DIEL VERTICAL MIGRATION OF ZOOPLANKTON IN THE UPWELLING AREA OF THE WEST-COAST OF SOUTH-AFRICA

On the basis of the net plankton samples collected vertically by layer s during 24 h cycle on a fixed station in the northern part of the Ben guela upwelling system, the diel dynamics of the vertical distribution and abundance of different species and groups of zooplankton were stu died. Practically non-migratory species (epipelagic small copepods Par acalanus, Clausocalanus, Oithona and Oncaea, also Centropages brachiat us and a chaetognath Eukrohnia hamata), weakly migrating in surface la yers (Nannocalanus minor, Sagitta spp.) and extensively migrating betw een the surface and deep waters (rather large copepods Pleuromamma gra cilis, P. borealis, Metridia lucens, Calanoides carinatus) were reveal ed. The diel dynamics of total zooplankton is discussed as a result of migratory behavior of these groups.