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Heather Stoll - One of the best experts on this subject based on the ideXlab platform.
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Technical note: Accelerate Coccolith size separation via repeated centrifugation
Biogeosciences, 2021Co-Authors: Hongrui Zhang, Chuanlian Liu, Luz María Mejía, Heather StollAbstract:Abstract. Coccolithophores play a key role in the marine carbon cycle and ecosystem. The carbonate shells produced by Coccolithophore, named as Coccolith, could be well preserved in the marine sediment for millions of years and become an excellent archive for paleoclimate studies. The micro-filtering and sinking–decanting methods have been successfully designed for Coccolith separation and promoted the development of geochemistry studies on Coccolith, such as the stable isotopes and Sr / Ca ratio. However, these two methods are still not efficient enough for the sample-consuming methods. In this study, the trajectory of Coccolith movement during a centrifugation process was calculated in theory and carefully tested by separations in practice. We offer a MATLAB code to estimate the appropriate parameter, angular velocity at a fixed centrifugation duration, for separating certain Coccolith size fractions from bulk sediment. This work could improve the efficiency of Coccolith separation, especially for the finest size fraction, and make it possible to carry out the clumped isotope and radio carbon analyses on Coccoliths in sediment.
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Technical note: Accelerate Coccolith size separation via repeated centrifugation
2020Co-Authors: Hongrui Zhang, Chuanlian Liu, Luz María Mejía, Heather StollAbstract:Abstract. Coccolithophore play a key role in the marine carbon cycle and ecosystem. The carbonate shells produced by Coccolithophore, named as Coccolith, could be well preserved in the marine sediment for million years and become an excellent archive for paleoclimate studies. The micro filtering and sinking-decanting method have been successfully designed for Coccolith separation and promoted the development of geochemistry studies on Coccolith, such as the stable isotopes and Sr / Ca ratio. However, these two methods are still not efficient enough for the sample-consuming methods. In this study, the trajectory of Coccoliths movement during a centrifugation process was calculated in theory and carefully tested by separations in practice. We offer a matlab code to estimate the appropriate parameter, angular velocity at a fixed centrifugation duration, for separating certain Coccolith size fractions from bulk sediment. This work could improve the efficiency of Coccolith separation, especially for the finest size fraction and make it possible to carry the clumped isotope and radio carbon analysis on Coccolith in sediment.
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A refinement of Coccolith separation methods: Measuring the sinking characters of Coccoliths
2018Co-Authors: Hongrui Zhang, Xiao-bo Jin, Heather Stoll, Clara T Bolton, Chuanlian LiuAbstract:Abstract. The sinking velocities of individual Coccoliths are relevant for export of their CaCO 3 from the surface ocean, and for laboratory methods to separate Coccoliths of different sizes and species for geochemical analysis. In the laboratory, the repeat settling/decanting method was the earliest method to separate Coccolith from sediments for geochemical analyses, and is still widely used. However, in the absence of estimates of settling velocity for non-spherical Coccoliths, previous implementations have depended mainly on time consuming empirical method development by trial and error. In this study, the sinking velocities of Coccoliths belonging to different species were carefully measured in a series of settling experiments for the first time. Settling velocities of modern Coccoliths range from 0.154 to 10.67 cm h −1 . We found that a quadratic relationship between Coccolith length and sinking velocity fits well and Coccolith sinking velocity can be estimated by measuring the Coccolith length and using the length-velocity factor, ksv. We found a negligible difference in sinking velocities measured in different vessels. However, an appropriate choice of vessel must be made to avoid hindered settling in Coccolith separations. The experimental data and theoretical calculations presented here will support and improve the repeat settling/decanting method.
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Technical note: A refinement of Coccolith separation methods: measuring the sinking characteristics of Coccoliths
Biogeosciences, 2018Co-Authors: Hongrui Zhang, Xiao-bo Jin, Heather Stoll, Clara Bolton, Chuanlian LiuAbstract:Quantification sinking velocities of individual coc-coliths will contribute to optimizing laboratory methods for separating Coccoliths of different sizes and species for geo-chemical analysis. The repeated settling-decanting method was the earliest method proposed to separate Coccoliths from sediments and is still widely used. However, in the absence of estimates of settling velocity for nonspherical Coccoliths, previous implementations have depended mainly on time-consuming empirical method development by trial and error. In this study, the sinking velocities of Coccoliths belonging to different species were carefully measured in a series of settling experiments for the first time. Settling velocities of modern Coccoliths range from 0.154 to 10.67 cm h −1. We found that a quadratic relationship between Coccolith length and sinking velocity fits well, and Coccolith sinking velocity can be estimated by measuring the Coccolith length and using the length-velocity factor, k v. We found a negligible difference in sinking velocities measured in different vessels. However, an appropriate choice of vessel must be made to avoid "hindered settling" in Coccolith separations. The experimental data and theoretical calculations presented here support and improve the repeated settling-decanting method.
