Accurate pH and O2 measurements from Spray underwater gliders

AbstractThe California Current System is thought to be particularly vulnerable to ocean acidification, yet pH remains chronically undersampled along this coast, limiting our ability to assess the impacts of ocean acidification. To address this observational gap, we integrated the Deep-Sea-DuraFET, a solid state pH sensor onto a Spray underwater glider. Over the course of a year starting in April 2019, we conducted 7 missions in Central California, which spanned 161 glider days and >1600 dives to a maximum depth of 1000 m. The sensor accuracy was estimated to be ± 0.01 based on comparisons to discrete samples taken alongside the glider (n=105), and the precision was ± 0.0016. CO2 partial pressure, dissolved inorganic carbon, and aragonite saturation state could be estimated from the pH data with uncertainty better than ± 2.5%, ± 8 μmol kg-1, and ± 2%, respectively. The sensor was stable to ± 0.01 for the first nine months, but exhibited a drift of 0.015 during the last mission. The drift was correctable using a piecewise linear regression based on a reference pH field at 450 m estimated from published global empirical algorithms. These algorithms require accurate O2 as inputs, thus, protocols for a simple pre-deployment air-calibration which achieved accuracy of better than 1 % were implemented. The glider observations revealed upwelling of undersaturated waters with respect to aragonite to within 5 m below the surface near Monterey Bay. These observations highlight the importance of persistent observations through autonomous platforms in highly dynamic coastal environments.

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Spatiotemporal variability and long-term trends of ocean acidification in the California Current System

Biogeosciences ◽

10.5194/bg-10-193-2013 ◽

2013 ◽

Vol 10 (1) ◽

pp. 193-216 ◽

Cited By ~ 98

Author(s):

C. Hauri ◽

N. Gruber ◽

M. Vogt ◽

S. C. Doney ◽

R. A. Feely ◽

...

Keyword(s):

Ocean Acidification ◽

Current System ◽

California Current ◽

Spatiotemporal Variability ◽

The Arctic ◽

Saturation State ◽

Aragonite Saturation ◽

Large Variability ◽

California Current System ◽

Ipcc Sres

Abstract. Due to seasonal upwelling, the upper ocean waters of the California Current System (CCS) have a naturally low pH and aragonite saturation state (Ωarag), making this region particularly prone to the effects of ocean acidification. Here, we use the Regional Oceanic Modeling System (ROMS) to conduct preindustrial and transient (1995–2050) simulations of ocean biogeochemistry in the CCS. The transient simulations were forced with increasing atmospheric pCO2 and increasing oceanic dissolved inorganic carbon concentrations at the lateral boundaries, as projected by the NCAR CSM 1.4 model for the IPCC SRES A2 scenario. Our results show a large seasonal variability in pH (range of ~ 0.14) and Ωarag (~ 0.2) for the nearshore areas (50 km from shore). This variability is created by the interplay of physical and biogeochemical processes. Despite this large variability, we find that present-day pH and Ωarag have already moved outside of their simulated preindustrial variability envelopes (defined by ±1 temporal standard deviation) due to the rapidly increasing concentrations of atmospheric CO2. The nearshore surface pH of the northern and central CCS are simulated to move outside of their present-day variability envelopes by the mid-2040s and late 2030s, respectively. This transition may occur even earlier for nearshore surface Ωarag, which is projected to depart from its present-day variability envelope by the early- to mid-2030s. The aragonite saturation horizon of the central CCS is projected to shoal into the upper 75 m within the next 25 yr, causing near-permanent undersaturation in subsurface waters. Due to the model's overestimation of Ωarag, this transition may occur even earlier than simulated by the model. Overall, our study shows that the CCS joins the Arctic and Southern oceans as one of only a few known ocean regions presently approaching the dual threshold of widespread and near-permanent undersaturation with respect to aragonite and a departure from its variability envelope. In these regions, organisms may be forced to rapidly adjust to conditions that are both inherently chemically challenging and also substantially different from past conditions.

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Including high-frequency variability in coastal ocean acidification projections

Biogeosciences ◽

10.5194/bg-12-5853-2015 ◽

2015 ◽

Vol 12 (19) ◽

pp. 5853-5870 ◽

Cited By ~ 42

Author(s):

Y. Takeshita ◽

C. A. Frieder ◽

T. R. Martz ◽

J. R. Ballard ◽

R. A. Feely ◽

...

