Features of the Biological State of the Smooth Scallop (Flexopecten glaber (Linnaeus, 1758), Bivalvia, Pectinidae) in a Sand Mining Area in the Black Sea

Using the Flexopecten glaber scallop population in Donuzlav Bay as an example, the main biological indicators of specimens sampled synchronously in two test areas were examined and compared: (1) a zone under the direct influence of sand mining, and (2) an intact zone with a natural sedimentation process. The sea scallop was found in Donuzlav Bay at depths ranging from 0.5 to 17 m, but its distribution was discontinuous and uneven. The main clusters of F. glaber were concentrated at depths of 2–3 m, where the density of scallops in some areas of the intact zone reached 12 specimens per square meter. In the distribution zone of turbidity from sand washing, the density of scallops reached six specimens per square meter. For scallops from both test samples, the age structure of settlements, the average values of size–weight characteristics, and the stages of gonad formation were shown to be quite close. However, in scallops from the conditionally intact zone, the average gonad mass was twice as large and the gonadal index was 1.5 times higher. The scallops of the unaffected zone had gonads that were not only larger, but also brighter and more varied in color. These and other characteristics studied indicate that scallops in the turbidity zone affected by sand mining were physiologically suppressed. Despite some signs of improvement in the status of the F. glaber population in the Black Sea, the need to maintain conservation measures for the species and to strengthen these measures in areas with an increased anthropogenic influence is highlighted.