Trace metals are key regulators of coral reef functioning, acting as essential micronutrients or toxic stressors depending on concentration, speciation, and biological regulation. Corals and their associated holobionts require metals such as iron, zinc, copper, manganese, cobalt, molybdenum, and vanadium for photosynthesis, antioxidant defense, calcification, and nutrient cycling, while elevated levels of these elements, and non-essential metals including cadmium, lead, mercury, and nickel can induce oxidative stress, disrupt metabolism, disrupt coral-algal symbiosis, and contribute to bleaching and mortality. This review synthesizes current knowledge on trace metals in corals using evidence from laboratory experiments, field studies, skeletal geochemistry, and omics-based investigations. The biological roles and regulation of trace metals within the coral holobiont, their physiological and molecular impacts across life stages, and the influence of biogeochemical cycling and environmental drivers on metal availability and exposure in reef systems are examined. Analytical and omics-based approaches for investigating coral and metal interactions are also evaluated. Altogether, current evidence indicates that coral responses to trace metals depend on external metal concentrations, physiological regulation and environmental context. As climate change and anthropogenic activities continue to modify ocean chemistry, redox conditions, and metal bioavailability, understanding these interactions will become increasingly important for anticipating coral responses to future environmental change. Substantial knowledge gaps remain regarding thresholds between essentiality and toxicity, interactions with climate stressors, and holobiont-level metal cycling. Addressing these gaps is essential for improving interpretation of coral metal records, predicting reef vulnerability, and informing effective conservation and management strategies in an increasingly anthropogenically altered ocean.
Continue reading ‘Trace metals in the coral holobiont: roles and regulation in a changing ocean’Posts Tagged 'multiple factors'
Community metabolism generates chemical legacies that alter coral physiology
Published 3 November 2026 Science Leave a CommentTags: biogeochemistry, biological response, communityMF, corals, field, mesocosms, multiple factors, photosynthesis, physiology, primary production, respiration, South Pacific
Coral reefs are among the world’s most diverse ecosystems and contribute substantially to ocean productivity and the carbon budget. Disturbances are shifting reefs to altered community states, yet how these new communities indirectly alter organismal physiology by modifying the local biogeochemical environment remains largely unknown. We investigated this biogeochemical feedback in a 25-d mesocosm experiment in Mo’orea, French Polynesia. We exposed the common coral Porites rus to the biogeochemical environments generated by three distinct communities representative of recent benthic states in this system: coral-, macroalgae-, and crustose coralline algae-enriched relative to a seawater-only control. While net community production was similar among communities, net community calcification was lowest in the macroalgae-enriched state. Across treatments, community metabolism drove changes in the organic and inorganic carbon pool, with net community production increasing both pH and dissolved organic carbon. Using structural equation modeling, we tested how these community-generated chemical legacies propagated through coral physiology. Elevated pH increased chlorophyll a content, which increased endosymbiont density, tissue biomass, gross photosynthesis, and respiration through a series of indirect pathways. Dissolved organic carbon had no detectable effect on downstream corals at 25 d. These results reveal a mechanistic pathway linking disturbance-driven shifts in benthic communities to coral performance. Altered community metabolism modifies local carbon chemistry, which reshapes symbiont physiology and ultimately influences host metabolic function. By identifying the pathways through which community states engineer their chemical environment, this study provides a framework for predicting coral performance and ecosystem trajectories as reefs transition away from coral-enriched states.
Continue reading ‘Community metabolism generates chemical legacies that alter coral physiology’Unlocking spatial ecological assessment for tropical seagrass habitats using a new rapid assessment method (SEARAM)
Published 3 November 2026 Science Leave a CommentTags: abundance, biological response, community composition, field, Indian, light, methods, multiple factors, otherprocess, phanerogams, salinity, temperature
Highlights
- Rapid and standardized assessment of tropical seagrass ecological state.
- Multimetric index combining structure and vitality indicators.
- Spatial mapping of seagrass fragmentation and degradation.
- Links between habitat condition, environment, and megafauna.
- A practical tool for coastal monitoring and impact mitigation.
