scholarly journals Influence of CO<sub>2</sub> and nitrogen limitation on the coccolith volume of <i>Emiliania huxleyi</i> (Haptophyta)

2012 ◽  
Vol 9 (4) ◽  
pp. 4979-5010 ◽  
Author(s):  
M. N. Müller ◽  
L. Beaufort ◽  
O. Bernard ◽  
M. L. Pedrotti ◽  
A. Talec ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Photosynthetic Activity ◽  
Co2 Concentration ◽  
Emiliania Huxleyi ◽  
Cell Diameter ◽  
Geometrical Parameters ◽  
Carbon Production ◽  
Seawater Carbonate Chemistry ◽  
Particulate Inorganic Carbon ◽  
Phytoplankton Group

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

scholarly journals Influence of CO<sub>2</sub> and nitrogen limitation on the coccolith volume of <I>Emiliania huxleyi</I> (Haptophyta)

2012 ◽  
Vol 9 (10) ◽  
pp. 4155-4167 ◽  
Author(s):  
M. N. Müller ◽  
L. Beaufort ◽  
O. Bernard ◽  
M. L. Pedrotti ◽  
A. Talec ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Particulate Organic Carbon ◽  
Nitrogen Limitation ◽  
Co2 Concentration ◽  
Emiliania Huxleyi ◽  
Cell Diameter ◽  
Geometrical Parameters ◽  
Carbon Production ◽  
Seawater Carbonate Chemistry ◽  
Particulate Inorganic Carbon

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

scholarly journals Strain-specific responses of <i>Emiliania huxleyi</i> to changing seawater carbonate chemistry

2009 ◽  
Vol 6 (2) ◽  
pp. 4361-4383 ◽  
Author(s):  
G. Langer ◽  
G. Nehrke ◽  
I. Probert ◽  
J. Ly ◽  
P. Ziveri
Keyword(s):  
Carbon Content ◽  
Genetic Basis ◽  
Inorganic Carbon ◽  
Emiliania Huxleyi ◽  
Organic Carbon Content ◽  
Carbonate Chemistry ◽  
Carbon Production ◽  
Seawater Carbonate Chemistry ◽  
Different Strains ◽  
Particulate Inorganic Carbon

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

scholarly journals Short-term response of the coccolithophore <i>Emiliania huxleyi</i> to abrupt changes in seawater carbon dioxide concentrations

2009 ◽  
Vol 6 (3) ◽  
pp. 4739-4763 ◽  
Author(s):  
J. Barcelos e Ramos ◽  
M. N. Müller ◽  
U. Riebesell
Keyword(s):  
Organic Carbon ◽  
Carbon Fixation ◽  
Emiliania Huxleyi ◽  
Carbonate Chemistry ◽  
Short Term ◽  
Co2 Concentrations ◽  
Lack Of Information ◽  
Seawater Carbonate Chemistry ◽  
Time Required ◽  
Term Response

Abstract. The response of the coccolithophore Emiliania huxleyi to rising CO2 concentrations is well documented in acclimated cultures where cells are exposed to the CO2 treatments for several generations prior to the experiment. Extended acclimation times have generally been applied because of the lack of information about time required to reach a new physiological "equilibrium" (acclimation) in response to CO2-induced changes in seawater carbonate chemistry. Here we show that Emiliania huxleyi's short-term response (hours to 1 day) to increasing CO2 is similar to that obtained with acclimated cultures under comparable conditions in earlier studies. At CO2 concentrations ranging from glacial (190 μatm) to projected year 2100 (750 μatm) levels, calcification decreased and organic carbon fixation increased within 8 h after exposing the cultures to the changed CO2 conditions. This led to a decrease in the ratio of CaCO3 to organic carbon production. Our results show that Emiliania huxleyiapidly alters the rates of various essential processes in response to changes in seawater carbonate chemistry, establishing a new physiological (acclimation) "state" within a matter of hours. If this relatively rapid response applies to other phytoplankton species, it may simplify interpretation of studies with natural communities (e.g. mesocosm studies and ship-board incubations), where often it is not feasible to allow for a pre-conditioning phase before starting experimental incubations.

scholarly journals Lateral, Vertical, and Temporal Variability of Seawater Carbonate Chemistry at Hog Reef, Bermuda

2021 ◽  
Vol 8 ◽  
Author(s):  
Ariel K. Pezner ◽  
Travis A. Courtney ◽  
Heather N. Page ◽  
Sarah N. Giddings ◽  
Cory M. Beatty ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Organic Carbon ◽  
Water Column ◽  
Temporal Variability ◽  
Current Flow ◽  
Biogeochemical Processes ◽  
Carbonate Chemistry ◽  
Carbonate Production ◽  
Carbon Production ◽  
Seawater Carbonate Chemistry

