The increase in anthropogenic CO2 emissions has induced significant physical and biogeochemical alterations in oceans worldwide, including warming, acidification, and oxygen depletion. Coastal areas are particularly vulnerable due to intensified human activities and terrestrial influences, resulting in increased coastal ocean acidification driven by atmospheric CO2 absorption and regional biological and anthropogenic processes. However, research on the collective impact of land-sea interaction and air-sea CO2 exchange on coastal ocean acidification in severely disturbed areas, such as the small islands of Lombok and Pari in Indonesia, remains limited. This study aims to investigate the daily fluctuations in marine carbonate systems and aragonite saturation (Ωarag) levels in the vicinity of seagrass and coral reef habitats in Pari Island and Sire Bay, Lombok. Seawater samples were collected from Sire Bay, Lombok, and the coastal waters of Pari Island to analyze the carbonate systems, CO₂ flux, and metabolic processes. The findings indicate that Pari Island’s coastal waters are more susceptible to ocean acidification than Sire Bay, Lombok, showing significantly lower pH values and Ωarag (P<0.05), ranging from 7.60 to 8.00 and 1.04 to 2.54, respectively. This disparity arises from the decreased temperature and salinity in Pari Island’s coastal waters during the northwest monsoon, coupled with the deteriorated state of the seagrass and coral reef ecosystems, altering the equilibrium of ecosystem productivity and calcification. The study underscores the necessity of adopting specific coastal management tactics to lessen the effects on fragile ecosystems, highlighting the urgency for additional studies to evaluate adaptive and conservation strategies to preserve coastal biodiversity and ecosystem services.
Continue reading ‘Variability of marine carbonate systems in seagrass and coral reef ecosystems of Pari and Lombok Islands, Indonesia’Archive Page 35
Variability of marine carbonate systems in seagrass and coral reef ecosystems of Pari and Lombok Islands, Indonesia
Published 2 July 2025 Science ClosedTags: chemistry, field, South Pacific
First study of seawater carbonate chemistry variability in a portion of the southern Atlantic coast of Cameroon: impact of organic pollution
Published 2 July 2025 Science ClosedTags: biogeochemistry, chemistry, field, North Atlantic
The carbonate system variability and acidification process remain little understood in the coastal ocean of Cameroon. The aim of this study was to assess the variability of the carbonate system in a portion of the southern coast of Cameroon, and the influence of local seawater physicochemical and biological properties on keys parameters of this system. The study was carried out at three fixed sampling stations (Bp, Kb, and Eb), from September 2021 to August 2022 involving all the seasons encountered in the study area. The carbonate system was determined from Total alkalinity (TA), pH, temperature and salinity, using the CO2SYS_xls program. In addition, nutrients (nitrate, nitrite, phosphate and nitrogen ammonia) and chlorophyll-a data were collected simultaneously at each station. The results showed a high variability of the carbonate system parameters on both temporal and spatial scale. TA and bicarbonate ions (HCO3− ) were significantly different between the large rainy season (LRS) and small rainy season (SRS), while CO2 and CO2 partial pressure (pCO2) were significantly different between Kb and Eb sampling stations (p-value < 0.05). The critical thresholds for ocean acidification (OA) seems to not been reached in the southern coastal ocean of Cameroon, given the means values of pH (8.14 ± 0.17), aragonite (3.31 ± 1.3 Ω) and calcite (5.3 ± 2.05 Ω) saturation states obtained. Salinity appears as the main driver of the variability of TA in the study area, while, nitrogen ammonia and the dissolved carbon dioxide from the degradation of organic matter, respiration and atmospheric absorption, appears as the drivers of pH variation. The large rainy season (LRS) seems to be the most critical period for OA sensitive organisms, while the Bp station looks most vulnerable.
Continue reading ‘First study of seawater carbonate chemistry variability in a portion of the southern Atlantic coast of Cameroon: impact of organic pollution’Effects of different environmental stressors on marine biogenic sulfur compounds in the Northwest Pacific and Eastern Indian Oceans
Published 2 July 2025 Science ClosedTags: abundance, biogeochemistry, biological response, community composition, growth, Indian, laboratory, multiple factors, North Pacific, otherprocess, physiology, phytoplankton
Abstract
Key roles of marine dimethyl sulfoniopropionate (DMSP), dimethyl sulfide (DMS), methyl mercaptan (MeSH), and carbon disulfide (CS2) in the sulfur cycle and/or atmospheric chemistry, alongside the rapid environmental changes in marine ecosystems, underscore the need to understand their responses to dynamic ecosystem shifts. We conducted two ship-based incubation experiments in the Northwest Pacific and Eastern Indian Oceans to explore how dust deposition, ocean acidification, and microplastic exposure impact these compounds. Our results demonstrate that these stressors not only alter phytoplankton community but also modify per-cell DMSP production capacity and DMSP degradation pathways, subsequently influencing DMSP, DMS, and MeSH concentrations. CS2‘s response closely mirrors phytoplankton abundance and species. Initial physical-chemical conditions, such as carbonate system and nutrient availability, may mediate the sensitivity of phytoplankton and sulfur compounds to environmental shifts. This study enhances our understanding of biogenic sulfur responses in dynamic marine ecosystems and provides essential basis for future climate modeling.
