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Sample records for coccolithophore emiliania huxleyi

  1. Phenotypic Variability in the Coccolithophore Emiliania huxleyi.

    Science.gov (United States)

    Blanco-Ameijeiras, Sonia; Lebrato, Mario; Stoll, Heather M; Iglesias-Rodriguez, Debora; Müller, Marius N; Méndez-Vicente, Ana; Oschlies, Andreas

    2016-01-01

    Coccolithophores are a vital part of oceanic phytoplankton assemblages that produce organic matter and calcium carbonate (CaCO3) containing traces of other elements (i.e. Sr and Mg). Their associated carbon export from the euphotic zone to the oceans' interior plays a crucial role in CO2 feedback mechanisms and biogeochemical cycles. The coccolithophore Emiliania huxleyi has been widely studied as a model organism to understand physiological, biogeochemical, and ecological processes in marine sciences. Here, we show the inter-strain variability in physiological and biogeochemical traits in 13 strains of E. huxleyi from various biogeographical provinces obtained from culture collections commonly used in the literature. Our results demonstrate that inter-strain genetic variability has greater potential to induce larger phenotypic differences than the phenotypic plasticity of single strains cultured under a broad range of variable environmental conditions. The range of variation found in physiological parameters and calcite Sr:Ca highlights the need to reconsider phenotypic variability in paleoproxy calibrations and model parameterizations to adequately translate findings from single strain laboratory experiments to the real ocean.

  2. Phenotypic Variability in the Coccolithophore Emiliania huxleyi.

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    Sonia Blanco-Ameijeiras

    Full Text Available Coccolithophores are a vital part of oceanic phytoplankton assemblages that produce organic matter and calcium carbonate (CaCO3 containing traces of other elements (i.e. Sr and Mg. Their associated carbon export from the euphotic zone to the oceans' interior plays a crucial role in CO2 feedback mechanisms and biogeochemical cycles. The coccolithophore Emiliania huxleyi has been widely studied as a model organism to understand physiological, biogeochemical, and ecological processes in marine sciences. Here, we show the inter-strain variability in physiological and biogeochemical traits in 13 strains of E. huxleyi from various biogeographical provinces obtained from culture collections commonly used in the literature. Our results demonstrate that inter-strain genetic variability has greater potential to induce larger phenotypic differences than the phenotypic plasticity of single strains cultured under a broad range of variable environmental conditions. The range of variation found in physiological parameters and calcite Sr:Ca highlights the need to reconsider phenotypic variability in paleoproxy calibrations and model parameterizations to adequately translate findings from single strain laboratory experiments to the real ocean.

  3. Inherent optical properties of the coccolithophore: Emiliania huxleyi.

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    Zhai, Peng-Wang; Hu, Yongxiang; Trepte, Charles R; Winker, David M; Josset, Damien B; Lucker, Patricia L; Kattawar, George W

    2013-07-29

    A realistic nonspherical model for Emiliania huxleyi (EHUX) is built, based on electron micrographs of coccolithophore cells. The Inherent Optical Properties (IOP) of the EHUX are then calculated numerically by using the discrete dipole approximation. The coccolithophore model includes a near-spherical core with the refractive index of 1.04 + m(i)j, and a carbonate shell formed by smaller coccoliths with refractive index of 1.2 + m(i)j, where m(i) = 0 or 0.01 and j(2) = -1. The reported IOP are the Mueller scattering matrix, backscattering probability, and depolarization ratio. Our calculation shows that the Mueller matrices of coccolithophores show different angular dependence from those of coccoliths.

  4. Coccolith arrangement follows Eulerian mathematics in the coccolithophore Emiliania huxleyi.

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    Xu, Kai; Hutchins, David; Gao, Kunshan

    2018-01-01

    The globally abundant coccolithophore, Emiliania huxleyi , plays an important ecological role in oceanic carbon biogeochemistry by forming a cellular covering of plate-like CaCO 3 crystals (coccoliths) and fixing CO 2 . It is unknown how the cells arrange different-sized coccoliths to maintain full coverage, as the cell surface area of the cell changes during daily cycle. We used Euler's polyhedron formula and CaGe simulation software, validated with the geometries of coccoliths, to analyze and simulate the coccolith topology of the coccosphere and to explore the arrangement mechanisms. There were only small variations in the geometries of coccoliths, even when the cells were cultured under variable light conditions. Because of geometric limits, small coccoliths tended to interlock with fewer and larger coccoliths, and vice versa. Consequently, to sustain a full coverage on the surface of cell, each coccolith was arranged to interlock with four to six others, which in turn led to each coccosphere contains at least six coccoliths. The number of coccoliths per coccosphere must keep pace with changes on the cell surface area as a result of photosynthesis, respiration and cell division. This study is an example of natural selection following Euler's polyhedral formula, in response to the challenge of maintaining a CaCO 3 covering on coccolithophore cells as cell size changes.

  5. Coccolith arrangement follows Eulerian mathematics in the coccolithophore Emiliania huxleyi

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    Kai Xu

    2018-04-01

    Full Text Available Background The globally abundant coccolithophore, Emiliania huxleyi, plays an important ecological role in oceanic carbon biogeochemistry by forming a cellular covering of plate-like CaCO3 crystals (coccoliths and fixing CO2. It is unknown how the cells arrange different-sized coccoliths to maintain full coverage, as the cell surface area of the cell changes during daily cycle. Methods We used Euler’s polyhedron formula and CaGe simulation software, validated with the geometries of coccoliths, to analyze and simulate the coccolith topology of the coccosphere and to explore the arrangement mechanisms. Results There were only small variations in the geometries of coccoliths, even when the cells were cultured under variable light conditions. Because of geometric limits, small coccoliths tended to interlock with fewer and larger coccoliths, and vice versa. Consequently, to sustain a full coverage on the surface of cell, each coccolith was arranged to interlock with four to six others, which in turn led to each coccosphere contains at least six coccoliths. Conclusion The number of coccoliths per coccosphere must keep pace with changes on the cell surface area as a result of photosynthesis, respiration and cell division. This study is an example of natural selection following Euler’s polyhedral formula, in response to the challenge of maintaining a CaCO3 covering on coccolithophore cells as cell size changes.

  6. Iron transport and storage in the coccolithophore: Emiliania huxleyi.

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    Hartnett, Andrej; Böttger, Lars H; Matzanke, Berthold F; Carrano, Carl J

    2012-11-01

    Iron is an essential element for all living organisms due to its ubiquitous role in redox and other enzymes, especially in the context of respiration and photosynthesis. The iron uptake and storage systems of terrestrial/higher plants are now reasonably well understood with two basic strategies for iron uptake being distinguished: strategy I plants use a mechanism involving soil acidification and induction of Fe(III)-chelate reductase (ferrireductase) and Fe(II) transporter proteins while strategy II plants have evolved sophisticated systems based on high-affinity, iron specific, binding compounds called phytosiderophores. In contrast, there is little knowledge about the corresponding systems in marine plant-like lineages. Herein we report a study of the iron uptake and storage mechanisms in the coccolithophore Emiliania huxleyi. Short term radio-iron uptake studies indicate that iron is taken up by Emiliania in a time and concentration dependent manner consistent with an active transport process. Based on inhibitor studies it appears that iron is taken up directly as Fe(iii). However if a reductive step is involved the Fe(II) must not be accessible to the external environment. Upon long term exposure to (57)Fe we have been able, using a combination of Mössbauer and XAS spectroscopies, to identify a single metabolite which displays spectral features similar to the phosphorus-rich mineral core of bacterial and plant ferritins.

  7. Environmental controls on the elemental composition of a Southern Hemisphere strain of the coccolithophore Emiliania huxleyi

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    Feng, Yuanyuan; Roleda, Michael Y.; Armstrong, Evelyn; Law, Cliff S.; Boyd, Philip W.; Hurd, Catriona L.

    2018-01-01

    A series of semi-continuous incubation experiments were conducted with the coccolithophore Emiliania huxleyi strain NIWA1108 (Southern Ocean isolate) to examine the effects of five environmental drivers (nitrate and phosphate concentrations, irradiance, temperature, and partial pressure of CO2 (pCO2)) on both the physiological rates and elemental composition of the coccolithophore. Here, we report the alteration of the elemental composition of E. huxleyi in response to the changes in these environmental drivers. A series of dose-response curves for the cellular elemental composition of E. huxleyi were fitted for each of the five drivers across an environmentally representative gradient. The importance of each driver in regulating the elemental composition of E. huxleyi was ranked using a semi-quantitative approach. The percentage variations in elemental composition arising from the change in each driver between present-day and model-projected conditions for the year 2100 were calculated. Temperature was the most important driver controlling both cellular particulate organic and inorganic carbon content, whereas nutrient concentrations were the most important regulator of cellular particulate nitrogen and phosphorus of E. huxleyi. In contrast, elevated pCO2 had the greatest influence on cellular particulate inorganic carbon to organic carbon ratio, resulting in a decrease in the ratio. Our results indicate that the different environmental drivers play specific roles in regulating the elemental composition of E. huxleyi with wide-reaching implications for coccolithophore-related marine biogeochemical cycles, as a consequence of the regulation of E. huxleyi physiological processes.

  8. Environmental controls on the elemental composition of a Southern Hemisphere strain of the coccolithophore Emiliania huxleyi

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    Y. Feng

    2018-01-01

    Full Text Available A series of semi-continuous incubation experiments were conducted with the coccolithophore Emiliania huxleyi strain NIWA1108 (Southern Ocean isolate to examine the effects of five environmental drivers (nitrate and phosphate concentrations, irradiance, temperature, and partial pressure of CO2 (pCO2 on both the physiological rates and elemental composition of the coccolithophore. Here, we report the alteration of the elemental composition of E. huxleyi in response to the changes in these environmental drivers. A series of dose–response curves for the cellular elemental composition of E. huxleyi were fitted for each of the five drivers across an environmentally representative gradient. The importance of each driver in regulating the elemental composition of E. huxleyi was ranked using a semi-quantitative approach. The percentage variations in elemental composition arising from the change in each driver between present-day and model-projected conditions for the year 2100 were calculated. Temperature was the most important driver controlling both cellular particulate organic and inorganic carbon content, whereas nutrient concentrations were the most important regulator of cellular particulate nitrogen and phosphorus of E. huxleyi. In contrast, elevated pCO2 had the greatest influence on cellular particulate inorganic carbon to organic carbon ratio, resulting in a decrease in the ratio. Our results indicate that the different environmental drivers play specific roles in regulating the elemental composition of E. huxleyi with wide-reaching implications for coccolithophore-related marine biogeochemical cycles, as a consequence of the regulation of E. huxleyi physiological processes.

  9. Impact of calcification state on the inherent optical properties of Emiliania huxleyi coccoliths and coccolithophores

    International Nuclear Information System (INIS)

    Bi, Lei; Yang, Ping

    2015-01-01

    Understanding the inherent optical properties (IOPs) of coccoliths and coccolithophores is important in oceanic radiative transfer simulations and remote sensing implementations. In this study, the invariant imbedding T-matrix method (II-TM) is employed to investigate the IOPs of coccoliths and coccolithophores. The Emiliania huxleyi (Ehux) coccolith and coccolithophore models are built based on observed biometric parameters including the eccentricity, the number of slits, and the rim width of detached coccoliths. The calcification state that specifies the amount of calcium of a single coccolith is critical in the determination of the size–volume/mass relationship (note, the volume/mass of coccoltihs at different calcification states are different although the diameters are the same). The present results show that the calcification state, namely, under-calcification, normal-calcification, or over-calcification, significantly influences the backscattering cross section and the phase matrix. Furthermore, the linear depolarization ratio of the light scattered by coccoliths is sensitive to the degree of calcification, and provides a potentially valuable parameter for interpreting oceanic remote sensing data. The phase function of an ensemble of randomly oriented coccolithophores has a similar pattern to that of individual coccoliths, but the forward scattering is dominant in the coccolithophores due to the large geometric cross sections. The linear depolarization ratio associated with coccolithophores is found to be larger than that for coccoliths as polarization is more sensitive to multiple scattering than the phase function. The simulated coccolithophore phase matrix numerical results are compared with laboratory measurements. For scattering angles larger than 100°, an increase of the phase function with respect to the scattering angle is confirmed based on the present coccolithophore model while the spherical approximation fails. - Highlights: • Realistic

  10. Effect of Ocean Acidification on the Food Quality of the Coccolithophore Emiliania huxleyi

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    Maine, J. E.; White, M. M.; Balch, W. M.; Milke, L. M.

    2016-02-01

    The anthropogenic burning of fossil fuels has doubled atmospheric carbon dioxide (CO2) levels over the last 200 years. Atmospheric CO2 diffuses into the ocean, changing the chemistry and decreasing the pH of seawater in a process called Ocean Acidification (OA). Calcifying marine phytoplankton, coccolithophores, are vulnerable to OA. Emiliania huxleyi is a lipid-dense and globally-abundant species of coccolithophore, therefore it is a vital food source for higher marine trophic levels. The objective of this project was to determine how OA affects the lipid profile and calcification of E. huxleyi CCMP #371. Gas chromatography was used to determine how the proportions of saturated (SFA), monounsaturated (MUFA), and polyunsaturated fatty acids (PUFA) in E. huxleyi varied with increasing pCO2. Flow cytometry was used to measure how the distribution of highly calcified cells, partially calcified cells, and un-calcified cells changed with increasing pCO2. The proportion of MUFA increased with pCO2. The proportion of un-calcified and partially calcified cells increased with increasing pCO2, however, the results varied across two experimental runs. In conclusion, the lipid-profile and calcification properties of E. huxleyi, and likely its food quality to predators, are affected by OA.

  11. Impact of calcification state on the inherent optical properties of Emiliania huxleyi coccoliths and coccolithophores

    Science.gov (United States)

    Bi, Lei; Yang, Ping

    2015-04-01

    Understanding the inherent optical properties (IOPs) of coccoliths and coccolithophores is important in oceanic radiative transfer simulations and remote sensing implementations. In this study, the invariant imbedding T-matrix method (II-TM) is employed to investigate the IOPs of coccoliths and coccolithophores. The Emiliania huxleyi (Ehux) coccolith and coccolithophore models are built based on observed biometric parameters including the eccentricity, the number of slits, and the rim width of detached coccoliths. The calcification state that specifies the amount of calcium of a single coccolith is critical in the determination of the size-volume/mass relationship (note, the volume/mass of coccoltihs at different calcification states are different although the diameters are the same). The present results show that the calcification state, namely, under-calcification, normal-calcification, or over-calcification, significantly influences the backscattering cross section and the phase matrix. Furthermore, the linear depolarization ratio of the light scattered by coccoliths is sensitive to the degree of calcification, and provides a potentially valuable parameter for interpreting oceanic remote sensing data. The phase function of an ensemble of randomly oriented coccolithophores has a similar pattern to that of individual coccoliths, but the forward scattering is dominant in the coccolithophores due to the large geometric cross sections. The linear depolarization ratio associated with coccolithophores is found to be larger than that for coccoliths as polarization is more sensitive to multiple scattering than the phase function. The simulated coccolithophore phase matrix numerical results are compared with laboratory measurements. For scattering angles larger than 100°, an increase of the phase function with respect to the scattering angle is confirmed based on the present coccolithophore model while the spherical approximation fails.

  12. Gene expression changes in the coccolithophore Emiliania huxleyi after 500 generations of selection to ocean acidification.

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    Lohbeck, Kai T; Riebesell, Ulf; Reusch, Thorsten B H

    2014-07-07

    Coccolithophores are unicellular marine algae that produce biogenic calcite scales and substantially contribute to marine primary production and carbon export to the deep ocean. Ongoing ocean acidification particularly impairs calcifying organisms, mostly resulting in decreased growth and calcification. Recent studies revealed that the immediate physiological response in the coccolithophore Emiliania huxleyi to ocean acidification may be partially compensated by evolutionary adaptation, yet the underlying molecular mechanisms are currently unknown. Here, we report on the expression levels of 10 candidate genes putatively relevant to pH regulation, carbon transport, calcification and photosynthesis in E. huxleyi populations short-term exposed to ocean acidification conditions after acclimation (physiological response) and after 500 generations of high CO2 adaptation (adaptive response). The physiological response revealed downregulation of candidate genes, well reflecting the concomitant decrease of growth and calcification. In the adaptive response, putative pH regulation and carbon transport genes were up-regulated, matching partial restoration of growth and calcification in high CO2-adapted populations. Adaptation to ocean acidification in E. huxleyi likely involved improved cellular pH regulation, presumably indirectly affecting calcification. Adaptive evolution may thus have the potential to partially restore cellular pH regulatory capacity and thereby mitigate adverse effects of ocean acidification. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  13. A synergetic biomineralization strategy for immobilizing strontium during calcification of the coccolithophore Emiliania huxleyi.

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    Sun, Shiyong; Liu, Mingxue; Nie, Xiaoqin; Dong, Faqin; Hu, Wenyuan; Tan, Daoyong; Huo, Tingting

    2018-01-24

    The coccolithophore species Emiliania huxleyi has one of the most global distributions in the modern oceans. They are characteristically covered with calcite scales called coccoliths. In this study, stable strontium immobilization during the calcification process was investigated to indirectly assess a proposed bioremediation approach for removing Sr 2+ contamination from marine environments. Results indicate that E. huxleyi has high Sr 2+ tolerance and removal efficiency in response to Sr 2+ stress ranging from 5.6 to 105.6 ppm. Sr 2+ immobilization during E. huxleyi calcification indicates a concentration-dependent synergistic mechanism. At lower concentrations of Sr 2+ (25.6 ppm), Sr 2+ is incorporated into coccoliths through competitive supply between Sr 2+ and Ca 2+ . In addition, calcite productivity decreases with increased Sr 2+ removal efficiency due to crystallographic transformation of coccoliths from hydrated calcite into aragonite at 55.6 ppm Sr 2+ . Further formation of strontianite at 105.6 ppm Sr 2+ is due to precipitation of Sr 2+ on the edge of the rims and radial arrays of the coccoliths. Our study implies that coccolithophores are capable of significant removal of Sr 2+ from the marine environment.

  14. Intragenomic spread of plastid-targeting presequences in the coccolithophore Emiliania huxleyi.

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    Burki, Fabien; Hirakawa, Yoshihisa; Keeling, Patrick J

    2012-09-01

    Nucleus-encoded plastid-targeted proteins of photosynthetic organisms are generally equipped with an N-terminal presequence required for crossing the plastid membranes. The acquisition of these presequences played a fundamental role in the establishment of plastids. Here, we report a unique case of two non-homologous proteins possessing completely identical presequences consisting of a bipartite plastid-targeting signal in the coccolithophore Emiliania huxleyi. We further show that this presequence is highly conserved in five additional proteins that did not originally function in plastids, representing de novo plastid acquisitions. These are among the most recent cases of presequence spreading from gene to gene and shed light on important evolutionary processes that have been usually erased by the ancient history of plastid evolution. We propose a mechanism of acquisition involving genomic duplications and gene replacement through non-homologous recombination that may have played a more general role for equipping proteins with targeting information.

  15. A Bacterial Quorum-Sensing Precursor Induces Mortality in the Marine Coccolithophore, Emiliania huxleyi.

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    Harvey, Elizabeth L; Deering, Robert W; Rowley, David C; El Gamal, Abrahim; Schorn, Michelle; Moore, Bradley S; Johnson, Matthew D; Mincer, Tracy J; Whalen, Kristen E

    2016-01-01

    Interactions between phytoplankton and bacteria play a central role in mediating biogeochemical cycling and food web structure in the ocean. However, deciphering the chemical drivers of these interspecies interactions remains challenging. Here, we report the isolation of 2-heptyl-4-quinolone (HHQ), released by Pseudoalteromonas piscicida, a marine gamma-proteobacteria previously reported to induce phytoplankton mortality through a hitherto unknown algicidal mechanism. HHQ functions as both an antibiotic and a bacterial signaling molecule in cell-cell communication in clinical infection models. Co-culture of the bloom-forming coccolithophore, Emiliania huxleyi with both live P. piscicida and cell-free filtrates caused a significant decrease in algal growth. Investigations of the P. piscicida exometabolome revealed HHQ, at nanomolar concentrations, induced mortality in three strains of E. huxleyi. Mortality of E. huxleyi in response to HHQ occurred slowly, implying static growth rather than a singular loss event (e.g., rapid cell lysis). In contrast, the marine chlorophyte, Dunaliella tertiolecta and diatom, Phaeodactylum tricornutum were unaffected by HHQ exposures. These results suggest that HHQ mediates the type of inter-domain interactions that cause shifts in phytoplankton population dynamics. These chemically mediated interactions, and other like it, ultimately influence large-scale oceanographic processes.

  16. A bacterial quorum-sensing precursor induces mortality in the marine coccolithophore, Emiliania huxleyi

    Directory of Open Access Journals (Sweden)

    Elizabeth L Harvey

    2016-02-01

    Full Text Available Interactions between phytoplankton and bacteria play a central role in mediating biogeochemical cycling and food web structure in the ocean. However, deciphering the chemical drivers of these interspecies interactions remains challenging. Here we report the isolation of 2-heptyl-4-quinolone (HHQ, released by Pseudoalteromonas piscicida, a marine gamma-proteobacteria previously reported to induce phytoplankton mortality through a hitherto unknown algicidal mechanism. HHQ functions as both an antibiotic and a bacterial signaling molecule in cell-cell communication in clinical infection models. Co-culture of the bloom-forming coccolithophore, Emiliania huxleyi with both live P. piscicida and cell-free filtrates caused a significant decrease in algal growth. Investigations of the P. piscicida exometabolome revealed HHQ, at nanomolar concentrations, induced mortality in three strains of E. huxleyi. Mortality of E. huxleyi in response to HHQ occurred slowly, implying static growth rather than a singular loss event (e.g. rapid cell lysis. In contrast, the marine chlorophyte, Dunaliella tertiolecta and diatom, Phaeodactylum tricornutum were unaffected by HHQ exposures. These results suggest that HHQ mediates the type of interkingdom interactions that cause shifts in phytoplankton population dynamics. These chemically mediated interactions, and other like it, ultimately influence large-scale oceanographic processes.

  17. In situ survey of life cycle phases of the coccolithophore Emiliania huxleyi (Haptophyta).

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    Frada, Miguel J; Bidle, Kay D; Probert, Ian; de Vargas, Colomban

    2012-06-01

    The cosmopolitan coccolithophore Emiliania huxleyi is characterized by a strongly differentiated haplodiplontic life cycle consisting of a diploid phase, generally bearing coccoliths (calcified) but that can be also non-calcified, and a non-calcified biflagellated haploid phase. Given most studies have focused on the bloom-producing calcified phase, there is little-to-no information about non-calcified cells in nature. Using field mesocoms as experimental platforms, we quantitatively surveyed calcified and non-calcified cells using the combined calcareous detection fluorescent in situ hybridization (COD-FISH) method and qualitatively screened for haploid specific transcripts using reverse transcription-PCR during E. huxleyi bloom successions. Diploid, calcified cells formed dense blooms that were followed by the massive proliferation of E. huxleyi viruses (EhVs), which caused bloom demise. Non-calcified cells were also detected throughout the experiment, accounting for a minor fraction of the population but becoming progressively more abundant during mid-late bloom periods concomitant with EhV burst. Non-calcified cell growth also paralleled a distinct window of haploid-specific transcripts and the appearance of autotrophic flagellates morphologically similar to haploid cells, both of which are suggestive of meiosis and sexual life cycling during natural blooms of this prominent marine phytoplankton species. © 2012 Society for Applied Microbiology and Blackwell Publishing Ltd.

  18. Growth of the coccolithophore Emiliania huxleyi in light- and nutrient-limited batch reactors: relevance for the BIOSOPE deep ecological niche of coccolithophores

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    Perrin, Laura; Probert, Ian; Langer, Gerald; Aloisi, Giovanni

    2016-11-01

    Coccolithophores are unicellular calcifying marine algae that play an important role in the oceanic carbon cycle via their cellular processes of photosynthesis (a CO2 sink) and calcification (a CO2 source). In contrast to the well-studied, surface-water coccolithophore blooms visible from satellites, the lower photic zone is a poorly known but potentially important ecological niche for coccolithophores in terms of primary production and carbon export to the deep ocean. In this study, the physiological responses of an Emiliania huxleyi strain to conditions simulating the deep niche in the oligotrophic gyres along the BIOSOPE transect in the South Pacific Gyre were investigated. We carried out batch culture experiments with an E. huxleyi strain isolated from the BIOSOPE transect, reproducing the in situ conditions of light and nutrient (nitrate and phosphate) limitation. By simulating coccolithophore growth using an internal stores (Droop) model, we were able to constrain fundamental physiological parameters for this E. huxleyi strain. We show that simple batch experiments, in conjunction with physiological modelling, can provide reliable estimates of fundamental physiological parameters for E. huxleyi that are usually obtained experimentally in more time-consuming and costly chemostat experiments. The combination of culture experiments, physiological modelling and in situ data from the BIOSOPE cruise show that E. huxleyi growth in the deep BIOSOPE niche is limited by availability of light and nitrate. This study contributes more widely to the understanding of E. huxleyi physiology and behaviour in a low-light and oligotrophic environment of the ocean.

  19. Independence of nutrient limitation and carbon dioxide impacts on the Southern Ocean coccolithophore Emiliania huxleyi.

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    Müller, Marius N; Trull, Thomas W; Hallegraeff, Gustaaf M

    2017-08-01

    Future oceanic conditions induced by anthropogenic greenhouse gas emissions include warming, acidification and reduced nutrient supply due to increased stratification. Some parts of the Southern Ocean are expected to show rapid changes, especially for carbonate mineral saturation. Here we compare the physiological response of the model coccolithophore Emiliania huxleyi (strain EHSO 5.14, originating from 50 o S, 149 o E) with pH/CO 2 gradients (mimicking ocean acidification ranging from 1 to 4 × current pCO 2 levels) under nutrient-limited (nitrogen and phosphorus) and -replete conditions. Both nutrient limitations decreased per cell photosynthesis (particulate organic carbon (POC) production) and calcification (particulate inorganic carbon (PIC) production) rates for all pCO 2 levels, with more than 50% reductions under nitrogen limitation. These impacts, however, became indistinguishable from nutrient-replete conditions when normalized to cell volume. Calcification decreased three-fold and linearly with increasing pCO 2 under all nutrient conditions, and was accompanied by a smaller ~30% nonlinear reduction in POC production, manifested mainly above 3 × current pCO 2 . Our results suggest that normalization to cell volume allows the major impacts of nutrient limitation (changed cell sizes and reduced PIC and POC production rates) to be treated independently of the major impacts of increasing pCO 2 and, additionally, stresses the importance of including cell volume measurements to the toolbox of standard physiological analysis of coccolithophores in field and laboratory studies.

  20. Size-fractionated dissolved primary production and carbohydrate composition of the coccolithophore Emiliania huxleyi

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    Borchard, C.; Engel, A.

    2015-02-01

    Extracellular release (ER) by phytoplankton is the major source of fresh dissolved organic carbon (DOC) in marine ecosystems and accompanies primary production during all growth phases. Little is known, so far, on size and composition of released molecules, and to which extent ER occurs passively, by leakage, or actively, by exudation. Here, we report on ER by the widespread and bloom-forming coccolithophore Emiliania huxleyi grown under steady-state conditions in phosphorus-controlled chemostats (N:P = 29, growth rate of μ = 0.2 d-1) at present-day and high-CO2 concentrations. 14C incubations were performed to determine primary production (PP), comprised of particulate (PO14C) and dissolved organic carbon (DO14C). Concentration and composition of particulate combined carbohydrates (pCCHO) and high-molecular-weight (>1 kDa, HMW) dissolved combined carbohydrates (dCCHO) were determined by ion chromatography. Information on size distribution of ER products was obtained by investigating distinct size classes (10 kDa was significantly different, with a higher mol% of arabinose. The mol% of acidic sugars increased and that of glucose decreased with increasing size of HMW-dCCHO. We conclude that larger polysaccharides follow different production and release pathways than smaller molecules, potentially serving distinct ecological and biogeochemical functions.

  1. Characterization of the selenite uptake mechanism in the coccolithophore Emiliania huxleyi (Haptophyta).

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    Araie, Hiroya; Sakamoto, Kou; Suzuki, Iwane; Shiraiwa, Yoshihiro

    2011-07-01

    The marine coccolithophore Emiliania huxleyi (Haptophyta) requires selenium as an essential element for growth, and the active species absorbed is selenite, not selenate. This study characterized the selenite uptake mechanism using ⁷⁵Se as a tracer. Kinetic analysis of selenite uptake showed the involvement of both active and passive transport processes. The active transport was suppressed by 0.5 mM vanadate, a membrane-permeable inhibitor of H⁺-ATPase, at pH 8.3. When the pH was lowered from 8.3 to 5.3, the selenite uptake activity greatly increased, even in the presence of vanadate, suggesting that the H⁺ concentration gradient may be a motive force for selenite transport. [⁷⁵Se]Selenite uptake at selenite-limiting concentrations was hardly affected by selenate, sulfate and sulfite, even at 100 μM. In contrast, 3 μM orthophosphate increased the K(m) 5-fold. These data showed that HSeO₃⁻, a dominant selenite species at acidic pH, is the active species for transport through the plasma membrane and transport is driven by ΔpH energized by H⁺-ATPase. Kinetic analysis showed that the selenite uptake activity was competitively inhibited by orthophosphate. Furthermore, the active selenite transport mechanism was shown to be induced de novo under Se-deficient conditions and induction was suppressed by the addition of either sufficient selenite or cycloheximide, an inhibitor of de novo protein synthesis. These results indicate that E. huxleyi cells developed an active selenite uptake mechanism to overcome the disadvantages of Se limitation in ecosystems, maintaining selenium metabolism and selenoproteins for high viability.

  2. The “Cheshire Cat” escape strategy of the coccolithophore Emiliania huxleyi in response to viral infection

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    Frada, Miguel; Probert, Ian; Allen, Michael J.; Wilson, William H.; de Vargas, Colomban

    2008-01-01

    The coccolithophore Emiliania huxleyi is one of the most successful eukaryotes in modern oceans. The two phases in its haplodiploid life cycle exhibit radically different phenotypes. The diploid calcified phase forms extensive blooms, which profoundly impact global biogeochemical equilibria. By contrast, the ecological role of the noncalcified haploid phase has been completely overlooked. Giant phycodnaviruses (Emiliania huxleyi viruses, EhVs) have been shown to infect and lyse diploid-phase cells and to be heavily implicated in the regulation of populations and the termination of blooms. Here, we demonstrate that the haploid phase of E. huxleyi is unrecognizable and therefore resistant to EhVs that kill the diploid phase. We further show that exposure of diploid E. huxleyi to EhVs induces transition to the haploid phase. Thus we have clearly demonstrated a drastic difference in viral susceptibility between life cycle stages with different ploidy levels in a unicellular eukaryote. Resistance of the haploid phase of E. huxleyi provides an escape mechanism that involves separation of meiosis from sexual fusion in time, thus ensuring that genes of dominant diploid clones are passed on to the next generation in a virus-free environment. These “Cheshire Cat” ecological dynamics release host evolution from pathogen pressure and thus can be seen as an opposite force to a classic “Red Queen” coevolutionary arms race. In E. huxleyi, this phenomenon can account for the fact that the selective balance is tilted toward the boom-and-bust scenario of optimization of both growth rates of calcifying E. huxleyi cells and infectivity of EhVs. PMID:18824682

  3. The coccolithophores Emiliania huxleyi and Coccolithus pelagicus: Extant populations from the Norwegian-Iceland Seas and Fram Strait

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    Dylmer, C. V.; Giraudeau, J.; Hanquiez, V.; Husum, K.

    2015-04-01

    The distributions of the coccolithophore species Emiliania huxleyi and Coccolithus pelagicus (heterococcolith-bearing phase) in the northern North Atlantic were investigated along two zonal transects crossing Fram Strait and the Norwegian-Iceland Sea, respectively, each conducted during both July 2011 and September-October 2007. Remote-sensing images as well as CTD and ARGO profiles were used to constrain the physico-chemical state of the surface water and surface mixed layer at the time of sampling. Strong seasonal differences in bulk coccolithophore standing stocks characterized the northern and southern transects, where the maximum values of 53×103 cells/l (fall) and 70×103 cells/l (summer), respectively, were essentially explained by E. huxleyi. This pattern confirms previous findings of a summer to fall northwestward shift in peak coccolithophore cell densities within the Nordic Seas. While depicting an overall zonal shift in high cell densities between the summer (Norwegian Sea) and fall (northern Iceland Sea) conditions, the southern transects were additionally characterized by local peak coccolithophore concentrations associated with a geographically and temporally restricted convective process (Lofoten Gyre, summer), as well as an island mass effect (in the vicinity of Jan Mayen Island, fall). Maximum coccolithophore abundances within Fram Strait were found during both seasons close to the western frontal zone (Polar and Arctic Fronts) an area of strong density gradients where physical and chemical properties of the surface mixed layer are prone to enhance phytoplankton biomass and productivity. Here, changes in species dominance from E. huxleyi in summer, to C. pelagicus in fall, were related to the strengthened influence during summer, of surface AW, as well as to high July solar irradiance, within an area usually characterized by C. pelagicus-dominated low density populations.

  4. ASSESSING THE ROLE OF CASPASE ACTIVITY AND METACASPASE EXPRESSION ON VIRAL SUSCEPTIBILITY OF THE COCCOLITHOPHORE, EMILIANIA HUXLEYI (HAPTOPHYTA).

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    Bidle, Kay D; Kwityn, Clifford J

    2012-10-01

    As part of their strategy to infect the globally important coccolithophore, Emiliania huxleyi (Lohmann) W.W. Hay & H.P. Mohler, Coccolithoviruses trigger and regulate the host's programmed cell death (PCD) machinery during lytic infection. The induction and recruitment of host metacaspases, specialized, ancestral death proteases that facilitate viral lysis, suggests they may be important subcellular determinants to infection. We examined the "basal" levels and patterns of caspase activity and metacaspase expression in exponentially growing resistant and sensitive E. huxleyi strains and linked them with susceptibility to E. huxleyi virus 1 (EhV1). Resistant E. huxleyi strains were consistently characterized by low caspase specific activity and a relatively simple metacaspase expression profile. In contrast, sensitive E. huxleyi strains had markedly elevated caspase specific activity and consistently expressed more diverse metacaspase proteins. Using pooled data sets from triplicate experiments, we observed statistically significant linear correlations between infectivity, caspase activity, and metacaspase expression, with each strain forming distinct clusters, within a gradient in viral susceptibility. At the same time, we observed positive correlations between the expression of a subset of metacaspase proteins and lower susceptibility, suggestive of potential protective roles. Our findings implicate the importance of subtle differences in the basal physiological regulation of the PCD machinery to viral resistance or sensitivity and cell fate. © 2012 Phycological Society of America.

  5. Identification and functional characterisation of genes encoding the omega-3 polyunsaturated fatty acid biosynthetic pathway from the coccolithophore Emiliania huxleyi.

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    Sayanova, Olga; Haslam, Richard P; Calerón, Monica Venegas; López, Noemi Ruiz; Worthy, Charlotte; Rooks, Paul; Allen, Michael J; Napier, Johnathan A

    2011-05-01

    The Prymnesiophyceae coccolithophore Emiliania huxleyi is one of the most abundant alga in our oceans and therefore plays a central role in marine foodwebs. E. huxleyi is notable for the synthesis and accumulation of the omega-3 long chain polyunsaturated fatty acid docosahexaenoic acid (DHA; 22:6Δ(4,7,10,13,16,19), n-3) which is accumulated in fish oils and known to have health-beneficial properties to humans, preventing cardiovascular disease and related pathologies. Here we describe the identification and functional characterisation of the five E. huxleyi genes which direct the synthesis of docosahexaenoic acid in this alga. Surprisingly, E. huxleyi does not use the conventional Δ6-pathway, instead using the alternative Δ8-desaturation route which has previously only been observed in a few unrelated microorganisms. Given that E. huxleyi accumulates significant levels of the Δ6-desaturated fatty acid stearidonic acid (18:4Δ(6,9,12,15), n-3), we infer that the biosynthesis of DHA is likely to be metabolically compartmentalised from the synthesis of stearidonic acid. Copyright © 2011 Elsevier Ltd. All rights reserved.

  6. Evidence for strain-specific exometabolomic responses of the coccolithophore Emiliania huxleyi to grazing by the dinoflagellate Oxyrrhis marina.

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    Kelsey L Poulson-Ellestad

    2016-01-01

    Full Text Available The coccolithophore Emiliania huxleyi forms massive blooms and plays a critical role in global elemental cycles, sequestering significant amounts of atmospheric carbon dioxide on geological time scales via production of calcium carbonate coccoliths and emitting dimethyl sulfoniopropionate (DMSP which has the potential for increasing atmospheric albedo. Because grazing in pelagic systems is a major top-down force structuring microbial communities, the influence of grazers on E. huxleyi populations has been of interest to researchers. Roles of DMSP (and related metabolites in interactions between E. huxleyi and protist grazers have been investigated, however, little is known about the release of other metabolites that may influence, or be influenced by, such grazing interactions. We used high-resolution mass spectrometry in an untargeted approach to survey the suite of low molecular weight compounds released by four different E. huxleyi strains in response to grazing by the dinoflagellate Oxyrrhis marina. Overall, a strikingly small number of metabolites were detected from E. huxleyi and O. marina cells, but these were distinctly informative to construct metabolic footprints. At most, E. huxleyi strains shared 25% of released metabolites. Furthermore, there appeared to be no unified metabolic response in E. huxleyi strains to grazing; rather these responses were strain specific. Concentrations of several metabolites also positively correlated with grazer activities, including grazing, ingestion, and growth rates; however, no single metabolite responded uniformly across all strains of E. huxleyi tested. Regardless, grazing clearly transformed the constituents of dissolved organic matter produced by these marine microbes. This study addresses several technical challenges, and presents a platform to further study the influence of chemical cues in aquatic systems and demonstrates the impact of strain diversity and grazing on the complexity of

  7. Environmental control on Emiliania huxleyi coccolithophore calcification in the Mediterranean Sea

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    D'Amario, Barbara; Grelaud, Michael; Ziveri, Patrizia

    2016-04-01

    The Mediterranean Sea, a "natural laboratory" characterized by strong environmental gradients, is likely to undergo serious alterations due to climate change and ocean acidification. These processes are expected to affect also phytoplankton distribution. Coccolithophores are the only phytoplankton calcifying group and laboratory studies on E. huxleyi, the most abundant and widely distributed species of coccolithophores worldwide, yield strain-specific results. Culture experiments must be integrated with observations in the natural environment to understand existing interactions between drivers, and to verify population structures in different areas. Two transects spanning the south-western and south-eastern basins have been investigated, combining data from April 2011 (Meteor cruise M84/3) and May 2013 (MedSeA cruise). E. huxleyi coccolith morphometry was analyzed to determine average mass and length. These results were then compared with morphological observations performed on the largely dominant E. huxleyi Type A through scanning electron microscope (SEM). We distinguished four main calcification morphologies within E. huxleyi Type A: low-calcified (A1), medium-calcified (A2), high-calcified with closed central area (A3a), and open central area (A3b). E. huxleyi coccolith mass was strongly and positively correlated with the relative abundance of a particular morphology. Moreover, the calcification morphologies were preferentially distributed in the Mediterranean according to specific combinations of environmental variables, which included the carbonate chemistry system. The distribution of E. huxleyi Type A calcification morphologies in the Mediterranean is likely to be influenced by climate changes. Coccolithophore calcification degree is connected to the carbon cycle through photosynthesis / calcification ratio and sedimentation (particulate inorganic and organic carbon reaching the seafloor). This study aims to provide a basis for future investigations on the

  8. Genetic delineation between and within the widespread coccolithophore morpho-species Emiliania huxleyi and Gephyrocapsa oceanica (Haptophyta).

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    Bendif, El Mahdi; Probert, Ian; Carmichael, Margaux; Romac, Sarah; Hagino, Kyoko; de Vargas, Colomban

    2014-02-01

    Emiliania huxleyi and Gephyrocapsa oceanica are abundant coccolithophore morpho-species that play key roles in ocean carbon cycling due to their importance as both primary producers and cal-cifiers. Global change processes such as ocean acidification impact these key calcifying species. The physiology of E. huxleyi, a developing model species, has been widely studied, but its genetic delineation from G. oceanica remains unclear due to a lack of resolution in classical genetic markers. Using nuclear (18S rDNA and 28S rDNA), mitochondrial (cox1, cox2, cox3, rpl16, and dam), and plastidial (16S rDNA, rbcL, tufA, and petA) DNA markers from 99 E. huxleyi and 44 G. oceanica strains, we conducted a multigene/multistrain survey to compare the suitability of different markers for resolving phylogenetic patterns within and between these two morpho-species. The nuclear genes tested did not provide sufficient resolution to discriminate between the two morpho-species that diverged only 291Kya. Typical patterns of incomplete lineage sorting were generated in phylogenetic analyses using plastidial genes. In contrast, full morpho-species delineation was achieved with mitochondrial markers and common intra-morpho-species phylogenetic patterns were observed despite differing rates of DNA substitution. Mitochondrial genes are thus promising barcodes for distinguishing these coccolithophore morpho-species, in particular in the context of environmental monitoring. © 2013 Phycological Society of America.

  9. Seasonal variability of the carbonate system and coccolithophore Emiliania huxleyi at a Scottish Coastal Observatory monitoring site

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    León, Pablo; Walsham, Pam; Bresnan, Eileen; Hartman, Susan E.; Hughes, Sarah; Mackenzie, Kevin; Webster, Lynda

    2018-03-01

    Lack of information about carbonate chemistry in inshore waters is a 'knowledge gap' in assessing the impacts of changing carbonate chemistry on the marine environment. Assessing the response of calcifying phytoplankton to this changing carbonate chemistry requires a greater understanding of temporal variation. This study provides a description of the variability of carbonate parameters at a monitoring site in the eastern coast of Scotland. Four-years of monthly data were analysed to assess the diversity, abundance and morphometrics of coccolithophores in relation to carbonate chemistry and environmental variables. The seasonality in carbonate parameters reflected the seasonal cycle in phytoplankton activity, with higher total alkalinity concentrations and pH and lower dissolved inorganic carbon concentrations during the growing season. The dominant coccolithophore at the site was Emiliania huxleyi which showed a clear seasonal pattern, being more abundant in mid-summer when warmer and nutrient-depleted conditions restricted the annual diatom bloom. This study revealed the presence of three morphotypes of E. huxleyi, type A, type A overcalcified (type AO) and type B, which were seasonally distributed throughout the year. The less calcified form was mainly observed in spring while heavily calcified morphotypes overlapped during summer. Autumn and winter months were dominated by the most calcified form (type AO). These results indicate that the seasonal pattern of E. huxleyi morphotypes was not related to the carbonate concentration at the site. This study reflects the strong interannual variability in carbonate chemistry and the complexity associated with coccolithophore calcification, and highlights the need of long-term data to understand the potential impact of ocean acidification on calcifying phytoplankton.

  10. Effect of CO2 on the properties and sinking velocity of aggregates of the coccolithophore Emiliania huxleyi

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    A. Engel

    2010-03-01

    Full Text Available Coccolithophores play an important role in organic matter export due to their production of the mineral calcite that can act as ballast. Recent studies indicated that calcification in coccolithophores may be affected by changes in seawater carbonate chemistry. We investigated the influence of CO2 on the aggregation and sinking behaviour of the coccolithophore Emiliania huxleyi (PML B92/11 during a laboratory experiment. The coccolithophores were grown under low (~180 μatm, medium (~380 μatm, and high (~750 μatm CO2 conditions. Aggregation of the cells was promoted using roller tables. Size and settling velocity of aggregates were determined during the incubation using video image analysis. Our results indicate that aggregate properties are sensitive to changes in the degree of ballasting, as evoked by ocean acidification. Average sinking velocity was highest for low CO2 aggregates (~1292 m d−1 that also had the highest particulate inorganic to particulate organic carbon (PIC/POC ratio. Lowest PIC/POC ratios and lowest sinking velocity (~366 m d−1 at comparable sizes were observed for aggregates of the high CO2 treatment. Aggregates of the high CO2 treatment showed a 4-fold lower excess density (~4.2×10−4 g cm−3 when compared to aggregates from the medium and low CO2 treatments (~1.7 g×10−3 cm−3. We also observed that more aggregates formed in the high CO2 treatment, and that those aggregates contained more bacteria than aggregates in the medium and low CO2 treatment. If applicable to the future ocean, our findings suggest that a CO2 induced reduction of the calcite content of aggregates could weaken the deep export of organic matter in the ocean, particularly in areas dominated by coccolithophores.

  11. Targeted sorting of single virus-infected cells of the coccolithophore Emiliania huxleyi.

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    Joaquín Martínez Martínez

    Full Text Available Discriminating infected from healthy cells is the first step to understanding the mechanisms and ecological implications of viral infection. We have developed a method for detecting, sorting, and performing molecular analysis of individual, infected cells of the important microalga Emiliania huxleyi, based on known physiological responses to viral infection. Of three fluorescent dyes tested, FM 1-43 (for detecting membrane blebbing gave the most unequivocal and earliest separation of cells. Furthermore, we were able to amplify the genomes of single infected cells using Multiple Displacement Amplification. This novel method to reliably discriminate infected from healthy cells in cultures will allow researchers to answer numerous questions regarding the mechanisms and implications of viral infection of E. huxleyi. The method may be transferable to other virus-host systems.

  12. Targeted sorting of single virus-infected cells of the coccolithophore Emiliania huxleyi.

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    Martínez Martínez, Joaquín; Poulton, Nicole J; Stepanauskas, Ramunas; Sieracki, Michael E; Wilson, William H

    2011-01-01

    Discriminating infected from healthy cells is the first step to understanding the mechanisms and ecological implications of viral infection. We have developed a method for detecting, sorting, and performing molecular analysis of individual, infected cells of the important microalga Emiliania huxleyi, based on known physiological responses to viral infection. Of three fluorescent dyes tested, FM 1-43 (for detecting membrane blebbing) gave the most unequivocal and earliest separation of cells. Furthermore, we were able to amplify the genomes of single infected cells using Multiple Displacement Amplification. This novel method to reliably discriminate infected from healthy cells in cultures will allow researchers to answer numerous questions regarding the mechanisms and implications of viral infection of E. huxleyi. The method may be transferable to other virus-host systems.

  13. Fungal-type carbohydrate binding modules from the coccolithophore Emiliania huxleyi show binding affinity to cellulose and chitin.

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    Rooijakkers, Bart J M; Ikonen, Martina S; Linder, Markus B

    2018-01-01

    Six fungal-type cellulose binding domains were found in the genome of the coccolithophore Emiliania huxleyi and cloned and expressed in Escherichia coli. Sequence comparison indicate high similarity to fungal cellulose binding domains, raising the question of why these domains exist in coccolithophores. The proteins were tested for binding with cellulose and chitin as ligands, which resulted in the identification of two functional carbohydrate binding modules: EHUX2 and EHUX4. Compared to benchmark fungal cellulose binding domain Cel7A-CBM1 from Trichoderma reesei, these proteins showed slightly lower binding to birch and bacterial cellulose, but were more efficient chitin binders. Finally, a set of cellulose binding domains was created based on the shuffling of one well-functioning and one non-functional domain. These were characterized in order to get more information of the binding domain's sequence-function relationship, indicating characteristic differences between the molecular basis of cellulose versus chitin recognition. As previous reports have showed the presence of cellulose in coccoliths and here we find functional cellulose binding modules, a possible connection is discussed.

  14. Fungal-type carbohydrate binding modules from the coccolithophore Emiliania huxleyi show binding affinity to cellulose and chitin.

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    Bart J M Rooijakkers

    Full Text Available Six fungal-type cellulose binding domains were found in the genome of the coccolithophore Emiliania huxleyi and cloned and expressed in Escherichia coli. Sequence comparison indicate high similarity to fungal cellulose binding domains, raising the question of why these domains exist in coccolithophores. The proteins were tested for binding with cellulose and chitin as ligands, which resulted in the identification of two functional carbohydrate binding modules: EHUX2 and EHUX4. Compared to benchmark fungal cellulose binding domain Cel7A-CBM1 from Trichoderma reesei, these proteins showed slightly lower binding to birch and bacterial cellulose, but were more efficient chitin binders. Finally, a set of cellulose binding domains was created based on the shuffling of one well-functioning and one non-functional domain. These were characterized in order to get more information of the binding domain's sequence-function relationship, indicating characteristic differences between the molecular basis of cellulose versus chitin recognition. As previous reports have showed the presence of cellulose in coccoliths and here we find functional cellulose binding modules, a possible connection is discussed.

  15. Acidification, not carbonation, is the major regulator of carbon fluxes in the coccolithophore Emiliania huxleyi.

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    Kottmeier, Dorothee M; Rokitta, Sebastian D; Rost, Björn

    2016-07-01

    A combined increase in seawater [CO2 ] and [H(+) ] was recently shown to induce a shift from photosynthetic HCO3 (-) to CO2 uptake in Emiliania huxleyi. This shift occurred within minutes, whereas acclimation to ocean acidification (OA) did not affect the carbon source. To identify the driver of this shift, we exposed low- and high-light acclimated E. huxleyi to a matrix of two levels of dissolved inorganic carbon (1400, 2800 μmol kg(-1) ) and pH (8.15, 7.85) and directly measured cellular O2 , CO2 and HCO3 (-) fluxes under these conditions. Exposure to increased [CO2 ] had little effect on the photosynthetic fluxes, whereas increased [H(+) ] led to a significant decline in HCO3 (-) uptake. Low-light acclimated cells overcompensated for the inhibition of HCO3 (-) uptake by increasing CO2 uptake. High-light acclimated cells, relying on higher proportions of HCO3 (-) uptake, could not increase CO2 uptake and photosynthetic O2 evolution consequently became carbon-limited. These regulations indicate that OA responses in photosynthesis are caused by [H(+) ] rather than by [CO2 ]. The impaired HCO3 (-) uptake also provides a mechanistic explanation for lowered calcification under OA. Moreover, it explains the OA-dependent decrease in photosynthesis observed in high-light grown phytoplankton. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

  16. Quantitative Analysis of Carbon Flow into Photosynthetic Products Functioning as Carbon Storage in the Marine Coccolithophore, Emiliania huxleyi.

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    Tsuji, Yoshinori; Yamazaki, Masatoshi; Suzuki, Iwane; Shiraiwa, Yoshihiro

    2015-08-01

    The bloom-forming coccolithophore Emiliania huxleyi (Haptophyta) is a dominant marine phytoplankton, cells of which are covered with calcareous plates (coccoliths). E. huxleyi produces unique lipids of C37-C40 long-chain ketones (alkenones) with two to four trans-unsaturated bonds, β-glucan (but not α-glucan) and acid polysaccharide (AP) associated with the morphogenesis of CaCO3 crystals in coccoliths. Despite such unique features, there is no detailed information on the patterns of carbon allocation into these compounds. Therefore, we performed quantitative estimation of carbon flow into various macromolecular products by conducting (14)C-radiotracer experiments using NaH(14)CO3 as a substrate. Photosynthetic (14)C incorporation into low molecular-mass compounds (LMC), extracellular AP, alkenones, and total lipids except alkenones was estimated to be 35, 13, 17, and 25 % of total (14)C fixation in logarithmic growth phase cells and 33, 19, 18, and 18 % in stationary growth phase cells, respectively. However, less than 1 % of (14)C was incorporated into β-glucan in both cells. (14)C-mannitol occupied ca. 5 % of total fixed (14)C as the most dominant LMC product. Levels of all (14)C compounds decreased in the dark. Therefore, alkenones and LMC (including mannitol), but not β-glucan, function in carbon/energy storage in E. huxleyi, irrespective of the growth phase. Compared with other algae, the low carbon flux into β-glucan is a unique feature of carbon metabolism in E. huxelyi.

  17. Intraspecific Differences in Biogeochemical Responses to Thermal Change in the Coccolithophore Emiliania huxleyi.

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    Paul G Matson

    Full Text Available 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. In this study, we investigated strain-specific responses to temperature in terms of morphology, carbon production, and carbonate mineralogy using a combination of microscopy, elemental analysis, flow cytometry, and nuclear magnetic resonance. Two strains of the cosmopolitan coccolithophore E. huxleyi isolated from different regions (subtropical, CCMP371; temperate, CCMP3266 were cultured under a range of temperature conditions (10°C, 15°C, and 20°C using batch cultures and sampled during both exponential and stationary growth. Results for both strains showed that growth rates decreased at lower temperatures while coccosphere size increased. Between 15°C and 20°C, both strains produced similar amounts of total carbon, but differed in allocation of that carbon between particulate inorganic carbon (PIC and particulate organic carbon (POC, though temperature effects were not detected. Between 10°C and 20°C, temperature effects on daily production of PIC and POC, as well as the cellular quota of POC were detected in CCMP3266. Strain-specific differences in coccolith shedding rates were found during exponential growth. In addition, daily shedding rates were negatively related to temperature in CCMP371 but not in CCMP3266. Despite differences in rates of particulate inorganic carbon production, both strains were found to produce coccoliths composed entirely of pure calcite, as established by solid-state 13C and 43Ca NMR and X-ray diffraction measurements. These results highlight the

  18. Dissecting the impact of CO2 and pH on the mechanisms of photosynthesis and calcification in the coccolithophore Emiliania huxleyi.

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    Bach, Lennart T; Mackinder, Luke C M; Schulz, Kai G; Wheeler, Glen; Schroeder, Declan C; Brownlee, Colin; Riebesell, Ulf

    2013-07-01

    Coccolithophores are important calcifying phytoplankton predicted to be impacted by changes in ocean carbonate chemistry caused by the absorption of anthropogenic CO2 . However, it is difficult to disentangle the effects of the simultaneously changing carbonate system parameters (CO2 , bicarbonate, carbonate and protons) on the physiological responses to elevated CO2 . Here, we adopted a multifactorial approach at constant pH or CO2 whilst varying dissolved inorganic carbon (DIC) to determine physiological and transcriptional responses to individual carbonate system parameters. We show that Emiliania huxleyi is sensitive to low CO2 (growth and photosynthesis) and low bicarbonate (calcification) as well as low pH beyond a limited tolerance range, but is much less sensitive to elevated CO2 and bicarbonate. Multiple up-regulated genes at low DIC bear the hallmarks of a carbon-concentrating mechanism (CCM) that is responsive to CO2 and bicarbonate but not to pH. Emiliania huxleyi appears to have evolved mechanisms to respond to limiting rather than elevated CO2 . Calcification does not function as a CCM, but is inhibited at low DIC to allow the redistribution of DIC from calcification to photosynthesis. The presented data provides a significant step in understanding how E. huxleyi will respond to changing carbonate chemistry at a cellular level. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

  19. Difference in physiological responses of growth, photosynthesis and calcification of the coccolithophore Emiliania huxleyi to acidification by acid and CO2 enrichment.

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    Fukuda, Shin-Ya; Suzuki, Yurina; Shiraiwa, Yoshihiro

    2014-09-01

    Ocean acidification, one of the great global environmental issues at present, is expected to result in serious damage on marine calcareous organisms such as corals and calcifying algae, which potentially release huge amounts of CO2 from the ocean to the atmosphere. The coccolithophore, Emiliania huxleyi (Haptophyceae), which frequently produces blooms, has greatly contributed to the biological CO2 pump. This study was aimed at analyzing effects of how E. huxleyi responds to acidification. Acidification was performed by two methods, namely by just adding HCl under bubbling ordinary air at 8.2-8.4, 7.6-7.8 and 7.1-7.3 (acidification by HCl) and by bubbling with ordinary air or with increased CO2 concentration such as 406, 816 and 1,192 ppm that maintained pH of the medium at 8.0-8.3, 7.6-7.9 and 7.5-7.7 (acidification by CO2 enrichment). As a result, cell growth and cellular calcification of E. huxleyi were strongly damaged by acidification by HCl, but not by acidification by CO2 enrichment. The activities of photosystems such as F v/F m and ϕPSII were not affected by any acidification conditions while photosynthetic O2 evolution was slightly stimulated. A (45)Ca-radiotracer experiment revealed that Ca(2+)-uptake was strongly suppressed by acidification with HCl. This suppression recovered after increasing the dissolved inorganic carbon (DIC) concentration and further stimulated by an additional increase in DIC concentration. The production of storage and coccolith polysaccharides was increased by acidification by HCl and also highly stimulated by acidification with CO2 enrichment. The present study clearly showed that the coccolithophore, E. huxleyi, has an ability to respond positively to acidification with CO2 enrichment, but not just acidification.

  20. NEW EVIDENCE FOR MORPHOLOGICAL AND GENETIC VARIATION IN THE COSMOPOLITAN COCCOLITHOPHORE EMILIANIA HUXLEYI (PRYMNESIOPHYCEAE) FROM THE COX1b-ATP4 GENES(1).

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    Hagino, Kyoko; Bendif, El Mahdi; Young, Jeremy R; Kogame, Kazuhiro; Probert, Ian; Takano, Yoshihito; Horiguchi, Takeo; de Vargas, Colomban; Okada, Hisatake

    2011-10-01

    Emiliania huxleyi (Lohmann) W. W. Hay et H. Mohler is a cosmopolitan coccolithophore occurring from tropical to subpolar waters and exhibiting variations in morphology of coccoliths possibly related to environmental conditions. We examined morphological characters of coccoliths and partial mitochondrial sequences of the cytochrome oxidase 1b (cox1b) through adenosine triphosphate synthase 4 (atp4) genes of 39 clonal E. huxleyi strains from the Atlantic and Pacific Oceans, Mediterranean Sea, and their adjacent seas. Based on the morphological study of culture strains by SEM, Type O, a new morphotype characterized by coccoliths with an open central area, was separated from existing morphotypes A, B, B/C, C, R, and var. corona, characterized by coccoliths with central area elements. Molecular phylogenetic studies revealed that E. huxleyi consists of at least two mitochondrial sequence groups with different temperature preferences/tolerances: a cool-water group occurring in subarctic North Atlantic and Pacific and a warm-water group occurring in the subtropical Atlantic and Pacific and in the Mediterranean Sea. © 2011 Phycological Society of America.

  1. Change in coccolith size and morphology due to response to temperature and salinity in coccolithophore Emiliania huxleyi (Haptophyta) isolated from the Bering and Chukchi seas

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    Saruwatari, Kazuko; Satoh, Manami; Harada, Naomi; Suzuki, Iwane; Shiraiwa, Yoshihiro

    2016-05-01

    Strains of the coccolithophore Emiliania huxleyi (Haptophyta) collected from the subarctic North Pacific and Arctic oceans in 2010 were established as clone cultures and have been maintained in the laboratory at 15 °C and 32 ‰ salinity. To study the physiological responses of coccolith formation to changes in temperature and salinity, growth experiments and morphometric investigations were performed on two strains, namely MR57N isolated from the northern Bering Sea and MR70N at the Chukchi Sea. This is the first report of a detailed morphometric and morphological investigation of Arctic Ocean coccolithophore strains. The specific growth rates at the logarithmic growth phases in both strains markedly increased as temperature was elevated from 5 to 20 °C, although coccolith productivity (estimated as the percentage of calcified cells) was similar at 10-20 % at all temperatures. On the other hand, the specific growth rate of MR70N was affected less by changes in salinity in the range 26-35 ‰, but the proportion of calcified cells decreased at high and low salinities. According to scanning electron microscopy (SEM) observations, coccolith morphotypes can be categorized into Type B/C on the basis of their biometrical parameters. The central area elements of coccoliths varied from thin lath type to well-calcified lath type when temperature was increased or salinity was decreased, and coccolith size decreased simultaneously. Coccolithophore cell size also decreased with increasing temperature, although the variation in cell size was slightly greater at the lower salinity level. This indicates that subarctic and arctic coccolithophore strains can survive in a wide range of seawater temperatures and at lower salinities with change in their morphology. Because all coccolith biometric parameters followed the scaling law, the decrease in coccolith size was caused simply by the reduced calcification. Taken together, our results suggest that calcification productivity may

  2. Morphological switch to a resistant subpopulation in response to viral infection in the bloom-forming coccolithophore Emiliania huxleyi.

    Science.gov (United States)

    Frada, Miguel José; Rosenwasser, Shilo; Ben-Dor, Shifra; Shemi, Adva; Sabanay, Helena; Vardi, Assaf

    2017-12-01

    Recognizing the life cycle of an organism is key to understanding its biology and ecological impact. Emiliania huxleyi is a cosmopolitan marine microalga, which displays a poorly understood biphasic sexual life cycle comprised of a calcified diploid phase and a morphologically distinct biflagellate haploid phase. Diploid cells (2N) form large-scale blooms in the oceans, which are routinely terminated by specific lytic viruses (EhV). In contrast, haploid cells (1N) are resistant to EhV. Further evidence indicates that 1N cells may be produced during viral infection. A shift in morphology, driven by meiosis, could therefore constitute a mechanism for E. huxleyi cells to escape from EhV during blooms. This process has been metaphorically coined the 'Cheshire Cat' (CC) strategy. We tested this model in two E. huxleyi strains using a detailed assessment of morphological and ploidy-level variations as well as expression of gene markers for meiosis and the flagellate phenotype. We showed that following the CC model, production of resistant cells was triggered during infection. This led to the rise of a new subpopulation of cells in the two strains that morphologically resembled haploid cells and were resistant to EhV. However, ploidy-level analyses indicated that the new resistant cells were diploid or aneuploid. Thus, the CC strategy in E. huxleyi appears to be a life-phase switch mechanism involving morphological remodeling that is decoupled from meiosis. Our results highlight the adaptive significance of morphological plasticity mediating complex host-virus interactions in marine phytoplankton.

  3. Dynamics of transparent exopolymer particle (TEP) production and aggregation during viral infection of the coccolithophore, Emiliania huxleyi.

    Science.gov (United States)

    Nissimov, Jozef I; Vandzura, Rebecca; Johns, Christopher T; Natale, Frank; Haramaty, Liti; Bidle, Kay D

    2018-06-19

    Emiliania huxleyi produces calcium carbonate (CaCO 3 ) coccoliths and transparent exopolymer particles (TEP), sticky, acidic carbohydrates that facilitate aggregation. E. huxleyi's extensive oceanic blooms are often terminated by coccolithoviruses (EhVs) with the transport of cellular debris and associated particulate organic carbon (POC) to depth being facilitated by TEP-bound "marine snow" aggregates. The dynamics of TEP production and particle aggregation in response to EhV infection are poorly understood. Using flow cytometry, spectrophotometry, and FlowCam visualization of alcian blue (AB)-stained aggregates, we assessed TEP production and the size spectrum of aggregates for E. huxleyi possessing different degrees of calcification and cellular CaCO 3 :POC mass ratios, when challenged with two EhVs (EhV207 and EhV99B1). FlowCam imaging also qualitatively assessed the relative amount of AB-stainable TEP (i.e. blue:red ratio of each particle). We show significant increases in TEP during early phase EhV207-infection (∼24 hours) of calcifying strains and a shift towards large aggregates following EhV99B1-infection. We also observed the formation of large aggregates with low blue:red ratios, suggesting that other exopolymer substances contribute towards aggregation. Our findings show the potential for virus infection and the associated response of their hosts to impact carbon flux dynamics and provide incentive to explore these dynamics in natural populations. This article is protected by copyright. All rights reserved. © 2018 Society for Applied Microbiology and John Wiley & Sons Ltd.

  4. Interacting effects of ocean acidification and warming on growth and DMS-production in the haptophyte coccolithophore Emiliania huxleyi.

    Science.gov (United States)

    Arnold, Hayley E; Kerrison, Philip; Steinke, Michael

    2013-04-01

    The production of the marine trace gas dimethyl sulfide (DMS) provides 90% of the marine biogenic sulfur in the atmosphere where it affects cloud formation and climate. The effects of increasing anthropogenic CO2 and the resulting warming and ocean acidification on trace gas production in the oceans are poorly understood. Here we report the first measurements of DMS-production and data on growth, DMSP and DMS concentrations in pH-stated cultures of the phytoplankton haptophyte Emiliania huxleyi. Four different environmental conditions were tested: ambient, elevated CO2 (+CO2 ), elevated temperature (+T) and elevated temperature and CO2 (+TCO2 ). In comparison to the ambient treatment, average DMS production was about 50% lower in the +CO2 treatment. Importantly, temperature had a strong effect on DMS production and the impacts outweighed the effects of a decrease in pH. As a result, the +T and +TCO2 treatments showed significantly higher DMS production of 36.2 ± 2.58 and 31.5 ± 4.66 μmol L(-1) cell volume (CV) h(-1) in comparison with the +CO2 treatment (14.9 ± 4.20 μmol L(-1) CV h(-1) ). As the cultures were aerated with an air/CO2 mixture, DMS was effectively removed from the incubation bottles so that concentration remained relatively low (3.6-6.1 mmol L(-1) CV). Intracellular DMSP has been shown to increase in E. huxleyi as a result of elevated temperature and/or elevated CO2 and our results are in agreement with this finding: the ambient and +CO2 treatments showed 125 ± 20.4 and 162 ± 27.7 mmol L(-1) CV, whereas +T and +TCO2 showed significantly increased intracellular DMSP concentrations of 195 ± 15.8 and 211 ± 28.2 mmol L(-1) CV respectively. Growth was unaffected by the treatments, but cell diameter decreased significantly under elevated temperature. These results indicate that DMS production is sensitive to CO2 and temperature in E. huxleyi. Hence, global environmental change that manifests in ocean acidification and warming may not result in

  5. Change in coccolith morphology by responding to temperature and salinity in coccolithophore Emiliania huxleyi (Haptophyta) isolated from the Bering and Chukchi Seas

    Science.gov (United States)

    Saruwatari, K.; Satoh, M.; Harada, N.; Suzuki, I.; Shiraiwa, Y.

    2015-11-01

    Strains of the coccolithophore Emiliania huxleyi (Haptophyta) collected from the subarctic North Pacific and Arctic Oceans during the R/V MIRAI cruise in 2010 (MR10-05) were established as clone cultures and have been maintained in the laboratory at 15 °C and 32 ‰ salinity. To study the physiological responses of coccolith formation to changes in temperature and salinity, growth experiments and morphometric investigations were performed on two strains of MR57N isolated from the northern Bering Sea (56°58' N, 167°11' W) and MR70N at the Chukchi Sea (69°99' N, 168° W). This is the first report of a detailed morphometric and morphological investigation of Arctic Ocean coccolithophore strains. The specific growth rates at the logarithmic growth phases in both strains markedly increased as temperature was elevated from 5 to 20 °C, although coccolith productivity (the percentage of calcified cells) was similar at 10-20 % at all temperatures. On the other hand, the specific growth rate of strain MR70N was affected less by changes in salinity in the range 26-35 ‰, but the proportion of calcified cells decreased at high and low salinities. According to scanning electron microscopy (SEM) observations, coccolith morphotypes can be categorized into Type B/C on the basis of their biometrical parameters, such as length of the distal shield (LDS), length of the inner central area (LICA), and the thickness of distal shield elements. The central area elements of coccoliths varied from grilled type to closed type when temperature was increased or salinity was decreased, and coccolith size decreased simultaneously. Coccolithophore cell size also decreased with increasing temperature, although the variation in cell size was slightly greater at the lower salinity level. This indicates that subarctic and arctic coccolithophore strains can survive in a wide range of seawater temperatures and at lower salinities due to their marked morphometric adaptation ability. Because all

  6. Over-calcified forms of the coccolithophore Emiliania huxleyi in high-CO2 waters are not preadapted to ocean acidification

    Science.gov (United States)

    von Dassow, Peter; Díaz-Rosas, Francisco; Mahdi Bendif, El; Gaitán-Espitia, Juan-Diego; Mella-Flores, Daniella; Rokitta, Sebastian; John, Uwe; Torres, Rodrigo

    2018-03-01

    Marine multicellular organisms inhabiting waters with natural high fluctuations in pH appear more tolerant to acidification than conspecifics occurring in nearby stable waters, suggesting that environments of fluctuating pH hold genetic reservoirs for adaptation of key groups to ocean acidification (OA). The abundant and cosmopolitan calcifying phytoplankton Emiliania huxleyi exhibits a range of morphotypes with varying degrees of coccolith mineralization. We show that E. huxleyi populations in the naturally acidified upwelling waters of the eastern South Pacific, where pH drops below 7.8 as is predicted for the global surface ocean by the year 2100, are dominated by exceptionally over-calcified morphotypes whose distal coccolith shield can be almost solid calcite. Shifts in morphotype composition of E. huxleyi populations correlate with changes in carbonate system parameters. We tested if these correlations indicate that the hyper-calcified morphotype is adapted to OA. In experimental exposures to present-day vs. future pCO2 (400 vs. 1200 µatm), the over-calcified morphotypes showed the same growth inhibition (-29.1±6.3 %) as moderately calcified morphotypes isolated from non-acidified water (-30.7±8.8 %). Under the high-CO2-low-pH condition, production rates of particulate organic carbon (POC) increased, while production rates of particulate inorganic carbon (PIC) were maintained or decreased slightly (but not significantly), leading to lowered PIC / POC ratios in all strains. There were no consistent correlations of response intensity with strain origin. The high-CO2-low-pH condition affected coccolith morphology equally or more strongly in over-calcified strains compared to moderately calcified strains. High-CO2-low-pH conditions appear not to directly select for exceptionally over-calcified morphotypes over other morphotypes, but perhaps indirectly by ecologically correlated factors. More generally, these results suggest that oceanic planktonic

  7. Optimal Mutagen Doses for Emiliania huxleyi

    Science.gov (United States)

    Byrne, P.

    2016-02-01

    Emiliania huxleyi (E. huxleyi) is one of the most prominent coccolithophores. Given favorable conditions, E. huxleyi blooms can reach sizes exceeding 100,000km2, with densities of 107 cells per L (Olson & Strom 2002). With increasing demand and limited supply of fossil fuels, it has become increasingly popular to look toward alternative renewable fuel sources. E. Huxleyi store energy predominately as uniquely structured polyunsaturated long chain (C37-39) alkenes, alkenones and alkenoates (abbreviated as PULCAs) (Eltgroth et al 2005). Unlike the stored energy of macroalgae and higher order plants, triacylglycerols (TAGs), PULCAs provide a similar composition to native petroleum crude oils (Yamane 2013), which offers a more cost effective and higher yielding extraction process (Wu et al 1999). A number of factors have been shown to influence the alkenone content of E. huxleyi, such as nitrogen deficiency, phosphate limitation (Li et al 2014), and temperature (Shiraiwa et al 2005). For these reasons E. huxleyi has the potential to be an attractive system for algal biofuel. The broad and long-term objective of our research is to elucidate the alkenone biosynthesis pathway in E. Huxleyi, using random mutagenesis techniques. We propose to use UV light and methylmethane sulfonate (MMS) to create a mutant population, from which clones unable to synthesize alkenones will be selected. Identifying genes whose specific mutations underlie the loss-of-function phenotype will then reveal genes of interest. The aim of this research was to determine the UV and MMS dose response rates for E. huxleyi to ascertain optimal doses defined as a 50% survival rate for each of the two mutagens. Preliminary data indicate that E. huxleyi appear to be highly sensitive to UV mutagenesis, with an LD50 of 0.57mJ/cm2 for the calcifying strain M217 and 0.96mJ/cm2 for the non-calcifying strain CCMP1516. Both calcifying and non-calcifying strains exhibit similar LD50 values for MMS at 1-2% (v/v).

  8. The Mechanisms of Calcification in Coccolithophores - The molecular basis of calcium and inorganic carbon transport in Emiliania huxleyi

    OpenAIRE

    Mackinder, Luke

    2012-01-01

    Coccolithophores are calcifying marine phytoplankton that through the fixation of inorganic carbon into calcite and particulate organic carbon play a fundamental role in global carbon cycles. As the CO2 concentration of the surface ocean increases through the anthropogenic release of CO2 by burning fossil fuels both a decrease in pH (ocean acidification) and a increase in dissolved inorganic carbon (ocean carbonation) are taking place. To understand the impact of these ocean changes on coccol...

  9. Response of the coccolithophore Emiliania huxleyi to increased CO2 and Fe availability within the plankton food web

    OpenAIRE

    Lorenzo Garrido, María del Rosario

    2016-01-01

    Ocean acidification due to increased CO2 emissions derived from anthropogenic activities is affecting marine ecosystems at an unprecedented rate (IPCC 2013). Ocean acidification has the potential to affect the physiological processes due to increasing CO2 levels and lower pH (Riebesell & Tortell 2011). Ocean acidification also impacts trace metal solubility and speciation. Among all trace metals, Fe is the most essential for biological functions of phytoplankton. Coccolithophores is one of...

  10. Dynamics and genotypic composition of Emiliania huxleyi and their co-occurring viruses during a coccolithophore bloom in the North Sea.

    Science.gov (United States)

    Martínez, Joaquín Martínez; Schroeder, Declan C; Wilson, William H

    2012-08-01

    We studied the temporal succession of vertical profiles of Emiliania huxleyi and their specific viruses (EhVs) during the progression of a natural phytoplankton bloom in the North Sea in June 1999. Genotypic richness was assessed by exploiting the variations in a gene encoding a protein with calcium-binding motifs (GPA) for E. huxleyi and in the viral major capsid protein gene for EhVs. Using denaturing gradient gel electrophoresis and sequencing analysis, we showed at least three different E. huxleyi and EhV genotypic profiles during the period of study, revealing a complex, and changing assemblage at the molecular level. Our results also indicate that the dynamics of EhV genotypes reflect fluctuations in abundance of potential E. huxleyi host cells. The presence and concentration of specific EhVs in the area prior to the bloom, or EhVs transported into the area by different water masses, are significant factors affecting the structure and intraspecific succession of E. huxleyi during the phytoplankton bloom. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  11. Dynamic energy budget modeling reveals the potential of future growth and calcification for the coccolithophore Emiliania huxleyi in an acidified ocean.

    Science.gov (United States)

    Muller, Erik B; Nisbet, Roger M

    2014-06-01

    Ocean acidification is likely to impact the calcification potential of marine organisms. In part due to the covarying nature of the ocean carbonate system components, including pH and CO2 and CO3(2-) levels, it remains largely unclear how each of these components may affect calcification rates quantitatively. We develop a process-based bioenergetic model that explains how several components of the ocean carbonate system collectively affect growth and calcification rates in Emiliania huxleyi, which plays a major role in marine primary production and biogeochemical carbon cycling. The model predicts that under the IPCC A2 emission scenario, its growth and calcification potential will have decreased by the end of the century, although those reductions are relatively modest. We anticipate that our model will be relevant for many other marine calcifying organisms, and that it can be used to improve our understanding of the impact of climate change on marine systems. © 2014 John Wiley & Sons Ltd.

  12. Phosphorus limitation and heat stress decrease calcification in Emiliania huxleyi

    Science.gov (United States)

    Gerecht, Andrea C.; Šupraha, Luka; Langer, Gerald; Henderiks, Jorijntje

    2018-02-01

    Calcifying haptophytes (coccolithophores) sequester carbon in the form of organic and inorganic cellular components (coccoliths). We examined the effect of phosphorus (P) limitation and heat stress on particulate organic and inorganic carbon (calcite) production in the coccolithophore Emiliania huxleyi. Both environmental stressors are related to rising CO2 levels and affect carbon production in marine microalgae, which in turn impacts biogeochemical cycling. Using semi-continuous cultures, we show that P limitation and heat stress decrease the calcification rate in E. huxleyi. However, using batch cultures, we show that different culturing approaches (batch versus semi-continuous) induce different physiologies. This affects the ratio of particulate inorganic (PIC) to organic carbon (POC) and complicates general predictions on the effect of P limitation on the PIC  /  POC ratio. We found heat stress to increase P requirements in E. huxleyi, possibly leading to lower standing stocks in a warmer ocean, especially if this is linked to lower nutrient input. In summary, the predicted rise in global temperature and resulting decrease in nutrient availability may decrease CO2 sequestration by E. huxleyi through lower overall carbon production. Additionally, the export of carbon may be diminished by a decrease in calcification and a weaker coccolith ballasting effect.

  13. Phosphorus limitation and heat stress decrease calcification in Emiliania huxleyi

    Directory of Open Access Journals (Sweden)

    A. C. Gerecht

    2018-02-01

    Full Text Available Calcifying haptophytes (coccolithophores sequester carbon in the form of organic and inorganic cellular components (coccoliths. We examined the effect of phosphorus (P limitation and heat stress on particulate organic and inorganic carbon (calcite production in the coccolithophore Emiliania huxleyi. Both environmental stressors are related to rising CO2 levels and affect carbon production in marine microalgae, which in turn impacts biogeochemical cycling. Using semi-continuous cultures, we show that P limitation and heat stress decrease the calcification rate in E. huxleyi. However, using batch cultures, we show that different culturing approaches (batch versus semi-continuous induce different physiologies. This affects the ratio of particulate inorganic (PIC to organic carbon (POC and complicates general predictions on the effect of P limitation on the PIC  ∕  POC ratio. We found heat stress to increase P requirements in E. huxleyi, possibly leading to lower standing stocks in a warmer ocean, especially if this is linked to lower nutrient input. In summary, the predicted rise in global temperature and resulting decrease in nutrient availability may decrease CO2 sequestration by E. huxleyi through lower overall carbon production. Additionally, the export of carbon may be diminished by a decrease in calcification and a weaker coccolith ballasting effect.

  14. An analytical model for light backscattering by coccoliths and coccospheres of Emiliania huxleyi.

    Science.gov (United States)

    Fournier, Georges; Neukermans, Griet

    2017-06-26

    We present an analytical model for light backscattering by coccoliths and coccolithophores of the marine calcifying phytoplankter Emiliania huxleyi. The model is based on the separation of the effects of diffraction, refraction, and reflection on scattering, a valid assumption for particle sizes typical of coccoliths and coccolithophores. Our model results match closely with results from an exact scattering code that uses complex particle geometry and our model also mimics well abrupt transitions in scattering magnitude. Finally, we apply our model to predict changes in the spectral backscattering coefficient during an Emiliania huxleyi bloom with results that closely match in situ measurements. Because our model captures the key features that control the light backscattering process, it can be generalized to coccoliths and coccolithophores of different morphologies which can be obtained from size-calibrated electron microphotographs. Matlab codes of this model are provided as supplementary material.

  15. Numerical cell model investigating cellular carbon fluxes in Emiliania huxleyi.

    Science.gov (United States)

    Holtz, Lena-Maria; Wolf-Gladrow, Dieter; Thoms, Silke

    2015-01-07

    Coccolithophores play a crucial role in the marine carbon cycle and thus it is interesting to know how they will respond to climate change. After several decades of research the interplay between intracellular processes and the marine carbonate system is still not well understood. On the basis of experimental findings given in literature, a numerical cell model is developed that describes inorganic carbon fluxes between seawater and the intracellular sites of calcite precipitation and photosynthetic carbon fixation. The implemented cell model consists of four compartments, for each of which the carbonate system is resolved individually. The four compartments are connected to each other via H(+), CO2, and HCO3(-) fluxes across the compartment-confining membranes. For CO2 accumulation around RubisCO, an energy-efficient carbon concentrating mechanism is proposed that relies on diffusive CO2 uptake. At low external CO2 concentrations and high light intensities, CO2 diffusion does not suffice to cover the carbon demand of photosynthesis and an additional uptake of external HCO3(-) becomes essential. The model is constrained by data of Emiliania huxleyi, the numerically most abundant coccolithophore species in the present-day ocean. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

  16. Phosphorus starvation induces membrane remodeling and recycling in Emiliania huxleyi.

    Science.gov (United States)

    Shemi, Adva; Schatz, Daniella; Fredricks, Helen F; Van Mooy, Benjamin A S; Porat, Ziv; Vardi, Assaf

    2016-08-01

    Nutrient availability is an important factor controlling phytoplankton productivity. Phytoplankton contribute c. 50% of the global photosynthesis and possess efficient acclimation mechanisms to cope with nutrient stress. We investigate the cellular response of the bloom-forming coccolithophore Emiliania huxleyi to phosphorus (P) scarcity, which is often a limiting factor in marine ecosystems. We combined mass spectrometry, fluorescence microscopy, transmission electron microscopy (TEM) and gene expression analyses in order to assess diverse cellular features in cells exposed to P limitation and recovery. Early starvation-induced substitution of phospholipids in the cells' membranes with galacto- and betaine lipids. Lipid remodeling was rapid and reversible upon P resupply. The PI3K inhibitor wortmannin reduced phospholipid substitution, suggesting a possible involvement of PI3K- signaling in this process. In addition, P limitation enhanced the formation and acidification of membrane vesicles in the cytoplasm. Intracellular vesicles may facilitate the recycling of cytoplasmic content, which is engulfed in the vesicles and delivered to the main vacuole. Long-term starvation was characterized by a profound increase in cell size and morphological alterations in cellular ultrastructure. This study provides cellular and molecular basis for future ecophysiological assessment of natural E. huxleyi populations in oligotrophic regions. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

  17. Reduced calcification decreases photoprotective capability in the coccolithophorid Emiliania huxleyi.

    Science.gov (United States)

    Xu, Kai; Gao, Kunshan

    2012-07-01

    Intracellular calcification of coccolithophores generates CO₂ and consumes additional energy for acquisition of calcium and bicarbonate ions; therefore, it may correlate with photoprotective processes by influencing the energetics. To address this hypothesis, a calcifying Emiliania huxleyi strain (CS-369) was grown semi-continuously at reduced (0.1 mM, LCa) and ambient Ca²⁺ concentrations (10 mM, HCa) for 150 d (>200 generations). The HCa-grown cells had higher photosynthetic and calcification rates and higher contents of Chl a and carotenoids compared with the naked (bearing no coccoliths) LCa-grown cells. When exposed to stressfull levels of photosynthetically active radiation (PAR), LCa-grown cells displayed lower photochemical yield and less efficient non-photochemical quenching (NPQ). When the LCa- or HCa-grown cells were inversely shifted to their counterpart medium, LCa to HCa transfer increased photosynthetic carbon fixation (P), calcification rate (C), the C/P ratio, NPQ and pigment contents, whereas those shifted from HCa to LCa exhibited the opposite effects. Increased NPQ, carotenoids and quantum yield were clearly linked with increased or sustained calcification in E. huxleyi. The calcification must have played a role in dissipating excessive energy or as an additional drainage of electrons absorbed by the photosynthetic antennae. This phenomenon was further supported by testing two non-calcifying strains, which showed insignificant changes in photosynthetic carbon fixation and NPQ when transferred to LCa conditions.

