transportation

Despite the ecological and societal importance of large rivers, fish
sampling remains costly and limited to specific habitats (e.g., river
banks). Using an eDNA metabarcoding approach, we regularly sampled 500 km
of a large river (Rhône River). Comparisons with long-term electrofishing
surveys demonstrated the ability of eDNA metabarcoding to qualitatively
and quantitatively reveal fish assemblage structures (relative species
abundance) but integrated a larger space than the classical sampling
location. Combination of a literature review and field data showed that
eDNA behaves in the water column like fine particulate organic matter. Its
detection distance varied from a few km in a small stream to more than 100
km in a large river. To our knowledge, our results are the first
demonstration of the capacity of eDNA metabarcoding to describe
longitudinal fish assemblage patterns in a large river, and metabarcoding
appears to be a reliable, cost-effective method for future monitoring.