Atmospheric carbon dioxide (CO2) levels are escalating at an unprecedented rate, leading to the phenomenon of ocean acidification (OA). Parental exposure to acidification has the potential to enhance offspring resilience through cross-generation plasticity. In this study, we analyzed larval growth and transcriptomic profiles in the Pacific oyster, Crassostrea gigas, a species of significant ecological relevance, under both control and elevated CO2 conditions experienced by their parental generation. Our findings indicate that the oyster populations exposed to OA exhibited a higher incidence of abnormalities during the D-shaped larval stage, followed by accelerated growth at the eyed stage. Through a comparative transcriptomic investigation of eyed larvae (25 d after fertilization), we observed that parental exposure to OA substantially influenced the gene expression in the offspring. Genes associated with lipid catabolism and shell formation were notably upregulated in oysters with parental OA exposure, potentially playing a role in cross-generational conditioning and conferring resilience to OA stressors. These results underscore the profound impact of OA on oyster larval development via cross-generational mechanisms and shed light on the molecular underpinnings of cross-generation plasticity.
Continue reading ‘Parental exposure to ocean acidification impacts the larval development and transcriptome of the Pacific oyster Crassostrea gigas’Posts Tagged 'molecular biology'
Parental exposure to ocean acidification impacts the larval development and transcriptome of the Pacific oyster Crassostrea gigas
Published 2 February 2026 Science ClosedTags: adaptation, biological response, growth, laboratory, molecular biology, mollusks, North Pacific, otherprocess, reproduction
Photoaged microplastics disrupt the response of marine medaka (Oryzias melastigma) to ocean acidification: perspectives from energy metabolism and ammonia production
Published 2 February 2026 Science ClosedTags: biological response, fish, laboratory, molecular biology, multiple factors, North Pacific, physiology, plastics, respiration
Ocean acidification (OA) and microplastics (MPs, <5 mm) are co-occurring stressors that threaten marine ecosystems. Although the marine environment contains multiple pollutants, OA can alter the environmental behavior of MPs, influencing their toxicity and environmental fate. Therefore, investigating the interactive effects of OA and MPs is essential. Fish can activate physiological compensatory mechanisms to adapt to OA; however, it remains unclear how MPs affect these mechanisms. In this study, marine medaka were exposed to acidified seawater (pH 7.70) containing environmentally relevant concentrations of MPs (0.1 mg/L) for 90 days to investigate the disruptive effects of MPs on responses to OA. The results showed that while OA triggered compensatory energy metabolism reprogramming to enhance ammonia production, MPs disrupted this process, reducing the TCA cycle intermediate α-ketoglutarate. This α-ketoglutarate deficiency limited the glutamate supply for ammonia production. Simultaneous inhibition of glutamate dehydrogenase activity further limited glutamate availability. As a result, MPs reduced the level of ammonia production by 25.29%, compromising the ability to neutralize excess H+. Crucially, photoaging exacerbated this toxicity, leading to a 32.04% reduction in ammonia production. This study demonstrates that MPs interfere with fish responses to OA via α-ketoglutarate-mediated metabolic reprogramming, highlighting a vulnerability in marine organisms facing climate change scenarios.
Continue reading ‘Photoaged microplastics disrupt the response of marine medaka (Oryzias melastigma) to ocean acidification: perspectives from energy metabolism and ammonia production’Short-term tolerance to ocean acidification of the sub-antarctic sea-urchin arbacia dufresnii
Published 29 January 2026 Science ClosedTags: Antarctic, biological response, echinoderms, laboratory, molecular biology, morphology, physiology
The accumulation of anthropogenic CO2 in the ocean is impacting the carbonate system chemistry in seawater, particularly in polar regions. Acidified seawater can impair the echinoderms internal regulation of pH due to an increase in hydrogen ions concentration, potentially affecting growth, and calcification, among other physiological activities. The goal of this work was to assess the effects of Ocean Acidification (OA) on Arbacia dufresnii, a sub-Antarctic sea urchin species. Adult specimens were exposed to three pH treatments: 7.4, 7.7, and 8.0 (control), for 21 up to 23 days. We assessed spine regeneration, a proxy of calcification, by cutting spines at the base of the shaft and evaluating the magnesium content, height, and weight of the regenerated part. The coelomic fluid was sampled for pH assessment and magnesium and calcium content analysis. The RNA/DNA ratio, a proxy of metabolic activity, was assessed in the gonads and body walls. The spine regenerated weight was significantly correlated to regenerated height but not to treatments. The coelomic fluid pH (6.77 ± 0.34) did not differ between treatments (pANOVA = 0.15). No significant differences were observed between treatments regarding RNA/DNA ratio in both body wall (pANOVA = 0.65) and gonads (pKruskal-Wallis = 0.34), the spine regenerated height (pANOVA = 0.35) and Mg regenerate content (pANOVA = 0.58). Our results suggest that A. dufresnii owns physiological mechanisms to cope with OA conditions during short-term exposure.
