Drifting Buoys in the Benguela Current Region, 1999 - 2002

The aim of this study is to describe and
quantify surface circulation in the Benguela ecosystem in relation to:
1) the transport and retention of, not only pelagic egg and larvae,
but also to that of its food supply, and 2) transport towards and
convergence on the Angola-Benguela front.

Specific objectives are
1. to identify locations of preferred onshore or offshore transport;
2. to identify areas of limited exchange;
3. to make transport data available for other environmental and resource
studies;
4. follow pathways of nutrient rich waters from its source (upwelling cell)
5. follow the movement of southward moving Tropical Atlantic water
6. describe the circulation to and in pelagic spawning areas
7. to provide training and collaboration opportunities in lagrangian methods

The surface circulation of the Benguela system is a critical component
of the fisheries environment, transporting both planktonic egg and
larvae and planktonic food for fish. Much needed in fisheries and
environmental management in the Benguela are (i) direct observations
of the surface circulation, (ii) understanding of the processes
controlling surface circulation, and (iii) quantification of the
dispersion of plankton transported by the surface circulation.

The proposed work will follow up on initial deployment of drifters
during the 1999 BENEFIT training cruise and the subsequent deployment
of drifters in Namibia and South Africa during 2001. The deployment
of more drifters will provide additional data, making it possible to
resolve seasonal differences in transport patterns. The analyses of
new data combined with that collected over the past three years and
historical data will provide parameter values and insight directly
relevant to understanding and managing fisheries in the Benguela
system. These analyses will shed new light on the nature of the
Benguela system as well as confirm a number of ideas which remain
poorly supported by existing data. Further, to appreciate how climate
change may alter the habitat or dispersion patterns of key species in
the Benguela, one has to obtain data and develop an understanding of
the present habitat and dispersion characteristics.

Drifter studies are a key component of fishery oceanography. In spite
of the technique being appropriate for southern Africa, it is little
used here. There is a need for training. This study presents a
unique opportunity for the involvement and education of both PhD- and
MSc-level physical oceanographers in all three BENEFIT countries. In
addition to formal training, this project provides many opportunities
for international collaboration in fieldwork and analysis.