Erratum to: Dissolved inorganic carbon and total alkalinity of a Hawaiian fringing reef: chemical techniques for monitoring the effects of ocean acidification on coral reefs

A national observing network has been operating over the past 4 years to inform the scientific and economic challenges of ocean acidification (OA) facing New Zealand. The New Zealand Ocean Acidification Observing Network (NZOA-ON) consists of 12 sites across varied coastal ecosystems. These ecosystems range from oligotrophic ocean-dominated systems to eutrophic river-dominated systems, with sites that are pristine or affected by agriculture and urbanisation. Fortnightly measurements of total alkalinity and dissolved inorganic carbon provide the baseline of carbonate chemistry in these varied ecosystems and will facilitate detection of future changes, as well as providing a present-day baseline. The National Institute of Water and Atmospheric Research and the University of Otago have developed a ‘grass-roots’ sampling program, providing training and equipment that enable sampling partners to collect field samples for analyses at a central laboratory. NZOA-ON leverages existing infrastructure and partnerships to maximise data captured for understanding the drivers of chemical changes associated with OA and ecological responses. NZOA-ON coordinates with and contributes to global initiatives to understand and mitigate the broader impacts of OA. A description of NZOA-ON is presented with preliminary analyses and comparison of data from different sites after the first 4 years of the network.

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Development of a Biogeochemical and Carbon Model Related to Ocean Acidification Indices with an Operational Ocean Model Product in the North Western Pacific

Sustainability ◽

10.3390/su11092677 ◽

2019 ◽

Vol 11 (9) ◽

pp. 2677 ◽

Cited By ~ 3

Author(s):

Miho Ishizu ◽

Yasumasa Miyazawa ◽

Tomohiko Tsunoda ◽

Xinyu Guo

Keyword(s):

Ocean Acidification ◽

General Circulation ◽

Inorganic Carbon ◽

Dissolved Inorganic Carbon ◽

Ocean Model ◽

Western Pacific ◽

Total Alkalinity ◽

The North ◽

North Western ◽

North Western Pacific

We developed a biogeochemical and carbon model (JCOPE_EC) coupled with an operational ocean model for the North Western Pacific. JCOPE_EC represents ocean acidification indices on the background of the risks due to ocean acidification and our model experiences. It is an off-line tracer model driven by a high-resolution regional ocean general circulation model (JCOPE2M). The results showed that the model adequately reproduced the general patterns in the observed data, including the seasonal variability of chlorophyll-a, dissolved inorganic nitrogen/phosphorus, dissolved inorganic carbon, and total alkalinity. We provide an overview of this system and the results of the model validation based on the available observed data. Sensitivity analysis using fixed values for temperature, salinity, dissolved inorganic carbon and total alkalinity helped us identify which variables contributed most to seasonal variations in the ocean acidification indices, pH and Ωarg. The seasonal variation in the pHinsitu was governed mainly by balances of the change in temperature and dissolved inorganic carbon. The seasonal increase in Ωarg from winter to summer was governed mainly by dissolved inorganic carbon levels.

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Total alkalinity minus dissolved inorganic carbon as a proxy for deciphering ocean acidification mechanisms

Marine Chemistry ◽

10.1016/j.marchem.2020.103791 ◽

2020 ◽

Vol 222 ◽

pp. 103791 ◽

Cited By ~ 3

Author(s):

Liang Xue ◽

Wei-Jun Cai

Keyword(s):

Ocean Acidification ◽

Inorganic Carbon ◽

Dissolved Inorganic Carbon ◽

Total Alkalinity

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The DIC carbon isotope evolutions during CO2 bubbling: implications for ocean acidification laboratory culture

10.31223/x5334w ◽

2022 ◽

Author(s):

Hongrui Zhang ◽

Ismael Torres-Romero ◽

Pien Anjewierden ◽

Madalina Jaggi ◽

Heather Stoll

Keyword(s):

