| Description |
The Mediterranean is a semi-enclosed sea, with a turnover period of approximately 80 years for water entering through the Straits of Gibraltar. (UNEP, 1989) The Mediterranean Sea contains a narrow shelf, with wider shelves and areas of higher productivity in the Adriatic and the Gulfs of Lions and Gabes. (Caddy, 1993). Several distinct biogeographical districts can be identified: the Alboran Sea; the Western Mediterranean; the Eastern Mediterranean; and the Adriatic. (Bombace, 1993) The Black Sea, included in biogeographical discussions of the Mediterranean, is discussed separately under LME 26. Through much of this summary, the Adriatic is discussed separately. The Mediterranean is bordered by arid or semi-arid lands to the south and east. The major inflow to the Mediterranean is nutrient-poor, oxygenated Atlantic surface water through the Straits of Gibraltar, resulting in generally well-oxygenated bottom waters. Nutrient levels are relatively low down to approximately 3,000 m, decreasing from west to east and from north to south, with low levels in the Levant area (Cuddy, 1993; Murdoch and Onuf, 1972). The outflow of highly saline bottom water through the Straits of Gibraltar is richer in nutrients. Freshwater inflows are relatively low, and only approximately 10 percent, including the Nile, enters along the southern shores. Evaporation approximately equals inputs, especially in the Levant Basin. Freshwater inputs, especially from the Nile, have been substantially reduced in the past decades by increased fresh water use, resulting in a decline in nutrient enrichment in the nutrient-poor eastern Mediterranean, reducing freshwater inputs, and perhaps facilitating colonization of the waters by species adapted to higher salinities. Nutrient levels in the remaining flows have increased. (Caddy, 1993; Por, 1978). The Mediterranean Sea coast has a large population, estimated at 132 million inhabitants and a very large transient population. With heavy use of its coastal and marine resources and severe threats from pollution, the Mediterranean was the first region to be addressed in the United Nations Environment Program (UNEP) Regional Seas Program, beginning in 1974, moving to an Action Program in 1975. (Caddy, 1993; UNEP, 1989) (http://www.na.nmfs.gov/lme/text/lme26.htm)
Not including the Black Sea (repair sq km). |
