Ain, Isère, Rhône: Diagnosis of the Dwarf Ramshorn Snail

The Rhône-Alpes Nature Conservation Centre plans punctual sampling in the Ferrande and Négria backwaters to study this protected species.

Generic image of aquatic snail shells on river stones.
AI

Generic image of aquatic snail shells on river stones.

As part of a hydraulic restoration project, the Rhône-Alpes Nature Conservation Centre plans punctual sampling to diagnose the presence of the Dwarf Ramshorn Snail (Anisus vorticulus) in the Ferrande and Négria backwaters, located in the departments of Ain, Isère, and Rhône.

Ten sampling points are planned in the aquatic section of the Ferrande backwater. Sampling involves collecting aquatic fauna from flooded and floating vegetation. Shells will be sorted on-site and examined with a hand lens before being released. Less characteristic shells will be taken to the laboratory for examination under a binocular microscope, with deferred release on-site within the week. These samples will concern only a minority of the captured individuals.
Complementary litter deposit sampling on the banks of the Négria backwater may also help detect the species' presence. The presence of the Dwarf Ramshorn Snail is not yet confirmed on the site, but it is historically known in the vicinity.
The Regional Scientific Council for Natural Heritage (CSRPN) gave a favorable opinion on this request on September 26, 2026. The consultation is open from November 03 to November 18, 2026 inclusive.
Based on information from the official source: DREAL Auvergne-Rhône-Alpes (03/11/2026)