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.
Continue reading ‘High vertical resolution measurements of pH, pCO2, total alkalinity, and dissolved inorganic carbon using a new approach: the carbonate profiler’Archive Page 5
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 ClosedTags: Arctic, Baltic, chemistry, field, methods
Modelling seawater pCO2 and pH in the Canary Islands region based on satellite measurements and machine learning techniques
Published 4 March 2026 Science ClosedTags: chemistry, modeling, North Atlantic, regionalmodeling
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.
Continue reading ‘Modelling seawater pCO2 and pH in the Canary Islands region based on satellite measurements and machine learning techniques’Integrated ocean carbon research: a vision primed for implementation
Published 4 March 2026 Newsletters and reports ClosedTags: policy
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):
- Evolution of the ocean carbon sink under a changing climate,
- The changing role of biology in the ocean carbon cycle,
- Carbon exchanges across the land-ocean-ice continuum,
- The impact of ocean industrial processes on the ocean bio logical carbon cycle,
- 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.
Physics-guided machine-learning forecasting and analysis of carbonate changes in the surface Western Mediterranean
Published 3 March 2026 Science ClosedTags: chemistry, Mediterranean, modeling, regionalmodeling
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.
Continue reading ‘Physics-guided machine-learning forecasting and analysis of carbonate changes in the surface Western Mediterranean’Interactive effects of ocean acidification and settlement biofilm on the early development of the European abalone Haliotis tuberculata
Published 3 March 2026 Science ClosedTags: biological response, communityMF, laboratory, mollusks, morphology, multiple factors, North Atlantic, performance, phytoplankton, reproduction, respiration
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.
Continue reading ‘Interactive effects of ocean acidification and settlement biofilm on the early development of the European abalone Haliotis tuberculata’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 ClosedTags: Arctic, biogeochemistry, chemistry, field, methods
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.
Continue reading ‘Neglecting organic alkalinity introduces greater error than assuming boron to salinity ratios in Arctic sea ice brine carbonate system calculations’Persistence of coral reef structures into the twenty-first century
Published 2 March 2026 Science ClosedTags: biological response, BRcommunity, corals, review
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.
Continue reading ‘Persistence of coral reef structures into the twenty-first century’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 ClosedTags: Arctic, biogeochemistry, chemistry, field, North Pacific
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.
Continue reading ‘Ocean acidification and changes in biological production in the western subarctic region of the North Pacific over the quarter century, 1999–2023’Pathways to adaptation for shellfish aquaculture on the U.S. West Coast
Published 2 March 2026 Science ClosedTags: fisheries, mitigation, North Pacific, socio-economy
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.
Continue reading ‘Pathways to adaptation for shellfish aquaculture on the U.S. West Coast’Range-extending fish become competitive dominants under ocean warming but not heatwaves or acidification
Published 27 February 2026 Science ClosedTags: biological response, field, fish, multiple factors, North Pacific, performance, temperature, vents
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.
Continue reading ‘Range-extending fish become competitive dominants under ocean warming but not heatwaves or acidification’The invisible engine of the oceans: marine microorganisms driving climate resilience and ecosystem stability: a literature review
Published 27 February 2026 Science ClosedTags: biological response, community composition, otherprocess, physiology, review
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.
Continue reading ‘The invisible engine of the oceans: marine microorganisms driving climate resilience and ecosystem stability: a literature review’Decadal biogeochemical predictions for the bottom marine environment of the Northeast U.S. Continental Shelf
Published 27 February 2026 Science ClosedTags: chemistry, modeling, North Atlantic, regionalmodeling
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.
Continue reading ‘Decadal biogeochemical predictions for the bottom marine environment of the Northeast U.S. Continental Shelf’Physiology and survival of intertidal calcifiers in two contrasting upwelling systems
Published 27 February 2026 Science ClosedTags: adaptation, biological response, field, laboratory, mollusks, morphology, mortality, otherprocess, physiology, South Pacific
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.