Key Points
- External stressors alter algal communities and production and degradation of dimethyl sulfoniopropionate, thus affecting biogenic sulfides
- Response of carbon disulfide to different environmental stressors is closely linked to algal abundance
- Initial physical-chemical conditions of seawater mediate algae and biogenic sulfides’ sensitivity to environmental stressors
Plain Language Summary
Biogenic sulfur-containing compounds in the ocean, such as dimethyl sulfoniopropionate (DMSP), dimethyl sulfide (DMS), methyl mercaptan (MeSH), and carbon disulfide (CS2), play critical roles in the global sulfur cycle and have the potential to influence the Earth’s climate. For instance, DMS released from the ocean into the atmosphere contributes to cloud formation, which in turn affects weather patterns. Over recent decades, rapid environmental changes in marine ecosystems may have significantly impacted marine biogeochemical processes. To investigate how these compounds respond to such changes, we conducted two ship-based incubation experiments in the Northwest Pacific and Eastern Indian Oceans. We assessed the effects of dust deposition, ocean acidification (due to increased carbon dioxide), and microplastic pollution on the production of DMSP, DMS, MeSH, and CS2 by marine organisms. Our results demonstrate that these stressors alter phytoplankton growth and community composition and impact the pathways through which DMSP is degraded. Consequently, the concentrations of sulfur compounds in seawater are affected. Notably, changes in CS2 levels were more closely related to shifts in phytoplankton abundance. These findings enhance our understanding of how marine sulfur compounds may respond to future oceanic changes and offer valuable data for improving climate models.
Continue reading ‘Effects of different environmental stressors on marine biogenic sulfur compounds in the Northwest Pacific and Eastern Indian Oceans’Building ocean acidification research and policy capacity in the wider Caribbean region: a case study for advancing regional resilience
Published 1 July 2025 Science ClosedTags: policy
To meet scientific, policy, and community goals, there is a critical need to strengthen research capacity, increase monitoring, and inform adaptation and mitigation policies to enhance resilience against ocean acidification (OA) and associated multi-stressors in the Caribbean. In 2023, an OA Needs Based Assessment survey of ocean professionals was conducted, engaging 59 participants from across the wider Caribbean to evaluate regional challenges and opportunities in OA research and monitoring. To understand differences in OA research capacity related to training and funding, we divide the respondents into four groups: those that have received 1) training and funding, 2) training only, 3) funding only, and 4) neither training nor funding. Results indicate regional strengths include awareness of local oceanic conditions, access to nearshore sites, and strong social support networks in ocean research. Regional barriers include limited technical capacity and funding to conduct oceanographic research and monitoring, and in particular, carbonate measurements. The four training and funding groups vary significantly, suggesting that access to training and funding are important factors to increasing the amount of access that respondents have to different types of equipment, the number of different types of measurements they conduct, the number of different habitats they research, and the amount of experience they have conducting OA research. This study also demonstrates the community-led efforts to address local OA challenges by presenting a case study on the formation of the Global Ocean Acidification Network (GOA-ON) OA Caribbean Hub that was founded by local leaders (co-authors of this study) who were inspired through the survey process and engagement that was conducted by co-authors. This study provides examples of avenues and challenges to build OA capacity for research and monitoring from the ground up within the wider Caribbean to advance towards global sustainability goals.
Continue reading ‘Building ocean acidification research and policy capacity in the wider Caribbean region: a case study for advancing regional resilience’Non-additive phospholipidomic responses to ocean warming and acidification drive intraspecific variation in cell membrane vulnerability in a marine ectotherm
Published 1 July 2025 Science ClosedTags: adaptation, biological response, crustaceans, laboratory, multiple factors, North Atlantic, otherprocess, physiology, temperature
Highlights
- Shrimp show non-additive phospholipidome responses to combined OW and OA.
- Synergistic and antagonistic responses are origin- and scenario-dependent.
- Physiological shifts emerge when OA occurs near shrimp’s thermal limits.
- Shrimp show potential local adaptation/acclimatisation of cell membrane phenotypes.
- Shrimp cell membrane vulnerability to combined OW and OA is origin-dependent.
Abstract
The lipidome is fundamental to the good functioning of cells and organisms. However, its role in species acclimatisation and adaptation to global changes remains overlooked. Investigating intraspecific variation in lipidome responses to combined global change drivers is therefore paramount to predict species’ vulnerability in future oceans. Here, we profiled the phospholipidome of the Northern shrimp, Pandalus borealis, from four different origins in the Northwest Atlantic, within an orthogonal design of ocean warming (OW) and acidification (OA) scenarios. We report complex origin-dependent non-additive responses under combined global changes. Shrimp display a high degree of intraspecific variation with distinct profiles of synergism, antagonism or temperature-driven phospholipidome responses when OA is superimposed on OW. Shrimp from the southernmost origin are only sensitive to OW, whilst those from the other three origins respond to combined OW and OA. These patterns involve changes in cellular membranes’ unsaturation, fluidity, curvature and thickness, underlying differential intraspecific cellular vulnerability to global changes. The isolated effects of OA are subtler, visible only in shrimp from the St. Lawrence Estuary (SLE). Shrimp from SLE also show the most pronounced phospholipidome remodelling, allowing them to acclimate to combined OW and OA. Whilst SLE shrimp seem most sensitive to global changes, those from the northernmost origins (Newfoundland and Esquiman Channel) display the greatest cellular vulnerability under combined OW and OA. Our findings evidence the highly complex interplay of OW and OA in remodelling marine ectotherms’ phospholipidomes, with direct implications for prioritising conservation efforts on populations most vulnerable to global changes.
Continue reading ‘Non-additive phospholipidomic responses to ocean warming and acidification drive intraspecific variation in cell membrane vulnerability in a marine ectotherm’The seven sins of climate change: a review of rates of change, and quantitative impacts on ecosystems and water quality in the Great Barrier Reef
Published 1 July 2025 Science ClosedTags: biological response, BRcommunity, chemistry, corals, review, South Pacific
Highlights
- Reviewed rates of change for 7 climate change factors, quantifying impacts
- Climate change affects water quality, emphasising local management needs
- Extreme weather events are still the most destructive climate change factors
- Progressive climate factors will increase in importance, altering ecosystems.