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vital effects in Coccolith calcite cenozoic climate pco2 drove the diversity of carbon acquisition strategies in Coccolithophores
Paleoceanography, 2012Co-Authors: Clara T Bolton, Heather Stoll, Ana MendezvicenteAbstract:[1] Coccoliths, calcite plates produced by the marine phytoplankton Coccolithophores, have previously shown a large array of carbon and oxygen stable isotope fractionations (termed “vital effects”), correlated to cell size and hypothesized to reflect the varying importance of active carbon acquisition strategies. Culture studies show a reduced range of vital effects between large and small Coccolithophores under high CO2, consistent with previous observations of a smaller range of interspecific vital effects in Paleocene Coccoliths. We present new fossil data examining Coccolithophore vital effects over three key Cenozoic intervals reflecting changing climate and atmospheric partial pressure of CO2 (pCO2). Oxygen and carbon stable isotopes of size-separated Coccolith fractions dominated by different species from well preserved Paleocene-Eocene thermal maximum (PETM, ∼56 Ma) samples show reduced interspecific differences within the greenhouse boundary conditions of the PETM. Conversely, isotope data from the Plio-Pleistocene transition (PPT; 3.5–2 Ma) and the last glacial maximum (LGM; ∼22 ka) show persistent vital effects of ∼2‰. PPT and LGM data show a clear positive trend between Coccolith (cell) size and isotopic enrichment in Coccolith carbonate, as seen in laboratory cultures. On geological timescales, the degree of expression of vital effects in Coccoliths appears to be insensitive topCO2 changes over the range ∼350 ppm (Pliocene) to ∼180 ppm (LGM). The modern array of Coccolith vital effects arose after the PETM but before the late Pliocene and may reflect the operation of more diverse carbon acquisition strategies in Coccolithophores in response to decreasing Cenozoic pCO2.
Michaël Hermoso - One of the best experts on this subject based on the ideXlab platform.
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Extreme strontium concentrations reveal specific biomineralization pathways in certain Coccolithophores with implications for the Sr/Ca paleoproductivity proxy
PloS one, 2017Co-Authors: Michaël Hermoso, Benjamin Lefeuvre, Fabrice Minoletti, Marc De RafélisAbstract:The formation of the Coccolith biominerals by a group of marine algae (the Coccolitho-phores) offers fascinating research avenues both from the biological and geological sides. It is surprising how biomineralisation by a key phytoplanktonic group remains undercon-strained, yet is influential on ocean alkalinity and responsible for the built up of our paleocli-matic archive over the last 200 Myrs. Here, we report two close relative Coccolith taxa exhibiting substantial bioaccumulation of strontium: Scyphosphaera and Pontosphaera grown in the laboratory or retrieved from Pliocene sediments. This strontium enrichment relative to calcium is one order of magnitude greater than reported in other Coccoliths of the orders Isochrysidales and Coccolithales, and extends well beyond established controls on Sr/Ca ratios by temperature and growth rate. We discuss this prominent vital effect in relation with possible specific uptake of strontium relative to calcium from the extracellular environment to the Coccolith vesicle in Coccolithophores excreting very large scale Coccoliths. The report of Sr-rich biominerals challenges our current understanding of the cellular acquisition and intracellular trafficking of alkaline earth cations in phytoplanktonic calcifying eukaryotic algae. The presence of Sr-rich Coccolith species in the geological record has to be quantitatively considered in future Sr/Ca-based palaeoceanographic reconstruction.
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The origin of carbon isotope vital effects in Coccolith calcite
Nature communications, 2017Co-Authors: Harry L. O. Mcclelland, Michaël Hermoso, J Bruggeman, Rosalind E. M. RickabyAbstract:Calcite microfossils are widely used to study climate and oceanography in Earth's geological past. Coccoliths, readily preserved calcite plates produced by a group of single-celled surface-ocean dwelling algae called Coccolithophores, have formed a significant fraction of marine sediments since the Late Triassic. However, unlike the shells of foraminifera, their zooplankton counterparts, Coccoliths remain underused in palaeo-reconstructions. Precipitated in an intracellular chemical and isotopic microenvironment, Coccolith calcite exhibits large and enigmatic departures from the isotopic composition of abiogenic calcite, known as vital effects. Here we show that the calcification to carbon fixation ratio determines whether Coccolith calcite is isotopically heavier or lighter than abiogenic calcite, and that the size of the deviation is determined by the degree of carbon utilization. We discuss the theoretical potential for, and current limitations of, Coccolith-based CO2 paleobarometry, that may eventually facilitate use of the ubiquitous and geologically extensive sedimentary archive.
