The dynamics of calcium carbonate structures in marine organisms (skeletons and shells) has become increasingly important due to heightened interest in marine environmental acidification. Research into molluscan shell corrosion and calcification in response to acidification is typically carried out in laboratory-controlled settings, which often overlooks the intricate interactions found in natural environments. Mollusks inhabiting intertidal zones are especially susceptible to intense shell weathering caused by tidal cycles of heating, cooling, wetting, and drying, exacerbated by solar radiation during periods of air exposure. We investigated the effect of sun exposure (solar radiative heating) on both outer shell corrosion and inner shell compensatory calcification in the tropical oyster, Saccostrea scyphophilla. Shell properties were compared between oysters from neighboring populations in sun-exposed and shaded habitats. Habitat temperatures were measured using iButtons, and right shell valve corrosion was quantified. Compensatory calcification was assessed through measurements of shell thickness, shell density, shell compression strength, and mineralogical properties. Our results revealed that oysters in the sun that experience global irradiance, higher temperature peaks and broader daily temperature ranges (averaging an increase of 10 °C) show considerably greater outer shell surface corrosion (87%) compared to shaded oysters (31%) that experience only diffuse irradiance. Sun-exposed shells also become thickened in the midsection and around the adductor muscle, and they are slightly stronger, indicating compensation for the outer shell loss. These findings highlight the need for caution when interpreting molluscan shell dynamics based on laboratory marine acidification protocols that fail to account for the many natural environmental factors influencing shell formation and dissolution.
Continue reading ‘Strong effects of sun exposure on oyster shell corrosion and compensatory calcification: a factor confounding coastal acidification responses’Posts Tagged 'biological response'
Strong effects of sun exposure on oyster shell corrosion and compensatory calcification: a factor confounding coastal acidification responses
Published 13 July 2026 Science ClosedTags: biological response, calcification, field, laboratory, molecular biology, mollusks, North Pacific, physiology
Impacts of warming, acidification, and deoxygenation on embryos and larvae of gilthead seabream (Sparus aurata)
Published 13 July 2026 Science ClosedTags: biological response, fish, laboratory, mortality, multiple factors, oxygen, physiology, reproduction, temperature
Simple Summary
This study evaluated how the combination of ocean warming, acidification, and deoxygenation (“deadly trio”) affects the early development of the fish Sparus aurata. Embryos and recently hatched larvae were exposed to increased temperature (Δ + 4 °C; 22 °C), elevated CO2 levels (pCO2 ~1000 μatm, Δ − 0.4 units; pH 7.7), and reduced oxygen (Δ − 60% O2 saturation; 3 mg O2 L −1). Deoxygenation emerged as the primary stressor, significantly reducing hatching rates, larval survival, and heart rates. These effects were further intensified when combined with warming and acidification. Acidification alone also reduced larval phototactic behavior by 50%, while exposure to all three stressors eliminated phototactic responses entirely. Overall, the results demonstrate that multiple climate-related stressors together severely harm fish early life stages, emphasizing the need to study combined environmental changes to better predict future impacts of climate change on marine fish populations and ecosystem functioning.
Abstract
The interaction between increased dissolved carbon dioxide, rising temperatures, and oxygen loss—the so-called “deadly trio”—is expected to strongly affect marine biota over the coming years, undermining ocean services and uses. Nonetheless, no study has so far scrutinized the cumulative impact of these three stressors on fish embryos and larvae. To fill this knowledge gap, we conducted a fully multi-factorial experiment to investigate the effects of warming (+4 °C: 22 °C), acidification (Δ − 0.4 pH units: 7.7 pH, pCO2 ~1000 μatm), and deoxygenation (Δ − 60% O2 saturation: 3 mg O2 L−1) on physiological and behavioral responses of the commercially important species Sparus aurata. Deoxygenation was the primary factor reducing hatching rates (64.25%), survival (46.71%), and heart rates (31.99%) of recently hatched larvae, being generally further exacerbated when combined with warming and acidification. No larvae exposed to the interaction of the three treatments reacted to the phototactic behavior test. However, acidification alone caused a 50% reduction in phototactic behavior. Our findings demonstrate that the deadly trio is detrimental to early fish development, impacting several key features at this critical life stage, and the need to assess the impacts of stressors’ interaction on marine taxa to better predict future ecosystem responses to ocean changes.