- Ocean acidification may reach critical thresholds within decades.
Abstract
The term climate change encompasses many types of impacts and threats to the long-term outlook of coastal marine ecosystems. Based on a structured Evidence Summary methodology, this review synthesises the peer-reviewed knowledge on climate change impacts on the Great Barrier Reef (GBR). We summarise the observed and predicted region-specific rates of change for seven climate change factors; three representing episodic extreme weather events (heatwaves, tropical storms, and extreme rainfall events), and four chronic progressive climate change factors (rising temperatures, ocean acidification and sea level, and altered cloudiness/windiness). We extract key quantitative findings on their impacts on GBR ecosystems and associated organisms, especially coral reefs, seagrasses, mangroves and wetlands, and on GBR water quality. Quantifying GBR-wide effects requires data on their four dimensions: intensity, duration, spatial extent, and frequency. The review shows that to date, most damage to GBR ecosystems is inflicted by extreme weather events. Of the progressive climate change factors, ocean acidification is already altering some GBR ecosystem functions, potentially reaching a critical threshold within decades. The progressive climate change factors are already causing selective mortality and changes in communities. We document regional differences, and we outline the evidence of climate change impacts on GBR water quality, suggesting further cumulative effects. This review provides an overview of empirical data for modellers and ecologists, and for experimentalists to choose environmentally relevant treatment levels. Intensifying climate change disturbances increase the urgency of climate change mitigation, as well as effective local management to accelerate ecosystem recovery.
Continue reading ‘The seven sins of climate change: a review of rates of change, and quantitative impacts on ecosystems and water quality in the Great Barrier Reef’A new model predicts dynamic seawater chemistry on Florida’s coral reefs
Published 1 July 2025 Press releases ClosedTags: communitymodeling, modeling
Water masses move over reefs, seagrass beds, and sandbanks – and as they do, the seawater chemistry changes.
In the Florida Keys, changes in coral reef carbonate chemistry are driven by benthic metabolism, the origin of the water mass, and the connectivity of habitats. A new study from NOAA’s Atlantic Oceanographic and Meteorological Laboratory (AOML) shows how we can use existing monitoring data to better understand the combined influence of these factors on local reef water chemistry.
Dr. Heidi Hirsh, an Assistant Scientist with the AOML Coral Program, demonstrates how integrating the source water, or “endmember”, chemistry conditions, the benthic habitat, and the flow of water between habitats can be used to predict the nearshore carbonate chemistry on a specific coral reef.
Benthic communities (i.e. seagrass, coral), source water (“endmember”) chemistry and the complex flow of water (hydrodynamics) between habitats all influence the local carbonate chemistry of a coral reef. Derived from: Hirsh, et al., 2025
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As part of the four-year Florida Regional Ecosystems Stressors Collaborative Assessment (FRESCA), a collaboration co-led by NOAA’s Atlantic and Meteorological Laboratory (AOML) and the University of Miami, Hirsh has developed a statistical model to predict nearshore coral reef carbonate chemistry based on modeled trajectories of currents and the interconnection between relevant sourcewater and habitats.
This approach takes into account where the water came from and the influence of marine ecosystems (i.e. benthic community metabolism) on a water mass before it arrives on a reef in a specific area.
Continue reading ‘A new model predicts dynamic seawater chemistry on Florida’s coral reefs ‘Novel sequential modeling framework improves phytoplankton biomass predictions in response to multiple environmental stressors
Published 1 July 2025 Science ClosedTags: biological response, modeling, North Pacific, phytoplankton, regionalmodeling
Understanding the impacts of multiple environmental stressors on phytoplankton biomass is crucial for predicting marine ecosystem responses under global climate change. This study employed a sequential modeling framework integrating principal component analysis, generalized additive models, and artificial neural networks to improve predictions of phytoplankton chlorophyll a concentrations in the Taiwan Strait. Analyzing a decadal dataset, we found that a 2C rise in sea surface temperature and a 0.2 pH decline will each lead to an 11.3% reduction in chlorophyll a biomass, whereas nitrogen enrichment is expected to increase it by only 2.8%. The combined effects of these stressors will result in an 18.3% reduction, with the most significant declines occurring in high-chlorophyll areas during algal blooms. Compared to simpler models, our approach improved accuracy by reducing overestimation biases, particularly under acidification scenarios, highlighting the need for advanced, multivariate models in forecasting phytoplankton dynamics under global changes.
Scientific Significance Statement
Phytoplankton are critical to marine ecosystems and global biogeochemical cycles, yet predicting their responses to the combined stressors of warming, acidification, and eutrophication remains a major challenge. Traditional models struggle with multicollinearity and nonlinear interactions among environmental variables. This study introduces an innovative sequential modeling framework that integrates principal component analysis, generalized additive models, and artificial neural networks, addressing these challenges by combining the strengths of each method in a series. This approach not only improves predictive accuracy, particularly during algal blooms, but also reveals that combined stressors lead to an 18.3% decline in phytoplankton biomass, underscoring their vulnerability under future climate scenarios. By bridging methodological advancements with ecological discovery, this work provides a powerful tool for understanding and forecasting marine ecosystem responses to global change.
Continue reading ‘Novel sequential modeling framework improves phytoplankton biomass predictions in response to multiple environmental stressors’An updated version of the OA-ICC bibliographic database is available online.
The database currently contains 9392 references and includes citations, abstracts and assigned keywords. Updates are made every month.
The database is available as a group on Zotero. Subscribe online or, for a better user experience, download the Zotero desktop application and sync with the group OA-ICC in Zotero. Please see the “User instructions” for further details.
