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

Published 20 October 2026 Events Closed

Dates: 30 November – 11 December 2026

Location: IAEA Marine Environment Laboratories, Monaco.

Deadline for application through InTouch+ platform: 6 November 2026

The Winter School is organized by the IAEA OA-ICC in partnership with the Prince Albert II of Monaco Foundation through the OACIS Initiative (Ocean Acidification and other ocean Changes – Impacts and Solutions) and the Laboratoire d’Océanographie de Villefranche (LOV).

Introduction

Ocean acidification is a global environmental stressor that threatens marine life and the livelihoods of coastal communities. Ocean acidification is caused by increasing atmospheric carbon dioxide being absorbed by the ocean, resulting in changes to seawater carbonate chemistry, including a drop in pH. Due to global concerns about its consequences, ocean acidification is included in international policies such as Target 3 of UN Sustainable Development Goal (SDG) 14 and Target 8 of the Global Biodiversity Framework (GBF).

The IAEA’s Ocean Acidification International Coordination Centre (OA-ICC) supports IAEA Member States to minimize and adapt to OA and report towards SDG 14.3 and the GBF, with a strong focus on building capacity to study ocean acidification and related stressors and promoting international collaboration and coordination.

Ocean acidification is not happening in isolation, but in combination with other human-driven pressures, including pollution, warming, and oxygen loss. The impact of multiple ocean stressors on marine life and ecosystem function is not well understood, yet this information is crucial to inform adaptation strategies that might minimize negative effects on organisms, ecosystems, and associated socioeconomic benefits.

The Fourth Winter School on Ocean Acidification and Multiple Stressors is part of the capacity building program of the OA-ICC.  This two-week training course will provide participating scientists with a thorough understanding about key concepts and experimental design used to study the impacts of ocean acidification in the context of additional stressors.

Objectives

The aim of the Winter School is to train early-career scientists who already have experience researching ocean acidification on how to study acidification in the context of other co-occurring stressors. Through lectures and practical exercises in the laboratory, the students will gain understanding of key concepts in multiple-stressor research (e.g., What is a stressor? What is a mode of action? What is an interaction?), purposeful experimental design, and analysis of complex datasets. During the course, participants will collaborate on a joint laboratory experiment to elucidate the effects of three simultaneous drivers on marine organisms.

Target Audience

The course is open to 10-12 trainees. Priority will be given to early-career scientists with experience in marine environmental change with a focus on ocean acidification; a background in biological sciences is preferred. At least one publication in the field of marine environmental change is required.

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Participation and Registration

All persons wishing to participate in the event have to be designated by an IAEA Member State or should be members of organizations that have been invited to attend.

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

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

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

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

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

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

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

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

Selected participants will be informed in due course on the procedures to be followed with regard to administrative and financial matters.

Participants are hereby informed that the personal data they submit will be processed in line with the Agency’s Personal Data and Privacy Policy and is collected solely for the purpose(s) of reviewing and assessing the application and to complete logistical arrangements where required. The IAEA may also use the contact details of Applicants to inform them of the IAEA’s scientific and technical publications, or the latest employment opportunities and current open vacancies at the IAEA. These secondary purposes are consistent with the IAEA’s mandate.

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Additional Requirements

Participants should have a university degree in marine chemistry, biology, oceanography or a related scientific field, and should be currently involved in or planning to study the ecological impact of multiple stressors, including ocean acidification. Experience with the R software is strongly encouraged.

Selection will be based on merit and interest. Applications should include:

 * A motivation letter with a short description of the candidate’s research interests and how the course would benefit the applicant’s current or future research on ocean acidification and multiple stressors (max one A4 page)

  * CV with publication list

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

OA-ICC bibliographic database updated

Published 6 November 2026 Science Leave a Comment

An updated version of the OA-ICC bibliographic database is available online.

The database currently contains 10,104 references and includes citations, abstracts and assigned keywords. Updates are made every month.

The database is available as a group on Zotero. Subscribe online or, for a better user experience, download the Zotero desktop application and sync with the group OA-ICC in Zotero. Please see the “User instructions” for further details.

OA-ICC, 6 November 2026.

Delay-induced Hopf bifurcation in a coral-macroalgae system under carbon-driven acidification stress

Published 6 November 2026 Science Leave a Comment
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Ocean acidification can reduce coral growth, alter coral-macroalgae interactions, and weaken reef resilience. This study develops a delayed coral-macroalgae-acidification-pressure model describing live coral cover, fleshy macroalgal cover, and a dimensionless effective acidification-pressure index. The model incorporates coral-macroalgae overgrowth, external stress input, natural relaxation, macroalgal-associated attenuation, coral-associated feedback, and a delayed coral response to acidification pressure. We establish positivity and boundedness of solutions, determine biologically feasible equilibria, derive local stability conditions, and analyze the effect of delay on the coexistence state. The analysis identifies a critical delay at which the stable coexistence equilibrium loses stability through a Hopf bifurcation. For the baseline parameter set, the bifurcation is supercritical and generates a local branch of orbitally asymptotically stable periodic orbits. Numerical simulations, sensitivity analysis, and robustness tests support the analytical findings and show how coral stress sensitivity, external forcing, and reef-scale feedbacks influence stability thresholds and coral persistence. These results provide a mechanistic framework for examining how delayed ecological responses to acidification may promote oscillatory reef dynamics.

