Call for abstracts: The Ocean in a High CO2 World Symposium

Published 5 March 2026 Events Leave a Comment

The Call for Abstracts is now open. Please submit your abstract no later than 1 April 2026 (any time zone). Full submission guidelines are provided below.

A limited number of early acceptances are available for applicants with time‑sensitive funding requirements. To request early consideration, please email highco2@confer.co.nz with your abstract submitted through the online form and a brief explanation of why early approval is needed.

Abstracts are invited that align with the themes and special sessions listed below. Details of confirmed special sessions are available here.
During submission, authors should select the theme or special session that best matches their abstract.

SUBMIT YOUR ABSTRACT

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Colony formation sustains the global competitiveness of nitrogen-fixing Trichodesmium under ocean acidification

Published 5 March 2026 Science Leave a Comment
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Anthropogenic carbon dioxide emissions drive ocean acidification. Trichodesmium, a key marine nitrogen-fixing cyanobacterium, displays contrasting growth responses to ocean acidification across morphotypes: negative in filamentous free trichomes but neutral or positive in colonies. However, lacking mechanistic understanding for these discrepancies has impaired our ability to predict Trichodesmium’s ecophysiological response. Here, we develop ecophysiological models to underpin mechanisms behind these divergent responses. For free trichomes, ocean acidification reduces nitrogen-fixing enzyme activity and photosynthetic energy production. In colonies, however, it alleviates copper and ammonia toxicity within the microenvironment—likely synergizing with enhanced iron acquisition—thereby outweighing minor benefit from relieved inorganic carbon limitation in the colony center. Projections suggest that globally, ocean acidification will reduce nitrogen fixation of trichomes by 16 ± 6% but increase that of colonies by 19 ± 24% within this century. By resolving morphotype-specific mechanisms, our study clarifies Trichodesmium’s adaptive strategies for sustaining its competitiveness and biogeochemical impacts in the changing ocean.

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Synthesis of data products for ocean carbonate chemistry

Published 5 March 2026 Science Leave a Comment
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As the largest active carbon reservoir on Earth, the ocean is a cornerstone of the global carbon cycle,
playing a pivotal role in modulating ocean health and the Earth’s climate system. Understanding these crucial
roles requires access to a broad array of data products documenting the changing chemistry of the global ocean
as a vast and interconnected system. This review article provides an overview of 68 existing ocean carbonate
chemistry data products and data product sets, encompassing compilations of cruise datasets, derived gap-filled
data products, model simulations, and compilations thereof. It is intended to help researchers identify and access
data products that best align with their research objectives, thereby advancing our understanding of the ocean’s
evolving carbonate chemistry. The list will be updated periodically to incorporate new data products. The most
up-to-date list is available at https://oceanco2.github.io/co2-products/ (Gregor and Jiang, 2026).

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Guest column: the world’s largest bank faces liquidation

Published 5 March 2026 Media coverage Leave a Comment

Ocean protection is too often treated as a moral issue, yet this conceals a harder truth: our oceans are vital economic systems under mounting pressure. In fact, if they knew what was good for them, every mercenary across the planet would want to protect our great blue expanse.

In many ways, the ocean operates like the world’s largest bank. Storing capital by preserving marine biodiversity, upholding food systems, and generating returns through fisheries, eco-tourism and coastal protection. Perhaps most importantly, it absorbs 30% of carbon dioxide (CO₂) emissions annually, protecting us and the global economy, at least in part, from our own polluting activities.

As the ocean’s investors, however, we are not making smart financial decisions. 

Overfishing, bottom trawling, and pollution reflect a familiar pattern: prioritising short-term extraction over long-term economic resilience. We are running down natural capital while congratulating ourselves on marginal gains. Yet the greatest financial threat to the ocean economy is still widely misunderstood and dangerously undervalued.

That threat is ocean acidification. 

