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.

…

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.

…

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

Continue reading ‘Applications open: fourth winter school on ocean acidification and multiple stressors’

From response to resilience: celebrating 15 years of NOAA’s Ocean Acidification Program

Published 27 October 2026 Web sites and blogs Leave a Comment

Fifteen years ago, oyster hatcheries on the West Coast faced an invisible crisis. Oyster larvae were dying by the billions from an unknown culprit, threatening a multi-million dollar industry and families’ livelihoods. Oyster growers turned to scientists to uncover the hidden threat – changing ocean chemistry that brought more corrosive waters to western shores.

Now, our nation is no longer flying blind. Congressional action empowered NOAA’s Ocean Acidification Program (OAP) to better understand ocean and coastal acidification (OA) and its ecological and economic impacts.

Highlights include:

  • OAP’s work helps harvesters of the nation’s most valuable shellfish fisheries understand a changing ocean and how they can adapt to keep up production.
  • OAP established the first-ever dedicated national ocean acidification observing network
  • Our science has advanced from from collecting observations to putting them to use in models and forecasts that enable community and industry planning.
  • OAP leads interagency coordination and outreach to on-the-ground communities most impacted by a ocean acidification.

Key Insight: Hatcheries on the West Coast were pumping in local water during upwelling, a natural process that has been delivering more corrosive waters to the surface due to OA. Technological advances allow hatcheries to measure acidity in real-time, and adjust the acidity of the water to protect oysters as they grow. Today, OAP helps growers prepare for continued OA from investigating practices from seawater to genes.

Recognizing the severe ecological and economic threats posed by OA, Congress passed the Federal Ocean Acidification Research and Monitoring Act (FOARAM) of 2009, officially establishing NOAA’s Ocean Acidification Program. Recently reauthorized under the CHIPS and Science Act of 2022, this mandate charged OAP with the critical mission to monitor ocean chemistry, understand its impacts on marine life, and give communities the information and tools they need to adapt.

From water chemistry to resilience

This year marks OAP’s fifteenth year on the frontlines of ocean acidification. Our understanding has evolved far beyond the initial identification of this ocean crisis. A robust observing network that powers modern forecasts now stands. This set the foundation to then unravel the complex sensitivities of many marine species, and deliver essential tools that communities rely on to secure their livelihoods and futures.

…

Continue reading ‘From response to resilience: celebrating 15 years of NOAA’s Ocean Acidification Program’

Response of volatile halocarbons release to atmospheric deposition and ocean acidification in the tropical eastern Indian Ocean

Published 27 October 2026 Science Leave a Comment
Tags: , , , , , , , , , ,

Highlights

  • Fe(III) inputs increased CH3I emission by photochemical and biogenic processes.
  • Nutrient inputs enhanced volatile halocarbons by boosting biogenic processes.
  • Ocean acidification enhanced CH2Br2/CHBr3 emissions by BrPO-mediated halogenation.

Abstract

Short-lived volatile halocarbons (SLVHCs) are important trace greenhouse gases and ozone-depleting substances influencing global climate. Anthropogenic activities have accelerated ocean acidification (OA) and enhanced atmospheric deposition, yet how these perturbations regulate SLVHCs production in open ocean remains unclear. Herein, we investigated the effects of OA and atmospheric deposition derived Fe(III) and nutrient input on SLVHCs production through ship-based incubation experiments at two stations in the tropical eastern Indian Ocean (10°N-10°S) from March to May 2022. Our findings revealed that nutrient addition promoted phytoplankton growth with the maximum Chlorophyll a (Chl a) increasing to 6.17 μg L−1, enhanced bromoperoxidase (BrPO) activity (by 108.3 % compared to the control group), and stimulated release of dissolved organic carbon (DOC), ultimately driving the production of CH3I, CH2Br2, and CHBr3 (by 152.0 %, 200.2 %, and 141.8 % increases, respectively). OA and Fe(III) additions promoted phytoplankton growth (Chl a up to 1.85 μg L⁻1), thereby enhancing SLVHCs production through biological and photochemical processes, whereas they exhibited no significant effects on SLVHCs production in relatively oligotrophic regions. Mechanistically, CH3I release was regulated by phytoplankton-mediated biogenic processes and photochemical processes. In contrast, CH2Br2 and CHBr3 production was predominantly associated with phytoplankton-mediated biogenic processes (BrPO-mediated halogenation). These results demonstrating that OA, Fe(III), and nutrient inputs regulate marine SLVHC production by altering phytoplankton-mediated biogenic processes and photochemical reactivity. Our study offers a novel perspective and direct evidence for quantifying the production of SLVHCs under climate change scenarios, thereby underscoring the need to reassess oceanic climate feedbacks in the context of anthropogenic forcing.

Continue reading ‘Response of volatile halocarbons release to atmospheric deposition and ocean acidification in the tropical eastern Indian Ocean’

Interactive effects of ocean acidification and benzophenone-3 on mussel physiology: a biomarker-based approach

Published 27 October 2026 Science Leave a Comment
Tags: , , , , ,

Highlights

  • Ocean acidification was the primary driver of biomarker responses.
  • Low pH enhanced BP3-induced cytotoxicity in hemocytes.
  • BP3 detoxification mainly involved the GST/GSH pathway.
  • Lipid peroxidation occurred in gills and digestive gland despite antioxidant response.
  • Acidification impacts biomineralization enzymes more strongly than BP3.

