Eutrophication of the Black Sea N. Berlinsky, Yu. Bogatova, G. Garkavaya Odessa Branch Institute of Biology of Southern Seas, National Academy of Sciences of Ukraine curriculum in natural environmental science, 2005

Sources of nutrients. Natural and anthropogenic sources of nutrients Specific characteristics of the basin as an area stressed by the Danube, Dniester and Dnieper river discharges Sources of nutrients. Natural and anthropogenic sources of nutrients Evolution of nutrient concentrations Ecosystem response on different trophic levels curriculum in natural environmental science, 2005

Black Sea Drainage Basin curriculum in natural environmental science, 2005

Hypoxia development in the Northwestern Part In 1973 – 1990 the zone of hypoxia (concentration of dissolved O2 less than 2 mg L-1) occupied 3,500 – 40,000 km2. It caused the mass mortality of 60 millions tons of bottom animals and 5,000 tons of fish, especially juvenile. curriculum in natural environmental science, 2005

Natural and Anthropogenic Sources of Nutrients in the Northwestern Part of the Black Sea river runoff atmospheric deposition municipal and industrial wastewater discharge bottom sediments, especially during eutrophication period curriculum in natural environmental science, 2005

River runoff The Danube - main river of the Black Sea The Danube (204 km3 year-1) provides up to 40 % of the fresh waters input into the sea. In high discharge year the area of the Danube influence occupies 70 % of the Northwestern part of the Black Sea. In low discharge year this area decreases up to 20 – 30 %. The total area of the Black Sea influenced by the Danube, according to the area of freshwater phytoplankton species recorded, is not less than 105 km2. At the beginning of the 70s, the nutrient load from the Danube river runoff has increased as a result of more intensive use of mineral fertilizers and increase in urban wastewaters. The coastal zone and the Northwestern part of the Black Sea experienced the development of phytoplankton blooms and near bottom hypoxia (concentration of dissolved oxygen less than 2 mg L-1). curriculum in natural environmental science, 2005

Construction of water reservoirs, use of fertilizers at the catchment area has changed nutrients volumes in the Danube runoff curriculum in natural environmental science, 2005

Water runoff (Q, km3·year-1) and nutrients runoff (103 t·year-1) of the Danube curriculum in natural environmental science, 2005

Input of Nutrients with the River Runoff into the Northwestern Part of the Black Sea (1950 – 2000) curriculum in natural environmental science, 2005

Nutrients concentrations in surface water (1), bottom water (2) and in sediment porewater (3) of the Danube coastal zone curriculum in natural environmental science, 2005

Nutrients concentrations in surface water (1), bottom water (2) and in sediment porewater (3) of the Danube coastal zone curriculum in natural environmental science, 2005

Relative contributions of point and non-point sources to phosphorus inputs to the NW shelf of the Black Sea in recent years   curriculum in natural environmental science, 2005

Relative contributions of point and non-point sources to nitrogen inputs to the NW shelf of the Black Sea in recent years curriculum in natural environmental science, 2005

Changes in concentrations of the main nutrients in the surface (а) and near bottom layers (b) of the Northwestern part of the Black Sea curriculum in natural environmental science, 2005

Changes on concentration of organic nitrogen and silica in the surface (а) and near bottom (b) layers in the Northwestern part of the Black Sea curriculum in natural environmental science, 2005

Ecosystem response on different tropic levels phytoplankton blooms blooms of one-celled animals and jellyfish decline in populations of large planktonic crustaceans decrease of water transparency and reduction in benthic macrophyte communities hypoxia and mass mortalities of bottom animals decreases in invertebrate standing stock curriculum in natural environmental science, 2005

Phytoplankton Blooms Zones of moderate (a) and intensive (b) summer phytoplankton blooms in the Black and Azov Seas (by Zaitsev & Mamaev, 1997 ) curriculum in natural environmental science, 2005

The Mediterranean and Black Seas (5 June, 2000; NASA data) curriculum in natural environmental science, 2005

Phytoplankton blooms in the Black Sea (5 June 2000;NASA data) curriculum in natural environmental science, 2005

The Decline in Populations of Large Crustaceans Specific impoverishment of bottom macrofauna on the Romanian shelf (by Zaitsev & Mamaev, 1997 ) curriculum in natural environmental science, 2005

Progressive reduction of “ Zernov’s Phyllophora field” in the Northwestern part of the Black Sea (by Zaitsev & Mamaev, 1997) curriculum in natural environmental science, 2005

Conclusion Recent eutrophication of the Northwestern part of the Black Sea is characterized by decreasing nutrients but increasing of organic compounds in river runoff and in marine water, because of regulation of all rivers entering the Sea and reduced use of mineral fertilizers in agriculture. However it is not correct to conclude to a decrease in eutrophication. Mineralization of organic compounds (N & P) enrich water masses with nutrients, which provokes phytoplankton development i.e. eutrophication. At present bottom sediments are also an important source of nutrients. The storage of organic matter in bottom sediments increases annually because of mass development of phytoplankton blooms. Upwelling contributes nitrogen and phosphorus compounds from the bottom sediments to biological cycles. The quantities of nutrients contributed by river runoff and bottom sediments are currently comparable. curriculum in natural environmental science, 2005