Abstract
Seagrass meadows are key coastal ecosystems supporting biodiversity, carbon storage, and essential trophic functions, yet they are increasingly threatened by anthropogenic and climatic pressures. Based on the Seagrass Meadows Rapid Assessment Method (SEARAM), a standardized protocol grounded in seagrass biodiversity indicators (SBIs), we developed a reliable and operational index to assess seagrass ecological state at high spatial resolution. Using 536 circular plots and 144 faunal stations across three intertidal reef habitats in Mayotte (Western Indian Ocean), SEARAM integrates structural and vitality sub-indices into a composite seagrass ecological state index (SESI), spatialized by geostatistical interpolation and analyzed using ANOVA, PCA, and multiple regression models. Results revealed highly fragmented meadows dominated by Halodule uninervis and Halophila ovalis, with low canopy height (5 ± 2 cm) and substantial epiphyte loads (37 ± 17%). The inner fringing reef flat showed the poorest ecological state (SESI = 4.8 ± 0.7/10), whereas the barrier reef (5.4 ± 0.8/10) and exposed fringing reef flat (5.6 ± 0.8/10) exhibited moderate scores. Key environmental drivers (turbidity, grain size, pH), significantly explained spatial patterns of seagrass structure and vitality, confirming the influence of sediment and light regimes. Functional relationships were also demonstrated between seagrass condition and associated fauna, particularly green turtle density and dugong feeding traces. SEARAM proved to be a rapid and robust tool for diagnosing tropical seagrass states. Its multimetric framework connects benthic condition to habitat suitability for megafauna, offering an operational foundation for ecological monitoring, management, and impact mitigation within the Avoid–Reduce–Offset (ARO) doctrine.
Graphical abstract
Climate-driven habitat loss of Chinese sturgeon in the Northwestern Pacific and implications for marine protected area design
Published 3 November 2026 Science Leave a CommentTags: abundance, biological response, fish, methods, modeling, multiple factors, North Pacific, nutrients, otherprocess, oxygen, regionalmodeling, salinity, temperature
Highlights
- Ensemble modeling integrates eleven algorithms to predict sturgeon habitat suitability.
- Temperature is the dominant driver, followed by pH and total suspended matter.
- Suitable habitats are projected to disappear completely by 2100 under SSP5–8.5.
- Static protected areas must transition to climate-adaptive zoning strategies.
Abstract
The conservation of endangered anadromous fishes depends on understanding their full-lifecycle habitat requirements, yet the marine phase of Chinese sturgeon (Acipenser sinensis) remains a critical knowledge gap despite over 90% of its lifespan occurring at sea. We integrated multi-source occurrence data (satellite tagging, bycatch records, environmental DNA, and online databases) and applied an ensemble modeling framework (Biomod2 with eleven algorithms) to predict habitat suitability across the Northwestern Pacific Ocean (100°E–150°E, 10°N–55°N). After collinearity filtering, seven key environmental drivers were retained, among which mean temperature contributed most, followed by maximum pH, total suspended matter and mean silicate. The ensemble model achieved high predictive performance (median TSS = 0.944) and identified the Changjiang Estuary and coastal waters of Zhejiang and Jiangsu provinces as current distribution hotspots. Under the high-emission scenario (SSP5–8.5), suitable habitats are projected to disappear completely by 2100, accompanied by a significant northward contraction. These projections should be regarded as a potential worst-case scenario under high-emission conditions rather than a deterministic forecast. These findings demonstrate that business-as-usual emissions would eliminate viable marine habitat for this critically endangered species. Conservation priorities should therefore focus on (1) protecting benthic prey resources in the Changjiang Estuary and Zhoushan Archipelago as core refugia, and (2) transitioning from static marine protected areas to dynamic, climate-adaptive zoning informed by real-time habitat predictions. The ensemble modeling approach developed here is transferable to other data-limited, endangered marine species facing similar climate threats.
Continue reading ‘Climate-driven habitat loss of Chinese sturgeon in the Northwestern Pacific and implications for marine protected area design’Spat origin does not affect phenotypic plasticity in the farmed mussel Mytilus chilensis facing experimental acidification
Published 2 November 2026 Science Leave a CommentTags: biological response, calcification, fisheries, mesocosms, mollusks, morphology, multiple factors, origin, physiology, South Pacific
Phenotypic plasticity allows organisms to cope with environmental variability, yet its role in sustaining aquaculture systems in the face of global change stressors remains poorly understood. We conducted a 90-day mesocosm experiment to test whether spat origin influences morphological, physiological, and periostracum responses in the Chilean mussel Mytilus chilensis under sustained experimental acidified conditions. Juveniles were collected from two contrasting habitats: an estuarine and dynamic/fluctuating environment, strongly influenced by freshwater discharges, and a marine, more stable environment; and then exposed to two pH regimes (8.0 and 7.5). Morphological traits showed subtle origin effects: estuarine mussels tended to exhibit higher shell length and calcification rates, though origin × pH interactions were not significant. Physiological responses were largely similar between both seed sources, with metabolic rates remaining stable while the clearance rate increased under acidified conditions in both populations. Periostracum analyses revealed some non-significant variation in organic composition, but no consistent effects of the pH were detected. Together, these results suggest that M. chilensis relies on conservative metabolic maintenance combined with flexible clearance responses possibly to cope with natural acidification pulses, while also tolerating sustained low-pH conditions, with only weak signals of origin-driven divergence. Our findings highlight the importance of phenotypic adjustments over local origin, suggesting that spat provenance may not be a primary determinant of performance under projected acidification scenarios tested here.