The short-term, short-sighted mindset

For years, we have hugely overstated the capacity of blue carbon habitats such as seagrasses, mangroves and saltmarshes, to solve our emissions problem. These ecosystems are rightly celebrated for their ability to lock away carbon and support biodiversity, but they are too often framed as quick wins – assets that can be restored or offset on short timelines.

In reality, while their capacity to store carbon is exceptional, the rate at which they absorb it is slow. The habitats that hold the greatest carbon stocks – and provide the strongest protection – are typically ancient, intact systems that have accumulated value over centuries. In economic terms, these ecosystems function less like high-yield savings accounts and more like environmental pensions. They deliver steady, compounding returns, but only if they are safeguarded and invested in over decades. 

The lesson is clear. Even when we act in the ocean’s favour, we often do so through a short-term lens – one that favours visible, measurable gains over long-term stability.

Ocean acidification exposes the flaw in this thinking.

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High vertical resolution measurements of pH, pCO2, total alkalinity, and dissolved inorganic carbon using a new approach: the carbonate profiler

Published 4 March 2026 Science Leave a Comment
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The equilibrium between the different parameters of the marine carbonate system–dissolved inorganic carbon (DIC), total alkalinity (TA), partial pressure of CO2, and pH–is the core of ocean acidification studies, evaluation of inorganic carbon inventory, and air-sea CO2 fluxes. To date, it has been challenging to simultaneously measure all those components in the water column due to different sampling methodologies, and especially in stratified waters, where sharp vertical biogeochemical gradients may occur. In this study, we designed a low-cost and easy-to-assemble pumping system, which, combined with a CTD profiler, makes a PUMP-CTD system that can efficiently serve as a precise water column sampler, allowing for simultaneous measurements and sampling of dissolved inorganic carbon, total alkalinity, partial pressure of CO2, and pH with high vertical resolution. Importantly, this water sampler (denoted as the carbonate profiler) can be easily integrated with equilibrator-based continuous pCO2 measurement systems, which are routinely used for underway data acquisition, making them suitable for water column sampling as well. We tested the carbonate profiler in the open ocean water column, where we obtained excellent consistency between measured pCO2 and calculated values based on pH and DIC. Afterwards, we tested the operability of the system by measuring the vertical variability of all the components of the marine carbonate system in the Vistula River estuarine waters (southern Baltic Sea) and within the Arctic fjords affected by continental freshwater runoff. Overall, this system performed outstandingly, with a vertical resolution of half a meter, proving its utility in accurately measuring steep biogeochemical changes in the water column regardless of the analytical method used.

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Modelling seawater pCO2 and pH in the Canary Islands region based on satellite measurements and machine learning techniques

Published 4 March 2026 Science Leave a Comment
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Recent advancements in remote sensing systems, combined with new machine-learning model-fitting algorithms, have enabled the estimation of seawater carbon dioxide partial pressure (pCO2,sw) and pH (pHT,is) in the waters around the Canary Islands (13–19° W; 27–30° N). Continuous time-series data collected from moored buoys and Voluntary Observing Ships (VOS) between 2019 and 2024 were used to train and validate the models, providing a robust observational basis for satellite-derived estimates.

Among all models tested, bootstrap aggregation (bagging) performed best, achieving an RMSE of 2.0 µatm (R2>0.99) for pCO2,sw and 0.002 for pHT,is. Multilinear regression (MLR), neural networks (NN) and categorical boosting (CatBoost) also showed good predictive skill, with RMSE values between 5.4 and 10 µatm for pCO2,sw (360–481 µatm) and 0.004–0.008 for pHT,is (7.97–8.07). Using the most reliable model, we identified an increasing trend in pCO2,sw of 3.51±0.31 µatm yr−1, exceeding the atmospheric CO2 growth rate (2.3 µatm yr−1), alongside an acidification trend of −0.003 ± 0.001 yr−1.

Over the 2019–2024 period, rising atmospheric CO2 and increasing sea surface temperatures (reaching up to 0.2 °C yr−1 during the unprecedented 2023 marine heatwave) likely contributed to these trends. The Canary Islands region shifted from a weak CO2 source (0.90 Tg CO2 yr−1) in 2019 to 4.5 Tg CO2 yr−1 in 2024. After 2022, eastern sites that previously acted as annual CO2 sinks became net sources.

