Application open: OA-ICC Basic Training Course on Ocean Acidification in Kingston, Jamaica

Published 19 December 2025 Courses and training , Science Closed

Dates: 16-20 March 2026

Location: Kingston, Jamaica

Deadline for receipt of application from the nominating national authority: 30 January 2026

The IAEA Ocean Acidification International Coordination Centre (OA-ICC) is holding a regional Basic Training Course on Ocean Acidification in Kingston, Jamaica from 16-20 March 2026.

Applications are open to anyone from 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.

In order to apply, applicants will need to submit their application through their national authority to the IAEA – in most cases, this will be your country’s permanent mission to the IAEA.

This course was previously scheduled for 2025. Please note that if you previously applied to the course, your application is still being considered.

Read below for full course details:

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.

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Editorial: ocean acidification in Latin America

Published 22 January 2026 Science Leave a Comment
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Ocean acidification is among the most significant threats to marine ecosystems worldwide, with profound implications for biodiversity, food security, and coastal economies (Gattuso et al., 2023). The Latin American region, with its vast coastline (approximately 59,960 km) and productive marine areas, hosts some of the planet’s most biodiverse ecosystems, including those in the Humboldt Current, the Tropical West Atlantic, the Pacific Central-American Coastal regions, the Gulf of California and the Southwest Atlantic. These ecosystems are critical to livelihoods and climate regulation, supporting diverse habitats such as coral reefs, mangroves, salt marshes, sandy beaches and kelp forests. However, they face significant threats from pollution, degradation, and are particularly vulnerable to changes in ocean chemistry. The studies compiled in this Research Topic of Frontiers in Marine Science provide crucial, up-to-date evidence on the complex interactions between global climate forcings and intricate local oceanographic variability, as well as their impacts on economically and ecologically important species, providing a detailed, multidimensional picture of the region’s specific vulnerabilities and resilience mechanisms. This editorial summarizes the 11 studies in this Research Topic, highlighting the advances in understanding OA in Latin America.

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Detecting the acidity of the ocean with sound, the role of lead in human evolution, and how the universe ends (podcast)

Published 22 January 2026 Media coverage Leave a Comment
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First up on the podcast, increased carbon dioxide emissions sink more acidity into the ocean, but checking pH all over the world, up and down the water column, is incredibly challenging. Staff Writer Paul Voosen joins host Sarah Crespi to discuss a technique that takes advantage of how sound moves through the water to detect ocean acidification.

…

This week’s episode was produced with help from Podigy.

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Coastal eutrophication and freshwater inputs drive acidification in the Indian River Lagoon, Florida

Published 22 January 2026 Science Leave a Comment
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Highlights

  • First quantification of acidification throughout the IRL using Ωarag.
  • A positive relationship was found between Ωarag and salinity.
  • Ωarag had a negative relationship with dissolved nutrients.
  • Nutrients, algal blooms, and freshwater are drivers of acidification in the IRL.
  • Ωarag is important to understand eutrophication in estuaries.

Abstract

The additive effects of eutrophication and acidification in coastal environments have a wide range of implications for the health of organisms and ecosystems. In the eutrophic waters of the Indian River Lagoon (IRL), FL, USA, decreases in overall shellfish size have been reported, which may be related to coastal acidification. To better understand the relationship between acidification and eutrophication in the IRL, environmental parameters, dissolved nutrients, and aragonite saturation state (Ωarag) were monitored along the entire IRL in the 2016–2017 wet and dry seasons. Additionally, three sites in the central IRL were sampled approximately weekly from June 2016–June 2017 to observe temporal variability. For the IRL-wide survey, northern sites with higher dissolved nutrient concentrations had lower Ωarag due to nutrient pollution and harmful algal blooms, while southern sites with lower salinity had lower Ωarag related to freshwater inputs (i.e., discharges and rainfall). In the time series sampling, there was a positive correlation between Ωarag with salinity and negative correlations with dissolved nutrient concentrations. This work suggests that freshwater inputs and associated dissolved nutrients and organics have implications for acidification in the IRL, which will be important considerations for restoration efforts in the IRL and beyond.

