Coral reefs and changing seawater carbonate chemistry

2006 ◽  
pp. 73-110 ◽  
Author(s):  
Joan A. Kleypas ◽  
Chris Langdon
Keyword(s):  
Coral Reefs ◽  
Carbonate Chemistry ◽  
Seawater Carbonate Chemistry

scholarly journals Dynamics of seawater carbonate chemistry, production, and calcification of a coral reef flat, central Great Barrier Reef

2013 ◽  
Vol 10 (10) ◽  
pp. 6747-6758 ◽  
Author(s):  
R. Albright ◽  
C. Langdon ◽  
K. R. N. Anthony
Keyword(s):  
Coral Reef ◽  
Coral Reefs ◽  
Great Barrier Reef ◽  
Reef Flat ◽  
Global Scale ◽  
Barrier Reef ◽  
Carbonate Chemistry ◽  
Saturation State ◽  
Diel Cycles ◽  
Seawater Carbonate Chemistry

Abstract. Ocean acidification is projected to shift coral reefs from a state of net accretion to one of net dissolution this century. Presently, our ability to predict global-scale changes to coral reef calcification is limited by insufficient data relating seawater carbonate chemistry parameters to in situ rates of reef calcification. Here, we investigate diel and seasonal trends in carbonate chemistry of the Davies Reef flat in the central Great Barrier Reef and relate these trends to benthic carbon fluxes by quantifying net ecosystem calcification (nec) and net community production (ncp). Results show that seawater carbonate chemistry of the Davies Reef flat is highly variable over both diel and seasonal cycles. pH (total scale) ranged from 7.92 to 8.17, pCO2 ranged from 272 to 542 μatm, and aragonite saturation state (Ωarag) ranged from 2.9 to 4.1. Diel cycles in carbonate chemistry were primarily driven by ncp, and warming explained 35% and 47% of the seasonal shifts in pCO2 and pH, respectively. Daytime ncp averaged 37 ± 19 mmol C m−2 h−1 in summer and 33 ± 13 mmol C m−2 h−1 in winter; nighttime ncp averaged −30 ± 25 and −7 ± 6 mmol C m−2 h−1 in summer and winter, respectively. Daytime nec averaged 11 ± 4 mmol CaCO3 m−2 h−1 in summer and 8 ± 3 mmol CaCO3 m−2 h−1 in winter, whereas nighttime nec averaged 2 ± 4 mmol and −1 ± 3 mmol CaCO3 m−2 h−1 in summer and winter, respectively. Net ecosystem calcification was highly sensitive to changes in Ωarag for both seasons, indicating that relatively small shifts in Ωarag may drive measurable shifts in calcification rates, and hence carbon budgets, of coral reefs throughout the year.

scholarly journals Evaluation of a semi-automatic system for long-term seawater carbonate chemistry manipulation

2013 ◽  
Vol 86 (4) ◽  
pp. 443-451 ◽  
Author(s):  
RODRIGO TORRES ◽  
PATRICIO H MANRIQUEZ ◽  
CRISTIAN DUARTE ◽  
JORGE M NAVARRO ◽  
NELSON A LAGOS ◽  
...  
Keyword(s):  
Automatic System ◽  
Carbonate Chemistry ◽  
Seawater Carbonate Chemistry

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 CO2 sensitivity experiments are not sufficient to show an effect of ocean acidification

2016 ◽  
Vol 74 (4) ◽  
pp. 926-928 ◽  
Author(s):  
Paul McElhany
Keyword(s):  
Ocean Acidification ◽  
Population Level ◽  
Population Abundance ◽  
Laboratory Studies ◽  
Species Sensitivity ◽  
Carbonate Chemistry ◽  
Marine Carbonate ◽  
Seawater Carbonate Chemistry ◽  
Experimental Treatments ◽  
Level Effect

The ocean acidification (OA) literature is replete with laboratory studies that report species sensitivity to seawater carbonate chemistry in experimental treatments as an “effect of OA”. I argue that this is unintentionally misleading, since these studies do not actually demonstrate an effect of OA but rather show sensitivity to CO2. Documenting an effect of OA involves showing a change in a species (e.g. population abundance or distribution) as a consequence of anthropogenic changes in marine carbonate chemistry. To date, there have been no unambiguous demonstrations of a population level effect of anthropogenic OA, as that term is defined by the IPCC.

