Coccolithophores in the Nordic Seas: comparison of living communities withsurface sediment assemblages

Coccolithophores were investigated in both numerous plankton samples and su rface sediments from across the entire Nordic Seas. Cell numbers of living coccolithophore communities are consistently higher during the high-product ion period (summer) than during the low-production period (fall-early summe r). Particularly high cell numbers are found far to the west during the hig h-production period. High cell densities in general are mainly caused by Em iliania huxleyi, which often dominates the communities in the eastern Norwe gian Sea. In contrast, during the low-production period, many of the collec ted samples contain no coccolithophores. The original composition of the li ving communities is obscured in the surface sediment assemblages. Samples f rom surface sediments contain significantly fewer coccolithophore species t han the living communities of the same area. The most frequently occurring species are Emiliania huxleyi and Coccolithus pelagicus. In addition, Calci discus leptoporus and Gephyrocapsa muellerae are regularly found in small a mounts. This is remarkable since these species are rarely found in living c ommunities. Based on the diversity and concentration of the preserved speci es and on the ratio change between E, huxleyi and C. pelagicus, distinct su rface water masses in this area are clearly reflected. (C) 2000 Elsevier Sc ience Ltd. All rights reserved.