Rosie Sheward

Goethe-Universität Frankfurt am Main · Institute for Geoscience

Coccolithophores are an abundant phytoplankton group that exhibit remarkable diversity in their biology, ecology and calcitic exoskeletons (coccospheres). Their extensive fossil record is a testament to their important biogeochemical role and is a valuable archive of biotic responses to environmental change stretching back over 200 million years. H...

The majority of fossil coccolithophore studies are based on disaggregated coccoliths but preserved complete coccospheres provide documentation of true cellular traits (cell size, numbers of coccoliths per cell and calcite quotas) and represent a relatively untapped archive of palaeobiological information. Coccospheres are more frequently present wh...

Coccolithophores, a diverse group of phytoplankton, make important contributions to pelagic calcite production and export, yet the comparative biogeochemical role of species other than the ubiquitous Emiliania huxleyi is poorly understood. The contribution of different coccolithophore species to total calcite production is controlled by inter-speci...

Coccolithophores are a key phytoplankton group that exhibit remarkable diversity in their biology, ecology, and in the highly distinctive morphological architecture of their calcite exoskeletons (coccospheres). Their extensive fossil record is testament to the crucial role that they play in the biogeochemical cycling of carbon through the productio...

The marine coccolithophore species Emiliania huxleyi tolerates a broad range of salinity conditions over its near-global distribution, including the relatively stable physiochemical conditions of open ocean environments and nearshore environments with dynamic and extreme short-term salinity fluctuations. Previous studies show that salinity impacts...

The elemental composition of marine microorganisms (their C:N:P ratio, or stoichiometry) is central to understanding the biotic and biogeochemical processes underlying key marine ecosystem functions. Phytoplankton C:N:P is species specific and flexible to changing environmental conditions. However, bulk or fixed phytoplankton stoichiometry is usual...

Cellular modelling and geochemical analyses reveal that a dominant group of phytoplankton changed their carbonate production as atmospheric CO2 levels declined from peak levels in the warm early Eocene, hinting at a positive feedback in the global carbon cycle.

The future physiology of marine phytoplankton will be impacted by a range of changes in global ocean conditions, including salinity regimes that vary spatially and on a range of short- to geological timescales. Coccolithophores have global ecological and biogeochemical significance as the most important calcifying marine phytoplankton group. Previo...

Stressful environmental conditions can induce many different acclimation mechanisms in marine phytoplankton, resulting in a range of changes in their photophysiology. Here we characterize the common photophysiological stress response of the model diatom Thalassiosira pseudonana to ten environmental stressors and identify diagnostic responses to par...

International Ocean Discovery Program (IODP) Expedition 378 was designed to recover the first comprehensive set of Paleogene sedimentary sections from a transect of sites strategically positioned in the South Pacific to reconstruct key changes in oceanic and atmospheric circulation. These sites would have provided an unparalleled opportunity to add...

Organic carbon burial is an important driver of carbon cycle and climate dynamics on geological and shorter time scales. Ocean basins emerging during the Early Cretaceous break-up of Gondwana were primary sites of organic carbon burial, implying that their tectonic and oceanographic evolution may have affected trends and perturbations in global cli...

The Chicxulub bolide impact 66 million years ago drove the near-instantaneous collapse of ocean ecosystems. The devastating loss of diversity at the base of ocean food webs probably triggered cascading extinctions across all trophic levels1–3 and caused severe disruption of the biogeochemical functions of the ocean, and especially disrupted the cyc...

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 inorg...

During the Holocene, North American ice sheet collapse and rapid sea-level rise reconnected the Black Sea with the global ocean. Rapid meltwater releases into the North Atlantic and associated climate change arguably slowed the pace of Neolithisation across southeastern Europe, originally hypothesized as a catastrophic flooding that fueled cultural...

Dataset to accompany Sheward, RM et al. (2017): Physiology regulates the relationship between coccosphere geometry and growth phase in coccolithophores. Biogeosciences, 14(6), 1493-1509, doi:10.5194/bg-14-1493-2017 Measurements of coccosphere geometry - coccolith length, number of coccoliths per cell, cell size and coccosphere size - measured usi...

The progressive loss of Arctic sea ice leads to increased surface emissions of Dimethyl Sulphide (DMS), which is the dominant local source of sulphate aerosols. We test the hypothesis that cloud condensation nuclei, derived from DMS, will increase cloud-top albedo in an earth-system global climate model. The earth-system model includes fully intera...

Coccolithophores are an abundant phytoplankton group that exhibit remarkable diversity in their biology, ecology, and calcitic exoskeletons (coccospheres). Their extensive fossil record is testament to their important biogeochemical role and is a valuable archive of biotic responses to environmental change stretching back over 200 million years. Ho...

Coccolithophores are a diverse and biogeochemically important group of phytoplankton in terms of the production and export of calcite, yet the comparative physiology and ecology of species other than the ubiquitous Emiliania huxleyi is poorly understood. Despite assumptions that Emiliania huxleyi is a fast growing species, we found it had comparabl...

Coccolithophores, a diverse group of phytoplankton, make important contributions to pelagic calcite production and export, yet the comparative biogeochemical role of species other than the ubiquitous Emiliania huxleyi is poorly understood. Here we examined the relative importance of E. huxleyi and two Coccolithus species (Coccolithus pelagicus and...