Posts Tagged 'physiology'

Analysis of the effects of seawater acidification on the biochemical composition and digestive enzyme activities of Oratosquilla oratoria (in Chinese)

Published 11 November 2026 Science Leave a Comment
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Objective

This study aimed to investigate the effects of CO2-induced seawater acidification on the biochemical composition and digestive enzyme activities of mantis shrimp (Oratosquilla oratoria).

Method

A 49-day aquaculture experiment was conducted. Three acidified treatment groups (pH 7.90, pH 7.70, pH 7.50) were established by introducing CO2 gas into seawater, using natural seawater (pH 8.10) serving as the control.

Result

(1) Under acidified conditions, the muscle moisture content of O. oratoria increased with decreasing pH levels. From day 21 onward, the moisture content in the pH 7.70 and pH 7.50 groups exhibited significantly higher than that in the control group (P < 0.05). Conversely, the contents of ash, crude protein, and crude lipid contents decreased with pH reduction. All acidified groups displayed significantly lower ash content than the control from day 7 onward (P < 0.05). The crude protein levels in respective acidified groups became significantly lower than those in the control starting on days 28 (pH 7.90 group), 14 (pH 7.70 group), and 7 (pH 7.50 group), respectively (P < 0.05). All acidified groups showed significantly reduced crude lipid content compared to the control from day 7 onward (P < 0.05). (2) Pepsin and trypsin activities showed an initial increase followed by a decrease, while lipase activity exhibited a gradual increasing trend. Although acidified groups exhibited marginally higher pepsin and trypsin activities than the control at day 7, these enzymes showed declining trends subsequently, with significant inhibition observed in pepsin by day 21 and trypsin by day 35, respectively (P < 0.05). Lipase activities in the acidified groups became significantly elevated compared to the control starting on day 28 (pH 7.90 group), day 7 (pH 7.70 group), and day 7 (pH 7.50 group), respectively (P < 0.05).

Conclusion

When seawater acidification reached pH levels of 7.50–7.30, it induced a stress response in the mantis shrimp (Oratosquilla oratoria). After 7–14 days of exposure, energy reserves such as crude fat and crude protein were mobilized to cope with the acidic conditions. Although the activities of digestive enzymes including pepsin, trypsin, and lipase were temporarily enhanced, this response failed to alleviate the stress caused by seawater acidification.

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Exploring biomineralization in echinoderms: a review of gene regulatory networks through bibliometrics and comparative genomics

Published 11 November 2026 Science Leave a Comment
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Simple Summary

Echinoderms, including sea urchins, sea cucumbers, starfish, brittle stars, and crinoids, produce mineralized skeletons that vary greatly in form among different groups and developmental stages. Understanding how these skeletons form is important for revealing the biological mechanisms underlying skeletal development and diversity. This review summarizes the development and major research themes of echinoderm biomineralization studies and examines the genes involved in skeletal formation across different echinoderm groups. We show that many genes controlling skeletal development are broadly shared among echinoderms, whereas some genes directly involved in mineral formation vary considerably among groups. By integrating previous biological studies with literature-based and genomic comparisons, this review provides a broader understanding of the molecular basis of echinoderm biomineralization and highlights important questions for future research beyond the extensively studied sea urchins.

Abstract

Biomineralization is a defining feature of echinoderms and underlies the formation of their calcitic endoskeletons. Considerable progress has been made in understanding the molecular basis of echinoderm biomineralization, particularly in sea urchins. However, studies of other echinoderm classes remain limited, and a comprehensive comparison of biomineralization genes and gene regulatory networks across the phylum is still lacking. Here, we combine bibliometric analysis with comparative genomic evidence to summarize current advances in echinoderm biomineralization research. Bibliometric analyses reveal the development of the field, major research themes, and emerging directions, whereas comparative genomic analyses provide an overview of biomineralization genes and gene regulatory networks across different echinoderm classes. Comparative evidence indicates that many transcription factors associated with skeletogenesis are widely distributed across echinoderms. In contrast, biomineralization genes exhibit substantial variation among echinoderm classes. These similarities and differences suggest that broadly shared developmental regulators have been integrated with lineage-specific biomineralization genes to generate the diversity of echinoderm skeletal structures. This review provides a comprehensive overview of biomineralization genes and gene regulatory networks in echinoderms and establishes a comparative framework for future studies of skeletal development, gene regulation, and the evolution of biomineralization across the phylum.

