Dissertations / Theses: 'Coccolithophore'

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Pereira, Pagarete Antonio Joaquim. "Functional Genomics of Coccolithophore Viruses." Paris 6, 2010. http://hal.upmc.fr/tel-01111009v1.

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L’Emiliania huxleyi virus (EhV) est un NCLDV. Il appartient à la famille des virus algaux, les Phycodnaviridae. Il infect Emiliania huxleyi, le coccolithophore le plus abondant dans les océans modernes. Nous avons montré sur une base phylogénétique le transfert de 29 gènes entre le génome d’Emiliania huxleyi et de EhV, notamment 7 gènes impliqués dans la biosynthèse des sphingolipides (SBP). C’est le premier cas patent, dans un système de virus et phytoplancton eucaryotes, de transfert horizontal de multiples gènes d’enzymes liées fonctionnellement. Pour deux des plus importantes enzymes de la SBP, la sérine palmitoyl transférase et la dihydroceramide désaturase, l’étude transcriptomique a permis de définir trois étapes au cours de la formation et de la disparition des blooms de E. Huxleyi, pendant lesquelles on registre une activation progressive des transcrits de coccolithovirus, culminant avec leur contrôle de la SBP au cours des étapes 2 et 3. En utilisant la technique de puce à ADN on a réalisé la première étude transcriptomique globale entre l’hôte le virus au sein d’une communauté océanique naturel. Nos résultats montrent que durant les efflorescences de E. Huxleyi il y a un épisode synchrone de dominance virale qui est clairement visible à travers les signaux transcriptomiques qui en résultent. Parmi les gènes dont la quantité de transcrits augmentent significativement entre la pre et la post dominance virale on a trouvé des fonctions impliquées dans le transfert de l’information génétique, mais aussi des gènes probablement impliqués dans le contrôle post-transitionnel, dans les mécanismes de déplacement intracellulaires, ou même dans le contrôle de l’apoptose
Emiliania huxleyi Virus (EhV) is a giant nucleo-cytoplasmic double stranded DNA virus that belongs to the Phycodnavirus family. It has the capacity to infect Emiliania huxleyi, the most abundant coccolithophore in today’s oceans. Population dynamics of these eukaryotic microalgae is clearly controlled by the severe lytic action of EhV. After an extended bibliographic review on the current knowledge existing on these viruses, we present a series of bioinformatic and experimental analyses conducted to unveil important functional genomic features of the EhV. Evidence for the transfer of 29 genes between E. Huxleyi’s and the EhV genomes is presented. In particular, we investigate the origin of seven genes involved in the unique viral sphingolipid biosynthesis pathway (SBP) encoded in EhV genome. This is the first clear case of horizontal gene transfer of multiple functionally-linked enzymes in a eukaryotic host-virus system. We then focus on a field E. Huxleyi/EhV system from a mesocosm experiment in Norway. The dynamics of expression for two of the most important homologous, host and virus, genes of this pathway, serine palmitoyl transferase and dihydroceramide desaturase is investigated. Three defined transcriptional stages are reported during the bloom, with the coccolithovirus transcripts taking over and controlling the SBP. Finally, host and virus global transcript abundance occurring along the mesocosm experiment was investigated. The majority of the genes that significantly increased in abundance from pre to post viral takeover corresponded to viral sequences for which there is so far no match in the protein databases. Nonetheless, novel transcription features associated with EhV infection were discovered, namely the utilization of genes potentially related to genetic information processing, posttranslational control, intracellular trafficking mechanisms, and control of programmed cell death. As a conclusion, the entire dataset analysed herein is discussed, followed by the potential implications of these findings and future research perspectives in the field of plankton virology

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Walker, Jessica Mary. "Role of macromolecules in coccolithophore biomineralization." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/31401.

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Biomineralization refers to the production of mineralized tissues by organisms. The fine control which organisms can exert over this process produces crystals with morphologies and properties contrasting to that of non-biogenic crystals and specifically altered to suit the required functional need. A key model system of biomineralization are a unicellular marine algae, coccolithophores, which produce calcium carbonate scales known as coccoliths. These coccoliths are comprised of arrangements of single crystals of calcite interlocked to form a plate-shaped structure. Coccoliths are developed intracellularly in a specialised compartment called the coccolith vesicle, before being extruded to the cell surface. In this work, two vital components of the coccolith biomineralization process are investigated - a soluble polysaccharide thought to act as a habit modifier and an insoluble organic scaffold known as a baseplate that provides the surface for nucleation and growth of the crystals. Whilst both these elements are thought to play a key part in the biomineralization process, the role of each is not fully understood. To investigate the effect of coccolith-associated polysaccharides (CAPs) on nucleation and polymorph selection, two systems that promote different polymorphs of calcium carbonate were utilised. In both systems, the intracrystalline polysaccharide fraction extracted from one species, Gephyrocapsa oceanica, was able to promote calcite nucleation in vitro, even under conditions favouring the kinetically-privileged polymorphs of calcium carbonate: vaterite and aragonite. As this property is not observed with CAPs extracted from its 'sister species', Emiliania huxleyi, the in vivo function of CAPs may differ between the two species. Both cryo-transmission electron microscopy (cryoTEM) and scanning electron microscopy (SEM) were used to determine the mechanism of calcite growth in the presence of G. oceanica CAPs, showing its impact on the forming amorphous calcium carbonate (ACC), decreasing the size of the particles and producing irregular, angular particles. Using cryo-electron tomography (cryoET), it was possible to create a 3D representation of the structure of the baseplate from the coccolithophore Pleurochrysis carterae, revealing its two-sided organisation. Examination of several stages of the coccolith growth process demonstrated the interlocking nature of the calcite crystals that make up the coccolith and the progression of the crystal morphologies over time, and the interaction of these crystals with the baseplate rim. Additionally, the effect of inhibiting carbonic anhydrase (CA), an enzyme involved in the regulation of carbonate species, revealed that inhibition of CA can affect coccolithogenesis as well as cell proliferation.

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McClelland, Harry-Luke Oliver. "Carbon dioxide and coccolithophore physiology in ancient oceans." Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:8a787b15-54cc-4a4e-8350-879a912cfe22.

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Coccolithophores form an important and dynamically evolving component of the carbon cycle. These ubiquitous single-celled marine calcifying phytoplankton are re- sponsible for half of the calcium carbonate production in the modern surface ocean, and their adorning calcite plates (coccoliths), produced intracellularly, have con- tributed to sedimentary carbonate for over 200 million years. They constitute a significant control on the partitioning of carbon between the atmosphere, ocean and sedimentary reservoirs on timescales from the instantaneous to the geological. Coc- colithophores are also uniquely placed to record aspects of the carbonate chemistry of the surface ocean, because the carbon isotopic composition of the organic matter (d13Corg) and calcite (d13Ccal) that they produce is a function of many parameters, including ambient aqueous carbon dioxide concentration [CO2]. This thesis addresses the bidirectional interaction between coccolithophores and the carbon cycle in the geological past, by asking how cellular carbon fluxes relate to physical evidence that is preserved throughout geological time. First, I present and calibrate a novel rationale for size-normalising coccolith mass, and show that over two glacial-interglacial cycles, coccolithophores appear to calcify more under high [CO2] conditions; a result that is manifest on evolutionary timescales, and is necessarily elusive to experiments. Second, I investigate the parameters controlling d13Ccal and d13Corg in coccolithophores through in vivo experimentation, and devel- opment of a model of cellular isotopic fluxes. I show that so called "vital effects" in coccolithophores arise as a result of differences in calcification to photosynthesis ratios. Third, using a combination of novel and established protocols for extraction and isotopic analysis of specific organic molecules from fossils taxonomically separated by size, I show the very first size-specific geologic time series of coccolith-associated d13Corg, and the first time-series of size-separated coccolith d13Ccal over a glacial cycle. A novel means of inferring past carbon dioxide concentrations, based on an iterative inverse modelling approach, is presented and tested.

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Bretherton, Laura. "The combined effect of daylength and CO2 on coccolithophore physiology." Thesis, University of Essex, 2015. http://repository.essex.ac.uk/15321/.

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Atmospheric CO2 levels have been increasing at an accelerated rate for the last 250 years, much of which is absorbed by the oceans, resulting in a process called ocean acidification (OA). This phenomenon has the capacity to disrupt many marine biological processes that utilise carbon, in particular photosynthesis and calcification, and as such phytoplankton have been a main topic of OA studies. While research has accelerated over the last decade, establishing general trends still remains confounded by methodological inconsistencies. Coccolithophores, particularly the species Emiliania huxleyi, are both ecologically and biogeochemically important phytoplankton; however, one strain (NZEH) has produced highly varied results. Here, we present a multivariate analysis that suggests previous inconsistencies between past studies of NZEH may be driven by variance of the light:dark (L:D) cycle used for growth. Experimental analysis on NZEH showed that under a 14:10h L:D cycle, CO2 induces significantly slower growth rates and higher PIC and POC cell-1, but this effect is dampened under 24h of light. This was widened to encompass more taxa, including more isolates of E. huxleyi (PLY70-3, PLY124-3, RCC962), and two other species of coccolithophore; Gephyrocapsa oceanica and Coccolithus pelagicus. L:D cycle changed the observed OA response, with two main responses divided by biogeographical origin. In tropical taxa, 24h light enhanced the effects of increased photosynthesis, but dampened the decrease in calcification in response to CO2. For temperate taxa, 24h dampened both the increases in photosynthesis and calcification with CO2. Evaluation of photobiology reveals that both CO2 and longer photoperiods induce a “high light” acclimation response, and changes in coccosphere thickness suggest it has a photoprotective role. Finally, results from bioassay experiments on natural phytoplankton populations in the polar regions show that CO2 response is hard to predict and based on community composition and ambient starting conditions. This work serves to further highlight the importance of environmental variables that moderate the OA response in accurately understanding future biogeochemical cycles. Future models attempting to predict the impact of OA upon marine systems must critically account for interactive role of light availability.

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Berger, Christine [Verfasser]. "Coccolithophore response to modern and past ocean acidification events / Christine Berger." Kiel : Universitätsbibliothek Kiel, 2014. http://d-nb.info/1046832263/34.

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Kamlow, Meriam. "Molecular Study of Dimethylsulfoniopropionate (DMSP) Metabolism in the Coccolithophore Emiliania huxleyi." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for biologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-24207.

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The compatible solute dimethylsulfoniopropionate (DMSP) is made in prodigious amounts by many single-celled marine phytoplankton. Emiliania huxleyi is the most prominent coccolithophore, distributed across the world's oceans and forming regular blooms that can cover over hundred thousand square kilometers. The blooms act as an important source of dimethyl sulfide (DMS). The enzymatic cleavage of DMSP to DMS and either acrylate or a proton 3-hydroxypropionate (3-HP) appears via the action of the enzymes known generically as DMSP lyases. The emitted DMS can be transformed by DMS-consuming bacteria or released into the atmosphere and can be oxidized further to sulfate aerosols that form cloud condensation nuclei (CCN), which may influence global climate by increasing albedo. The metabolism of DMSP was investigated and compared in two E. huxleyi strains (NCMA1516 and 373) previously reported to exhibit low and high DMSP lyase activity, respectively. The EhDddD gene, encoding a putative DMSP lyase, was sequenced in both strains, and an expression analysis of EhDddD was performed. Furthermore, DMSP lyase activity was studied by determining extracellular DMS and DMSP concentrations and in vitro measurements of DMSP lyase activity (DLA).The amino acid sequence of EhDddD in 1516 contains an insertion of one amino acid at the N-terminus compared with 373, which may be aspartate or serine. The amino acid (aa) sequence contains eleven amino acid substitutions between 1516 and 373, of which six are non-conserved. EhDddD encodes an additional C-terminal protein domain of 200 amino acids in length that is missing in bacteria. The additional domain may be involved in the function of the protein or in the regulation of the protein. Expression of the EhDddD gene was 8.414 times higher in 373 than 1516, whereas in vitro DMSP lyase activity was observed to be 60.6 times higher in 373 than 1516. In determination of extracellular DMS and DMSP concentrations, extracts of both strains produced DMS from DMSP, but the DMS production was 0.8 times lower in 373 than 1516. The DMSP concentration in 373 was observed to be 1.2 time higher than 1516. These results did not correlate with in vitro DMSP lyase activity.These results suggest that the observed differences in DMSP lyase activity between E. huxleyi strains are due to structural differences and adaptation to different environmental conditions.

