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’Posts Tagged 'laboratory'
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
Warming coupled with elevated pCO2 modulates microplastic inhibition in a commercial red alga Pyropia haitanensis
Published 5 December 2025 Science ClosedTags: algae, biological response, growth, laboratory, multiple factors, North Pacific, photosynthesis, physiology, plastics, temperature
Highlights
- Microplastics exert concentration-dependent negative effects on Pyropia haitanensis.
- Warming (24 °C) exacerbated microplastic-induced growth inhibition at ambient CO₂ level.
- High CO₂ inhibited growth at 20 °C but enhanced it at 24 °C under high microplastic stress.
Abstract
Ocean acidification, warming, and microplastics are pervasive stressors in coastal ocean, yet their combined effects on economically important seaweed Pyropia haitanensis remain unclear. To investigate how elevated pCO2, warming, and microplastics interact to affect physiology of P. haitanensis, we cultured thalli at ambient (418 μatm, AC) and elevated (1000 μatm, HC) CO2 levels with two temperatures (20 and 24 °C), and a gradient of microplastics (0.025, 2.5, 25, 50, 100 mg L−1) in a controlled indoor experiment. Our results indicate that microplastics imposed a strong, concentration-dependent stress on P. haitanensis, consistently reducing relative growth rate (RGR), Fv/Fm, photosynthetic pigments (chlorophyll a, carotenoids, and phycobiliproteins), and cellular reserves (soluble protein and carbohydrates), with the strongest inhibition observed at concentration of 100 mg L−1. However, while the increased temperature (24 °C) promoted the content of pigments and soluble protein of the thalli, it decreased the content of soluble carbohydrate among the microplastic concentrations regardless of pCO2 levels. It is noteworthy that under ambient pCO2 level, elevated temperature exacerbated the growth inhibition caused by microplastics, resulting in the highest inhibition rate of 57 % occurring at 100 mg L−1. In contrast, this temperature-aggravated microplastic toxicity was mitigated by high pCO2 levels, with the inhibition rate of 32 % at the highest microplastic concentration. These findings reveal that while elevated pCO2 and warming can modulate microplastic stress via physiological reallocation, persistent declines in photochemical efficiency and light-harvesting pigments may constrain yield and nutritional quality of P. haitanensis where microplastics are high in coastal aquaculture area.
Continue reading ‘Warming coupled with elevated pCO2 modulates microplastic inhibition in a commercial red alga Pyropia haitanensis’Ocean acidification alters phytoplankton diversity and community structure in the coastal water of the East China Sea
Published 5 December 2025 Science ClosedTags: biogeochemistry, biological response, community composition, laboratory, mesocosms, North Pacific, otherprocess, phytoplankton, primary production, respiration
Anthropogenic CO2 emissions and their continuous dissolution into seawater lead to seawater pCO2 rise and ocean acidification (OA). Phytoplankton groups are known to be differentially affected by carbonate chemistry changes associated with OA in different regions of contrasting physical and chemical features. To explore responses of phytoplankton to OA in the Chinese coastal waters, we conducted a mesocosm experiment in a eutrophic bay of the southern East China Sea under ambient (410 μatm, AC) and elevated (1000 μatm, HC) pCO2 levels. The HC stimulated phytoplankton growth and primary production during the initial nutrient-replete stage, while the community diversity and evenness were reduced during this stage due to the rapid nutrient consumption and diatom blooms, and the subsequent shift from diatoms to hetero-dinoflagellates led to a decline in primary production during the mid and later phases under nutrient depletion. Such suppression of diatom-to-dinoflagellate succession occurred with enhanced remineralization of organic matter under the HC conditions, with smaller phytoplankton becoming dominant for the sustained primary production. Our findings indicate that, the impacts of OA on phytoplankton diversity in the coastal water of the southern East China Sea depend on availability of nutrients, with primary productivity and biodiversity of phytoplankton reduced in the eutrophicated coastal water.