Continue reading ‘Spat origin does not affect phenotypic plasticity in the farmed mussel Mytilus chilensis facing experimental acidification’Putting a time scale on emerging climate change stressors: a vulnerability index for Atlantic Ocean marine ecosystem services
Published 2 November 2026 Science Leave a CommentTags: chemistry, modeling, multiple factors, North Atlantic, oxygen, policy, regionalmodeling, socio-economy, South Atlantic, temperature
Highlights
- Climate stressor emergence is highly heterogeneous across the Atlantic.
- Multi-stressor emergence before 2100 is projected for all Atlantic EEZs.
- Vulnerability is driven by emerging climate stressors, amplified by a high sensitivity of habitats and communities, and a low adaptive capacity.
- Lower vulnerability is partly driven by robust governance and infrastructure.
- Adaptive responses must address socio-economic differences and variable exposure to stressors.
Abstract
Marine ecosystem services underpin human wellbeing and support resilient socio-ecological systems, yet existing vulnerability assessments remain fragmented, often focusing on isolated industries and overlooking the whole-system socio-ecological context. To bridge this gap, we develop a comprehensive Vulnerability Index to assess marine ecosystem service vulnerability to emerging climate stressors in the Atlantic. Using high-resolution ocean simulations and moving beyond traditional long-term projections, we employ the Time of Emergence metric to address actionable decision-making timescales (2–3 decades). We found that all Atlantic marine ecosystem services are projected to be exposed to multiple emerging stressors before 2100, though the sequence and the timing of emergence are highly heterogenous. Overall vulnerability is highest in tropical West Africa due to the early emergence of hypoxia and sea level rise extremes compound by low adaptive capacity. Additional hotspots are found in subpolar and polar regions driven by rapid sea ice retreat and the sensitivities of region-specific habitats alongside a high dependence on marine ecosystems. Coupled with socio-ecological data, we determined which services (provisioning, regulatory and cultural) are most sensitive to potential impacts in each EEZ. We anticipate this index to be a starting point to develop targeted vulnerability indices for specific ecosystem services and regions. Mitigative and adaptive efforts must be multi-scale and tailored to national and local contexts, addressing not only socio-economic differences but also variable climate stressors and their impacts. Uncertainties associated with time series data gaps and indicator aggregation, particularly for island and remote territories, highlight the need for targeted national adaptation.
Continue reading ‘Putting a time scale on emerging climate change stressors: a vulnerability index for Atlantic Ocean marine ecosystem services’Integrated study of ocean warming, CO₂ uptake, and acidification under anthropogenic emissions
Published 30 October 2026 Science Leave a CommentTags: chemistry, globalmodeling, methods, mitigation, modeling, multiple factors, phytoplankton, temperature
The study examines the influence of greenhouse gas pollutants on ocean waters. A key parameter describing ocean properties is pH, whose decrease negatively affects marine flora and fauna. Ocean surface temperatures rise over time due to the absorption of anthropogenic heat, with the most significant processes occurring within the upper 10 m layer. Phytoplankton, increasingly important for addressing ecological issues, is also affected by decreasing pH levels. To quantitatively describe ocean conditions, a thermodynamic calorimetric method is proposed. Validation is performed through a comparison of calculated and observed temperature variations, as well as the estimated specific heat capacity of ocean water. Measured pH variations are also compared with calculated values. The resulting expression incorporates temperature change, absorbed heat, and CO₂ content. Phytoplankton photosynthetic activity is further assessed in relation to potential cultivation areas on the ocean surface.
Continue reading ‘Integrated study of ocean warming, CO₂ uptake, and acidification under anthropogenic emissions’How ocean acidification makes marine fish reproduction vulnerable: physiological mechanisms and ecosystem consequences
Published 29 October 2026 Science Leave a CommentTags: biological response, fish, fisheries, mortality, multiple factors, physiology, reproduction, review, temperature
Highlights
What are the main findings?
- Ocean Acidification (OA) disrupts the HPG axis, reducing sex steroids and vitellogenesis.
- OA impairs gamete quality, sperm motility, egg integrity, and Ca²⁺ signaling.
- pH decline may weaken Dax1 repression of P450arom, but this remains unvalidated.
- OA plus warming often worsens reproductive dysfunction; multigenerational recruitment effects are still unknown.
What is the implication of the main finding?
- OA threatens fish recruitment, community structure, and fishery productivity/food security.
- Long-term, multigenerational, multi-stressor field studies are needed for effective management.