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Laboratory-grown Coccoliths exhibit no vital effect in clumpet isotope (∆47) composition on a range of geologically relevant temperatures
Geochimica et Cosmochimica Acta, 2017Co-Authors: A. Katz, Michaël Hermoso, M. Bonifacie, P. Cartigny, D. CalmelsAbstract:The carbonate clumped isotope (or Δ47) thermometer relies on the temperature dependence of the abundance of 13C18O16O22- ion groups within the mineral lattice. This proxy shows tremendous promise to reconstruct sea surface temperatures (SSTs), but requires calibration of the relationship between Δ47 and calcification temperatures. Specifically, it is important to determine whether biologically-driven fractionation (the so-called “vital effect”) overprints Δ47 values, as reported in some biominerals such as the foraminifera and the Coccoliths for the carbon and oxygen isotope systems. Despite their abundance in the pelagic environment, Coccolithophores have not been comprehensively investigated to test the reliability of Coccolith Δ47-infered temperatures. In this study, we cultured three geologically-relevant Coccolith species (Emiliania huxleyi, Coccolithus pelagicus, and Calcidiscus leptoporus) at controlled temperatures between 7 and 25 ± 0.2 °C. Other variables such as pCO2, pH, alkalinity, nutrient concentrations, and salinity were kept constant at mean present-day oceanic conditions. Although cultured Coccoliths exhibit substantial species-specific oxygen and carbon isotope vital effects, we found that their Δ47 composition follows a statistically indistinguishable relationship with 1/T2 for all three species, indicating a lack of interspecific vital effects in Coccoliths. Further, the Δ47 composition of Coccolith calcite is identical to inorganic calcite precipitated at the same temperature, indicating an overall absence of clumped isotope vital effect in Coccolith biominerals. From a paleoceanographic perspective, this study indicates that the Δ47 values of sedimentary Coccoliths – even from highly diverse / mixed assemblages – can be analyzed to reconstruct SSTs with confidence, as such temperature estimates are not biased by taxonomic content or changing interspecies vital effects through time.
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Environmental control of the isotopic composition of subfossil Coccolith calcite: Are laboratory culture data transferable to the natural environment?
GeoResJ, 2015Co-Authors: Michaël Hermoso, Yaël Candelier, Thomas J. Browing, Fabrice MinolettiAbstract:Coccoliths contribute significantly to pelagic sediments formed over the last 200 million years, yet their geochemistry has been largely overlooked as a potential record of palaeoenvironmental information. Recently developed techniques have enabled successful extraction of Coccolith-dominated sediment fractions. However, the reliability of palaeoenvironmental interpretations that can be drawn from Coccolith analyses is still confounded by a poor understanding of the “vital effect” – the physiological component of the isotopic composition of biominerals. Here we demonstrate that oxygen isotope composition in core-top Coccoliths is not only set by the temperature and isotopic composition of seawater, but appears to be controlled to first order by the environmental factors regulating algal growth rate. Partial registration of the isotopic signature of assimilated CO2 (with a heavy isotopic composition relative to other dissolved inorganic carbon species) is confirmed to be the dominant mechanism behind the vital effect recorded in the Noelaerhabdaceae Coccoliths. Our data point towards a strong role of growth irradiance on expression of the 18O and 13C vital effects, ranging from limited (near equilibrium composition) in low light regimes to 3‰ offset in oxygen isotopes at higher growth irradiances, such as those found under light-saturated conditions typically imposed in laboratory cultures. This highlights the importance of considering environmental controls when translating oxygen isotope composition of Coccoliths into temperature estimates. Furthermore, our calibration suggests that the alkenone-based CO2 palaeobarometer proxy may be refined by combining paired organic/calcite measurements during the Cenozoic.
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Coccolith-Derived Isotopic Proxies in Palaeoceanography: Where Geologists Need Biologists
Cryptogamie Algologie, 2014Co-Authors: Michaël HermosoAbstract:Coccolithophore biominerals, the Coccoliths, represent an important part of the Meso-Cenozoic sedimentary archive. Geochemical analyses of Coccoliths can be used to unravel climatic fluctuations in the oceanic realm, but such reconstructions are complicated due to the problem of the "vital effect". This concept refers to the modulation in the record of the physico-chemistry of seawater in calcite due to algal physiology. For decades, it was thought that the magnitude of the vital effect was species-specific and constant for a given species. Recent studies aiming at a mechanistic understanding of these processes point towards a plastic and environmental-dependent interplay between the physiology of Coccolithophores and isotopic composition in Coccolith calcite. This "mobilis in mobili" relationship opens the door to the possibility to explore the vital effects as palaeoenvironmental proxies undertaking an interspecies approach. New physiological parameters, such as the quantification of calcification rates, pH, and calcium and carbon pools in the Coccolith vesicle would further help geologists to constrain the vital effect. Emerging "non-traditional" isotope systems will also contribute to refine the transfer functions between Coccolith geochemistry, vital effect, and palaeoenvironments.