Continue reading ‘Ocean acidification alters phytoplankton diversity and community structure in the coastal water of the East China Sea’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’Resistance of the cold-water coral Dendrophyllia cornigera to single and combined global change stressors
Published 28 November 2025 Science ClosedTags: biological response, corals, growth, laboratory, morphology, mortality, multiple factors, North Atlantic, oxygen, respiration, temperature
Current knowledge of the consequences on global change in deep marine ecosystems is still limited, especially since environmental pressures do not act separately, and their potential interactions are mostly unknown. Cold-water corals (CWC) play a significant role in the deep sea, being ecosystem engineers supporting high biodiversity. However, global change may impact CWCs, compromising their integrity and survival. In this study, a nine-month aquaria experiment was conducted on the CWC Dendrophyllia cornigera from the NW Iberian Shelf (NE Atlantic Ocean). The aim was to assess the individual and combined effects of elevated temperature (12 vs. 15 °C), low pH (~ 7.99 vs. 7.69 pHT) and low oxygen (~ 6.4 vs. 4.7 mL L−1), based on the IPCC RCP 8.5 scenario. During the experiment, coral survival, skeletal growth, tissue cover and respiration were monitored as response variables. No significant effects were found on any of the response variables for either individual or combined stressors, pointing to the resistance of D. cornigera to different global change scenarios. Such a physiological resistance may support D. cornigera persistence under future conditions where other CWCs with narrower tolerance ranges may face greater limitations. However, further research is needed to assess potential trade-offs to cope with environmental change, which might impact the long-term survival capacity of this species.
Continue reading ‘Resistance of the cold-water coral Dendrophyllia cornigera to single and combined global change stressors’Acidification-mediated perturbations of developmental pathways and life-stage transitions in Artemia salina
Published 27 November 2025 Science ClosedTags: biological response, crustaceans, fisheries, laboratory, mortality, reproduction
Projected increases in atmospheric carbon dioxide are anticipated to induce a 0.3–0.5 unit decline in oceanic pH by the year 2100, posing a significant threat to marine ecosystems. This study investigated the sub lethal effects of simulated ocean acidification on the ontogenetic success of Artemia salina, a key trophic link in aquaculture systems. A controlled, in vitro experiment employing a Completely Randomized Design (CRD) was conducted, maintaining constant temperature, salinity, and dissolved oxygen. Embryonic development and larval survival were assessed across a gradient of pH levels, representing projected future ocean acidification scenarios. Preliminary data indicate a negative correlation between decreasing pH and both hatching success and larval survivorship. Further investigations are warranted to elucidate the long-term ecological consequences of ocean acidification on Artemia salina populations and their role in aquaculture.
Continue reading ‘Acidification-mediated perturbations of developmental pathways and life-stage transitions in Artemia salina’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’Impact of seawater acidification on the growth, nutritional composition, sensory profile, and antioxidant activity of Caulerpa racemosa in laboratory culture
Published 20 November 2025 Science ClosedTags: algae, biological response, growth, laboratory, morphology, physiology, South Pacific
Fluctuations in coastal water pH, driven by ocean acidification, can strongly influence photosynthetic marine species, including seaweeds. This study investigated the effects of seawater acidification on the growth, nutritional composition, sensory profile, and antioxidant activity of the green alga Caulerpa racemosa. Cultured under varying pH levels (8.25, 8.00, 7.75, and 7.50) adjusted using HCl, C. racemosa exhibited significant morphological and biochemical changes. Lower pH conditions caused bleaching and textural brittleness, with pH levels between 7.50 and 7.75 showing the most pronounced impacts. Conversely, pH 8.25 supported optimal growth, with superior morphometric performance (absolute growth of 138.30 ± 3.70 g; specific growth rate of 3.08 ± 0.04% day⁻1). Acidification decreased chlorophyll content but enhanced carotenoids, indicating reduced photosynthetic efficiency. Protein content declined under acidic conditions, while lipid and carbohydrate levels increased. Notably, antioxidant activity peaked under pH 7.50 (15.09 ± 0.04%; IC50 275.04 ± 0.85 ppm), suggesting an adaptive physiological response. Sensory evaluation revealed that C. racemosa cultured at pH 8.25 achieved the highest overall acceptability, supporting its potential for culinary and nutritional use. These findings highlight the capacity of C. racemosa to acclimate to acidified environments, providing insights into its adaptive mechanisms and applications in food, pharmaceuticals, and sustainable aquaculture.