  18. Evidence for methane production by the marine algae Emiliania huxleyi

    Science.gov (United States)

    Lenhart, Katharina; Klintzsch, Thomas; Langer, Gerald; Nehrke, Gernot; Bunge, Michael; Schnell, Sylvia; Keppler, Frank

    2016-06-01

    Methane (CH4), an important greenhouse gas that affects radiation balance and consequently the earth's climate, still has uncertainties in its sinks and sources. The world's oceans are considered to be a source of CH4 to the atmosphere, although the biogeochemical processes involved in its formation are not fully understood. Several recent studies provided strong evidence of CH4 production in oxic marine and freshwaters, but its source is still a topic of debate. Studies of CH4 dynamics in surface waters of oceans and large lakes have concluded that pelagic CH4 supersaturation cannot be sustained either by lateral inputs from littoral or benthic inputs alone. However, regional and temporal oversaturation of surface waters occurs frequently. This comprises the observation of a CH4 oversaturating state within the surface mixed layer, sometimes also termed the "oceanic methane paradox". In this study we considered marine algae as a possible direct source of CH4. Therefore, the coccolithophore Emiliania huxleyi was grown under controlled laboratory conditions and supplemented with two 13C-labeled carbon substrates, namely bicarbonate and a position-specific 13C-labeled methionine (R-S-13CH3). The CH4 production was 0.7 µg particular organic carbon (POC) g-1 d-1, or 30 ng g-1 POC h-1. After supplementation of the cultures with the 13C-labeled substrate, the isotope label was observed in headspace CH4. Moreover, the absence of methanogenic archaea within the algal culture and the oxic conditions during CH4 formation suggest that the widespread marine algae Emiliania huxleyi might contribute to the observed spatially and temporally restricted CH4 oversaturation in ocean surface waters.

  19. Emiliania Huxleyi (Prymnesiophyceae): Nitrogen-metabolism genes and their expression in response to external nitrogen souces

    DEFF Research Database (Denmark)

    Bruhn, Annette; LaRoche, Julie; Richardson, Katherine

    2010-01-01

    The availability and composition of dissolved nitrogen in ocean waters are factors that influence species composition in natural phytoplankton communities. The same factors affect the ratio of organic to inorganic carbon incorporation in calcifying species, such as the coccolithophore Emiliania...... huxleyi (Lohman) W. W. Hay et H. Mohler. E. huxleyi has been shown to thrive on various nitrogen sources, including dissolved organic nitrogen. Nevertheless, assimilation of dissolved nitrogen under nitrogen-replete and -limited conditions is not well understood in this ecologically important species....... In this study, the complete amino acid sequences for three functional genes involved in nitrogen metabolism in E. huxleyi were identified: a putative formamidase, a glutamine synthetase (GSII family), and assimilatory nitrate reductase. Expression patterns of the three enzymes in cells grown on inorganic...

  20. Transcriptome analyses reveal differential gene expression patterns between the life-cycle stages of Emiliania Huxleyi (haptophyta) and reflect specialization to different ecological niches

    NARCIS (Netherlands)

    Rokitta, S.D.; Nooijer, L.J. de; Trimborn, S.; de Vargas, C.; Rost, B.; John, U.

    2011-01-01

    Coccolithophores, especially the abundant, cosmopolitan species Emiliania huxleyi (Lohmann) W. W. Hay et H. P. Mohler, are one of the main driving forces of the oceanic carbonate pump and contribute significantly to global carbon cycling, due to their ability to calcify. A recent study

  1. Optical Modeling of Spectral Backscattering and Remote Sensing Reflectance From Emiliania huxleyi Blooms

    Directory of Open Access Journals (Sweden)

    Griet Neukermans

    2018-05-01

    Full Text Available In this study we develop an analytical model for spectral backscattering and ocean color remote sensing of blooms of the calcifying phytoplankton species Emiliania huxleyi. Blooms of this coccolithophore species are ubiquitous and particularly intense in temperate and subpolar ocean waters. We first present significant improvements to our previous analytical light backscattering model for E. huxleyi coccoliths and coccospheres by accounting for the elliptical shape of coccoliths and the multi-layered coccosphere architecture observed on detailed imagery of E. huxleyi liths and coccospheres. Our new model also includes a size distribution function that closely matches measured E. huxleyi size distributions. The model for spectral backscattering is then implemented in an analytical radiative transfer model to evaluate the variability of spectral remote sensing reflectance with respect to changes in the size distribution of the coccoliths and during a hypothetical E. huxleyi bloom decay event in which coccospheres shed their liths. Our modeled remote sensing reflectance spectra reproduced well the bright milky turquoise coloring of the open ocean typically associated with the final stages of E. huxleyi blooms, with peak reflectance at a wavelength of 0.49 μm. Our results also show that the magnitude of backscattering from coccoliths when attached to or freed from the coccosphere does not differ much, contrary to what is commonly assumed, and that the spectral shape of backscattering is mainly controlled by the size and morphology of the coccoliths, suggesting that they may be estimated from spectral backscattering.

  2. Responses of the Emiliania huxleyi proteome to ocean acidification.

    Science.gov (United States)

    Jones, Bethan M; Iglesias-Rodriguez, M Debora; Skipp, Paul J; Edwards, Richard J; Greaves, Mervyn J; Young, Jeremy R; Elderfield, Henry; O'Connor, C David

    2013-01-01

    Ocean acidification due to rising atmospheric CO2 is expected to affect the physiology of important calcifying marine organisms, but the nature and magnitude of change is yet to be established. In coccolithophores, different species and strains display varying calcification responses to ocean acidification, but the underlying biochemical properties remain unknown. We employed an approach combining tandem mass-spectrometry with isobaric tagging (iTRAQ) and multiple database searching to identify proteins that were differentially expressed in cells of the marine coccolithophore species Emiliania huxleyi (strain NZEH) between two CO2 conditions: 395 (∼current day) and ∼1340 p.p.m.v. CO2. Cells exposed to the higher CO2 condition contained more cellular particulate inorganic carbon (CaCO3) and particulate organic nitrogen and carbon than those maintained in present-day conditions. These results are linked with the observation that cells grew slower under elevated CO2, indicating cell cycle disruption. Under high CO2 conditions, coccospheres were larger and cells possessed bigger coccoliths that did not show any signs of malformation compared to those from cells grown under present-day CO2 levels. No differences in calcification rate, particulate organic carbon production or cellular organic carbon: nitrogen ratios were observed. Results were not related to nutrient limitation or acclimation status of cells. At least 46 homologous protein groups from a variety of functional processes were quantified in these experiments, of which four (histones H2A, H3, H4 and a chloroplastic 30S ribosomal protein S7) showed down-regulation in all replicates exposed to high CO2, perhaps reflecting the decrease in growth rate. We present evidence of cellular stress responses but proteins associated with many key metabolic processes remained unaltered. Our results therefore suggest that this E. huxleyi strain possesses some acclimation mechanisms to tolerate future CO2 scenarios

  3. Draft genome sequence of the Coccolithovirus Emiliania huxleyi virus 203.

    Science.gov (United States)

    Nissimov, Jozef I; Worthy, Charlotte A; Rooks, Paul; Napier, Johnathan A; Kimmance, Susan A; Henn, Matthew R; Ogata, Hiroyuki; Allen, Michael J

    2011-12-01

    The Coccolithoviridae are a recently discovered group of viruses that infect the marine coccolithophorid Emiliania huxleyi. Emiliania huxleyi virus 203 (EhV-203) has a 160- to 180-nm-diameter icosahedral structure and a genome of approximately 400 kbp, consisting of 464 coding sequences (CDSs). Here we describe the genomic features of EhV-203 together with a draft genome sequence and its annotation, highlighting the homology and heterogeneity of this genome in comparison with the EhV-86 reference genome.

  4. Draft genome sequence of the coccolithovirus Emiliania huxleyi virus 202.

    Science.gov (United States)

    Nissimov, Jozef I; Worthy, Charlotte A; Rooks, Paul; Napier, Johnathan A; Kimmance, Susan A; Henn, Matthew R; Ogata, Hiroyuki; Allen, Michael J

    2012-02-01

    Emiliania huxleyi virus 202 (EhV-202) is a member of the Coccolithoviridae, a group of viruses that infect the marine coccolithophorid Emiliania huxleyi. EhV-202 has a 160- to 180-nm-diameter icosahedral structure and a genome of approximately 407 kbp, consisting of 485 coding sequences (CDSs). Here we describe the genomic features of EhV-202, together with a draft genome sequence and its annotation, highlighting the homology and heterogeneity of this genome in comparison with the EhV-86 reference genome.

  5. Physiological Responses of Oxyrrhis marina to the Altered Fatty Acid Composition of Virally Infected Emiliania huxleyi

    Science.gov (United States)

    Goode, A.; Fields, D.; Martinez-Martinez, J.

    2016-02-01

    Emiliania huxleyi is a coccolithophore that forms some of the largest phytoplankton blooms in the ocean. E. huxleyi abundance, distribution, and composition of essential fatty acids make them a key component in marine food webs. E. huxleyi-specific viruses have been shown to control the bloom duration and change the lipid composition of E. huxleyi cells. Alteration of essential fatty acids at the base of the food web may have downstream effects on trophic interactions. Oxyrrhis marina has been studied extensively, and is used as a micrograzer model organism. We investigated differential physiological responses of O. marina to a diet ( 100:1 prey:predator ratio) of virallyinfected versus uninfected E. huxleyi cells over a maximum 7-day period. Our results showed higher O. marina grazing rates on uninfected cells (phuxleyi cells. This suggests a higher nutritional value of infected cells and/or better assimilation by O. marina of infected cells' carbon. In the marine environment this would translate into larger carbon transport to higher trophic levels when blooms become infected.

  6. Influence of CO2 and nitrogen limitation on the coccolith volume of Emiliania huxleyi (Haptophyta

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    A. Talec

    2012-10-01

    Full Text Available Coccolithophores, a key phytoplankton group, are one of the most studied organisms regarding their physiological response to ocean acidification/carbonation. The biogenic production of calcareous coccoliths has made coccolithophores a promising group for paleoceanographic research aiming to reconstruct past environmental conditions. Recently, geochemical and morphological analyses of fossil coccoliths have gained increased interest in regard to changes in seawater carbonate chemistry. The cosmopolitan coccolithophore Emiliania huxleyi (Lohm. Hay and Mohler was cultured over a range of pCO2 levels in controlled laboratory experiments under nutrient replete and nitrogen limited conditions. Measurements of photosynthesis and calcification revealed, as previously published, an increase in particulate organic carbon production and a moderate decrease in calcification from ambient to elevated pCO2. The enhancement in particulate organic carbon production was accompanied by an increase in cell diameter. Changes in coccolith volume were best correlated with the coccosphere/cell diameter and no significant correlation was found between the coccolith volume and the particulate inorganic carbon production. The conducted experiments revealed that the coccolith volume of E. huxleyi is variable with aquatic CO2 concentration but its sensitivity is rather small in comparison with its sensitivity to nitrogen limitation. Comparing coccolith morphological and geometrical parameters like volume, mass and size to physiological parameters under controlled laboratory conditions is an important step to understand variations in fossil coccolith geometry.

  7. Temperature affects the morphology and calcification of Emiliania huxleyi strains

    Science.gov (United States)

    Rosas-Navarro, Anaid; Langer, Gerald; Ziveri, Patrizia

    2016-05-01

    The global warming debate has sparked an unprecedented interest in temperature effects on coccolithophores. The calcification response to temperature changes reported in the literature, however, is ambiguous. The two main sources of this ambiguity are putatively differences in experimental setup and strain specificity. In this study we therefore compare three strains isolated in the North Pacific under identical experimental conditions. Three strains of Emiliania huxleyi type A were grown under non-limiting nutrient and light conditions, at 10, 15, 20 and 25 °C. All three strains displayed similar growth rate versus temperature relationships, with an optimum at 20-25 °C. Elemental production (particulate inorganic carbon (PIC), particulate organic carbon (POC), total particulate nitrogen (TPN)), coccolith mass, coccolith size, and width of the tube element cycle were positively correlated with temperature over the sub-optimum to optimum temperature range. The correlation between PIC production and coccolith mass/size supports the notion that coccolith mass can be used as a proxy for PIC production in sediment samples. Increasing PIC production was significantly positively correlated with the percentage of incomplete coccoliths in one strain only. Generally, coccoliths were heavier when PIC production was higher. This shows that incompleteness of coccoliths is not due to time shortage at high PIC production. Sub-optimal growth temperatures lead to an increase in the percentage of malformed coccoliths in a strain-specific fashion. Since in total only six strains have been tested thus far, it is presently difficult to say whether sub-optimal temperature is an important factor causing malformations in the field. The most important parameter in biogeochemical terms, the PIC : POC ratio, shows a minimum at optimum growth temperature in all investigated strains. This clarifies the ambiguous picture featuring in the literature, i.e. discrepancies between PIC : POC

  8. Temperature-induced viral resistance in Emiliania huxleyi (Prymnesiophyceae).

    Science.gov (United States)

    Kendrick, B Jacob; DiTullio, Giacomo R; Cyronak, Tyler J; Fulton, James M; Van Mooy, Benjamin A S; Bidle, Kay D

    2014-01-01

    Annual Emiliania huxleyi blooms (along with other coccolithophorid species) play important roles in the global carbon and sulfur cycles. E. huxleyi blooms are routinely terminated by large, host-specific dsDNA viruses, (Emiliania huxleyi Viruses; EhVs), making these host-virus interactions a driving force behind their potential impact on global biogeochemical cycles. Given projected increases in sea surface temperature due to climate change, it is imperative to understand the effects of temperature on E. huxleyi's susceptibility to viral infection and its production of climatically active dimethylated sulfur species (DSS). Here we demonstrate that a 3°C increase in temperature induces EhV-resistant phenotypes in three E. huxleyi strains and that successful virus infection impacts DSS pool sizes. We also examined cellular polar lipids, given their documented roles in regulating host-virus interactions in this system, and propose that alterations to membrane-bound surface receptors are responsible for the observed temperature-induced resistance. Our findings have potential implications for global biogeochemical cycles in a warming climate and for deciphering the particular mechanism(s) by which some E. huxleyi strains exhibit viral resistance.

  9. Mingled Mortality: the Interplay Between Protist Grazing and Viral Lysis on Emiliania huxleyi Cell Fate

    Science.gov (United States)

    Harvey, E.; Bidle, K. D.; Johnson, M. D.

    2016-02-01

    The coccolithophore, Emiliania huxleyi plays a prominent role in global carbon cycling, as their calcite coccoliths account for a third of all oceanic calcite production. Mortality due to grazing by microzooplankton is the largest contributor to phytoplankton loss in the marine environment. However, viral infection of E. huxleyi is now thought to be as important as grazing pressure in contributing to its mortality. To understand the influence of viral infection on grazing dynamics, we examined the response of the dinoflagellate predator, Oxyrrhis marina to E. huxleyi infected with four different strains of the E. huxleyi virus (EhV). Grazing rate was significantly slower on E. huxleyi cultures that had been infected for 48 h compared to an uninfected control and this reduction in grazing rate was dependent on the strain identity of infecting EhVs. Additional experimentation indicated that grazing was the primary source of E. huxleyi loss ( 78-98%) during the first 24 h of exposure to both predator and virus. However, as viral infection progressed into the late lytic phase (48 h hour post infection), the relative contribution of grazing to total E. huxleyi mortality decreased ( 5-60%). These results suggest that mortality is partitioned along a gradient between predator-based consumption and virus-induced cell lysis, dependent on the timing of infection. Deciphering the relative importance and interactive nature of these alga-predator-viral interactions will help to elucidate the mechanisms that drive bulk measurements of phytoplankton loss, a necessary understanding to interpret and predict phytoplankton population dynamics and associated biogeochemical cycling.

  10. Expression of biomineralization-related ion transport genes in Emiliania huxleyi.

    Science.gov (United States)

    Mackinder, Luke; Wheeler, Glen; Schroeder, Declan; von Dassow, Peter; Riebesell, Ulf; Brownlee, Colin

    2011-12-01

    Biomineralization in the marine phytoplankton Emiliania huxleyi is a stringently controlled intracellular process. The molecular basis of coccolith production is still relatively unknown although its importance in global biogeochemical cycles and varying sensitivity to increased pCO₂ levels has been well documented. This study looks into the role of several candidate Ca²⁺, H⁺ and inorganic carbon transport genes in E. huxleyi, using quantitative reverse transcriptase PCR. Differential gene expression analysis was investigated in two isogenic pairs of calcifying and non-calcifying strains of E. huxleyi and cultures grown at various Ca²⁺ concentrations to alter calcite production. We show that calcification correlated to the consistent upregulation of a putative HCO₃⁻ transporter belonging to the solute carrier 4 (SLC4) family, a Ca²⁺/H⁺ exchanger belonging to the CAX family of exchangers and a vacuolar H⁺-ATPase. We also show that the coccolith-associated protein, GPA is downregulated in calcifying cells. The data provide strong evidence that these genes play key roles in E. huxleyi biomineralization. Based on the gene expression data and the current literature a working model for biomineralization-related ion transport in coccolithophores is presented. © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.

  11. Change in Emiliania huxleyi Virus Assemblage Diversity but Not in Host Genetic Composition during an Ocean Acidification Mesocosm Experiment.

    Science.gov (United States)

    Highfield, Andrea; Joint, Ian; Gilbert, Jack A; Crawfurd, Katharine J; Schroeder, Declan C

    2017-03-08

    Effects of elevated p CO₂ on Emiliania huxleyi genetic diversity and the viruses that infect E. huxleyi (EhVs) have been investigated in large volume enclosures in a Norwegian fjord. Triplicate enclosures were bubbled with air enriched with CO₂ to 760 ppmv whilst the other three enclosures were bubbled with air at ambient p CO₂; phytoplankton growth was initiated by the addition of nitrate and phosphate. E. huxleyi was the dominant coccolithophore in all enclosures, but no difference in genetic diversity, based on DGGE analysis using primers specific to the calcium binding protein gene ( gpa ) were detected in any of the treatments. Chlorophyll concentrations and primary production were lower in the three elevated p CO₂ treatments than in the ambient treatments. However, although coccolithophores numbers were reduced in two of the high- p CO₂ treatments; in the third, there was no suppression of coccolithophores numbers, which were very similar to the three ambient treatments. In contrast, there was considerable variation in genetic diversity in the EhVs, as determined by analysis of the major capsid protein ( mcp ) gene. EhV diversity was much lower in the high- p CO₂ treatment enclosure that did not show inhibition of E. huxleyi growth. Since virus infection is generally implicated as a major factor in terminating phytoplankton blooms, it is suggested that no study of the effect of ocean acidification in phytoplankton can be complete if it does not include an assessment of viruses.

  12. Genome variations associated with viral susceptibility and calcification in Emiliania huxleyi.

    Science.gov (United States)

    Kegel, Jessica U; John, Uwe; Valentin, Klaus; Frickenhaus, Stephan

    2013-01-01

    Emiliania huxleyi, a key player in the global carbon cycle is one of the best studied coccolithophores with respect to biogeochemical cycles, climatology, and host-virus interactions. Strains of E. huxleyi show phenotypic plasticity regarding growth behaviour, light-response, calcification, acidification, and virus susceptibility. This phenomenon is likely a consequence of genomic differences, or transcriptomic responses, to environmental conditions or threats such as viral infections. We used an E. huxleyi genome microarray based on the sequenced strain CCMP1516 (reference strain) to perform comparative genomic hybridizations (CGH) of 16 E. huxleyi strains of different geographic origin. We investigated the genomic diversity and plasticity and focused on the identification of genes related to virus susceptibility and coccolith production (calcification). Among the tested 31940 gene models a core genome of 14628 genes was identified by hybridization among 16 E. huxleyi strains. 224 probes were characterized as specific for the reference strain CCMP1516. Compared to the sequenced E. huxleyi strain CCMP1516 variation in gene content of up to 30 percent among strains was observed. Comparison of core and non-core transcripts sets in terms of annotated functions reveals a broad, almost equal functional coverage over all KOG-categories of both transcript sets within the whole annotated genome. Within the variable (non-core) genome we identified genes associated with virus susceptibility and calcification. Genes associated with virus susceptibility include a Bax inhibitor-1 protein, three LRR receptor-like protein kinases, and mitogen-activated protein kinase. Our list of transcripts associated with coccolith production will stimulate further research, e.g. by genetic manipulation. In particular, the V-type proton ATPase 16 kDa proteolipid subunit is proposed to be a plausible target gene for further calcification studies.

  13. A three-dimensional niche comparison of Emiliania huxleyi and Gephyrocapsa oceanica: reconciling observations with projections

    Directory of Open Access Journals (Sweden)

    N. A. Gafar

    2018-06-01

    Full Text Available Coccolithophore responses to changes in carbonate chemistry speciation such as CO2 and H+ are highly modulated by light intensity and temperature. Here, we fit an analytical equation, accounting for simultaneous changes in carbonate chemistry speciation, light and temperature, to published and original data for Emiliania huxleyi, and compare the projections with those for Gephyrocapsa oceanica. Based on our analysis, the two most common bloom-forming species in present-day coccolithophore communities appear to be adapted for a similar fundamental light niche but slightly different ones for temperature and CO2, with E. huxleyi having a tolerance to lower temperatures and higher CO2 levels than G. oceanica. Based on growth rates, a dominance of E. huxleyi over G. oceanica is projected below temperatures of 22 °C at current atmospheric CO2 levels. This is similar to a global surface sediment compilation of E. huxleyi and G. oceanica coccolith abundances suggesting temperature-dependent dominance shifts. For a future Representative Concentration Pathway (RCP 8.5 climate change scenario (1000 µatm fCO2, we project a CO2 driven niche contraction for G. oceanica to regions of even higher temperatures. However, the greater sensitivity of G. oceanica to increasing CO2 is partially mitigated by increasing temperatures. Finally, we compare satellite-derived particulate inorganic carbon estimates in the surface ocean with a recently proposed metric for potential coccolithophore success on the community level, i.e. the temperature-, light- and carbonate-chemistry-dependent CaCO3 production potential (CCPP. Based on E. huxleyi alone, as there was interestingly a better correlation than when in combination with G. oceanica, and excluding the Antarctic province from the analysis, we found a good correlation between CCPP and satellite-derived particulate inorganic carbon (PIC with an R2 of 0.73, p < 0.01 and a slope of 1.03 for austral winter

  14. The role of coccoliths in protecting Emiliania huxleyi against stressful light and UV radiation

    Science.gov (United States)

    Xu, Juntian; Bach, Lennart T.; Schulz, Kai G.; Zhao, Wenyan; Gao, Kunshan; Riebesell, Ulf

    2016-08-01

    Coccolithophores are a group of phytoplankton species which cover themselves with small scales (coccoliths) made of calcium carbonate (CaCO3). The reason why coccolithophores form these calcite platelets has been a matter of debate for decades but has remained elusive so far. One hypothesis is that they play a role in light or UV protection, especially in surface dwelling species like Emiliania huxleyi, which can tolerate exceptionally high levels of solar radiation. In this study, we tested this hypothesis by culturing a calcified and a naked strain under different light conditions with and without UV radiation. The coccoliths of E. huxleyi reduced the transmission of visible radiation (400-700 nm) by 7.5 %, that of UV-A (315-400 nm) by 14.1 % and that of UV-B (280-315 nm) by 18.4 %. Growth rates of the calcified strain (PML B92/11) were about 2 times higher than those of the naked strain (CCMP 2090) under indoor constant light levels in the absence of UV radiation. When exposed to outdoor conditions (fluctuating sunlight with UV radiation), growth rates of calcified cells were almost 3.5 times higher compared to naked cells. Furthermore, the relative electron transport rate was 114 % higher and non-photochemical quenching (NPQ) was 281 % higher in the calcified compared to the naked strain, implying higher energy transfer associated with higher NPQ in the presence of calcification. When exposed to natural solar radiation including UV radiation, the maximal quantum yield of photosystem II was only slightly reduced in the calcified strain but strongly reduced in the naked strain. Our results reveal an important role of coccoliths in mitigating light and UV stress in E. huxleyi.

  15. Simultaneous shifts in elemental stoichiometry and fatty acids of Emiliania huxleyi in response to environmental changes

    Science.gov (United States)

    Bi, Rong; Ismar, Stefanie M. H.; Sommer, Ulrich; Zhao, Meixun

    2018-02-01

    Climate-driven changes in environmental conditions have significant and complex effects on marine ecosystems. Variability in phytoplankton elements and biochemicals can be important for global ocean biogeochemistry and ecological functions, while there is currently limited understanding on how elements and biochemicals respond to the changing environments in key coccolithophore species such as Emiliania huxleyi. We investigated responses of elemental stoichiometry and fatty acids (FAs) in a strain of E. huxleyi under three temperatures (12, 18 and 24 °C), three N : P supply ratios (molar ratios 10:1, 24:1 and 63:1) and two pCO2 levels (560 and 2400 µatm). Overall, C : N : P stoichiometry showed the most pronounced response to N : P supply ratios, with high ratios of particulate organic carbon vs. particulate organic nitrogen (POC : PON) and low ratios of PON vs. particulate organic phosphorus (PON : POP) in low-N media, and high POC : POP and PON : POP in low-P media. The ratio of particulate inorganic carbon vs. POC (PIC : POC) and polyunsaturated fatty acid proportions strongly responded to temperature and pCO2, both being lower under high pCO2 and higher with warming. We observed synergistic interactions between warming and nutrient deficiency (and high pCO2) on elemental cellular contents and docosahexaenoic acid (DHA) proportion in most cases, indicating the enhanced effect of warming under nutrient deficiency (and high pCO2). Our results suggest differential sensitivity of elements and FAs to the changes in temperature, nutrient availability and pCO2 in E. huxleyi, which is to some extent unique compared to non-calcifying algal classes. Thus, simultaneous changes of elements and FAs should be considered when predicting future roles of E. huxleyi in the biotic-mediated connection between biogeochemical cycles, ecological functions and climate change.

  16. The 24 hour recovery kinetics from n starvation in Phaeodactylum tricornutum and Emiliania huxleyi.

    Science.gov (United States)

    Zhao, Yan; Wang, You; Quigg, Antonietta

    2015-08-01

    The response of N (nitrate) starved cells of the diatom Phaeodactylum tricornutum and the coccolithophore Emiliania huxleyi to a pulse of new N were measured to investigate rapid cellular and photosynthetic recovery kinetics. The changes of multiple parameters were followed over 24 h. In P. tricornutum, the recovery of Fv /Fm (the maximum quantum yield of PS II) and σPSII (the functional absorption cross-section for PSII) started within the first hour, much earlier than other parameters. Cellular pigments did not recover during the 24 h but the chlorophyll (chl) a/carotenoid ratios increased to levels measured in the controls. Cell division was independent of the recovery of chl a. In E. huxleyi, the recovery of Fv /Fm and σPSII started after an hour, synchronous with the increase in cellular organic N and chl a with pigments fully recovered within 14 h. P. tricornutum prioritized the recovery of its photosynthetic functions and cell divisions while E. huxleyi did not follow this pattern. We hypothesize that the different recovery strategies between the two species allow P. tricornutum to be more competitive when N pulses are introduced into N-limited water while E. huxleyi is adapted to N scarce waters where such pulses are infrequent. These findings are consistent with successional patterns observed in coastal environments. This is one of only a few studies exploring recovery kinetics of cellular functions and photosynthesis after nitrogen stress in phytoplankton. Our results can be used to enhance ecological models linking phytoplankton traits to species diversity and community structure. © 2015 Phycological Society of America.

  17. Population-specific responses in physiological rates of Emiliania huxleyi to a broad CO2 range

    Directory of Open Access Journals (Sweden)

    Y. Zhang

    2018-06-01

    Full Text Available Although coccolithophore physiological responses to CO2-induced changes in seawater carbonate chemistry have been widely studied in the past, there is limited knowledge on the variability of physiological responses between populations from different areas. In the present study, we investigated the specific responses of growth, particulate organic (POC and inorganic carbon (PIC production rates of three populations of the coccolithophore Emiliania huxleyi from three regions in the North Atlantic Ocean (Azores: six strains, Canary Islands: five strains, and Norwegian coast near Bergen: six strains to a CO2 partial pressure (pCO2 range from 120 to 2630 µatm. Physiological rates of each population and individual strain increased with rising pCO2 levels, reached a maximum and declined thereafter. Optimal pCO2 for growth, POC production rates, and tolerance to low pH (i.e., high proton concentration was significantly higher in an E. huxleyi population isolated from the Norwegian coast than in those isolated near the Azores and Canary Islands. This may be due to the large environmental variability including large pCO2 and pH fluctuations in coastal waters off Bergen compared to the rather stable oceanic conditions at the other two sites. Maximum growth and POC production rates of the Azores and Bergen populations were similar and significantly higher than that of the Canary Islands population. This pattern could be driven by temperature–CO2 interactions where the chosen incubation temperature (16 °C was slightly below what strains isolated near the Canary Islands normally experience. Our results indicate adaptation of E. huxleyi to their local environmental conditions and the existence of distinct E. huxleyi populations. Within each population, different growth, POC, and PIC production rates at different pCO2 levels indicated strain-specific phenotypic plasticity. Accounting for this variability is important to understand how or whether E. huxleyi

  18. Bacterial Diversity Associated with the Coccolithophorid Algae Emiliania huxleyi and Coccolithus pelagicus f. braarudii

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    David H. Green

    2015-01-01

    Full Text Available Coccolithophores are unicellular calcifying marine phytoplankton that can form large and conspicuous blooms in the oceans and make significant contributions to oceanic carbon cycling and atmospheric CO2 regulation. Despite their importance, the bacterial diversity associated with these algae has not been explored for ecological or biotechnological reasons. Bacterial membership of Emiliania huxleyi and Coccolithus pelagicus f. braarudii cultures was assessed using cultivation and cultivation-independent methods. The communities were species rich compared to other phytoplankton cultures. Community analysis identified specific taxa which cooccur in all cultures (Marinobacter and Marivita. Hydrocarbon-degrading bacteria were found in all cultures. The presence of Acidobacteria, Acidimicrobidae, Schlegelella, and Thermomonas was unprecedented but were potentially explained by calcification associated with coccolith production. One strain of Acidobacteria was cultivated and is closely related to a marine Acidobacteria isolated from a sponge. From this assessment of the bacterial diversity of coccolithophores, a number of biotechnological opportunities are evident, from bioprospecting for novel taxa such as Acidobacteria to helping understand the relationship between obligate hydrocarbonoclastic bacteria occurrence with phytoplankton and to revealing bacterial taxa that have a specific association with algae and may be suitable candidates as a means to improve the efficiency of mass algal cultivation.

  19. Functional genetic divergence in high CO2 adapted Emiliania huxleyi populations.

    Science.gov (United States)

    Lohbeck, Kai T; Riebesell, Ulf; Collins, Sinéad; Reusch, Thorsten B H

    2013-07-01

    Predicting the impacts of environmental change on marine organisms, food webs, and biogeochemical cycles presently relies almost exclusively on short-term physiological studies, while the possibility of adaptive evolution is often ignored. Here, we assess adaptive evolution in the coccolithophore Emiliania huxleyi, a well-established model species in biological oceanography, in response to ocean acidification. We previously demonstrated that this globally important marine phytoplankton species adapts within 500 generations to elevated CO2 . After 750 and 1000 generations, no further fitness increase occurred, and we observed phenotypic convergence between replicate populations. We then exposed adapted populations to two novel environments to investigate whether or not the underlying basis for high CO2 -adaptation involves functional genetic divergence, assuming that different novel mutations become apparent via divergent pleiotropic effects. The novel environment "high light" did not reveal such genetic divergence whereas growth in a low-salinity environment revealed strong pleiotropic effects in high CO2 adapted populations, indicating divergent genetic bases for adaptation to high CO2 . This suggests that pleiotropy plays an important role in adaptation of natural E. huxleyi populations to ocean acidification. Our study highlights the potential mutual benefits for oceanography and evolutionary biology of using ecologically important marine phytoplankton for microbial evolution experiments. © 2012 The Author(s). Evolution © 2012 The Society for the Study of Evolution.

  20. Cellular pH measurements in Emiliania huxleyi reveal pronounced membrane proton permeability.

    Science.gov (United States)

    Suffrian, K; Schulz, K G; Gutowska, M A; Riebesell, U; Bleich, M

    2011-05-01

    • To understand the influence of changing surface ocean pH and carbonate chemistry on the coccolithophore Emiliania huxleyi, it is necessary to characterize mechanisms involved in pH homeostasis and ion transport. • Here, we measured effects of changes in seawater carbonate chemistry on the fluorescence emission ratio of BCECF (2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein) as a measure of intracellular pH (pH(i)). Out of equilibrium solutions were used to differentiate between membrane permeation pathways for H(+), CO(2) and HCO(3)(-). • Changes in fluorescence ratio were calibrated in single cells, resulting in a ratio change of 0.78 per pH(i) unit. pH(i) acutely followed the pH of seawater (pH(e)) in a linear fashion between pH(e) values of 6.5 and 9 with a slope of 0.44 per pH(e) unit. pH(i) was nearly insensitive to changes in seawater CO(2) at constant pH(e) and HCO(3)(-). An increase in extracellular HCO(3)(-) resulted in a slight intracellular acidification. In the presence of DIDS (4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid), a broad-spectrum inhibitor of anion exchangers, E. huxleyi acidified irreversibly. DIDS slightly reduced the effect of pH(e) on pH(i). • The data for the first time show the occurrence of a proton permeation pathway in E. huxleyi plasma membrane. pH(i) homeostasis involves a DIDS-sensitive mechanism. © 2011 The Authors. New Phytologist © 2011 New Phytologist Trust.

  1. Incorporation of zinc into the coccoliths of the microalga Emiliania huxleyi.

    Science.gov (United States)

    Santomauro, Giulia; Sun, Wei-Lin; Brümmer, Franz; Bill, Joachim

    2016-04-01

    The coccolithophore Emiliania huxleyi is covered with elaborated calcite plates, the so-called coccoliths, which are produced inside the cells. We investigated the incorporation of zinc into the coccoliths of E. huxleyi by applying different zinc and calcium amounts via the culture media and subsequently analyzing the zinc content in the cells and the Zn/Ca ratio of the coccoliths. To investigate the Zn/Ca ratio of coccoliths built in the manipulated media, the algae have first to be decalcified, i.e. coccolith free. We used a newly developed decalcification method to obtain 'naked' cells for cultivation. E. huxleyi proliferated and produced new coccoliths in all media with manipulated Zn/Ca ratios. The cells and the newly built coccoliths were investigated regarding their zinc content and their Zn/Ca ratio, respectively. High zinc amounts were taken up by the algae. The Zn/Ca ratio of the coccoliths was positively correlated to the Zn/Ca ratio of the applied media. The unique feature of the coccoliths was maintained also at high Zn/Ca ratios. We suggest the following pathway of the zinc ions into the coccoliths: first, the zinc ions are bound to the cell surface, followed by their transportation into the cytoplasm. Obviously, the zinc ions are removed afterwards into the coccolith vesicle, where the zinc is incorporated into the calcite coccoliths which are then extruded. The incorporation of toxic zinc ions into the coccoliths possibly due to a new function of the coccoliths as detoxification sites is discussed.

  2. Environmental carbonate chemistry selects for phenotype of recently isolated strains of Emiliania huxleyi

    Science.gov (United States)

    Rickaby, Rosalind E. M.; Hermoso, Michaël; Lee, Renee B. Y.; Rae, Benjamin D.; Heureux, Ana M. C.; Balestreri, Cecilia; Chakravarti, Leela; Schroeder, Declan C.; Brownlee, Colin

    2016-05-01

    Coccolithophorid algae, particularly Emiliania huxleyi, are prolific biomineralisers that, under many conditions, dominate communities of marine eukaryotic plankton. Their ability to photosynthesise and form calcified scales (coccoliths) has placed them in a unique position in the global carbon cycle. Contrasting reports have been made with regards to the response of E. huxleyi to ocean acidification. Therefore, there is a pressing need to further determine the fate of this key organism in a rising CO2 world. In this paper, we investigate the phenotype of newly isolated, genetically diverse, strains of E. huxleyi from UK Ocean Acidification Research Programme (UKOA) cruises around the British Isles, the Arctic, and the Southern Ocean. We find a continuum of diversity amongst the physiological and photosynthetic parameters of different strains of E. huxleyi morphotype A under uniform, ambient conditions imposed in the laboratory. This physiology is best explained by adaptation to carbonate chemistry in the former habitat rather than being prescribed by genetic fingerprints such as the coccolithophore morphology motif (CMM). To a first order, the photosynthetic capacity of each strain is a function of both aqueous CO2 availability, and calcification rate, suggestive of a link between carbon concentrating ability and calcification. The calcification rate of each strain is related linearly to the natural environmental [CO32-] at the site of isolation, but a few exceptional strains display low calcification rates at the highest [CO32-] when calcification is limited by low CO2 availability and/or a lack of a carbon concentrating mechanism. We present O2-electrode measurements alongside coccolith oxygen isotopic composition and the uronic acid content (UAC) of the coccolith associated polysaccharide (CAP), that act as indirect tools to show the differing carbon concentrating ability of the strains. The environmental selection revealed amongst our recently isolated strain

  3. 7000 years of Emiliania huxleyi viruses in the Black Sea.

    Science.gov (United States)

    Coolen, Marco J L

    2011-07-22

    A 7000-year record of Coccolithovirus and its host, the calcifying haptophyte Emiliania huxleyi, was reconstructed on the basis of genetic signatures preserved in sediments underlying the Black Sea. The data show that the same virus and host populations can persist for centuries. Major changes in virus and host populations occurred during early sapropel deposition, ~5600 years ago, and throughout the formation of the coccolith-bearing sediments of Unit I during the past 2500 years, when the Black Sea experienced dramatic changes in hydrologic and nutrient regimes. Unit I saw a reoccurrence of the same host genotype thousands of years later in the presence of a different subset of viruses. Historical plankton virus populations can thus be included in paleoecological and paleoenvironmental studies.

  4. Formation and mosaicity of coccolith segment calcite of the marine algae Emiliania huxleyi.

    Science.gov (United States)

    Yin, Xiaofei; Ziegler, Andreas; Kelm, Klemens; Hoffmann, Ramona; Watermeyer, Philipp; Alexa, Patrick; Villinger, Clarissa; Rupp, Ulrich; Schlüter, Lothar; Reusch, Thorsten B H; Griesshaber, Erika; Walther, Paul; Schmahl, Wolfgang W

    2018-02-01

    Coccolithophores belong to the most abundant calcium carbonate mineralizing organisms. Coccolithophore biomineralization is a complex and highly regulated process, resulting in a product that strongly differs in its intricate morphology from the abiogenically produced mineral equivalent. Moreover, unlike extracellularly formed biological carbonate hard tissues, coccolith calcite is neither a hybrid composite, nor is it distinguished by a hierarchical microstructure. This is remarkable as the key to optimizing crystalline biomaterials for mechanical strength and toughness lies in the composite nature of the biological hard tissue and the utilization of specific microstructures. To obtain insight into the pathway of biomineralization of Emiliania huxleyi coccoliths, we examine intracrystalline nanostructural features of the coccolith calcite in combination with cell ultrastructural observations related to the formation of the calcite in the coccolith vesicle within the cell. With TEM diffraction and annular dark-field imaging, we prove the presence of planar imperfections in the calcite crystals such as planar mosaic block boundaries. As only minor misorientations occur, we attribute them to dislocation networks creating small-angle boundaries. Intracrystalline occluded biopolymers are not observed. Hence, in E. huxleyi calcite mosaicity is not caused by occluded biopolymers, as it is the case in extracellularly formed hard tissues of marine invertebrates, but by planar defects and dislocations which are typical for crystals formed by classical ion-by-ion growth mechanisms. Using cryo-preparation techniques for SEM and TEM, we found that the membrane of the coccolith vesicle and the outer membrane of the nuclear envelope are in tight proximity, with a well-controlled constant gap of ~4 nm between them. We describe this conspicuous connection as a not yet described interorganelle junction, the "nuclear envelope junction". The narrow gap of this junction likely

  5. Temperature effects on sinking velocity of different Emiliania huxleyi strains.

    Science.gov (United States)

    Rosas-Navarro, Anaid; Langer, Gerald; Ziveri, Patrizia

    2018-01-01

    The sinking properties of three strains of Emiliania huxleyi in response to temperature changes were examined. We used a recently proposed approach to calculate sinking velocities from coccosphere architecture, which has the advantage to be applicable not only to culture samples, but also to field samples including fossil material. Our data show that temperature in the sub-optimal range impacts sinking velocity of E. huxleyi. This response is widespread among strains isolated in different locations and moreover comparatively predictable, as indicated by the similar slopes of the linear regressions. Sinking velocity was positively correlated to temperature as well as individual cell PIC/POC over the sub-optimum to optimum temperature range in all strains. In the context of climate change our data point to an important influence of global warming on sinking velocities. It has recently been shown that seawater acidification has no effect on sinking velocity of a Mediterranean E. huxleyi strain, while nutrient limitation seems to have a small negative effect on sinking velocity. Given that warming, acidification, and lowered nutrient availability will occur simultaneously under climate change scenarios, the question is what the net effect of different influential factors will be. For example, will the effects of warming and nutrient limitation cancel? This question cannot be answered conclusively but analyses of field samples in addition to laboratory culture studies will improve predictions because in field samples multi-factor influences and even evolutionary changes are not excluded. As mentioned above, the approach of determining sinking rate followed here is applicable to field samples. Future studies could use it to analyse not only seasonal and geographic patterns but also changes in sinking velocity over geological time scales.

  6. Simultaneous shifts in elemental stoichiometry and fatty acids of Emiliania huxleyi in response to environmental changes

    Directory of Open Access Journals (Sweden)

    R. Bi

    2018-02-01

    Full Text Available Climate-driven changes in environmental conditions have significant and complex effects on marine ecosystems. Variability in phytoplankton elements and biochemicals can be important for global ocean biogeochemistry and ecological functions, while there is currently limited understanding on how elements and biochemicals respond to the changing environments in key coccolithophore species such as Emiliania huxleyi. We investigated responses of elemental stoichiometry and fatty acids (FAs in a strain of E. huxleyi under three temperatures (12, 18 and 24 °C, three N : P supply ratios (molar ratios 10:1, 24:1 and 63:1 and two pCO2 levels (560 and 2400 µatm. Overall, C : N : P stoichiometry showed the most pronounced response to N : P supply ratios, with high ratios of particulate organic carbon vs. particulate organic nitrogen (POC : PON and low ratios of PON vs. particulate organic phosphorus (PON : POP in low-N media, and high POC : POP and PON : POP in low-P media. The ratio of particulate inorganic carbon vs. POC (PIC : POC and polyunsaturated fatty acid proportions strongly responded to temperature and pCO2, both being lower under high pCO2 and higher with warming. We observed synergistic interactions between warming and nutrient deficiency (and high pCO2 on elemental cellular contents and docosahexaenoic acid (DHA proportion in most cases, indicating the enhanced effect of warming under nutrient deficiency (and high pCO2. Our results suggest differential sensitivity of elements and FAs to the changes in temperature, nutrient availability and pCO2 in E. huxleyi, which is to some extent unique compared to non-calcifying algal classes. Thus, simultaneous changes of elements and FAs should be considered when predicting future roles of E. huxleyi in the biotic-mediated connection between biogeochemical cycles, ecological functions and climate change.

  7. ELEVATED CARBON DIOXIDE DIFFERENTIALLY ALTERS THE PHOTOPHYSIOLOGY OF THALASSIOSIRA PSEUDONANA (BACILLARIOPHYCEAE) AND EMILIANIA HUXLEYI (HAPTOPHYTA)(1).

    Science.gov (United States)

    McCarthy, Avery; Rogers, Susan P; Duffy, Stephen J; Campbell, Douglas A

    2012-06-01

    Increasing anthropogenic carbon dioxide is causing changes to ocean chemistry, which will continue in a predictable manner. Dissolution of additional atmospheric carbon dioxide leads to increased concentrations of dissolved carbon dioxide and bicarbonate and decreased pH in ocean water. The concomitant effects on phytoplankton ecophysiology, leading potentially to changes in community structure, are now a focus of concern. Therefore, we grew the coccolithophore Emiliania huxleyi (Lohmann) W. W. Hay et H. Mohler and the diatom strains Thalassiosira pseudonana (Hust.) Hasle et Heimdal CCMP 1014 and T. pseudonana CCMP 1335 under low light in turbidostat photobioreactors bubbled with air containing 390 ppmv or 750 ppmv CO2 . Increased pCO2 led to increased growth rates in all three strains. In addition, protein levels of RUBISCO increased in the coastal strains of both species, showing a larger capacity for CO2 assimilation at 750 ppmv CO2 . With increased pCO2 , both T. pseudonana strains displayed an increased susceptibility to PSII photoinactivation and, to compensate, an augmented capacity for PSII repair. Consequently, the cost of maintaining PSII function for the diatoms increased at increased pCO2 . In E. huxleyi, PSII photoinactivation and the counter-acting repair, while both intrinsically larger than in T. pseudonana, did not change between the current and high-pCO2 treatments. The content of the photosynthetic electron transport intermediary cytochrome b6/f complex increased significantly in the diatoms under elevated pCO2 , suggesting changes in electron transport function. © 2012 Phycological Society of America.

  8. Influence of changing carbonate chemistry on morphology and weight of coccoliths formed by Emiliania huxleyi

    Directory of Open Access Journals (Sweden)

    K. G. Schulz

    2012-08-01

    Full Text Available The coccolithophore Emiliania huxleyi is a marine phytoplankton species capable of forming small calcium carbonate scales (coccoliths which cover the organic part of the cell. Calcification rates of E. huxleyi are known to be sensitive to changes in seawater carbonate chemistry. It has, however, not yet been clearly determined how these changes are reflected in size and weight of individual coccoliths and which specific parameter(s of the carbonate system drive morphological modifications. Here, we compare data on coccolith size, weight, and malformation from a set of five experiments with a large diversity of carbonate chemistry conditions. This diversity allows distinguishing the influence of individual carbonate chemistry parameters such as carbon dioxide (CO2, bicarbonate (HCO3−, carbonate ion (CO32−, and protons (H+ on the measured parameters. Measurements of fine-scale morphological structures reveal an increase of coccolith malformation with decreasing pH suggesting that H+ is the major factor causing malformations. Coccolith distal shield area varies from about 5 to 11 μm2. Changes in size seem to be mainly induced by varying [HCO3−] and [H+] although influence of [CO32−] cannot be entirely ruled out. Changes in coccolith weight were proportional to changes in size. Increasing CaCO3 production rates are reflected in an increase in coccolith weight and an increase of the number of coccoliths formed per unit time. The combined investigation of morphological features and coccolith production rates presented in this study may help to interpret data derived from sediment cores, where coccolith morphology is used to reconstruct calcification rates in the water column.

  9. Nineteen-year time-series sediment trap study of Coccolithus pelagicus and Emiliania huxleyi (calcareous nannoplankton) fluxes in the Bering Sea and subarctic Pacific Ocean

    Science.gov (United States)

    Tsutsui, Hideto; Takahashi, Kozo; Asahi, Hirofumi; Jordan, Richard W.; Nishida, Shiro; Nishiwaki, Niichi; Yamamoto, Sumito

    2016-03-01

    Coccolithophore fluxes at two sediment trap stations, Station AB in the Bering Sea and Station SA in the subarctic Pacific Ocean, were studied over a nineteen-year (August 1990-July 2009) interval. Two major species, Coccolithus pelagicus and Emiliania huxleyi, occur at both stations, with Gephyrocapsa oceanica, Umbilicosphaera sibogae, Braarudosphaera bigelowii, and Syracosphaera spp. as minor components. The mean coccolithophore fluxes at Stations AB and SA increased from 28.9×106 m2 d-1 and 61.9×106 m2 d-1 in 1990-1999 to 54.4×106 m2 d-1 and 130.2×106 m2 d-1 in 2002-2009, respectively. Furthermore, in late 1999 to early 2000, there was a significant shift in the most dominant species from E. huxleyi to C. pelagicus. High abundances of E. huxleyi correspond to the positive mode of the Pacific Decadal Oscillation (PDO), while those of C. pelagicus respond to the PDO negative mode and are related to water temperature changes at huxleyi. At both stations the mean seawater temperature in the top 45 m from August to October increased ca. 1 °C with linear recurrence from 1990 to 2008. The coccosphere fluxes after Year 2000 at Stations AB and SA, and the shift in species dominance, may have been influenced by this warming.

  10. Variable production of transparent exopolymeric particles by haploid and diploid life stages of coccolithophores grown under different CO2 concentrations

    NARCIS (Netherlands)

    Pedrotti, M.L.; Fiorini, S.; Kerros, M.E.; Middelburg, J.J.; Gattuso, J.P.

    2012-01-01

    The production of transparent exopolymeric particles (TEP) by the coccolithophores, Emiliania huxleyi, Calcidiscus leptoporus and Syracosphaera pulchra was investigated in batch cultures. The abundance, size spectra and carbon content of TEP were examined during the exponential growth phase of both

  11. Phenotypic diversity of diploid and haploid Emiliania huxleyi cells and of cells in different growth phases revealed by comparative metabolomics.

    Science.gov (United States)

    Mausz, Michaela A; Pohnert, Georg

    2015-01-01

    In phytoplankton a high species diversity of microalgae co-exists at a given time. But diversity is not only reflected by the species composition. Within these species different life phases as well as different metabolic states can cause additional diversity. One important example is the coccolithophore Emiliania huxleyi. Diploid cells play an important role in marine ecosystems since they can form massively abundant algal blooms but in addition the less abundant haploid life phase of E. huxleyi occurs in lower quantities. Both life phases may fulfill different functions in the plankton. We hypothesize that in addition to the functional diversity caused by this life phase transition the growth stage of cells can also influence the metabolic composition and thus the ecological impact of E. huxleyi. Here we introduce a metabolomic survey in dependence of life phases as well as different growth phases to reveal such changes. The comparative metabolomic approach is based on the extraction of intracellular metabolites from intact microalgae, derivatization and analysis by gas chromatography coupled to mass spectrometry (GC-MS). Automated data processing and statistical analysis using canonical analysis of principal coordinates (CAP) revealed unique metabolic profiles for each life phase. Concerning the correlations of metabolites to growth phases, complex patterns were observed. As for example the saccharide mannitol showed its highest concentration in the exponential phase, whereas fatty acids were correlated to stationary and sterols to declining phase. These results are indicative for specific ecological roles of these stages of E. huxleyi and are discussed in the context of previous physiological and ecological studies. Copyright © 2014 Elsevier GmbH. All rights reserved.

  12. Release of dissolved carbohydrates by Emiliania huxleyi and formation of transparent exopolymer particles depend on algal life cycle and bacterial activity.

    Science.gov (United States)

    Van Oostende, Nicolas; Moerdijk-Poortvliet, Tanja C W; Boschker, Henricus T S; Vyverman, Wim; Sabbe, Koen

    2013-05-01

    The coccolithophore Emiliania huxleyi plays a pivotal role in the marine carbon cycle. However, we have only limited understanding of how its life cycle and bacterial interactions affect the production and composition of dissolved extracellular organic carbon and its transfer to the particulate pool. We traced the fate of photosynthetically fixed carbon during phosphate-limited stationary growth of non-axenic, calcifying E. huxleyi batch cultures, and more specifically the transfer of this carbon to bacteria and to dissolved high molecular weight neutral aldoses (HMW NAld) and extracellular particulate carbon. We then compared the dynamics of dissolved carbohydrates and transparent exopolymer particles (TEP) between cultures of non-axenic and axenic diploid E. huxleyi. In addition, we present the first data on extracellular organic carbon in (non-axenic) haploid E. huxleyi cultures. Bacteria enhanced the accumulation of dissolved polysaccharides and altered the composition of dissolved HMW NAld, while they also stimulated the formation of TEP containing high densities of charged polysaccharides in diploid E. huxleyi cultures. In haploid E. huxleyi cultures we found a more pronounced accumulation of dissolved carbohydrates, which had a different NAld composition than the diploid cultures. TEP formation was significantly lower than in the diploid cultures, despite the presence of bacteria. In diploid E. huxleyi cultures, we measured a high level of extracellular release of organic carbon (34-76%), retrieved mainly in the particulate pool instead of the dissolved pool. Enhanced formation of sticky TEP due to bacteria-alga interactions, in concert with the production of coccoliths, suggests that especially diploid E. huxleyi blooms increase the efficiency of export production in the ocean during dissolved phosphate-limited conditions. © 2012 Society for Applied Microbiology and Blackwell Publishing Ltd.

  13. Novel molecular determinants of viral susceptibility and resistance in the lipidome of Emiliania huxleyi.

    Science.gov (United States)

    Fulton, James M; Fredricks, Helen F; Bidle, Kay D; Vardi, Assaf; Kendrick, B Jacob; DiTullio, Giacomo R; Van Mooy, Benjamin A S

    2014-04-01

    Viruses play a key role in controlling the population dynamics of algae, including Emiliania huxleyi, a globally distributed haptophyte with calcite coccoliths that comprise ca. 50% of the sinking carbonate flux from the surface ocean. Emiliania huxleyi viruses (EhVs) routinely infect and terminate E. huxleyi blooms. EhVs are surrounded by a lipid envelope, which we found to be comprised largely of glycosphingolipids (GSLs) with lesser amounts of polar glycerolipids. Infection appears to involve membrane fusion between the virus and host, and we hypothesized that specific polar lipids may facilitate virus attachment. We identified three novel intact polar lipids in E. huxleyi strain CCMP 374 and EhV86, including a GSL with a monosaccharide sialic acid headgroup (sGSL); for all 11 E. huxleyi strains we tested, there was a direct relationship between sGSL content and sensitivity to infection by EhV1, EhV86 and EhV163. In mesocosms, the E. huxleyi population with greatest initial sGSL content had the highest rate of virus-induced mortality. We propose potential physiological roles for sGSL that would be beneficial for growth but leave cells susceptible to infection, thus furthering the discussion of Red Queen-based co-evolution and the cost(s) of sensitivity and resistance in the dynamic E. huxleyi-EhV system. © 2013 Society for Applied Microbiology and John Wiley & Sons Ltd.

  14. Simulating the effects of light intensity and carbonate system composition on particulate organic and inorganic carbon production in Emiliania huxleyi.

    Science.gov (United States)

    Holtz, Lena-Maria; Wolf-Gladrow, Dieter; Thoms, Silke

    2015-05-07

    Coccolithophores play an important role in the marine carbon cycle. Variations in light intensity and external carbonate system composition alter intracellular carbon fluxes and therewith the production rates of particulate organic and inorganic carbon. Aiming to find a mechanistic explanation for the interrelation between dissolved inorganic carbon fluxes and particulate carbon production rates, we develop a numerical cell model for Emiliania huxleyi, one of the most abundant coccolithophore species. The model consists of four cellular compartments, for each of which the carbonate system is resolved dynamically. The compartments are connected to each other and to the external medium via substrate fluxes across the compartment-confining membranes. By means of the model we are able to explain several pattern observed in particulate organic and inorganic carbon production rates for different strains and under different acclimation conditions. Particulate organic and inorganic carbon production rates for instance decrease at very low external CO2 concentrations. Our model suggests that this effect is caused mainly by reduced HCO3(-) uptake rates, not by CO2 limitation. The often observed decrease in particulate inorganic carbon production rates under Ocean Acidification is explained by a downregulation of cellular HCO3(-) uptake. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  15. Isolation and characterization of lipid rafts in Emiliania huxleyi: a role for membrane microdomains in host-virus interactions.

    Science.gov (United States)

    Rose, Suzanne L; Fulton, James M; Brown, Christopher M; Natale, Frank; Van Mooy, Benjamin A S; Bidle, Kay D

    2014-04-01

    Coccolithoviruses employ a suite of glycosphingolipids (GSLs) to successfully infect the globally important coccolithophore Emiliania huxleyi. Lipid rafts, chemically distinct membrane lipid microdomains that are enriched in GSLs and are involved in sensing extracellular stimuli and activating signalling cascades through protein-protein interactions, likely play a fundamental role in host-virus interactions. Using combined lipidomics, proteomics and bioinformatics, we isolated and characterized the lipid and protein content of lipid rafts from control E. huxleyi cells and those infected with EhV86, the type strain for Coccolithovirus. Lipid raft-enriched fractions were isolated and purified as buoyant, detergent-resistant membranes (DRMs) in OptiPrep density gradients. Transmission electron microscopy of vesicle morphology, polymerase chain reaction amplification of the EhV major capsid protein gene and immunoreactivity to flotillin antisera served as respective physical, molecular and biochemical markers. Subsequent lipid characterization of DRMs via high performance liquid chromatography-triple quadrapole mass spectrometry revealed four distinct GSL classes. Parallel proteomic analysis confirmed flotillin as a major lipid raft protein, along with a variety of proteins affiliated with host defence, programmed cell death and innate immunity pathways. The detection of an EhV86-encoded C-type lectin-containing protein confirmed that infection occurs at the interface between lipid rafts and cellular stress/death pathways via specific GSLs and raft-associated proteins. © 2013 Society for Applied Microbiology and John Wiley & Sons Ltd.

  16. Response of growth and photosynthesis of Emiliania huxleyi to visible and UV irradiances under different light regimes.

    Science.gov (United States)

    Xing, Tao; Gao, Kunshan; Beardall, John

    2015-01-01

    Microalgae are capable of acclimating to changes in light and ultraviolet radiation (UVR, 280-400 nm). However, little is known about how the ecologically important coccolithophore Emiliania huxleyi responds to UVR when acclimated to different light regimes. Here, we grew E. huxleyi under indoor constant light or fluctuating sunlight with or without UVR, and investigated its growth, photosynthetic performance and pigmentation. Under the indoor constant light regime, the specific growth rate (μ) was highest, while fluctuating outdoor solar radiation significantly decreased the growth rate. Addition of UVR further decreased the growth rate. The repair rate of photosystem II (PSII), as reflected in changes in PSII quantum yield, showed an inverse correlation with growth rate. Cells grown under the indoor constant light regime exhibited the lowest repair rate, while cells from the outdoor fluctuating light regimes significantly increased their repair rate. Addition of UVR increased both the repair rate and intracellular UV-absorbing compounds. This increased repair capability, at the cost of decreased growth rate, persisted after the cells were transferred back to the indoor again, suggesting an enhanced allocation of energy and resources for repair of photosynthetic machinery damage by solar UVR which persisted for a period after transfer from solar UVR. © 2014 The American Society of Photobiology.

  17. Emiliania huxleyi increases calcification but not expression of calcification-related genes in long-term exposure to elevated temperature and pCO2.

    Science.gov (United States)

    Benner, Ina; Diner, Rachel E; Lefebvre, Stephane C; Li, Dian; Komada, Tomoko; Carpenter, Edward J; Stillman, Jonathon H

    2013-01-01

    Increased atmospheric pCO2 is expected to render future oceans warmer and more acidic than they are at present. Calcifying organisms such as coccolithophores that fix and export carbon into the deep sea provide feedbacks to increasing atmospheric pCO2. Acclimation experiments suggest negative effects of warming and acidification on coccolithophore calcification, but the ability of these organisms to adapt to future environmental conditions is not well understood. Here, we tested the combined effect of pCO2 and temperature on the coccolithophore Emiliania huxleyi over more than 700 generations. Cells increased inorganic carbon content and calcification rate under warm and acidified conditions compared with ambient conditions, whereas organic carbon content and primary production did not show any change. In contrast to findings from short-term experiments, our results suggest that long-term acclimation or adaptation could change, or even reverse, negative calcification responses in E. huxleyi and its feedback to the global carbon cycle. Genome-wide profiles of gene expression using RNA-seq revealed that genes thought to be essential for calcification are not those that are most strongly differentially expressed under long-term exposure to future ocean conditions. Rather, differentially expressed genes observed here represent new targets to study responses to ocean acidification and warming.

  18. Temperature, light, and the dimethylsulfoniopropionate (DMSP) content of Emiliania huxleyi (Prymnesiophyceae)

    NARCIS (Netherlands)

    van Rijssel, M; Gieskes, W.W C

    The precursor of the volatile S-compound dimethylsulfide (DMS), dimethylsulfoniopropionate (DMSP), is produced by marine microalgae, notably by Prymnesiophyceae. The production of DMSP by an axenic isolate of Emiliania huxleyi (Lohm.) Hay et Mohler under different temperature and light conditions

  19. Photosynthesis and Calcification by Emiliania huxleyi (Prymnesiophyceae) as a Function of Inorganic Carbon Species

    NARCIS (Netherlands)

    Buitenhuis, Erik T.; Baar, Hein J.W. de; Veldhuis, Marcel J.W.

    1999-01-01

    To test the possibility of inorganic carbon limitation of the marine unicellular alga Emiliania huxleyi (Lohmann) Hay and Mohler, its carbon acquisition was measured as a function of the different chemical species of inorganic carbon present in the medium. Because these different species are

  20. UV radiation induced stress does not affect DMSP synthesis in the marine prymnesiophyte Emiliania huxleyi

    NARCIS (Netherlands)

    van Rijssel, M; Buma, A.G.J.

    2002-01-01

    A possible coupling between UV radiation (UVR; 280 to 400 nm) induced stress and the production of dimethylsulfoniopropionate (DMSP), the precursor of the climate-regulating gas dimethylsulfide (DMS), was investigated in the marine prymnesiophyte Emiliania huxleyi. To this end, axenic cultures of E.

  1. Emerging Interaction Patterns in the Emiliania huxleyi-EhV System.

    Science.gov (United States)

    Ruiz, Eliana; Oosterhof, Monique; Sandaa, Ruth-Anne; Larsen, Aud; Pagarete, António

    2017-03-22

    Viruses are thought to be fundamental in driving microbial diversity in the oceanic planktonic realm. That role and associated emerging infection patterns remain particularly elusive for eukaryotic phytoplankton and their viruses. Here we used a vast number of strains from the model system Emiliania huxleyi /Emiliania huxleyi Virus to quantify parameters such as growth rate (µ), resistance (R), and viral production (Vp) capacities. Algal and viral abundances were monitored by flow cytometry during 72-h incubation experiments. The results pointed out higher viral production capacity in generalist EhV strains, and the virus-host infection network showed a strong co-evolution pattern between E. huxleyi and EhV populations. The existence of a trade-off between resistance and growth capacities was not confirmed.

  2. Structural analysis of acidic oligosaccharides derived from the methylated, acidic polysaccharide associated with coccoliths of Emiliania huxleyi (lohmann) kamptner

    NARCIS (Netherlands)

    Fichtinger-Schepman, A.M.J.; Kamerling, J.P.; Versluis, C.; Vliegenthart, J.F.G.

    1980-01-01

    A series of acidic oligosaccharides was obtained by graded, acid hydrolysis of the methylated, acidic polysaccharide associated with the coccoliths of the alga Emiliania huxleyi (Lohmann) Kamptner. After fractionation by ion-exchange chromatography, the structures of the oligosaccharides were

  3. Coccolithophores in the equatorial Atlantic Ocean

    DEFF Research Database (Denmark)

    Kinkel, Hanno; Baumann, K.-H.; Cepek, M.

    2000-01-01

    with each other. In general, the living coccolithophores in the surface and subsurface waters show considerable variation in cell numbers and distribution patterns. Cell densities reached a maximum of up to 300 x 10 coccospheres/l in the upwelling area of the equatorial Atlantic. Here, Emiliania huxleyi...

  4. cDNA microarrays as a tool for identification of biomineralization proteins in the coccolithophorid Emiliania huxleyi (Haptophyta).

    Science.gov (United States)

    Quinn, Patrick; Bowers, Robert M; Zhang, Xiaoyu; Wahlund, Thomas M; Fanelli, Michael A; Olszova, Daniela; Read, Betsy A

    2006-08-01

    Marine unicellular coccolithophore algae produce species-specific calcite scales otherwise known as coccoliths. While the coccoliths and their elaborate architecture have attracted the attention of investigators from various scientific disciplines, our knowledge of the underpinnings of the process of biomineralization in this alga is still in its infancy. The processes of calcification and coccolithogenesis are highly regulated and likely to be complex, requiring coordinated expression of many genes and pathways. In this study, we have employed cDNA microarrays to investigate changes in gene expression associated with biomineralization in the most abundant coccolithophorid, Emiliania huxleyi. Expression profiling of cultures grown under calcifying and noncalcifying conditions has been carried out using cDNA microarrays corresponding to approximately 2,300 expressed sequence tags. A total of 127 significantly up- or down-regulated transcripts were identified using a P value of 0.01 and a change of >2.0-fold. Real-time reverse transcriptase PCR was used to test the overall validity of the microarray data, as well as the relevance of many of the proteins predicted to be associated with biomineralization, including a novel gamma-class carbonic anhydrase (A. R. Soto, H. Zheng, D. Shoemaker, J. Rodriguez, B. A. Read, and T. M. Wahlund, Appl. Environ. Microbiol. 72:5500-5511, 2006). Differentially regulated genes include those related to cellular metabolism, ion channels, transport proteins, vesicular trafficking, and cell signaling. The putative function of the vast majority of candidate transcripts could not be defined. Nonetheless, the data described herein represent profiles of the transcription changes associated with biomineralization-related pathways in E. huxleyi and have identified novel and potentially useful targets for more detailed analysis.

  5. The Bacterial Symbiont Phaeobacter inhibens Shapes the Life History of Its Algal Host Emiliania huxleyi

    Directory of Open Access Journals (Sweden)

    Anna R. Bramucci

    2018-05-01

    Full Text Available Marine microbes form host-associated biofilm communities that are shaped by complex interactions between bacteria and their host. The roseobacter Phaeobacter inhibens exploits both symbiotic and pathogenic niches while interacting with its microalgal host Emiliania huxleyi. During co-cultivation over extended periods with E. huxleyi, we show that P. inhibens selectively kills two host cell types, the diploid calcifying strain and the haploid flagellated strain. Meanwhile, various non-calcifying diploid strains are resistant to this pathogen or the pathogen is avirulent to this cell type. This differential pathogenesis has the potential of dramatically altering the composition of E. huxleyi blooms, which are typically dominated by the roseobacter-susceptible calcifying strain. This cell type makes calcite plates, which are an important sink in the marine carbon cycle and forms part of the marine paleobotanic record. P. inhibens kills the haploid cells, which have been proposed as critical to the survival of the algae, as they readily escape both eukaryotic predation and viral infection. Consequently, bacteria such as P. inhibens could influence E. huxleyi's life history by selective pathogenesis, thereby altering the composition of cell types within E. huxleyi populations and its bloom-bust lifestyle.

  6. Transcriptome analysis of the sulfate deficiency response in the marine microalga Emiliania huxleyi.

    Science.gov (United States)

    Bochenek, Michal; Etherington, Graham J; Koprivova, Anna; Mugford, Sam T; Bell, Thomas G; Malin, Gill; Kopriva, Stanislav

    2013-08-01

    The response to sulfate deficiency of plants and freshwater green algae has been extensively analysed by system biology approaches. By contrast, seawater sulfate concentration is high and very little is known about the sulfur metabolism of marine organisms. Here, we used a combination of metabolite analysis and transcriptomics to analyse the response of the marine microalga Emiliania huxleyi as it acclimated to sulfate limitation. Lowering sulfate availability in artificial seawater from 25 to 5 mM resulted in significant reduction in growth and intracellular concentrations of dimethylsulfoniopropionate and glutathione. Sulfate-limited E. huxleyi cells showed increased sulfate uptake but sulfate reduction to sulfite did not seem to be regulated. Sulfate limitation in E. huxleyi affected expression of 1718 genes. The vast majority of these genes were upregulated, including genes involved in carbohydrate and lipid metabolism, and genes involved in the general stress response. The acclimation response of E. huxleyi to sulfate deficiency shows several similarities to the well-described responses of Arabidopsis and Chlamydomonas, but also has many unique features. This dataset shows that even though E. huxleyi is adapted to constitutively high sulfate concentration, it retains the ability to re-program its gene expression in response to reduced sulfate availability. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

  7. How many Coccolithovirus genotypes does it take to terminate an Emiliania huxleyi bloom?

    Science.gov (United States)

    Highfield, Andrea; Evans, Claire; Walne, Anthony; Miller, Peter I; Schroeder, Declan C

    2014-10-01

    Giant viruses are known to be significant mortality agents of phytoplankton, often being implicated in the terminations of large Emiliania huxleyi blooms. We have previously shown the high temporal variability of E. huxleyi-infecting coccolithoviruses (EhVs) within a Norwegian fjord mesocosm. In the current study we investigated EhV dynamics within a naturally-occurring E. huxleyi bloom in the Western English Channel. Using denaturing gradient gel electrophoresis and marker gene sequencing, we uncovered a spatially highly dynamic Coccolithovirus population that was associated with a genetically stable E. huxleyi population as revealed by the major capsid protein gene (mcp) and coccolith morphology motif (CMM), respectively. Coccolithoviruses within the bloom were found to be variable with depth and unique virus populations were detected at different stations sampled indicating a complex network of EhV-host infections. This ultimately will have significant implications to the internal structure and longevity of ecologically important E. huxleyi blooms. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

  8. A Bacterial Pathogen Displaying Temperature-Enhanced Virulence of the Microalga Emiliania huxleyi.

    Science.gov (United States)

    Mayers, Teaghan J; Bramucci, Anna R; Yakimovich, Kurt M; Case, Rebecca J

    2016-01-01

    Emiliania huxleyi is a globally abundant microalga that plays a significant role in biogeochemical cycles. Over the next century, sea surface temperatures are predicted to increase drastically, which will likely have significant effects on the survival and ecology of E. huxleyi. In a warming ocean, this microalga may become increasingly vulnerable to pathogens, particularly those with temperature-dependent virulence. Ruegeria is a genus of Rhodobacteraceae whose population size tracks that of E. huxleyi throughout the alga's bloom-bust lifecycle. A representative of this genus, Ruegeria sp. R11, is known to cause bleaching disease in a red macroalga at elevated temperatures. To investigate if the pathogenicity of R11 extends to microalgae, it was co-cultured with several cell types of E. huxleyi near the alga's optimum (18°C), and at an elevated temperature (25°C) known to induce virulence in R11. The algal populations were monitored using flow cytometry and pulse-amplitude modulated fluorometry. Cultures of algae without bacteria remained healthy at 18°C, but lower cell counts in control cultures at 25°C indicated some stress at the elevated temperature. Both the C (coccolith-bearing) and S (scale-bearing swarming) cell types of E. huxleyi experienced a rapid decline resulting in apparent death when co-cultured with R11 at 25°C, but had no effect on N (naked) cell type at either temperature. R11 had no initial negative impact on C and S type E. huxleyi population size or health at 18°C, but caused death in older co-cultures. This differential effect of R11 on its host at 18 and 25°C suggest it is a temperature-enhanced opportunistic pathogen of E. huxleyi. We also detected caspase-like activity in dying C type cells co-cultured with R11, which suggests that programmed cell death plays a role in the death of E. huxleyi triggered by R11 - a mechanism induced by viruses (EhVs) and implicated in E. huxleyi bloom collapse. Given that E. huxleyi has recently been

  9. A Bacterial Pathogen Displaying Temperature-Enhanced Virulence of the Microalga Emiliania huxleyi

    Science.gov (United States)

    Mayers, Teaghan J.; Bramucci, Anna R.; Yakimovich, Kurt M.; Case, Rebecca J.

    2016-01-01

    Emiliania huxleyi is a globally abundant microalga that plays a significant role in biogeochemical cycles. Over the next century, sea surface temperatures are predicted to increase drastically, which will likely have significant effects on the survival and ecology of E. huxleyi. In a warming ocean, this microalga may become increasingly vulnerable to pathogens, particularly those with temperature-dependent virulence. Ruegeria is a genus of Rhodobacteraceae whose population size tracks that of E. huxleyi throughout the alga’s bloom–bust lifecycle. A representative of this genus, Ruegeria sp. R11, is known to cause bleaching disease in a red macroalga at elevated temperatures. To investigate if the pathogenicity of R11 extends to microalgae, it was co-cultured with several cell types of E. huxleyi near the alga’s optimum (18°C), and at an elevated temperature (25°C) known to induce virulence in R11. The algal populations were monitored using flow cytometry and pulse-amplitude modulated fluorometry. Cultures of algae without bacteria remained healthy at 18°C, but lower cell counts in control cultures at 25°C indicated some stress at the elevated temperature. Both the C (coccolith-bearing) and S (scale-bearing swarming) cell types of E. huxleyi experienced a rapid decline resulting in apparent death when co-cultured with R11 at 25°C, but had no effect on N (naked) cell type at either temperature. R11 had no initial negative impact on C and S type E. huxleyi population size or health at 18°C, but caused death in older co-cultures. This differential effect of R11 on its host at 18 and 25°C suggest it is a temperature-enhanced opportunistic pathogen of E. huxleyi. We also detected caspase-like activity in dying C type cells co-cultured with R11, which suggests that programmed cell death plays a role in the death of E. huxleyi triggered by R11 – a mechanism induced by viruses (EhVs) and implicated in E. huxleyi bloom collapse. Given that E. huxleyi has

  10. Plasticity in the proteome of Emiliania huxleyi CCMP 1516 to extremes of light is highly targeted.

    Science.gov (United States)

    McKew, Boyd A; Lefebvre, Stephane C; Achterberg, Eric P; Metodieva, Gergana; Raines, Christine A; Metodiev, Metodi V; Geider, Richard J

    2013-10-01

    Optimality principles are often applied in theoretical studies of microalgal ecophysiology to predict changes in allocation of resources to different metabolic pathways, and optimal acclimation is likely to involve changes in the proteome, which typically accounts for > 50% of cellular nitrogen (N). We tested the hypothesis that acclimation of the microalga Emiliania huxleyi CCMP 1516 to suboptimal vs supraoptimal light involves large changes in the proteome as cells rebalance the capacities to absorb light, fix CO2 , perform biosynthesis and resist photooxidative stress. Emiliania huxleyi was grown in nutrient-replete continuous culture at 30 (LL) and 1000 μmol photons m(-2) s(-1) (HL), and changes in the proteome were assessed by LC-MS/MS shotgun proteomics. Changes were most evident in proteins involved in the light reactions of photosynthesis; the relative abundance of photosystem I (PSI) and PSII proteins was 70% greater in LL, light-harvesting fucoxanthin-chlorophyll proteins (Lhcfs) were up to 500% greater in LL and photoprotective LI818 proteins were 300% greater in HL. The marked changes in the abundances of Lhcfs and LI818s, together with the limited plasticity in the bulk of the E. huxleyi proteome, probably reflect evolutionary pressures to provide energy to maintain metabolic capabilities in stochastic light environments encountered by this species in nature. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

  11. Strain-specific responses of Emiliania huxleyi to changing seawater carbonate chemistry

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    P. Ziveri

    2009-11-01

    Full Text Available Four strains of the coccolithophore E. huxleyi (RCC1212, RCC1216, RCC1238, RCC1256 were grown in dilute batch culture at four CO2 levels ranging from ~200 μatm to ~1200 μatm. Growth rate, particulate organic carbon content, and particulate inorganic carbon content were measured, and organic and inorganic carbon production calculated. The four strains did not show a uniform response to carbonate chemistry changes in any of the analysed parameters and none of the four strains displayed a response pattern previously described for this species. We conclude that the sensitivity of different strains of E. huxleyi to acidification differs substantially and that this likely has a genetic basis. We propose that this can explain apparently contradictory results reported in the literature.

  12. PHOTOSYNTHETIC PIGMENT AND GENETIC DIFFERENCES BETWEEN TWO SOUTHERN OCEAN MORPHOTYPES OF EMILIANIA HUXLEYI (HAPTOPHYTA)1.

    Science.gov (United States)

    Cook, Suellen S; Whittock, Lucy; Wright, Simon W; Hallegraeff, Gustaaf M

    2011-06-01

    The widespread coccolithophorid Emiliania huxleyi (Lohmann) W. W. Hay et H. Mohler plays a pivotal role in the carbon pump and is known to exhibit significant morphological, genetic, and physiological diversity. In this study, we compared photosynthetic pigments and morphology of triplicate strains of Southern Ocean types A and B/C. The two morphotypes differed in width of coccolith distal shield elements (0.11-0.24 μm, type A; 0.06-0.12 μm, type B/C) and morphology of distal shield central area (grill of curved rods in type A; thin plain plate in type B/C) and showed differences in carotenoid composition. The mean 19'-hexanoyloxyfucoxanthin (Hex):chl a ratio in type B/C was >1, whereas the type A ratio was huxleyi var. aurorae var. nov. S. S. Cook et Hallegr. © 2011 Phycological Society of America.

  13. Virus-induced apoptosis and phosphorylation form of metacaspase in the marine coccolithophorid Emiliania huxleyi.

    Science.gov (United States)

    Liu, Jingwen; Cai, Weicong; Fang, Xian; Wang, Xueting; Li, Guiling

    2018-04-01

    Lytic viral infection and programmed cell death (PCD) are thought to represent two distinct death mechanisms in phytoplankton, unicellular photoautotrophs that drift with ocean currents. PCD (apoptosis) is mainly brought about by the activation of caspases, a protease family with unique substrate selectivity. Here, we demonstrated that virus infection induced apoptosis of marine coccolithophorid Emiliania huxleyi BOF92 involving activation of metacaspase. E. huxleyi cells exhibited cell death process akin to that of apoptosis when exposed to virus infection. We observed typical hallmarks of apoptosis including cell shrinkage, associated nuclear morphological changes and DNA fragmentation. Immunoblotting revealed that antibody against human active-caspase-3 shared epitopes with a protein of ≈ 23 kDa; whose pattern of expression correlated with the onset of cell death. Moreover, analysis on two-dimensional gel electrophoresis revealed that two spots of active caspase-3 co-migrated with the different isoelectric points. Phosphatase treatment of cytosolic extracts containing active caspases-3 showed a mobility shift, suggesting that phosphorylated form of this enzyme might be present in the extracts. Computational prediction of phosphorylation sites based on the amino acid sequence of E. huxleyi metacaspase showed multiple phosphorylated sites for serine, threonine and tyrosine residues. This is the first report showing that phosphorylation modification of metacaspase in E. huxleyi might be required for certain biochemical and morphological changes during virus induced apoptosis.

  14. The effect of visible light stress on chemical signaling in two life stages of Emiliania huxleyi

    Science.gov (United States)

    Valentin-Alvarado, L.; Cooney, E.; Bright, K.; Strom, S.