Continue reading ‘OA-ICC bibliographic database updated’Biophysical model of eelgrass and water quality in Coos Bay, OR shows greater mitigation potential for ocean acidification than hypoxia
Published 30 June 2025 Science ClosedTags: biological response, chemistry, communitymodeling, mitigation, modeling, North Pacific, phanerogams
Seagrass beds provide important ecosystem services and are valued, in part, for their potential to mediate stressors such as ocean acidification and hypoxia (OAH) for sensitive species. However, the susceptibility of seagrasses to anthropogenic impacts and recent declines motivate the need to better understand the drivers of seagrass and the water quality consequences that occur with variation in seagrass abundance. To meet this need, we leveraged existing monitoring data (water quality and seagrass), hydrodynamic circulation model, and biogeochemical model framework with seagrass submodel, to produce a biophysical model of Coos Bay estuary, Oregon, U.S. The model includes biogeochemical processes involving water quality, plankton, seagrass, and sediment-water interactions. Ecosystem models like this are useful for evaluating complex estuarine systems because they allow us to extend our understanding of system dynamics beyond existing observations and perform experiments to identify the processes driving observed patterns. We used the biophysical model of Coos Bay to evaluate the dynamics of water quality and native eelgrass (Zostera marina) under three eelgrass abundance scenarios (zero eelgrass, current extent, and maximum observed extent) to elucidate the relationship between eelgrass and OAH. Including eelgrass in the Coos Bay model produced results that more closely resembled water quality observations – dissolved oxygen (DO) and pH were more dynamic in simulations with eelgrass, often having both higher highs and lower lows. While there were some areas of the estuary where DO improved with the addition of eelgrass to the model there was overall a small net increase in harmful DO conditions (based on a salmon physiological threshold). In contrast, ocean acidification conditions, pH and calcium carbonate saturation state for aragonite (Ω), were improved (based on oyster requirements) with the addition of eelgrass – although the magnitude of improvement differed seasonally and spatially. Our new model represents a useful tool – one which accounts for and controls the relevant physical and biogeochemical processes – to evaluate conditions that confer resilience or enhance vulnerability to OAH in an important Pacific Northwest coastal estuary and results can inform the OAH-related dynamics occurring in other eastern boundary current estuaries.
Continue reading ‘Biophysical model of eelgrass and water quality in Coos Bay, OR shows greater mitigation potential for ocean acidification than hypoxia’Commentary: synthesis of thresholds of ocean acidification impacts on decapods
Published 30 June 2025 Science ClosedTags: biological response, crustaceans, review
Biologically-relevant ocean acidification (OA) thresholds and syntheses are critical for interpreting the growing body of OA monitoring data and guiding ocean conservation actions. Bednaršek et al. (2021a) conducted such a synthesis and developed OA-specific thresholds for decapods, compiling literature data and analyzing 27,000 data points from 55 studies, making it one of the most robust OA decapod meta-analyses. Bednaršek et al. (2021a) related biological responses to OA stress and then convened a working group of experts to develop consensus thresholds based on that evidence, using similar approaches and data analyses as published previously for pteropods and echinoderms (Bednaršek et al., 2019, 2021b).
McElhany and Bush (2024) critiqued the decapod synthesis and suggested a need for re-evaluation. Their primary concerns were with the statistical methods, particularly the use of Least Squares Regression (LSR) and Piecewise Regression (PR). They argued that LSR-derived thresholds are dependent on experimental pH ranges, while PR is criticized because all data points were treated equally, rather than weighing them so each study has an equal influence on the outcome.
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While we disagree with the McElhany and Bush (2024) critiques and assert the thresholds developed by Bednaršek et al. (2021a) through expert consensus are suitable for OA risk assessments, we do want to highlight that these important numbers should be subject to continual refinement. We suggest that the greatest improvements in the threshold estimates in the future will come from more targeted experimental design focusing specifically on deriving biological thresholds. Specifically, increasing the number of exposure levels and the number of species across different habitats will allow for greater species-specific data resolution robustness of their thresholds. Moreover, conducting studies that account for, or better yet quantify, multifactorial stressors, biological variability and adaptations will provide greater value. Reducing the differences in experimental parameters will improve future statistical modelling and help the scientific community advance towards more robust thresholds that can effectively guide conservation efforts.
Continue reading ‘Commentary: synthesis of thresholds of ocean acidification impacts on decapods’Assessing pteropod shell dissolution to advance ocean monitoring techniques: a methods comparison of SEM, CT, and light microscopy
Published 30 June 2025 Science ClosedTags: biological response, methods, mollusks, morphology, zooplankton
Pteropods are marine planktonic snails that are used as bioindicators of ocean acidification due to their thin, aragonitic shells, and ubiquity throughout the world’s oceans; their responses include decreased size, reduced shell thickness, and increased shell dissolution. Shell dissolution has been measured with a variety of metrics involving light microscopy, scanning electron microscopy (SEM), and computed tomography (CT). While CT and SEM metrics offer high resolution imaging, these analyses are cost- and time-intensive relative to light microscopy analysis. This research compares light microscopy, CT, and SEM shell dissolution metrics across three pteropod species: Limacina helicina, Limacina retroversa, and Heliconoides inflatus. Sourced from multiple localities, these specimens lived in tropical to subpolar environments and were exposed to varying aragonite saturations states due to oceanographic differences in these environments. Specimens were evaluated with light microscopy for the Limacina Dissolution Index (LDX), with SEM for percent of pristine shell coverage and maximum dissolution type, and with CT for whole-shell thickness. LDX and the percentage of pristine shell determined via SEM were highly correlated in all three species’ datasets. For L. retroversa, LDX was also significantly correlated to SEM maximum dissolution type. Although the genera Heliconoides and Limacina have different shell microstructures, the relationship between LDX and SEM dissolution did not vary by species. The CT metric for shell thickness was not significantly correlated to any other dissolution metrics for any species. However, severely dissolved areas apparent in SEM were visually discernible in CT thickness heatmaps. While CT may not detect minor shell dissolution, previous studies have used CT to detect reduced calcification in response to ocean acidification. SEM is ideal for detecting the onset of dissolution, but SEMing large numbers of specimens may not be practical due to monetary and time constraints. LDX, on the other hand, is a fast and cost-effective metric that is strongly correlated with SEM metrics, regardless of the oceanographic conditions that those species experienced. These results suggest that an efficient ocean acidification monitoring strategy is to evaluate all pteropod specimens via LDX and to then SEM a subset of those specimens.
