Black Sea large marine ecosystem

March 14, 2011, 9:36 pm
Source: NOAA
Content Cover Image

Marshy Black Sea coastline near Histria, Romania. @ C.Michael Hogan

The Black Sea Large Marine Ecosystem (LME) is characterized by its temperate climate. It is an almost completely enclosed sea located off of the Mediterranean Sea. It is surrounded by six countries, Romania, Bulgaria, Turkey, Georgia, Ukraine and Russia. It communicates with the Mediterranean Sea LME through the Turkish Straits (Bosporus and Dardanelles), and receives freshwater from the Danube, Dniepr, Dniestr, Don, and Kuban Rivers. Eutrophication is the primary force driving the LME, with intensive fishing as the secondary driving force. The Global Environment Facility (GEF) is supporting an LME project in the Black Sea, to address critical threats to the coastal and marine environment, and to promote ecosystem-based management of coastal and marine resources.


caption Black Sea littoral and intertidal zone, southern Romania.
@ C.Michael Hogan

The Black Sea LME measures approximately 330 miles from North to South and 630 miles from East to West. The LME has a narrow continental shelf, except in the productive Sea of Azov. It is strongly influenced by river runoff and the lack of rapid exchange with the adjacent Mediterranean Sea LME. The Black Sea Large Marine Ecosystem is considered a Class I, highly productive (>300gC/m2-yr) ecosystem based on SeaWiFS global primary production estimates. River inflows contribute to high phytoplankton production in this LME. In some places, the Black Sea reaches a depth of more than 2200 metres. A distinctive feature of the Black Sea LME is the distribution of dissolved oxygen and hydrogen sulphide. Oxygen is nearly absent below 250 to 300 metres. Thus 90% of the LME’s volume is anoxic, the world’s largest such volume.

Fish and Fisheries

The Food and Agriculture Organization (FAO) 10-year trend shows an increase in the catch from 390,000 tons in 1990 to 500,000 in 1999. However, catch trends were irregular, with a peak of almost 600,000 tons in 1995, and two catch troughs, in 1991 and in 1998. The average catch is 500,000 tons. The most important species group in terms of shelf catches are clupeoids (herrings, sardines and anchovies). The combination of uncontrolled fisheries and eutrophication is causing important alterations in the structure and dynamics of this LME. Daskalov examines the effect of uncontrolled fisheries and of the removal of predators on trophic interactions. What he calls a trophic cascade is a reduction in apex predators leading to a higher abundance of planktivorous fish that feed on zooplankton biomass. Industrial fisheries began relatively early, especially for small pelagics such as anchovy. Demersal trawl fishery landings increased steadily after 1960.

By the early 1970s, most of the demersal resources of the Black Sea were close to maximum sustainable yield (MSY). In recent decades, landings of turbot, migratory pelagics, and anadromous species, especially sturgeon, have declined. The anchovy fishery has collapsed. There is now a decline for many demersal fish, for pelagic predators and for benthic invertebrates. Benthic systems are dominated by species such as Mya arenaria, better adapted to low-oxygen conditions. Increased salinity in the Sea of Azov, due to the reduction of freshwater inflow related to irrigation, appears to have affected species structure. This has changed the dominant species of ichthyofauna. There is a shortening of the food chain. Dolphins (common, harbor porpoise and bottlenose) are down to a population of 500,000 due to accidental killings, gill net fishing, the destruction of coastal ecosystems and various forms of pollution. Other marine mammals are critically endangered. The monk seal is virtually extinct. The productive fishery of the Black Sea Oyster, indigenous to the area, has been destroyed through the introduction of exotic species in ballast waters. The Global International Waters Assessment (GIWA) has issued a matrix that ranks LMEs according to the sustainable exploitation of fisheries and the predicted direction of future changes. GIWA characterizes the LME as severely impacted in terms of overfishing and destructive fishing practices. However, these impacts are decreasing. A fisheries convention is to be negotiated by the 6 Black Sea states to adopt an ecosystem based management approach. The University of British Columbia Fisheries Center has detailed fish catch statistics for this Large Marine Ecosystem. A graphical representation of the data is provided below.

