Mediterranean Sea large marine ecosystem

Introduction

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The Mediterranean Sea Large Marine Ecosystem (LME) is characterized by its temperate climate. It is a semi-enclosed sea with several distinct biogeographical sub-units. It is bordered by a high number of countries. Intensive fishing is the primary force driving the LME, with eutrophication as the secondary driving force. The Global Environment Facility (GEF) is supporting an LME project in the Mediterranean Sea, to address critical threats to the coastal and marine environment, and to promote ecosystem-based management of coastal and marine resources. LME book chapters and articles pertaining to this LME include Bombace, 1993 (about the sub-unit of the Adriatic Sea), and Caddy, 1993.

Productivity

The Mediterranean Sea has a narrow continental shelf. For the origin and history of the Mediterranean and Adriatic Seas, see Bombace, 1993. The LME presents a composite structure of environmental conditions, with local areas of upwelling, wind-driven currents, high water temperatures at least in some periods of the year, and nutrient inputs from rivers and human activities (see Caddy, 1993). The major inflow into the Mediterranean is nutrient-poor, oxygenated Atlantic surface water through the Strait of Gibraltar, resulting in generally well-oxygenated bottom waters. Gyres and upwellings contribute to the Adriatic Sea’s high phytoplankton productivity. The highest levels of productivity occur along the coasts, near major cities, and at river estuaries. The lowest levels occur in the southeastern Mediterranean (see Darmouli, 1988). Overall, the Mediterranean Sea LME is considered a Class III, low (<150 grams of Carbon per square meter per year (gC/m2-yr)) productivity ecosystem, based on SeaWiFS global primary productivity estimates. For an oceanographic overview of the Mediterranean Sea and its hydrographic inputs and primary production, see Caddy, 1993. The Mediterranean has unusual biodiversity for a temperate sea (see FAO, 2003). Temperature stratification can occur during extended periods of calm seas, high temperatures, and inflows of freshwater. This separates the warmer, less saline surface water from the deeper, colder and more saline water, resulting in autumnal algal blooms and extended hypoxia or anoxia.

Fish and Fisheries

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This is one of the most diverse and stable LMEs in terms of species groupings and their share in the total catch. The Food and Agriculture Organization (FAO) 10-year capture trend (1990-1999) shows stable catch trends in recent years, with a moderate increase in shelf catch, from under 1 million tons in 1990 to 1.1 million tons in 1999 (see FAO, 2003, figure 20). Clupeoids (herrings, sardines and anchovies) form the most important species group with 38% of catch. Miscellaneous coastal fishes account for 18% of the catch, and mollusks for 16%. For more information on primary production and fisheries, see Caddy, 1993. For a study on ecology and fisheries in the Adriatic Sea, see Bombace, 1993. |Technological improvements in the fishing fleet and increased fishing capabilities have resulted in a decline in the catch rate per boat (see Caddy, 1993). Fishing effort has increased in response to high fish prices. By the 1970s, a substantial portion of the less productive southern shelves was being harvested for demersal resources. This also involved distant-water trawlers, with the result that demersal resources were fished at close to maximum sustainable yield. In the Adriatic Sea, coastal pollution and eutrophication have been the principal factors driving change in fisheries yields. Fish kills have occurred in the northern Adriatic as a result of noxious phytoplankton blooms and anoxic conditions. For more information on demersal and pelagic fish and mollusks in the Adriatic, see Bombace, 1993. The University of British Columbia Fisheries Center has detailed fish catch statistics for this LME. A graphical representation is provided below. The FAO also has information on the decadal trend (1990-1999) for fisheries in this LME.

