Title:

Distribution and malformation of living coccolithophores in the northern Benguela upwelling system off Namibia

Publication Year:
1993
Abstract:

The water-column distribution of coccolithophores in the northern Benguela upwelling regime is investigated in a transect of five hydrographic and phytoplankton stations off Walvis Bay, Namibia. Hydrographic conditions indicate that upwelling was not in progress during the sampling period. Coccolithophore standing crops range from 0 to466×103cells/l , the maximum cell density occurring in the shallow-water stations. Dissipation of turbulence and stratification of the system favour the dominance of coccolithophores over diatom and dinoflagellate communities which are normally associated with early stages of the upwelling cycles. Twelve species are identified withEmiliania huxleyi dominating in the nutrient depleted surface layers supporting a high cell density. LivingCoccolithus pelagicus are reported, for the first time, in waters of the southern hemisphere. Vertical changes in species dominance are related to differences in nutrient preferences betweenE. huxleyi andGephyrocapsa oceanica. Deep layers of the three offshore-most stations support a peculiar community which shows a high degree of skeletal deformation. The presence of these malformed coccolithophores, the first ever reported in South Atlantic surface waters, is not related to in-situ nutrient deficiency, or temperature anomalies. This malformed community could have been transported into the study area within a southward-moving, subsurface tongue of moderately saline tropical waters.

Publication Title:

Marine Micropaleontology

Volume:
22
Issue:
1-2
Pages:
93-110
Item Type:
Journal Article
Language:
en