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Garcia-Soto, Carlos. "Evolution and structure of a shelf coccolithophore bloom in the western English Channel." Thesis, University of Southampton, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240659.

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Street, Christianne. "Palaeobiogeography of Early Cretaceous calcareous nannoplankton." Thesis, University College London (University of London), 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322002.

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D’Amario, Barbara. "Coccolithophore calcification, life-cycle dynamics and diversity response to a warming and acidifying Mediterranean Sea." Doctoral thesis, Universitat Autònoma de Barcelona, 2017. http://hdl.handle.net/10803/458602.

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RESUMEN Esta tesis se llevó a cabo bajo el proyecto “Acidificación oceánica del Mediterráneo europeo en un clima cambiante (MedSeA, por sus siglas en inglés)”, financiado por la Comisión Europea en el marco del Programa 7 (http://medsea-project.eu, número 265103). El proyecto MedSeA estimuló la investigación sobre el efecto combinado del calentamiento de los océanos y la acidificación en la biogeoquímica y los ecosistemas mediterráneos. La presente tesis se centra en los coccolitóforos, un grupo de fitoplancton calcificante fuertemente conectado al clima global a través del ciclo del carbono. Ambos estadios de vida calcificados (heterococolitóforos y holococolitóforos) de estas algas unicelulares se encuentran comúnmente en el Mar Mediterráneo. Aquí, la comunidad en general presenta un alto grado de diversidad de especies, aparentemente más alto que en el Mar Rojo adyacente y el Océano Atlántico. Por otra parte, el Mar Mediterráneo es un área sometida a fuertes oscilaciones estacionales ambientales y presiones antropogénicas. El Mar Mediterráneo està considerado un "punto caliente" para el cambio climático, estando entre las regiones oceánicas bajo un calentamiento y acidificación más rápidos. Se espera que estos procesos provoquen no sólo un aumento de las temperaturas y cambios en el sistema del carbonato, sino también intensificar la estratificación de la columna de agua. Se prevé que tales cambios ambientales influirán en las poblaciones de cocolitóforos, de formas que aún no se entienden. Esta tesis contribuye a la comprensión de las respuestas de los cocolitóforos a un Mar Mediterráneo cambiante basada en i) muestras de agua recogidas a lo largo de un transecto O-E durante el “MedSeA Ocean Research Cruise” (crucero de investigación oceánica de MedSeA) (https://medseaocancruise.wordpress.com), que capturó su población regional y diversidad (Capítulos II, III, IV); y ii) muestras de agua colectadas durante el experimento de mesocosmos “MedSeA Crete” (https://medseacrete2013.wordpress.com), que probó los efectos combinados del calentamiento oceánico y de la acidificación en el ecosistema pelágico oligotrófico del Mediterráneo Oriental bajo limitación de nutrientes (Capítulo V). Estos dos conjuntos de observaciones permitieron el examen de varios aspectos de la población de cocolitóforos, tales como: i) la masa media del cocolito de Emiliania huxleyi, su distribución y los principales controles morfológicos / ambientales (Capítulo II); ii) las abundancias absolutas de heterococolitóforo y holococolitóforo, sus distribuciones relativas, patrones de diversidad y hipotéticos desencadenantes de las transformaciones de la fase de vida (Capítulo III y IV); y iii) la variabilidad en la abundancia absoluta de la población total de cocolitóforos, heterococolitóforos y holococolitóforos totales, y de las especies predominantes (E. huxleyi, Rhabdosphaera spp.) en la comunidad de cocolitóforos bajo calentamiento y acidificación en un entorno oligotrófico (Capítulo V). En general, los resultados presentados en esta tesis sugieren que los cocolitóforos que habitan el Mar Mediterráneo serán influenciados de diversas maneras por las perturbaciones ambientales proyectadas: la masa promedio del cocolito de E. huxleyi cambiará, siguiendo cambios futuros en la proporción de las variedades de calcificación y probablemente causando cambios en la producción y exportación de carbonato en el Mar Mediterráneo; la fase haploide podría ser favorecida sobre la fase diploide en muchas especies de cocolitóforos, aumentando en última instancia la proporción de los holo- sobre los hetero-cocolitóforos y la diversidad de los holococolitóforos; en el Mediterráneo Oriental, el calentamiento y la limitación de nutrientes, antes que la acidificación, tienden a reducir la población total de cocolitóforos, aunque los crecimientos óptimos específicos de las especies y cepas pueden modular esta respuesta.
SUMMARY This thesis was conducted under the “European Mediterranean Sea Acidification in a changing climate” (MedSeA) project, funded by the European Commission under Framework Program 7 (http://medsea-project.eu; grant number 265103). The MedSeA project stimulated research on the combined effect of ocean warming and acidification on Mediterranean biogeochemistry and ecosystems. The present thesis focuses on coccolithophores, a group of calcifying phytoplankton tightly connected to the global climate through the carbon cycle. Both calcified life stages (heterococcolithophores and holococcolithophores) of these unicellular algae are commonly found in the Mediterranean Sea. Here, the overall community presents a high degree of species diversity, apparently higher than in the adjacent Red Sea and Atlantic Ocean. On the other hand, the Mediterranean Sea is an area subject to strong environmental seasonal oscillations and anthropogenic pressures. The Mediterranean Sea is considered a “hot spot” for climate change, being among the oceanic regions under faster warming and acidification. These processes are expected to cause not only a rise in temperatures and shifts in the carbonate system, but also to enhance water column stratification. It is anticipated that such environmental changes will influence the coccolithophore populations, in ways that are not yet understood. This thesis contributes to the understanding of coccolithophore responses to a changing Mediterranean Sea based on i) water samples collected along a W-E transect during the MedSeA Ocean Research Cruise (https://medseaoceancruise.wordpress.com), which captured their regional population and diversity (Chapters II, III, IV); and ii) water samples collected during the MedSeA Crete mesocosm experiment (https://medseacrete2013.wordpress.com), which tested the combined effects of ocean warming and acidification on the oligotrophic Eastern Mediterranean pelagic ecosystem under nutrient limitation (Chapter V). These two sets of observations allowed the examination of several aspects of the coccolithophore population such as i) the average coccolith mass of Emiliania huxleyi, its distribution and the main morphological / environmental controls (Chapter II); ii) the heterococcolithophore and holococcolithophore absolute abundances, their relative distributions, diversity patterns, and hypothetical triggers of life phase transformations (Chapter III and IV); and iii) the variability in absolute abundance of the total coccolithophore population, total heterococcolithophores and holococcolithophores, and of the predominant species (E. huxleyi, Rhabdosphaera spp.) in the coccolithophore community under warming and acidification in an oligotrophic setting (Chapter V). Overall, the results presented in this thesis suggest that coccolithophores inhabiting the Mediterranean Sea will be influenced in various ways by projected environmental perturbations: E. huxleyi average coccolith mass will change, following future shifts in the proportion of calcification varieties and likely cause changes in the carbonate export production in the Mediterranean Sea; the haploid phase could be favoured over the diploid phase in many coccolithophore species, ultimately increasing the proportion of holo- over hetero-coccolithophores and holococcolithophore diversity; in the Eastern Mediterranean Sea, warming and nutrient limitation, rather than acidification, tend to reduce the total coccolithophore population, although species specific and strain specific growth optima may modulate this response.

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Rosas, Navarro Anaid. "Impact of ocean warming and acidification on coccolithophore ecology and calcification in the North Pacific." Doctoral thesis, Universitat Autònoma de Barcelona, 2018. http://hdl.handle.net/10803/664186.

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Los cocolitofóridos son fitoplancton calcificante unicelular cosmopolita involucrado en importantes ciclos biogeoquímicos globales. Esta tesis doctoral se centra en los impactos del calentamiento del océano y la acidificación sobre la morfología y la calcificación de los cocolitofóridos, con especial atención a la especie cosmopolita y dominante Emiliania huxleyi. El estudio incluye experimentos de temperatura usando cepas de E. huxleyi aisladas en el noroeste del océano Pacífico, y el análisis de muestras de agua colectadas a lo largo de un transecto que cubre aguas del Golfo de California y del margen NE del oceáno Pacífico. Este tipo de trabajo es oportuno dado que el calentamiento global y el rápido aumento del CO2 antropogénico en la atmósfera tienen consecuencias notables en el medio marino. Para aclarar discrepancias que aparecen en la literatura sobre la respuesta de la calcificación a los cambios de temperatura, comparamos tres cepas de E. huxleyi cultivadas bajo condiciones no limitantes de nutrientes ni de luz, a 10, 15, 20 y 25 ºC de temperatura. Las tres cepas mostraron tasas de crecimiento similares en función de la temperatura, con un óptimo en los 20–25 ºC. Se correlacionaron positivamente con la temperatura: la tasa de producción de cocolitos y de elementos particulados (carbono inorgánico particulado (PIC), carbono orgánico particulado (POC), nitrógeno particulado total (TPN)), la masa y tamaño del cocolito, el ancho del ciclo de elementos del tubo de los cocolitos, el número de cocolitos en la cocosfera, la masa de la cocosfera, y la velocidad de hundimiento y la relación PIC : POC de las células individuales. La correlación entre la producción de PIC y la masa/tamaño del cocolito apoya la noción de que la masa del cocolito se puede usar como proxy para la producción de PIC en muestras de sedimentos. Encontramos que los cocolitos incompetos no se deben a la escasez de tiempo a altas producciones de PIC. Las temperaturas de crecimiento subóptimas aumentan el porcentaje de coccolitos malformados en algunas cepas. La relación PIC : POC mostró un mínimo a la temperatura óptima de crecimiento. En el contexto del cambio climático, el calentamiento global podría causar una disminución en la contribución del PIC exportado de los cocolitofóridos, podría ser una conveniencia en algunos genotipos debido a una menor cantidad de malformaciones de cocolitos y podría influir de manera importante sobre las velocidades de hundimiento. Dado que el calentamiento, la acidificación y la menor disponibilidad de nutrientes pueden ocurrir simultáneamente en los escenarios de cambio climático, existe la pregunta sobre cuál será el efecto neto de los diferentes factores de influencia. Aquí analizamos 68 muestras de agua abarcando una amplia gama de condiciones. Enfocamos el estudio en las principales variaciones morfológicas y de morfotipo de la especie E. huxleyi, y también en las diferentes especies del género Gephyrocapsa. Descubrimos que E. huxleyi tipo O es un morfotipo más frío potenciado por concentraciones más altas de amonio y es más tolerante a valores de pH más bajos que el morfotipo A. El morfotipo A sobre-calcificado compartió nicho con el morfotipo O. Las aberraciones morfológicas observadas y la morfología sub-calcificada se asociaron a condiciones desfavorables, tales como bajas (aunque no las más bajas) concentraciones de nutrientes. La contribución de PIC por litro de G. oceanica fue más alta que la de E. huxleyi, en tercer lugar fue la de G. muellerae. Gephyrocapsa oceanica presentó la mayor afinidad a las aguas más cálidas con menores concentraciones de nutrientes, y G. muellerae la mayor tolerancia a un pH más bajo. En el contexto del cambio climático, G. oceanica y G. muellerae podrían aumentar su abundancia relativa, generando cambios en la producción de PIC.
Coccolithophores are cosmopolitan unicellular calcifying phytoplankton involved in important biogeochemical global cycles. This PhD thesis focuses on the impacts of ocean warming and acidification on the morphology and calcification of coccolithophores, with special attention to the cosmopolitan and dominant species Emiliania huxleyi. The study includes temperature experiments using three strains of E. huxleyi isolated in the NW Pacific Ocean, and the analysis of water samples collected along a transect covering the Gulf of California and NE Pacific margin waters. This type of work is timely since global warming and the rapid increase in anthropogenic atmospheric CO2 have remarkable consequences on the marine environment. To clarify discrepancies featuring in the literature about the calcification response to temperature changes, we compared three strains of E. huxleyi grown under non-limiting nutrient and light conditions, at 10, 15, 20 and 25 ºC of temperature. All three strains displayed similar growth rate versus temperature relationships, with an optimum at 20–25 ºC. Over the sub-optimum to optimum temperature range (10–25 ºC), elemental production (particulate inorganic carbon (PIC), particulate organic carbon (POC), total particulate nitrogen (TPN)), coccolith mass, coccolith size, width of the tube element cycle, number of attached coccoliths per coccosphere, coccosphere mass, individual sinking velocity, individual cell PIC : POC ratio, and coccolith production rate, were positively correlated with temperature. 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. We found 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. The PIC : POC ratio showed a minimum at optimum growth temperature in all investigated strains. In the context of climate change, global warming might cause a decline in coccolithophore’s PIC contribution to the rain ratio, as well as improved fitness in some genotypes due to fewer coccolith malformations; our data also point to an important influence of global warming on sinking velocities. Given that warming, acidification, and lowered nutrient availability might occur simultaneously under climate change scenarios, there is the question about what the net effect of different influential factors will be. Therefore, we analysed 68 summertime samples along a transect at different stations and depths, giving a large range of conditions. The studied regions are expected to be particularly susceptible to both warming and acidification, and are characterized by high seasonal primary production through upwelling events. We focused the study on the coccosphere standing stock variations of the main morphotypes and morphological variations of the species E. huxleyi and on the different species of the genus Gephyrocapsa. We found that E. huxleyi type O is a colder morphotype enhanced by higher ammonium concentrations and is more tolerant to lower pH values than the morphotype A. The over-calcified E. huxleyi type A shared niche with the morphotype O. The observed morphological aberrations and the under-calcified morphology were associated to unfavorable conditions for the cell such as low (though not the lowest) nutrient concentrations. The PIC contribution per liter of G. oceanica was higher than that of E. huxleyi, in third place was that of G. muellerae. Gephyrocapsa oceanica presented the highest affinity to warmer waters with lower nutrient concentrations, and G. muellerae the highest tolerance to lower pH. In the context of climate change, G. oceanica and G. muellerae might increase their relative abundance with subsequent changes in the coccolithophore PIC production.

