We present a new version of the standardized Northern Hemisphere “modern” dinoflagellate cyst (“dinocyst”) database, which includes abundances of 71 taxa at 1968 sites across the Northern Hemisphere, cross-referenced with 17 environmental parameters extracted mostly from the 2013 World Ocean Atlas. Several taxa with tropical to warm temperate affinities were added to the previous database version. Dinocyst concentrations in the surface sediments reach 106 cysts g−1, with maximum values along the continental margins and minimum values offshore in distal open ocean settings. Assemblages are characterized by the co-occurrence of phototrophic (n = 41) and heterotrophic taxa (n = 30), with maximum proportions of heterotrophic taxa in high productivity regions, notably at the sea-ice edge and in upwelling regions. The main pattern of assemblage distributions includes north–south and nearshore–offshore gradients, with maximum diversity of species along the continental margins and towards the south, in warm temperate and tropical areas. Canonical correspondence analyses performed on heterotrophic and phototrophic taxa independently yield consistent results, hence suggesting similar, but not identical, ecological affinities for both taxonomic groups. For both groups, sea-surface temperature and sea-ice are the most determining parameters, but the phototrophic taxa seem more sensitive to onshore–offshore gradients marked by salinity changes. Productivity-related parameters also determine dinocyst distribution, especially primary productivity in the fall and winter, with a stronger relationship for the combined dataset of phototrophic and heterotrophic taxa.
Bibliographical noteFunding Information:
This study is the result of a long-term endeavor led by AdV, which was supported by the Natural Sciences and Engineering Research Council (NSERC) of Canada and the Fonds de recherche du Québec – Nature et Technologie (FRQNT) . SDS is funded by Research Council of Norway project 268062 ( aDNAPROX ). Samples in the Greenland Sea were collected by participants of the Ice2Ice project, funded from the European Research Council under the European Community's Seventh Framework Program ( FP7/2007-2013 ) / ERC grant agreement 610055. This work was also supported in part by the Zuckerman STEM Leadership Program through a postdoctoral fellowship to AP. We are extremely grateful to all colleagues who helped us to access surface sediment samples and to all students and research personnel who contributed to sample preparation and/or analyses at the microscope.We also thank the anonymous reviewers and the editor of the Journal for their helpful comments and suggestions.