Responses of coral gastrovascular cavity pH during light and dark incubations to reduced seawater pH suggest species-specific responses to the effects of ocean acidification on calcification

Variability in metabolic scaling in animals, the relationship between metabolic rate ( R ) and body mass ( M ), has been a source of debate and controversy for decades. R is proportional to M b , the precise value of b much debated, but historically considered equal in all organisms. Recent metabolic theory, however, predicts b to vary among species with ecology and metabolic level, and may also vary within species under different abiotic conditions. Under climate change, most species will experience increased temperatures, and marine organisms will experience the additional stressor of decreased seawater pH (‘ocean acidification’). Responses to these environmental changes are modulated by myriad species-specific factors. Body-size is a fundamental biological parameter, but its modulating role is relatively unexplored. Here, we show that changes to metabolic scaling reveal asymmetric responses to stressors across body-size ranges; b is systematically decreased under increasing temperature in three grazing molluscs, indicating smaller individuals were more responsive to warming. Larger individuals were, however, more responsive to reduced seawater pH in low temperatures. These alterations to the allometry of metabolism highlight abiotic control of metabolic scaling, and indicate that responses to climate warming and ocean acidification may be modulated by body-size.

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Does ocean acidification induce an upward flux of marine aggregates?

Biogeosciences ◽

10.5194/bg-5-1023-2008 ◽

2008 ◽

Vol 5 (4) ◽

pp. 1023-1031 ◽

Cited By ~ 51

Author(s):

X. Mari

Keyword(s):

Ocean Acidification ◽

Atmospheric Carbon Dioxide ◽

New Caledonia ◽

Seawater Acidification ◽

Seawater Ph ◽

Biogenic Carbon ◽

Marine Aggregates ◽

Atmospheric Carbon ◽

Carbon Dioxide Co2 ◽

Sedimentation Processes

Abstract. The absorption of anthropogenic atmospheric carbon dioxide (CO2) by the ocean provokes its acidification. This acidification may alter several oceanic processes, including the export of biogenic carbon from the upper layer of the ocean, hence providing a feedback on rising atmospheric carbon concentrations. The effect of seawater acidification on transparent exopolymeric particles (TEP) driven aggregation and sedimentation processes were investigated by studying the interactions between latex beads and TEP precursors collected in the lagoon of New Caledonia. A suspension of TEP and beads was prepared and the formation of mixed aggregates was monitored as a function of pH under increasing turbulence intensities. The pH was controlled by addition of sulfuric acid. Aggregation and sedimentation processes driven by TEP were drastically reduced when the pH of seawater decreases within the expected limits imposed by increased anthropogenic CO2 emissions. In addition to the diminution of TEP sticking properties, the diminution of seawater pH led to a significant increase of the TEP pool, most likely due to swollen structures. A diminution of seawater pH by 0.2 units or more led to a stop or a reversal of the downward flux of particles. If applicable to oceanic conditions, the sedimentation of marine aggregates may slow down or even stop as the pH decreases, and the vertical flux of organic carbon may reverse. This would enhance both rising atmospheric carbon and ocean acidification.

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Ocean alkalinity enhancement as a tool to mitigate ocean acidification and facilitate CO2 uptake from the atmosphere

10.5194/egusphere-egu21-2264 ◽

2021 ◽

Author(s):

Jakob Rønning ◽

Carolin Löscher

Keyword(s):