Pollution and Ecosystem Health

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There are concerns over the decline, especially in the northern Mediterranean, of fish species and species diversity. Negative anthropogenic impacts on fisheries are untreated sewage and an increased incidence of toxic blooms. However, quantifying these effects and establishing the respective contributions of overfishing and eutrophication are problematic (see Caddy, 1993). Blooms of phytoplankton and benthic diatoms have resulted in local fish kills caused by anoxia. Planktonic blooms and sewage contamination of coastal waters have also caused health problems associated with the ingestion of contaminated shellfish (see UNEP/FAO, 1990; and Caddy, 1993). Major threats to the biodiversity of the region’s coastal and wetland ecosystems are: uncontrolled development, urbanization, and especially pollution from land-based sources such as industry, human sewage and agriculture, which enter the Mediterranean via runoff, discharge, and river transport. The atmosphere contributes nitrogenous compounds, contaminants, and heavy metals (see Caddy, 1993; and UNEP, 1989). GEF assistance has resulted in a Strategic Action Programme (SAP) for land-based sources of marine pollution, living resources and critical habitats. This was adopted by all 20 nations under the Barcelona Convention (see governance, see Mediterranean Action Plan, 1999).

Socioeconomic Conditions

The Mediterranean Sea’s 26,000 kilometers of coast supports a population estimated at 132 million inhabitants. The figures swell in the summer months, as tourists flock to the region, attracted by its cultures and pleasant climate. The continuous increase of tourists and settlers is a boon to the region, and is today of higher economic value than fisheries in many Mediterranean countries (see Caddy, 1993). But tourism is also causing environmental degradation through extensive development, added pressure to the coastal areas, and stress on the marine environment. The region, situated at the crossroads of Africa, Europe and Asia, has a high diversity of cultures, countries, political systems, and religions. It contains major population centers and industrial activities. Numerous fishing ports are dispersed along the Mediterranean coastline. For a historical perspective on fisheries in the Mediterranean Sea, see Caddy, 1993. Fisheries production has increased in many areas and is of major economic importance. Mariculture has increased production figures for mussels and oysters. Anthropogenic nutrient enrichment and eutrophication caused by runoff and polluted river discharges are a concern both for fisheries and tourism revenues.

Governance

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Governance of the Mediterranean Sea LME involves a high number of countries (20 countries). They differ in their stage of economic and institutional development and in their capacity to address biodiversity issues in the context of sustainable development. The Mediterranean Sea LME was the first region to be addressed by UNEP’s Regional Seas Program in 1974 (see Caddy, 1993; and UNEP, 1989). ). MEDPOL was a pollution monitoring and assessment program that was started in the mid-1970s. With GEF support, the Mediterranean countries are jointly addressing coastal and marine issues. GEF projects involve the conservation of wetlands and coastal ecosystems, and the building of country capacity. Mediterranean countries in a Transboundary Diagnostic Analysis (TDA) are analyzing factual and scientific information on transboundary concerns and their root causes, and they are setting priorities for action (see Mediterranean Action Plan, 1999). They are determining national and regional policy, legal and institutional reforms and investments needed to address priorities within the LME. They have committed to pollution reduction for specific pollutants with specific timetables and targets. A Strategic Action Programme (SAP) for land based sources of marine pollution was adopted by all 20 countries under the Barcelona Convention. Future priorities are living resources and their critical habitats, with programs to be developed in conjunction with a review of the European Union’s Common Fisheries Policy. A greater coordination of scientific studies of fish resources and of the biological and oceanographic environment is necessary (see Caddy, 1993). Existing legislation pertaining to ecosystem management includes the Barcelona Convention (1976); the Protocol for the Prevention of Pollution by Dumping from Ships and Aircraft; and the Protocol for the Protection of the Mediterranean Sea against Pollution from Land Based sources (1996).

References

Articles and LME Volumes

  • Bombace, Giovanni. 1993. "Ecological and Fishing Features of the Adriatic Sea," in Kenneth Sherman, et al. (eds.), Large Marine Ecosystems: Stress, Mitigation, and Sustainability (Washington, D.C.: American Association for the Advancement of Science, 1993) pp. 119-136. ISBN: 087168506X.
  • FAO, 2003. Trends in oceanic captures and clustering of large marine ecosystems—2 studies based on theFAO capture database. FAO fisheries technical paper 435. 71 pages.
  • Caddy, John F. 1993. "Contrast Between recent Fishery Trends and Evidence from 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, 1993) pp. 137-147. ISBN: 087168506X.

Other References

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(2008). Mediterranean Sea large marine ecosystem. Retrieved from http://www.eoearth.org/view/article/51cbee6c7896bb431f697bcf

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