Pollution and Ecosystem Health 

caption Black Sea coastal scene. Source: NOAA

The Black Sea area is a major industrial and agricultural region, with uncontrolled urban development. In coastal areas there are discharges from rivers, industry, agricultural pollution and domestic sewage. The LME has a huge drainage basin. There is an acceleration of eutrophication due to excessive levels of nitrogen loading. The combination of eutrophication and uncontrolled fisheries has caused important alterations in the structure and dynamics of this LME. The almost entirely enclosed nature of the LME contributes to the eutrophication problem. There is decreasing transparency of Black Sea waters. Beaches are littered, and there are regular beach closures due to sewage discharge problems. There is a growing risk of losing valuable habitats in these areas. While there is little data on toxic contamination and heavy metal accumulation, the Mussel Watch program in each of the six countries assesses areas with high pollution. A chemical pollution study for the Black Sea was completed by 98 Black Sea scientists. This resulted in the publication of a “State of Pollution of the Black Sea” report. Oil pollution comes from land-based sources, and from shipping. There has been a rapid increase in traffic in Black Sea ports, and an oil spill occurred in 1994 when the "Nassia" collided with an empty freighter. A report on Black Sea Pollution leading to the depletion of fishing stocks raised international concern. In the 1970s and 1980s there were frequent explosions of phytoplankton and jellyfish (Aurelia aurita). Blooms and red tides have been reported in the northern and western sections of the Black Sea. The Global International Waters Assessment (GIWA) has issued a matrix that ranks LMEs according to pollution. GIWA characterizes the LME as severely impacted in terms of eutrophication and ecotone modification. However, these impacts are not increasing, according to GIWA. A series of small GEF projects have focused on reducing nitrogen loadings from the 17 contributing nations of the Black Sea basin. Following the successful completion of a Transboundary Diagnostic Analysis (TDA) and a Strategic Action Programme (SAP) in the 1990s, there is a political commitment to reduce nutrients and abate persistent toxic substances being released from hotspots. Agriculture pollution is being reduced, and wetlands are being restored in the upstream basins to serve as nutrient sinks to protect the LME. A GEF Strategic Partnership is in place for 2001-2006, to assist the 17 nations.

Socioeconomic Conditions

caption Black Sea resort. Source: NOAA

The Black Sea LME has historically played a very important role, as a crossroads of Greek, oriental, southern, and western influences (through the Danube River). Peoples of many different languages, religions, trades and cultures, lived in this area together. Today, the area’s population is 165 million. The Black Sea watershed includes the six coastal countries of Romania, Bulgaria, Turkey, Georgia, Ukraine and Russia, as well as 11 others. The 17 countries have diverging socioeconomic and political structures. There are socioeconomic problems related to the transition of countries from the former Soviet Block to a market economy.

In ancient times, people depended on the Black Sea for fisheries resources, for transportation and for trade. The LME long supported a valuable fishery that was larger than that of the Mediterranean. Fish in these earlier times served as a basis for trade with other areas. Fish, sun-dried or cured with salt, from the Dnieper and Danube estuaries was exchanged for pottery from the Aegean Sea. The Black Sea coast contains many ports for ocean transport and facilities for recreation. It is served by large harbors, and by industrial and resort cities. The city of Istanbul (formerly Byzantium and Constantinople) has played a major historical role. Shipping via the Turkish straits is a major activity. Oil is piped to Black Sea harbours for transportation. The LME’s environmental degradation has economic and social consequences. The fisheries collapse has created a crisis in employment in the fisheries sector and has reduced food security in protein resources. As a result of the reduced availability of fish, market prices for fish have risen. Aquaculture shows promise but is still at an early stage. There is a long experience of sturgeon culture in the Azov Sea. More recent ventures involve the cultivation of mussels, oysters and Atlantic salmon. Aquaculture would provide an important local source of food, income and employment for fishermen displaced by the stock collapse. Sustainable tourism must address the problems of beach degradation, coastal erosion, water quality and water supply. Reductions in freshwater flow, due to irrigation, have had a major effect on estuarine fauna. Regular beach closures due to sewage discharge problems affect the tourist industry in the region.


In this LME and its large drainage basin, the Global Environment Facility (GEF) is supporting its biggest international waters initiative for environmental improvements. This is occurring despite difficulties due to the number of countries and stakeholders involved, and difficulties in harmonizing objectives. Many of these countries are undergoing political change. Romania, Bulgaria, Georgia and Ukraine have emerged from under the aegis of the former Soviet Union. In the early 1990s, a series of small GEF projects focused on reducing nitrogen loadings from the 17 contributing nations. A TDA and SAP process (see Pollution and Ecosystem Health) was completed in the 1990s. For more information on the perceived transboundary problems and areas where action is proposed to reduce pollution, manage living resources and sustain human development, see GEF, 1997. See the Black Sea Strategic Action Plan (SAP), signed by the six Ministers of Environment of the coastal Black Sea countries in 1996. The Black Sea and Danube Basin countries are collaborating in an effort to uncover the needed policy, institutional, and legal reforms in each country. There is a need to increase the level of public concern, increase the flow of information between the countries and involve the public in environmental decision-making. There is a commitment to achieve nutrient reduction and to abate persistent toxic substances being released from hotspots. Reforms in policy, laws, institutions and investments are now being supported by GEF in each country for nitrogen abatement from the agriculture, municipal, and industrial sectors. There is community and NGO participation for mobilizing support for hotspot cleanup. Protocols to 2 conventions, the Bucharest Convention and the Istanbul Convention, are to be adopted that codify country commitments. See the fisheries convention, under Fish and Fisheries.