Continue reading ‘Impacts of warming, acidification, and deoxygenation on embryos and larvae of gilthead seabream (Sparus aurata)’The effects of single and multiple climate-driven stressors exposures on the seagrass Posidonia oceanica: phenological, cellular, and genetic adaptations
Published 10 July 2026 Science ClosedTags: adaptation, biological response, Mediterranean, phanerogams
Posidonia oceanica is a foundation seagrass species endemic to the Mediterranean Sea, where it forms highly productive meadows that support biodiversity, coastal protection and long-term blue carbon storage. However, these ecosystems are increasingly threatened by the combined effects of climate change and local anthropogenic pressures, including ocean warming, marine heatwaves, ocean acidification, hypersalinity and thermal pollution. Despite growing evidence of the vulnerability of P. oceanica to environmental change, the mechanisms underlying its acclimation capacity, resilience and potential vulnerability thresholds remain only partially understood, particularly under multiple-stressor scenarios.This study investigates the responses of P. oceanica to climate change-related stressors across multiple levels of biological organization, integrating evidence from meta-analysis, controlled mesocosm experiments, molecular analyses and field observations. Special attention is given to the role of environmental history in shaping population-specific responses, comparing plants exposed to contrasting environmental conditions and assessing their phenological, physiological, metabolic and molecular performance under single and combined stressors.By linking organismal, molecular and meadow-scale responses, this work provides new insights into the capacity of P. oceanica to cope with future climate scenarios and local anthropogenic disturbances. The findings contribute to identifying resilience mechanisms and vulnerability patterns in Mediterranean seagrass ecosystems, supporting the development of more effective monitoring, management and conservation strategies under ongoing global change.
Continue reading ‘The effects of single and multiple climate-driven stressors exposures on the seagrass Posidonia oceanica: phenological, cellular, and genetic adaptations’The fate of macroalgal carbon under microbial anaerobic respiration: a critical factor in macroalgae cultivation for climate change mitigation
Published 8 July 2026 Science ClosedTags: algae, biological response, laboratory, mitigation
Highlights
- Anoxic remineralization rates were not consistently lower than oxic rates.
- Macroalgal degradation modulates the DIC pool, crucial for carbon sequestration.
- Alkalinity generated by anaerobic respiration stabilizes the DIC pool.
Abstract
Macroalgae play a significant role in global carbon sequestration. Substantial macroalgal organic carbon inputs and subsequent degradation can cause deoxygenation; however, the impact of oxygen deficiency on carbon fate remains understudied, which is critical for assessing the climate mitigation role of macroalgae. Here, we investigated changes in the carbon pool and non-CO2 greenhouse gases (N2O and CH4) to assess the influence of oxygen levels on the carbon sink capacity of macroalgae. The microbial remineralization rate of macroalgal organic matter was not consistently slower under anoxic conditions (AK) compared to oxic conditions (OK). Total organic carbon (TOC) concentrations in the water column were 530 ± 94 (OK) and 282 ± 38 (AK) μmol kg−1. For dissolved inorganic carbon (DIC), concentrations on day 30 were 4585 ± 197 (OK) and 5200 ± 492 (AK) μmol kg−1, while those for total alkalinity (TA) were 2684 ± 18 (OK) and 4523 ± 671 (AK) μmol kg−1. Following a 30-day sealed incubation, the bags were opened to reach atmospheric equilibrium. Subsequently, DIC dropped to 1837 ± 79 (OK) and 3744 ± 354 (AK) μmol kg−1, and TA fell to 2059 ± 14 (OK) and 4431 ± 657 (AK) μmol kg−1. Ultimately, relative to the control group (seawater only, OS) under air-sea equilibrium, the ΔDIC values were −22 ± 76 and 1885 ± 351 μmol kg−1 in the OK and AK treatments, respectively, while ΔTA values were −57 ± 11 and 2315 ± 655 μmol kg−1. The emissions of N2O and CH4 did not substantially offset the climate effect of carbon sequestration. These results suggest that, beyond the traditional focus on organic carbon preservation, anaerobic respiration under anoxic conditions may also contribute to macroalgal carbon sequestration by generating alkalinity that enhances the retention and stabilization of DIC.
Continue reading ‘The fate of macroalgal carbon under microbial anaerobic respiration: a critical factor in macroalgae cultivation for climate change mitigation’Evaluating the combined effects of ocean acidification and harmful algal blooms on the fitness of Artemia salina
Published 6 July 2026 Science ClosedTags: biological response, crustaceans, laboratory, mortality, multiple factors, performance, physiology, reproduction, toxicants, zooplankton
This study assessed the potential synergistic effects of harmful algal blooms (HABs) and ocean acidification (OA) on the survival and grazing potential on HABs by brine shrimp (Artemia salina). The effects on the fitness of three life stages (i.e. newly hatched, 1-week old, and 2-week old post hatch) of A. salina was evaluated over a 24-hour period. Using well plates, A. salina were individually exposed to toxin producing HABs (i.e. Alexandrium catenella or Margalefidinium polykrikoides), a non-toxin producing HAB (i.e. Gymnodinium aureolum), and fed or unfed non-HAB controls. pH conditions administered were ambient (pH ~ 8) or acidified (pH ~ 7.2). Survival analysis revealed a significant effect of treatment on mortality across life stages. Hazard ratios showed elevated mortality in HAB treatments relative to controls, while OA alone did not. HAB exposure or ontogeny are more important for survival of A. salina than short-term OA exposure. Regarding grazing potential, significant reductions in HAB cell density were more commonly found in treatments with older individuals than younger conspecifics. Cell density of A. catenella was never significantly reduced as compared with other HAB treatments. Overall, exposure to OA conditions did not affect the survival or grazing potential of A. salina, but the species of HAB did.