Ocean Acidification ◽

Total Alkalinity ◽

Small Scale ◽

Marine Biodiversity ◽

Steady Increase ◽

Co2 Uptake ◽

Seawater Ph ◽

Mineral Additions ◽

Primary Producer ◽

Negative Emission Technologies

Anthropogenic global warming over the last century has led to a steady increase of CO2 in the atmosphere. One of the consequences of increasing CO2 concentrations is ocean acidification, a phenomenon problematic to marine biodiversity and biogeochemistry. The ocean reservoir takes up 25% of CO2 from the atmosphere both chemically and biologically. This potential can be made use of to promote CO2 uptake from the atmosphere while mitigating ocean acidification and protecting biodiversity using negative emission technologies associated with the ocean. We have investigated the potential of various alkaline minerals to stabilize seawater pH overtime on a small scale. Those alkaline minerals were predicted to be appropriate for ocean alkalinity enhancement and can offer a toolset to mitigate CO2 from the atmosphere. Specifically, we have examined how chalk, calcite, dolomite, limestone, and olivine affects seawater pH and total alkalinity (TA) on timescales of several months. Thereby, we could identify two promising minerals, dolomite and olivine, and develop a strategy for mineral additions to buffer the seawater pH. Importantly, the often proposed had an unexpected opposite impact and massively lowered the seawater pH over a timescale of 100 days. The identified advantageous minerals will inform our experiments on primary producer cultures and natural consortia.

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Progressive seawater acidification on the Great Barrier Reef continental shelf

Scientific Reports ◽

10.1038/s41598-020-75293-1 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Katharina E. Fabricius ◽

Craig Neill ◽

Erik Van Ooijen ◽

Joy N. Smith ◽

Bronte Tilbrook

Keyword(s):

Coral Reefs ◽

Continental Shelf ◽

Great Barrier Reef ◽

Ocean Acidification ◽

Seawater Temperature ◽

Barrier Reef ◽

Saturation State ◽

Seawater Acidification ◽

Seawater Ph ◽

Seawater Samples

Abstract Coral reefs are highly sensitive to ocean acidification due to rising atmospheric CO2 concentrations. We present 10 years of data (2009–2019) on the long-term trends and sources of variation in the carbon chemistry from two fixed stations in the Australian Great Barrier Reef. Data from the subtropical mid-shelf GBRWIS comprised 3-h instrument records, and those from the tropical coastal NRSYON were monthly seawater samples. Both stations recorded significant variation in seawater CO2 fugacity (fCO2), attributable to seasonal, daytime, temperature and salinity fluctuations. Superimposed over this variation, fCO2 progressively increased by > 2.0 ± 0.3 µatm year−1 at both stations. Seawater temperature and salinity also increased throughout the decade, whereas seawater pH and the saturation state of aragonite declined. The decadal upward fCO2 trend remained significant in temperature- and salinity-normalised data. Indeed, annual fCO2 minima are now higher than estimated fCO2 maxima in the early 1960s, with mean fCO2 now ~ 28% higher than 60 years ago. Our data indicate that carbonate dissolution from the seafloor is currently unable to buffer the Great Barrier Reef against ocean acidification. This is of great concern for the thousands of coral reefs and other diverse marine ecosystems located in this vast continental shelf system.

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Ocean acidification disrupts the orientation of postlarval Caribbean spiny lobsters

Scientific Reports ◽

10.1038/s41598-020-75021-9 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Philip M. Gravinese ◽

Heather N. Page ◽

Casey B. Butler ◽

Angelo Jason Spadaro ◽

Clay Hewett ◽

...

Keyword(s):

Ocean Acidification ◽

Time Scales ◽

Coastal Waters ◽

Chemical Cues ◽

Spiny Lobster ◽

Episodic Acidification ◽

Anthropogenic Inputs ◽

Seawater Ph ◽

Y Maze ◽

The Caribbean

Abstract Anthropogenic inputs into coastal ecosystems are causing more frequent environmental fluctuations and reducing seawater pH. One such ecosystem is Florida Bay, an important nursery for the Caribbean spiny lobster, Panulirus argus. Although adult crustaceans are often resilient to reduced seawater pH, earlier ontogenetic stages can be physiologically limited in their tolerance to ocean acidification on shorter time scales. We used a Y-maze chamber to test whether reduced-pH seawater altered the orientation of spiny lobster pueruli toward chemical cues produced by Laurencia spp. macroalgae, a known settlement cue for the species. We tested the hypothesis that pueruli conditioned in reduced-pH seawater would be less responsive to Laurencia spp. chemical cues than pueruli in ambient-pH seawater by comparing the proportion of individuals that moved to the cue side of the chamber with the proportion that moved to the side with no cue. We also recorded the amount of time (sec) before a response was observed. Pueruli conditioned in reduced-pH seawater were less responsive and failed to select the Laurencia cue. Our results suggest that episodic acidification of coastal waters might limit the ability of pueruli to locate settlement habitats, increasing postsettlement mortality.

