Annelid invaders in the Black Sea region: The distribution of Streblospio gynobranchiata and first occurrence of Laonome xeprovala

Abstract

The present study reports the spread of Streblospio gynobranchiata (Annelida, Spionidae) off Romanian coast and adjacent waters and the first occurrence of Laonome xeprovala (Annelida, Sabellidae) in the Black Sea basin. The spionid is considered among worst invaders in Mediterranean soft bottoms, while the sabellid is a new invader that successfully settled in the Baltic and the Azov Seas and, after a decade since first European report, finally reached the Black Sea (Musura Bay and Sakhalin Lagoon, Danube Delta). Based on 50 samples collected between 2011 and 2020, we provide an overview of the distribution and possible arrival pathways of both species. Their larval ecology and life traits suggest a secondary introduction through shipping. Since first report along the Romanian coast in 2011, S. gynobranchiata, has spread very quickly, reaching very high densities (4945.2 ± 7599.4 ind.m -2 ) at 11–15 m depth in infralittoral sandy-mud habitat of the Danube plume area, while L. xeprovala remains confined to estuarine habitats, reaching its highest abundance (100.8 ind.m -2 ) in Sakhalin Lagoon.