Seasonal dynamics and characterizationof coccolithophore export productionin two major upwelling regions:Cape Blanc (NW-Africa)&Chile (30 degrees S)

Abstract

Sediment trap samples of the Cape Blanc (1988-1991) and of the Chilean upwelling region (30 degrees S) was studied to characterize the coccolith flux and the coccolith-CaCO3. flux. The taxonomical study showed a complex and diverse community. Off Cape Blanc the coccolith flux had a distinct seasonal cycle with maximum in winter/fall, but strong interannual variability. The maximum coccolith flux was related to environmental parameters. Change in species assemblage occurred (increase of Ophiaster and Acanthoica). Underlying surface sediment had similar coccolith flux. The plankton community showed maximum fluxes of phytoplankton in winter and of foraminifera in spring.Off Chile the assemblage was as diverse with a strong seasonality which was absent during El Nino. Maximum fluxes of diatoms were followed by flux of silicoflagellates, coccolithophores and foraminifers. It corresponded to nutrient availability. During El Nià �à ±o water properties changed, as the flux pattern of the plankton.