Applications open: fourth winter school on ocean acidification and multiple stressors

Published 20 October 2026 Events Closed

Dates: 30 November – 11 December 2026

Location: IAEA Marine Environment Laboratories, Monaco.

Deadline for application through InTouch+ platform: 6 November 2026

The Winter School 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) and the Laboratoire d’Océanographie de Villefranche (LOV).

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 Fourth 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.

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.

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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 or invited organization, participants are requested to submit their application via the InTouch+ platform (https://intouchplus.iaea.org) to the competent national authority (Ministry of Foreign Affairs, Permanent Mission to the IAEA or National Atomic Energy Authority) or organization for onward transmission to the IAEA by 6 November 2026, following the registration procedure in InTouch+:

1. Access the InTouch+ platform (https://intouchplus.iaea.org):

  • Persons with an existing NUCLEUS account can sign in to the platform with their username and password;
  • Persons without an existing NUCLEUS account can register here.

2. Once signed in, prospective participants can use the InTouch+ platform to:

  • Complete or update their personal details under ‘Complete Profile’ and upload the relevant supporting documents;
  • Search for the relevant event under the ‘My Eligible Events’ tab;
  • Select the Member State or invited organization they want to represent from the drop-down menu entitled ‘Designating Authority’ (if an invited organization is not listed, please contact InTouchPlus.Contact-Point@iaea.org);
  • If applicable, indicate whether a paper is being submitted and complete the relevant information;
  • If applicable, indicate whether financial support is requested and complete the relevant information (this is not applicable to participants from invited organizations);
  • Based on the data input, the InTouch+ platform will automatically generate the Participation Form (Form A) and/or the Grant Application Form (Form C);
  • Submit their application.

Once submitted through the InTouch+ platform, the application, together with the auto-generated form(s), will be transmitted automatically to the required authority for approval. If approved, the application, together with the applicable form(s), will automatically be sent to the IAEA through the online platform.

NOTE: The application for financial support should be made, together with the submission of the application, by 6 November 2026.

For additional information on how to apply for an event, please refer to the InTouch+ Help page. Any other issues or queries related to InTouch+ can be sent to InTouchPlus.Contact-Point@iaea.org.

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 with the R software 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

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Trace metals in the coral holobiont: roles and regulation in a changing ocean

Published 3 November 2026 Science Leave a Comment
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Trace metals are key regulators of coral reef functioning, acting as essential micronutrients or toxic stressors depending on concentration, speciation, and biological regulation. Corals and their associated holobionts require metals such as iron, zinc, copper, manganese, cobalt, molybdenum, and vanadium for photosynthesis, antioxidant defense, calcification, and nutrient cycling, while elevated levels of these elements, and non-essential metals including cadmium, lead, mercury, and nickel can induce oxidative stress, disrupt metabolism, disrupt coral-algal symbiosis, and contribute to bleaching and mortality. This review synthesizes current knowledge on trace metals in corals using evidence from laboratory experiments, field studies, skeletal geochemistry, and omics-based investigations. The biological roles and regulation of trace metals within the coral holobiont, their physiological and molecular impacts across life stages, and the influence of biogeochemical cycling and environmental drivers on metal availability and exposure in reef systems are examined. Analytical and omics-based approaches for investigating coral and metal interactions are also evaluated. Altogether, current evidence indicates that coral responses to trace metals depend on external metal concentrations, physiological regulation and environmental context. As climate change and anthropogenic activities continue to modify ocean chemistry, redox conditions, and metal bioavailability, understanding these interactions will become increasingly important for anticipating coral responses to future environmental change. Substantial knowledge gaps remain regarding thresholds between essentiality and toxicity, interactions with climate stressors, and holobiont-level metal cycling. Addressing these gaps is essential for improving interpretation of coral metal records, predicting reef vulnerability, and informing effective conservation and management strategies in an increasingly anthropogenically altered ocean.

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Community metabolism generates chemical legacies that alter coral physiology

Published 3 November 2026 Science Leave a Comment
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Coral reefs are among the world’s most diverse ecosystems and contribute substantially to ocean productivity and the carbon budget. Disturbances are shifting reefs to altered community states, yet how these new communities indirectly alter organismal physiology by modifying the local biogeochemical environment remains largely unknown. We investigated this biogeochemical feedback in a 25-d mesocosm experiment in Mo’orea, French Polynesia. We exposed the common coral Porites rus to the biogeochemical environments generated by three distinct communities representative of recent benthic states in this system: coral-, macroalgae-, and crustose coralline algae-enriched relative to a seawater-only control. While net community production was similar among communities, net community calcification was lowest in the macroalgae-enriched state. Across treatments, community metabolism drove changes in the organic and inorganic carbon pool, with net community production increasing both pH and dissolved organic carbon. Using structural equation modeling, we tested how these community-generated chemical legacies propagated through coral physiology. Elevated pH increased chlorophyll a content, which increased endosymbiont density, tissue biomass, gross photosynthesis, and respiration through a series of indirect pathways. Dissolved organic carbon had no detectable effect on downstream corals at 25 d. These results reveal a mechanistic pathway linking disturbance-driven shifts in benthic communities to coral performance. Altered community metabolism modifies local carbon chemistry, which reshapes symbiont physiology and ultimately influences host metabolic function. By identifying the pathways through which community states engineer their chemical environment, this study provides a framework for predicting coral performance and ecosystem trajectories as reefs transition away from coral-enriched states.

