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

Published 20 October 2026 Events Leave a Comment

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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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.

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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.
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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.

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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)

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Lagrangian drifter measurements of the effects of seaweed cultivation on seawater carbon chemistry on a nearshore coral reef in Okinawa, Japan

Published 30 October 2026 Science Leave a Comment
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Ocean acidification (OA) and deoxygenation (collectively OAD) increasingly threaten coral reefs, which support marine biodiversity and human economic activity. Seaweed farms have been proposed to locally mitigate OAD conditions by removing dissolved inorganic carbon (DIC) and enhancing pH and dissolved oxygen (DO), but empirical evidence has been limited. Here, we investigated the effects of seaweed farming on net community production (NCPDIC, NCPDO), net community calcification (NCC), and seawater chemistry on a back reef lagoon system in Onna, Okinawa, Japan. Lagrangian drifters were used to measure and calculate rates of NCP, NCC, pH, and aragonite saturation state (Ωarag) in December 2022, April 2023, January 2024, and May 2024. The April 2023 and May 2024 surveys coincided with the annual maximum extents of seaweed cultivation (0.16 and 0.14 km2 respectively). Mean NCP and NCC were positive across sessions, but had high variability. Under saturating solar radiation, we observed elevated NCPDIC and NCPDO in April 2023 compared to January 2024, and stronger increases in pH and Ωarag in April 2023 and in May 2024 than in January 2024. Changes in pH and Ωarag were driven by NCPDIC, which was itself driven by temperature and solar radiation. We noted that NCC had a minor effect on the carbonate chemistry system relative to NCP. While we observed biogeochemical signals consistent with biotically-driven OAD modulation, the lack of spring survey control groups limits our ability to decisively attribute this modulation to the seaweed farm.

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Integrated study of ocean warming, CO₂ uptake, and acidification under anthropogenic emissions

Published 30 October 2026 Science Leave a Comment
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The study examines the influence of greenhouse gas pollutants on ocean waters. A key parameter describing ocean properties is pH, whose decrease negatively affects marine flora and fauna. Ocean surface temperatures rise over time due to the absorption of anthropogenic heat, with the most significant processes occurring within the upper 10 m layer. Phytoplankton, increasingly important for addressing ecological issues, is also affected by decreasing pH levels. To quantitatively describe ocean conditions, a thermodynamic calorimetric method is proposed. Validation is performed through a comparison of calculated and observed temperature variations, as well as the estimated specific heat capacity of ocean water. Measured pH variations are also compared with calculated values. The resulting expression incorporates temperature change, absorbed heat, and CO₂ content. Phytoplankton photosynthetic activity is further assessed in relation to potential cultivation areas on the ocean surface.

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Current knowledge of marine crustaceans in Mauritius and their global importance in a changing climate

Published 30 October 2026 Science Leave a Comment
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Marine crustaceans are ecologically and socio-economically important components of coastal and marine ecosystems; however, in Mauritius, knowledge of their biodiversity, functional roles, and responses to climate change remains limited and fragmented. This narrative review synthesizes available information on Mauritian marine crustaceans, with particular emphasis on the class Malacostraca, while identifying key knowledge gaps and research priorities relevant to their ecological importance and climate-change vulnerability at both local and global scales. Although existing records document 61 crustacean families in Mauritius, these data are sparse, outdated, and largely based on historical surveys, highlighting the urgent need for updated inventories and long-term monitoring. Globally, marine crustaceans act as trophic intermediaries, ecosystem engineers, and scavengers, contributing to nutrient cycling, sediment dynamics, and habitat stability. They support fisheries, aquaculture, tourism, and cultural practices, and provide valuable bioresources such as chitin, chitosan, and other bioactive compounds with applications in regeneratiom engineering, medicine, agriculture, environmental remediation, and biotechnology. Trade patterns further emphasize their economic importance, revealing export-oriented dynamics in Mauritius, instead of local consumption, that result in a net reliance on imports. Climate change poses an escalating threat through ocean warming, acidification, and increasing environmental variability, affecting DNA repair, protein synthesis, haemolymph, metabolic performance, calcification, reproduction, immunity, behavior, and species interactions. These stressors are further compounded by habitat degradation, altered symbiotic interactions and food-web disruption. The scarcity of empirical studies from Mauritius underscores the need for integrative, multi-stressor, and long-term research to support effective conservation, fisheries management, and climate resilience.

