The significance of extant coccolithophores as indicators of ocean water masses, surface water temperature, and palaeoproductivity: a review

Coccolithophores are one of the main groups of marine phytoplankton playing key roles in the marine eco-system as primary producers and in marine biogeochemistry. These organisms have gained considerable attention as they play a unique role in the global carbon cycle because of their combined effects on both the organic carbon and the carbonate pump. In addition to steady advances in research on coccoliths as biogeochemical agents and palaeontological proxies were obtained knowledge of the biology of these organisms has progressed considerably in recent years. It is now clear that holococcolithophores are not autonomous but stages in the life cycle of heterococcolithophores. A general introduction to the taxonomy and biology of extant coccolithophores is followed by a brief overview of the environmental parameters affecting these phytoplanktonic organisms and their biogeography. Another chapter summarizes the investigations on coccolithophores in the Arabian Sea which were conducted during the past years to produce a synthesis of the production of living coccolithophores in the photic zone, their transformation to settling assemblages, their accumulation on the seafloor, and their final burial in the Sediments. In the following, applications of coccolithophores to palaeoenvironmental analyses are provided as case studies. In particular, the usage of both ecologically restricted species, such asFlorisphaera profunda, for palaeoproductivity studies and of a new coccolithophore-based palaeother-mometry for surface-water reconstructions are presented. In addition, haptophyte-specific biomarkers (long-chain alkenones) are reviewed and their applicability for palaeoceanographical reconstructions is demonstrated.