Streblospio cf. gynobranchiata (Polychaeta, Spionidae) from the Eastern Part of Taganrog Bay (Sea of Azov)

Until recently, there were only five polychaete species known from the Taganrog Bay and the delta of the Don River. However, over the last three years, the invasion of the exotic species has accelerated in the region. In 2013-2014, two alien polychaete species were introduced and successfully naturalized. In November 2015, we recorded another species, Streblospio cf. gynobranchiata. All the examined specimens match fully the descriptions of the Black Sea invaders. Even though the species introduction is still at the early stage, the species frequency of occurrence in the quantitative samples reaches 60%, increasing up to 80% when integral qualitative samples are also taken into account. The abundance of S. cf gynobranchiata averages 1406 specimens per square meter, increasing in accordance with an increase in the water salinity. However, the biomass rarely exceeds 0.001 g/m(2) at any of the sampling stations.