Ocean Acidification ◽

Carbon Isotope ◽

Inorganic Carbon ◽

Dissolved Inorganic Carbon ◽

Carbon Isotope Ratio ◽

Laboratory Culture ◽

Total Alkalinity ◽

Isotopic Tracers ◽

Physiological Processes ◽

Isotope Equilibrium

Ocean acidification increases pCO2 and decreases pH of seawater and its impact on marine organisms has emerged as a key research focus. In addition to directly measured variables such as growth or calcification rate, stable isotopic tracers such as carbon isotopes have also been used to more completely understand the physiological processes contributing to the response of organisms to ocean acidification. To simulate ocean acidification in laboratory cultures, direct bubbling of seawater with CO2 has been a preferred method because it adjusts pCO2 and pH without altering total alkalinity. Unfortunately, the carbon isotope equilibrium between seawater and CO2 gas has been largely ignored so far. Frequently, the dissolved inorganic carbon (DIC) in the initial seawater culture has a distinct 13C/12C ratio which is far from the equilibrium expected with the isotopic composition of the bubbled CO2. To evaluate the consequences of this type of experiment for isotopic work, we measured the carbon isotope evolutions in two chemostats during CO2 bubbling and composed a numerical model to simulate this process. The isotopic model can predict well the carbon isotope ratio of dissolved inorganic carbon evolutions during bubbling. With help of this model, the carbon isotope evolution during a batch and continuous culture can be traced dynamically improving the accuracy of fractionation results from laboratory culture. Our simulations show that if not properly accounted for in experimental or sampling design, many typical culture configurations involving CO2 bubbling can lead to large errors in estimated carbon isotope fractionation between seawater and biomass or biominerals, consequently affecting interpretations and hampering comparisons among different experiments. Therefore, we describe the best practices on future studies working with isotope fingerprinting in the ocean acidification background.

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CO<sub>2</sub> perturbation experiments: similarities and differences between dissolved inorganic carbon and total alkalinity manipulations

Biogeosciences ◽

10.5194/bg-6-2145-2009 ◽

2009 ◽

Vol 6 (10) ◽

pp. 2145-2153 ◽

Cited By ~ 80

Author(s):

K. G. Schulz ◽

J. Barcelos e Ramos ◽

R. E. Zeebe ◽

U. Riebesell

Keyword(s):

Ocean Acidification ◽

Inorganic Carbon ◽

Dissolved Inorganic Carbon ◽

Total Alkalinity ◽

Calcium Carbonate Precipitation ◽

Carbonate Chemistry ◽

Carbonate System ◽

Experimental Conditions ◽

Saturation State ◽

Basic Approaches

Abstract. Increasing atmospheric carbon dioxide (CO2) through human activities and invasion of anthropogenic CO2 into the surface ocean alters the seawater carbonate chemistry, increasing CO2 and bicarbonate (HCO3−) at the expense of carbonate ion (CO32−) concentrations. This redistribution in the dissolved inorganic carbon (DIC) pool decreases pH and carbonate saturation state (Ω). Several components of the carbonate system are considered potential key variables influencing for instance calcium carbonate precipitation in marine calcifiers such as coccolithophores, foraminifera, corals, mollusks and echinoderms. Unravelling the sensitivities of marine organisms and ecosystems to CO2 induced ocean acidification (OA) requires well-controlled experimental setups and accurate carbonate system manipulations. Here we describe and analyse the chemical changes involved in the two basic approaches for carbonate chemistry manipulation, i.e. changing DIC at constant total alkalinity (TA) and changing TA at constant DIC. Furthermore, we briefly introduce several methods to experimentally manipulate DIC and TA. Finally, we examine responses obtained with both approaches using published results for the coccolithophore Emiliania huxleyi. We conclude that under most experimental conditions in the context of ocean acidification DIC and TA manipulations yield similar changes in all parameters of the carbonate system, which implies direct comparability of data obtained with the two basic approaches for CO2 perturbation.

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Effects of diurnally oscillating p CO 2 on the calcification and survival of coral recruits

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2011.2545 ◽

2012 ◽

Vol 279 (1740) ◽

pp. 2951-2958 ◽

Cited By ~ 82

Author(s):

Aaron M. Dufault ◽

Vivian R. Cumbo ◽

Tung-Yung Fan ◽

Peter J. Edmunds

Keyword(s):