Keyword(s):

Time Series ◽

Ocean Acidification ◽

Surf Zone ◽

Current System ◽

Sensor Data ◽

High Temporal Resolution ◽

Saturation State ◽

Study Region ◽

California Current System ◽

Anthropogenic Carbon

Abstract. Assessing the impacts of anthropogenic ocean acidification requires knowledge of present-day and future environmental conditions. Here, we present a simple model for upwelling margins that projects anthropogenic acidification trajectories by combining high-temporal-resolution sensor data, hydrographic surveys for source water characterization, empirical relationships of the CO2 system, and the atmospheric CO2 record. This model characterizes CO2 variability on timescales ranging from hours (e.g., tidal) to months (e.g., seasonal), bridging a critical knowledge gap in ocean acidification research. The amount of anthropogenic carbon in a given water mass is dependent on the age; therefore a density–age relationship was derived for the study region and then combined with the 2013 Intergovernmental Panel on Climate Change CO2 emission scenarios to add density-dependent anthropogenic carbon to the sensor time series. The model was applied to time series from autonomous pH sensors deployed in the surf zone, kelp forest, submarine canyon edge, and shelf break in the upper 100 m of the Southern California Bight. All habitats were within 5 km of one another, and exhibited unique, habitat-specific CO2 variability signatures and acidification trajectories, demonstrating the importance of making projections in the context of habitat-specific CO2 signatures. In general, both the mean and range of pCO2 increase in the future, with the greatest increase in both magnitude and range occurring in the deeper habitats due to reduced buffering capacity. On the other hand, the saturation state of aragonite (ΩAr) decreased in both magnitude and range. This approach can be applied to the entire California Current System, and upwelling margins in general, where sensor and complementary hydrographic data are available.

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Spatiotemporal variability and long-term trends of ocean acidification in the California Current System

Biogeosciences Discussions ◽

10.5194/bgd-9-10371-2012 ◽

2012 ◽

Vol 9 (8) ◽

pp. 10371-10428 ◽

Cited By ~ 9

Author(s):

C. Hauri ◽

N. Gruber ◽

M. Vogt ◽

S. C. Doney ◽

R. A. Feely ◽

...

Keyword(s):

Ocean Acidification ◽

Current System ◽

California Current ◽

Spatiotemporal Variability ◽

The Arctic ◽

Saturation State ◽

Aragonite Saturation ◽

Large Variability ◽

California Current System ◽

Ipcc Sres

Abstract. Due to seasonal upwelling, the upper ocean waters of the California Current System (CCS) have a naturally low pH and aragonite saturation state (Ωarag), making this region particularly prone to the effects of ocean acidification. Here, we use the Regional Oceanic Modeling System (ROMS) to conduct preindustrial and transient (1995–2050) simulations of ocean biogeochemistry in the CCS. The transient simulations were forced with increasing atmospheric pCO2 as projected by the NCAR CSM 1.4 model run under either the IPCC SRES A2 or B1 scenarios. Using ROMS, we investigate the timing of transition decades during which pH and Ωarag depart from their modeled preindustrial (1750) and present-day (2011) variability envelopes. We report these transition decades by noting the midpoint of the ten-year transition periods. In addition, we also analyze the timing of near permanent aragonite undersaturation in the upper 100 m of the water column. Our results show that an interplay of physical and biogeochemical processes create large seasonal variability in pH (∼ 0.14) and Ωarag (∼ 0.2). Despite this large variability, we find that present-day pH and Ωarag have already moved out of their preindustrial variability envelopes due to the rapidly increasing concentrations of atmospheric CO2. The simulations following the A2 emissions scenario suggest that nearshore surface pH of the northern and central CCS will move out of their present-day variability envelopes by 2045 and 2037, respectively. However, surface Ωarag of the northern and central CCS subregions are projected to depart from their present-day variability envelopes sooner, by 2030 and 2035, respectively. By 2025, the aragonite saturation horizon of the central CCS is projected to shoal into the upper 75 m for the duration of the annual cycle, causing near permanent undersaturation in subsurface waters. Overall, our study shows that the CCS joins the Arctic and Southern Oceans as one of only a few known ocean regions presently approaching this dual threshold of undersaturation with respect to aragonite and a departure from its variability envelope. In these regions, organisms may be forced to rapidly adjust to conditions that are both inherently chemically challenging and also substantially different from prior conditions.

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Including high frequency variability in coastal ocean acidification projections

Biogeosciences Discussions ◽

10.5194/bgd-12-7125-2015 ◽

2015 ◽

Vol 12 (9) ◽

pp. 7125-7176 ◽

Cited By ~ 4

Author(s):

Y. Takeshita ◽

C. A. Frieder ◽

T. R. Martz ◽

J. R. Ballard ◽

R. A. Feely ◽

...

