Seasonal and Interannual Variability of Phytoplankton in the Black Sea on the Basis of Remote Sensing Data and In Situ Measurements of Chlorophyll-a

The patterns of the seasonal and interannual variability in the development of phytoplankton, including coccolithophores, were studied in the northeastern part of the Black Sea in various seasons. The research was carried out on the basis of long-term observations and data provided by the Modis Aqua ocean color scanner. This paper reports that, in the coastal and open waters of the Black Sea, the development of phytoplankton reaches the highest level in the fall-winter and winter-spring seasons, i.e., in the periods of active winter convection. Coastal waters are also characterized by expressed spring peak of chlorophyll a concentrations associated with phytoplankton bloom in March. Winter and spring coccolithophore blooms, which are unusual for the Black Sea, were registered on the basis of satellite data. It was noted that there is a relationship between the level of coccolithophore development in the summer period and the minimal temperature of the sea surface layer in the preceding winter. The most active coccolithophore blooms, which were registered in 2006 and 2012, were observed after the coldest winters.