Abstract

Benzophenone-3 (BP3), a widely used ultraviolet (UV) filter in personal care products and industrial applications, is an emerging concern in aquatic ecosystems due to its lipophilicity, bioaccumulation potential, and toxicity to marine biota. Its occurrence in marine environments coincides with ocean acidification driven by rising atmospheric CO2 emissions, which disrupts the bicarbonate buffer system and reduces pH. This study investigated the acute effects (96 h exposure) of BP3 (at realistic concentrations of 0.2 and 2 μg/L) under 3 pH conditions (8.1- the current South Atlantic condition- and 7.6 and 7.3 as projected acidification scenarios for 2100 and 2300, respectively) in the brown mussel Perna perna. The effects were investigated through analysis of hemocyte viability and biomarkers related to detoxification (glutathione S-transferase, glutathione, glutamate cysteine ligase, and reduced glutathione), oxidative stress (antioxidant capacity against peroxyl radicals and lipid peroxidation), and biomineralization (carbonic anhydrase and Ca2+ATPase), measured in the gills, digestive gland, and mantle. Despite BP3-induced activation of glutathione-related detoxification pathways, as evidenced by increased GSH levels and GST activity, particularly in the gills, hemocyte viability decreased after BP3 exposure, with the greatest reduction at pH 7.3. Lipid peroxidation (LPO) also increased in the gills and digestive gland under acidified conditions, with the magnitude of the response varying according to BP3 concentration. CA and Ca2+ATPase activities were more strongly influenced by acidification than by BP3 exposure, although their responses were tissue-specific and, in some cases, modulated by BP3 exposure. Multivariate analyses identified pH as the primary driver of biomarker responses.

Graphical abstract

Continue reading ‘Interactive effects of ocean acidification and benzophenone-3 on mussel physiology: a biomarker-based approach’

From population to individual: bulk and single-cell analysis reveal Fe bioavailability, limitation thresholds, and biological responses for marine diatom Chaetoceros debilis

Published 27 October 2026 Science Leave a Comment
Tags: , , , , , , ,

Highlights

  • Fe speciation and pH jointly regulated Fe bioavailability.
  • A critical bioavailable Fe limitation threshold (∼10 nM) was identified for the marine algae.
  • Single-cell analysis revealed previously hidden heterogenous Fe accumulation.
  • Fe stress induced adaptive responses including metallome remodeling.

Abstract

In marine ecosystems, Fe fundamentally regulates algal productivity and drives biogeochemical cycling in the hydrosphere, yet its environmental controls and cellular responses remain insufficiently resolved, particularly at the single-cell level. Herein, we combined bulk and single-cell analysis to systematically investigate Fe bioaccumulation process in the marine diatom Chaetoceros debilis under varying Fe species, initial pH, and concentration conditions. Fe bioavailability followed the order Fe-ethylenediaminetetraacetate > Fe-deferoxamine B > Ferrihydrite and decreased with declining initial pH, highlighting the combined control of chemical speciation and ocean acidification. A critical bioavailable Fe limitation threshold of ∼10 nM was identified, below which algal growth, pigmentation, and cell size were significantly suppressed. Under Fe limitation, cells exhibited compensatory accumulation of other metals (e.g., Zn, Mn, Cu, and Ni), indicating metallome remodeling as an adaptive strategy. Notably, single-cell analysis revealed pronounced heterogeneity in Fe accumulation within populations, with heterogeneity positively related to bioavailable Fe levels. These findings demonstrate that algal Fe accumulation is governed by coupled environmental and physiological processes and that population-level averages mask critical cell-to-cell variability and their adaptive strategies under environmental stress. This work provides mechanistic insights into how environmental chemistry regulates metal bioavailability and biological responses, offering a broadly applicable framework for understanding the environmental behavior and ecological effects of trace metals and other contaminants in aquatic ecosystems.

Graphical abstract

Continue reading ‘From population to individual: bulk and single-cell analysis reveal Fe bioavailability, limitation thresholds, and biological responses for marine diatom Chaetoceros debilis’

Surviving together: evolutionary dependency, community dynamics, and mortality in marine microbial communities

Published 26 October 2026 Science Leave a Comment
Tags: , , , , , , , , , , , , , , , , , , ,

Oligotrophic regions of the world ocean sustain vast phytoplankton populations despite extremely low nutrient levels. However, the mechanisms governing their coexistence, interdependence, and mortality are poorly understood. This dissertation investigates how evolutionary dependency, community feedback, and regulated cell death (RCD) jointly shape the stability of marine microbial communities using the Prochlorococcus/Parasynechococcus/Alteromonas model system.

In Chapter 1, I argue that the Black Queen (BQ) hypothesis—which posits that microbes lose costly metabolic functions supplied by community partners—provides a unifying framework for understanding phytoplankton ecology. This framework helps resolve longstanding puzzles, including the paradox of the plankton and the evolutionary maintenance of RCD in unicellular organisms. Building on this framework, Chapter 2 uses transcriptomic analysis of Alteromonas in co-culture with picocyanobacteria to demonstrate that community composition induces greater changes in gene expression than pCO₂ alone. Reduced 2-phosphoglycolate/glycolate exudation by Prochlorococcus under elevated pCO₂ may disrupt the helper heterotroph effect underlying this cyanobacterium’s BQ dependency.