Continue reading ‘Assessing pteropod shell dissolution to advance ocean monitoring techniques: a methods comparison of SEM, CT, and light microscopy’‘Ticking timebomb’: sea acidity has reached critical levels, threatening entire ecosystems – study
Published 27 June 2025 Press releases ClosedThe world’s oceans are in worse health than realised, scientists have said today, as they warn that a key measurement shows we are “running out of time” to protect marine ecosystems.
Ocean acidification, often called the “evil twin” of the climate crisis, is caused when carbon dioxide is rapidly absorbed by the ocean, where it reacts with water molecules leading to a fall in the pH level of the seawater. It damages coral reefs and other ocean habitats and, in extreme cases, can dissolve the shells of marine creatures.
Until now, ocean acidification had not been deemed to have crossed its “planetary boundary”. The planetary boundaries are the natural limits of key global systems – such as climate, water and wildlife diversity – beyond which their ability to maintain a healthy planet is in danger of failing. Six of the nine had been crossed already, scientists said last year.
However, a new study by the UK’s Plymouth Marine Laboratory (PML), the Washington-based National Oceanic and Atmospheric Administration and Oregon State University’s Co-operative Institute for Marine Resources Studies found that ocean acidification’s “boundary” was also reached about five years ago.
“Ocean acidification isn’t just an environmental crisis – it’s a ticking timebomb for marine ecosystems and coastal economies,” said PML’s Prof Steve Widdicombe, who is also co-chair of the Global Ocean Acidification Observing Network.
The study drew on new and historical physical and chemical measurements from ice cores, combined with advanced computer models and studies of marine life, which gave the scientists an overall assessment of the past 150 years.
It found that by 2020 the average ocean condition worldwide was already very close to – and in some regions beyond – the planetary boundary for ocean acidification. This is defined as when the concentration of calcium carbonate in seawater is more than 20% below preindustrial levels.
Continue reading ‘‘Ticking timebomb’: sea acidity has reached critical levels, threatening entire ecosystems – study’Applications open: third winter school on ocean acidification and multiple stressors
Published 27 June 2025 Courses and training , Science ClosedDates: 24 November – 5 December 2025
Location: IAEA Marine Environment Laboratories, Monaco.
Deadline for receipt of application from the nominating national authority: 15 September 2025
The course is organized by the IAEA OA-ICC in partnership with the Prince Albert II of Monaco Foundation through the OACIS Initiative (Ocean Acidification and other ocean Changes – Impacts and Solutions).
Introduction
Ocean acidification is a global environmental stressor that threatens marine life and the livelihoods of coastal communities. Ocean acidification is caused by increasing atmospheric carbon dioxide being absorbed by the ocean, resulting in changes to seawater carbonate chemistry, including a drop in pH. Due to global concerns about its consequences, ocean acidification is included in international policies such as Target 3 of UN Sustainable Development Goal (SDG) 14 and Target 8 of the Global Biodiversity Framework (GBF).
The IAEA’s Ocean Acidification International Coordination Centre (OA-ICC) supports IAEA Member States to minimize and adapt to OA and report towards SDG 14.3 and the GBF, with a strong focus on building capacity to study ocean acidification and related stressors and promoting international collaboration and coordination.
Ocean acidification is not happening in isolation, but in combination with other human-driven pressures, including pollution, warming, and oxygen loss. The impact of multiple ocean stressors on marine life and ecosystem function is not well understood, yet this information is crucial to inform adaptation strategies that might minimize negative effects on organisms, ecosystems, and associated
socioeconomic benefits.
The Third Winter School on Ocean Acidification and Multiple Stressors is part of the capacity building program of the OA-ICC. This two-week training course will provide participating scientists with a thorough understanding about key concepts and experimental design used to study the impacts of ocean acidification in the context of additional stressors.
Objectives
The aim of the Winter School is to train early-career scientists who already have experience researching ocean acidification on how to study acidification in the context of other co-occurring stressors. Through lectures and practical exercises in the laboratory, the students will gain understanding of key concepts in multiple-stressor research (e.g., What is a stressor? What is a mode of action? What is an interaction?), purposeful experimental design, and analysis of complex datasets. During the course, participants will collaborate on a joint laboratory experiment to elucidate the effects of three simultaneous drivers on marine organisms, with the objective to publish the results in a collective article after the training.
Target Audience
The course is open to 10-12 trainees. Priority will be given to early-career scientists with experience in marine environmental change with a focus on ocean acidification; a background in biological sciences is preferred. At least one publication in the field of marine environmental change is required.
Working Language: English
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Participation and Registration
All persons wishing to participate in the event have to be designated by an IAEA Member State or should be members of organizations that have been invited to attend.
In order to be designated by an IAEA Member State, participants are requested to send the Participation Form (Form A) to their competent national authority (e.g. Ministry of Foreign Affairs, Permanent Mission to the IAEA or National Atomic Energy Authority) for onward transmission to the IAEA by 15 September 2025. Participants who are members of an organization invited to attend are requested to send the Participation Form (Form A) through their organization to the IAEA by the above deadline.
Selected participants will be informed in due course on the procedures to be followed with regard to administrative and financial matters.