Continue reading ‘Evaluating the combined effects of ocean acidification and harmful algal blooms on the fitness of Artemia salina’Interactive effects of triclosan, microplastic vectors, and ocean warming–acidification on sea urchin embryo development
Published 6 July 2026 Science ClosedTags: biological response, echinoderms, growth, laboratory, morphology, multiple factors, North Atlantic, physiology, plastics, reproduction, toxicants
Highlights
- Microplastics modulate triclosan toxicity in a concentration-dependent manner.
- Microplastic loads reverse triclosan attenuation affecting larval development.
- Acidification amplifies triclosan–microplastic toxicity in sea urchin embryos.
- Ocean Warming modulates toxicity; degree-day normalization reveals hidden stress.
Abstract
Understanding how emerging contaminants interact with climate-driven stressors is essential for accurate ecological risk assessment in coastal ecosystems. This study evaluates the individual and combined effects of triclosan (TC), polyethylene microplastics (MP), ocean warming (OW), and ocean acidification (OA) on the early development of Paracentrotus lividus embryos. A tiered experimental design was implemented to: (i) characterize TC dose–response curves alone and in combination with increasing concentrations of MP (300–3000 particles mL−1), and (ii) assess how OW (24 °C) and OA (pH 7.6) modulate contaminant toxicity. TC showed concentration-dependent growth inhibition, while MP exhibited a biphasic interaction with TC: at moderate concentrations, MP increased EC10 values and steepened dose–response slopes, consistent with contaminant sorption reducing freely dissolved TC. At 3000 particles mL−1, this trend reversed, lowering EC50 values and enhancing toxicity. Morphometric analyses revealed that co-exposure to TC alone and with MP loads impaired arm elongation, increased body-width ratios, and reduced stomach volume, indicating compromised feeding and skeletal development. Climate stressors significantly altered toxicological outcomes. OA strongly amplified the combined toxicity of TC + MP, reducing larval growth to near-zero levels, whereas OW alone did not exacerbate toxicity and partially mitigated OA-driven effects in MP-TC treated groups. Degree-day normalization demonstrated that warming accelerates development but reduces growth efficiency across treatments. Overall, these results reveal threshold-dependent MP–TC interactions and highlight acidification as a critical amplifier of contaminant effects. Incorporating realistic MP–pollutant interactions and climate variables is crucial for improving hazard assessments under future ocean scenarios.
Continue reading ‘Interactive effects of triclosan, microplastic vectors, and ocean warming–acidification on sea urchin embryo development’Assessing early oil industry awareness of the impacts of fossil fuels on coral reefs using a novel AI agent
Published 3 July 2026 Science ClosedTags: biological response, corals, modeling, review
Global warming threatens to eradicate Earth’s tropical corals. As legal interventions addressing climate change expand, fossil fuel companies’ historical awareness of their products’ damaging effects is increasingly important. We searched historical documents using a large-language-model-based agent, finding that carbon majors were aware by the 1980s of prospective impacts of fossil fuels on corals from ocean acidification, marine heatwaves, sea-level rise, and intensified storms and later funded efforts downplaying such impacts.
Introduction
The world’s tropical coral reefs are under imminent threat of collapse from global warming. Living corals have declined by approximately 50% worldwide since the 1990s, with global warming now the greatest threat to future survival1. Global warming kills corals primarily through increased ocean temperatures and more frequent and intense marine heatwaves, which cause coral bleaching (loss of coral symbionts), exacerbated by ocean acidification (from increased carbon dioxide levels), which weakens coral health, and intensified storms (from increased sea surface temperatures), which physically destroy coral assemblages, all ultimately caused by fossil fuels1. Approximately one billion people worldwide depend directly on coral reefs for livelihoods, food security, and protection from storms and coastal erosion, and coral reefs provide shelter and nourishment to over 30% of the world’s named marine species2. Economically, coral reefs provide an estimated 10 trillion USD per year in ecosystem services, including tens of billions of dollars per year in coral reef tourism3, and potential efforts to restore reefs lost over the last decade alone have been estimated to cost around 1 trillion USD2. Mass coral bleaching and mortality from marine heatwaves driven by global warming is ongoing4. The Intergovernmental Panel on Climate Change (IPCC) predicts mortality of 70—90% of the world’s reef-building corals at global warming of 1.5 °C and mortality of more than 99% at 2 °C1.
Legal interventions may play a critical role in helping to protect the world’s coral reefs and associated ecosystems (for example, by securing funding for reef monitoring and rehabilitation) and in compensating affected communities for economic losses associated with climate-change-driven coral impacts. In this context, the history of fossil fuel industry awareness of the foreseeable impacts of climate change on coral reefs is highly relevant. Climate lawsuits against governments, fossil fuel producers, and other parties have expanded in number and sophistication over the past decade5 and have recently cited impacts on coral reefs6. Additionally, the 2024 and 2025 advisory opinions from the International Tribunal for the Law of the Sea (ITLOS)7 and the International Court of Justice (ICJ)8 on climate change clarified, respectively, that greenhouse gases are marine pollutants under the United Nations Convention on the Law of the Sea (UNCLOS) and that best efforts to attain the 1.5 °C warming limit of the United Nations Framework Convention on Climate Change (UNFCCC) Paris Agreement are legally binding on governments under international law, strengthening the basis for legal actions seeking to mitigate global warming and obtain reparations for damages. Research on the fossil fuel industry’s internal knowledge of global warming9, public-facing denial and minimization of the problem10,11, and false assurances to be solving it12 has clarified global warming as not only a scientific and technological problem but also one of corporate corruption subject to legal correction and remedy13. Such research has so far informed dozens of ongoing legal actions seeking industry accountability for climate change14.