Chapter 3 integrates co-culture experiments, RNA-seq, metabolomics, and mathematical modeling to demonstrate that the stable coexistence of Prochlorococcus and Parasynechococcus is maintained by an “Ouroboros network” of feedback loops. In this network, resource competition, carbon exudation, BQ dependency, and possibly RCD collectively stabilize the community across environmental gradients and during adaptation to changing conditions.

Chapter 4 resolves the cellular mechanisms underlying RCD in these cyanobacteria, showing that differences in cell death modes and the number of checkpoint-linked mortality events between taxa are associated with divergent life-history strategies. These findings suggest that carbon released at these checkpoints may shape interactions with helper Alteromonas, linking individual cell death to community-level interdependencies.

In conclusion, these findings converge on a new resolution to the paradox of the plankton: coexistence in resource-limited environments emerges from interdependent metabolic exchanges, feedback, and regulated cell death shaped by multilevel selection. I propose that together, these processes form an “altruistic bargain” in which stability arises from self-constraint rather than competition alone. Because these interactions are environmentally sensitive, climate change, including warming and acidification, may disrupt the dependencies that sustain microbial diversity and ecosystem function in the world ocean.

Continue reading ‘Surviving together: evolutionary dependency, community dynamics, and mortality in marine microbial communities’

Large-scale water-sediment regulation (Yellow River) substantially reshapes organic carbon mineralization pathways and benthic fluxes in sediment of a river-dominated sea (Bohai Sea)

Published 26 October 2026 Science Leave a Comment
Tags: , , ,

Large-scale hydrological engineering has fundamentally altered the rhythm of land-to-ocean material transport globally, yet the mechanistic response of coastal benthic biogeochemistry to these “pulse” events remains poorly quantified. Here, we investigated the transient impacts of the annual Yellow River Water-Sediment Regulation (WSR), a massive anthropogenic flood, on sediment organic carbon (OC) mineralization and benthic fluxes in the Bohai Sea (BHS) by combining geochemical analyses with sediment incubations. Results indicated that the WSR enhanced sediment OC mineralization rates by an average factor of 1.65, driven primarily by pulsed input of labile OC and probably also reflecting a priming effect. This stimulation reconfigured dominant diagenetic pathways: significantly elevating the role of dissimilatory iron reduction at the expense of both aerobic respiration and sulfate reduction. In addition, pulsed nitrate inputs promoted denitrification, establishing it as an important OC mineralization pathway. Concurrently, diffusive nutrient fluxes increased by a factor of 1.9–5.1 following the WSR, and the mean ratio of total alkalinity to dissolved inorganic carbon fluxes decreased from 1.34 to 0.96. This shift in the ratio signifies a reduced capacity for carbonate buffering in the bottom waters, which could exacerbate seasonal bottom-water acidification. Collectively, our findings demonstrate that short-term anthropogenic perturbations can rapidly reprogram sediment diagenesis and benthic fluxes, thereby perturbing carbon and nutrient cycling as well as benthic-pelagic coupling in river-dominated coastal systems.

Plain Language Summary

The annual Water-Sediment Regulation of the Yellow River is one of the world’s largest engineered flow manipulations, rapidly delivering huge amounts of freshwater and sediment into the Bohai Sea (BHS). While much is known about its effects on the water column ecochemistry, how such a large-scale human intervention alters organic carbon degradation and chemical exchange in seafloor sediments has remained unclear. By combining field measurements and laboratory experiments, we show that this event strongly enhances sediment carbon degradation rates and shifts the dominant pathways, favoring iron reduction and nitrate reduction processes. These changes drive substantial increases in benthic fluxes of dissolved inorganic carbon and nutrients (ammonium, silicate, and phosphate) into overlying waters. Notably, the regulation reduces the ratio of alkalinity to inorganic carbon flux, implying a temporary decline in the capacity of the sea to absorb atmospheric CO2. Our findings provide critical insights by revealing that large-scale human-regulated river discharges can rapidly reshape coastal sediment biogeochemistry. These results have important implications for carbon and nutrient cycling, offering valuable references for understanding not only the BHS but also other river-dominated coastal systems worldwide.

Continue reading ‘Large-scale water-sediment regulation (Yellow River) substantially reshapes organic carbon mineralization pathways and benthic fluxes in sediment of a river-dominated sea (Bohai Sea)’

Hypoxia and acidification antagonistically suppress nitrification but enhance its N2O production in coastal waters

Published 26 October 2026 Science Leave a Comment
Tags: , , , , , , , ,

The concurrent intensification of hypoxia and acidification poses a growing threat to estuarine-coastal ecosystems globally, yet their interactive impacts on nitrification, a key process in the nitrogen (N) cycle and a substantial source of nitrous oxide (N2O), remain poorly understood. This knowledge gap hinders reliable projections of future N cycling and climate feedbacks in these critical ecosystems. Here, we demonstrate that along the estuarine-coastal continuum, the co-occurrence of hypoxia and acidification suppresses nitrification rates but stimulates nitrification-derived N2O emissions—although their combined effect is lesser than the sum of their individual effects. Metatranscriptomic analysis provided molecular evidence for these isotopically traced responses and uncovered critical microbial coping strategies through transcriptional adjustments in metabolic pathways for energy conservation and stress tolerance. This previously overlooked interaction disrupts microbial N cycling with potential impacts on N2O emissions and climate feedbacks, highlighting the necessity to revise predictive models by incorporating such multistressor dynamics.