Spatial and temporal carbonate chemistry variability on coral reefs is influenced by a combination of seawater hydrodynamics, geomorphology, and biogeochemical processes, though their relative influence varies by site. It is often assumed that the water column above most reefs is well-mixed with small to no gradients outside of the benthic boundary layer. However, few studies to date have explored the processes and properties controlling these multi-dimensional gradients. Here, we investigated the lateral, vertical, and temporal variability of seawater carbonate chemistry on a Bermudan rim reef using a combination of spatial seawater chemistry surveys and autonomous in situ sensors. Instruments were deployed at Hog Reef measuring current flow, seawater temperature, salinity, pHT, pCO2, dissolved oxygen (DO), and total alkalinity (TA) on the benthos, and temperature, salinity, DO, and pCO2 at the surface. Water samples from spatial surveys were collected from surface and bottom depths at 13 stations covering ∼3 km2 across 4 days. High frequency temporal variability in carbonate chemistry was driven by a combination of diel light and mixed semi-diurnal tidal cycles on the reef. Daytime gradients in DO between the surface and the benthos suggested significant water column production contributing to distinct diel trends in pHT, pCO2, and DO, but not TA. We hypothesize these differences reflect the differential effect of biogeochemical processes important in both the water column and benthos (organic carbon production/respiration) vs. processes mainly occurring on the benthos (calcium carbonate production/dissolution). Locally at Hog Reef, the relative magnitude of the diel variability of organic carbon production/respiration was 1.4–4.6 times larger than that of calcium carbonate production/dissolution, though estimates of net organic carbon production and calcification based on inshore-offshore chemical gradients revealed net heterotrophy (−118 ± 51 mmol m–2 day–1) and net calcification (150 ± 37 mmol CaCO3 m–2 day–1). These results reflect the important roles of time and space in assessing reef biogeochemical processes. The spatial variability in carbonate chemistry parameters was larger laterally than vertically and was generally observed in conjunction with depth gradients, but varied between sampling events, depending on time of day and modifications due to current flow.

scholarly journals Strain-specific responses of <i>Emiliania huxleyi</i> to changing seawater carbonate chemistry

2009 ◽  
Vol 6 (11) ◽  
pp. 2637-2646 ◽  
Author(s):  
G. Langer ◽  
G. Nehrke ◽  
I. Probert ◽  
J. Ly ◽  
P. Ziveri
Keyword(s):  
Carbon Content ◽  
Genetic Basis ◽  
Inorganic Carbon ◽  
Response Pattern ◽  
Organic Carbon Content ◽  
Carbonate Chemistry ◽  
Carbon Production ◽  
Seawater Carbonate Chemistry ◽  
Different Strains ◽  
Particulate Inorganic Carbon

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

scholarly journals Organic matter exudation by <i>Emiliania huxleyi</i> under simulated future ocean conditions

2012 ◽  
Vol 9 (1) ◽  
pp. 1199-1236 ◽  
Author(s):  
C. Borchard ◽  
A. Engel
Keyword(s):  
Molecular Weight ◽  
Organic Carbon ◽  
Elevated Co2 ◽  
Emiliania Huxleyi ◽  
Greenhouse Condition ◽  
Pronounced Increase ◽  
Temperature Conditions ◽  
Extracellular Release ◽  
Aggregation Processes ◽  
Elevated Co2 And Temperature