Continue reading ‘Assessing early oil industry awareness of the impacts of fossil fuels on coral reefs using a novel AI agent’Short-term plasticity and long-term transcriptomic rewiring under natural ocean acidification in an ecosystem-relevant sea urchin
Published 1 July 2026 Science ClosedTags: biological response, BRcommunity, echinoderms, laboratory, molecular biology, North Atlantic, vents
Highlights
- Natural CO2 vents reveal transcriptomic responses to chronic ocean acidification.
- Acute low-pH exposure triggers rapid but limited plastic responses in Arbacia lixula.
- Vent-origin Arbacia lixula exhibit extensive metabolic reprogramming and antioxidant activation.
- Low pH supresses biomineralization genes and up-regulates collagen and extracellular matrix pathways.
- Persistence under ocean acidification is associated with energetic trade-offs and skeletal homeostasis.
Abstract
Ocean acidification is reshaping coastal ecosystems as a consequence of anthropogenic CO2 emissions. Natural CO2 vent systems provide valuable analogues for investigating organismal responses to long-term acidified conditions under ecologically realistic scenarios. Here, we examined genome-wide transcriptomic responses of the sea urchin Arbacia lixula, an ecosystem-relevant grazer inhabiting a natural CO2 vent system in La Palma (Canary Islands, Spain). Using RNA sequencing of 24 adults (n = 8 per treatment), we compared: (i) acute experimental exposure of ambient-origin individuals to low pH, (ii) chronic exposure by comparing ambient and vent-origin populations in their native pH conditions, and (iii) a genotype-of-origin comparison under shared low pH. Acute exposure triggered a limited transcriptional response (116 differentially expressed genes, DEG), characterized by activation of ion transport, redox regulation, and NAD-associated metabolism. In contrast, chronically exposed vent-origin urchins showed a tenfold increase in transcriptional changes (1053 DEG), reflecting metabolic reprogramming involving lipid, carbohydrate and amino acid pathways, and strengthened antioxidant capacity. Chronic low-pH exposure was also associated with suppression of biomineralization and developmental genes, alongside strong upregulation of collagen and extracellular matrix–associated genes that may help maintain skeletal performance under reduced carbonate availability. Genotype-of-origin effects (131 DEGs) revealed constitutive differences in metabolic, redox, extracellular matrix, and biomineralization pathways in vent populations. Together, these findings indicate that persistence under natural acidification involves both rapid plastic responses and sustained physiological reorganization, providing mechanistic insight into how calcifying species maintain functional performance under ongoing ocean acidification.
Continue reading ‘Short-term plasticity and long-term transcriptomic rewiring under natural ocean acidification in an ecosystem-relevant sea urchin’Impact of water quality and gear type on Eastern oyster (Crassostrea virginica) growth in Narragansett Bay, RI
Published 1 July 2026 Science ClosedTags: biological response, growth, laboratory, mollusks, mortality, North Atlantic, physiology
Oyster aquaculture is expanding in Rhode Island, yet key farming regions in the lower West Passage of Narragansett Bay (WPNB) lack the in-situ, high-temporal resolution monitoring needed to evaluate emerging stressors and support production. At the same time, the industry is undergoing rapid technological development aimed at improving production while reducing labor and overall costs. In recent years, a low maintenance, alternative surface gear was introduced in WPNB; however, its impact on oyster performance relative to traditional cultivation methods has not been quantified. This study established a 1.5-year continuous water quality time series in WPNB and paired these observations with physiological assessments of Crassostrea virginica grown in three cultivation methods (i.e., traditional surface, alternative surface, and bottom gear). This work aimed to better understand the impact of environmental variability and gear type on oyster health, growth, and survival. Multiparameter sondes and discrete bottle samples were used to monitor water quality and calculate carbonate saturation state (Ω) at a 4-acre oyster farm. Nine mesh bags containing early-life stage C. virginica (16 ± 0.4 mm; n = 300 per bag) were deployed in July 2025, with three replicate bags in each gear type. Subsamples (n = 15) from each gear type were collected over a 6-month period for morphometric measurements and scope for growth (SFG) determinations. Minimal differences in carbonate chemistry were observed among sampling sites and Ω remained supersaturated (Ω >1) for the majority of the study period, indicating that ocean acidification was not a major stressor for farmed oysters. Survival was highest (82 ± 4.5%) in surface gear types compared to bottom gear (27 ± 0.58%), while physical growth (shell and tissue) and SFG were largely similar among all gear types. These results suggest that the alternative surface gear may support comparable production and product quality to traditional gear types, while also reducing maintenance and labor demands. Overall, this study provides important physiological and biological context for oyster aquaculture while informing gear selection and farm management strategies.
