THE WESTERN AGULHAS BANK - CIRCULATION, STRATIFICATION AND ECOLOGY
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Studies of the physical oceanography of the western Agulhas Bank are reviewed, pointing out the unique position of this shelf region between the eastern boundary Benguela system and the western boundary Agulhas system. New observations from moorings off Quoin Point during summer 1986/87 permit a fuller description of the dynamics of circulation and stratification and the identification of three subregions. The inner shelf is dominated by wind-forcing, as in eastern boundary upwelling systems, whereas the outer shelf is dominated by oceanic forcing, as over western boundary shelves. The mid-shelf is characterized by strong stratification separating near-surface oceanic water from near-bottom upwelling Central Water. A lack of correlation between currents and temperatures in these three subregions of the western Agulhas Bank suggests that they function independently. This synthesis of the physical oceanography, which includes discussion of the hydrodynamic coupling of the western Agulhas Bank with shelf regions to the east and west, leads to a discussion of the importance of circulation and stratification to the anchovy-related ecology of the region. This centres on the availability of food and transport for spawning anchovy Engraulis capensis on the western Agulhas Bank. 1992 Taylor & Francis Group, LLC.