Firts records of Bursatella leachii de Blainville 1817 (Mollusca; Gastropoda; Aplysiidae) in Black Sea

Abstract

ABSTRACT This study reports, for the first time, the discovery of the ragged sea hare Bursatella leachii de Blainville 1817 in the Black Sea. The observations were made during the month of September 2023 at depths varying between 1,0 and 4,0 meters by scuba and snorkeling. A total of 484 specimens of this species were found. Of these, a part were observed in the sandy-muddy bottom of Kumbaba beach and a part in the sandy bottom of Uzunkum beach, in the Sile district (Istanbul province). The estimate of the density of individuals per square meter of seabed made it possible to highlight how the high number of individuals was present on the Kumbaba beach near the mouth of the Türknil river. It could be hypothesized that the introduction of this species into Black Sea could have occurred through natural means. This may have been possible for two reasons; the first is that the beaches of Sile are a few kilometers from the Bosphorus Canal while the other reason lies in the fact that the report of B. leachii closest to the town of Sile dates back to January 2020, when the species was observed in the seabed of the coast southern Dardanelles (Çanakkale Strait). To be certain of what has been stated, monitoring should be carried out on a regular basis but, at this moment, this hypothesis appears to be the most real. Keywords: Bursatella leachii, Black Sea, Turkey, AIS, NIS