Abstract. Emiliania huxleyi (strain B 92/11) was exposed to different growth, CO2 and temperature conditions in phosphorous controlled chemostats, to investigate effects on organic carbon exudation, and partitioning between the pools of particulate organic carbon (POC) and dissolved organic carbon (DOC). 14C incubation measurements for primary production (PP) and for extracellular release (ER) were performed. Chemical analysis included amount and composition of high molecular weight dissolved combined carbohydrates (>1 kDa, HMW-dCCHO), particulate combined carbohydrates (pCCHO) and the carbon content of transparent exopolymer particles (TEP-C). Applied CO2 and temperature conditions were 300, 550 and 900 μatm pCO2 at 14 °C, and additionally 900 μatm pCO2 at 18 °C simulating a greenhouse ocean scenario. A reduction in growth rate from μ =0.3 d−1 to μ =0.1 d−1 induced the most profound effect on the performance of E. huxleyi, relative to the effect of elevated CO2 and temperature. At μ =0.3 d−1, PP was significantly higher at elevated CO2 and temperature. DO14C production correlated to PO14C production in all cultures, resulting in similar percentages of extracellular release (DO14C/PP × 100; PER) of averaged 3.74 &amp;pm; 0.94%. At μ =0.1 d−1, PO14C decreased significantly, while exudation of DO14C increased, thus leading to a stronger partitioning from the particulate to the dissolved pool. Maximum PER of 16.3 &amp;pm; 2.3% were observed at μ =0.1 d−1 at greenhouse conditions. Concentrations of HMW-dCCHO and pCCHO were generally higher at μ =0.1 d−1 compared to μ =0.3 d−1. At μ =0.3 d−1, pCCHO concentration increased significantly along with elevated CO2 and temperature. Despite of high PER, the percentage of HMW-dCCHO was smallest at greenhouse conditions. However, highest TEP-formation was observed under greenhouse conditions, together with a pronounced increase in pCCHO concentration, suggesting a stronger partitioning of PP from DOC to POC by coagulation of exudates. Our results imply that greenhouse condition will enhance exudation processes in E. huxleyi and may affect organic carbon partitioning in the ocean due to an enhanced transfer of HMW-dCCHO to TEP by aggregation processes.

scholarly journals Generic analysis of the response of calcifying microalgae to an elevation of pCO2 : qualitative vs quantitative analysis

2008 ◽  
Vol Volume 9, 2007 Conference in... ◽  
Author(s):  
Olivier Bernard ◽  
Antoine Sciandre
Keyword(s):  
Large Scale ◽  
Co2 Concentration ◽  
Emiliania Huxleyi ◽  
Atmospheric Co2 ◽  
Quantitative Prediction ◽  
General Level ◽  
Sont Encore ◽  
Chemostat Cultures ◽  
International Audience ◽  
Parameter Values

International audience Calcifying microalgae can play a key role in atmospheric CO2 trapping through large scale precipitation of calcium carbonate in the oceans. However, recent experiments revealed that the associated fluxes may be slow down by an increase in atmospheric CO2 concentration. In this paper we design models to account for the decrease in calcification and photosynthesis rates observed after an increase of pCO2 in Emiliania huxleyi chemostat cultures. Since the involved mechanisms are still not completely understood, we consider various models, each of them being based on a different hypothesis. These models are kept at a very general level, by maintaining the growth and calcification functions in a generic form, i.e. independent on the exact shape of these functions and on parameter values. The analysis is thus performed using these generic functions where the only hypothesis is an increase of these rates with respect to the regulating carbon species. As a result, each model responds differently to a pCO2 elevation. Surprisingly, the only models whose behaviour are in agreement with the experimental results correspond to carbonate as the regulating species for photosynthesis. Finally we show that the models whose qualitative behaviour are wrong could be considered as acceptable on the basis of a quantitative prediction error criterion. Les microalgues calcifiantes jouent un rôle clé dans le piégeage du CO2 atmosphérique d’origine anthropique en précipitant du carbonate de calcium qui sédimente au fond des océans. Toutefois, des expériences en laboratoire ont suggéré que cette activité biologique pourrait être diminuée par l’augmentation de la pression partielle de CO2 (pCO2) dans les océans qui a tendance à s’ équilibrer avec celle de l’atmosphère. Dans ce papier, nous concevons des modèles dynamiques pour essayer de simuler la diminution des taux de calcification et de photosynthèse observés chez Emiliania huxleyi après une hausse de la pCO2 reproduite en chémostat. Comme les mécanismes physiologiques impliqués sont encore loin d’ être complètement élucidés, nous considérons différents modèles, chacun d’eux étant basé sur une hypothèse biologique différente. Ces modèles, construits en utilisant des fonctions génériques pour caractériser les processus de croissance et de calcification, peuvent être analysés indépendamment de la forme exacte de ces fonctions et de la valeur des paramètres. L’ étude s’appuie donc sur ces fonctions génériques où la seule hypothèse est une régulation de ces taux par une des trois formes qui composent la totalité du carbone inorganique dissous : le CO2, les carbonates et les bicarbonates. Il s’en suit que chaque modèle réagit différemment à une élévation de la pCO2. Contrairement aux hypothèses classiquement admises, notre étude montre que les seuls modèles dont le comportement est en accord avec les résultats expérimentaux sont ceux pour lesquels une régulation de la photosynthèse par les carbonates a été supposée, ce qui corrobore les conclusions de travaux récents. Enfin, nous montrons que les modèles dont le comportement qualitatif est mauvais ne seraient pas rejetés sur la base d’un critère quantitatif d’erreur de prédiction.

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