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 Perturbation experiments to investigate the impact of ocean acidification: approaches and software tools

2009 ◽  
Vol 6 (2) ◽  
pp. 4413-4439 ◽  
Author(s):  
J.-P. Gattuso ◽  
H. Lavigne
Keyword(s):  
Ocean Acidification ◽  
Software Package ◽  
Biological Response ◽  
Experimental Manipulation ◽  
Carbonate Chemistry ◽  
R Software ◽  
Seawater Chemistry ◽  
Seawater Carbonate Chemistry ◽  
Gas Bubbling ◽  
The Impact

Abstract. Although future changes in the seawater carbonate chemistry are well constrained, their impact on marine organisms and ecosystems remains poorly known. The biological response to ocean acidification is a recent field of research as most purposeful experiments have only been carried out in the late 1990s. The potentially dire consequences of ocean acidification attract scientists and students with a limited knowledge of the carbonate chemistry and its experimental manipulation. Hence, some guidelines on carbonate chemistry manipulations may be helpful for the growing ocean acidification community to maintain comparability. Perturbation experiments are one of the key approaches used to investigate the biological response to elevated pCO2. They are based on measurements of physiological or metabolic processes in organisms and communities exposed to seawater with normal or altered carbonate chemistry. Seawater chemistry can be manipulated in different ways depending on the facilities available and on the question being addressed. The goal of this paper is (1) to examine the benefits and drawbacks of various manipulation techniques and (2) to describe a new version of the R software package seacarb which includes new functions aimed at assisting the design of ocean acidification perturbation experiments. Three approaches closely mimic the on-going and future changes in the seawater carbonate chemistry: gas bubbling, addition of high-CO2 seawater as well as combined additions of acid and bicarbonate and/or carbonate.

scholarly journals Continuous fluorescence-based monitoring of seawater pH in a temperate estuary

2017 ◽  
Author(s):  
John W. Runcie ◽  
Christian Krause ◽  
Sergio A. Torres Gabarda ◽  
Maria Byrne
Keyword(s):  
Surface Waters ◽  
Ph Monitoring ◽  
Good Resolution ◽  
Carbonate Chemistry ◽  
Temperature Drift ◽  
Seawater Ph ◽  
Calcite Saturation ◽  
Seawater Carbonate Chemistry ◽  
Diel Variability ◽  
Diel Fluctuations

Abstract. Abstract. Electrical conductivity (salinity), temperature and fluorescence-based measurements of pH were employed to examine diel fluctuations in seawater carbonate chemistry of surface waters in Sydney Harbour over two multiple-day periods. The fluorescence-based technique provided a useful time-series for pH. Alkalinity with pH and temperature were used to calculate the degree of aragonite and calcite saturation (ΩCa and ΩAr respectively). Alkalinity was determined from an alkalinity-salinity relationship. Variation in pH over minute- to hour-long periods was distinguishable from background variability. Diel variability in pH, Ωara and Ωcal showed a clear pattern that appeared to correlate with both salinity and temperature. Drift due to photodegradation of the fluorophore was minimised by reducing exposure to ambient light. ΩCa and ΩAr fluctuated approximately on a daily cycle. The net result of changes in pH, salinity and temperature combined to influence seawater carbonate chemistry. The fluorescence-based pH monitoring technique is simple, provides good resolution and is unaffected by moving parts or leaching of solutions over time. The use of optics is pressure insensitive, making this approach to ocean acidification monitoring well suited to deepwater applications.

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