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New river chemistry insights may boost coastal ocean modeling

Published 21 January 2026 Press releases Leave a Comment

Rivers deliver freshwater, nutrients, and carbon to Earth’s oceans, influencing the chemistry of coastal seawater worldwide. Notably, a river’s alkalinity and the levels of dissolved inorganic carbon it brings to the sea help to shape regional conditions for marine life, including shellfish and corals. These factors also affect the ability of coastal seawater to absorb carbon dioxide from Earth’s atmosphere—which can have major implications for climate change.

However, the factors influencing river chemistry are complex. Consequently, models for predicting worldwide carbon dynamics typically simplify or only partially account for key effects of river chemistry on coastal seawater. That could now change with new river chemistry insights from Da et al. By more realistically accounting for river inputs, the researchers demonstrate significant corrections to overestimation of the amount of carbon dioxide absorbed by the coastal ocean.

The researchers used real-world data on rivers around the world to analyze how factors such as forest cover, carbonate-containing rock, rainfall, permafrost, and glaciers in a watershed influence river chemistry. In particular, they examined how these factors affect a river’s levels of dissolved inorganic carbon as well as its total alkalinity—the ability of the water to resist changes in pH.

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The internal consistency between calculated and measured variables of the marine carbonate system in Arctic open and coastal waters, case study: Atlantic Arctic

Published 21 January 2026 Science Leave a Comment
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Highlights

  • Good consistency between calculated and measured variables of the marine carbonate system in Oceanic waters.
  • Only pH and pCO2 can be calculated with good accuracy in coastal waters.
  • The nutrient data are not required to calculate accurate marine carbonate system data in this region.
  • Total Alkalinity and pH (or pCO2) can be used to obtain good quality pCO2 (or pH) data.

Abstract

The Arctic Ocean plays a crucial role in anthropogenic carbon sequestration, while also being among the regions most susceptible to Ocean Acidification (OA). To understand, quantify, and monitor the rapid biogeochemical changes in the Arctic shelves and coastal waters, it is necessary to accurately determine the complete marine carbonate system. However, the uncertainty range in the calculated values is still unclear, fogging our ability to properly estimate carbon inventory and OA. In this study, we collected samples in the Arctic open and coastal waters to estimate the internal consistency of total alkalinity (TA), pH, partial pressure of CO2 (pCO2) and dissolved inorganic carbon (DIC) when only two of them are measured and the other two calculated. In open ocean waters, calculated values generally show good consistency with observations, whereas in coastal areas, it was only possible to accurately calculate two variables: 1) pH using as input parameters pCO2 together with either TA or DIC, and 2) pCO2 using DIC and pH. Furthermore, we found that, in this dataset, using the TA estimated from its correlation with salinity together with pCO2 also allowed obtaining accurate pH values in both coastal and ocean waters. This opens a new possibility of monitoring changes in the carbon cycle by measuring only salinity and pCO2 in areas where its consistency has been evaluated. Finally, in this study, we provide guidelines for obtaining and reporting good-quality carbonate system data in Arctic coastal areas.

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Nonlinear interactions of timing and amplitude biases in modeled Southern Ocean pCO2: the roles of dissolved inorganic carbon, total alkalinity, and sea surface temperature

Published 21 January 2026 Science Leave a Comment
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The Southern Ocean is a major sink for atmospheric carbon dioxide and critical to the current and future carbon cycle. This net annual CO2 flux reflects the balance between strong seasonal variability characterized by opposing periods of winter outgassing and summer uptake. Using a simple framework, we evaluate how model biases in both the amplitude and timing of dissolved inorganic carbon (DIC) and total alkalinity (TA) and in the amplitude of sea surface temperature (SST) impact simulated pCO2. We examine seasonal CO2 fluxes and pCO2 south of the Subantarctic Front in 42 Earth System Model and three state estimate simulations. Only 11 of the 45 simulations have a seasonal pCO2 cycle with a correlation of ≥0.7 to observed pCO2, while 26 have a correlation of <0. Four of the well-correlated models accurately represent the seasonality of SST, DIC, and TA, while TA biases compensate for DIC or SST biases in the other seven. DIC and SST amplitude biases are related to mixed layer (MLD) biases, with shallow MLDs, especially in the summer, correlated with larger amplitude DIC and SST cycles than observed. The amplitude of seasonal Net Primary Production is correlated to DIC and TA timing. We provide input on the main adjustments needed to correct the simulated pCO2 seasonality in each of the evaluated models. These findings highlight the difficulty and importance of capturing the seasonal processes influencing the carbonate system to correctly model and predict the Southern Ocean carbon sink and its response to a changing climate.