Chuanlian Liu - One of the best experts on this subject based on the ideXlab platform.
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Technical note: Accelerate Coccolith size separation via repeated centrifugation
Biogeosciences, 2021Co-Authors: Hongrui Zhang, Chuanlian Liu, Luz María Mejía, Heather StollAbstract:Abstract. Coccolithophores play a key role in the marine carbon cycle and ecosystem. The carbonate shells produced by Coccolithophore, named as Coccolith, could be well preserved in the marine sediment for millions of years and become an excellent archive for paleoclimate studies. The micro-filtering and sinking–decanting methods have been successfully designed for Coccolith separation and promoted the development of geochemistry studies on Coccolith, such as the stable isotopes and Sr / Ca ratio. However, these two methods are still not efficient enough for the sample-consuming methods. In this study, the trajectory of Coccolith movement during a centrifugation process was calculated in theory and carefully tested by separations in practice. We offer a MATLAB code to estimate the appropriate parameter, angular velocity at a fixed centrifugation duration, for separating certain Coccolith size fractions from bulk sediment. This work could improve the efficiency of Coccolith separation, especially for the finest size fraction, and make it possible to carry out the clumped isotope and radio carbon analyses on Coccoliths in sediment.
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Technical note: Accelerate Coccolith size separation via repeated centrifugation
2020Co-Authors: Hongrui Zhang, Chuanlian Liu, Luz María Mejía, Heather StollAbstract:Abstract. Coccolithophore play a key role in the marine carbon cycle and ecosystem. The carbonate shells produced by Coccolithophore, named as Coccolith, could be well preserved in the marine sediment for million years and become an excellent archive for paleoclimate studies. The micro filtering and sinking-decanting method have been successfully designed for Coccolith separation and promoted the development of geochemistry studies on Coccolith, such as the stable isotopes and Sr / Ca ratio. However, these two methods are still not efficient enough for the sample-consuming methods. In this study, the trajectory of Coccoliths movement during a centrifugation process was calculated in theory and carefully tested by separations in practice. We offer a matlab code to estimate the appropriate parameter, angular velocity at a fixed centrifugation duration, for separating certain Coccolith size fractions from bulk sediment. This work could improve the efficiency of Coccolith separation, especially for the finest size fraction and make it possible to carry the clumped isotope and radio carbon analysis on Coccolith in sediment.
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late quaternary Coccolith weight variations in the northern south china sea and their environmental controls
Marine Micropaleontology, 2020Co-Authors: Chuanlian Liu, Luc BeaufortAbstract:Abstract Coccolithophores are one of the most abundant and widespread groups of calcifying plankton and have attracted extensive study in terms of their likely response to ocean acidification. Conflicting results concerning Coccolithophore calcification have been reported from both experimental and field studies. Due to their minute size, it is difficult to estimate the amount of calcite in Coccoliths. Here we apply the SYRACO system to analyzing the weights and lengths of Coccoliths produced by the dominant Coccolithophore family Noelaerhabdaceae. We obtain high-resolution Coccolith weight and length records of GEO (Gephyrocapsa oceanica) and SPC (Emiliania huxleyi and small Gephyrocapsa spp.) groups from sediment core MD05-2904 in the northern South China Sea (SCS) over the past 200 kyr. A calcification index (CI) based on the Coccolith weight and length is applied to evaluate the changes in Coccolithophore calcification. The two groups of Coccolith weights / CIs show different patterns on long term variations and during the last two terminations. We compare the Coccolith weight and CI records with the environmental variables and carbonate chemistry parameters calculated in the same core. Our data reveals that sea surface temperature and insolation have weak correlations to Coccolith weight and CI on long-term variations. The SPC weight / CI are correlated with the seawater pH and pCO2 variations while the GEO weight/ CI are more related to the nutrient variations. This implies a more significant role of ocean carbonate chemistry in the calcification of less calcified Coccolithophores and nutrient concentration in the heavier calcifying Coccolithophores.