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Landry, Dori M. "Characterization of nitrogen- and phosphorus-regulated cell-surface proteins in the marine coccolithophore, Emiliania huxleyi." Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2006. http://wwwlib.umi.com/cr/ucsd/fullcit?p3223020.

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Thesis (Ph. D.)--University of California, San Diego, 2006.
Title from first page of PDF file (viewed September 21, 2006). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.

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Salmon, Deborah Louise. "Metabolite profiling of the coccolithophore Emiliania huxleyi to examine links between calcification and central metabolism." Thesis, University of Exeter, 2013. http://hdl.handle.net/10871/14932.

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Coccolithophores are single-celled marine phytoplankton, which produce intricate calcium carbonate platelets or ‘coccoliths’. Emiliania huxleyi is the most abundant and widespread coccolithophore, and is one of the most productive calcifying species on earth, playing a key role in global carbon, carbonate and sulphur cycles. Despite much research into coccolithophore biology, the underlying function of their coccoliths is still unknown. The main aim of the research reported in this thesis was to examine the impact of calcification on metabolism in coccolithophores. Calcification is a significant global process, so it is important to discover what effect it has on the metabolism of cells. The major metabolites each have different costs and benefits to the cell, which will vary depending on the habitat and environmental conditions the cell is in. By comparing the metabolite profiles of different strains, including calcifying, non-calcifying, haploid and diploid cells, differences in metabolite composition and potential patterns related to cell type were investigated. Low molecular weight (LMW) metabolites were characterised using a combination of metabolomic techniques. In agreement with previous research, dimethylsulphoniopropionate (DMSP) was the most abundant compound, followed by mannitol and glycine betaine (GBT). Less abundant sugars, polyols and amino acids were also identified. Environmental factors were manipulated to investigate how the principal metabolites were affected by salinity, different light intensities and nutrient (phosphate and nitrate) limitation. The data revealed a striking difference between haploid and diploid cells of the same strain, with the haploid containing lower concentrations of most of the major metabolites. Thus it is proposed that haploid cells have a different osmoregulatory strategy from the diploid cells. A negative correlation was found between DMSP and mannitol, suggesting that mannitol has a dual function, not only as a major storage compound but also as a principal compatible solute. Untargeted metabolite profiling is becoming a popular tool to investigate phenotypes and varying environmental conditions. LC-ESI-QTOF-MS/MS analyses of a wide range of metabolites showed that it is an effective method to identify differences and similarities between E. huxleyi strains grown in different conditions. Strain and growth phase appear to be the more important factors in differentiating metabolite profiles. Surprisingly there were no obvious metabolite profiling differences between calcifying and non-calcifying cells. Untargeted analysis can, however, be used to identify the compounds that did display differences, and which may be important biomarkers, so warrant further investigation. A range of metabolite profiling techniques highlighted important differences between strains, which will hopefully lead onto further research into the metabolome of E. huxleyi, and the unravelling of important metabolic pathways. There has been little research into the LMW metabolites of E. huxleyi, and especially comparisons between strains. Thus the use of metabolomics is a novel way to investigate the difference between cell types and the possible functions of calcification.

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Schlüter, Lothar [Verfasser]. "Long-term adaptation of the coccolithophore Emiliania huxleyi to ocean acidification and global warming / Lothar Schlüter." Kiel : Universitätsbibliothek Kiel, 2016. http://d-nb.info/1088401104/34.

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Schwab, Christian [Verfasser]. "Late Quaternary changes in paleoproductivity and hydrography in the Azores region deduced from coccolithophore assemblages / Christian Schwab." Kiel : Universitätsbibliothek Kiel, 2013. http://d-nb.info/1035182114/34.

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Herfort, Lydie Marie-Claude Catherine. "Photosynthesis and calcification in the coccolithophore, Emiliania huxleyi, and two hermatypic corals, Porites porites and Acropora sp." Thesis, Queen Mary, University of London, 2002. http://qmro.qmul.ac.uk/xmlui/handle/123456789/28588.

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Most global calcification is carried out by organisms which are also photosynthetic. In this study, the coccolithophore Emiliania huxleyi (Lohmann) Hay and Mohler and two species of hermatypic coral were used to: examine the effect of dissolved inorganic carbon (DIC) and light on photosynthesis and calcification; and determine the extent to which these two processes interact. A novel method of producing coccolith-less (non-calcifying) cells from calcifying cells of the same strain of E huxley! was developed thus allowing photosynthesis and calcification to be studied separately. The kinetics of photosynthesis in both types of cell, and of calcification in coccolith-bearing cells, were shown to be biphasic with respect to DIC concentration. The hiatus in all three cases was located at 1 mM DIC. This unusual pattern was shown to be the product of two carbon uptake mechanisms: an anion exchanger working at all DIC concentrations and an external carbonic anhydrase active only at low DIC concentrations. In contrast to the commonly-held view, this study demonstrated that calcification did not promote photosynthesis in E. huxleyi. Nevertheless, there was clearly strong biological control of calcification in this alga since DIC uptake was mediated by an anion transporter and a dehydroxylating enzyme. This work also showed that in E huxleyi, DIC addition enhanced photosynthesis at both limiting and saturating photon flux densities and that bicarbonate affected photochemical processes directly. Photosystem II activity was stimulated and non-photochemical quenching was reduced, possibly protecting the photosynthetic apparatus from damage by light. In the two corals; Porites porites and Acropora sp., strong biological control of calcium carbonate precipitation was also evident. Again, calcification did not stimulate photosynthesis. Calcification rates of Acropora sp. were monitored in the dark and although these were lower than in the light, they still increased dramatically with bicarbonate addition. This showed that high concentrations of the bicarbonate ion can compensate for the lack of light. Hence, it seems that in hermatypic corals, light-dependence of calcification may be facultative and not obligate. It is therefore clear from the results of this study that calcification and photosynthesis are not as closely coupled as has been previously thought. In neither E. huxleyi, nor in the hermatypic corals, were photosynthetic and calcification rates saturated at the present ambient DIC concentration of seawater.

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Lezius, Jeannette [Verfasser]. "Impact of the closing Panamanian seaway in the late Miocene to Pliocene on coccolithophore evolution, biogeography and palaeoproductivity / Jeannette Lezius." Kiel : Universitätsbibliothek Kiel, 2009. http://d-nb.info/101981201X/34.

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Boller, Amanda J. "Stable carbon isotope discrimination by rubisco enzymes relevant to the global carbon cycle." Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4291.

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Five different forms of ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO; IA, IB, IC, ID, II), the carboxylase of the Calvin-Benson-Bassham cycle (CBB), are utilized by plants, algae and autotrophic bacteria for carbon fixation. Discrimination against 13C by RubisCO is a major factor dictating the stable carbon isotopic composition (δ13C = {[13C/12C sample/13C/12C standard] - 1} X 1000) of biomass. To date, isotope discrimination, expressed as ε values (={[12k/13k] - 1} X 1000; 12k and 13k = rates of 12C and 13C fixation) has been measured for form IA, IB, and II RubisCOs from only a few species, with ε values ranging from 18 to 29 /. The aim of this study was to better characterize form ID and IC RubisCO enzymes, which differ substantially in primary structure from the IB enzymes present in many cyanobacteria and organisms with green plastids, by measuring isotopic discrimination and kinetic parameters (KCO2 and Vmax). Several major oceanic primary producers, including diatoms, coccolithophores, and some dinoflagellates have form ID RubisCO, while form IC RubisCO is present in many proteobacteria of ecological interest, including marine manganese-oxidizing bacteria, some nitrifying and nitrogen-fixing bacteria, and extremely metabolically versatile organisms such as Rhodobacter sphaeroides. The ε - values of the form ID RubisCO from the coccolithophore, Emiliania huxleyi and the diatom, Skeletonema costatum (respectively 11.1 / and 18.5 /) were measured along with form IC RubisCO from Rhodobacter sphaeroides and Ralstonia eutropha (respectively 22.9 / and 19.0 /). Isotopic discrimination by these form ID/IC RubisCOs is low when compared to form IA/IB RubisCOs (22-29 /). Since the measured form ID RubisCOs are less selective against 13C, oceanic carbon cycle models based on 13C values may need to be reevaluated to accommodate lower ε values of RubisCOs found in major marine algae. Additionally, with further isotopic studies, the extent to which form IC RubisCO from soil microorganisms contributes to the terrestrial carbon sink may also be determined.

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Eliassen, Nicole. "Cell Size Variation in Fossil Coccolithophores (Haptophyta) : A Study of Pliocene Sediments from Northwestern Australia." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-353793.