Continue reading ‘Impact of seawater acidification on the growth, nutritional composition, sensory profile, and antioxidant activity of Caulerpa racemosa in laboratory culture’The multiple responses of Mytilus galloprovincialis in the multi-stressor scenario: impacts of low pH, low dissolved oxygen, and microplastics
Published 18 November 2025 Science ClosedTags: biological response, laboratory, Mediterranean, mollusks, multiple factors, oxygen, physiology, plastics, respiration
Highlights
- Low pH, low dissolved oxygen (DO), and microplastics (MPs) did not notably affect organismal parameters or ETS activity.
- Stressors significantly affected hemocytes, genotoxicity, and gill metabolites individually and interactively.
- Hemolymph phagocytic activity, granulocyte/hyalinocyte ratio, and mantle lipid peroxidation were partly affected.
- Metabolomic analyses showed that mussel gills are valuable indicators of metabolic status under stress.
Abstract
Along with high temperatures, acidification, deoxygenation, and microplastics (MPs) pollution represent key drivers in coastal marine ecosystems. Sessile invertebrates living in coastal habitats are primarily exposed to the combination of these drivers, often at severe levels. Here, we investigated the individual and combined impacts of low pH (pHT: 7.35), low dissolved oxygen (DO) (1.91 mg L−1), and MP (26 μg L−1) in the Mediterranean mussel Mytilus galloprovincialis by measuring organismal and cellular parameters after a 15-day exposure period. Organismal parameters (respiration rate, ammonia excretion rate, absorption efficiency) as well as electron transport system (ETS) activity were not impacted by the stressors, either individually or combined. At the cellular level, however, we observed significant effects of these stressors individually and interactively on the hemocyte count, hemocyte viability, genotoxicity (comet assay), and gill metabolite profiles. In addition, we observed partial effects on the hemolymph phagocytic activity (PA) and granulocyte/hyalinocyte (G/H) ratio, and mantle lipid peroxidation (LPO). Metabolomics results manifested that the gill of mussels can serve as a valuable indicator of metabolic status under the stress of low pH, low DO and MP. Metabolites involved in osmoregulation, membrane stability, oxidative stress, energy, amino acid and nitrogen metabolism were significantly affected by the stressors, with low DO being the main driver of metabolic changes. We suggest that the individual and variable interactions of these stressors negatively impact M. galloprovincialis, except for the organismal and, to some extent, biochemical parameters.
Continue reading ‘The multiple responses of Mytilus galloprovincialis in the multi-stressor scenario: impacts of low pH, low dissolved oxygen, and microplastics’Environmental stressors interplay with top-down and bottom-up effects upon shell structure and function of an intertidal marine snail
Published 17 November 2025 Science ClosedTags: biological response, calcification, growth, laboratory, mesocosms, mollusks, morphology, multiple factors, physiology, predation, South Pacific, temperature
Highlights
- Environmental stressors affect shell properties varied across the trophic network.
- OA, OW and predator cues, reduced snail’s shell growth and calcification.
- OA and OW influenced shell structure and resistance more than predator risk.
- Food quality modulates periostracum organic content under OA and OW conditions.
- Biopolymer plasticity aids shell resistance, reducing climate stress vulnerability.
Abstract
Mollusc gastropods have evolved complex shells to protect their soft tissues from biotic and abiotic stress, but the impact of biological and environmental interactions on shell properties is not well understood. This study assessed how the individual and combined effects of increased temperature and pCO2 affect the structural and functional properties in shells of the intertidal snail Tegula atra, considering predator risk from the crab Homalaspis plana and changes in the nutritional quality of its food source, the brown kelp Lessonia spicata. Ocean acidification (OA) and ocean warming (OW) significantly affected growth rate and calcification of snails, with greater impacts under predator risk (top-down) than food quality (bottom-up) influences. FTIR-ATR analyses of the organic composition of shell periostracum indicated that OA conditions increased total organic matter, while polysaccharides, and carbonate content signals showed complex interactive effects under OA and OW conditions, with minor predator cue effects, while the nutritional value of the food source alters polysaccharides and lipids signals. Functional properties (resistance) of the shell material were affected by OA, OW, and predator cues but not by food quality source. These findings provides a novel understanding of how interacting climate stressors and trophic dynamics shape the structural (biomineralization) and functional (biomechanical) resilience of intertidal gastropods.