    2016-02-01

    The cosmopolitan marine phytoplankton species Emiliania huxleyi presents a digenetic heteromorphic life cycle, with the non-motile diploid phase bearing coccoliths and the flagellated haploid phase being non-calcified. E. huxleyi contains high concentrations of dimethylsulphoniopropionate (DMSP), the precursor of dimethylsulphide (DMS). DMSP is a multifactorial compound; it acts as a compatible solute in cell metabolism and as a chemical signal influencing bacterial and protist behavior. In the atmosphere DMS enhances cloud formation influencing climate. However, little has been documented on E. huxleyi chemical signal responses to high light stress, and how this relates to the heteromorphic life cycle. To this end, low light acclimated cultures of both haploid and diploid E. huxleyi were exposed to high light for 2 hr and allowed to recover in low light for 2 hr. During and after these treatments, growth, photosynthetic efficiency (Fv/Fm), DMSP (intracellular and released) and cell chlorophyll content were measured. Our preliminary results suggest that presence of high light decreased Fv/Fm to a greater extent in haploid than in diploid (calcified) cells, while recovery of Fv/Fm was rapid in both life stages. The chlorophyll content and intracellular DMSP was not different in both life stages. However, the dissolved DMSP increased after light stress in diploid cells suggesting a possible advantage as antioxidant protection or another cellular function, such as grazing protection in this life stage.

  15. Rewiring Host Lipid Metabolism by Large Viruses Determines the Fate of Emiliania huxleyi, a Bloom-Forming Alga in the Ocean[C][W][OPEN

    Science.gov (United States)

    Rosenwasser, Shilo; Mausz, Michaela A.; Schatz, Daniella; Sheyn, Uri; Malitsky, Sergey; Aharoni, Asaph; Weinstock, Eyal; Tzfadia, Oren; Ben-Dor, Shifra; Feldmesser, Ester; Pohnert, Georg; Vardi, Assaf

    2014-01-01

    Marine viruses are major ecological and evolutionary drivers of microbial food webs regulating the fate of carbon in the ocean. We combined transcriptomic and metabolomic analyses to explore the cellular pathways mediating the interaction between the bloom-forming coccolithophore Emiliania huxleyi and its specific coccolithoviruses (E. huxleyi virus [EhV]). We show that EhV induces profound transcriptome remodeling targeted toward fatty acid synthesis to support viral assembly. A metabolic shift toward production of viral-derived sphingolipids was detected during infection and coincided with downregulation of host de novo sphingolipid genes and induction of the viral-encoded homologous pathway. The depletion of host-specific sterols during lytic infection and their detection in purified virions revealed their novel role in viral life cycle. We identify an essential function of the mevalonate-isoprenoid branch of sterol biosynthesis during infection and propose its downregulation as an antiviral mechanism. We demonstrate how viral replication depends on the hijacking of host lipid metabolism during the chemical “arms race” in the ocean. PMID:24920329

  16. Characterization of the Small RNA Transcriptome of the Marine Coccolithophorid, Emiliania huxleyi.

    Science.gov (United States)

    Zhang, Xiaoyu; Gamarra, Jaime; Castro, Steven; Carrasco, Estela; Hernandez, Aaron; Mock, Thomas; Hadaegh, Ahmad R; Read, Betsy A

    2016-01-01

    Small RNAs (smRNAs) control a variety of cellular processes by silencing target genes at the transcriptional or post-transcription level. While extensively studied in plants, relatively little is known about smRNAs and their targets in marine phytoplankton, such as Emiliania huxleyi (E. huxleyi). Deep sequencing was performed of smRNAs extracted at different time points as E. huxleyi cells transition from logarithmic to stationary phase growth in batch culture. Computational analyses predicted 18 E. huxleyi specific miRNAs. The 18 miRNA candidates and their precursors vary in length (18-24 nt and 71-252 nt, respectively), genome copy number (3-1,459), and the number of genes targeted (2-107). Stem-loop real time reverse transcriptase (RT) PCR was used to validate miRNA expression which varied by nearly three orders of magnitude when growth slows and cells enter stationary phase. Stem-loop RT PCR was also used to examine the expression profiles of miRNA in calcifying and non-calcifying cultures, and a small subset was found to be differentially expressed when nutrients become limiting and calcification is enhanced. In addition to miRNAs, endogenous small RNAs such as ra-siRNAs, ta-siRNAs, nat-siRNAs, and piwiRNAs were predicted along with the machinery for the biogenesis and processing of si-RNAs. This study is the first genome-wide investigation smRNAs pathways in E. huxleyi. Results provide new insights into the importance of smRNAs in regulating aspects of physiological growth and adaptation in marine phytoplankton and further challenge the notion that smRNAs evolved with multicellularity, expanding our perspective of these ancient regulatory pathways.

  17. Induction of Phase Variation Events in the Life Cycle of the Marine Coccolithophorid Emiliania huxleyi

    Science.gov (United States)

    Laguna, Richard; Romo, Jesus; Read, Betsy A.; Wahlund, Thomas M.

    2001-01-01

    Emiliania huxleyi is a unicellular marine alga that is considered to be the world's major producer of calcite. The life cycle of this alga is complex and is distinguished by its ability to synthesize exquisitely sculptured calcium carbonate cell coverings known as coccoliths. These structures have been targeted by materials scientists for applications relating to the chemistry of biomedical materials, robust membranes for high-temperature separation technology, lightweight ceramics, and semiconductor design. To date, however, the molecular and biochemical events controlling coccolith production have not been determined. In addition, little is known about the life cycle of E. huxleyi and the environmental and physiological signals triggering phase switching between the diploid and haploid life cycle stages. We have developed laboratory methods for inducing phase variation between the haploid (S-cell) and diploid (C-cell) life cycle stages of E. huxleyi. Plating E. huxleyi C cells on solid media was shown to induce phase switching from the C-cell to the S-cell life cycle stage, the latter of which has been maintained for over 2 years under these conditions. Pure cultures of S cells were obtained for the first time. Laboratory conditions for inducing phase switching from the haploid stage to the diploid stage were also established. Regeneration of the C-cell stage from pure cultures of S cells followed a predictable pattern involving formation of large aggregations of S cells and the subsequent production of cultures consisting predominantly of diploid C cells. These results demonstrate the ability to manipulate the life cycle of E. huxleyi under controlled laboratory conditions, providing us with powerful tools for the development of genetic techniques for analysis of coccolithogenesis and for investigating the complex life cycle of this important marine alga. PMID:11525973

  18. Characterization of the Small RNA Transcriptome of the Marine Coccolithophorid, Emiliania huxleyi.

    Directory of Open Access Journals (Sweden)

    Xiaoyu Zhang

    Full Text Available Small RNAs (smRNAs control a variety of cellular processes by silencing target genes at the transcriptional or post-transcription level. While extensively studied in plants, relatively little is known about smRNAs and their targets in marine phytoplankton, such as Emiliania huxleyi (E. huxleyi. Deep sequencing was performed of smRNAs extracted at different time points as E. huxleyi cells transition from logarithmic to stationary phase growth in batch culture. Computational analyses predicted 18 E. huxleyi specific miRNAs. The 18 miRNA candidates and their precursors vary in length (18-24 nt and 71-252 nt, respectively, genome copy number (3-1,459, and the number of genes targeted (2-107. Stem-loop real time reverse transcriptase (RT PCR was used to validate miRNA expression which varied by nearly three orders of magnitude when growth slows and cells enter stationary phase. Stem-loop RT PCR was also used to examine the expression profiles of miRNA in calcifying and non-calcifying cultures, and a small subset was found to be differentially expressed when nutrients become limiting and calcification is enhanced. In addition to miRNAs, endogenous small RNAs such as ra-siRNAs, ta-siRNAs, nat-siRNAs, and piwiRNAs were predicted along with the machinery for the biogenesis and processing of si-RNAs. This study is the first genome-wide investigation smRNAs pathways in E. huxleyi. Results provide new insights into the importance of smRNAs in regulating aspects of physiological growth and adaptation in marine phytoplankton and further challenge the notion that smRNAs evolved with multicellularity, expanding our perspective of these ancient regulatory pathways.

  19. TRANSCRIPTOME ANALYSES REVEAL DIFFERENTIAL GENE EXPRESSION PATTERNS BETWEEN THE LIFE-CYCLE STAGES OF EMILIANIA HUXLEYI (HAPTOPHYTA) AND REFLECT SPECIALIZATION TO DIFFERENT ECOLOGICAL NICHES(1).

    Science.gov (United States)

    Rokitta, Sebastian D; de Nooijer, Lennart J; Trimborn, Scarlett; de Vargas, Colomban; Rost, Björn; John, Uwe

    2011-08-01

    Coccolithophores, especially the abundant, cosmopolitan species Emiliania huxleyi (Lohmann) W. W. Hay et H. P. Mohler, are one of the main driving forces of the oceanic carbonate pump and contribute significantly to global carbon cycling, due to their ability to calcify. A recent study indicates that termination of diploid blooms by viral infection induces life-cycle transition, and speculation has arisen about the role of the haploid, noncalcifying stage in coccolithophore ecology. To explore gene expression patterns in both life-cycle stages, haploid and diploid cells of E. huxleyi (RCC 1217 and RCC 1216) were acclimated to limiting and saturating photon flux densities. Transcriptome analyses were performed to assess differential genomic expression related to different ploidy levels and acclimation light intensities. Analyses indicated that life-cycle stages exhibit different properties of regulating genome expression (e.g., pronounced gene activation and gene silencing in the diploid stage), proteome maintenance (e.g., increased turnover of proteins in the haploid stage), as well as metabolic processing (e.g., pronounced primary metabolism and motility in the haploid stage and calcification in the diploid stage). Furthermore, higher abundances of transcripts related to endocytotic and digestive machinery were observed in the diploid stage. A qualitative feeding experiment indicated that both life-cycle stages are capable of particle uptake (0.5 μm diameter) in late-stationary growth phase. Results showed that the two life-cycle stages represent functionally distinct entities that are evolutionarily shaped to thrive in the environment they typically inhabit. © 2011 Phycological Society of America.

  20. NO MECHANISTIC DEPENDENCE OF PHOTOSYNTHESIS ON CALCIFICATION IN THE COCCOLITHOPHORID EMILIANIA HUXLEYI (HAPTOPHYTA)(1).

    Science.gov (United States)

    Leonardos, Nikos; Read, Betsy; Thake, Brenda; Young, Jeremy R

    2009-10-01

    There is still considerable uncertainty about the relationship between calcification and photosynthesis. It has been suggested that since calcification in coccolithophorids is an intracellular process that releases CO2 , it enhances photosynthesis in a manner analogous to a carbon-concentrating mechanism (CCM). The ubiquitous, bloom-forming, and numerically abundant coccolithophorid Emiliania huxleyi (Lohmann) W. W. Hay et H. Mohler was studied in nutrient-replete, pH and [CO2 ] controlled, continuous cultures (turbidostats) under a range of [Ca(2+) ] from 0 to 9 mM. We examined the long-term, fully acclimated photosynthesis-light responses and analyzed the crystalline structure of the coccoliths using SEM. The E. huxleyi cells completely lost their coccosphere when grown in 0 [Ca(2+) ], while thin, undercalcified and brittle coccoliths were evident at 1 mM [Ca(2+) ]. Coccoliths showed increasing levels of calcification with increasing [Ca(2+) ]. More robust coccoliths were noted, with no discernable differences in coccolith morphology when the cells were grown in either 5 or 9 mM (ambient seawater) [Ca(2+) ]. In contrast to calcification, photosynthesis was not affected by the [Ca(2+) ] in the media. Cells showed no correlation of their light-dependent O2 evolution with [Ca(2+) ], and in all [Ca(2+) ]-containing turbidostats, there were no significant differences in growth rate. The results show unequivocally that as a process, photosynthesis in E. huxleyi is mechanistically independent from calcification. © 2009 Phycological Society of America.

  1. Solar UV irradiances modulate effects of ocean acidification on the coccolithophorid Emiliania huxleyi.

    Science.gov (United States)

    Xu, Kai; Gao, Kunshan

    2015-01-01

    Emiliania huxleyi, the most abundant coccolithophorid in the oceans, is naturally exposed to solar UV radiation (UVR, 280-400 nm) in addition to photosynthetically active radiation (PAR). We investigated the physiological responses of E. huxleyi to the present day and elevated CO2 (390 vs 1000 μatm; with pH(NBS) 8.20 vs 7.86) under indoor constant PAR and fluctuating solar radiation with or without UVR. Enrichment of CO2 stimulated the production rate of particulate organic carbon (POC) under constant PAR, but led to unchanged POC production under incident fluctuating solar radiation. The production rates of particulate inorganic carbon (PIC) as well as PIC/POC ratios were reduced under the elevated CO2, ocean acidification (OA) condition, regardless of PAR levels, and the presence of UVR. However, moderate levels of UVR increased PIC production rates and PIC/POC ratios. OA treatment interacted with UVR to influence the alga's physiological performance, leading to reduced specific growth rate in the presence of UVA (315-400 nm) and decreased quantum yield, along with enhanced nonphotochemical quenching, with addition of UVB (280-315 nm). The results clearly indicate that UV radiation needs to be invoked as a key stressor when considering the impacts of ocean acidification on E. huxleyi. © 2014 The American Society of Photobiology.

  2. Functional screening of a novel Δ15 fatty acid desaturase from the coccolithophorid Emiliania huxleyi.

    Science.gov (United States)

    Kotajima, Tomonori; Shiraiwa, Yoshihiro; Suzuki, Iwane

    2014-10-01

    The coccolithophorid Emiliania huxleyi is a bloom-forming marine phytoplankton thought to play a key role as a biological pump that transfers carbon from the surface to the bottom of the ocean, thus contributing to the global carbon cycle. This alga is also known to accumulate a variety of polyunsaturated fatty acids. At 25°C, E. huxleyi produces mainly 14:0, 18:4n-3, 18:5n-3 and 22:6n-3. When the cells were transferred from 25°C to 15°C, the amount of unsaturated fatty acids, i.e. 18:1n-9, 18:3n-3 and 18:5n-3, gradually increased. Among the predicted desaturase genes whose expression levels were up-regulated at low temperature, we identified a gene encoding novel ∆15 fatty acid desaturase, EhDES15, involved in the production of n-3 polyunsaturated fatty acids in E. huxleyi. This desaturase contains a putative transit sequence for localization in chloroplasts and a ∆6 desaturase-like domain, but it does not contain a cytochrome b5 domain nor typical His-boxes found in ∆15 desaturases. Heterologous expression of EhDES15 cDNA in cyanobacterium Synechocystis sp. PCC 6803 cells increased the level of n-3 fatty acid species, which are produced at low levels in wild-type cells grown at 30°C. The orthologous genes are only conserved in the genomes of prasinophytes and cryptophytes. The His-boxes conserved in orthologues varied from that of the canonical ∆15 desaturases. These results suggested the gene encodes a novel ∆15 desaturase responsible for the synthesis of 18:3n-3 from 18:2n-6 in E. huxleyi. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Release and Consumption of DMSP from Emiliania Huxleyi during grazing by Oxyrrhis Marina

    Science.gov (United States)

    Wolfe, Gordon V.; Sherr, Evelyn B.; Sherr, Barry F.

    1994-01-01

    Degradation and release to solution of intracellular dimethylsulfoniopropionate (DMSP) from Emiliania huxleyi 370 was observed during grazing by the heterotrophic dinoflagellate Oxyrrhis marina in 24 h bottle incubations. Between 30 and 70% of the lost algal DMSP was metabolized by the grazers without production of dimethylsulfide (DMS) when grazer densities were 150 to 450/ml. The rest was released to solution and about 30% was converted to DMS by bacteria associated with the grazer culture. These experiments demonstrate that grazing by herbivorous protists may be an important sink for DMSP in marine waters, removing a potential source of DMS. Microzooplankton grazing may also indirectly increase the production of DMS by transferring algal DMSP to the dissolved pool, making it available for bacterial metabolism.

  4. Biodegradation of Emiliania huxleyi Aggregates by natural Prokaryotic Communities under Increasing Hydrostatic Pressure.

    Science.gov (United States)

    Riou, V.; Para, J.; Garel, M.; Guigue, C.; Al Ali, B.; Santinelli, C.; Lefèvre, D.; Gattuso, J. P.; Goutx, M.; Panagiotopoulos, C.; Beaufort, L.; Jacquet, S.; Le Moigne, F. A. C.; Tachikawa, K.; Tamburini, C.

    2016-02-01

    Fluxes of particulate organic carbon (POC) and minerals are positively correlated, suggesting that minerals could enhance the flux of POC into the deep ocean. The so called "ballast effect" posits that minerals could increase sinking particle densities and/or protect the organic matter from heterotrophic degradation. Laboratory controlled experiments on coccolithophorid aggregates under atmospheric pressure show that biogenic calcite both increases particle settling velocities and preserves the organic matter. However, such experiments have yet to include genuine prokaryote rates indicators as well as the effect of increasing pressure. Here, we used the PArticle Sinking Simulator (PASS) to investigate the effect of the increasing pressure on the degradation of Emiliania huxleyi (calcifiers) aggregates. Extra care was taken to obtain culture aggregates with low prokaryotic abundance prior to exposure to natural mesopelagic prokaryotic communities. Particulate organic and inorganic carbon and dissolved organic carbon concentrations were monitored along with the lipid and carbohydrate compositions, as well as prokaryotic community abundance and specific diversity. A control experiment, without natural prokaryotic community addition, indicates that the pressure increase did not have any effect on calcite dissolution observed after ten days. In contrast, the addition of natural prokaryotic community accelerates calcite dissolution under conditions of increasing pressure. Prokaryotic community development and the lipid fraction of E. huxleyi particulate organic carbon are enhanced under increasing pressure. These results suggest that hydrostatic pressure denatures the structural integrity of the carbonate skeleton that protects the cellular organic matter.

  5. Unveiling the transcriptional features associated with coccolithovirus infection of natural Emiliania huxleyi blooms.

    Science.gov (United States)

    Pagarete, António; Le Corguillé, Gildas; Tiwari, Bela; Ogata, Hiroyuki; de Vargas, Colomban; Wilson, William H; Allen, Michael J

    2011-12-01

    Lytic viruses have been implicated in the massive cellular lysis observed during algal blooms, through which they assume a prominent role in oceanic carbon and nutrient flows. Despite their impact on biogeochemical cycling, the transcriptional dynamics of these important oceanic events is still poorly understood. Here, we employ an oligonucleotide microarray to monitor host (Emiliania huxleyi) and virus (coccolithovirus) transcriptomic features during the course of E. huxleyi blooms induced in seawater-based mesocosm enclosures. Host bloom development and subsequent coccolithovirus infection was associated with a major shift in transcriptional profile. In addition to the expected metabolic requirements typically associated with viral infection (amino acid and nucleotide metabolism, as well as transcription- and replication-associated functions), the results strongly suggest that the manipulation of lipid metabolism plays a fundamental role during host-virus interaction. The results herein reveal the scale, so far massively underestimated, of the transcriptional domination that occurs during coccolithovirus infection in the natural environment. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  6. Emiliania huxleyi endures N-limitation with an efficient metabolic budgeting and effective ATP synthesis.

    Science.gov (United States)

    Rokitta, Sebastian D; Von Dassow, Peter; Rost, Björn; John, Uwe

    2014-12-02

    Global change will affect patterns of nutrient upwelling in marine environments, potentially becoming even stricter regulators of phytoplankton primary productivity. To better understand phytoplankton nutrient utilization on the subcellular basis, we assessed the transcriptomic responses of the life-cycle stages of the biogeochemically important microalgae Emiliania huxleyi to nitrogen-limitation. Cells grown in batch cultures were harvested at 'early' and 'full' nitrogen-limitation and were compared with non-limited cells. We applied microarray-based transcriptome profilings, covering ~10.000 known E. huxleyi gene models, and screened for expression patterns that indicate the subcellular responses. The diploid life-cycle stage scavenges nitrogen from external organic sources and -like diatoms- uses the ornithine-urea cycle to rapidly turn over cellular nitrogen. The haploid stage reacts similarly, although nitrogen scavenging is less pronounced and lipid oxidation is more prominent. Generally, polyamines and proline appear to constitute major organic pools that back up cellular nitrogen. Both stages induce a malate:quinone-oxidoreductase that efficiently feeds electrons into the respiratory chain and drives ATP generation with reduced respiratory carbon throughput. The use of the ornithine-urea cycle to budget the cellular nitrogen in situations of limitation resembles the responses observed earlier in diatoms. This suggests that underlying biochemical mechanisms are conserved among distant clades of marine phototrophic protists. The ornithine-urea cycle and proline oxidation appear to constitute a sensory-regulatory system that monitors and controls cellular nitrogen budgets under limitation. The similarity between the responses of the life-cycle stages, despite the usage of different genes, also indicates a strong functional consistency in the responses to nitrogen-limitation that appears to be owed to biochemical requirements. The malate

  7. Variability in the organic ligands released by Emiliania huxleyi under simulated ocean acidification conditions

    Directory of Open Access Journals (Sweden)

    Guillermo Samperio-Ramos

    2017-12-01

    Full Text Available The variability in the extracellular release of organic ligands by Emiliania huxleyi under four different pCO2 scenarios (225, 350, 600 and 900 μatm, was determined. Growth in the batch cultures was promoted by enriching them only with major nutrients and low iron concentrations. No chelating agents were added to control metal speciation. During the initial (IP, exponential (EP and steady (SP phases, extracellular release rates, normalized per cell and day, of dissolved organic carbon (DOCER, phenolic compounds (PhCER, dissolved combined carbohydrates (DCCHOER and dissolved uronic acids (DUAER in the exudates were determined. The growth rate decreased in the highest CO2 treatment during the IP (<48 h, but later increased when the exposure was longer (more than 6 days. DOCER did not increase significantly with high pCO2. Although no relationship was observed between DCCHOER and the CO2 conditions, DCCHO was a substantial fraction of the freshly released organic material, accounting for 18% to 37%, in EP, and 14% to 23%, in SP, of the DOC produced. Growth of E. huxleyi induced a strong response in the PhCER and DUAER. While in EP, PhCER were no detected, the DUAER remained almost constant for all CO2 treatments. Increases in the extracellular release of these organic ligands during SP were most pronounced under high pCO2 conditions. Our results imply that, during the final growth stage of E. huxleyi, elevated CO2 conditions will increase its excretion of acid polysaccharides and phenolic compounds, which may affect the biogeochemical behavior of metals in seawater.

  8. Ocean acidification affects redox-balance and ion-homeostasis in the life-cycle stages of Emiliania huxleyi.

    Directory of Open Access Journals (Sweden)

    Sebastian D Rokitta

    Full Text Available Ocean Acidification (OA has been shown to affect photosynthesis and calcification in the coccolithophore Emiliania huxleyi, a cosmopolitan calcifier that significantly contributes to the regulation of the biological carbon pumps. Its non-calcifying, haploid life-cycle stage was found to be relatively unaffected by OA with respect to biomass production. Deeper insights into physiological key processes and their dependence on environmental factors are lacking, but are required to understand and possibly estimate the dynamics of carbon cycling in present and future oceans. Therefore, calcifying diploid and non-calcifying haploid cells were acclimated to present and future CO(2 partial pressures (pCO(2; 38.5 Pa vs. 101.3 Pa CO(2 under low and high light (50 vs. 300 µmol photons m(-2 s(-1. Comparative microarray-based transcriptome profiling was used to screen for the underlying cellular processes and allowed to follow up interpretations derived from physiological data. In the diplont, the observed increases in biomass production under OA are likely caused by stimulated production of glycoconjugates and lipids. The observed lowered calcification under OA can be attributed to impaired signal-transduction and ion-transport. The haplont utilizes distinct genes and metabolic pathways, reflecting the stage-specific usage of certain portions of the genome. With respect to functionality and energy-dependence, however, the transcriptomic OA-responses resemble those of the diplont. In both life-cycle stages, OA affects the cellular redox-state as a master regulator and thereby causes a metabolic shift from oxidative towards reductive pathways, which involves a reconstellation of carbon flux networks within and across compartments. Whereas signal transduction and ion-homeostasis appear equally OA-sensitive under both light intensities, the effects on carbon metabolism and light physiology are clearly modulated by light availability. These interactive effects

  9. Ocean acidification affects redox-balance and ion-homeostasis in the life-cycle stages of Emiliania huxleyi.

    Science.gov (United States)

    Rokitta, Sebastian D; John, Uwe; Rost, Björn

    2012-01-01

    Ocean Acidification (OA) has been shown to affect photosynthesis and calcification in the coccolithophore Emiliania huxleyi, a cosmopolitan calcifier that significantly contributes to the regulation of the biological carbon pumps. Its non-calcifying, haploid life-cycle stage was found to be relatively unaffected by OA with respect to biomass production. Deeper insights into physiological key processes and their dependence on environmental factors are lacking, but are required to understand and possibly estimate the dynamics of carbon cycling in present and future oceans. Therefore, calcifying diploid and non-calcifying haploid cells were acclimated to present and future CO(2) partial pressures (pCO(2); 38.5 Pa vs. 101.3 Pa CO(2)) under low and high light (50 vs. 300 µmol photons m(-2) s(-1)). Comparative microarray-based transcriptome profiling was used to screen for the underlying cellular processes and allowed to follow up interpretations derived from physiological data. In the diplont, the observed increases in biomass production under OA are likely caused by stimulated production of glycoconjugates and lipids. The observed lowered calcification under OA can be attributed to impaired signal-transduction and ion-transport. The haplont utilizes distinct genes and metabolic pathways, reflecting the stage-specific usage of certain portions of the genome. With respect to functionality and energy-dependence, however, the transcriptomic OA-responses resemble those of the diplont. In both life-cycle stages, OA affects the cellular redox-state as a master regulator and thereby causes a metabolic shift from oxidative towards reductive pathways, which involves a reconstellation of carbon flux networks within and across compartments. Whereas signal transduction and ion-homeostasis appear equally OA-sensitive under both light intensities, the effects on carbon metabolism and light physiology are clearly modulated by light availability. These interactive effects can be

  10. Light intensity modulation by coccoliths of Emiliania huxleyi as a micro-photo-regulator

    Science.gov (United States)

    Mizukawa, Yuri; Miyashita, Yuito; Satoh, Manami; Shiraiwa, Yoshihiro; Iwasaka, Masakazu

    2015-09-01

    In this study, we present experimental evidence showing that coccoliths have light-scattering anisotropy that contributes to a possible control of solar light exposure in the ocean. Changing the angle between the incident light and an applied magnetic field causes differences in the light-scattering intensities of a suspension of coccoliths isolated from Emiliania huxleyi. The magnetic field effect is induced by the diamagnetic torque force directing the coccolith radial plane perpendicular to the applied magnetic fields at 400 to 500 mT. The developed technique reveals the light-scattering anisotropies in the 3-μm-diameter floating coccoliths by orienting themselves in response to the magnetic fields. The detached coccolith scatters radially the light incident to its radial plane. The experimental results on magnetically oriented coccoliths show that an individual coccolith has a specific direction of light scattering, although the possible physiological effect of the coccolith remains for further study, focusing on the light-scattering anisotropies of coccoliths on living cells.

  11. Grazing-Activated Production of Dimethyl Sulfide (DMS) by two clones of Emiliania huxleyi

    Science.gov (United States)

    Wolfe, Gordon V.; Steinke, Michael

    1996-01-01

    Emiliania huxleyi clones CCMP 370 and CCMP 373 produced similar amounts of dimethylsulfoniopropionate (DMSP) during axenic exponential growth, averaging 109 mM internal DMSP. Both clones had detectable DMSP lyase activity, as measured by production of dimethyl sulfide (DMS) during in vitro assays of crude cell preparations, but activities and conditions differed considerably between clones. Clone 373 had high activity; clone 370 had low activity and required chloride. For both strains, enzyme activity per cell was constant during exponential growth, but little DMS was produced by healthy cells. Rather, DMS production was activated when cells were subjected to physical or chemical stresses that caused cell lysis. We propose that DMSP lyase and DMSP are segregated within these cells and re-action only under conditions that result in cell stress or damage. Such activation occurs during microzooplankton grazing. When these clones were grazed by the dinoflagellate Oxyrrhis marina, DMS was produced; ungrazed cells, as well as those exposed to grazer exudates and associated bacteria, generated no DMS. Grazing of clone 373 produced much more DMS than grazing of clone 370, consistent with their relative in vitro DMSP lyase activities. DMS was only generated when cells were actually being grazed, indicating that ingested cells were responsible for the DMS formation. We suggest that even low levels of grazing can greatly accelerate DMS production.

  12. n-Nonacosadienes from the marine haptophytes Emiliania huxleyi and Gephyrocapsa oceanica.

    Science.gov (United States)

    Nakamura, Hideto; Sawada, Ken; Araie, Hiroya; Suzuki, Iwane; Shiraiwa, Yoshihiro

    2015-03-01

    The hydrocarbons in cultures of marine haptophytes Emiliania huxleyi NIES837 and Gephyrocapsa oceanica NIES1315 were analyzed, and nonacosadienes and hentriacontadienes were detected as the major compounds in both strains. C29 and C31 monoenes and di-, tri- and tetra-unsaturated C33 alkenes were also detected as minor compounds but not C37 and C38 alkenes. The positions of the double bonds in the C29 and C31 alkenes were determined by mass spectrometry of their dimethyl disulfide (DMDS) adducts. Among the four C29 alkenes identified, the most abundant isomer was 2,20-nonacosadiene, and the other three compounds were 1,20-nonacosadiene, 3,20-nonacosadiene and 9-nonacosene, respectively. Hitherto, 2,20-nonacosadiene and 3,20-nonacosadiene were unknown to be natural products. The double bond at the n-9 (ω9) position in these C29 alkenes is hypothesized to be derived from precursors of unsaturated fatty acids possessing an n-9 double bond, such as (9Z)-9-octadecenoic acid. Nonacosadienes have the potential for being used as distinct haptophyte biomarkers. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Shotgun proteomic analysis of Emiliania huxleyi, a marine phytoplankton species of major biogeochemical importance.

    Science.gov (United States)

    Jones, Bethan M; Edwards, Richard J; Skipp, Paul J; O'Connor, C David; Iglesias-Rodriguez, M Debora

    2011-06-01

    Emiliania huxleyi is a unicellular marine phytoplankton species known to play a significant role in global biogeochemistry. Through the dual roles of photosynthesis and production of calcium carbonate (calcification), carbon is transferred from the atmosphere to ocean sediments. Almost nothing is known about the molecular mechanisms that control calcification, a process that is tightly regulated within the cell. To initiate proteomic studies on this important and phylogenetically remote organism, we have devised efficient protein extraction protocols and developed a bioinformatics pipeline that allows the statistically robust assignment of proteins from MS/MS data using preexisting EST sequences. The bioinformatics tool, termed BUDAPEST (Bioinformatics Utility for Data Analysis of Proteomics using ESTs), is fully automated and was used to search against data generated from three strains. BUDAPEST increased the number of identifications over standard protein database searches from 37 to 99 proteins when data were amalgamated. Proteins involved in diverse cellular processes were uncovered. For example, experimental evidence was obtained for a novel type I polyketide synthase and for various photosystem components. The proteomic and bioinformatic approaches developed in this study are of wider applicability, particularly to the oceanographic community where genomic sequence data for species of interest are currently scarce.

  14. Draft genome sequence of four coccolithoviruses: Emiliania huxleyi virus EhV-88, EhV-201, EhV-207, and EhV-208.

    Science.gov (United States)

    Nissimov, Jozef I; Worthy, Charlotte A; Rooks, Paul; Napier, Johnathan A; Kimmance, Susan A; Henn, Matthew R; Ogata, Hiroyuki; Allen, Michael J

    2012-03-01

    The Coccolithoviridae are a group of viruses which infect the marine coccolithophorid microalga Emiliania huxleyi. The Emiliania huxleyi viruses (known as EhVs) described herein have 160- to 180-nm diameter icosahedral structures, have genomes of approximately 400 kbp, and consist of more than 450 predicted coding sequences (CDSs). Here, we describe the genomic features of four newly sequenced coccolithoviruses (EhV-88, EhV-201, EhV-207, and EhV-208) together with their draft genome sequences and their annotations, highlighting the homology and heterogeneity of these genomes to the EhV-86 model reference genome.

  15. Coccolithophore calcification response to past ocean acidification and climate change.

    Science.gov (United States)

    O'Dea, Sarah A; Gibbs, Samantha J; Bown, Paul R; Young, Jeremy R; Poulton, Alex J; Newsam, Cherry; Wilson, Paul A

    2014-11-17

    Anthropogenic carbon dioxide emissions are forcing rapid ocean chemistry changes and causing ocean acidification (OA), which is of particular significance for calcifying organisms, including planktonic coccolithophores. Detailed analysis of coccolithophore skeletons enables comparison of calcite production in modern and fossil cells in order to investigate biomineralization response of ancient coccolithophores to climate change. Here we show that the two dominant coccolithophore taxa across the Paleocene-Eocene Thermal Maximum (PETM) OA global warming event (~56 million years ago) exhibited morphological response to environmental change and both showed reduced calcification rates. However, only Coccolithus pelagicus exhibits a transient thinning of coccoliths, immediately before the PETM, that may have been OA-induced. Changing coccolith thickness may affect calcite production more significantly in the dominant modern species Emiliania huxleyi, but, overall, these PETM records indicate that the environmental factors that govern taxonomic composition and growth rate will most strongly influence coccolithophore calcification response to anthropogenic change.

  16. Pigment variations in Emiliania huxleyi (CCMP370) as a response to changes in light intensity or quality.

    Science.gov (United States)

    Garrido, José L; Brunet, Christophe; Rodríguez, Francisco

    2016-12-01

    Many studies on photoacclimation examine the pigment responses to changes in light intensity, but variations in light climate in the aquatic environment are also related to changes in spectral composition. We have employed a high-performance liquid chromatography method with improved resolution towards chlorophyll c and fucoxanthin-related xanthophylls to examine the pigment composition of Emiliania huxleyi CCMP 370 under different light intensities and spectral qualities. To maintain its photosynthetic performance, E. huxleyi CCMP370 promotes drastic pigment changes that can be either the interconversion of pigments in pools with the same basic chromophoric structure (Fucoxanthin type or chlorophyll c type), or the ex novo synthesis (Diatoxanthin). These changes are linked either to variations in light quality (Fucoxanthin related xanthophylls) or in light intensity (chlorophyll c 3 /Monovinyl chlorophyll c 3 , Diadinoxanthin/Diatoxanthin, β,ɛ-carotene/ β,β-carotene). Fucoxanthin and 19'-hexanoyloxyfucoxanthin proportions were highly dependent on spectral conditions. Whereas Fucoxanthin dominated in green and red light, 19'-hexanoyloxyfucoxanthin prevailed under blue spectral conditions. Our results suggest that the huge pigment diversity enhanced the photoacclimative capacities of E. huxleyi to efficiently perform under changing light environments. The ubiquity and success in the global ocean as well as the capacity of E. huxleyi to form large surface blooms might be associated to the plasticity described here. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

  17. Large effect of irradiance on hydrogen isotope fractionation of alkenones in Emiliania huxleyi

    Science.gov (United States)

    van der Meer, Marcel T. J.; Benthien, Albert; French, Katherine L.; Epping, Eric; Zondervan, Ingrid; Reichart, Gert-Jan; Bijma, Jelle; Sinninghe Damsté, Jaap S.; Schouten, Stefan

    2015-07-01

    The hydrogen isotopic (δD) composition of long-chain alkenones produced by certain haptophyte algae has been suggested as a potential proxy for reconstructing paleo sea surface salinity. However, environmental parameters other than salinity may also affect the δD of alkenones. We investigated the impact of the level of irradiance on hydrogen isotopic fractionation of alkenones versus growth water by cultivating two strains of the cosmopolitan haptophyte Emiliania huxleyi at different light intensities. The hydrogen isotope fractionation decreased by approximately 40‰ when irradiance was increased from 15 to 200 μmol photons m-2 s-1 above which it was relatively constant. The response is likely a direct effect of photosystem I and II activity as the relationship of the fractionation factor α versus light intensity can be described by an Eilers-Peeters photosynthesis model. This irradiance effect is in agreement with published δD data of alkenones derived from suspended particulate matter collected from different depths in the photic zone of the Gulf of California and the eastern tropical North Pacific. However, haptophyte algae tend to bloom at relatively high light intensities (>500 μmol photons m-2 s-1) occurring at the sea surface, at which hydrogen isotope fractionation is relatively constant and not affected by changes in light intensity. Alkenones accumulating in the sediment are likely mostly derived from these surface water haptophyte blooms, when the largest amount of biomass is produced. Therefore, the observed irradiance effect is unlikely to affect the applicability of the hydrogen isotopic composition of sedimentary long chain alkenones as a proxy for paleosalinity.

  18. Light-Dependent Transcriptional Regulation of Genes of Biogeochemical Interest in the Diploid and Haploid Life Cycle Stages of Emiliania huxleyi▿ †

    Science.gov (United States)

    Richier, Sophie; Kerros, Marie-Emmanuelle; de Vargas, Colomban; Haramaty, Liti; Falkowski, Paul G.; Gattuso, Jean-Pierre

    2009-01-01

    The expression of genes of biogeochemical interest in calcifying and noncalcifying life stages of the coccolithophore Emiliania huxleyi was investigated. Transcripts potentially involved in calcification were tested through a light-dark cycle. These transcripts were more abundant in calcifying cells and were upregulated in the light. Their application as potential candidates for in situ biogeochemical proxies is also suggested. PMID:19304825

  19. TEM preparation methods and influence of radiation damage on the beam sensitive CaCO3 shell of Emiliania huxleyi.

    Science.gov (United States)

    Hoffmann, Ramona; Wochnik, Angela S; Betzler, Sophia B; Matich, Sonja; Griesshaber, Erika; Schmahl, Wolfgang W; Scheu, Christina

    2014-07-01

    The ultrastructure of biologically formed calcium carbonate crystals like the shell of Emiliania huxleyi depends on the environmental conditions such as pH value, temperature and salinity. Therefore, they can be used as indicator for climate changes. However, for this a detailed understanding of their crystal structure and chemical composition is required. High resolution methods like transmission electron microscopy can provide those information on the nanoscale, given that sufficiently thin samples can be prepared. In our study, we developed sample preparation techniques for cross-section and plan-view investigations and studied the sample stability under electron bombardment. In addition to the biological material (Emiliania huxleyi) we also prepared mineralogical samples (Iceland spar) for comparison. High resolution transmission electron microscopy imaging, electron diffraction and electron energy-loss spectroscopy studies revealed that all prepared samples are relatively stable under electron bombardment at an acceleration voltage of 300 kV when using a parallel illumination. Above an accumulated dose of ∼10(5) e/nm2 the material--independent whether its origin is biological or geological--transformed to poly-crystalline calcium oxide. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Phylogenomic analysis of Emiliania huxleyi provides evidence for haptophyte-stramenopile association and a chimeric haptophyte nuclear genome.

    Science.gov (United States)

    Miller, John J; Delwiche, Charles F

    2015-06-01

    Emiliania huxleyi is a haptophyte alga of uncertain phylogenetic affinity containing a secondarily derived, chlorophyll c containing plastid. We sought to characterize its relationships with other taxa by quantifying the bipartitions in which it was included from a group of single protein phylogenetic trees in a way that allowed for variation in taxonomic content and accounted for paralogous sequences. The largest number of sequences supported a phylogenetic relationship of E. huxleyi with the stramenopiles, in particular Aureococcus anophagefferens. Far fewer nuclear sequences gave strong support to the placement of this coccolithophorid with the cryptophyte, Guillardia theta. The majority of the sequences that did support this relationship did not have plastid related functions. These results suggest that the haptophytes may be more closely allied with the heterokonts than with the cryptophytes. Another small set of genes associated E. huxleyi with the Viridiplantae with high support. While these genes could have been acquired with a plastid, the lack of plastid related functions among the proteins for which they code and the lack of other organisms with chlorophyll c containing plastids within these bipartitions suggests other explanations may be possible. This study also identified several genes that may have been transferred from the haptophyte lineage to the dinoflagellates Karenia brevis and Karlodinium veneficum as a result of their haptophyte derived plastid, including some with non-photosynthetic functions. Published by Elsevier B.V.

  1. Schrödinger’s Cheshire Cat: Are Haploid Emiliania huxleyi Cells Resistant to Viral Infection or Not?

    Directory of Open Access Journals (Sweden)

    Gideon J. Mordecai

    2017-03-01

    Full Text Available Emiliania huxleyi is the main calcite producer on Earth and is routinely infected by a virus (EhV; a double stranded DNA (dsDNA virus belonging to the family Phycodnaviridae. E. huxleyi exhibits a haplodiploid life cycle; the calcified diploid stage is non-motile and forms extensive blooms. The haploid phase is a non-calcified biflagellated cell bearing organic scales. Haploid cells are thought to resist infection, through a process deemed the “Cheshire Cat” escape strategy; however, a recent study detected the presence of viral lipids in the same haploid strain. Here we report on the application of an E. huxleyi CCMP1516 EhV-86 combined tiling array (TA that further confirms an EhV infection in the RCC1217 haploid strain, which grew without any signs of cell lysis. Reverse transcription polymerase chain reaction (RT-PCR and PCR verified the presence of viral RNA in the haploid cells, yet indicated an absence of viral DNA, respectively. These infected cells are an alternative stage of the virus life cycle deemed the haplococcolithovirocell. In this instance, the host is both resistant to and infected by EhV, i.e., the viral transcriptome is present in haploid cells whilst there is no evidence of viral lysis. This superimposed state is reminiscent of Schrödinger’s cat; of being simultaneously both dead and alive.

  2. Schrödinger's Cheshire Cat: Are Haploid Emiliania huxleyi Cells Resistant to Viral Infection or Not?

    Science.gov (United States)

    Mordecai, Gideon J; Verret, Frederic; Highfield, Andrea; Schroeder, Declan C

    2017-03-18

    Emiliania huxleyi is the main calcite producer on Earth and is routinely infected by a virus (EhV); a double stranded DNA (dsDNA) virus belonging to the family Phycodnaviridae . E. huxleyi exhibits a haplodiploid life cycle; the calcified diploid stage is non-motile and forms extensive blooms. The haploid phase is a non-calcified biflagellated cell bearing organic scales. Haploid cells are thought to resist infection, through a process deemed the "Cheshire Cat" escape strategy; however, a recent study detected the presence of viral lipids in the same haploid strain. Here we report on the application of an E. huxleyi CCMP1516 EhV-86 combined tiling array (TA) that further confirms an EhV infection in the RCC1217 haploid strain, which grew without any signs of cell lysis. Reverse transcription polymerase chain reaction (RT-PCR) and PCR verified the presence of viral RNA in the haploid cells, yet indicated an absence of viral DNA, respectively. These infected cells are an alternative stage of the virus life cycle deemed the haplococcolithovirocell. In this instance, the host is both resistant to and infected by EhV, i.e., the viral transcriptome is present in haploid cells whilst there is no evidence of viral lysis. This superimposed state is reminiscent of Schrödinger's cat; of being simultaneously both dead and alive.

  3. Schrödinger’s Cheshire Cat: Are Haploid Emiliania huxleyi Cells Resistant to Viral Infection or Not?

    Science.gov (United States)

    Mordecai, Gideon J.; Verret, Frederic; Highfield, Andrea; Schroeder, Declan C.

    2017-01-01

    Emiliania huxleyi is the main calcite producer on Earth and is routinely infected by a virus (EhV); a double stranded DNA (dsDNA) virus belonging to the family Phycodnaviridae. E. huxleyi exhibits a haplodiploid life cycle; the calcified diploid stage is non-motile and forms extensive blooms. The haploid phase is a non-calcified biflagellated cell bearing organic scales. Haploid cells are thought to resist infection, through a process deemed the “Cheshire Cat” escape strategy; however, a recent study detected the presence of viral lipids in the same haploid strain. Here we report on the application of an E. huxleyi CCMP1516 EhV-86 combined tiling array (TA) that further confirms an EhV infection in the RCC1217 haploid strain, which grew without any signs of cell lysis. Reverse transcription polymerase chain reaction (RT-PCR) and PCR verified the presence of viral RNA in the haploid cells, yet indicated an absence of viral DNA, respectively. These infected cells are an alternative stage of the virus life cycle deemed the haplococcolithovirocell. In this instance, the host is both resistant to and infected by EhV, i.e., the viral transcriptome is present in haploid cells whilst there is no evidence of viral lysis. This superimposed state is reminiscent of Schrödinger’s cat; of being simultaneously both dead and alive. PMID:28335465

  4. The effect of nitrate and phosphate availability on Emiliania huxleyi (NZEH) physiology under different CO2 scenarios.

    Science.gov (United States)

    Rouco, Mónica; Branson, Oscar; Lebrato, Mario; Iglesias-Rodríguez, M Débora

    2013-01-01

    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. Cells were exposed to different CO2 levels (ranging from 250 to 1314 μatm) under three nutrient conditions [nutrient replete (R), nitrate limited (-N), and phosphate limited (-P)]. We focused on calcite and organic carbon quotas and on nitrate and phosphate utilization by analyzing the activity of nitrate reductase (NRase) and alkaline phosphatase (APase), respectively. Particulate inorganic (PIC) and organic (POC) carbon quotas increased with increasing CO2 under R conditions but a different pattern was observed under nutrient limitation. The PIC:POC ratio decreased with increasing CO2 in nutrient limited cultures. Coccolith length increased with CO2 under all nutrient conditions but the coccosphere volume varied depending on the nutrient treatment. Maximum APase activity was found at 561 μatm of CO2 (pH 7.92) in -P cultures and in R conditions, NRase activity increased linearly with CO2. These results suggest that E. huxleyi's competitive ability for nutrient uptake might be altered in future high-CO2 oceans. The combined dataset will be useful in model parameterizations of the carbon cycle and ocean acidification.

  5. Abnormal carbonate diagenesis in Holocene-late Pleistocene sapropel-associated sediments from the Eastern Mediterranean; Evidence from Emiliania huxleyi coccolith morphology

    DEFF Research Database (Denmark)

    Crudeli, D.; Young, J.R.; Erba, E.

    2004-01-01

    In studying the Holocene-late Pleistocene record of the Eastern Mediterranean, considerable Emiliania huxleyi size/shape variation not clearly assignable to primary or secondary calcification was observed. Accordingly, different morphotypes were distinguished by light microscope (LM). A subsequent......, but also that they show effects of carbonate precipitation and dissolution much more clearly than other coccoliths. The relative abundances of the different LM-morphotypes were used to define an E. huxleyi overgrowth index (EXO) that qualitatively estimates carbonate precipitation/dissolution on coccoliths...

  6. Application of the major capsid protein as a marker of the phylogenetic diversity of Emiliania huxleyi viruses.

    Science.gov (United States)

    Rowe, Janet M; Fabre, Marie-Françoise; Gobena, Daniel; Wilson, William H; Wilhelm, Steven W

    2011-05-01

    Studies of the Phycodnaviridae have traditionally relied on the DNA polymerase (pol) gene as a biomarker. However, recent investigations have suggested that the major capsid protein (MCP) gene may be a reliable phylogenetic biomarker. We used MCP gene amplicons gathered across the North Atlantic to assess the diversity of Emiliania huxleyi-infecting Phycodnaviridae. Nucleotide sequences were examined across >6000 km of open ocean, with comparisons between concentrates of the virus-size fraction of seawater and of lysates generated by exposing host strains to these same virus concentrates. Analyses revealed that many sequences were only sampled once, while several were over-represented. Analyses also revealed nucleotide sequences distinct from previous coastal isolates. Examination of lysed cultures revealed a new richness in phylogeny, as MCP sequences previously unrepresented within the existing collection of E. huxleyi viruses (EhV) were associated with viruses lysing cultures. Sequences were compared with previously described EhV MCP sequences from the North Sea and a Norwegian Fjord, as well as from the Gulf of Maine. Principal component analysis indicates that location-specific distinctions exist despite the presence of sequences common across these environments. Overall, this investigation provides new sequence data and an assessment on the use of the MCP gene. © 2011 Federation of European Microbiological Societies Published by Blackwell Publishing Ltd. All rights reserved.

  7. Effect of salinity on 2H/1H fractionation in lipids from continuous cultures of the coccolithophorid Emiliania huxleyi

    Science.gov (United States)

    Sachs, Julian P.; Maloney, Ashley E.; Gregersen, Josh; Paschall, Christopher

    2016-09-01

    Salinity and temperature dictate the buoyancy of seawater, and by extension, ocean circulation and heat transport. Yet there remain few widely applicable proxies for salinity with the precision necessary to infer all but the largest hydrographic variations in the past. In the last decade the hydrogen isotope composition (2H/1H or δ2H) of microalgal lipids has been shown to increase systematically with salinity, providing a foundation for its use as a paleosalinity proxy. Culture and field studies have indicated a wide range of sensitivities for this response, ranging from about 0.6-3.3‰ ppt-1 depending on the lipid, location and/or culturing conditions. Lacking in these studies has been the controlled conditions necessary to isolate the response to salinity while keeping all other growth parameters constant. Here we show that the hydrogen isotope composition of lipids in the marine coccolithophorid Emiliania huxleyi grown in chemostats increased by 1.6 ± 0.3‰ ppt-1 (p huxleyi, which can be attributed to the fact that previous experiments were performed with batch cultures in which growth rates and other parameters differed between salinity treatments. The underlying cause of this response to salinity remains unknown, but may result from changes in (1) the proportion of lipid hydrogen derived from NADPH versus water, (2) the proportion of lipid hydrogen derived from NADPH from Photosystem I versus the oxidative pentose phosphate pathway (and other metabolic sources), or (3) the δ2H value of intracellular water.

  8. The effect of nitrate and phosphate availability on Emiliania huxleyi (NZEH physiology under different CO2 scenarios

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    Mónica eRouco

    2013-06-01

    Full Text Available 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. Cells were exposed to different CO2 levels (ranging from 250 to 1314 µatm under three nutrient conditions [nutrient replete (R, nitrate limited (-N and phosphate limited (-P]. We focused on calcite and organic carbon quotas and on nitrate and phosphate utilization by analyzing the activity of nitrate reductase (NRase and alkaline phosphatase (APase, respectively. Particulate inorganic (PIC and organic (POC carbon quotas increased with increasing CO2 under R conditions but a different pattern was observed under nutrient limitation. The PIC:POC ratio decreased with increasing CO2 in nutrient limited cultures. Coccolith length increased with CO2 under all nutrient conditions but the coccosphere volume varied depending on the nutrient treatment. Maximum APase activity was found at 561 µatm of CO2 (pH 7.92 in -P cultures and in R conditions, NRase activity increased linearly with CO2. These results suggest that E. huxleyi’s competitive ability for nutrient uptake might be altered in future high-CO2 oceans. The combined dataset will be useful in model parameterizations of the carbon cycle and ocean acidification.

  9. PHOTOINHIBITION OF PSII IN EMILIANIA HUXLEYI (HAPTOPHYTA) UNDER HIGH LIGHT STRESS: THE ROLES OF PHOTOACCLIMATION, PHOTOPROTECTION, AND PHOTOREPAIR(1).

    Science.gov (United States)

    Ragni, Maria; Airs, Ruth L; Leonardos, Nikos; Geider, Richard J

    2008-06-01

    The response of the coccolithophorid Emiliania huxleyi (Lohmann) W. H. Hay et H. Mohler to acute exposure to high photon flux densities (PFD) was examined in terms of PSII photoinhibition, photoprotection, and photorepair. The time and light dependencies of these processes were characterized as a function of the photoacclimation state of the alga. Low-light (LL) acclimated cells displayed a higher degree of photoinhibition, measured as decline in Fv /Fm , than high-light (HL) acclimated cells. However, HL cultures were more susceptible to photodamage but also more capable of compensating for it by performing a faster repair cycle. The relation between gross photoinhibition (observed in the presence of an inhibitor of repair) and PFD to which the algae were exposed deviated from linearity at high PFD, which calls into question the universality of current concepts of photoinhibition in mechanistic models. The light dependence of the de-epoxidation state (DPS) of the xanthophyll cycle (XC) pigments on the timescale of hours was the same in cells acclimated to LL and HL. However, HL cells were more efficient in realizing nonphotochemical quenching (NPQ) on short timescales, most likely due to a larger XC pool. LL cells displayed an increase in the PSII effective cross-section (σPSII ) as a result of photoinhibition, which was observed also in HL cells when net photoinhibition was induced by blocking the D1 repair cycle. The link between σPSII and photoinhibition suggests that the population of PSII reaction centers (RCIIs) of E. huxleyi shares a common antenna, according to a "lake" organization of the light-harvesting complex. © 2008 Phycological Society of America.

  10. Transcriptome analysis of functional differentiation between haploid and diploid cells of Emiliania huxleyi, a globally significant photosynthetic calcifying cell

    Science.gov (United States)

    2009-01-01

    Background Eukaryotes are classified as either haplontic, diplontic, or haplo-diplontic, depending on which ploidy levels undergo mitotic cell division in the life cycle. Emiliania huxleyi is one of the most abundant phytoplankton species in the ocean, playing an important role in global carbon fluxes, and represents haptophytes, an enigmatic group of unicellular organisms that diverged early in eukaryotic evolution. This species is haplo-diplontic. Little is known about the haploid cells, but they have been hypothesized to allow persistence of the species between the yearly blooms of diploid cells. We sequenced over 38,000 expressed sequence tags from haploid and diploid E. huxleyi normalized cDNA libraries to identify genes involved in important processes specific to each life phase (2N calcification or 1N motility), and to better understand the haploid phase of this prominent haplo-diplontic organism. Results The haploid and diploid transcriptomes showed a dramatic differentiation, with approximately 20% greater transcriptome richness in diploid cells than in haploid cells and only ≤ 50% of transcripts estimated to be common between the two phases. The major functional category of transcripts differentiating haploids included signal transduction and motility genes. Diploid-specific transcripts included Ca2+, H+, and HCO3- pumps. Potential factors differentiating the transcriptomes included haploid-specific Myb transcription factor homologs and an unusual diploid-specific histone H4 homolog. Conclusions This study permitted the identification of genes likely involved in diploid-specific biomineralization, haploid-specific motility, and transcriptional control. Greater transcriptome richness in diploid cells suggests they may be more versatile for exploiting a diversity of rich environments whereas haploid cells are intrinsically more streamlined. PMID:19832986

  11. Increased CO2 and the effect of pH on growth and calcification of Pleurochrysis carterae and Emiliania huxleyi (Haptophyta) in semicontinuous cultures.

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    Moheimani, Navid R; Borowitzka, Michael A

    2011-05-01

    The effects of changes in CO(2) and pH on biomass productivity and carbon uptake of Pleurochrysis carterae and Emiliania huxleyi in open raceway ponds and a plate photobioreactor were studied. The pH of P. carterae cultures increased during day and decreased at night, whereas the pH of E. huxleyi cultures showed no significant diurnal changes. P. carterae coccolith production occurs during the dark period, whereas in E. huxleyi, coccolith production is mainly during the day. Addition of CO(2) at constant pH (pH-stat) resulted in an increase in P. carterae biomass and coccolith productivity, while CO(2) addition lowered E. huxleyi biomass and coccolith production. Neither of these algae could grow at less than pH 7.5. Species-specific diurnal pH and pCO(2) variations could be indicative of significant differences in carbon uptake between these two species. While E. huxleyi has been suggested to be predominantly a bicarbonate user, our results indicate that P. carterae may be using CO(2) as the main C source for photosynthesis and calcification.

  12. Indole-3-Acetic Acid Is Produced by Emiliania huxleyi Coccolith-Bearing Cells and Triggers a Physiological Response in Bald Cells.

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    Labeeuw, Leen; Khey, Joleen; Bramucci, Anna R; Atwal, Harjot; de la Mata, A Paulina; Harynuk, James; Case, Rebecca J

    2016-01-01

    Indole-3-acetic acid (IAA) is an auxin produced by terrestrial plants which influences development through a variety of cellular mechanisms, such as altering cell orientation, organ development, fertility, and cell elongation. IAA is also produced by bacterial pathogens and symbionts of plants and algae, allowing them to manipulate growth and development of their host. They do so by either producing excess exogenous IAA or hijacking the IAA biosynthesis pathway of their host. The endogenous production of IAA by algae remains contentious. Using Emiliania huxleyi, a globally abundant marine haptophyte, we investigated the presence and potential role of IAA in algae. Homologs of genes involved in several tryptophan-dependent IAA biosynthesis pathways were identified in E. huxleyi. This suggests that this haptophyte can synthesize IAA using various precursors derived from tryptophan. Addition of L-tryptophan to E. huxleyi stimulated IAA production, which could be detected using Salkowski's reagent and GC × GC-TOFMS in the C cell type (coccolith bearing), but not in the N cell type (bald). Various concentrations of IAA were exogenously added to these two cell types to identify a physiological response in E. huxleyi. The N cell type, which did not produce IAA, was more sensitive to it, showing an increased variation in cell size, membrane permeability, and a corresponding increase in the photosynthetic potential quantum yield of Photosystem II (PSII). A roseobacter (bacteria commonly associated with E. huxleyi) Ruegeria sp. R11, previously shown to produce IAA, was co-cultured with E. huxleyi C and N cells. IAA could not be detected from these co-cultures, and even when stimulated by addition of L-tryptophan, they produced less IAA than axenic C type culture similarly induced. This suggests that IAA plays a novel role signaling between different E. huxleyi cell types, rather than between a bacteria and its algal host.

  13. Viral infection of the marine alga Emiliania huxleyi triggers lipidome remodeling and induces the production of highly saturated triacylglycerol.

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    Malitsky, Sergey; Ziv, Carmit; Rosenwasser, Shilo; Zheng, Shuning; Schatz, Daniella; Porat, Ziv; Ben-Dor, Shifra; Aharoni, Asaph; Vardi, Assaf

    2016-04-01

    Viruses that infect marine photosynthetic microorganisms are major ecological and evolutionary drivers of microbial food webs, estimated to turn over more than a quarter of the total photosynthetically fixed carbon. Viral infection of the bloom-forming microalga Emiliania huxleyi induces the rapid remodeling of host primary metabolism, targeted towards fatty acid metabolism. We applied a liquid chromatography-mass spectrometry (LC-MS)-based lipidomics approach combined with imaging flow cytometry and gene expression profiling to explore the impact of viral-induced metabolic reprogramming on lipid composition. Lytic viral infection led to remodeling of the cellular lipidome, by predominantly inducing the biosynthesis of highly saturated triacylglycerols (TAGs), coupled with a significant accumulation of neutral lipids within lipid droplets. Furthermore, TAGs were found to be a major component (77%) of the lipidome of isolated virions. Interestingly, viral-induced TAGs were significantly more saturated than TAGs produced under nitrogen starvation. This study highlights TAGs as major products of the viral-induced metabolic reprogramming during the host-virus interaction and indicates a selective mode of membrane recruitment during viral assembly, possibly by budding of the virus from specialized subcellular compartments. These findings provide novel insights into the role of viruses infecting microalgae in regulating metabolism and energy transfer in the marine environment and suggest their possible biotechnological application in biofuel production. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

  14. The effect of oil sands process-affected water and model naphthenic acids on photosynthesis and growth in Emiliania huxleyi and Chlorella vulgaris.

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    Beddow, Jessica; Johnson, Richard J; Lawson, Tracy; Breckels, Mark N; Webster, Richard J; Smith, Ben E; Rowland, Steven J; Whitby, Corinne

    2016-02-01

    Naphthenic acids (NAs) are among the most toxic organic pollutants present in oil sands process waters (OSPW) and enter marine and freshwater environments through natural and anthropogenic sources. We investigated the effects of the acid extractable organic (AEO) fraction of OSPW and individual surrogate NAs, on maximum photosynthetic efficiency of photosystem II (PSII) (FV/FM) and cell growth in Emiliania huxleyi and Chlorella vulgaris as representative marine and freshwater phytoplankton. Whilst FV/FM in E. huxleyi and C. vulgaris was not inhibited by AEO, exposure to two surrogate NAs: (4'-n-butylphenyl)-4-butanoic acid (n-BPBA) and (4'-tert-butylphenyl)-4-butanoic acid (tert-BPBA), caused complete inhibition of FV/FM in E. huxleyi (≥10 mg L(-1)n-BPBA; ≥50 mg L(-1)tert-BPBA) but not in C. vulgaris. Growth rates and cell abundances in E. huxleyi were also reduced when exposed to ≥10 mg L(-1)n- and tert-BPBA; however, higher concentrations of n- and tert-BPBA (100 mg L(-1)) were required to reduce cell growth in C. vulgaris. AEO at ≥10 mg L(-1) stimulated E. huxleyi growth rate (p ≤ 0.002), yet had no apparent effect on C. vulgaris. In conclusion, E. huxleyi was generally more sensitive to NAs than C. vulgaris. This report provides a better understanding of the physiological responses of phytoplankton to NAs which will enable improved monitoring of NA pollution in aquatic ecosystems in the future. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  15. Competition for inorganic and organic forms of nitrogen and phosphorous between phytoplankton and bacteria during an Emiliania huxleyi spring bloom

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    V. Martin-Jézéquel

    2008-03-01

    Full Text Available Using 15N and 33P, we measured the turnover of organic and inorganic nitrogen (N and phosphorus (P substrates, and the partitioning of N and P from these sources into two size fractions of marine osmotrophs during the course of a phytoplankton bloom in a nutrient manipulated mesocosm. The larger size fraction (>0.8 μm, mainly consisting of the coccolithophorid Emiliania huxleyi, but also including an increasing amount of large particle-associated bacteria as the bloom proceeded, dominated uptake of the inorganic forms NH4+, NO3−, and PO43−. The uptake of N from leucine, and P from ATP and dissolved DNA, was initially dominated by the 0.8–0.2 μm size fraction, but shifted towards dominance by the >0.8 μm size fraction as the system turned to an increasing degree of N-deficiency. Normalizing uptake to biomass of phytoplankton and heterotrophic bacteria revealed that organisms in the 0.8–0.2 μm size fraction had higher specific affinity for leucine-N than those in the >0.8 μm size fraction when N was deficient, whereas the opposite was the case for NH4+. There was no such difference regarding the specific affinity for P substrates. Since heterotrophic bacteria seem to acquire N from organic compounds like leucine more efficiently than phytoplankton, our results suggest different structuring of the microbial food chain in N-limited relative to P-limited environments.

  16. Growth and Mortality of Coccolithophores during spring in the Celtic Sea

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    Mayers, K.; Poulton, A. J.; Giering, S. L. C.; Daniels, C. J.; Wells, S. R.; Tarran, G.

    2016-02-01

    Coccolithophores are an important group of single celled protists which dominate pelagic calcite production, however little is currently known about the mortality rates within this group, or their importance in shelf seas regarding productivity and nutrient recycling. Measurements of coccolithophore calcification and cellular calcite quotas, as well as dilution experiments for microzooplankton grazing rates, were made during a spring cruise (April, 2015) in the Celtic Sea (NW European Shelf) and within an April bloom of Emiliania huxleyi. Calcite production and coccolithophore cell numbers showed a general positive trend throughout the progression of the spring bloom, ranging from 15 - 34µmol C m-3d-1 and 6 - 94 cells ml-1. Cell normalised calcification rates declined from 3 - 0.6 pmol C cell-1d-1 due to a shift from a mixed community to an E. huxleyi dominated one. Within the E. huxleyi bloom we recorded high daily calcite production (6049 µmol C m-3d-1) and cell normalised calcification of 3 pmol C cell-1d-1. This is significantly higher than E. huxleyi dominated sites in the Iceland Basin and more similar to a bloom on the Patagonian Shelf. Within the E. huxleyi bloom, mortality rates were 0.23 d-1 compared with growth rates of 0.29 d-1, meaning 80% of daily calcification was removed by grazers. In this study, coccolithophore mortality rates are presented from the central Celtic Sea throughout spring, and compared with an April E. huxleyi bloom in terms of species composition, trends in calcite production and composition of the phytoplankton community. These observations will potentially elucidate the role grazing plays in the fate of calcium carbonate, bloom formation and community composition.

  17. The effect of temperature, salinity and growth rate on the stable hydrogen isotopic composition of long chain alkenones produced by Emiliania huxleyi and Gephyrocapsa oceanica

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    S. Schouten

    2006-01-01

    Full Text Available Two haptophyte algae, Emiliania huxleyi and Gephyrocapsa oceanica, were cultured at different temperatures and salinities to investigate the impact of these factors on the hydrogen isotopic composition of long chain alkenones synthesized by these algae. Results showed that alkenones synthesized by G. oceanica were on average depleted in D by 30 compared to those of E. huxleyi when grown under similar temperature and salinity conditions. The fractionation factor, αalkenones-H2O, ranged from 0.760 to 0.815 for E. huxleyi and from 0.741 to 0.788 for G. oceanica. There was no significant correlation of αalkenones-H2O with temperature but a positive linear correlation was observed between αalkenones-H2O and salinity with ~3 change in fractionation per salinity unit and a negative correlation between αalkenones-H2O and growth rate. This suggests that both salinity and growth rate can have a substantial impact on the stable hydrogen isotopic composition of long chain alkenones in natural environments.

  18. Targeted and Untargeted Lipidomics of Emiliania huxleyi Viral Infection and Life Cycle Phases Highlights Molecular Biomarkers of Infection, Susceptibility, and Ploidy

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    Jonathan Eliott Hunter

    2015-10-01

    Full Text Available Marine viruses that infect phytoplankton strongly influence the ecology and evolution of their hosts. Emiliania huxleyi is characterized by a biphasic life cycle composed of a diploid (2N and haploid (1N phase; diploid cells are susceptible to infection by specific coccolithoviruses, yet haploid cells are resistant. Glycosphingolipids (GSLs play a role during infection, but their molecular distribution in haploid cells is unknown. We present mass spectrometric analyses of lipids from cultures of uninfected diploid, infected diploid, and uninfected haploid E. huxleyi. Known viral GSLs were present in the infected diploid cultures as expected, but surprisingly, trace amounts of viral GSLs were also detected in the uninfected haploid cells. Sialic-acid GSLs have been linked to viral susceptibility in diploid cells, but were found to be absent in the haploid cultures, suggesting a mechanism of haploid resistance to infection. Additional untargeted high-resolution mass spectrometry data processed via multivariate analysis unveiled a number of novel biomarkers of infected, non-infected, and haploid cells. These data expand our understanding on the dynamics of lipid metabolism during E. huxleyi host/virus interactions and highlight potential novel biomarkers for infection, susceptibility, and ploidy.

  19. Gas-Chromatography Mass-Spectrometry (GC-MS Based Metabolite Profiling Reveals Mannitol as a Major Storage Carbohydrate in the Coccolithophorid Alga Emiliania huxleyi

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    Alisdair R. Fernie

    2013-03-01

    Full Text Available Algae are divergent organisms having a wide variety of evolutional histories. Although most of them share photosynthetic activity, their pathways of primary carbon metabolism are rather diverse among species. Here we developed a method for gas chromatography-mass spectroscopy (GC-MS based metabolite profiling for the coccolithophorid alga Emiliania huxleyi, which is one of the most abundant microalgae in the ocean, in order to gain an overview of the pathway of primary metabolism within this alga. Following method optimization, twenty-six metabolites could be detected by this method. Whilst most proteogenic amino acids were detected, no peaks corresponding to malate and fumarate were found. The metabolite profile of E. huxleyi was, however, characterized by a prominent accumulation of mannitol reaching in excess of 14 nmol 106 cells−1. Similarly, the accumulation of the 13C label during short term H13CO3− feeding revealed a massive redistribution of label into mannitol as well as rapid but saturating label accumulation into glucose and several amino acids including aspartate, glycine and serine. These results provide support to previous work suggesting that this species adopts C3 photosynthesis and that mannitol functions as a carbon store in E. huxleyi.

  20. Acclimation of Emiliania huxleyi (1516) to nutrient limitation involves precise modification of the proteome to scavenge alternative sources of N and P.

    Science.gov (United States)

    McKew, Boyd A; Metodieva, Gergana; Raines, Christine A; Metodiev, Metodi V; Geider, Richard J

    2015-10-01

    Limitation of marine primary production by the availability of nitrogen or phosphorus is common. Emiliania huxleyi, a ubiquitous phytoplankter that plays key roles in primary production, calcium carbonate precipitation and production of dimethyl sulfide, often blooms in mid-latitude at the beginning of summer when inorganic nutrient concentrations are low. To understand physiological mechanisms that allow such blooms, we examined how the proteome of E. huxleyi (strain 1516) responds to N and P limitation. We observed modest changes in much of the proteome despite large physiological changes (e.g. cellular biomass, C, N and P) associated with nutrient limitation of growth rate. Acclimation to nutrient limitation did however involve significant increases in the abundance of transporters for ammonium and nitrate under N limitation and for phosphate under P limitation. More notable were large increases in proteins involved in the acquisition of organic forms of N and P, including urea and amino acid/polyamine transporters and numerous C-N hydrolases under N limitation and a large upregulation of alkaline phosphatase under P limitation. This highly targeted reorganization of the proteome towards scavenging organic forms of macronutrients gives unique insight into the molecular mechanisms that underpin how E. huxleyi has found its niche to bloom in surface waters depleted of inorganic nutrients. © 2015 The Authors. Environmental Microbiology published by Society for Applied Microbiology and John Wiley & Sons Ltd.

  1. Intraspecific Adaptations to Thermal Gradients in a Cosmopolitan Coccolithophore

    Science.gov (United States)

    Matson, P. G.; Ladd, T. M.; Iglesias-Rodriguez, D.

    2016-02-01

    The species concept in marine phytoplankton has enormous biological complexity. Differences in genomic, morphological, physiological, biogeochemical, and ecological/biogeographic properties between strains of the same species can be comparable or even exceed those between species. This complexity is particularly pronounced in the cosmopolitan coccolithophore species Emiliania huxleyi. This bloom-forming species is found at nearly every latitude in a variety of environments including upwelling regions, and exposed to large temperature gradients. We present results from experiments using two strains of E. huxleyi isolated from different latitudes and environmental conditions. Tests involved semi-continuous culturing in lab manipulation experiments to determine how carbon fixation, growth, and morphology respond to temperature-driven alterations in physico-chemical conditions. This talk will discuss the observed differences in physiology within an ecological context and the implications of these biogeochemical differences in modeling carbon fluxes driven by phytoplankton.

  2. Coccolithophore responses to environmental variability in the South China Sea: species composition and calcite content

    Science.gov (United States)

    Jin, Xiaobo; Liu, Chuanlian; Poulton, Alex J.; Dai, Minhan; Guo, Xianghui

    2016-08-01

    Coccolithophore contributions to the global marine carbon cycle are regulated by the calcite content of their scales (coccoliths) and the relative cellular levels of photosynthesis and calcification rates. All three of these factors vary between coccolithophore species and with response to the growth environment. Here, water samples were collected in the northern basin of the South China Sea (SCS) during summer 2014 in order to examine how environmental variability influenced species composition and cellular levels of calcite content. Average coccolithophore abundance and their calcite concentration in the water column were 11.82 cells mL-1 and 1508.3 pg C mL-1, respectively, during the cruise. Water samples can be divided into three floral groups according to their distinct coccolithophore communities. The vertical structure of the coccolithophore community in the water column was controlled by the trophic conditions, which were regulated by mesoscale eddies across the SCS basin. The evaluation of coccolithophore-based calcite in the surface ocean also showed that three key species in the SCS (Emiliania huxleyi, Gephyrocapsa oceanica, Florisphaera profunda) and other larger, numerically rare species made almost equal contributions to total coccolith-based calcite in the water column. For Emiliania huxleyi biometry measurements, coccolith size positively correlated with nutrients (nitrate, phosphate), and it is suggested that coccolith length is influenced by light and nutrients through the regulation of growth rates. Larger-sized coccoliths were also linked statistically to low pH and calcite saturation states; however, it is not a simple cause and effect relationship, as carbonate chemistry was strongly co-correlated with the other key environmental factors (nutrients, light).

  3. Morphological and Phylogenetic Characterization of New Gephyrocapsa Isolates Suggests Introgressive Hybridization in the Emiliania/Gephyrocapsa Complex (Haptophyta).

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    Bendif, El Mahdi; Probert, Ian; Young, Jeremy R; von Dassow, Peter

    2015-07-01

    The coccolithophore genus Gephyrocapsa contains a cosmopolitan assemblage of pelagic species, including the bloom-forming Gephyrocapsa oceanica, and is closely related to the emblematic coccolithophore Emiliania huxleyi within the Noëlaerhabdaceae. These two species have been extensively studied and are well represented in culture collections, whereas cultures of other species of this family are lacking. We report on three new strains of Gephyrocapsa isolated into culture from samples from the Chilean coastal upwelling zone using a novel flow cytometric single-cell sorting technique. The strains were characterized by morphological analysis using scanning electron microscopy and phylogenetic analysis of 6 genes (nuclear 18S and 28S rDNA, plastidial 16S and tufA, and mitochondrial cox1 and cox3 genes). Morphometric features of the coccoliths indicate that these isolates are distinct from G. oceanica and best correspond to G. muellerae. Surprisingly, both plastidial and mitochondrial gene phylogenies placed these strains within the E. huxleyi clade and well separated from G. oceanica isolates, making Emiliania appear polyphyletic. The only nuclear sequence difference, 1bp in the 28S rDNA region, also grouped E. huxleyi with the new Gephyrocapsa isolates and apart from G. oceanica. Specifically, the G. muellerae morphotype strains clustered with the mitochondrial β clade of E. huxleyi, which, like G. muellerae, has been associated with cold (temperate and sub-polar) waters. Among putative evolutionary scenarios that could explain these results we discuss the possibility that E. huxleyi is not a valid taxonomic unit, or, alternatively the possibility of past hybridization and introgression between each E. huxleyi clade and older Gephyrocapsa clades. In either case, the results support the transfer of Emiliania to Gephyrocapsa. These results have important implications for relating morphological species concepts to ecological and evolutionary units of diversity

  4. Seasonal and interannual variations in coccolithophore abundance off Terceira Island, Azores (Central North Atlantic)

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    Narciso, Áurea; Gallo, Francesca; Valente, André; Cachão, Mário; Cros, Lluïsa; Azevedo, Eduardo B.; e Ramos, Joana Barcelos

    2016-04-01

    In order to characterize the natural coccolithophore community occurring offshore Azores and to determine their annual and interannual patterns, monthly samples were collected, from September 2010 to December 2014, in the photic zone off Terceira Island. The present study revealed a clear seasonal distribution and a considerable interannual variability of the living coccolithophore community. The highest coccolithophore abundances were observed during spring and winter months, especially due to the smaller species Emiliania huxleyi and Gephyrocapsa ericsonii. In fact, the highest biomass period was registered during April 2011, associated with enhanced abundance of the overcalcified morphotype of E. huxleyi, which was possibly influenced by subpolar waters and subsequent upwelling conditions. The highest abundances of Gephyrocapsa muellerae were recorded during June 2011 and 2014, indicating that this species characterizes the transition between the period of maximum productivity and the subsequent smoother environmental conditions, the first and the later stages of the phytoplankton succession described by Margalef, respectively. During summer to early fall, a gradual decrease of the overall coccolithophore abundance was observed, while the species richness (Margalef diversity index) increased. A subtropical coccolithophore assemblage mainly composed by Umbellosphaera tenuis, Syracosphaera spp., Discosphaera tubifera, Rhabdosphaera clavigera and Coronosphaera mediterranea indicated the presence of surface warmer waters accompanied by reduced mixing and low nutrients concentration. During late fall to winter, the coccolithophore abundance increased again with a concomitant reduction in species diversity. This is potentially linked to low sea surface temperatures, moderate nutrients concentration and surface mixed layer deepening. During 2011, colder and productive waters led to an increase in the total coccolithophore abundances. On contrary, during 2012

  5. Modeling and Simulation of Optimal Resource Management during the Diurnal Cycle in Emiliania huxleyi by Genome-Scale Reconstruction and an Extended Flux Balance Analysis Approach.

    Science.gov (United States)

    Knies, David; Wittmüß, Philipp; Appel, Sebastian; Sawodny, Oliver; Ederer, Michael; Feuer, Ronny

    2015-10-28

    The coccolithophorid unicellular alga Emiliania huxleyi is known to form large blooms, which have a strong effect on the marine carbon cycle. As a photosynthetic organism, it is subjected to a circadian rhythm due to the changing light conditions throughout the day. For a better understanding of the metabolic processes under these periodically-changing environmental conditions, a genome-scale model based on a genome reconstruction of the E. huxleyi strain CCMP 1516 was created. It comprises 410 reactions and 363 metabolites. Biomass composition is variable based on the differentiation into functional biomass components and storage metabolites. The model is analyzed with a flux balance analysis approach called diurnal flux balance analysis (diuFBA) that was designed for organisms with a circadian rhythm. It allows storage metabolites to accumulate or be consumed over the diurnal cycle, while keeping the structure of a classical FBA problem. A feature of this approach is that the production and consumption of storage metabolites is not defined externally via the biomass composition, but the result of optimal resource management adapted to the diurnally-changing environmental conditions. The model in combination with this approach is able to simulate the variable biomass composition during the diurnal cycle in proximity to literature data.

  6. Effects of alkalinity and salinity at low and high light intensity on hydrogen isotope fractionation of long-chain alkenones produced by Emiliania huxleyi

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    G. M. Weiss

    2017-12-01

    Full Text Available Over the last decade, hydrogen isotopes of long-chain alkenones have been shown to be a promising proxy for reconstructing paleo sea surface salinity due to a strong hydrogen isotope fractionation response to salinity across different environmental conditions. However, to date, the decoupling of the effects of alkalinity and salinity, parameters that co-vary in the surface ocean, on hydrogen isotope fractionation of alkenones has not been assessed. Furthermore, as the alkenone-producing haptophyte, Emiliania huxleyi, is known to grow in large blooms under high light intensities, the effect of salinity on hydrogen isotope fractionation under these high irradiances is important to constrain before using δDC37 to reconstruct paleosalinity. Batch cultures of the marine haptophyte E. huxleyi strain CCMP 1516 were grown to investigate the hydrogen isotope fractionation response to salinity at high light intensity and independently assess the effects of salinity and alkalinity under low-light conditions. Our results suggest that alkalinity does not significantly influence hydrogen isotope fractionation of alkenones, but salinity does have a strong effect. Additionally, no significant difference was observed between the fractionation responses to salinity recorded in alkenones grown under both high- and low-light conditions. Comparison with previous studies suggests that the fractionation response to salinity in culture is similar under different environmental conditions, strengthening the use of hydrogen isotope fractionation as a paleosalinity proxy.

  7. Modeling and Simulation of Optimal Resource Management during the Diurnal Cycle in Emiliania huxleyi by Genome-Scale Reconstruction and an Extended Flux Balance Analysis Approach

    Directory of Open Access Journals (Sweden)

    David Knies

    2015-10-01

    Full Text Available The coccolithophorid unicellular alga Emiliania huxleyi is known to form large blooms, which have a strong effect on the marine carbon cycle. As a photosynthetic organism, it is subjected to a circadian rhythm due to the changing light conditions throughout the day. For a better understanding of the metabolic processes under these periodically-changing environmental conditions, a genome-scale model based on a genome reconstruction of the E. huxleyi strain CCMP 1516 was created. It comprises 410 reactions and 363 metabolites. Biomass composition is variable based on the differentiation into functional biomass components and storage metabolites. The model is analyzed with a flux balance analysis approach called diurnal flux balance analysis (diuFBA that was designed for organisms with a circadian rhythm. It allows storage metabolites to accumulate or be consumed over the diurnal cycle, while keeping the structure of a classical FBA problem. A feature of this approach is that the production and consumption of storage metabolites is not defined externally via the biomass composition, but the result of optimal resource management adapted to the diurnally-changing environmental conditions. The model in combination with this approach is able to simulate the variable biomass composition during the diurnal cycle in proximity to literature data.

  8. Effects of alkalinity and salinity at low and high light intensity on hydrogen isotope fractionation of long-chain alkenones produced by Emiliania huxleyi

    Science.gov (United States)

    Weiss, Gabriella M.; Pfannerstill, Eva Y.; Schouten, Stefan; Sinninghe Damsté, Jaap S.; van der Meer, Marcel T. J.

    2017-12-01

    Over the last decade, hydrogen isotopes of long-chain alkenones have been shown to be a promising proxy for reconstructing paleo sea surface salinity due to a strong hydrogen isotope fractionation response to salinity across different environmental conditions. However, to date, the decoupling of the effects of alkalinity and salinity, parameters that co-vary in the surface ocean, on hydrogen isotope fractionation of alkenones has not been assessed. Furthermore, as the alkenone-producing haptophyte, Emiliania huxleyi, is known to grow in large blooms under high light intensities, the effect of salinity on hydrogen isotope fractionation under these high irradiances is important to constrain before using δDC37 to reconstruct paleosalinity. Batch cultures of the marine haptophyte E. huxleyi strain CCMP 1516 were grown to investigate the hydrogen isotope fractionation response to salinity at high light intensity and independently assess the effects of salinity and alkalinity under low-light conditions. Our results suggest that alkalinity does not significantly influence hydrogen isotope fractionation of alkenones, but salinity does have a strong effect. Additionally, no significant difference was observed between the fractionation responses to salinity recorded in alkenones grown under both high- and low-light conditions. Comparison with previous studies suggests that the fractionation response to salinity in culture is similar under different environmental conditions, strengthening the use of hydrogen isotope fractionation as a paleosalinity proxy.