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Integrated ocean carbon research: a vision primed for implementation

Published 4 March 2026 Newsletters and reports Leave a Comment
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Executive Summary

The mission of the ‘Integrated Ocean Carbon Research’ (IOC-R) programme is to enhance our understanding of the ocean as a changing sink for human-produced CO2 and its climate change mitigation capacity, as well as the vulnerability of ocean ecosystems to increasing CO2 levels. The IOC-R programme aims to provide an actionable foundation for addressing the challenges of ocean carbon research. In doing so, it is contributing to the objectives of the United Nations (UN) Decade of Ocean Science for Sustainable Development by integrating the latest scientific findings and observational data for ocean carbon.

Supported by interdisciplinary research, the understanding of the ocean carbon cycle has advanced significantly since the last release of a report from the IOC-R community (IOC of UNESCO, 2021; Sabine et al., 2024). However, major knowledge and observational gaps remain, leading to considerable uncertainties in model projections. These hamper the development of climate change adaptation and mitigation strategies, including those involving ocean based solutions.

The IOC-R programme itself is co-sponsored by five international research and coordination programmes which have a strong involvement and focus on ocean carbon (Global Carbon Project1, SOLAS2, IMBeR3, CLIVAR4and IOCCP5) and the Intergovernmental Oceanographic Commission of UNESCO (IOC)6.

This IOC-R report is a global community effort with 72 authors and 13 reviewers from 23 countries. The report aims to guide the scientific focus of these programmes, as well as GOOS7, and to highlight new global cross-cutting priorities of ocean carbon research that help national and international ocean science funding entities determine future areas of investment. It will accomplish this by identifying knowledge gaps and coordinated research approaches to increase understanding about the ocean carbon cycle in a changing world.

The IOC-R community has defined five focus areas for ocean carbon research (Figure ES1), which will be further developed and explained in the report (Section 3):

  1. Evolution of the ocean carbon sink under a changing climate,
  2. The changing role of biology in the ocean carbon cycle,
  3. Carbon exchanges across the land-ocean-ice continuum,
  4. The impact of ocean industrial processes on the ocean bio logical carbon cycle,
  5. Future changes in the carbon cycle from deliberate ocean-based climate interventions.

…

5.b Capacity development

Among the organizations supporting integrated ocean carbon research, nine programmes and organizations, including science networks and programmes, Ocean Decade activities and UN organizations were identified as having a specific mandate in capacity development (Table 1). Many of these focus on human and technical capacity development, as well as awareness raising. However, only a few organizations put emphasis on research policies.

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Physics-guided machine-learning forecasting and analysis of carbonate changes in the surface Western Mediterranean

Published 3 March 2026 Science Leave a Comment
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Highlights

  • Physics-guided ML forecasts surface pCO2 and pH along a Western Mediterranean VOS line.
  • Day-ahead pCO2 is predicted with μatm-level RMSE; pH behaves nearly deterministically.
  • Boosted trees and sequence models retain skill under strict, deployable forecast conditions.
  • Explainable AI recovers dominant thermal control and air–sea CO2 gradient drivers.
  • Improved pCO2 forecasts directly reduce uncertainty in air–sea CO2 flux estimates.