Continue reading ‘Environmental stressors interplay with top-down and bottom-up effects upon shell structure and function of an intertidal marine snail’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’Sediment topography enhances the response of coral reef carbonate sediment dissolution to ocean acidification
Published 13 November 2025 Science ClosedTags: annelids, biological response, BRcommunity, calcification, chemistry, community composition, laboratory, mollusks, otherprocess, primary production, respiration, sediment
The interaction between water flow and sediment topography (e.g., surface ripples) in shallow, permeable coral reef carbonate sediments establishes pressure gradients that increase the rate of sediment–water solute exchange relative to water flow along a flat bottom. It is unknown how this effect from surface ripples may modify the rate at which the sediment porewater is exposed to future chemical changes in the overlying water column, such as elevated pCO2 that is causing ocean acidification (OA). To address this question, this study used a series of 22-h incubations in flume aquaria with live permeable calcium carbonate sediment communities and examined the interactive effect of pCO2 (400 and 1000 µatm) and surface topography (flat and rippled sediments) on invertebrate infaunal activity, carbonate sediment microbial metabolism, and inorganic carbonate dissolution. Results show that the introduction of oxygen into flat sediments was largely driven by infaunal activity, whereas introduction of oxygen into rippled sediments was largely driven by physical flow processes. Rippled sediments exhibited rates of respiration and gross primary production that were ~ 45% and ~ 50% higher, respectively, than flat sediments. An increase in pCO2 shifted the sediments in the flat flumes from net calcifying to net dissolving, an effect that was amplified an additional ~ 60% in rippled sediments. These results suggest that current estimates of coral reef carbonate sediment calcification may be underestimating the dissolution response to OA where the carbonate sediment environment exhibits ripples in the topography.
Continue reading ‘Sediment topography enhances the response of coral reef carbonate sediment dissolution to ocean acidification’Impact of crustose coralline algae, ocean acidification, and ocean warming on larval pinto abalone settlement and juvenile survival
Published 11 November 2025 Science ClosedTags: algae, biological response, BRcommunity, communityMF, laboratory, mollusks, morphology, mortality, multiple factors, North Pacific, reproduction, temperature
Highlights
- Ocean acidification reduced pinto abalone settlement and survival in the hatchery.
- Ocean acidification is likely a greater threat than warming to Washington pinto abalone.
- Use of a natural settlement inducer improves abalone settlement and survival.
- Coralline algae may improve survival of pinto abalone under ocean acidification.
Abstract
Since 1994, Washington State (USA) has experienced a 97 % drop in the native pinto abalone population. Since 2007, conservation aquaculture initiatives have been underway to return the population to a self-sustaining level. Successful restoration, however, depends on both the ability to successfully raise juveniles in hatchery settings and the capacity of outplanted pinto abalone to survive and reproduce in the wild as threats of ocean acidification and warming continue to increase. Crustose coralline algae (CCA) can play an important role in restoration efforts by acting as natural inducers of larval settlement. Additionally, studies have shown that CCA can create a boundary layer with elevated pH, potentially providing a refuge for benthic species. We examined the settlement of pinto abalone under different environmental conditions (7.90 pH/14 °C (ambient), 7.90 pH/18 °C, 7.55 pH/14 °C; and 7.55 pH/18 °C) using two substrates: CCA-covered rocks and clean rocks with GABA (a chemical settlement inducer). Low pH negatively impacted larval settlement. Though settlement was higher with CCA than with GABA, this difference was not statistically significant. Juvenile survival was negatively impacted by low pH, but positively impacted by CCA presence, demonstrating the potential of CCA to increase juvenile pinto abalone survival and ameliorate the negative effects of low pH. Using CCA in hatchery culture and selecting sites with CCA cover for pinto abalone outplants may improve the efficiency of restoration in Washington.