  9. The trade-off between the light-harvesting and photoprotective functions of fucoxanthin-chlorophyll proteins dominates light acclimation in Emiliania huxleyi (clone CCMP 1516).

    Science.gov (United States)

    McKew, Boyd A; Davey, Phillip; Finch, Stewart J; Hopkins, Jason; Lefebvre, Stephane C; Metodiev, Metodi V; Oxborough, Kevin; Raines, Christine A; Lawson, Tracy; Geider, Richard J

    2013-10-01

    Mechanistic understanding of the costs and benefits of photoacclimation requires knowledge of how photophysiology is affected by changes in the molecular structure of the chloroplast. We tested the hypothesis that changes in the light dependencies of photosynthesis, nonphotochemical quenching and PSII photoinactivation arises from changes in the abundances of chloroplast proteins in Emiliania huxleyi strain CCMP 1516 grown at 30 (Low Light; LL) and 1000 (High Light; HL) μmol photons m(-2) s(-1) photon flux densities. Carbon-specific light-saturated gross photosynthesis rates were not significantly different between cells acclimated to LL and HL. Acclimation to LL benefited cells by increasing biomass-specific light absorption and gross photosynthesis rates under low light, whereas acclimation to HL benefited cells by reducing the rate of photoinactivation of PSII under high light. Differences in the relative abundances of proteins assigned to light-harvesting (Lhcf), photoprotection (LI818-like), and the photosystem II (PSII) core complex accompanied differences in photophysiology: specifically, Lhcf:PSII was greater under LL, whereas LI818:PSII was greater in HL. Thus, photoacclimation in E. huxleyi involved a trade-off amongst the characteristics of light absorption and photoprotection, which could be attributed to changes in the abundance and composition of proteins in the light-harvesting antenna of PSII. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

  10. Enzymological evidence for the function of a plastid-located pyruvate carboxylase in the Haptophyte alga Emiliania huxleyi: a novel pathway for the production of C4 compounds.

    Science.gov (United States)

    Tsuji, Yoshinori; Suzuki, Iwane; Shiraiwa, Yoshihiro

    2012-06-01

    Pyruvate carboxylase (PYC) catalyzes the β-carboxylation of pyruvate to yield oxaloacetate (OAA). We previously isolated a cDNA encoding a putative PYC (EhPYC1) from the haptophyte alga Emiliania huxleyi and then proposed that EhPYC1 contributes to active anaplerotic β-carboxylation during photosynthesis although PYC activity was not detected in the cell extracts. Involvement of PYC in photosynthetic carbon metabolism is unique, since PYC generally functions in non-photosynthetic organisms. In the present study, we demonstrate that EhPYC1 is highly sensitive to endogenous proteases and therefore is easily degraded in cell extracts. By avoiding proteolytic degradation, PYC activity can be detected in the cell extracts of E. huxleyi. The activity of a recombinant His-tagged EhPYC1 expressed in Streptomyces lividans was inhibited by l-malate in a mixed non-competitive manner. Immunofluorescence labeling showed that EhPYC1 is located in the plastid. This result agrees with the prediction that a bipartite plastid-targeting signal is present that functions to deliver proteins into the four-membrane plastid of haptophyte algae. This is the first finding of a plastid-located PYC. These results indicate that E. huxleyi possesses a unique pathway to produce OAA catalyzed by PYC, and the pathway may provide carbon skeletons for amino acid biosynthesis in the plastid. A database search indicates that PYC genes are widespread in green algae, diatoms and brown algae, suggesting the crucial role of PYC in various aquatic phototrophs.

  11. Coccolithophore assemblage response to Black Sea Water inflow into the North Aegean Sea (NE Mediterranean)

    Science.gov (United States)

    Karatsolis, B.-Th.; Triantaphyllou, M. V.; Dimiza, M. D.; Malinverno, E.; Lagaria, A.; Mara, P.; Archontikis, O.; Psarra, S.

    2017-10-01

    This study aims to presents the species composition of living coccolithophore communities in the NE Aegean Sea, investigating their spatial and temporal variations along a north-south transect in the area receiving the inflowing surface Black Sea Water (BSW) over the deeper Levantine Water (LW) layer. Coccolithophores in the area were relatively diverse and a total of 95 species over 3 sampling periods studied were recognized using Scanning Electron Microscope (SEM) techniques. R-mode hierarchical cluster analysis distinguished two coccolithophore Groups (I, IIa, IIb, IIc) with different ecological preferences. Emiliania huxleyi was the most abundant species of Group I, whereas Syracosphaera spp., Rhabdosphaera spp. and holococcolithophores were prevailing in the highly diversified Group II assemblages. Biometric analysis conducted on E. huxleyi coccoliths from Aegean water column and Black Sea sediment trap samples, indicated that during autumn, NE Aegean specimens in samples under BSW influence were featured by unimodal distribution concerning the coccolith relative tube width, with values similar to those provided by the Black Sea specimens. In early spring, coccoliths in the stations with increased BSW influx displayed a bimodal pattern of relative tube width with smaller values found mostly in the surface layers, while the distribution became again unimodal and dominated by larger values within the deeper LW layers. In the summer period, the typical LW holococcolithophore species (Group II) presented low cell numbers in the surface layer (huxleyi was almost absent in the NE Aegean during the summer sampling period.

  12. Pan genome of the phytoplankton Emiliania underpins its global distribution.

    Science.gov (United States)

    Read, Betsy A; Kegel, Jessica; Klute, Mary J; Kuo, Alan; Lefebvre, Stephane C; Maumus, Florian; Mayer, Christoph; Miller, John; Monier, Adam; Salamov, Asaf; Young, Jeremy; Aguilar, Maria; Claverie, Jean-Michel; Frickenhaus, Stephan; Gonzalez, Karina; Herman, Emily K; Lin, Yao-Cheng; Napier, Johnathan; Ogata, Hiroyuki; Sarno, Analissa F; Shmutz, Jeremy; Schroeder, Declan; de Vargas, Colomban; Verret, Frederic; von Dassow, Peter; Valentin, Klaus; Van de Peer, Yves; Wheeler, Glen; Dacks, Joel B; Delwiche, Charles F; Dyhrman, Sonya T; Glöckner, Gernot; John, Uwe; Richards, Thomas; Worden, Alexandra Z; Zhang, Xiaoyu; Grigoriev, Igor V

    2013-07-11

    Coccolithophores have influenced the global climate for over 200 million years. These marine phytoplankton can account for 20 per cent of total carbon fixation in some systems. They form blooms that can occupy hundreds of thousands of square kilometres and are distinguished by their elegantly sculpted calcium carbonate exoskeletons (coccoliths), rendering them visible from space. Although coccolithophores export carbon in the form of organic matter and calcite to the sea floor, they also release CO2 in the calcification process. Hence, they have a complex influence on the carbon cycle, driving either CO2 production or uptake, sequestration and export to the deep ocean. Here we report the first haptophyte reference genome, from the coccolithophore Emiliania huxleyi strain CCMP1516, and sequences from 13 additional isolates. Our analyses reveal a pan genome (core genes plus genes distributed variably between strains) probably supported by an atypical complement of repetitive sequence in the genome. Comparisons across strains demonstrate that E. huxleyi, which has long been considered a single species, harbours extensive genome variability reflected in different metabolic repertoires. Genome variability within this species complex seems to underpin its capacity both to thrive in habitats ranging from the equator to the subarctic and to form large-scale episodic blooms under a wide variety of environmental conditions.

  13. Pan Genome of the Phytoplankton Emiliania Underpins its Global Distribution

    Energy Technology Data Exchange (ETDEWEB)

    Read, Betsy A. [California State Univ. (CalState), San Marcos, CA (United States); Kegel, Jessica [Alfred Wegener Inst. for Polar and Marine Research, Bremerhaven (Germany); Klute, Mary J. [Univ. of Alberta, Edmonton, AB (Canada); Kuo, Alan [USDOE Joint Genome Inst., Walnut Creek, CA (United States); Lefebvre, Stephane C. [J. Craig Venter Inst., San Diego, CA (United States); Maumus, Florian [National Institute of Agricultural Research, Versailles (France); Mayer, Christoph [Alexander Koenig Research Museum, Bonn (Germany); Ruhr Univ., Bochum (Germany); Miller, John [Univ. of Maryland, College Park, MD (United States); Monier, Adam [Monterey Bay Aquarium Research Inst., Moss Landing, CA (United States); Salamov, Asaf [USDOE Joint Genome Inst., Walnut Creek, CA (United States); Young, Jeremy [Univ. College London (United Kingdom); Aguilar, Maria [Univ. of Alberta, Edmonton, AB (Canada); Claverie, Jean-Michel [Aix-Marseille Univ. (France); Frickenhaus, Stephan [Alfred Wegener Inst. for Polar and Marine Research, Bremerhaven (Germany); Univ. of Bremerhaven (Germany); Gonzalez, Karina [Harvard Medical School, Boston, MA (United States); Herman, Emily K. [Univ. of Alberta, Edmonton, AB (Canada); Lin, Yao-Cheng [Ghent Univ. (Belgium); Napier, Johnathan [Rothamstead Research, Harpenden (United Kingdom); Ogata, Hiroyuki [Aix-Marseille Univ. (France); Sarno, Analissa F. [California State Univ. (CalState), San Marcos, CA (United States); Schmutz, Jeremy [USDOE Joint Genome Inst., Walnut Creek, CA (United States); HudsonAlpha Genome Sequencing Center, Huntsville, AL (United States); Schroeder, Declan [Marine Biological Association of the UK, Plymouth (United Kingdom); de Vargas, Columban [CNRS. Univ. Pierre and Marie Curie (France).; Verret, Frederic [Univ. of Essex, Colchester (United Kingdom); von Dassow, Peter [Pontifical Catholic University of Chile, Santiago (Chile); Valentin, Klaus [Alfred Wegener Inst. for Polar and Marine Research, Bremerhaven (Germany); Van de Peer, Yves [Ghent Univ. (Belgium); Wheeler, Glen [Marine Biological Association of the UK, Plymouth (United Kingdom); Plymouth Marine Lab. (United Kingdom); Annotation Consortium, Emiliania huxleyi; Dacks, Joel B. [Univ. of Alberta, Edmonton, AB (Canada); Delwiche, Charles F. [Univ. of Maryland, College Park, MD (United States); Dyhrman, Sonya T. [Woods Hole Oceanographic Inst., MA (United States); Columbia Univ., Palisades, NY (United States); Glockner, Gernot [Univ. of Cologne (Germany); John, Uwe [Alfred Wegener Inst. for Polar and Marine Research, Bremerhaven (Germany); Richards, Thomas [National History Museum, London (United Kingdom); Worden, Alexandra Z. [Monterey Bay Aquarium Research Inst., Moss Landing, CA (United States); Zhang, Xiaoyu [California State Univ. (CalState), San Marcos, CA (United States); Grigoriev, Igor V. [USDOE Joint Genome Inst., Walnut Creek, CA (United States)

    2012-06-18

    Coccolithophores have influenced the global climate for over 200 million years1. These marine phytoplankton can account for 20 per cent of total carbon fixation in some systems2. They form blooms that can occupy hundreds of thousands of square kilometres and are distinguished by their elegantly sculpted calcium carbonate exoskeletons (coccoliths), rendering themvisible fromspace3.Although coccolithophores export carbon in the form of organic matter and calcite to the sea floor, they also release CO2 in the calcification process. Hence, they have a complex influence on the carbon cycle, driving either CO2 production or uptake, sequestration and export to the deep ocean4. Here we report the first haptophyte reference genome, from the coccolithophore Emiliania huxleyi strain CCMP1516, and sequences from 13 additional isolates. Our analyses reveal a pan genome (core genes plus genes distributed variably between strains) probably supported by an atypical complement of repetitive sequence in the genome. Comparisons across strains demonstrate thatE. huxleyi, which has long been considered a single species, harbours extensive genome variability reflected in different metabolic repertoires. Genome variability within this species complex seems to underpin its capacity both to thrive in habitats ranging from the equator to the subarctic and to form large-scale episodic blooms under a wide variety of environmental conditions.

  14. Stable carbon isotope signals in particulate organic and inorganic carbon of coccolithophores - A numerical model study for Emiliania huxleyi.

    Science.gov (United States)

    Holtz, Lena-Maria; Wolf-Gladrow, Dieter; Thoms, Silke

    2017-05-07

    A recent numerical cell model, which explains observed light and carbonate system effects on particulate organic and inorganic carbon (POC and PIC) production rates under the assumption of internal pH homeostasis, is extended for stable carbon isotopes ( 12 C, 13 C). Aim of the present study is to mechanistically understand the stable carbon isotopic fractionation signal (ε) in POC and PIC and furthermore the vital effect(s) included in measured ε PIC values. The virtual cell is divided into four compartments, for each of which the 12 C as well as the 13 C carbonate system kinetics are implemented. The compartments are connected to each other via trans-membrane fluxes. In contrast to existing carbon fractionation models, the presented model calculates the disequilibrium state for both carbonate systems and for each compartment. It furthermore calculates POC and PIC production rates as well as ε POC and ε PIC as a function of given light conditions and the compositions of the external carbonate system. Measured POC and PIC production rates as well as ε PIC values are reproduced well by the model (comparison with literature data). The observed light effect on ε POC (increase of ε POC with increasing light intensities), however, is not reproduced by the basic model set-up, which is solely based on RubisCO fractionation. When extending the latter set-up by assuming that biological fractionation includes further carbon fractionation steps besides the one of RubisCO, the observed light effect on ε POC is also reproduced. By means of the extended model version, four different vital effects that superimpose each other in a real cell can be detected. Finally, we discuss potential limitations of the ε PIC proxy. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Impact of trace metal concentrations on coccolithophore growth and morphology: laboratory simulations of Cretaceous stress

    Science.gov (United States)

    Faucher, Giulia; Hoffmann, Linn; Bach, Lennart T.; Bottini, Cinzia; Erba, Elisabetta; Riebesell, Ulf

    2017-07-01

    The Cretaceous ocean witnessed intervals of profound perturbations such as volcanic input of large amounts of CO2, anoxia, eutrophication and introduction of biologically relevant metals. Some of these extreme events were characterized by size reduction and/or morphological changes of a few calcareous nannofossil species. The correspondence between intervals of high trace metal concentrations and coccolith dwarfism suggests a negative effect of these elements on nannoplankton biocalcification processes in past oceans. In order to test this hypothesis, we explored the potential effect of a mixture of trace metals on growth and morphology of four living coccolithophore species, namely Emiliania huxleyi, Gephyrocapsa oceanica, Pleurochrysis carterae and Coccolithus pelagicus. The phylogenetic history of coccolithophores shows that the selected living species are linked to Mesozoic species showing dwarfism under excess metal concentrations. The trace metals tested were chosen to simulate the environmental stress identified in the geological record and upon known trace metal interactions with living coccolithophore algae.Our laboratory experiments demonstrated that elevated trace metal concentrations, similarly to the fossil record, affect coccolithophore algae size and/or weight. Smaller coccoliths were detected in E. huxleyi and C. pelagicus, while coccoliths of G. oceanica showed a decrease in size only at the highest trace metal concentrations. P. carterae coccolith size was unresponsive to changing trace metal concentrations. These differences among species allow discriminating the most- (P. carterae), intermediate- (E. huxleyi and G. oceanica) and least-tolerant (C. pelagicus) taxa. The fossil record and the experimental results converge on a selective response of coccolithophores to metal availability.These species-specific differences must be considered before morphological features of coccoliths are used to reconstruct paleo-chemical conditions.

  16. Impact of trace metal concentrations on coccolithophore growth and morphology: laboratory simulations of Cretaceous stress

    Directory of Open Access Journals (Sweden)

    G. Faucher

    2017-07-01

    Full Text Available The Cretaceous ocean witnessed intervals of profound perturbations such as volcanic input of large amounts of CO2, anoxia, eutrophication and introduction of biologically relevant metals. Some of these extreme events were characterized by size reduction and/or morphological changes of a few calcareous nannofossil species. The correspondence between intervals of high trace metal concentrations and coccolith dwarfism suggests a negative effect of these elements on nannoplankton biocalcification processes in past oceans. In order to test this hypothesis, we explored the potential effect of a mixture of trace metals on growth and morphology of four living coccolithophore species, namely Emiliania huxleyi, Gephyrocapsa oceanica, Pleurochrysis carterae and Coccolithus pelagicus. The phylogenetic history of coccolithophores shows that the selected living species are linked to Mesozoic species showing dwarfism under excess metal concentrations. The trace metals tested were chosen to simulate the environmental stress identified in the geological record and upon known trace metal interactions with living coccolithophore algae.Our laboratory experiments demonstrated that elevated trace metal concentrations, similarly to the fossil record, affect coccolithophore algae size and/or weight. Smaller coccoliths were detected in E. huxleyi and C. pelagicus, while coccoliths of G. oceanica showed a decrease in size only at the highest trace metal concentrations. P. carterae coccolith size was unresponsive to changing trace metal concentrations. These differences among species allow discriminating the most- (P. carterae, intermediate- (E. huxleyi and G. oceanica and least-tolerant (C. pelagicus taxa. The fossil record and the experimental results converge on a selective response of coccolithophores to metal availability.These species-specific differences must be considered before morphological features of coccoliths are used to reconstruct paleo-chemical conditions.

  17. Coccolithophore populations and their contribution to carbonate export during an annual cycle in the Australian sector of the Antarctic zone

    Science.gov (United States)

    Rigual Hernández, Andrés S.; Flores, José A.; Sierro, Francisco J.; Fuertes, Miguel A.; Cros, Lluïsa; Trull, Thomas W.

    2018-03-01

    The Southern Ocean is experiencing rapid and relentless change in its physical and biogeochemical properties. The rate of warming of the Antarctic Circumpolar Current exceeds that of the global ocean, and the enhanced uptake of carbon dioxide is causing basin-wide ocean acidification. Observational data suggest that these changes are influencing the distribution and composition of pelagic plankton communities. Long-term and annual field observations on key environmental variables and organisms are a critical basis for predicting changes in Southern Ocean ecosystems. These observations are particularly needed, since high-latitude systems have been projected to experience the most severe impacts of ocean acidification and invasions of allochthonous species. Coccolithophores are the most prolific calcium-carbonate-producing phytoplankton group playing an important role in Southern Ocean biogeochemical cycles. Satellite imagery has revealed elevated particulate inorganic carbon concentrations near the major circumpolar fronts of the Southern Ocean that can be attributed to the coccolithophore Emiliania huxleyi. Recent studies have suggested changes during the last decades in the distribution and abundance of Southern Ocean coccolithophores. However, due to limited field observations, the distribution, diversity and state of coccolithophore populations in the Southern Ocean remain poorly characterised. We report here on seasonal variations in the abundance and composition of coccolithophore assemblages collected by two moored sediment traps deployed at the Antarctic zone south of Australia (2000 and 3700 m of depth) for 1 year in 2001-2002. Additionally, seasonal changes in coccolith weights of E. huxleyi populations were estimated using circularly polarised micrographs analysed with C-Calcita software. Our findings indicate that (1) coccolithophore sinking assemblages were nearly monospecific for E. huxleyi morphotype B/C in the Antarctic zone waters in 2001-2002; (2

  18. Detection of a variable intracellular acid-labile carbon pool in Thalassiosira weissflogii (Heterokontophyta) and Emiliania huxleyi (Haptophyta) in response to changes in the seawater carbon system.

    Science.gov (United States)

    Isensee, Kirsten; Erez, Jonathan; Stoll, Heather M

    2014-02-01

    Accumulation of an intracellular pool of carbon (C(i) pool) is one strategy by which marine algae overcome the low abundance of dissolved CO2 (CO2 (aq) ) in modern seawater. To identify the environmental conditions under which algae accumulate an acid-labile C(i) pool, we applied a (14) C pulse-chase method, used originally in dinoflagellates, to two new classes of algae, coccolithophorids and diatoms. This method measures the carbon accumulation inside the cells without altering the medium carbon chemistry or culture cell density. We found that the diatom Thalassiosira weissflogii [(Grunow) G. Fryxell & Hasle] and a calcifying strain of the coccolithophorid Emiliania huxleyi [(Lohmann) W. W. Hay & H. P. Mohler] develop significant acid-labile C(i) pools. C(i) pools are measureable in cells cultured in media with 2-30 µmol l(-1) CO2 (aq), corresponding to a medium pH of 8.6-7.9. The absolute C(i) pool was greater for the larger celled diatoms. For both algal classes, the C(i) pool became a negligible contributor to photosynthesis once CO2 (aq) exceeded 30 µmol l(-1) . Combining the (14) C pulse-chase method and (14) C disequilibrium method enabled us to assess whether E. huxleyi and T. weissflogii exhibited thresholds for foregoing accumulation of DIC or reduced the reliance on bicarbonate uptake with increasing CO2 (aq) . We showed that the C(i) pool decreases with higher CO2 :HCO3 (-) uptake rates. © 2013 Scandinavian Plant Physiology Society.

  19. Covariation of metabolic rates and cell size in coccolithophores

    Science.gov (United States)

    Aloisi, G.

    2015-08-01

    Coccolithophores are sensitive recorders of environmental change. The size of their coccosphere varies in the ocean along gradients of environmental conditions and provides a key for understanding the fate of this important phytoplankton group in the future ocean. But interpreting field changes in coccosphere size in terms of laboratory observations is hard, mainly because the marine signal reflects the response of multiple morphotypes to changes in a combination of environmental variables. In this paper I examine the large corpus of published laboratory experiments with coccolithophores looking for relations between environmental conditions, metabolic rates and cell size (a proxy for coccosphere size). I show that growth, photosynthesis and, to a lesser extent, calcification covary with cell size when pCO2, irradiance, temperature, nitrate, phosphate and iron conditions change. With the exception of phosphate and temperature, a change from limiting to non-limiting conditions always results in an increase in cell size. An increase in phosphate or temperature (below the optimum temperature for growth) produces the opposite effect. The magnitude of the coccosphere-size changes observed in the laboratory is comparable to that observed in the ocean. If the biological reasons behind the environment-metabolism-size link are understood, it will be possible to use coccosphere-size changes in the modern ocean and in marine sediments to investigate the fate of coccolithophores in the future ocean. This reasoning can be extended to the size of coccoliths if, as recent experiments are starting to show, coccolith size reacts to environmental change proportionally to coccosphere size. The coccolithophore database is strongly biased in favour of experiments with the coccolithophore Emiliania huxleyi (E. huxleyi; 82 % of database entries), and more experiments with other species are needed to understand whether these observations can be extended to coccolithophores in general. I

  20. Unusual Δ7,12,19 C35:3 Alkenone Produced by the Mutant Emiliania huxleyi strain CCMP2758 in Culture

    Science.gov (United States)

    Zheng, Y.; Huang, Y.; Zhang, Y.; Dillon, J. T.

    2015-12-01

    Alkenones with chain length ranging from C37 to C40 are highly specific biomarkers for certain haptophyte algae in ocean and lake sediments and have been widely used for paleoclimate studies. Short chain alkenones (e.g., C35 and C36) have been found in environmental and culture samples but the origin and structures of these compounds are not fully understood. The benchmark marine alkenone producer, Emiliania huxleyi CCMP2758 strain (the mutant of strain CCMP1742, NEPCC55a) was reported to make 35:2 alkenone when cultured at 15 °C (Prahl et al., 2006). Here we show, when this strain is cultured at lower temperatures (e.g., 4°C), CCMP2758 produces large amount of 35:3 alkenone with unusual double bond positions of Δ7,12,19. We determined the double bond positions of the C35:3 methyl ketonee based on GC-MS analysis of cyclobutylimine derivatives and dimethyl disulfide derivatives respectively, and provide the first temperature calibrations based on the unsaturation ratios of C35 alkenones. Previous studies have found 35:2 alkenone with three methylene interruption in the Black Sea sediment, but it is the first time that an alkenone with a mixed three and five methylene interruption is found. The discovery of short chain alkenones with unusual double bond positions may shed new light to alkenone biosynthesis.

  1. Effects of long-term high CO2 exposure on two species of coccolithophores

    Directory of Open Access Journals (Sweden)

    K. G. Schulz

    2010-03-01

    Full Text Available The physiological performance of two coccolithophore species, Emiliania huxleyi and Coccolithus braarudii, was investigated during long-term exposure to elevated pCO2 levels. Mono-specific cultures were grown over 152 (E. huxleyi and 65 (C. braarudii generations while pCO2 was gradually increased to maximum levels of 1150 μatm (E. huxleyi and 930 μatm (C. braarudii and kept constant thereafter. Rates of cell growth and cell quotas of particulate organic carbon (POC, particulate inorganic carbon (PIC and total particulate nitrogen (TPN were determined repeatedly throughout the incubation period. Increasing pCO2 caused a decrease in cell growth rate of 9% and 29% in E. huxleyi and C. braarudii, respectively. In both species cellular PIC:TPN and PIC:POC ratios decreased in response to rising pCO2, whereas no change was observed in the POC:TPN ratios of E. huxleyi and C. braarudii. These results are consistent with those obtained in shorter-term high CO2 exposure experiments following abrupt pertubations of the seawater carbonate system and indicate that for the strains tested here a gradual CO2 increase does not alleviate CO2/pH sensitivity.

  2. Satellite Evidence that E. huxleyi Phytoplankton Blooms Weaken Marine Carbon Sinks

    Science.gov (United States)

    Kondrik, D. V.; Pozdnyakov, D. V.; Johannessen, O. M.

    2018-01-01

    Phytoplankton blooms of the coccolithophore Emiliania huxleyi are known to produce CO2, causing less uptake of atmospheric CO2 by the ocean, but a global assessment of this phenomenon has so far not been quantified. Therefore, here we quantify the increase in CO2 partial pressure (ΔpCO2) at the ocean surface within E. huxleyi blooms for polar and subpolar seas using an 18 year ocean color time series (1998-2015). When normalized to pCO2 in the absence of bloom, the mean and maximum ΔpCO2 values within the bloom areas varied between 21.0%-43.3% and 31.6%-62.5%, respectively. These results might have appreciable implications for climatology, marine chemistry, and ecology.

  3. Recent reticulate evolution in the ecologically dominant lineage of coccolithophores

    Directory of Open Access Journals (Sweden)

    El Mahdi eBendif

    2016-05-01

    Full Text Available The coccolithophore family Noëlaerhabdaceae contains a number of taxa that are very abundant in modern oceans, including the cosmopolitan bloom-forming Emiliania huxleyi. Introgressive hybridization has been suggested to account for incongruences between nuclear, mitochondrial and plastidial phylogenies of morphospecies within this lineage, but the number of species cultured to date remains rather limited. Here, we present the characterization of 5 new Noëlaerhabdaceae culture strains isolated from samples collected in the south-east Pacific Ocean. These were analyzed morphologically using scanning electron microscopy and phylogenetically by sequencing 5 marker genes (nuclear 18S and 28S rDNA, plastidial tufA, and mitochondrial cox1 and cox3 genes. Morphologically, one of these strains corresponded to Gephyrocapsa ericsonii and the four others to Reticulofenestra parvula. Ribosomal gene sequences were near identical between these new strains, but divergent from G. oceanica, G. muellerae and E. huxleyi. In contrast to the clear distinction in ribosomal phylogenies, sequences from other genomic compartments clustered with those of E. huxleyi strains with which they share an ecological range (i.e. warm temperate to tropical waters. These data provide strong support for the hypothesis of past (and potentially ongoing introgressive hybridization within this ecologically important lineage and for the transfer of R. parvula to Gephyrocapsa. These results have important implications for understanding the role of hybridization in speciation in vast ocean meta-populations of phytoplankton.

  4. Strong shift from HCO3 (-) to CO 2 uptake in Emiliania huxleyi with acidification: new approach unravels acclimation versus short-term pH effects.

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    Kottmeier, Dorothee M; Rokitta, Sebastian D; Tortell, Philippe D; Rost, Björn

    2014-09-01

    Effects of ocean acidification on Emiliania huxleyi strain RCC 1216 (calcifying, diploid life-cycle stage) and RCC 1217 (non-calcifying, haploid life-cycle stage) were investigated by measuring growth, elemental composition, and production rates under different pCO2 levels (380 and 950 μatm). In these differently acclimated cells, the photosynthetic carbon source was assessed by a (14)C disequilibrium assay, conducted over a range of ecologically relevant pH values (7.9-8.7). In agreement with previous studies, we observed decreased calcification and stimulated biomass production in diploid cells under high pCO2, but no CO2-dependent changes in biomass production for haploid cells. In both life-cycle stages, the relative contributions of CO2 and HCO3 (-) uptake depended strongly on the assay pH. At pH values ≤ 8.1, cells preferentially used CO2 (≥ 90 % CO2), whereas at pH values ≥ 8.3, cells progressively increased the fraction of HCO3 (-) uptake (~45 % CO2 at pH 8.7 in diploid cells; ~55 % CO2 at pH 8.5 in haploid cells). In contrast to the short-term effect of the assay pH, the pCO2 acclimation history had no significant effect on the carbon uptake behavior. A numerical sensitivity study confirmed that the pH-modification in the (14)C disequilibrium method yields reliable results, provided that model parameters (e.g., pH, temperature) are kept within typical measurement uncertainties. Our results demonstrate a high plasticity of E. huxleyi to rapidly adjust carbon acquisition to the external carbon supply and/or pH, and provide an explanation for the paradoxical observation of high CO2 sensitivity despite the apparently high HCO3 (-) usage seen in previous studies.

  5. Individual and interacting effects of pCO2 and temperature on Emiliania huxleyi calcification: study of the calcite production, the coccolith morphology and the coccosphere size

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    K. Sabbe

    2010-05-01

    Full Text Available The impact of ocean acidification and increased water temperature on marine ecosystems, in particular those involving calcifying organisms, has been gradually recognised. We examined the individual and combined effects of increased pCO2 (180 ppmV CO2, 380 ppmV CO2 and 750 ppmV CO2 corresponding to past, present and future CO2 conditions, respectively and temperature (13 °C and 18 °C during the exponential growth phase of the coccolithophore E. huxleyi using batch culture experiments. We showed that cellular production rate of Particulate Organic Carbon (POC increased from the present to the future CO2 treatments at 13 °C. A significant effect of pCO2 and of temperature on calcification was found, manifesting itself in a lower cellular production rate of Particulate Inorganic Carbon (PIC as well as a lower PIC:POC ratio at future CO2 levels and at 18 °C. Coccosphere-sized particles showed a size reduction with both increasing temperature and CO2 concentration. The influence of the different treatments on coccolith morphology was studied by categorizing SEM coccolith micrographs. The number of well-formed coccoliths decreased with increasing pCO2 while temperature did not have a significant impact on coccolith morphology. No interacting effects of pCO2 and temperature were observed on calcite production, coccolith morphology or on coccosphere size. Finally, our results suggest that ocean acidification might have a larger adverse impact on coccolithophorid calcification than surface water warming.

  6. Effect of coccolith polysaccharides isolated from the coccolithophorid, Emiliania huxleyi, on calcite crystal formation in in vitro CaCO3 crystallization.

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    Kayano, Keisuke; Saruwatari, Kazuko; Kogure, Toshihiro; Shiraiwa, Yoshihiro

    2011-02-01

    Marine coccolithophorids (Haptophyceae) produce calcified scales "coccoliths" which are composed of CaCO(3) and coccolith polysaccharides (CP) in the coccolith vesicles. CP was previously reported to be composed of uronic acids and sulfated residues, etc. attached to the polymannose main chain. Although anionic polymers are generally known to play key roles in biomineralization process, there is no experimental data how CP contributes to calcite crystal formation in the coccolithophorids. CP used was isolated from the most abundant coccolithophorid, Emiliania huxleyi. CaCO(3) crystallization experiment was performed on agar template layered onto a plastic plate that was dipped in the CaCO(3) crystallization solution. The typical rhombohedral calcite crystals were formed in the absence of CP. CaCO(3) crystals formed on the naked plastic plate were obviously changed to stick-like shapes when CP was present in the solution. EBSD analysis proved that the crystal is calcite of which c-axis was elongated. CP in the solution stimulated the formation of tabular crystals with flat edge in the agarose gel. SEM and FIB-TEM observations showed that the calcite crystals were formed in the gel. The formation of crystals without flat edge was stimulated when CP was preliminarily added in the gel. These observations suggest that CP has two functions: namely, one is to elongate the calcite crystal along c-axis and another is to induce tabular calcite crystal formation in the agarose gel. Thus, CP may function for the formation of highly elaborate species-specific structures of coccoliths in coccolithophorids.

  7. The influence of environmental variability on the biogeography of coccolithophores and diatoms in the Great Calcite Belt

    Science.gov (United States)

    Smith, Helen E. K.; Poulton, Alex J.; Garley, Rebecca; Hopkins, Jason; Lubelczyk, Laura C.; Drapeau, Dave T.; Rauschenberg, Sara; Twining, Ben S.; Bates, Nicholas R.; Balch, William M.

    2017-11-01

    The Great Calcite Belt (GCB) of the Southern Ocean is a region of elevated summertime upper ocean calcite concentration derived from coccolithophores, despite the region being known for its diatom predominance. The overlap of two major phytoplankton groups, coccolithophores and diatoms, in the dynamic frontal systems characteristic of this region provides an ideal setting to study environmental influences on the distribution of different species within these taxonomic groups. Samples for phytoplankton enumeration were collected from the upper mixed layer (30 m) during two cruises, the first to the South Atlantic sector (January-February 2011; 60° W-15° E and 36-60° S) and the second in the South Indian sector (February-March 2012; 40-120° E and 36-60° S). The species composition of coccolithophores and diatoms was examined using scanning electron microscopy at 27 stations across the Subtropical, Polar, and Subantarctic fronts. The influence of environmental parameters, such as sea surface temperature (SST), salinity, carbonate chemistry (pH, partial pressure of CO2 (pCO2), alkalinity, dissolved inorganic carbon), macronutrients (nitrate + nitrite, phosphate, silicic acid, ammonia), and mixed layer average irradiance, on species composition across the GCB was assessed statistically. Nanophytoplankton (cells 2-20 µm) were the numerically abundant size group of biomineralizing phytoplankton across the GCB, with the coccolithophore Emiliania huxleyi and diatoms Fragilariopsis nana, F. pseudonana, and Pseudo-nitzschia spp. as the most numerically dominant and widely distributed. A combination of SST, macronutrient concentrations, and pCO2 provided the best statistical descriptors of the biogeographic variability in biomineralizing species composition between stations. Emiliania huxleyi occurred in silicic acid-depleted waters between the Subantarctic Front and the Polar Front, a favorable environment for this species after spring diatom blooms remove silicic acid

  8. Reviews and Syntheses: Responses of coccolithophores to ocean acidification: a meta-analysis

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    Meyer, J.; Riebesell, U.

    2015-03-01

    Concerning their sensitivity to ocean acidification, coccolithophores, a group of calcifying single-celled phytoplankton, are one of the best-studied groups of marine organisms. However, in spite of the large number of studies investigating coccolithophore physiological responses to ocean acidification, uncertainties still remain due to variable and partly contradictory results. In the present study we have used all existing data in a meta-analysis to estimate the effect size of future pCO2 changes on the rates of calcification and photosynthesis and the ratio of particulate inorganic to organic carbon (PIC / POC) in different coccolithophore species. Our results indicate that ocean acidification has a negative effect on calcification and the cellular PIC / POC ratio in the two most abundant coccolithophore species: Emiliania huxleyi and Gephyrocapsa oceanica. In contrast, the more heavily calcified species Coccolithus braarudii did not show a distinct response when exposed to elevated pCO2/reduced pH. Photosynthesis in Gephyrocapsa oceanica was positively affected by high CO2, while no effect was observed for the other coccolithophore species. There was no indication that the method of carbonate chemistry manipulation was responsible for the inconsistent results regarding observed responses in calcification and the PIC / POC ratio. The perturbation method, however, appears to affect photosynthesis, as responses varied significantly between total alkalinity (TA) and dissolved inorganic carbon (DIC) manipulations. These results emphasize that coccolithophore species respond differently to ocean acidification, both in terms of calcification and photosynthesis. Where negative effects occur, they become evident at CO2 levels in the range projected for this century in the case of unabated CO2 emissions. As the data sets used in this meta-analysis do not account for adaptive responses, ecological fitness and ecosystem interactions, the question remains as to how these

  9. The Influence of Growth Rate on 2H/1H Fractionation in Continuous Cultures of the Coccolithophorid Emiliania huxleyi and the Diatom Thalassiosira pseudonana.

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    Sachs, Julian P; Kawka, Orest E

    2015-01-01

    The hydrogen isotope (2H/1H) ratio of lipids from phytoplankton is a powerful new tool for reconstructing hydroclimate variations in the geologic past from marine and lacustrine sediments. Water 2H/1H changes are reflected in lipid 2H/1H changes with R2 > 0.99, and salinity variations have been shown to cause about a 1‰ change in lipid δ2H values per unit (ppt) change in salinity. Less understood are the effects of growth rate, nutrient limitation and light on 2H/1H fractionation in phytoplankton. Here we present the first published study of growth rate effects on 2H/1H fractionation in the lipids of coccolithophorids grown in continuous cultures. Emiliania huxleyi was cultivated in steady state at four growth rates and the δ2H value of individual alkenones (C37:2, C37:3, C38:2, C38:3), fatty acids (C14:0, C16:0, C18:0), and 24-methyl cholest-5,22-dien-3β-ol (brassicasterol) were measured. 2H/1H fractionation increased in all lipids as growth rate increased by 24‰ to 79‰ (div d-1)-1. We attribute this response to a proportional increase in the fraction of NADPH from Photosystem I (PS1) of photosynthesis relative to NADPH from the cytosolic oxidative pentose phosphate (OPP) pathway in the synthesis of lipids as growth rate increases. A 3-endmember model is presented in which lipid hydrogen comes from NADPH produced in PS1, NADPH produced by OPP, and intracellular water. With published values or best estimates of the fractionation factors for these sources (αPS1 = 0.4, αOPP = 0.75, and αH2O = 0) and half of the hydrogen in a lipid derived from water the model indicates αlipid = 0.79. This value is within the range measured for alkenones (αalkenone = 0.77 to 0.81) and fatty acids (αFA = 0.75 to 0.82) in the chemostat cultures, but is greater than the range for brassicasterol (αbrassicasterol = 0.68 to 0.72). The latter is attributed to a greater proportion of hydrogen from NADPH relative to water in isoprenoid lipids. The model successfully explains

  10. Effect of Organic Fe-Ligands, Released by Emiliania huxleyi, on Fe(II Oxidation Rate in Seawater Under Simulated Ocean Acidification Conditions: A Modeling Approach

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    Guillermo Samperio-Ramos

    2018-06-01

    Full Text Available The potential effect of ocean acidification on the exudation of organic matter by phytoplankton and, consequently, on the iron redox chemistry is largely unknown. In this study, the coccolithophorid Emiliania huxleyi was exposed to different pCO2 conditions (225–900 μatm, in order to determine the role of natural organic ligands on the Fe(II oxidation rate. Oxidation kinetics of Fe(II were studied as a function of pH (7.75–8.25 and dissolved organic carbon levels produced (0–141.11 μmol C L−1 during the different growth stages. The Fe(II oxidation rate always decreased in the presence of exudates as compared to that in the exudates-free seawater. The organic ligands present in the coccolithophorid exudates were responsible for this decrease. The oxidation of Fe(II in artificial seawater was also investigated at nanomolar levels over a range of pH (7.75–8.25 at 25°C in the presence of different glucuronic acid concentrations. Dissolved uronic acids (DUA slightly increased the experimental rate compared to control artificial seawater (ASW which can be ascribed to the stabilization of the oxidized form by chelation. This behavior was a function of the Fe(II:DUA ratio and was a pH dependent process. A kinetic model in ASW, with a single organic ligand, was applied for computing the equilibrium constant (log KFeCHO+ = 3.68 ± 0.81 M−1 and the oxidation rate (log kFeCHO+ = 3.28 ± 0.41 M−1 min−1 for the Fe(II-DUA complex (FeCHO+, providing an excellent description of data obtained over a wide range of DUA concentrations and pH conditions. Considering the Marcus theory the Fe(III complexing constant with DUA was limited to between 1013 and 1016. For the seawater enriched with exudates of E. huxleyi a second kinetic modeling approach was carried out for fitting the Fe(II speciation, and the contribution of each Fe(II species to the overall oxidation rate as a function of the pH/pCO2 conditions. The influence of organic ligands in the

  11. Improving transcriptome construction in non-model organisms: integrating manual and automated gene definition in Emiliania huxleyi.

    Science.gov (United States)

    Feldmesser, Ester; Rosenwasser, Shilo; Vardi, Assaf; Ben-Dor, Shifra

    2014-02-22

    The advent of Next Generation Sequencing technologies and corresponding bioinformatics tools allows the definition of transcriptomes in non-model organisms. Non-model organisms are of great ecological and biotechnological significance, and consequently the understanding of their unique metabolic pathways is essential. Several methods that integrate de novo assembly with genome-based assembly have been proposed. Yet, there are many open challenges in defining genes, particularly where genomes are not available or incomplete. Despite the large numbers of transcriptome assemblies that have been performed, quality control of the transcript building process, particularly on the protein level, is rarely performed if ever. To test and improve the quality of the automated transcriptome reconstruction, we used manually defined and curated genes, several of them experimentally validated. Several approaches to transcript construction were utilized, based on the available data: a draft genome, high quality RNAseq reads, and ESTs. In order to maximize the contribution of the various data, we integrated methods including de novo and genome based assembly, as well as EST clustering. After each step a set of manually curated genes was used for quality assessment of the transcripts. The interplay between the automated pipeline and the quality control indicated which additional processes were required to improve the transcriptome reconstruction. We discovered that E. huxleyi has a very high percentage of non-canonical splice junctions, and relatively high rates of intron retention, which caused unique issues with the currently available tools. While individual tools missed genes and artificially joined overlapping transcripts, combining the results of several tools improved the completeness and quality considerably. The final collection, created from the integration of several quality control and improvement rounds, was compared to the manually defined set both on the DNA and

  12. Numerical modelling of physiological and ecological impacts of ocean acidification on coccolithophores

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    Furukawa, Makoto; Sato, Toru; Suzuki, Yoshimi; Casareto, Beatriz E.; Hirabayashi, Shinichiro

    2018-06-01

    Ocean surface acidification due to increasing atmospheric CO2 concentration is currently attracting much attention. Coccolithophores distribute widely across the world's oceans and represent a carbon sink containing about 100 million tonnes of carbon. For this reason, there is concern about dissolution of their shells, which are made of calcium carbonate, due to decreasing pH. In this study, intracellular calcification, photosynthesis, and mass transport through biomembranes of Emiliania huxleyi were modelled numerically for understanding biological response in calcifying organisms. Unknown parameters were optimised by a generic algorithm to match existing experimental results. The model showed that the production of calcium carbonate rather than its dissolution is promoted under an acidified environment. Calcite remains at saturation levels in a coccolith even when it is below saturation levels in the external seawater. Furthermore, a coccolith can dissolve even in water where calcite saturation exceeds 1, because the saturation may be below the threshold level locally around the cell membrane. The present model also showed that the different calcification rates of E. huxleyi with respect to rising CO2 concentrations reported in the literature are due to differences in experimental conditions; in particular, how the CO2 concentration is matched. Lastly, the model was able to reproduce differences in calcification rates among coccolithophore species. The above biochemical-kinetic model was then incorporated into an ecosystem model, and the behaviour of coccolithophores in the ecosystem and the influence of increases in CO2 concentration on water quality were simulated and validated by comparison with existing experimental results. The model also suggests that increased CO2 concentration could lead to an increase in the biomass ratio of coccolithophores to diatoms at high CO2 concentrations, particularly in oligotrophic environments, and to a consequent decrease in

  13. Coccolithophore diversity and dynamics at a coastal site in the Gulf of Trieste (northern Adriatic Sea)

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    Cerino, Federica; Malinverno, Elisa; Fornasaro, Daniela; Kralj, Martina; Cabrini, Marina

    2017-09-01

    Two years-data (May 2011-February 2013) obtained from a monthly sampling carried out at the coastal long term Ecological Research station C1-LTER in the Gulf of Trieste (northern Adriatic Sea) were analysed to describe the seasonal dynamics and diversity of coccolithophore assemblages and to assess their relationship with environmental forcing. Coccolithophores represented 10.7% of the total Utermöhl phytoplankton that were mainly dominated by small (Emiliania huxleyi, and a secondary peak in May-June (0.7-15.0 · 104 coccospheres L-1), coinciding with the increase of the light intensity and the beginning of the seasonal stratification, dominated by holococcolithophores and small Syracosphaera species. The most abundant taxa were E. huxleyi and holococcolithophores, followed by Acanthoica quattrospina, Syracosphaera species and other minor species. Statistical analyses recognized four distinct groups, corresponding to seasonal variations of environmental conditions. Considering the two years, some species displayed a recurrent seasonal pattern highlighting possible species-specific ecological requirements, while others showed an interannual variability probably due to local factors.

  14. Coccolithophores and calcite saturation state in the Baltic and Black Seas

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    T. Tyrrell

    2008-04-01

    Full Text Available The Baltic and Black Seas are both brackish, that is to say both have salinities intermediate between freshwater and seawater. The coccolithophore Emiliania huxleyi is abundant in one, the Black Sea, but absent from the other, the Baltic Sea. Here we present summertime coccolithophore measurements confirming this difference, as well as data on the calcium carbonate saturation state of the Baltic Sea. We find that the Baltic Sea becomes undersaturated (or nearly so in winter, with respect to both the aragonite and calcite mineral forms of CaCO3. Data for the Black Sea are more limited, but it appears to remain strongly supersaturated year-round. The absence of E. huxleyi from the Baltic Sea could therefore potentially be explained by dissolution of their coccoliths in winter, suggesting that minimum annual (wintertime saturation states could be most important in determining future ocean acidification impacts. In addition to this potential importance of winter saturation state, alternative explanations are also possible, either related to differences in salinity or else to differences in silicate concentrations.

  15. Late winter coccolithophore bloom off central Portugal in response to river discharge and upwelling

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    Guerreiro, Catarina; Oliveira, Anabela; de Stigter, Henko; Cachão, Mário; Sá, Carolina; Borges, Carlos; Cros, Lluϊsa; Santos, Ana; Fortuño, José-Manuel; Rodrigues, Aurora

    2013-05-01

    Coccolithophore communities collected during late winter (9-19 March of 2010) over the central Portuguese margin showed a major change in species abundance and composition within a few days' time, closely related to the highly transient meteorological and oceanographic conditions. Particularly favourable conditions for coccolithophore growth resulted from late winter continental runoff combined with northerly winds prevailing over the shelf, under clear sky conditions. A nutrient-rich Buoyant Plume (BP) resulting from intense river water runoff prior to and during the start of the cruise, was observed to spread out over the denser winter mixed layer water beneath, and extend equatorwards and offshore under influence of Ekman superficial dynamics. Stabilization of buoyancy, settling of suspended sediment from the BP and the prevailing clear sky conditions in the transition to the 2nd leg of the cruise resulted in optimum conditions for coccolithophores to develop, at the expense of nutrient availability in the superficial sunlit layer. Within a few days, coccolithophore cell densities and associated phytoplankton biomass more than tripled, reaching maximum values of 145,000 cells/l and ~13 µg/l Chl-a, respectively. Often considered as a uniform functional group of calcifying phytoplankton thriving in low-turbulence, low-nutrients and high-light environments, results presented in this study clearly show that coccolithophore life strategies are much more diverse than expected. The increase of cell densities was mainly due to the bloom of Emiliania huxleyi and Gephyrocapsa oceanica in the coastal region west off Cape Carvoeiro, together with other opportunistic phytoplankton genera (Chaetoceros s.l., Thalassiosira s.l and Skeletonema s.l.). This confirms their role as early succession r-selected taxa, capable of rapid growth within nutrient-rich environments. On the contrary, Syracosphaera spp. and Ophiaster spp. displayed the characteristics of K-selected species

  16. Importance of coccolithophore-associated organic biopolymers for fractionating particle-reactive radionuclides (234Th, 233Pa, 210Pb, 210Po, and 7Be) in the ocean

    Science.gov (United States)

    Lin, Peng; Xu, Chen; Zhang, Saijin; Sun, Luni; Schwehr, Kathleen A.; Bretherton, Laura; Quigg, Antonietta; Santschi, Peter H.

    2017-08-01

    Laboratory incubation experiments using the coccolithophore Emiliania huxleyi were conducted in the presence of 234Th, 233Pa, 210Pb, 210Po, and 7Be to differentiate radionuclide uptake to the CaCO3 coccosphere from coccolithophore-associated biopolymers. The coccosphere (biogenic calcite exterior and its associated biopolymers), extracellular (nonattached and attached exopolymeric substances), and intracellular (sodium-dodecyl-sulfate extractable and Fe-Mn-associated metabolites) fractions were obtained by sequentially extraction after E. huxleyi reached its stationary growth phase. Radionuclide partitioning and the composition of different organic compound classes, including proteins, total carbohydrates (TCHO), and uronic acids (URA), were assessed. 210Po was closely associated with the more hydrophobic biopolymers (high protein/TCHO ratio, e.g., in attached exopolymeric substances), while 234Th and 233Pa showed similar partitioning behavior with most activity being distributed in URA-enriched, nonattached exopolymeric substances and intracellular biopolymers. 234Th and 233Pa were nearly undetectable in the coccosphere, with a minor abundance of organic components in the associated biopolymers. These findings provide solid evidence that biogenic calcite is not the actual main carrier phase for Th and Pa isotopes in the ocean. In contrast, both 210Pb and 7Be were found to be mostly concentrated in the CaCO3 coccosphere, likely substituting for Ca2+ during coccolith formation. Our results demonstrate that even small cells (E. huxleyi) can play an important role in the scavenging and fractionation of radionuclides. Furthermore, the distinct partitioning behavior of radionuclides in diatoms (previous studies) and coccolithophores (present study) explains the difference in the scavenging of radionuclides between diatom- and coccolithophore-dominated marine environments.

  17. Ocean Acidification: Coccolithophore's Light Controlled Effect on Alkalinity

    Science.gov (United States)

    Dobbins, W.

    2015-12-01

    Coccolithophorids, which play a significant role in the flux of calcite and organic carbon from the photic region to deeper pelagic and benthic zones, are potentially far more useful than siliceous phytoplankton for ocean fertilization projects designed to sequester CO2. However, the production of H+ ions during calcification (HCO3 + Ca+ —> CaCO3 + H+) has resulted in localized acidification around coccolithophore blooms. It has been hypothesized that under the correct light conditions photosynthesis could proceed at a rate such that CO2 is removed in amounts equimolar or greater than the H+ produced by calcification, allowing stable or increasing alkalinity despite ongoing calcification. Previously, this effect had not been demonstrated under laboratory conditions. Fifteen Emiliania huxleyi cultures were separated into equal groups with each receiving: 0, 6, 12, 18, or 24 hours of light each day for 24 days. Daily pH, cell density, and temperature measurements revealed a strong positive correlation between light exposure and pH, and no significant decline in pH in any of the cultures. Alkalinity increases were temperature independent and not strongly correlated with cell density, implying photosynthetic removal of carbon dioxide as the root cause. The average pH across living cultures increased from 7.9 to 8.3 over the first week and changed little for the reminder of the 24-day period. The results demonstrate coccolithophorids can increase alkalinity across a broad range of cell densities, despite the acidification inherent to the calcification process. If the light-alkalinity effect reported here proves scalable to larger cultures, Emiliania huxleyi are a strong candidate for carbon sequestration via targeted ocean fertilization.

  18. A voltage-gated H+ channel underlying pH homeostasis in calcifying coccolithophores.

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    Alison R Taylor

    2011-06-01

    Full Text Available Marine coccolithophorid phytoplankton are major producers of biogenic calcite, playing a significant role in the global carbon cycle. Predicting the impacts of ocean acidification on coccolithophore calcification has received much recent attention and requires improved knowledge of cellular calcification mechanisms. Uniquely amongst calcifying organisms, coccolithophores produce calcified scales (coccoliths in an intracellular compartment and secrete them to the cell surface, requiring large transcellular ionic fluxes to support calcification. In particular, intracellular calcite precipitation using HCO₃⁻ as the substrate generates equimolar quantities of H+ that must be rapidly removed to prevent cytoplasmic acidification. We have used electrophysiological approaches to identify a plasma membrane voltage-gated H+ conductance in Coccolithus pelagicus ssp braarudii with remarkably similar biophysical and functional properties to those found in metazoans. We show that both C. pelagicus and Emiliania huxleyi possess homologues of metazoan H(v1 H+ channels, which function as voltage-gated H+ channels when expressed in heterologous systems. Homologues of the coccolithophore H+ channels were also identified in a diversity of eukaryotes, suggesting a wide range of cellular roles for the H(v1 class of proteins. Using single cell imaging, we demonstrate that the coccolithophore H+ conductance mediates rapid H+ efflux and plays an important role in pH homeostasis in calcifying cells. The results demonstrate a novel cellular role for voltage gated H+ channels and provide mechanistic insight into biomineralisation by establishing a direct link between pH homeostasis and calcification. As the coccolithophore H+ conductance is dependent on the trans-membrane H+ electrochemical gradient, this mechanism will be directly impacted by, and may underlie adaptation to, ocean acidification. The presence of this H+ efflux pathway suggests that there is no obligate

  19. Calcite production by coccolithophores in the south east Pacific Ocean

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    L. Beaufort

    2008-08-01

    Full Text Available BIOSOPE cruise covered an oceanographic transect through the centre of the South Pacific Gyre (SPG from the Marquesas archipelago to the Peru-Chile upwelling (PCU. Water samples from 6 depths in the euphotic zone were collected at 20 stations. The concentrations of suspended calcite particles, coccolithophores cells and detached coccoliths were estimated together with size and weight using an automatic polarizing microscope, a digital camera, and a collection of softwares performing morphometry and pattern recognition. Some of these softwares are new and described here for the first time. The coccolithophores standing stocks were usually low and reached maxima west of the PCU. The coccoliths of Emiliania huxleyi, Gephyrocapsa spp. and Crenalithus spp. (Order Isochrysidales represented more than 30% of all the suspended calcite particles detected in the size range 0.1–46 μm (22% of PIC in term of calcite weight. These species grew preferentially in the Chlorophyll maximum zone. In the SPG their maximum cell concentrations were recorded between depth of 150 and 200 m, which is unusually deep for these taxa. The weight of coccoliths and coccospheres were correlated to their size. Large and heavy coccoliths and coccospheres were found in regions with relatively high fertility in the Marquises Island and in the PCU. Small and light coccoliths and coccospheres were found west of the PCU. This distribution is strongly related to ocean chemistry in particular to alkalinity and to carbonate ions concentration. The biotic (coccolithophores production influence on calcification is mainly driven at the local scale (depth whereas the abiotic (carbonate chemistry plays its most important role at the regional (horizontal level. Here 94% of the variability of coccolith and coccosphere weight can be explained by a change in 7 environmental variables.

  20. Response of the calcifying coccolithophore Emiliania huxleyi to low pH/high pCO2: from physiology to molecular level

    NARCIS (Netherlands)

    Richier, S.; Fiorini, S.; Kerros, M.E.; von Dassow, P.; Gattuso, J.P.

    2011-01-01

    The emergence of ocean acidification as a significant threat to calcifying organisms in marine ecosystems creates a pressing need to understand the physiological and molecular mechanisms by which calcification is affected by environmental parameters. We report here, for the first time, changes in

  1. Photosynthetic carbon assimilation in the coccolithophorid Emiliania huxleyi (Haptophyta): Evidence for the predominant operation of the c3 cycle and the contribution of {beta}-carboxylases to the active anaplerotic reaction.

    Science.gov (United States)

    Tsuji, Yoshinori; Suzuki, Iwane; Shiraiwa, Yoshihiro

    2009-02-01

    The coccolithophorid Emiliania huxleyi (Haptophyta) is a representative and unique marine phytoplankton species that fixes inorganic carbon by photosynthesis and calci-fication. We examined the initial process of photosynthetic carbon assimilation by analyses of metabolites, enzymes and genes. When the cells were incubated with a radioactive substrate (2.3 mM NaH(14)CO(3)) for 10 s under illumination, 70% of the (14)C was incorporated into the 80% methanol-soluble fraction. Eighty-five and 15% of (14)C in the soluble fraction was incorporated into phosphate esters (P-esters), including the C(3) cycle intermediates and a C(4) compound, aspartate, respectively. A pulse-chase experiment showed that (14)C in P-esters was mainly transferred into lipids, while [(14)C]aspartate, [(14)C]alanine and [(14)C]glutamate levels remained almost constant. These results indicate that the C(3) cycle functions as the initial pathway of carbon assimilation and that beta-carboxylation contributes to the production of amino acids in subsequent metabolism. Transcriptional analysis of beta-carboxylases such as pyruvate carboxylase (PYC), phosphoenolpyruvate carboxylase (PEPC) and phosphoenolpyruvate carboxykinase (PEPCK) revealed that PYC and PEPC transcripts were greatly increased under illumination, whereas the PEPCK transcript decreased remarkably. PEPC activity was higher in light-grown cells than in dark-adapted cells. PYC activity was detected in isolated chloroplasts of light-grown cells. According to analysis of their deduced N-terminal sequence, PYC and PEPC are predicted to be located in the chloroplasts and mitochondria, respectively. These results suggest that E. huxleyi possesses unique carbon assimila-tion mechanisms in which beta-carboxylation by both PYC and PEPC plays important roles in different organelles.

  2. Spatial and temporal variability in coccolithophore abundance and distribution in the NW Iberian coastal upwelling system

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    B. Ausín

    2018-01-01

    Full Text Available A systematic investigation of the spatial and temporal variability in coccolithophore abundance and distribution through the water column of the NW Iberian coastal upwelling system was performed. From July 2011 to June 2012, monthly sampling at various water depths was conducted at two parallel stations located at 42° N. Total coccosphere abundance was higher at the outer-shelf station, where warmer, nutrient-depleted waters favoured coccolithophore rather than phytoplanktonic diatom blooms, which are known to dominate the inner-shelf location. In seasonal terms, higher coccosphere and coccolith abundances were registered at both stations during upwelling seasons, coinciding with high irradiance levels. This was typically in conjunction with stratified, nutrient-poor conditions (i.e. relaxing upwelling conditions. However, it also occurred during some upwelling events of colder, nutrient-rich subsurface waters onto the continental shelf. Minimum abundances were generally found during downwelling periods, with unexpectedly high coccolith abundance registered in subsurface waters at the inner-shelf station. This finding can only be explained if strong storms during these downwelling periods favoured resuspension processes, thus remobilizing deposited coccoliths from surface sediments, and hence hampering the identification of autochthonous coccolithophore community structure. At both locations, the major coccolithophore assemblages were dominated by Emiliania huxleyi, small Gephyrocapsa group, Gephyrocapsa oceanica, Florisphaera profunda, Syracosphaera spp., Coronosphaera mediterranea, and Calcidiscus leptoporus. Ecological preferences of the different taxa were assessed by exploring the relationships between environmental conditions and temporal and vertical variability in coccosphere abundance. These findings provide relevant information for the use of fossil coccolith assemblages in marine sediment records, in order to infer past

  3. Spatial and temporal variability in coccolithophore abundance and distribution in the NW Iberian coastal upwelling system

    Science.gov (United States)

    Ausín, Blanca; Zúñiga, Diana; Flores, Jose A.; Cavaleiro, Catarina; Froján, María; Villacieros-Robineau, Nicolás; Alonso-Pérez, Fernando; Arbones, Belén; Santos, Celia; de la Granda, Francisco; Castro, Carmen G.; Abrantes, Fátima; Eglinton, Timothy I.; Salgueiro, Emilia

    2018-01-01

    A systematic investigation of the spatial and temporal variability in coccolithophore abundance and distribution through the water column of the NW Iberian coastal upwelling system was performed. From July 2011 to June 2012, monthly sampling at various water depths was conducted at two parallel stations located at 42° N. Total coccosphere abundance was higher at the outer-shelf station, where warmer, nutrient-depleted waters favoured coccolithophore rather than phytoplanktonic diatom blooms, which are known to dominate the inner-shelf location. In seasonal terms, higher coccosphere and coccolith abundances were registered at both stations during upwelling seasons, coinciding with high irradiance levels. This was typically in conjunction with stratified, nutrient-poor conditions (i.e. relaxing upwelling conditions). However, it also occurred during some upwelling events of colder, nutrient-rich subsurface waters onto the continental shelf. Minimum abundances were generally found during downwelling periods, with unexpectedly high coccolith abundance registered in subsurface waters at the inner-shelf station. This finding can only be explained if strong storms during these downwelling periods favoured resuspension processes, thus remobilizing deposited coccoliths from surface sediments, and hence hampering the identification of autochthonous coccolithophore community structure. At both locations, the major coccolithophore assemblages were dominated by Emiliania huxleyi, small Gephyrocapsa group, Gephyrocapsa oceanica, Florisphaera profunda, Syracosphaera spp., Coronosphaera mediterranea, and Calcidiscus leptoporus. Ecological preferences of the different taxa were assessed by exploring the relationships between environmental conditions and temporal and vertical variability in coccosphere abundance. These findings provide relevant information for the use of fossil coccolith assemblages in marine sediment records, in order to infer past environmental conditions, of

  4. The White Ocean hypothesis: a late Pleistocene Southern Ocean governed by Coccolithophores and driven by phosphorus

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    Jose Abel Flores

    2012-07-01

    Full Text Available Paleoproductivity is a critical component in past ocean biogeochemistry, but accurate reconstructions of productivity are often hindered by limited integration of proxies. Here, we integrate geochemical (phosphorus and micropaleontological proxies at millennial timescales, revealing that the coccolithophore record in the Subantarctic zone of the South Atlantic Ocean is driven largely by variations in marine phosphorus availability. A quantitative micropaleontological and geochemical analysis carried out in sediments retrieved from ODP Site 1089 (Subantarctic Zone reveals that most of the export productivity in this region over the last 0.5 my was due to coccolithophores. Glacial periods were generally intervals of high productivity, with productivity reaching a peak at terminations. Particularly high productivity was observed at Termination V and Termination IV, events that are characterized by high abundance of coccolithophores and maxima in the phosphorus/titanium and strontium/titanium records. We link the increase in productivity both to regional oceanographic phenomena, i.e., the northward displacement of the upwelling cell of the Antarctic divergence when the ice-sheet expanded, and to the increase in the inventory of phosphorus in the ocean due to enhanced transfer of this nutrient from continental margins during glacial lowstands in sea level. The Mid-Brunhes interval stands out from the rest of the record, being dominated by the small and highly-calcified species Gephyrocapsa caribbeanica that provides most of the carbonate in these sediments. This likely represents higher availability of phosphorus in the surface ocean, especially in mesotrophic and oligotrophic zones. Under these condition, some coccolithophore species developed an r-strategy (opportunistic species; growth rate maximized resulting in the bloom of G. caribbeanica. These seasonal blooms of may have inducedwhite tides similar to those observed today in Emiliania huxleyi.

  5. A survey of the summer coccolithophore community in the western Barents Sea

    Science.gov (United States)

    Giraudeau, Jacques; Hulot, Vivien; Hanquiez, Vincent; Devaux, Ludovic; Howa, Hélène; Garlan, Thierry

    2016-06-01

    The Barents Sea is particularly vulnerable to large-scale hydro-climatic changes associated with the polar amplification of climate change. Key oceanographical variables in this region are the seasonal development of sea-ice and the location and strength of physico-chemical gradients in the surface and subsurface water layers induced by the convergence of Arctic- and Atlantic-derived water masses. Remote sensing imagery have highlighted the increasing success of calcifying haptophytes (coccolithophores) in the summer phytoplankton production of the Barents Sea over the last 20 years, as a response to an overall larger contribution of Atlantic waters to surface and sub-surface waters, as well as to enhanced sea-ice melt-induced summer stratification of the photic layer. The present study provides a first thorough description of coccolithophore standing stocks and diversity over the shelf and slope of the western Barents Sea from two sets of surface and water column samples collected during August-September 2014 from northern Norway to southern Svalbard. The abundance and composition of coccolithophore cells and skeletal remains (coccoliths) are discussed in view of the physical-chemical-biological status of the surface waters and water column based on in-situ (temperature, salinity, fluorescence) and shore-based (microscope enumerations, chemotaxonomy) measurements, as well as satellite-derived data (Chl a and particulate inorganic carbon contents). The coccolithophore population is characterized by a low species diversity and the overwhelming dominance of Emiliania huxleyi. Coccolithophores are abundant both within the well stratified, Norwegian coastal water - influenced shallow mixed layer off northern Norway, as well as within well-mixed cool Atlantic water in close vicinity of the Polar Front. Bloom concentrations with standing stocks larger than 4 million cells/l are recorded in the latter area north of 75°N. Our limited set of chemotaxonomic data suggests

  6. Coccolithophore ecology in the tropical and subtropical Atlantic Ocean: New perspectives from the Atlantic meridional transect (AMT) programme

    Science.gov (United States)

    Poulton, Alex J.; Holligan, Patrick M.; Charalampopoulou, Anastasia; Adey, Tim R.

    2017-11-01

    Coccolithophore species composition was determined in 199 samples collected from the upper 300 m of the Atlantic Ocean, spanning temperate, tropical and subtropical waters in both hemispheres during four Atlantic Meridional Transect (AMT) cruises over the period 2003-2005. Of the 171 taxa observed, 140 consistently represented 10% surface irradiance); the lower euphotic zone (LEZ, 10-1% surface irradiance); and the sub-euphotic zone (SEZ, Emiliania huxleyi and Gephyrocapsa ericsonii which were also abundant at higher latitudes. It is suggested that this pattern reflects similarities in the light (and inorganic nutrient) conditions between the LEZ and temperate waters. The SEZ is below the depth where light is thought to be sufficient to support photosynthesis, suggesting that deep-dwelling species such as Florisphaera profunda and Gladiolithus spp. may be mixotrophic or phagotrophic, although conclusive proof will need to be gained experimentally. Mixotrophy could also be an important nutritional strategy for species abundant (Umbellosphaera spp., holococcolithophores) in the UEZ where inorganic nutrient concentrations are depleted and limiting to growth, although other nutritional strategies, such as the use of organic nutrients, are also possible. Statistical differences were also found in the species composition between the different cruises, with high levels of similarity for similar timed cruises (May or September-October). Few individual taxa showed significant variability in abundance over the time-span of sampling, except species such as E. huxleyi and G. ericsonii at higher latitudes. In subtropical and equatorial waters, high levels of species richness and low levels of species dominance remained throughout the sampling period indicating that seasonal fluctuations reflected differences in the whole coccolithophore community rather than in just one or a few species. Multivariate analyses of the taxa classified as rare also indicated some level of temporal

  7. Calcite production by Coccolithophores in the South East Pacific Ocean: from desert to jungle

    Science.gov (United States)

    Beaufort, L.; Couapel, M.; Buchet, N.; Claustre, H.

    2007-09-01

    BIOSOPE cruise achieved an oceanographic transect from the Marquise Islands to the Peru-Chili upwelling (PCU) via the centre of the South Pacific Gyre (SPG). Water samples from 6 depths in the euphotic zone were collected at 20 stations. The concentrations of suspended calcite particles, coccolithophores cells and detached coccoliths were estimated together with size and weight using an automatic polarizing microscope, a digital camera, and a collection of softwares performing morphometry and pattern recognition. Some of these softwares are new and described here for the first time. The coccolithophores standing stocks are usually low and reach maxima west of the PCU. The coccoliths of Emiliania huxleyi, Gephyrocapsa spp. and Crenalithus spp. (Order Isochrysidales) represent 50% of all the suspended calcite particles detected in the size range 0.1-46 μm (21% of PIC in term of the calcite weight). The latter species are found to grow preferentially in the Chlorophyll maximum zone. In the SPG their maximum concentrations was found to occur between 150 and 200 m, which is very deep for these taxa. The weight and size of coccoliths and coccospheres are correlated. Large and heavy coccoliths and coccospheres are found in the regions with relative higher fertility in the Marquises Island and in the PCU. Small and light coccoliths and coccospheres are found west of the PCU. This distribution may correspond to that of the concentration of calcium and carbonate ions.

  8. Host–virus dynamics and subcellular controls of cell fate in a natural coccolithophore population

    Science.gov (United States)

    Vardi, Assaf; Haramaty, Liti; Van Mooy, Benjamin A. S.; Fredricks, Helen F.; Kimmance, Susan A.; Larsen, Aud; Bidle, Kay D.

    2012-01-01

    Marine viruses are major evolutionary and biogeochemical drivers in marine microbial foodwebs. However, an in-depth understanding of the cellular mechanisms and the signal transduction pathways mediating host–virus interactions during natural bloom dynamics has remained elusive. We used field-based mesocosms to examine the “arms race” between natural populations of the coccolithophore Emiliania huxleyi and its double-stranded DNA-containing coccolithoviruses (EhVs). Specifically, we examined the dynamics of EhV infection and its regulation of cell fate over the course of bloom development and demise using a diverse suite of molecular tools and in situ fluorescent staining to target different levels of subcellular resolution. We demonstrate the concomitant induction of reactive oxygen species, caspase-specific activity, metacaspase expression, and programmed cell death in response to the accumulation of virus-derived glycosphingolipids upon infection of natural E. huxleyi populations. These subcellular responses to viral infection simultaneously resulted in the enhanced production of transparent exopolymer particles, which can facilitate aggregation and stimulate carbon flux. Our results not only corroborate the critical role for glycosphingolipids and programmed cell death in regulating E. huxleyi–EhV interactions, but also elucidate promising molecular biomarkers and lipid-based proxies for phytoplankton host–virus interactions in natural systems. PMID:23134731

  9. Coccolithophores put a CAP on calcification and carbon

    Science.gov (United States)

    Rickaby, R. E. M.; Lee, R. B. Y.; Mavridou, D. A. I.; Papadakos, G.; McClelland, H. L. O.; Anderson, C. J.

    2014-12-01

    Unlike the majority of biomineralization, mediated via proteins, the coccolithophores employ acidic polysaccharides (CAPs) as the template for the multitude of intricate calcium carbonate liths which are precipitated inside their cells and expelled to form an external spherical armour. Massive accumulations of these calcium carbonate coccoliths (we estimate a flux of ~ 6x1025 liths/year) form sediments on the deep seafloor, a dominant sink of carbon from the atmosphere over geological timescales, and a buffer for seawater chemistry. This acidic, coccolith-associated polysaccharide (CAP) plays a dual role, likely determined by the calcifying vesicle chemistry, promoting and limiting precipitation. We have developed and demonstrated novel techniques for the extraction and characterisation of these biomineral-mediating molecules, encapsulated and preserved within liths from sediments as old as the Mesozoic. Modern cultures of extant coccolithophores show that the composition of CAP is distinctive for different species, and even strains of e.g. Emiliania huxleyi, suggestive that interactions with galacturonic acid residues are key to dictating the architecture of the liths. Furthermore, it appears that the galacturonic acid content reflects an adaptive response of the CAP to the chemistry within the coccolith vesicle where calcification is induced; in particular the size of the internal carbon pool and inferred saturation state. Extraction of CAPs from the Coccolithale fraction of sediments suggests that the galacturonic acid content of these relatively large and inefficient carbon concentrators evolves in response to declining CO2 availability and thus may provide a novel means for reconstructing paleo pCO2.

  10. The stereochemistry of chlorophyll-c₃ from the haptophyte Emiliania huxleyi: the (13²R)-enantiomers of chlorophylls-c are exclusively selected as the photosynthetically active pigments in chromophyte algae.

    Science.gov (United States)

    Mizoguchi, Tadashi; Kimura, Yuki; Yoshitomi, Taichi; Tamiaki, Hitoshi

    2011-11-01

    Chlorophyll(Chl)-c pigments in algae, diatoms and some prokaryotes are characterized by the fully conjugated porphyrin π-system as well as the acrylate residue at the 17-position. The precise structural characterization of Chl-c(3) from the haptophyte Emiliania huxleyi was performed. The conformations of the π-conjugated peripheral substituents, the 3-/8-vinyl, 7-methoxycarbonyl and 17-acrylate moieties were evaluated, in a solution, using nuclear Overhauser enhancement correlations and molecular modeling calculations. The rotation of the 17-acrylate residue was considerably restricted, whereas the other three substituents readily rotated at ambient temperature. Moreover, the stereochemistry at the 13²-position was determined by combination of chiral high-performance liquid chromatography (HPLC) with circular dichroism (CD) spectroscopy. Compared with the CD spectra of the structurally related, synthetic (13²R)- and (13²S)-protochlorophyllide(PChlide)-a, naturally occurring Chl-c₃ had exclusively the (13²R)-configuration. To elucidate this natural selection of a single enantiomer, we analyzed the three major Chl-c pigments (Chl-c₁, c₂ and c₃) in four phylogenetically distinct classes of Chl-c containing algae, i.e., heterokontophyta, dinophyta, cryptophyta and haptophyta using chiral HPLC. All the photosynthetic organisms contained only the (13²R)-enantiomerically pure Chls-c, and lacked the corresponding enantiomeric (13²S)-forms. Additionally, Chl-c₂ was found in all the organisms as the common Chl-c. These results throw a light on the biosynthesis as well as photosynthetic function of Chl-c pigments: Chl-c₂ is derived from 8-vinyl-PChlide-a by dehydrogenation of the 17-propionate to acrylate residues as generally proposed, and the (13²R)-enantiomers of Chls-c function as photosynthetically active, light-harvesting pigments together with the principal Chl-a and carotenoids. 2011 Elsevier B.V. All rights reserved.

  11. Distribution of coccolithophores as a potential proxy in paleoceanography: The case of the Oman Sea monsoonal pattern

    Directory of Open Access Journals (Sweden)

    Mojtahedin Elham

    2015-02-01

    Full Text Available High abundances of coccoliths have been observed in surface sediment samples from near the coasts of the Oman Sea in February 2011. At the end of the NE monsoon, the locally observed high Gephyrocapsa oceanica production is hypothesized to respond to local injections of nutrient-rich deep water into the surface water due to sea-surface cooling leading to convection. The most abundant coccolithophore species are G. oceanica followed by Emiliania huxleyi, Helicosphaera carteri, Calcidiscus leptoporus. Some species, such as Gephyrocapsa muellerae, Gephyrocapsa ericsonii, Umbilicosphaera sibogae, Umbellosphaera tenuis and Florisphaera profunda, are rare. The G. oceanica suggested a prevalence of upwelling conditions or high supply of nutrients in the Oman Sea (especially West Jask at the end of the NE monsoon. E. huxleyi showed low relative abundances at the end of the NE monsoon. Due to the location of the Oman Sea in low latitudes with high temperatures, we have observed low abundances of G. muellerae in the study area. Additionally, we have identified low abundances of G. ericsonii at the end of the NE monsoon. Helicosphaera carteri showed a clear negative response with decreasing amounts (relative abundances at the end of the NE monsoon. C. leptoporus, U. sibogae and U. tenuis have very low relative abundances in the NE monsoon and declined extremely at the end of the NE monsoon. F. profunda, which is known to inhabit the lower photic zone (<100 m depht was rarely observed in the samples.

  12. Distribution of coccolithophores as a potential proxy in paleoceanography: The case of the Oman Sea monsoonal pattern

    Science.gov (United States)

    Mojtahedin, Elham; Hadavi, Fatemeh; Lak, Razyeh

    2015-02-01

    High abundances of coccoliths have been observed in surface sediment samples from near the coasts of the Oman Sea in February 2011. At the end of the NE monsoon, the locally observed high Gephyrocapsa oceanica production is hypothesized to respond to local injections of nutrient-rich deep water into the surface water due to sea-surface cooling leading to convection. The most abundant coccolithophore species are G. oceanica followed by Emiliania huxleyi, Helicosphaera carteri, Calcidiscus leptoporus. Some species, such as Gephyrocapsa muellerae, Gephyrocapsa ericsonii, Umbilicosphaera sibogae, Umbellosphaera tenuis and Florisphaera profunda, are rare. The G. oceanica suggested a prevalence of upwelling conditions or high supply of nutrients in the Oman Sea (especially West Jask) at the end of the NE monsoon. E. huxleyi showed low relative abundances at the end of the NE monsoon. Due to the location of the Oman Sea in low latitudes with high temperatures, we have observed low abundances of G. muellerae in the study area. Additionally, we have identified low abundances of G. ericsonii at the end of the NE monsoon. Helicosphaera carteri showed a clear negative response with decreasing amounts (relative abundances) at the end of the NE monsoon. C. leptoporus, U. sibogae and U. tenuis have very low relative abundances in the NE monsoon and declined extremely at the end of the NE monsoon. F. profunda, which is known to inhabit the lower photic zone (<100 m depht) was rarely observed in the samples.

  13. Evidence for methane production by marine algae (Emiliana huxleyi) and its implication for the methane paradox in oxic waters

    Science.gov (United States)

    Lenhart, K.; Klintzsch, T.; Langer, G.; Nehrke, G.; Bunge, M.; Schnell, S.; Keppler, F.

    2015-12-01

    Methane (CH4), an important greenhouse gas that affects radiation balance and consequently the earth's climate, still has uncertainties in its sinks and sources. The world's oceans are considered to be a source of CH4 to the atmosphere, although the biogeochemical processes involved in its formation are not fully understood. Several recent studies provided strong evidence of CH4 production in oxic marine and freshwaters but its source is still a topic of debate. Studies of CH4 dynamics in surface waters of oceans and large lakes have concluded that pelagic CH4 supersaturation cannot be sustained either by lateral inputs from littoral or benthic inputs alone. However, frequently regional and temporal oversaturation of surface waters occurs. This comprises the observation of a CH4 oversaturating state within the surface mixed layer, sometimes also termed the "oceanic methane paradox". In this study we considered marine algae as a possible direct source of CH4. Therefore, the coccolithophore Emiliania huxleyi was grown under controlled laboratory conditions and supplemented with two 13C-labelled carbon substrates, namely bicarbonate and a position-specific 13C-labelled methionine (R-S-13CH3). The CH4 production was 0.7 μg POC g-1 d-1, or 30 ng g-1 POC h-1. After supplementation of the cultures with the 13C labelled substrate, the isotope label was observed in headspace-CH4. Moreover, the absence of methanogenic archaea within the algal culture and the oxic conditions during CH4 formation suggest that marine algae such as Emiliania huxleyi contribute to the observed spatial and temporal restricted CH4 oversaturation in ocean surface waters.

  14. Coccolithophores: Functional Biodiversity, Enzymes and Bioprospecting

    Directory of Open Access Journals (Sweden)

    Michael J. Allen

    2011-04-01

    Full Text Available Emiliania huxleyi is a single celled, marine phytoplankton with global distribution. As a key species for global biogeochemical cycling, a variety of strains have been amassed in various culture collections. Using a library consisting of 52 strains of E. huxleyi and an ‘in house‘ enzyme screening program, we have assessed the functional biodiversity within this species of fundamental importance to global biogeochemical cycling, whilst at the same time determining their potential for exploitation in biocatalytic applications. Here, we describe the screening of E. huxleyi strains, as well as a coccolithovirus infected strain, for commercially relevant biocatalytic enzymes such as acid/alkali phosphodiesterase, acid/alkali phosphomonoesterase, EC1.1.1-type dehydrogenase, EC1.3.1-type dehydrogenase and carboxylesterase.

  15. Calcium Carbonate Dissolution Above the Lysocline: Implications of Copepod Grazing on Coccolithophores

    Science.gov (United States)

    White, M. M.; Waller, J. D.; Lubelczyk, L.; Drapeau, D.; Bowler, B.; Wyeth, A.; Fields, D.; Balch, W. M.