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Coccolith morphological and assemblage responses to dissolution in the recent sediments of the East China Sea
Marine Micropaleontology, 2019Co-Authors: Xiao-bo Jin, Chuanlian Liu, Hongrui ZhangAbstract:Abstract Evaluating carbonate dissolution in deep sea sediments is of key importance in understanding the variation of the carbonate compensation depth and the ocean carbon cycle in the geological past. Since Coccoliths are one of the main contributors to oceanic CaCO3, their dissolution and preservation degrees in sediments can be a useful indicator for deep sea carbonate chemistry. Varying Coccolith preservation conditions have been found due to dissolution caused by organic matter degradation in the recent surface sediments of the East China Sea, which provides a good basis for the study of Coccolith morphological and assemblage responses to dissolution. We measured the Coccolith weight, thickness, and length of Gephyrocapsa spp. (>3 μm) using a circularly polarized light microscope. It has been found that Gephyrocapsa spp. (>3 μm) Coccoliths become thinner and lighter in response to dissolution, and Coccolith assemblages are also altered in poorly preserved sediments. This phenomenon was confirmed by an acidification experiment on a sediment sample, which also showed that Coccoliths became thinner and lighter under increasingly acidified conditions. There is selective dissolution, i.e., Emiliania huxleyi Coccoliths are most dissolution-prone, followed by Gephyrocapsa spp. ( 3 μm), and Helicosphaera spp.. Coccolith morphological parameters can be used to quantitatively evaluate Coccolith preservation and dissolution in sediment samples. We suggest that using size-normalized weight, a mean Coccolith weight loss of ~30–50% can be assigned to moderate-poor preservation for Coccoliths, as reflected by the measured Coccolith morphological changes in the surface sediments and in the acidification experiment.
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A refinement of Coccolith separation methods: Measuring the sinking characters of Coccoliths
2018Co-Authors: Hongrui Zhang, Xiao-bo Jin, Heather Stoll, Clara T Bolton, Chuanlian LiuAbstract:Abstract. The sinking velocities of individual Coccoliths are relevant for export of their CaCO 3 from the surface ocean, and for laboratory methods to separate Coccoliths of different sizes and species for geochemical analysis. In the laboratory, the repeat settling/decanting method was the earliest method to separate Coccolith from sediments for geochemical analyses, and is still widely used. However, in the absence of estimates of settling velocity for non-spherical Coccoliths, previous implementations have depended mainly on time consuming empirical method development by trial and error. In this study, the sinking velocities of Coccoliths belonging to different species were carefully measured in a series of settling experiments for the first time. Settling velocities of modern Coccoliths range from 0.154 to 10.67 cm h −1 . We found that a quadratic relationship between Coccolith length and sinking velocity fits well and Coccolith sinking velocity can be estimated by measuring the Coccolith length and using the length-velocity factor, ksv. We found a negligible difference in sinking velocities measured in different vessels. However, an appropriate choice of vessel must be made to avoid hindered settling in Coccolith separations. The experimental data and theoretical calculations presented here will support and improve the repeat settling/decanting method.
Patrizia Ziveri - One of the best experts on this subject based on the ideXlab platform.
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emiliania huxleyi Coccolith calcite mass modulation by morphological changes and ecology in the mediterranean sea
PLOS ONE, 2018Co-Authors: Barbara Damario, Patrizia Ziveri, Michael Grelaud, Angela Maria OviedoAbstract:To understand the response of marine calcifying organisms under high CO2 scenarios, it is critical to study their calcification patterns in the natural environment. This paper focuses on a major calcifying phytoplankton group, the Coccolithophores, through the analysis of water samples collected along a W-E Mediterranean transect during two research cruises, in April 2011 (Meteor cruise M84/3) and May 2013 (MedSeA cruise 2013). The Mediterranean Sea is a marginal sea characterized by large biogeochemical gradients. Currently, it is undergoing both warming and ocean acidification, processes which are rapidly modifying species distribution and calcification. The species Emiliania huxleyi largely dominates the total Coccolithophore production in present day oceans and marine basins, including the Mediterranean Sea. A series of morphometric measurements were performed on the Coccoliths of this species to estimate their mass, length and calculate a calcification index (proxy for the size-normalized calcification degree). The most abundant morphotype of E. huxleyi in the Mediterranean Sea is Type A. Coccoliths of this morphotype were additionally analyzed based on scanning electron microscopy images: four calcification varieties were quantified, according to the relationship between slit length-tube width, and the state of the central area (open or closed). The average E. huxleyi Coccolith mass along the Mediterranean oceanographic transect depended strongly on both the average Coccolith length and calcification index. The variability in average Coccolith length and calcification index across samples reflected oscillations in the relative abundance of the calcification varieties. We also demonstrated that the distribution of the calcification varieties followed the main environmental gradients (carbonate chemistry, salinity, temperature, nutrient concentrations). Hence, shifts in the distribution of the calcification varieties and of the average E. huxleyi Coccolith mass are to be expected in the Mediterranean Sea under climate change. These physiological and ecological responses will modulate the net Coccolithophore calcification and, ultimately, the regional carbonate export to the seafloor.
