Dinoflagellate cysts in surface sediments

Surface sediments at 439 sites throughout the North Atlantic Ocean and adjacent seas have been analyzed for dinoflagellate cysts in order to establish a reference database from which paleoenvironmental transfer functions can be developed. Laboratory procedures and systematics were standardized in order to avoid bias introduced by the selective loss of taxa and to facilitate site to site comparison. 371 sites were retained to develop the database that includes 41 taxa, some of which were grouped using morphological and/or ecological criteria. 27 taxa were retained for statistical purposes. Distribution maps of these latter taxa have been plotted on the basis of their relative abundance. Principal component analyses were performed in order to describe the distribution of assemblages. The relation between the assemblages, as well as the relative abundance of individual taxa, and selected sea-surface parameters are illustrated. The parameters which were considered include temperature and salinity for winter (February) and summer (August) together with the duration of sea-ice cover. Transfer functions using the best analogue method have been tested with a view to reconstruct past sea-surface parameters. Validation procedures on this transfer function demonstrate that more than 95% of the reconstructions are included within the interannual variability of modern sea-surface conditions. Therefore, these transfer functions give accurate results and can be applied to reconstructing paleo-temperatures and -salinities from analogous assemblages in Quaternary sedimentary sequences. Protoperidinium stellatum (Wall in Wall & Dale, 1968) Head, comb. nov. (basionym = Peridinium stellatum) is proposed as new, and Algidasphaeridium? minutum var. cezare de Vernal et al., 1989 ex de Vernal et al. is newly validated.