CEREGE, CNRS-Université Aix-Marseille, Europôle Méditerranéen de l'Arbois, BP80, 13545 Aix en Provence, FrancePalaeontology Department, The Natural History Museum, Cromwell Road, London, SW7 5BD, UK.
Published: August 2009
AI Article Synopsis
Article Abstract
A new combination coccosphere of the heterococcolithophore Helicosphaera wallichii (Lohman 1902) Okada and McIntyre 1977 and holococcolithophore Syracolithus ponticuliferus (Kamptner 1941) Kleijne and Jordan 1990 is documented. This combination coccosphere was observed within a rich and diverse assemblage collected during late summer at a 20 m water depth from the NW Mediterranean Sea.
Coccolithophores play an important role in global biogeochemical cycling, but many aspects of their ecology remain poorly understood, including their heteromorphic haplo-diplontic life cycle. The presence of combination coccospheres in environmental samples, which represent a transition between the lightly calcified haploid (HOL) and heavily calcified diploid (HET) life phases, provides crucial evidence linking the two life cycle phases of a particular species. Here, we describe combination coccospheres from the Southern Ocean that show a novel association between (HET) and HOL type.
Size is a fundamental cellular trait that is important in determining phytoplankton physiological and ecological processes. Fossil coccospheres, the external calcite structure produced by the excretion of interlocking plates by the phytoplankton coccolithophores, can provide a rare window into cell size in the past. Coccospheres are delicate however and are therefore poorly preserved in sediment.
Past global warming events such as the Palaeocene-Eocene Thermal Maximum (PETM-56 Ma) are attributed to the release of vast amounts of carbon into the ocean, atmosphere and biosphere with recovery ascribed to a combination of silicate weathering and organic carbon burial. The phytoplanktonic nannoplankton are major contributors of organic and inorganic carbon but their role in this recovery process remains poorly understood and complicated by their contribution to marine calcification. Biocalcification is implicated not only in long-term carbon burial but also both short-term positive and negative climatic feedbacks associated with seawater buffering and responses to ocean acidification.
The species concept in marine phytoplankton is defined based on genomic, morphological, and functional properties. Reports of intraspecific diversity are widespread across major phytoplankton groups but the impacts of this variation on ecological and biogeochemical processes are often overlooked. Intraspecific diversity is well known within coccolithophores, which play an important role in the marine carbon cycle via production of particulate inorganic carbon.
National Oceanography Centre Southampton, School of Ocean and Earth Science, University of Southampton Southampton, UK ; Department of Biology, Woods Hole Oceanographic Institution Woods Hole, MA, USA.
Growth and calcification of the marine coccolithophorid Emiliania huxleyi is affected by ocean acidification and macronutrients limitation and its response varies between strains. Here we investigated the physiological performance of a highly calcified E. huxleyi strain, NZEH, in a multiparametric experiment.