Abstract
Ocean acidification, driven by the absorption of anthropogenic carbon dioxide into seawater, poses a significant threat to marine environments and biodiversity. This comprehensive review examines the specific impacts of acidification on the reproductive physiology of fish, integrating recent advances in our understanding of gonadal development, gametogenesis, and early embryonic development. We synthesize current findings on how altered carbonate chemistry disturbs the reproductive system from gametogenesis and fertilization to larval development and beyond. Our analysis reveals that ocean acidification affects multiple physiological pathways, including disruption of the hypothalamic–pituitary–gonadal (HPG) axis, impairment of calcium signaling, and alterations in sex hormone synthesis. We propose a mechanistic model in which pH reduction may weaken Dax1-mediated repression of P450arom transcription, thereby dysregulating aromatase activity and leading to sex hormone imbalance that impairs gonadal development; however, this proposed mechanism requires direct experimental validation under ocean acidification, as the net outcome may be modulated by additional regulatory layers such as epigenetic modifications and other transcription factors. Furthermore, we discuss the synergistic effects of ocean acidification with temperature elevation and other stressors, which often exacerbate reproductive dysfunction. This review concludes that no multi-generational study has yet evaluated HPG axis disruption to population-level recruitment failure, a critical gap for fishery resource assessment. We emphasize the critical importance of multi-generational and field-based studies to fully understand these impacts, which is essential for forecasting consequences for global marine biodiversity and the long-term sustainability of fisheries.
When oceans acidify: metal toxicity, uptake–depuration, and ion homeostasis in the copepod Nitokra sp.
Published 28 October 2026 Science Leave a CommentTags: biological response, crustaceans, laboratory, metals, mortality, multiple factors, physiology, zooplankton
Highlights
- Seawater pH affected metal toxicokinetics, but not toxicity in Nitokra sp.
- Seawater pH affected Cu, Zn and Cd toxicokinetics, but not toxicity in Nitokra sp.
- The highest bioconcentration factor was observed for Cu at pH 8.1.
- Acute Cu, Cd, and Zn exposure did not reduce significantly copepod Ca or Na at pH 8.1 and 7.6.
- Copepod Ca declined 48 h after Cd exposure ended, indicating Cd-induced ionic imbalance.
Abstract
Mechanisms governing metal kinetics help maintain trace element levels required for physiological functions and ion regulation in aquatic organisms. However, both essential and non-essential metals can become toxic at excessive concentrations. Water physicochemical properties, including pH and dissolved anions, influence metal speciation, bioavailability, and toxicity. Under acidic conditions, bioavailability may increase as H+ competes with metal cations for binding sites, increasing free metal ions. Greater bioavailability may also disrupt uptake of essential macronutrients such as calcium (Ca) and sodium (Na) through competition at biotic binding sites. In the present study, we assessed the toxicity (half maximal lethal concentration [LC50]), toxicokinetics (bioaccumulation at the 10% lethal concentration [LC10] followed by depuration), and the impacts on Ca and Na levels of cadmium (Cd), copper (Cu), and zinc (Zn) in the estuarine copepod Nitokra sp. at pH 8.1 (natural) and pH 7.6 (acidified, as projected by the Intergovernmental Panel on Climate Change). All tested metals followed typical dose–response toxicity curves, with Cu being the most toxic, followed by Cd and Zn, with no significant differences between pH 8.1 and 7.6. Contrary to our hypothesis, bioconcentration factors were higher at pH 8.1 than at pH 7.6. Metal exposure did not significantly affect Ca and Na, but trends suggest early physiological disturbance, with Ca decreasing with exposure to Cd or Zn and increasing with exposure to Cu. During elimination, Ca levels were higher in Cu-exposed copepods than in Cd-exposed ones and similar to controls, suggesting that Cd competes with Ca at the cellular level.
Graphical abstract
Elevated pCO2 promotes growth but compromises PSII repair and antioxidant balance in the bloom-forming diatom Skeletonema costatum under ultraviolet radiation
Published 28 October 2026 Science Leave a CommentTags: biological response, growth, laboratory, light, multiple factors, photosynthesis, physiology, phytoplankton, protists
Highlights
- Elevated pCO2 stimulates growth but not UV photoprotection in Skeletonema costatum.
- Ocean acidification constrains PSII repair and PsbA turnover under UVR.
- Trade-off between carbon-sequestration capacity and antioxidant defense raises UV sensitivity.
