<p><strong>Abstract.</strong> Living coccolithophore assemblages were investigated in 35 surface water samples taken from the Natal Valley (southwest Indian Ocean) in January and November, 1983 and February, 1984. Fifty-nine species were recognised using a scanning electron microscope (S.E.M.). Cluster analysis revealed four different species assemblages dominated by <i>Emiliania huxleyi, Umbilicosphaera hulburtiana, Umbellosphaera tenuis</i> and <i>Gephyrocapsa oceanica.</i> Significant

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... nces in species composition between the sampling periods are attributed to seasonal fluctuations. The regional distribution of the assemblages reflects two different océanographic regimes: 1) The Agulhas Current, which is a nearly stable feature and 2) the area of the Agulhas Return Current, characterised by rapidly changing hydrographic and ecological conditions.</p>