Oceanography of Marginal Seas

The Indian Ocean assumes great importance in mediating the global thermohaline circulation. The north Atlantic deep waters that ultimately ventilate in the north Pacific not only pass through but also occupy a large depth range in the Indian Ocean. Intermediate flow patterns in the Indian Ocean are immensely influenced by high-density waters pouring into the Arabian Sea from the marginal seas, the Persian Gulf and the Red Sea. Their positioning is much in common among the marginal seas including the Andaman Sea above or close to the ridge systems. While these systems in the Red Sea and in the Andaman region are seismically active, the one in the Persian Gulf is not. This leads to greater variations in the ecology of these marginal bodies. Climatic difference leads to greater evaporation in the northwestern parts of the Indian Ocean, while the northeastern parts experience intense rainfall. Therefore, the Persian Gulf, the Red Sea and the Arabian Sea are negative water bodies, while the Bay of Bengal is a positive one. The above differences among the marginal seas in question make these areas interesting with their distinct oceanographic aspects. This chapter deals with the salient characteristics of the marginal seas: the Persian Gulf, the Red Sea and the Andaman Sea ( Fig. 1 ).