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Chronic exposure to low pH negatively impacts blue mussels (Mytilus edulis) from an intertidal zone

Published 20 January 2026 Science Leave a Comment
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In intertidal ecosystems, mussels experience daily fluctuations in pH due to the biological activity, intertidal currents, freshwater inflow and anthropogenic influences. This study aimed to determine whether these short-term fluctuations enable blue mussels (Mytilus edulis) to endure long-term exposure to low pH using biological indicators (mortality rates, oxidative stress and enzyme activities). Mussels were collected from an intertidal zone in the western coast of Morocco and exposed for 6 months to seawater pH ranging from 6.6 to 8.0. Our results showed that mortality rates increased exponentially with decreasing pH, while growth rates declined linearly. At pH 6.6, mortality was observed after approximately 15 days and reached 22% at 6 months. Low pH negatively impacted the function of metabolic enzymes (glyceraldehyde-3-phosphate dehydrogenase and succinate dehydrogenase), and caused oxidative stress (elevated lipid peroxidation and protein oxidation) in the mantle, digestive gland, and whole tissues. Additionally, the activity of antioxidant enzymes catalase and superoxide dismutase increased in response to higher levels of reactive oxygen species at low pH. These findings suggest that, although mussels can inhabit intertidal zones with short-term pH fluctuations, this does not equip them with the ability to deal with chronic exposure to low pH (6.6), significantly impairing their fitness.

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Neurometabolic rewiring in squid (Sepioteuthis lessoniana) optic lobes drives behavioral plasticity and visual integration under environmental acidification

Published 20 January 2026 Science Leave a Comment
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Ocean acidification’s impacts on marine animal behavior have substantial implications for ecosystem stability. Understanding how key predators respond to acidification is crucial for predicting future ocean food web dynamics, yet the underlying neural mechanisms remain poorly understood. Here, we show that prolonged exposure to projected year 2100 acidification conditions substantially impairs predatory behavior in bigfin reef squid (Sepioteuthis lessoniana), a key invertebrate predator. Chronic acidification exposure reduces expression of acetylcholine receptors in optic lobes and alters systemic HCO₃⁻ levels and metabolic rates. Using custom electroretinogram recordings, we find that while basic visual processing remains intact, behavioral impairments likely stem from changes in downstream neural integration pathways. Transcriptomic expression analysis reveals broad reductions in energy metabolism and synaptic signaling under acute exposure, while chronic exposure induces compensatory upregulation of cellular maintenance pathways. Our findings demonstrate that while squids maintain visual capabilities through adaptive mechanisms, the energy-intensive processes of neural integration and behavioral execution are compromised. These results highlight the complex physiological trade-offs marine predators face under ocean acidification, with implications for understanding future shifts in marine ecosystem structure and function.

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Metrological concepts applied to Total Alkalinity measurements in seawater: reference materials, inter-laboratory comparison and uncertainty budget

Published 20 January 2026 Science Leave a Comment
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Total alkalinity (TA) measurements in seawater are crucial for characterizing and monitoring the oceanic carbonate system. While international best practices and guidelines exist, the field still lacks widely available traceable reference materials and a well-established uncertainty budget of the measurement method. In this study, we applied key metrological principles – development of reference materials, inter-laboratory comparison and uncertainty quantification – to TA measurements. We developed two reference materials, including an artificial material with a rigorously characterized reference value and an associated uncertainty budget, being traceable to the International System of units (SI). These materials were tested in an inter-laboratory comparison involving five laboratories and demonstrated the applicability of the reference materials developed for quality control. Additionally, we established an uncertainty budget for the TA measurement method using two metrological approaches. The resulting expanded uncertainty was 5 µmol kg−1 (with a coverage factor k=2) in TA, approaching the 4 µmol kg−1 target set by the Global Ocean Acidification Observing Network for climate monitoring. These findings mark a significant step toward improving the quality and comparability of TA measurements, thereby strengthening long-term ocean carbonate system monitoring.