Continue reading ‘Hypoxia and acidification antagonistically suppress nitrification but enhance its N2O production in coastal waters’

Physiological responses of Atlantic surfclams (Spisula solidissima) to moderate ocean acidification across thermal regimes

Published 23 October 2026 Science Leave a Comment
Tags: , , , , , , , , , , , ,

Highlights

  • Interactive effects of warming and acidification tested in surfclams.
  • Growth, feeding, and metabolic rates measured after 6-week exposure.
  • Moderate acidification had limited effects under warming conditions.
  • Surfclams showed resilience to near-future ocean acidification.
  • Multi-stressor design improves ecological relevance of lab studies.

Abstract

Understanding marine organismal responses to co-occurring climate stressors is critical for predicting changes in ecosystems and commercial fisheries. The Atlantic surfclam supports a major commercial fishery in the Northeastern United States, where ocean warming and acidification are rapidly altering marine habitats. To evaluate how changing ocean conditions may affect bivalve physiology, surfclams were exposed to conditions reflective of ocean warming and acidification, respectively. One-year-old surfclams were exposed to nine conditions in a fully crossed design of temperature (ambient, +2 °C, and + 5 °C) and pH (7.88 ± 0.05, 7.76 ± 0.05, and 7.51 ± 0.07) for six weeks in a flow-through laboratory experiment using natural seawater. We quantified several physiological responses including growth, feeding, digestion, respiration rates, and shell weight and thickness to assess organismal performance across treatments.

Surfclams generally exhibited resistance to moderate ocean acidification across warming, but non-thermally stressful, temperatures. No effects of ocean acidification were observed on surfclam growth or respiration, although other physiological metrics (shell thickness and absorption rate) decreased with decreasing pH at some temperatures. These findings provide experimentally-derived insight into species-specific responses to interacting climate stressors. Further, the experimental design highlights the importance of integrating natural environmental variability into laboratory studies and studying multiple environmental stressors concurrently. This study contributes a basis for refining models of surfclam growth and distribution in potential future climate scenarios, with implications for sustainable fisheries management.

Continue reading ‘Physiological responses of Atlantic surfclams (Spisula solidissima) to moderate ocean acidification across thermal regimes’

Ocean warming and acidification reveal transcriptional plasticity in the gastropod Hexaplex trunculus

Published 23 October 2026 Science Leave a Comment
Tags: , , , , , , ,

Coastal ecosystems, particularly in the rapidly warming Mediterranean Sea, are increasingly impacted by climate change driven by ocean warming and acidification. Calcifying marine invertebrates are especially vulnerable, yet their molecular responses remain poorly understood. Gene expression dynamics in the ecologically and commercially important gastropod Hexaplex trunculus were investigated under simulated scenarios combining elevated temperature and reduced pH. High-throughput RNA sequencing was used to generate a de novo assembly of the foot transcriptome, followed by differential gene expression analyses to characterize molecular responses to individual and interactive stressors under high-emission (RCP 8.5) projections. The foot tissue – central to locomotion, adhesion, and environmental interaction – exhibited pronounced transcriptional changes in genes associated with calcium signaling, ion transport, aerobic respiration, muscle contraction, and transmembrane transport. Ocean acidification emerged as the dominant driver of transcriptional change, inducing substantial shifts in metabolic demand and ion regulatory pathways, which might suggest increased energetic costs and potential functional constraints. The results demonstrate marked transcriptional plasticity in H. trunculus under combined climate stressors. By providing foundational transcriptomic resources for this species and mechanistic insight into its response to projected environmental changes, this study advances the understanding of molecular processes in vulnerable Mediterranean gastropods and informs ecological assessment efforts in rapidly warming marine ecosystems.

Continue reading ‘Ocean warming and acidification reveal transcriptional plasticity in the gastropod Hexaplex trunculus’

Flinders University research links ocean acidification to diatom health and carbon cycling

Published 23 October 2026 Press releases Leave a Comment

New research from Flinders University shows how changes in diatoms (microalgae) could further undermine the foundation of aquatic life’s food webs—as well as vital deep-sea carbon capture or sequestration.

A new study published in Marine Ecology used high-tech methods to test common microalgal species to assess how various stressors, including acidification from excessive carbon dioxide (CO2) levels, affect absorption of trace metals and therefore undermine their overall health and role in Earth’s carbon cycling.

Although microscopic, the single-celled algae diatoms that live in oceans, lakes, rivers, and even damp soil are among the most important organisms on Earth, as they produce a significant portion of oxygen in the atmosphere.

Diatoms account for 40%–50% of primary production in oceans, and they contribute to organic carbon being exported to the deep ocean by fixing CO2 from near-surface waters, says senior author Professor Sophie Leterme, director of the ARC Industry Transformation Training Centre for Biofilm Research and Innovation at Flinders University’s College of Science and Engineering.

“We showed that changes in the ocean pH can affect the growth, abundance and elemental composition of these diatoms,” said Professor Leterme. “We need to investigate how these changes interplay between various trace elements and can lead to broader ecological impacts, such as disruption to marine food webs, reduced carbon and silicon export, and increased microbial and nutrient activity.”

Rising carbon emissions affect pH levels in seawater, which can alter planktonic algae’s absorption of trace elements including iron, zinc, and cadmium, which are essential for inorganic carbon acquisition.

The dissolution of CO2 into the ocean has already induced a global drop in pH of 0.1 units since the end of the Industrial Revolution, and values are expected to drop another 0.3–0.6 units by the end of this century.