Abstract
Diatoms serve as key marine primary producers, driving global biogeochemical cycles, but their physiological performance is increasingly challenged by ocean acidification (OA) and enhanced ultraviolet radiation (UVR). This study investigated how OA caused by elevated pCO2 (1000μatm) modulates the UVR sensitivity of the bloom-forming diatom Skeletonema costatum. Elevated pCO2 significantly enhanced the specific growth rate by ~11.6%; it did not significantly aggravate the UVR-induced decline in Fv/Fm, but it constrained PSII repair and PsbA turnover, as indicated by lower rate constants for PSII repair (Krec, s−1) and PsbA removal (KPsbA, s−1), and was associated with a greater net decline in total PsbA content under PAR + UVR. Although elevated pCO2 upregulated the relative maximal electron transport rate (rETRmax) and light-saturation parameter (Ik), and maintained a higher RbcL/PsbA ratio consistent with a possible role of carbon assimilation as a downstream sink, it did not enhance the sustained non-photochemical quenching (NPQs). Furthermore, under elevated pCO2, CAT activity had a lower baseline; although CAT increased under UVR relative to PAR, its absolute activity remained lower, indicating an imbalanced antioxidant response. Collectively, these findings reveal a physiological trade-off: elevated pCO2 promotes growth and carbon-sequestration capacity but simultaneously compromises photoprotective mechanisms. Consequently, S. costatum grown under elevated pCO2 becomes more susceptible to UVR-induced photoinhibition, potentially suppressing photosynthetic production during surface blooms and influencing bloom persistence and carbon export.
Continue reading ‘Elevated pCO2 promotes growth but compromises PSII repair and antioxidant balance in the bloom-forming diatom Skeletonema costatum under ultraviolet radiation’Interactive effects of ocean acidification and benzophenone-3 on mussel physiology: a biomarker-based approach
Published 27 October 2026 Science Leave a CommentTags: biological response, laboratory, mollusks, multiple factors, physiology, toxicants
Highlights
- Ocean acidification was the primary driver of biomarker responses.
- Low pH enhanced BP3-induced cytotoxicity in hemocytes.
- BP3 detoxification mainly involved the GST/GSH pathway.
- Lipid peroxidation occurred in gills and digestive gland despite antioxidant response.
- Acidification impacts biomineralization enzymes more strongly than BP3.
Abstract
Benzophenone-3 (BP3), a widely used ultraviolet (UV) filter in personal care products and industrial applications, is an emerging concern in aquatic ecosystems due to its lipophilicity, bioaccumulation potential, and toxicity to marine biota. Its occurrence in marine environments coincides with ocean acidification driven by rising atmospheric CO2 emissions, which disrupts the bicarbonate buffer system and reduces pH. This study investigated the acute effects (96 h exposure) of BP3 (at realistic concentrations of 0.2 and 2 μg/L) under 3 pH conditions (8.1- the current South Atlantic condition- and 7.6 and 7.3 as projected acidification scenarios for 2100 and 2300, respectively) in the brown mussel Perna perna. The effects were investigated through analysis of hemocyte viability and biomarkers related to detoxification (glutathione S-transferase, glutathione, glutamate cysteine ligase, and reduced glutathione), oxidative stress (antioxidant capacity against peroxyl radicals and lipid peroxidation), and biomineralization (carbonic anhydrase and Ca2+ATPase), measured in the gills, digestive gland, and mantle. Despite BP3-induced activation of glutathione-related detoxification pathways, as evidenced by increased GSH levels and GST activity, particularly in the gills, hemocyte viability decreased after BP3 exposure, with the greatest reduction at pH 7.3. Lipid peroxidation (LPO) also increased in the gills and digestive gland under acidified conditions, with the magnitude of the response varying according to BP3 concentration. CA and Ca2+ATPase activities were more strongly influenced by acidification than by BP3 exposure, although their responses were tissue-specific and, in some cases, modulated by BP3 exposure. Multivariate analyses identified pH as the primary driver of biomarker responses.
Graphical abstract
From population to individual: bulk and single-cell analysis reveal Fe bioavailability, limitation thresholds, and biological responses for marine diatom Chaetoceros debilis
Published 27 October 2026 Science Leave a CommentTags: abundance, biological response, laboratory, metals, multiple factors, otherprocess, physiology, protists
Highlights
- Fe speciation and pH jointly regulated Fe bioavailability.
- A critical bioavailable Fe limitation threshold (∼10 nM) was identified for the marine algae.
- Single-cell analysis revealed previously hidden heterogenous Fe accumulation.
- Fe stress induced adaptive responses including metallome remodeling.
Abstract
In marine ecosystems, Fe fundamentally regulates algal productivity and drives biogeochemical cycling in the hydrosphere, yet its environmental controls and cellular responses remain insufficiently resolved, particularly at the single-cell level. Herein, we combined bulk and single-cell analysis to systematically investigate Fe bioaccumulation process in the marine diatom Chaetoceros debilis under varying Fe species, initial pH, and concentration conditions. Fe bioavailability followed the order Fe-ethylenediaminetetraacetate > Fe-deferoxamine B > Ferrihydrite and decreased with declining initial pH, highlighting the combined control of chemical speciation and ocean acidification. A critical bioavailable Fe limitation threshold of ∼10 nM was identified, below which algal growth, pigmentation, and cell size were significantly suppressed. Under Fe limitation, cells exhibited compensatory accumulation of other metals (e.g., Zn, Mn, Cu, and Ni), indicating metallome remodeling as an adaptive strategy. Notably, single-cell analysis revealed pronounced heterogeneity in Fe accumulation within populations, with heterogeneity positively related to bioavailable Fe levels. These findings demonstrate that algal Fe accumulation is governed by coupled environmental and physiological processes and that population-level averages mask critical cell-to-cell variability and their adaptive strategies under environmental stress. This work provides mechanistic insights into how environmental chemistry regulates metal bioavailability and biological responses, offering a broadly applicable framework for understanding the environmental behavior and ecological effects of trace metals and other contaminants in aquatic ecosystems.
