Development an Blooms of Peridinea Akashivo sanguinea in the Bulgarian Marine Aquatories

The article presents results of empirical field research on the development and distribution of the ''unarmoured'' peridinea Akashivo sanguinea in the Bulgarian marine aquatories during the period 1995-2015. The analysis has established that A. sanguinea is a phytoplankton species relatively rarely met in the water in front of the Bulgarian coast. The development and blooms of the species have been identified both in the surface water layer and up to 25 m (layer above the thermocline). It developed mainly in water areas rich in nutrients (Varna Bay, Burgas Bay, Balchik), but also in open sea areas (10-30 miles offshore), probably under the influence of the Danube inflow. Basically the blooms of the species were recorded in the mid-90s and at the beginning of the new century (2001). After this period the concentrations of A. sanguinea were minimal. A constant trend of reducing the size of the cells of the species has been registered. The purpose of this study was to describe, track and analyze the patterns in the development and distribution of the phytoplankton species A. sanguinea in the Bulgarian marine aquatories during that 20 year period.