    2016-02-01

    Copepod-coccolithophore predator-prey interactions are of great importance because they facilitate the export of particulate inorganic and organic carbon (PIC and POC) from the surface ocean. Coccolith dissolution in acidic copepod guts has been proposed as a possible explanation for the paradox of PIC dissolution above the lysocline, but warrants further investigation. Using a new application of the 14C-microdiffusion technique, we investigated the dissolution of coccoliths in copepod guts. We considered both an estuarine predator-prey model (Acartia tonsa and Pleurochrysis carterae) and an open ocean predator-prey model (Calanus finmarchicus and Emiliania huxleyi). Additionally, we considered the impacts of pCO2 on this process to advance our understanding of the effects of ocean acidification on trophic interactions. In the estuarine predator-prey model, fecal pellets produced immediately after previously-starved copepods grazed on P. carterae had PIC/POC ratios 27-40 % lower than that of the algae, indicating PIC dissolution within the copepod gut, with no impact of pCO2 on this dissolution. Subsequent fecal pellets showed increasing PIC/POC, suggesting that calcite dissolution decreases as the gut fills. The open ocean predator-prey model showed equivocal results, indicating high variability among individual grazing behavior, and therefore no consistent impact of copepod grazing on coccolith dissolution above the lysocline in the open ocean. We will further discuss the effects of fecal pellet PIC/POC ratios on sinking rate.

  16. Coccolithophore fluxes in the open tropical North Atlantic: influence of thermocline depth, Amazon water, and Saharan dust

    Science.gov (United States)

    Guerreiro, Catarina V.; Baumann, Karl-Heinz; Brummer, Geert-Jan A.; Fischer, Gerhard; Korte, Laura F.; Merkel, Ute; Sá, Carolina; de Stigter, Henko; Stuut, Jan-Berend W.

    2017-10-01

    Coccolithophores are calcifying phytoplankton and major contributors to both the organic and inorganic oceanic carbon pumps. Their export fluxes, species composition, and seasonal patterns were determined in two sediment trap moorings (M4 at 12° N, 49° W and M2 at 14° N, 37° W) collecting settling particles synchronously from October 2012 to November 2013 at 1200 m of water depth in the open equatorial North Atlantic. The two trap locations showed a similar seasonal pattern in total coccolith export fluxes and a predominantly tropical coccolithophore settling assemblage. Species fluxes were dominated throughout the year by lower photic zone (LPZ) taxa (Florisphaera profunda, Gladiolithus flabellatus) but also included upper photic zone (UPZ) taxa (Umbellosphaera spp., Rhabdosphaera spp., Umbilicosphaera spp., Helicosphaera spp.). The LPZ flora was most abundant during fall 2012, whereas the UPZ flora was more important during summer. In spite of these similarities, the western part of the study area produced persistently higher fluxes, averaging 241×107 ± 76×107 coccoliths m-2 d-1 at station M4 compared to only 66×107 ± 31×107 coccoliths m-2 d-1 at station M2. Higher fluxes at M4 were mainly produced by the LPZ species, favoured by the westward deepening of the thermocline and nutricline. Still, most UPZ species also contributed to higher fluxes, reflecting enhanced productivity in the western equatorial North Atlantic. Such was the case of two marked flux peaks of the more opportunistic species Gephyrocapsa muellerae and Emiliania huxleyi in January and April 2013 at M4, indicating a fast response to the nutrient enrichment of the UPZ, probably by wind-forced mixing. Later, increased fluxes of G. oceanica and E. huxleyi in October-November 2013 coincided with the occurrence of Amazon-River-affected surface waters. Since the spring and fall events of 2013 were also accompanied by two dust flux peaks, we propose a scenario in which atmospheric dust also

  17. Emiliania huxleyi v1.0

    Energy Technology Data Exchange (ETDEWEB)

    Kuo, Alan

    2008-10-01

    We discuss how to find tandem duplicates and look at: (1) self aligning, proteomes - [Blastp]; (2) convert into symmetric similarity matrix; (3) cluster into familites - [MCL]; (4) annotate families with Pfam - [Hmmer]; and (5) classify families by taxa; and (6) look for interesting stuff.

  18. Physiological responses of coccolithophores to abrupt exposure of naturally low pH deep seawater.

    Science.gov (United States)

    Iglesias-Rodriguez, Maria Debora; Jones, Bethan M; Blanco-Ameijeiras, Sonia; Greaves, Mervyn; Huete-Ortega, Maria; Lebrato, Mario

    2017-01-01

    Upwelling is the process by which deep, cold, relatively high-CO2, nutrient-rich seawater rises to the sunlit surface of the ocean. This seasonal process has fueled geoengineering initiatives to fertilize the surface ocean with deep seawater to enhance productivity and thus promote the drawdown of CO2. Coccolithophores, which inhabit many upwelling regions naturally 'fertilized' by deep seawater, have been investigated in the laboratory in the context of ocean acidification to determine the extent to which nutrients and CO2 impact their physiology, but few data exist in the field except from mesocosms. Here, we used the Porcupine Abyssal Plain (north Atlantic Ocean) Observatory to retrieve seawater from depths with elevated CO2 and nutrients, mimicking geoengineering approaches. We tested the effects of abrupt natural deep seawater fertilization on the physiology and biogeochemistry of two strains of Emiliania huxleyi of known physiology. None of the strains tested underwent cell divisions when incubated in waters obtained from seawater from ~1,000 m (pH = 7.9; CO2 ~560 p.p.m.; 14-17 μM nitrate) and ~4,800 m (pH = 7.9; CO2 ~600 p.p.m.; 21 μM nitrate). Emiliania huxleyi strain CCMP 88E showed no differences in growth rate or in cellular content or production rates of particulate organic (POC) and inorganic (PIC) carbon and cellular particulate organic nitrogen (PON) between treatments using water from 1,000 m and 4,800 m. However, despite the N:P ratio of seawater being comparable in water from ~1,000 and ~4,800 m, the PON production rates were three times lower in one incubation using water from ~1,000 m compared to values observed in water from ~4,800 m. Thus, the POC:PON ratios were threefold higher in cells that were incubated in ~1,000 m seawater. The heavily calcified strain NZEH exhibited lower growth rates and PIC production rates when incubated in water from ~4,800 m compared to ~1,000 m, while cellular PIC, POC and PON were higher in water from 4,800 m

  19. Coccolithophore export production and seasonal variation from a trans-Atlantic array of sediment trap moorings (NW Africa to Caribbean)

    Science.gov (United States)

    Guerreiro, C. V.; Baumann, K. H.; Brummer, G. J. A.; Fischer, G.; Korte, L.; Stuut, J. B. W.

    2016-02-01

    In this study, we contribute to disclose the ecology and seasonal variability of coccolithophores, to improve their use as proxies for environmental variability in the Equatorial Atlantic Ocean. To this aim, the coccolithophore export fluxes and species composition were investigated from a trans-Atlantic array of sediment trap moorings from NW Africa (Cape Blanc) into the Caribbean (Barbados) (i.e., CB at 20°N/52ºW: M1 at 12ºN/23ºW; M2 at 14ºN/37ºW; M4 at 12ºN/49ºW). Each of the sediment trap devices was deployed at 1200 m depth, sampling settling particles at two-week intervals, and covering a full year (Oct. 2012 to Oct. 2013). First results show important contrasts between both ends of the trans-Atlantic array: total coccolith fluxes were much higher in the oligotrophic station M4 (western part of the basin) than in the highly productive waters off Cape Blanc (eastern edge of the basin), mostly due to the overwhelming dominance of the deep photic layer species Florisphaera profunda and Gladiolithus flabellatus. Off Cape Blanc, higher abundances of the placolith-bearing species Emiliania huxleyi and Gephyrocapsa spp. were found, more typical of the upper photic layer, while F. profunda decreases in relative abundance and G. flabellatus is almost absent, in comparison to M4. The presence of trans-Atlantic ecological gradients in terms of species diversity and prevalence of K- and r-selected species will be discussed with respect to the prevailing environmental conditions during the monitored period, including Saharan-dust deposition and the influence of the Amazon River plume.This study is part of ongoing multidisciplinary research in the study area, in the context of the projects "DUSTRAFFIC" and "TRAFFIC - Transatlantic Fluxes of Saharan Dust".

  20. Coccolithophore surface distributions in the North Atlantic and their modulation of the air-sea flux of CO2 from 10 years of satellite Earth observation data

    Directory of Open Access Journals (Sweden)

    J. D. Shutler

    2013-04-01

    Full Text Available Coccolithophores are the primary oceanic phytoplankton responsible for the production of calcium carbonate (CaCO3. These climatically important plankton play a key role in the oceanic carbon cycle as a major contributor of carbon to the open ocean carbonate pump (~50% and their calcification can affect the atmosphere-to-ocean (air-sea uptake of carbon dioxide (CO2 through increasing the seawater partial pressure of CO2 (pCO2. Here we document variations in the areal extent of surface blooms of the globally important coccolithophore, Emiliania huxleyi, in the North Atlantic over a 10-year period (1998–2007, using Earth observation data from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS. We calculate the annual mean sea surface areal coverage of E. huxleyi in the North Atlantic to be 474 000 ± 104 000 km2, which results in a net CaCO3 carbon (CaCO3-C production of 0.14–1.71 Tg CaCO3-C per year. However, this surface coverage (and, thus, net production can fluctuate inter-annually by −54/+8% about the mean value and is strongly correlated with the El Niño/Southern Oscillation (ENSO climate oscillation index (r=0.75, pE. huxleyi blooms in the North Atlantic can increase the pCO2 and, thus, decrease the localised air-sea flux of atmospheric CO2. In regions where the blooms are prevalent, the average reduction in the monthly air-sea CO2 flux can reach 55%. The maximum reduction of the monthly air-sea CO2 flux in the time series is 155%. This work suggests that the high variability, frequency and distribution of these calcifying plankton and their impact on pCO2 should be considered if we are to fully understand the variability of the North Atlantic air-to-sea flux of CO2. We estimate that these blooms can reduce the annual N. Atlantic net sink atmospheric CO2 by between 3–28%.

  1. Testing the effects of elevated pCO2 on coccolithophores (Prymnesiophysceae): comparison between haploid and diploid life stages

    NARCIS (Netherlands)

    Fiorini, S.; Middelburg, J.J.; Gattuso, J.P.

    2011-01-01

    The response of Emiliania huxleyi (Lohmann) W. W. Hay et H. Mohler, Calcidiscus leptoporus (G. Murray et V. H. Blackman) J. Schiller, and Syracosphaera pulchra Lohmann to elevated partial pressure of carbon dioxide (pCO2) was investigated in batch cultures. We reported on the response of both

  2. Coccolithophore fluxes in the open tropical North Atlantic: influence of thermocline depth, Amazon water, and Saharan dust

    Directory of Open Access Journals (Sweden)

    C. V. Guerreiro

    2017-10-01

    Full Text Available Coccolithophores are calcifying phytoplankton and major contributors to both the organic and inorganic oceanic carbon pumps. Their export fluxes, species composition, and seasonal patterns were determined in two sediment trap moorings (M4 at 12° N, 49° W and M2 at 14° N, 37° W collecting settling particles synchronously from October 2012 to November 2013 at 1200 m of water depth in the open equatorial North Atlantic. The two trap locations showed a similar seasonal pattern in total coccolith export fluxes and a predominantly tropical coccolithophore settling assemblage. Species fluxes were dominated throughout the year by lower photic zone (LPZ taxa (Florisphaera profunda, Gladiolithus flabellatus but also included upper photic zone (UPZ taxa (Umbellosphaera spp., Rhabdosphaera spp., Umbilicosphaera spp., Helicosphaera spp.. The LPZ flora was most abundant during fall 2012, whereas the UPZ flora was more important during summer. In spite of these similarities, the western part of the study area produced persistently higher fluxes, averaging 241×107 ± 76×107 coccoliths m−2 d−1 at station M4 compared to only 66×107 ± 31×107 coccoliths m−2 d−1 at station M2. Higher fluxes at M4 were mainly produced by the LPZ species, favoured by the westward deepening of the thermocline and nutricline. Still, most UPZ species also contributed to higher fluxes, reflecting enhanced productivity in the western equatorial North Atlantic. Such was the case of two marked flux peaks of the more opportunistic species Gephyrocapsa muellerae and Emiliania huxleyi in January and April 2013 at M4, indicating a fast response to the nutrient enrichment of the UPZ, probably by wind-forced mixing. Later, increased fluxes of G. oceanica and E. huxleyi in October–November 2013 coincided with the occurrence of Amazon-River-affected surface waters. Since the spring and fall events of 2013 were also accompanied by two dust

  3. Response to Comment on "Phytoplankton Calcification in a High-CO2 World"

    NARCIS (Netherlands)

    Iglesias-Rodriguez, M. Debora; Buitenhuis, Erik T.; Raven, John A.; Schofield, Oscar; Poulton, Alex J.; Gibbs, Samantha; Halloran, Paul R.; de Baar, Hein J. W.

    2008-01-01

    Recently reported increasing calcification rates and primary productivity in the coccolithophore Emiliania huxleyi were obtained by equilibrating seawater with mixtures of carbon dioxide in air. The noted discrepancy with previously reported decreasing calcification is likely due to the previously

  4. Coccolithophore response to climate and surface hydrography in Santa Barbara Basin, California, AD 1917–2004

    Directory of Open Access Journals (Sweden)

    M. Grelaud

    2009-10-01

    Full Text Available The varved sedimentary AD 1917–2004 record from the depositional center of the Santa Barbara Basin (SBB, California was analyzed with monthly to triannual resolution to yield relative abundances of six coccolithophore species representing at least 96% of the coccolithophore assemblage. Seasonal/annual relative abundances respond to climatic and surface hydrographic conditions in the SBB, whereby (i the three species G. oceanica, H. carteri and F. profunda are characteristic of the strength of the northward flowing warm California Counter Current, (ii the two species G. ericsonii and G. muellerae are associated with the cold equatorward flowing California Current, (iii and E. huxleyi appears to be endemic to the SBB. Spectral analyses on relative abundances of these species show that all are influenced by the El Niño Southern Oscillation (ENSO and/or by the Pacific Decadal Oscillation (PDO. Increased relative abundances of G. oceanica and H. carteri are associated with warm ENSO events, G. muellerae responds to warm PDO events and the abundance of G. ericsonii increases during cold PDO events. Morphometric parameters measured on E. huxleyi, G. muellerae and G. oceanica indicate increasing coccolithophore shell carbonate mass from ~1917 until 2004 concomitant with rising pCO2 and sea surface temperature in the region of the SBB.

  5. Molecular Biogeochemistry of Modern and Ancient Marine Microbes

    Science.gov (United States)

    2010-02-01

    jahnii AF163148 Isochrysis sp. AB183617 Emiliania huxleyi M87327 Chrysochromulina campanulifera AJ246273 Chrysochromulina throndsenii AJ246277... Emiliania huxleyi Skeletonema costatum hotChlE9, syn-A hotChlC1, med4-B hotChlD9, med4-B hotChlD12, med4-B hotChlE5, syn-A hotChlE4, syn-A hotChlA9, med4...straight-chain C37- C39 methyl and ethyl ketones in marine sediments and a coccolithophore Emiliania huxleyi . Advances in Organic Geochemistry 1979

  6. New Coccolithophore Bloom in Bering Sea

    Science.gov (United States)

    2002-01-01

    For the fourth year in a row it appears as if there is a bloom of coccolithophores-marine single-celled plants with calcite scales-in the Bering Sea off the coast of Alaska. Similar blooms were rare before 1997, but they have appeared every year since then. Scientists believe the coccolithophore blooms are the result of changing wind patterns in the region. Weaker than normal winds fail to mix the water of the Bering Sea, resulting in the growth of coccolithophores instead of other types of phytoplankton. Seabird populations have also been changing as a result of this climate change. The Sea-Viewing Wide Field-of-View Sensor (SeaWiFS), flying aboard the OrbView-2 satellite, saw the coccolith-brightened waters of the Bering Sea in 1997, 1998, and 1999. The waters have looked fairly bright again this winter and spring, as seen in this SeaWiFS image acquired April 29, 2000. But scientists are unsure whether this year's phenomenon is caused by living coccolithophorids, re-suspended coccoliths, or something else. Like all phytoplankton, coccolithophores contain chlorophyll and have the tendency to multiply rapidly near the surface. Yet, in large numbers, coccolithophores periodically shed their tiny scales, called 'coccoliths,' by the bucketful into the surrounding waters. The calcium-rich coccoliths turn the normally dark water a bright, milky aquamarine, making coccolithophore blooms easy to spot in satellite imagery. The edge of the whitish cloud in the water seen in this image is roughly 50 kilometers off the West Coast of Alaska. For more information see: SeaWiFS home page Changing Currents Color the Bering Sea a New Shade of Blue Image courtesy SeaWiFS project

  7. Characterization of [8-ethyl]-chlorophyll c3 from Emiliania huxleyi.

    Science.gov (United States)

    Álvarez, Susana; Zapata, Manuel; Garrido, José L; Vaz, Belén

    2012-06-04

    We report herein the isolation and complete characterization of a member of the chlorophyll c family, designated as [8-ethyl]-chlorophyll c(3) ([8-ethyl]-chl c(3)). Structural elucidation of this pigment rested on the analysis of mono- and bidimensional NMR, UV-VIS spectroscopy and ESI-MS data, and the configuration at the 13(2) position on chiral HPLC analysis.

  8. Coccolithophores from the central Arabian Sea: Sediment trap results

    Indian Academy of Sciences (India)

    35.8 E were analyzed for temporal variation of coccolithophore fluxes from Octo- ber 1993 to ... production in the central Arabian Sea due to southward extent of nutrients from the northeast ... increases its residence period in the water column.

  9. Coccolithophore growth and calcification in a changing ocean

    Science.gov (United States)

    Krumhardt, Kristen M.; Lovenduski, Nicole S.; Iglesias-Rodriguez, M. Debora; Kleypas, Joan A.

    2017-12-01

    Coccolithophores are the most abundant calcifying phytoplankton in the ocean. These tiny primary producers have an important role in the global carbon cycle, substantially contributing to global ocean calcification, ballasting organic matter to the deep sea, forming part of the marine food web base, and influencing ocean-atmosphere CO2 exchange. Despite these important impacts, coccolithophores are not explicitly simulated in most marine ecosystem models and, therefore, their impacts on carbon cycling are not represented in most Earth system models. Here, we compile field and laboratory data to synthesize overarching, across-species relationships between environmental conditions and coccolithophore growth rates and relative calcification (reported as a ratio of particulate inorganic carbon to particulate organic carbon in coccolithophore biomass, PIC/POC). We apply our relationships in a generalized coccolithophore model, estimating current surface ocean coccolithophore growth rates and relative calcification, and projecting how these may change over the 21st century using output from the Community Earth System Model large ensemble. We find that average increases in sea surface temperature of ∼ 2-3 ° C lead to faster coccolithophore growth rates globally (> 10% increase) and increased calcification at high latitudes. Roughly an ubiquitous doubling of surface ocean pCO2 by the end of the century has the potential to moderately stimulate coccolithophore growth rates, but leads to reduced calcification (∼ 25% decrease). Decreasing nutrient availability (from warming-induced increases in stratification) produces increases in relative calcification, but leads to ∼ 25% slower growth rates. With all drivers combined, we observe decreases in calcification and growth in most low and mid latitude regions, with possible increases in both of these responses in most high latitude regions. Major limitations of our coccolithophore model stem from a lack of conclusive

  10. Cytochemical and x-ray microanalysis studies of intracellular calcium pools in scale-bearing cells of the coccolithophorid emiliana huxleyi

    International Nuclear Information System (INIS)

    Wal, P. van der; Bruijn, W.C. de; Westbroek, P.

    1985-01-01

    Emiliania huxleyi is a coccolithophorid with a life cycle including a stage characterized by the occurrence of a scale-bearing cell type. The scales are composed of organic material and are produced in the cisternae of the Golgi apparatus. The present report deals with the ultrastructural calcium localization in scale-bearing cells using cation-precipitating agents. Cations were precipitated either with potassium carbonate, or potassium phosphate, and then with potassium pyroantimonate. The distribution of electron-opaque deposits was the same when visualized by all four techniques. The most extensive deposits occurred in the Golgi apparatus, the 'peripheral space' (a cellular compartment totally encompassing the protoplast), the multivesicular bodies, and the cell vacuole. X-ray microanalysis revealed that calcium was a constituent of the electron-opaque deposits. The uptake and transport of calcium, as universal functions of the Golgi apparatus, are discussed. (Author)

  11. Improving transcriptome construction in non-model organisms: integrating manual and automated gene definition in Emiliania huxleyi.

    OpenAIRE

    Feldmesser, Ester; Rosenwasser, Shilo; Vardi, Assaf; Ben-Dor, Shifra

    2014-01-01

    Background The advent of Next Generation Sequencing technologies and corresponding bioinformatics tools allows the definition of transcriptomes in non-model organisms. Non-model organisms are of great ecological and biotechnological significance, and consequently the understanding of their unique metabolic pathways is essential. Several methods that integrate de novo assembly with genome-based assembly have been proposed. Yet, there are many open challenges in defining genes, particularly whe...

  12. Seasonal and interannual variabilities of coccolithophore blooms in the Bay of Biscay and the Celtic Sea observed from a 18-year time-series of non-algal Suspended Particulate Matter images

    Science.gov (United States)

    Perrot, Laurie; Gohin, Francis; Ruiz-Pino, Diana; Lampert, Luis

    2016-04-01

    Coccolithophores belong to the nano-phytoplankton size-class and produce CaCO3 scales called coccoliths which form the «shell» of the algae cell. Coccoliths are in the size range of a few μm and can also be detached from the cell in the water. This phytoplankton group has an ubiquitous distribution in all oceans but blooms only in some oceanic regions, like the North East Atlantic ocean and the South Western Atlantic (Patagonian Sea). At a global scale coccolithopore blooms are studied in regard of CaCO3 production and three potential feedback on climate change: albedo modification by the way of dimethylsulfide (DMS) production and atmospheric CO2 source by calcification and a CO2 pump by photosynthesis. As the oceans are more and more acidified by anthropogenic CO2 emissions, coccolithophores generally are expected to be negatively affected. However, recent studies have shown an increase in coccolithophore occurrence in the North Atlantic. A poleward expansion of the coccolithophore Emiliana Huxleyi has also been pointed out. By using a simplified fuzzy method applied to a 18-year time series of SeaWiFS (1998-2002) and MODIS (2003-2015) spectral reflectance, we assessed the seasonal and inter-annual variability of coccolithophore blooms in the vicinity of the shelf break in the Bay of Biscay and the Celtic Sea After identification of the coccolith pixels by applying the fuzzy method, the abundance of coccoliths is assessed from a database of non-algal Suspended Particulate Matter (SPM). Although a regular pattern in the phenology of the blooms is observed, starting south in April in Biscay and moving northwards until July in Ireland, there is a high seasonal and interannual variability in the extent of the blooms. Year 2014 shows very low concentrations of detached coccoliths (twice less than average) from space and anomalies point out the maximum level in 2001. Non-algal SPM, derived from a procedure defined for the continental shelf, appears to be well

  13. Coccolithophores from the central Arabian Sea: Sediment trap results

    Digital Repository Service at National Institute of Oceanography (India)

    Mergulhao, L.P.; Mohan, R.; Murty, V.S.N.; Guptha, M.V.S.; Sinha, D.K.

    , Anoplosolenia braciliensisi, Calciosolenia murrayi and Oolithotus antillarum. Minor species such as Discosphaera tubifera, Syracosphaera pulchra, Umbellosphaera tenuis, Neosphaera coccolithomor- pha, Algirosphaera oryza, Michaelsarsia adriati- cus, Gladiolithus... profunda, Oolithotus antillarum) are presented (figure 2a?b). In addition to the majority of isolated coccol- iths, a few coccospheres comprising of G. oceanica, E. huxleyi, G. flabellatus, A. oryza, F. profunda, C. leptoporus were also observed...

  14. Influence of the Nazaré Canyon, central Portuguese margin, on late winter coccolithophore assemblages

    NARCIS (Netherlands)

    Guerreiro, C.; Sá, C.; de Stigter, H.; Oliveira, A.; Cachão, M.; Cros, L.; Borges, C.; Quaresma, L.; Santos, A.I.; Fortuño, J.-M.; Rodrigez, A.

    2014-01-01

    This paper presents a first attempt to characterize coccolithophore assemblages occurring in the context of an active submarine canyon. Coccolithophores from the upper-middle sections of the Nazaré Canyon (central Portuguese margin) – one of the largest canyons of the European continental margin –

  15. A coccolithophore concept for constraining the Cenozoic carbon cycle

    Science.gov (United States)

    Henderiks, J.; Rickaby, R. E. M.

    2007-06-01

    An urgent question for future climate, in light of increased burning of fossil fuels, is the temperature sensitivity of the climate system to atmospheric carbon dioxide (pCO>sub>2). To date, no direct proxy for past levels of pCO2 exists beyond the reach of the polar ice core records. We propose a new methodology for placing a constraint on pCO2 over the Cenozoic based on the physiological plasticity of extant coccolithophores. Specifically, our premise is that the contrasting calcification tolerance of various extant species of coccolithophore to raised pCO2 reflects an "evolutionary memory" of past atmospheric composition. The different times of evolution of certain morphospecies allows an upper constraint of past pCO2 to be placed on Cenozoic timeslices. Further, our hypothesis has implications for the response of marine calcifiers to ocean acidification. Geologically "ancient" species, which have survived large changes in ocean chemistry, are likely more resilient to predicted acidification.

  16. Reduced resilience of a globally distributed coccolithophore to ocean acidification: Confirmed up to 2000 generations

    KAUST Repository

    Jin, Peng; Gao, Kunshan

    2015-01-01

    been poorly studied. Here we examined the coccolithophore Gephyrocapsa oceanica, while growing it for 2000 generations under ambient and elevated CO2 levels. While OA stimulated growth in the earlier selection period (from generations ~700 to ~1550

  17. Magneto-optical properties of biogenic photonic crystals in algae

    International Nuclear Information System (INIS)

    Iwasaka, M.; Mizukawa, Y.

    2014-01-01

    In the present study, the effects of strong static magnetic fields on the structural colors of the cell covering crystals on a microalgae, coccolithophore, were investigated. The coccolithophore, Emiliania huxleyi, generates a precise assembly of calcite crystals called coccoliths by biomineralization. The coccoliths attached to the cells exhibited structural colors under side light illumination, and the colors underwent dynamic transitions when the magnetic fields were changed between 0 T and 5 T, probably due to diamagnetically induced changes of their inclination under the magnetic fields. The specific light-scattering property of individual coccoliths separated from the cells was also observed. Light scattering from a condensed suspension of coccoliths drastically decreased when magnetic fields of more than 4 T were applied parallel to the direction of observation. The magnetically aligned cell-covering crystals of the coccolithophores exhibited the properties of both a photonic crystal and a minimum micromirror

  18. Multidecadal Increase in North Atlantic Coccolithophores and Potential Role of Increasing CO2

    Science.gov (United States)

    Rivero-Calle, S.; Gnanadesikan, A.; del Castillo, C. E.; Balch, W. M.; Guikema, S.

    2016-02-01

    As anthropogenic CO2 emissions acidify the oceans, calcifiers are expected to be negatively impacted. Using data from the Continuous Plankton Recorder, we show that coccolithophore occurrence in the North Atlantic has increased from 2 to over 20% from 1965 through 2010. We used Random Forest models to examine more than 20 possible environmental drivers of this change. CO2 and the Atlantic Multidecadal Oscillation were the best predictors. Since coccolithophore photosynthesis is strongly carbon-limited, we hypothesize that higher CO2 levels might be encouraging growth. A compilation of 41 independent laboratory studies supports our hypothesis. Our study shows a long-term basin-scale increase in coccolithophores and suggests that increasing pCO2 and temperature accelerated the growth rate of a key phytoplankton group for carbon cycling.

  19. A unifying concept of coccolithophore sensitivity to changing carbonate chemistry embedded in an ecological framework

    Science.gov (United States)

    Bach, Lennart Thomas; Riebesell, Ulf; Gutowska, Magdalena A.; Federwisch, Luisa; Schulz, Kai Georg

    2015-06-01

    Coccolithophores are a group of unicellular phytoplankton species whose ability to calcify has a profound influence on biogeochemical element cycling. Calcification rates are controlled by a large variety of biotic and abiotic factors. Among these factors, carbonate chemistry has gained considerable attention during the last years as coccolithophores have been identified to be particularly sensitive to ocean acidification. Despite intense research in this area, a general concept harmonizing the numerous and sometimes (seemingly) contradictory responses of coccolithophores to changing carbonate chemistry is still lacking to date. Here, we present the "substrate-inhibitor concept" which describes the dependence of calcification rates on carbonate chemistry speciation. It is based on observations that calcification rate scales positively with bicarbonate (HCO3-), the primary substrate for calcification, and carbon dioxide (CO2), which can limit cell growth, whereas it is inhibited by protons (H+). This concept was implemented in a model equation, tested against experimental data, and then applied to understand and reconcile the diverging responses of coccolithophorid calcification rates to ocean acidification obtained in culture experiments. Furthermore, we (i) discuss how other important calcification-influencing factors (e.g. temperature and light) could be implemented in our concept and (ii) embed it in Hutchinson's niche theory, thereby providing a framework for how carbonate chemistry-induced changes in calcification rates could be linked with changing coccolithophore abundance in the oceans. Our results suggest that the projected increase of H+ in the near future (next couple of thousand years), paralleled by only a minor increase of inorganic carbon substrate, could impede calcification rates if coccolithophores are unable to fully adapt. However, if calcium carbonate (CaCO3) sediment dissolution and terrestrial weathering begin to increase the oceans' HCO3

  20. Relating coccolithophore calcification rates to phytoplankton community dynamics: Regional differences and implications for carbon export

    Science.gov (United States)

    Poulton, Alex J.; Adey, Tim R.; Balch, William M.; Holligan, Patrick M.

    2007-03-01

    Recent measurements of surface coccolithophore calcification from the Atlantic Ocean (50°N-50°S) are compared to similar measurements from other oceanic settings. By combining the different data sets of surface measurements, we examine general and regional patterns of calcification relative to organic carbon production (photosynthesis) and other characteristics of the phytoplankton community. Generally, surface calcification and photosynthesis are positively correlated, although the strength of the relationship differs between biogeochemical provinces. Relationships between surface calcification, chlorophyll- a and calcite concentrations are also statistically significant, although again there is considerable regional variability. Such variability appears unrelated to phytoplankton community composition or hydrographic conditions, and may instead reflect variations in coccolithophore physiology. The contribution of inorganic carbon fixation (calcification) to total carbon fixation (calcification plus photosynthesis) is ˜1-10%, and we estimate a similar contribution from coccolithophores to total organic carbon fixation. However, these contributions vary between biogeochemical provinces, and occasionally coccolithophores may account for >20% of total carbon fixation in unproductive central subtropical gyres. Combining surface calcification and photosynthetic rates with standing stocks of calcite, particulate organic carbon, and estimated phytoplankton carbon allows us to examine the fates of these three carbon pools. The relative turnover times vary between different biogeochemical provinces, with no clear relationship to the overall productivity or phytoplankton community structure found in each province. Rather, interaction between coccolithophore physiology (coccolith production and detachment rates), species diversity (cell size), and food web dynamics (grazer ecology) may control the composition and turnover times of calcite particles in the upper ocean.

  1. Ecology of coccolithophores in the Indian sector of the Southern Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Mohan, R.; Mergulhao, L.P.; Guptha, M.V.S.; Rajakumar, A.; Thamban, M.; AnilKumar, N.; Sudhakar, M.; Ravindra, R.

    A, Type C and variety corona. It is believed that the probable limiting factors of E. huxleyi types A and C were high temperature and low nutrient concentra- tions respectively. The species of C. leptopora has rare occurrences at stations 23, 27...

  2. Dynamic metabolic exchange governs a marine algal-bacterial interaction.

    Science.gov (United States)

    Segev, Einat; Wyche, Thomas P; Kim, Ki Hyun; Petersen, Jörn; Ellebrandt, Claire; Vlamakis, Hera; Barteneva, Natasha; Paulson, Joseph N; Chai, Liraz; Clardy, Jon; Kolter, Roberto

    2016-11-18

    Emiliania huxleyi is a model coccolithophore micro-alga that generates vast blooms in the ocean. Bacteria are not considered among the major factors influencing coccolithophore physiology. Here we show through a laboratory model system that the bacterium Phaeobacter inhibens , a well-studied member of the Roseobacter group, intimately interacts with E. huxleyi. While attached to the algal cell, bacteria initially promote algal growth but ultimately kill their algal host. Both algal growth enhancement and algal death are driven by the bacterially-produced phytohormone indole-3-acetic acid. Bacterial production of indole-3-acetic acid and attachment to algae are significantly increased by tryptophan, which is exuded from the algal cell. Algal death triggered by bacteria involves activation of pathways unique to oxidative stress response and programmed cell death. Our observations suggest that bacteria greatly influence the physiology and metabolism of E. huxleyi. Coccolithophore-bacteria interactions should be further studied in the environment to determine whether they impact micro-algal population dynamics on a global scale.

  3. A minireview of marine algal virus — Coccolithoviruses

    Science.gov (United States)

    Liu, Jingwen; Xu, Miaomiao; Zheng, Tianling

    2015-04-01

    Coccolithophorid is unicellular marine microalgae with a global distribution in temperate and sub-temperate oceanic regions and has the ability to produce `the coccoliths'. It is considered to be the second most productive calcifying organism on earth and becoming an important factor in the global carbonate cycle. Emiliania huxleyi is one of the only two bloom-forming coccolithophores and becomes a species crucial to the study of global biogeochemical cycles and climate modeling. Coccolithoviruse is a recently discovered group of viruses infecting the marine coccolithophorid E. huxleyi. They are a major cause of coccolithophore bloom termination, and DMSP concentration is increasing in the process of viral lysis. Phylogenetic evidences support that some genes are functional both in E. huxleyi and its virus (EhV). Horizontal gene transfer (HGT) of multiple functionally coupled enzymes occurs in E. huxleyi and its DNA virus EhV has been confirmed, which contributes to the diversification and adaptation of plankton in the oceans and also critically regulates virus-host infection by allowing viruses to control host metabolic pathways for their replication. Therefore, it is of particular interest to understand this host-virus interaction. On this issue, we have made a minireview of coccolithoviruses focusing on the basic characteristics, phylogenesis, horizontal gene transfer and the interaction between the host and its viruses, as well as its important role in global biogeochemical cycling.

  4. Multidecadal increase in North Atlantic coccolithophores and the potential role of rising CO₂.

    Science.gov (United States)

    Rivero-Calle, Sara; Gnanadesikan, Anand; Del Castillo, Carlos E; Balch, William M; Guikema, Seth D

    2015-12-18

    As anthropogenic carbon dioxide (CO2) emissions acidify the oceans, calcifiers generally are expected to be negatively affected. However, using data from the Continuous Plankton Recorder, we show that coccolithophore occurrence in the North Atlantic increased from ~2 to more than 20% from 1965 through 2010. We used random forest models to examine more than 20 possible environmental drivers of this change, finding that CO2 and the Atlantic Multidecadal Oscillation were the best predictors, leading us to hypothesize that higher CO2 levels might be encouraging growth. A compilation of 41 independent laboratory studies supports our hypothesis. Our study shows a long-term basin-scale increase in coccolithophores and suggests that increasing CO2 and temperature have accelerated the growth of a phytoplankton group that is important for carbon cycling. Copyright © 2015, American Association for the Advancement of Science.

  5. Multidecadal increase in North Atlantic coccolithophores and the potential role of rising CO2

    Science.gov (United States)

    Rivero-Calle, Sara; Gnanadesikan, Anand; Del Castillo, Carlos E.; Balch, William M.; Guikema, Seth D.

    2015-12-01

    As anthropogenic carbon dioxide (CO2) emissions acidify the oceans, calcifiers generally are expected to be negatively affected. However, using data from the Continuous Plankton Recorder, we show that coccolithophore occurrence in the North Atlantic increased from ~2 to more than 20% from 1965 through 2010. We used random forest models to examine more than 20 possible environmental drivers of this change, finding that CO2 and the Atlantic Multidecadal Oscillation were the best predictors, leading us to hypothesize that higher CO2 levels might be encouraging growth. A compilation of 41 independent laboratory studies supports our hypothesis. Our study shows a long-term basin-scale increase in coccolithophores and suggests that increasing CO2 and temperature have accelerated the growth of a phytoplankton group that is important for carbon cycling.

  6. Picarola margalefii, gen. et sp. nov., a new planktonic coccolithophore from NW Mediterranean waters

    Directory of Open Access Journals (Sweden)

    Lluïsa Cros

    2004-04-01

    Full Text Available A coccolithophore which is referred to a new genus Picarola gen. nov. and described as a new species Picarola margalefii sp. nov., has been observed from the NW Mediterranean. The description of the new species is based on Scanning Electronic Microscopy (SEM observations. The coccoliths of Picarola margalefii sp. nov. are muroliths that have a narrow high rim and a central area with a cross and an elongate four-sided central process. Energy dispersive X-ray microanalyses confirmed their calcareous nature. The relation between the new genus and the genera Papposphaera Tangen, Vexillarius Jordan et Chamberlain, and Turrilithus Jordan et al., is discussed. The coccolithophore Picarola margalefii gen. et sp. nov., is dedicated to Dr. Ramon Margalef.

  7. Vertical Distributions of Coccolithophores, PIC, POC, Biogenic Silica, and Chlorophyll a Throughout the Global Ocean.

    Science.gov (United States)

    Balch, William M; Bowler, Bruce C; Drapeau, David T; Lubelczyk, Laura C; Lyczkowski, Emily

    2018-01-01

    Coccolithophores are a critical component of global biogeochemistry, export fluxes, and seawater optical properties. We derive globally significant relationships to estimate integrated coccolithophore and coccolith concentrations as well as integrated concentrations of particulate inorganic carbon (PIC) from their respective surface concentration. We also examine surface versus integral relationships for other biogeochemical variables contributed by all phytoplankton (e.g., chlorophyll a and particulate organic carbon) or diatoms (biogenic silica). Integrals are calculated using both 100 m integrals and euphotic zone integrals (depth of 1% surface photosynthetically available radiation). Surface concentrations are parameterized in either volumetric units (e.g., m -3 ) or values integrated over the top optical depth. Various relationships between surface concentrations and integrated values demonstrate that when surface concentrations are above a specific threshold, the vertical distribution of the property is biased to the surface layer, and when surface concentrations are below a specific threshold, the vertical distributions of the properties are biased to subsurface maxima. Results also show a highly predictable decrease in explained-variance as vertical distributions become more vertically heterogeneous. These relationships have fundamental utility for extrapolating surface ocean color remote sensing measurements to 100 m depth or to the base of the euphotic zone, well beyond the depths of detection for passive ocean color remote sensors. Greatest integrated concentrations of PIC, coccoliths, and coccolithophores are found when there is moderate stratification at the base of the euphotic zone.

  8. Changes in calcification of coccoliths under stable atmospheric CO2

    DEFF Research Database (Denmark)

    Berger, C.; Meier, K. J. S.; Kinkel, H.

    2014-01-01

    , which constitutes the main part of the assemblage in the North Atlantic. Records of average coccolith weights from three Holocene sediment cores along a north-south transect in the North Atlantic were analysed. During the Holocene, mean weight (and therefore calcification) of Noelaerhabdaceae (Emiliania...... huxleyi and Gephyrocapsa) coccoliths decreased at the Azores (Geofar KF 16) from around 7 to 6 pg, but increased at the Rockall Plateau (ODP site 980) from around 6 to 8 pg, and at the Voring Plateau (MD08-3192) from 7 to 10 pg. The amplitude of average weight variability is within the range of glacial...... Plateau. Here, more favourable productivity conditions apparently lead to an increase in coccolith weight, either due to the capability of coccolithophore species, especially E. huxleyi, to adapt to decreasing carbonate ion concentration or due to a shift towards heavier calcifying morphotypes....

  9. Patterns of coccolithophore pigment change under global acidification conditions based on in-situ observations at BATS site between July 1990-Dec 2008

    Science.gov (United States)

    Lv, Jianhai; Kuang, Yaoqiu; Zhao, Hui; Andersson, Andreas

    2017-06-01

    Coccolith production is an important part of the biogenic carbon cycle as the largest source of calcium carbonate on earth, accounting for about 75% of the deposition of carbon on the sea floor. Recent studies based on laboratory experiment results indicated that increasing anthropogenic CO2 in the atmosphere triggered global ocean acidification leading to a decrease of calcite or aragonite saturation and calcium carbonate, and to decreasing efficiency of carbon export/pumping to deep layers. In the present study, we analyzed about 20 years of field observations of coccolithophore pigment, dissolved inorganic carbon (DIC), nutrients, and temperatures from the Bermuda Atlantic Time-series Study (BATS) site and satellite remote sensing to investigate the variable tendency of the coccolithophore pigment, and to evaluate the influence of ocean acidification on coccolithophore biomass. The results indicated that there was a generally increasing tendency of coccolithophore pigment, coupled with increasing bicarbonate concentrations or decreasing carbonate ion concentration. The change of coccolithophore pigment was also closely associated with pH, nutrients, mixed layer depth (MLD), and temperature. Correlation analyses between coccolithophores and abiotic parameter imply that coccoliths production or coccolithophore pigment has increased with increasing acidification in the recent 20 years.

  10. Detection of Coccolithophore Blooms in Ocean Color Satellite Imagery: a Generalized Approach for Use with Multiple Sensors

    Science.gov (United States)

    Moore, Timothy; Dowell, Mark; Franz, Bryan A.

    2012-01-01

    A generalized coccolithophore bloom classifier has been developed for use with ocean color imagery. The bloom classifier was developed using extracted satellite reflectance data from SeaWiFS images screened by the default bloom detection mask. In the current application, we extend the optical water type (OWT) classification scheme by adding a new coccolithophore bloom class formed from these extracted reflectances. Based on an in situ coccolithophore data set from the North Atlantic, the detection levels with the new scheme were between 1,500 and 1,800 coccolithophore cellsmL and 43,000 and 78,000 lithsmL. The detected bloom area using the OWT method was an average of 1.75 times greater than the default bloom detector based on a collection of SeaWiFS 1 km imagery. The versatility of the scheme is shown with SeaWiFS, MODIS Aqua, CZCS and MERIS imagery at the 1 km scale. The OWT scheme was applied to the daily global SeaWiFS imagery mission data set (years 19972010). Based on our results, average annual coccolithophore bloom area was more than two times greater in the southern hemisphere compared to the northern hemi- sphere with values of 2.00 106 km2 and 0.75 106 km2, respectively. The new algorithm detects larger bloom areas in the Southern Ocean compared to the default algorithm, and our revised global annual average of 2.75106 km2 is dominated by contributions from the Southern Ocean.

  11. Metabolic profiles of prokaryotic and eukaryotic communities in deep-sea sponge Neamphius huxleyi indicated by metagenomics

    Science.gov (United States)

    Li, Zhi-Yong; Wang, Yue-Zhu; He, Li-Ming; Zheng, Hua-Jun

    2014-01-01

    The whole metabolism of a sponge holobiont and the respective contributions of prokaryotic and eukaryotic symbionts and their associations with the sponge host remain largely unclear. Meanwhile, compared with shallow water sponges, deep-sea sponges are rarely understood. Here we report the metagenomic exploration of deep-sea sponge Neamphius huxleyi at the whole community level. Metagenomic data showed phylogenetically diverse prokaryotes and eukaryotes in Neamphius huxleyi. MEGAN and gene enrichment analyses indicated different metabolic potentials of prokaryotic symbionts from eukaryotic symbionts, especially in nitrogen and carbon metabolisms, and their molecular interactions with the sponge host. These results supported the hypothesis that prokaryotic and eukaryotic symbionts have different ecological roles and relationships with sponge host. Moreover, vigorous denitrification, and CO2 fixation by chemoautotrophic prokaryotes were suggested for this deep-sea sponge. The study provided novel insights into the respective potentials of prokaryotic and eukaryotic symbionts and their associations with deep-sea sponge Neamphius huxleyi. PMID:24463735

  12. Metabolic profiles of prokaryotic and eukaryotic communities in deep-sea sponge Neamphius huxleyi [corrected]. indicated by metagenomics.

    Science.gov (United States)

    Li, Zhi-Yong; Wang, Yue-Zhu; He, Li-Ming; Zheng, Hua-Jun

    2014-01-27

    The whole metabolism of a sponge holobiont and the respective contributions of prokaryotic and eukaryotic symbionts and their associations with the sponge host remain largely unclear. Meanwhile, compared with shallow water sponges, deep-sea sponges are rarely understood. Here we report the metagenomic exploration of deep-sea sponge Neamphius huxleyi [corrected] . at the whole community level. Metagenomic data showed phylogenetically diverse prokaryotes and eukaryotes in Neamphius huxleyi [corrected]. MEGAN and gene enrichment analyses indicated different metabolic potentials of prokaryotic symbionts from eukaryotic symbionts, especially in nitrogen and carbon metabolisms, and their molecular interactions with the sponge host. These results supported the hypothesis that prokaryotic and eukaryotic symbionts have different ecological roles and relationships with sponge host. Moreover, vigorous denitrification, and CO2 fixation by chemoautotrophic prokaryotes were suggested for this deep-sea sponge. The study provided novel insights into the respective potentials of prokaryotic and eukaryotic symbionts and their associations with deep-sea sponge Neamphius huxleyi [corrected].

  13. Improvement to the PhytoDOAS method for identification of coccolithophores using hyper-spectral satellite data

    Directory of Open Access Journals (Sweden)

    A. Sadeghi

    2012-11-01

    Full Text Available The goal of this study was to improve PhytoDOAS, which is a new retrieval method for quantitative identification of major phytoplankton functional types (PFTs using hyper-spectral satellite data. PhytoDOAS is an extension of the Differential Optical Absorption Spectroscopy (DOAS, a method for detection of atmospheric trace gases, developed for remote identification of oceanic phytoplankton groups. Thus far, PhytoDOAS has been successfully exploited to identify cyanobacteria and diatoms over the global ocean from SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY hyper-spectral data. This study aimed to improve PhytoDOAS for remote identification of coccolithophores, another functional group of phytoplankton. The main challenge for retrieving more PFTs by PhytoDOAS is to overcome the correlation effects between different PFT absorption spectra. Different PFTs are composed of different types and amounts of pigments, but also have pigments in common, e.g. chl a, causing correlation effects in the usual performance of the PhytoDOAS retrieval. Two ideas have been implemented to improve PhytoDOAS for the PFT retrieval of more phytoplankton groups. Firstly, using the fourth-derivative spectroscopy, the peak positions of the main pigment components in each absorption spectrum have been derived. After comparing the corresponding results of major PFTs, the optimized fit-window for the PhytoDOAS retrieval of each PFT was determined. Secondly, based on the results from derivative spectroscopy, a simultaneous fit of PhytoDOAS has been proposed and tested for a selected set of PFTs (coccolithophores, diatoms and dinoflagellates within an optimized fit-window, proven by spectral orthogonality tests. The method was then applied to the processing of SCIAMACHY data over the year 2005. Comparisons of the PhytoDOAS coccolithophore retrievals in 2005 with other coccolithophore-related data showed similar patterns in their

  14. Formonsella pyramidosa (Haptophyta, Papposphaeraceae): A new weakly calcified coccolithophore genus from warm-water regions

    DEFF Research Database (Denmark)

    Thomsen, Helge Abildhauge; Cros, Lluïsa; Malinverno, Elisa

    2016-01-01

    A new species Formonsella pyramidosa gen. et sp. nov. is described to accommodate a widely distributed warm-water coccolithophore species that has previously been referred to as Pappomonas sp. 2. Formonsella differs from Pappomonas with respect to, in particular, the detailed structure of the rim...... on both calicate and non-calicate coccoliths. In Formonsella the rim comprises two cycles of rod-shaped elements. Although elements in the distal layer are higher at one end, giving this cycle a serrate outline, the overall appearance is very different from the Pappomonas rim which encompasses a distal...... cycle of pentagonal elements, giving the rim a very distinct toothed appearance. Inverted rectangular pyramidal structures terminate the calicate F. pyramidosa coccoliths. In non-calicate coccoliths the central area calcification comprises differently sized tile-shaped elements, mostly arranged along...

  15. Reduced resilience of a globally distributed coccolithophore to ocean acidification: Confirmed up to 2000 generations

    KAUST Repository

    Jin, Peng

    2015-12-30

    © 2015 Elsevier Ltd. Ocean acidification (OA), induced by rapid anthropogenic CO2 rise and its dissolution in seawater, is known to have consequences for marine organisms. However, knowledge on the evolutionary responses of phytoplankton to OA has been poorly studied. Here we examined the coccolithophore Gephyrocapsa oceanica, while growing it for 2000 generations under ambient and elevated CO2 levels. While OA stimulated growth in the earlier selection period (from generations ~700 to ~1550), it reduced it in the later selection period up to 2000 generations. Similarly, stimulated production of particulate organic carbon and nitrogen reduced with increasing selection period and decreased under OA up to 2000 generations. The specific adaptation of growth to OA disappeared in generations 1700 to 2000 when compared with that at 1000 generations. Both phenotypic plasticity and fitness decreased within selection time, suggesting that the species\\' resilience to OA decreased after 2000 generations under high CO2 selection.

  16. Predominance of heavily calcified coccolithophores at low CaCO3 saturation during winter in the Bay of Biscay

    OpenAIRE

    Smith, Helen E. K.; Tyrrell, Toby; Charalampopoulou, Anastasia; Dumousseaud, Cynthia; Legge, Oliver J.; Birchenough, Sarah; Pettit, Laura R.; Garley, Rebecca; Hartman, Sue E.; Hartman, Mark C.; Sagoo, Navjit; Daniels, Chris J.; Achterberg, Eric P.; Hydes, David J.

    2012-01-01

    Coccolithophores are an important component of the Earth system, and, as calcifiers, their possible susceptibility to ocean acidification is of major concern. Laboratory studies at enhanced pCO2 levels have produced divergent results without overall consensus. However, it has been predicted from these studies that, although calcification may not be depressed in all species, acidification will produce “a transition in dominance from more to less heavily calcified coccolithophores” [Ridgwell A,...

  17. Coccolithophore response to the 1997-1998 El Niño in Santa Barbara Basin (California)

    NARCIS (Netherlands)

    De Bernardi, B.; Ziveri, P.; Erba, E.; Thunell, R.C.

    2005-01-01

    The response of coccolithophore export production to non-El Niño and El Niño conditions was monitored during a two year period (26 March 1996-3 April 1998) in the centre of the Santa Barbara Basin (34°14′ N; 120°02′ W), California borderland. During the 1997-1998 El Niño the seasonal cycle of the

  18. Reduced resilience of a globally distributed coccolithophore to ocean acidification: Confirmed up to 2000 generations, supplement to: Jin, Peng; Gao, Kunshan (2016): Reduced resilience of a globally distributed coccolithophore to ocean acidification: Confirmed up to 2000 generations. Marine Pollution Bulletin, 103(1-2), 101-108

    KAUST Repository

    Jin, Peng; Gao, Kunshan

    2016-01-01

    . Here we examined the coccolithophore Gephyrocapsa oceanica, while growing it for 2000 generations under ambient and elevated CO2 levels. While OA stimulated growth in the earlier selection period (from generations 700 to 1550), it reduced

  19. Phytoplankton calcification as an effective mechanism to alleviate cellular calcium poisoning

    Science.gov (United States)

    Müller, M. N.; Ramos, J. Barcelos e.; Schulz, K. G.; Riebesell, U.; Kaźmierczak, J.; Gallo, F.; Mackinder, L.; Li, Y.; Nesterenko, P. N.; Trull, T. W.; Hallegraeff, G. M.

    2015-11-01

    Marine phytoplankton have developed the remarkable ability to tightly regulate the concentration of free calcium ions in the intracellular cytosol at a level of ~ 0.1 μmol L-1 in the presence of seawater Ca2+ concentrations of 10 mmol L-1. The low cytosolic calcium ion concentration is of utmost importance for proper cell signalling function. While the regulatory mechanisms responsible for the tight control of intracellular Ca2+ concentration are not completely understood, phytoplankton taxonomic groups appear to have evolved different strategies, which may affect their ability to cope with changes in seawater Ca2+ concentrations in their environment on geological timescales. For example, the Cretaceous (145 to 66 Ma), an era known for the high abundance of coccolithophores and the production of enormous calcium carbonate deposits, exhibited seawater calcium concentrations up to 4 times present-day levels. We show that calcifying coccolithophore species (Emiliania huxleyi, Gephyrocapsa oceanica and Coccolithus braarudii) are able to maintain their relative fitness (in terms of growth rate and photosynthesis) at simulated Cretaceous seawater calcium concentrations, whereas these rates are severely reduced under these conditions in some non-calcareous phytoplankton species (Chaetoceros sp., Ceratoneis closterium and Heterosigma akashiwo). Most notably, this also applies to a non-calcifying strain of E. huxleyi which displays a calcium sensitivity similar to the non-calcareous species. We hypothesize that the process of calcification in coccolithophores provides an efficient mechanism to alleviate cellular calcium poisoning and thereby offered a potential key evolutionary advantage, responsible for the proliferation of coccolithophores during times of high seawater calcium concentrations. The exact function of calcification and the reason behind the highly ornate physical structures of coccoliths remain elusive.

  20. Phytoplankton calcification as an effective mechanism to prevent cellular calcium poisoning

    Science.gov (United States)

    Müller, M. N.; Ramos, J. Barcelos e.; Schulz, K. G.; Riebesell, U.; Kaźmierczak, J.; Gallo, F.; Mackinder, L.; Li, Y.; Nesterenko, P. N.; Trull, T. W.; Hallegraeff, G. M.

    2015-08-01

    Marine phytoplankton has developed the remarkable ability to tightly regulate the concentration of free calcium ions in the intracellular cytosol at a level of ~ 0.1 μmol L-1 in the presence of seawater Ca2+ concentrations of 10 mmol L-1. The low cytosolic calcium ion concentration is of utmost importance for proper cell signalling function. While the regulatory mechanisms responsible for the tight control of intracellular Ca2+ concentration are not completely understood, phytoplankton taxonomic groups appear to have evolved different strategies, which may affect their ability to cope with changes in seawater Ca2+ concentrations in their environment on geological time scales. For example, the Cretaceous (145 to 66 Ma ago), an era known for the high abundance of coccolithophores and the production of enormous calcium carbonate deposits, exhibited seawater calcium concentrations up to four times present-day levels. We show that calcifying coccolithophore species (Emiliania huxleyi, Gephyrocapsa oceanica and Coccolithus braarudii) are able to maintain their relative fitness (in terms of growth rate and photosynthesis) at simulated Cretaceous seawater calcium concentrations, whereas these rates are severely reduced under these conditions in some non-calcareous phytoplankton species (Chaetoceros sp., Ceratoneis closterium and Heterosigma akashiwo). Most notably, this also applies to a non-calcifying strain of E. huxleyi which displays a calcium-sensitivity similar to the non-calcareous species. We hypothesize that the process of calcification in coccolithophores provides an efficient mechanism to prevent cellular calcium poisoning and thereby offered a potential key evolutionary advantage, responsible for the proliferation of coccolithophores during times of high seawater calcium concentrations.

  1. Temperature modulates coccolithophorid sensitivity of growth, photosynthesis and calcification to increasing seawater pCO₂.

    Directory of Open Access Journals (Sweden)

    Scarlett Sett

    Full Text Available Increasing atmospheric CO₂ concentrations are expected to impact pelagic ecosystem functioning in the near future by driving ocean warming and acidification. While numerous studies have investigated impacts of rising temperature and seawater acidification on planktonic organisms separately, little is presently known on their combined effects. To test for possible synergistic effects we exposed two coccolithophore species, Emiliania huxleyi and Gephyrocapsa oceanica, to a CO₂ gradient ranging from ∼0.5-250 µmol kg⁻¹ (i.e. ∼20-6000 µatm pCO₂ at three different temperatures (i.e. 10, 15, 20°C for E. huxleyi and 15, 20, 25°C for G. oceanica. Both species showed CO₂-dependent optimum-curve responses for growth, photosynthesis and calcification rates at all temperatures. Increased temperature generally enhanced growth and production rates and modified sensitivities of metabolic processes to increasing CO₂. CO₂ optimum concentrations for growth, calcification, and organic carbon fixation rates were only marginally influenced from low to intermediate temperatures. However, there was a clear optimum shift towards higher CO₂ concentrations from intermediate to high temperatures in both species. Our results demonstrate that the CO₂ concentration where optimum growth, calcification and carbon fixation rates occur is modulated by temperature. Thus, the response of a coccolithophore strain to ocean acidification at a given temperature can be negative, neutral or positive depending on that strain's temperature optimum. This emphasizes that the cellular responses of coccolithophores to ocean acidification can only be judged accurately when interpreted in the proper eco-physiological context of a given strain or species. Addressing the synergistic effects of changing carbonate chemistry and temperature is an essential step when assessing the success of coccolithophores in the future ocean.

  2. A Taste of Algal Genomes from the Joint Genome Institute

    Energy Technology Data Exchange (ETDEWEB)

    Kuo, Alan; Grigoriev, Igor

    2012-06-17

    Algae play profound roles in aquatic food chains and the carbon cycle, can impose health and economic costs through toxic blooms, provide models for the study of symbiosis, photosynthesis, and eukaryotic evolution, and are candidate sources for bio-fuels; all of these research areas are part of the mission of DOE's Joint Genome Institute (JGI). To date JGI has sequenced, assembled, annotated, and released to the public the genomes of 18 species and strains of algae, sampling almost all of the major clades of photosynthetic eukaryotes. With more algal genomes currently undergoing analysis, JGI continues its commitment to driving forward basic and applied algal science. Among these ongoing projects are the pan-genome of the dominant coccolithophore Emiliania huxleyi, the interrelationships between the 4 genomes in the nucleomorph-containing Bigelowiella natans and Guillardia theta, and the search for symbiosis genes of lichens.

  3. Ocean acidification has different effects on the production of dimethylsulfide and dimethylsulfoniopropionate measured in cultures of Emiliania huxleyi and a mesocosm study : A comparison of laboratory monocultures and community interactions

    NARCIS (Netherlands)

    Webb, Alison L.; Malin, Gill; Hopkins, Frances E.; Ho, Kai Lam; Riebesell, Ulf; Schulz, Kai G.; Larsen, Aud; Liss, Peter S.

    2016-01-01

    Environmental context Approximately 25% of CO2 released to the atmosphere by human activities has been absorbed by the oceans, resulting in ocean acidification. We investigate the acidification effects on marine phytoplankton and subsequent production of the trace gas dimethylsulfide, a major route

  4. Ecological and taphonomical influences on coccoliths in surface sediments in the shelf of the Yellow and East China Seas

    Science.gov (United States)

    Jin, Xiaobo; Liu, Chuanlian

    2017-05-01

    Coccoliths, combined with sediment grain size, carbonate calcium and organic matters content, were analyzed to assess the ecological and taphonomical influences on coccolith distribution patterns in surface sediments in the continental shelf of the Yellow and East China Seas. Coccolith abundances ranged from 0 to 2.08×109 coccoliths g-1 sediment. The increasing abundance from the coastal inner shelf to the seaward middle shelf generally reflects the ecological fact that living coccolithophores are more abundant in the mesotrophic shelf waters than in the eutrophic coastal waters, although their deposits are still controlled by taphonomical effects, such as bottom (tidal) currents and calcite preservation conditions. Most abundant coccoliths are found in the fine-grained sediments of southwestern Cheju Island, where both ecology and taphonomy favor coccolith preservation. Still, large densities of coccoliths (>108 coccoliths g-1 sediment) are also found in coarse-grained relict sediments in the middle shelf. Coccolith assemblages were predominated by Gephyrocapsa oceanica and Emiliania huxleyi. The relative abundance of E. huxleyi, in addition to ecological reasons, may relate to selective post-mortem dissolution, since small E. huxleyi coccoliths are more susceptible to dissolution. Coccolith calcite has minor contributions (<1% to 12%) to total sediment CaCO3, and the main parts are attributed to terrigenous CaCO3 debris and relict shell fragments.

  5. Increasing costs due to ocean acidification drives phytoplankton to be more heavily calcified: optimal growth strategy of coccolithophores.

    Directory of Open Access Journals (Sweden)

    Takahiro Irie

    Full Text Available Ocean acidification is potentially one of the greatest threats to marine ecosystems and global carbon cycling. Amongst calcifying organisms, coccolithophores have received special attention because their calcite precipitation plays a significant role in alkalinity flux to the deep ocean (i.e., inorganic carbon pump. Currently, empirical effort is devoted to evaluating the plastic responses to acidification, but evolutionary considerations are missing from this approach. We thus constructed an optimality model to evaluate the evolutionary response of coccolithophorid life history, assuming that their exoskeleton (coccolith serves to reduce the instantaneous mortality rates. Our model predicted that natural selection favors constructing more heavily calcified exoskeleton in response to increased acidification-driven costs. This counter-intuitive response occurs because the fitness benefit of choosing a better-defended, slower growth strategy in more acidic conditions, outweighs that of accelerating the cell cycle, as this occurs by producing less calcified exoskeleton. Contrary to the widely held belief, the evolutionarily optimized population can precipitate larger amounts of CaCO(3 during the bloom in more acidified seawater, depending on parameter values. These findings suggest that ocean acidification may enhance the calcification rates of marine organisms as an adaptive response, possibly accompanied by higher carbon fixation ability. Our theory also provides a compelling explanation for the multispecific fossil time-series record from ∼200 years ago to present, in which mean coccolith size has increased along with rising atmospheric CO(2 concentration.

  6. Nannoplankton and uranium concentration relations in the Black Sea Deposits

    Directory of Open Access Journals (Sweden)

    Vedia TOKER

    1983-12-01

    Full Text Available Nannoplanktons obtained from sixty-two core samples taken from twenty-three holes penetrated in the Southern part of Black Sea were investigated in this work. Twelve species belonging to the Emiliania huxleyi zone (NN 21-Holocene were determined. Emiliania huxleyi (Lohmann came into existence in Black Sea three thousand years ago and is very abundant in these sediments. This study clearly showed that uranium concentration increases with increasing nannoplankton content of the sediments. It is also observed that the uranium oxide (U3O8 contents of the Emiliania huxleyi (Lohmann accumulations on the abyssal plains are higher than those other sediments in the same environments.

  7. Phytoplankton composition and biomass across the southern Indian Ocean

    DEFF Research Database (Denmark)

    Schlüter, Louise; Henriksen, Peter; Nielsen, Torkel Gissel

    2011-01-01

    prochlorophytes dominated at these two stations, but also pelagophytes, haptophytes and cyanobacteria were abundant. Haptophytes Type 6 (sensu Zapata et al., 2004), most likely Emiliania huxleyi, and pelagophytes were the dominating eucaryotes in the southern Indian Ocean. Prochlorophytes dominated...

  8. Controls over δ44/40Ca and Sr/Ca variations in coccoliths: New perspectives from laboratory cultures and cellular models

    Science.gov (United States)

    Mejía, Luz María; Paytan, Adina; Eisenhauer, Anton; Böhm, Florian; Kolevica, Ana; Bolton, Clara; Méndez-Vicente, Ana; Abrevaya, Lorena; Isensee, Kirsten; Stoll, Heather

    2018-01-01

    Coccoliths comprise a major fraction of the global carbonate sink. Therefore, changes in coccolithophores' Ca isotopic fractionation could affect seawater Ca isotopic composition, affecting interpretations of the global Ca cycle and related changes in seawater chemistry and climate. Despite this, a quantitative interpretation of coccolith Ca isotopic fractionation and a clear understanding of the mechanisms driving it are not yet available. Here, we address this gap in knowledge by developing a simple model (CaSri-Co) to track coccolith Ca isotopic fractionation during cellular Ca uptake and allocation to calcification. We then apply it to published and new δ 44 / 40 Ca and Sr/Ca data of cultured coccolithophores of the species Emiliania huxleyi and Gephyrocapsa oceanica. We identify changes in calcification rates, Ca retention efficiency and solvation-desolvation rates as major drivers of the Ca isotopic fractionation and Sr/Ca variations observed in cultures. Higher calcification rates, higher Ca retention efficiencies and lower solvation-desolvation rates increase both coccolith Ca isotopic fractionation and Sr/Ca. Coccolith Ca isotopic fractionation is most sensitive to changes in solvation-desolvation rates. Changes in Ca retention efficiency may be a major driver of coccolith Sr/Ca variations in cultures. We suggest that substantial changes in the water structure strength caused by past changes in temperature could have induced significant changes in coccolithophores' Ca isotopic fractionation, potentially having some influence on seawater Ca isotopic composition. We also suggest a potential effect on Ca isotopic fractionation via modification of the solvation environment through cellular exudates, a hypothesis that remains to be tested.

  9. Phytoplankton growth inhibited by the toxic and bacterivorous ciliate

    NARCIS (Netherlands)

    Schaafsma, F.L.; Peperzak, L.

    2013-01-01

    The ubiquitous marine ciliate Uronema marinum is mainly bacterivorous. It was therefore surprising that in a ciliate-contaminated experiment the growth rate of the phytoplankton species Emiliania huxleyi was significantly reduced. As U. marinum does not ingest E. huxleyi cells, their growth

  10. Phytoplankton growth inhibited by the toxic and bacterivorous ciliate Uronema marinum (Protozoa, Ciliophora)

    NARCIS (Netherlands)

    Schaafsma, F. L.; Peperzak, L.

    2013-01-01

    The ubiquitous marine ciliate Uronema marinum is mainly bacterivorous. It was therefore surprising that in a ciliate-contaminated experiment the growth rate of the phytoplankton species Emiliania huxleyi was significantly reduced. As U. marinum does not ingest E. huxleyi cells, their growth

  11. A coccolithophore based view on paleoenvironmental changes in the open ocean mid-latitude North Atlantic between 130 and 48ka BP with special emphasis on MIS 5e

    DEFF Research Database (Denmark)

    Schwab, C.; Kinkel, Hanno; Weinelt, M.

    2013-01-01

    in coccolithophore assemblages and changes in the abundance of siliceous plankton (diatoms) indicate a southward shift of the Azores Front (AzF), and hence a southward retreat of the North Atlantic subtropical gyre, as well as an increased productivity, during glacial Marine Isotope Stage (MIS) 4, Termination II...... and during cold substages of MIS 5. Furthermore we hypothesize that the ecological changes led to distinct evolutionary patterns of coccolithophores, resulting e.g. in a dominance of Gephyrocapsa ornata between 76 and 105ka BP. Additionally, high-resolution analysis of MIS 5e indicate a short reversal...... towards cool conditions during MIS 5e, corresponding to a basin-wide cooling event. Full interglacial conditions are reached only late in the Azores region. During MIS 5e an increased advection of Subantarctic Mode Water (SAMW), and/or the possibility to occupy new habitats after glacial conditions...

  12. Reduced resilience of a globally distributed coccolithophore to ocean acidification: Confirmed up to 2000 generations, supplement to: Jin, Peng; Gao, Kunshan (2016): Reduced resilience of a globally distributed coccolithophore to ocean acidification: Confirmed up to 2000 generations. Marine Pollution Bulletin, 103(1-2), 101-108

    KAUST Repository

    Jin, Peng

    2016-01-01

    Ocean acidification (OA), induced by rapid anthropogenic CO2 rise and its dissolution in seawater, is known to have consequences for marine organisms. However, knowledge on the evolutionary responses of phytoplankton to OA has been poorly studied. Here we examined the coccolithophore Gephyrocapsa oceanica, while growing it for 2000 generations under ambient and elevated CO2 levels. While OA stimulated growth in the earlier selection period (from generations 700 to 1550), it reduced it in the later selection period up to 2000 generations. Similarly, stimulated production of particulate organic carbon and nitrogen reduced with increasing selection period and decreased under OA up to 2000 generations. The specific adaptation of growth to OA disappeared in generations 1700 to 2000 when compared with that at 1000 generations. Both phenotypic plasticity and fitness decreased within selection time, suggesting that the species\\' resilience to OA decreased after 2000 generations under high CO2 selection.

  13. Nano-Scale Spatial Assessment of Calcium Distribution in Coccolithophores Using Synchrotron-Based Nano-CT and STXM-NEXAFS

    Science.gov (United States)

    Sun, Shiyong; Yao, Yanchen; Zou, Xiang; Fan, Shenglan; Zhou, Qing; Dai, Qunwei; Dong, Faqin; Liu, Mingxue; Nie, Xiaoqin; Tan, Daoyong; Li, Shuai

    2014-01-01

    Calcified coccolithophores generate calcium carbonate scales around their cell surface. In light of predicted climate change and the global carbon cycle, the biomineralization ability of coccoliths has received growing interest. However, the underlying biomineralization mechanism is not yet well understood; the lack of non-invasive characterizing tools to obtain molecular level information involving biogenic processes and biomineral components remain significant challenges. In the present study, synchrotron-based Nano-computed Tomography (Nano-CT) and Scanning Transmission X-ray Microscopy-Near-edge X-ray Absorption Fine Structure Spectromicroscopy (STXM-NEXAFS) techniques were employed to identify Ca spatial distribution and investigate the compositional chemistry and distinctive features of the association between biomacromolecules and mineral components of calcite present in coccoliths. The Nano-CT results show that the coccolith scale vesicle is similar as a continuous single channel. The mature coccoliths were intracellularly distributed and immediately ejected and located at the exterior surface to form a coccoshpere. The NEXAFS spectromicroscopy results of the Ca L edge clearly demonstrate the existence of two levels of gradients spatially, indicating two distinctive forms of Ca in coccoliths: a crystalline-poor layer surrounded by a relatively crystalline-rich layer. The results show that Sr is absorbed by the coccoliths and that Sr/Ca substitution is rather homogeneous within the coccoliths. Our findings indicate that synchrotron-based STXM-NEXAFS and Nano-CT are excellent tools for the study of biominerals and provide information to clarify biomineralization mechanism. PMID:25530614

  14. An unaccounted fraction of marine biogenic CaCO3 particles.

    Directory of Open Access Journals (Sweden)

    Mikal Heldal

    Full Text Available Biogenic production and sedimentation of calcium carbonate in the ocean, referred to as the carbonate pump, has profound implications for the ocean carbon cycle, and relate both to global climate, ocean acidification and the geological past. In marine pelagic environments coccolithophores, foraminifera and pteropods have been considered the main calcifying organisms. Here, we document the presence of an abundant, previously unaccounted fraction of marine calcium carbonate particles in seawater, presumably formed by bacteria or in relation to extracellular polymeric substances. The particles occur in a variety of different morphologies, in a size range from 100 µm, and in a typical concentration of 10(4-10(5 particles L(-1 (size range counted 1-100 µm. Quantitative estimates of annual averages suggests that the pure calcium particles we counted in the 1-100 µm size range account for 2-4 times more CaCO(3 than the dominating coccolithophoride Emiliania huxleyi and for 21% of the total concentration of particulate calcium. Due to their high density, we hypothesize that the particles sediment rapidly, and therefore contribute significantly to the export of carbon and alkalinity from surface waters. The biological and environmental factors affecting the formation of these particles and possible impact of this process on global atmospheric CO(2 remains to be investigated.

  15. Methanol Production by a Broad Phylogenetic Array of Marine Phytoplankton.

    Directory of Open Access Journals (Sweden)

    Tracy J Mincer

    Full Text Available Methanol is a major volatile organic compound on Earth and serves as an important carbon and energy substrate for abundant methylotrophic microbes. Previous geochemical surveys coupled with predictive models suggest that the marine contributions are exceedingly large, rivaling terrestrial sources. Although well studied in terrestrial ecosystems, methanol sources are poorly understood in the marine environment and warrant further investigation. To this end, we adapted a Purge and Trap Gas Chromatography/Mass Spectrometry (P&T-GC/MS method which allowed reliable measurements of methanol in seawater and marine phytoplankton cultures with a method detection limit of 120 nanomolar. All phytoplankton tested (cyanobacteria: Synechococcus spp. 8102 and 8103, Trichodesmium erythraeum, and Prochlorococcus marinus, and Eukarya (heterokont diatom: Phaeodactylum tricornutum, coccolithophore: Emiliania huxleyi, cryptophyte: Rhodomonas salina, and non-diatom heterokont: Nannochloropsis oculata produced methanol, ranging from 0.8-13.7 micromolar in culture and methanol per total cellular carbon were measured in the ranges of 0.09-0.3%. Phytoplankton culture time-course measurements displayed a punctuated production pattern with maxima near early stationary phase. Stabile isotope labeled bicarbonate incorporation experiments confirmed that methanol was produced from phytoplankton biomass. Overall, our findings suggest that phytoplankton are a major source of methanol in the upper water column of the world's oceans.

  16. Coccolith Assemblages and Primary Productivity Variations in the Central Western Pacific Warm Pool Over the Last 380 kyr

    Science.gov (United States)

    Liang, Dan; Liu, Chuanlian

    2018-06-01

    Coccolith assemblages in two gravity cores (KX21-2 and KX12-1) from the central Western Pacific Warm Pool (WPWP) have been analyzed with SYRACO. The variations of nutricline and primary productivity ( PP) have been reconstructed based on these assemblages. The results show that the coccolith assemblages were dominated by Florisphaera profunda, Gephyrocapsa and Emiliania huxleyi over the last 380 kyr. Variations of nutricline and primary productivity can be divided into three intervals. Interval I (about 380-300 kyr): PP was high and nutricline was shallow; Interval II (about 300-160 kyr): PP decreased dramatically for a short time after the acme of G. caribbeanica in Mid-Brunhes while nutricline became deeper; Interval III (about 160 kyr-present): PP fluctuated at low levels and nutricline was deep. Variations of each coccolith taxon and PP were highly correlated in the two cores, which means that the geological environment is similar in the two cores. Spectrum analysis is performed for all coccolith taxons and PP, and the 19-kyr cycle is the most prominent. It means that the production of coccolithophores in the WPWP is mainly controlled by precession.

  17. Methanol Production by a Broad Phylogenetic Array of Marine Phytoplankton.

    Science.gov (United States)

    Mincer, Tracy J; Aicher, Athena C

    2016-01-01

    Methanol is a major volatile organic compound on Earth and serves as an important carbon and energy substrate for abundant methylotrophic microbes. Previous geochemical surveys coupled with predictive models suggest that the marine contributions are exceedingly large, rivaling terrestrial sources. Although well studied in terrestrial ecosystems, methanol sources are poorly understood in the marine environment and warrant further investigation. To this end, we adapted a Purge and Trap Gas Chromatography/Mass Spectrometry (P&T-GC/MS) method which allowed reliable measurements of methanol in seawater and marine phytoplankton cultures with a method detection limit of 120 nanomolar. All phytoplankton tested (cyanobacteria: Synechococcus spp. 8102 and 8103, Trichodesmium erythraeum, and Prochlorococcus marinus), and Eukarya (heterokont diatom: Phaeodactylum tricornutum, coccolithophore: Emiliania huxleyi, cryptophyte: Rhodomonas salina, and non-diatom heterokont: Nannochloropsis oculata) produced methanol, ranging from 0.8-13.7 micromolar in culture and methanol per total cellular carbon were measured in the ranges of 0.09-0.3%. Phytoplankton culture time-course measurements displayed a punctuated production pattern with maxima near early stationary phase. Stabile isotope labeled bicarbonate incorporation experiments confirmed that methanol was produced from phytoplankton biomass. Overall, our findings suggest that phytoplankton are a major source of methanol in the upper water column of the world's oceans.

  18. Methanol Production by a Broad Phylogenetic Array of Marine Phytoplankton

    Science.gov (United States)

    Mincer, Tracy J.; Aicher, Athena C.

    2016-01-01

    Methanol is a major volatile organic compound on Earth and serves as an important carbon and energy substrate for abundant methylotrophic microbes. Previous geochemical surveys coupled with predictive models suggest that the marine contributions are exceedingly large, rivaling terrestrial sources. Although well studied in terrestrial ecosystems, methanol sources are poorly understood in the marine environment and warrant further investigation. To this end, we adapted a Purge and Trap Gas Chromatography/Mass Spectrometry (P&T-GC/MS) method which allowed reliable measurements of methanol in seawater and marine phytoplankton cultures with a method detection limit of 120 nanomolar. All phytoplankton tested (cyanobacteria: Synechococcus spp. 8102 and 8103, Trichodesmium erythraeum, and Prochlorococcus marinus), and Eukarya (heterokont diatom: Phaeodactylum tricornutum, coccolithophore: Emiliania huxleyi, cryptophyte: Rhodomonas salina, and non-diatom heterokont: Nannochloropsis oculata) produced methanol, ranging from 0.8–13.7 micromolar in culture and methanol per total cellular carbon were measured in the ranges of 0.09–0.3%. Phytoplankton culture time-course measurements displayed a punctuated production pattern with maxima near early stationary phase. Stabile isotope labeled bicarbonate incorporation experiments confirmed that methanol was produced from phytoplankton biomass. Overall, our findings suggest that phytoplankton are a major source of methanol in the upper water column of the world’s oceans. PMID:26963515

  19. Bacterial Infochemicals are Drivers of Algal Lysis

    Science.gov (United States)

    Whalen, K.; Deering, R.; Rowley, D. C.; El Gamal, A.; Schorn, M.; Moore, B. S.; Johnson, M. D.; Mincer, T. J.; Harvey, E.

    2016-02-01

    Processing of organic matter by bacteria forces oceanic biogeochemical cycles, food web structure and ultimately environmental stoichiometry. A newly emerging picture of the microbial loop suggests that bacteria are not merely passive recipients of dissolved organic matter (DOM) from phytoplankton exudate. Rather, heterotrophic bacteria can mediate the flow of DOM by actively producing soluble algicidal compounds. However, deciphering those chemical signals that determine these interactions has remained a challenge. Here, we report the isolation of 2-heptyl-4-quinolone (HHQ), released by Pseudoalteromonas piscicida, a marine gamma-proteobacteria isolated from plastic debris in the North Atlantic. Both 2-heptyl-3-hydroxy-4-quinolone and its immediate precursor, HHQ are known to function as antibiotics and quorum sensing signaling molecules with crucial roles in virulence, and apoptosis in eukaryotic cells (e.g. fungi and mammalian cells). Our ecologically-relevant screening of live cells and filtrate from P. piscicida cultures caused a significant decrease in the growth rate of the bloom-forming coccolithophore, Emiliania huxleyi. Bioassay-guided fraction of P. piscicida extracellular crude extracts identified HHQ, which induced mortality in three strains of E. huxleyi with an IC50 in the nanomolar range. In contrast, the marine chlorophyte, Dunaliella tertiolecta and diatom, Phaeodactylum tricornutum were unaffected by HHQ exposures (IC50 > 10 micromolar), but were susceptible to extracts of P. piscicida, indicating this bacterium may produce a cocktail of algicidal compounds specific to different phytoplankton guilds. The ability of HHQ to influence phytoplankton growth suggests that alkylquinolone-signaling molecules play a fundamental role in interkingdom interactions, ultimately influencing shifts in phytoplankton population dynamics. This study implicates a new role for HHQ beyond its importance in quorum sensing.

