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

2010 ◽  
Vol 7 (1) ◽  
pp. 177-186 ◽  
Author(s):  
J. Barcelos e Ramos ◽  
M. N. Müller ◽  
U. Riebesell
Keyword(s):  
Carbon Fixation ◽  
Physiological State ◽  
Emiliania Huxleyi ◽  
Carbonate Chemistry ◽  
Short Term ◽  
Co2 Concentrations ◽  
Carbon Dioxide Concentrations ◽  
Seawater Carbonate Chemistry ◽  
Induced Changes ◽  
Term Response

Abstract. The response of the coccolithophore Emiliania huxleyi to rising CO2 concentrations is well documented for acclimated cultures where cells are exposed to the CO2 treatments for several generations prior to the experiment. The exact number of generations required for acclimation to CO2-induced changes in seawater carbonate chemistry, however, is unknown. Here we show that Emiliania huxleyi's short-term response (26 h) after cultures (grown at 500 μatm) were abruptly exposed to changed CO2 concentrations (~190, 410, 800 and 1500 μatm) is similar to that obtained with acclimated cultures under comparable conditions in earlier studies. Most importantly, from the lower CO2 levels (190 and 410 μatm) to 750 and 1500 μatm calcification decreased and organic carbon fixation increased within the first 8 to 14 h after exposing the cultures to changes in carbonate chemistry. This suggests that Emiliania huxleyi rapidly alters the rates of essential metabolical processes in response to changes in seawater carbonate chemistry, establishing a new physiological "state" (acclimation) 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 The role of ocean acidification in <i>Emiliania huxleyi</i> coccolith thinning in the Mediterranean Sea

2014 ◽  
Vol 11 (10) ◽  
pp. 2857-2869 ◽  
Author(s):  
K. J. S. Meier ◽  
L. Beaufort ◽  
S. Heussner ◽  
P. Ziveri
Keyword(s):  
Ocean Acidification ◽  
Mediterranean Sea ◽  
Abundant Species ◽  
Emiliania Huxleyi ◽  
Carbonate Chemistry ◽  
Carbonate Production ◽  
Surface Ocean ◽  
Nw Mediterranean ◽  
Seawater Carbonate Chemistry

Abstract. Ocean acidification is a result of the uptake of anthropogenic CO2 from the atmosphere into the ocean and has been identified as a major environmental and economic threat. The release of several thousands of petagrams of carbon over a few hundred years will have an overwhelming effect on surface ocean carbon reservoirs. The recorded and anticipated changes in seawater carbonate chemistry will presumably affect global oceanic carbonate production. Coccolithophores as the primary calcifying phytoplankton group, and especially Emiliania huxleyi as the most abundant species have shown a reduction of calcification at increased CO2 concentrations for the majority of strains tested in culture experiments. A reduction of calcification is associated with a decrease in coccolith weight. However, the effect in monoclonal cultures is relatively small compared to the strong variability displayed in natural E. huxleyi communities, as these are a mix of genetically and sometimes morphologically distinct types. Average coccolith weight is likely influenced by the variability in seawater carbonate chemistry in different parts of the world's oceans and on glacial/interglacial time scales due to both physiological effects and morphotype selectivity. An effect of the ongoing ocean acidification on E. huxleyi calcification has so far not been documented in situ. Here, we analyze E. huxleyi coccolith weight from the NW Mediterranean Sea in a 12-year sediment trap series, and surface sediment and sediment core samples using an automated recognition and analyzing software. Our findings clearly show (1) a continuous decrease in the average coccolith weight of E. huxleyi from 1993 to 2005, reaching levels below pre-industrial (Holocene) and industrial (20th century) values recorded in the sedimentary record and (2) seasonal variability in coccolith weight that is linked to the coccolithophore productivity. The observed long-term decrease in coccolith weight is most likely a result of the changes in the surface ocean carbonate system. Our results provide the first indications of an in situ impact of ocean acidification on coccolithophore weight in a natural E. huxleyi population, even in the highly alkaline Mediterranean Sea.

scholarly journals Influence of changing carbonate chemistry on morphology and weight of coccoliths formed by <i>Emiliania huxleyi</i>

2012 ◽  
Vol 9 (8) ◽  
pp. 3449-3463 ◽  
Author(s):  
L. T. Bach ◽  
C. Bauke ◽  
K. J. S. Meier ◽  
U. Riebesell ◽  
K. G. Schulz
Keyword(s):  
Sediment Cores ◽  
Emiliania Huxleyi ◽  
Marine Phytoplankton ◽  
Carbonate Chemistry ◽  
Production Rates ◽  
Organic Part ◽  
Carbonate Ion ◽  
Seawater Carbonate Chemistry ◽  
Decreasing Ph ◽  
Carbon Dioxide Co2

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

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 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 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.

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