Classification of Adjacent Seas by their Opening Width and Interpretation of their Nomenclature Origins

Abstract

The global marine environment has been traditionally classified into three oceans and 19 adjacent seas, the latter being further classified into large and small mediterranean seas and marginal seas (Kossinna, 1921). Since this nomenclature applied to subdivisions of adjacent seas is unsystematic, it is not adopted in this paper. An adjacent sea is demarcated from oceans or other adjacent seas by the land of continents, archipelagos, islands or peninsulas. The degree of demarcation, i.e. the opening or enclosed degree, changes from the perfect opening such as the Sargasso Sea to the perfect enclosing such as the Caspian Sea, but they are not really adjacent seas. As the opening degree decreases, free exchange of water through channels connecting an adjacent sea with oceans or other adjacent seas is impeded, when the water motion is kept constant. Consequently, the opening or enclosed degree brings important influences upon water pollution and drift and migration of marine organisms, but it has been qualitatively and unsystematically classified so far, in terms of categories such as large and small mediterranean seas and marginal seas. In this paper, the degree of opening is expressed by using the two quantities A and W, where A is the area of an adjacent sea, W = ΣW_i is the total opening width of channels for each of adjacent seas, W_i is the shortest width of each channel, and i is a serial number of each channel (Fig. 1). Since the intermediate value of W is at about1,000 km (Fig. 2), we regard adjacent seas with W longer than 1,000 km as the open type. Unless the original names of adjacent seas of the open type are accepted for a considerable reason, their names should bear the name of the continent or the nation located in the hinterland of the adjacent sea. Since the central value of W is at about 200 km, and since adjacent seas with W shorter than 200 km are highly enclosed, we regard adjacent seas with W shorter than 200 km as the enclosed type and adjacent seas with W longer than 200 km as the semi-enclosed type. Unless the original names of adjacent seas of the enclosed or semi-enclosed type are accepted for a considerable reason, their names should indicate the archipelago or the nation located int he oceanic frontier of the adjacent sea. However, we do not know whether the name "Gulf of California" is for the state located in the hinterland or for the peninsula located in the oceanic frontier (Table 3). Whether the hinter land or the oceanic frontier becomes the origin of the name for an adjacent sea depends upon which exerts greater influence upon mariners or people living along the coastal area of the adjacent sea. Introducing these three types of opening degree (open, semi-enclosed or enclosed), and interpreting the naming origins of 20 adjacent seas (Table 3), we have assumed a folk custom that gives the exclusive priority to the names of adjacent seas with accepted reasons.