Continue reading ‘Impact of crustose coralline algae, ocean acidification, and ocean warming on larval pinto abalone settlement and juvenile survival’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)’Impact of CO2-induced seawater acidification at increased hydrostatic pressure on cellular-level responses of the infaunal nereid Hediste diversicolor
Published 3 November 2025 Science ClosedTags: annelids, Baltic, biological response, laboratory, physiology
Carbon Capture and Storage (CCS) provides a promising mitigation technology for reducing the anthropogenic emission of carbon dioxide (CO2) to the atmosphere. Despite CO2 having been stored safely below the seafloor and the likelihood of leakage is considered small, experimental studies addressing the environmental impacts of potential leaks still present important support to ecological risk assessment. This study investigated biological responses at the cellular level to seawater acidification in a range simulating pH reduction in the overlying bottom water due to potential CO2 leakage from the CCS site in the Baltic Sea. In a series of 40-day laboratory experiments, the infaunal polychaete Hediste diversicolor was exposed in a hyperbaric TiTank to three pH levels (7.7, 7.0 and 6.3) at increased hydrostatic pressure (900 kPa) mimicking the actual situation at 80 m water depth. Hypercapnic conditions, particularly pH 7.0, induced oxidative stress in cells activating the defence mechanisms that included inhibition of GST and activation of CAT and GPx. The acidic environment did also cause damage to cellular membranes as indicated by an increase in the concentration of MDA. The activation of defence processes in the polychaetes did not interfere, however, with the energetic metabolism and aerobiosis remained the principal energy production pathway. Patterns of temporal variation of most cellular biomarkers revealed that after a 15–20 day initial response, the antioxidant and detoxification systems recovered their capabilities to cope with acidification highlighting the acclimatisation potential of the nereids to hypercapnia.
Continue reading ‘Impact of CO2-induced seawater acidification at increased hydrostatic pressure on cellular-level responses of the infaunal nereid Hediste diversicolor’Effects of ocean acidification on fatty acid composition in the Antarctic snail Neobuccinum eatoni
Published 31 October 2025 Science ClosedTags: adaptation, Antarctic, biological response, laboratory, mollusks, otherprocess, physiology
Introduction: Ocean acidification (OA), resulting from the absorption of increasing atmospheric CO2 by the oceans, represents a major threat to marine organisms. Despite growing concern, the biochemical responses of Antarctic species to OA remain poorly understood.
Methods: This study investigated the impact of OA (pH 7.70 ± 0.09) on the fatty acid (FA) composition of the Antarctic snail Neobuccinum eatoni over a two-month experimental period (December 2015–March 2016). Fatty acid profiles were analyzed in multiple tissues to assess potential alterations induced by low-pH (LpH) conditions.
Results: Significant tissue-specific changes in FA composition were detected, particularly in the mantle and gill. Under LpH exposure, notable modifications occurred in long-chain polyunsaturated fatty acids (LC-PUFAs) such as 22:5n-3, 22:6n-3, and 24:5n-6. Elevated LC-PUFA levels in the mantle suggested a compensatory response to oxidative stress, while shifts in the n-3/n-6 ratios in the gill pointed to potential alterations in immune and anti-inflammatory functions.
Discussion: Indicators of homeoviscous adaptation (HVA), including PUFA/SFA ratios and mean chain length (MCL), revealed biochemical strategies used by N. eatoni to maintain membrane fluidity under acidified conditions. This study provides the first evidence of FA-based responses to elevated pCO₂ in an Antarctic gastropod, highlighting the potential of fatty acids as sensitive biomarkers of physiological adaptation to environmental stressors.
