Large Scale Physical Variability of the Benguela Current Large Marine Ecosystem

The Benguela Current Large Marine Ecosystem (BCLME) is situated off the west coast of Africa between 5-37oS, 0-26oE, and spans the three countries of Angola, Namibia and South Africa. It is one of the four major eastern boundary current upwelling systems of the world oceans (Hill et al. 1998), and although it has some similar characteristics to the other eastern boundary upwelling areas, a unique feature is that it is bounded on both the equatorial and poleward extremities by warm water current systems (the tropical warm Angola Current system in the north, and the Indian Ocean western boundary Agulhas Current System in the south; Shannon and Nelson, 1996; Shillington 1998; Shannon and O’Toole 2003). In the region between about 1537oS, the surface currents are generally equatorward, with vigorous coastal upwelling cells, strong and narrow equatorward shelf edge jets (near Cape Town which is situated at 34oS, 18oE and off Lüderitz; 28oS, 15oE), and a poleward undercurrent along the shelf slope and bottom. The warm tropical Angola Current System (Ajao and Houghton 1998) generally has southward moving coastal currents which meet the Benguela Upwelling System at the Angola-Benguela Frontal Zone (ABFZ) at ~1517oS (Shannon et al. 1987; Field and Shillington 2005; Monteiro and van der Plas, this volume; Veitch et al. 2006).