Continue reading ‘Delay-induced Hopf bifurcation in a coral-macroalgae system under carbon-driven acidification stress’

Effects of ocean acidification on the energetics and larval development of a coastal fish, the California grunion (Leuresthes tenuis)

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The burning of fossil fuels has increased atmospheric CO₂ at an unprecedented rate. The world’s oceans have absorbed much of this carbon dioxide, resulting in a decrease of pH and an increase in the partial pressure of CO2 in seawater in a process referred to as ocean acidification. Ocean acidification (OA) can cause a variety of detrimental effects on the physiology and ecology of larval fishes. Despite a preponderance of negative effects, studies of how OA affects the early life stages of fishes have produced mixed results and have tended to focus on a limited set of responses. In this study, I tested the effects of OA on energy intake, as measured by feeding rate, and energy expenditure, as measured by metabolic rate, then compared these results to growth and development in the California grunion (Leuresthes tenuis). I also created family groupings to analyze genetic variation underlying these responses. My pCO2 treatments ranged from a control with a central value of 550 μatm, followed by 1080 μatm, 1760 μatm, and 2820 μatm. Each experiment lasted for a period of 12 days, and I ran a total of 12 experiments. Within an experiment, measures of metabolic rate, feeding rate, growth, and development were conducted multiple times. Mortality rates were measured continuously. By analyzing the similarities in the responses of related larvae to CO2, I was able to estimate broad sense heritability’s for metabolic rate, feeding rate, growth, and mortality. I found that at 6-days post hatch, larvae developing in high CO2 conditions exerted significantly more energy on routine metabolic rate. This increase in energetic expenditure with CO2 was not matched by an increase in feeding. Paradoxically, however, growth in mass had a positive relationship with CO2. To explore the consequences of these results, I examined development via allometric analysis of organ growth. I found that the relative growth of the eyes and stomachs of larvae were significantly slower when larvae developed under high pCO2 conditions. Furthermore, I found that both growth and metabolic rates showed significant genetic variation in sensitivity to OA, suggesting considerable evolutionary potential in these traits. I also present evidence that maternal effects are highly influential within the first 6 days after hatch. Overall, my results suggest that OA can cause both an energy deficit and abnormalities in the development of California grunion. The developmental abnormalities observed may be a symptom of an allocation of resources that prioritizes growth at the expense of internal organ development. These changes are likely to have long-term effects on recruitment in natural populations. Additionally, our results suggest that there is appreciable standing genetic variation within the population for the phenotypes studied here.

Continue reading ‘Effects of ocean acidification on the energetics and larval development of a coastal fish, the California grunion (Leuresthes tenuis)’

A microRNA catalogue for red abalone larvae reveals developmental and acidification-associated abundance patterns

Published 6 November 2026 Science Leave a Comment
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Larval development in marine mollusks requires coordinated gene regulation and is particularly sensitive to ocean acidification, yet post-transcriptional regulation remains poorly characterized in non-model gastropods. We characterized the microRNA (miRNA) repertoire and respiratory response of red abalone (Haliotis rufescens) larvae reared at pH 8.0 and 7.6. Small-RNA sequencing was performed at the trochophore (24 h post-fertilization, hpf) and competent veliger (110 hpf) stages, with three biological replicates per stage and pH treatment, while oxygen consumption was measured at 24, 48, 60, and 110 hpf. Genome-anchored annotation identified 147 precursor loci encoding 117 distinct mature miRNA sequences, including 70 matching reference databases and 47 candidate novel miRNAs. The developmental stage was the predominant source of variation in miRNA abundance, with the first principal component explaining 87.3% of the variation, whereas acidification affected a comparatively small subset of miRNAs. Cumulative oxygen consumption from 24 to 110 hpf was 57% higher at pH 7.6 than at pH 8.0. Both intergenic and intragenic miRNAs contributed to the acidification-associated response, with no significant preferential representation of either genomic-origin class. Computational predictions link pH-responsive miRNAs to genes associated with aerobic metabolism, morphogenesis, biomineralization, chromatin regulation, and stress responses. Because these miRNA–target relationships are computational predictions and the physiological and molecular measurements were not biologically paired, they do not establish a direct regulatory relationship. These results provide the first larval miRNA catalogue for H. rufescens and identify developmental- and acidification-associated miRNA abundance patterns and candidate miRNA–target relationships for future functional validation.

Continue reading ‘A microRNA catalogue for red abalone larvae reveals developmental and acidification-associated abundance patterns’

Limited post-stress recovery and constrained physiological resilience: multi-biomarker evidence for metabolic trade-offs in a gastropod under ocean acidification

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Highlights

  • OA induces severe apoptosis of hepatopancreas cells in Brunneifusus ternatanus.
  • IBR index indicates partial but incomplete physiological restoration after recovery.
  • Transcriptomics reveals energy downregulation and immunity activation under OA stress.