Diatom species are great bio-indicators, often used to assess water quality and boost understanding of how ongoing ocean acidification and rising water temperatures downgrade their physiology and functioning—which have important consequences for the future of oceans.

The Flinders researchers say a better understanding of how these complex processes work in seawater will help find solutions, including the development of novel biofilms to reduce shipping pollution in harbors.

Using seawater samples collected in South Australia’s Gulf St Vincent and from the CSIRO algae collection, the researchers’ highly sensitive neutron activation analysis was used in experimental setups on the species Thalassiosira pseudonana and Nitzschia navis-varingica.

The experiments, supported by ANSTO expertise, showed how trace metal uptake by marine diatoms could be applied to other marine organisms’ absorption of a wide range of other elements in the environment.

“While a higher abundance and growth of diatoms might be beneficial to reduce carbon dioxide levels, the impact of lower concentrations of major and trace elements in the environment is not well understood.”

The research article—’The impact of ocean acidification on the sorption of trace metals by diatoms‘ (2026) by Sophie C Leterme, Tamar Jamieson, Alessandra Mazzoli, Angus Hambrook, Rachel S Popelka-Filcoff, John Bennett, and Attila Stopic—has been published in Marine Ecology (Wiley). DOI: 10.1111/maec.70112.

Continue reading ‘Flinders University research links ocean acidification to diatom health and carbon cycling’

Planetary Health Check 2026 finds mounting pressures across Earth’s life support systems

Published 23 October 2026 Press releases Leave a Comment

Seven breached Planetary Boundaries continue to worsen as record ocean heat, droughts, floods, wildfires and extreme heat reveal an Earth system under strain, according to the latest Planetary Health Check. The annual update is authored by more than 60 scientists, and produced by the Planetary Boundaries Science Lab at the Potsdam Institute for Climate Impact Research (PIK).

The Planetary Boundaries describe the interconnected Earth-system processes that must remain within safe limits to preserve the planet’s stability and resilience. Seven of the nine Planetary Boundaries are now transgressed, with ocean acidification the latest to breach its boundary in 2025. All seven are now at their highest recorded levels of transgression.

The seven transgressed boundaries are: climate change, change in biosphere integrity, land system change, freshwater change, modification of biogeochemical flows, introduction of novel entities and ocean acidification. Only the stratospheric ozone depletion and atmospheric aerosol loading boundaries have shown improvement over the last decade. However, the authors caution that global progress may mask unsafe aerosol levels persisting in some regions.

“The diagnosis is unambiguous. Pressure is rising across every Planetary Boundary already outside the safe operating space. It means that the risk of large-scale, persistent and potentially irreversible change is increasing, while our margin for error in tackling these problems is shrinking,” commented Boris Sakschewski, PIK scientist and lead author of the report.

“We do not have the luxury of time, but we do have the knowledge, capacity and solutions to change course. Accelerating action to return to the safe operating space across all Planetary Boundaries is essential to protect lives and livelihoods, and to deliver on the promise of shared future prosperity,” said Johan Rockström, PIK Director and co-author of the report.

A year of extreme events highlights escalating risks

The report comes after 12 months marked by extremes across land and oceans. Human-caused warming intensified several major weather extremes, while degraded ecosystems, water stress, land-use change, exposure and social vulnerability often magnified their impacts.

Pakistan’s 2025 monsoon floods affected more than 6.9 million people. Global ocean heat content reached a new record in 2025, with Hurricane Melissa rapidly ramping up to a Category 5 Hurricane and striking Jamaica after passing over exceptionally warm seas. January 2023 to September 2025 saw bleaching-level heat stress impacting approximately 84.4 percent of the world’s coral reef area, making it the largest global coral-bleaching event observed to date.

In 2026, Western Europe experienced its hottest June-July period on record, accompanied by drought across France, Spain, Germany and the United Kingdom, with major wildfires across Europe and Canada. Record-breaking heat was also recorded in Japan, South Korea and parts of the Middle East.

Hindou Oumarou Ibrahim, Chair of the Planetary Guardians said, “Read that list again: Pakistan, the Caribbean, Europe, the reefs beneath our oceans. These are not separate emergencies; the planet is telling us, in every region at once, that it is out of balance. As Chair of Planetary Guardians, I hear this same story wherever I go, whether from a pastoralist watching the rains fail season after season or a coastal community watching the sea rise. The 2026 Planetary Health Check puts data behind what communities on the frontlines already know from living it. We do not have the luxury of treating these as separate crises any longer.”

“Any kind of movement requires patience, trust, and the will to keep going, even when it may be easier to stop. The 2026 Planetary Health Check tells us we need that same collective resolve now, applied to the whole planet. Seven of nine boundaries are broken, and no single nation can restore them alone; this is a peace process the entire world must commit to, together, starting now,” said Juan Manuel Santos, former President of Colombia and Co-Vice Chair of the Planetary Guardians.

Natural carbon sinks under pressure

Vegetation and soils absorb a substantial share of human carbon dioxide emissions, but repeated heat, drought, fire and ecosystem degradation can reduce carbon uptake and, in some regions, turn ecosystems from sinks into carbon sources.

This year’s report discusses whether the models that we use to calculate the land carbon sink may overestimate its resilience.

“Our path to net zero emissions relies on functioning carbon sinks. Current observations raise the alarm that our planet may be losing its buffering capacity against the increasing pressures we’re putting on it,” Sakschewski said.

