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Currents on the South African shelf have been measured on 13 cruises since an Acoustic Doppler Current Profiler (ADCP) was installed on F.R.S. Africana in ]989. Most previous descriptions of the West Coast (Benguela) system, including the baroclinic jet currents off the Cape Peninsula and Cape Columbine, the ]aller clearly diverging into a dominant offshore arm and a weaker inshore arm, have been confirmed. This baroclinic flow originates along the south-western margin of the Agulhas Bank. Measurements of the inshore features of the Agulhas Current have shown strong WSW -SSW flow aligned with the bathymetry, but with significant she]fedge north-eastward return flows. The velocity differences between the surface and depth reveal barotropic dominance in all inshore areas and over the central Agulhas Bank. The West Coast outer shelf displays variable baroclinic effects, reflecting the importance of frontal features and cross-shelf flow. SSW flow on the outer eastern Agulhas Bank appears responsible for an offshore loss of eggs from this region. The funnelling of anchovy eggs from the western Agulhas Bank to the West Coast was clear, but this "funnel" was found to have holes through which substantial loss of eggs offshore is also probable. The currents on the Agulhas Bank and the West Coast are discussed with regard to the life histories of various commercially fished species, in addition to anchovy. The study concludes that hypotheses relating environmental factors and recruitment need to consider the variety of potential options in terms of life history contained within the prevailing current system. Seder! 'n Doppler-Akoestiese Stroomprofileerder in 1989 op VNS. Africana aangebring is, is strome tydens 13 vaarte op die Suid-Afrikaanse vastelandsplat gemeel. Die meeste vorige beskrywings van die Weskus (Benguela)stelsel is bevestig, met inbegrip van die barokliniese snelstrome teenoor die Kaapse Skiereiland en Kaap Columbine en laasgenoemde se ooglopende vertakking in 'n oorheersende aflandige been en 'n swakker aanlandige been. Hierdie barokliniese vloei het sy oorsprong langs die suidwestelike grens van die Agulhasbank. Metings van die aanlandige kenmerke van die Agulhasstroom het sterk WSW tot SSW vloei vertoon in ooreenstemming met die batimetrie, maar met beduidende noordoostelike terugkeervloei aan die rand van die vastelandsplal. Verskille in vloeisnelheid tussen die oppervlak en dieper water dui op barotropiese oorheersing in aile aanlandige gebiede en oor die sentrale Agulhasbank. Die afIandige streek van die plat aan die Weskus word gekenmerk deur wisselvallige barokliniese gevolge wat die belang van frontale kenmerke en dwarsvloei oor die plat beklemtoon. SSW vloei op die buitenste oostelike Agulhasbank is blykbaar verantwoordelik vir seewaartse verlies van eiers uit hierdie streek. Daar is onteenseglik 'n tregtereffek op beweging van ansjoviseiers van die weste]ike Bank na die Weskus, maar die "tregter" het openinge waardeur ook aansienlike seewaartse eierverlies waarskynlik is. Vermelde strome op die A...

Changes that occurred in sea surface and some deeper temperatures, surface winds, currents, plankton and some dominant crustacean (rock lobster Jasus lalandii), molluscan (squid Loligo vulgaris reynaudii and abalone Haliotis midae), fish (anchovy Engraulis capensis, pilchard Sardinops oce/latus, Cape hakes Merluccius spp., sole Austroglossus pectoralis, kingklip Genypterus capensis and various species of linefish) and seabird (Cape gannet Morus capensis) resources in the Benguela ecosystem in the 1980s are documented. Although fishing had a clear influence on changes in some of the resources, a wide spectrum of organisms, from plankton to top predators, were influenced directly or indirectly by the abiotic environment. Concurrent changes in many of the resources suggest that the same environmental change may impact on more than one. Simultaneous change throughout the Benguela system indicates that environmental forcing sometimes takes place over wide geographic areas. At the northern and southern extremities of the Benguela system, responses to environmental change may be different because processes through which the change is mediated are different.Verandering wat plaasgevind het in die see-oppervlak-en sommige dieper temperature, oppervlakwinde, strome, plankton en sommige hulpbronne soos skaaldiere (kreef Jasus lalandii), weekdiere (tjokka Loligo vulgaris reynaudii en perlemoen Ha/iotis midae), vis (ansjovis Engraulis capensis, sardyn Sardinops oce/latus, Kaapse stokvis Merluccius spp., tongvis Austroglossus pectoralis, koningklip Genypterus capensis en verskeie lynvisspesies) en seevoels (witmalgas Morus capensis) in die Benguela-ekostelsel in die 1980s word gedokumenteer. Ofskoon die vissery 'n duidelike invloed op veranderinge in somrnige van die hulpbronne gehad het, is 'n wye spektrum organismes, van plankton tot spitsroofdiere, regstreeks of onregstreeks be"invloed deur die nie-Iewende omgewing. Gelyktydige veranderinge in baie van die hulpbronne dui daarop dat dieselfde omgewingsverandering op meer as een van hlllle 'n uitwerking mag he. Gelyktydige verandering dwarsdeur die Benguelastelsel laat dink dat omgewingsforsering soms oor wye geografiese gebiede plaasvind. By die noorder-en suider-uiteindes van die Bengllelastelsel kan die reaksies op omgewingsverandering verskil omdat die prosesse waardeur die verandering teweeggebring word, verskil. 1992 4 J 2 J

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