Continue reading ‘Short-term tolerance to ocean acidification of the sub-antarctic sea-urchin arbacia dufresnii’Core transcriptional plasticity pave the way for fish to succeed in a high-CO2 world
Published 26 January 2026 Science ClosedTags: biological response, BRcommunity, field, fish, molecular biology, performance, South Pacific, vents
Ocean acidification (OA) can alter the physiological and behavioural traits of marine fishes, raising concerns about how wild species will adapt to rising pCO2. Using natural volcanic CO2 vents at White Island, New Zealand, as analogues for future OA conditions, we quantified behaviours in situ and sequenced the brain transcriptomes of four highly site-attached fish species from two vents and a nearby control site with ambient pCO2, of which two species exhibit increased population densities at the vent. We found that two species showed changes in habitat preferences, and all four species with significant changes in gene expression related to circadian rhythm, visual perception, and energy metabolism at the vents. Strikingly, three differentially expressed genes, a heat shock protein (HS90A) and two immediate early genes (IEGs: JUN and FOS), were central regulators for transcriptional changes across all species at the vents. Within the circadian entrainment pathway, expression changes in opsins may act as a trigger, while core clock genes and IEGs function as downstream effectors, suggesting that elevated pCO2 may reset the circadian clock in these fishes. Notably, the two species with increased populations at the vents exhibited distinct transcriptional responses in genes involved in calcium signalling, reproduction, intracellular pH regulation and energy metabolism. Together with convergent evolution in a calcium signalling gene and an HS90 facilitator, these molecular features may confer their reproduction advantages and ability to cope with elevated pCO2. Our study provides novel insights into the molecular mechanisms underlying fish responses to OA and highlights key pathways that may support survival and ecological success under a naturally high-CO2 world.
Continue reading ‘Core transcriptional plasticity pave the way for fish to succeed in a high-CO2 world’Prolonged low pH reprograms carbon and nitrogen metabolism and micronutrient use in Symbiodinium kawagutii and reveals indicators for reef water quality management
Published 23 January 2026 Science ClosedTags: biological response, growth, laboratory, molecular biology, photosynthesis, physiology, phytoplankton
Highlights
- Low- pH stress suppresses S. kawagutii growth by ∼50%
- Enhanced NPQ and reduced chlorophyll indicate increased photoprotection
- Lipid pools increase as proteins and carbohydrates are diverted to fatty acids
- Elevated C:N ratios and Fe/Mn loss reveal nutrient limitation under acid stress
- Multi-omics uncover upregulated CA, antioxidant enzymes, and proton pumps
Abstract
Ocean acidification is a pervasive driver of coastal and reef water-quality change. We investigated how chronic low-pH exposure representative of extreme reef scenarios (pH 7.4-7.5) reshapes the physiology and metabolism of the coral symbiont Symbiodinium kawagutii. Integrating growth assays, photophysiology, ultrastructural imaging, biochemical profiling, transcriptomics, and metabolomics, we show that low pH suppresses growth and redirects resources from biosynthesis to stress mitigation. Non-photochemical quenching increased while chlorophyll content declined, indicating photoprotective energy reallocation. Ultrastructural deterioration coincided with losses of protein and carbohydrate pools, whereas fatty-acid stores expanded, evidencing a shift in carbon storage. Elemental and trace-metal measurements revealed higher cellular C:N and significant Fe/Mn depletion, indicating micronutrient constraints under acid stress. Multi-omics analyses identified coordinated upregulation of carbonic anhydrases, vacuolar H+-ATPases, and antioxidant defenses with downregulation of nitrogen and phosphorus assimilation, forming a plastic network that maintains pH and redox homeostasis at the expense of growth. These cellular trade-offs clarify how symbiont plasticity can buffer acidified conditions while altering the quality and quantity of photosynthate available to hosts. By linking mechanistic responses to potential monitoring indicators, this study provides actionable targets to anticipate and manage acidification impacts on reef water quality and to guide restoration strategies that prioritize acid-tolerant symbiont strains and relief of micronutrient stress.