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Assessment of sediment and water regimes in island ecosystems of the Gulf of Mannar: implications for ecological monitoring

Published 3 November 2026 Uncategorized Leave a Comment
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Island ecosystems are highly dynamic, and this study examined sediment and water regimes across four coral islands in the Gulf of Mannar to evaluate their ecological significance. Sediment and water samples were collected from four islands, with sediment analyses covering grain size, calcium carbonate (CaCO₃), organic carbon, organic matter, and key water parameters: pH, salinity, temperature, conductivity, dissolved oxygen (DO), turbidity, and total dissolved solids (TDS). Standardized protocols ensured consistency, and data analysis (ANOVA, correlation, regression, Principal Component Analysis (PCA)) was used to assess spatial variability and interrelationships. Sediment composition varied significantly (p< 0.05) in terms of sand, silt, clay, calcium carbonate, organic carbon, and organic matter, with regression analysis revealing a positive trend for silt and negative trends for the other components. PCA (KMO = 0.402; Bartlett’s p< 0.0001) revealed two principal components explaining 87.05% of total variance, with Component 1 linked to sand, organic carbon, and organic matter, and Component 2 to silt, clay, calcium carbonate, and organic matter. Water parameters also varied significantly (p< 0.05); conductivity (r = 0.369) and temperature (r = 0.302) correlated with island location, while temperature was strongly associated with conductivity (r = 0.478) and TDS (r = 0.405). PCA (Kaiser-Meyer-Olkin (KMO) = 0.563; Bartlett’s p< 0.0001) identified ionic strength and thermal regime as key environmental drivers. These findings establish critical baseline data, offering a robust framework that demonstrates how sedimentary composition and physicochemical parameters jointly regulate benthic-pelagic interactions and ecosystem resilience. Overall, island-specific sediment and water patterns exert strong control on ecological processes, providing early detection of environmental shifts and strengthening evidence-based adaptive management. The study offers valuable insights for ecological monitoring and conservation within the Gulf of Mannar region.

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Coupled increases in pelagic fish productivity and export productivity during the Paleocene-Eocene Thermal Maximum

Published 3 November 2026 Science Leave a Comment
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Ocean productivity is sensitive to climate change, and its decline in recent decades has profoundly impacted the biosphere. Yet its long-term trajectory under global warming remains a topic lacking consensus. To address this question, we use paired ichthyolith and marine barite accumulation rates to investigate marine productivity and associated biological responses during the Paleocene-Eocene Thermal Maximum. We find a widespread increase in pelagic fish productivity, particularly in the Pacific and North Atlantic, that closely tracks export productivity in trend and spatial pattern, suggesting this increase was fueled by enhanced carbon export from the surface ocean. Model simulations support the observed trend, demonstrating that under elevated pCO2 conditions, the effects of enhanced nutrient supply can outweigh the suppressive effects of ocean stratification on export productivity. Our findings highlight that the long-term response of marine productivity to sustained greenhouse warming may differ fundamentally from the short-term declines observed in the modern ocean.

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Time-variant bioeconomic risks on a gastropod fishery affected by uncertain ocean acidification trajectories

Published 3 November 2026 Science Leave a Comment
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Introduction: In the north-eastern Pacific, high-value abalone fisheries, which are sensitive to pH variations, require in situ pH data to properly assess the bioeconomic effects of their possible dynamic trajectories under alternative fishing mortalities.

Methods: In situ pH data were collected every 15 min using a HOBO® MX2501 sensor in the La Bocana pink abalone fishing grounds and compared them with Argo float and Copernicus Marine Service observations. The observed pH distribution was fitted to the Extreme Value Minimum distribution based on the Anderson–Darling goodness-of-fit statistic. Stochastic pH trajectories were generated through 10,000 Monte Carlo replications under three IPCC ocean acidification scenarios (SSP1-2.6, SSP2-4.5, and SSP5-8.5) and three fishing mortalities (FD = 0.02, 0.04, and 0.06). These trajectories were incorporated into a dynamic age-structured bioeconomic model by making individual growth and age-specific natural mortality functions dependent on pH. Biomass and resource rent per boat were projected from 2025 to 2100, and linear mixed-effects models, sensitivity analyses, and 95% confidence intervals were used to evaluate temporal responses and parameter uncertainty. Dynamic risks were estimated as the probability that biomass and resource rent fell below their respective limit reference points (LRPs: 190 t and USD 15,000 yr-1) across scenarios and fishing mortalities.

