Increase in findings of Mediterranean nonnative species in the Black Sea

Data from our investigations and other publications on the Mediterranean species records in the Black Sea are summarized in the article. The number of such findings has increased in the last decades both in the southern Black Sea, where these species have always occurred, and in the other areas of the Black Sea owing to a rise of the water surface layer temperature and more intense shipping. The vectors of species penetrations, their possibility of establishment, and their role played in the ecosystem are discussed.