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Spatiotemporal water quality dynamics in Southern U.S. coastal reserves: a long-term perspective

Published 30 October 2026 Science Leave a Comment
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Water quality monitoring in estuarine ecosystems is essential for assessing the health and sustainability of these dynamic coastal habitats, which are increasingly vulnerable to environmental change and human impacts. This study aims to characterize long-term trends and seasonal drivers of seven key water quality parameters: temperature, salinity, dissolved oxygen (DO), pH, chlorophyll-a (Chla), nitrate + nitrite (NOx), and phosphate (PO4) across four southern U.S. National Estuarine Research Reserves (Apalachicola Bay, Grand Bay, Mission-Aransas, and Weeks Bay) to identify which reserves and processes are most vulnerable to climate and anthropogenic change. Using two decades of data (1995–2020) and applying Generalized Additive Models (GAMs), we identified significant spatial and temporal patterns linked to environmental and anthropogenic factors. Results revealed a warming trend in Weeks Bay (+0.1035 °C/year, P = 0.0013), a salinity decline in Grand Bay (−0.1699 PSU/year, P = 0.033), and a salinity increase in Apalachicola Bay (+0.2055 PSU/year, P = 0.003). DO concentrations peaked in spring and dropped in summer, reflecting seasonal nutrient inputs. Grand Bay exhibited the highest Chla variability (CV=131.48%). NOx concentrations declined in Grand Bay (−0.0003 mg/L/year, P = 0.0162), while PO4 levels remained relatively stable. pH trends suggested localized acidification, particularly in Mission-Aransas (−0.0071/year, P = 0.0016). GAM results emphasized the combined effects of long-term and seasonal changes, with site-specific differences. These findings provide critical insights into estuarine functioning and highlight the need for regionally tailored management strategies to enhance resilience and biodiversity conservation in U.S. coastal reserves.

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Abrupt pH changes overestimate the responses of Chaetoceros muelleri to ocean acidification

Published 30 October 2026 Science Leave a Comment
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Ocean acidification, characterized by a gradual seawater pH decline, influences marine primary producers such as diatoms, which contribute substantially to oceanic carbon fixation. Experimental studies aiming to project climate change impacts often simulate acidification via abrupt pH shifts, potentially misrepresenting ecological and evolutionary responses. Here we conduct a long-term evolution experiment with the marine diatom Chaetoceros muelleri, comparing abrupt and gradual CO2 increases from 440 to 1000 ppm over 1100 generations. Integrating evolutionary genomics, physiological assays, elemental stoichiometry, and Earth System Modeling, we find that abrupt acidification exaggerates diatom growth and carbon fixation responses by up to 15%, driven by enhanced divergent genomic signals and persistent gene expression changes. Gradual acidification elicits weaker phenotypic and genomic shifts, aligning more closely with natural ocean conditions. These findings suggest that models based on abrupt CO2 increases may overestimate the contribution of Chaetoceros muelleri and maybe also other diatoms to productivity and biogeochemical cycling under ocean acidification, highlighting the importance of gradual pH decline in experimental designs to accurately predict marine ecosystem responses.

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Navigating uncertainty in the Pacific Arctic region: toward adaptive fisheries management under climate change and ocean acidification impacts

Published 30 October 2026 Science Leave a Comment
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Fisheries management under climate change in the Pacific Arctic Region faces profound uncertainties, particularly concerning the trajectory of environmental drivers and the biological responses of fish species to ocean acidification (OA), which affect both stock productivity and spatial distributions. Here, we employed the Dynamic Bioclimate Envelope Model to project century-scale changes in abundance, maximum catch potential, and species distributions for key commercial fish under two climate scenarios (SSP1-2.6 and SSP5-8.5) and two alternative assumptions about OA responses, namely without OA effect and with OA effect parameterized as increases in basal metabolic rate and elevated larval mortality. Fishing mortality was treated as a management control variable, and the minimax regret criterion was applied to select the fishing mortality strategy that minimizes the worst-case loss in landed value relative to the scenario-specific optimal strategy across all climate and OA response scenarios. Results indicate strong regional heterogeneity: southern LMEs (East Bering Sea, West Bering Sea, and Aleutians) experienced persistent declines in abundance and maximum catch potential, with negative responses to OA further amplifying reductions, whereas the northern LME (Northern Bering–Chukchi Seas) exhibited substantial gains. These poleward shifts were accompanied by increased spatial aggregation, highlighting that species are not only shifting northward but also becoming more spatially concentrated within suitable habitats. Assessments that ignore OA effects risk overestimating long-term yields and exposing fisheries to productivity and revenue losses. Precautionary reductions in fishing mortality consistently minimized long-term regret across most species and LMEs. These findings highlight the critical interplay between climate change, OA effects, and management decisions, providing a scientific basis for adaptive fisheries management in the rapidly changing Pacific Arctic Region.