Results: The results indicate considerable variability in pH measurements between remote and in situ sources, which may introduce a proportional bias into the bioeconomic modeling if local observations are absent. Also, the effects of ocean acidification on H. corrugata biomass, survival, and fishery resource rent increase with time, IPCC pH scenario, and alternative exploitation intensity. Under the current exploitation rate (FMSY = 0.06), effects were negligible in the short term under SSP1-2.6, whereas by 2100 pH-related growth effects decreased by 4%, 13%, and 26% under SSP1-2.6, SSP2-4.5, and SSP5-8.5, respectively. Over the same period, pH effects on survival rates resulted in a slight increase of 2.14% under SSP1-2.6, but reductions of 6.48% and 22% under SSP2-4.5 and SSP5-8.5, respectively, while age-specific biomass peaks declined by up to 20% and 44% under SSP2-4.5 and SSP5-8.5. Mixed-effects models confirmed significant effects of pH scenario, exploitation rate, and time on biomass and resource rent, including significant interactions (all p < 0.001). By 2100, annual resource rent per small-scale boat was significantly higher under SSP1-2.6 than under SSP2-4.5 and SSP5-8.5 by USD 3,083 and USD 7,482, respectively (p < 0.0001). Under FMSY, the risk of biomass falling below its LRP was <25% during 2025–2040 but increased to 34% and 54% under SSP2-4.5 and SSP5-8.5, respectively, by 2100; corresponding risks for resource rent increased to 27% and 48%.

Discussion: These results indicate that ocean acidification may substantially increase the long-term bioeconomic vulnerability of the fishery, particularly under high-emission scenarios. Management actions to mitigate the undesired bioeconomic effects of OA will likely depend on the fishery authority’s risk attitude (i.e., degree of risk aversion) and corresponding exploitation-rate strategy selection.

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Unlocking spatial ecological assessment for tropical seagrass habitats using a new rapid assessment method (SEARAM)

Published 3 November 2026 Science Leave a Comment
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Highlights

  • Rapid and standardized assessment of tropical seagrass ecological state.
  • Multimetric index combining structure and vitality indicators.
  • Spatial mapping of seagrass fragmentation and degradation.
  • Links between habitat condition, environment, and megafauna.
  • A practical tool for coastal monitoring and impact mitigation.

Abstract

Seagrass meadows are key coastal ecosystems supporting biodiversity, carbon storage, and essential trophic functions, yet they are increasingly threatened by anthropogenic and climatic pressures. Based on the Seagrass Meadows Rapid Assessment Method (SEARAM), a standardized protocol grounded in seagrass biodiversity indicators (SBIs), we developed a reliable and operational index to assess seagrass ecological state at high spatial resolution. Using 536 circular plots and 144 faunal stations across three intertidal reef habitats in Mayotte (Western Indian Ocean), SEARAM integrates structural and vitality sub-indices into a composite seagrass ecological state index (SESI), spatialized by geostatistical interpolation and analyzed using ANOVA, PCA, and multiple regression models. Results revealed highly fragmented meadows dominated by Halodule uninervis and Halophila ovalis, with low canopy height (5 ± 2 cm) and substantial epiphyte loads (37 ± 17%). The inner fringing reef flat showed the poorest ecological state (SESI = 4.8 ± 0.7/10), whereas the barrier reef (5.4 ± 0.8/10) and exposed fringing reef flat (5.6 ± 0.8/10) exhibited moderate scores. Key environmental drivers (turbidity, grain size, pH), significantly explained spatial patterns of seagrass structure and vitality, confirming the influence of sediment and light regimes. Functional relationships were also demonstrated between seagrass condition and associated fauna, particularly green turtle density and dugong feeding traces. SEARAM proved to be a rapid and robust tool for diagnosing tropical seagrass states. Its multimetric framework connects benthic condition to habitat suitability for megafauna, offering an operational foundation for ecological monitoring, management, and impact mitigation within the Avoid–Reduce–Offset (ARO) doctrine.

Graphical abstract

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Climate-driven habitat loss of Chinese sturgeon in the Northwestern Pacific and implications for marine protected area design

Published 3 November 2026 Science Leave a Comment
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Highlights

  • Ensemble modeling integrates eleven algorithms to predict sturgeon habitat suitability.
  • Temperature is the dominant driver, followed by pH and total suspended matter.
  • Suitable habitats are projected to disappear completely by 2100 under SSP5–8.5.
  • Static protected areas must transition to climate-adaptive zoning strategies.

Abstract

The conservation of endangered anadromous fishes depends on understanding their full-lifecycle habitat requirements, yet the marine phase of Chinese sturgeon (Acipenser sinensis) remains a critical knowledge gap despite over 90% of its lifespan occurring at sea. We integrated multi-source occurrence data (satellite tagging, bycatch records, environmental DNA, and online databases) and applied an ensemble modeling framework (Biomod2 with eleven algorithms) to predict habitat suitability across the Northwestern Pacific Ocean (100°E–150°E, 10°N–55°N). After collinearity filtering, seven key environmental drivers were retained, among which mean temperature contributed most, followed by maximum pH, total suspended matter and mean silicate. The ensemble model achieved high predictive performance (median TSS = 0.944) and identified the Changjiang Estuary and coastal waters of Zhejiang and Jiangsu provinces as current distribution hotspots. Under the high-emission scenario (SSP5–8.5), suitable habitats are projected to disappear completely by 2100, accompanied by a significant northward contraction. These projections should be regarded as a potential worst-case scenario under high-emission conditions rather than a deterministic forecast. These findings demonstrate that business-as-usual emissions would eliminate viable marine habitat for this critically endangered species. Conservation priorities should therefore focus on (1) protecting benthic prey resources in the Changjiang Estuary and Zhoushan Archipelago as core refugia, and (2) transitioning from static marine protected areas to dynamic, climate-adaptive zoning informed by real-time habitat predictions. The ensemble modeling approach developed here is transferable to other data-limited, endangered marine species facing similar climate threats.