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Spatial dynamics of aragonite saturation state and blue carbon stocks in seagrass meadows of the Palk Bay, Southeast Coast of India

Published 19 January 2026 Science Leave a Comment
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Seagrass meadows are increasingly recognized for their role in mitigating climate change through blue carbon sequestration and their influence on local carbonate chemistry. This study investigates the spatial variability of aragonite saturation state (Ωarag) and assesses the blue carbon storage potential of seagrass meadows along the Palk Bay, Southeast Coast of India. Subsurface water samples were collected across multiple seagrass-dominated stations between May and June 2024. Key seawater carbonate system parameters, including pH, temperature, total alkalinity (TA), and salinity, were measured to calculate Ωarag using CO2SYS software. Sediment cores were analyzed for organic carbon content and bulk density to estimate carbon stock. Results revealed significant spatial variation in Ωarag, influenced by seagrass density, species composition (Cymodocea serrulata and C. rotundata), and hydrodynamic conditions. Stations with dense C. serrulata beds showed elevated Ωarag values, suggesting local amelioration of acidification stress. The mean carbon stock was estimated at 1.97 Mg C/ha−1, with higher values in more mature (> 60% cover) and dense seagrass patches. These findings highlight the dual ecological function of seagrass meadows in enhancing local carbonate saturation and functioning as effective carbon storage systems, underlining their significance in coastal ecosystem-based climate mitigation strategies.

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Northern shrimp exhibit origin-specific proteomic remodelling under ocean acidification, with limited response to ocean warming

Published 19 January 2026 Science Leave a Comment
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Highlights

  • Ocean acidification, but not warming, drives proteomic response in Northern Shrimp.
  • Shrimp from different origins show distinct molecular responses to ocean acidification.
  • St. Lawrence shrimp display the strongest protein changes to ocean acidification.
  • Local conditions shape how shrimp cope with global change drivers.
  • Conservation plans must consider regional differences in shrimp responses.

Abstract

The Northern shrimp (Pandalus borealis) is an ecologically important species and the target of one of the world’Canas largest shellfish fisheries. Yet, its habitats are rapidly changing due to human-driven climate change, with temperatures projected to increase by ∼4 °C and seawater pH to decline by 0.3 pH units the end of the century. These stressors may cause interactive effects, with responses differing among origins due to local adaptation or long-term acclimatisation. We investigated the impacts of ocean warming and acidification (individually and combined) on the proteome of female P. borealis from four geographic origins. Shrimp proteomes responded to ocean acidification, but not to warming, with marked origin-specific differences. Comparing the most favourable condition (2 °C, pH 7.75) to low pH (7.35) across tested temperatures, we detected 109 differentially abundant proteins (DAPs) in shrimp from the Saint Lawrence Estuary (SLE), six in those from the Northeast Newfoundland Coast (NNC) and Eastern Scotian Shelf (ESS), and three in the Esquiman Channel (EC). SLE shrimp showed widespread downregulation across metabolic, genetic information processing, and signalling pathways, suggesting higher sensitivity to acidification relative to other origins, where responses were muted. These findings highlight intraspecific variation in proteomic responses to ocean acidification in this commercially valuable crustacean. They confirm ocean acidification as a major concern in the context of rapid environmental change and suggest that uniform conservation strategies may be ineffective. Instead, management efforts should account for origin-specific sensitivities, reflecting the complex adaptive landscape shaping the resilience of P. borealis and other exploited marine species.

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Explainable machine learning models for coastal pH forecasting at aquaculture-relevant thresholds in Eastern Canada

Published 19 January 2026 Science Leave a Comment
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Highlights

  • Benchmark of ML models for coastal pHSWS forecasting.
  • Models trained on rare high-frequency data from Eastern Canada.
  • XGBoost balances sensitivity and precision at pHSWS < 7.75
  • SHAP shows Julian day dominance as composite environmental driver.
  • Promising low-cost framework for aquaculture acidification early warning.