Keyword(s):

Time Series ◽

Ocean Acidification ◽

Surf Zone ◽

Current System ◽

Sensor Data ◽

High Temporal Resolution ◽

Saturation State ◽

Study Region ◽

California Current System ◽

Anthropogenic Carbon

Abstract. Assessing the impacts of anthropogenic ocean acidification requires knowledge of present-day and future environmental conditions. Here, we present a simple model for upwelling margins that projects anthropogenic acidification trajectories by combining high-temporal resolution sensor data, hydrographic surveys for source water characterization, empirical relationships of the CO2 system, and the atmospheric CO2 record. This model characterizes CO2 variability on timescales ranging from hours (e.g. tidal) to months (e.g. seasonal), bridging a critical knowledge gap in ocean acidification research. The amount of anthropogenic carbon in a given water mass is dependent on the age, therefore a density–age relationship was derived for the study region, and was combined with the 2013 Intergovernmental Panel on Climate Change CO2 emission scenarios to add density-dependent anthropogenic carbon to the sensor time series. The model was applied to time series from four autonomous pH sensors, each deployed in the surf zone, kelp forest, submarine canyon edge, and shelf break in the upper 100 m of the Southern California Bight. All habitats were within 5 km of one another, and exhibited unique, habitat-specific CO2 variability signatures and acidification trajectories, demonstrating the importance of making projections in the context of habitat-specific CO2 signatures. In general, both the mean and range of pCO2 increase in the future, with the greatest increases in both magnitude and range occurring in the deeper habitats due to reduced buffering capacity. On the other hand, the saturation state of aragonite (ΩAr) decreased in both magnitude and range. This approach can be applied to the entire California Current System, and upwelling margins in general, where sensor and complementary hydrographic data are available.

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Faculty Opinions recommendation of Rapid progression of ocean acidification in the California Current System.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.717953148.793458716 ◽

2012 ◽

Author(s):

Russell Moll

Keyword(s):

Ocean Acidification ◽

Current System ◽

California Current ◽

Rapid Progression ◽

California Current System

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Persistent spatial structuring of coastal ocean acidification in the California Current System

Scientific Reports ◽

10.1038/s41598-017-02777-y ◽

2017 ◽

Vol 7 (1) ◽

Cited By ~ 64

Author(s):

F. Chan ◽

J. A. Barth ◽

C. A. Blanchette ◽

R. H. Byrne ◽

F. Chavez ◽

...

Keyword(s):

Ocean Acidification ◽

Current System ◽

California Current ◽

Coastal Ocean ◽

California Current System ◽

Spatial Structuring

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Quantifying the influence of CO<sub>2</sub> seasonality on future ocean acidification

Biogeosciences Discussions ◽

10.5194/bgd-12-5907-2015 ◽

2015 ◽

Vol 12 (8) ◽

pp. 5907-5940

Author(s):

T. P. Sasse ◽

B. I. McNeil ◽

R. J. Matear ◽

A. Lenton

Keyword(s):

Ocean Acidification ◽

North Pacific ◽

Dissolved Inorganic Carbon ◽

Marine Ecosystem ◽

Global Ocean ◽

Saturation State ◽

The North ◽

Data Limitations ◽

The Future ◽

The North Pacific

Abstract. Ocean acidification is a predictable consequence of rising atmospheric carbon dioxide (CO2), and is highly likely to impact the entire marine ecosystem – from plankton at the base to fish at the top. Factors which are expected to be impacted include reproductive health, organism growth and species composition and distribution. Predicting when critical threshold values will be reached is crucial for projecting the future health of marine ecosystems and for marine resources planning and management. The impacts of ocean acidification will be first felt at the seasonal scale, however our understanding how seasonal variability will influence rates of future ocean acidification remains poorly constrained due to current model and data limitations. To address this issue, we first quantified the seasonal cycle of aragonite saturation state utilizing new data-based estimates of global ocean surface dissolved inorganic carbon and alkalinity. This seasonality was then combined with earth system model projections under different emissions scenarios (RCPs 2.6, 4.5 and 8.5) to provide new insights into future aragonite under-saturation onset. Under a high emissions scenario (RCP 8.5), our results suggest accounting for seasonality will bring forward the initial onset of month-long under-saturation by 17 years compared to annual-mean estimates, with differences extending up to 35 ± 17 years in the North Pacific due to strong regional seasonality. Our results also show large-scale under-saturation once atmospheric CO2 reaches 486 ppm in the North Pacific and 511 ppm in the Southern Ocean independent of emission scenario. Our results suggest that accounting for seasonality is critical to projecting the future impacts of ocean acidification on the marine environment.

