CORAL STUDY IN THE SOUTHERN OCEAN — SQUIRES 



451 



gence. Two zones of water within the Southern Ocean are defined by 

 these (the Subtropical Convergence being used here as the northern 

 boundary of the Southern Ocean) . Both zones are relatively shallow, 

 for the ocean is layered vertically as well as horizontally. Innermost 

 of these water masses is the Antarctic Surface water which surrounds 

 the Antarctic in a sinuous fashion. This is the area of floating ice 

 or pack ice, and is completely dominated by the East Wind Drift. 

 The waters are cold, being below or only slightly above the freezing 

 point all year round. The water is less saline in the summer because 

 the melting ice adds fresh water, but becomes more saline in the winter 

 as ice is frozen. Across the Antarctic Convergence, which has a tem- 



FiGURE 2. — Map of the Q)ntinental Shelves, Southern Ocean. (After N. A. MacKintosh, 

 1960, Proc.'Roy. Soc, Ser. B, vol. 152.) 