Continue reading ‘Impact of water quality and gear type on Eastern oyster (Crassostrea virginica) growth in Narragansett Bay, RI’Climate change and aquatic ecosystems: impacts on salinity, species survival, and ecological resilience
Published 29 June 2026 Science ClosedTags: biological response, fisheries, mesocosms, mortality, phytoplankton, reproduction, review, salinity
Highlights
- Unveils Climate-Driven Disease Mechanisms Across Aquatic Systems.
- Integrates Multistressor Impacts Including Pollution, Eutrophication, and Salinity Fluctuations.
- Explores Shifts in Species Distribution, Reproduction, and Food Web Dynamics.
- Highlights Adaptive Traits and Resilience Mechanisms in Aquatic Organisms.
- Provides Science-Based Recommendations for Climate-Responsive Management.
Abstract
Climate change is rapidly transforming aquatic ecosystems, posing complex environmental challenges with far-reaching ecological and socio-economic implications. Rising temperatures, sea-level rise, altered precipitation patterns, shifting hydrological regimes, and sea-ice loss are intensifying pressures on coastal, estuarine, freshwater, and polar systems. These stressors contribute to habitat degradation, increased frequency of hypoxic events, and altered species distributions. Crucially, while some dual stressors, such as warming and acidification, can paradoxically increase primary producer biomass, our findings reveal that this resultant biomass often accumulates as detritus rather than being efficiently transferred to higher trophic levels. This observation directly challenges the simplistic assumption that “more growth” is invariably beneficial, highlighting complex indirect effects on food web dynamics and ecosystem function. Ecological perturbations propagate through trophic networks, resulting in biodiversity loss, reduced ecosystem resilience, and declining fisheries productivity, thereby threatening food security and coastal livelihoods. Marine and freshwater organisms are increasingly exposed to multiple, interacting stressors, including warming, acidification, salinity fluctuations (requiring distinct osmoregulatory strategies, e.g., heterosmotic regulation in teleosts vs. isosmotic intracellular regulation in crustaceans), pollution, and overexploitation. These cumulative pressures can exacerbate disease outbreaks, modify host–pathogen dynamics, and facilitate the emergence and spread of aquatic pathogens, with consequences for ecosystem stability and human health. In aquaculture systems, climate-driven stress often acts synergistically with anthropogenic disturbances, amplifying production risks and economic vulnerability. Furthermore, anthropogenic infrastructure like reservoirs can act as unintended hubs facilitating species dispersal following extreme events like floods, altering community structures. At the biogeochemical scale, climate-induced alterations in nutrient cycling, primary productivity, and carbon sequestration are reshaping ecosystem functioning, particularly in high-latitude and freshwater environments where adaptive capacity is comparatively constrained. Changes in food web architecture and energy transfer efficiency further compromise ecosystem services. This review specifically centers on the biological and ecological mechanisms underlying these climate-driven changes, including organism-level stress responses, shifts in species interactions, and alterations in pathogen dynamics. Recognizing the societal implications and public discourse surrounding climate change underscores the urgency of examining its tangible impacts on sensitive environments, such as estuarine ecosystems, which serve as critical interfaces between terrestrial and marine realms and are thus highly susceptible to both climatic shifts and human influence.
Continue reading ‘Climate change and aquatic ecosystems: impacts on salinity, species survival, and ecological resilience’Skeletal porosity of a cold-water coral increases with decreasing aragonite saturation state along a depth gradient in the Mediterranean Sea
Published 29 June 2026 Science ClosedTags: biogeochemistry, biological response, BRcommunity, chemistry, corals, laboratory, Mediterranean, physiology
Background
Cold-water corals (CWCs) are key ecosystem engineers that create complex three-dimensional habitats much like tropical reefs, but in deep, cold seas. However, like other reef-building systems, they are increasingly threatened by climate change and ocean acidification. CWC communities in the Mediterranean Sea may be especially vulnerable because these waters absorb more atmospheric CO2 than the global ocean, making it a mesocosm that mirrors broader global trends affecting marine life. Since calcification is energetically costly and likely becomes even more demanding as pH and carbonate ion availability decline, understanding how the decrease in aragonite saturation state (Ωarag) affects biomineralization is essential for predicting the future of these corals.
Results
Here, we investigated skeletal structural and compositional changes of the scleractinian CWC Desmophyllum dianthus along an Ωarag gradient in the Mediterranean Sea using specimens collected between 400 and 1200 m depth. Our findings indicate that skeletal porosity increases at the macro-scale with decreasing Ωarag, while micro- and nano-scale structural and compositional features remained unaffected.
Conclusions
The persistence of micro- and nano-scale skeletal features across an 800 m depth gradient suggests that D. dianthus maintains tight biological control over mineralization at these scales, even as Ωarag declines. This control does not extend to the macro-scale, where increasing porosity alters the skeleton’s overall architecture under lower Ωarag. D. dianthus thus appears to preserve the fundamental “building blocks” of its skeleton while changing its larger-scale structure, a decoupling that may make macro-scale porosity an early marker of acidification stress in CWCs.