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Pathways to calcification in coccolithophores

Published 11 November 2026 Science Leave a Comment
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Calcification by coccolithophores represents a major biogeochemical process in the oceans. Calcification involves the formation of calcite coccoliths within a Golgi-derived compartment inside the cell. These are secreted to the cell surface where they form the coccosphere. Coccolithophore calcification is underpinned by membrane transport processes that deliver the inorganic carbon and calcium substrates from the external seawater to the site of calcification and by the removal of products, namely protons produced in the calcification reactions. Understanding these critical aspects of calcification will provide clearer insights into the responses of coccolithophores to chemical and physical conditions, both in terms of short-term acclimation and long-term adaptation to a changing ocean. In this review we consider these processes, their localization and the specific transporters likely to be involved. We also consider how transport processes are linked to structural aspects of the cell, providing specialized pathways for the substantial ion fluxes involved.

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Global change reshapes marine microbial communities, functions and One Health outcomes

Published 10 November 2026 Science Leave a Comment
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Marine microorganisms underpin primary production, biogeochemical cycling and host-associated symbioses, supporting climate regulation, coastal protection, fisheries and other ecosystem services. Rapid global change, including ocean warming and marine heatwaves, acidification, deoxygenation, eutrophication, pollution and overuse reshape microbial communities and their functions across marine habitats. These changes can alter carbon, nitrogen and sulfur cycles, promote microbialization and harmful algal blooms, disrupt host–microbiome associations and modify pathogen and antimicrobial resistance dynamics, collectively amplifying the ecological and societal impacts of global change. This Review frames marine microbiomes as cross-scale mediators that translate external pressures, including climate change, pollution, eutrophication and habitat degradation, into altered microbial metabolism, biogeochemical fluxes, host-associated health outcomes, ecosystem service consequences and broader One Health risks. We synthesize shared mechanisms and cross-habitat patterns, highlight cases in which microbiome interventions and stewardship could mitigate impacts and/or accelerate recovery, and outline management options ranging from the reduction of local stressors to emerging microbiome stewardship approaches in ecosystem restoration. Building upon this, we outline pathways for embedding marine microbiome science into globally coordinated One Health strategies, operational management protocols and financing frameworks that align economic incentives with long-term ecosystem and public health outcomes.

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Ocean acidification reshapes phytoplankton phosphorus metabolism under phosphate-limited conditions

Published 9 November 2026 Science Leave a Comment
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Phosphorus (P) availability constrains marine productivity, yet how ocean acidification interacts with intensifying phosphate limitation remains unresolved. Here we present multi-omics analyses of >1,000 generations of experimental diatom evolution to disentangle evolutionary and acclimation-driven responses to ocean acidification under different phosphate regimes. Long-term selection under elevated CO2 produced heritable increases in growth and carbon fixation that persisted irrespective of phosphate availability. In contrast, ocean acidification-driven reductions in particulate organic phosphorus were reversed after reciprocal transfers between selection treatments under phosphate limitation, indicating acclimation and environment-dependent P allocation. Multi-omics analyses indicate that the particulate organic phosphorus decline could be attributed to depletion of cellular P reserves and enrichment of non-P cell membrane lipids under combined ocean acidification and phosphate stress. Coastal mesocosm experiments revealed similarly reduced particulate organic phosphorus in natural phytoplankton at low-phosphate stations under ocean acidification. Global meta-transcriptomes further indicate widespread upregulation of gene expression in non-P cell membrane lipid pathways in high-pCO2 and low-phosphate regions. Earth system models predict a 211% to 2,185% decline in particulate organic phosphorus by 2100 under the under the Shared Socioeconomic Pathway (SSP)2–4.5 or SSP5–8.5 scenarios, respectively. These results show that ocean acidification could intensify nutrient imbalance and reshape global phosphorus cycling in marine ecosystems.

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Ocean acidification impairs the chiton shadow defensive response via degradation of aragonitic lenses

Published 9 November 2026 Science Leave a Comment
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Ocean acidification (OA) has the potential to disrupt the behavior of marine organisms by altering the function of γ-aminobutyric acid type A (GABAA) receptors. In addition, OA can impair sensory performance by reducing the calcification of mineralized sensory structures. Some species of polyplacophoran mollusks (chitons) possess calcified visual organs (aragonitic lenses) that contribute to shadow defense responses triggered by sudden decreases in overhead illumination. Therefore, we hypothesized that OA affects this response by impairing GABAA-mediated signaling or lens calcification. To test this hypothesis, we exposed chitons to “control” or acidified seawater and examined their shadow defensive behavior with and without gabazine, a GABAA antagonist known to restore OA-induced GABAergic dysfunction. Although gabazine did not eliminate behavioral differences between the control and acidified groups, acidification reduced the response strength, suggesting that factors other than GABAA-mediated signaling may contribute to the observed behavioral impairment. Microscopic observations revealed clouding of aragonitic lenses under acidic conditions, suggesting reduced optical performance. Overall, our results indicate that OA-induced degradation of calcified lens structures is associated with impaired shadow defense responses and may contribute to behavioral dysfunction. To the best of our knowledge, this study provides the first evidence that acidification-induced physical and optical changes in the visual anatomy can alter behavioral performance in animals.

