Gulf of Finland

Baltic sea area

Baltic sea area. Source: wikipedia

Gulf of Finland is the easternmost arm of the Baltic Sea, located at around 59°50′N 26°00′E.Its length is 400 km, width 48-135 km, average depth 37 m, maximum depth 123 m, total area 29 570 km2, and volume 1100 km3. The surface water salinity varies between  0 – ca. 7 and the near-bottom water salinity between 0.3 –  8.5, lowest values occurring in the east and near river mouths and the highest in the west, near the northern Baltic Proper.The Gulf of Finland is west-east shaped elongated bay – an extension of the main basin of the Baltic Proper. The Northern coast of the Gulf is multiform: high and winding, with abundant small bays,skerries and rocky islands. The Southern shores are smooth and shallow, but along the entire coast runs the Baltic Klint – an erosional limestone escarpment with the height up to 55 m. In the middle of the Gulf, there is the natural border on the bottom surface between granite bedrock in the North and limestone bedrock in the South.
The Gulf of Finland receives major human pressures: high input of nutrients, organic matter and hazardous substances, as well as heavy maritime transport.  It is the most eutrophied sub-basin of the Baltic Sea, with a drainage area of 420 990 km2, which is ca 20% of the drainage area of the whole Baltic Sea; the volume of the Gulf of Finland is – however – only 5% of the total water volume. The external nutrient load relative to its surface area is two to three times that of the corresponding average for the whole Baltic Sea.The Gulf receives direct nutrient loading from three surrounding countries: Finland, Russia and Estonia. The River Neva (the biggest river in the Baltic Sea) is the largest single source of total nitrogen into the Gulf of Finland and the city of St Petersburg is the largest source of external phosphorus load.The Gulf of Finland is home to species of both marine and limnic origin.

Gulf of Finland

Gulf of Finland. Source: wikipedia

According to the HELCOM Red list, more than 700 macro-species have been observed in the area, a figure much higher than that of adjacent sea areas. The Gulf of Finland is also an important resting and breeding area of many migratory bird species.