Abstract

Ocean acidification (OA), driven by increasing atmospheric CO2 absorption, represents a critical environmental stressor that disrupts hepatopancreas function in aquatic organisms, particularly affecting metabolic homeostasis and immune competence. This study employed an integrated multi-biomarker approach combining histopathology, integrated biomarker response (IBR) indices, and transcriptomics to systematically investigate the effects of short-term (14 d), medium-term (28 d) CO2-driven acidification exposure and a subsequent recovery period on the whelk Brunneifusus ternatanus. Hepatopancreatic cells suffered progressive structural and functional damage during 14–28 d of acidification, characterized by reduced hemocyte counts, disruption of rough endoplasmic reticulum membranes, and obscured cell boundaries. During recovery, damage was attenuated yet persistent, manifesting as intracellular matrix edema, hemocyte rebound, and restored membrane integrity—but cell boundaries remained altered relative to controls. The IBR index (integrating oxidative stress markers and hepatopancreas function enzyme indices) increased continuously during early and medium exposure, then decreased significantly during recovery yet remained elevated above control levels, indicating partial but incomplete physiological restoration. Transcriptomic analysis revealed time-specific molecular reprogramming: energy metabolism and mitochondrial function pathways were downregulated during early acidification and recovery stages, whereas medium-term exposure significantly activated immunity- and metabolism-associated pathways. These findings demonstrate that B. ternatanus mounts vigorous physiological regulatory responses to OA stress at a demonstrable energetic cost, characterized by immune-metabolic trade-offs and sustained metabolic reprogramming even after stress removal. This study provides evidence for assessing OA impacts on gastropod mollusks and contributes to predictive frameworks for evaluating marine ecosystem vulnerability under climate change.

Continue reading ‘Limited post-stress recovery and constrained physiological resilience: multi-biomarker evidence for metabolic trade-offs in a gastropod under ocean acidification’

Drivers of biogenic acidification in oyster cultivation waters: macroalgal photosynthesis raises pH and carbonate saturation state, but not total alkalinity

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Highlights

  • Oyster respiration and calcification jointly deplete seawater alkalinity and buffering capacity.
  • High stocking density and low water exchange intensify biogenic acidification.
  • Biogenic acidification reduces short-term CO2 excretion and calcification rates in oysters.
  • Macroalgal photosynthesis raises pH and Ωcal but not the total alkalinity consumed by calcification.

Abstract

Biogenic acidification is a growing concern in large-scale bivalve aquaculture. To investigate its drivers and mitigation strategies, oysters were incubated in a continuous flow-through system with five chambers in series to simulate upstream-to-downstream water flow in a large-scale long-line oyster aquaculture system. Four stocking densities (1, 3, 6, and 9 ind. Chamber−1) and three water exchange rates (3.6, 5.4, and 7.2 L h−1) were tested. The mitigation potential of macroalgal photosynthesis was then evaluated. Results showed that biogenic acidification was observed in experimental waters and higher oyster stocking density intensified seawater acidification, with downstream chambers exhibiting more pronounced acidification than upstream chambers. Compared with the blank control, the terminal chamber at the highest density showed a pH decrease of 0.85 units, a pCO2 increase of 2698 μatm, and decreases in total alkalinity (TA) and TA − DIC of 333 and 349 μmol kg−1, respectively. Lower water exchange rate also exacerbated biogenic acidification. In the terminal chamber at the lowest water exchange rate, pH decreased by 0.52 units, pCO2 increased by 976 μatm, and TA and TA − DIC decreased by 140 and 188 μmol kg−1, respectively. Negative effects were observed: correlation analysis revealed a significant negative correlation between seawater pCO2 and the weight-specific CO2 excretion rate (P < 0.05), alongside a significant positive correlation between Ωcal and the weight-specific calcification rate (P < 0.05). Adding Ulva Lactuca L. to the acidified seawater progressively raised pH (7.75 to 8.06) and Ωcal (2.3 to 4.3) and lowered pCO2 (1306 to 585 μatm) over five days, approaching ambient levels, whereas TA remained at its post-acidification level despite a DIC drawdown of 133 μmol kg−1. CO2 removal therefore raises the pH and saturation -state caused by biogenic acidification but not the TA deficit, indicating that TA must be included when the mitigating effect of macroalgal photosynthesis is evaluated and that supplementary alkalinity sources may be required in large-scale bivalve aquaculture.