Continue reading ‘Skeletal porosity of a cold-water coral increases with decreasing aragonite saturation state along a depth gradient in the Mediterranean Sea’Acute low pH associated with coastal acidification is detrimental to larval development of the Cape urchin Parechinus angulosus
Published 26 June 2026 Science ClosedTags: biological response, BRcommunity, echinoderms, growth, Indian, laboratory, mortality, physiology, reproduction
Acidification in coastal habitats is increasing in duration and amplitude under the continued influence of ocean acidification and contributing coastal processes. The impacts of low pH conditions on calcifying organisms, especially echinoderms, is well established, with the early developmental stages being especially vulnerable. This is the first study to assess the impact of locally relevant coastal acidification scenarios on the early development of the Cape urchin Parechinus angulosus. Our findings suggest that the early larval stages of this species are unlikely to survive when exposed to low pH conditions, specifically during the onset of skeletogenesis. In our laboratory experiments, larvae that were exposed to the low pH treatment (pH 7.32) showed significantly reduced growth (GLMM, Time × Treatment interaction: β = −0.361 ± 0.019, z = −19.06, p < 0.001) and developmental regression compared with those from the control treatment (pH 7.95). Substantially slower growth rates were observed in the low pH treatment (length = 72.3 hpf0.18) compared with in the control treatment (length = 24.24 hpf0.54). There was also evidence of abnormal and delayed development and potential dissolution of skeletal structures under the low pH condition. However, fertilisation success and larval survival did not differ significantly between the experimental treatments, suggesting that developmental impacts of low pH over short durations, even though substantial, may be sublethal. The developmental impacts are likely to impair the transition of larvae to the adult stages, which may ultimately affect populations of this ecologically important species under future coastal acidification scenarios.
Continue reading ‘Acute low pH associated with coastal acidification is detrimental to larval development of the Cape urchin Parechinus angulosus’Will the Mediterranean sea be a cul-de-sac for marine gastropods under climate change?
Published 23 June 2026 Science ClosedTags: biological response, BRcommunity, communitymodeling, individualmodeling, Mediterranean, modeling, mollusks, North Atlantic, physiology, reproduction
Marine ecosystems are undergoing rapid transformation under climate change, yet the responses of many marine invertebrates remain vastly understudied. In particular, for many benthic gastropods there is a striking imbalance between their traditional appreciation by shell collectors—and, consequently, their consistent representation in Natural History Collections—and the limited attention they receive in ecological and conservation studies. Focusing on the northeastern Atlantic and the Mediterranean, the cowries Luria lurida, Naria spurca, Zonaria pyrum and the frog-shell Talisman scrobilator are emblematic examples of this knowledge gap, despite being frequently mentioned as species of conservation concern. Using long-term occurrence records spanning more than a century, we modelled past and present distributions of these species and explored their potential responses to future climate scenarios through a multi-temporal Species Distribution Modelling framework. Our results show that intermediate climatic conditions—both in time (2050–2060 vs. 2090–2100) and scenario intensity (moderate SSP2-4.5 versus high-emission SSP5-8.5)—may represent a critical transition phase, leading to habitat contractions without compensatory gains in newly emerging suitable areas. The Mediterranean Sea is expected to increasingly function as a cul-de-sac, with the dominant circulation patterns strongly limiting outward movements towards cooler regions for species relying on planktic larvae for dispersal. Furthermore, incorporating larval sensitivity to reduced pH suggests that large areas of the Atlantic Ocean may actually result unsuitable for larval persistence, substantially reducing the habitat effectively available for completion of the full life cycle; this highlights the need to account for connectivity, life-history constraints and juvenile-stage sensitivity when assessing climate-driven range shifts in shelled organisms with planktic larvae.
Continue reading ‘Will the Mediterranean sea be a cul-de-sac for marine gastropods under climate change?’Physical-chemical gradients, CO2 venting dynamics and microbial community composition in a shallow Mediterranean CO2-rich hydrothermal system
Published 19 June 2026 Science ClosedTags: biogeochemistry, biological response, chemistry, community composition, Mediterranean, otherprocess, physiology, prokaryotes, vents
Shallow-water CO2-rich hydrothermal systems provide natural laboratories for studying localized ocean acidification under realistic environmental conditions. Here, we present a multidisciplinary characterization of the Calent mound CO2-rich system (Columbretes Islands, Western Mediterranean), based on oceanographic surveys conducted in 2020 and 2021. Localized pH anomalies were detected directly above active vents, reaching maximum reductions of 1.12 pH units, whereas water-column temperature anomalies were minimal and subsurface sediment temperatures exceeded ambient seawater by 5.67 °C. Gas analyses indicated high CO2 concentrations (0.094 ± 0.008 mol L− 1), with heterogeneous degassing regimes, ranging from sporadic to continuous emissions and an average flux of 189.4 ± 15.4 kg CO2 m− 2 yr− 1 at the active vent field. Vent fluids were significantly enriched in dissolved inorganic nutrients, particularly silicate, phosphate, nitrate+nitrite, and ammonium. Benthic microbial mats hosted metabolically diverse prokaryotic and eukaryotic communities, including hydrothermal-associated taxa such as Zetaproteobacteria, Campylobacterota, and Nitrosophaeria, consistent with iron, sulfur, and ammonia oxididation metabolisms. Several microbial core taxa persisted across years despite shifts in relative abundance. These findings demonstrate that Calent mound sustains an intense yet highly localized biogeochemical environment within the photic zone, where CO2 venting and nutrient inputs jointly influence carbonate chemistry and microbial community structure.