Graphical abstract
Surviving together: evolutionary dependency, community dynamics, and mortality in marine microbial communities
Published 26 October 2026 Science Leave a CommentTags: abundance, adaptation, biological response, community composition, growth, laboratory, light, molecular biology, mortality, multiple factors, nutrients, otherprocess, photosynthesis, physiology, phytoplankton, primary production, prokaryotes, reproduction, respiration, temperature
Oligotrophic regions of the world ocean sustain vast phytoplankton populations despite extremely low nutrient levels. However, the mechanisms governing their coexistence, interdependence, and mortality are poorly understood. This dissertation investigates how evolutionary dependency, community feedback, and regulated cell death (RCD) jointly shape the stability of marine microbial communities using the Prochlorococcus/Parasynechococcus/Alteromonas model system.
In Chapter 1, I argue that the Black Queen (BQ) hypothesis—which posits that microbes lose costly metabolic functions supplied by community partners—provides a unifying framework for understanding phytoplankton ecology. This framework helps resolve longstanding puzzles, including the paradox of the plankton and the evolutionary maintenance of RCD in unicellular organisms. Building on this framework, Chapter 2 uses transcriptomic analysis of Alteromonas in co-culture with picocyanobacteria to demonstrate that community composition induces greater changes in gene expression than pCO₂ alone. Reduced 2-phosphoglycolate/glycolate exudation by Prochlorococcus under elevated pCO₂ may disrupt the helper heterotroph effect underlying this cyanobacterium’s BQ dependency.
Chapter 3 integrates co-culture experiments, RNA-seq, metabolomics, and mathematical modeling to demonstrate that the stable coexistence of Prochlorococcus and Parasynechococcus is maintained by an “Ouroboros network” of feedback loops. In this network, resource competition, carbon exudation, BQ dependency, and possibly RCD collectively stabilize the community across environmental gradients and during adaptation to changing conditions.
Chapter 4 resolves the cellular mechanisms underlying RCD in these cyanobacteria, showing that differences in cell death modes and the number of checkpoint-linked mortality events between taxa are associated with divergent life-history strategies. These findings suggest that carbon released at these checkpoints may shape interactions with helper Alteromonas, linking individual cell death to community-level interdependencies.
In conclusion, these findings converge on a new resolution to the paradox of the plankton: coexistence in resource-limited environments emerges from interdependent metabolic exchanges, feedback, and regulated cell death shaped by multilevel selection. I propose that together, these processes form an “altruistic bargain” in which stability arises from self-constraint rather than competition alone. Because these interactions are environmentally sensitive, climate change, including warming and acidification, may disrupt the dependencies that sustain microbial diversity and ecosystem function in the world ocean.
Continue reading ‘Surviving together: evolutionary dependency, community dynamics, and mortality in marine microbial communities’Hypoxia and acidification antagonistically suppress nitrification but enhance its N2O production in coastal waters
Published 26 October 2026 Science Leave a CommentTags: biogeochemistry, biological response, molecular biology, multiple factors, North Pacific, otherprocess, oxygen, physiology, prokaryotes
The concurrent intensification of hypoxia and acidification poses a growing threat to estuarine-coastal ecosystems globally, yet their interactive impacts on nitrification, a key process in the nitrogen (N) cycle and a substantial source of nitrous oxide (N2O), remain poorly understood. This knowledge gap hinders reliable projections of future N cycling and climate feedbacks in these critical ecosystems. Here, we demonstrate that along the estuarine-coastal continuum, the co-occurrence of hypoxia and acidification suppresses nitrification rates but stimulates nitrification-derived N2O emissions—although their combined effect is lesser than the sum of their individual effects. Metatranscriptomic analysis provided molecular evidence for these isotopically traced responses and uncovered critical microbial coping strategies through transcriptional adjustments in metabolic pathways for energy conservation and stress tolerance. This previously overlooked interaction disrupts microbial N cycling with potential impacts on N2O emissions and climate feedbacks, highlighting the necessity to revise predictive models by incorporating such multistressor dynamics.