Continue reading ‘Drivers of biogenic acidification in oyster cultivation waters: macroalgal photosynthesis raises pH and carbonate saturation state, but not total alkalinity’

Relative resistance of estuarine dimethyl sulfide production to ocean acidification in the Yangtze river estuary

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Dimethyl sulfide (DMS) is a climatically important sulfur gas, yet its response to ocean acidification in estuarine systems remains poorly constrained. Here, we combined three seasonal field surveys with ship-based microcosm experiments in the Yangtze River Estuary and adjacent coastal waters to resolve spatial variability in DMS cycling and assess responses to declining pH. DMS concentrations and cycling rates showed pronounced seasonal variability, remaining broadly comparable in spring and autumn but reaching maxima in summer. During the wet season, mean sea-to-air DMS fluxes estimated using two gas-transfer parameterizations were 11.5–14.3 μmol m−2 d−1, approximately 1.8–2.2 times the global ocean mean. Across all seasons, estuarine waters exhibited lower pH than adjacent coastal waters, yet DMS concentrations showed no corresponding decline. Along the pH gradient, coastal waters exhibited significant positive relationships between pH and chlorophyll a, DMS concentration, DMS accumulation rate, and DMS yield, whereas these relationships were largely absent in the estuary. The microcosm experiments further confirmed this contrast, with pH reductions of 0.2–0.4 units significantly decreasing chlorophyll a, particulate and dissolved dimethylsulfoniopropionate, and DMS in coastal waters by 11.9%–31.2%, 10.9%–24.6%, 13.0%–32.1%, and 13.9%–42.4%, respectively, but producing little response in estuarine waters. These results reveal that DMS production in the Yangtze River Estuary exhibits relative resistance to pH declines of 0.2–0.4 units across all three seasons investigated, suggesting that natural pH variability and environmental exposure history may modulate acidification responses.

Plain Language Summary

Dimethyl sulfide (DMS) is a naturally produced sulfur gas in seawater that can influence clouds and climate after being emitted to the atmosphere and oxidized to form sulfate aerosols. Previous studies have suggested that ocean acidification may reduce marine DMS production, but most evidence has come from open-ocean or relatively stable coastal environments. Here, we combined seasonal field surveys in spring, summer, and autumn with ship-based acidification experiments in the Yangtze River Estuary and adjacent coastal waters to examine how DMS production responds to declining pH. In the adjacent coastal waters, lower pH was associated with reduced phytoplankton biomass and lower DMS concentrations, and experimental acidification further suppressed DMS production. In contrast, DMS and related processes in the estuary showed limited responses to comparable pH reductions. These results demonstrate a marked difference in sensitivity to ocean acidification between the estuarine and adjacent coastal waters of the Yangtze River Estuary. Given the relative resistance of DMS production observed in estuarine waters, the contribution of the Yangtze River Estuary to future ocean-atmosphere sulfur exchange may remain relatively stable under moderate acidification.

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Dual stress of ocean acidification and sulfide: physiological adaptation mechanisms of the tropical seagrass Thalassia hemprichii

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Ocean acidification and sulfide intrusion are key environmental stressors affecting seagrass bed ecosystems. Although sulfide stress drives large-scale seagrass mortality, the physiological response of seagrasses under ocean acidification remains unclear. Therefore, this study selected Thalassia hemprichii, a dominant species of seagrass beds, to investigate the effects of ocean acidification (pH 7.7), sulfide stress, and their interaction on its physiological responses and growth. Our results showed that acidification alone relieved photosynthetic carbon limitation of T. hemprichii, significantly increasing net photosynthetic oxygen release and growth rate (p < 0.05). Sulfide stress alone significantly decreased the maximum quantum yield (Fv/Fm) and net photosynthetic rate and increased tissue H2S content (p < 0.05), while the growth rate showed a decreasing trend. Under combined acidification and sulfide stress, acidification promoted sulfide intrusion and significantly increased leaf H2S content (p < 0.05), whereas no significant reduction in growth rate was observed. Compared with sulfide treatment alone, combined acidification and sulfide stress enhanced the electron transport rate and radial oxygen loss (ROL) in T. hemprichii, thereby significantly increasing O2 contents in the sediment (p < 0.05). Meanwhile, the antioxidant defense systems of T. hemprichii were activated. These coordinated responses jointly mitigated sulfide toxicity. Therefore, under ocean acidification, T. hemprichii alleviated sulfide toxicity by coordinating carbon acquisition, rhizosphere oxygen cycling, and antioxidant defense. These findings provide key physiological and ecological evidence for predicting the adaptive capacity of seagrass beds under future climate change and underscore the importance of interactions among multiple stressors for seagrass conservation.

