Dinoflagellate cyst assemblages as tracers of sea-surface conditions in the northern North Atlantic, Arctic and sub-Arctic seas: the new 'n=677' database and its application for quantitative palaeoceanographic reconstruction

The distribution of dinoflagellate cyst (dinocyst) assemblages in surface s ediment samples from 677 sites of the northern North Atlantic, Arctic and s ub-Arctic seas is discussed with emphasis on the relationships with sea-sur face parameters, including sea-ice cover, salinity and temperature of the c oldest and warmest months. Difficulties in developing a circum-Arctic data base include the morphological variation within taxa (e.g. Operculodinium c entrocarpum, Islandinium? cezare and Polykrikos sp.), which probably relate to phenotypic adaptations to cold and/or low salinity environments. Sparse hydrographical data, together with large interannual variations of tempera ture and salinity in surface waters of Arctic seas constitute additional li mitations. Nevertheless, the use of the best-analogue technique with this n ew dinocyst data base including 677 samples permits quantitative reconstruc tion of sea-surface conditions at the scale of the northern North Atlantic and the Arctic domain. The error of prediction calculated from modern assem blages is +/-1.3 degreesC and +/-1.8 degreesC for the temperature of Februa ry and August, respectively, +/-1.8 for the salinity, and +/-1.5 months yr( -1) for the sea-ice cover. Application to late Quaternary sequences from th e western and eastern subpolar North Atlantic (Labrador Sea and Barents Sea ) provide reconstructions compatible with those obtained using the previous dinocyst data base (n = 371), which mainly included modern data from the n orthern North Atlantic. Copyright (C) 2001 John Wiley & Sons, Ltd.