Spatial analysis of salinity distribution patterns in upper layers of the Black Sea

Abstract

Salinity is one of the most important factors that primarily determines the level of seawater’s density and, consequently, the movement of water masses in the World Ocean. Spatial distribution of the salinity in different layers of the Black Sea are associated with varying levels of water balance seasonal variability and, general circulation of Black Seas waters and in the surface layer has a seasonal structure. To study spatial distribution of salinity in upper layers of the Black Sea we’ve used data from Copernicus Marine Environment Monitoring Service, that were processed and aggregate by seasons and depth. We found that the most fluctuated layer is a top layer (up to 2.8 m) and the highest values Black Sea salinity reaches near the Bosporus Strait, where more saline water from the Sea of Marmara connected with fresher water of the Black Sea. Also we found that the impact of the river flows, mixing of the water, water regime of the sea decreasing with depth, so in the bottom of the upper layer the spatial fluctuation of the salinity is minimal and reaches about ±3‰, while in the depth of 2.8 m its reaches ±12-15‰.The lowest level of salinity through all of the upper layer (0-50 m) lays around the seashore and north-western part of the sea.

Response of the Coastal Phytoplankton Community to the Runoff from Small Rivers in the Northeastern Black Sea

“…Among which are the significant continental freshwater runoff that exceeds the evaporation level, the relative isolation of the water basin, limited connection with the more saline and denser Mediterranean Sea waters, and the bottom topography-all of which prevent vertical mixing of water [1]. The average salinity in Black Sea surface water is about 18 [2].…”

“…The coastal zone of the Black Sea is the most desalinated due to significant river runoff with an average annual discharge of 348 km 3 per year [3]. Salinity can decrease to less than 9 near estuaries [2]. The northwestern (NW) Black Sea is the most freshened.…”

“…The fresh water interacts with the narrow shelf zone, mostly less than 11 km wide and no more than 40 km at its widest. The narrow shelf stretches along the coastline for only about 3000 km 2 . Interaction between fresh and seawaters forms local desalinated areas called plumes with a salinity up to 16 on the surface [18].…”