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relationship between Coccolith sr ca ratios and Coccolithophore production and export in the arabian sea and sargasso sea
Deep-sea Research Part Ii-topical Studies in Oceanography, 2007Co-Authors: Heather Stoll, Nobumichi Shimizu, Patrizia Ziveri, Maureen H Conte, Susanna TherouxAbstract:Coccolithophore CaCO3 production can account for 20–80% of biogenic carbonate exported from the photic zone, and Coccoliths are a dominant biogenic carbonate in many deep-sea sediments. A new method for picking individual Coccoliths from sediment traps and sediments for analysis using Secondary Ion Mass Spectrometry (ion probe) allows us to make precise Sr/Ca and Mg/Ca determinations on Coccoliths from single species even in samples where material is limited. There are large biological effects in Sr/Ca partitioning in Coccoliths that have been related to variations in Coccolithophore productivity. In sediment traps from the Sargasso Sea at Bermuda and Arabian Sea in the Somali Basin, we can identify Sr/Ca variations in several species that are consistent with inferred seasonal variations in Coccolithophore productivity in surface waters. In the Arabian Sea, Coccolith Sr/Ca ratios in Calcidiscus leptoporus and Helicosphaera carteri are lowest during the nonproductive intermonsoon. They are highest during the upwelling of southwest monsoon and during the nutrient entrainment from strong winds of the northeast monsoon. These Sr/Ca variations match seasonal trends in Coccolith export flux. Furthermore, Sr/Ca variations in C. leptoporus are larger, and this species also has the greater variation in export flux between southwest monsoon and intermonsoon seasons. At Bermuda, a 1996 fall bloom, driven by passage of a warm mode water eddy, induced a large increase in Sr/Ca of C. leptoporus coincident with an increase of C. leptoporus export. Over an annual series for 2004, highest Sr/Ca ratios of C. leptoporus in the summer months match the typical summer peak in surface standing stock of this species and the stimulation of its productivity by mesoscale cyclonic eddies and eddy–eddy interactions. High Sr/Ca did not coincide with the highest export of C. leptoporus Coccoliths, likely because cyclonic eddies, unlike mode-water eddies, are dominated by small phytoplankton with low export efficiency. These data confirm a relationship between Coccolith Sr/Ca ratios and productivity. Sr/Ca ratios of the smaller and more slowly sinking Emiliania huxleyi at Bermuda show very small (o4%) seasonal Sr/Ca variations. In contrast, nutrientlimited culture experiments for this species reveal significant (435%) increases in Sr/Ca with nitrate-stimulated growth
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present day Coccolith fluxes recorded in central eastern mediterranean sediment traps and surface sediments
Palaeogeography Palaeoclimatology Palaeoecology, 2000Co-Authors: Patrizia Ziveri, A Rutten, G J De Lange, J Thomson, C CorselliAbstract:Two sediment traps were deployed in time series collection from November 1991 to August 1994 at 3000 and 3500 m, respectively, above and below the oxygenated sea water/anoxic brine interface in the Bannock Basin, central eastern Mediterranean. Here, the Coccolithophore flux and its contribution to the carbonate particulate flux are presented for the 3000 m trap and compared with the record in eastern Mediterranean surface sediments. A marked seasonal variation is observed in the fluxes of total mass, total Coccoliths and whole coccospheres, with flux maxima in late winter and spring. The annual Coccolith flux of 1×1010 Coccoliths m?2 year?1 measured in the deep waters of Bannock Basin is much lower than published data from most other oceanographic settings, even when corrected for the trap efficiency of ~23% calculated from the 230Th flux. The biogenic and lithogenic fluxes are primarily controlled by Coccolithophore production and Saharan dust input, respectively. The calculated Coccolith and coccosphere settling rates, estimated from the comparison of maximum pigment concentration in the surface ocean and arrival of maximum flux at 3000 m water depth, ranged from 17 to 25 m day?1 for Coccoliths and 100 m day?1 for coccospheres. At the study site, carbonate dissolution is a minor process at both the trap depth and at the sea floor in both oxic and anoxic conditions, and there is a high preservation of Coccolith CaCO3. Coccolithophores are the main contributor to the biogenic carbonate flux, followed by thoracosphaerids. Emiliania huxleyi and Florisphaera profunda followed by Syracosphaera, Helicosphaera carteri and Calcidiscus leptoporus are the dominant species in the sediment trap and surface sediments.