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Contrasting catchment characteristics and carbonate buffering capacity shape acidification susceptibility and CO2 source-sink dynamics in tropical lagoons

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Coastal ecosystems face increasing anthropogenic pressure, driving acidification and shifting them from carbon sinks to sources, yet comparative assessments across contrasting catchment types remain limited, particularly in the Indian Ocean region. We investigated carbonate chemistry in two contrasting tropical Sri Lankan lagoons, Negombo Lagoon, impacted by intensive anthropogenic and marsh-derived inputs, and minimally disturbed Rekawa Lagoon. In Negombo, low-pH, low total alkalinity (TA), and high-CO2 river water and acid-sulfate marsh inputs, combined with weaker carbonate buffering, intensified acidification (pH = 7.66 ± 0.45) and sustained CO2 outgassing (9.1 ± 10.2 mmol m-2 d-1). The lowest pH and weakest buffering occurred in the inner lagoon, and increased toward the seawater inlet through river-sea mixing. In contrast, catchment-derived higher-pH, higher-TA, lower-CO2 river water and strong buffering in Rekawa supported higher pH (8.31 ± 0.52) and net CO2 uptake (−1.8 ± 0.9 mmol m-2 d-1). Our simulations showed that riverine alkalinity enhancement (292–526 µmol kg-1 TA addition) mitigated acidification and CO2 outgassing in Negombo within 40–50 days. Our regional data synthesis showed that pH increased significantly with increasing TA/DIC ratio across estuaries and lagoons. These findings highlight carbonate buffering and catchment management as key strategies for mitigating coastal acidification and CO2 emissions.

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Call for submissions – Ocean ecosystems in a high-CO₂ world: biological responses from organisms to ecosystems

Published 6 November 2026 Events , Science Leave a Comment

Open for submissions

Submission deadline: 15 March 2027

Rising atmospheric CO₂ concentrations are reshaping ocean systems at every level, from seawater chemistry to ecosystem functioning and global biogeochemical cycles. As acidification, warming, and deoxygenation intensify, marine organisms and ecosystems face unprecedented physiological and ecological pressures. These changes influence biodiversity patterns, alter food‑web dynamics, and disrupt the ocean’s capacity to regulate climate and support essential ecosystem services. Understanding how marine systems respond to these carbon‑driven stressors is critical for predicting future ocean states and safeguarding the ecological functions upon which human societies depend.

Recent advances in experimental, observational, and modelling approaches have deepened our understanding of how elevated CO₂ affects marine organisms, communities, and biogeochemical processes. Long‑term monitoring efforts have revealed accelerating shifts in carbonate chemistry and oxygen availability, while physiological and ecological studies highlight species‑specific sensitivities and adaptive capacities. At the ecosystem scale, research is uncovering how multiple stressors interact to influence productivity, nutrient cycling, and resilience. Emerging work on marine carbon dioxide removal further underscores the need to evaluate both ecological risks and potential climate benefits within a rapidly changing ocean.

This Collection brings together interdisciplinary research that advances our understanding of ocean ecosystems under high‑CO₂ conditions. Contributions examine the mechanisms, impacts, and broader implications of carbon‑driven change across biological, chemical, and ecological dimensions. Topics of interest include, but are not limited to:

  • Ocean acidification and its impact on marine organisms, communities, and ecosystems
  • Ocean warming, deoxygenation, and interactions among multiple climate stressors
  • Changes in marine biodiversity, community structure, and ecosystem functioning under elevated CO₂
  • Shifts in ocean biogeochemical cycles, including carbon, nutrient, and oxygen dynamics
  • Physiological responses and adaptive capacity of marine organisms to carbon‑driven stress
  • Ecosystem‑level consequences of high‑CO₂ conditions, including productivity and food‑web dynamics
  • Ecological implications of marine carbon dioxide removal approaches
  • Modelling and forecasting future ocean states in a high‑CO₂ climate
  • Long‑term observations and experimental studies on carbon‑related ocean change
  • Management, conservation, and resilience strategies for carbon‑stressed marine ecosystems

For submissions to Ocean Ecosystems in 2026, waivers are available upon request.

This Collection supports and amplifies research related to SDG 13: Climate Action and SDG 14: Life Below Water.

All submissions in this collection undergo the journal’s standard peer review process. The Editors have no competing interests with the submissions which they handle through the peer review process. The peer review of any submissions for which the Editors have competing interests is handled by another Editorial Board Member or Guest Editor who has no competing interests. As an open access publication, this journal levies an article processing fee (details here). We recognize that many key stakeholders may not have access to such resources and are committed to supporting participation in this issue wherever resources are a barrier. For more information about what support may be available, please visit OA funding and support, or email OAfundingpolicy@springernature.com or the Editor-in-Chief.

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Chapter 4: sustainability tools I – systems thinking

Published 5 November 2026 Science Leave a Comment
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This chapter focuses on one of the approaches that can be used to connect sustainability and chemistry concepts: systems thinking. Because systems thinking approaches are relatively new to the chemistry education community, this chapter begins with a description of the essential characteristics of a systems thinking approach, as well as a brief overview of potential benefits and challenges associated with the approach. The chapter then uses two sustainability contexts to show how systems thinking approaches can be integrated into chemistry teaching and learning: (1) ocean acidification to demonstrate how instructors can use the essential characteristics of a systems thinking approach to iteratively make existing chemistry lessons more systems thinking oriented, and (2) lithium-ion batteries to show how systems-oriented concept map extensions (SOCMEs) can be used to connect core chemical content to both planetary systems and real-world socio-scientific issues. The final section of this chapter provides recommendations related to initial attempts to integrate systems thinking approaches into chemistry courses.