Planetary Boundaries Science (PBScience), 2026: Planetary Health Check 2026. Potsdam Institute for Climate Impact Research, Potsdam, Germany.

Link once published: https://www.planetaryhealthcheck.org/

Continue reading ‘Planetary Health Check 2026 finds mounting pressures across Earth’s life support systems’

Global projections of coral reef sediment dissolution in the 21st century

Published 22 October 2026 Science Leave a Comment
Tags: , , , , , ,

Abstract

Coral reefs build carbonate frameworks, but ocean acidification threatens to reverse this role by accelerating dissolution of permeable reef sediments. We combined Earth system model projections across five emission pathways with an aragonite saturation state-dissolution relationship to project global reef sediment dissolution through 2100. Under stringent mitigation, less than 2% of reef area experiences dissolution by 2100, compared with 30% under intermediate emissions and nearly all reefs under high emissions. Cumulative calcium carbonate loss reaches 2.5 gigatonnes under the highest-emission pathway, accompanied by 0.7 gigatonnes of potential carbon dioxide uptake that is globally negligible but signals framework degradation. Model-derived aragonite saturation states exceeded in situ observations in most regions, suggesting that reef sediment dissolution may begin earlier than gridded projections indicate. The southern Central Pacific emerges as a candidate acidification refugium warranting reef-scale evaluation. Continued high emissions could shift reefs from net carbonate accretion toward widespread structural loss.

Plain Language Summary

Human carbon emissions are making the oceans more acidic, threatening not only living corals but also the carbonate sand and rubble that help build and support reef structures. Using climate model projections and reef observations, we estimated how reef sediment dissolution may change worldwide through 2100. Under high-emission scenarios, nearly all coral reefs are projected to experience sediment dissolution by the end of the century, with cumulative calcium carbonate losses reaching 2.5 billion metric tons. Although this process can absorb carbon dioxide, the amount is far too small to meaningfully slow climate change and instead reflects the physical breakdown of reef structures. The southern Central Pacific may acidify more slowly and could offer some protection, but local water chemistry and heat stress must be evaluated before the region can be considered a reliable refuge.

Continue reading ‘Global projections of coral reef sediment dissolution in the 21st century’

Assessing the skill of a biogeochemical model tailored to a global coupled forecasting system: a case study for the Bay of Bengal carbon cycle

Published 22 October 2026 Science Leave a Comment
Tags: , , , ,

To achieve real-time prediction of surface ocean carbonaceous variables in the Indian Ocean, we integrate an extended-range coupled forecast system with a global ocean biogeochemistry model incorporating an explicit carbon cycle. The physical ocean state is provided by the Indian Institute of Tropical Meteorology Extended Range Prediction for Applications to Society (IITM-ERPAS) coupled model, which drives the Ocean Tracer Transport Model (OTTM) with phosphate-dependent biology and OCMIP-II-type carbonate chemistry (hereafter referred to as OTTM-ERPAS-BGC). Daily mean outputs from IITM-ERPAS are used to drive the biogeochemical simulations. Model skill is evaluated against in situ observations of surface partial pressure of CO₂ (pCO₂) and pH from the Bay of Bengal Ocean Acidification (BOBOA) mooring (90°E, 15°N) over the period 2013-2018. The model successfully reproduces observed variability, with strong and statistically significant correlations (r = 0.65 for pCO₂ and r = 0.80 for pH; p < 0.001). Based on this performance, a coherent region of influence (87.5°E-92.5°E, 12.5°N-17.5°N) is identified to further assess model skill against BOBOA time-series observations, climatological products and other derived datasets of pCO₂ and pH in terms of seasonal cycle, subseasonal variability and long-term trends. Seasonal cycle analysis reveals that the updated Takahashi climatological pCO₂ product is systematically underestimated by ∼18 ± 3 μatm compared to BOBOA observations, OTTM-ERPAS-BGC simulations and other derived products. Subseasonal variability exhibits pronounced intraseasonal signals, with significant spectral peaks at 13-41 days for pCO₂ and 17-41 days for pH, reflecting dominant intraseasonal modulation of the Bay of Bengal carbon cycle. Long-term trends indicate a robust increase in pCO₂ (2.02 μatm yr⁻¹) and a concomitant decline in pH (-0.00253 yr⁻¹), consistent with progressive acidification of the basin. The decomposition analysis demonstrates that dissolved inorganic carbon (DIC) and total alkalinity (ALK) exert dominant and complementary controls on pCO₂ and pH variability, respectively, while sea surface temperature (SST) plays a secondary role. Overall, this study demonstrates that coupling extended-range physical forecasts with ocean biogeochemical models provides a viable pathway for the operational prediction of carbon variables. Such capability is critical for the early detection of ocean acidification and hypercapnia hotspots, with significant implications for marine ecosystem management and climate services in the Indian Ocean.

