The First Record of Marenzelleria neglecta and the Spread of Laonome xeprovala in the Danube Delta–Black Sea Ecosystem

Biological invasions can have major impacts on freshwater and marine ecosystems. Therefore, it is vital that non-indigenous species are accurately identified reported when potential or confirmed occur. The present study reports the first occurrence of Marenzelleria neglecta (Annelida, Spionidae) spread Laonome xeprovala Sabellidae) in Danube Delta–Black Sea ecosystem. Spionidae one most diverse families annelid worms a dominant group terms number been introduced to non-native areas, while members Sabellidae among visible polychaetes commonly found fouling communities colonizing new geographic areas. Based 20 samples collected 2021, we provide an overview distribution investigated possible arrival pathways for neglecta. Specimens were based morphological descriptions. Both invasive behaviour, large areas relatively short time periods reaching high densities (M. neglecta—1400 ind.m?2; L. xeprovala—40 ind.m?2). Due their abundances, biology ecology these River–Danube system need be further order assess impact ecosystem structure functioning.