Continue reading ‘Prolonged low pH reprograms carbon and nitrogen metabolism and micronutrient use in Symbiodinium kawagutii and reveals indicators for reef water quality management’Transcriptomic responses of the marine diatom Phaeodactylum tricornutum to high carbon and low nitrogen stress
Published 23 January 2026 Science ClosedTags: adaptation, biological response, laboratory, molecular biology, multiple factors, nutrients, otherprocess, phytoplankton
Diatoms play a pivotal role in global biogeochemical cycling and marine primary productivity, making them ideal model organisms for understanding how phytoplankton respond to environmental fluctuations associated with global climate change. In natural marine systems, diatoms frequently encounter simultaneous variations in carbon and nitrogen availability, yet most previous studies have examined the effects of these factors in isolation. To elucidate the integrated transcriptional mechanisms underlying diatom acclimation to coupled carbon–nitrogen (C—N) imbalance, we employed RNA sequencing (RNA‐Seq) to characterize the global transcriptional response of the model diatom Phaeodactylum tricornutum to high CO2 (~2000 μatm) and low nitrogen (10% of nitrogen concentration in f/2 medium) under parallel culture conditions. The results revealed both shared and distinct transcriptional responses between the two treatments. Key genes involved in carbon metabolism, such as phosphoglycerate mutase (PGAM_7) and dihydrolipoamide succinyltransferase (PHATRDRAFT_40430), were significantly upregulated, indicating enhanced glycolytic and TCA cycle activity. In contrast, the Calvin‐cycle enzyme fructose‐1,6‐bisphosphatase (FBPC4) was downregulated. Genes associated with nitrogen assimilation‐including nitrate reductase (PHATRDRAFT_54983), nitrite reductases (PHATRDRAFT_13154, PHATRDRAFT_8155), and ferredoxin–nitrite reductase (PHATRDRAFT_27757)‐were strongly induced under both conditions. Pathway enrichment analysis further indicated the activation of lactic acid fermentation and nitrogen salvage pathways, suggesting a metabolic shift toward energy conservation and nutrient recycling. Collectively, these findings provide an overview of the transcriptional adjustments that enable P. tricornutum to maintain C—N homeostasis under high CO2 and low nitrogen stress, offering new insights into diatom metabolic plasticity under changing ocean conditions.
Continue reading ‘Transcriptomic responses of the marine diatom Phaeodactylum tricornutum to high carbon and low nitrogen stress’Neurometabolic rewiring in squid (Sepioteuthis lessoniana) optic lobes drives behavioral plasticity and visual integration under environmental acidification
Published 20 January 2026 Science ClosedTags: biological response, laboratory, molecular biology, mollusks, North Pacific, performance, physiology
Ocean acidification’s impacts on marine animal behavior have substantial implications for ecosystem stability. Understanding how key predators respond to acidification is crucial for predicting future ocean food web dynamics, yet the underlying neural mechanisms remain poorly understood. Here, we show that prolonged exposure to projected year 2100 acidification conditions substantially impairs predatory behavior in bigfin reef squid (Sepioteuthis lessoniana), a key invertebrate predator. Chronic acidification exposure reduces expression of acetylcholine receptors in optic lobes and alters systemic HCO₃⁻ levels and metabolic rates. Using custom electroretinogram recordings, we find that while basic visual processing remains intact, behavioral impairments likely stem from changes in downstream neural integration pathways. Transcriptomic expression analysis reveals broad reductions in energy metabolism and synaptic signaling under acute exposure, while chronic exposure induces compensatory upregulation of cellular maintenance pathways. Our findings demonstrate that while squids maintain visual capabilities through adaptive mechanisms, the energy-intensive processes of neural integration and behavioral execution are compromised. These results highlight the complex physiological trade-offs marine predators face under ocean acidification, with implications for understanding future shifts in marine ecosystem structure and function.
Continue reading ‘Neurometabolic rewiring in squid (Sepioteuthis lessoniana) optic lobes drives behavioral plasticity and visual integration under environmental acidification’Integrated biochemical profiling, comparative transcriptome and weighted gene co-expression network analysis to explore the response mechanism of global warming and ocean acidification to the stress of Sepia esculenta larvae
Published 16 January 2026 Science ClosedTags: biological response, laboratory, molecular biology, mollusks, multiple factors, North Pacific, physiology, reproduction, temperature
Highlights
- Multi-angle analysis of Sepia esculenta under global warming and ocean acidification.
- Stress enhanced the immune defense and antioxidant defense of S.esculenta.
- The hub genes closely related to stress resistance were identified and screened out.
- Provided a theoretical basis for the breeding of fine varieties and pond culture.
Abstract
The Sepia esculenta has high economic value and nutritional value, and accounts for a high proportion of the catch of cephalopods in China ‘s coastal waters. Global warming and ocean acidification, as major environmental problems currently facing the world, have a serious negative influence on the survival and breeding of S. esculenta. Therefore, in the research, transcriptome sequencing and biochemical quantitative analysis were performed on the larvae of S. esculenta after high temperature, low pH and combined stress at different time points, and the differential expressed genes (DEGs) and response mechanisms were identified. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that these DEGs were mainly involved in a large number of immune-related biological processes and signaling pathways, including Immune response、Phagocytosis、Regulation of DNA-templated transcription and Positive regulation of DNA-templated transcription. Then, we further explored the functional relationship between these DEGs by constructing weighted gene co-expression network and protein-protein interaction networks. We identified ten hub genes including HSP90AA1, ALDH1L1, VPS13A, MAPK8IP1 and KDM6A. These hub genes may play an important role in the face of high temperature, low pH and their combined stress at different times. Our findings not only elucidate the molecular response mechanisms of S. esculenta to environmental stress and delineate the key regulatory pathways underlying its adaptation, but also provide a theoretical foundation for advancing pond cultivation.
