Bivalves des étangs des Espaces naturels sensibles du Maine-et-Loire : diversité et étude pilote sur la détection par analyse de l’ADNe

In 2020 and 2021, the CPIE Loire Anjou carried out a study to estimate the diversity of bivalves in 16 ponds in Maine-et-Loire, most of which are classified as Sensitive Natural Areas, and to estimate the degree of presence of the Chinese Pond Mussel Sinanodonta woodiana (I. Lea, 1934), an invasive species recently detected in the department. Surveys were carried out using traditional methods (pedestrian prospections, viewing glass, sediment sieving) and environmental DNA (eDNA) analysis in the water matrix. eDNA, already used on rivers, was used here for the first time in a stagnant environment, with transects carried out on foot, by canoe and by sampling at outlets. In total, 16 species were identified. Excluding the special case of Lac de Maine in Angers, whose richness is linked to its temporary connection with the river Maine (13 species), the average number of species identified per water body is 2.7. Invasive exotic species are rarely present in the water bodies, and the Chinese Pond Mussel is completely absent. The eDNA surveys proved to be very effective, allowing the detection of many Sphaeridae that were not observed during the pedestrian surveys. However, in some ponds, the detection rate did not reach 100 %.