Controlling populations of invasive pygmy mussel (Xenostrobus securis) through citizen science and environmental DNA

•Researchers, citizens and eDNA for controlling Xenostrobus securis invasion.•Successful eradication of Xenostrobus securis with citizen science.•eDNA to confirm and to monitor biological invasions.

Early detection of dangerous exotic species is crucial for stopping marine invasions. The New Zealand pygmy mussel Xenostrobus securis is a problematic species in coasts of temperate regions in the northern hemisphere. In this study we have controlled a population of this invader that recently expanded in a north Iberian estuary with both a participatory approach involving researchers and citizens, and employing a sensitive eDNA-based tool to monitor the population expansion in the estuary. Results demonstrate successful eradication of pygmy mussels in the outer part of the estuary with citizen science and the practical utility of eDNA for controlling biological invasions.