Continue reading ‘Integrated biochemical profiling, comparative transcriptome and weighted gene co-expression network analysis to explore the response mechanism of global warming and ocean acidification to the stress of Sepia esculenta larvae’Co–occurring aquatic acidification and hypoxia promote methane emissions from estuarine ecosystems
Published 14 January 2026 Science ClosedTags: biological response, laboratory, molecular biology, North Pacific, physiology, sediment
Highlights
- Acidification, hypoxia, and the combined effect enhanced CH4 emission from estuary.
- Acidification and hypoxia exerted contrasting regulatory mechanisms on CH4 emission.
- Acidification raised CH4 release by suppressing methanotrophs more than methanogens.
- Hypoxia preferentially enhanced methanogenic activity over CH4 oxidation.
- Oxygen availability dominated CH4 dynamics under acidification–hypoxia interactions.
Abstract
Estuaries worldwide are experiencing intensifying acidification and hypoxia, driven synergistically by anthropogenic activities and global climate change. Nevertheless, their combined impact on the emissions of the potent greenhouse gas methane (CH4) and its underlying regulatory mechanisms remains poorly understood, undermining our ability to project climate feedbacks. Here, we integrated 13C stable isotope tracing, DNA/mRNA–based qPCR, and amplicon/metagenomic sequencing to unravel how acidification–hypoxia interactions regulate the complex balance between CH4 production and consumption in estuarine sediments. Results showed that aquatic acidification and hypoxia combined to significantly increase CH4 emissions from estuarine sediments (P < 0.05), in a non-additive (antagonistic) manner where oxygen availability was the dominant factor governing this response. Notably, acidification increased CH4 emissions by suppressing methanotrophy more strongly than methanogenesis, whereas hypoxia preferentially stimulated methanogenic activity over CH4 oxidation. These response patterns were further demonstrated by metagenomic sequencing and mRNA-based quantitative PCR analyses, which revealed coordinated shifts in both the relative abundance and transcriptional activity of key functional genes. These findings uncover a previously overlooked mechanism whereby the worldwide co-occurrence of acidification and hypoxia in estuarine ecosystems jointly promote CH4 emissions, providing a scientific basis for improving predictive models of the global CH4 cycle and its climate feedbacks under combined anthropogenic and climatic stressors.
Continue reading ‘Co–occurring aquatic acidification and hypoxia promote methane emissions from estuarine ecosystems’Assessing impacts of extreme climate and weather events on endangered pearl oysters Pinctada maxima
Published 13 January 2026 Science ClosedTags: biological response, laboratory, molecular biology, mollusks, multiple factors, North Pacific, physiology, reproduction, temperature
Extreme climate and weather events in the ocean, especially ocean acidification (OA) and marine heatwaves (MHWs), have strikingly accelerated in the past decades, yet their compound consequences remain poorly understood. The pearl oyster (Pinctada maxima), an endangered keystone species in Indo-Pacific reef ecosystems, is highly vulnerable to such events. Here, we assessed how OA-stressed P. maxima juveniles responded to MHWs (+3 °C), based on a total of 100 individuals exposed to two weeks. Oysters reared at pH 7.7 significantly increased activities of energy-metabolizing enzymes (T-ATP and NKA) in response to MHWs, whereas both enzymes significantly decreased, albeit CMA increased, at pH 7.4. MHWs significantly depressed antioxidant enzyme activities, such as SOD at both pH levels, resulting in elevated MDA levels indicative of lipid peroxidation. Contrasting responses of immune enzymes (ACP and AKP) to MHWs were seen in oysters grown under moderately and severely acidified conditions. MHWs, also, significantly depressed expression levels of key genes related to cellular metabolism (ATP1A, ATP1B, ND5, ATPeV1F and ATPeF1A) and those associated with antioxidant defence (SOD, SOD1, SOD2, Hsp70, Hsp90 and CAT), in particular when stressed at pH 7.4. Taken together, our findings suggest that intensifying MHWs can constrain the ability of P. maxima to cope with OA and likely accelerate further population decline in this era of unprecedented climate change.
Continue reading ‘Assessing impacts of extreme climate and weather events on endangered pearl oysters Pinctada maxima’Physiological and transcriptomic responses of a harmful algal bloom-causing dinoflagellate Karenia mikimotoi to multiple environmental factors
Published 12 January 2026 Science ClosedTags: biological response, growth, laboratory, molecular biology, multiple factors, North Pacific, nutrients, photosynthesis, physiology, phytoplankton, temperature
Highlights
- Elevated temperature was the primary factor significantly reducing K. mikimotoi growth and photosynthesis.
- Increased pCO₂ and high N: P ratios partially mitigated thermal stress induced by elevated temperature.
- K. mikimotoi consistently up-regulated energy and lipid metabolism to cope with environmental stressors irrespective of treatment.
- K. mikimotoi may persist and even thrive under multiple stressors, subsequently influencing productivity and biogeochemical cycles.