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A review: climate, contaminants and disease dynamics in lobster species Homarus americanus, Homarus gammarus and Jasus edwardsii

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Climate change, contaminant exposure, and emerging disease dynamics are increasingly recognized as interconnected stressors affecting marine crustaceans, including lobsters. This review compares three commercially and ecologically important species: Homarus americanus, Homarus gammarus, and Jasus edwardsii. Although these species differ taxonomically and ecologically, environmental stressors rarely act in isolation; climate change and contaminants interact to modify metabolic performance, molting, microbial dynamics and pathogen susceptibility. By synthesizing existing literature, this review identifies shared vulnerabilities and species-specific responses. Evidence suggests differences in thermal tolerance, developmental sensitivity and physiological plasticity, with early life stages consistently representing the most sensitive period across species. The American lobster has the strongest evidence linking warming waters to physiological stress and disease prevalence, particularly in Southern New England, whereas extensive research for European and Southern Rock lobsters remain limited. Across species, warming and ocean acidification often interact with contaminant exposure to alter immune function, molting, and recruitment. Key gaps remain in multi-stressor experiments, disease ecology and early life-stage research, emphasizing the need for integrative multi-stressor and cross-species frameworks to improve predictions of lobster resilience under accelerating environmental change.

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Overlooked contribution of organic alkalinity in Arctic Ocean margins biases ocean acidification estimates

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Organic alkalinity has been recognized as a potentially substantial fraction of total alkalinity in coastal waters. However, conventional assessments of ocean acidification typically neglect its contribution when calculating pH and aragonite saturation state, potentially biasing the derived values. Here, we present elevated organic alkalinity in Arctic margins, and show that failure to account for it introduces substantial biases in calculated [H+] (1% – 51%) and aragonite saturation state (1% – 117%) in the Svalbard fjords, Tanafjorden, and the Barents Sea Opening, with potential implications for the broader Atlantic sector of the Arctic margins. Regional projections based on Earth system model outputs further indicate that accounting for organic alkalinity leads to a larger and faster pH decline. These results indicate non-negligible biases in conventional ocean acidification assessments for Arctic margins and highlight the need to account for organic alkalinity in coastal waters and beyond.

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Africa’s first permanent Ocean Observatory: powering science, defending nature, and shaping policy for ocean governance and the blue economy

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Sustained, high-resolution ocean observation is essential for understanding how marine ecosystems respond to climate variability, human pressure, and conservation action. Yet long-term observing platforms remain scarce across the Global South, limiting the capacity to detect environmental change, evaluate management interventions, and support evidence-based ocean governance. To help address this gap, we established Africa’s first permanent, multi-ecosystem Ocean Observatory in Mozambique’s Bazaruto Archipelago, operated by the Bazaruto Center for Scientific Studies (BCSS) and Kisawa Sanctuary through a novel Resort-to-Research (R2R) funding and operational model. The observatory spans ~6,850 km² of ocean habitats in the Western Indian Ocean (WIO) region, a domain nearly six times larger than Bazaruto Archipelago National Park-BANP (1,430 km²) and more than fourteen times the San Sebastian Sanctuary (472 km²). It extends ecosystem-scale monitoring beyond protected-area boundaries across coral reefs, seagrass meadows, mangroves, sandy habitats, seamounts, coastal waters, and open-ocean environments. Between 2017 and 2026, the observatory generated more than 22 million high-frequency measurements across more than 30 ocean, weather, and biodiversity variables from 14 long-term stations distributed across six ecosystem types. These records are complemented by more than 250,000 minutes of underwater soundscape recordings, more than 120,000 georeferenced species records, and over 14,000 kg of marine debris recovered through monitoring and clean-up operations. Together, these datasets constitute one of the most comprehensive long-term environmental and biodiversity time-series currently available for the WIO region. The observatory is organized around four thematic programs: ecosystem dynamics, habitat mapping, migratory populations, and marine plastics, integrating physical, chemical, biological, and anthropogenic dimensions of environmental change. This publication forms part of a paired contribution on the BCSS Ocean Observatory. The companion technical/data paper published in Frontiers in Marine Science, “Africa’s first long-term ocean observatory in the Bazaruto Archipelago for multi-ecosystem and biodiversity data,” describes the observatory architecture, sensor systems, measured variables, QA/QC procedures, metadata structure, DOI-linked repositories, FAIR data-access pathways, and reuse potential. Building on this technical foundation, the present publication examines the observatory’s broader scientific, institutional, conservation, governance, and blue-economy significance. Embedded within the R2R model, the BCSS Ocean Observatory links eco-tourism, science, education, and community stewardship to support long-term operational continuity. Its open-access, DOI-linked datasets provide a foundation for environmental reporting and future monitoring, reporting, and verification applications related to climate, weather, ocean physics and chemistry, biodiversity, and pollution. More broadly, the observatory shows how locally anchored and community-engaged science can produce actionable knowledge for conservation planning, policy support, and selected blue-economy applications, including the future development of blue bonds, biodiversity credits, or plastic credits where appropriate validation and governance frameworks exist. The BCSS Ocean Observatory and R2R model therefore provide a transferable Africa-based example of how sustained ocean observation can support environmental accountability and strengthen long-term ocean governance.