Continue reading ‘Physical-chemical gradients, CO2 venting dynamics and microbial community composition in a shallow Mediterranean CO2-rich hydrothermal system’Marine invertebrates and fishes exhibit inconsistent body size responses to ocean acidification
Published 18 June 2026 Science ClosedTags: algae, annelids, biological response, BRcommunity, bryozoa, cnidaria, community composition, corals, crustaceans, echinoderms, fish, Indian, laboratory, mollusks, morphology, North Pacific, otherprocess, physiology, vents
Body size is a fundamental characteristic of all living organisms that determines physiological functions and life-history traits. Ecological theory predicts that ocean acidification can cause body size reductions, confirmed by several studies reporting miniaturization in ectotherms. Based on this prediction, we would expect a broad suite of species to show similar plastic body-size responses to elevated CO2. Using four natural climate change analogues of ocean acidification across the northern and southern hemispheres, we quantified body size alterations across 18 marine invertebrate and fish taxa to test for climate-driven miniaturization. Only three species consistently showed body-size reductions under ocean acidification: one urchin and two fish species. In contrast, 15 other species, ranging from highly calcified to non-calcified, displayed unchanged or increased body sizes or inconsistent miniaturization. If body-size miniaturization responses were consistently reproducible across taxa we would have observed it more frequently, suggesting that species responses to ocean acidification are more variable than previously thought and likely vary depending on a species’ physiology and life history. Thus, rather than entire communities undergoing miniaturization, species are likely to display a spectrum of responses, with some exhibiting size reductions, others demonstrating physiological resistance to elevated CO2, and others potentially benefiting from the indirect effects of ocean acidification.
Continue reading ‘Marine invertebrates and fishes exhibit inconsistent body size responses to ocean acidification’Pteropod vulnerability to ocean acidification in the eastern Arabian Sea
Published 18 June 2026 Science ClosedTags: biological response, BRcommunity, Indian, laboratory, mollusks, zooplankton
Highlights
- First study on pteropod response to ocean acidification in the eastern Arabian Sea.
- High pteropod abundance during fall inter monsoon season due to food availability.
- pH in the Arabian Sea was low during south west monsoon with pHT upto 7.75
- Pteropod shell dissolution was observed under acidified conditions
- Protrusions through the pteropod shell were observed under acidified conditions
Abstract
The rapid rise in atmospheric CO2 and its subsequent uptake by the oceans has led to ocean acidification and other associated changes in the marine ecosystem. The recent reports of the shoaling of the aragonite saturation horizon in the northern Indian Ocean are particularly alarming, as they pose a serious threat to the survival of calcareous organisms. Pteropods, also known as sea-butterflies, are believed to be highly susceptible to ocean acidification due to their thin aragonite shell. In our study in the eastern Arabian Sea, we found low pH conditions with surface pHT as low as 7.751 during late South-west monsoon (SWM). The pteropod abundance is high during the fall inter-monsoon (FIM), suggesting that the system continues to sustain productivity even after the cessation of peak monsoon activity. This also implies that the food availability regulates pteropod abundance in the eastern Arabian Sea. As pteropods are key components of food sources for many marine species, such as fish, any changes in their abundance can have cascading effects on the marine food web. To show how pteropods will be affected in futuristic elevated CO2 conditions, a CO2 manipulation experiment was conducted in the eastern Arabian Sea during December 2024. Pteropods belonging to Creseis acicula from the eastern Arabian Sea were subjected to pHT = 7.470, and pCO2 = 1734 μatm under controlled conditions. Our findings suggest that acidification led to the dissolution of pteropod shells. Acidification also led to protrusion through the shells, and these protrusions varied in length up to 88 μm. These structural alterations represent an acute response of pteropod shells to reduced pH, highlighting their rapid vulnerability to acidification stress. These observed protrusions need to be assessed further to determine if they provide any competitive advantage in combating or minimizing the impact of ocean acidification.