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This report examines the size variations of fossil carbonate-producing haptophyte microalgae, coccolithophores, using sediments deposited during the Pliocene. The sediments were collected by the International Ocean Discovery Program (IODP) in 2015, off the coast of NW Australia (Gallagher et al., 2017). A climate shift from arid to humid, warm climate occurred over northwest Australia during the early Pliocene, leading to the so-called “Humid Interval” 5.5-3.3 Ma (Christensen et al., 2017). The investigated samples cover approximately 1 million years within this Humid Interval (~4.5 to 3.5 million years ago, Ma). The cell size of coccolithophores can be related to growth and carbonate production rates, and thus size becomes important to examine as these marine algae are considered to be a big part of the carbon cycle. Previous laboratory work has shown that environmental factors such as temperature, nutrient availability, and pH affect extant coccolithophore cell size. By looking at reports concerning related extant species, such as Emiliania huxleyi, clues can be given as to why the fossil genusReticulofenestra may have changed in cell size during the Pliocene. The measurements of fossil Reticulofenestra coccospheres in this report show an increase in cell size during the studied interval that could be due to heat stress, limited nutrient availability, or other factors, that are less beneficial for the growth of coccolithophores.
Denna rapport undersöker storleksvariationerna av fossila kalkproducerande fästalger, kokkolitoforider, i sediment avsatta under Pliocen. Sedimenten samlades in av International Ocean Discovery Program (IODP) under år 2015, utanför Australiens nordvästra kust (Gallagher et al., 2017). En klimatskiftning inträffade över nordvästra Australien under tidig Pliocen, från ett torrt klimat till ett varmt och fuktigt klimat 5.5 miljoner år sedan och dessa klimatförhållanden varade till ca. 3.3 miljoner år sedan (Christensen et al., 2017). De prov som studerades i denna studie täcker en tidsperiod på 1 miljon år (från ca 4,5 till 3,5 miljoner år sedan, Ma). Kokkolitoforidernas cellstorlek kan indikera tillväxthastighet och karbonatproduktionshastighet, och således blir storleken viktig att undersöka eftersom dessa alger är en stor del av kolcykeln. Tidigare laboratoriearbete har visat att miljöfaktorer som temperatur, näringstillgänglighet och pH påverkar existerande fästalgers cellstorlek genom förändrade tillväxthastigheter och deras förmåga att bilda kalk. Genom att titta på rapporter om besläktade levande arter, såsom Emiliania huxleyi, kan ledtrådar ges till varför det fossila släkte Reticulofenestra kan ha förändrats i cellstorlek under Pliocens varma klimat. Mätningarna av fossila Reticulofenestra cellerna i denna rapport visar att en ökning av cellstorleken kan ses under intervallet, vilket kan bero på antingen förhöjda temperaturer, begränsad tillgång till näringsämnen eller andra faktorer som är mindre fördelaktiga för fästalgernas tillväxt.

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Kottmeier, Dorothee Marie [Verfasser], Björn [Akademischer Betreuer] Rost, Björn [Akademischer Betreuer] Rost, and Anya [Akademischer Betreuer] Waite. "Process understanding of photosynthetic fluxes underlying ocean acidification responses in the coccolithophore Emiliania huxleyi / Dorothee Marie Kottmeier. Betreuer: Björn Rost. Gutachter: Björn. Rost ; Anya Waite." Bremen : Staats- und Universitätsbibliothek Bremen, 2015. http://d-nb.info/1096391163/34.

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Kaffes, Athanasios [Verfasser]. "Carbon and nitrogen fluxes in the marine coccolithophore Emiliania huxleyi grown under different nitrate concentrations / Athanasios Kaffes. Alfred-Wegener-Institute for Polar and Marine Research." Bremen : IRC-Library, Information Resource Center der Jacobs University Bremen, 2010. http://d-nb.info/1035034182/34.

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21

Rokitta, Sebastian [Verfasser], Björn [Akademischer Betreuer] Rost, and Kai [Akademischer Betreuer] Bischof. "Characterization of the life-cycle stages of the coccolithophore Emiliania huxleyi and their responses to Ocean acidification / Sebastian D. Rokitta. Gutachter: Björn Rost ; Kai Bischof. Betreuer: Björn Rost." Bremen : Staats- und Universitätsbibliothek Bremen, 2012. http://d-nb.info/1072046725/34.

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22

Harper, Glenn Martin. "Calcification in coccolithophores." Thesis, University of Plymouth, 2017. http://hdl.handle.net/10026.1/8664.

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Coccolithophores are uni-cellular phytoplankton and they form an exceedingly diverse group in the phylum Haptophyta. They produce highly complex structures known as coccoliths by a biomineralisation process known as calcification. The first part of the work undertaken was to investigate the process of calcification in the coccolithophore Coccolithus pelagicus using a combination of Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM) and light microscopy techniques. This allowed better understanding of the formation, transit of the coccolith through the cell until its final placing in the coccosphere. The second part of the work looked at the coccolithophore Emiliania huxleyi which is divided into several morphotypes with the two most widely recognised being A and B, it can be further subdivided into further groups according to genotype by Coccolithophore Morphology Motif (CMM). The CMMs lie in the 3/ untranslated region of the coccolith-polysaccharide associated protein-GPA, which is associated with coccolith structure control and they are labelled I, II, III and IV. The work undertaken used a Scanning Electron Microscope (SEM) to investigate the morphologies of homozygous CMM I and CMMIV cell’s coccoliths. This information was used to establish a significant difference between the CMMI cells and CMMIV cells but only at certain locations. The cause for this is possibly as a result of several factors (temperature, salinity, pCO2, Ca availability and light levels) and requires further investigation.

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Meyerdierks, Doris. "Zur Ökophysiologie des Dimethylsulfoniumpropionat (DMSP)-Gehaltes temperierter und polarer Phytoplanktongemeinschaften im Vergleich mit Laborkulturen der Coccolithophoride Emiliania huxleyi und der antarktischen Diatomee Nitzschia lecointei = Ecophysiology of the dimethylsulfoniopropionate (DMSP) content of temperate and polar phytoplankton communities in comparison with cultures of the coccolithophore Emiliania huxleyi and the antarctic diatom Nitzschia lecointei /." Bremerhaven : Alfred-Wegener-Institut für Polar- und Meeresforschung, 1997. http://www.gbv.de/dms/bs/toc/229009328.pdf.

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24

Harlay, Jérôme. "Biogeochemical study of coccolithophorid blooms in the context of climate change." Doctoral thesis, Universite Libre de Bruxelles, 2009. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210352.

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Coccolithophores are unicellular microscopic algae (Haptophyta) surrounded by calcium carbonate plates that are produced during their life cycle. These species, whose contemporary contributor is Emiliania huxleyi, are mainly found in the sub-polar and temperate oceans, where they produce huge blooms visible from space. Coccolithophores are sensitive to ocean acidification that results from the ongoing accumulation of anthropogenic carbon dioxide (CO2) in the atmosphere. The response of these organisms to global change appears to be related to the reduction of their ability to produce calcium carbonate at the cellular level. At the community levels, one anticipates changes in the carbon fluxes associated to their blooms as calcification is reduced. However, the consequences of such environmental changes on this species are speculative and require improvements in the description of the mechanisms controlling the organic and inorganic carbon production and export.

The first aspect of this work was to study the response of these organisms to artificially modified CO2 concentrations representative of the conditions occurring in the past (glacial) and those expected by the end of the century (2100). Two different levels were examined: the continuous monospecific cultures (chemostats) allowed us to work at the cellular level while the mesocosms gave light to the mechanisms taking place in an isolated fraction of the natural community. The second aspect of this work consisted of field studies carried out during four cruises (2002, 2003, 2004 and 2006) in the northern Bay of Biscay, where the occurrence of E. huxleyi blooms were observed in late spring and early summer. We describe the vertical profiles of biogeochemical variables (nutrients, chlorophyll-a, dissolved inorganic chemistry, particulate carbon, transparent exopolymer particles (TEP)) and study processes such as primary production, calcification and bacterial production. The properties of these blooms are compared with those reported in the literature and enriched with original measurements such as the abundance and concentration of TEP that could play an important role in carbon export to the deep ocean, modifying the properties of the settling ballasted aggregates.

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25

Perrot, Laurie. "Observer les coccolithophores de l'espace." Thesis, Brest, 2017. http://www.theses.fr/2017BRES0032/document.

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Les coccolithes, dans les cellules ou détachés, des coccolithophores sont de petites plaquettes de calcite diffusant fortement la lumière. Les efflorescences sont donc très visibles de l’espace et sont couramment quantifiées par l’algorithme Calcite de la NASA appliqué aux données des capteurs de la Couleur de l’Eau.Les coccolithes impactent aussi le produit des matières en suspension non-algales de l’ifremer (MES) largement utilisé sur le plateau continental ouest-européen. Bien que développés indépendamment, ces algorithmes sont basés sur des concepts très proches mais l’algorithme Ifremer est plus souple dans sa modélisation et permet d’établir un lien avec les particules autres que les coccolithes telles les remises en suspension ou les agrégats de particules. L'identification des blooms de coccolithophores sur 18 ans, duGolfe de Gascogne jusqu'au sud de l'Irlande, a été établie par une méthode spectrale, permettant de discriminer la fraction de MES correspondant aux coccolithes. Les blooms suivent le talus au printemps avec une progression vers le nord bien reliée à la variabilité saisonnière de la lumière. La variabilité interannuelle observée indique une légère décroissance globale des blooms, avec une année 2014 aux abondances extrêmement faibles sur toute la région.Les données des campagnes PELGAS en mai dans le Golfe de Gascogne ont mis en évidence la forte corrélation entre le produit MES et la turbidité in situ sur les blooms de coccolithophores. Ce paramètre peut être considéré comme un bon proxy pour le suivi des blooms et pour la description de leur structure verticale.Les données hydrologiques in situ montrent une occurrence plus forte des blooms dans un environnement moins stratifié, des températures plus froides et une salinité plus élevée.La sensibilité de la méthode satellite face à la présence réelle de blooms de coccolithophores a pu être évaluée grâce aux observations in situ de campagnes menées dans le Golfe de Gascogne et en Patagonie.Cette sensibilité reste variable car dépendante de nombreux facteurs intrinsèques aux blooms, liés à la proportion coccolithes/coccosphères et à leur composition taxonomique, qui s’est avérée très riche en mai2016 dans le Golfe de Gascogne
Coccoliths, in cells or detached, from coccolithophores are calcite plates with highly backscattering signal.Coccolithophore blooms are visible from space and are currently quantified by Calcite algorithm fromNASA applied to Ocean Color data. Coccoliths impact also the Suspended Particulate Matters (SPM) product from Ifremer, well established in the Northwest european continental shelf. Although these algorithms are independent, they are based on the same basic concepts, but Ifremer algorithm is more adaptable and allows to link up with other particles than coccoliths, as the resuspended matters or aggregates.Coccolithophore blooms identification over 18 years, from bay of Biscay to South Irelands has been established by a spectral method, allowing to discriminate coccoliths from SPM. Blooms follow the continental slope northward in connection with the seasonal variability of irradiance. The interannual variability observed indicates a slight decrease of blooms, with a very poor productive year in 2014.Data from PELGAS cruises in May in the Bay of Biscay highlight the strong correlation between SPM product and the in situ turbidity in coccolithophore blooms.This parameter can be considered a a good proxy for the blooms monitoring and for the description of their vertical structure. Hydrological in situ data show a stronger occurrence in less stratified environment, with lower temperatures and higher salinity.The sensitivity of the satellite to the presence of coccoliths has benn evaluated based on in situ observations from cruises in the Bay of Biscay and in Patagonia. This sensitivity is variable due to a lot of inherent factors, to the coccoliths/coccospheres proportion and to the taxonomic composition which has been rich in May 2016 in the Bay of Biscay

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26

Walker, Charlotte. "Mechanisms of calcification in coccolithophores." Thesis, University of Southampton, 2018. https://eprints.soton.ac.uk/425508/.