Continue reading ‘Assessing the skill of a biogeochemical model tailored to a global coupled forecasting system: a case study for the Bay of Bengal carbon cycle’

Climate change and fish reproduction: a meta-analysis of global laboratory-based experimental evidence across species and ecosystems

Published 22 October 2026 Science Leave a Comment
Tags: , , , , , , , , ,

Climate change is altering fish reproduction by disrupting spawning cycles, reducing egg viability, and altering reproductive behaviours essential for population sustainability, to our knowledge, this is the first synthesis to integrate laboratory-based evidence for temperature, hypoxia, ocean acidification, and their combined exposure across reproductive performance, physiological, developmental, and molecular endpoints, and across freshwater, brackish, and marine habitats. Following PICOS and PRISMA criteria, we synthesised 779 effect sizes (740 retained after outlier exclusion) from 80 controlled laboratory studies (38,500 observations; 54 species; 28 countries). A three-level multilevel model accounting for non-independence among effect sizes drawn from the same study showed a significant overall negative effect of climate stressors on fish reproduction (Hedges’ g = −0.421, 95% CI: −0.631 to −0.210, p < 0.001; I² = 94.9%, decomposed into 36.3% between-study and 58.6% within-study heterogeneity). Hypoxia was the dominant and statistically distinct driver (g = −1.145, 95% CI: −1.648 to −0.643, p < 0.0001), most severely impairing gonadal development and sperm quality. The overall warming effect did not reach significance once non-independence was accounted for (g = −0.221, 95% CI: −0.448–0.006, p = 0.057), an uncertain negative trend rather than confirmed impairment, although tropical freshwater species showed significant subgroup-specific declines in reproductive physiology and genetic parameters. Ocean acidification showed a small positive effect (g = 0.199, 95% CI: 0.056–0.343, p = 0.006) that was not robust under robust variance estimation (p = 0.133) and is interpreted with caution. Combined multi-stressor exposure showed a negative trend (g = −0.901, 95% CI: −1.992–0.190, p = 0.106) that did not reach significance, based on only three studies. A formal omnibus test confirmed that stressor categories differ significantly in their effects (QM = 18.61,df = 3, p = 0.0003), with hypoxia statistically distinct from both temperature and ocean acidification. Leave-one-out and cumulative meta-analyses confirmed the robustness of the overall finding.

Continue reading ‘Climate change and fish reproduction: a meta-analysis of global laboratory-based experimental evidence across species and ecosystems’

Plastic pollution as a pathway to ocean acidification and disruption of the seawater carbonate system

Published 22 October 2026 Science Leave a Comment
Tags: , , , ,

Ocean acidification threatens calcifying organisms by reducing seawater pH and carbonate ion availability, while plastic pollution may intensify this effect through chemical and microbial processes, exacerbating impacts on calcification. Here, we investigated, for the first time, the biogeochemical mechanisms of plastic-pollution-induced ocean acidification and the role of plastic as a modifier of the seawater carbonate system. Microcosm experiments were conducted using naturally weathered plastic particles incubated in seawater under irradiated and dark conditions. The experiment comprised two seven-day phases: (1) an abiotic phase evaluating the physicochemical effects of plastic degradation and (2) a biotic phase assessing microbial contributions to plastic-induced acidification. Variations in pH, dissolved CO₂, Ωarag, and Ωcalc were monitored as acidification indicators. During the abiotic phase, plastic increased dissolved CO₂ concentrations threefold under irradiation (27.08 µmol kg⁻¹) compared with the dark treatment (9.65 µmol kg⁻¹), reducing pH, Ωarag, and Ωcalc. By the end of this phase, irradiated plastic reached pH = 7.6, Ωarag = 2.16, and Ωcalc = 3.25, corresponding to values associated with impacts on calcifying organisms and considered terminal for coral reef development. During the biotic phase, no significant changes were observed, likely due to limited dissolved organic carbon release, indicating that UV-driven abiotic processes, rather than microbial activity, predominated in CO₂ release. The observed chemical changes matched end-of-century projections under high-emission scenarios, highlighting that plastic pollution may intensify reductions in carbonate ion concentration and calcium carbonate saturation states, accelerating calcifier mortality and biodiversity loss.

Continue reading ‘Plastic pollution as a pathway to ocean acidification and disruption of the seawater carbonate system’

Inside the Extinction Envelope: a systemic review and meta-analysis of paleoclimate extinction markers with comments on the necessary array of last-threshold interventions

Published 21 October 2026 Science Leave a Comment
Tags: , , ,

Every element of the causal chain that produced the five largest mass extinctions of the last half-billion years is presently active in the Earth system. The rate of the modern perturbation exceeds every peer-reviewed paleoclimate reference case. A six-intervention portfolio, deployed together at wartime industrial scale beginning now, is the physically necessary and sufficient response. The window in which that portfolio remains fully effective closes between 2028 and 2040. The anthropogenic-versus-feedback tipping point is expected between 2035 and 2040; corrected for the at-least-order-of-magnitude higher rate of contemporary carbon release, loss of agency — the point at which coordinated intervention can no longer arrest the cascade — arrives 200 to 400 years after feedback engagement under sustained portfolio deployment, and collapses onto the tipping point itself under any scenario in which the portfolio is not deployed within the 2028–2040 window.