Abstract

We introduce a hybrid, physics-guided machine-learning system for forecasting and explaining surface marine carbonate changes along a fixed Volunteer Observing Ship route between Gibraltar and Barcelona from 2019 to 2024. The dataset includes more than 90 high-frequency transects collected under ICOS/SOOP standards, containing underway pCO2/fCO2, pH (measured and derived), sea-surface temperature, and salinity. After applying consistent quality control and harmonizing the data in time and space, we combine physics-based carbonate diagnostics—such as the thermal/non-thermal decomposition (FASS) and first-order Taylor attribution of temperature, salinity, total alkalinity, and dissolved inorganic carbon sensitivities—with time-aware models including linear regressions, boosted trees, and sequence networks (1-D CNNs and LSTMs) trained on historical windows. We evaluate generalization and uncertainty through chronological splits, leave-one-year-out tests, and year-wise bootstrap sampling. With all current predictors available, day-ahead pH and pCO2 predictions reach near-optimal skill; pH behaves almost deterministically, while pCO2 achieves RMSE on the order of a few μatm. Even under stricter forecast conditions without real-time carbonate chemistry, boosted trees and sequence models maintain strong performance by exploiting persistence and seasonal timing. Model-explanation tools (SHAP, partial dependence) recover the expected carbonate drivers, highlighting dominant thermal effects and key roles of seawater CO2 state and air–sea gradients. Spatial–temporal diagnostics reveal amplified summer pCO2 peaks in the Alboran/northern Morocco region and out-of-phase pH patterns. Predicted fields are converted to air–sea CO2 flux using standard solubility and gas-transfer formulations, and propagated uncertainties show that improving pCO2 accuracy directly reduces flux uncertainty. The resulting air–sea CO2 fluxes exhibit a pronounced seasonal cycle, with summer outgassing reaching several mmol m-2 d-1 and winter uptake of comparable magnitude along the transect, while interannual variability dominates over 2019–2024 and no statistically robust long-term trend is detected; typical flux uncertainties are on the order of 0.1–0.2 mmol m-2 d-1. Altogether, this delivers an explainable, uncertainty-aware system ready for deployment, linking forecast skill to process understanding and CO2 exchange in a climate-sensitive corridor.

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Interactive effects of ocean acidification and settlement biofilm on the early development of the European abalone Haliotis tuberculata

Published 3 March 2026 Science Leave a Comment
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Highlights

  • Interactive effects of OA and settlement biofilm were investigated on juvenile abalone.
  • Post-larval density and total length decreased significantly under lower pH.
  • Biofilm composition induced indirect effects through changes in diatom biomass.
  • (pH × Ulvella) interaction affected abalone shell resistance and colouration.

Abstract

Ocean acidification (OA) and associated shifts in carbonate chemistry represent major threats to marine organisms, particularly calcifiers. OA effects can be influenced by other environmental variables, including the biotic environment. This study investigated the effects of OA and algal density, acting through an Ulvella-conditioned settlement biofilm, on post-larval and juvenile abalone (Haliotis tuberculata). In a three-month full factorial experiment, abalone were exposed from metamorphosis onward to two pH conditions (ambient 8.0 and reduced 7.7) and two initial densities of the green alga Ulvella lens on settlement plates. Biofilm biomass and composition were characterised using spectral reflectance and HPLC pigment analysis. Biological (density, length), physiological (respiration rate), behavioural (hiding response) and shell parameters (colour, surface corrosion, strength) of abalone were measured. Biofilm biomass and composition assessed with pigment proxies remained relatively stable under both pH conditions, though greater variability in algal biomass occurred at low initial Ulvella density. Post-larval density and total length decreased significantly under low pH, while high Ulvella density reduced juvenile length at 80 days, likely due to competition between algal groups. A pH × Ulvella interaction affected shell fracture resistance and colouration, but not metabolism or behaviour, indicating that juvenile abalone maintained vital functions. Overall, the results confirm the sensitivity of early H. tuberculata stages to moderate OA (−0.3 pH unit) and highlight indirect macroalgal effects through changes in diatom cover. In natural environment, the capacity of abalone to cope with future OA will depend on complex trade-offs between direct acidification effects and food-related biotic interactions.

