Characteristics of Up-Welling Algal Bloom and Hypoxia Events In the Western Black Sea in 2010

The year 2010 was characterized by extreme hydro-meteorological events. In situ sea water temperature, salinity, dissolved oxygen, chlorophyll a and the atmospheric wind stresses at the Constanta shore station (44 degree 14' N, 28 degree 38'E) and on the Romanian Black Sea shelf were used to study the up-welling, algal bloom and hypoxia events that occurred in 2010. The highly productive zones in the Western Black Sea coast are usually associated with the up-welling phenomena which contribute to the heterogeneous distribution of chlorophyll-a, suspended and dissolved organic matter. The occurrence and extent of these events during 2010 are validated with MODIS - AQUA satellite images (Sea Surface Temperature (SST), Chl_a) and with the results of the regional forecast system for the Western Black Sea. The unusual high values of air temperatures recorded in the summer of 2010 and the limited deep water mixing lead to the high values of sea water temperature (26-28 degree C) favoring the strong algal bloom on the southern part of the Romanian Black Sea Coast. The low oxygen concentration (a minimum of 34.80 mu M recorded at Constanta) was measured from the coast up to 16 km offshore in the sea upper layer, causing the local hypoxia event observed in the shallow water near the coast.