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Long-term stress induced by low bicarbonate alkalinity causes intestinal oxidative stress, gut microbiota imbalance and metabolic disorder in Scylla paramamosain

Published 3 November 2026 Science Leave a Comment
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Highlights

  • Low bicarbonate induces acid-base imbalance and oxidative stress
  • Opportunistic pathogen Klebsiella is a potential biomarker of the LB group.
  • Low bicarbonate affects chitin synthesis and gut barrier.
  • Low bicarbonate affects NDAA and gut microbiota.

Abstract

To investigate the effects of low bicarbonate alkalinity on intestinal health of Scylla paramamosain, we systematically evaluated the growth survival, intestinal antioxidant enzyme activities, and expression profiles of genes involved in immunity, inflammation, apoptosis and osmoregulation under low alkalinity conditions. Meanwhile, integrated intestinal microbiome and metabolome analyses were performed. The results showed that low bicarbonate alkalinity significantly reduced the survival and molting rates of S. paramamosain. It markedly elevated the activities of intestinal SOD, CAT and GSH-Px, as well as the expression levels of inflammation-related genes (IL-16, RELISH, LITAF), apoptosis-related genes (CASPASE7, BAX, BCL2) and osmoregulation-related genes (NKA, NHE, Cl−/HCO₃−), while suppressing the expression of immune genes (proPO, ALF1, LZM) (P<0.05). Low bicarbonate alkalinity disrupted the intestinal microbiota structure of S. paramamosain, accompanied by a decreased abundance of the phylum Bacteroidota and a significant increase in the abundance of the genus Klebsiella (P<0.05). A total of 714 differential metabolites were identified by metabolomic analysis, which were mainly annotated into Fatty Acyls, Glycerophospholipids, and Steroids and steroid derivatives. Multiple carbohydrate metabolism pathways were significantly enriched and participated in the regulation of Fructose 6-Phosphate (F6P). Integrated microbiome-metabolome analysis revealed that N,N-dimethyl arachidonoyl amine (NDAA) may cooperate with intestinal microorganisms to regulate the stress tolerance of S. paramamosain under low bicarbonate alkalinity stress. Based on the physiological and biochemical characterization of the intestine, this study elucidated the adaptive characteristics of S. paramamosain under low bicarbonate alkalinity. The findings provide important theoretical basis and practical significance for the saline-alkaline aquaculture of S. paramamosain.

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Spat origin does not affect phenotypic plasticity in the farmed mussel Mytilus chilensis facing experimental acidification

Published 2 November 2026 Science Leave a Comment
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Phenotypic plasticity allows organisms to cope with environmental variability, yet its role in sustaining aquaculture systems in the face of global change stressors remains poorly understood. We conducted a 90-day mesocosm experiment to test whether spat origin influences morphological, physiological, and periostracum responses in the Chilean mussel Mytilus chilensis under sustained experimental acidified conditions. Juveniles were collected from two contrasting habitats: an estuarine and dynamic/fluctuating environment, strongly influenced by freshwater discharges, and a marine, more stable environment; and then exposed to two pH regimes (8.0 and 7.5). Morphological traits showed subtle origin effects: estuarine mussels tended to exhibit higher shell length and calcification rates, though origin × pH interactions were not significant. Physiological responses were largely similar between both seed sources, with metabolic rates remaining stable while the clearance rate increased under acidified conditions in both populations. Periostracum analyses revealed some non-significant variation in organic composition, but no consistent effects of the pH were detected. Together, these results suggest that M. chilensis relies on conservative metabolic maintenance combined with flexible clearance responses possibly to cope with natural acidification pulses, while also tolerating sustained low-pH conditions, with only weak signals of origin-driven divergence. Our findings highlight the importance of phenotypic adjustments over local origin, suggesting that spat provenance may not be a primary determinant of performance under projected acidification scenarios tested here.

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The Arabian Seas: a window into future oceans —physical, biogeochemical, and ecological dynamics in unique marginal environments

Published 2 November 2026 Science Leave a Comment
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The Arabian Sea provide a sentinel system for understanding how global planetary boundary transgressions manifest through regional ocean processes. Their rapid warming, altered circulation, declining ventilation, deoxygenation, acidification, and ecological reorganization reveal interconnected regional manifestations of pressures associated with the Climate Change, Biogeochemical Flows, Ocean Acidification, and Biosphere Integrity boundaries. Regional physical and biogeochemical amplification compresses the timescale over which these pressures become ecologically consequential, exposing regional responses and increasing risks of regime shifts. Although the Arabian Seas possess distinctive environmental characteristics, the mechanisms linking planetary forcing to regional change are broadly relevant to other tropical and marginal oceans. Their present trajectory therefore provides a conditional, mechanism-based analogue for selected processes expected to intensify across future tropical open-ocean and marginal-sea environments. This illustrates how multiple global boundary transgressions may interact to weaken regional resilience and reorganize marine ecosystem function.