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Neglecting organic alkalinity introduces greater error than assuming boron to salinity ratios in Arctic sea ice brine carbonate system calculations

Published 3 March 2026 Science Leave a Comment
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While total alkalinity (AT) is traditionally attributed to dissolved inorganic constituents, dissolved organic matter (DOM) can significantly contribute to AT as organic alkalinity (OrgAlk), introducing errors in calculated carbonate parameters, such as the CaCO3 saturation state (Ω) and partial pressure of CO2 (pCO2). This study presents measurements of OrgAlk in the Arctic Ocean sea ice system and assesses its influence on carbonate speciation, with OrgAlk contributing 0.1–1.0% to AT. Sea ice brine exhibited elevated DOM and OrgAlk, with an OrgAlk/DOC ratio of 0.13 ± 0.06 µmol kg− 1 µM− 1, consistent with global ocean values. Correcting AT for OrgAlk increased computed pCO2 up to 84 µatm and decreased Ω ≤ 0.2 for aragonite and ≤ 0.3 for calcite compared to un-adjusted values. Elevated brine pCO2 suggests that conventional estimates of Arctic sea ice CO2 uptake may be overestimated when AT is used as an input parameter, particularly in spring as OrgAlk is released. The omission of OrgAlk contributed greater errors to calculated carbonate parameters than the differences in boron from using direct measurements versus salinity based ratios, highlighting the necessity of accounting for even minor OrgAlk to refine predictions of surface pCO2, net air-sea CO2 flux, and the fate of CaCO3 minerals.

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Persistence of coral reef structures into the twenty-first century

Published 2 March 2026 Science Leave a Comment
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Coral reefs provide important socioecological services but are vulnerable to climate change, which shifts the balance between the production and erosion of calcium carbonate (CaCO3). In this Review, we summarize understanding of reef accretion, describe the mechanisms of carbonate production and erosion, and consider the effects of future ocean warming and acidification on key reef-building and eroding taxa. The combined stressors of climate change substantially reduce net carbonate production, with a more pronounced effect on calcifying algae than corals. However, declining coral cover driven by marine heatwaves and mass bleaching will probably be the dominant determinant of future reef carbonate budgets, and thus only reefs with thermally adapted populations are predicted to maintain the ability to sustain positive CaCO3 production under climate change, even if calcareous algal cover increases. As carbonate budgets become net negative in the future, the longevity of pre-existing reef frameworks remains unknown and understudied owing to the timescales required to meaningfully assess framework removal rates. Improving estimates of the rates of biologically driven framework loss and chemical dissolution will also be important in better predicting future reef persistence. Key knowledge gaps exist in understanding the effects of deoxygenation on coral reefs, as well as the influence of climate change on understudied sediment-producing taxa such as foraminifera and tropical molluscs.

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Ocean acidification and changes in biological production in the western subarctic region of the North Pacific over the quarter century, 1999–2023

Published 2 March 2026 Science Leave a Comment
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Changes in the physical and biogeochemical conditions of the ocean over time can affect marine ecosystems. In this study, we use biogeochemical observational data for the past 25 years (1999–2023) to investigate ocean acidification and changes in biological production at site K2 (47˚ N, 160˚ E) in the western subarctic region of the North Pacific Ocean. During this period, satellite-derived sea surface temperatures increased at a rate of 0.056 °C yr–1, while the surface mixed-layer salinity decreased by 0.004 yr−1. As a result of the oceanic uptake of anthropogenic CO2 from the atmosphere, the deseasonalized annual mean surface mixed-layer pH and saturation states of calcium carbonate minerals of calcite and aragonite decreased at rates of 0.0013 ± 0.0004, 0.007 ± 0.003, and 0.004 ± 0.002 yr−1, respectively. These rates are consistent with those calculated for winter. Under these acidification conditions, no significant trends were observed in either the annual mean or winter concentrations of nutrients (phosphate, nitrate, and silicate), or in total alkalinity in the surface mixed layer. However, the decadal trends in nutrient concentrations show a significant increase in May and decrease in July. Net community production (NCP), which is an index of biological production, was estimated from differences in nutrient concentrations between winter and May or July. This analysis revealed significant decreasing trends in NCP from winter to May, followed by increasing trends from winter to July. The stoichiometric molar ratio of Si associated with the July NCP increase (P:N:Si = 1:15:55) is higher than the previously reported ratio (1:16:40). A significant decreasing trend in satellite-derived photosynthetically active radiation (PAR) was observed in May (0.20 ± 0.08 yr−1), which may be linked to reduced biological production during that month. This decrease may be offset by increased production in summer that is likely due to a shift in the timing of the diatom bloom. These findings highlight the effects of long-term changes of potential drivers of both atmospheric and deep oceanic origin on oceanic biological production.