Abstract
Dinoflagellates play a crucial role in marine food webs and biogeochemical cycles, yet they are increasingly affected by global environmental changes. While there is limited understanding of their response to individual stressors projected under future oceanic conditions, their response to multiple concurrent environmental stressors remains inadequately explored. This study investigated the singular and interactive effects of elevated temperature (26 °C vs. 22 °C), increased pCO2 (1000 μatm vs. 400 μatm), and a high nitrogen-to-phosphorus ratio (N:P = 180:1 vs. 40:1) on the harmful algal bloom-forming dinoflagellate Karenia mikimotoi over a 40-day exposure period. Among these factors, elevated temperature exerted the most pronounced influence, markedly reducing the cell growth rate and photosynthesis while simultaneously increasing the particulate organic matter content and antioxidant level. Transcriptomic analyses indicated that elevated temperature enhanced the expression of genes associated with oxidative stress, suggesting a potential defense mechanism against thermal stress. Notably, increased pCO2 and a high N:P ratio appeared to mitigate thermal stress to some extent. Irrespective of the treatment, K. mikimotoi demonstrated a consistent response strategy characterized by the synergistic upregulation of energy metabolism and lipid biosynthesis pathways, coordinated by the modulation of both upstream and downstream genes in the tricarboxylic acid cycle. This metabolic reprogramming likely facilitates a more efficient allocation of energy, thereby enhancing the resilience of K. mikimotoi to environmental stress. This study underscores the interactive effects of multiple stressors on marine dinoflagellates, highlighting that elevated temperature is the most critical factor affecting dinoflagellates in future oceanic environments.
Continue reading ‘Physiological and transcriptomic responses of a harmful algal bloom-causing dinoflagellate Karenia mikimotoi to multiple environmental factors’Acute CO2 toxicity and the effects of seawater acidification on health status, histopathology, immunity and disease resistance in Asian Seabass (Lates calcarifer)
Published 12 January 2026 Science ClosedTags: biological response, fish, laboratory, molecular biology, mortality, physiology, reproduction
Carbon dioxide capture and storage (CCS) is a technology that can be used to reduce carbon dioxide (CO2) emissions generated by both natural and anthropogenic industrial processes, particularly petroleum production. To mimic and investigate the effects of CO2 leakage that may result from CCS, the acute toxicity of seawater acidification induced by continuous CO2 injection was studied in Asian seabass (Lates calcarifer) fry under static bioassay conditions. Fry (0.828 ± 0.22 g) were exposed to seawater with different pH levels (5.5, 6.0, 6.5, 7.5, and 8.3). Rapid and 100% mortality within 15 min was observed in the pH 5.5 exposure group, while mortality rates ranging from 10.00–41.67% were recorded at 6–96 h in the pH 6.0 exposure group; no mortality was noted in the other pH exposure groups. According to these mortality data, the median lethal concentration at 96 h (96 h LC50) was determined to be a pH of 5.884. Interestingly, after exposure to seawater with pH levels of 5.5 and 6.0, histopathological alterations in the skin, gills, trunk kidney and liver were evident. Additionally, some water quality parameters, especially dissolved oxygen (DO) levels, alkalinity, ammonia levels, and nitrite levels, vary depending on the pH. To further investigate the effects of seawater with pH levels of 8.3 and 5.884 (96 h LC50) and 6.5 (10% safety level) on health status, immune responses and disease susceptibility, fingerling fish (21.25 ± 3.89 g) were studied. Unexpectedly, fish exposed to seawater with a pH of 5.884 rapidly lost muscle control and gradually died, reaching 100% mortality within 24 h, and all response analyses were aborted. Interestingly, with the exception of hematocrit and some immune parameters, various serum innate immune indices, blood biochemistry parameters and immune-related gene expression patterns were similar in fish exposed to seawater with pH levels of 8.3 and 6.5. Additionally, fish were challenged with 0 (control), 1 × 107 and 1 × 109 CFU/mL Vibrio vulnificus, and fish in seawater with a pH level of 6.5 showed a higher sensitivity to 1 × 109 CFU/mL Vibrio vulnificus than fish in seawater with a pH level of 8.3, with mortality rates of 71.24% and 25.44%, respectively (p < 0.05). These findings enhance the understanding of the toxicity effects of seawater acidification caused by CO2, which will be useful for further assessing the site-specific effects of CCS projects.
Continue reading ‘Acute CO2 toxicity and the effects of seawater acidification on health status, histopathology, immunity and disease resistance in Asian Seabass (Lates calcarifer)’Short-term focus: phased response of Zostera marina seedlings to the combined stress of marine heatwave and ocean acidification
Published 25 December 2025 Science ClosedTags: biological response, laboratory, molecular biology, morphology, multiple factors, North Pacific, phanerogams, physiology, temperature
Marine heat wave (MHW) and ocean acidification (OA) caused by global climate change occur frequently and intensify, which cause damage to the stability of seagrass bed. However, the understanding of the phased-impacts of sudden temperature and acidification changes on seagrass is limited. The study conducted phenomic, transcriptomic and metabolomic analyses to investigate the short-term response mechanisms of Zostera marina seedlings to sudden temperature and acidification incerease. The results showed that Z. marina seedlings activated an integrated metabolic response involving fatty acid metabolism, carbohydrate metabolism and amino acid metabolism to modulate cell membrane properties, enhance thermotolerance and maintain developmental stability. What is noteworthy is that the continuous high expression of the ABC transporters play a crucial role in resisting stress. The study is helpful to clarify the short-term phased response of Z. marina seedlings to the combination of MHW and OA, and have significant importance for the protection and restoration of seagrass beds.
