Compilation, Revision, and Annotation of DNA Barcodes of Marine Invertebrate Non-Indigenous Species (NIS) Occurring in European Coastal Regions

The introduction of non-indigenous species (NIS) is one the major threats to integrity European coastal ecosystems. DNA-based assessments have been increasingly adopted for monitoring NIS. However, accuracy taxonomic assignments largely dependent on completion and reliability DNA barcode reference libraries. As such, we aimed compile audit a library marine invertebrate NIS occurring in Europe. To do so, compiled list using three databases: Alien Species Information Network (EASIN), System Aquatic Non-indigenous Cryptogenic (AquaNIS), World Register Introduced Marine (WRiMS). For each species, retrieved available cytochrome c oxidase subunit I (COI) mitochondrial gene sequences from Barcode Life Data (BOLD) used Barcode, Audit & Grade (BAGS) check congruence between morphospecies names Index Numbers (BINs). From 1249 compiled, approximately 42% had records BOLD, among which 56% were discordant. We further analyzed these cases determine causes discordances attributed additional annotation tags. Of 622 discordant BINs, after revision, 35% successfully solved, increased number detected metabarcoding datasets 12 16. fair BINs remained Reliability particularly critical case NIS, where erroneous identification may trigger action or inaction when not required.