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

Didier Pont (1, 2, 3) , Mathieu Rocle (4) , Alice Valentini (1, 3) , Raphaël Civade (3) , Pauline Jean (1) , Anthony Maire (5) , Nicolas Roset (6) , Michael Schabuss (7) , Horst Zornig (7) , Tony Dejean (1)

1 SPYGEN [Le Bourget-du-Lac]
2 Institute of Hydrobiology and Aquatic Ecosystem Management
3 VIGILIFE
4 CNR - Compagnie Nationale du Rhône
5 EDF R&D LNHE - Laboratoire National d’Hydraulique et Environnement
6 AFB - Agence Française pour la Biodiversité
7 PRO FISCH OG Ecological Consultants

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 eDNA 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.

Domaines: Biodiversité et Ecologie; Biodiversité

Didier Pont, Mathieu Rocle, Alice Valentini, Raphaël Civade, Pauline Jean, et al.. Environmental DNA reveals quantitative patterns of fish biodiversity in large rivers despite its downstream transportation. Scientific Reports, 2018, 8 (1), pp.10361. ⟨10.1038/s41598-018-28424-8⟩. ⟨hal-01834958⟩