Continue reading ‘Short-term focus: phased response of Zostera marina seedlings to the combined stress of marine heatwave and ocean acidification’Multifactorial neural disruption in the brain of the Senegalese Sole (Solea senegalensis) under ocean acidification
Published 9 December 2025 Science ClosedTags: biological response, fish, laboratory, molecular biology, North Atlantic, physiology
Global ocean acidification, driven by rising atmospheric CO2, is threatening marine ecosystems and biodiversity, with increasing evidence of its disruptive effects on fish neurobiology and behaviour, yet the mechanisms underpinning its impact on fish neurobiology remain unresolved. Here, we reveal how chronic exposure to future-predicted CO2 levels disrupts brain function in the marine teleost Solea senegalensis, a species with functionally distinct olfactory organs. Using an integrative approach combining electrophysiology, immunohistochemistry, and transcriptomics, we demonstrate that elevated CO2 conditions induce a complex multifaceted disruption in brain physiology. Notably, our findings conflict with the widely held GABAA receptor reversal hypothesis; we observed increased Cl- and CO2 in cerebrospinal fluid and suppressed neural excitability, rather than the predicted loss of Cl- and heightened excitatory signalling. Immunohistochemistry further revealed reduced expression of glial fibrillary acidic protein across multiple brain regions, suggesting glial impairment. Furthermore, transcriptomic profiling of the olfactory bulb uncovered immune modulation, downregulation of neural excitability genes, and upregulation of neuroplasticity, ciliary, and anti-inflammatory pathways, hallmarks of cellular stress adaptation. Notably, genes involved in circadian regulation and thyroid signalling were also dysregulated, pointing to broader neuroendocrine disruption. These findings challenge current relatively simple models of ocean acidification impact and unveil a complex cascade of central and peripheral alterations, including enhanced GABAergic inhibition, immune shifts, glial dysfunction, and disrupted timekeeping mechanisms, likely contributing to the behavioural impairments observed under high CO₂. Challenging current models, our work highlights the need for integrative neurophysiological frameworks to predict marine fish resilience and vulnerability in a changing ocean.
Continue reading ‘Multifactorial neural disruption in the brain of the Senegalese Sole (Solea senegalensis) under ocean acidification’Stressed overwintering bottleneck hypothesis: ocean warming and acidification synergistically disrupt Arctic zooplankton overwintering
Published 1 December 2025 Science ClosedTags: Arctic, biological response, crustaceans, laboratory, molecular biology, mortality, multiple factors, physiology, reproduction, respiration, temperature, zooplankton
Ocean warming (OW), driven by the influx of warm Atlantic water masses, and acidification (OA) are threatening Arctic marine ecosystems. However, their potential synergistic effects are poorly understood, especially during the Polar Night when marine species are particularly vulnerable to stressors. Here, we tested our novel Stressed Overwintering Bottleneck Hypothesis (SOBH): warming will disrupt the overwintering of the keystone pan-Arctic copepod Calanus glacialis, a pivotal secondary producer, by impairing fitness-related traits underpinning survival and reproduction. We exposed C. glacialis to current and projected future OW levels (0 °C and 4 °C) and OA levels (pH 8.0 and 7.4-7.3) for 53 days during the mid-Arctic Polar Night. We assessed survival, development, and physiological and molecular mechanisms (oxygen consumption, lipid depletion, the expression of nine targeted genes related to oxidative stress and damage repair, and DNA damage). OW alone did not affect C. glacialis mortality; however, OA increased copepod survival at 0 °C. Notably, their combined effects (OWA) synergistically doubled mortality, as predicted by SOBH. Warming also accelerated moulting from copepodite stage V to adulthood in December, and increased respiration, exhausted lipid reserves entirely by early March, approximately one to four months before the spring algal bloom, further supporting SOBH. DNA damage and gene expression patterns indicated low investment in maintenance and damage repair. Collectively, these findings reveal hidden mechanisms by which OW and OA synergistically threaten overwintering Calanus copepods by drastically increasing mortality, accelerating moulting, raising metabolic rates, and causing early lipid depletion. These effects generate cross-seasonal phenological mismatches among overwintering survival, energy reserves, reproduction, and primary production. Such stressed overwintering bottlenecks in foundational secondary producers like Calanus copepods provide novel explanations for how OW and OA can constrict Arctic marine food webs. At a broader perspective, SOBH highlights how multiple stressors induced overwintering disruption could reshape pan-Arctic and global biodiversity.