Participants are hereby informed that the personal data they submit will be processed in line with the Agency’s Personal Data and Privacy Policy and is collected solely for the purpose(s) of reviewing and assessing the application and to complete logistical arrangements where required. The IAEA may also use the contact details of Applicants to inform them of the IAEA’s scientific and technical publications, or the latest employment opportunities and current open vacancies at the IAEA. These secondary purposes are consistent with the IAEA’s mandate.
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Additional Requirements
Participants should have a university degree in marine chemistry, biology, oceanography or a related scientific field, and should be currently involved in or planning to study the ecological impact of multiple stressors, including ocean acidification. Experience in R is strongly encouraged.
Selection will be based on merit and interest. Applications should include:
- A motivation letter with a short description of the candidate’s research interests and how the course would benefit the applicant’s current or future research on ocean acidification and multiple stressors (max one A4 page)
- CV with publication list
Spatial variability of marine carbonate system along the Drake Passage and northern Antarctic Peninsula during the austral summer
Published 27 June 2025 Science ClosedTags: Antarctic, chemistry, field
Highlights
- Sea surface pCO2, O2 and hydrographic parameters were measured, whereas Alk was estimated through different approaches.
- In Drake Passage, photosynthesis drives carbonate variability north of the Polar Front and upwelling dominates to the south.
- Photosynthesis reduces pCO2 and increases pH and carbonate concentration at enclosed coastal Antarctic areas.
- Lowest pH in the northern Antarctic Peninsula likely results from mixing of waters rich in natural and anthropogenic carbon.
- Calcite and aragonite are mostly supersaturated though aragonite undersaturation occurs under Dense Shelf Water influence.
Abstract
The influence of physical and biogeochemical processes on the variability of the carbonate system in the Southern Ocean remains poorly constrained. Understanding this influence is crucial to distinguish natural variations from anthropogenic impacts and accurately interpret observed trends. Here, we investigate how physical and biogeochemical processes influence the spatial distribution of summer carbonate system variables along the Drake Passage and northern Antarctic Peninsula. Continuous, high-frequency surface partial pressure of CO2 (pCO2), dissolved oxygen (O2) and essential hydrographic variables were collected during the austral summer of 2019, whereas other carbonate system variables were estimated after the reconstruction and evaluation of total alkalinity. Our findings show that in the Drake Passage, Circumpolar Deep Water upwelling increases the pCO2 (> 400 μatm) and dissolved inorganic carbon (> 2175 μmol kg−1), leading to reduced pH (< 7.99) south of the Polar Front. North of the Polar Front, photosynthesis lowers pCO2 (< 390 μatm), while increasing pH (> 8.00) and carbonate ions (> 110 μmol kg−1), with enrichment occurring in the Subantarctic coccolithophore growth region. Along the northern Antarctic Peninsula, including Gerlache Strait, Antarctic Sound, and Admiralty Bay, photosynthesis and sea ice/glacial melt are the main drivers of pCO2 reductions to levels below 350 μatm. The mixing of Circumpolar Deep Water with Weddell Sea Dense Shelf Water can naturally and anthropogenically raise pCO2 and decrease pH in northern Antarctic Peninsula waters, where pH is generally lower (as low as 7.90) compared to adjacent areas. Nevertheless, most environments remain supersaturated with respect to carbonate minerals calcite and aragonite, although signs of aragonite undersaturation have occur in surface waters influenced by Dense Shelf Water. These findings offer new insights into carbonate system processes across a large Southern Ocean region, improving understanding of spatial variability in marine carbon dynamics.
Continue reading ‘Spatial variability of marine carbonate system along the Drake Passage and northern Antarctic Peninsula during the austral summer’Deadline extension: basic training course on ocean acidification
Published 26 June 2025 Events ClosedDates: 11-15 August 2025
Location: Kingston, Jamaica
Deadline for receipt of application from the nominating national authority: 2 July 2025
The course is a cooperative effort organized by the International Atomic Energy Agency’s Ocean Acidification International Coordination Centre (OA-ICC) and hosted by the Government of Jamaica through the University of the West Indies (UWI) as the local organizer.
Introduction
The IAEA’s Ocean Acidification International Coordination Centre (OA-ICC) supports IAEA Member States to minimize and adapt to OA and report towards SDG 14.3 and the GBF, with a strong focus on building capacity to study ocean acidification and related stressors and promoting international collaboration and coordination.
Caribbean Small Island Developing States (SIDS) are particularly vulnerable to ocean acidification due to their reliance on the ocean for food, income, and recreation. This Basic Training Course on Ocean Acidification will provide scientists from Caribbean SIDS with foundational knowledge on conducting ocean acidification monitoring and designing purposeful experiments to understand the impacts of ocean acidification on key marine organisms in the Caribbean region. By the end of the course, participants will have a better understanding of the challenges and complexities presented by ocean acidification and the critical role we all play in addressing this issue and developing solutions.
Objectives
The course aims to empower Caribbean SIDS to monitor ocean acidification and its effects on key marine species, informing both SDG 14.3 and Target 8 of the Global Biodiversity Framework, and to explore local solutions to increase the resilience to ocean acidification in the region.
It will cover various topics, including theoretical aspects and best practices for the measurement of seawater carbonate chemistry, how to evaluate the impacts of ocean acidification on marine species and ecosystems, and potential solutions for minimizing its effects, including possible local adaptation measures. Guidance on how to report towards Sustainable Development Goal 14.3 and its indicator 14.3.1 on ocean acidification will be provided.
The course will be taught by experts in the field of ocean acidification, who will provide lectures, interactive discussions, and hands-on activities to ensure that participants gain a comprehensive understanding of the topic. The course will also provide opportunities for participants to network with peers and engage with the broader ocean acidification community. Local aquaculture managers will be invited to a special session to discuss potential local adaptation measures to counter the effects of ocean acidification in the Caribbean.
