Distribution of alien polychaetes in biotopes of the northern part of the Black Sea.
The article analyzes the distribution of alien polychaetes in the northern part of the Black Sea using the original material collected in 1998-2019, which includes ten species from five families, and published data. The family Spionidae is represented by five species; two species belong to the family Serpulidae; and the families Pilargiidae, Scalibregmatidae, and Sabellidae are represented by one species each. The distribution of polychaetes across the biotopes of the northern part of the Black Sea is as follows: Polydora cornuta Bosc, 1802 and Streblospio gynobranchiata Rise & Levin, 1998 are widely distributed on soft bottom sediments in the shallow area of semi-enclosed bays, lagoons and ports. Similarly, Sigambra tentaculata (Treadwell, 1941) is recorded from soft substrates in shallow waters, but largely occurs at the coast that fronts on the open waters. Dipolydora quadrilobata (Jacobi, 1883) is the only representative of the deep-water area of the Black Sea. The species Marenzellerianeglecta Sikorski & Bick, 2004 and Hyboscolex cf. pacificus (Moore, 1909) are occasionally encountered on soft bottom sediments. Hydroides dianthus (Verrill, 1873) and Pseudopotamilla cf. reniformis (Bruguière, 1789) are recorded from fouling (or other styles of attachment) on hard substrates, as well as Ficopomatus enigmaticus (Fauvel, 1923), whose status of an introduced species needs clarification. Two species, Polydora websteri Hartman in Loosanoff & Engle, 1943 and H. dianthus, which settle on the shells of mollusks, while negatively affecting them, can be classified as invasive species. In the Black Sea basin, polychaetes were probably introduced at the pelagic stage with ballast waters or in fouling of ships. The species F. enigmaticus, P. cornuta, and S. tentaculata introduced to the Black Sea more than 60 years ago can be considered fully naturalized.