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Transient disturbance and community convergence of coral-associated microbial communities under acidification, benzo[a]pyrene pollution, and combined stress in coral Acropora millepora

Published 9 November 2026 Science Leave a Comment
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Ocean acidification (OA), driven by global climate change together with pollution from organic contaminants, is increasing the ecological risk faced by coral reef ecosystems. The coral holobiont comprises diverse microbial communities that collectively support the coral host in coping with and adapting to environmental stress. However, the response of the coral holobiont to the combined stress of acidification and benzo[a]pyrene (BaP) remains poorly understood. In this study, Acropora millepora was selected as a model species to investigate the responses of coral-associated microbiomes to acidification (pH 7.8), BaP exposure (10 µg·L−1) and their combined effects. We found that while the cell density of coral-associated Symbiodiniaceae increased significantly with prolonged exposure time in all treatment groups, and there were no temporal differences in chlorophyll-a contents. The Symbiodiniaceae community was stable within all treatments, with Cladocopium as the dominant genus, and subtype C3u had the highest relative abundance (>70%). A rapid and significant increase in rare bacteria taxa was observed in the single-stress treatments (acidification, BaP), whereas prolonged exposure led to an increasing number of unique bacteria taxa in the combined-stress group in two weeks. Surprisingly, the main community structure of core coral-associated bacteria in the combined treatment group was close to that of the control group. Across all treatments, core coral-associated bacteria (including Sphingomonadaceae and Burkholderiaceae) consistently dominated the microbial community, while core coral-associated archaea exhibited more stochastic variations. Collectively, these results highlight the critical role of coral-associated microbiomes in rapidly and flexibly responding to environmental stressors, thereby contributing to the maintenance of holobiont stability under multiple stress conditions.

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Metabolic dynamics of an offshore coral reef in the central Red Sea: observations from autonomous sensors

Published 9 November 2026 Science Leave a Comment
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Abstract

Coral reefs are increasingly threatened by local and global stressors. Traditional visual reef monitoring methods are time-intensive and provide only a snapshot of reef condition. Recent efforts aim to measure reef metabolism, or the balance of net community production (NCP) and net community calcification (NCC), as coral reef carbonate budgets shift globally toward declining NCC and greater NCP influence. Resolving these metabolic changes requires comprehensive, high-resolution biogeochemical measurements unattainable by traditional sampling alone. This work reports the novel multi-month deployment of a high-resolution, autonomous total alkalinity (TA) sensor alongside pH, partial pressure of CO2, and dissolved oxygen (DO) sensors at Cement Wreck, a central Red Sea offshore reef. Observations from the back reef and fore reef revealed strong diel variability and distinct reef-zone biogeochemical dynamics linked to contrasting benthic compositions. On the back reef, pH and DO were tightly coupled and closely matched a Redfield-based model (𝑅2=0.943), while the fore reef relationship was weaker (𝑅2=0.145). TA observations allowed characterization of the back reef carbonate system, with TA–DIC stoichiometry yielding a slope of 0.26, indicating NCP accounted for approximately 87% of observed carbonate system variability. Compared to global reefs, Cement Wreck exhibits high % NCP contribution. However, the observed 2023 TA–DIC slope closely matches those from Red Sea observations from 1997 to 2013, suggesting that while reefs around the world shift, Red Sea reefs like Cement Wreck represent a persistent metabolic state. Scaled-up autonomous deployments, like the one presented here, will better enable predictions of global reef health in future conditions.

Plain Language Summary

Globally, coral reefs are threatened by rising temperatures, changes in seawater chemistry, pollution, and overfishing. The health of coral reefs is traditionally monitored by reef community composition through visual analysis, however changes in surrounding seawater chemistry can provide insight into reef processes and holistically monitor reef health. Here, we deploy a newly developed total alkalinity (TA) sensor, alongside commercially available pH and oxygen sensors on a coral reef in the Red Sea. Autonomous sensors allow the collection of high-resolution data on reef seawater chemistry, including daily cycles and changes over time, with a cost per data point much lower than traditional discrete samples. Furthermore, the TA sensor allows us to evaluate the relative balance between the reef-building processes and reef-eroding processes occurring, which are important parameters when evaluating a reef’s present and future health. We found that the reef studied here was strongly influenced by organic production, and that this signal closely matched Red Sea observations from the last 25 years. This suggests that some Red Sea reefs may represent a persistent metabolic state rather than a recent shift. The Red Sea lacks high-resolution carbonate-system observations, and this deployment contributes to baseline understanding of Red Sea reef metabolism and carbonate budgets.