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Pathways to adaptation for shellfish aquaculture on the U.S. West Coast

Published 2 March 2026 Science Leave a Comment
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Understanding how shellfish growers adapt to environmental and socioeconomic stressors is critical for food security, especially with growing impacts from climate change. However, we know relatively little about the supporting factors that lead shellfish growers who experience stressors to make adaptive choices. Through interviews conducted with US West Coast (California and Oregon) shellfish farm owners and managers (growers), we document environmental and socioeconomic stressors that growers experience and investigate whether they can adapt, react, or cope (ARC response) to these stressors. We further identify growers’ strategies for adaptation and link these strategies to theoretical adaptive capacity domains (ie, assets, flexibility, social organization, learning, agency, and governance) using qualitative comparative analysis (QCA). We found regulatory stressors were the most impactful to growers overall. These stressors caused financial burdens and time delays to operations for growers in both states. Ocean acidification and/or hypoxia (OAH) was the most frequently reported environmental stressor. Ocean acidification and/or hypoxia impacts include increased mortality and shellfish die-off events. Out of 125 responses to stressors, growers were able to adapt in just over half of stressor responses (54.4%). Agency, flexibility, learning, and social organization supported adaptation most frequently, while governance was employed the least. Growers responded with cope responses (35.2%) more frequently than react responses (10.4%). Growers combined adaptive capacity domains in various ways to adapt. For example, the adaptive capacity domain of agency was frequently employed, but almost always in combination with other adaptive capacity domains (eg, assets, governance, flexibility, and learning). This study demonstrates that US West Coast shellfish growers combine adaptive capacity domains in creative ways to form adaptive pathways and illuminates pathways to better support adaptive capacity in shellfish aquaculture.

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Range-extending fish become competitive dominants under ocean warming but not heatwaves or acidification

Published 27 February 2026 Science Leave a Comment
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Ocean warming is driving species range extensions into cooler regions. The direct physiological influence of warming on species performance can accelerate such extensions into novel ecosystems; however, indirect effects of invader–resident interactions in cooler regions may counter these positive effects. Here, we examined the foraging performance and densities of competing warm‐water and cool‐water fishes across a latitudinal temperature gradient spanning 1500 km from tropical to temperate reefs subjected to rapid ocean warming in the southern hemisphere, and across natural analogs of temperate, tropicalized, and acidified reef localities in the northern hemisphere, and during a severe marine heatwave at a temperate reef. While current levels of ocean warming have allowed the warm‐water fish to extend their ranges into temperate ecosystems at both hemispheres, their foraging performance was reduced at both the cold‐ and warm‐temperate reefs compared to the (sub)tropical reefs. However, at the (warmer) tropicalized reef, the warm‐water fish had higher foraging performance and maintained densities, even under extreme pH reduction, compared to the temperate reef. In contrast, the cool‐water species struggled at the warmer tropicalized and extreme reefs with reduced foraging performance and lower population densities compared to the temperate reef. Contrastingly, the severe heatwave experienced at the temperate reef did not alter the foraging behaviors of either species. We suggest that ocean warming boosts the foraging performance of the range‐extending warm‐water fish and impairs that of their cool‐water competitor at temperate reefs, irrespective of acidification and heatwaves, leading to a shift in dominance hierarchies on temperate reefs. We conclude that warming‐driven increases in foraging performance of the warm‐water species may alleviate foraging limitations and enhance its establishment at its leading range edges under climate change, to the detriment of its cool‐water competitors.

