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

This study reports the presence of the ragged sea hare Bursatella leachii de Blainville 1817 in the Black Sea. A total of 484 specimens of this species were observed during scuba diving and snorkeling at depths ranging from 1.0 to 4.0 meters in September 2023. The samples were observed on the sandy-muddy bottom of Kumbaba Beach and the sandy bottom of Uzunkum Beach in Şile district (Istanbul province). The density of individuals per square meter of the seabed was calculated and the highest number of individuals was detected on the Kumbaba Beach near the mouth of the Türknil River. Considering the location of discovery, it is logical to assume that the introduction of this species into the Black Sea may have occurred naturally. This hypothesis can be supported for two main reasons; a) Şile beaches are a few kilometers away from the Bosphorus Channel, b) the report of B. leachii closest to Şile district dates back to January 2020, when the species was observed on the seabed on the southern coast of the Dardanelles. Long-term monitoring and more in-depth studies should be conducted in the region to give certainty to these hypotheses.