Novel tools for early detection of a global aquatic invasive, the zebra mussel Dreissena polymorpha

1. This study presents a species-specific DNA-based marker for detection of the zebra mussel Dreissena polymorpha, recognized as one of the worst invasive species worldwide. 2. The marker was developed in silico and experimentally tested on environmental samples. Gel and capillary electrophoreses for visualization of the PCR products were compared. 3. Marker specificity and sensitivity were assessed in vitro by cross-amplifications and serial dilutions, respectively. The method allows detecting at least 0.7 ng of Dreissena DNA per μL and cross-species amplification was not found in any case. 4. Next-generation sequencing (NGS) metabarcoding (PCR amplification and massive sequencing of a DNA barcode) was used as an independent method for verifying presence of Dreissena DNA molecules in environmental plankton samples collected from the south-eastern Baltic Sea. 5. The consistency between NGS results reporting presence of Dreissena and positive PCR amplification of the marker from the plankton samples confirmed the efficacy of this highly reproducible, fast, cheap and technically easy method