  20. High nitrate to phosphorus regime attenuates negative effects of rising pCO2 on total population carbon accumulation

    Directory of Open Access Journals (Sweden)

    S. A. Krug

    2012-03-01

    Full Text Available The ongoing rise in atmospheric pCO2 and consequent increase in ocean acidification have direct effects on marine calcifying phytoplankton, which potentially alters carbon export. To date it remains unclear, firstly, how nutrient regime, in particular by coccolithophores preferred phosphate limitation, interacts with pCO2 on particulate carbon accumulation; secondly, how direct physiological responses on the cellular level translate into total population response. In this study, cultures of Emiliania huxleyi were full-factorially exposed to two different N:P regimes and three different pCO2 levels. Cellular biovolume and PIC and POC content significantly declined in response to pCO2 in both nutrient regimes. Cellular PON content significantly increased in the Redfield treatment and decreased in the high N:P regime. Cell abundance significantly declined in the Redfield and remained constant in the high N:P regime. We hypothesise that in the high N:P regime severe phosphorous limitation could be compensated either by reduced inorganic phosphorous demand and/or by enzymatic uptake of organic phosphorous. In the Redfield regime we suggest that enzymatic phosphorous uptake to supplement enhanced phosphorous demand with pCO2 was not possible and thus cell abundance declined. These hypothesised different physiological responses of E. huxleyi among the nutrient regimes significantly altered population carrying capacities along the pCO2 gradient. This ultimately led to the attenuated total population response in POC and PIC content and biovolume to increased pCO2 in the high N:P regime. Our results point to the fact that the physiological (i.e. cellular PIC and POC response to ocean acidification cannot be linearly extrapolated to total population response and thus carbon export. It is therefore necessary to consider both effects of nutrient limitation on cell physiology and their consequences for population size when predicting the influence of

  1. From laboratory manipulations to Earth system models: scaling calcification impacts of ocean acidification

    Directory of Open Access Journals (Sweden)

    J. R. Young

    2009-11-01

    Full Text Available The observed variation in the calcification responses of coccolithophores to changes in carbonate chemistry paints a highly incoherent picture, particularly for the most commonly cultured "species", Emiliania huxleyi. The disparity between magnitude and potentially even sign of the calcification change under simulated end-of-century ocean surface chemical changes (higher pCO2, lower pH and carbonate saturation, raises challenges to quantifying future carbon cycle impacts and feedbacks because it introduces significant uncertainty in parameterizations used for global models. Here we compile the results of coccolithophore carbonate chemistry manipulation experiments and review how ocean carbon cycle models have attempted to bridge the gap from experiments to global impacts. Although we can rule out methodological differences in how carbonate chemistry is altered as introducing an experimental bias, the absence of a consistent calcification response implies that model parameterizations based on small and differing subsets of experimental observations will lead to varying estimates for the global carbon cycle impacts of ocean acidification. We highlight two pertinent observations that might help: (1 the degree of coccolith calcification varies substantially, both between species and within species across different genotypes, and (2 the calcification response across mesocosm and shipboard incubations has so-far been found to be relatively consistent. By analogy to descriptions of plankton growth rate vs. temperature, such as the "Eppley curve", which seek to encapsulate the net community response via progressive assemblage change rather than the response of any single species, we posit that progressive future ocean acidification may drive a transition in dominance from more to less heavily calcified coccolithophores. Assemblage shift may be more important to integrated community calcification response than species

  2. Calcareous nannoplankton dating of the Late Quaternary deposits in Greece and the eastern Mediterranean: Case studies from terrestrial and marine sites

    Directory of Open Access Journals (Sweden)

    Maria V. Triantaphyllou

    2015-10-01

    Full Text Available The distribution and abundance of Emiliania huxleyi (E. huxleyi assemblages in the marine sediments of the Aravonitsa Plateau, Greece, and from the eastern Mediterranean are used (1 to evaluate the calcareous nannoplankton NN21a and NN21b biozones and the NN21a/NN21b boundary, and (2 to analyze the palaeoenvironmental and palaeoclimatic conditions prevailing in this interval. The sediment succession displays varied E. huxleyi assemblages and these are interpreted as reflecting climatic variability during marine isotope stages MIS 1–8.

  3. Salinity dependent hydrogen isotope fractionation in alkenones produced by coastal and open ocean haptophyte algae

    NARCIS (Netherlands)

    M'boule, D.; Chivall, D.; Sinke-Schoen, D.; Sinninghe Damsté, J.S.; Schouten, S.; van der Meer, M.T.J.

    2014-01-01

    The hydrogen isotope fractionation in alkenones produced by haptophyte algae is a promising new proxy for paleosalinity reconstructions. To constrain and further develop this proxy the coastal haptophyte Isochrysis galbana and the open ocean haptophyte alga Emiliania huxleyi were cultured at

  4. Dynamics regulating major trends in Barents Sea temperatures and subsequent effect on remotely sensed particulate inorganic carbon

    DEFF Research Database (Denmark)

    Hovland, Erlend Kjeldsberg; Dierssen, Heidi M.; Ferreira, Ana Sofia

    2013-01-01

    A more comprehensive understanding of how ocean temperatures influence coccolithophorid production of particulate inorganic carbon (PIC) will make it easier to constrain the effect of ocean acidification in the future. We studied the effect of temperature on Emiliania huxleyi PIC production...

  5. Reticulofenestra calicis n. sp., an unusual small reticulofenestrid coccolith from the lower pliocene of the South Caribbean Sea

    DEFF Research Database (Denmark)

    Crudeli, D.; Kinkel, Hanno

    2004-01-01

    occasionally has few slits between the distal shield elements. Attribution to the genera Reticulofenestra instead of Pseudoemiliania is discussed in detail. R. calicis n. sp. is structurally similar to the modern Emiliania huxleyi var. corona and to Reticulofenestra maceria. R. calicis n. sp., readily...

  6. Biomineralization

    DEFF Research Database (Denmark)

    Sand, K. K.; Pedersen, C. S.; Sjöberg, S.

    2014-01-01

    a modern coccolithophorid, Emiliania huxleyi. We generated surface complexation constants for the branch components: malonate: 14.25 ± 0.17, succinate: 11.91 ± 0.06, tricarballylate: 14.86 ± 0.04, and citrate: 15.25 ± 0.04. The implication is that complex PS could hold promise for smart material...

  7. Ancient DNA derived from alkenone-biosynthesizing haptophytes and other algae in Holocene sediments from the Black Sea

    NARCIS (Netherlands)

    Coolen, M.J.L.; Boere, A.; Abbas, M.; Wakeham, S.G.; Sinninghe Damsté, J.S.

    2006-01-01

    Holocene sea surface temperatures (SST) of the Black Sea have been reconstructed using sedimentary C37 unsaturated alkenones assumed to be derived from the coccolithophorid haptophyte Emiliania huxleyi, whose fossil coccoliths are an important constituent of the unit I sediments. However,

  8. Seasonal diversity and dynamics of haptophytes in the Skagerrak, Norway, explored by high-throughput sequencing

    Science.gov (United States)

    Egge, Elianne Sirnæs; Johannessen, Torill Vik; Andersen, Tom; Eikrem, Wenche; Bittner, Lucie; Larsen, Aud; Sandaa, Ruth-Anne; Edvardsen, Bente

    2015-01-01

    Microalgae in the division Haptophyta play key roles in the marine ecosystem and in global biogeochemical processes. Despite their ecological importance, knowledge on seasonal dynamics, community composition and abundance at the species level is limited due to their small cell size and few morphological features visible under the light microscope. Here, we present unique data on haptophyte seasonal diversity and dynamics from two annual cycles, with the taxonomic resolution and sampling depth obtained with high-throughput sequencing. From outer Oslofjorden, S Norway, nano- and picoplanktonic samples were collected monthly for 2 years, and the haptophytes targeted by amplification of RNA/cDNA with Haptophyta-specific 18S rDNA V4 primers. We obtained 156 operational taxonomic units (OTUs), from c. 400.000 454 pyrosequencing reads, after rigorous bioinformatic filtering and clustering at 99.5%. Most OTUs represented uncultured and/or not yet 18S rDNA-sequenced species. Haptophyte OTU richness and community composition exhibited high temporal variation and significant yearly periodicity. Richness was highest in September–October (autumn) and lowest in April–May (spring). Some taxa were detected all year, such as Chrysochromulina simplex, Emiliania huxleyi and Phaeocystis cordata, whereas most calcifying coccolithophores only appeared from summer to early winter. We also revealed the seasonal dynamics of OTUs representing putative novel classes (clades HAP-3–5) or orders (clades D, E, F). Season, light and temperature accounted for 29% of the variation in OTU composition. Residual variation may be related to biotic factors, such as competition and viral infection. This study provides new, in-depth knowledge on seasonal diversity and dynamics of haptophytes in North Atlantic coastal waters. PMID:25893259

  9. Laboratory-grown coccoliths exhibit no vital effect in clumped isotope (Δ47) composition on a range of geologically relevant temperatures

    Science.gov (United States)

    Katz, Amandine; Bonifacie, Magali; Hermoso, Michaël; Cartigny, Pierre; Calmels, Damien

    2017-07-01

    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 past 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-inferred 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.

  10. Elucidating the composition and conservation of the autophagy pathway in photosynthetic eukaryotes

    Science.gov (United States)

    Shemi, Adva; Ben-Dor, Shifra; Vardi, Assaf

    2015-01-01

    Aquatic photosynthetic eukaryotes represent highly diverse groups (green, red, and chromalveolate algae) derived from multiple endosymbiosis events, covering a wide spectrum of the tree of life. They are responsible for about 50% of the global photosynthesis and serve as the foundation for oceanic and fresh water food webs. Although the ecophysiology and molecular ecology of some algal species are extensively studied, some basic aspects of algal cell biology are still underexplored. The recent wealth of genomic resources from algae has opened new frontiers to decipher the role of cell signaling pathways and their function in an ecological and biotechnological context. Here, we took a bioinformatic approach to explore the distribution and conservation of TOR and autophagy-related (ATG) proteins (Atg in yeast) in diverse algal groups. Our genomic analysis demonstrates conservation of TOR and ATG proteins in green algae. In contrast, in all 5 available red algal genomes, we could not detect the sequences that encode for any of the 17 core ATG proteins examined, albeit TOR and its interacting proteins are conserved. This intriguing data suggests that the autophagy pathway is not conserved in red algae as it is in the entire eukaryote domain. In contrast, chromalveolates, despite being derived from the red-plastid lineage, retain and express ATG genes, which raises a fundamental question regarding the acquisition of ATG genes during algal evolution. Among chromalveolates, Emiliania huxleyi (Haptophyta), a bloom-forming coccolithophore, possesses the most complete set of ATG genes, and may serve as a model organism to study autophagy in marine protists with great ecological significance. PMID:25915714

  11. Seasonal diversity and dynamics of haptophytes in the Skagerrak, Norway, explored by high-throughput sequencing.

    Science.gov (United States)

    Egge, Elianne Sirnaes; Johannessen, Torill Vik; Andersen, Tom; Eikrem, Wenche; Bittner, Lucie; Larsen, Aud; Sandaa, Ruth-Anne; Edvardsen, Bente

    2015-06-01

    Microalgae in the division Haptophyta play key roles in the marine ecosystem and in global biogeochemical processes. Despite their ecological importance, knowledge on seasonal dynamics, community composition and abundance at the species level is limited due to their small cell size and few morphological features visible under the light microscope. Here, we present unique data on haptophyte seasonal diversity and dynamics from two annual cycles, with the taxonomic resolution and sampling depth obtained with high-throughput sequencing. From outer Oslofjorden, S Norway, nano- and picoplanktonic samples were collected monthly for 2 years, and the haptophytes targeted by amplification of RNA/cDNA with Haptophyta-specific 18S rDNA V4 primers. We obtained 156 operational taxonomic units (OTUs), from c. 400.000 454 pyrosequencing reads, after rigorous bioinformatic filtering and clustering at 99.5%. Most OTUs represented uncultured and/or not yet 18S rDNA-sequenced species. Haptophyte OTU richness and community composition exhibited high temporal variation and significant yearly periodicity. Richness was highest in September-October (autumn) and lowest in April-May (spring). Some taxa were detected all year, such as Chrysochromulina simplex, Emiliania huxleyi and Phaeocystis cordata, whereas most calcifying coccolithophores only appeared from summer to early winter. We also revealed the seasonal dynamics of OTUs representing putative novel classes (clades HAP-3-5) or orders (clades D, E, F). Season, light and temperature accounted for 29% of the variation in OTU composition. Residual variation may be related to biotic factors, such as competition and viral infection. This study provides new, in-depth knowledge on seasonal diversity and dynamics of haptophytes in North Atlantic coastal waters. © 2015 The Authors. Molecular Ecology Published by John Wiley & Sons Ltd.

  12. A data-model synthesis to explain variability in calcification observed during a CO2 perturbation mesocosm experiment

    Science.gov (United States)

    Krishna, Shubham; Schartau, Markus

    2017-04-01

    The effect of ocean acidification on growth and calcification of the marine algae Emiliania huxleyi was investigated in a series of mesocosm experiments where enclosed water volumes that comprised a natural plankton community were exposed to different carbon dioxide (CO2) concentrations. Calcification rates observed during those experiments were found to be highly variable, even among replicate mesocosms that were subject to similar CO2 perturbations. Here, data from an ocean acidification mesocosm experiment are reanalysed with an optimality-based dynamical plankton model. According to our model approach, cellular calcite formation is sensitive to variations in CO2 at the organism level. We investigate the temporal changes and variability in observations, with a focus on resolving observed differences in total alkalinity and particulate inorganic carbon (PIC). We explore how much of the variability in the data can be explained by variations of the initial conditions and by the level of CO2 perturbation. Nine mesocosms of one experiment were sorted into three groups of high, medium, and low calcification rates and analysed separately. The spread of the three optimised ensemble model solutions captures most of the observed variability. Our results show that small variations in initial abundance of coccolithophores and the prevailing physiological acclimation states generate differences in calcification that are larger than those induced by ocean acidification. Accordingly, large deviations between optimal mass flux estimates of carbon and of nitrogen are identified even between mesocosms that were subject to similar ocean acidification conditions. With our model-based data analysis we document how an ocean acidification response signal in calcification can be disentangled from the observed variability in PIC.

  13. Influence of plankton community structure on the sinking velocity of marine aggregates

    Science.gov (United States)

    Bach, L. T.; Boxhammer, T.; Larsen, A.; Hildebrandt, N.; Schulz, K. G.; Riebesell, U.

    2016-08-01

    About 50 Gt of carbon is fixed photosynthetically by surface ocean phytoplankton communities every year. Part of this organic matter is reprocessed within the plankton community to form aggregates which eventually sink and export carbon into the deep ocean. The fraction of organic matter leaving the surface ocean is partly dependent on aggregate sinking velocity which accelerates with increasing aggregate size and density, where the latter is controlled by ballast load and aggregate porosity. In May 2011, we moored nine 25 m deep mesocosms in a Norwegian fjord to assess on a daily basis how plankton community structure affects material properties and sinking velocities of aggregates (Ø 80-400 µm) collected in the mesocosms' sediment traps. We noted that sinking velocity was not necessarily accelerated by opal ballast during diatom blooms, which could be due to relatively high porosity of these rather fresh aggregates. Furthermore, estimated aggregate porosity (Pestimated) decreased as the picoautotroph (0.2-2 µm) fraction of the phytoplankton biomass increased. Thus, picoautotroph-dominated communities may be indicative for food webs promoting a high degree of aggregate repackaging with potential for accelerated sinking. Blooms of the coccolithophore Emiliania huxleyi revealed that cell concentrations of 1500 cells/mL accelerate sinking by about 35-40%, which we estimate (by one-dimensional modeling) to elevate organic matter transfer efficiency through the mesopelagic from 14 to 24%. Our results indicate that sinking velocities are influenced by the complex interplay between the availability of ballast minerals and aggregate packaging; both of which are controlled by plankton community structure.

  14. Coccolith distribution patterns in South Atlantic and Southern Ocean surface sediments in relation to environmental gradients

    DEFF Research Database (Denmark)

    Boeckel, B.; Baumann, K.-H.; Henrich, R.

    2006-01-01

    affinities were ascertained. In general, Emiliania huxleyi is the most abundant species of the recent coccolith assemblages in the study region. However, the lower photic zone taxa, composed of Florisphaera profunda and Gladiolithus flabellatus often dominate the assemblages between 20°N and 30°S. If E....... huxleyi is excluded, Calcidiscus leptoporus and F. profunda become the most abundant species, each dominating discrete oceanographic regimes. While F. profunda is very abundant in the sediments underneath warmer, stratified surface waters with a deep nutricline, Calcidiscus leptoporus is encountered...

  15. Phylogenetic distribution of roseobacticides in the Roseobacter group and their effect on microalgae

    DEFF Research Database (Denmark)

    Sonnenschein, Eva C.; Phippen, Christopher Broughton William; Bentzon-Tilia, Mikkel

    2018-01-01

    not produce roseobacticides, possibly due to a transposable element. TDA-producing Ruegeria and Pseudovibrio did not produce roseobacticides. Addition of roseobacticide-containing bacterial extracts affected the growth of the microalgae Rhodomonas salina, Thalassiosira pseudonana and Emiliania huxleyi, while...... growth of Tetraselmis suecica was unaffected. During co-cultivation, growth of E. huxleyi was initially stimulated by the roseobacticide producer DSM 17395, while the subsequent decline in algal cell numbers during senescence was enhanced. Strain 27-4 that does not produce roseobacticides had no effect...

  16. Bacterial Influence on Alkenones in Live Microalgae1

    Science.gov (United States)

    Segev, Einat; Castañeda, Isla S.; Sikes, Elisabeth L.; Vlamakis, Hera; Kolter, Roberto

    2015-01-01

    The microalga Emiliania huxleyi produces alkenone lipids which are important proxies for estimating past sea surface temperatures. Field calibrations of this proxy are robust but highly variable results are obtained in culture. Here we present results suggesting that algal-bacterial interactions may be responsible for some of this variability. Co-cultures of E. huxleyi and the bacterium Phaeobacter inhibens resulted in a 2.5-fold decrease in algal alkenone-containing lipid bodies. In addition levels of unsaturated alkenones increase in co-cultures. These changes result in an increase in the reconstructed growth temperature of up to 2°C relative to axenic algal cultures. PMID:26987094

  17. Life-cycle modification in open oceans accounts for genome variability in a cosmopolitan phytoplankton.

    Science.gov (United States)

    von Dassow, Peter; John, Uwe; Ogata, Hiroyuki; Probert, Ian; Bendif, El Mahdi; Kegel, Jessica U; Audic, Stéphane; Wincker, Patrick; Da Silva, Corinne; Claverie, Jean-Michel; Doney, Scott; Glover, David M; Flores, Daniella Mella; Herrera, Yeritza; Lescot, Magali; Garet-Delmas, Marie-José; de Vargas, Colomban

    2015-06-01

    Emiliania huxleyi is the most abundant calcifying plankton in modern oceans with substantial intraspecific genome variability and a biphasic life cycle involving sexual alternation between calcified 2N and flagellated 1N cells. We show that high genome content variability in Emiliania relates to erosion of 1N-specific genes and loss of the ability to form flagellated cells. Analysis of 185 E. huxleyi strains isolated from world oceans suggests that loss of flagella occurred independently in lineages inhabiting oligotrophic open oceans over short evolutionary timescales. This environmentally linked physiogenomic change suggests life cycling is not advantageous in very large/diluted populations experiencing low biotic pressure and low ecological variability. Gene loss did not appear to reflect pressure for genome streamlining in oligotrophic oceans as previously observed in picoplankton. Life-cycle modifications might be common in plankton and cause major functional variability to be hidden from traditional taxonomic or molecular markers.

  18. Bioaccumulation and toxicity of selenium compounds in the green alga Scenedesmus quadricauda

    Czech Academy of Sciences Publication Activity Database

    Umysová, Dáša; Vítová, Milada; Doušková, Irena; Bišová, Kateřina; Hlavová, Monika; Čížková, Mária; Machat, J.; Doucha, Jiří; Zachleder, Vilém

    2009-01-01

    Roč. 9, č. 58 (2009), s. 1-16 ISSN 1471-2229 R&D Projects: GA AV ČR IAA600200701; GA MŠk OE 221; GA MŠk OE09025 Institutional research plan: CEZ:AV0Z50200510 Keywords : CHLAMYDOMONAS-REINHARDTII * THIOREDOXIN REDUCTASE * EMILIANIA-HUXLEYI Subject RIV: EE - Microbiology, Virology Impact factor: 3.774, year: 2009

  19. Isolation of Methylophaga spp. from Marine Dimethylsulfide-Degrading Enrichment Cultures and Identification of Polypeptides Induced during Growth on Dimethylsulfide▿

    OpenAIRE

    Schäfer, Hendrik

    2007-01-01

    Dimethylsulfide (DMS)-degrading enrichment cultures were established from samples of coastal seawater, nonaxenic Emiliania huxleyi cultures, and mixed marine methyl halide-degrading enrichment cultures. Bacterial populations from a broad phylogenetic range were identified in the mixed DMS-degrading enrichment cultures by denaturing gradient gel electrophoresis (DGGE). Sequences of dominant DGGE bands were similar to those of members of the genera Methylophaga and Alcanivorax. Several closely ...

  20. Identification of the algal dimethyl sulfide-releasing enzyme: A missing link in the marine sulfur cycle

    Science.gov (United States)

    Alcolombri, Uria; Ben-Dor, Shifra; Feldmesser, Ester; Levin, Yishai; Tawfik, Dan S.; Vardi, Assaf

    2015-06-01

    Algal blooms produce large amounts of dimethyl sulfide (DMS), a volatile with a diverse signaling role in marine food webs that is emitted to the atmosphere, where it can affect cloud formation. The algal enzymes responsible for forming DMS from dimethylsulfoniopropionate (DMSP) remain unidentified despite their critical role in the global sulfur cycle. We identified and characterized Alma1, a DMSP lyase from the bloom-forming algae Emiliania huxleyi. Alma1 is a tetrameric, redox-sensitive enzyme of the aspartate racemase superfamily. Recombinant Alma1 exhibits biochemical features identical to the DMSP lyase in E. huxleyi, and DMS released by various E. huxleyi isolates correlates with their Alma1 levels. Sequence homology searches suggest that Alma1 represents a gene family present in major, globally distributed phytoplankton taxa and in other marine organisms.

  1. The Geological Legacy of Vitamin E

    Science.gov (United States)

    Cox, A. D.; Eglinton, T. I.

    2012-12-01

    genes of the pathway are known diazotrophs, suggesting a possible association with nitrogen fixation for Vitamin E in cyanobacteria. In addition, Gonyaulax polyedra, a dinoflagellate and known producer of tocopherols, and Emiliania huxleyi, a coccolithophore, are also under investigation. Combining analyses of Vitamin E in modern organisms with environmental samples will yield insights into oxidative stress and carbon cycling throughout Earth's history to the present day.

  2. The Labrador Sea during the Last Glacial Maximum: Calcite dissolution or low biogenic carbonate fluxes?

    Science.gov (United States)

    Marshall, Nicole; de Vernal, Anne; Mucci, Alfonso; Filippova, Alexandra; Kienast, Markus

    2017-04-01

    Low concentrations of biogenic carbonate characterize the sediments deposited in the Labrador Sea during the last glaciation. This may reflect poor calcite preservation and/or low biogenic carbonate productivity and fluxes. Regional bottom water ventilation was reduced during the Last Glacial Maximum (LGM), so the calcite lysocline might have been shallower than at present in the deep Labrador Sea making dissolution of calcite shells in the deep Labrador Sea possible. To address the issue, a multi-proxy approach based on micropaleontological counts (coccoliths, foraminifers, palynomorphs) and biogeochemical analyses (alkenones) was applied in the investigation of core HU2008-029-004-PC recovered in the northwestern Labrador Sea. Calcite dissolution indices based on the relative abundance benthic foraminifera shells to their organic linings as well as on fragmentation of planktonic foraminifera shells were used to evaluate changes in calcite dissolution/ preservation since the LGM. In addition, the ratio of the concentrations of coccoliths, specifically of the alkenone-producer Emiliania huxleyi, and alkenones (Emiliania huxleyi: alkenones) was explored as a potential new proxy of calcite dissolution. A sharp increase in coccoliths, foraminifers and organic linings from nearly none to substantial concentrations at 12 ka, reflect a jump to significantly greater biogenic fluxes at the glacial-interglacial transition. Furthermore, conventional dissolution indices (shells/linings of benthic foraminifera and fragmentation of planktic foraminifers) reveal that dissolution is not likely responsible for the lower glacial abundances of coccoliths and foraminifers. Only the low Emiliania huxleyi: alkenones ratios in glacial sediments could be interpreted as evidence of increased dissolution during the LGM. Given the evidence of allochthonous alkenone input into the glacial Labrador Sea, the latter observations must be treated with caution. Overall, the records indicate that

  3. Bioaccumulation of Cs-137 and Co-57 by marine phytoplankton

    International Nuclear Information System (INIS)

    Heldal, H.E.; Stupakoff, I.; Fisher, N.S.

    1999-01-01

    Under controlled laboratory conditions we have examined the bioaccumulation of Cs-137 and Co-57 in three prymnesiophytes, the coccolithophorid Emiliania huxleyi and the non-calcareous species Isochrysis galbana and Phaeocystis globosa, and two diatoms Skeletonema costatum and Thalassiosira pseudonana. We measured uptake in growing and non-growing cells, and determined concentration factors on both volume and dry weight basis. For Co-57 uptake in non-growing cells, volume concentration factors (VCF) at equilibrium ranged from 0.2 * 10 3 for Emiliana huxleyi to 4 * 10 3 for the diatom Thalassiosira pseudonana. For Cs-137 uptake in non-growing cells the VCFs were close to zero. The results suggest that, in contrast to Co, the cycling and bioaccumulation in animals of Cs in marine systems is unlikely to be affected by primary producers. (au)

  4. Bioaccumulation of 137Cs and 57Co by five marine phytoplankton species

    International Nuclear Information System (INIS)

    Heldal, H.E.; Stupakoff, I.; Fisher, N.S.

    2001-01-01

    Under controlled laboratory conditions, we have examined the bioaccumulation of 137 Cs and 57 Co in three prymnesiophytes, the coccolithophorid Emiliania huxleyi and the non-calcareous species Isochrysis galbana and Phaeocystis globosa, and two diatoms Skeletonema costatum and Thalassiosira pseudonana. We measured the uptake in growing and non-growing cells and determined concentration factors on both volume and dry weight bases. For uptake of 57 Co in non-growing cells, volume concentration factors (VCF) at equilibrium ranged from 0.2x10 3 for E. huxleyi to 4x10 3 for T. pseudonana. For uptake of 137 Cs in non-growing cells, the VCFs were low for all species and the uptake pattern seemed unsystematic. The results suggest that, in contrast to Co, the cycling and bioaccumulation of Cs in marine animals are unlikely to be affected by Cs accumulation in primary producers

  5. The Jekyll-and-Hyde chemistry of Phaeobacter gallaeciensis

    Science.gov (United States)

    Seyedsayamdost, Mohammad R.; Case, Rebecca J.; Kolter, Roberto; Clardy, Jon

    2012-01-01

    Emiliania huxleyi, an environmentally important marine microalga, has a bloom- and-bust lifestyle in which massive algal blooms appear and fade. Phaeobacter gallaeciensis belongs to the roseobacter clade of α-Proteobacteria, whose populations wax and wane with that of E. huxleyi. Roseobacter are thought to promote algal growth by biosynthesizing and secreting antibiotics and growth stimulants (auxins). Here we show that P. gallaeciensis switches its secreted small molecule metabolism to the production of potent and selective algaecides, the roseobacticides, in response to p-coumaric acid, an algal lignin breakdown product that is symptomatic of aging algae. This switch converts P. gallaeciensis into an opportunistic pathogen of its algal host. PMID:21430694

  6. Bacterial influence on alkenones in live microalgae.

    Science.gov (United States)

    Segev, Einat; Castañeda, Isla S; Sikes, Elisabeth L; Vlamakis, Hera; Kolter, Roberto

    2016-02-01

    The microalga Emiliania huxleyi produces alkenone lipids that are important proxies for estimating past sea surface temperatures. Field calibrations of this proxy are robust but highly variable results are obtained in culture. Here, we present results suggesting that algal-bacterial interactions may be responsible for some of this variability. Co-cultures of E. huxleyi and the bacterium Phaeobacter inhibens resulted in a 2.5-fold decrease in algal alkenone-containing lipid bodies. In addition levels of unsaturated alkenones increase in co-cultures. These changes result in an increase in the reconstructed growth temperature of up to 2°C relative to axenic algal cultures. © 2015 Phycological Society of America.

  7. Infection of phytoplankton by aerosolized marine viruses

    Science.gov (United States)

    Sharoni, Shlomit; Trainic, Miri; Schatz, Daniella; Lehahn, Yoav; Flores, Michel J.; Bidle, Kay D.; Ben-Dor, Shifra; Rudich, Yinon; Vardi, Assaf

    2015-01-01

    Marine viruses constitute a major ecological and evolutionary driving force in the marine ecosystems. However, their dispersal mechanisms remain underexplored. Here we follow the dynamics of Emiliania huxleyi viruses (EhV) that infect the ubiquitous, bloom-forming phytoplankton E. huxleyi and show that EhV are emitted to the atmosphere as primary marine aerosols. Using a laboratory-based setup, we showed that the dynamic of EhV aerial emission is strongly coupled to the host–virus dynamic in the culture media. In addition, we recovered EhV DNA from atmospheric samples collected over an E. huxleyi bloom in the North Atlantic, providing evidence for aerosolization of marine viruses in their natural environment. Decay rate analysis in the laboratory revealed that aerosolized viruses can remain infective under meteorological conditions prevailing during E. huxleyi blooms in the ocean, allowing potential dispersal and infectivity over hundreds of kilometers. Based on the combined laboratory and in situ findings, we propose that atmospheric transport of EhV is an effective transmission mechanism for spreading viral infection over large areas in the ocean. This transmission mechanism may also have an important ecological impact on the large-scale host–virus “arms race” during bloom succession and consequently the turnover of carbon in the ocean. PMID:25964340

  8. Coccolithoviruses: A Review of Cross-Kingdom Genomic Thievery and Metabolic Thuggery

    Directory of Open Access Journals (Sweden)

    Jozef I. Nissimov

    2017-03-01

    Full Text Available Coccolithoviruses (Phycodnaviridae infect and lyse the most ubiquitous and successful coccolithophorid in modern oceans, Emiliania huxleyi. So far, the genomes of 13 of these giant lytic viruses (i.e., Emiliania huxleyi viruses—EhVs have been sequenced, assembled, and annotated. Here, we performed an in-depth comparison of their genomes to try and contextualize the ecological and evolutionary traits of these viruses. The genomes of these EhVs have from 444 to 548 coding sequences (CDSs. Presence/absence analysis of CDSs identified putative genes with particular ecological significance, namely sialidase, phosphate permease, and sphingolipid biosynthesis. The viruses clustered into distinct clades, based on their DNA polymerase gene as well as full genome comparisons. We discuss the use of such clustering and suggest that a gene-by-gene investigation approach may be more useful when the goal is to reveal differences related to functionally important genes. A multi domain “Best BLAST hit” analysis revealed that 84% of the EhV genes have closer similarities to the domain Eukarya. However, 16% of the EhV CDSs were very similar to bacterial genes, contributing to the idea that a significant portion of the gene flow in the planktonic world inter-crosses the domains of life.

  9. Effect of metals on the lytic cycle of the coccolithovirus, EhV86.

    Directory of Open Access Journals (Sweden)

    Martha eGledhill

    2012-04-01

    Full Text Available In this study we show that metals, and in particular copper (Cu, can disrupt the lytic cycle in the Emiliania huxleyi - EhV86 host-virus system. Numbers of virus particles produced per E. huxleyi cell and E. huxleyi lysis rates were reduced by Cu at total metal concentrations over 500 nM in the presence of EDTA (ethylenediaminetetraacetic acid, and 250 nM in the absence of EDTA in acute short term exposure experiments. Zinc (Zn, cadmium (Cd and cobalt (Co were not observed to affect the lysis rate of EhV86 in these experiments. The cellular glutathione (GSH content increased in virus infected cells, but not as a result of metal exposure. In contrast, the cellular content of phytochelatins (PCs increased only in response to metal exposure. The increase in gluthatione content is consistent with increases in the production of reactive oxygen species (ROS on viral infection, while increases in PC content are likely linked to metal homeostasis and indicate that metal toxicity to the host was not affected by viral infection. We propose that Cu prevents lytic production of EhV86 by interfering with virus DNA (deoxyribonucleic acid synthesis through a transcriptional block, which ultimately suppresses the formation of ROS, a biochemical response required for successful virus infection.

  10. Horizontal gene transfer of an entire metabolic pathway between a eukaryotic alga and its DNA virus

    Science.gov (United States)

    Monier, Adam; Pagarete, António; de Vargas, Colomban; Allen, Michael J.; Read, Betsy; Claverie, Jean-Michel; Ogata, Hiroyuki

    2009-01-01

    Interactions between viruses and phytoplankton, the main primary producers in the oceans, affect global biogeochemical cycles and climate. Recent studies are increasingly revealing possible cases of gene transfers between cyanobacteria and phages, which might have played significant roles in the evolution of cyanobacteria/phage systems. However, little has been documented about the occurrence of horizontal gene transfer in eukaryotic phytoplankton/virus systems. Here we report phylogenetic evidence for the transfer of seven genes involved in the sphingolipid biosynthesis pathway between the cosmopolitan eukaryotic microalga Emiliania huxleyi and its large DNA virus EhV. PCR assays indicate that these genes are prevalent in E. huxleyi and EhV strains isolated from different geographic locations. Patterns of protein and gene sequence conservation support that these genes are functional in both E. huxleyi and EhV. This is the first clear case of horizontal gene transfer of multiple functionally linked enzymes in a eukaryotic phytoplankton–virus system. We examine arguments for the possible direction of the gene transfer. The virus-to-host direction suggests the existence of ancient viruses that controlled the complex metabolic pathway in order to infect primitive eukaryotic cells. In contrast, the host-to-virus direction suggests that the serial acquisition of genes involved in the same metabolic pathway might have been a strategy for the ancestor of EhVs to stay ahead of their closest relatives in the great evolutionary race for survival. PMID:19451591

  11. Anaerobic Coculture of Microalgae with Thermosipho globiformans and Methanocaldococcus jannaschii at 68°C Enhances Generation of n-Alkane-Rich Biofuels after Pyrolysis

    Science.gov (United States)

    Matsuyama, Shigeru; Igarashi, Kensuke; Utsumi, Motoo; Shiraiwa, Yoshihiro; Kuwabara, Tomohiko

    2013-01-01

    We tested different alga-bacterium-archaeon consortia to investigate the production of oil-like mixtures, expecting that n-alkane-rich biofuels might be synthesized after pyrolysis. Thermosipho globiformans and Methanocaldococcus jannaschii were cocultured at 68°C with microalgae for 9 days under two anaerobic conditions, followed by pyrolysis at 300°C for 4 days. Arthrospira platensis (Cyanobacteria), Dunaliella tertiolecta (Chlorophyta), Emiliania huxleyi (Haptophyta), and Euglena gracilis (Euglenophyta) served as microalgal raw materials. D. tertiolecta, E. huxleyi, and E. gracilis cocultured with the bacterium and archaeon inhibited their growth and CH4 production. E. huxleyi had the strongest inhibitory effect. Biofuel generation was enhanced by reducing impurities containing alkanenitriles during pyrolysis. The composition and amounts of n-alkanes produced by pyrolysis were closely related to the lipid contents and composition of the microalgae. Pyrolysis of A. platensis and D. tertiolecta containing mainly phospholipids and glycolipids generated short-carbon-chain n-alkanes (n-tridecane to n-nonadecane) and considerable amounts of isoprenoids. E. gracilis also produced mainly short n-alkanes. In contrast, E. huxleyi containing long-chain (31 and 33 carbon atoms) alkenes and very long-chain (37 to 39 carbon atoms) alkenones, in addition to phospholipids and glycolipids, generated a high yield of n-alkanes of various lengths (n-tridecane to n-pentatriacontane). The gas chromatography-mass spectrometry (GC-MS) profiles of these n-alkanes were similar to those of native petroleum crude oils despite containing a considerable amount of n-hentriacontane. The ratio of phytane to n-octadecane was also similar to that of native crude oils. PMID:23183975

  12. Growth phase dependent hydrogen isotopic fractionation in alkenone-producing haptophytes

    Directory of Open Access Journals (Sweden)

    M. D. Wolhowe

    2009-08-01

    Full Text Available Recent works have investigated use of the hydrogen isotopic composition of C37 alkenones (δDK37s, lipid biomarkers of certain haptophyte microalgae, as an independent paleosalinity proxy. We discuss herein the factors impeding the success of such an application and identify the potential alternative use of δDK37s measurements as a proxy for non-thermal, physiological stress impacts on the U37K' paleotemperature index. Batch-culture experiments with the haptophyte Emiliania huxleyi (CCMP 1742 were conducted to determine the magnitude and variability of the isotopic contrasts between individual C37 alkenones. Further experiments were conducted with Emiliania huxleyi (CCMP 1742 andGephyrocapsa oceanica (PZ3-1 to determine whether, and to what extent, δDK37s varies between the physiological extremes of nutrient-replete exponential growth and nutrient-depleted senescence. Emiliania huxleyi was observed to exhibit an isotopic contrast between di- and tri-unsaturated C37 alkenones (αK37:3-K37:2≈0.97 that is nearly identical to that reported recently by others for environmental samples. Furthermore, this contrast appears to be constant with growth stage. The consistency of the offset across different growth stages suggests that a single, well-defined value for αK37:3-K37:2 may exist and that its use in an isotope mass-balance will allow accurate determination of δD values for individual alkenones without having to rely on time- and labor-intensive chemical separations. The isotopic fractionation between growth medium and C37 alkenones was observed to increase dramatically upon the onset of nutrient-depletion-induced senescence, suggesting that δDK37s may serve as an objective tool for recognizing and potentially correcting, at least semi-quantitatively, for the effects

  13. Nannofossils in upper quaternary bottom sediments of back-arc basins in the southwestern Pacific

    Science.gov (United States)

    Dmitrenko, O. B.

    2015-05-01

    The analysis of calcareous nannoplankton assemblages in bottom sediments sampled during Cruise 21 of the R/V Akademik Mstislav Keldysh in three areas located in back-arc basins of the southwestern Pacific (western Woodlark in the Solomon Sea, Manus in the Bismarck Sea, Central Lau) reveal that they belong to the Emiliania huxleyi Acme Zone, the most detailed one in the Gartner's scale of 1977. The content of coccoliths and their taxonomic composition indicate warm subtropical-tropical conditions. Long cores demonstrate a decrease in species diversity reflecting the transition from the cold late Pleistocene to the Holocene. The changes in species diversity and presence/absence of thermophilic representatives indicate transformation of depositional environments with unstable conditions in the water column and bottom layer, seismic activity, and widely developed processes of sediment redistribution and reworking.

  14. Isolation and Characterization of a Double Stranded DNA Megavirus Infecting the Toxin-Producing Haptophyte Prymnesium parvum

    Directory of Open Access Journals (Sweden)

    Ben A. Wagstaff

    2017-03-01

    Full Text Available Prymnesium parvum is a toxin-producing haptophyte that causes harmful algal blooms globally, leading to large-scale fish kills that have severe ecological and economic implications. For the model haptophyte, Emiliania huxleyi, it has been shown that large dsDNA viruses play an important role in regulating blooms and therefore biogeochemical cycling, but much less work has been done looking at viruses that infect P. parvum, or the role that these viruses may play in regulating harmful algal blooms. In this study, we report the isolation and characterization of a lytic nucleo-cytoplasmic large DNA virus (NCLDV collected from the site of a harmful P. parvum bloom. In subsequent experiments, this virus was shown to infect cultures of Prymnesium sp. and showed phylogenetic similarity to the extended Megaviridae family of algal viruses.

  15. Photochemical Production and Behavior of Hydroperoxyacids in Heterotrophic Bacteria Attached to Senescent Phytoplanktonic Cells

    Directory of Open Access Journals (Sweden)

    Frédéric Vaultier

    2013-06-01

    Full Text Available The photooxidation of cellular monounsaturated fatty acids was investigated in senescent phytoplanktonic cells (Emiliania huxleyi and in their attached bacteria under laboratory controlled conditions. Our results indicated that UV-visible irradiation of phytodetritus induced the photooxidation of oleic (produced by phytoplankton and bacteria and cis-vaccenic (specifically produced by bacteria acids. These experiments confirmed the involvement of a substantial singlet oxygen transfer from senescent phytoplanktonic cells to attached bacteria, and revealed a significant correlation between the concentration of chlorophyll, a photosensitizer, in the phytodetritus and the photodegradation state of bacteria. Hydroperoxyacids (fatty acid photoproducts appeared to be quickly degraded to ketoacids and hydroxyacids in bacteria and in phytoplanktonic cells. This degradation involves homolytic cleavage (most likely induced by UV and/or transition metal ions and peroxygenase activity (yielding epoxy acids.

  16. Influence of Late Quaternary depositional environments on the structure of nannofossil assemblages in the Titanic area (northwestern Atlantic)

    Science.gov (United States)

    Dmitrenko, O. B.

    2012-02-01

    The nannofosssil assemblages have been analyzed in five cores taken from the Titanic area of the northwestern Atlantic (˜41°-42° N, ˜47°-50° W, water depths >3500 m) during cruises 41 and 43 of the R/V Akademik Mstislav Keldysh in 1998 and 2000. They correlate the host sediments with the upper Pleistocene-Holocene Emiliania huxleyi zone. The changes in the structure of the nannofossil assemblages and the lithological characteristics such as the content of biogenic CaCO3, the abundance of ice-rafted debris, and the grain-size composition were used for the high-resolution stratigraphy of sections with defining marine isotopic stages 1-3 of the last 24 kyr. A characteristic feature of the nannofossil assemblages from this area is their enrichment with the cold-resistant species Coccolthus pelagicus during the warm climatic stages and the lack of allochthonous coccolitophorid remains.

  17. Examining the impact of grazing on iron remineralization: effect of prey type on digestive vacuole pH

    Science.gov (United States)

    Pritchard, K. R.; Nuester, J.; Twining, B.

    2012-12-01

    Most of the iron available to phytoplankton in high-nutrient, low-chlorophyll areas is regenerated by zooplankton grazers. The extent to which the bioavailability of this regenerated iron is a function of prey-type and the chemical conditions within digestive systems of zooplankton is unknown. The chemical composition of the prey, including silica frustules of diatoms and calcium carbonate coccoliths of cocolithophores, might buffer the acidity within a digestive vacuole and thereby influencing the resulting speciation and bioavailability of regenerated iron. In order to test the effect of prey-type on the chemical condition in the digestive vacuole of the heterotrophic dinoflagellate Oxyrrhis marina, we used the ratiometric fluorescent dye Lysosensor Yellow/Blue DND-160 in conjunction with confocal microscopy to measure and compare digestive vacuole acidity after feeding O. marina with either the diatom Thalassiosira pseudonana, the coccolithophore Emiliana huxleyi, or the chlorophyte Dunaliella tertiolecta. After feeding and loading O. marina with the Lysosensor dye, we recorded the total fluorescence (f) of the wavelength regions λ1=500-555 nm and λ2=410-490 nm using an excitation wavelength of 405 nm, and calculated the Lysosensor fluorescence ratio r=f(λ1)/f(λ2). External calibration curves show that this ratio (r) is inversely related to pH. In addition, we also measured the emission of chlorophyll fluorescence above 640 nm in order to identify prey within the grazers and study the timing chlorophyll degradation in conjunction with vacuole pH. After the initial addition of either prey, O. marina consumed 10 times and 2 times more D. tertiolecta cells than E. huxleyi and T. pseudonana cells, respectively. The clearance of the digestive vacuole measured as the disappearance of chlorophyll fluorescence is ca. twice as long for O. marina feeding on D. tertiolecta than on E. huxleyi or T. pseudonana. Initial r was inversely proportional to prey preference

  18. Synchronized Regulation of Different Zwitterionic Metabolites in the Osmoadaption of Phytoplankton

    Directory of Open Access Journals (Sweden)

    Georg Pohnert

    2013-06-01

    Full Text Available The ability to adapt to different seawater salinities is essential for cosmopolitan marine phytoplankton living in very diverse habitats. In this study, we examined the role of small zwitterionic metabolites in the osmoadaption of two common microalgae species Emiliania huxleyi and Prorocentrum minimum. By cultivation of the algae under salinities between 16‰ and 38‰ and subsequent analysis of dimethylsulfoniopropionate (DMSP, glycine betaine (GBT, gonyol, homarine, trigonelline, dimethylsulfonioacetate, trimethylammonium propionate, and trimethylammonium butyrate using HPLC-MS, we could reveal two fundamentally different osmoadaption mechanisms. While E. huxleyi responded with cell size reduction and a nearly constant ratio between the major metabolites DMSP, GBT and homarine to increasing salinity, osmolyte composition of P. minimum changed dramatically. In this alga DMSP concentration remained nearly constant at 18.6 mM between 20‰ and 32‰ but the amount of GBT and dimethylsulfonioacetate increased from 4% to 30% of total investigated osmolytes. Direct quantification of zwitterionic metabolites via LC-MS is a powerful tool to unravel the complex osmoadaption and regulation mechanisms of marine phytoplankton.

  19. Selenium Utilization Strategy by Microalgae

    Directory of Open Access Journals (Sweden)

    Hiroya Araie

    2009-11-01

    Full Text Available The diversity of selenoproteins raises the question of why so many life forms require selenium. Selenoproteins are found in bacteria, archaea, and many eukaryotes. In photosynthetic microorganisms, the essential requirement for selenium has been reported in 33 species belonging to six phyla, although its biochemical significance is still unclear. According to genome databases, 20 species are defined as selenoprotein-producing organisms, including five photosynthetic organisms. In a marine coccolithophorid, Emiliania huxleyi (Haptophyta, we recently found unique characteristics of selenium utilization and novel selenoproteins using 75Se-tracer experiments. In E. huxleyi, selenite, not selenate, is the main substrate used and its uptake is driven by an ATP-dependent highaffinity, active transport system. Selenite is immediately metabolized to low-molecular mass compounds and partly converted to at least six selenoproteins, named EhSEP1–6. The most (EhSEP2 and second-most abundant selenoproteins (EhSEP1 are disulfide isomerase (PDI homologous protein and thioredoxin reductase (TR 1, respectively. Involvement of selenium in PDI is unique in this organism, while TR1 is also found in other organisms. In this review, we summarize physiological, biochemical, and molecular aspects of selenium utilization by microalgae and discuss their strategy of selenium utilization.

  20. Effects of phosphorus limitation and ocean acidification on coccolithophores in the Mediterranean Sea

    OpenAIRE

    Oviedo Sabogal, Angela María

    2015-01-01

    Este trabajo se desarrolló en el marco del proyecto Europeo Mediterranean Sea Acidification in a changing climate (MedSeA) (http://medsea-project.eu) con el fin de estudiar los efectos de la limitación por fósforo (P) y el incremento en la presión parcial de dióxido de carbono (pCO2) sobre diferentes aspectos de la biología y ecología de los cocolitóforos. Esta tesis consta de una introducción al tema de estudio donde se presenta el problema de la acidificación oceánica y la limitación por nu...

  1. Living coccolithophores during the northeast monsoon from the Equatorial Indian Ocean: Implications on hydrography

    Digital Repository Service at National Institute of Oceanography (India)

    Guptha, M.V.S.; Mergulhao, L.P.; Murty, V.S.N.; Shenoy, D.M.

    suggested a prevalence of oligotrophic conditions or lack of supply of nutrients into the upper mixed layer (approx. 50 m thick) during the northeast monsoon. However, the relatively higher abundance of Florisphaera profunda at 4 degrees S indicated...

  2. Coccolithophore paleoproductivity and ecology response to deglacial and Holocene changes in the Azores Current System

    DEFF Research Database (Denmark)

    Schwab, C.; Kinkel, Hanno; Weinelt, M.

    2012-01-01

    In order to test the sensitivity of marine primary productivity in the midlatitude open ocean North Atlantic to changes in the Atlantic Meridional Overturning Circulation (AMOC), we investigated two spliced sediment cores from a site south of the Azores Islands at the northern rim of the North At...

  3. Effects of increased atmospheric CO2 on small and intermediate sized osmotrophs during a nutrient induced phytoplankton bloom

    Directory of Open Access Journals (Sweden)

    A. Larsen

    2008-05-01

    Full Text Available We report the transient population dynamic response of the osmotrophic community initiated by a nutrient pulse in mesocosms exposed to different pCO2 levels. Differences in phytoplankton and heterotrophic bacteria abundances associated with the CO2 treatment are also described. Coastal seawater was enclosed in floating mesocosms (27 m3 and nutrients were supplied initially in order to stimulate growth of microbial organisms, including the coccolitophorid Emiliania huxleyi. The mesocosms were modified to achieve 350 μatm (1×CO2, 700 μatm (2×CO2 and 1050 μatm (3×CO2 CO2 pressure. The temporal dynamics was related to nutrient conditions in the enclosures. Numerically small osmotrophs (picoeukaryotes and Synechoccocus sp. dominated initially and towards the end of the experiment, whereas intermediate sized osmotrophs bloomed as the initial bloom of small sized osmotrophs ceased. Maximum concentrations of E. huxleyi were approximately 4.6×103 cells ml−1 whereas other intermediate sized osmotrophs reached approximately twice as high concentrations. The osmotrophic succession pattern did not change, and neither were we able to detect differences with regard to presence or absence of specific osmotrophic taxa as a consequence of altered pCO2. Towards the end of the experiment we did, however, record significantly higher picoeukaryotic- and lower Synechococcus-abundances in the higher CO2 treatments. Slightly increased cell concentrations of E. huxleyi and other nanoeukaryotes were also recorded at elevated pCO2 on certain days.

  4. Seasonal calcareous nannoplankton and other biogenic particle fluxes for 1990-2009: twenty-year long records from the central subarctic Pacific Ocean and the Bering Sea

    Science.gov (United States)

    Takahashi, Kozo; Tsutsui, Hideto

    2017-04-01

    Time-series sediment traps were deployed for nearly 20 years (1990-2009) at two long-term locations: Station SA (49°N, 174°W, trap depth 4,800 m, water depth 5,400 m) in the central subarctic Pacific, and Station AB (53.5°N, 177°W, trap depth 3,200 m, water depth 3,800 m) in the southern Bering Sea. Among many biogenic particles, calcareous nannoplankton represented nearly half or more of the entire calcium carbonate fluxes of the regions. Dominant taxa include Coccolithus pelagicus and Emiliania huxleyi. The flux maxima of the former taxon occurred twice a year during June and October-November, whereas that of the latter taxon only occurred primarily once a year in November at both stations, indicating environmental preferences of the taxa. Among many environmental conditions, the fluxes of Emiliania huxleyi showed strong correlations with both water temperatures above 45 m depth and air temperatures (these parameters taken with one-month lag [earlier values] considering sinking time of ca. a month to the respective trap depths). Coccolithus pelagicus, on the other hand, showed lower values in the correlation with temperatures (Tsutsui et al., 2016), indicating that this taxon is somewhat more dependent on other factors such as nutrients compared to those of E. huxleyi. The timings of the seasonal flux maxima of calcareous nannoplankton are quite different from and later than those of other taxonomic groups such as diatoms and silicoflagellates. The primary seasonal flux maxima of diatoms and silicoflagellates, for example, occurred in May, a month earlier than the June maximum of C. pelagicus, and secondary seasonal flux maxima occurred in August, 2-3 months earlier than those of calcareous nannoplankton at both stations, based on 8 year flux records for diatoms (Onodera and Takahashi, 2009) and 4 year records for silicoflagellates (Onodera and Takahashi, 2012). By examining seasonal changes of nitrate and phosphate concentrations above 50 m depth from ERDDAP

  5. Selenium Uptake and Volatilization by Marine Algae

    Science.gov (United States)

    Luxem, Katja E.; Vriens, Bas; Wagner, Bettina; Behra, Renata; Winkel, Lenny H. E.

    2015-04-01

    Selenium (Se) is an essential trace nutrient for humans. An estimated one half to one billion people worldwide suffer from Se deficiency, which is due to low concentrations and bioavailability of Se in soils where crops are grown. It has been hypothesized that more than half of the atmospheric Se deposition to soils is derived from the marine system, where microorganisms methylate and volatilize Se. Based on model results from the late 1980s, the atmospheric flux of these biogenic volatile Se compounds is around 9 Gt/year, with two thirds coming from the marine biosphere. Algae, fungi, and bacteria are known to methylate Se. Although algal Se uptake, metabolism, and methylation influence the speciation and bioavailability of Se in the oceans, these processes have not been quantified under environmentally relevant conditions and are likely to differ among organisms. Therefore, we are investigating the uptake and methylation of the two main inorganic Se species (selenate and selenite) by three globally relevant microalgae: Phaeocystis globosa, the coccolithophorid Emiliania huxleyi, and the diatom Thalassiosira oceanica. Selenium uptake and methylation were quantified in a batch experiment, where parallel gas-tight microcosms in a climate chamber were coupled to a gas-trapping system. For E. huxleyi, selenite uptake was strongly dependent on aqueous phosphate concentrations, which agrees with prior evidence that selenite uptake by phosphate transporters is a significant Se source for marine algae. Selenate uptake was much lower than selenite uptake. The most important volatile Se compounds produced were dimethyl selenide, dimethyl diselenide, and dimethyl selenyl sulfide. Production rates of volatile Se species were larger with increasing intracellular Se concentration and in the decline phase of the alga. Similar experiments are being carried out with P. globosa and T. oceanica. Our results indicate that marine algae are important for the global cycling of Se

  6. Calcareous Nannofossils and Variation of the Kuroshio Current in the Okinawa Tro ugh During the Last 14000 Years

    Directory of Open Access Journals (Sweden)

    Xin

    2005-01-01

    Full Text Available A quantitative census study on calcareous nannofossils from sediments of Site 1202 recovered by ODP Leg 195 and surface sediments from the East China Sea was carried out to obtain a high-resolution nannofossil record of the change of the Kuroshio Current during the late Quaternary. Two nannofossil ratio indices were designed and employed in this study: (1 ratio of Florisphaera profunda against F. profunda, Emiliania huxleyi and Gephyrocapsa oceanica (F-EG ratio as a nannofossil proxy of the Kuroshio Current, (2 ratio of G. oceanica against F. profunda and E. huxleyi and G. oceanica (G-FE ratio as a proxy of near-coast environment. Results from the 14 surface nannofossil samples demonstrate that the F-EG ratio is > 15% in the assemblage lying directly under the main route of the Kuroshio Current, whereas it is very low ( 30% were seen from all samples on the East China Sea continental shelf or from near-coast cores. Down hole nannofossil record from the top 60 mbsf sediment interval at ODP Hole 1202B reflects the change of the Kuroshio Current in the last glacial and postglacial period since 14 ka. Extreme low F-EG ratio together with very high G-FE ratio at Hole 1202B during the time of the latest Pleistocene and the earliest Holocene suggest the absence of the Kuroshio Current in the area studied. The event of intrusion of the Kuroshio Current was clearly recorded by a dramatically increase of F-EG ratio and notably a reduction in the G-FE ratio around 9 ka. Furthermore, based on the variation of the F-EG ratio and _ of planktonic foraminifera Neogloboquadrina dutertrei, variation of the Kuroshio Current in the Holocene shows three long-term cycles (with a periodicity of ~3000 yr.

  7. Ballast minerals and the sinking carbon flux in the ocean: carbon-specific respiration rates and sinking velocity of marine snow aggregates

    Directory of Open Access Journals (Sweden)

    M. H. Iversen

    2010-09-01

    Full Text Available Recent observations have shown that fluxes of ballast minerals (calcium carbonate, opal, and lithogenic material and organic carbon fluxes are closely correlated in the bathypelagic zones of the ocean. Hence it has been hypothesized that incorporation of biogenic minerals within marine aggregates could either protect the organic matter from decomposition and/or increase the sinking velocity via ballasting of the aggregates. Here we present the first combined data on size, sinking velocity, carbon-specific respiration rate, and composition measured directly in three aggregate types; Emiliania huxleyi aggregates (carbonate ballasted, Skeletonema costatum aggregates (opal ballasted, and aggregates made from a mix of both E. huxleyi and S. costatum (carbonate and opal ballasted. Overall average carbon-specific respiration rate was ~0.13 d−1 and did not vary with aggregate type and size. Ballasting from carbonate resulted in 2- to 2.5-fold higher sinking velocities than those of aggregates ballasted by opal. We compiled literature data on carbon-specific respiration rate and sinking velocity measured in aggregates of different composition and sources. Compiled carbon-specific respiration rates (including this study vary between 0.08 d−1 and 0.20 d−1. Sinking velocity increases with increasing aggregate size within homogeneous sources of aggregates. When compared across different particle and aggregate sources, however, sinking velocity appeared to be independent of particle or aggregate size. The carbon-specific respiration rate per meter settled varied between 0.0002 m−1 and 0.0030 m−1, and decreased with increasing aggregate size. It was lower for calcite ballasted aggregates as compared to that of similar sized opal ballasted aggregates.

  8. Seasonal variation of the flux of living coccolithophore communities in the Bay of Bengal and their implication on hydrography

    Digital Repository Service at National Institute of Oceanography (India)

    Mergulhao, L

    ). The systematics of coccoliths in relation to the palaeontological record. In: B.M. Funnell and W.R. Riedel (eds.), The Micropalaeontology of the Oceans. Cambridge Univ. Press, Cambridge, pp. 611-624. Bloesch, J. and N.M. Burns (1980). A critical review... (to 25°S, 100°E). Inst. of Oceanogr., Wormely, England, U.K. IOS Tech. Rep., 187, 36 charts, 8 pp. De Souza, S.N., S.W.A Naqvi and C.V.G Reddy (1981). Distribution of nutrients in the western Bay of Bengal. Indian J. Mar. Sci., 10, 327...

  9. Seasonality and variability of coccolithophore fluxes in response to diverse oceanographic regimes in the Bay of Bengal: Sediment trap results

    Digital Repository Service at National Institute of Oceanography (India)

    Mergulhao, L.P.; Guptha, M.V.S.; Unger, D.; Murty, V.S.N.

    carbonate and diatom opal fluxes continued to increase. Tanaka and Kawahata (2001) reported that the calculated coccolith- CaCO3 fluxes ranged between 6.8 and 49.6 mg m-2day-1 and contributed 23.3% of total CaCO3 flux in the west Caroline Basin...

  10. Picarola margalefii, gen. et sp. nov., a new planktonic coccolithophore from NW Mediterranean waters

    OpenAIRE

    Lluïsa Cros; Marta Estrada

    2004-01-01

    [ES] Un cocolitóforo atribuido a un género nuevo, Picarola gen. nov., y descrito como una especie nueva, Picarola margalefii, sp. nov., ha sido hallado en el Mediterráneo noroccidental. La descripción de la nueva especie se basa en observaciones realizadas con Microscopía Electrónica de Barrido. Los cocolitos de Picarola margalefii sp. nov. son murolitos que tienen un margen alto y estrecho y un área central que presenta una cruz con un largo proceso central de cuatro caras. Se confirmó su na...

  11. Diversity of pico- to mesoplankton along the 2000 km salinity gradient of the Baltic Sea

    Directory of Open Access Journals (Sweden)

    Yue O.O. Hu

    2016-05-01

    Full Text Available Microbial plankton form the productive base of both marine and freshwater ecosystems and are key drivers of global biogeochemical cycles of carbon and nutrients. Plankton diversity is immense with representations from all major phyla within the three domains of life. So far, plankton monitoring has mainly been based on microscopic identification, which has limited sensitivity and reproducibility, not least because of the numerical majority of plankton being unidentifiable under the light microscope. High-throughput sequencing of taxonomic marker genes offers a means to identify taxa inaccessible by traditional methods; thus, recent studies have unveiled an extensive previously unknown diversity of plankton. Here, we conducted ultra-deep Illumina sequencing (average 105 sequences/sample of rRNA gene amplicons of surface water eukaryotic and bacterial plankton communities sampled in summer along a 2000 km transect following the salinity gradient of the Baltic Sea. Community composition was strongly correlated with salinity for both bacterial and eukaryotic plankton assemblages, highlighting the importance of salinity for structuring the biodiversity within this ecosystem. In contrast, no clear trends in alpha-diversity for bacterial or eukaryotic communities could be detected along the transect. The distribution of major planktonic taxa followed expected patterns as observed in monitoring programs, but groups novel to the Baltic Sea were also identified, such as relatives to the coccolithophore Emiliana huxleyi detected in the northern Baltic Sea. This study provides the first ultra-deep sequencing-based survey on eukaryotic and bacterial plankton biogeography in the Baltic Sea.

  12. Phytoplankton on the western coasts of Baja California in two different seasons in 1998

    Directory of Open Access Journals (Sweden)

    David U. Hernández-Becerril

    2007-12-01

    Full Text Available Phytoplankton was studied in two different seasons of 1998 (March-April and December, during two cruises along the western coasts of Baja California, in three zones. Two different protocols for obtaining and studying phytoplankton were followed. In the March-April season, phytoplankton had relatively low species richness and was dominated in cell density (up to 93% by coccolithophorids (mainly Emiliania huxleyi, together with nanoplanktonic centric and pennate diatoms, with abundances ranging from 5.4 103 to 1.2 105 cells L-1. In December, phytoplankton had higher species richness and was represented by larger, chain-forming diatom species, such as Pseudonitzschia delicatissima and P. pungens, which were widespread and numerically significant. There was a relative scarcity of coccolithophorids and thecate dinoflagellates, and densities were between 7 102 and 1.4 106 cells L-1. Hydrographic and oceanographic conditions in March-April were influenced by the occurrence of El Niño and the phytoplankton structure was found to be modified accordingly, with nanoplanktonic coccolithophorids and diatoms being significant contributors to the total abundance. In contrast, post-upwelling conditions might have favoured relatively high densities of Pseudonitzschia and other diatoms in December, 1998. Coccolithophorids have not been previously regarded as important contributors to the phytoplankton abundances in Baja California.

  13. Occurrence of Coccolithophorids in the Northeastern and Central South China Sea

    Directory of Open Access Journals (Sweden)

    Tien-Nan Yang

    2003-03-01

    Full Text Available Coccolithophorids in the northeastern and central South China Sea (SCS were surveyed in March and October 1996. The cell density of coccolithophorids ranged from 25 x 103 cells L-1 to 31 x 103 cells L-1 in sea-surface water (0–25 m in depth, and from 12 x 103 cells L-1 to 62 x 103 cells L-1 in subsurface water (150 m in depth. The lowest cell number was recorded in the subsurface (150 m in depth in the central gyral area, while the highest one was at the same depth in the northeastern realm. A total of thirty-one species were identified. The species richness in the northeastern SCS is higher than in the central area. Emiliania huxleyi (Lohmann Hay et Mohler, Gephyrocapsa oceanica Kamptner, Umbellosphaera Paasche spp. And Syracosphaera Lohmann spp. Dominated the surface assemblages, whereas Florisphaera profunda Okada et Honjo, Gladiolithus flabellatus (Halldal et Markali Jordan et Chamberlain predominated in the subsurface layer. In contrast, Palusphaera vandeli Lecal emend. R. E. Norris presented in both surface and subsurface assemblages.

  14. Microplankton of the Barents Sea: current composition and structure on the eve of the winter

    Directory of Open Access Journals (Sweden)

    Makarevich P. R.

    2017-06-01

    Full Text Available The results of microplankton (Protista investigations in the Barents Sea (standard "Kola Meridian Transect", ~70–78° N, 33° 30′ E in November / December have been presented. Samples for the determination of the taxonomical composition and abundance have been fixed with buffered formalin and examined with light microscopy using Nageotte counting chambers. A list of species recorded in the Barents Sea on transect, abundance and vertical distribution of microplankton has been given: a the seasonal composition of species (Ceratium fusus, Dicroerisma psilonereiella, Dinophysis rotundata, Lessardia elongata aff., Oxytoxum caudatum, Pronoctiluca pelagica, Protoperidinium brevipes, Prorocentrum balticum (Dinophyta, Corethron criophilum (Bacillariophyta, Coccolithus pelagicus (Haptophyta, Halosphaera viridis (Prasinophyta; b mean values of the total biomass of microplankton and its distribution in the water column (1.14 mkg/l in the layer of 50–0 m, 0.97 mkg/l – 100–50 m, 0.75 mkg/l – 200–100 m, 0.53 mkg/l – 300–200 m. Such parameter as dominant species in the structure of the total number is less constant (the ordinary dominant O. caudatum, subdominants – L. elongata aff., P. balticum, C. pelagicus, C. criophilum; in some years, at selected sites of the Barents Sea most of the total number has been formed to unusual species (Emiliania huxleyi, Mesoporos perforatus. The less stable characteristics of microplancton are dominant species composition in the biomass structure, total number of cells and their distribution in the water column.

  15. The Origin and Evolution of Baeyer-Villiger Monooxygenases (BVMOs: An Ancestral Family of Flavin Monooxygenases.

    Directory of Open Access Journals (Sweden)

    Maria Laura Mascotti

    Full Text Available The Baeyer-Villiger Monooxygenases (BVMOs are enzymes belonging to the "Class B" of flavin monooxygenases and are capable of performing exquisite selective oxidations. These enzymes have been studied from a biotechnological perspective, but their physiological substrates and functional roles are widely unknown. Here, we investigated the origin, taxonomic distribution and evolutionary history of the BVMO genes. By using in silico approaches, 98 BVMO encoding genes were detected in the three domains of life: Archaea, Bacteria and Eukarya. We found evidence for the presence of these genes in Metazoa (Hydra vulgaris, Oikopleura dioica and Adineta vaga and Haptophyta (Emiliania huxleyi for the first time. Furthermore, a search for other "Class B" monooxygenases (flavoprotein monooxygenases--FMOs--and N-hydroxylating monooxygenases--NMOs was conducted. These sequences were also found in the three domains of life. Phylogenetic analyses of all "Class B" monooxygenases revealed that NMOs and BVMOs are monophyletic, whereas FMOs form a paraphyletic group. Based on these results, we propose that BVMO genes were already present in the last universal common ancestor (LUCA and their current taxonomic distribution is the result of differential duplication and loss of paralogous genes.

  16. The influence of marine microbial activities on aerosol production: A laboratory mesocosm study

    Science.gov (United States)

    Alpert, Peter A.; Kilthau, Wendy P.; Bothe, Dylan W.; Radway, JoAnn C.; Aller, Josephine Y.; Knopf, Daniel A.

    2015-09-01

    The oceans cover most of the Earth's surface, contain nearly half the total global primary biomass productivity, and are a major source of atmospheric aerosol particles. Here we experimentally investigate links between biological activity in seawater and sea spray aerosol (SSA) flux, a relationship of potential significance for organic aerosol loading and cloud formation over the oceans and thus for climate globally. Bubbles were generated in laboratory mesocosm experiments either by recirculating impinging water jets or glass frits. Experiments were conducted with Atlantic Ocean seawater collected off the eastern end of Long Island, NY, and with artificial seawater containing cultures of bacteria and phytoplankton Thalassiosira pseudonana, Emiliania huxleyi, and Nannochloris atomus. Changes in SSA size distributions occurred during all phases of bacterial and phytoplankton growth, as characterized by cell concentrations, dissolved organic carbon, total particulate carbon, and transparent exopolymer particles (gel-forming polysaccharides representing a major component of biogenic exudate material). Over a 2 week growth period, SSA particle concentrations increased by a factor of less than 2 when only bacteria were present and by a factor of about 3 when bacteria and phytoplankton were present. Production of jet-generated SSA particles of diameter less than 200 nm increased with time, while production of all particle diameters increased with time when frits were used. The implications of a marine biological activity dependent SSA flux are discussed.

  17. Direct measurements of the light dependence of gross photosynthesis and oxygen consumption in the ocean

    Science.gov (United States)

    Bailleul, B.; Park, J.; Brown, C. M.; Bidle, K. D.; Lee, S.; Falkowski, P. G.

    2016-02-01

    For decades, a lack of understanding of how respiration is influenced by light has been stymying our ability to quantitatively analyze how phytoplankton allocate carbon in situ and the biological mechanisms that participate to the fate of blooms. Using membrane inlet mass spectrometry (MIMS), the light dependencies of gross photosynthesis and oxygen uptake rates were measured during the bloom demises of two prymnesiophytes, in two open ocean regions. In the North Atlantic, dominated by Emiliania huxleyi, respiration was independent of irradiance and was higher than the gross photosynthetic rate at all irradiances. In the Amundsen Sea (Antarctica), dominated by Phaeocystis antarctica, the situation was very different. Dark respiration was one order of magnitude lower than the maximal gross photosynthetic rate. ut the oxygen uptake rate increased by 10 fold at surface irradiances, where it becomes higher than gross photosynthesis. Our results suggest that the light dependence of oxygen uptake in P. antarctica has two sources: one is independent of photosynthesis, and is possibly associated with the photo-reduction of O2 mediated by dissolved organic matter; the second reflects the activity of an oxidase fueled in the light with photosynthetic electron flow. Interestingly, these dramatic light-dependent changes in oxygen uptake were not reproduced in nutrient-replete P. antarctica cultures, in the laboratory. Our measurements highlight the importance of improving our understanding of oxygen consuming reactions in the euphotic zone, which is critical to investigating the physiology of phytoplankton and tracing the fate of phytoplankton blooms.

  18. Variations and controlling factors of the coccolith weight in the Western Pacific Warm Pool over the last 200 ka

    Science.gov (United States)

    Liang, Dan; Liu, Chuanlian

    2016-06-01

    Using a coccolith weight analytic software (Particle Analyser), we analyze most abundant coccolith species in a sediment core from the central Western Pacific Warm Pool (WPWP) and calculate coccolith size and weight variations over the last 200 ka. These variations are compared with the trends of sea surface temperature (SST), primary productivity (PP), sea surface salinity (SSS), and insolation. Our results demonstrate that the size and weight of the coccoliths varied in response to variations of these factors, and their average total weight is primarily related to the relative abundance of the dominant species GEO ( Gephyrocapsa oceanica). The variation in weight of EMI ( Emiliania huxleyi) and GEE ( Gephyrocapsa ericsonii) are mainly influenced by nutrients, and the variation of GEM ( G. muellerae conformis) and GEO ( G. oceanica) weight are mainly influenced by SST. For all of the taxa weight, PP and SST present apparent precession or semi-precession cycles, we consider that the mono-coccolith weight of the Equatorial Western Pacific is primarily affected by precession drived thermocline and nutricline variation.

  19. Influence of food on the assimilation of selected metals in tropical bivalves from the New Caledonia lagoon: Qualitative and quantitative aspects

    International Nuclear Information System (INIS)

    Hedouin, Laetitia; Metian, Marc; Lacoue-Labarthe, Thomas; Fichez, Renaud; Teyssie, Jean-Louis; Bustamante, Paco; Warnau, Michel

    2010-01-01

    The present study aimed at examining the influence of food quality and quantity on the assimilation efficiency (AE) of metals in two abundant bivalves in the New Caledonia lagoon, the oyster Isognomon isognomon and the clam Gafrarium tumidum. Bivalves were exposed via their food to the radiotracers of three metals of concern in New Caledonia ( 54 Mn, 57 Co and 65 Zn) under different feeding conditions (phytoplankton species, cell density, and cell-associated metal concentration). When bivalves were fed Heterocapsa triquetra, Emiliania huxleyi and Isochrysis galbana, AE of Mn, Co and Zn was strongly influenced by the phytoplankton species and by the metal considered. In contrast, when fed one given phytoplankton species previously exposed to different concentrations of Co, phytoplankton-associated Co load had no influence on the AE and on the retention time of the metal in both bivalves. Metals ingested with I. galbana displayed generally the highest AE in both bivalve species, except for Mn in clams for which the highest AE was observed for H. triquetra. Influence of food quantity was investigated by exposing bivalves to different cell densities of I. galbana (5 x 10 3 , 10 4 or 5 x 10 4 cell ml -1 ). As for food quality, food quantity was found to influence AE of Mn, Co and Zn, the highest AE being observed when bivalves were fed the lowest cell density. Overall, results indicate that the two bivalve species are able to adjust their feeding strategies according to the food conditions prevailing in their environment.

  20. The fate of pelagic CaCO3 production in a high CO2 ocean: a model study

    Directory of Open Access Journals (Sweden)

    C. Ethe

    2007-07-01

    Full Text Available This model study addresses the change in pelagic calcium carbonate production (CaCO3, as calcite in the model and dissolution in response to rising atmospheric CO2. The parameterization of CaCO3 production includes a dependency on the saturation state of seawater with respect to calcite. It was derived from laboratory and mesocosm studies on particulate organic and inorganic carbon production in Emiliania huxleyi as a function of pCO2. The model predicts values of CaCO3 production and dissolution in line with recent estimates. The effect of rising pCO2 on CaCO3 production and dissolution was quantified by means of model simulations forced with atmospheric CO2 increasing at a rate of 1% per year from 286 ppm to 1144 ppm over a 140 year time-period. The simulation predicts a decrease of CaCO3 production by 27%. The combined change in production and dissolution of CaCO3 yields an excess uptake of CO2 from the atmosphere by the ocean of 5.9 GtC over the period of 140 years.

  1. Response of marine viral populations to a nutrient induced phytoplankton bloom at different pCO2 levels

    Directory of Open Access Journals (Sweden)

    R.-A. Sandaa

    2008-04-01

    Full Text Available During the PeECE III mesocosm experiment in 2005 we investigated how the virioplankton community responded to increased levels of nutrients (N and P and CO2. We applied a combination of flow cytometry, Pulsed Field Gel Electrophoresis and degenerate PCR primers to categorize and quantify individual viral populations, and to investigate their temporal dynamics. Species specific and degenerate primers enabled us to identify two specific large dsDNA viruses, EhV and CeV, infecting the haptophytes Emiliania huxleyi and Crysochromulina ericina, respectively. Some of the viral populations detected and enumerated by flow cytometry did not respond to altered CO2-levels, but the abundance of EhV and an unidentified dsDNA virus decreased with increasing CO2 levels. Our results thus indicate that CO2 conditions, or the related change in pH, may affect the marine pelagic food web at the viral level. Our results also demonstrate that in order to unravel ecological problems as how CO2 and nutrient levels affect the relationship between marine algal viruses and their hosts, we need to continue the effort to develop molecular markers used to identify both hosts and viruses.

  2. Genome Sequence and Transcriptome Analyses of Chrysochromulina tobin: Metabolic Tools for Enhanced Algal Fitness in the Prominent Order Prymnesiales (Haptophyceae.

    Directory of Open Access Journals (Sweden)

    Blake T Hovde

    Full Text Available Haptophytes are recognized as seminal players in aquatic ecosystem function. These algae are important in global carbon sequestration, form destructive harmful blooms, and given their rich fatty acid content, serve as a highly nutritive food source to a broad range of eco-cohorts. Haptophyte dominance in both fresh and marine waters is supported by the mixotrophic nature of many taxa. Despite their importance the nuclear genome sequence of only one haptophyte, Emiliania huxleyi (Isochrysidales, is available. Here we report the draft genome sequence of Chrysochromulina tobin (Prymnesiales, and transcriptome data collected at seven time points over a 24-hour light/dark cycle. The nuclear genome of C. tobin is small (59 Mb, compact (∼ 40% of the genome is protein coding and encodes approximately 16,777 genes. Genes important to fatty acid synthesis, modification, and catabolism show distinct patterns of expression when monitored over the circadian photoperiod. The C. tobin genome harbors the first hybrid polyketide synthase/non-ribosomal peptide synthase gene complex reported for an algal species, and encodes potential anti-microbial peptides and proteins involved in multidrug and toxic compound extrusion. A new haptophyte xanthorhodopsin was also identified, together with two "red" RuBisCO activases that are shared across many algal lineages. The Chrysochromulina tobin genome sequence provides new information on the evolutionary history, ecology and economic importance of haptophytes.

  3. Proteomic analysis of the EhV-86 virion

    Directory of Open Access Journals (Sweden)

    Lilley Kathryn S

    2008-03-01

    Full Text Available Abstract Background Emiliania huxleyi virus 86 (EhV-86 is the type species of the genus Coccolithovirus within the family Phycodnaviridae. The fully sequenced 407,339 bp genome is predicted to encode 473 protein coding sequences (CDSs and is the largest Phycodnaviridae sequenced to date. The majority of EhV-86 CDSs exhibit no similarity to proteins in the public databases. Results Proteomic analysis by 1-DE and then LC-MS/MS determined that the virion of EhV-86 is composed of at least 28 proteins, 23 of which are predicted to be membrane proteins. Besides the major capsid protein, putative function can be assigned to 4 other components of the virion: two lectin proteins, a thioredoxin and a serine/threonine protein kinase. Conclusion This study represents the first steps toward the identification of the protein components that make up the EhV-86 virion. Aside from the major capsid protein, whose function in the virion is well known and defined, the nature of the other proteins suggest roles involved with viral budding, caspase activation, signalling, anti-oxidation, virus adsorption and host range determination.

  4. Spontaneous Assembly of Exopolymers from Phytoplankton

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    Yong-Xue Ding

    2009-01-01

    Full Text Available Phytoplankton exopolymeric substances (EPS contribute significantly to the dissolved organic car bon (DOC pool in the ocean, playing crucial roles in the surface ocean car bon cycle. Recent studies have demonstrated that ~10% of marine DOC can self-assemble as microgels through electro static Ca bonds providing hotspots of enriched microbial substrate. How ever, the question whether EPS can self-assemble and the formation mechanisms for EPS microgels have not been examined. Here were port that EPS from three representative phytoplankton species, Synechococcus, Emiliania huxleyi, and Skeletonema costatum can spontaneously self assemble in artificial sea water (ASW, forming microscopic gels of ~ 3 - 4 __m in diameter. Different from the marine DOC polymers assembly, these EPS samples can self-assemble in Ca2+-free ASW. Further experiments from fluorescence enhancement and chemical composition analysis confirmed the existence of fair amounts of hydrophobic domains in these EPS samples. These results suggest that hydrophobic interactions play a key role in the assembly of EPS from these three species of marine phytoplankton.

  5. Pleistocene calcareous nannofossil biochronology at IODP Site U1385 (Expedition 339)

    Science.gov (United States)

    Balestra, B.; Flores, J.-A.; Hodell, D. A.; Hernández-Molina, F. J.; Stow, D. A. V.

    2015-12-01

    During Integrated Ocean Drilling Program (IODP) Expedition 339, Site U1385 (37°34‧N, 10°7‧W, 2578 m below sea level) was drilled in the lower slope of the Portuguese margin, to provide a marine reference section of Pleistocene millennial-scale climate variability. Five holes were cored using the Advanced Piston Corer (APC) to a depth of ~ 151 m below sea floor (mbsf) recovering a continuous stratigraphic record covering the past 1.4 Ma. Here we present results of the succession of standard and unconventional calcareous nannofossil biostratigraphic events. The quantitative study of calcareous nannofossils showed well-preserved and abundant assemblages throughout the core. Most conventional Pleistocene events were recognized and the timing of bioevents were calibrated using correlation to the new oxygen isotope stratigraphy record developed for the Site U1385. The analyses provide further data on the stratigraphic distribution of selected species and genera, such as the large Emiliania huxleyi (> 4 μm), Gephyrocapsa caribbeanica, Helicosphaera inversa, Gephyrocapsa omega and Reticulofenestra asanoi (> 6 μm) and other circular-subcircular small reticulofenestrids, resulting in new insights into the environmental control of their stratigraphic patterns. Finally, the comparison between nannofossil datums and oxygen isotope stratigraphy on the same samples has resulted in an accurate revision of timing of the events, providing valuable biochronologic information.

  6. Is chloroplastic class IIA aldolase a marine enzyme?

    Science.gov (United States)

    Miyasaka, Hitoshi; Ogata, Takeru; Tanaka, Satoshi; Ohama, Takeshi; Kano, Sanae; Kazuhiro, Fujiwara; Hayashi, Shuhei; Yamamoto, Shinjiro; Takahashi, Hiro; Matsuura, Hideyuki; Hirata, Kazumasa

    2016-01-01

    Expressed sequence tag analyses revealed that two marine Chlorophyceae green algae, Chlamydomonas sp. W80 and Chlamydomonas sp. HS5, contain genes coding for chloroplastic class IIA aldolase (fructose-1, 6-bisphosphate aldolase: FBA). These genes show robust monophyly with those of the marine Prasinophyceae algae genera Micromonas, Ostreococcus and Bathycoccus, indicating that the acquisition of this gene through horizontal gene transfer by an ancestor of the green algal lineage occurred prior to the divergence of the core chlorophytes (Chlorophyceae and Trebouxiophyceae) and the prasinophytes. The absence of this gene in some freshwater chlorophytes, such as Chlamydomonas reinhardtii, Volvox carteri, Chlorella vulgaris, Chlorella variabilis and Coccomyxa subellipsoidea, can therefore be explained by the loss of this gene somewhere in the evolutionary process. Our survey on the distribution of this gene in genomic and transcriptome databases suggests that this gene occurs almost exclusively in marine algae, with a few exceptions, and as such, we propose that chloroplastic class IIA FBA is a marine environment-adapted enzyme. This hypothesis was also experimentally tested using Chlamydomonas W80, for which we found that the transcript levels of this gene to be significantly lower under low-salt (that is, simulated terrestrial) conditions. Expression analyses of transcriptome data for two algae, Prymnesium parvum and Emiliania huxleyi, taken from the Sequence Read Archive database also indicated that the expression of this gene under terrestrial conditions (low NaCl and low sulfate) is significantly downregulated. Thus, these experimental and transcriptome data provide support for our hypothesis. PMID:27058504

  7. Bioaccumulation of technetium by marine phytoplankton

    International Nuclear Information System (INIS)

    Fisher, N.S.

