New specific molecular marker detects Ficopomatus enigmaticus from water eDNA before positive results of conventional sampling

Abstract The tubeworm Ficopomatus enigmaticus is a highly invasive species with an increasingly expanding distribution in Europe and America. In port areas it causes damage to structures and sewage systems because it is an active reef builder. Having short generation time and high reproduction capacity it is especially important to detect the species before it is fully settled down. Here we have designed a PCR-based species-specific molecular marker within the Cytochrome Oxidase subunit I gene (COI). The new marker was validated in vitro and from field water samples obtained in southwest Bay of Biscay ports (north of Spain). The species was detected only from eDNA in Villaviciosa port, where it was not found de visu in the intertidal zone and floating structures. Adults were found in the same port one year later as confirmed taxonomically and by conventional barcoding, which confirms the utility of the new eDNA marker for early detection of F. enigmaticus . This new and cheap molecular tool could be used for routine monitoring of coastal areas, in order to early detecting this invasive species.