Target Audience
The course is intended for scientists from the Caribbean who are entering the ocean acidification field. It is open to 10 to 12 trainees from the following countries: Antigua and Barbuda, Bahamas, Barbados, Belize, Cuba, Dominica, Dominican Republic, Grenada, Guyana, Haiti, Jamaica, Saint Kitts and Nevis, Saint Lucia, Saint Vincent and the Grenadines, Suriname and Trinidad and Tobago.
Priority will be given to early-career scientists with experience in marine sciences. Scientific publications in related fields will be valued.
Working Language: English
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Participation and Registration
All persons wishing to participate in the event have to be designated by an IAEA Member State or should be members of organizations that have been invited to attend.
In order to be designated by an IAEA Member State, participants are requested to send the Participation Form (Form A) to their competent national authority (e.g. Ministry of Foreign Affairs, Permanent Mission to the IAEA or National Atomic Energy Authority) for onward transmission to the IAEA by 2 July 2025. Participants who are members of an organization invited to attend are requested to send the Participation Form (Form A) through their organization to the IAEA by the above deadline.
Selected participants will be informed in due course on the procedures to be followed with regards to administrative and financial matters.
Participants are hereby informed that the personal data they submit will be processed in line with the Agency’s Personal Data and Privacy Policy and is collected solely for the purpose(s) of reviewing and assessing the application and to complete logistical arrangements where required. The IAEA may also use the contact details of Applicants to inform them of the IAEA’s scientific and technical publications, or the latest employment opportunities and current open vacancies at the IAEA. These secondary purposes are consistent with the IAEA’s mandate.
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Additional Requirements
The participants should have a university degree in marine chemistry, biology, oceanography or a related scientific field, and should be currently involved in or planning to study ocean acidification. Scientific publications in related fields will be valued.
Selection will be based on merit and interest. Applications should include:
- A motivation letter with a short description of the candidate’s research interests and how the course would benefit the applicant’s current or future research (max one A4 page).
- CV with publication list.
Combined physiological effects of differentially charged nanoplastics and ocean acidification on the mussel Mytilus coruscus
Published 26 June 2025 Science ClosedTags: biological response, laboratory, mollusks, morphology, multiple factors, North Pacific, physiology
Highlights
- OA enhances the effect of P-NPs on mussels.
- The effect of P-NPs on oxidative stress of mussels was more significant.
- OA changes the effect of differentially charge nanoplastics on energy metabolism.
- OA may affect the behavior and toxicity of NPs by altering its charge distribution.
Abstract
In the context of ocean acidification (OA) in the near future, along with the continuous production of nanoplastics (NPs) with different charges in the ocean, it is critical to investigate their combined effects on marine life and ecosystem stability. Thus, this study assessed the joint effects of NPs with different charges and OA on Mytilus coruscus by analyzing antioxidant stress, energy metabolism, condition index, and shell resistance. Results indicated that positively charged NPs (P-NPs) significantly elevated ROS levels, MDA content, and the activities of GPX and CAT, with more pronounced effects under OA. NPs with different charges have varying effects on energy metabolism enzyme activity, and OA further influences these disparities. Overall, P-NPs had a more detrimental impact on mussels, an effect that was further intensified by OA. Low pH alters the surface charge distribution of NPs, enhancing their binding to biomolecules and potentially exacerbating physiological effects on mussels by altering NPs’ aggregation behavior. This study provides insights into the combined toxic effects of NPs with different charges and OA on mussels, offering a reference for evaluating the environmental risks of OA and charged NPs in marine ecosystems.
Continue reading ‘Combined physiological effects of differentially charged nanoplastics and ocean acidification on the mussel Mytilus coruscus’Infaunal bivalves exhibit resilience to ocean acidification but remain sensitive to food supply
Published 26 June 2025 Science ClosedTags: biological response, chemistry, dissolution, laboratory, mesocosms, mollusks, morphology, multiple factors, physiology, South Pacific
Soft-sediment habitats are crucial for marine coastal ecosystems, supporting diverse biodiversity both above and below the sediment. Ocean acidification, driven by rising CO2 and nutrient influx, enhances heterotrophic metabolism, raising CO2 levels and lowering pH. These alterations complicate the dynamics of tidal flat, emphasizing the need for further research into their impact on biodiversity. Within these ecosystems, deposit- and suspension-feeding bivalves play crucial roles. Tagelus dombeii, a bivalve mollusc found in soft sediments, exhibits burrowing behavior linked to food supply and is of significant commercial value in southern Chile. This study assessed the response capacity of T. dombeii to key stressors associated with global ocean change, such as ocean acidification and food availability. Our results revealed significant differences in pH levels between the water column and pore water from the sediment in experimental mesocosms. T. dombeii was affected by ocean acidification and food availability in terms of its morphological traits (i.e. length, width, height and growth rate), while oxygen consumption was influenced only by the interaction between acidification and food supply. Notably, heart rate remained constant but increased when food supply was low. Our study suggests that T. dombeii exhibits partial tolerance to variations in seawater pH and carbonate chemistry, possibly due to its natural exposure to acidic pore water, but it is sensitive to food availability. These plastic physiological responses suggest that T. dombeii may be less vulnerable to future global change scenarios, demonstrating potential resilience and ecological success in its natural habitat.