Continue reading ‘Stressed overwintering bottleneck hypothesis: ocean warming and acidification synergistically disrupt Arctic zooplankton overwintering’Physiological and transcriptomic responses of Sargassum hemiphyllum var. chinense to ocean acidification and nitrogen enrichment
Published 21 November 2025 Science ClosedTags: algae, biological response, laboratory, molecular biology, multiple factors, North Pacific, nutrients, physiology
Sargassum hemiphyllum var. chinense is a major brown macroalga and has important ecological and economic significance. Ocean acidification and nitrogen enrichment are serious threats to marine ecosystems primarily by altering the physiology of organisms. However, the response of S. hemiphyllum var. chinense to the combined effects of ocean acidification and elevated nitrogen levels remains unclear. This study conducted a 7-day dual-factor experiment to investigate the physiological and transcriptional responses of S. hemiphyllum var. chinense under two CO2 levels (400 μatm and 1000 μatm) and two NO3⁻ levels (50 μmol/L and 300 μmol/L). The results showed that high CO2 and NO3− concentrations promoted the synthesis of photosynthetic pigments including qN and NPQ. Physiological results showed that high CO2 and the combined high NO3− and CO2 treatments enhanced growth rate and NO3− uptake rate, but NR activity was significantly decreased. Transcriptome analysis identified differentially expressed genes involved in oxidative phosphorylation, carbon metabolism, the TCA cycle, and nitrogen metabolic pathways. Notably, genes related to oxidative phosphorylation and TCA cycle were significantly up-regulated under high NO3− and dual-factor treatments, suggesting that carbohydrate metabolism and energy metabolism of S. hemiphyllum var. chinense were significantly enhanced. The qRT-PCR analysis revealed that the expression levels of key genes involved in carbon fixation and nitrogen metabolism, including PFK, PRK, GAPDH, Rubisco, NR, and MDH, were significantly downregulated. These findings elucidate the molecular mechanisms by which S. hemiphyllum var. chinense adapts to ocean acidification and nitrogen enrichment, offering valuable insights for understanding its capacity to withstand changing marine environments.
Continue reading ‘Physiological and transcriptomic responses of Sargassum hemiphyllum var. chinense to ocean acidification and nitrogen enrichment’Impact of ocean acidification on the intestinal microflora of Sinonovacula constricta
Published 20 November 2025 Science ClosedTags: biological response, BRcommunity, community composition, laboratory, molecular biology, mollusks, North Pacific, otherprocess, prokaryotes
The intestinal microflora, which is vital for nutrient absorption and immune regulation, can experience dysbiosis under environmental stress, potentially enhancing host susceptibility to pathogenic invasion. The impact of ocean acidification on bivalves is substantial, but its effects on their intestinal microflora remain poorly understood. To explore the impact of ocean acidification on the intestinal microflora of Sinonovacula constricta, this study used high-throughput 16S rRNA sequencing technology to investigate the variations in the intestinal microflora communities of S. constricta during ocean acidification across different time points. After exposure to ocean acidification, changes in the composition of the intestinal microflora of S. constricta were observed, with no significant difference in α-diversity between the acidified and control groups. The abundance of Proteobacteria in the acidification group increased, whereas that of Cyanobacteria decreased. The abundance of Firmicutes initially decreased and then increased. At the genus level, the relative abundance of Pseudomonas was lower than that in the control group, whereas the relative abundance of Photobacterium, Acinetobacter, and Enterobacter gradually increased. LEfSe analysis identified Serpens as the discriminative biomarker at 7 days of acidification, Enterobacteriales, Rhodobacteraceae, and Martvita at 14 days of acidification, and Serpens, Acidibacteria, and Aeromonadaceae at 35 days of acidification. Functional prediction analysis indicated significant stimulation in various metabolic pathways at different time points following acidification stress. Specifically, pathways involved in biosynthesis were significantly stimulated at 14 days of acidification, while those related to sucrose degradation were disrupted at 35 days. The results further indicated that ocean acidification stress can influence the intestinal microflora of S. constricta, but no severe dysbiosis or digestive system impairment was observed at the microbial level. This study provides new insights into the effects of ocean acidification on the intestinal microflora of marine bivalves.
Continue reading ‘Impact of ocean acidification on the intestinal microflora of Sinonovacula constricta’Integrative analysis of coral plasticity and adaptations reveals key proteins driving resilience to changes in ocean carbonate chemistry
Published 14 November 2025 Science ClosedTags: adaptation, biological response, calcification, corals, laboratory, molecular biology, otherprocess, physiology
Understanding how corals adapt to changes in seawater carbonate chemistry is crucial for developing effective coral conservation strategies. Research to date has mostly focused on short-term experiments, overlooking long-term evolutionary effects. Here, we investigated the link between short-term stress responses and long-term genetic adaptations in the coral species Porites pukoensis through experiments under varying CO2 and alkalinity conditions. Our results showed that alkalinity enrichment significantly increased coral calcification rates by 35%-45% compared to high CO2 treatment, highlighting the potential of alkalinity enrichment to mitigate acidification impacts. Corals modulated relative expression levels of basic and acidic proteins in response to changes in seawater carbonate chemistry in the stress experiments. Genomic data revealed that this mechanism has been evolutionarily fixed in various organisms adapting to seawater carbonate chemistry. Additionally, both experimental and genomic results showed that extracellular matrix proteins, like collagen with von Willebrand factor type A domain, were modified in response to distinct carbonate environments. Molecular dynamics simulations and in-vitro experiments demonstrated that the structural stability of these proteins contributes to coral resilience under acidified conditions. This study established an integrated framework combining stress experiments, multi-omics analyses, molecular simulations, and in-vitro validation to identify key proteins involved in coral adaptation to acidification.