Abstract

Ocean acidification poses a growing threat to marine ecosystems and aquaculture productivity, particularly in under-monitored coastal regions such as Eastern Canada. Existing pH prediction frameworks typically rely on multi-year records combining extensive carbonate chemistry, physical, and biological parameters. While these models can achieve high accuracy, their data requirements make them costly, complex, and challenging to implement for local, site-specific acidification forecasting in aquaculture contexts. To address this limitation, this study benchmarks several machine learning models for coastal pHSWS prediction using only three routinely measured environmental variables (temperature, salinity, sea level), from which we derived moving-average descriptors, local gradients, and two temporal indicators, resulting in a compact set of 11 input features. Six different models and a multivariate linear regression baseline were trained on one of the most complete and extended high-frequency datasets available (BSSS2018) and evaluated across four independent datasets: one from the same site but six months earlier (BSSS2017), and three from nearby bays in northeastern New Brunswick collected between 2017 and 2019. Among all tested models, XGBoost emerged as the most reliable and interpretable, achieving the best trade-off between sensitivity and precision at the operational acidification threshold (pHSWS < 7.75). Its performance remained acceptable within-site but declined across bays due to environmental and seasonal discrepancies, underscoring the importance of training data representativeness. SHAP-based explainability confirmed that Julian day was the dominant predictor, integrating the composite effects of seasonal environmental variability. Overall, this study demonstrates that using only low-cost, routinely measured features provides a promising foundation for short-term coastal pH forecasting, particularly for aquaculture monitoring needs. Despite limited inter-bay generalization, the proposed framework shows that interpretable machine learning models can deliver actionable early-warning insights under realistic data constraints. It constitutes one of the first data-driven benchmarks explicitly tested at aquaculture-relevant thresholds, highlighting a scalable and transparent approach toward operational acidification forecasting.

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An indoor mesocosm system for cost-effective simulation of multiple ocean stressors affecting marine organisms

Published 16 January 2026 Science Leave a Comment
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Global climate change is exacerbating multiple ocean stressors, including ocean acidification (OA), ocean warming (OW), and deoxygenation (deOxy), which collectively threaten marine ecosystems and fisheries. Understanding how these stressors interact to shape organismal and ecosystem responses is increasingly critical, yet it remains technically challenging and expensive to simulate them concurrently under controlled indoor conditions. To address this limitation, we developed a closed indoor mesocosm system that enables stable and long-term simulation of these three stressors for biological and aquaculture research. The system maintains consistent levels of CO2, temperature, and dissolved oxygen (DO) over multi-month experiments without automated control units, relying instead on robust initial settings. High-purity CO2 and N2 gases are blended with ambient air in controlled ratios to regulate carbonate chemistry and oxygen levels, while chillers and heaters ensure precise temperature control. Validation experiments demonstrated that the system can (1) increase pCO2 to approximately twice the present-day level with a pH reduction of ~ 0.22 units, (2) elevate temperature by + 3 °C above ambient temperature, and (3) reduce DO by up to 40% relative to ambient concentration, reflecting projected climate scenarios. This simple and versatile mesocosm provides a practical platform for investigating the ecophysiological responses of marine organisms under multi-stressor environments, supporting research on climate adaptation and aquaculture resilience.

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Pier2Peer alumni showcase webinar

Published 16 January 2026 Events Leave a Comment

Date: January 23, 2026
Time: 7:00 – 8:30 AM ET // 12:00 -13:30 UTC
Location: Virtual

Register

Join us for a webinar showcasing research from Pier2Peer Alumni on Friday, 23 January 2026 from 12:00- 1:30 pm UTC. In this webinar, we’ll be joined by two Pier2Peer Scholarship recipients to learn about their research and mentorship experiences.

Dr. M. Anand will be presenting “ARMS (Autonomous Reef Monitoring Structures) – an emerging tool to monitor ocean acidification and coral reef health”. Dr. M. Anand is an Associate Professor and Head in the Dept. of Marine and Coastal Studies, School of Energy, Environment and Natural Resources, Madurai Kamaraj University, Tamil Nadu, India. During his participation in Pier2Peer, he was mentored by Dr. Aileen Tan Shau Hwai and received the 2023 Pier2Peer Scholarship.

