Hydrophysical factors of coccolithophores Emiliania huxleyi intensive bloom formation in the Abkhazian sector of the Black Sea at the end of May 2013

Abstract

At the end of May 2013, in the Abkhazian sector of the north-eastern part of the Black Sea, intensive blooms of Emiliania huxleyi coccolithophores of up to 4,4×106 cells/L were observed. In order to identify the necessary and sufficient hydrophysical conditions for the blooming of this alga at 15 stations of the water area, the spatial distribution of hydrophysical parameters was investigated. It is shown that the vertical distribution of temperature, salinity and density is typical for this time of year and is characterized by the presence of a sharp-gradient seasonal thermocline. The horizontal distribution of the main hydrophysical parameters on the surface water was as follows: at an average temperature of 20,209±1,027°C, the areas of elevated temperatures were located in the coastal zone, for salinity (17,585±0,556 psu) the reverse distribution was observed. Variations of conditional density were 11,477±0,516. A characteristic feature of 2013 was the renewal of the Cold Intermediate Layer (CIL) in the winter period. During the bloom period, the coccolithophores tended to be deepened along the coordinate from the center of the sea to the coast. Variations in the speed of geostrophic currents from 3,58 to 22,43 cm/s did not lead to the destruction of the bloom.