Introduction of species of genus Marenzelleria Mensil, 1896 (Polychaeta: Spionidae) in the Don River delta and Taganrog Bay

Abstract

Two alien polychaete species of genus Marenzelleria Mesnil, 1896 (fam. Spionidae) were recorded in the monitoring studies in the Don River delta and Taganrog Bay. The species of this genus as a rule occur in marine biotopes varying in the extent of desalination and were not recorded previously in the Azov-Black Sea basin. Adult specimens were collected in March–April and November 2014. In addition, high abundances of spionid nectochaetes supposedly belonging to these species were recorded in February 2014 in Taganrog Bay. Descriptions of sampled adult and larval specimens are given; two morphological groups are distinguished, followed by a discussion on their identity and possible consequences of their introduction. Presumably, transfer of pelagic larval stages in ballast water tanks from the Baltic Sea or North Sea was the main vector of their penetration into the study region.