Continue reading ‘Integrative analysis of coral plasticity and adaptations reveals key proteins driving resilience to changes in ocean carbonate chemistry’Mothers know best: maternal signaling boosts larval resilience under ocean acidification conditions
Published 12 November 2025 Science ClosedTags: adaptation, biological response, fisheries, molecular biology, mollusks, morphology, mortality, otherprocess, physiology, reproduction
Highlights
- Environmental priming effectively rescued larval phenotype under OA conditions.
- Egg ‘omics were investigated to elucidate mechanism of priming across generations.
- Clam egg lipidomes were largely unperturbed by maternal low-pH exposure.
- Differentially expressed genes were identified in eggs of low-pH primed clams.
Abstract
Bivalve aquaculture is a growing sector worldwide, producing sustainable animal protein to meet growing demand from consumers. Yet, the industry remains vulnerable to environmental changes that can impact their product across life stages, especially at the larval stage. Parental priming, or the exposure of broodstock to adverse environmental conditions as they undergo gametogenesis, holds promise as a method to increase resilience in bivalve offspring. We exposed Manila clam (Ruditapes philippinarum) broodstock to low pH conditions (pH 7.4 for 78 days during gametogenesis). Larvae were produced from primed (low pH) and unprimed (ambient pH) broodstock and exposed to ambient or low pH conditions in a full factorial design. Larval phenotype in response to low pH was partially rescued by broodstock priming: larvae from low pH-exposed broodstock had better survival and growth than larvae from broodstock held under ambient conditions. Clam egg lipidomic and transcriptomic analyses were performed to determine the physiological differences associated with broodstock environmental conditions. Egg lipid abundance profiles were not significantly different between parental treatments. The egg transcriptome revealed 48 differentially expressed transcripts associated with parental environmental conditions. These genes are involved in important processes for early larval physiology, including metabolism, cell cycle, and transcriptional regulation. Broodstock clams were minimally impacted by their exposure to low pH for 78 days, however we show here that subtle maternal signals may contribute to the vastly improved larval performance observed under low pH conditions.
Continue reading ‘Mothers know best: maternal signaling boosts larval resilience under ocean acidification conditions’Transcriptomic analysis of the hepatopancreas response to low-pH stress in kuruma shrimp (Marsupenaeus japonicus)
Published 6 November 2025 Science ClosedTags: biological response, crustaceans, fisheries, laboratory, molecular biology, North Pacific, physiology
Highlights
- Low-pH stress disrupted oxidative balance in M. japonicus, suppressing SOD and CAT activities while increasing MDA levels.
- Low-pH stress triggered 2705 DEGs in hepatopancreas linked to immunity, oxidative stress, and energy metabolism.
- CTSD, GLB1, and LGI4 are implicated in long-term immune adaptation to low pH.
- Key pathways—lysosome, Toll-like receptor, AMPK, and PPAR signaling—were activated under low pH stress.
- Hub genes such as NADH-GOGAT and MDHM were identified as central regulators of antioxidant defense and energy metabolism.
Abstract
Ocean acidification has emerged as a globally recognized environmental issue, posing a serious threat to marine ecosystems. To elucidate the adaptive mechanisms of Marsupenaeus japonicus under acidified conditions, both biochemical and transcriptomic analyses were performed following low-pH exposure. Biochemical assays revealed that low pH stress significantly SOD and CAT activities while markedly elevating MDA levels, indicating oxidative damage. T-AOC exhibited a transient rise followed by a sharp decline at later stages, suggesting initial activation and subsequent exhaustion of antioxidant defense. Transcriptomic profiling identified 2705 DEGs that were primarily enriched in pathways related to immune regulation, redox balance, apoptosis, and energy metabolism, including the lysosome, Toll-like receptor, and PPAR signaling pathways. Protein interaction analysis identified 9 hub genes, including NADH-GOGAT and MDHM, which may play key roles in antioxidant defense and metabolic regulation. The integration of enzyme activity and transcriptomic data indicates that acid stress initially induces oxidative imbalance, followed by compensatory activation of antioxidant and immune systems to restore cellular homeostasis. These findings provide comprehensive insights into the oxidative stress adaptation of M. japonicus and offer a genetic and physiological foundation for breeding acid-tolerant shrimp strains.
Continue reading ‘Transcriptomic analysis of the hepatopancreas response to low-pH stress in kuruma shrimp (Marsupenaeus japonicus)’