Dr. Georgina D. Cepeda will be presenting “Planktonic calcifiers under pressure: implementation and results from ocean acidification training in the SW Atlantic Ocean”. Dr. Cepeda is a researcher at Instituto de Investigaciones Marinas y Costeras (IIMyC), CONICET-Universidad Nacional de Mar del Plata, Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), Mar del Plata, Argentina. During her tenure with Pier2Peer, Dr. Cepeda was mentored by Dr. Nina Bednarsek and received the 2025 Pier2Peer Scholarship. 

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Integrated biochemical profiling, comparative transcriptome and weighted gene co-expression network analysis to explore the response mechanism of global warming and ocean acidification to the stress of Sepia esculenta larvae

Published 16 January 2026 Science Leave a Comment
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Highlights

  • Multi-angle analysis of Sepia esculenta under global warming and ocean acidification.
  • Stress enhanced the immune defense and antioxidant defense of S.esculenta.
  • The hub genes closely related to stress resistance were identified and screened out.
  • Provided a theoretical basis for the breeding of fine varieties and pond culture.

Abstract

The Sepia esculenta has high economic value and nutritional value, and accounts for a high proportion of the catch of cephalopods in China ‘s coastal waters. Global warming and ocean acidification, as major environmental problems currently facing the world, have a serious negative influence on the survival and breeding of S. esculenta. Therefore, in the research, transcriptome sequencing and biochemical quantitative analysis were performed on the larvae of S. esculenta after high temperature, low pH and combined stress at different time points, and the differential expressed genes (DEGs) and response mechanisms were identified. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that these DEGs were mainly involved in a large number of immune-related biological processes and signaling pathways, including Immune response、Phagocytosis、Regulation of DNA-templated transcription and Positive regulation of DNA-templated transcription. Then, we further explored the functional relationship between these DEGs by constructing weighted gene co-expression network and protein-protein interaction networks. We identified ten hub genes including HSP90AA1, ALDH1L1, VPS13A, MAPK8IP1 and KDM6A. These hub genes may play an important role in the face of high temperature, low pH and their combined stress at different times. Our findings not only elucidate the molecular response mechanisms of S. esculenta to environmental stress and delineate the key regulatory pathways underlying its adaptation, but also provide a theoretical foundation for advancing pond cultivation.

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New link: register for Pier2Peer webinar – 23 January

Published 16 January 2026 Events Leave a Comment
Register for the Pier2Peer Alumni Webinar! Join us for a webinar showcasing research from Pier2Peer Alumni on Friday, 23 January 2026 from 12:00- 1:30 pm UTC. In this webinar, we’ll be joined by two Pier2Peer Scholarship recipients to learn about their research  experiences.
 
Register Now
  Speakers Dr. M. Anand will be presenting “ARMS (Autonomous Reef Monitoring Structures) – an emerging tool to monitor ocean acidification and coral reef health”. Dr. M. Anand is an Associate Professor and Head in the Dept. of Marine and Coastal Studies, School of Energy, Environment and Natural Resources, Madurai Kamaraj University, Tamil Nadu, India. During his participation in Pier2Peer, he was mentored by Dr. Aileen Tan Shau Hwai and received the 2023 Pier2Peer Scholarship.
  Dr. Georgina D. Cepeda will be presenting “Planktonic calcifiers under pressure: implementation and results from ocean acidification training in the SW Atlantic Ocean”. Dr. Cepeda is a researcher at Instituto de Investigaciones Marinas y Costeras (IIMyC), CONICET-Universidad Nacional de Mar del Plata, Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), Mar del Plata, Argentina. During her tenure with Pier2Peer, Dr. Cepeda was mentored by Dr. Nina Bednarsek and received the 2025 Pier2Peer Scholarship. 
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Interannual variability of oceanic pH in a highly human-perturbed bay in China