Continue reading ‘Pteropod vulnerability to ocean acidification in the eastern Arabian Sea’Temperature, but not acidification, influences the growth and lipid profile of juvenile sand whiting, Sillago ciliata (Cuvier 1829)
Published 18 June 2026 Science ClosedTags: biological response, fish, Indian, mesocosms, morphology, multiple factors, physiology, reproduction, temperature
Seafood provides an essential source of macro- and micronutrients for coastal communities worldwide. Climate change is a key threat to seafood security, altering the sizes, abundances, distributions, physiology and ecological interactions of fisheries species, and increasingly, there is evidence of impacts to seafood nutritional quality. In a 12-week mesocosm experiment, we tested the influence of projected ocean warming and acidification scenarios on the growth and lipid quality of juvenile sand whiting (Sillago ciliata), a popular fisheries species in eastern Australia. The growth of S. ciliata significantly increased (by 61% body weight) under elevated temperature (+3°C) but was not affected by acidification treatment levels. Lipidomic analysis revealed no influence of temperature or acidification on total lipid content or the composition and total proportions of lipid classes and subclasses. However, elevated temperatures significantly impacted the overall composition of fatty acids, including a shift toward higher saturation and a decline in important omega-3 fatty acids. Fish exposed to elevated temperature treatments had more saturated fatty acids than those at control temperatures, along with reduced levels of the valuable omega-3 eicosapentaenoic (C20:5) and docosahexaenoic (C22:6) fatty acids. Despite impacting fatty acid composition in S. ciliata, the increased growth of the juvenile whiting, if sustained into adulthood, under elevated temperatures, may help compensate for the overall availability of essential polyunsaturated fatty acids to support consumer nutritional requirements. These findings contribute to the growing body of evidence on variable climate resilience in nearshore species to future environmental conditions and the implications for the trophic transfer of nutrients in estuarine ecosystems.
Continue reading ‘Temperature, but not acidification, influences the growth and lipid profile of juvenile sand whiting, Sillago ciliata (Cuvier 1829)’Shifts of tentacles-associated prokaryotes of Anemonia viridis along a natural pH gradient
Published 18 June 2026 Science ClosedTags: biological response, BRcommunity, cnidaria, community composition, laboratory, Mediterranean, molecular biology, otherprocess, physiology, prokaryotes, sediment
Highlights
- A. viridis tentacle microbiomes were studied under changing natural pH conditions.
- Notable shifts in the abundance of specific taxa emerged in the acidified sites.
- Differences in seawater emphasized the host’s unique microbial signature.
- Rickettsiales predominance suggested a specialized ecological role in symbiosis.
- Further research is needed to discern the role of microbes for host resilience.
Abstract
Marine hydrothermal vents are extreme environments that naturally select for organisms with strong resistance and the ability to cope with special conditions of acidification. Sea anemones are an interesting example that are able to buffer intracellular pH conditions. In this study, the influence of a natural pH gradient on microbial communities associated with Anemonia viridis (Cnidaria, Anthozoa) tentacles was investigated. We hypothesized that exposure to a natural pH gradient would be associated with changes in the structure and activity of A. viridis-associated microbial communities, potentially contributing to the host’s resilience in hydrothermal environments. Microbial enzymatic activities within anemones’ tentacles were investigated by incubation with fluorogenic compounds. The leucine amino peptidase activity was highest in the tentacles of specimens living in more acidified sites. A microbial biodiversity loss was observed in bacterial symbionts from less acidified to more acidified sites, with a reduction of relative abundance in certain groups (i.e., Planctomycetota, Firmicutes, and Desulfobacterota). Results obtained by a metabarcoding approach provided interesting insights into the taxonomic shifts of the A. viridis holobiont system in naturally acidified environments.
Continue reading ‘Shifts of tentacles-associated prokaryotes of Anemonia viridis along a natural pH gradient’Response of HAB-forming microalgae competition to ocean acidification, warming, and changing light fields
Published 17 June 2026 Science ClosedTags: algae, biological response, BRcommunity, community composition, growth, laboratory, light, multiple factors, otherprocess, phytoplankton, temperature
In recent years, the East China Sea (ECS) has experienced frequent harmful algal blooms (HABs), driven by the complex interplay of climate change—specifically ocean warming and acidification—and eutrophication-induced light attenuation. Despite their ecological significance, the interactive effects of these environmental stressors on the competitive dynamics between bloom-forming microalgae remain poorly understood. This study aimed to elucidate how warming, reduced light, and elevated CO2 influence the competition between two dominant diatoms. We conducted controlled monoculture and mixed-culture experiments using two key species: Skeletonema costatum and Chaetoceros curvisetus. The experimental design incorporated varying levels of CO2, temperature, and light intensity to simulate future coastal scenarios. Growth rates, peak cell densities, and successional patterns were monitored to assess competitive outcomes under multiple stressors. Monoculture results indicated that high temperature and low light intensity promoted the growth of both species. However, in mixed cultures, these conditions significantly accelerated the time to reach peak density and induced a definitive successional shift from S. costatum to C. curvisetus. Notably, while the general successional pattern was consistent, elevated CO2 further enhanced the competitive advantage of C. curvisetus, particularly when combined with high-temperature and low-light scenarios. These findings suggest that the synergy of future warming, declining light availability, and intensified ocean acidification in the ECS will likely favor C. curvisetus over S. costatum. This shift may increase the frequency of HAB events dominated by C. curvisetus, driving significant climate-related restructuring of phytoplankton communities in coastal ecosystems.
Continue reading ‘Response of HAB-forming microalgae competition to ocean acidification, warming, and changing light fields’