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Coccolithophores are unicellular marine algae characterised by the production of calcite coccoliths. As a result of their calcification they contribute significantly to global biogeochemical cycles. Comprehensive understanding of the mechanisms behind calcification remains elusive, due in part to the research focus on one species, Emiliania huxleyi; the most globally abundant of all coccolithophores. It is imperative to investigate calcification in other species to better understand this biogeochemically important process, especially as the ecological success of E. huxleyi may be due to certain physiological differences with other species. This study set out to explore differences between species in the mechanisms of calcification in three primary areas. Firstly, the physiological requirement for calcification remains poorly understood, particularly as non-calcifying strains of E. huxleyi grow normally in laboratory culture. This study identified a contrast in the requirement for calcification between E. huxleyi and the ecologically important Coccolithus braarudii. Calcification disruption had no negative impacts on E. huxleyi but resulted in major growth defects in C. braarudii demonstrating an obligate requirement for calcification in this species. Secondly, the previous identification of Si transporters in some coccolithophores was further investigated using a combination of physiological and expression studies to identify that Si plays a role in heterococcolith calcification during their diploid life stage. C. braarudii Si transporters were also found to be regulated in response to available Si and shown to be expressed in natural populations. Finally, coccolith associated polysaccharides (CAPs) are an integral component of the calcification mechanism known to modulate the precipitation of calcite. The data presented here show that extracellular CAPs differ in structure and composition between species and that they also play an important role in the organisation of the coccosphere, expanding upon their role and importance in calcification. These findings mark crucial physiological differences between coccolithophore species. The identification of a requirement for calcification in coccolithophores highlights the importance of maintaining a coccosphere. The requirement for Si in some species suggests major physiological differences between species which may influence their ecology. Consequently, these contrasting physiological characteristics may contribute to significant differences in the response of coccolithophores to future ocean conditions.

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Tangunan, Deborah [Verfasser], Rüdiger [Akademischer Betreuer] Henrich, Rüdiger [Gutachter] Henrich, and Villarejo Jose Abel [Gutachter] Flores. "Late Neogene to Quaternary paleoproductivity of the western Indian Ocean and the eastern South Atlantic from coccolithophore assemblage and coccolith geochemistry / Deborah Tangunan ; Gutachter: Rüdiger Henrich, Jose Abel Flores Villarejo ; Betreuer: Rüdiger Henrich." Bremen : Staats- und Universitätsbibliothek Bremen, 2017. http://d-nb.info/115083398X/34.

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De, Bodt Caroline. "Pelagic calcification and fate of carbonate production in marine systems." Doctoral thesis, Universite Libre de Bruxelles, 2010. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210156.

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Human activities have contributed to the increase in atmospheric greenhouse gases such as carbon dioxide (CO2). This anthropogenic gas emission has led to a rise in the average Earth temperature. Moreover, the ocean constitutes the major sink for anthropogenic CO2 and its dissolution in surface waters has already resulted in an increase of seawater acidity since the beginning of the industrial revolution. This is commonly called ocean acidification. The increase in water temperature could induce modifications of the physical and chemical characteristics of the ocean. Also, the structure and the functioning of marine ecosystems may be altered as a result of ocean acidification.

Phytoplankton productivity is one of the primary controls in regulating our climate, for instance via impact on atmospheric CO2 levels. Coccolithophores, of which Emiliania huxleyi is the most abundant species, are considered to be the most important pelagic calcifying organisms on Earth. Coccolithophores are characterized by calcium carbonate platelets (coccoliths) covering the exterior of the cells. They form massive blooms in temperate and sub-polar oceans and in particular along continental margin and in shelf seas. The intrinsic coupling of organic matter production and calcification in coccolithophores underlines their biogeochemical importance in the marine carbon cycle. Both processes are susceptible to change with ocean acidification and warming. Coccolithophores are further known to produce transparent exopolymer particles (TEP) that promote particle aggregation and related processes such as marine snow formation and sinking. Thus, the impact of ocean warming and acidification on coccolithophores needs to be studied and this can be carried out through a transdisciplinary approach.

The first part of this thesis consisted of laboratory experiments on E. huxleyi under controlled conditions. The aim was to estimate the effect of increasing water temperature and acidity on E. huxleyi and especially on the calcification. Cultures were conducted at different partial pressures of CO2 (pCO2); the values considered were 180, 380 and 750 ppm corresponding to past, present and future (year 2100) atmospheric pCO2. These experiments were conducted at 13°C and 18°C. The cellular calcite concentration decreases with increasing pCO2. In addition, it decreases by 34 % at 380 ppm and by 7 % at 750 ppm with an increase in temperature of 5°C. Changes in calcite production at future pCO2 values are reflected in deteriorated coccolith morphology, while temperature does not affect coccolith morphology. Our findings suggest that the sole future increase of pCO2 may have a larger negative impact on calcification than its interacting effect with temperature or the increase in temperature alone. The evolution of culture experiments allows a better comprehension of the development of a bloom in natural environments. Indeed, in order to predict the future evolution of calcifying organisms, it is required to better understand the present-day biogeochemistry and ecology of pelagic calcifying communities under field conditions.

The second part of this dissertation was dedicated to results obtained during field investigations in the northern Bay of Biscay, where frequent and recurrent coccolithophorid blooms were observed. Cruises, assisted by remote sensing, were carried out along the continental margin in 2006 (29 May – 10 June), 2007 (7 May – 24 May) and 2008 (5 May – 23 May). Relevant biogeochemical parameters were measured in the water column (temperature, salinity, dissolved oxygen, Chlorophyll-a and nutrient concentrations) in order to determine the status of the bloom at the time of the different campaigns. Calcification has been shown to be extremely important in the study area. In addition, TEP production was significant at some stations, suggesting that the northern Bay of Biscay could constitute an area of important carbon export. Mortality factors for coccolithophores were studied and the first results of lysis rates measured in this region were presented.

Results obtained during culture experiments and comparison with data reported in the literature help to better understand and to predict the future of coccolithophores in a context of climate change. Data obtained during either culture experiments or field investigations allowed a better understanding of the TEP dynamics. Finally, the high lysis rates obtained demonstrate the importance of this process in bloom decline. Nevertheless, it is clear that we only begin to understand the effects of global change on marine biogeochemistry, carbon cycling and potential feedbacks on increasing atmospheric CO2. Thus, further research with a combination of laboratory experiments, field measurements and modelling are encouraged.

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29

Fresnel, Jacqueline. "Les Coccolithophorides (Prymnesiophyceae) du littoral : genres Cricosphaera, Pleurorochrysis, Cruciplacolithus, Hymenomonas et Ochroaphaera. Ultrastructure, cycle biologique, systématique." Caen, 1989. http://www.theses.fr/1989CAEN2018.

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Ce travail a pour objectif de faire la mise au point de nos recherches sur les Coccolithophorides du littoral, toutes obtenues en cultures unialgales. La description des organismes au microscope photonique est suivie de l'étude au microscope électronique de leur couverture cellulaire (différentes catégories d'écailles organiques et coccolithes en met et meb) et de leur ultrastructure. L'accent est mis sur la coccolithogénese et les caractères ultrastructuraux de l'appareil flagellaire. L'étude du cycle complet a été réalisée chez Pleurochrysis pseudoroscoffensis par l'observation de toutes les étapes de la fécondation entre zoides haploides issus de filaments jusqu'à la réapparition de la génération diploide à coccolithes. En outre, un nouveau type d'alternance de générations est mis en évidence chez trois espèces à trémalithes, Ochrosphaera neapolitana, Hymenomonas lacuna et h. Coronata. Il est notamment montré dans ce travail: 1) la présence de deux sous-groupes parmi les espèces à cricolithes; 2) la particularité d'Ochrosphaera dont les coccolithes se surcalficient progressivement; 3) l'originalité des Coccolithophorides quant aux racines microtubulaires liées aux bases flagellaires et la présence d'une racine, qualifiée de contractile, chez tous les genres étudiés; 4) que la morphologie fine des écailles organiques caractérise les générations. La réunion des genres à tremalithes dans la famille des Hymenomonadaceae est proposée ainsi que la création d'une nouvelle famille pour les espèces à cricolithes

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30

Berry, L. S. "Calcification, photosynthesis and nutrient uptake in coccolithophores." Thesis, Swansea University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636084.

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Emiliania huxleyi is the most abundant coccolithophore in the World's oceans today. These organisms have the ability to calcify and photosynthesise, and may represent an important oceanic sink for dissolved inorganic carbon. As a result, they have the potential to influence the oceanic carbon cycle. It has been proposed that calcification may improve carbon acquisition under CO₂ _(aqueous) limiting conditions, but may involve high Ca²⁺ transport costs. In this thesis, results presented show that calcification increases in E. huxleyi (strain L) in response to low phosphorus and/or nitrate, high external pH, and high dissolved inorganic carbon. This information was used to produce calcifying and non-calcifying cells of the same strain allowing comparisons, which avoided the genetic and psychological differences between strains. Calcification correlated with an increase in photosynthetic efficiency (Φ>_PSII), relative electron transport rate (REF_PSII) and the proportion of photons captured and converted to chemical energy (qP). The mechanisms underlying these correlations are unknown, but may involve the H⁺ produced during calcification being used to supply an internal CO₂ source. High calcifying cells were found to have a lower internal pH than low-calcifying cells, and were able to take up HCO₃^-. This may influence CO₂ availability within the cell, or nutrient requirements and assimilation. Results from X-ray microanalysis and Electron Energy Loss Spectroscopy indicate that the endomembrane system may provide an efficient pathway for Ca²⁺ transport to the coccolith vesicle. Potentially, this avoids transport of Ca²⁺ against a concentration gradient, and resolves what was thought to be one of the major cost-aspects of calcification. The most likely advantage of calcification is that it may allow low levels of photosynthesis to occur efficiently, thus increasing survival time during co-limitation by CO₂, phosphorous and/or nitrate. Calcification may enable the cell to reduce the nutrient requirements for photosynthesis, or allow internal nutrient recycling.

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31

Hopkins, Jason. "A satellite perspective on global blooms of coccolithophores." Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/374825/.

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Coccolithophores are a unique group of phytoplankton that produce calcium carbonate coccoliths. The production of coccoliths can potentially reduce the carbon sink effect associated with phytoplankton photosynthesis. However, this may be offset by a coccolith ‘ballast’ effect that increases particulate organic carbon export efficiency. During a coccolithophore bloom, large quantities of coccoliths are shed into the water column. The unique light scattering properties of calcium carbonate particles of ~2 μm in size (the size of an Emiliania huxleyi coccolith) have previously been used to develop an algorithm that enables estimates of particulate inorganic carbon (PIC) concentration to be made from space. Here, these satellite derived PIC data have been used to generate a unique set of phonological characteristics, such as start date, peak date and bloom magnitude, for global coccolithophore blooms. A comparison of similar timings generated from chlorophyll data indicates that, contrary to conventional thinking, blooms of coccolithophores can co-‐occur with other phytoplankton taxa. An assessment of the environmental conditions associated with coccolithophore blooms suggests that current understanding of coccolithophore bloom characteristics may be associated with the peak of the bloom and that conditions at the start of the bloom can be significantly different (i.e. deep mixed layers, moderate light levels and elevated silicic acid concentrations). A global PIC inventory of 29.0 ± 4.3 MT C was determined from satellite derived PIC and mixed layer depth data. The Great Calcite Belt and tropical Pacific were found to be regions that make a significant contribution to this budget. The data produced in this thesis provide the first multi-‐year, global overview of coccolithophores and offer a novel means of monitoring coccolithophore populations over the long-term, global scales needed to identify the possible influences of climate change.

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32

Geisen, Markus. "Studies on the species level variation of selected coccolithophores." Thesis, University College London (University of London), 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.409704.

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33

Šupraha, Luka. "Phenotypic evolution and adaptive strategies in marine phytoplankton (Coccolithophores)." Doctoral thesis, Uppsala universitet, Paleobiologi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-302903.

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Coccolithophores are biogeochemically important marine algae that interact with the carbon cycle through photosynthesis (CO2 sink), calcification (CO2 source) and burial of carbon into oceanic sediments. The group is considered susceptible to the ongoing climate perturbations, in particular to ocean acidification, temperature increase and nutrient limitation. The aim of this thesis was to investigate the adaptation of coccolithophores to environmental change, with the focus on temperature stress and nutrient limitation. The research was conducted in frame of three approaches: experiments testing the physiological response of coccolithophore species Helicosphaera carteri and Coccolithus pelagicus to phosphorus limitation, field studies on coccolithophore life-cycles with a method comparison and an investigation of the phenotypic evolution of the coccolithophore genus Helicosphaera over the past 15 Ma. Experimental results show that the physiology and morphology of large coccolithophores are sensitive to phosphorus limitation, and that the adaptation to low-nutrient conditions can lead to a decrease in calcification rates. Field studies have contributed to our understanding of coccolithophore life cycles, revealing complex ecological patterns within the Mediterranean community which are seemingly regulated by seasonal, temperature-driven environment changes. In addition, the high-throughput sequencing (HTS) molecular method was shown to provide overall good representation of coccolithophore community composition. Finally, the study on Helicosphaera evolution showed that adaptation to decreasing CO2 in higher latitudes involved cell and coccolith size decrease, whereas the adaptation in tropical ecosystems also included a physiological decrease in calcification rates in response to nutrient limitation. This thesis advanced our understanding of coccolithophore adaptive strategies and will improve our predictions on the fate of the group under ongoing climate change.