Continue reading ‘Physiology and survival of intertidal calcifiers in two contrasting upwelling systems’Seawater pH fluctuations during the Ordovician to Silurian transition: insights from δ11B records in carbonates
Published 26 February 2026 Science ClosedTags: chemistry, field, North Pacific, paleo
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.
Continue reading ‘Seawater pH fluctuations during the Ordovician to Silurian transition: insights from δ11B records in carbonates’Natural analogues of climate change can reveal fish responses across multiple levels of biological organisation
Published 26 February 2026 Science ClosedTags: biological response, field, fish, review, vents
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.
Continue reading ‘Natural analogues of climate change can reveal fish responses across multiple levels of biological organisation’A standardised experimental setup for simulating ocean warming and acidification in benthic marine invertebrates
Published 26 February 2026 Science ClosedTags: biological response, laboratory, Mediterranean, methods, mollusks, multiple factors, porifera, temperature
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.
Continue reading ‘A standardised experimental setup for simulating ocean warming and acidification in benthic marine invertebrates’Ocean acidification reduces diatom and photosynthetic gene abundance on plastic in an coastal bay mesocosm experiment
Published 25 February 2026 Science ClosedTags: abundance, biological response, BRcommunity, community composition, laboratory, mesocosms, molecular biology, North Pacific, otherprocess, phytoplankton, prokaryotes
Discarded plastics are accumulating in the global ocean and posing threat to marine life. The plastisphere – the community colonizing plastic surfaces – profoundly influences plastic’s environmental behavior, affecting its degradation and entry into marine food webs. Ocean acidification (OA) resulted from anthropogenic CO2 emissions, is also threatening marine ecosystems, but the effect of OA on the structure and ecological function of the plastisphere community remains poorly understood. Here, using a mesocosm experiment, we investigated the effects of OA on the plastisphere colonizing floating PET plastic bottles. The study was conducted using subtropical eutrophic coastal water from Southern China under two CO2 conditions: increased CO2 to 1000 μatm (HC) and ambient CO2 410 μatm (LC). Metagenomic sequencing of the plastic samples, after exposure for 32 days, showed striking changes in relative abundance of eukaryotes and bacteria caused by HC. There was a 75.3 % decrease in eukaryote read abundances at high CO2, most strikingly a 95.6% decrease in the relative abundance of diatoms. In addition, the relative abundance of genes involved in photosystem II light reactions and pigment synthesis decreased under high CO2 conditions. This suggests that OA could reduce the photosynthetic potential within the plastisphere. Shifts in plastisphere community structure and potentially diminished photosynthesis under OA could influence the food chains within plastisphere, plastic degradation, transportation, and carbon cycle involving plastics. Overall, our results suggest that OA can alter the functional ecology of the plastisphere, with potential implications for marine biogeochemical processes and food web dynamics in subtropical eutrophic coastal water.
Continue reading ‘Ocean acidification reduces diatom and photosynthetic gene abundance on plastic in an coastal bay mesocosm experiment’Ocean acidification modifies site fidelity and patterns of seagrass habitat use by a herbivorous fish
Published 25 February 2026 Science ClosedTags: algae, biological response, BRcommunity, field, fish, Mediterranean, morphology, performance, physiology, vents
Ocean acidification (OA), characterized by changes in seawater chemistry and a concomitant decline of pH due to the uptake by seawater of the atmospheric CO2, will profoundly shape marine ecosystems. The lower pH/higher pCO2 can act negatively (as a stressor for organisms with a calcareous exoskeleton) or positively (as a direct resource for primary producers like macrophytes). Consequently, herbivores may indirectly benefit from OA counteracting the direct negative effects of living under high pCO2/low pH conditions. Here, we investigated how OA may influence site fidelity, habitat use, and trophic behaviour patterns of Sarpa salpa, the main herbivorous fish associated with Posidonia oceanica meadows in the north-western Mediterranean Sea. We assessed if and how OA influences the habitat use of S. salpa by comparing natural tags, in otoliths and muscle tissues, between CO2 vents and reference pH sites. We did not find differences in otolith elemental composition and shape among fish exposed to different pH conditions (CO2 vent vs ambient pH sites). However, otolith isotopic signatures differed between life stages (young vs sub-adults), consistent with the variations observed in seawater-dissolved inorganic carbon across sites. Finally, comparisons of the nutritional value marine vegetation (macroalgae, P. oceanica, epiphytes) showed that P. oceanica and epiphytes were more nutritious at CO2 vents, along with increased consumption by S. salpa. This trophic separation indicates that S. salpa spent more time exploiting the trophic resources in the CO2 vents. Together, our findings shed new light on plant–herbivore interactions within P. oceanica meadows under future OA scenarios.
