PHYTOPLANKTON BIOMASS AND SEA-SURFACE TEMPERATURE ESTIMATES FROM SEA-BED DISTRIBUTION OF NANNOFOSSILS AND PLANKTONIC-FORAMINIFERA IN THE BENGUELA UPWELLING SYSTEM

The distribution of Recent nannofossils and planktonic foraminifera in 140 surface sediment samples beneath the Benguela system (from 35-degrees-S to 17-degrees-S latitude) are related to mean annual chlorophyll a (0-30m integrated) and sea-surface temperature by factor analysis and regression techniques. Independent Q-mode factor analyses of the floral and faunal census data yield 4 and 3 factors, respectively, explaining in both cases more than 95% of the variance. Their distribution is closely related to the various surface water masses induced by the coastal upwelling process. Multiple regressions show a good correlation between chlorophyll a concentrations and the nannofossil factor loadings, on the one hand, and between sea-surface temperatures and the planktonic foraminiferal factor loadings, on the other. The derived transfer functions reproduce accurately the modern sea-surface conditions of the Benguela system, with standard errors for chlorophyll a and sea-surface temperature estimates of +/-0.93 mg.m-3 and +/-0.43-degrees-C, respectively.