New evidence on the quagga mussel spread south to the Alps from an eDNA approach. INVSPTICH

The dreissenid quagga mussel, Dreissena rostriformis bugensis, is an invasive species native to the Black Sea region that has recently spread to Western Europe. In Swiss northern perialpine lakes this organism quickly colonized the lakeshore, with major implications for aquatic ecosystems and human activities. Due to its competitiveness, the quagga mussel can easily take advantage of human mediated transport to reach new environments. Therefore, the management of quagga mussel seeks to prevent further spread and minimize its negative impact. With this aim, the early detection by environmental DNA (eDNA) methods is increasingly applied in freshwater systems. Here, an approach based on species-specific primer targeting the quagga mussel from eDNA was applied in two renowned tourist destinations, Lake Lugano and Lake Maggiore. Our results showed for the first time the spread of the quagga mussel south to the Alps and suggested that in both the lakes the colonization is in the early stages. Besides, the eDNA approach proved to be a powerful tool for the early detection of the quagga mussel, and may be applied to reduce the ecological and economic impact resulting from the introduction of invasive mussels.