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Critical swimming speed in fish: measurement, determinants, and applications in aquaculture and fisheries management

Published 2 November 2026 Science Leave a Comment
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Critical swimming speed (Ucrit) is widely used as a non-invasive and practical metric for quantifying swimming performance in fish. This review summarizes current advances in Ucrit research, focusing on measurement methods, environmental and biological determinants, and the underlying genetic and molecular mechanisms. We highlight key methodological developments, including step and ramp protocols, while addressing ongoing challenges such as the lack of standardized procedures and the limited comparability across studies. Environmental factors, including temperature, dissolved oxygen, salinity, and ocean acidification, strongly influence Ucrit, while intrinsic traits such as body size, sex, and physiological capacity further shape its variation. Recent studies have begun to uncover the genetic architecture of Ucrit, with evidence from heritability estimates, genome-wide association studies, and transcriptomic analyses pointing to a polygenic basis and a central role of energy metabolism and mitochondrial function. We further discuss the applications of Ucrit in aquaculture and fisheries management, including selective breeding, exercise training, fish passage design, and stock enhancement. Finally, we outline future research directions, emphasizing the need to establish standardized measurement frameworks, develop high-throughput phenotyping technologies integrated with artificial intelligence, and achieve multi-omics integration. Advancing these approaches will deepen our understanding of swimming performance and facilitate the development of more efficient and sustainable aquaculture, while promoting continued innovation in fisheries science.

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Green total factor productivity and ocean health: a global panel analysis of institutional, environmental and economic drivers

Published 2 November 2026 Science Leave a Comment
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The deterioration of ocean health has become a critical global challenge due to increasing pressures from economic activities, environmental degradation, and institutional weaknesses. This study examines the impacts of economic growth, capture fisheries production, greenhouse gas emissions, and government effectiveness on ocean health at the global level during the period 2012–2022, using the Ocean Health Index (OHI) as a multidimensional measure of marine sustainability. A quantitative research design based on panel data analysis is employed using secondary data collected from the Ocean Health Index database, the World Bank, and Our World in Data. Descriptive statistics, correlation analysis, panel unit root tests, multicollinearity diagnostics, and panel model specification tests are conducted, followed by fixed-effects estimation with country-clustered standard errors. An environmentally extended Solow-residual method is then employed to calculate the Green Total Factor Productivity (GTFP) growth and added to an extended model of ocean health. The results indicate that there is a positive and significant relationship between economic growth and ocean health, and a negative and significant relationship between government effectiveness and ocean health. Ocean health is statistically significant and negatively associated with the growth of GTFP, while both capture fisheries production and GHGs are statistically insignificant. The study demonstrates that ocean health is a multidimensional socio-ecological phenomenon shaped by the interaction of economic, environmental, institutional factors and productivity related aspects. These findings contribute to the literature by integrating economic, environmental, institutional and productivity related dimensions to provide a broader understanding of the factors associated with ocean health across countries.

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Adaptation to extreme environments: a review of Antarctic fish physiology

Published 2 November 2026 Science Leave a Comment
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Having evolved in the chronically cold and thermally stable waters of the Southern Ocean (SO) for millions of years, Antarctic fish possess a suite of physiological specializations that enable them to survive at temperatures near the freezing point of seawater. Adaptations include the evolution of antifreeze proteins, modifications of membrane composition, altered metabolic processes, unique mechanisms of oxygen transport and utilization, and distinctive cellular stress responses. This review synthesizes current knowledge of the physiological adaptations of Antarctic fish, focusing on the mechanisms that support survival in extreme cold environments. We examine adaptations related to cold tolerance, osmoregulation, metabolism, reproduction, sensory biology and oxygen transport and discuss the evolutionary processes that have shaped these traits. We further evaluate how ongoing climate-driven changes, including ocean warming, acidification and biological invasions, may affect Antarctic fish populations and ecosystems. Understanding the physiological foundations underlying Antarctic fish adaptation provides important insights into evolutionary responses to environmental extremes and provides a framework for predicting potential vulnerabilities of polar marine organisms in a rapidly changing world.

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Does the evolution of Indian Ocean acidification follow CMIP6 projections under a high-emission scenario?

Published 2 November 2026 Science Leave a Comment
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The Indian Ocean (IO) surface acidification is governed by pronounced regional variability that is inadequately resolved in coarse-resolution CMIP6 models. Here, we employ eddy-resolving, dynamically downscaled outputs from three CMIP6 Earth System Models under the high-emissions SSP5-8.5 scenario to project future changes in IO acidification, with the model ensemble selected to account for uncertainty in future projections. Eddy-resolving simulations improve representation of mesoscale-driven surface acidification variability by ∼5%–10% relative to CMIP6 models, particularly in coastal regions, while reducing inter-model spatio-temporal heterogeneity. The analysis indicates a relatively weaker mean increase in [H+] compared with CMIP6 projections. The downscaled models yield a dynamically consistent, improved representation of the seasonal cycle of [H+] compared to CMIP6 models, particularly in the northern IO. This facilitates a more robust assessment of future anthropogenically driven changes in [H+] amplitude, with the monthly composite amplitude projected to increase by ∼63%–83% during the far-future period (FF; 2071–2100) across the IO. However, in the Arabian Sea, the increase is ∼37% smaller than in CMIP6, whereas other regions exhibit largely comparable changes. This amplification is primarily driven by enhanced sensitivity of [H+] to surface temperature and dissolved inorganic carbon under warming and increased CO2 uptake. Consistent with these changes, acidification extremes intensify (∼26%–45%) and become more frequent (∼3–5 times higher) in FF. Notably, in coastal regions after 2070, anthropogenic acidification signals emerge later in the downscaled projections than in CMIP6. These results highlight the need for high-resolution projections to improve estimates of future IO acidification and its associated risks.