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Coccolithophore export production species composition and Coccolith caco3 fluxes in the ne atlantic and
Deep-sea Research Part Ii-topical Studies in Oceanography, 2000Co-Authors: Alexandra T C Broerse, Patrizia Ziveri, Jan E Van Hinte, Susumu HonjoAbstract:Abstract Coccolithophores were examined in two sediment traps, deployed for one year (April 1989 to April 1990) at approximately 1 km water depth, in the subtropical NE Atlantic at 34° N 21° W (station NABE-34) and in the temperate NE Atlantic 48° N 21° W (station NABE-48) as part of the JGOFS North Atlantic Bloom Experiment (NABE). At both stations, maximum Coccolith and coccosphere fluxes were recorded during local spring bloom periods. The average Coccolith and coccosphere fluxes at NABE-34 were 1.12×10 9 m −2 d −1 and 4.90×10 6 m −2 d −1 , respectively. At this station Coccoliths from 51 taxa were identified. A marked seasonal change was noticed in relative abundances of Emiliania huxleyi and deep photic zone species: E. huxleyi dominated during spring, while in late autumn the Coccolith assemblage was dominated by Florisphaera profunda and the coccosphere assemblage by G. flabellatus and Algirosphaera spp.. Emiliania huxleyi was the most abundant species in the overall Coccolith and coccosphere assemblages with 69% and 64%, respectively. At NABE-48, the average daily fluxes were significantly lower, with 3.88×10 8 Coccoliths m −2 d −1 and 8.45×10 5 coccospheres m −2 d −1 , and only 36 taxa were recorded in the trap samples. Emiliania huxleyi was the dominant species in the Coccolith assemblage throughout the year with 72%, and showed maximum fluxes during spring 1990. Coccolithus pelagicus exhibited a distinct seasonal pattern, with maximum fluxes in early June 1989, probably related to the development of a mesoscale cyclonic eddy in the vicinity of the trap site. HoloCoccolithophore fluxes were highest during maximum sea surface temperatures in summer. The coccosphere assemblage was dominated by Gephyrocapsa spp., Syracosphaera spp., and E. huxleyi. Estimated CaCO3 fluxes of Coccoliths, coccospheres, and calcareous dinophytes were compared with the CaCO3 content in the fine ( μm ) fraction. The annual mass estimated CaCO3 flux of Coccoliths and coccospheres was 5.1 g m 2 yr at NABE-34 and 2.7 g m 2 yr at NABE-48, and that of calcareous dinophytes 0.9 and 0.1 g m 2 yr , respectively. These summed mass estimated values contributed on average only 55% at NABE-34 and 60% at NABE-48 to the fine fraction CaCO3.
Jeremy R. Young - One of the best experts on this subject based on the ideXlab platform.
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nanoprobe crystallographic orientation studies of isolated shield elements of the Coccolithophore species emiliania huxleyi
European Journal of Mineralogy, 2014Co-Authors: Ramona Hoffmann, Angela S. Wochnik, Erika Griesshaber, Jeremy R. Young, Christoph Heinzl, Sophia B Betzler, Sonja Matich, Hartmut Schulz, Michal Kucera, Christina ScheuAbstract:Coccolithophore algae produce elaborately structured skeletons composed of sub-micrometer-scale calcite crystals. In order to understand calcite crystallization and assembly in a coccosphere with nanoscale resolution, the crystal orientation and interdigitation of the structural units were investigated by transmission electron microscopy imaging, selected-area and nano-probe electron diffraction. Focused ion beam sectioning of Coccoliths of the Coccolithophore species Emiliania huxleyi is used to obtain target-prepared specimens in suitable orientation. We were able to detect and analyze the V-unit, which is overgrown by the R-unit. For the V-unit the 001 direction points perpendicular to the Coccolith plane while the 110 axis is tangential to the Coccolith ring. The R-unit c-axis is parallel and the b-axis is perpendicular to the Coccolith plane, thus confirming the R- and V-model which was based on scanning electron microscopy and optical microscopy. Furthermore we show that the distal- and the proximal shield element of an individual R-unit of a single segment are tilted by 4 degrees +/- 1 degrees with respect to each other. This orientation change is required to obtain the flat domed character of the Coccoliths, which is necessary to form the coccosphere. The orientation change between the distal- and the proximal shield element appears continuous.