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Ocean acidification as a multiple driver: how interactions between changing seawater carbonate parameters affect marine life

Marine and Freshwater Research ◽

10.1071/mf19267 ◽

2020 ◽

Vol 71 (3) ◽

pp. 263 ◽

Cited By ~ 8

Author(s):

Catriona L. Hurd ◽

John Beardall ◽

Steeve Comeau ◽

Christopher E. Cornwall ◽

Jonathan N Havenhand ◽

...

Keyword(s):

Ocean Acidification ◽

Inorganic Carbon ◽

Dissolved Inorganic Carbon ◽

Multiple Stressors ◽

Rapid Expansion ◽

Coralline Algae ◽

Carbonate System ◽

Saturation State ◽

Marine Life ◽

Key Terms

‘Multiple drivers’ (also termed ‘multiple stressors’) is the term used to describe the cumulative effects of multiple environmental factors on organisms or ecosystems. Here, we consider ocean acidification as a multiple driver because many inorganic carbon parameters are changing simultaneously, including total dissolved inorganic carbon, CO2, HCO3–, CO32–, H+ and CaCO3 saturation state. With the rapid expansion of ocean acidification research has come a greater understanding of the complexity and intricacies of how these simultaneous changes to the seawater carbonate system are affecting marine life. We start by clarifying key terms used by chemists and biologists to describe the changing seawater inorganic carbon system. Then, using key groups of non-calcifying (fish, seaweeds, diatoms) and calcifying (coralline algae, coccolithophores, corals, molluscs) organisms, we consider how various physiological processes are affected by different components of the carbonate system.

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A regional hindcast model simulating ecosystem dynamics, inorganic carbon chemistry, and ocean acidification in the Gulf of Alaska

Biogeosciences ◽

10.5194/bg-17-3837-2020 ◽

2020 ◽

Vol 17 (14) ◽

pp. 3837-3857

Author(s):

Claudine Hauri ◽

Cristina Schultz ◽

Katherine Hedstrom ◽

Seth Danielson ◽

Brita Irving ◽

...

Keyword(s):

Ocean Acidification ◽

Seasonal Cycle ◽

Bottom Water ◽

Inorganic Carbon ◽

Dissolved Inorganic Carbon ◽

Gulf Of Alaska ◽

Saturation State ◽

Aragonite Saturation ◽

Carbon Chemistry ◽

Seward Line

Abstract. The coastal ecosystem of the Gulf of Alaska (GOA) is especially vulnerable to the effects of ocean acidification and climate change. Detection of these long-term trends requires a good understanding of the system’s natural state. The GOA is a highly dynamic system that exhibits large inorganic carbon variability on subseasonal to interannual timescales. This variability is poorly understood due to the lack of observations in this expansive and remote region. We developed a new model setup for the GOA that couples the three-dimensional Regional Oceanic Model System (ROMS) and the Carbon, Ocean Biogeochemistry and Lower Trophic (COBALT) ecosystem model. To improve our conceptual understanding of the system, we conducted a hindcast simulation from 1980 to 2013. The model was explicitly forced with temporally and spatially varying coastal freshwater discharges from a high-resolution terrestrial hydrological model, thereby affecting salinity, alkalinity, dissolved inorganic carbon, and nutrient concentrations. This represents a substantial improvement over previous GOA modeling attempts. Here, we evaluate the model on seasonal to interannual timescales using the best available inorganic carbon observations. The model was particularly successful in reproducing observed aragonite oversaturation and undersaturation of near-bottom water in May and September, respectively. The largest deficiency in the model is its inability to adequately simulate springtime surface inorganic carbon chemistry, as it overestimates surface dissolved inorganic carbon, which translates into an underestimation of the surface aragonite saturation state at this time. We also use the model to describe the seasonal cycle and drivers of inorganic carbon parameters along the Seward Line transect in under-sampled months. Model output suggests that the majority of the near-bottom water along the Seward Line is seasonally undersaturated with respect to aragonite between June and January, as a result of upwelling and remineralization. Such an extensive period of reoccurring aragonite undersaturation may be harmful to ocean acidification-sensitive organisms. Furthermore, the influence of freshwater not only decreases the aragonite saturation state in coastal surface waters in summer and fall, but it simultaneously decreases the surface partial pressure of carbon dioxide (pCO2), thereby decoupling the aragonite saturation state from pCO2. The full seasonal cycle and geographic extent of the GOA region is under-sampled, and our model results give new and important insights for months of the year and areas that lack in situ inorganic carbon observations.

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