Coral Reefs ◽

Ocean Acidification ◽

Inorganic Carbon ◽

Dissolved Inorganic Carbon ◽

Diurnal Variations ◽

Night Time ◽

Reverse Phase ◽

Effect On Growth

Manipulative studies have demonstrated that ocean acidification (OA) is a threat to coral reefs, yet no experiments have employed diurnal variations in p CO 2 that are ecologically relevant to many shallow reefs. Two experiments were conducted to test the response of coral recruits (less than 6 days old) to diurnally oscillating p CO 2 ; one exposing recruits for 3 days to ambient (440 µatm), high (663 µatm) and diurnally oscillating p CO 2 on a natural phase (420–596 µatm), and another exposing recruits for 6 days to ambient (456 µatm), high (837 µatm) and diurnally oscillating p CO 2 on either a natural or a reverse phase (448–845 µatm). In experiment I, recruits exposed to natural-phased diurnally oscillating p CO 2 grew 6–19% larger than those in ambient or high p CO 2 . In experiment II, recruits in both high and natural-phased diurnally oscillating p CO 2 grew 16 per cent larger than those at ambient p CO 2 , and this was accompanied by 13–18% higher survivorship; the stimulatory effect on growth of oscillatory p CO 2 was diminished by administering high p CO 2 during the day (i.e. reverse-phased). These results demonstrate that coral recruits can benefit from ecologically relevant fluctuations in p CO 2 and we hypothesize that the mechanism underlying this response is highly p CO 2 -mediated, night-time storage of dissolved inorganic carbon that fuels daytime calcification.

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Implications of salinity normalization of seawater total alkalinity in coral reef metabolism studies

PLoS ONE ◽

10.1371/journal.pone.0261210 ◽

2021 ◽

Vol 16 (12) ◽

pp. e0261210

Author(s):

Travis A. Courtney ◽

Tyler Cyronak ◽

Alyssa J. Griffin ◽

Andreas J. Andersson

Keyword(s):

Coral Reef ◽

Coral Reefs ◽

Surface Runoff ◽

Inorganic Carbon ◽

Dissolved Inorganic Carbon ◽

Total Alkalinity ◽

Mixing Processes ◽

Carbonate Production ◽

Freshwater Inputs ◽

Global Datasets

Salinity normalization of total alkalinity (TA) and dissolved inorganic carbon (DIC) data is commonly used to account for conservative mixing processes when inferring net metabolic modification of seawater by coral reefs. Salinity (S), TA, and DIC can be accurately and precisely measured, but salinity normalization of TA (nTA) and DIC (nDIC) can generate considerable and unrecognized uncertainties in coral reef metabolic rate estimates. While salinity normalization errors apply to nTA, nDIC, and other ions of interest in coral reefs, here, we focus on nTA due to its application as a proxy for net coral reef calcification and the importance for reefs to maintain calcium carbonate production under environmental change. We used global datasets of coral reef TA, S, and modeled groundwater discharge to assess the effect of different volumetric ratios of multiple freshwater TA inputs (i.e., groundwater, river, surface runoff, and precipitation) on nTA. Coral reef freshwater endmember TA ranged from -2 up to 3032 μmol/kg in hypothetical reef locations with freshwater inputs dominated by riverine, surface runoff, or precipitation mixing with groundwater. The upper bound of freshwater TA in these scenarios can result in an uncertainty in reef TA of up to 90 μmol/kg per unit S normalization if the freshwater endmember is erroneously assumed to have 0 μmol/kg alkalinity. The uncertainty associated with S normalization can, under some circumstances, even shift the interpretation of whether reefs are net calcifying to net dissolving, or vice versa. Moreover, the choice of reference salinity for normalization implicitly makes assumptions about whether biogeochemical processes occur before or after mixing between different water masses, which can add uncertainties of ±1.4% nTA per unit S normalization. Additional considerations in identifying potential freshwater sources of TA and their relative volumetric impact on seawater are required to reduce uncertainties associated with S normalization of coral reef carbonate chemistry data in some environments. However, at a minimum, researchers should minimize the range of salinities over which the normalization is applied, precisely measure salinity, and normalize TA values to a carefully selected reference salinity that takes local factors into account.

