A preliminary study of the oxygen and phosphate distribution in the Mediterranean Sea

Observations in the eastern Mediterranean basin confirm Pollak's suggestion (1951) that the deep water there originates in the southern Adriatic Sea by the mixing of water masses under the influence of the prevailing winter wind. This water then sinks and flows along the bottom into the eastern Mediterranean, moving counter-clockwise. Such a flow is confirmed by the distribution of oxygen in the deep water of the entire eastern Mediterranean Sea. In the western Mediterranean a deep water mass is produced at the northern end of the Algiers-Provençal basin in winter and shows a similar spread toward the south. Oxygen and phosphate concentrations indicate a low level of biological productivity throughout the year except for localized inshore regions and in the enclosed bays. The concentration of nutrients in the western basin is about twice that of the eastern basin but it is still below the concentration of the neighbouring Atlantic.