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Science in a Seashell: Periwinkles Littorina littorea

Published 2 November 2026 Art , Web sites and blogs Leave a Comment

Who are they?

The periwinkle is a marine gastropod that lives in the intertidal zone of temperate marine ecosystems. This zone corresponds to the part of the beach between high tide and low tide. It therefore usually lives close to the water’s surface, although it has, on very rare occasions, been observed at depths of up to 60 metres! Native to the north-eastern Atlantic coast, it is found along all the Atlantic coasts of the northern hemisphere. It is thought to have been introduced to the North American coast in the mid-19th century, although this hypothesis is still debated today 1,2. It thrives quite comfortably in areas where predation pressure remains low 2.

It plays an important role in the ecosystem. It is a herbivorous animal that feeds on green and brown algae as well as diatoms 3, which it grazes on using its radula (its mouth and teeth) as it moves along the seabed. In this way, it regulates the proliferation of these algae 4 and maintains a balance in their growth 5. It also helps to feed smaller organisms by breaking these algae down into smaller pieces (whilst contributing to the carbon cycle) 5.

The periwinkle is often dark in colour. Like many other gastropods, it has a muscular foot and most of its internal organs are housed within its shell. As an adult, it measures around 2.5 cm. Its main predators are crabs and starfish. It should not be confused with another gastropod: the turbinate monodont , Phorcus turbinatus.

Figure. Naturalistic illustration of periwinkles under different points of view

A clear vulnerability

Periwinkles are vulnerable to climate change and pollution, but also to parasites.

Firstly, their shells are made of calcium carbonate (CaCO₃), which is highly sensitive to acidification; this makes periwinkles, like many other marine organisms, vulnerable to Ocean acidification 8. Indeed, an acidic environment causes the calcium carbonate to dissolve.

It has been shown that periwinkles produce shells of varying thickness depending on the predation pressure to which they are exposed 9,10. For example, periwinkles living in the presence of crabs tend to produce significantly thicker shells (and larger ones 11) than those of periwinkles that do not encounter crabs 9. However, periwinkles exposed to lower pH levels (= more acidic water) produce a thinner shell, making them more vulnerable to predators 9. Ocean acidification therefore has a direct effect on periwinkles (and other marine organisms) but also an indirect effect via changes in metabolism and an increase in predation pressure 9.

Changes in temperature also have a considerable impact on periwinkle populations 12. Indeed, their tolerance to high temperatures varies depending on the rate at which the temperature rises and the season in which they were born, but they appear to suffer in all cases when temperatures exceed 28 °C 13. Embryonic development is possible between 5 °C and 23 °C, but below and above these temperatures, periwinkle populations do not develop properly 7. Temperature affects not only embryonic development but also its duration 7. Adults, too, suffer from changes to their environment caused by climate change. Rising CO₂ concentrations and temperatures have direct implications for their physiological processes. An increase in CO₂ concentration alone causes a 31 % reduction in the respiratory rate of periwinkles and, more generally, in their metabolism. When combined with temperature, effects are observed on growth, population dynamics and, ultimately, all ecosystem processes 14. Recent studies show that periwinkles have low resistance to extreme temperatures. They cease to cling to the substrate and enter a ‘heat coma’ from 31°C onwards (with the temperature increased by 1 °C every 5 minutes) 12. 50 % of individuals die after 330 minutes (5.5 hours) of exposure to 39 °C, 90 to 120 minutes at 40 °C, or 60 minutes at 41 °C 13. The indirect consequences of temperature changes, arising from alterations to the ecosystem (plants, predators, etc.) in which young periwinkles develop, must also be taken into account and constitute a significant impact.

As periwinkles live in the intertidal zone, they are significantly exposed to chemical and plastic pollution in their habitat, as well as to heavy metals; indeed, they are organisms that are sensitive to pollution in their ecosystem 15–17. High concentrations of silver have been found in their gills, kidneys and stomachs following exposure to water containing dissolved silver 16. Even at low concentrations, a large proportion (80%) of individuals are affected even more than 24 hours after exposure. Furthermore, the greater the exposure and the higher the concentrations, the less the periwinkles feed 15. Studies on plastics and microplastics show that 100 per cent of the periwinkles studied had ingested microplastics and had them present in their bodies 17. These plastics originate from human activities. They have been released into the environment (as waste or when synthetic fabrics and clothing are washed) before being carried to the ocean by rainfall and drainage systems.