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Inorganic carbon fluxes on the Mackenzie Shelf of the Beaufort Sea

10.5194/bg-2017-318 ◽

2017 ◽

Author(s):

Jacoba Mol ◽

Helmuth Thomas ◽

Paul G. Myers ◽

Xianmin Hu ◽

Alfonso Mucci

Keyword(s):

Sea Ice ◽

Inorganic Carbon ◽

Dissolved Inorganic Carbon ◽

Beaufort Sea ◽

Total Alkalinity ◽

The Arctic ◽

Surface Mixed Layer ◽

Saturation State ◽

Carbon Transfer ◽

Mackenzie Shelf

Abstract. The Mackenzie Shelf in the southeastern Beaufort Sea is a region that has experienced large changes in the past several decades as warming, sea-ice loss, and increased river discharge have altered carbon cycling. Upwelling and downwelling events are common on the shelf, caused by strong, fluctuating along-shore winds, resulting in cross-shelf Ekman transport, and an alternating estuarine and anti-estuarine circulation. Downwelling carries inorganic carbon and other remineralization products off the shelf and into the deep basin for possible long-term storage in the world oceans. Upwelling carries dissolved inorganic carbon (DIC) and nutrient-rich waters from the Pacific-origin upper halocline layer (UHL) onto the shelf. Profiles of DIC and total alkalinity (TA) taken in August and September of 2014 are used to investigate the cycling of inorganic carbon on the Mackenzie Shelf. The along-shore transport of water and the cross-shelf transport of inorganic carbon are quantified using velocity field output from a simulation of the Arctic and Northern Hemisphere Atlantic (ANHA4) configuration of the Nucleus of European Modelling of the Ocean (NEMO) framework. A strong upwelling event prior to sampling on the Mackenzie Shelf is analyzed and the resulting influence on the carbonate system, including the saturation state of waters with respect to aragonite and pH, is investigated. TA and the oxygen isotope ratio of water (δ18O) are used to examine water-mass distributions in the study area and to investigate the influence of Pacific Water, Mackenzie River freshwater, and sea-ice melt on carbon dynamics and air-sea fluxes of carbon dioxide (CO2) in the surface mixed layer. Understanding carbon transfer in this seasonally dynamic environment is key to quantify the importance of Arctic shelf regions to the global carbon cycle and provide a basis for understanding how it will respond to the aforementioned climate-induced changes.

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Ocean acidification from 1997 to 2011 in the subarctic western North Pacific Ocean

Biogeosciences Discussions ◽

10.5194/bgd-10-8283-2013 ◽

2013 ◽

Vol 10 (5) ◽

pp. 8283-8311 ◽

Cited By ~ 1

Author(s):

M. Wakita ◽

S. Watanabe ◽

M. Honda ◽

A. Nagano ◽

K. Kimoto ◽

...

Keyword(s):

Ocean Acidification ◽

Mixed Layer ◽

North Pacific ◽

Dissolved Inorganic Carbon ◽

North Pacific Ocean ◽

Total Alkalinity ◽

Co2 Uptake ◽

The North ◽

Western Subarctic Gyre ◽

Calcite Saturation

Abstract. Rising atmospheric CO2 contents have led to greater CO2 uptake by the oceans, lowering both pH due to increasing hydrogen ions and CaCO3 saturation states due to declining carbonate ion (CO32−). Here, we used previously compiled data sets and new data collected in 2010 and 2011 to investigate ocean acidification of the North Pacific western subarctic gyre. In winter, the western subarctic gyre is a source of CO2 to the atmosphere because of convective mixing of deep waters rich in dissolved inorganic carbon (DIC). We calculated pH in winter mixed layer from DIC and total alkalinity (TA), and found that it decreased at the rate of −0.001 ± 0.0004 yr−1 from 1997 to 2011. This decrease rate is slower than that expected under condition of seawater/atmosphere equilibration, and it is also slower than the rate in the subtropical regions (−0.002 yr−1). The slow rate is caused by a reduction of CO2 emission in winter due to an increase in TA. Below the mixed layer, the calcite saturation horizon (~185 m depth) shoaled at the rate of 2.9 ± 0.9 m yr−1 as the result of the declining CO32− concentration (−0.03 ± 0.01 μmol k−1yr−1). Between 200 m and 300 m depth, pH decline during the study period (−0.0051 ± 0.0010 yr−1) was larger than ever reported in the open North Pacific. This enhanced acidification rate below the calcite saturation horizon reflected not only the uptake of anthropogenic CO2 but also the increase in the decomposition of organic matter evaluated from the increase in AOU, which suggests that the dissolution of CaCO3 particles increased.

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