Continue reading ‘Hypoxia and acidification antagonistically suppress nitrification but enhance its N2O production in coastal waters’Physiological responses of Atlantic surfclams (Spisula solidissima) to moderate ocean acidification across thermal regimes
Published 23 October 2026 Science Leave a CommentTags: biological response, chemistry, fisheries, growth, laboratory, mollusks, morphology, multiple factors, North Atlantic, performance, physiology, respiration, temperature
Highlights
- Interactive effects of warming and acidification tested in surfclams.
- Growth, feeding, and metabolic rates measured after 6-week exposure.
- Moderate acidification had limited effects under warming conditions.
- Surfclams showed resilience to near-future ocean acidification.
- Multi-stressor design improves ecological relevance of lab studies.
Abstract
Understanding marine organismal responses to co-occurring climate stressors is critical for predicting changes in ecosystems and commercial fisheries. The Atlantic surfclam supports a major commercial fishery in the Northeastern United States, where ocean warming and acidification are rapidly altering marine habitats. To evaluate how changing ocean conditions may affect bivalve physiology, surfclams were exposed to conditions reflective of ocean warming and acidification, respectively. One-year-old surfclams were exposed to nine conditions in a fully crossed design of temperature (ambient, +2 °C, and + 5 °C) and pH (7.88 ± 0.05, 7.76 ± 0.05, and 7.51 ± 0.07) for six weeks in a flow-through laboratory experiment using natural seawater. We quantified several physiological responses including growth, feeding, digestion, respiration rates, and shell weight and thickness to assess organismal performance across treatments.
Surfclams generally exhibited resistance to moderate ocean acidification across warming, but non-thermally stressful, temperatures. No effects of ocean acidification were observed on surfclam growth or respiration, although other physiological metrics (shell thickness and absorption rate) decreased with decreasing pH at some temperatures. These findings provide experimentally-derived insight into species-specific responses to interacting climate stressors. Further, the experimental design highlights the importance of integrating natural environmental variability into laboratory studies and studying multiple environmental stressors concurrently. This study contributes a basis for refining models of surfclam growth and distribution in potential future climate scenarios, with implications for sustainable fisheries management.
Continue reading ‘Physiological responses of Atlantic surfclams (Spisula solidissima) to moderate ocean acidification across thermal regimes’Ocean warming and acidification reveal transcriptional plasticity in the gastropod Hexaplex trunculus
Published 23 October 2026 Science Leave a CommentTags: biological response, molecular biology, mollusks, multiple factors, performance, physiology, respiration, temperature
Coastal ecosystems, particularly in the rapidly warming Mediterranean Sea, are increasingly impacted by climate change driven by ocean warming and acidification. Calcifying marine invertebrates are especially vulnerable, yet their molecular responses remain poorly understood. Gene expression dynamics in the ecologically and commercially important gastropod Hexaplex trunculus were investigated under simulated scenarios combining elevated temperature and reduced pH. High-throughput RNA sequencing was used to generate a de novo assembly of the foot transcriptome, followed by differential gene expression analyses to characterize molecular responses to individual and interactive stressors under high-emission (RCP 8.5) projections. The foot tissue – central to locomotion, adhesion, and environmental interaction – exhibited pronounced transcriptional changes in genes associated with calcium signaling, ion transport, aerobic respiration, muscle contraction, and transmembrane transport. Ocean acidification emerged as the dominant driver of transcriptional change, inducing substantial shifts in metabolic demand and ion regulatory pathways, which might suggest increased energetic costs and potential functional constraints. The results demonstrate marked transcriptional plasticity in H. trunculus under combined climate stressors. By providing foundational transcriptomic resources for this species and mechanistic insight into its response to projected environmental changes, this study advances the understanding of molecular processes in vulnerable Mediterranean gastropods and informs ecological assessment efforts in rapidly warming marine ecosystems.
Continue reading ‘Ocean warming and acidification reveal transcriptional plasticity in the gastropod Hexaplex trunculus’Climate change and fish reproduction: a meta-analysis of global laboratory-based experimental evidence across species and ecosystems
Published 22 October 2026 Science Leave a CommentTags: biological response, fish, laboratory, multiple factors, oxygen, performance, physiology, reproduction, review, temperature
Climate change is altering fish reproduction by disrupting spawning cycles, reducing egg viability, and altering reproductive behaviours essential for population sustainability, to our knowledge, this is the first synthesis to integrate laboratory-based evidence for temperature, hypoxia, ocean acidification, and their combined exposure across reproductive performance, physiological, developmental, and molecular endpoints, and across freshwater, brackish, and marine habitats. Following PICOS and PRISMA criteria, we synthesised 779 effect sizes (740 retained after outlier exclusion) from 80 controlled laboratory studies (38,500 observations; 54 species; 28 countries). A three-level multilevel model accounting for non-independence among effect sizes drawn from the same study showed a significant overall negative effect of climate stressors on fish reproduction (Hedges’ g = −0.421, 95% CI: −0.631 to −0.210, p < 0.001; I² = 94.9%, decomposed into 36.3% between-study and 58.6% within-study heterogeneity). Hypoxia was the dominant and statistically distinct driver (g = −1.145, 95% CI: −1.648 to −0.643, p < 0.0001), most severely impairing gonadal development and sperm quality. The overall warming effect did not reach significance once non-independence was accounted for (g = −0.221, 95% CI: −0.448–0.006, p = 0.057), an uncertain negative trend rather than confirmed impairment, although tropical freshwater species showed significant subgroup-specific declines in reproductive physiology and genetic parameters. Ocean acidification showed a small positive effect (g = 0.199, 95% CI: 0.056–0.343, p = 0.006) that was not robust under robust variance estimation (p = 0.133) and is interpreted with caution. Combined multi-stressor exposure showed a negative trend (g = −0.901, 95% CI: −1.992–0.190, p = 0.106) that did not reach significance, based on only three studies. A formal omnibus test confirmed that stressor categories differ significantly in their effects (QM = 18.61,df = 3, p = 0.0003), with hypoxia statistically distinct from both temperature and ocean acidification. Leave-one-out and cumulative meta-analyses confirmed the robustness of the overall finding.
