On the reproduction and dispersal of the nudibranch immigrant, Doridella obscura (Gastropoda, Opisthobranchia, Corambidae) in the Black Sea

The typical shallow-water, brackish-water North American nudibranch mollusk, Doridella obscura Verrill, 1870, invaded the Black Sea, apparently, through ballast waters of ships during the 1980s. However, only in November 1992 were numerous clutches of eggs discovered in nature (at Inkerman). This shows that D. obscura has, adapted to the Black Sea and is not resented exclusively by pseudopopulations sustained by veligers arriving in ballast waters.