Species Composition and Distribution of the Mussels (Mollusca: Bivalvia) in the Bulgarian Sector of the Black Sea

A total of 11 orders, 22 families, 45 genera and 48 species of mussels are known from the Bulgarian aquatory of the Black Sea. They are divided into 23 zoogeographical categories. The predominant part of them are Atlantic-Mediterranean elements (30 species or 62.5%). In the Bulgarian shelf there are from eight to 12 biocenoses and a large number of groups, which are characterised by specific types of mussels. The belts of Mytilus galloprovincialis and Modiolula phaseolina are typical of the Black Sea. Biogenic reefs built by Ostrea edulis but without living forms have been established. Four alien species are recorded, of which two are invasive. Nineteen species (39.6%) have a conservation value.