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biometry of detached emiliania huxleyi Coccoliths along the patagonian shelf
Marine Ecology Progress Series, 2011Co-Authors: Alex J Poulton, Jeremy R. Young, Nicholas R Bates, William M. BalchAbstract:The biometry (morphology, size) of Coccoliths of the Coccolithophorid Emiliania huxleyi has implications for their calcite content and cellular rates of calcification. We investigated the biometry of detached Coccoliths of E. huxleyi in surface waters during the December 2008 ‘Coccolithophores of the Patagonian Shelf (COPAS’08)’ expedition. Two morphotypes of E. huxleyi were abundant along the shelf, although with different distributions: Morphotype A dominated waters on the shelf and at the northern end of the shelf, while Morphotype B/C dominated offshore and within the main Coccolithophore bloom. The 2 morphotypes had opposite relationships to environmental variables along the shelf: Morphotype B/C was abundant in cold ( 10 ?mol nitrate kg?1) waters with calcite saturation states of ~3.5, whereas Morphotype A was abundant in warm (>10°C), nutrientpoor 0.1 to 10 ?mol nitrate kg?1) waters with higher >4.5) calcite saturation states. These findings support previous suggestions that E. huxleyi morphotypes are distinct ecotypes. Furthermore, we suggest that Morphotype B/C is a Southern Ocean ecotype. Measurements of Coccolith distal shield length (total range: 1.8 to 4.4 ?m) indicated considerable physiological and/or phenotypic variability along the shelf and within each morphotype. Conversion of distal shield length into estimates of Coccolith calcite showed that the E. huxleyi population was producing Coccoliths with low median calcite quotas (overall average ± SD, 0.015 ± 0.006 pmol C) relative to other studies of field populations.
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Coccolith function and morphogenesis: insights from appendage-bearing Coccolithophores of the family syracosphaeraceae (haptophyta)
Journal of Phycology, 2009Co-Authors: Jeremy R. Young, Harald Andruleit, Ian ProbertAbstract:The morphology of three remarkable genera of Coccolithophores, Ophiaster, Michaelsarsia, and Calciopappus, is reviewed based on new images using field emission scanning electron microscopy. Each of these genera characteristically forms coccospheres with long appendages formed of highly modified Coccoliths, which radiate from either the circum-flagellar pole of the coccosphere (Calciopappus and Michaelsarsia) or the antapical pole (Ophiaster). For each genus, it is shown that the appendage Coccoliths can also occur in an alternative orientation appressed to the main coccosphere. It is hypothesized that the appendage Coccoliths are initially deployed in the appressed orientation and that extension of the appendages is a dynamic response to environmental stress. The observations suggest that Coccoliths are more sophisticatedly adapted to specific functions than has been assumed and that the cytoskeleton plays more active roles in Coccolith morphogenesis and deployment than has previously been inferred.
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Coccolith function and morphogenesis insights from appendage bearing Coccolithophores of the family syracosphaeraceae haptophyta 1
Journal of Phycology, 2009Co-Authors: Jeremy R. Young, Harald Andruleit, Ian ProbertAbstract:The morphology of three remarkable genera of Coccolithophores, Ophiaster, Michaelsarsia, and Calciopappus, is reviewed based on new images using field emission scanning electron microscopy. Each of these genera characteristically forms coccospheres with long appendages formed of highly modified Coccoliths, which radiate from either the circum-flagellar pole of the coccosphere (Calciopappus and Michaelsarsia) or the antapical pole (Ophiaster). For each genus, it is shown that the appendage Coccoliths can also occur in an alternative orientation appressed to the main coccosphere. It is hypothesized that the appendage Coccoliths are initially deployed in the appressed orientation and that extension of the appendages is a dynamic response to environmental stress. The observations suggest that Coccoliths are more sophisticatedly adapted to specific functions than has been assumed and that the cytoskeleton plays more active roles in Coccolith morphogenesis and deployment than has previously been inferred.
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biological control on calcite crystallization afm investigation of Coccolith polysaccharide function
American Mineralogist, 2004Co-Authors: Karen Friis Henriksen, Jeremy R. Young, S L S Stipp, M. E. MarshAbstract:Calcite crystals grown by organisms can be elaborate and enigmatic. One of the best examples is the tiny calcite shields known as Coccoliths that are produced by unicellular algae. Coccoliths consist of interlocking single crystals of highly modified morphology, and complex organic molecules called CAPs (Coccolith associated polysaccharides) are known to be intimately associated with their formation. Here, we show how a CAP can regulate crystal morphology to enhance precipitation of specific faces, a crucial aspect of the biomineralization process. Using atomic force microscopy (AFM), we investigated the interaction of CAP from the species Emiliania huxleyi with the calcite surface during dissolution, precipitation, and dynamic equilibrium. We were able to see the polysaccharide adsorbed to the surface and observe its impact on mineral behavior. These experiments demonstrate that CAP preferentially interacts with surface sites defined by acute, rather than obtuse, angles and blocks acute sites during dissolution and growth. Therefore, CAP makes the calcite face that is most stable in the pure system, {1014}, extend preferentially on the obtuse edges, promoting development of faces with lower angles to c -axis. AFM images of E. huxleyi at micrometer and atomic scales established that this is precisely the type of faces that define the morphology of the Coccolith crystals. Therefore, we propose that crystal shape regulation by CAP is a fundamental aspect of Coccolith biomineralization, and that preferential growth inhibition by site-specific functional groups is the mechanism causing CAP functionality.