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34

Jordan, Richard William. "Coccolithophorid communities in the North-East Atlantic." Thesis, University of Surrey, 1988. http://epubs.surrey.ac.uk/814123/.

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Caccolithopliorids are important members of phytoplankton communities in most parts of the world's oceans. The formation, release and flux of the calcite scales (coccoliths) of these organisms over millions of years, has led to sedimentary deposits of great geological significance. The reporting of immense blooms of coccolithophorids by satellite photography and their passible involvement in atmospheric sulphur emissions has emphasised the necessity for further information on their distribution and ecology. During an extensive sampling programme in the N.E. Atlantic, water samples were collected throughout the photic zone at 30 stations. Scanning electron microscopy of filtered water samples enabled coccolithophorid family and species distributions to be compiled. It was found that certain species assemblages could be assigned to distinct biogeographic zones and that these zones closely conformed to the movements of the N. Atlantic surface currents. However, at the Azores Front it was shown that a transitional region existed between the cold and warm water masses, where the flora of each zone could be found. Detailed studies of coccolithophorid vertical distribution has shown that most species can be assigned to discrete depth bands within the euphotic zone. Furthermore, it was noticed that in two species which have no depth preference, the degree of calcification increased with depth. One of these species, E. huxleyi, displayed two ecomorphotypic variants differing in their calcification, size and morphology. During two east to west transects it was noticed that the halocaccolitiiophorid numbers increased towards the Mid-Atlantic Ridge. A number of new species are described and current taxonomic problems reviewed.

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35

Eek, Magnus. "Environmental control of stable carbon isotope systematics in Emiliania huxleyi." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0017/NQ52759.pdf.

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36

Supraha, Luka. "Phenotypic variation and adaptive strategies in calcifying marine phytoplankton (Coccolithophores)." Licentiate thesis, Uppsala universitet, Paleobiologi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-253357.

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37

Moheimani, Navid Reza. "The culture of coccolithophorid algae for carbon dioxide bioremediationn /." Access via Murdoch University Digital Theses Project, 2005. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20050901.140745.

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38

Maurin, Claire. "Régulation de la glutamine synthétase chez le cocolithophoridé Emiliania Huxleyi." Brest, 1997. http://www.theses.fr/1997BRES2008.

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La nature de la source azotee et sa concentration ainsi que la lumiere sont des facteurs de regulation de la glutamine synthetase d'emiliania huxleyi au niveau de son activite et de sa synthese. L'etude parallele de la glutamate deshydrogenase et de la glutamine synthetase montre que cette derniere se situe sur la voie principale d'assimilation de l'azote. Deux isoformes de la glutamine synthetase (gs1 et gs2) ont ete purifies et caracterises. Les modalites de regulation propres a chaque isoforme ont ete etudiees afin de preciser le role de chacune dans les differents processus d'assimilation, de reassimilation ou de detoxication de l'ammonium.

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39

Sheward, Rosie Melanie. "Cell size, coccosphere geometry and growth in modern and fossil coccolithophores." Thesis, University of Southampton, 2016. https://eprints.soton.ac.uk/397327/.

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Coccolithophores are a key phytoplankton group that exhibit remarkable diversity in their biology, ecology, and in the highly distinctive morphological architecture of their calcite exoskeletons (coccospheres). Their extensive fossil record is testament to the crucial role that they play in the biogeochemical cycling of carbon through the production and export of inorganic coccoliths and organic matter. This fossil record provides an excellent archive of their biotic responses to environmental variability over thousands to millions of years that can be used to investigate the possible sensitivity of coccolithophores to potential changes in future climate. In this thesis, I explore how the fossil record of coccospheres can be utilized to investigate coccolithophore growth and physiology, providing a new cellular-level perspective on how we understand their interactions with global climate. This work focuses particularly on coccolithophores during the Paleogene, ~66 to ~23 million years ago, that was characterized by initially warm, high CO2 ‘greenhouse’ conditions that progressively cooled, involving substantial restructuring of marine systems. By imaging and measuring thousands of individual coccospheres, I have extensively documented the fundamentals of coccosphere architecture, including coccosphere size and shape and its relationship to coccolith size, number of coccoliths and their arrangement around each cell. This unprecedented dataset reveals the remarkable level of diversity in the architecture of Paleogene coccospheres for the first time, including multiple extinct species that had not previously been observed in this original form. Understanding what this dataset of coccosphere ‘geometry’ can tell us has necessitated the parallel exploration of modern coccolithophore biomineralisation and physiology. My culturing experiments on multiple modern species reveal that cell size and the number of coccoliths per cell is strongly regulated by cellular physiology, specifically responding to a decoupling between cellular division and calcification ability as populations transition between exponential and non-exponential phases of growth. Drawing direct comparisons between the coccosphere geometry of modern and fossil coccolithophores enables a proxy for growth phase to be developed that allows cellular physiology in the fossil record to be directly investigated. This is a potentially powerful new tool for understanding biotic-abiotic interactions in geological time. Furthermore, taxon-specific cellular geometry information provides us with a unique means to begin to reconstruct community-level cellular size structure and, crucially, its associated biovolume. These first reconstructions of community cell size structure across the transition from the Early Eocene greenhouse to the Early Oligocene icehouse demonstrate a massive shift in community biovolume distribution towards larger cells. This radically different-looking community must, in part, reflect the ability of the environment to support the demands of larger cells. Taken in conjunction with inferred changes in nutrient availability by the Late Eocene, this shift in population size structure was likely accompanied by an increase in community biomass, with potentially important implications for carbon export and size-specific grazing. Overall, my research illustrates that coccosphere geometry is a valuable tool for investigating fossil coccolithophore assemblages as populations of individual cells that are recording daily physiological responses to their immediate environment that ultimately determines the response of species and communities to environmental change.

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40

com, n_moheimani@hotmail, and Navid Reza Moheimani. "The culture of coccolithophorid algae for carbon dioxide bioremediationn." Murdoch University, 2005. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20050901.140745.

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The culture of coccolithophorid algae is an attractive option for sequestration or recycling of CO2 as they can fix carbon by photosynthesis as well as in calcium carbonate scales known as coccoliths. They also produce high amounts of lipids which have a potential application as a renewable fuel. Five species of coccolithophorids (Pleurochrysis carterae, CCMP647, Pleurochrysis sp. CCMP1211, Gephyrocapsa oceanica CS-335/2, Emiliania huxleyi CCMP371, and Emiliania huxleyi CS-369) were screened for their ability to grow at high temperature. All species grew up to 28oC except E. huxleyi CS-369. However, Pleurochrysis sp. CCMP 1211 which was found to clump and can therefore not be recommended for large-scale cultivation. The salinity tolerance of these species was also examined. Growth of P. carterae, G. oceanica, and E. huxleyi in laboratory scale closed photobioreactors (plate, carboy, airlift, and tubular photobioreactors) showed the plate photobioreactor to be the best closed cultivation system. The highest productivities were achieved by P. carterae in the plate photobioreactor and were 0.54 g.L-1.d-1, 0.12 g.L-1.d-1, 0.06 g.L-1.d-1 for total dry weight, lipid and CaCO3 respectively. The growth of P. carterae and E. huxleyi was also examined in an outdoor raceway pond. The E. huxleyi culture was easily contaminated resulting in the loss of the culture in less than three weeks, but P. carterae grew well over a period of 13 months. The overall total dry weight productivity of P. carterae was 0.19 g.L-1.d-1 with lipid and CaCO3 contents of up to 33% and 10% of dry weight respectively. There was little protozoan and bacterial contamination. Medium pH increased to pH 11 during the day and was found to be a reliable variable for maintaining the health of the culture. A maximum pH achieved during the day of less than pH 8.5 indicated the imminent collapse of the culture. Heavy rain and low temperature were the main reasons for culture loss in mid winter, whereas high temperature during summer favoured P. carterae growth. A comparison of the growth of P. carterae and Dunaliella salina MUR8 in the raceway ponds showed no significant differences between these two species with regard to areal total dry weight productivity and lipid content. The effects of several limiting factors were also examined. A reduction in medium pH resulting from CO2 addition inhibited the growth of E. huxleyi in the plate photobioreactor, whereas P. carterae growth and productivities increased in the pH range of pH 7.7 to 8.0 in the plate photobioreactor and pH 9.1 to 9.6 in the outdoor raceway pond. The best operational pond depth for outdoor raceway culture of P. carterae was between 16 cm and 21 cm. Early morning temperatures, especially during the winter, highly affected the growth of P. carterae in the raceway pond, whereas artificially increasing the medium temperature improved the health of the culture but resulted in little increase in productivity. Photosynthesis of P. carterae was found to be highly inhibited by high oxygen concentration in the medium irrespective of temperature or irradiance. An economic model of P. carterae in a 63 ha raceway plant resulted in a cost for the biomass of between 7.35 Aus$.Kg-1 and 14.17 Aus$.Kg-1 depending on the harvesting method used.

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41

Moheimani, Navid Reza. "The culture of coccolithophorid algae for carbon dioxide bioremediation." Thesis, Moheimani, Navid Reza ORCID: 0000-0003-2310-4147 (2005) The culture of coccolithophorid algae for carbon dioxide bioremediation. PhD thesis, Murdoch University, 2005. https://researchrepository.murdoch.edu.au/id/eprint/206/.

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The culture of coccolithophorid algae is an attractive option for sequestration or recycling of CO2 as they can fix carbon by photosynthesis as well as in calcium carbonate scales known as coccoliths. They also produce high amounts of lipids which have a potential application as a renewable fuel. Five species of coccolithophorids (Pleurochrysis carterae, CCMP647, Pleurochrysis sp. CCMP1211, Gephyrocapsa oceanica CS-335/2, Emiliania huxleyi CCMP371, and Emiliania huxleyi CS-369) were screened for their ability to grow at high temperature. All species grew up to 28oC except E. huxleyi CS-369. However, Pleurochrysis sp. CCMP 1211 which was found to clump and can therefore not be recommended for large-scale cultivation. The salinity tolerance of these species was also examined. Growth of P. carterae, G. oceanica, and E. huxleyi in laboratory scale closed photobioreactors (plate, carboy, airlift, and tubular photobioreactors) showed the plate photobioreactor to be the best closed cultivation system. The highest productivities were achieved by P. carterae in the plate photobioreactor and were 0.54 g.L-1.d-1, 0.12 g.L-1.d-1, 0.06 g.L-1.d-1 for total dry weight, lipid and CaCO3 respectively. The growth of P. carterae and E. huxleyi was also examined in an outdoor raceway pond. The E. huxleyi culture was easily contaminated resulting in the loss of the culture in less than three weeks, but P. carterae grew well over a period of 13 months. The overall total dry weight productivity of P. carterae was 0.19 g.L-1.d-1 with lipid and CaCO3 contents of up to 33% and 10% of dry weight respectively. There was little protozoan and bacterial contamination. Medium pH increased to pH 11 during the day and was found to be a reliable variable for maintaining the health of the culture. A maximum pH achieved during the day of less than pH 8.5 indicated the imminent collapse of the culture. Heavy rain and low temperature were the main reasons for culture loss in mid winter, whereas high temperature during summer favoured P. carterae growth. A comparison of the growth of P. carterae and Dunaliella salina MUR8 in the raceway ponds showed no significant differences between these two species with regard to areal total dry weight productivity and lipid content. The effects of several limiting factors were also examined. A reduction in medium pH resulting from CO2 addition inhibited the growth of E. huxleyi in the plate photobioreactor, whereas P. carterae growth and productivities increased in the pH range of pH 7.7 to 8.0 in the plate photobioreactor and pH 9.1 to 9.6 in the outdoor raceway pond. The best operational pond depth for outdoor raceway culture of P. carterae was between 16 cm and 21 cm. Early morning temperatures, especially during the winter, highly affected the growth of P. carterae in the raceway pond, whereas artificially increasing the medium temperature improved the health of the culture but resulted in little increase in productivity. Photosynthesis of P. carterae was found to be highly inhibited by high oxygen concentration in the medium irrespective of temperature or irradiance. An economic model of P. carterae in a 63 ha raceway plant resulted in a cost for the biomass of between 7.35 Aus$.Kg-1 and 14.17 Aus$.Kg-1 depending on the harvesting method used.