Published 15 January 2026 Science Leave a Comment
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Due to anthropogenic carbon dioxide (CO2) emissions, open oceans are acidifying, and the acidification rate is relatively stable. While coastal waters experience even greater pH fluctuations from terrestrial inputs, upwelling, and biological activity, this variability necessitates detailed long-term research in these regions. Based on field observations and historical literature data from 1980 to 2016, the interannual variability of seawater pH and its driving mechanisms were analyzed in Jiaozhou Bay, a highly human-perturbed bay in China. The results revealed an overall decreasing trend in pH over the three-decade period, with a decline rate of 0.0062 years−1, which is 3.6 times faster than that observed in the open ocean, indicating significant anthropogenic impacts on pH variations in Jiaozhou Bay. The long-term pH changes showed strong correlations with coastal environmental pollution status, characterized by three distinct phases: a decline from 1980 to 1986, followed by an increase during 1991 to 2004, and subsequently another decreasing trend from 2004 to 2016. Terrestrial (including wastewater) inputs were identified as predominant anthropogenic factors influencing these pH variations. Furthermore, this study highlights that while future management should focus on reducing organic matter and nutrient inputs, particular attention should be paid to the direct impacts of dissolved inorganic carbon (DIC) from treated wastewater discharge on pH reduction.

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Ocean acidification threatening world’s shellfish (video)

Published 15 January 2026 Media coverage Leave a Comment
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Ocean acidification and anthropogenic carbon in the Eastern Mediterranean Sea and the effects of acidification on marine organisms

Published 15 January 2026 Science Leave a Comment
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Ocean acidification (OA), driven by rising atmospheric carbon dioxide (CO2) levels, is a critical issue affecting our oceans. The Eastern Mediterranean Sea (EMS) remains poorly understood in terms of the carbonate system and the impact of OA, despite its key role in Levantine Intermediate Water (LIW) formation and its peculiar characteristics in buffering capacity and ongoing OA. This study provides the first comprehensive spatial and temporal assessment of carbonate system in the North-Eastern Levantine Basin, in EMS, providing essential reference data for Total Alkalinity (TA), Dissolved Inorganic Carbon (DIC), and Anthropogenic Carbon (CANT). The mean TA of the measurements was 2622.11 μmol/kg, with higher surface values in summer, reflected also in the surface salinity (S) maximum caused by strong evaporation. A clear vertical gradient was observed, with TA decreasing with depth. Hot and dry meteorological conditions contribute to increased S and TA, resulting in seasonal and vertical variations in the water column. The mean DIC of the measurements was 2291.23 μmol/kg. In contrast to the observations for TA, surface DIC values were higher in winter than in summer. The higher DIC values in winter are attributed to thermodynamic equilibrium and vertical mixing in the surface waters. This study has also investigates the presence of CANT, has infiltrated deep layers, with a mean concentration of 52.07 μmol/kg, decreasing significantly throughout the water column. These findings confirms the ongoing influence of human activities on intermediate and deep layers in EMS. To reconstruct past carbonate system dynamics, the relationships of TA and DIC were determined with salinity (S) and temperature (T) data. Long-term data from METU-IMS Erdemli Time Series (ETS) stations, collected monthly for a decade, provided valuable findings into seasonal patterns and temporal shifts in TA, DIC, and pH. The coastal station displayed clear trends in the carbonate system over time, reflecting its sensitivity to local environmental changes. In contrast, the offshore station exhibited minimal variability, indicating greater stability against seasonal and long-term fluctuations. These results highlight the heightened vulnerability of coastal waters to carbonate system changes, while offshore waters remain more stable. Understanding carbonate chemistry and acidification levels is crucial for assessing impacts on marine life. In addition to the characterization of carbonate chemistry, this study also explores OA’s biological impacts on two key organisms of the Mediterranean ecosystem: phytoplankton and mussels. Firstly, effects of elevated CO₂ on phytoplankton, an essential primary producer in aquatic food webs and global biogeochemical cycles are explored. Specifically, the study explores the impacts on phytoplankton physiology, focusing on growth rates, respiration, and photopigment content in selected species from the coccolithophores, dinoflagellates, and diatoms groups. While growth rates and respiration remained relatively stable under reduced pH conditions, photopigment content was significantly influenced by changes in seawater pH, highlighting the importance of considering environmental influences on photopigment composition. The study further investigated the effects of acidification on calcifying organisms through a global program aimed at understanding the long-term effects of acidification on key seafood species and exploring adaptation strategies with a collaborative approach. This study focused on the long-term (6 months long experiment) physiological impacts of OA on marine calcifiers, specifically Mediterranean mussel, Mytilus galloprovincialis, an abundant species and one of the most consumed non-fish marine species in Türkiye. Results indicate that OA poses a substantial threat to mussel health and survival. Reduced pH levels negatively impacted survival rates, while other physiological parameters like clearance rate, condition index, respiration, and the distribution of a radionuclide, 210Po, did not significantly change. However, lipid content and immune response were affected. Oxygen consumption decreased over time, especially at lower pH. This study underscores the potential risks of OA to the fitness of the commercially important mussel species, indicating that future OA may impact both this key seafood species and its associated ecosystems. The established baseline data are crucial for future monitoring and provide valuable insights into the vulnerability of marine organisms and ecosystems to ongoing OA. By integrating chemical, biological, and ecological perspectives, this dissertation offers a comprehensive assessment of OA in EMS. It establishes baseline data for carbonate system variables, revealing distinct spatial and temporal variations influenced by S, T, and mixing processes. By linking changes in carbonate chemistry to physiological responses in primary producers and a commercially vital shellfish species, this study highlights the ecological and economic impacts of OA in EMS. The findings emphasize the need for continued research and mitigation efforts to protect marine ecosystems and commercially important species. This integrated approach provides valuable insights into the vulnerability of marine organisms and ecosystems to ongoing OA, underscoring the significance of this research for the Mediterranean Sea.

