ABSTRACT
The Mediterranean is a land-locked sea connected to the Atlantic Ocean via the Strait of Gibraltar. There are two main basins, eastern and western, and communication between them is across sills in the Strait of Sicily and Strait of Messina. The annual rainfall and the contribution of fresh water via rivers is less than the water lost by evaporation from the sea surface. Consequently, water is drawn in from the North Atlantic and it flows along the coast of North Africa towards the east. Surface salinities increase from ∼35‰ at the Strait of Gibraltar to ∼39‰ in the eastern Mediterranean. During the winter, the more saline surface waters cool and therefore become more dense, and they sink into the deep basins. The latter are filled with relatively warm (∼13 °C) more saline waters (>38‰). Circulation in the eastern basin is sluggish and the waters are somewhat depleted in oxygen although not dysaerobic (∼4.5 ml 1-1). However, in the past anoxic conditions have developed. There is an outflow of MW at a depth >300 m through the Strait of Gibraltar into the North Atlantic. The water in the Mediterranean is renewed in about 75 years (Sverdrup et al . 1942). For a general review of the sediments and geology see Stanley (1972). Localities are shown in Fig. 11.1 and surface-water temperature in Fig. 11.2.
