PALEOCEANOGRAPHY, BIOLOGICAL PROXIES | Dinoflagellates

Dinoflagellates occur in most aquatic environments and constitute an important part of primary productivity. During their life cycle, some dinoflagellates produce organic-walled cysts (or dinocysts) that fossilize in sediment and are prepared for microscopic observation following palynological procedures. The dinoflagellates producing fossilizable cysts include autotrophic and heterotrophic species that belong either to the phytoplankton or to the microzooplankton. The study of dinocysts on the sea floor has revealed relatively diverse assemblages from the equator to polar environments, with particularly high fluxes in marine environments of the continental margins. The geographical distribution of dinocyst assemblages suggests relationships with sea-surface temperature, salinity, sea-ice cover, and productivity. Qualitative and quantitative approaches permit the reconstruction of past sea-surface conditions.