Abstract:   In this study, biomarkers, including brassicasterol, dinosterol and alkenone, in sediments were used as indicators to rebuild the changes in the phytoplankton community in the upper water columns of Prydz Bay, Antarctica. Records of biomarkers in surface and core sediment samples showed obvious changes at spatial and temporal scales. The biomass of phytoplankton determined from biomarkers ranged from 391.0 to 1470.6ng/g. The ocean primary productivity has increased in Prydz Bay over the past 100 years and this increase was closely related to the changing climate in this area. The total content of biomarkers in surface sediments from Prydz Bay and its adjacent area ranged from 215.8 to 1294.3ng/g. The rebuilt biomass of phytoplankton in Prydz Bay was higher than that outside the bay, which agreed with the distributions of chlorophyll a (Chl a), organic carbon and biogenic silica measured in surface waters using in situ observations. This consistency supports the use of biomarkers in sediment to reflect biogeochemical processes in the upper seawater.

Key words: Prydz Bay, Antarctic, sediment, biomarker, primary productivity, phytoplankton