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The invisible engine of the oceans: marine microorganisms driving climate resilience and ecosystem stability: a literature review

Published 27 February 2026 Science Leave a Comment
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Marine microorganisms form the invisible foundation upon which ocean life depends. Despite their microscopic size, they regulate major biogeochemical cycles, sustain primary productivity, and play a decisive role in maintaining the balance and resilience of marine ecosystems. As climate change intensifies and marine pollution expands in scale and complexity, the responses of these microbial communities have become central to understanding the future of the oceans. This work explores the diversity of marine microorganisms and examines how rising sea temperatures, ocean acidification, physical oceanographic changes, and multiple pollution sources interact to reshape microbial structure and function. Current evidence shows that shifts in temperature and seawater chemistry can alter microbial metabolism, community composition, and ecological interactions, with far-reaching consequences for carbon cycling, nutrient availability, and food web dynamics. At the same time, chemical pollutants, plastics, heavy metals, and excess nutrients impose strong selective pressures, often disrupting microbial balance while also promoting the emergence of microorganisms capable of degrading contaminants. These dual responses highlight marine microbes as both sensitive indicators of environmental stress and active contributors to ecosystem recovery. By bringing together recent scientific insights, this study underscores the essential role of marine microorganisms in ocean ecosystem regulation and climate change adaptation and emphasizes the need to incorporate microbial processes more fully into ocean monitoring, climate modeling, and sustainable marine management efforts.

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Decadal biogeochemical predictions for the bottom marine environment of the Northeast U.S. Continental Shelf

Published 27 February 2026 Science Leave a Comment
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The Gulf of Maine and the surrounding Northeast U.S. Continental Shelf are experiencing rapid marine environmental change arising from complex regional dynamics that challenge near-term (1–10 years) predictive capabilities for valuable living marine resources. Here, using a high-resolution regional ocean model, we demonstrate skilful decadal forecasts of ocean bottom habitat characteristics including bottom temperature, dissolved oxygen (O2), pH and aragonite saturation state (Ωar). Bottom temperature and pH predictions show substantial skill driven primarily by radiatively forced warming and carbon uptake trends, while bottom O2 and Ωar predictions benefit more from initialization due to stronger internal variability. Retrospective forecasts successfully predicted observed historical changes in water masses and environmental properties, including recent cooling/freshening transitions driven by replacement of Warm Slope Water with Labrador Slope Water. This water mass variability also modulates biogeochemical conditions and ocean acidification buffering capacity, with our recent forecasts indicating that benefits from the expected respite from rapid warming might be tempered by challenges posed by rapid acidification. The demonstrated predictability of coupled physical-biogeochemical processes supports developing integrated prediction systems for climate-informed marine resource management.

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Physiology and survival of intertidal calcifiers in two contrasting upwelling systems

Published 27 February 2026 Science Leave a Comment
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Climate change alters the oceans’ temperature, pH, and oxygen concentration. These changes are expected to increase globally over the coming decades, affecting a wide range of marine organisms. Coastal upwelling zones, characterized by their high environmental variability, serve as ideal natural laboratories to study the potential impacts on marine organisms and ecosystems of temperature change, acidification, and ocean deoxygenation. The estimation of survival using capture‐mark‐recapture (CMR) data has been commonly applied to vertebrates, and to date, very few studies have been done on marine invertebrate organisms. In this study, we combined field CMR data and laboratory measurements to assess the physiological responses (metabolic rate and heart rate) and survival probability of individuals in two populations of intertidal mollusks, Chiton granosus and Scurria zebrina, in contrasting upwelling environments (i.e., semi‐permanent vs. seasonal). We found that (1) there are no differences between the two studied populations for heart rate in both species, (2) the S. zebrina population subjected to seasonal upwelling has a higher metabolism, (3) there are no differences in the calcification rate between the two studied populations of both species, and (4) survival is significantly higher in the semi‐permanent upwelling location for both species. Our findings highlight species‐specific responses to contrasting upwelling regimes, suggesting that phenotypic plasticity and survival differences may influence resilience under ongoing climate change.