Articles and LME Volumes

  • Caddy, John F, 1993. "Contrast Between Recent Fishery Trends and Evidence for Nutrient Enrichment in Two Large Marine Ecosystems: The Mediterranean and the Black Seas," in Kenneth Sherman, et al. (eds.), Large Marine Ecosystems: Stress, Mitigation, and Sustainability (Washington, D.C.: American Association for the Advancement of Science) pp.137-147. ISBN: 087168506X
  • Daskalov, G.M., 2002. Overfishing drives a trophic cascade in the Black Sea. Marine Ecology Progress Series, 225:53-63.
  • Alfred M. Duda and Kenneth Sherman. 2002. A new imperative for improving management of large marine ecosystems. Ocean and Coastal Management Vol 45 797-833.
  • FAO, 2003. Trends in oceanic captures and clustering of large marine ecosystems—2 studies based on the FAO capture database. FAO fisheries technical paper 435. 71 pages. FAO Fisheries & Aquaculture-Large Marine Ecosystems
  • GEF, 1996. Strategic Action Plan for the Rehabilitation and Protection of the Black Sea. 29p. Strategic Action Plan for the Rehabilitation and Protection of the Black Sea
  • GEF, 1997. Black Sea Transboundary Diagnostic Analysis. UNEP, New York, 142 pages. ISBN: 9211260752
  • Sorokin, Y.I., 1985. The Black Sea. In: Ecosystems of the World, Estuaries and closed seas, B.H. Ketchum, ed. 253-292. ISBN: 0444419217

Other References

  • Ascherson, N. 1995. Black Sea. Hill and Wang. 305 pages.
  • Balkas, T., et al. 1990. Review of the state of the marine environment of the Black Sea. UNEP Reg. Seas Rep. Stud. No. 124. UNEP, Nairobi.
  • Bologa AS, Bodeanu N, Petran A, Tiganus V, and Zaitzev Yup, 1995. Major modifications of the Black Sea benthic and biotic biota in the last three decades. In: Briand F (ed), Les mers tributaires de Mediterranee. Bulletin de l’Institut oceanographique, Monaco, numero special 15, CIESM Science Series No. 1, p. 85-110.
  • Hey, E. and L.D. Mee, 1993. Black Sea. The Ministerial Declaration: an Important Step. Envir. Pollution Law, 2315, 215-217 and 235-236.
  • Hobson, S. and L.D. Mee, eds, 1998. The Black Sea in Crisis. Religion, Science and the Environment. World Scientific. 262 pages.
  • Ivanov, L. and Beverton, R.J.H. 1985. The fisheries resources of the Mediterranean. Part II. Black Sea GFCM Studies and Reviews. No. 50. FAO, Rome.
  • Kideys, A.E., Recent dramatic changes in the Black Sea ecosystem: the reason for the sharp decline in Turkish anchovy fisheries. J. of Mar. Systems 5:171-181.
  • Mamaev, V.O., D.G. Aubrey, and V.N. Eremeev, eds., 1995. Black Sea bibliography. UN Publ. New York. 364 p.
  • Mee, L. 1992. The Black sea in crisis: a need for concerted international action. Ambio 21 (4):1278-1286.
  • Naegele, J. Turkey: Black Sea Pollution Depletes Fishing Stocks.
  • Zaitsev, Y. and V. Mamaev. 1997. Marine Biological Diversity in the Black Sea: A Study of Change and Decline. Black Sea Environmental Series Vol 3. New York: United Nations Publications. 208 p.



Disclaimer: This article is contains some information that was originally published by the National Oceanic and Atmospheric Administration. Topic editors and authors for the Encyclopedia of Earth have edited its content and added new information. The use of information from the National Oceanic and Atmospheric Administration should not be construed as support for or endorsement by that organization for any new information added by EoE personnel, or for any editing of the original content.






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