Organic-walled dinoflagellate cysts: Palynological tracers of sea-surface conditions in middle to high latitude marine environments

A reference data base of dinoflagellate cyst assemblages was developed from the palynological analyses of surface sediment samples collected at similar to 450 sites from middle to high latitudes of the North Atlantic and adjacent basins. The data set is representative of a wide range of sea-surface conditions with respect to sea-ice cover (0-12 months/year), temperature (up to 25 degrees C), salinity (20-36 psu), and seasonality. The analyses reveal relatively high dinoflagellate cyst concentrations especially along the continental margins (up to 10(5) cysts/cm(3)). The distribution of species and assemblages show close relationships with the salinity, the temperature of the warmest and coldest months, and the seasonal duration of the sea-ice cover. On these grounds, transfer functions using the best analogue method were developed in order to reconstruct the following sea-surface parameters with a reasonable degree of accuracy, i.e. within the range of interannual variations: temperature in February (+/-1.2 degrees C) and August (+/-16 degrees C), salinity (+/-0.7 psu) and sea-ice cover extent (+/-1.1 months/year). The transfer functions based on dinoflagellate cysts are original and yield paleoceanographic and paleoclimatic data complementary to those produced currently on the basis of transfer function using planktonic foraminifera.