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Phenotypic plasticity supports green tide persistence before bioenergetic failure underlies terminal decline

Published 9 November 2026 Science Leave a Comment
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Trans-regional green tides dominated by Ulva prolifera exert significant impacts on coastal ecosystems. While the mechanisms of early-stage proliferation are well documented, the specific physiological and molecular drivers governing the transition from bloom persistence to terminal decline during this trans-regional drift remain unresolved. Using in situ physiological and transcriptomic data collected across a 300-km latitudinal gradient in the Yellow Sea, we found that a dominant molecular type (5S-II) within the sampled 2021 U. prolifera population showed phenotypic plasticity, with its physiological and transcriptional traits varying across environmental conditions. Physiological observations showed declines in photosynthetic performance (Fv/Fm and rETR) and pigment content along the northward drift path, marking a transition from active growth to physiological decline. Transcriptomic and physiological evidence further indicated that the intermediate drifting phase was characterized by a compensatory photoprotective state, potentially involving cyclic electron flow. By contrast, terminal-phase stress was associated with reduced expression of G-protein-signaling-related genes and patterns suggesting that PSII repair could no longer compensate for photodamage as energy metabolism declined. This bioenergetic failure coincided with a shift toward endogenous catabolism and a transition from vegetative growth toward sporulation. Together, these findings provide insight into bloom termination and suggest that ocean warming may accelerate late-stage senescence, whereas acidification may intensify photosynthetic inhibition under multiple stressors, potentially increasing coastal hypoxia risk.

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

Published 6 November 2026 Science Leave a Comment
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The burning of fossil fuels has increased atmospheric CO₂ at an unprecedented rate. The world’s oceans have absorbed much of this carbon dioxide, resulting in a decrease of pH and an increase in the partial pressure of CO2 in seawater in a process referred to as ocean acidification. Ocean acidification (OA) can cause a variety of detrimental effects on the physiology and ecology of larval fishes. Despite a preponderance of negative effects, studies of how OA affects the early life stages of fishes have produced mixed results and have tended to focus on a limited set of responses. In this study, I tested the effects of OA on energy intake, as measured by feeding rate, and energy expenditure, as measured by metabolic rate, then compared these results to growth and development in the California grunion (Leuresthes tenuis). I also created family groupings to analyze genetic variation underlying these responses. My pCO2 treatments ranged from a control with a central value of 550 μatm, followed by 1080 μatm, 1760 μatm, and 2820 μatm. Each experiment lasted for a period of 12 days, and I ran a total of 12 experiments. Within an experiment, measures of metabolic rate, feeding rate, growth, and development were conducted multiple times. Mortality rates were measured continuously. By analyzing the similarities in the responses of related larvae to CO2, I was able to estimate broad sense heritability’s for metabolic rate, feeding rate, growth, and mortality. I found that at 6-days post hatch, larvae developing in high CO2 conditions exerted significantly more energy on routine metabolic rate. This increase in energetic expenditure with CO2 was not matched by an increase in feeding. Paradoxically, however, growth in mass had a positive relationship with CO2. To explore the consequences of these results, I examined development via allometric analysis of organ growth. I found that the relative growth of the eyes and stomachs of larvae were significantly slower when larvae developed under high pCO2 conditions. Furthermore, I found that both growth and metabolic rates showed significant genetic variation in sensitivity to OA, suggesting considerable evolutionary potential in these traits. I also present evidence that maternal effects are highly influential within the first 6 days after hatch. Overall, my results suggest that OA can cause both an energy deficit and abnormalities in the development of California grunion. The developmental abnormalities observed may be a symptom of an allocation of resources that prioritizes growth at the expense of internal organ development. These changes are likely to have long-term effects on recruitment in natural populations. Additionally, our results suggest that there is appreciable standing genetic variation within the population for the phenotypes studied here.