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The spatial and temporal variability of dissolved inorganic carbon and total alkalinity production during early diagenesis in river dominated ocean margin sediments and their resultant effect on bottom water acidification

Published 30 October 2026 Science Leave a Comment
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Rapid anthropogenic release of CO2(g) to the atmosphere promotes global ocean acidification that is exacerbated in coastal environments by processes such as eutrophication and upwelling of low pH deep water. The decline in ocean pH through time poses a threat to marine ecosystems and the coastal communities that depend on them. Total alkalinity (TA), mainly supplied to the ocean by river discharge, allows seawater to buffer against future pH decline. Pore water DIC and TA generated in sediments during early diagenesis may be released to the overlying waters and either contribute to acidity or buffer against overlying water acidity, depending on the benthic TA to dissolved inorganic carbon (DIC) flux ratio (RTA:DIC), as RTA:DIC < 1 promotes acidification and RTA:DIC > 1 mitigates further acidification. The rapid accumulation of organic matter in river dominated ocean margin (RiOMar) sediments promotes the generation of relatively large benthic DIC and TA fluxes that may significantly influence overlying water acidification in these regions. A number of seasonally variable environmental factors such as river discharge and sediment resuspension may promote early diagenetic redox cycling in RiOMar sediments and induce seasonal RTA:DIC variability. This seasonal RTA:DIC variability is poorly characterized, however, despite their potential influence on overlying water acidification in these regions.

The present dissertation investigated how early diagenetic processes in RiOMar sediments and resultant benthic solute fluxes and RTA:DIC respond to seasonally variable environmental factors. This was accomplished using a combination of in-situ benthic flux measurements on the northern Gulf of Mexico (nGoM) continental margin and ex-situ sediment core solid phase and pore water analyses from both nGoM margin and Rhône River prodelta sediments. Overall, the results presented in this dissertation revealed significant seasonal early diagenetic and RTA:DIC variability in RiOMars that was driven by seasonally variable environmental factors such as river discharge, primary production, sediment perturbations, and bottom water hypoxia development. The largest RTA:DIC from RiOMar sediments may be promoted either 1) proximal to river deltas and in eutrophic hypoxic systems, where anerobic TA generation is high and reoxidation of reduced metabolites is low, or 2) when CaCO3 dissolution generates significant TA in pore waters.

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Connecting international ocean, climate and biodiversity governance to protect deep-sea life

Published 29 October 2026 Science Leave a Comment
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Deep-ocean biodiversity plays a fundamental role in the global carbon cycle and Earth’s climate system. Despite this critical function, international biodiversity and climate change governance frameworks have rarely considered deep-sea life to any considerable extent historically. Recent developments create opportunities to close this gap, including through the Agreement under the United Nations Convention on the Law of the Sea on the Conservation and Sustainable Use of Marine Biological Diversity of Areas beyond National Jurisdiction (BBNJ Agreement), the Paris Agreement under the UN Framework Convention on Climate Change (UNFCCC), and the Kunming-Montreal Global Biodiversity Framework under the Convention on Biological Diversity (CBD). We review the history and developments of these conventions to date regarding how they address the interface between climate, biodiversity, and the deep ocean, and use this historical overview to identify specific opportunities and mechanisms that can be used to sustain and protect life in the deep ocean more effectively and coherently going forward. Practical suggestions include incorporating climate and carbon considerations in the creation of marine protected areas and other area-based management tools under the BBNJ Agreement, establishing cross-cutting mechanisms that can align efforts under the UNFCCC, CBD, and the BBNJ Agreement, and, under the Paris Agreement, incorporating deep-ocean actions in nationally determined contributions, reconsidering what counts as mitigation or adaptation to encourage consideration of carbon conservation actions, and ensuring that climate change mitigation efforts do not harm deep-ocean biodiversity.

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