    1982-01-01

    /sup 95m/Tc, in the IV and VII oxidation states, was added in picomolar quantities to monocultures of seven species of marine phytoplankton, including a green algae (Dunaliella tertiolecta), a diatom (Thalassiosira pseudonana), a blue-green alga (Oscillatoria woronichinii), a prasinophyte (Testraselmis chuii), two haptophytes (Emiliania huxleyi and Cricosphaera carterae), and a dinoflagellate (Heterocapsa pygmaea). Cultures were incubated for 4 days, and uptake of Tc was periodically determined by ν spectroscopy of filtered and unfiltered samples. All the Tc remained in the water column in all flasks, but none of the species appreciably concentrated the element in either oxidation state. Mean uptake (measured as the fraction retained on filters) for all species was 0.029% for Tc(IV) and 0.023% for Tc(VII), neither of which was significantly different from the uninoculated control cultures. Wet weight concentration factors never exceeded 20 for any species, 3 orders of magnitude lower than previously reported for phytoplankton and Tc. The results indicate that phytoplankton are likely to have negligble influence on the cycling of Tc in marine systems

  8. The Origin and Evolution of Baeyer—Villiger Monooxygenases (BVMOs): An Ancestral Family of Flavin Monooxygenases

    Science.gov (United States)

    Mascotti, Maria Laura; Lapadula, Walter Jesús; Juri Ayub, Maximiliano

    2015-01-01

    The Baeyer—Villiger Monooxygenases (BVMOs) are enzymes belonging to the “Class B” of flavin monooxygenases and are capable of performing exquisite selective oxidations. These enzymes have been studied from a biotechnological perspective, but their physiological substrates and functional roles are widely unknown. Here, we investigated the origin, taxonomic distribution and evolutionary history of the BVMO genes. By using in silico approaches, 98 BVMO encoding genes were detected in the three domains of life: Archaea, Bacteria and Eukarya. We found evidence for the presence of these genes in Metazoa (Hydra vulgaris, Oikopleura dioica and Adineta vaga) and Haptophyta (Emiliania huxleyi) for the first time. Furthermore, a search for other “Class B” monooxygenases (flavoprotein monooxygenases –FMOs – and N-hydroxylating monooxygenases – NMOs) was conducted. These sequences were also found in the three domains of life. Phylogenetic analyses of all “Class B” monooxygenases revealed that NMOs and BVMOs are monophyletic, whereas FMOs form a paraphyletic group. Based on these results, we propose that BVMO genes were already present in the last universal common ancestor (LUCA) and their current taxonomic distribution is the result of differential duplication and loss of paralogous genes. PMID:26161776

  9. Assessing the potential long-term increase of oceanic fossil fuel CO2 uptake due to CO2-calcification feedback

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    T. M. Lenton

    2007-07-01

    Full Text Available Plankton manipulation experiments exhibit a wide range of sensitivities of biogenic calcification to simulated anthropogenic acidification of the ocean, with the "lab rat" of planktic calcifiers, Emiliania huxleyi apparently not representative of calcification generally. We assess the implications of this observational uncertainty by creating an ensemble of realizations of an Earth system model that encapsulates a comparable range of uncertainty in calcification response to ocean acidification. We predict that a substantial reduction in marine carbonate production is possible in the future, with enhanced ocean CO2 sequestration across the model ensemble driving a 4–13% reduction in the year 3000 atmospheric fossil fuel CO2 burden. Concurrent changes in ocean circulation and surface temperatures in the model contribute about one third to the increase in CO2 uptake. We find that uncertainty in the predicted strength of CO2-calcification feedback seems to be dominated by the assumption as to which species of calcifier contribute most to carbonate production in the open ocean.

  10. Investigation of the Genetics and Biochemistry of Roseobacticide Production in the Roseobacter Clade Bacterium Phaeobacter inhibens

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    Rurun Wang

    2016-03-01

    Full Text Available Roseobacter clade bacteria are abundant in surface waters and are among the most metabolically diverse and ecologically significant species. This group includes opportunistic symbionts that associate with micro- and macroalgae. We have proposed that one representative member, Phaeobacter inhibens, engages in a dynamic symbiosis with the microalga Emiliania huxleyi. In one phase, mutualistically beneficial molecules are exchanged, including the Roseobacter-produced antibiotic tropodithietic acid (TDA, which is thought to protect the symbiotic interaction. In an alternative parasitic phase, triggered by algal senescence, the bacteria produce potent algaecides, the roseobacticides, which kill the algal host. Here, we employed genetic and biochemical screens to identify the roseobacticide biosynthetic gene cluster. By using a transposon mutagenesis approach, we found that genes required for TDA synthesis—the tda operon and paa catabolon—are also necessary for roseobacticide production. Thus, in contrast to the one-cluster–one-compound paradigm, the tda gene cluster can generate two sets of molecules with distinct structures and bioactivities. We further show that roseobacticide production is quorum sensing regulated via an N-acyl homoserine lactone signal (3-OH–C10-HSL. To ensure tight regulation of algaecide production, and thus of a lifestyle switch from mutualism to parasitism, roseobacticide biosynthesis necessitates the presence of both an algal senescence molecule and a quorum sensing signal.

  11. Losses, Expansions, and Novel Subunit Discovery of Adaptor Protein Complexes in Haptophyte Algae.

    Science.gov (United States)

    Lee, Laura J Y; Klute, Mary J; Herman, Emily K; Read, Betsy; Dacks, Joel B

    2015-11-01

    The phylum Haptophyta (Diaphoratickes) contains marine algae that perform biomineralization, extruding large, distinctive calcium carbonate scales (coccoliths) that completely cover the cell. Coccolith production is an important part of global carbon cycling; however, the membrane trafficking pathway by which they are secreted has not yet been elucidated. In most eukaryotes, post-Golgi membrane trafficking involves five heterotetrameric adaptor protein (AP) complexes, which impart cargo selection specificity. To better understand coccolith secretion, we performed comparative genomic, phylogenetic, and transcriptomic analyses of the AP complexes in Emiliania huxleyi strains 92A, Van556, EH2, and CCMP1516, and related haptophytes Gephyrocapsa oceanica and Isochrysis galbana; the latter has lost the ability to biomineralize. We show that haptophytes have a modified membrane trafficking system (MTS), as we found both AP subunit losses and duplications. Additionally, we identified a single conserved subunit of the AP-related TSET complex, whose expression suggests a functional role in membrane trafficking. Finally, we detected novel alpha adaptin ear and gamma adaptin ear proteins, the first of their kind to be described outside of opisthokonts. These novel ear proteins and the sculpting of the MTS may support the capacity for biomineralization in haptophytes, enhancing their ability to perform this highly specialized form of secretion. Copyright © 2015 Elsevier GmbH. All rights reserved.

  12. Seasonal Dynamics of Haptophytes and dsDNA Algal Viruses Suggest Complex Virus-Host Relationship.

    Science.gov (United States)

    Johannessen, Torill Vik; Larsen, Aud; Bratbak, Gunnar; Pagarete, António; Edvardsen, Bente; Egge, Elianne D; Sandaa, Ruth-Anne

    2017-04-20

    Viruses influence the ecology and diversity of phytoplankton in the ocean. Most studies of phytoplankton host-virus interactions have focused on bloom-forming species like Emiliania huxleyi or Phaeocystis spp. The role of viruses infecting phytoplankton that do not form conspicuous blooms have received less attention. Here we explore the dynamics of phytoplankton and algal viruses over several sequential seasons, with a focus on the ubiquitous and diverse phytoplankton division Haptophyta, and their double-stranded DNA viruses, potentially with the capacity to infect the haptophytes. Viral and phytoplankton abundance and diversity showed recurrent seasonal changes, mainly explained by hydrographic conditions. By 454 tag-sequencing we revealed 93 unique haptophyte operational taxonomic units (OTUs), with seasonal changes in abundance. Sixty-one unique viral OTUs, representing Megaviridae and Phycodnaviridae , showed only distant relationship with currently isolated algal viruses. Haptophyte and virus community composition and diversity varied substantially throughout the year, but in an uncoordinated manner. A minority of the viral OTUs were highly abundant at specific time-points, indicating a boom-bust relationship with their host. Most of the viral OTUs were very persistent, which may represent viruses that coexist with their hosts, or able to exploit several host species.

  13. Zanclean/Piacenzian transition on Cyprus (SE Mediterranean): calcareous nannofossil and Sea Surface Temperatures evidence of sapropel formation

    Science.gov (United States)

    Athanasiou, Maria; Triantaphyllou, Maria; Bouloubassi, Ioanna; Dimiza, Margarita; Gogou, Alexandra; Klein, Vincent; Parinos, Constantine; Theodoroyu, George

    2016-04-01

    Quantitative analyses of calcareous nannofossils in the sediments of Pissouri South section on the island of Cyprus have produced a paleoceanographic record reflecting the paleoclimatic conditions during Zanclean/Piacenzian transition. According to the performed calcareous nannofossil biostratigraphy the studied section is correlated with MNN14/15 and MNN16 calcareous nannofossil biozones and is astronomically dated between 4.065 and 3.217 Ma. Intervals of increased organic carbon content along with the positive values of Florisphaera profunda, Helicosphaera sellii, Discoaster spp. and the subsequent increase of stratification S-index correspond to the sapropel deposition during periods of wetter climate and intense continental runoff especially from the river Nile. These layers are alternating with grey marly intervals, featured by the increased values of small placoliths of Reticulofenestra and Gephyrocapsa species, which are indicative of eutrophic conditions during intense surface waters mixing. Pissouri South section comprises a SSTs sequence using alkenone unsaturation index (Uk 37) providing with the first continuous record from SE Mediterranean covering the Zanclean/Piacenzian (Pliocene) transition (~ 4.1-3.2 Ma). Correlation of the total alkenone concentration to the calcareous nannofossil assemblage and especially representatives among Noelaerhabdaceae family revealed that Pseudoemiliania lacunosa probably had similar temperature sensitivity to that of Emiliania huxleyi, currently producing alkenones in present day oceans.Our data support the prevalence of a generally warm phase characterized by the absence of high-frequency climate variations in the southeastern Mediterranean during the Zanclean/Piacenzian (Early/Late Pliocene) transition.

  14. Reduced calcification of marine plankton in response to increased atmospheric CO2.

    Science.gov (United States)

    Riebesell, U; Zondervan, I; Rost, B; Tortell, P D; Zeebe, R E; Morel, F M

    2000-09-21

    The formation of calcareous skeletons by marine planktonic organisms and their subsequent sinking to depth generates a continuous rain of calcium carbonate to the deep ocean and underlying sediments. This is important in regulating marine carbon cycling and ocean-atmosphere CO2 exchange. The present rise in atmospheric CO2 levels causes significant changes in surface ocean pH and carbonate chemistry. Such changes have been shown to slow down calcification in corals and coralline macroalgae, but the majority of marine calcification occurs in planktonic organisms. Here we report reduced calcite production at increased CO2 concentrations in monospecific cultures of two dominant marine calcifying phytoplankton species, the coccolithophorids Emiliania huxleyi and Gephyrocapsa oceanica. This was accompanied by an increased proportion of malformed coccoliths and incomplete coccospheres. Diminished calcification led to a reduction in the ratio of calcite precipitation to organic matter production. Similar results were obtained in incubations of natural plankton assemblages from the north Pacific ocean when exposed to experimentally elevated CO2 levels. We suggest that the progressive increase in atmospheric CO2 concentrations may therefore slow down the production of calcium carbonate in the surface ocean. As the process of calcification releases CO2 to the atmosphere, the response observed here could potentially act as a negative feedback on atmospheric CO2 levels.

  15. Dissolution of coccolithophorid calcite by microzooplankton and copepod grazing

    Science.gov (United States)

    Antia, A. N.; Suffrian, K.; Holste, L.; Müller, M. N.; Nejstgaard, J. C.; Simonelli, P.; Carotenuto, Y.; Putzeys, S.

    2008-01-01

    Independent of the ongoing acidification of surface seawater, the majority of the calcium carbonate produced in the pelagial is dissolved by natural processes above the lysocline. We investigate to what extent grazing and passage of coccolithophorids through the guts of copepods and the food vacuoles of microzooplankton contribute to calcite dissolution. In laboratory experiments where the coccolithophorid Emiliania huxleyi was fed to the rotifer Brachionus plicatilis, the heterotrophic flagellate Oxyrrhis marina and the copepod Acartia tonsa, calcite dissolution rates of 45-55%, 37-53% and 5-22% of ingested calcite were found. We ascribe higher loss rates in microzooplankton food vacuoles as compared to copepod guts to the strongly acidic digestion and the individual packaging of algal cells. In further experiments, specific rates of calcification and calcite dissolution were also measured in natural populations during the PeECE III mesocosm study under differing ambient pCO2 concentrations. Microzooplankton grazing accounted for between 27 and 70% of the dynamic calcite stock being lost per day, with no measurable effect of CO2 treatment. These measured calcite dissolution rates indicate that dissolution of calcite in the guts of microzooplankton and copepods can account for the calcite losses calculated for the global ocean using budget and model estimates.

  16. Improved monitoring of phytoplankton bloom dynamics in a Norwegian fjord by integrating satellite data, pigment analysis, and Ferrybox data with a coastal observation network

    Science.gov (United States)

    Volent, Zsolt; Johnsen, Geir; Hovland, Erlend K.; Folkestad, Are; Olsen, Lasse M.; Tangen, Karl; Sørensen, Kai

    2011-01-01

    Monitoring of the coastal environment is vitally important as these areas are of economic value and at the same time highly exposed to anthropogenic influence, in addition to variation of environmental variables. In this paper we show how the combination of bio-optical data from satellites, analysis of water samples, and a ship-mounted automatic flow-through sensor system (Ferrybox) can be used to detect and monitor phytoplankton blooms both spatially and temporally. Chlorophyll a (Chl a) data and turbidity from Ferrybox are combined with remotely sensed Chl a and total suspended matter from the MERIS instrument aboard the satellite ENVISAT (ENVIronmental SATellite) European Space Agency. Data from phytoplankton speciation and enumeration obtained by a national coastal observation network consisting of fish farms and the Norwegian Food Safety Authority are supplemented with data on phytoplankton pigments. All the data sets are then integrated in order to describe phytoplankton bloom dynamics in a Norwegian fjord over a growth season, with particular focus on Emiliania huxleyi. The approach represents a case example of how coastal environmental monitoring can be improved with existing instrument platforms. The objectives of the paper is to present the operative phytoplankton monitoring scheme in Norway, and to present an improved model of how such a scheme can be designed for a large part of the world's coastal areas.

  17. Lipid and DNA biomarker analyses of Narragansett Bay Sediments: Evaluating the UK'37 proxy in an Estuarine Environment

    Science.gov (United States)

    George, S. E.; Herbert, T.; Amaral-Zettler, L. A.; Richter, N.

    2017-12-01

    Long chain polyunsaturated alkenone (LCA) lipid biomarkers produced by haptophyte phytoplankton species within the Order Isochrysidales (Phylum Haptophyta) have proven exceptionally useful in paleotemperature studies by means of the Uk'37 and Uk37 indices. Two closely-related Group III haptophytes, Emiliania huxleyi and Gephyrocapsa oceanica are the primary alkenone synthesizers in the modern ocean, while freshwater systems host the distinct Group I phylotype, sometimes called the Greenland phylotype, in reference to the location of its original discovery. Group I haptophytes produce large quantities of the distinct C37:4 ketone, which acts as a chemical `fingerprint' in sediments. The utility of alkenones as a paleotemperature proxy in estuarine environments has remained largely untested, representing an under-utilized opportunity to construct high-resolution paleotemperature records from environments at the intersection of fluvial and marine systems. This uncertainty is due, in part, to the presence of multiple haptophyte groups in estuaries, resulting in a mixed alkenone signature. To determine the community composition of alkenone-producing haptophytes within Narragansett Bay, four geographically separated cores from within the Bay were analyzed for alkenones as well as haptophyte rRNA biomarker gene presence. Haptophyte rRNA genes (small and large subunit) were recovered from surface and near-subsurface samples, and in conjunction with alkenone profiles, reveal recent haptophyte community structure and alkenone production regimes throughout the Bay. A surprising result is the recovery of rRNA biomarker genes with a 100% match to the open-ocean alkenone producer E. huxleyi in locations away from large fresh water inputs to the Bay. Results of these analyses elucidate the effect of salinity and nutrient dynamics on alkenone-producing haptophyte communities and enhance applicability of long chain polyunsaturated alkenones as lipid biomarkers in estuarine

  18. Comment on ''Effects of long-term high CO2 exposure on two species of coccolithophore'' by Müller et al. (2010

    Directory of Open Access Journals (Sweden)

    S. Collins

    2010-07-01

    Full Text Available Populations can respond to environmental change over tens or hundreds of generations by shifts in phenotype that can be the result of a sustained physiological response, evolutionary (genetic change, shifts in community composition, or some combination of these factors. Microbes evolve on human timescales, and evolution may contribute to marine phytoplankton responses to global change over the coming decades. However, it is still unknown whether evolutionary responses are likely to contribute significantly to phenotypic change in marine microbial communities under high pCO2 regimes or other aspects of global change. Recent work by Müller et al. (2010 highlights that long-term responses of marine microbes to global change must be empirically measured and the underlying cause of changes in phenotype explained. Here, I briefly discuss how tools from experimental microbial evolution may be used to detect and measure evolutionary responses in marine phytoplankton grown in high CO2 environments and other environments of interest. I outline why the particular biology of marine microbes makes conventional experimental evolution challenging right now and make a case that marine microbes are good candidates for the development of new model systems in experimental evolution. I suggest that "black box" frameworks that focus on partitioning phenotypic change, such as the Price equation, may be useful in cases where direct measurements of evolutionary responses alone are difficult, and that such approaches could be used to test hypotheses about the underlying causes of phenotypic shifts in marine microbe communities responding to global change.

  19. Marine ecosystem community carbon and nutrient uptake stoichiometry under varying ocean acidification during the PeECE III experiment

    Directory of Open Access Journals (Sweden)

    R. G. J. Bellerby

    2008-11-01

    Full Text Available Changes to seawater inorganic carbon and nutrient concentrations in response to the deliberate CO2 perturbation of natural plankton assemblages were studied during the 2005 Pelagic Ecosystem CO2 Enrichment (PeECE III experiment. Inverse analysis of the temporal inorganic carbon dioxide system and nutrient variations was used to determine the net community stoichiometric uptake characteristics of a natural pelagic ecosystem perturbed over a range of pCO2 scenarios (350, 700 and 1050 μatm. Nutrient uptake showed no sensitivity to CO2 treatment. There was enhanced carbon production relative to nutrient consumption in the higher CO2 treatments which was positively correlated with the initial CO2 concentration. There was no significant calcification response to changing CO2 in Emiliania huxleyi by the peak of the bloom and all treatments exhibited low particulate inorganic carbon production (~15 μmol kg−1. With insignificant air-sea CO2 exchange across the treatments, the enhanced carbon uptake was due to increase organic carbon production. The inferred cumulative C:N:P stoichiometry of organic production increased with CO2 treatment from 1:6.3:121 to 1:7.1:144 to 1:8.25:168 at the height of the bloom. This study discusses how ocean acidification may incur modification to the stoichiometry of pelagic production and have consequences for ocean biogeochemical cycling.

  20. Differential Growth Responses of Marine Phytoplankton to Herbicide Glyphosate.

    Directory of Open Access Journals (Sweden)

    Cong Wang

    Full Text Available Glyphosate is a globally popular herbicide to kill weeds and its wide applications may lead to accumulation in coastal oceans as a source of phosphorus (P nutrient or growth inhibitor of phytoplankton. We studied the physiological effects of glyphosate on fourteen species representing five major coastal phytoplankton phyla (haptophyta, bacillariophyta, dinoflagellata, raphidophyta, and chlorophyta. Based on growth responses to different concentrations of glyphosate under contrasting dissolved inorganic phosphorus (DIP conditions, we found that phytoplankton species could be classified into five groups. Group I (Emiliania huxleyi, Skeletonema costatum, Phaeodactylum tricornutum could utilize glyphosate as sole P-source to support growth in axenic culture, but in the presence of DIP, they were inhibited by both 36-μM and 360-μM glyphosate. Group II (Karenia mikimotoi, Prorocentrum minimum, Dunaliella tertiolecta, Symbiodinium sp., Heterosigma akashiwo and Alexandrium catenella could not utilize glyphosate as sole P-source to support growth, and in the presence of DIP growth was not affected by 36-μM but inhibited by 360-μM glyphosate. Glyphosate consistently enhanced growth of Group III (Isochrysis galbana and inhibited Group IV (Thalassiosira weissflogii, Thalassiosira pseudonana and Chattonella marina regardless of DIP condition. Group V (Amphidinium carterae exhibited no measurable response to glyphosate regardless of DIP condition. This grouping is not congruent with the phylogenetic relationships of the phytoplankton species suggesting functional differentiation driven by environmental pressure. We conclude that glyphosate could be used as P-source by some species while is toxic to some other species and yet has no effects on others. The observed differential effects suggest that the continued use of glyphosate and increasing concentration of this herbicide in the coastal waters will likely exert significant impact on coastal marine

  1. Cocolitóforos en sedimentos marinos frente a la entrada occidental del Estrecho de Magallanes (53°S revelan cambios en la productividad durante los últimos 30.000 años

    Directory of Open Access Journals (Sweden)

    Gloria E Sánchez

    2014-11-01

    Full Text Available Se presenta un nuevo registro de producción exportada de cocolitóforos (cocolitos durante los últimos 30.000 años, basado en el estudio de un testigo de sedimento marino obtenido frente a la entrada occidental del Estrecho de Magallanes (testigo MD07-3128; 53°S, 75°W. Este testigo reveló la presencia de una asociación compuesta por trece taxones de cocolitóforos dominada por Gephyrocapsa "small" (representando en promedio >80% de la asociación total y acompañada, en menor proporción (1-10%, por dos morfotipos de Emiliania huxleyi, Coccolithus pelagicus y Calcidiscus leptoporus. La concentración de cocolitos se correlacionó positivamente con el contenido de CaCO3 (P 30% y la abundancia de cocolitos (~10(9 cocolitos g-1 sedimento seco coincidieron con periodos relativamente cálidos (e.g., el Holoceno. Se hallaron marcadas diferencias al comparar estos datos con el registro de cocolitos de Saavedra-Pellitero et al. (2011 para el sitio ODP 1233 a los 41°S: en el sitio ODP 1233 la producción de cocolitóforos fue máxima durante el Último Máximo Glacial en respuesta a la advección hacia el norte de las aguas ricas en macronutrientes de la corriente Circumpolar Antártica. En contraste, el sitio MD07-3128 experimentó al mismo tiempo una baja en productividad de cocolitóforos probablemente relacionada al efecto negativo ejercido por un alto aporte de material terrígeno y agua de deshielo proveniente del gran casquete de hielo patagónico.

  2. Genome of Phaeocystis globosa virus PgV-16T highlights the common ancestry of the largest known DNA viruses infecting eukaryotes

    Science.gov (United States)

    Santini, Sebastien; Jeudy, Sandra; Bartoli, Julia; Poirot, Olivier; Lescot, Magali; Abergel, Chantal; Barbe, Valérie; Wommack, K. Eric; Noordeloos, Anna A. M.; Brussaard, Corina P. D.; Claverie, Jean-Michel

    2013-01-01

    Large dsDNA viruses are involved in the population control of many globally distributed species of eukaryotic phytoplankton and have a prominent role in bloom termination. The genus Phaeocystis (Haptophyta, Prymnesiophyceae) includes several high-biomass-forming phytoplankton species, such as Phaeocystis globosa, the blooms of which occur mostly in the coastal zone of the North Atlantic and the North Sea. Here, we report the 459,984-bp-long genome sequence of P. globosa virus strain PgV-16T, encoding 434 proteins and eight tRNAs and, thus, the largest fully sequenced genome to date among viruses infecting algae. Surprisingly, PgV-16T exhibits no phylogenetic affinity with other viruses infecting microalgae (e.g., phycodnaviruses), including those infecting Emiliania huxleyi, another ubiquitous bloom-forming haptophyte. Rather, PgV-16T belongs to an emerging clade (the Megaviridae) clustering the viruses endowed with the largest known genomes, including Megavirus, Mimivirus (both infecting acanthamoeba), and a virus infecting the marine microflagellate grazer Cafeteria roenbergensis. Seventy-five percent of the best matches of PgV-16T–predicted proteins correspond to two viruses [Organic Lake phycodnavirus (OLPV)1 and OLPV2] from a hypersaline lake in Antarctica (Organic Lake), the hosts of which are unknown. As for OLPVs and other Megaviridae, the PgV-16T sequence data revealed the presence of a virophage-like genome. However, no virophage particle was detected in infected P. globosa cultures. The presence of many genes found only in Megaviridae in its genome and the presence of an associated virophage strongly suggest that PgV-16T shares a common ancestry with the largest known dsDNA viruses, the host range of which already encompasses the earliest diverging branches of domain Eukarya. PMID:23754393

  3. Differential Growth Responses of Marine Phytoplankton to Herbicide Glyphosate

    Science.gov (United States)

    Wang, Cong; Lin, Xin; Li, Ling; Lin, Senjie

    2016-01-01

    Glyphosate is a globally popular herbicide to kill weeds and its wide applications may lead to accumulation in coastal oceans as a source of phosphorus (P) nutrient or growth inhibitor of phytoplankton. We studied the physiological effects of glyphosate on fourteen species representing five major coastal phytoplankton phyla (haptophyta, bacillariophyta, dinoflagellata, raphidophyta, and chlorophyta). Based on growth responses to different concentrations of glyphosate under contrasting dissolved inorganic phosphorus (DIP) conditions, we found that phytoplankton species could be classified into five groups. Group I (Emiliania huxleyi, Skeletonema costatum, Phaeodactylum tricornutum) could utilize glyphosate as sole P-source to support growth in axenic culture, but in the presence of DIP, they were inhibited by both 36-μM and 360-μM glyphosate. Group II (Karenia mikimotoi, Prorocentrum minimum, Dunaliella tertiolecta, Symbiodinium sp., Heterosigma akashiwo and Alexandrium catenella) could not utilize glyphosate as sole P-source to support growth, and in the presence of DIP growth was not affected by 36-μM but inhibited by 360-μM glyphosate. Glyphosate consistently enhanced growth of Group III (Isochrysis galbana) and inhibited Group IV (Thalassiosira weissflogii, Thalassiosira pseudonana and Chattonella marina) regardless of DIP condition. Group V (Amphidinium carterae) exhibited no measurable response to glyphosate regardless of DIP condition. This grouping is not congruent with the phylogenetic relationships of the phytoplankton species suggesting functional differentiation driven by environmental pressure. We conclude that glyphosate could be used as P-source by some species while is toxic to some other species and yet has no effects on others. The observed differential effects suggest that the continued use of glyphosate and increasing concentration of this herbicide in the coastal waters will likely exert significant impact on coastal marine phytoplankton

  4. Planktic foraminifer and coccolith contribution to carbonate export fluxes over the central Kerguelen Plateau

    Science.gov (United States)

    Rembauville, M.; Meilland, J.; Ziveri, P.; Schiebel, R.; Blain, S.; Salter, I.

    2016-05-01

    We report the contribution of planktic foraminifers and coccoliths to the particulate inorganic carbon (PIC) export fluxes collected over an annual cycle (October 2011/September 2012) on the central Kerguelen Plateau in the Antarctic Zone (AAZ) south of the Polar Front (PF). The seasonality of PIC flux was decoupled from surface chlorophyll a concentration and particulate organic carbon (POC) fluxes and was characterized by a late summer (February) maximum. This peak was concomitant with the highest satellite-derived sea surface PIC and corresponded to a Emiliania huxleyi coccoliths export event that accounted for 85% of the annual PIC export. The foraminifer contribution to the annual PIC flux was much lower (15%) and dominated by Turborotalita quinqueloba and Neogloboquadrina pachyderma. Foraminifer export fluxes were closely related to the surface chlorophyll a concentration, suggesting food availability as an important factor regulating the foraminifer's biomass. We compared size-normalized test weight (SNW) of the foraminifers with previously published SNW from the Crozet Islands using the same methodology and found no significant difference in SNW between sites for a given species. However, the SNW was significantly species-specific with a threefold increase from T. quinqueloba to Globigerina bulloides. The annual PIC:POC molar ratio of 0.07 was close to the mean ratio for the global ocean and lead to a low carbonate counter pump effect (~5%) compared to a previous study north of the PF (6-32%). We suggest that lowers counter pump effect south of the PF despite similar productivity levels is due to a dominance of coccoliths in the PIC fluxes and a difference in the foraminifers species assemblage with a predominance of polar species with lower SNW.

  5. Interrogating Host-virus Interactions and Elemental Transfer Using NanoSIMS

    Science.gov (United States)

    Pasulka, A.; Thamatrakoln, K.; Poulos, B.; Bidle, K. D.; Sullivan, M. B.; Orphan, V. J.

    2016-02-01

    Marine viruses (bacteriophage and eukaryotic viruses) impact microbial food webs by influencing microbial community structure, carbon and nutrient flow, and serving as agents of gene transfer. While the collective impact of viral activity has become more apparent over the last decade, there is a growing need for single-cell and single-virus level measurements of the associated carbon and nitrogen transfer, which ultimately shape the biogeochemical impact of viruses in the upper ocean. Stable isotopes have been used extensively for understanding trophic relationships and elemental cycling in marine food webs. While single-cell isotope approaches such as nanoscale secondary ion mass spectrometry (nanoSIMS) have been more readily used to study trophic interactions between microorganisms, isotopic enrichment in viruses has not been described. Here we used nanoSIMS to quantify the transfer of stable isotopes (13C and 15N) from host to individual viral particles in two distinct unicellular algal-virus model systems. These model systems represent a eukaryotic phytoplankton (Emiliania huxleyi strain CCMP374) and its 200nm coccolithovirus (EhV207), as well as a cyanobacterial phytoplankton (Synechococcus WH8101) and its 80nm virus (Syn1). Host cells were grown on labeled media for multiple generations, subjected to viral infection, and then viruses were harvested after lysis. In both cases, nanoSIMS measurements were able to detect 13C and 15N in the resulting viral particles significantly above the background noise. The isotopic enrichment in the viral particles mirrored that of the host. Through use of these laboratory model systems, we quantified the sensitivity (ion counts), spatial resolution, and reproducibility, including sources of methodological and biological variability, in stable isotope incorporation into viral particles. Our findings suggest that nanoSIMS can be successfully employed to directly probe virus-host interactions at the resolution of individual

  6. Productions of Volatile Organic Compounds (VOCs) in Surface Waters from Reactions with Atmospheric Ozone

    Science.gov (United States)

    Hopkins, Frances; Bell, Thomas; Yang, Mingxi

    2017-04-01

    Ozone (O3) is a key atmospheric oxidant, greenhouse gas and air pollutant. In marine environments, some atmospheric ozone is lost by reactions with aqueous compounds (e.g. dissolved organic material, DOM, dimethyl sulfide, DMS, and iodide) near the sea surface. These reactions also lead to formations of volatile organic compounds (VOCs). Removal of O3 by the ocean remains a large uncertainty in global and regional chemical transport models, hampering coastal air quality forecasts. To better understand the role of the ocean in controlling O3 concentrations in the coastal marine atmosphere, we designed and implemented a series of laboratory experiments whereby ambient surface seawater was bubbled with O3-enriched, VOC-free air in a custom-made glass bubble equilibration system. Gas phase concentrations of a range of VOCs were monitored continuously over the mass range m/z 33 - 137 at the outflow of the bubble equilibrator by a proton transfer reaction - mass spectrometer (PTR-MS). Gas phase O3 was also measured at the input and output of the equilibrator to monitor the uptake due to reactions with dissolved compounds in seawater. We observed consistent productions of a variety of VOCs upon reaction with O3, notably isoprene, aldehydes, and ketones. Aqueous DMS is rapidly removed from the reactions with O3. To test the importance of dissolved organic matter precursors, we added increasing (milliliter) volumes of Emiliania huxleyi culture to the equilibrator filled with aged seawater, and observed significant linear increases in gas phase concentrations of a number of VOCs. Reactions between DOM and O3 at the sea-air interface represent a potentially significant source of VOCs in marine air and a sink of atmospheric O3.

  7. Addressing the ice nucleating abilities of marine aerosol: A combination of deposition mode laboratory and field measurements

    Science.gov (United States)

    Ladino, L. A.; Yakobi-Hancock, J. D.; Kilthau, W. P.; Mason, R. H.; Si, M.; Li, J.; Miller, L. A.; Schiller, C. L.; Huffman, J. A.; Aller, J. Y.; Knopf, D. A.; Bertram, A. K.; Abbatt, J. P. D.

    2016-05-01

    This study addresses, through two types of experiments, the potential for the oceans to act as a source of atmospheric ice-nucleating particles (INPs). The INP concentration via deposition mode nucleation was measured in situ at a coastal site in British Columbia in August 2013. The INP concentration at conditions relevant to cirrus clouds (i.e., -40 °C and relative humidity with respect to ice, RHice = 139%) ranged from 0.2 L-1 to 3.3 L-1. Correlations of the INP concentrations with levels of anthropogenic tracers (i.e., CO, SO2, NOx, and black carbon) and numbers of fluorescent particles do not indicate a significant influence from anthropogenic sources or submicron bioaerosols, respectively. Additionally, the INPs measured in the deposition mode showed a poor correlation with the concentration of particles with sizes larger than 500 nm, which is in contrast with observations made in the immersion freezing mode. To investigate the nature of particles that could have acted as deposition INP, laboratory experiments with potential marine aerosol particles were conducted under the ice-nucleating conditions used in the field. At -40 °C, no deposition activity was observed with salt aerosol particles (sodium chloride and two forms of commercial sea salt: Sigma-Aldrich and Instant Ocean), particles composed of a commercial source of natural organic matter (Suwannee River humic material), or particle mixtures of sea salt and humic material. In contrast, exudates from three phytoplankton (Thalassiosira pseudonana, Nanochloris atomus, and Emiliania huxleyi) and one marine bacterium (Vibrio harveyi) exhibited INP activity at low RHice values, down to below 110%. This suggests that the INPs measured at the field site were of marine biological origins, although we cannot rule out other sources, including mineral dust.

  8. Northward advection of Atlantic water in the eastern Nordic Seas over the last 3000 yr

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    C. V. Dylmer

    2013-07-01

    Full Text Available Three marine sediment cores distributed along the Norwegian (MD95-2011, Barents Sea (JM09-KA11-GC, and Svalbard (HH11-134-BC continental margins have been investigated in order to reconstruct changes in the poleward flow of Atlantic waters (AW and in the nature of upper surface water masses within the eastern Nordic Seas over the last 3000 yr. These reconstructions are based on a limited set of coccolith proxies: the abundance ratio between Emiliania huxleyi and Coccolithus pelagicus, an index of Atlantic vs. Polar/Arctic surface water masses; and Gephyrocapsa muellerae, a drifted coccolith species from the temperate North Atlantic, whose abundance changes are related to variations in the strength of the North Atlantic Current. The entire investigated area, from 66 to 77° N, was affected by an overall increase in AW flow from 3000 cal yr BP (before present to the present. The long-term modulation of westerlies' strength and location, which are essentially driven by the dominant mode of the North Atlantic Oscillation (NAO, is thought to explain the observed dynamics of poleward AW flow. The same mechanism also reconciles the recorded opposite zonal shifts in the location of the Arctic front between the area off western Norway and the western Barents Sea–eastern Fram Strait region. The Little Ice Age (LIA was governed by deteriorating conditions, with Arctic/Polar waters dominating in the surface off western Svalbard and western Barents Sea, possibly associated with both severe sea ice conditions and a strongly reduced AW strength. A sudden short pulse of resumed high WSC (West Spitsbergen Current flow interrupted this cold spell in eastern Fram Strait from 330 to 410 cal yr BP. Our dataset not only confirms the high amplitude warming of surface waters at the turn of the 19th century off western Svalbard, it also shows that such a warming was primarily induced by an excess flow of AW which stands as unprecedented over the last 3000 yr.

  9. Nanofósseis Calcários da Área de Ressurgência de Cabo Frio, Brasil

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    Deise de Oliveira Delfino

    2013-01-01

    Full Text Available Nanofósseis calcários são um grupo de microfósseis, com representantes viventes e um abundante registro fóssil nos sedimentos marinhos. A maioria das pesquisas voltadas para estes fósseis apresenta como foco regiões de mar profundo (talude e bacia oceânica. São de interesse para a indústria do petróleo por sua aplicação em uma bioestratigrafia de alta resolução e em reconstruções paleoambientais. No Brasil ainda são incipientes os esforços para estudos dos nanofósseis nas áreas costeiras e de plataforma continental. O presente artigo tem por objetivo caracterizar a assembleia de nanofósseis calcários presente em testemunhos da área de ressurgência costeira de Cabo Frio e avaliar seu potencial como indicador paleoambiental na região. Para isto foram elaboradas lâminas com material do testemunho CF02-01B (23º16’S e 41º48’W, que corresponde a 268 cm do perfil sedimentar da plataforma de Cabo Frio. Vinte e sete espécies de nanofósseis calcários foram encontradas, sendo predominantes os táxons Emiliania huxleyi, Florisphaera profunda e Gephyrocapsa oceanica. Com base no perfil de distribuição destes táxons e sua paleoecologia foi possível subdividir os primeiros 151 cm do perfil sedimentar em quatro intervalos: 1 (~2800 a ~2300 anos AP e 3 (~1800 a ~1000 anos AP representativos de períodos de fortalecimento do sistema de ressurgência na área com predomínio da atuação da ACAS, menores temperaturas das águas superficiais, maiores taxas de nutrientes e aumento da produtividade; e 2 (~2300 a ~1800 anos AP e 4 (~1000 a ~700 anos AP representativos do enfraquecimento do sistema de ressurgência em Cabo Frio, com predomínio da influência da CB, águas superficiais mais quentes, com poucos nutrientes e baixa produtividade. Portanto, esta pesquisa ratificou a importância e eficiência do estudo dos nanofósseis calcários em regiões costeiras para reconstruções paleoambientais.

  10. Pleistocene to Miocene Calcareous Nannofossil Biostratigraphy from IODP Expedition 334 Hole U1381A and Expedition 352 Hole U1439A

    Science.gov (United States)

    Power, M.; Scientists, I. E.; Avery, A. J.

    2015-12-01

    Samples for this study were collected from drill cores taken during the Integrated Ocean Drilling Program (IODP) Expeditions 334 and 352 at Sites U1381 and U1439, respectively. Both of these expeditions were focused around subduction zones and, therefore, had priorities to determine time frames for the initiation of subduction. There are two main objectives for this study, the first being to age-date Pleistocene to Miocene sediments from the western offshore continental margin of Costa Rica (IODP Expedition 334) via calcareous nannofossils. The second objective is to age-date the Miocene sediments from the fore-arc of the Izu-Bonin-Mariana system, east of Japan (IODP Expedition 352), using calcareous nannofossils. Shore-based analysis allows for high-resolution study to determine exact biostratigraphic zonations. These zonations reflect specific time frames based on the occurrence or non-occurrence of certain nannofossil species. Once these zonations are determined, scientists can use the data to identify the initiation of seismic processes that often occur in these regions. Calcareous nannofossil biostratigraphy has now provided zonations for the samples taken from IODP Expedition 334 cores. Samples from core 6R are assigned to the Pleistocene nannofossil Zone NN19 due to the presence ofPseudoemiliania lacunosa and the absence of Emiliania huxleyi. Using the zonal scheme by de Kaenel (1999), this can further be broken down into Event 18 due to the presence of Gephyrocapsa oceanica larger than 4 μm but less than 5 μm, the presence of Calcidiscus macintyrei smaller than 11 μm, and the absence ofGephyrocapsa caribbeanica larger than 4 μm. De Kaenel (1999) has assigned this event datum an age of 1.718 Ma using orbital time scales and oxygen isotope data. Below these samples, an extensive hiatus ranges from the Pleistocene to the early Miocene. Samples from cores 7R through 10R are assigned to nannofossil zone NN5; however, it is impossible to constrain the top of

  11. Effects of CO2 on particle size distribution and phytoplankton abundance during a mesocosm bloom experiment (PeECE II

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    M. Schartau

    2008-04-01

    Full Text Available The influence of seawater carbon dioxide (CO2 concentration on the size distribution of suspended particles (2–60 μm and on phytoplankton abundance was investigated during a mesocosm experiment at the large scale facility (LFS in Bergen, Norway, in the frame of the Pelagic Ecosystem CO2 Enrichment study (PeECE II. In nine outdoor enclosures the partial pressure of CO2 in seawater was modified by an aeration system to simulate past (~190 μatm CO2, present (~370 μatm CO2 and future (~700 μatm CO2 CO2 conditions in triplicates. Due to the initial addition of inorganic nutrients, phytoplankton blooms developed in all mesocosms and were monitored over a period of 19 days. Seawater samples were collected daily for analysing the abundance of suspended particles and phytoplankton with the Coulter Counter and with Flow Cytometry, respectively. During the bloom period, the abundance of small particles (2 levels. At that time, a direct relationship between the total-surface-to-total-volume ratio of suspended particles and DIC concentration was determined for all mesocosms. Significant changes with respect to the CO2 treatment were also observed in the phytoplankton community structure. While some populations such as diatoms seemed to be insensitive to the CO2 treatment, others like Micromonas spp. increased with CO2, or showed maximum abundance at present day CO2 (i.e. Emiliania huxleyi. The strongest response to CO2 was observed in the abundance of small autotrophic nano-plankton that strongly increased during the bloom in the past CO2 mesocosms. Together, changes in particle size distribution and phytoplankton community indicate a complex interplay between the ability of the cells to physiologically respond to changes in CO2 and size selection. Size of cells is of general importance for a variety of processes in marine systems such as diffusion-limited uptake of substrates, resource allocation, predator-prey interaction, and gravitational settling

  12. Earth 2075 (CO2) - can Ocean-Amplified Carbon Capture (oacc) Impart Atmospheric CO2-SINKING Ability to CCS Fossil Energy?

    Science.gov (United States)

    Fry, R.; Routh, M.; Chaudhuri, S.; Fry, S.; Ison, M.; Hughes, S.; Komor, C.; Klabunde, K.; Sethi, V.; Collins, D.; Polkinghorn, W.; Wroobel, B.; Hughes, J.; Gower, G.; Shkolnik, J.

    2017-12-01

    Previous attempts to capture atmospheric CO2 by algal blooming were stalled by ocean viruses, zooplankton feeding, and/or bacterial decomposition of surface blooms, re-releasing captured CO2 instead of exporting it to seafloor. CCS fossil energy coupling could bypass algal bloom limits—enabling capture of 10 GtC/yr atmospheric CO2 by selective emiliania huxleyi (EHUX) blooming in mid-latitude open oceans, far from coastal waters and polar seas. This could enable a 500 GtC drawdown, 350 ppm restoration by 2050, 280 ppm CO2 by 2075, and ocean pH 8.2. White EHUX blooms could also reflect sunlight back into outer space and seed extra ocean cloud cover, via DMS release, to raise albedo 1.8%—restoring preindustrial temperature (ΔT = 0°C) by 2030. Open oceans would avoid post-bloom anoxia, exclusively a coastal water phenomenon. The EHUX calcification reaction initially sources CO2, but net sinking prevails in follow-up equilibration reactions. Heavier-than-water EHUX sink captured CO2 to the sea floor before surface decomposition occurs. Seeding EHUX high on their nonlinear growth curve could accelerate short-cycle secondary open-ocean blooming—overwhelming mid-latitude viruses, zooplankton, and competition from other algae. Mid-latitude "ocean deserts" exhibit low viral, zooplankton, and bacterial counts. Thermocline prevents nutrient upwelling that would otherwise promote competing algae. Adding nitrogen nutrient would foster exclusive EHUX blooming. Elevated EHUX seed levels could arise from sealed, pH-buffered, floating, seed-production bioreactors infused with 10% CO2 from carbon feedstock supplied by inland CCS fossil power plants capturing 90% of emissions as liquid CO2. Deep-water SPAR platforms extract natural gas from beneath the sea floor. On-platform Haber and pH processing could convert extracted CH4 to buffered NH4+ nutrient, enabling ≥0.7 GtC/yr of bioreactor seed production and 10 GtC/yr of amplified secondary open-ocean CO2 capture—making CCS

  13. Seasonal and inter-annual variability of the phytoplankton communities in an upwelling area of the Alborán Sea (SW Mediterranean Sea

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    Jesús M. Mercado

    2005-12-01

    Full Text Available Temporal variability (seasonal and inter-annual in the assembly of phytoplankton communities from the northern Alborán Sea was investigated. For this purpose, the taxonomic composition of the micro- and nano-phytoplankton communities at three fixed stations was determined every three months from 1994 to 2002. A total of 357 different taxa were identified. Most of them (about 54% were diatom species belonging to 57 genera. Dinoflagellates and coccolitophorids accounted for 118 and 30 taxa respectively. Two time periods could be differentiated with respect to the cell abundance. Thus, the mean abundance from 1994 to 1999 was 338 cell ml-1 and it dropped to about 60 cell ml-1 during the period 2000-2002. Diatoms and un-identified small flagellates dominated the communities during this first period, although a significant increase in the abundance of coccolitophorids occurred after 1997. Pseudo-nitzschia, Leptocylindrus and Chaetoceros were the dominant genera. In contrast, the coccolitophorids Emiliania huxleyi and Gephyrocapsa spp. quantitatively dominated the communities from 2000 to 2002. These shifts in the community assembly were assessed by performing a sample-oriented stepwise discriminant analysis (SDA. The analysis separated the samples into three year-groups, with great inter-annual variability. In contrast, the SDA did not find any seasonal sucessional pattern. In spite of this result, chlorophyll a and cell abundance tended to be higher in the spring period, which has been described for the whole Alborán basin. The nutrient concentrations in the 75 m upper seawater layer had inter-annual fluctuations. Thus, NO3-+NO2-, PO4-3 and Si(OH4 concentrations decreased significantly in 1997-1998. Additionally, lower Si(OH4 concentrations and Si:P molar ratios were obtained in 2000. These results suggest that the inter-annual shifts in the phytoplankton taxonomic composition were due to alterations in the nutrient regime. In this paper we

  14. Late Pleistocene Age Model for Site U1460, Perth Basin, SW Australian Shelf: Implications for Leeuwin Current History

    Science.gov (United States)

    Christensen, B. A.; Takayanagi, H.; Petrick, B.; Ishiwa, T.; Henderiks, J.; Groeneveld, J.; Mamo, B. L.; De Vleeschouwer, D.; Auer, G.; Deik, H.; Fulthorpe, C.; Gallagher, S. J.; McHugh, C.; Reuning, L.; Yokoyama, Y.

    2017-12-01

    The Leeuwin Current (LC) exerts an important control on modern Australian climate, but its onset is not well defined. The LC is the only southward flowing eastern boundary current. Driven by a pressure gradient set up in the Indonesian Throughflow, its warm waters support reefs to 29°S. It is seasonally controlled south of the Western Cape. Determination of the onset of the LC was a major objective of IODP Expedition 356. Expedition 356 drilling on the western Australian margin provides an opportunity to explore depositional patterns and timing in the region influenced by the current. Site U1460 was drilled in 214.5 m w.d. (Gallagher et al., 2017). Integrated calcareous nannofossil and planktonic foraminiferal biostratigraphy places the upper 86.5 m firmly within the late Pleistocene. However, the glacial- interglacial stratigraphy is uncertain because of the complexity of this shelfal depositional environment. Here we present a likely late Pleistocene stratigraphy based on integrated geochemical and paleontological datasets. A benthic foraminifer (Uvigerina peregrina) stable isotope record provides the foundation for the age model and the data are supported by SST estimates based on Tex86 and alkenones. Our age model places MIS 16 between 104 and 99 m-CSF-A, followed by an expanded MIS 15 section (99 - 50 m-CSF-A). We correlate the interval from 50 - 5 m-CSF-A with MIS 14 to MIS 8, with the largest magnitude glacial events (MIS 12, MIS 6) either condensed or represented as depositional hiatuses. A Recent 14C date at 0.34 mbsf constrains the interval from 2 - 0.5 m-CSF-A to MIS 4-3, which is in good agreement with the base of common Emiliania huxleyi (0.09 Ma) at 2.13 m-CSF-A. Thus MIS 5 is equivalent to the interval from 5 to 2 m-CSF-A. The expanded MIS 15 section follows a geometric change from slope to prograding shelf. It is associated with a shift to infaunal benthic foraminiferal assemblages, abundant sponge spicules, and a reduction in CaCO3%, suggesting

  15. Aerosolization, Chemical Characterization, Hygroscopicity and Ice Formation of Marine Biogenic Particles

    Science.gov (United States)

    Alpert, P. A.; Radway, J.; Kilthau, W.; Bothe, D.; Knopf, D. A.; Aller, J. Y.

    2013-12-01

    The oceans cover the majority of the earth's surface, host nearly half the total global primary productivity and are a major source of atmospheric aerosol particles. However, effects of biological activity on sea spray generation and composition, and subsequent cloud formation are not well understood. Our goal is to elucidate these effects which will be particularly important over nutrient rich seas, where microorganisms can reach concentrations of 10^9 per mL and along with transparent exopolymer particles (TEP) can become aerosolized. Here we report the results of mesocosm experiments in which bubbles were generated by two methods, either recirculating impinging water jets or glass frits, in natural or artificial seawater containing bacteria and unialgal cultures of three representative phytoplankton species, Thalassiosira pseudonana, Emiliania huxleyi, and Nannochloris atomus. Over time we followed the size distribution of aerosolized particles as well as their hygroscopicity, heterogeneous ice nucleation potential, and individual physical-chemical characteristics. Numbers of cells and the mass of dissolved and particulate organic carbon (DOC, POC), TEP (which includes polysaccharide-containing microgels and nanogels >0.4 μm in diameter) were determined in the bulk water, the surface microlayer, and aerosolized material. Aerosolized particles were also impacted onto substrates for ice nucleation and water uptake experiments, elemental analysis using computer controlled scanning electron microscopy and energy dispersive analysis of X-rays (CCSEM/EDX), and determination of carbon bonding with scanning transmission X-ray microscopy and near-edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS). Regardless of bubble generation method, the overall concentration of aerosol particles, TEP, POC and DOC increased as concentrations of bacterial and phytoplankton cells increased, stabilized, and subsequently declined. Particles cloud formation and potential

  16. Geochemical characteristics of Holocene laminated sapropel (unit II) and underlying lacustrine unit III in the Black Sea

    Science.gov (United States)

    Dean, Walter E.; Arthur, Michael A.

    2011-01-01

    eg 1 of the 1988 R/V Knorr expeditions to the Black Sea recovered 90 gravity and box cores. The longest recovery by gravity cores was about 3 meters, with an average of about 2.5 meters, recovering all of the Holocene and upper Pleistocene sections in the Black Sea. During the latest Pleistocene glaciation, sea level dropped below the 35-meters-deep Bosporus outlet sill of the Black Sea. Therefore throughout most of its history the Black Sea was a lake, and most of its sediments are lacustrine. The oldest sediments recovered (older than 8,000 calendar years) consist of massive to coarsely banded lacustrine calcareous clay designated as lithologic Unit III, generally containing less than 1 percent organic carbon (OC). The base of overlying Unit II marks the first incursion of Mediterranean seawater into the Black Sea, and the onset of bottom-water anoxia about 7,900 calendar years. Unit II contains as much as 15 percent OC in cores from the deepest part of the Black Sea (2,200 meters). The calcium carbonate (CaCO3) remains of the coccolith Emiliania huxleyi form the distinctive white laminae of overlying Unit I. The composition of Unit III and Unit II sediments are quite different, reflecting different terrigenous clastic sources and increased contributions from hydrogenous and biogenic components in anoxic Unit II sapropel. In Unit II, positive covariance between OC and three trace elements commonly concentrated in OC-rich sediments where sulfate reduction has occurred (molybdenum, nickel, and vanadium) and a nutrient (phosphorus) suggest a large marine source for these elements although nickel and vanadium also have a large terrigenous clastic source. The marine sources may be biogenic or hydrogenous. A large biogenic source is also suggested for copper and cobalt. Because abundant pyrite forms in the water column and sediments of the Black Sea, we expected to find a large hydrogenous iron component, but a strong covariance of iron with aluminum suggests that the

  17. A middle Pleistocene eastern Mediterranean fish refuge: the Tsampika Bay (Rhodes, Greece)

    Science.gov (United States)

    Agiadi, K.; Koskeridou, E.; Moissette, P.; Lopez-Otalvaro, G. E.; Quillévéré, F.; Cornée, J. J.

    2012-04-01

    Extensive sampling of the Tsampika marly diatomites reveals the presence of at least three very important fish species, Bregmaceros sp., Sygnathus acus and Spratteloides sp.. Previous records of Bregmaceros sp. in the Mediterranean have suggested that this characteristic Pliocene warm-water circumglobal pelagic fish disappeared from the Mediterranean basin due to the climatic deterioration, after the Gelasian age1,2,3,4. The Tsampika fish-bearing deposits, mainly marly diatomites, are younger than 268 Ka, based on the occurrence of Emiliania huxleyi. Consequently, this is so far the youngest record of Bregmaceros sp. in the Mediterranean, suggesting that typical Pliocene fish may have found refuge in selected localities, such as Tsampika Bay, at least until the Ionian. Evidence for its presence in the Mediterranean basin today is ambiguous. Isolated records of Bregmaceros atlanticus place it in the Sicily Strait5, and off the Israeli and south Turkish coasts6. Although it appears more likely that Bregmaceros atlanticus has been introduced to the modern Mediterranean from the Red Sea, through the Suez Canal, the possibility that it is part of a small population native to the Mediterranean can not be excluded based on present-day data6. Indeed the late Pleistocene Mediterranean fish record is obsolete, due to the lack of appropriate sampling on this subject. Furthermore, the majority of Pleistocene Bregmaceros samples pertain to otoliths, which cannot be unambiguously identified on the species level. As a result, the present findings pose the considerable possibility that the Pleistocene Bregmaceros records belong to two species, B. albyi, the well known post-Messinian Mediterranean fish, and B. atlanticus, which may have invaded the Mediterranean Sea from Gibraltar along with several other warm-water taxa during recurring interglacial periods. The specific identification of the Tsampika fish will undoubtedly shed light to this possibility, and enhance our knowledge

  18. A Comprehensive Modeling Approach Towards Understanding and Prediction of the Alaskan Coastal System Response to Changes in an Ice-diminished Arctic

    Science.gov (United States)

    2009-09-30

    ammonifying and nitrifying bacteria ; six groups of phytoplankton (diatoms, dinoflagellates, coccolithophores, colonial prymnesiophytes, microflagellates...and diazotrophs ), for which cell counts were made at the species level during 2002, 2003, and 2004 cruises of the Polar Star, Healy, Mirai, Louis St...groups of backscattering coccolithophores and diazotrophs , compared to the other phytoplankton groups. Finally, food web closures is effected in the

  19. Increasing coccolith calcification during CO2 rise of the penultimate deglaciation (Termination II)

    DEFF Research Database (Denmark)

    Meier, K. J. S.; Berger, C.; Kinkel, Hanno

    2014-01-01

    during Termination II. This is partly due to an assemblage shift towards larger and heavier calcifying morphotypes, but mainly an effect of increasing coccolithophore calcification. This increase is exactly mirroring the rise in atmospheric CO2, contradicting previous findings from Termination I......Glacial to interglacial environmental changes have a strong impact on coccolithophore assemblage composition. At the same time, glacial terminations are characterised by an increase in atmospheric CO2 concentration. In order to determine how these two processes influence the calcite production...... for the coccolithophore calcification increase during atmospheric CO2 rise. Our results illustrate that even during rising atmospheric CO2 the conditions of the seawater carbonate system can be favourable for coccolithophore calcification. The total CaCO3 production of a coccolithophore assemblage under increasing CO2...

  20. Evidence for a multi-species coccolith volume change over the past two centuries: understanding a potential ocean acidification response

    Directory of Open Access Journals (Sweden)

    P. R. Halloran

    2008-12-01

    Full Text Available Major questions surround the species-specific nature of coccolithophore calcification in response to rising atmospheric CO2 levels. Here we present CaCO3 particle volume distribution data from the coccolith size-fraction of a rapidly accumulating North Atlantic sediment core. Without direct volume measurements on coccoliths produced by individual coccolithophore species, and knowledge of organic, as well as inorganic carbon production, it is not possible to state conclusively the coccolithophore calcification change at this site. However, by analysing the size distribution of CaCO3 particles in the less than 10 μm sediment fraction, we demonstrate a changing particle volume since the late 20th Century consistent with an increase in the mass of coccoliths produced by the larger coccolithophore species, and potentially a decrease in mass of coccoliths produced by the smaller species, present at this location. This finding has significant implications for the realistic representation of an assemblage-wide coccolithophore CO2-calcification response in numerical models.

  1. Investigating Coccolithophorid Biology in the Sedimentary Laboratory

    Science.gov (United States)

    McClelland, H. L. O.; Barbarin, N.; Beaufort, L.; Hermoso, M.; Rickaby, R. E. M.

    2014-12-01

    Coccolithophores are the ocean's dominant calcifying phytoplankton; they play an important, but poorly understood, role in long-term biogeochemical climatic feedbacks. Calcite producing marine organisms are likely to calcify less in a future world where higher carbon dioxide concentrations will lead to ocean acidification (OA), but coccolithophores may be the exception. In coccolithophores calcification occurs in an intracellular vesicle, where the site of calcite precipitation is buffered from the external environment and is subject to a uniquely high degree of biological control. Culture manipulation experiments mimicking the effects of OA in the laboratory have yielded empirical evidence for phenotypic plasticity, competition and evolutionary adaptation in asexual populations. However, the extent to which these results are representative of natural populations, and of the response over timescales of greater than a few hundred generations, is unclear. Here we describe a new sediment-based proxy for the PIC:POC (particulate inorganic to particulate organic carbon ratio) of coccolithophore biomass, which is equivalent to the fractional energy contribution to calcification at constant pH, and a biologically meaningful measure of the organism's tendency to calcify. Employing the geological record as a laboratory, we apply this proxy to sedimentary material from the southern Pacific Ocean to investigate the integrated response of real ancient coccolithophore populations to environmental change over many thousands of years. Our results provide a new perspective on phenotypic change in real populations of coccolithophorid algae over long timescales.

  2. Surface water dynamics in the Reykjanes Ridge area during the Holocene as revealed by coccolith assemblages

    NARCIS (Netherlands)

    Balestra, B.; Ziveri, P.; Baumann, K. H.; Troelstra, S.R.; Monechi, S.

    2010-01-01

    The calcareous nannofossil assemblages from sediment core DS97-2P from the Reykjanes Ridge have been investigated to document oceanographic changes in surface water during the Holocene. The recorded variations in coccolithophore species assemblages and accumulation rates indicate that the region was

  3. Productivity modes in the Mediterranean Sea during Dansgaard–Oeschger (20,000–70,000 yr ago) oscillations

    NARCIS (Netherlands)

    Incarbona, A.; Sprovieri, M.; di Stefano, A.; di Stefano, E.; Salvagio Manta, D.; Pelosi, N.; d’ Alcalà, M.R.; Sprovieri, R.; Ziveri, P.

    2013-01-01

    The study of planktonic organisms during abrupt climatic variations of the last glacial period (Dansgaard-Oeschger oscillations, D-O) may reveal important insights on climatic, oceanographic and biological interactions. Here we present planktic foraminifera and coccolithophore data collected at the

  4. Modelling an alkenone-like proxy record in the NW African upwelling

    Directory of Open Access Journals (Sweden)

    X. Giraud

    2006-01-01

    Full Text Available A regional biogeochemical model is applied to the NW African coastal upwelling between 19° N and 27° N to investigate how a water temperature proxy, alkenones, are produced at the sea surface and recorded in the slope sediments. The biogeochemical model has two phytoplankton groups: an alkenone producer group, considered to be coccolithophores, and a group comprising other phytoplankton. The Regional Ocean Modelling System (ROMS is used to simulate the ocean circulation and takes advantage of the Adaptive Grid Refinement in Fortran (AGRIF package to set up an embedded griding system. In the simulations the alkenone temperature records in the sediments are between 1.1 and 2.3°C colder than the annual mean SSTs. Despite the seasonality of the coccolithophore production, this temperature difference is not mainly due to a seasonal bias, nor to the lateral advection of phytoplankton and phytodetritus seaward from the cold near-shore waters, but to the production depth of the coccolithophores. If coretop alkenone temperatures are effectively recording the annual mean SSTs, the amount of alkenone produced must vary among the coccolithophores in the water column and depend on physiological factors (e.g. growth rate, nutrient stress.

  5. Evaluation of the CaCO3 dissolution proxies in sediment cores from above the lysocline

    Digital Repository Service at National Institute of Oceanography (India)

    Naik, S.S.; Naidu, P.D.

    and the total CaCO sub(3) content shows that the total carbonate variations are controlled by the finer fraction composed of juvenile foraminifera, foraminifera fragments and coccolithophores. This further confirms the observed variations of CaCO sub(3) content...

  6. Effects of Ocean Acidification on the Life Cycle and Fitness of the Mysid Shrimp Americamysis Bahia

    Science.gov (United States)

    Most concern about effects of CO2-induced ocean acidification focuses on mollusks, corals, and coccolithophores because skeletal and shell formation by these organisms is sensitive to the solubility of calcium minerals. However, many other marine organisms are likely affected by...

  7. Ocean acidification reduces growth and calcification in a marine dinoflagellate

    NARCIS (Netherlands)

    Van de Waal, D.B.; John, U.; Ziveri, P.; Reichart, G.J.; Hoins, M.; Sluijs, A.; Rost, B.

    2013-01-01

    Ocean acidification is considered a major threat to marine ecosystems and may particularly affect calcifying organisms such as corals, foraminifera and coccolithophores. Here we investigate the impact of elevated pCO2 and lowered pH on growth and calcification in the common calcareous dinoflagellate

  8. Effects of Seawater Acidification on the Liffe Cycle and Fitness of Opossum Shrimp Population

    Science.gov (United States)

    Much of the current concern about ecological effects of ocean acidification focuses on molluscs and coccolithophores because of their importance in the global calcium cycle. However, many other marine organisms are likely to be affected by acidification because of their known se...

  9. Effects of Seawater Acidification on the Life Cycle and fitness of Opossum Shrimp Populations

    Science.gov (United States)

    Much of the current concern about ecological effects of ocean acidification focuses on molluscs and coccolithophores because of their importance in the global calcium cycle. However, many other marine organisms are likely to be affected by acidification because of their known ph...

  10. Production, oxygen respiration rates, and sinking velocity of copepod fecal pellets: Direct measurements of ballasting by opal and calcite

    DEFF Research Database (Denmark)

    Ploug, H.; Iversen, M.H.; Koski, Marja

    2008-01-01

    sp., T. weissflogii, and E. huxleyi, respectively. The average carbon-specific respiration rate was 0.15 d(-1) independent on diet (range: 0.08-0.21 d(-1)). Because of ballasting of opal and calcite, sinking velocities were significantly higher for pellets produced on T. weissflogii (322 +/- 169 m d...

  11. Inter-annual Variability in Global Suspended Particulate Inorganic Carbon Inventory Using Space-based Measurements

    Science.gov (United States)

    Hopkins, J.; Balch, W. M.; Henson, S.; Poulton, A. J.; Drapeau, D.; Bowler, B.; Lubelczyk, L.

    2016-02-01

    Coccolithophores, the single celled phytoplankton that produce an outer covering of calcium carbonate coccoliths, are considered to be the greatest contributors to the global oceanic particulate inorganic carbon (PIC) pool. The reflective coccoliths scatter light back out from the ocean surface, enabling PIC concentration to be quantitatively estimated from ocean color satellites. Here we use datasets of AQUA MODIS PIC concentration from 2003-2014 (using the recently-revised PIC algorithm), as well as statistics on coccolithophore vertical distribution derived from cruises throughout the world ocean, to estimate the average global (surface and integrated) PIC standing stock and its associated inter-annual variability. In addition, we divide the global ocean into Longhurst biogeochemical provinces, update the PIC biomass statistics and identify those regions that have the greatest inter-annual variability and thus may exert the greatest influence on global PIC standing stock and the alkalinity pump.

  12. The Effects of Climate Variability on Phytoplankton Composition in the Equatorial Pacific Ocean using a Model and a Satellite-Derived Approach

    Science.gov (United States)

    Rousseaux, C. S.; Gregg, W. W.

    2012-01-01

    Compared the interannual variation in diatoms, cyanobacteria, coccolithophores and chlorophytes from the NASA Ocean Biogeochemical Model with those derived from satellite data (Hirata et al. 2011) between 1998 and 2006 in the Equatorial Pacific. Using NOBM, La Ni a events were characterized by an increase in diatoms (correlation with MEI, r=-0.81, Pphytoplankton community in response to climate variability. However, satellite-derived phytoplankton groups were all negatively correlated with climate variability (r ranged from -0.39 for diatoms to -0.64 for coccolithophores, Pphytoplankton groups except diatoms than NOBM. However, the different responses of phytoplankton to intense interannual events in the Equatorial Pacific raises questions about the representation of phytoplankton dynamics in models and algorithms: is a phytoplankton community shift as in the model or an across-the-board change in abundances of all phytoplankton as in the satellite-derived approach.

  13. Pleurochrysis pseudoroscoffensis (Prymnesiophyceae) blooms on the surface of the Salton Sea, California

    Science.gov (United States)

    Reifel, K.M.; McCoy, M.P.; Tiffany, M.A.; Rocke, T.E.; Trees, C.C.; Barlow, S.B.; Faulkner, D.J.; Hurlbert, S.H.

    2001-01-01

    Dense populations of the coccolithophore Pleurochrysis pseudoroscoffensis were found in surface films at several locations around the Salton Sea in February-August, 1999. An unidentified coccolithophorid was also found in low densities in earlier studies of the lake (1955-1956). To our knowledge, this is the first record of this widespread marine species in any lake. Samples taken from surface films typically contained high densities of one or two other phytoplankton species as well as high densities of the coccolithophore. Presence or absence of specific algal pigments was used to validate direct cell counts. In a preliminary screen using a brine shrimp lethality assay, samples showed moderate activity. Extracts were then submitted to a mouse bioassay, and no toxic activity was observed. These results indicate that blooms of P. pseudoroscoffensis are probably not toxic to vertebrates and do not contribute to the various mortality events of birds and fish that occur in the Salton Sea.

  14. Orbital forcing on marine organic and carbonate production in the Indo-Pacific during the last 1.7 Myrs

    Science.gov (United States)

    Beaufort, L.; Bolton, C. T.; Mazur, J. C.; Gally, Y.

    2017-12-01

    The Western Pacific Warm Pool (WPWP) is a place of intense energy storage and redistribution … It is climatically relatively stable with, for example, little seasonality in sea surface temperature (SST). However, significant changes occur in the vertical structure of the upper ocean related to El Nino Southern Oscillation dynamics. These changes significantly impact the phytoplankton communities that are adapted to specific conditions in different layers of the photic zone, and are precisely recorded in the sediments by microfossils such as those produced by coccolithophores. Core MD97-2540 was retrieved on the Eauripik rise in the WPWP and covers, in 37 metres, a time interval spanning the last 1.7 million years (Myrs). Two samples were prepared (settling slide) every 5 cm. The entire coccolith assemblage was counted and identified automatically in each sample using the software SYRACO. Morphometric characteristics (length, thickness, mass…) were measured on every coccolith. Primary productivity (PP) was estimated using a transfer function based on the percentage of the species Florisphaera profunda. Changes in mass (M) of the dominant coccolithophore group, the Noelarhabdaceae (including Emilianiaand Gephyrocapsa), were studied. We also estimated the coccolithophore carbonate export production (CCEP). Those 3 parameters (PP, M and CCEP) show a significant imprint of precession and eccentricity of the Earth's orbit. In contrast to SST and planktic foraminiferal oxygen isotopes measured on the same samples, the coccolithophore parameters exhibit significant 400 kyr cyclicity, and the 100 kyr cycle is present prior to its appearance in the SST and oxygen isotope records 0.9 Myrs ago. This indicates direct forcing by insolation and seasonality on the WPWP, independent of global climatic variations. A discussion of the relationship between the Indian Monsoon and ENSO on orbital and longer timescales is enabled via comparisons with PP and CCEP measured at a similar

  15. Calcification response of a key phytoplankton family to millennial-scale environmental change.

    Science.gov (United States)

    McClelland, H L O; Barbarin, N; Beaufort, L; Hermoso, M; Ferretti, P; Greaves, M; Rickaby, R E M

    2016-09-28

    Coccolithophores are single-celled photosynthesizing marine algae, responsible for half of the calcification in the surface ocean, and exert a strong influence on the distribution of carbon among global reservoirs, and thus Earth's climate. Calcification in the surface ocean decreases the buffering capacity of seawater for CO 2 , whilst photosynthetic carbon fixation has the opposite effect. Experiments in culture have suggested that coccolithophore calcification decreases under high CO 2 concentrations ([CO 2 (aq)]) constituting a negative feedback. However, the extent to which these results are representative of natural populations, and of the response over more than a few hundred generations is unclear. Here we describe and apply a novel rationale for size-normalizing the mass of the calcite plates produced by the most abundant family of coccolithophores, the Noëlaerhabdaceae. On average, ancient populations subjected to coupled gradual increases in [CO 2 (aq)] and temperature over a few million generations in a natural environment become relatively more highly calcified, implying a positive climatic feedback. We hypothesize that this is the result of selection manifest in natural populations over millennial timescales, so has necessarily eluded laboratory experiments.

  16. Monsoonal and fertility contols on recent marginal sea and continental shelf coccolith assemblages from the western Pacific and northern Indian Oceans

    Digital Repository Service at National Institute of Oceanography (India)

    Houghton, S.D.; Guptha, M.V.S.

    Gill, 1973). These nutrient-enriched surface waters support large blooms of the diatom Rhizo- solenia (Nair et al., 1989). High fluxes of carbonate, mainly coccolithophorids with some foraminifera, are associated with the monsoons. High levels.... In the low-latitude Pacific Ocean, high abun- dances of E. huxleyi (>40%) are generally re- stricted to assemblages beneath waters of low to medium fertility; these areas include the East Pacific Rise (near the Galapogos Islands), and below the central...

  17. Distribution of planktonic biogenic carbonate organisms in the Southern Ocean south of Australia: a baseline for ocean acidification impact assessment

    Science.gov (United States)

    Trull, Thomas W.; Passmore, Abraham; Davies, Diana M.; Smit, Tim; Berry, Kate; Tilbrook, Bronte

    2018-01-01

    The Southern Ocean provides a vital service by absorbing about one-sixth of humankind's annual emissions of CO2. This comes with a cost - an increase in ocean acidity that is expected to have negative impacts on ocean ecosystems. The reduced ability of phytoplankton and zooplankton to precipitate carbonate shells is a clearly identified risk. The impact depends on the significance of these organisms in Southern Ocean ecosystems, but there is very little information on their abundance or distribution. To quantify their presence, we used coulometric measurement of particulate inorganic carbonate (PIC) on particles filtered from surface seawater into two size fractions: 50-1000 µm to capture foraminifera (the most important biogenic carbonate-forming zooplankton) and 1-50 µm to capture coccolithophores (the most important biogenic carbonate-forming phytoplankton). Ancillary measurements of biogenic silica (BSi) and particulate organic carbon (POC) provided context, as estimates of the biomass of diatoms (the highest biomass phytoplankton in polar waters) and total microbial biomass, respectively. Results for nine transects from Australia to Antarctica in 2008-2015 showed low levels of PIC compared to Northern Hemisphere polar waters. Coccolithophores slightly exceeded the biomass of diatoms in subantarctic waters, but their abundance decreased more than 30-fold poleward, while diatom abundances increased, so that on a molar basis PIC was only 1 % of BSi in Antarctic waters. This limited importance of coccolithophores in the Southern Ocean is further emphasized in terms of their associated POC, representing less than 1 % of total POC in Antarctic waters and less than 10 % in subantarctic waters. NASA satellite ocean-colour-based PIC estimates were in reasonable agreement with the shipboard results in subantarctic waters but greatly overestimated PIC in Antarctic waters. Contrastingly, the NASA Ocean Biogeochemical Model (NOBM) shows coccolithophores as overly

  18. Distribution of planktonic biogenic carbonate organisms in the Southern Ocean south of Australia: a baseline for ocean acidification impact assessment

    Directory of Open Access Journals (Sweden)

    T. W. Trull

    2018-01-01

    Full Text Available The Southern Ocean provides a vital service by absorbing about one-sixth of humankind's annual emissions of CO2. This comes with a cost – an increase in ocean acidity that is expected to have negative impacts on ocean ecosystems. The reduced ability of phytoplankton and zooplankton to precipitate carbonate shells is a clearly identified risk. The impact depends on the significance of these organisms in Southern Ocean ecosystems, but there is very little information on their abundance or distribution. To quantify their presence, we used coulometric measurement of particulate inorganic carbonate (PIC on particles filtered from surface seawater into two size fractions: 50–1000 µm to capture foraminifera (the most important biogenic carbonate-forming zooplankton and 1–50 µm to capture coccolithophores (the most important biogenic carbonate-forming phytoplankton. Ancillary measurements of biogenic silica (BSi and particulate organic carbon (POC provided context, as estimates of the biomass of diatoms (the highest biomass phytoplankton in polar waters and total microbial biomass, respectively. Results for nine transects from Australia to Antarctica in 2008–2015 showed low levels of PIC compared to Northern Hemisphere polar waters. Coccolithophores slightly exceeded the biomass of diatoms in subantarctic waters, but their abundance decreased more than 30-fold poleward, while diatom abundances increased, so that on a molar basis PIC was only 1 % of BSi in Antarctic waters. This limited importance of coccolithophores in the Southern Ocean is further emphasized in terms of their associated POC, representing less than 1 % of total POC in Antarctic waters and less than 10 % in subantarctic waters. NASA satellite ocean-colour-based PIC estimates were in reasonable agreement with the shipboard results in subantarctic waters but greatly overestimated PIC in Antarctic waters. Contrastingly, the NASA Ocean Biogeochemical Model (NOBM shows

  19. The role of phytoplankton dynamics in the seasonal and interannual variability of carbon in the subpolar North Atlantic – a modeling study

    Directory of Open Access Journals (Sweden)

    S. R. Signorini

    2012-05-01

    Full Text Available We developed an ecosystem/biogeochemical model system, which includes multiple phytoplankton functional groups and carbon cycle dynamics, and applied it to investigate physical-biological interactions in Icelandic waters. Satellite and in situ data were used to evaluate the model. Surface seasonal cycle amplitudes and biases of key parameters (DIC, TA, pCO2, air-sea CO2 flux, and nutrients are significantly improved when compared to surface observations by prescribing deep water values and trends, based on available data. The seasonality of the coccolithophore and "other phytoplankton" (diatoms and dinoflagellates blooms is in general agreement with satellite ocean color products. Nutrient supply, biomass and calcite concentrations are modulated by light and mixed layer depth seasonal cycles. Diatoms are the most abundant phytoplankton, with a large bloom in early spring and a secondary bloom in fall. The diatom bloom is followed by blooms of dinoflagellates and coccolithophores. The effect of biological changes on the seasonal variability of the surface ocean pCO2 is nearly twice the temperature effect, in agreement with previous studies. The inclusion of multiple phytoplankton functional groups in the model played a major role in the accurate representation of CO2 uptake by biology. For instance, at the peak of the bloom, the exclusion of coccolithophores causes an increase in alkalinity of up to 4 μmol kg−1 with a corresponding increase in DIC of up to 16 μmol kg−1. During the peak of the bloom in summer, the net effect of the absence of the coccolithophores bloom is an increase in pCO2 of more than 20 μatm and a reduction of atmospheric CO2 uptake of more than 6 mmol m−2 d−1. On average, the impact of coccolithophores is an increase of air-sea CO2 flux of about 27%. Considering the areal

  20. The Role of Phytoplankton Dynamics in the Seasonal and Interannual Variability of Carbon in the Subpolar North Atlantic - a Modeling Study

    Science.gov (United States)

    Signorini, Sergio; Hakkinen, Sirpa; Gudmundsson, K.; Olsen, A.; Omar, A. M.; Olafsson, J.; Reverdin, G.; Henson, S. A.; McClain, C. R.; Worthen, D. L.

    2014-01-01

    We developed an ecosystem/biogeochemical model system, which includes multiple phytoplankton functional groups and carbon cycle dynamics, and applied it to investigate physical-biological interactions in Icelandic waters. Satellite and in situ data were used to evaluate the model. Surface seasonal cycle amplitudes and biases of key parameters (DIC, TA, pCO2, air-sea CO2 flux, and nutrients) are significantly improved when compared to surface observations by prescribing deep water values and trends, based on available data. The seasonality of the coccolithophore and "other phytoplankton" (diatoms and dinoflagellates) blooms is in general agreement with satellite ocean color products. Nutrient supply, biomass and calcite concentrations are modulated by light and mixed layer depth seasonal cycles. Diatoms are the most abundant phytoplankton, with a large bloom in early spring and a secondary bloom in fall. The diatom bloom is followed by blooms of dinoflagellates and coccolithophores. The effect of biological changes on the seasonal variability of the surface ocean pCO2 is nearly twice the temperature effect, in agreement with previous studies. The inclusion of multiple phytoplankton functional groups in the model played a major role in the accurate representation of CO2 uptake by biology. For instance, at the peak of the bloom, the exclusion of coccolithophores causes an increase in alkalinity of up to 4 µmol kg(sup -1) with a corresponding increase in DIC of up to 16 µmol kg(sup -1). During the peak of the bloom in summer, the net effect of the absence of the coccolithophores bloom is an increase in pCO2 of more than 20 µatm and a reduction of atmospheric CO2 uptake of more than 6 mmolm(sup -2) d(sup -1). On average, the impact of coccolithophores is an increase of air-sea CO2 flux of about 27 %. Considering the areal extent of the bloom from satellite images within the Irminger and Icelandic Basins, this reduction translates into an annual mean of nearly 1500

  1. A Conceptual Model for Projecting Coccolithophorid Growth, Calcification and Photosynthetic Carbon Fixation Rates in Response to Global Ocean Change

    Directory of Open Access Journals (Sweden)

    Natasha A. Gafar

    2018-01-01

    Full Text Available Temperature, light and carbonate chemistry all influence the growth, calcification and photosynthetic rates of coccolithophores to a similar degree. There have been multiple attempts to project the responses of coccolithophores to changes in carbonate chemistry, but the interaction with light and temperature remains elusive. Here we devise a simple conceptual model to derive a fit equation for coccolithophorid growth, photosynthetic and calcification rates in response to simultaneous changes in carbonate chemistry, temperature and light conditions. The fit equation is able to account for up to 88% of the variability in measured metabolic rates. Equation projections indicate that temperature, light and carbonate chemistry all have different modulating effects on both optimal growth conditions and the sensitivity of responses to extreme environmental conditions. Calculations suggest that a single extreme environmental condition (CO2, temperature, light will reduce maximum rates regardless of how optimal the other environmental conditions may be. Thus, while the response of coccolithophores to ocean change depends on multiple variables, the one which is least optimal will have the most impact on overall rates. Finally, responses to ocean change are usually reported in terms of cellular rates. However, changes in cellular rates can be a poor predictor for assessing changes in production at the community level. We therefore introduce a new metric, the calcium carbonate production potential (CCPP, which combines the independent effects of changes in growth rate and cellular calcium carbonate content to assess how environmental changes will impact coccolith production. Direct comparison of CO2 impacts on cellular CaCO3 production rates and CCPP shows that while the former is still at 45% of its pre-industrial capacity at 1,000 μatm, the latter is reduced to 10%.

  2. Coccolith calcite time capsules preserve a molecule-specific record of pCO2

    Science.gov (United States)

    McClelland, H. L. O.; Pearson, A.; Hermoso, M.; Wilkes, E.; Lee, R. B. Y.; Rickaby, R. E. M.