Plastic pollution as a pathway to ocean acidification and disruption of the seawater carbonate system
Published 22 October 2026 Science Leave a CommentTags: biogeochemistry, chemistry, laboratory, multiple factors, plastics
Ocean acidification threatens calcifying organisms by reducing seawater pH and carbonate ion availability, while plastic pollution may intensify this effect through chemical and microbial processes, exacerbating impacts on calcification. Here, we investigated, for the first time, the biogeochemical mechanisms of plastic-pollution-induced ocean acidification and the role of plastic as a modifier of the seawater carbonate system. Microcosm experiments were conducted using naturally weathered plastic particles incubated in seawater under irradiated and dark conditions. The experiment comprised two seven-day phases: (1) an abiotic phase evaluating the physicochemical effects of plastic degradation and (2) a biotic phase assessing microbial contributions to plastic-induced acidification. Variations in pH, dissolved CO₂, Ωarag, and Ωcalc were monitored as acidification indicators. During the abiotic phase, plastic increased dissolved CO₂ concentrations threefold under irradiation (27.08 µmol kg⁻¹) compared with the dark treatment (9.65 µmol kg⁻¹), reducing pH, Ωarag, and Ωcalc. By the end of this phase, irradiated plastic reached pH = 7.6, Ωarag = 2.16, and Ωcalc = 3.25, corresponding to values associated with impacts on calcifying organisms and considered terminal for coral reef development. During the biotic phase, no significant changes were observed, likely due to limited dissolved organic carbon release, indicating that UV-driven abiotic processes, rather than microbial activity, predominated in CO₂ release. The observed chemical changes matched end-of-century projections under high-emission scenarios, highlighting that plastic pollution may intensify reductions in carbonate ion concentration and calcium carbonate saturation states, accelerating calcifier mortality and biodiversity loss.
Continue reading ‘Plastic pollution as a pathway to ocean acidification and disruption of the seawater carbonate system’Carry-over effects of low salinity during embryonic development modulate larval responses to combined salinity-pH stress in an estuarine crab
Published 21 October 2026 Science Leave a CommentTags: biological response, crustaceans, laboratory, mortality, multiple factors, physiology, reproduction, respiration, salinity
Early life stages of estuarine organisms are exposed to concurrent environmental stressors, but the extent to which embryonic conditions shape larval responses to multiple stressors remains largely unexplored. We evaluated whether salinity during embryogenesis modulates larval responses to combined salinity and pH stress in the estuarine crab Neohelice granulata. Embryos were reared at two salinities (15 and 33), and larvae were subsequently exposed to combinations of pH (8 and 6.9) and salinity (15 and 33). Salinity during embryogenesis did not affect development duration or eye size, but altered other embryonic traits: embryos at low salinity showed higher heart rate, larger egg volume, and increased egg mass at late stages. In larvae, salinity was the main driver, strongly affecting development, survival, and metabolic performance, whereas pH alone had limited or stage-dependent effects. However, their interaction intensified responses, particularly increasing mortality. Low salinity during the larval stage increased intermolt duration and mortality, effects further exacerbated under low pH. The strongest negative responses occurred under combined low salinity and low pH, with delayed development, higher mortality, and reduced oxygen consumption rates. Although low salinity during embryogenesis influenced larval performance under low pH, larval responses were primarily driven by current environmental conditions. These results highlight that co-occurring stressors can outweigh early-life conditioning. Given that low salinity events and acidification frequently co-occur in estuarine systems, their interaction is critical for understanding organismal responses.
Continue reading ‘Carry-over effects of low salinity during embryonic development modulate larval responses to combined salinity-pH stress in an estuarine crab’