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Multiscale pH fluctuations on a stable algal reef community (SE Sardinia, Tyrrhenian Sea)

Published 5 November 2026 Science Leave a Comment
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Highlights

  • Mean Tyrrhenian surface pH is 8.33, but drops to 8.07 at Capo Carbonara coralligenous.
  • High-frequency pH fluctuations are twice the open-sea mean multidecadal pH decrease.
  • Intrusion of Atlantic water and Saharan dust outbreaks affect local pH variability.
  • Coralligenous assemblage had long-lived, stable components and seasonal turf development.
  • Future shifting boundaries of variability by OA may impair Coralligenous tolerance.

Abstract

The Mediterranean Sea is threatened by ocean acidification and warming, in combination with habitat loss, pollution, invasive species, and overexploitation. Assessing local high-frequency pH variability in the context of relevant basin-scale time series data is essential to understand ecosystem vulnerability. We report the results of the Italian national pH monitoring based on the Marine Strategy Framework Directive, and the pH dynamics observed at Capo Carbonara. An experimental station equipped with a pH sensor and CTD probe was deployed at 32 m depth on a sandy bottom bordered by Coralligenous assemblages. Physical and biogeochemical variables were continuously recorded over 345 days and analyzed through additive time series decomposition. The benthic assemblages were surveyed by photographic and destructive sampling in summer and autumn 2016 and spring 2017 on algal reef and sandy bottom, to describe the biological components undergoing and contributing to the pH fluctuations. Seasonal pH variability ranged up to 0.2 units annually and 0.1 units daily, with maxima in January and minima in August, while the range of pH on the basin scale had higher mean values and exceeded local variability. Assemblage changes were driven by algal turf development and the invasive Caulerpa cylindracea. Coralligenous taxa appear stable, despite the substantial natural pH variability, shaped by meteo-marine conditions, water mass circulation, Saharan dust inputs, and benthic biological processes, with primary producers and calcifiers exerting a key influence. The ongoing trend of increasing temperatures and decreasing pH may threaten the Coralligenous ability to cope with the shifting future boundaries of such variability.

Continue reading ‘Multiscale pH fluctuations on a stable algal reef community (SE Sardinia, Tyrrhenian Sea)’

High alkalinity mitigates the negative impacts of high-CO2 ocean on foraminiferal calcification quantity and quality

Published 5 November 2026 Science Leave a Comment
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Ocean acidification threatens marine calcifiers, but the independent effects of seawater pH and total alkalinity on shell formation remain poorly understood. Here, we experimentally decoupled pH and alkalinity to examine their effects on shell growth and density in the large benthic foraminifer Amphisorus kudakajimensis. Low pH under present-day alkalinity substantially reduced shell weight, volume, and density, whereas simultaneously elevated alkalinity largely compensated for these negative effects. Shell weight and volume increased across the tested range of calcite saturation state, consistent with the balance between available inorganic carbon substrates and inhibitory protons. In contrast, shell density showed a more constrained response, suggesting physiological limits on further densification. These results provide experimental support for a carbonate-chemistry mechanism that may help explain how the low-pH but high-saturation conditions of Cretaceous oceans allowed calcifiers to persist. They also suggest that maintaining carbonate saturation through ocean alkalinity enhancement could help protect calcification under future acidification. Assessments of the vulnerability of marine carbonate producers to changing ocean chemistry should therefore distinguish between changes in shell growth and shell density.

Continue reading ‘High alkalinity mitigates the negative impacts of high-CO2 ocean on foraminiferal calcification quantity and quality’

Climate-driven reproductive dysfunction in cultured fish and shellfish: endocrine mechanisms, consequences and adaptive strategies

Published 4 November 2026 Science Leave a Comment
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Climate change is altering the environmental conditions experienced by aquatic organisms through rising temperatures, marine heatwaves, hypoxia, salinity fluctuations, ocean acidification and more frequent extreme events. Although the effects of climate change on growth, survival and disease have received considerable attention, reproductive impairment may occur before substantial mortality and can directly threaten aquaculture seed production. Reproduction depends on the coordinated interaction of environmental cues, neuroendocrine pathways, gonadal function, gametogenesis and energy allocation, making it particularly sensitive to environmental instability. In fish, climate-related changes can affect the brain–pituitary–gonad axis, steroidogenesis, sex differentiation, gametogenesis, gamete quality and spawning. Temperature is especially important because it influences endocrine regulation throughout reproductive development, while hypoxia, salinity changes and ocean acidification can further modify endocrine, metabolic and cellular processes. In shellfish, environmental stress can affect gonadal development, gametogenesis, spawning, fertilisation and larval performance through mechanisms that differ from those operating in vertebrate fishes. Multiple climate-related stressors may also act simultaneously, producing additive, synergistic or antagonistic effects. Parental exposure can further influence offspring through maternal provisioning, paternal effects and epigenetic mechanisms. These processes have direct implications for broodstock conditioning, hatchery seed production and the sustainability of aquaculture. This review examines the links between climate-related environmental change, reproductive endocrine regulation and reproductive performance in cultured fish and shellfish, with emphasis on gamete quality, spawning, early development, multiple-stressor interactions and reproductive resilience. Environmental management, broodstock selection, nutrition, acclimation, selective breeding, biomarker-based monitoring and climate-resilient hatchery technologies are considered potential approaches for sustaining reproductive performance under future environmental conditions.