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Time series in the Mediterranean Sea

Published 15 January 2026 Web sites and blogs Leave a Comment
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13 January 2026/Kiel/Limassol. Today, Expedition M216 set sail for the Mediterranean Sea with the research vessel METEOR. An international research team led by GEOMAR Helmholtz Centre for Ocean Research will assess the state of the Mediterranean over the coming weeks. The research is conducted as part of a time series that was last carried out in 2018. The data collected now are therefore central to assessing current and future changes in the Mediterranean Sea. Among other things, temperature, salinity, nutrients and trace gases are being investigated, as well as the stratification and circulation of the water masses.

Like the Baltic Sea and the Black Sea, the Mediterranean Sea is an inland sea connected to the global ocean only by the Strait of Gibraltar. As a result, it responds more quickly to changes. It warms more rapidly, absorbs more carbon dioxide and acidifies more strongly than the open ocean. At the same time, through its connection with the Atlantic, the Mediterranean Sea also influences the global ocean and additionally plays an important role for the regional climate, fisheries and tourism.

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Several factors come together in the Mediterranean Sea: it has a very high salinity and pronounced water circulation. The high salt concentration and temperature promotes the uptake of anthropogenic CO2. At the same time, surface water is transported relatively quickly to the depth, where it remains at a temperature of around 12 to 13°C. In addition, the circulation ensures that deep water reaches the surface, which can again absorb CO2. This creates a dynamic cycle that enables the Mediterranean Sea to bind a comparatively large amount of CO2 from the atmosphere,” explains Dr Toste Tanhua, expedition leader and chemical oceanographer at GEOMAR.

Measurements from the surface to the sea floor

The measurements cover the entire water column, i. e. all layers of the Mediterranean Sea from the surface to the sea floor. At its deepest point, the Mediterranean Sea is over five thousand metres deep. “The unique topography of the Mediterranean Sea is challenging for us. There are several basins with different conditions and water depths,” says Toste Tanhua. The expedition focuses on measuring nutrients, salinity, oxygen, alkalinity, dissolved inorganic carbon, organic carbon, CO2 and the degree of ocean acidification. This enables the researchers to deduce how the Mediterranean Sea is faring under the influence of climate change and to estimate further changes. They are also investigating the distribution of water masses, currents and the exchange between surface water and the deep ocean.

“The Med-SHIP programme gives us the opportunity to take a very close look at the individual components of the entire water column. Among other things, we will be investigating inorganic carbon. This refers to carbon that is not found in living organisms, but in rocks, water or in the atmosphere as CO2. Among other things, it is responsible for transporting CO2 between the atmosphere, the surface and deep water. As the water masses in the Mediterranean are in contact with the atmosphere relatively frequent, this is particularly interesting for us,” explains Toste Tanhua.

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