DNA barcode reference libraries for the monitoring of aquatic biota in Europe: Gap-analysis and recommendations for future work

For aquatic ecosystems in Europe, reliable barcode reference libraries are particularly important if molecular identification tools are to be implemented in biomonitoring and reports in the context of the EU Water Framework Directive (WFD) and the Marine Strategy Framework Directive (MSFD). Researcher of the DNAquaNet WG I (https://dnaqua.net/) recently published preprint analysed gaps in the two most important reference databases, Barcode of Life Data Systems (BOLD) and NCBI GenBank, with a focus on the taxa most frequently used in WFD and MSFD. The results have implications for the future strategy to fill existing gaps in barcode libraries. The paper discusses why quality assurance of barcode reference libraries is needed and recommends future steps to ensure full utilization of metabarcoding in aquatic biomonitoring.