    2017-12-01

    Coccolithophores are single-celled phytoplankton that have contributed organic matter and calcite to marine sediments since the Late Triassic. The carbon isotopic compositions of both the calcite, and the organic matter, constitute valuable archives of information about the interaction between these organisms and the environments in which they lived. The isotopic composition of alkenone lipids, a recalcitrant component of coccolithophore organic carbon produced by a single family of coccolithophores, has been widely used to reconstruct pCO2 in the geological past. However, the robustness of this approach has remained controversial, due in part to the difficulties associated with reproducing pCO2 changes across periods of known pCO2 change, and uncertainties in relevant physiological variables such as growth rate and cell size. Meanwhile the calcite, produced in the form of plates called coccoliths, and which has had limited utility in paleoclimate reconstructions due to its large and variable departures from the isotopic composition of abiogenic calcite, has garnered increasing attention in recent years for the environmental and physiological information it contains. Here we show that polysaccharides preserved within the calcite crystal lattice of near monospecific fractions of fossil coccoliths constitute an ancient pristine source of organic carbon that unlike alkenones is unambiguously associated with the coccolith1. The isotopic composition of these polysaccharides, in tandem with that of the host coccolith calcite, and morphometrics from the same coccoliths2, can be used simultaneously constrain a recently published cellular carbon isotope flux model3, embedded in a more complex nutrient limitation model, in a powerful new approach to simultaneously predict cellular parameters and pCO2. We demonstrate the validity of this approach across a glacial / interglacial cycle. Lee, R. B. Y., et al,, Nat. Commun. 7, 13144 (2016). McClelland, H. L. O. et al. Sci. Rep. 6

  3. Distribution of calcifying and silicifying phytoplankton in relation to environmental and biogeochemical parameters during the late stages of the 2005 North East Atlantic Spring Bloom

    Directory of Open Access Journals (Sweden)

    K. Leblanc

    2009-10-01

    Full Text Available The late stage of the North East Atlantic (NEA spring bloom was investigated during June 2005 along a transect section from 45 to 66° N between 15 and 20° W in order to characterize the contribution of siliceous and calcareous phytoplankton groups and describe their distribution in relation to environmental factors. We measured several biogeochemical parameters such as nutrients, surface trace metals, algal pigments, biogenic silica (BSi, particulate inorganic carbon (PIC or calcium carbonate, particulate organic carbon, nitrogen and phosphorus (POC, PON and POP, respectively, as well as transparent exopolymer particles (TEP. Results were compared with other studies undertaken in this area since the JGOFS NABE program. Characteristics of the spring bloom generally agreed well with the accepted scenario for the development of the autotrophic community. The NEA seasonal diatom bloom was in the late stages when we sampled the area and diatoms were constrained to the northern part of our transect, over the Icelandic Basin (IB and Icelandic Shelf (IS. Coccolithophores dominated the phytoplankton community, with a large distribution over the Rockall-Hatton Plateau (RHP and IB. The Porcupine Abyssal Plain (PAP region at the southern end of our transect was the region with the lowest biomass, as demonstrated by very low Chla concentrations and a community dominated by picophytoplankton. Early depletion of dissolved silicic acid (DSi and increased stratification of the surface layer most likely triggered the end of the diatom bloom, leading to coccolithophore dominance. The chronic Si deficiency observed in the NEA could be linked to moderate Fe limitation, which increases the efficiency of the Si pump. TEP closely mirrored the distribution of both biogenic silica at depth and prymnesiophytes in the surface layer suggesting the sedimentation of the diatom bloom in the form of aggregates, but the relative contribution of diatoms and

  4. Phytoplankton across Tropical and Subtropical Regions of the Atlantic, Indian and Pacific Oceans.

    Science.gov (United States)

    Estrada, Marta; Delgado, Maximino; Blasco, Dolors; Latasa, Mikel; Cabello, Ana María; Benítez-Barrios, Verónica; Fraile-Nuez, Eugenio; Mozetič, Patricija; Vidal, Montserrat

    2016-01-01

    We examine the large-scale distribution patterns of the nano- and microphytoplankton collected from 145 oceanic stations, at 3 m depth, the 20% light level and the depth of the subsurface chlorophyll maximum, during the Malaspina-2010 Expedition (December 2010-July 2011), which covered 15 biogeographical provinces across the Atlantic, Indian and Pacific oceans, between 35°N and 40°S. In general, the water column was stratified, the surface layers were nutrient-poor and the nano- and microplankton (hereafter phytoplankton, for simplicity, although it included also heterotrophic protists) community was dominated by dinoflagellates, other flagellates and coccolithophores, while the contribution of diatoms was only important in zones with shallow nutriclines such as the equatorial upwelling regions. We applied a principal component analysis to the correlation matrix among the abundances (after logarithmic transform) of the 76 most frequent taxa to synthesize the information contained in the phytoplankton data set. The main trends of variability identified consisted of: 1) A contrast between the community composition of the upper and the lower parts of the euphotic zone, expressed respectively by positive or negative scores of the first principal component, which was positively correlated with taxa such as the dinoflagellates Oxytoxum minutum and Scrippsiella spp., and the coccolithophores Discosphaera tubifera and Syracosphaera pulchra (HOL and HET), and negatively correlated with taxa like Ophiaster hydroideus (coccolithophore) and several diatoms, 2) a general abundance gradient between phytoplankton-rich regions with high abundances of dinoflagellate, coccolithophore and ciliate taxa, and phytoplankton-poor regions (second principal component), 3) differences in dominant phytoplankton and ciliate taxa among the Atlantic, the Indian and the Pacific oceans (third principal component) and 4) the occurrence of a diatom-dominated assemblage (the fourth principal

  5. Galacturonomannan and Golgi-derived membrane linked to growth and shaping of biogenic calcite

    Science.gov (United States)

    Marsh, M. E.; Ridall, A. L.; Azadi, P.; Duke, P. J.

    2002-01-01

    The coccolithophores are valuable models for the design and synthesis of composite materials, because the cellular machinery controlling the nucleation, growth, and patterning of their calcitic scales (coccoliths) can be examined genetically. The coccoliths are formed within the Golgi complex and are the major CaCO(3) component in limestone sediments-particularly those of the Cretaceous period. In this study, we describe mutants lacking a sulfated galacturonomannan and show that this polysaccharide in conjunction with the Golgi-derived membrane is directly linked to the growth and shaping of coccolith calcite but not to the initial orientated nucleation of the mineral phase.

  6. Ventimolina stellata gen. et sp. nov. (Haptophyta, Papposphaeraceae) from warm water regions

    DEFF Research Database (Denmark)

    Thomsen, Helge Abildhauge; Østergaard, Jette B.; Cros, Lluïsa

    2015-01-01

    It has been known for some time that the distinctive polar weakly calcified coccolithophores are also present in samples from lower latitudes. While polar species may actually have a geographic range that vastly extends beyond the polar realms, it is often the case that the warm water regions...... contribute species that can be allocated to genera previously described based on polar material. We are currently in the process of formally dealing with the warm water species diversity affiliated with the family Papposphaeraceae. In this paper we describe a new genus and species Ventimolina stellata based...

  7. Phytoplankton across Tropical and Subtropical Regions of the Atlantic, Indian and Pacific Oceans

    Science.gov (United States)

    Estrada, Marta; Delgado, Maximino; Blasco, Dolors; Latasa, Mikel; Cabello, Ana María; Benítez-Barrios, Verónica; Fraile-Nuez, Eugenio; Mozetič, Patricija; Vidal, Montserrat

    2016-01-01

    We examine the large-scale distribution patterns of the nano- and microphytoplankton collected from 145 oceanic stations, at 3 m depth, the 20% light level and the depth of the subsurface chlorophyll maximum, during the Malaspina-2010 Expedition (December 2010-July 2011), which covered 15 biogeographical provinces across the Atlantic, Indian and Pacific oceans, between 35°N and 40°S. In general, the water column was stratified, the surface layers were nutrient-poor and the nano- and microplankton (hereafter phytoplankton, for simplicity, although it included also heterotrophic protists) community was dominated by dinoflagellates, other flagellates and coccolithophores, while the contribution of diatoms was only important in zones with shallow nutriclines such as the equatorial upwelling regions. We applied a principal component analysis to the correlation matrix among the abundances (after logarithmic transform) of the 76 most frequent taxa to synthesize the information contained in the phytoplankton data set. The main trends of variability identified consisted of: 1) A contrast between the community composition of the upper and the lower parts of the euphotic zone, expressed respectively by positive or negative scores of the first principal component, which was positively correlated with taxa such as the dinoflagellates Oxytoxum minutum and Scrippsiella spp., and the coccolithophores Discosphaera tubifera and Syracosphaera pulchra (HOL and HET), and negatively correlated with taxa like Ophiaster hydroideus (coccolithophore) and several diatoms, 2) a general abundance gradient between phytoplankton-rich regions with high abundances of dinoflagellate, coccolithophore and ciliate taxa, and phytoplankton-poor regions (second principal component), 3) differences in dominant phytoplankton and ciliate taxa among the Atlantic, the Indian and the Pacific oceans (third principal component) and 4) the occurrence of a diatom-dominated assemblage (the fourth principal

  8. Multicellular Features of Phytoplankton

    Directory of Open Access Journals (Sweden)

    Adi Abada

    2018-04-01

    Full Text Available Microscopic marine phytoplankton drift freely in the ocean, harvesting sunlight through photosynthesis. These unicellular microorganisms account for half of the primary productivity on Earth and play pivotal roles in the biogeochemistry of our planet (Field et al., 1998. The major groups of microalgae that comprise the phytoplankton community are coccolithophores, diatoms and dinoflagellates. In present oceans, phytoplankton individuals and populations are forced to rapidly adjust, as key chemical and physical parameters defining marine habitats are changing globally. Here we propose that microalgal populations often display the characteristics of a multicellular-like community rather than a random collection of individuals. Evolution of multicellularity entails a continuum of events starting from single cells that go through aggregation or clonal divisions (Brunet and King, 2017. Phytoplankton may be an intermediate state between single cells and aggregates of physically attached cells that communicate and co-operate; perhaps an evolutionary snapshot toward multicellularity. In this opinion article, we journey through several studies conducted in two key phytoplankton groups, coccolithophores and diatoms, to demonstrate how observations in these studies could be interpreted in a multicellular context.

  9. The Miocene "Pteropod event" in the SW part of the Central Paratethys (Medvednica Mt., northern Croatia)

    Science.gov (United States)

    Bošnjak, Marija; Sremac, Jasenka; Vrsaljko, Davor; Aščić, Šimun; Bosak, Luka

    2017-08-01

    Deep marine Miocene deposits exposed sporadically in the Medvednica Mt. (northern Croatia) comprise pelagic organisms such as coccolithophores, planktic foraminifera and pteropods. The pteropod fauna from yellow marls at the Vejalnica locality (central part of Medvednica Mt.) encompasses abundant specimens of Vaginella austriaca Kittl, 1886, accompanied with scarce Clio fallauxi (Kittl, 1886). Calcareous nannoplankton points to the presence of NN5 nannozone at this locality. Highly fossiliferous grey marls at the Marija Bistrica locality (north-eastern area of Medvednica Mt.) comprise limacinid pteropods: Limacina valvatina (Reuss, 1867), L. gramensis (Rasmussen, 1968) and Limacina sp. Late Badenian (NN5 to NN6 nannozone) age of these marls is presumed on the basis of coccolithophores. Most of the determined pteropods on species level, except V. austriaca have been found and described from this region for the first time. New pteropod records from Croatia point to two pteropod horizons coinciding with the Badenian marine transgressions in Central Paratethys. These pteropod assemblages confirm the existence of W-E marine connection ("Transtethyan Trench Corridor") during the Badenian NN5 nannozone. Limacinids point to the possible immigration of the "North Sea fauna" through a northern European marine passage during the Late Badenian (end of NN5-beginning of NN6 zone), as previously presumed by some other authors.

  10. Distribution of phytoplankton groups within the deep chlorophyll maximum

    KAUST Repository

    Latasa, Mikel

    2016-11-01

    The fine vertical distribution of phytoplankton groups within the deep chlorophyll maximum (DCM) was studied in the NE Atlantic during summer stratification. A simple but unconventional sampling strategy allowed examining the vertical structure with ca. 2 m resolution. The distribution of Prochlorococcus, Synechococcus, chlorophytes, pelagophytes, small prymnesiophytes, coccolithophores, diatoms, and dinoflagellates was investigated with a combination of pigment-markers, flow cytometry and optical and FISH microscopy. All groups presented minimum abundances at the surface and a maximum in the DCM layer. The cell distribution was not vertically symmetrical around the DCM peak and cells tended to accumulate in the upper part of the DCM layer. The more symmetrical distribution of chlorophyll than cells around the DCM peak was due to the increase of pigment per cell with depth. We found a vertical alignment of phytoplankton groups within the DCM layer indicating preferences for different ecological niches in a layer with strong gradients of light and nutrients. Prochlorococcus occupied the shallowest and diatoms the deepest layers. Dinoflagellates, Synechococcus and small prymnesiophytes preferred shallow DCM layers, and coccolithophores, chlorophytes and pelagophytes showed a preference for deep layers. Cell size within groups changed with depth in a pattern related to their mean size: the cell volume of the smallest group increased the most with depth while the cell volume of the largest group decreased the most. The vertical alignment of phytoplankton groups confirms that the DCM is not a homogeneous entity and indicates groups’ preferences for different ecological niches within this layer.

  11. Calcification response of Pleurochrysis carterae to iron concentrations in batch incubations: implication for the marine biogeochemical cycle

    Science.gov (United States)

    Zou, Xiang; Sun, Shiyong; Lin, Sen; Shen, Kexuan; Dong, Faqin; Tan, Daoyong; Nie, Xiaoqin; Liu, Mingxue; Wei, Jie

    2017-12-01

    Calcified coccolithophores, a diverse and widely distributed group of marine microalgae, produce biogenic calcite in the form of coccoliths located on the cell surface. Using batch incubations of the coccolithophorid Pleurochrysis carterae, we investigated the responses of this calcification process to iron concentrations by changing the iron supply in the initial culture media from a normal concentration to 1 ppm (parts per million), 5 ppm, and 10 ppm. Time-dependent measurements of cell population, production of inorganic carbon (coccoliths), and organic carbon (organic cellular components) showed that elevated iron supply in the growth medium of P. carterae stimulates carbon sequestration by increasing growth along enhanced photosynthetic activity and calcification. In addition, the acquired time-dependent UV-Vis and FT-IR spectra revealed that iron fertilization-enhanced coccolith calcification is accompanied by a crystalline phase transition from calcite to aragonite or amorphous phase. Our results suggest that iron concentration has a significant influence on the marine carbon cycle of coccolithophores.

  12. The Effect of ENSO on Phytoplankton Composition in the Pacific Ocean

    Science.gov (United States)

    Rousseaux, Cecile

    2012-01-01

    The effect of climate variability on phytoplankton communities was assessed for the tropical and sub-tropical Pacific Ocean between 1998 and 2005 using an established biogeochemical assimilation model. The phytoplankton communities exhibited wide range of responses to climate variability, from radical shifts in the Equatorial Pacific, to changes of only a couple of phytoplankton groups in the North Central Pacific, to no significant changes in the South Pacific. In the Equatorial Pacific, climate variability dominated the variability of phytoplankton. Here, nitrate, chlorophyll and all but one of the 4 phytoplankton types (diatoms, cyanobacteria and coccolithophores) were strongly correlated (p less than 0.01) with the Multivariate El Nino Southern Oscillation Index (MEI). In the North Central Pacific, MEI and chlorophyll were significantly (pphytoplankton groups (chlorophytes and coccolithophores). Ocean biology in the South Pacific was not significantly correlated with MEI. During La Ni a events, diatoms increased and expanded westward along the cold tongue (correlation with MEI, r=-0.81), while cyanobacteria concentrations decreased significantly (r=0.78). El Nino produced the reverse pattern, with cyanobacteria populations increasing while diatoms plummeted. The diverse response of phytoplankton in the different major basins of the Pacific suggests the different roles climate variability can play in ocean biology.

  13. Climate Variability and Phytoplankton in the Pacific Ocean

    Science.gov (United States)

    Rousseaux, Cecile

    2012-01-01

    The effect of climate variability on phytoplankton communities was assessed for the tropical and sub-tropical Pacific Ocean between 1998 and 2005 using an established biogeochemical assimilation model. The phytoplankton communities exhibited wide range of responses to climate variability, from radical shifts in the Equatorial Pacific, to changes of only a couple of phytoplankton groups in the North Central Pacific, to no significant changes in the South Pacific. In the Equatorial Pacific, climate variability dominated the variability of phytoplankton. Here, nitrate, chlorophyll and all but one of the 4 phytoplankton types (diatoms, cyanobacteria and coccolithophores) were strongly correlated (pphytoplankton groups (chlorophytes and coccolithophores). Ocean biology in the South Pacific was not significantly correlated with MEI. During La Nina events, diatoms increased and expanded westward along the cold tongue (correlation with MEI, r=-0.81), while cyanobacteria concentrations decreased significantly (r=0.78). El Nino produced the reverse pattern, with cyanobacteria populations increasing while diatoms plummeted. The diverse response of phytoplankton in the different major basins of the Pacific suggests the different roles climate variability can play in ocean biology.

  14. Paleolatitudinal Gradients in Marine Phytoplankton Composition and Cell Size

    Science.gov (United States)

    Henderiks, J.; Bordiga, M.; Bartol, M.; Šupraha, L.

    2014-12-01

    Coccolithophores, a prominent group of marine calcifying unicellular algae, are widely studied in context of current and past climate change. We know that marine phytoplankton are sensitive to climatic changes, but the complex interplay of several processes such as warming, changes in nutrient content, and ocean acidification, makes future scenarios difficult to predict. Some taxa may be more susceptible to environmental perturbations than others, as evidenced by significantly different species-specific sensitivities observed in laboratory experiments. However, short-term plastic responses may not translate into longer-term climatic adaptation, nor should we readily extrapolate the behavior of single strains in the laboratory to natural, multi-species assemblages and their interactions in the ocean. The extensive fossil record of coccolithophores (in the form of coccoliths) reveals high morphological and taxonomic diversity and allows reconstructing the cell size of individual taxonomic groups. In a suite of deep-sea drilling sites from the Atlantic Ocean, we document distinct latitudinal gradients in phytoplankton composition and cell size across major climate transitions of the late Eocene - earliest Oligocene, and the middle - late Miocene. With these data we test hypotheses of species migration, phenotypic evolution, as well as the rates of species extinction and speciation in relation to concurrent paleoenvironmental changes during the Cenozoic.

  15. Metagenomic Analysis of Genes Encoding Nutrient Cycling Pathways in the Microbiota of Deep-Sea and Shallow-Water Sponges.

    Science.gov (United States)

    Li, Zhiyong; Wang, Yuezhu; Li, Jinlong; Liu, Fang; He, Liming; He, Ying; Wang, Shenyue

    2016-12-01

    Sponges host complex symbiotic communities, but to date, the whole picture of the metabolic potential of sponge microbiota remains unclear, particularly the difference between the shallow-water and deep-sea sponge holobionts. In this study, two completely different sponges, shallow-water sponge Theonella swinhoei from the South China Sea and deep-sea sponge Neamphius huxleyi from the Indian Ocean, were selected to compare their whole symbiotic communities and metabolic potential, particularly in element transformation. Phylogenetically diverse bacteria, archaea, fungi, and algae were detected in both shallow-water sponge T. swinhoei and deep-sea sponge N. huxleyi, and different microbial community structures were indicated between these two sponges. Metagenome-based gene abundance analysis indicated that, though the two sponge microbiota have similar core functions, they showed different potential strategies in detailed metabolic processes, e.g., in the transformation and utilization of carbon, nitrogen, phosphorus, and sulfur by corresponding microbial symbionts. This study provides insight into the putative metabolic potentials of the microbiota associated with the shallow-water and deep-sea sponges at the whole community level, extending our knowledge of the sponge microbiota's functions, the association of sponge- microbes, as well as the adaption of sponge microbiota to the marine environment.

  16. Multi-nutrient, multi-group model of present and future oceanic phytoplankton communities

    Directory of Open Access Journals (Sweden)

    E. Litchman

    2006-01-01

    Full Text Available Phytoplankton community composition profoundly affects patterns of nutrient cycling and the dynamics of marine food webs; therefore predicting present and future phytoplankton community structure is crucial to understand how ocean ecosystems respond to physical forcing and nutrient limitations. We develop a mechanistic model of phytoplankton communities that includes multiple taxonomic groups (diatoms, coccolithophores and prasinophytes, nutrients (nitrate, ammonium, phosphate, silicate and iron, light, and a generalist zooplankton grazer. Each taxonomic group was parameterized based on an extensive literature survey. We test the model at two contrasting sites in the modern ocean, the North Atlantic (North Atlantic Bloom Experiment, NABE and subarctic North Pacific (ocean station Papa, OSP. The model successfully predicts general patterns of community composition and succession at both sites: In the North Atlantic, the model predicts a spring diatom bloom, followed by coccolithophore and prasinophyte blooms later in the season. In the North Pacific, the model reproduces the low chlorophyll community dominated by prasinophytes and coccolithophores, with low total biomass variability and high nutrient concentrations throughout the year. Sensitivity analysis revealed that the identity of the most sensitive parameters and the range of acceptable parameters differed between the two sites. We then use the model to predict community reorganization under different global change scenarios: a later onset and extended duration of stratification, with shallower mixed layer depths due to increased greenhouse gas concentrations; increase in deep water nitrogen; decrease in deep water phosphorus and increase or decrease in iron concentration. To estimate uncertainty in our predictions, we used a Monte Carlo sampling of the parameter space where future scenarios were run using parameter combinations that produced acceptable modern day outcomes and the

  17. Interannual Variation in Phytoplankton Class-Specific Primary Production at a Global Scale

    Science.gov (United States)

    Rousseaux, Cecile Severine; Gregg, Watson W.

    2014-01-01

    We used the NASA Ocean Biogeochemical Model (NOBM) combined with remote sensing data via assimilation to evaluate the contribution of 4 phytoplankton groups to the total primary production. First we assessed the contribution of each phytoplankton groups to the total primary production at a global scale for the period 1998-2011. Globally, diatoms were the group that contributed the most to the total phytoplankton production (50, the equivalent of 20 PgC y-1. Coccolithophores and chlorophytes each contributed to 20 (7 PgC y-1 of the total primary production and cyanobacteria represented about 10 (4 PgC y(sub-1) of the total primary production. Primary production by diatoms was highest in high latitude (45) and in major upwelling systems (Equatorial Pacific and Benguela system). We then assessed interannual variability of this group-specific primary production over the period 1998-2011. Globally the annual relative contribution of each phytoplankton groups to the total primary production varied by maximum 4 (1-2 PgC y-1. We assessed the effects of climate variability on the class-specific primary production using global (i.e. Multivariate El Nio Index, MEI) and regional climate indices (e.g. Southern Annular Mode (SAM), Pacific Decadal Oscillation (PDO) and North Atlantic Oscillation (NAO)). Most interannual variability occurred in the Equatorial Pacific and was associated with climate variability as indicated by significant correlation (p 0.05) between the MEI and the class-specific primary production from all groups except coccolithophores. In the Atlantic, climate variability as indicated by NAO was significantly correlated to the primary production of 2 out of the 4 groups in the North Central Atlantic (diatomscyanobacteria) and in the North Atlantic (chlorophytes and coccolithophores). We found that climate variability as indicated by SAM had only a limited effect on the class-specific primary production in the Southern Ocean. These results provide a modeling and

  18. Interannual Variation in Phytoplankton Primary Production at a Global Scale

    Science.gov (United States)

    Rousseaux, Cecile Severine; Gregg, Watson W.

    2013-01-01

    We used the NASA Ocean Biogeochemical Model (NOBM) combined with remote sensing data via assimilation to evaluate the contribution of four phytoplankton groups to the total primary production. First, we assessed the contribution of each phytoplankton groups to the total primary production at a global scale for the period 1998-2011. Globally, diatoms contributed the most to the total phytoplankton production ((is)approximately 50%, the equivalent of 20 PgC·y1). Coccolithophores and chlorophytes each contributed approximately 20% ((is) approximately 7 PgC·y1) of the total primary production and cyanobacteria represented about 10% ((is) approximately 4 PgC·y1) of the total primary production. Primary production by diatoms was highest in the high latitudes ((is) greater than 40 deg) and in major upwelling systems (Equatorial Pacific and Benguela system). We then assessed interannual variability of this group-specific primary production over the period 1998-2011. Globally the annual relative contribution of each phytoplankton groups to the total primary production varied by maximum 4% (1-2 PgC·y1). We assessed the effects of climate variability on group-specific primary production using global (i.e., Multivariate El Niño Index, MEI) and "regional" climate indices (e.g., Southern Annular Mode (SAM), Pacific Decadal Oscillation (PDO) and North Atlantic Oscillation (NAO)). Most interannual variability occurred in the Equatorial Pacific and was associated with climate variability as indicated by significant correlation (p (is) less than 0.05) between the MEI and the group-specific primary production from all groups except coccolithophores. In the Atlantic, climate variability as indicated by NAO was significantly correlated to the primary production of 2 out of the 4 groups in the North Central Atlantic (diatoms/cyanobacteria) and in the North Atlantic (chlorophytes and coccolithophores). We found that climate variability as indicated by SAM had only a limited effect

  19. Marine biominerals: perspectives and challenges for polymetallic nodules and crusts.

    Science.gov (United States)

    Wang, Xiaohong; Müller, Werner E G

    2009-06-01

    Deep sea minerals in polymetallic nodules, crusts and hydrothermal vents are not only formed by mineralization but also by biologically driven processes involving microorganisms (biomineralization). Within the nodules, free-living and biofilm-forming bacteria provide the matrix for manganese deposition, and in cobalt-rich crusts, coccolithophores represent the dominant organisms that act as bio-seeds for an initial manganese deposition. These (bio)minerals are economically important: manganese is an important alloying component and cobalt forms part of special steels in addition to being used, along with other rare metals, in plasma screens, hard-disk magnets and hybrid car motors. Recent progress in our understanding of the participation of the organic matrices in the enrichment of these metals might provide the basis for feasibility studies of biotechnological applications.

  20. Effects of changes in carbonate chemistry speciation on Coccolithus braarudii: a discussion of coccolithophorid sensitivities

    Directory of Open Access Journals (Sweden)

    U. Riebesell

    2011-03-01

    Full Text Available Ocean acidification and associated shifts in carbonate chemistry speciation induced by increasing levels of atmospheric carbon dioxide (CO2 have the potential to impact marine biota in various ways. The process of biogenic calcification, for instance, is usually shown to be negatively affected. In coccolithophores, an important group of pelagic calcifiers, changes in cellular calcification rates in response to changing ocean carbonate chemistry appear to differ among species. By applying a wider CO2 range we show that a species previously reported insensitive to seawater acidification, Coccolithus braarudii, responds both in terms of calcification and photosynthesis, although at higher levels of CO2. Thus, observed differences between species seem to be related to individual sensitivities while the underlying mechanisms could be the same. On this basis we develop a conceptual model of coccolithophorid calcification and photosynthesis in response to CO2-induced changes in seawater carbonate chemistry speciation.

  1. The plastic-associated microorganisms of the North Pacific Gyre.

    Science.gov (United States)

    Carson, Henry S; Nerheim, Magnus S; Carroll, Katherine A; Eriksen, Marcus

    2013-10-15

    Microorganisms likely mediate processes affecting the fate and impacts of marine plastic pollution, including degradation, chemical adsorption, and colonization or ingestion by macroorganisms. We investigated the relationship between plastic-associated microorganism communities and factors such as location, temperature, salinity, plankton abundance, plastic concentration, item size, surface roughness, and polymer type. Small plastic items from the surface of the North Pacific Gyre in 2011 were examined using scanning electron microscopy. Bacillus bacteria (mean 1664 ± 247 individuals mm(-2)) and pennate diatoms (1097 ± 154 mm(-2)) were most abundant, with coccoid bacteria, centric diatoms, dinoflagellates, coccolithophores, and radiolarians present. Bacterial abundance was patchy, but increased on foamed polystyrene. Diatom abundance increased on items with rough surfaces and at sites with high plastic concentrations. Morphotype richness increased slightly on larger fragments, and a biogeographic transition occurred between pennate diatom groups. Better characterizing this community will aid in understanding how it interacts with plastic pollution. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. Contribution of fish to the marine inorganic carbon cycle.

    Science.gov (United States)

    Wilson, R W; Millero, F J; Taylor, J R; Walsh, P J; Christensen, V; Jennings, S; Grosell, M

    2009-01-16

    Oceanic production of calcium carbonate is conventionally attributed to marine plankton (coccolithophores and foraminifera). Here we report that marine fish produce precipitated carbonates within their intestines and excrete these at high rates. When combined with estimates of global fish biomass, this suggests that marine fish contribute 3 to 15% of total oceanic carbonate production. Fish carbonates have a higher magnesium content and solubility than traditional sources, yielding faster dissolution with depth. This may explain up to a quarter of the increase in titratable alkalinity within 1000 meters of the ocean surface, a controversial phenomenon that has puzzled oceanographers for decades. We also predict that fish carbonate production may rise in response to future environmental changes in carbon dioxide, and thus become an increasingly important component of the inorganic carbon cycle.

  3. Nutrient Limitation in Surface Waters of the Oligotrophic Eastern Mediterranean Sea: an Enrichment Microcosm Experiment

    KAUST Repository

    Tsiola, A.

    2015-12-01

    The growth rates of planktonic microbes in the pelagic zone of the Eastern Mediterranean Sea are nutrient limited, but the type of limitation is still uncertain. During this study, we investigated the occurrence of N and P limitation among different groups of the prokaryotic and eukaryotic (pico-, nano-, and micro-) plankton using a microcosm experiment during stratified water column conditions in the Cretan Sea (Eastern Mediterranean). Microcosms were enriched with N and P (either solely or simultaneously), and the PO4 turnover time, prokaryotic heterotrophic activity, primary production, and the abundance of the different microbial components were measured. Flow cytometric and molecular fingerprint analyses showed that different heterotrophic prokaryotic groups were limited by different nutrients; total heterotrophic prokaryotic growth was limited by P, but only when both N and P were added, changes in community structure and cell size were detected. Phytoplankton were N and P co-limited, with autotrophic pico-eukaryotes being the exception as they increased even when only P was added after a 2-day time lag. The populations of Synechococcus and Prochlorococcus were highly competitive with each other; Prochlorococcus abundance increased during the first 2 days of P addition but kept increasing only when both N and P were added, whereas Synechococcus exhibited higher pigment content and increased in abundance 3 days after simultaneous N and P additions. Dinoflagellates also showed opportunistic behavior at simultaneous N and P additions, in contrast to diatoms and coccolithophores, which diminished in all incubations. High DNA content viruses, selective grazing, and the exhaustion of N sources probably controlled the populations of diatoms and coccolithophores.

  4. Reassessment of the wing feathers of Archaeopteryx lithographica suggests no robust evidence for the presence of elongated dorsal wing coverts.

    Directory of Open Access Journals (Sweden)

    Robert L Nudds

    Full Text Available Recently it was proposed that the primary feathers of Archaeopteryx lithographica (HMN1880 were overlaid by long covert feathers, and that a multilayered feathered wing was a feature of early fossils with feathered forelimbs. The proposed long covert feathers of Archaeopteryx were previously interpreted as dorsally displaced remiges or a second set of impressions made by the wing. The following study shows that the qualitative arguments forwarded in support of the elongated covert hypothesis are neither robust nor supported quantitatively. The idea that the extant bird wing with its single layer of overlapping primaries evolved from an earlier multilayered heavily coveted feathered forelimb as seen in Anchiornis huxleyi is reasonable. At this juncture, however, it is premature to conclude unequivocally that the wing of Archaeopteryx consisted of primary feathers overlaid with elongated coverts.

  5. Directional and Spectral Irradiance in Ocean Models: Effects on Simulated Global Phytoplankton, Nutrients, and Primary Production

    Science.gov (United States)

    Gregg, Watson W.; Rousseaux, Cecile S.

    2016-01-01

    The importance of including directional and spectral light in simulations of ocean radiative transfer was investigated using a coupled biogeochemical-circulation-radiative model of the global oceans. The effort focused on phytoplankton abundances, nutrient concentrations and vertically-integrated net primary production. The importance was approached by sequentially removing directional (i.e., direct vs. diffuse) and spectral irradiance and comparing results of the above variables to a fully directionally and spectrally-resolved model. In each case the total irradiance was kept constant; it was only the pathways and spectral nature that were changed. Assuming all irradiance was diffuse had negligible effect on global ocean primary production. Global nitrate and total chlorophyll concentrations declined by about 20% each. The largest changes occurred in the tropics and sub-tropics rather than the high latitudes, where most of the irradiance is already diffuse. Disregarding spectral irradiance had effects that depended upon the choice of attenuation wavelength. The wavelength closest to the spectrally-resolved model, 500 nm, produced lower nitrate (19%) and chlorophyll (8%) and higher primary production (2%) than the spectral model. Phytoplankton relative abundances were very sensitive to the choice of non-spectral wavelength transmittance. The combined effects of neglecting both directional and spectral irradiance exacerbated the differences, despite using attenuation at 500 nm. Global nitrate decreased 33% and chlorophyll decreased 24%. Changes in phytoplankton community structure were considerable, representing a change from chlorophytes to cyanobacteria and coccolithophores. This suggested a shift in community function, from light-limitation to nutrient limitation: lower demands for nutrients from cyanobacteria and coccolithophores favored them over the more nutrient-demanding chlorophytes. Although diatoms have the highest nutrient demands in the model, their

  6. Dimethylsulfoniopropionate (DMSP) and dimethyl sulfide (DMS) cycling across contrasting biological hotspots of the New Zealand subtropical front

    Science.gov (United States)

    Lizotte, Martine; Levasseur, Maurice; Law, Cliff S.; Walker, Carolyn F.; Safi, Karl A.; Marriner, Andrew; Kiene, Ronald P.

    2017-11-01

    The oceanic frontal region above the Chatham Rise east of New Zealand was investigated during the late austral summer season in February and March 2012. Despite its potential importance as a source of marine-originating and climate-relevant compounds, such as dimethyl sulfide (DMS) and its algal precursor dimethylsulfoniopropionate (DMSP), little is known of the processes fuelling the reservoirs of these sulfur (S) compounds in the water masses bordering the subtropical front (STF). This study focused on two opposing short-term fates of DMSP-S following its uptake by microbial organisms (either its conversion into DMS or its assimilation into bacterial biomass) and has not considered dissolved non-volatile degradation products. Sampling took place in three phytoplankton blooms (B1, B2, and B3) with B1 and B3 occurring in relatively nitrate-rich, dinoflagellate-dominated subantarctic waters, and B2 occurring in nitrate-poor subtropical waters dominated by coccolithophores. Concentrations of total DMSP (DMSPt) and DMS were high across the region, up to 160 and 14.5 nmol L-1, respectively. Pools of DMSPt showed a strong association with overall phytoplankton biomass proxied by chlorophyll a (rs = 0.83) likely because of the persistent dominance of dinoflagellates and coccolithophores, both DMSP-rich taxa. Heterotrophic microbes displayed low S assimilation from DMSP (less than 5 %) likely because their S requirements were fulfilled by high DMSP availability. Rates of bacterial protein synthesis were significantly correlated with concentrations of dissolved DMSP (DMSPd, rs = 0.86) as well as with the microbial conversion efficiency of DMSPd into DMS (DMS yield, rs = 0.84). Estimates of the potential contribution of microbially mediated rates of DMS production (0.1-27 nmol L-1 day-1) to the near-surface concentrations of DMS suggest that bacteria alone could not have sustained DMS pools at most stations, indicating an important role for phytoplankton-mediated DMS

  7. Synergistic Exploitation of Hyper- and Multi-Spectral Precursor Sentinel Measurements to Determine Phytoplankton Functional Types (SynSenPFT

    Directory of Open Access Journals (Sweden)

    Svetlana N. Losa

    2017-07-01

    Full Text Available We derive the chlorophyll a concentration (Chla for three main phytoplankton functional types (PFTs – diatoms, coccolithophores and cyanobacteria – by combining satellite multispectral-based information, being of a high spatial and temporal resolution, with retrievals based on high resolution of PFT absorption properties derived from hyperspectral satellite measurements. The multispectral-based PFT Chla retrievals are based on a revised version of the empirical OC-PFT algorithm applied to the Ocean Color Climate Change Initiative (OC-CCI total Chla product. The PhytoDOAS analytical algorithm is used with some modifications to derive PFT Chla from SCIAMACHY hyperspectral measurements. To combine synergistically these two PFT products (OC-PFT and PhytoDOAS, an optimal interpolation is performed for each PFT in every OC-PFT sub-pixel within a PhytoDOAS pixel, given its Chla and its a priori error statistics. The synergistic product (SynSenPFT is presented for the period of August 2002 March 2012 and evaluated against PFT Chla data obtained from in situ marker pigment data and the NASA Ocean Biogeochemical Model simulations and satellite information on phytoplankton size. The most challenging aspects of the SynSenPFT algorithm implementation are discussed. Perspectives on SynSenPFT product improvements and prolongation of the time series over the next decades by adaptation to Sentinel multi- and hyperspectral instruments are highlighted.

  8. Carbon and nutrient mixed layer dynamics in the Norwegian Sea

    Directory of Open Access Journals (Sweden)

    H. S. Findlay

    2008-10-01

    Full Text Available A coupled carbon-ecosystem model is compared to recent data from Ocean Weather Station M (66° N, 02° E and used as a tool to investigate nutrient and carbon processes within the Norwegian Sea. Nitrate is consumed by phytoplankton in the surface layers over the summer; however the data show that silicate does not become rapidly limiting for diatoms, in contrast to the model prediction and in contrast to data from other temperate locations. The model estimates atmosphere-ocean CO2 flux to be 37 g C m−2 yr−1. The seasonal cycle of the carbonate system at OWS M resembles the cycles suggested by data from other high-latitude ocean locations. The seasonal cycles of calcite saturation state and [CO32-] are similar in the model and in data at OWS M: values range from ~3 and ~120 μmol kg−1 respectively in winter, to ~4 and ~170 μmol kg−1 respectively in summer. The model and data provide further evidence (supporting previous modelling work that the summer is a time of high saturation state within the annual cycle at high-latitude locations. This is also the time of year that coccolithophore blooms occur at high latitudes.

  9. Advanced characterization of dissolved organic matter released by bloom-forming marine algae

    KAUST Repository

    Rehman, Zahid Ur

    2017-06-01

    Algal organic matter (AOM), produced by marine phytoplankton during bloom periods, may adversely affect the performance of membrane processes in seawater desalination. The polysaccharide fraction of AOM has been related to (bio)fouling in micro-filtration and ultrafiltration, and reverse osmosis membranes. However, so far, the chemical structure of the polysaccharides released by bloom-forming algae is not well understood. In this study, dissolved fraction of AOM produced by three algal species (Chaetoceros affinis, Nitzschia epithemoides and Hymenomonas spp.) was characterized using liquid chromatography–organic carbon detection (LC-OCD) and fluorescence spectroscopy. Chemical structure of polysaccharides isolated from the AOM solutions at stationary phase was analyzed using proton nuclear magnetic resonance (H-NMR). The results showed that production and composition of dissolved AOM varied depending on algal species and their growth stage. AOM was mainly composed of biopolymers (BP; i.e., polysaccharides and proteins [PN]), but some refractory substances were also present.H-NMR spectra confirmed the predominance of carbohydrates in all samples. Furthermore, similar fingerprints were observed for polysaccharides of two diatom species, which differed considerably from that of coccolithophores. Based on the findings of this study,H-NMR could be used as a method for analyzing chemical profiles of algal polysaccharides to enhance the understanding of their impact on membrane fouling.

  10. Ocean acidification reduces growth and calcification in a marine dinoflagellate.

    Directory of Open Access Journals (Sweden)

    Dedmer B Van de Waal

    Full Text Available Ocean acidification is considered a major threat to marine ecosystems and may particularly affect calcifying organisms such as corals, foraminifera and coccolithophores. Here we investigate the impact of elevated pCO2 and lowered pH on growth and calcification in the common calcareous dinoflagellate Thoracosphaera heimii. We observe a substantial reduction in growth rate, calcification and cyst stability of T. heimii under elevated pCO2. Furthermore, transcriptomic analyses reveal CO2 sensitive regulation of many genes, particularly those being associated to inorganic carbon acquisition and calcification. Stable carbon isotope fractionation for organic carbon production increased with increasing pCO2 whereas it decreased for calcification, which suggests interdependence between both processes. We also found a strong effect of pCO2 on the stable oxygen isotopic composition of calcite, in line with earlier observations concerning another T. heimii strain. The observed changes in stable oxygen and carbon isotope composition of T. heimii cysts may provide an ideal tool for reconstructing past seawater carbonate chemistry, and ultimately past pCO2. Although the function of calcification in T. heimii remains unresolved, this trait likely plays an important role in the ecological and evolutionary success of this species. Acting on calcification as well as growth, ocean acidification may therefore impose a great threat for T. heimii.

  11. Voltage-Gated Proton Channels: Molecular Biology, Physiology, and Pathophysiology of the HV Family

    Science.gov (United States)

    2013-01-01

    Voltage-gated proton channels (HV) are unique, in part because the ion they conduct is unique. HV channels are perfectly selective for protons and have a very small unitary conductance, both arguably manifestations of the extremely low H+ concentration in physiological solutions. They open with membrane depolarization, but their voltage dependence is strongly regulated by the pH gradient across the membrane (ΔpH), with the result that in most species they normally conduct only outward current. The HV channel protein is strikingly similar to the voltage-sensing domain (VSD, the first four membrane-spanning segments) of voltage-gated K+ and Na+ channels. In higher species, HV channels exist as dimers in which each protomer has its own conduction pathway, yet gating is cooperative. HV channels are phylogenetically diverse, distributed from humans to unicellular marine life, and perhaps even plants. Correspondingly, HV functions vary widely as well, from promoting calcification in coccolithophores and triggering bioluminescent flashes in dinoflagellates to facilitating killing bacteria, airway pH regulation, basophil histamine release, sperm maturation, and B lymphocyte responses in humans. Recent evidence that hHV1 may exacerbate breast cancer metastasis and cerebral damage from ischemic stroke highlights the rapidly expanding recognition of the clinical importance of hHV1. PMID:23589829

  12. Millimeter-Sized Marine Plastics: A New Pelagic Habitat for Microorganisms and Invertebrates

    Science.gov (United States)

    Reisser, Julia; Shaw, Jeremy; Hallegraeff, Gustaaf; Proietti, Maira; Barnes, David K. A.; Thums, Michele; Wilcox, Chris; Hardesty, Britta Denise; Pattiaratchi, Charitha

    2014-01-01

    Millimeter-sized plastics are abundant in most marine surface waters, and known to carry fouling organisms that potentially play key roles in the fate and ecological impacts of plastic pollution. In this study we used scanning electron microscopy to characterize biodiversity of organisms on the surface of 68 small floating plastics (length range = 1.7–24.3 mm, median = 3.2 mm) from Australia-wide coastal and oceanic, tropical to temperate sample collections. Diatoms were the most diverse group of plastic colonizers, represented by 14 genera. We also recorded ‘epiplastic’ coccolithophores (7 genera), bryozoans, barnacles (Lepas spp.), a dinoflagellate (Ceratium), an isopod (Asellota), a marine worm, marine insect eggs (Halobates sp.), as well as rounded, elongated, and spiral cells putatively identified as bacteria, cyanobacteria, and fungi. Furthermore, we observed a variety of plastic surface microtextures, including pits and grooves conforming to the shape of microorganisms, suggesting that biota may play an important role in plastic degradation. This study highlights how anthropogenic millimeter-sized polymers have created a new pelagic habitat for microorganisms and invertebrates. The ecological ramifications of this phenomenon for marine organism dispersal, ocean productivity, and biotransfer of plastic-associated pollutants, remains to be elucidated. PMID:24941218

  13. Interannual Variation in Phytoplankton Class-specific Primary Production at a Global Scale

    Science.gov (United States)

    Rousseaux, Cecile; Gregg, Watson

    2014-01-01

    Phytoplankton is responsible for over half of the net primary production on earth. The knowledge on the contribution of various phytoplankton groups to the total primary production is still poorly understood. Data from satellite observations suggest that for upwelling regions, photosynthetic rates by microplankton is higher than that of nanoplankton but that when the spatial extent is considered, the production by nanoplankton is comparable or even larger than microplankton. Here, we used the NASA Ocean Biogeochemical Model (NOBM) combined with remote sensing data via assimilation to evaluate the contribution of 4 phytoplankton groups to the total primary production. Globally, diatoms were the group that contributed the most to the total phytoplankton production (approx. 50%) followed by coccolithophores and chlorophytes. Primary production by diatoms was highest in high latitude (>45 deg) and in major upwelling systems (Equatorial Pacific and Benguela system). We assessed the effects of climate variability on the class-specific primary production using global (i.e. Multivariate El Nino Index, MEI) and 'regional' climate indices (e.g. Southern Annular Mode (SAM), Pacific Decadal Oscillation (PDO) and North Atlantic Oscillation (NAO)). Most interannual variability occurred in the Equatorial Pacific and was associated with climate variability. These results provide a modeling and data assimilation perspective to phytoplankton partitioning of primary production and contribute to our understanding of the dynamics of the carbon cycle in the oceans at a global scale.

  14. Millimeter-sized marine plastics: a new pelagic habitat for microorganisms and invertebrates.

    Directory of Open Access Journals (Sweden)

    Julia Reisser

    Full Text Available Millimeter-sized plastics are abundant in most marine surface waters, and known to carry fouling organisms that potentially play key roles in the fate and ecological impacts of plastic pollution. In this study we used scanning electron microscopy to characterize biodiversity of organisms on the surface of 68 small floating plastics (length range = 1.7-24.3 mm, median = 3.2 mm from Australia-wide coastal and oceanic, tropical to temperate sample collections. Diatoms were the most diverse group of plastic colonizers, represented by 14 genera. We also recorded 'epiplastic' coccolithophores (7 genera, bryozoans, barnacles (Lepas spp., a dinoflagellate (Ceratium, an isopod (Asellota, a marine worm, marine insect eggs (Halobates sp., as well as rounded, elongated, and spiral cells putatively identified as bacteria, cyanobacteria, and fungi. Furthermore, we observed a variety of plastic surface microtextures, including pits and grooves conforming to the shape of microorganisms, suggesting that biota may play an important role in plastic degradation. This study highlights how anthropogenic millimeter-sized polymers have created a new pelagic habitat for microorganisms and invertebrates. The ecological ramifications of this phenomenon for marine organism dispersal, ocean productivity, and biotransfer of plastic-associated pollutants, remains to be elucidated.

  15. Effects of the pH/pCO2 control method in the growth medium of phytoplankton

    Science.gov (United States)

    Shi, D.; Xu, Y.; Morel, F. M. M.

    2009-02-01

    To study the effects of ocean acidification on the physiology of phytoplankton requires that the key chemical parameters of the growth medium, pCO2, pH and Ω (the saturation state of calcium carbonate) be carefully controlled. This is made difficult by the interdependence of these parameters. Moreover, in growing batch cultures of phytoplankton, the fixation of CO2, the uptake of nutrients and, for coccolithophores, the precipitation of calcite all change the inorganic carbon and acid-base chemistry of the medium. For example, absent pH-buffering or CO2 bubbling, a sizeable decrease in pCO2 occurs at a biomass concentration as low as 50 μM C in non-calcifying cultures. Even in cultures where pCO2 or pH is maintained constant, other chemical parameters change substantially at high cell densities. The quantification of these changes is facilitated by the use of buffer capacities. Experimentally we observe that all methods of adjustment of pCO2/pH can be used, the choice of one or the other depending on the specifics of the experiments. The mechanical effect of bubbling of cultures seems to induce more variable results than other methods of pCO2/pH control. While highly convenient, the addition of pH buffers to the medium induces changes in trace metal availability and cannot be used under trace metal-limiting conditions.

  16. The plastic-associated microorganisms of the North Pacific Gyre

    International Nuclear Information System (INIS)

    Carson, Henry S.; Nerheim, Magnus S.; Carroll, Katherine A.; Eriksen, Marcus

    2013-01-01

    Highlights: • Microorganisms mediate processes affecting the fate and impacts of marine plastic. • North Pacific Gyre (NPG) plastics were examined with scanning-electron microscopy. • Bacillus bacteria and pennate diatoms dominated the NPG plastic fouling community. • Bacterial abundance was patchily distributed but increased on foamed polystyrene. • Diatom abundance increased on rough surfaces and at sites with high plastic density. -- Abstract: Microorganisms likely mediate processes affecting the fate and impacts of marine plastic pollution, including degradation, chemical adsorption, and colonization or ingestion by macroorganisms. We investigated the relationship between plastic-associated microorganism communities and factors such as location, temperature, salinity, plankton abundance, plastic concentration, item size, surface roughness, and polymer type. Small plastic items from the surface of the North Pacific Gyre in 2011 were examined using scanning electron microscopy. Bacillus bacteria (mean 1664 ± 247 individuals mm −2 ) and pennate diatoms (1097 ± 154 mm −2 ) were most abundant, with coccoid bacteria, centric diatoms, dinoflagellates, coccolithophores, and radiolarians present. Bacterial abundance was patchy, but increased on foamed polystyrene. Diatom abundance increased on items with rough surfaces and at sites with high plastic concentrations. Morphotype richness increased slightly on larger fragments, and a biogeographic transition occurred between pennate diatom groups. Better characterizing this community will aid in understanding how it interacts with plastic pollution

  17. Ocean acidification alters the photosynthetic responses of a coccolithophorid to fluctuating ultraviolet and visible radiation.

    Science.gov (United States)

    Jin, Peng; Gao, Kunshan; Villafañe, Virginia E; Campbell, Douglas A; Helbling, E Walter

    2013-08-01

    Mixing of seawater subjects phytoplankton to fluctuations in photosynthetically active radiation (400-700 nm) and ultraviolet radiation (UVR; 280-400 nm). These irradiance fluctuations are now superimposed upon ocean acidification and thinning of the upper mixing layer through stratification, which alters mixing regimes. Therefore, we examined the photosynthetic carbon fixation and photochemical performance of a coccolithophore, Gephyrocapsa oceanica, grown under high, future (1,000 μatm) and low, current (390 μatm) CO₂ levels, under regimes of fluctuating irradiances with or without UVR. Under both CO₂ levels, fluctuating irradiances, as compared with constant irradiance, led to lower nonphotochemical quenching and less UVR-induced inhibition of carbon fixation and photosystem II electron transport. The cells grown under high CO₂ showed a lower photosynthetic carbon fixation rate but lower nonphotochemical quenching and less ultraviolet B (280-315 nm)-induced inhibition. Ultraviolet A (315-400 nm) led to less enhancement of the photosynthetic carbon fixation in the high-CO₂-grown cells under fluctuating irradiance. Our data suggest that ocean acidification and fast mixing or fluctuation of solar radiation will act synergistically to lower carbon fixation by G. oceanica, although ocean acidification may decrease ultraviolet B-related photochemical inhibition.

  18. Pleurochrysome: A Web Database of Pleurochrysis Transcripts and Orthologs Among Heterogeneous Algae

    Science.gov (United States)

    Fujiwara, Shoko; Takatsuka, Yukiko; Hirokawa, Yasutaka; Tsuzuki, Mikio; Takano, Tomoyuki; Kobayashi, Masaaki; Suda, Kunihiro; Asamizu, Erika; Yokoyama, Koji; Shibata, Daisuke; Tabata, Satoshi; Yano, Kentaro

    2016-01-01

    Pleurochrysis is a coccolithophorid genus, which belongs to the Coccolithales in the Haptophyta. The genus has been used extensively for biological research, together with Emiliania in the Isochrysidales, to understand distinctive features between the two coccolithophorid-including orders. However, molecular biological research on Pleurochrysis such as elucidation of the molecular mechanism behind coccolith formation has not made great progress at least in part because of lack of comprehensive gene information. To provide such information to the research community, we built an open web database, the Pleurochrysome (http://bioinf.mind.meiji.ac.jp/phapt/), which currently stores 9,023 unique gene sequences (designated as UNIGENEs) assembled from expressed sequence tag sequences of P. haptonemofera as core information. The UNIGENEs were annotated with gene sequences sharing significant homology, conserved domains, Gene Ontology, KEGG Orthology, predicted subcellular localization, open reading frames and orthologous relationship with genes of 10 other algal species, a cyanobacterium and the yeast Saccharomyces cerevisiae. This sequence and annotation information can be easily accessed via several search functions. Besides fundamental functions such as BLAST and keyword searches, this database also offers search functions to explore orthologous genes in the 12 organisms and to seek novel genes. The Pleurochrysome will promote molecular biological and phylogenetic research on coccolithophorids and other haptophytes by helping scientists mine data from the primary transcriptome of P. haptonemofera. PMID:26746174

  19. Comprehensive Genetic Database of Expressed Sequence Tags for Coccolithophorids

    Science.gov (United States)

    Ranji, Mohammad; Hadaegh, Ahmad R.

    Coccolithophorids are unicellular, marine, golden-brown, single-celled algae (Haptophyta) commonly found in near-surface waters in patchy distributions. They belong to the Phytoplankton family that is known to be responsible for much of the earth reproduction. Phytoplankton, just like plants live based on the energy obtained by Photosynthesis which produces oxygen. Substantial amount of oxygen in the earth's atmosphere is produced by Phytoplankton through Photosynthesis. The single-celled Emiliana Huxleyi is the most commonly known specie of Coccolithophorids and is known for extracting bicarbonate (HCO3) from its environment and producing calcium carbonate to form Coccoliths. Coccolithophorids are one of the world's primary producers, contributing about 15% of the average oceanic phytoplankton biomass to the oceans. They produce elaborate, minute calcite platelets (Coccoliths), covering the cell to form a Coccosphere and supplying up to 60% of the bulk pelagic calcite deposited on the sea floors. In order to understand the genetics of Coccolithophorid and the complexities of their biochemical reactions, we decided to build a database to store a complete profile of these organisms' genomes. Although a variety of such databases currently exist, (http://www.geneservice.co.uk/home/) none have yet been developed to comprehensively address the sequencing efforts underway by the Coccolithophorid research community. This database is called CocooExpress and is available to public (http://bioinfo.csusm.edu) for both data queries and sequence contribution.

  20. Review: geological and experimental evidence for secular variation in seawater Mg/Ca (calcite-aragonite seas and its effects on marine biological calcification

    Directory of Open Access Journals (Sweden)

    J. B. Ries

    2010-09-01

    Full Text Available Synchronized transitions in the polymorph mineralogy of the major reef-building and sediment-producing calcareous marine organisms and abiotic CaCO3 precipitates (ooids, marine cements throughout Phanerozoic time are believed to have been caused by tectonically induced variations in the Mg/Ca ratio of seawater (molar Mg/Ca>2="aragonite seas", <2="calcite seas". Here, I assess the geological evidence in support of secular variation in seawater Mg/Ca and its effects on marine calcifiers, and review a series of recent experiments that investigate the effects of seawater Mg/Ca (1.0–5.2 on extant representatives of calcifying taxa that have experienced variations in this ionic ratio of seawater throughout the geologic past.

    Secular variation in seawater Mg/Ca is supported by synchronized secular variations in (1 the ionic composition of fluid inclusions in primary marine halite, (2 the mineralogies of late stage marine evaporites, abiogenic carbonates, and reef- and sediment-forming marine calcifiers, (3 the Mg/Ca ratios of fossil echinoderms, molluscs, rugose corals, and abiogenic carbonates, (4 global rates of tectonism that drive the exchange of Mg2+ and Ca2+ along zones of ocean crust production, and (5 additional proxies of seawater Mg/Ca including Sr/Mg ratios of abiogenic carbonates, Sr/Ca ratios of biogenic carbonates, and Br concentrations in marine halite.

    Laboratory experiments have revealed that aragonite-secreting bryopsidalean algae and scleractinian corals and calcite-secreting coccolithophores exhibit higher rates of calcification and growth in experimental seawaters formulated with seawater Mg/Ca ratios that favor their skeletal mineral. These results support the assertion that seawater Mg/Ca played an important role in determining which hypercalcifying marine organisms were the major reef-builders and sediment-producers throughout Earth history. The observation that primary

  1. Indice de la microflora marina de Venezuela: diatomeas, dinoflagelados y cocolitofóridos

    Directory of Open Access Journals (Sweden)

    José Rafael Díaz-Ramos

    2000-12-01

    Full Text Available Los estudios sobre el fitoplancton marino de Venezuela han sido realizados de manera regular desde mediados del siglo XX. Sin embargo, hasta ahora no se ha realizado un compendio de las especies encontradas que sirva como marco de referencia a los trabajos taxonómicos. En este trabajo se presenta por primera vez un índice de la microflora marina de Venezuela. El índice incluye sólo las diatomeas (89 especies céntricas y 186 especies pennadas, los dinoflagelados (ocho especies atecadas y 154 especies tecadas y los cocolitóforidos (24 especies a los cuales se les realizado una diagnosis formal e ilustraciones (dibujos y/o fotografias y que han sido reportados en la literatura científica (revistas y/o tesis de licenciatura o maestría. Esta ordenado según la clase, orden, familia y especie. Además, en el se cita al autor (es de cada taxón.ha.The marine phytoplankton of Venezuela has been studied on a regular basis since the mid 20th century. However, a species checklist that can be used as a framework for taxonomic studies is lacking. In this paper, an index of the marine microflora of Venezuela is presented for the first time. The index includes only those diatoms (89 centric and 186 pennate species, dinoflagellates (eight naked and 154 thecate species and coccolithophores (24 especies for which formal diagnosis and illustrations (drawings and/or photographs have been reported in the scientific literature (journals and/or first degree or master's theses. It is ordered alphabetically according to class, order, family, and species. It includes the author (s of the taxa.

  2. Modelling coral polyp calcification in relation to ocean acidification

    Directory of Open Access Journals (Sweden)

    S. Hohn

    2012-11-01

    Full Text Available Rising atmospheric CO2 concentrations due to anthropogenic emissions induce changes in the carbonate chemistry of the oceans and, ultimately, a drop in ocean pH. This acidification process can harm calcifying organisms like coccolithophores, molluscs, echinoderms, and corals. It is expected that ocean acidification in combination with other anthropogenic stressors will cause a severe decline in coral abundance by the end of this century, with associated disastrous effects on reef ecosystems. Despite the growing importance of the topic, little progress has been made with respect to modelling the impact of acidification on coral calcification. Here we present a model for a coral polyp that simulates the carbonate system in four different compartments: the seawater, the polyp tissue, the coelenteron, and the calcifying fluid. Precipitation of calcium carbonate takes place in the metabolically controlled calcifying fluid beneath the polyp tissue. The model is adjusted to a state of activity as observed by direct microsensor measurements in the calcifying fluid. We find that a transport mechanism for bicarbonate is required to supplement carbon into the calcifying fluid because CO2 diffusion alone is not sufficient to sustain the observed calcification rates. Simulated CO2 perturbation experiments reveal decreasing calcification rates under elevated pCO2 despite the strong metabolic control of the calcifying fluid. Diffusion of CO2 through the tissue into the calcifying fluid increases with increasing seawater pCO2, leading to decreased aragonite saturation in the calcifying fluid. Our modelling study provides important insights into the complexity of the calcification process at the organism level and helps to quantify the effect of ocean acidification on corals.

  3. A 1200 Year Alkenone-based Reconstruction of Sea Surface Temperature and Marine Productivity in the Southern California Current System from the Medieval Climate Anomaly to Present

    Science.gov (United States)

    O'Mara, N. A.; Kelly, C. S.; Herbert, T.

    2017-12-01

    Laminated sediment cores taken from the San Lazaro Basin (SLB) (25.18N, 112.66W) located off the coast of Baja California in the subtropical eastern Pacific were geochemically analyzed for alkenone and sterol biomarkers to reconstruct sea surface temperature (SST) and marine productivity from 850-1980 CE. High sedimentation rates, low bottom water dissolved oxygen, and high marine productivity in combination with the San Lazaro Basin's location within the dynamic transition zone between the tropical and subtropical eastern Pacific, make it a prime location to study variability of tropical and subtropical modes of climate variability. This study focuses on the impacts and variability of the El Niño Southern Oscillation and the Pacific Decadal Oscillation on the subtropical eastern Pacific. SST and coccolithophore productivity (n=730) for 2 mm sections of sediment corresponding to 1 measurement every 1.8 years were reconstructed using the Uk'37 unsaturation index and C37 alkenone concentration. The high resolution of this record allowed for the analysis of variability of SST and productivity on decadal timescales. Brassicasterol concentrations were calculated for a limited number of samples (n=44) to assess diatom productivity. High spectral power was found at periods of 20-30 years in SST and productivity records indicating a strong influence of the PDO on the SLB, making this the first marine based record directly relevant to PDO reconstructions that continuously spans the last millennium. Cool and productive (warm and less productive) waters were observed in the southern California Current in the Medieval Climate Anomaly 900-1200 CE (Little Ice Age 1400-1800 CE) supporting previous reconstructions that warmer (cooler) SST are linked to both reduced (enhanced) phytoplankton productivity. Additionally, cool (warm) SST were also associated with dry (wet) conditions in the American Southwest indicating that changes in the PDO has had a significant impact on drought

  4. Environmental biogeography of near-surface phytoplankton in the southeast Pacific Ocean

    Science.gov (United States)

    Hardy, John; Hanneman, Andrew; Behrenfeldt, Michael; Horner, Rita

    1996-10-01

    Biogeographic interpretation of large-scale phytoplankton distribution patterns in relation to surface hydrography is essential to understanding pelagic food web dynamics and biogeochemical processes influencing global climate. We examined the abundance and biomass of phytoplankton in relation to physical and chemical parameters in the southeast Pacific Ocean. Samples were collected along longitude 110°W, between 10°N and 60°S during late austral summer. Patterns of taxa abundance and hydrographic variables were interpreted by principal components analysis. Five distinct phytohydrographic regions were identified: (i) a north equatorial region of moderate productivity dominated by small flagellates, low nitrate and low-to-moderate pCO 2; (ii) a south equatorial region characterized by high primary productivity dominated by diatoms, high nutrient levels, and relatively high pCO 2; (iii) a central gyre region characterized by low productivity dominated by small flagellates, low nitrate, and high pCO 2; (iv) a sub-Antarctic region with moderate productivity dominated by coccolithophores, moderate nitrate concentrations, and low pCO 2; and (v) an Antarctic region with high productivity dominated by diatoms, very high nitrate, and low pCO 2. Productivity and average phytoplankton cell size were positively correlated with nitrate concentration. Total phytoplankton abundance was negatively correlated with pCO 2, photosynthetically active radiation, and ultraviolet-B radiation. The interaction between phytoplankton carbon assimilation, atmospheric CO2, and the inhibitory effect of ultraviolet radiation could have implications for the global climate. These data suggest that the effects would be greatest at southern mid-latitudes (40-50°S) where present phytoplankton production and predicted future increases in UV-B are both relatively high.

  5. Progress Towards a Global Understanding of Plankton Dynamics: The Global Alliance of CPR Surveys (GACS)

    Science.gov (United States)

    Batten, S.; Richardson, A.; Melrose, C.; Muxagata, E.; Hosie, G.; Verheye, H.; Hall, J.; Edwards, M.; Koubbi, P.; Abu-Alhaija, R.; Chiba, S.; Wilson, W.; Nagappa, R.; Takahashi, K.

    2016-02-01

    The Continuous Plankton Recorder (CPR) was first used in 1931 to routinely sample plankton and its continued deployment now sustains the longest-running, and spatially most extensive marine biological sampling programme in the world. Towed behind, for the most part commercial, ships it collects plankton samples from the surface waters that are subsequently analysed to provide taxonomically-resolved abundance data on a broad range of planktonic organisms from the size of coccolithophores to euphausiids. Plankton appear to integrate changes in the physical environment and by underpinning most marine food-webs, pass on this variability to higher trophic levels which have societal value. CPRs are deployed increasingly around the globe in discrete regional surveys that until recently interacted in an informal way. In 2011 the Global Alliance of CPR Surveys (GACS) was launched to bring these surveys together to collaborate more productively and address issues such as: methodological standardization, data integration, capacity building, and data analysis. Early products include a combined global database and regularly-released global marine ecological status reports. There are, of course, limitations to the exploitation of CPR data as well as the current geographic coverage. A current focus of GACS is integration of the data with models to meaningfully extrapolate across time and space. In this way the output could be used to provide more robust synoptic representations of key plankton variables. Recent years have also seen the CPR used as a platform in itself with the inclusion of additional sensors and water samplers that can sample the microplankton. The archive of samples has already been used for some molecular investigations and curation of samples is maintained for future studies. Thus the CPR is a key element of any regional to global ocean observing system of biodiversity.

  6. Dynamics of living phytoplankton: Implications for paleoenvironmental reconstructions

    Energy Technology Data Exchange (ETDEWEB)

    Barbosa, A B [Centre for Marine and Environmental Research (CIMA), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro (Portugal)], E-mail: abarbosa@ualg.pt

    2009-01-01

    Phytoplankton is the dominant primary producer in aquatic ecosystems and is considered a gauge of ecological condition and change. Some phytoplankton groups, namely diatoms, dinoflagellates, and coccolithophores, produce morphological or chemical fossils that can be used for paleoenvironmental reconstruction. This study aims to review the processes that regulate dynamics in living phytoplankton and to highlight how this knowledge is used in paleoecological studies. The distribution patterns of phytoplankton in present-day aquatic ecosystems are shaped by the interplay between processes that regulate cell growth and cell death. Cell growth and cell death are regulated by the internal environment of phytoplankton (e.g., specific environmental tolerances, resource uptake properties, cell size, density and morphology, alternative nutritional strategies such as mixotrophy or N{sub 2} uptake, motility, intracellular storage capacities, grazing resistance properties), and by its external environment. The external environment includes variables dependent on the availability of resources (e.g., light intensity, concentration of CO{sub 2} and dissolved inorganic macronutrients and micronutrients, availability of living prey in case of mixotrophs) and variables independent of resources (e.g., temperature, salinity, turbulence, ultraviolet radiation, bioactive compounds, activity of grazers, viruses, and eukaryotic parasites). The importance of recently described loss processes, such as grazing by phagotrophic protists, viral lyses, and programmed cell death, is discussed in the context of its potential impact upon phytoplankton vertical fluxes. Examples of the use of different phytoplankton metrics (e.g. abundance, species composition, species morphology, and elemental composition) to infer contemporaneous as well as past environmental and ecological conditions are critically evaluated.

  7. Dynamics of living phytoplankton: Implications for paleoenvironmental reconstructions

    International Nuclear Information System (INIS)

    Barbosa, A B

    2009-01-01

    Phytoplankton is the dominant primary producer in aquatic ecosystems and is considered a gauge of ecological condition and change. Some phytoplankton groups, namely diatoms, dinoflagellates, and coccolithophores, produce morphological or chemical fossils that can be used for paleoenvironmental reconstruction. This study aims to review the processes that regulate dynamics in living phytoplankton and to highlight how this knowledge is used in paleoecological studies. The distribution patterns of phytoplankton in present-day aquatic ecosystems are shaped by the interplay between processes that regulate cell growth and cell death. Cell growth and cell death are regulated by the internal environment of phytoplankton (e.g., specific environmental tolerances, resource uptake properties, cell size, density and morphology, alternative nutritional strategies such as mixotrophy or N 2 uptake, motility, intracellular storage capacities, grazing resistance properties), and by its external environment. The external environment includes variables dependent on the availability of resources (e.g., light intensity, concentration of CO 2 and dissolved inorganic macronutrients and micronutrients, availability of living prey in case of mixotrophs) and variables independent of resources (e.g., temperature, salinity, turbulence, ultraviolet radiation, bioactive compounds, activity of grazers, viruses, and eukaryotic parasites). The importance of recently described loss processes, such as grazing by phagotrophic protists, viral lyses, and programmed cell death, is discussed in the context of its potential impact upon phytoplankton vertical fluxes. Examples of the use of different phytoplankton metrics (e.g. abundance, species composition, species morphology, and elemental composition) to infer contemporaneous as well as past environmental and ecological conditions are critically evaluated.

  8. Late Quaternary high resolution micropaleontological and sedimentological records in the Gulf of Cadiz.

    Science.gov (United States)

    Balestra, B.; Ducassou, E.; Zarikian, C.; Bout-Roumazeilles, V.; Flores, J. A.; Paytan, A.

    2017-12-01

    We present preliminary micropaleontological and sedimentological data from IODP Site U1390 (Expedition 339), located in the central middle slope of the Gulf of Cadiz, since the last glaciation. This site has been targeted for reconstruction of regional paleo-circulation as it shows particularly high sedimentation rates, throughout the Holocene and the Last Glacial Maximum (LGM). We use micropaleontological and sedimentological proxies to understand the bottom current variations through time and the ecological conditions at the sea surface (planktonic foraminifer, pteropod and nannofossil assemblages), and the sea bottom (ostracod assemblages). Eleven samples, chosen at transitions of planktonic foraminifer assemblages, have been dated by AMS radiocarbon analyses. Preliminary results from benthic ostracod assemblages show variations in bottom water ventilation and food supply. Planktonic foraminifer assemblages clearly show the well-known cold events of this period such as the Younger Dryas and Heinrich stadial associated to coarser sediment, and warmer phases such as the Bölling-Allerød associated to muddy sediment. Other bio-events within the Holocene period are also recorded. The preservation of the coccolithophore assemblages is good to moderate. Coccolith abundances (expressed in coccoliths/gr of sediment) show higher values during the Holocene and generally are like assemblages previously reported for the same area. Implications for characterization of the Holocene, the last termination and LGM ecological conditions at high resolution and their potential fluctuations (i.e. amplitude and magnitude) under the influence of the lower core of the Mediterranean Outflow Water (MOW), with this multi proxy approach based on sedimentological, and paleontological data will be discussed.

  9. Exploring the potential of clumped isotope thermometry on coccolith-rich sediments as a sea surface temperature proxy

    Science.gov (United States)

    Drury, Anna Joy; John, Cédric M.

    2016-10-01

    Understanding past changes in sea surface temperatures (SSTs) is crucial; however, existing proxies for reconstructing past SSTs are hindered by unknown ancient seawater composition (foraminiferal Mg/Ca and δ18O) or reflect subsurface temperatures (TEX86) or have a limited applicable temperature range (U37k'). We examine clumped isotope (Δ47) thermometry to fossil coccolith-rich material as an SST proxy, as clumped isotopes are independent of original seawater composition and applicable to a wide temperature range and coccolithophores are widespread and dissolution resistant. The Δ47-derived temperatures from 63 μm fraction removes most nonmixed layer components; however, the Δ47-derived temperatures display an unexpected slight decreasing trend with decreasing size fraction. This unexpected trend could partly arise because larger coccoliths (5-12 μm) are removed during the size fraction separation process. The c1 and <63 μm c2 Δ47-derived temperatures are comparable to concurrent U37k' SSTs. The <20, <10, and 2-5 μm c2 Δ47-derived temperatures are consistently cooler than expected. The Δ47-U37k' temperature offset is probably caused by abiotic/diagenetic calcite present in the c2 2-5 μm fraction (˜53% by area), which potentially precipitated at bottom water temperatures of ˜6°C. Our results indicate that clumped isotopes on coccolith-rich sediment fractions have potential as an SST proxy, particularly in tropical regions, providing that careful investigation of the appropriate size fraction for the region and time scale is undertaken.

  10. Habitat suitability and ecological niches of different plankton functional types in the global ocean

    Science.gov (United States)

    Vogt, Meike; Brun, Philipp; Payne, Mark R.; O'Brien, Colleen J.; Bednaršek, Nina; Buitenhuis, Erik T.; Doney, Scott C.; Leblanc, Karine; Le Quéré, Corinne; Luo, Yawei; Moriarty, Róisín; O'Brien, Todd D.; Schiebel, Ralf; Swan, Chantal

    2013-04-01

    Marine plankton play a central role in the biogeochemical cycling of important elements such as carbon, nitrogen, and sulphur. While our knowledge about marine ecosystem structure and functioning is still scarce and episodic, several recent observational studies confirm that marine ecosystems have been changing due to recent climate change, overfishing, and coastal eutrophication. In order to better understand marine ecosystem dynamics, the MAREDAT initiative has recently collected abundance and biomass data for 5 autotrophic (diatoms, Phaeocystis, coccolithophores, nitrogen fixers, picophytoplankton), and 6 heterotrophic plankton functional types (PFTs; bacteria, micro-, meso- and macrozooplankton, foraminifera and pteropods). Species distribution models (SDMs) are statistical tools that can be used to derive information about species habitats in space and time. They have been used extensively for a wide range of ecological applications in terrestrial ecosystems, but here we present the first global application in the marine realm, which was made possible by the MAREDAT data synthesis effort. We use a maximum entropy SDM to simulate global habitat suitability, habitat extent and ecological niches for different PFTs in the modern ocean. Present habitat suitability is derived from presence-only MAREDAT data and the observed annual and monthly mean levels of physiologically relevant variables such as SST, nutrient concentration or photosynthetic active radiation received in the mixed layer. This information can then be used to derive ecological niches for different species or taxa within each PFT, and to compare the ecological niches of different PFTs. While these results still need verification because data was not available for all ocean regions for all PFTs, they can give a first indication what present and future plankton habitats may look like, and what consequences we may have to expect for future marine ecosystem functioning and service provision in a warmer

  11. Latitudinal phytoplankton distribution and the neutral theory of biodiversity

    KAUST Repository

    Chust, Guillem

    2012-11-16

    Recent studies have suggested that global diatom distributions are not limited by dispersal, in the case of both extant species and fossil species, but rather that environmental filtering explains their spatial patterns. Hubbell\\'s neutral theory of biodiversity provides a framework in which to test these alternatives. Our aim is to test whether the structure of marine phytoplankton (diatoms, dinoflagellates and coccolithophores) assemblages across the Atlantic agrees with neutral theory predictions. We asked: (1) whether intersite variance in phytoplankton diversity is explained predominantly by dispersal limitation or by environmental conditions; and (2) whether species abundance distributions are consistent with those expected by the neutral model. Location: Meridional transect of the Atlantic (50° N-50° S). Methods: We estimated the relative contributions of environmental factors and geographic distance to phytoplankton composition using similarity matrices, Mantel tests and variation partitioning of the species composition based upon canonical ordination methods. We compared the species abundance distribution of phytoplankton with the neutral model using Etienne\\'s maximum-likelihood inference method. Results: Phytoplankton communities are slightly more determined by niche segregation (24%), than by dispersal limitation and ecological drift (17%). In 60% of communities, the assumption of neutrality in species\\' abundance distributions could not be rejected. In tropical zones, where oceanic gyres enclose large stable water masses, most communities showed low species immigration rates; in contrast, we infer that communities in temperate areas, out of oligotrophic gyres, have higher rates of species immigration. Conclusions: Phytoplankton community structure is consistent with partial niche assembly and partial dispersal and drift assembly (neutral processes). The role of dispersal limitation is almost as important as habitat filtering, a fact that has been

  12. The role of nutricline depth in regulating the ocean carbon cycle.

    Science.gov (United States)

    Cermeño, Pedro; Dutkiewicz, Stephanie; Harris, Roger P; Follows, Mick; Schofield, Oscar; Falkowski, Paul G

    2008-12-23

    Carbon uptake by marine phytoplankton, and its export as organic matter to the ocean interior (i.e., the "biological pump"), lowers the partial pressure of carbon dioxide (pCO(2)) in the upper ocean and facilitates the diffusive drawdown of atmospheric CO(2). Conversely, precipitation of calcium carbonate by marine planktonic calcifiers such as coccolithophorids increases pCO(2) and promotes its outgassing (i.e., the "alkalinity pump"). Over the past approximately 100 million years, these two carbon fluxes have been modulated by the relative abundance of diatoms and coccolithophores, resulting in biological feedback on atmospheric CO(2) and Earth's climate; yet, the processes determining the relative distribution of these two phytoplankton taxa remain poorly understood. We analyzed phytoplankton community composition in the Atlantic Ocean and show that the distribution of diatoms and coccolithophorids is correlated with the nutricline depth, a proxy of nutrient supply to the upper mixed layer of the ocean. Using this analysis in conjunction with a coupled atmosphere-ocean intermediate complexity model, we predict a dramatic reduction in the nutrient supply to the euphotic layer in the coming century as a result of increased thermal stratification. Our findings indicate that, by altering phytoplankton community composition, this causal relationship may lead to a decreased efficiency of the biological pump in sequestering atmospheric CO(2), implying a positive feedback in the climate system. These results provide a mechanistic basis for understanding the connection between upper ocean dynamics, the calcium carbonate-to-organic C production ratio and atmospheric pCO(2) variations on time scales ranging from seasonal cycles to geological transitions.

  13. Stratigraphic Evolution of Brazos-Trinity Basin IV, Western Gulf of Mexico: Preliminary Results of IODP Expedition 308

    Science.gov (United States)

    Pirmez, C.; Behrmann, J.; Flemings, P. B.; John, C.

    2005-12-01

    IODP Expedition 308 drilled three sites across Brazos-Trinity Basin IV, at the terminal end of a system of four salt-withdrawal intra-slope basins offshore Texas. A 175 m thick succession of sand-rich turbidite fans, mass-transport deposits and hemipelagic sediments was deposited within the last ~120 ka in Basin IV, as recorded at Site U1320. Pre-fan deposits dating back to MIS 6 form a conformable succession of laminated and bioturbated clays, deposited from distal turbidity currents and/or river plumes. The pre-fan succession is capped by a hemipelagic clay interpreted to represent the high stand of sea level during MIS 5e. The basal turbidite deposits in the basin are mud-rich, with the exception of the very first turbidity currents to enter the basin. This initial pulse, possibly derived from failure of older shelf edge deposits, accumulated an ~8 m thick sand-rich interval. A pause in turbidity current influx lasted 30 to 40 kyrs, beginning a few thousand years before ash layer Y8 dated at 84 ka and the Emiliana huxleyi acme. During MIS 3 to MIS 2 sand-rich fans containing 5-25 m thick packets of very fine to lower medium sand beds accumulated up to 130 m of sediments. A 2-3 m thick microfossil-rich clay marks the end of turbidity current influx into the basin during the Holocene. The sedimentary record of Brazos-Trinity Basin IV shows that the accumulation of turbidites in the terminal end of this source to sink depositional system reflects a complex interaction between the availability of material and the initiation of flows at the source near the shelf edge, the interaction of turbidity currents with complex slope topography, and the effects of salt tectonics and flow processes on modifying this topography. The initial results indicate that sealevel changes alone cannot explain the sedimentation patterns observed in the basin.

  14. Calcareous nannoplankton and benthic foraminiferal assemblages from the Nazare Canyon (Portuguese continental margin): Preliminary results

    International Nuclear Information System (INIS)

    Guerreiro, C; Oliveira, A; Rodrigues, A; Rosa, F; Cachao, M; Fatela, F

    2009-01-01

    Submarine canyons are assumed to play an important role in oceanic/neritic circulation, marine productivity and sedimentary processes, acting as preferential conduits between the littoral and deep oceanic domain. Here we present first results of a comparative micropalaeontological study on calcareous nannoplankton and benthic foraminifera from surface sediments from the surroundings of the upper Nazare Canyon (Portuguese continental margin) and from the shelf north of the canyon. Regardless of the difficulty to distinguish taphonomical from (palaeo)ecological effects in such a complex and still poorly known marine system, the first results suggest that the canyon's hydro-sedimentary dynamic regime act as a prolongation of the shore/inner shelf hydrodynamic conditions towards west, preventing deposition and/or preservation of the smaller and fragile species of calcareous nannoplankton (e.g. E. huxleyi and G. ericsonii) and enhancing the record of the larger and more opportunistic ones (e.g. G. oceanica); and disturbing benthic foraminiferal productivity and/or diversity, or their preservation in the fossil record. Both calcareous nannoplankton and benthic foraminifera are more abundant off the canyon's domain, suggesting that its highly energetic thalweg conditions are probably filtering the fossil record in the sediment. Still, preliminary results suggest that the occurrence of persistent physical phenomena related with the canyon's morphology and proximity to the coast (e.g. solitary internal waves) may be locally promoting favourable conditions for calcareous nannoplankton, as shown by high values of nannoliths, chlorophyll a and 19' hexanoyloxyfucoxantine (unpublished data) north of the canyon's head. It is our goal to test this hypothesis in the near future by (a) studying multicore and surficial sediments from more recent surveys, and (b) calibrating the sediment results with water column data presently in process at the Institute of Oceanography (IO).

  15. Calcareous nannoplankton and benthic foraminiferal assemblages from the Nazare Canyon (Portuguese continental margin): Preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Guerreiro, C; Oliveira, A; Rodrigues, A [Division of Marine Geology, Portuguese Hydrographic Institute (IH), Rua das Trinas 49, 1249-093 Lisboa (Portugal); Rosa, F [CIACOMAR, Algarve University, Av. 16 de Julho s/n 8700-311 Olhao (Portugal); Cachao, M; Fatela, F [Geology Center and Geology Department, FCUL, Bloco C6, 3o Piso, sala 6.3.57 Campo Grande 1749-016 Lisboa (Portugal)], E-mail: catarina.guerreiro@hidrografico.pt

    2009-01-01

    Submarine canyons are assumed to play an important role in oceanic/neritic ci