A coccolithophore concept for constraining the Cenozoic carbon cycle

Henderiks, Jorijntje; Rickaby, Rosalind E. M.

doi:10.5194/bg-4-323-2007

Cited by 30 publications

(23 citation statements)

References 45 publications

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“…This order diverged from its last common ancestor with the Isochrysidales after the P/Tr boundary (∼243 Ma; ref. 14), and has prevailed throughout the early Cenozoic, only to be marginalized in present-day oceans15. Gephyrocapsa oceanica (Fig.…”

Section: Resultsmentioning

confidence: 99%

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The uronic acid content of coccolith-associated polysaccharides provides insight into coccolithogenesis and past climate

et al. 2016

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Unicellular phytoplanktonic algae (coccolithophores) are among the most prolific producers of calcium carbonate on the planet, with a production of ∼1026 coccoliths per year. During their lith formation, coccolithophores mainly employ coccolith-associated polysaccharides (CAPs) for the regulation of crystal nucleation and growth. These macromolecules interact with the intracellular calcifying compartment (coccolith vesicle) through the charged carboxyl groups of their uronic acid residues. Here we report the isolation of CAPs from modern day coccolithophores and their prehistoric predecessors and we demonstrate that their uronic acid content (UAC) offers a species-specific signature. We also show that there is a correlation between the UAC of CAPs and the internal saturation state of the coccolith vesicle that, for most geologically abundant species, is inextricably linked to carbon availability. These findings suggest that the UAC of CAPs reports on the adaptation of coccolithogenesis to environmental changes and can be used for the estimation of past CO2 concentrations.

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Section: Resultsmentioning

confidence: 99%

“…Isochrysidales and Coccolithales have distinct geological histories with regard to cell size153435. Estimates based on coccolith morphometrics suggest that the cell size of Coccolithus spp.…”

Section: Resultsmentioning

confidence: 99%

The uronic acid content of coccolith-associated polysaccharides provides insight into coccolithogenesis and past climate

et al. 2016

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“…Therefore, maximum growth rate at a pH of ~7.9 for C . pelagicus can be understood as a “memory” of the environmental conditions that prevailed when this species evolved in the Paleogene [ Henderiks and Rickaby , ]. From the data, it is also apparent that C. pelagicus has much wider pH tolerance in terms of growth rates than G. oceanica .…”

Section: Resultsmentioning

confidence: 99%

Control of ambient pH on growth and stable isotopes in phytoplanktonic calcifying algae

Hermoso

2015

Paleoceanography

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The present work examines the relationship between pH-induced changes in growth and stable isotopic composition of coccolith calcite in two coccolithophore species with a geological perspective. These species (Gephyrocapsa oceanica and Coccolithus pelagicus) with differing physiologies and vital effects possess a growth optimum corresponding to average pH of surface seawater in the geological period during their first known occurrence. The "ancestral" C. pelagicus has much wider pH tolerance in terms of growth rates than the more recently evolved G. oceanica. Diminished growth rates are explained by the challenge of proton translocation into the extracellular environment at low pH and enhanced aqueous CO 2 limitation at high pH. Reducing the cell dynamics in this way leads to a lower degree of oxygen isotopic disequilibrium in G. oceanica. In contrast, the slower growing species C. pelagicus, which typically precipitates near-equilibrium calcite, does not show any modulation of oxygen isotope signals with changing pH. Overall, carbon and oxygen isotope compositions are best explained by the degree of utilization of the internal dissolved inorganic carbon (DIC) pool and the dynamics of isotopic reequilibration inside the cell. Thus, the "carbonate ion effect" may not apply to coccolithophores. This difference with foraminifera can be traced to different modes of DIC incorporation into these two distinct biomineralizing organisms. From a geological perspective, these findings have implications for refining the use of oxygen isotopes to infer more reliable sea surface temperatures (SSTs) from fossil carbonates and contribute to a better understanding of how climate-relevant parameters are recorded in the sedimentary archive.

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“…This novel approach (recently outlined in Hermoso, 2015, andHermoso et al, 2015) will require coupled foraminiferal data that may serve as an inorganic reference (Spero et al, 2003). In addition, it appears possible to reconstruct cell geometry via morphometric measurements made on fossil coccoliths (Henderiks and Rickaby, 2007;Henderiks, 2008;Henderiks and Pagani, 2008), as this parameter is of paramount importance for inferring algal growth dynamics and cell size in the absence of preserved coccospheres in the sedimentary register, except in some peculiar settings (Gibbs et al, 2013).…”

Section: Outlook For Coccolith-based Palaeoceanographic Reconstructionsmentioning

confidence: 99%

Vanishing coccolith vital effects with alleviated carbon limitation

et al. 2016

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Abstract. By recreating a range of geologically relevant concentrations of dissolved inorganic carbon (DIC) in the laboratory, we demonstrate that the magnitude of the vital effects in both carbon and oxygen isotopes of coccolith calcite of multiple species relates to ambient DIC concentration. Under high DIC levels, all the examined coccoliths exhibit significantly reduced isotopic offsets from inorganic calcite compared to the substantial vital effects expressed at low (preindustrial and present-day) DIC concentrations. The supply of carbon to the cell exerts a primary control on biological fractionation in coccolith calcite via the modulation of coccolithophore growth rate, cell size and carbon utilisation by photosynthesis and calcification, altogether accounting for the observed interspecific differences between coccolith species. These laboratory observations support the recent hypothesis from field observations that the appearance of interspecific vital effect in coccolithophores coincides with the long-term Neogene decline of atmospheric CO 2 concentrations and bring further valuable constraints by demonstrating a convergence of all examined species towards inorganic values at high pCO 2 regimes. This study provides palaeoceanographers with a biogeochemical framework that can be utilised to further develop the use of calcareous nannofossils in palaeoceanography to derive sea surface temperature and pCO 2 levels, especially during periods of relatively elevated pCO 2 concentrations, as they prevailed during most of the Meso-Cenozoic.

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A coccolithophore concept for constraining the Cenozoic carbon cycle

Cited by 30 publications

References 45 publications

The uronic acid content of coccolith-associated polysaccharides provides insight into coccolithogenesis and past climate

The uronic acid content of coccolith-associated polysaccharides provides insight into coccolithogenesis and past climate

Control of ambient pH on growth and stable isotopes in phytoplanktonic calcifying algae

Vanishing coccolith vital effects with alleviated carbon limitation

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