Coccolithophores: a major phytoplankton component in mature upwelled waters off the Cape Peninsula,South Africa in March, 1983

Coccolithophores, together with other phytoplankton, were sampled at ten stations along a transect following the general orientation of the Cape Peninsula upwelling plume in March, 1983. Thirteen coccolithophore species were identified with Emiliania huxleyi dominating the assemblages. Coccolithophores and other microflagellates were more abundant than diatoms along the transect except at one station in mature upwelled water. Very high populations (2 340×10³ cells l^-1) of coccolithophores were found in mature upwelled water adjacent to the oceanic front. This count is one of the highest counts ever recorded in an upwelling area. The anomalous warm event prior to sampling may have had a residual effect on seeding, contributing towards the predominance of small-celled phytoplankton over chain-forming diatoms.