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

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

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

Published 6 November 2026 Science Leave a Comment
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Highlights

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

Abstract

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

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

Published 6 November 2026 Science Leave a Comment
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Highlights

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

Abstract

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

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

Published 6 November 2026 Science Leave a Comment
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Ocean acidification and sulfide intrusion are key environmental stressors affecting seagrass bed ecosystems. Although sulfide stress drives large-scale seagrass mortality, the physiological response of seagrasses under ocean acidification remains unclear. Therefore, this study selected Thalassia hemprichii, a dominant species of seagrass beds, to investigate the effects of ocean acidification (pH 7.7), sulfide stress, and their interaction on its physiological responses and growth. Our results showed that acidification alone relieved photosynthetic carbon limitation of T. hemprichii, significantly increasing net photosynthetic oxygen release and growth rate (p < 0.05). Sulfide stress alone significantly decreased the maximum quantum yield (Fv/Fm) and net photosynthetic rate and increased tissue H2S content (p < 0.05), while the growth rate showed a decreasing trend. Under combined acidification and sulfide stress, acidification promoted sulfide intrusion and significantly increased leaf H2S content (p < 0.05), whereas no significant reduction in growth rate was observed. Compared with sulfide treatment alone, combined acidification and sulfide stress enhanced the electron transport rate and radial oxygen loss (ROL) in T. hemprichii, thereby significantly increasing O2 contents in the sediment (p < 0.05). Meanwhile, the antioxidant defense systems of T. hemprichii were activated. These coordinated responses jointly mitigated sulfide toxicity. Therefore, under ocean acidification, T. hemprichii alleviated sulfide toxicity by coordinating carbon acquisition, rhizosphere oxygen cycling, and antioxidant defense. These findings provide key physiological and ecological evidence for predicting the adaptive capacity of seagrass beds under future climate change and underscore the importance of interactions among multiple stressors for seagrass conservation.

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

Published 5 November 2026 Science Leave a Comment
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Climate change, contaminant exposure, and emerging disease dynamics are increasingly recognized as interconnected stressors affecting marine crustaceans, including lobsters. This review compares three commercially and ecologically important species: Homarus americanus, Homarus gammarus, and Jasus edwardsii. Although these species differ taxonomically and ecologically, environmental stressors rarely act in isolation; climate change and contaminants interact to modify metabolic performance, molting, microbial dynamics and pathogen susceptibility. By synthesizing existing literature, this review identifies shared vulnerabilities and species-specific responses. Evidence suggests differences in thermal tolerance, developmental sensitivity and physiological plasticity, with early life stages consistently representing the most sensitive period across species. The American lobster has the strongest evidence linking warming waters to physiological stress and disease prevalence, particularly in Southern New England, whereas extensive research for European and Southern Rock lobsters remain limited. Across species, warming and ocean acidification often interact with contaminant exposure to alter immune function, molting, and recruitment. Key gaps remain in multi-stressor experiments, disease ecology and early life-stage research, emphasizing the need for integrative multi-stressor and cross-species frameworks to improve predictions of lobster resilience under accelerating environmental change.

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

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

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

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

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

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

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

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

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

Active calcifying fluid pH upregulation facilitates resilience of the coral Tubastraea aurea to ocean acidification

Published 4 November 2026 Science Leave a Comment
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Ocean acidification poses a critical threat to marine calcifiers, yet the physiological mechanisms allowing certain species to thrive in high-CO₂ environments remain poorly understood. Kueishan Island (Taiwan) provides a unique natural laboratory to address this gap. While nearby non-vent reefs support diverse coral communities, the strongly acidified hydrothermal vent fields at Kueishan Island are dominated by the azooxanthellate coral Tubastraea aurea. Here, we tested whether this persistence is driven by regulation of the calcifying microenvironment. Using skeletal boron isotope (δ¹¹B) composition and scanning electron microscopy (SEM), we reconstructed calcifying-fluid pH (pHCF) and assessed skeletal microstructure in specimens from the vent site (HV, pH ~6.6) and a reference site (FU, pH ~8.0). Despite a ~1.4-unit difference in ambient seawater pH (pHSW), the estimated pHCF was indistinguishable between sites (HV 8.45 ± 0.02, FU 8.38 ± 0.01), resulting in a markedly larger ΔpH (pHCF − pHSW) at the vents. While SEM analysis revealed no gross dissolution at the resolution examined, vent colonies were smaller than reference counterparts, suggesting possible growth constraints under extreme conditions (exploratory given limited colony replication). These findings indicate that T. aurea maintains elevated pHCF in exceptionally low-pH seawater, highlighting a physiological capacity that could contribute to skeletal maintenance under future acidified oceans.

Continue reading ‘Active calcifying fluid pH upregulation facilitates resilience of the coral Tubastraea aurea to ocean acidification’

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