Mediterranean Sea

Lore & Background

The Mediterranean Sea is classified as a concentration basin as a whole, meaning it has a higher salinity than the outer ocean due to evaporation, with water exchange consisting of inflow of fresher oceanic water in the upper layer and outflow of saltier mediterranean water in the lower layer of the connecting channel. However, the Adriatic Sea and the Black Sea are dilution basins, having lower salinity due to freshwater gains from rivers: the Adriatic Sea from the Po River, and the Black Sea from the Danube, Dnieper, and Don rivers. In a dilution basin, water exchange consists of outflow of fresher mediterranean water in the upper layer and inflow of saltier oceanic water in the lower layer, and renewal of deep water may not be sufficient to supply oxygen to the bottom.

Reader's Guide

The Mediterranean Sea is the namesake for the oceanographic term 'mediterranean sea,' defined as a mostly enclosed sea with limited water exchange with outer oceans, where circulation is dominated by salinity and temperature differences rather than by winds or tides. As a concentration basin overall, it experiences higher salinity from evaporation, drawing in fresher oceanic water at the surface while exporting saltier water below. Notable exceptions within it are the Adriatic Sea and the Black Sea, which function as dilution basins due to significant freshwater input from major rivers—the Po for the Adriatic, and the Danube, Dnieper, and Don for the Black Sea. In these dilution basins, fresher water flows out at the surface and saltier oceanic water flows in below, and deep-water oxygen renewal may be insufficient. The Mediterranean Sea includes a vast array of marginal seas: the Adriatic Sea, Aegean Sea (including the Sea of Crete and the Thracian Sea), Alboran Sea, Balearic Sea, Sardinian Sea, Black Sea, Ionian Sea, Ligurian Sea, Sea of Azov, Sea of Marmara, and Tyrrhenian Sea.

Did You Know?

• The Mediterranean Sea is the eponymous example of a 'mediterranean sea,' a mostly enclosed sea with limited water exchange with outer oceans.
• As a concentration basin, the Mediterranean Sea has higher salinity than the outer ocean due to evaporation.
• The Adriatic Sea and the Black Sea are dilution basins within the Mediterranean, fed by the Po River and the Danube, Dnieper, and Don rivers respectively.
• In dilution basins like the Black Sea, renewal of deep water may not be sufficient to supply oxygen to the bottom.
• The Mediterranean Sea includes the Adriatic Sea, Aegean Sea, Alboran Sea, Balearic Sea, Sardinian Sea, Black Sea, Ionian Sea, Ligurian Sea, Sea of Azov, Sea of Marmara, and Tyrrhenian Sea.