Comparaison de la distribution et du bilan d'echanges des sels nutritifs en Mediterranee et en Mer Rouge

The Mediterranean and the Red Sea are two concentration basins with very similar hydrological characteristics. The water of the adjoining ocean, entering over a sill, holds the water and the nutrient budgets of the basins in balance. Changes in this inflowing oceanic water are analogous in the two basins: reduction in nutrient content, due to mixing with the nutrient-poor water of the basin, biological activity and the existence of successive sills (in the Mediterranean). The Mediterranean receives from the Atlantic Ocean the main part of its nutrient supply (of the order of 70%, the rest being provided by the rivers). This supply is practically constant over the year. The inflowing water from the Indian Ocean provides the entire nutrient supply of the Red Sea. This oceanic supply follows the two circulation regimes at Bab-el-Mandeb straits, the gain in summer (over 3-4 months) compensating the loss in winter (over 8-9 months).