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42

Moheimani, Navid Reza. "The culture of coccolithophorid algae for carbon dioxide bioremediation." Moheimani, Navid Reza (2005) The culture of coccolithophorid algae for carbon dioxide bioremediation. PhD thesis, Murdoch University, 2005. http://researchrepository.murdoch.edu.au/206/.

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The culture of coccolithophorid algae is an attractive option for sequestration or recycling of CO2 as they can fix carbon by photosynthesis as well as in calcium carbonate scales known as coccoliths. They also produce high amounts of lipids which have a potential application as a renewable fuel. Five species of coccolithophorids (Pleurochrysis carterae, CCMP647, Pleurochrysis sp. CCMP1211, Gephyrocapsa oceanica CS-335/2, Emiliania huxleyi CCMP371, and Emiliania huxleyi CS-369) were screened for their ability to grow at high temperature. All species grew up to 28oC except E. huxleyi CS-369. However, Pleurochrysis sp. CCMP 1211 which was found to clump and can therefore not be recommended for large-scale cultivation. The salinity tolerance of these species was also examined. Growth of P. carterae, G. oceanica, and E. huxleyi in laboratory scale closed photobioreactors (plate, carboy, airlift, and tubular photobioreactors) showed the plate photobioreactor to be the best closed cultivation system. The highest productivities were achieved by P. carterae in the plate photobioreactor and were 0.54 g.L-1.d-1, 0.12 g.L-1.d-1, 0.06 g.L-1.d-1 for total dry weight, lipid and CaCO3 respectively. The growth of P. carterae and E. huxleyi was also examined in an outdoor raceway pond. The E. huxleyi culture was easily contaminated resulting in the loss of the culture in less than three weeks, but P. carterae grew well over a period of 13 months. The overall total dry weight productivity of P. carterae was 0.19 g.L-1.d-1 with lipid and CaCO3 contents of up to 33% and 10% of dry weight respectively. There was little protozoan and bacterial contamination. Medium pH increased to pH 11 during the day and was found to be a reliable variable for maintaining the health of the culture. A maximum pH achieved during the day of less than pH 8.5 indicated the imminent collapse of the culture. Heavy rain and low temperature were the main reasons for culture loss in mid winter, whereas high temperature during summer favoured P. carterae growth. A comparison of the growth of P. carterae and Dunaliella salina MUR8 in the raceway ponds showed no significant differences between these two species with regard to areal total dry weight productivity and lipid content. The effects of several limiting factors were also examined. A reduction in medium pH resulting from CO2 addition inhibited the growth of E. huxleyi in the plate photobioreactor, whereas P. carterae growth and productivities increased in the pH range of pH 7.7 to 8.0 in the plate photobioreactor and pH 9.1 to 9.6 in the outdoor raceway pond. The best operational pond depth for outdoor raceway culture of P. carterae was between 16 cm and 21 cm. Early morning temperatures, especially during the winter, highly affected the growth of P. carterae in the raceway pond, whereas artificially increasing the medium temperature improved the health of the culture but resulted in little increase in productivity. Photosynthesis of P. carterae was found to be highly inhibited by high oxygen concentration in the medium irrespective of temperature or irradiance. An economic model of P. carterae in a 63 ha raceway plant resulted in a cost for the biomass of between 7.35 Aus$.Kg-1 and 14.17 Aus$.Kg-1 depending on the harvesting method used.

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43

Webb, Jason. "Growth, calcification and photosynthesis in the coccolithophorid chrysotila carterae." Thesis, Webb, Jason (2015) Growth, calcification and photosynthesis in the coccolithophorid chrysotila carterae. PhD thesis, Murdoch University, 2015. https://researchrepository.murdoch.edu.au/id/eprint/30271/.

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The mass culture of microalgae for the commercial production of a) low value commodities such as biofuel and food and b) high value products such as polyunsaturated fatty acids, carotenoids, and nano-scaffolds is becoming increasingly attractive. Coccolithophorid algae have been investigated as potential candidates for both low and high value products. This thesis provides data on the specific nutrient and growth requirements in the coccolithophorid, Chrysotila carterae (previously Pleurochrysis carterae). Via the use of oxygen evolution techniques and PAM fluorometry, it is shown that C. carterae is just as susceptible to photoinhibition as some other microalgae with photoinhibition occurring at around 1100-1500 μmol photon m2 s-1. C. carterae also has the ability to recover from short periods of acidification, with recovery from pH 5 when there was no organic carbon assimilation to pH 9 after 20 minutes, Carbon assimilation increased from almost 0, to 3.01 pg CORG cell-1 h-1 . This microalga has a fundamental requirement for selenium, with specific growth rates falling from a μmax of 0.6 d-1, with selenium to 0.1 d-1 in selenium-limited culture. Selenium is also required for coccolith production. In Se-limited culture coccolith production was almost reduced by half, from 70 x105 coccoliths mL-1 to 3.8 x 105 coccoliths mL-1. Diurnal studies of organic and inorganic carbon assimilation showed that C. carterae CCMP647 synthesises coccoliths during the day, and then extrudes them onto the cell surface during the last hours of the dark cycle. Investigations into the effect of various nitrogen sources indicated that with unregulated pH, nitrate achieved the greatest cell density and stable growth: The maximum cell densities reached were nitrate (66.61 x 104 ± 8.2 x 103 cells mL-1) > urea (34.0 x 104 ± 6.2 x 103 cells mL-1) = ammonium (36.08 x 104 ± 4.2 x 103 cells mL-1). Nitrate had the greatest effect on the culture medium ΔpH, (NO3- (0.134 ± 0.003) > urea (0.111 ± 0.003) > NH4+ (0.043 ± 0.001) and urea increased the growth rate of C. carterae by 150 % from 0.17 0.002 d-1 on NO3- to 0.44 ± 0.001 d-1 on urea. However, coccolith production increased with NO3- (73.81± 3.51 ng CaCO3 cell-1> NH4+ 55.18 ± 0.61 ng CaCO3 cell-1 > urea at 12.88 1.62 ng CaCO3 cell-1. Organic carbon (CORG) assimilation using NO3- far exceeded that on NH4+ and urea (CORG assimilated with NO3- = 7 x103 pg CORG cell-1 h-1 vs Urea at 6 x103 pg CORG cell-1 h-1 and NH4+ 5 x103 pg CORG cell-1 h-1 . Inorganic carbon assimilation (CINORG) was also elevated with NO3- producing 3 x103 pg CINORG cell-1 h-1 vs urea at 2 x103 pg CINORG cell-1 h-1 and NH4+ at 2 x103 pg CINORG cell-1 h-1. Thus, nitrate provides long term, stable growth with the highest cell overall cell density under unregulated pH. Under elevated medium pH, urea and ammonium had the highest rate of carbon assimilation far in excess of NO3- for both CORG (Urea 44921.73 ± 2191.08 pg CORG cell-1 h-1 > NH4+ 22006.22 ± 640.39 pg CORG cell-1 h-1 > NO3- 773.59 ± 14.8 pg CORG cell-1 h-1) and CINORG, Urea 773.59 ± 14.8 pg CINORG cell-1 h-1 NO3- 569.44 ± 31.4 pg CINORG cell-1 h-1. Although carbon assimilation rates were elevated under urea and NH4+ at higher pH levels, NO3- at pH 8 had the highest Calcifaction to photosynthsdis ratio (C:P) ratio of 0.158, while closely followed by urea at pH 9 (C:P = 0.150). With enhanced carbon assimilation at pH levels exceeding the pKa of CO2 in the medium pH indicated that this species must be using HCO3- as a carbon source, as cell growth and calcification were elevated at pH levels at which there is a greatly reduced level of CO2 in the medium which is typically in air equilibrated water approximately 10 μmol L-1.

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44

Oviedo, Sabogal Angela María. "Effects of phosphorus limitation and ocean acidification on coccolithophores in the Mediterranean Sea." Doctoral thesis, Universitat Autònoma de Barcelona, 2015. http://hdl.handle.net/10803/327587.

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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 nutrientes en el océano. Se introduce así mismo el organismo de estudio, los cocolitóforos. Los últimos apartados de la introducción contienen los objetivos (expuestos como preguntas de investigación) y una explicación del porqué se eligió el Mar Mediterráneo como zona de estudio. Los siguientes 4 capítulos (capítulos 2 al 5) conforman el “cuerpo del trabajo”. Esta tesis combina diferentes aproximaciones metodológicas, desde experimentos de cultivo y mesocosmos hasta observaciones de campo, para responder preguntas a diferentes escalas, de especies a comunidades. Los capítulos 2 y 3 se basan en experimentos de cultivo realizados con la especie Emiliania huxleyi, la más abundante de las especies de cocolitóforos actuales. Se investigaron los impactos de la limitación por P y la acidificación oceánica en cultivos monoclonales de E. huxleyi. En el Capítulo 2, los posibles impactos de la limitación por P se investigan en 6 cepas de la especie E. huxleyi, 4 de ellas aisladas en el Este del Mediterráneo (ultra-oligotrófico) y 2 en el oeste (oligotrófico a mesotrófico). El Capítulo 3 presenta los resultados de un segundo experimento diseñado para examinar los efectos de la acidificación oceánica en aguas pobres en P sobre una de las cepas de E. huxleyi usadas en el experimento previo. El Capítulo 4 presenta los resultados de dos experimentos de mesocosmos realizados en Córcega y Villefranche-sur-Mer (Francia). Estos se enfocan en cuantificar y entender los impactos de la acidificación oceánica en dos comunidades naturales de coccolitoforos, ambas habitando aguas pobres en P. Finalmente, el Capítulo 5 presenta los resultados del análisis de 81 muestras colectadas entre los 0 – 100 m de profundidad, en diferentes puntos del mar Mediterráneo, incluyendo un transepto de este a oeste (Meteor R.V. campaña M84-3, Abril 2011). Los datos adquiridos proveen una descripción de la distribución de los coccolitoforos durante primavera, lo cual se relacionó con una amplia serie de variables ambientales medidas in situ. Se concluye que la limitación por P amplifica la respuesta a la acidificación oceánica dado que disminuye la densidad celular máxima que los cocolitóforos pueden alcanzar. Juntos, los resultados referentes a la limitación por P (Capítulo 2) y los de otros estudios referentes a la acidificación oceánica (Meyer & Riebesell 2015) sugieren que E. huxleyi puede, en un futuro océano limitado por nutrientes y acidificado, contribuir muy poco a la exportación de carbono inorgánico relativa a la exportación total de materia. Esto favorecería la remineralización en lugar del secuestro a largo tiempo de carbono. Aunque limitación por P no induce malformaciones en los coccolitos de E. huxleyi (Capítulos 2 y 3), bajo una exposición prolongada a una elevada pCO2 y en ausencia de selección entre clones, la acidificación oceánica si causa malformación de los cocolitos irrespectivamente de la [P].
This thesis was conducted in the framework of the European Mediterranean Sea Acidification in a changing climate (MedSeA) project (http://medsea-project.eu). It studies the effects of phosphorus limitation and increased partial pressure of carbon dioxide (pCO2) on different aspects of the biology and ecology of coccolithophores. This thesis starts with an introduction to the studied problem. This is the ocean acidification and phosphorus limitation in the oceans. The organisms under study, the coccolithophores, are also introduced. The last two parts of the introduction expose the objectives of the thesis (exposed as research questions) and an explanation of why the study is performed in the Mediterranean Sea. The following four chapters (chapters 2 to 5) compose the main part of the work. The thesis combines different approaches from culture to mesocosm experiments and field observations, aiming to solve questions at different scale from species to community level. Chapters 2 and 3 are focussing on culture experiments performed on the most abundant modern coccolithophore species, Emiliania huxleyi. The experiments investigate the impacts of phosphorus limitation and ocean acidification on monoclonal E. huxleyi cultures. In Chapter 2 the possible impacts of P limitation are investigated on 6 E. huxleyi clones, 4 of them isolated in the eastern Mediterranean (ultra-oligotrophic) and 2 in the western Mediterranean (oligotrophic to mesotrophic). Chapter 3 presents the results of a second culture experiment designed to test the combined effects of seawater acidification under P limitation in one of the E. huxleyi clones used in the previous experiment. Chapter 4 presents the work performed in two mesocosm experiments conducted off Corsica and Villefrance sur Mer (France). They focussed on the quantification and understating of the impacts of ocean acidification on two different coccolithophore communities inhabiting P poor waters. Finally, Chapter 5 elaborates on field data from 81 samples collected at depths from 0 – 100 m on an east to west transect in the Mediterranean Sea (Meteor Research Vessel, M84-3 cruise, April 2011). The acquired data are used to describe the spring-time coccolithophore distribution in the Mediterranean Sea, which was related to a broad set of in situ measured environmental variables. It is concluded that oligothrophy (i.e. P limitation) amplifies the response to ocean acidification in terms of maximum cell densities. That is, further decreases maximum cell densities. Results on P limitation (Chapter 2) and from other studies in ocean acidification (Meyer & Riebesell 2015) allowed to conclude that E. huxleyi might, in a future P-poor and acidified ocean, contribute relatively little inorganic carbon to exported matter, which would in turn favour remineralization over long term burial at depth. While P limitation does not induce coccolith malformations in E. huxleyi (Chapters 2 and 3), under a long time exposure to enhanced pCO2 and the absence of clone selection, ocean acidification does cause coccolith malformation irrespectively of the [P].