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Near-shore Antarctic pH variability has implications for the design of oceanacidification experiments

Scientific Reports ◽

10.1038/srep09638 ◽

2015 ◽

Vol 5 (1) ◽

Cited By ~ 41

Author(s):

Lydia Kapsenberg ◽

Amanda L. Kelley ◽

Emily C. Shaw ◽

Todd R. Martz ◽

Gretchen E. Hofmann

Keyword(s):

Time Series ◽

Ocean Acidification ◽

Marine Species ◽

Physiological Data ◽

Ph Change ◽

Physiological Tolerance ◽

Seawater Ph ◽

Near Shore ◽

Ecosystem Changes

Abstract Understanding how declining seawater pH caused by anthropogenic carbon emissions, or oceanacidification, impacts Southern Ocean biota is limited by a paucity of pH time-series. Here,we present the first high-frequency in-situ pH time-series in near-shore Antarctica fromspring to winter under annual sea ice. Observations from autonomous pH sensors revealed aseasonal increase of 0.3 pH units. The summer season was marked by an increase in temporalpH variability relative to spring and early winter, matching coastal pH variability observedat lower latitudes. Using our data, simulations of ocean acidification show a future periodof deleterious wintertime pH levels potentially expanding to 7–11 months annually by 2100.Given the presence of (sub)seasonal pH variability, Antarctica marine species have anexisting physiological tolerance of temporal pH change that may influence adaptation tofuture acidification. Yet, pH-induced ecosystem changes remain difficult to characterize inthe absence of sufficient physiological data on present-day tolerances. It is thereforeessential to incorporate natural and projected temporal pH variability in the design ofexperiments intended to study ocean acidification biology.

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Is Ocean Acidification an Open-Ocean Syndrome? Understanding Anthropogenic Impacts on Seawater pH

Estuaries and Coasts ◽

10.1007/s12237-013-9594-3 ◽

2013 ◽

Vol 36 (2) ◽

pp. 221-236 ◽

Cited By ~ 371

Author(s):

Carlos M. Duarte ◽

Iris E. Hendriks ◽

Tommy S. Moore ◽

Ylva S. Olsen ◽

Alexandra Steckbauer ◽

...

Keyword(s):

Ocean Acidification ◽

Anthropogenic Impacts ◽

Open Ocean ◽

Seawater Ph

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Response of Acropora digitifera to ocean acidification: constraints from δ11B, Sr, Mg, and Ba compositions of aragonitic skeletons cultured under variable seawater pH

Coral Reefs ◽

10.1007/s00338-015-1319-6 ◽

2015 ◽

Vol 34 (4) ◽

pp. 1139-1149 ◽

Cited By ~ 22

Author(s):

Kentaro Tanaka ◽

Michael Holcomb ◽

Asami Takahashi ◽

Haruko Kurihara ◽

Ryuji Asami ◽

...

Keyword(s):

Ocean Acidification ◽

Acropora Digitifera ◽

Seawater Ph

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Decrease in volume and density of foraminiferal shells with progressing ocean acidification

Scientific Reports ◽

10.1038/s41598-021-99427-1 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Azumi Kuroyanagi ◽

Takahiro Irie ◽

Shunichi Kinoshita ◽

Hodaka Kawahata ◽

Atsushi Suzuki ◽

...