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Seawater pH fluctuations during the Ordovician to Silurian transition: insights from δ11B records in carbonates

Published 26 February 2026 Science Leave a Comment
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Highlights

  • A positive δ11Bcarb excursion has been observed during the Hirnantian coinciding with Gondwana glaciation.
  • Seawater pH fluctuations during the OST are caused by declining atmospheric pCO₂, sea level fall and carbonate weathering.
  • The fluctuation of seawater pH exerted a crucial role in the climatic changes and biotic evolutions during the OST.

Abstract

Environmental changes during the Ordovician to Silurian transition (OST) and the cause of Late Ordovician Mass Extinctions (LOMEs) remain a subject of debate. This study presents the first continuous seawater pH record spanning the Late Ordovician and Early Silurian, based on carbonate boron isotope (δ11Bcarb) data obtained from a carbonate-dominated section in South China. Our results reveal predominantly stable δ11Bcarb values throughout the Late Ordovician and Early Silurian, punctuated by a positive δ11Bcarb excursion during the Hirnantian coinciding with Gondwana glaciation. The calculated seawater pH pattern indicates a generally low pH baseline across the OST, temporarily interrupted by a transient increase in surface ocean pH coinciding with the glacial episode. These pH fluctuations are interpreted to result from a combination of factors, including declining atmospheric pCO₂ levels, sea level changes, weathering of carbonate rocks, and decomposition of organic matter. This study suggests that the fluctuation of seawater pH exerted a crucial role in the climatic changes and biotic evolution during the OST. The enhanced carbonate weathering and increased seawater pH, together with sea level fall and a reduction in shelf area, likely contributed to the decreased net accumulation of carbonates and represented a negative feedback for the development of glaciation and cooling climate. Given that the living of organisms (e.g. brachiopod, conodont, sponge and radiolarian) was sensitive to the changes in seawater pH, if and how the seawater pH fluctuations affected the LOMEs still needs more detailed work in the future.

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Natural analogues of climate change can reveal fish responses across multiple levels of biological organisation

Published 26 February 2026 Science Leave a Comment
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Anthropogenic climate change is threatening ecosystem functionality and biodiversity globally. While significant research has been dedicated to understanding how organisms may respond to future climate change, most of these studies focus on individual levels of biological organisation in controlled laboratory settings, which often fail to capture the complexity of natural ecosystems. Organisms respond to climate stressors across various levels of biological organisation, which also involve complex interactions or feedback mechanisms among levels, making it difficult to generalise responses to climate change from laboratory experiments or single levels alone. Natural analogues provide a unique opportunity to observe complex ecological interactions in real-world environments with long-term exposure to climate change stressors. Here, we provide a systematic literature review to reveal how natural analogues of ocean warming and ocean acidification can be used to assess fish responses to climate change across multiple levels of biological organisation (from molecular to biogeographical scales) and to assess how cross-level buffering and feedback mechanisms may shape fish species persistence in a future ocean. We identify key knowledge gaps and propose research frameworks that integrate natural analogues with laboratory experiments, mesocosms, and predictive models to better capture the complexity of fish responses to climate stressors in a more holistic way. Finally, we highlight the importance of coordinated, cross-system research using multiple natural analogues to reveal adaptive mechanisms and strengthen predictions of fish community reorganisation under climate change.

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A standardised experimental setup for simulating ocean warming and acidification in benthic marine invertebrates

Published 26 February 2026 Science Leave a Comment
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Recent studies identify ocean warming and acidification as major drivers of ecological change in the Eastern Mediterranean, posing serious threats to marine biodiversity, particularly for sessile or low-mobility organisms that cannot escape unfavourable conditions. At the same time, the need for standardised experimental approaches capable of generating high-quality data on organismal responses to multiple climate stressors has become increasingly evident. This manuscript presents a fully detailed and replicable experimental framework for simulating ocean warming and acidification in benthic marine invertebrates under controlled laboratory conditions. Detailed protocols include the technical set-up, experimental design, selection of climate scenarios, monitoring procedures and criteria for species selection and demonstrating its application through a validation case study from the MACCIMO project.

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