Finally, periwinkles are regularly infected by parasites, particularly trematodes (worms). These parasites significantly reduce the periwinkles’ appetite, causing them to graze less on seaweed on the seabed, thereby altering the natural balance between seaweed and periwinkle populations 18.

They are now recognised as a species that is important to understand within the context of evolutionary ecology 19.

Continue reading ‘Science in a Seashell: Periwinkles Littorina littorea’

Putting a time scale on emerging climate change stressors: a vulnerability index for Atlantic Ocean marine ecosystem services

Published 2 November 2026 Science Leave a Comment
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Highlights

  • Climate stressor emergence is highly heterogeneous across the Atlantic.
  • Multi-stressor emergence before 2100 is projected for all Atlantic EEZs.
  • Vulnerability is driven by emerging climate stressors, amplified by a high sensitivity of habitats and communities, and a low adaptive capacity.
  • Lower vulnerability is partly driven by robust governance and infrastructure.
  • Adaptive responses must address socio-economic differences and variable exposure to stressors.

Abstract

Marine ecosystem services underpin human wellbeing and support resilient socio-ecological systems, yet existing vulnerability assessments remain fragmented, often focusing on isolated industries and overlooking the whole-system socio-ecological context. To bridge this gap, we develop a comprehensive Vulnerability Index to assess marine ecosystem service vulnerability to emerging climate stressors in the Atlantic. Using high-resolution ocean simulations and moving beyond traditional long-term projections, we employ the Time of Emergence metric to address actionable decision-making timescales (2–3 decades). We found that all Atlantic marine ecosystem services are projected to be exposed to multiple emerging stressors before 2100, though the sequence and the timing of emergence are highly heterogenous. Overall vulnerability is highest in tropical West Africa due to the early emergence of hypoxia and sea level rise extremes compound by low adaptive capacity. Additional hotspots are found in subpolar and polar regions driven by rapid sea ice retreat and the sensitivities of region-specific habitats alongside a high dependence on marine ecosystems. Coupled with socio-ecological data, we determined which services (provisioning, regulatory and cultural) are most sensitive to potential impacts in each EEZ. We anticipate this index to be a starting point to develop targeted vulnerability indices for specific ecosystem services and regions. Mitigative and adaptive efforts must be multi-scale and tailored to national and local contexts, addressing not only socio-economic differences but also variable climate stressors and their impacts. Uncertainties associated with time series data gaps and indicator aggregation, particularly for island and remote territories, highlight the need for targeted national adaptation.

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On the future strategy for dissolution kinetics of CaCO3 in seawater by the solution-oriented approach

Published 2 November 2026 Science Leave a Comment
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Highlights

  • A new strategy for the laboratory study of CaCO3 dissolution in seawater using the Solution oriented approach is proposed based on the mixed kinetics model.
  • A check-list is provided against which any new design of experiment choosing to adopt this new strategy, can be tested before implementation.

Abstract

While the distribution of undersaturation of CaCO3 in the oceans is broadly known by applying chemical equilibrium theory, there is an increasing need, especially with advancing Climate Change and acidification of the oceans, to know about CaCO3-dissolution kinetics in more mobile systems. Experiments conducted in the laboratory to mimic conditions in the oceans in these faster circumstances often operate at even higher overall velocities, and matching laboratory simulations to field conditions is once again, problematic. Added to this, it has been shown in the last few years that when heterogeneous chemical kinetics developed out of its homogeneous counterpart, essential kinetics rigor was not carried forward. The Solution-oriented approach has been developed to recover the lost rigor, and the mathematical modelling of an in-line sequence of, molecular and diffusion components, which rely upon rigorous chemical kinetics, accompanies these developments. This paper supports workers adopting this new approach by describing 9 major practical issues that should be built into future experiments intending to prove the modelling.

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Standard Operating Procedure – Calibration of measurement systems for total dissolved inorganic carbon in seawater

Published 2 November 2026 Science Leave a Comment
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Total dissolved inorganic carbon (DIC) is a fundamental variable for characterizing the marine carbonate system and quantifying key biogeochemical processes, including ocean acidification, carbon storage, air-sea CO2 fluxes, and monitoring, reporting, and verification for marine carbon dioxide removal. Although standardized guidelines exist (e.g., IOCCP Report No. 8, SOP 2), routine oceanographic practice frequently relies on single-point calibrations using seawater reference materials (RMs) near ~2000 µmol/kg. While this practice has significantly improved inter-laboratory comparability, it often lacks formal metrological traceability to the International System of Units (SI), fails to verify system response linearity across the full working range, and leaves major components of the measurement uncertainty budget unconstrained.
To address these metrological limitations, the International Association for the Physical Sciences of the Oceans Best Practice Study Group (IAPSO-BP-SG) on ‘Calibrating Measurements of Total Dissolved Inorganic Carbon in Seawater’ was established in late 2023. This IAPSO-BP-SG presents a updated Standard Operating Procedure (SOP) based on recent inter-laboratory comparison results. This SOP unifies calibration guidelines across diverse analytical architectures. The recommended framework is structured around four primary operational pillars:

  1. Daily single-point calibration and adjustment: Using a characterized seawater RM to adjust for daily slope drift and verify operational stability.
  2. Periodic linearity verification: Assessing system linearity over the entire working range (0–2500 µmol/kg) using a minimum of six sodium carbonate standard solutions or calibrated gas loops to evaluate baseline intercepts and prevent scaling errors.
  3. Repeatability quantification: Regularly determining system and method precision through replicate measurements under repeatable laboratory conditions.
  4. Metrological uncertainty evaluation: Constructing a robust uncertainty budget following the Guide to the Expression of Uncertainty in Measurement (GUM), propagating contributions from standard materials, repeatability, density conversions, and potential instrumental drift.
    Additionally, the SOP outlines detailed procedures for volumetric and gravimetric preparation of primary standard solutions under CO2-free conditions, along with guidelines for density corrections and uncertainty propagation. Implementing this SOP ensures SI-traceable, high-precision DIC data suitable for long-term oceanographic monitoring and global data repositories.
Continue reading ‘Standard Operating Procedure – Calibration of measurement systems for total dissolved inorganic carbon in seawater’

Tolerance measured at one developmental stage mispredicts climate resilience in an animal with a complex life cycle

Published 2 November 2026 Science Leave a Comment
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Forecasts of whether marine species can evolve fast enough to survive climate change rely largely on single-stage tolerance assays, tacitly assuming that tolerance measured at one developmental stage reflects adaptive capacity across the organism’s life cycle. We test this assumption in a common marine bivalve (Mercenaria mercenaria) and find that it fails in sign, not degree: larval and post-metamorphic tolerance to end-century ocean acidification are strongly negatively correlated (r = −0.53, 95% CI [−0.69, −0.33]) across family-level, pedigree-conditioned and animal model estimates, with pervasive rank reversals among the top performers of each stage. A multivariate analysis of the among-family covariance matrix G shows why: under acidification, 57% of the among-family variance collapses onto a single dominant axis that loads positively on every larval trait and negatively on every post-metamorphic trait, whereas under ambient conditions the same families show no cross-stage covariance at all. Acidification therefore does not merely depress performance—it reorganizes the genetic architecture into a cross-stage conflict. Under ramping RCP 8.5 forcing this conflict geometry dictates the direction—not merely the magnitude—of adaptation: only balanced multi-stage selection preserves family diversity, whereas single-stage selection systematically erodes the opposite axis. In complex life cycles, resilience is a geometric property of ontogeny that forecasts cannot compress into a single-stage without inverting the sign of the answer.

Continue reading ‘Tolerance measured at one developmental stage mispredicts climate resilience in an animal with a complex life cycle’

One life stage cannot predict climate resilience in clams

Published 2 November 2026 Web sites and blogs Leave a Comment

Forecasts of whether marine species can adapt quickly enough to survive climate change usually rest on tolerance assays performed at a single developmental stage, tacitly assuming that what holds for a larva also holds for a juvenile. A new study of the hard clam Mercenaria mercenaria shows that this assumption fails in sign, not merely in degree. Across family-level, pedigree-conditioned and animal model estimates, larval tolerance to end-century ocean acidification and post-metamorphic tolerance to the same conditions were strongly negatively correlated, with a coefficient of r = −0.53 (95% CI [−0.69, −0.33]). Families whose larvae performed best under acidified seawater tended to produce the worst-performing juveniles after metamorphosis, and the top performers of each stage showed pervasive rank reversals.

A multivariate analysis of the among-family covariance matrix G reveals the mechanism behind this reversal. Under acidification, 57% of the among-family variance collapsed onto a single dominant axis that loaded positively on every larval trait and negatively on every post-metamorphic trait. Under ambient conditions, the same families showed no cross-stage covariance at all. In other words, acidification does not simply depress performance uniformly across the life cycle; it reorganizes the genetic architecture into a conflict between stages, so that genetic variation that benefits one stage actively works against the other.

The consequences for adaptation were explored under ramping RCP 8.5 forcing scenarios. In these simulations, the geometry of the cross-stage conflict dictated the direction, not merely the magnitude, of evolutionary change. Selection applied at a single stage systematically eroded the opposing axis of variation, whereas only balanced multi-stage selection preserved family diversity across the life cycle. Single-stage breeding or screening programs could therefore quietly eliminate the very genetic variation that later stages would need under continued acidification.

The authors conclude that, in organisms with complex life cycles, climate resilience is a geometric property of ontogeny that cannot be compressed into a single-stage measurement without inverting the sign of the answer. The findings are specific to one marine bivalve species and to family-level estimates of tolerance, and the covariance structure was characterized under experimental acidification conditions rather than observed across natural populations over time. Even so, the result cautions that adaptive capacity measured at one developmental stage may mispredict resilience in any species whose larval and adult forms face different physiological constraints.

Subject of Research: Evolutionary genetics of ocean acidification tolerance across life stages in a marine bivalve

Article Title: Tolerance measured at one developmental stage mispredicts climate resilience in an animal with a complex life cycle (https://doi.org/10.1371/journal.pbio.3004079)

Continue reading ‘One life stage cannot predict climate resilience in clams’

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