Continue reading ‘Ocean acidification modifies site fidelity and patterns of seagrass habitat use by a herbivorous fish’Climate change impacts on coral reefs and emerging resilience pathways: a systematic review
Published 25 February 2026 Science ClosedTags: biological response, corals, review
Highlights
- Rising temperatures, acidification, sea level rise and storms are accelerating coral bleaching and reef weakening worldwide.
- Review of 220 studies from 1996–2025 reveals major biodiversity loss and high risk of reef collapse under warming.
- The 2023–2025 global bleaching event impacted about 84 percent of reefs, the most severe on record.
- Coral gardening, larval restoration, assisted evolution and connected marine protected areas boost reef resilience.
- Emission cuts combined with local conservation, community stewardship and adaptive management are vital for reef survival.
Abstract
Coral reefs are one of the ecosystems that are most affected by climate change, but they also support biodiversity, coastal stability, fisheries, and tourism around the world. This review uses a structured narrative literature review based on PRISMA protocols to put together evidence from 220 peer-reviewed articles (1996 to 2025) to see how warming seas, ocean acidification, rising sea levels, and stronger storms change coral ecology, structure, and ecosystem functioning. The results indicate that heightened thermal stress is the principal catalyst of mass bleaching and mortality, occurring with greater frequency and at larger spatial scales, whereas ongoing acidification persists in diminishing calcification, skeletal density, and recruitment success. The rise in sea level and damage caused by storms make habitat loss happen even faster, make reefs less complex, and make communities of reef-associated species less stable. Even though things are going this way, new interventions like coral gardening, larval propagation, assisted evolution, marine protected areas, and community-led co-management show promise for making things more resilient in the face of future climate change. The review emphasizes the necessity of immediate global carbon reduction in conjunction with customized conservation and restoration strategies at the local level. If no strong action is taken, coral reefs may not last long, and the economic security they provide may also go down.
Continue reading ‘Climate change impacts on coral reefs and emerging resilience pathways: a systematic review’Plasticity and adaptation in a changing ocean: a review of research trends and challenges
Published 24 February 2026 Science ClosedTags: adaptation, biological response, otherprocess, review
Climate change and ocean acidification pose significant challenges to both terrestrial and aquatic ecosystems, making it critical to understand species’ vulnerability. Phenotypic plasticity and evolutionary adaptation are key mechanisms enabling organisms to cope with environmental shifts, with marine species appearing particularly susceptible. This semi-quantitative bibliometric review, conducted following PRISMA guidelines, examines research on climate change and ocean acidification impacts on marine organisms, focusing on plasticity and adaptation. We analysed 168 peer-reviewed articles published between 1995 and 2024 from Web of Science and Scopus. Publications remained low until 2013, then increased threefold, peaking in 2019, with the US, Australia, and China leading. Research predominantly addressed marine animals, especially fish, bivalves, and other invertebrates. Most studies focused on plasticity (57%) and examined molecular traits as response variables. Temperature, pH, and their combination were the most studied environmental drivers, whereas salinity and dissolved oxygen received little attention. Conceptual ambiguities in the use of plasticity and adaptation were noted. Our review highlights research gaps and emphasizes the need for integrated studies on plasticity and adaptation to better understand marine species’ vulnerability to climate change and ocean acidification and guide effective conservation and management strategies.
Continue reading ‘Plasticity and adaptation in a changing ocean: a review of research trends and challenges’