Continue reading ‘Infaunal bivalves exhibit resilience to ocean acidification but remain sensitive to food supply’Surface Ocean CO2 Atlas Database Version 2025 (SOCATv2025) (NCEI Accession 0304549)
Published 25 June 2025 Science ClosedTags: chemistry, field
The ocean absorbs one quarter of the global CO2 emissions from human activity. The community-led Surface Ocean CO2 Atlas (www.socat.info) is key for the quantification of ocean CO2 uptake and its variation, now and in the future. SOCAT version 2025 has quality-controlled in situ surface ocean fCO2 (fugacity of CO2) measurements on ships, moorings, sailing yachts, autonomous and drifting surface platforms for the global ocean and coastal seas from 1957 to 2025. The main SOCAT synthesis and gridded products contain fCO2 values with an estimated accuracy of better than 5 μatm. Sensor fCO2 data with an estimated accuracy of better than 10 μatm are separately available. During secondary quality control, marine scientists assign a flag to each data set, as well as WOCE flags of 2 (good), 3 (questionable) or 4 (bad) to individual fCO2 values. Data sets are assigned flags of A and B for an estimated accuracy of better than 2 μatm, flag of C (and D) for an accuracy of better than 5 μatm and a flag of E for an accuracy of better than 10 μatm. Bakker et al. (2016) describe the quality control criteria used from SOCAT version 3 onward. SOCAT quality control cookbooks provide quality control updates (www.socat.info), with (Gkritzalis et al., 2024) used for version 2025. Quality control comments for individual data sets can be accessed via the SOCAT Data Set Viewer (www.socat.info). All data sets, where data quality has been deemed acceptable, have been made public. The main SOCAT synthesis files and the gridded products contain all data sets with an estimated accuracy of better than 5 µatm (data set flags of A to D) and fCO2 values with a WOCE flag of 2. Access to data sets with an estimated accuracy of better than 10 µatm (flag of E) and fCO2 values with flags of 3 and 4 is via additional data products and the Data Set Viewer (Table 8 in Bakker et al., 2016). SOCAT publishes a global gridded product with a 1° longitude by 1° latitude resolution without gap filling. A second product with a higher resolution of 0.25° longitude by 0.25° latitude is available for the coastal seas. The gridded products contain all data sets with an estimated accuracy of better than 5 µatm (data set flags of A to D) and fCO2 values with a WOCE flag of 2. Gridded products are available monthly, per year and per decade. Two powerful, interactive, online viewers, the Data Set Viewer and the Gridded Data Viewer (www.socat.info), enable investigation of the SOCAT synthesis and gridded data products. SOCAT data products can be downloaded. Matlab code is available for reading these files. Ocean Data View also provides access to the SOCAT data products (www.socat.info). SOCAT data products are discoverable, accessible and citable. The SOCAT Data Use Statement (www.socat.info) asks users to generously acknowledge the contribution of SOCAT scientists by invitation to co-authorship, especially for data providers in regional studies, and/or reference to relevant scientific articles. It also asks users to cite the relevant SOCAT data set, the relevant methods paper(s), and to use acknowledgement text (https://socat.info/index.php/citing-socat/). The SOCAT website (www.socat.info) provides a single access point for online viewers, downloadable data sets, the Data Use Statement, a list of contributors and an overview of scientific publications on SOCAT and using SOCAT. Automation of data upload and initial data checks have allowed annual releases of SOCAT from version 4 onwards. Automation of metadata upload is ongoing. SOCAT is used for quantification of ocean CO2 uptake and ocean acidification and for evaluation of earth system models and sensor data. SOCAT products inform on ocean CO2 uptake in the annual Global Carbon Budget since 2013. SOCAT is a key element of the World Meteorological Organization’s (WMO) Global Greenhouse Gas Watch (G3W) program and is a key resource for Copernicus’ evaluations. The annual SOCAT releases by the SOCAT scientific community contribute to United Nations (UN) Sustainable Development Goal (SDG) 13 and SDG 14 (Life Below Water), and to the UN Decade of Ocean Science for Sustainable Development. However, since 2022 SOCAT critically relies on support provided by the Pacific Marine Environmental Laboratory of the National Oceanic and Atmospheric Administration in the US. This has been sufficient to keep the basic operation running, however this limited support has resulted in SOCAT data architecture not being updated, leading to a system with limited resilience that is highly vulnerable to external factors. Hundreds of peer-reviewed scientific publications and high-impact reports cite SOCAT. The SOCAT community-led synthesis product is a key step in the value chain based on in situ surface ocean carbon measurements, which provides policy makers with critical information on ocean CO2 uptake for policy makers. The need for accurate knowledge of global ocean CO2 uptake and its (future) variation makes sustained funding of in situ surface ocean CO2 observations and their synthesis imperative.
Surface Ocean CO₂ Atlas (SOCAT)
Continue reading ‘Surface Ocean CO2 Atlas Database Version 2025 (SOCATv2025) (NCEI Accession 0304549)’Revisiting wastewater pH standards: a policy lever for mitigating coastal acidification and enhancing blue carbon
Published 25 June 2025 Science ClosedTags: mitigation, policy, socio-economy
Global ocean acidification driven by atmospheric CO2 uptake is well recognized; however, coastal zones are subject to additional, localized acidification pressures. Among these, the chronic discharge of low pH treated wastewater (often pH 6.0), permitted under many current regulations, represents a significant but often overlooked stressor. This practice introduces highly acidic loads into sensitive nearshore ecosystems that are chemically incompatible with ambient seawater (pH ∼8.1). This perspective argues for reframing effluent pH not only as a pollutant parameter to be bounded but also as a modifiable policy lever. Revising discharge standards to require a minimum effluent pH > 8.0 for marine outfalls offers a novel pathway to mitigate localized coastal acidification. Furthermore, this approach aligns with emerging ocean alkalinity enhancement strategies, potentially enhancing coastal carbon sequestration and offering cobenefits such as reduced metal toxicity. Such a policy shift necessitates technological adaptation but promises significant benefits for coastal resilience and broader ocean sustainability goals.
Continue reading ‘Revisiting wastewater pH standards: a policy lever for mitigating coastal acidification and enhancing blue carbon’