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Houdan, Aude. "Cycle biologique et stratégies de développement chez les coccolithophores (Prymnesiophyceae, Haptophyta) . Implications écologiques." Phd thesis, Université de Caen, 2003. http://tel.archives-ouvertes.fr/tel-00009000.

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Les coccolithophores sont des microalgues calcifiées constituant un des principaux groupes phytoplanctoniques marins. Ces organismes restent cependant encore mal connus, du fait du peu d'espèces cultivées. Dans ce travail, les connaissances sur la biologie et l'écologie de ce groupe ont été approfondies à travers l'étude du cycle de vie et de ses implications écologiques pour quatre coccolithophores en culture : Coccolithus pelagicus, Calcidiscus leptoporus, Coronosphaera mediterranea et Emiliania huxleyi. Un cycle digénétique haplo-diplophasique hétéromorphe a d'abord été démontré par différentes techniques. Des expériences écophysiologiques sur des facteurs abiotiques (température, lumière, turbulence, nutriments) ont ensuite permis d'émettre des hypothèses sur l'influence du cycle digénétique sur l'écologie de ces espèces et d'établir un cycle écologique. Enfin, une étude préliminaire de la toxicité a été réalisée, démontrant la toxicité de cinq espèces côtières de coccolithophores.

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Müller, Marius N. [Verfasser]. "Calcification in coccolithophores : effects of environmental conditions and paleoproxy calibrations / Marius N. Müller." Kiel : Universitätsbibliothek Kiel, 2009. http://d-nb.info/1019868767/34.

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Harington, Amy. "Trace metal effects on phytoplankton in subpolar seas with special emphasis on coccolithophores." Doctoral thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/27354.

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Coccolithophores are a biogeochemically important phytoplankton group, fulfilling an important role in the global carbon cycle through primary production and the formation and export of calcium carbonate. Despite this biogeochemical importance, relatively little is known about their ecophysiology, for example their response to nutrient availability in terms of both macronutrient (nitrate, phosphate) and micronutrient (trace metal) or how this impacts on their competition with other phytoplankton groups (e.g. diatoms, Synechococcus). Hence, this study investigated the response of coccolithophores to trace metal (iron, zinc and cobalt) additions in the high latitude North Atlantic (Iceland and Irminger basins) and the Southern Ocean (Great Calcite Belt, Scotia Sea). The response of coccolithophores to environmental conditions was investigated by examining distribution patterns in situ and in targeted bioassays where natural communities were incubated with elevated levels of trace metal concentration. The wide range of initial conditions for these bioassays (e.g. temperature, macro- and micro-nutrient availability and phytoplankton community composition), provided valuable insights into coccolithophore responses to trace metal addition across a range of different biogeographic regions. These responses were investigated in terms of coccolithophore cell abundances, species composition, calcite production and growth rates, and were contrasted with responses of the total phytoplankton community (chlorophyll α) and abundances of diatoms and other phytoplankton groups (e.g. Synechococcus). The major finding of this thesis is that iron addition positively enhances coccolithophore growth rates and calcite production in both the Northern and Southern subpolar oceans. Another significant finding was that zinc addition also positively enhanced growth rates of coccolithophores (and diatoms) in a number of bioassays across the Great Calcite Belt (Southern Ocean). Thus, the trace metals iron and zinc are important micronutrients to consider in regulating coccolithophore growth and calcite production. As climate change potentially altering the flux of such trace metals to the ocean it is therefore important to further investigate the role of these micronutrients in regulating coccolithophore communities and their biogeochemical impact.

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Moussion, Philippe. "Etude des conditions de culture favorisant la production en photobioréacteur d'un exométabolite algosourcé d'intérêt cosmétique." Thesis, Nantes, 2019. http://www.theses.fr/2019NANT4053.

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Les coccolithophores marines sont des microalgues connues pour leurs efflorescences visibles depuis l’espace. Ces organismes photosynthétiques sont supposés résister à de fortes radiations lumineuses dont les UV-A et UV-B, ce qui les rend intéressantes pour des applications dermo-cosmétiques. L’objectif de l’étude menée était d’identifier et de lever les points de blocage pour la production d’un exométabolite en culture intensifiée. Un criblage a permis la sélection de deux espèces, dont Emiliania huxleyi, sur lesquelles l’effet de limitations en nutriment et lumière sur la croissance, la photosynthèse et la calcification a été exploré en photobioréacteurs. Une analyse cinétique de la compartimentation du phosphate (P) chez E. huxleyi a été menée en lien avec la calcification et la croissance en limitation P. Un paramètre spécifique de culture, principalement le P extracellulaire, a par ailleurs permis la synchronisation du passage des cellules nues à calcifiées. Cette observation originale pour les coccolithophores pourrait permettre de faire avancer les connaissances sur leur cycle de vie. Ces résultats sont discutés sur la base d’un modèle suggérant un rôle pour des molécules riches en P fixatrices du calcium, les polyphosphates, dans la calcification et dans le contrôle du cycle de vie des coccolithophores. Ces données physiologiques ont permis la conception d’un procédé de fed-batch dans un photobioréacteur pilote de laboratoire de 9 L, générant les plus fortes productivités en métabolites jamais reportées pour ces deux espèces
Marine coccolithophores are microalgae known for their blooms visible from space. These photosynthetic microorganisms are presumed to resist to strong light radiation like UV A and B, what make them of great interest for dermo-cosmetic applications. The present study aimed to identify and lift the blocking points for metabolite production in intensified culture. A screening resulted in the selection of two productive species, among them Emiliania huxleyi, on which the effect of nutrient and light limitation on growth, photosynthesis and calcification was investigated in PBR. A kinetic analysis of the phosphate (P) compartmentation in E. huxleyi cultures was examined in relation to calcification and growth under P limitation. A specific culture parameter, mainly extracellular P, was furthermore shown to synchronize the switch from naked to calcifying cells. Such observation has never been reported in the literature for coccolithophores and may actively improve knowledges on their life cycle. These results are discussed on the basis of a model inferring a potential role of calcium binding P rich molecules, the polyphosphates, in the control of calcification and life-cycle of coccolithophores. These physiological data allowed the design of a fed-batch process in a 9 L laboratory pilot photobioreactor, resulting in the highest productivities in metabolites ever reported for these two species

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Crudeli, Daniela. "Early pliocene evolution of coccolithophores in the Caribbean Sea taxonomy, biostratigraphy, paleoecology and paleoceanography /." [S.l.] : [s.n.], 2005. http://e-diss.uni-kiel.de/diss_1760/d1760.pdf.

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Heinle, Moritz. "The effects of light, temperature and nutrients on coccolithophores and implications for biogeochemical models." Thesis, University of East Anglia, 2013. https://ueaeprints.uea.ac.uk/48676/.

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Coccolithophores are one of the important groups of phytoplankton in the global oceans, which makes it important to know how this group will react to changes in their environment due to climate change. Modellers already recognized their importance and included this group independently in global biogeochemical models. This study assesses the effect of light, temperature and nutrient availability on five coccolithophores, performing a range of laboratory experiments. The results of these experiments were then used to change the parameterisation of coccolithophores in the global biogeochemical model PlankTOM10. Furthermore, the model was validated in two ways, using a database of coccolithophore biomass measurements from the field and measurements of surface calcium carbonate derived from satellite data. Temperature effects on growth depend a great deal on the coccolithophore species. E. huxleyi (both, a subtropical and a temperate strain) and P. carterae grew best around 20°C, whereas G. oceanica and C. leptoporus had optimum temperatures above 25°C and still grew well at the maximum temperature tested in the experiments. E. huxleyi was the species with the highest growth rates (μmax=0.98 for the subtropical strain and μmax=0.97 for the temperate), followed closely by G. oceanica and C. leptoporus (μmax=0.91 in both species). P. carterae (μmax=0.77) had a noticeably lower maximum growth rate than the other coccolithophores. An inverse relationship with growth rate was found for all measured cellular components (POM, PIC, Chl a) as well as for cell volume in P. carterae. Coccolithophores are good competitors at high light intensities, having optimum growth light intensities above 180 μmol photons m-2 s-1. The temperate strain of E. huxleyi and the species G. oceanica showed the lowest optima at 350 μmol photon III m-2 s-1. C. leptoporus (Iopt=500 μmol photon m-2 s-1) and P. carterae (Iopt=600 μmol photon m-2 s-1) had higher optimum growth light intensities and the subtropical strain of E. huxleyi (Iopt=900 μmol photon m-2 s-1) grew best at the highest light intensity applied in this study. Only one strain of E. huxleyi showed light inhibition in its photosynthetic activity that was well above the detection limit in P-I curves up to 2000 μmol photons m-2 s-1. Apart from a well-known decrease in Chl a/C ratio with increasing light intensity, little variation in the concentration of cellular components (POM, PIC) was observed. Nutrient experiments were carried out in a chemostat with two strains of E. huxleyi and one G. oceanica. Phosphorus limitation led to an increase in cell volume (112- 157%) and particulate organic carbon (21-54%) in E. huxleyi and G. oceanica, relative to cultures grown under nitrogen limitation. Comparison of uptake rates for phosphate and nitrate with other phytoplankton groups showed that both species are very good competitors for phosphate and relatively poor competitors for nitrate. The initial PlankTOM10 model simulation overestimated biomass compared with a new observational database, and underestimated surface calcium carbonate compared with satellite data. Changing the coccolithophore parameterisation in PlankTOM10, based on the laboratory results, did not lead to significant improvements relative to the observations. However, the response of the model to the parameter changes could be explained either directly from the changed parameters, or indirectly from changes in the model ecosystem.

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