Keyword(s):

Partial Pressure ◽

Ocean Acidification ◽

Benthic Foraminifera ◽

Growth Parameters ◽

Carbonate Production ◽

Large Benthic Foraminifera ◽

Seawater Ph ◽

Ph Conditions ◽

Calcification Process ◽

The Tropics

AbstractRapid increases in anthropogenic atmospheric CO2 partial pressure have led to a decrease in the pH of seawater. Calcifying organisms generally respond negatively to ocean acidification. Foraminifera are one of the major carbonate producers in the ocean; however, whether calcification reduction by ocean acidification affects either foraminiferal shell volume or density, or both, has yet to be investigated. In this study, we cultured asexually reproducing specimens of Amphisorus kudakajimensis, a dinoflagellate endosymbiont-bearing large benthic foraminifera (LBF), under different pH conditions (pH 7.7–8.3, NBS scale). The results suggest that changes in seawater pH would affect not only the quantity (i.e., shell volume) but also the quality (i.e., shell density) of foraminiferal calcification. We proposed that pH and temperature affect these growth parameters differently because (1) they have differences in the contribution to the calcification process (e.g., Ca2+-ATPase and Ω) and (2) pH mainly affects calcification and temperature mainly affects photosynthesis. Our findings also suggest that, under the IPCC RCP8.5 scenario, both ocean acidification and warming will have a significant impact on reef foraminiferal carbonate production by the end of this century, even in the tropics.

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Dichotomy between regulation of coral bacterial communities and calcification physiology under ocean acidification conditions

Applied and Environmental Microbiology ◽

10.1128/aem.02189-20 ◽

2021 ◽

Author(s):

A. Shore ◽

R. D. Day ◽

J. A. Stewart ◽

C.A. Burge

Keyword(s):

Ocean Acidification ◽

Bacterial Communities ◽

16S Rrna Gene Sequencing ◽

Ph Gradient ◽

Rrna Gene ◽

Seawater Ph ◽

Coral Health ◽

And Function ◽

The Impact

Ocean acidification (OA) threatens the growth and function of coral reef ecosystems. A key component to coral health is the microbiome, but little is known about the impact of OA on coral microbiomes. A submarine CO2 vent at Maug Island in the Northern Marianas Islands provides a natural pH gradient to investigate coral responses to long-term OA conditions. Three coral species (Pocillopora eydouxi, Porites lobata, and Porites rus) were sampled from three sites where mean seawater pH is 8.04, 7.98, and 7.94. We characterized coral bacterial communities (using 16S rRNA gene sequencing) and determined pH of the extracellular calcifying fluid (ECF) (using skeletal boron isotopes) across the seawater pH gradient. Bacterial communities of both Porites species stabilized (decreases in community dispersion) with decreased seawater pH, coupled with large increases in the abundance of Endozoicomonas, an endosymbiont. P. lobata experienced a significant decrease in ECF pH near the vent, whereas P. rus experienced a trending decrease in ECF pH near the vent. By contrast, Pocillopora exhibited bacterial community destabilization (increases in community dispersion), with significant decreases in Endozoicomonas abundance, while its ECF pH remained unchanged across the pH gradient. Our study shows that OA has multiple consequences on Endozoicomonas abundance and suggests that Endozoicomonas abundance may be an indicator of coral response to OA. We reveal an interesting dichotomy between two facets of coral physiology (regulation of bacterial communities and regulation of calcification), highlighting the importance of multidisciplinary approaches to understanding coral health and function in a changing ocean. IMPORTANCE Ocean acidification (OA) is a consequence of anthropogenic CO2 emissions that is negatively impacting marine ecosystems such as coral reefs. OA affects many aspects of coral physiology, including growth (i.e. calcification) and disrupting associated bacterial communities. Coral-associated bacteria are important for host health, but it remains unclear how coral-associated bacterial communities will respond to future OA conditions. We document changes in coral-associated bacterial communities and changes to calcification physiology with long-term exposure to decreases in seawater pH that are environmentally relevant under mid-range IPCC emission scenarios (0.1 pH units). We also find species-specific responses that may reflect different responses to long-term OA. In Pocillopora, calcification physiology was highly regulated despite changing seawater conditions. In Porites spp., changes in bacterial communities do not reflect a breakdown of coral-bacterial symbiosis. Insights into calcification and host-microbe interactions are critical to predicting the health and function of different coral taxa to future OA conditions.

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