Continue reading ‘Climate-driven reproductive dysfunction in cultured fish and shellfish: endocrine mechanisms, consequences and adaptive strategies’

Oxidative stress as a potential mechanistic link between climate change and aquatic biodiversity loss

Published 4 November 2026 Science Leave a Comment
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Climate change is rapidly altering aquatic ecosystems through rising temperatures, ocean acidification, hypoxia, ultraviolet radiation, salinity fluctuations, and interacting environmental stressors. These changes impose substantial physiological challenges on aquatic organisms, with oxidative stress representing an important mechanistic pathway linking environmental disturbances to biological responses across multiple levels of organization. This review synthesizes current evidence on oxidative stress responses associated with climate change-related environmental stressors across aquatic taxa, including fish, aquatic invertebrates, corals, phytoplankton, macroalgae, amphibians, and polar and deep-sea organisms. We examine the mechanisms underlying reactive oxygen species production, disruption of antioxidant defenses, and oxidative damage, while critically evaluating biochemical, molecular, and omics-based biomarkers for environmental stress assessment. Particular emphasis is placed on how oxidative stress may translate from cellular and organismal responses into changes in growth, reproduction, behavior, survival, species distributions, population dynamics, community structure, biodiversity, and ecosystem resilience. We also highlight limitations of current biomarker approaches, including species-specific variability, methodological inconsistencies, and difficulties in extrapolating laboratory findings to natural ecosystems. Future research should prioritize integrated multi-biomarker and multi-stressor approaches, long-term ecological monitoring, standardized protocols, and the integration of omics, environmental DNA, remote sensing, and artificial intelligence. Overall, oxidative stress biomarkers provide complementary tools for assessing climate-change impacts on aquatic biodiversity and ecosystem resilience.

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Kinetics of dissolved inorganic carbon acquisition by red seaweeds (Rhodophyta) with and without carbon-dioxide concentrating mechanisms

Published 4 November 2026 Science Leave a Comment
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Seaweed responses to ocean acidification (OA) may depend on whether they possess a carbon dioxide (CO2) concentrating mechanism (CCM). Using photosynthesis versus dissolved inorganic carbon (DIC) experiments, we determined the photosynthetic affinity (K0.5(CO2)) for CO2 for the red algae Pollexfenia lobata (CCM), and Callophyllis rangiferina, Delisea pulchra and Plocamium cirrhosum (non-CCM). K0.5(CO2) was statistically similar for CCM and non-CCM species, but P. lobata had values lower than those published for isolated red algal Rubiscos. Maximum photosynthetic rates (Pmax) were 2.5 times higher for Pl. cirrhosum and D. pulchra. Non-CCM species may benefit from future OA because photosynthesis would be less limited by DIC.

Continue reading ‘Kinetics of dissolved inorganic carbon acquisition by red seaweeds (Rhodophyta) with and without carbon-dioxide concentrating mechanisms’

Silicate accumulation in taxonomically diverse seaweeds: morphology, uptake, visualization and environmental responses

Published 4 November 2026 Science Leave a Comment
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Silicon is required by some microalgae but use and accumulation by seaweeds has been quantified in few taxa. This study aimed to examine biogenic Si (bSi) in taxonomically and morphologically diverse seaweeds, measure Si uptake rates, assess the effects of environmental conditions on bSi, and visualize Si within seaweed tissues. bSi was determined in 57 seaweed taxa across 17 taxonomic orders collected around Tasmania, Australia. There were no clear phylogenetic trends in bSi, but fine filamentous morphologies showed higher bSi content than thicker thalli, suggesting structural roles of Si. Highly variable bSi could relate to epiphytes. Simulated ocean acidification and warming did not affect bSi in taxa with or without active CO2 uptake mechanisms. Across estuarine-marine gradients, bSi was higher in samples of the same taxa closer to riverine sources, possibly due to higher dissolved Si (dSi) availability. Selected seaweed taxa took up dSi, though slower than rates for macronutrients, and accumulation of bSi and internal dSi was stimulated by higher ambient dSi. Si was visualized in cell walls and marginal cells with Rhodamine 123 staining and epifluorescence microscopy. Si pools in seaweeds can be significant (>0.6 % DW) but more studies on Si growth dependence would be valuable.

Continue reading ‘Silicate accumulation in taxonomically diverse seaweeds: morphology, uptake, visualization and environmental responses’

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