Continue reading ‘Inside the Extinction Envelope: a systemic review and meta-analysis of paleoclimate extinction markers with comments on the necessary array of last-threshold interventions’

Extreme compound events in the Agulhas Leakage

Published 21 October 2026 Science Leave a Comment
Tags: , , ,

Marine heatwaves (MHWs) and ocean acidity extremes (OAXs) are intensifying under anthropogenic climate change, and their compound co-occurrence can amplify ecological impacts. Yet the Agulhas Leakage, a key gateway transferring warm, saline Indian Ocean water into the Atlantic, remains understudied. Here we characterise MHWs over 1982–2024 and OAXs, and their compound events in this region over 1982–2021, comparing analyses of original and linearly detrended data. Under a fixed baseline, MHW cumulative intensity rose from approximately 29.95 to 109.51 °C-year in the original data and 49.4 to 66.7 °C-year after detrending between the first and fourth decades. OAX intensity increased from approximately 0.24 to 4.10 nmol kg–¹-year in the original data and from 0.35 to 0.46 nmol kg–¹-year after detrending. Compound events emerge only after the 2000s. Detrending reveals that most of this increase reflects the long-term warming and acidification trends, while residual variability remains in the dynamically active Agulhas Retroflexion, where anticyclonic eddies trap warm, high [H+] Indian Ocean waters. A likelihood multiplication factor confirms statistically significant positive MHW–OAX dependence that persists after detrending, indicating statistically significant positive co-occurrence between MHW and OAX on interannual timescales, consistent with physical coupling through carbonate chemistry. Baseline choice critically shapes compound-extreme risk assessment.

Continue reading ‘Extreme compound events in the Agulhas Leakage’

Carry-over effects of low salinity during embryonic development modulate larval responses to combined salinity-pH stress in an estuarine crab

Published 21 October 2026 Science Leave a Comment
Tags: , , , , , , , ,

Early life stages of estuarine organisms are exposed to concurrent environmental stressors, but the extent to which embryonic conditions shape larval responses to multiple stressors remains largely unexplored. We evaluated whether salinity during embryogenesis modulates larval responses to combined salinity and pH stress in the estuarine crab Neohelice granulata. Embryos were reared at two salinities (15 and 33), and larvae were subsequently exposed to combinations of pH (8 and 6.9) and salinity (15 and 33). Salinity during embryogenesis did not affect development duration or eye size, but altered other embryonic traits: embryos at low salinity showed higher heart rate, larger egg volume, and increased egg mass at late stages. In larvae, salinity was the main driver, strongly affecting development, survival, and metabolic performance, whereas pH alone had limited or stage-dependent effects. However, their interaction intensified responses, particularly increasing mortality. Low salinity during the larval stage increased intermolt duration and mortality, effects further exacerbated under low pH. The strongest negative responses occurred under combined low salinity and low pH, with delayed development, higher mortality, and reduced oxygen consumption rates. Although low salinity during embryogenesis influenced larval performance under low pH, larval responses were primarily driven by current environmental conditions. These results highlight that co-occurring stressors can outweigh early-life conditioning. Given that low salinity events and acidification frequently co-occur in estuarine systems, their interaction is critical for understanding organismal responses.

Continue reading ‘Carry-over effects of low salinity during embryonic development modulate larval responses to combined salinity-pH stress in an estuarine crab’

Present but overlooked: biogenic acidification in aquaculture waters and its implication for mollusc mariculture

Published 21 October 2026 Science Leave a Comment
Tags: , , , , , , , ,

Mollusc mariculture, a critical global source of high-quality protein, is increasingly threatened by seawater acidification. While climate-driven ocean acidification (OA) has been widely studied, intensive aquaculture systems face an additional, locally exacerbated phenomenon: biogenic acidification. In this review, we comprehensively compare biogenic acidification with OA and other seawater acidification types, highlighting its occurrence across various aquaculture systems and its capacity to induce conditions more corrosive than end-of-century OA projections under densely stocked settings. Driven by the respiration and calcification of high-density mollusc populations, biogenic acidification leads to distinct alterations in the carbonate chemistry of mollusc farming systems—notably a reduction in total alkalinity (TA)—that are mechanistically different from OA. We further discuss how biogenic acidification imposes stronger physiological stresses on molluscs, impairing calcification, growth, and energy allocation, and how it synergistically interacts with climate change. Finally, we propose practical mitigation strategies, including TA supplementation and integrated multi-trophic aquaculture, to enhance the resilience and sustainability of mollusc farming. This review underscores the necessity to address biogenic acidification as a distinct and ongoing challenge in global mariculture.

Continue reading ‘Present but overlooked: biogenic acidification in aquaculture waters and its implication for mollusc mariculture’

The impact of the CO2 fertilization effect in seagrasses: a comparative perspective with terrestrial plants

Published 20 October 2026 Science Leave a Comment
Tags: , , , , , , , , , ,

This article comments on:

Pazzaglia J, Marín-Guirao L, Ambrosino L, Pes K, Costa M, Barrote I, Silva J, Procaccini G. 2025. Handling the heat: ocean acidification mitigates the effects of marine heatwaves on Posidonia oceanica seedlings. Journal of Experimental Botany 76, 6958–6973. https://doi.org/10.1093/jxb/eraf276.

Seagrass meadows are among the world’s most ecologically and economically important marine ecosystems. Although they cover only 0.1% of the seafloor, they sequester carbon at rates rivalling tropical rainforests, protect coastlines, and support marine biodiversity (do Amaral Camara Lima et al., 2023). Yet they are declining globally due to anthropogenic pressures including coastal development, pollution, and climate change (Waycott et al., 2009; Dunic et al., 2021). While ocean acidification and ocean warming are pervasive stressors under accelerating global change, Pazzaglia et al. (2025) have demonstrated that elevated dissolved CO2 may enhance seagrass resilience by increasing thermal tolerance in Posidonia oceanica seedlings through the CO2 fertilization effect.

Continue reading ‘The impact of the CO2 fertilization effect in seagrasses: a comparative perspective with terrestrial plants’

Subscribe

Search

  • Reset

OA-ICC Highlights

Resources