Continue reading ‘Effects of ocean acidification on fatty acid composition in the Antarctic snail Neobuccinum eatoni’The negative responses and acclimation mechanisms of Neopyropia yezoensis conchocelis filaments to short- and long-term ocean acidification
Published 30 October 2025 Science ClosedTags: adaptation, algae, biological response, growth, laboratory, molecular biology, North Pacific, otherprocess, photosynthesis, physiology
Background
Ocean acidification (OA) significantly alters the carbonate chemistry of seawater, leading to a decrease of seawater pH to impact the physiological and biochemical processes of those intertidal macroalgae. Previous studies have focused on the response of macroalgae to OA at thallus stage, while the effects at filamentous stage remain insufficiently explored.
Results
This study investigated the physiological-biochemical and molecular mechanisms of the filamentous conchocelis stage (the diploid sporophyte) of Neopyropia yezoensis responding to short- (5 days) and long-term (20 days) OA (2000 ppm CO2, pH 7.53). The results showed that short-term OA rapidly inhibited the growth and photosynthesis, suppressed chlorophyll synthesis and nitrogen assimilation, and down-regulated genes associated with photosynthesis, Calvin cycle, and carbohydrate metabolism of N. yezoensis conchocelis filaments. However, N. yezoensis conchocelis filaments showed acclimation strategies under long-term OA, in terms of metabolic reorganization, prioritizing stress tolerance over growth. Further weighted gene co-expression network analysis (WGCNA) based on the metabolomic and transcriptomic results under long-term OA showed that the strategy was manifested by the accumulation of soluble sugars as osmolytes, lipid β-oxidation compensating for energy deficits, and H+ extrusion mediated via ABC transporters.
Conclusions
This study suggested time-depended responses of N. yezoensis conchocelis filaments to OA, proving the pronounced negative effects of OA on N. yezoensis conchocelis filaments, revealing N. yezoensis conchocelis filaments could acclimate to long-term OA by resource reallocation. These findings provide new insight into the survival of N. yezoensis conchocelis filaments under OA, and facilitate the development of technologies and breeding strategies for improved acidification tolerance in N. yezoensis.
Continue reading ‘The negative responses and acclimation mechanisms of Neopyropia yezoensis conchocelis filaments to short- and long-term ocean acidification’Gut microbial community plasticity as a climate shield mediating sea cucumber resilience to ocean acidification and warming
Published 28 October 2025 Science ClosedTags: biological response, BRcommunity, community composition, echinoderms, laboratory, mesocosms, multiple factors, North Pacific, otherprocess, physiology, prokaryotes, temperature
Ocean acidification (OA) and ocean warming (OW) pose escalating threats to marine ecosystems, particularly to benthic organisms, such as sea cucumbers, that play pivotal roles in nutrient cycling and sediment health. Existing studies have mostly focused on the physiological responses of sea cucumbers, yet overlooked the critical roles of both gut microbial communities and metabolites in the host’s responses under environmental stress. Herein, a mesocosm experiment was constructed and analyzed by using integrated gut microbiome and metabolomics approaches to investigate the responses of sea cucumbers Apostichopus japonicus to OA and OW. Results revealed that microbial community plasticity underpins holobiont adaptation, with warming restructuring gut microbiota toward thermotolerant taxa, whereas acidification enriches alkalinity-modulating Rhodobacteraceae and Halioglobus sp.. Metabolomic profiling identified 43 amino acid derivatives that exhibit significantly increased concentrations in the OA and OW groups. These derivatives include upregulated N-methyl-aspartic acid and γ-glutamyl peptides, which stabilize macromolecules and enhance redox homeostasis. Conversely, antioxidative metabolites, such as ergothioneine and L-homocystine, are suppressed, reflecting trade-offs between energy allocation and stress protection. In OW group, the antioxidant synthesis pathway is shifted to energy metabolism related to heat tolerance, whereas in OA group, energy is preferentially used for alkalinity regulation pathways rather than oxidative stress defense. Changes in microbial community structure mechanistically explain the trends in metabolite concentrations, as the proliferation of Vibrio spp. in the OW group drives lysine catabolism, leading to a significant increase in L-saccharopine levels. The reduction of Bacteroidetes in the OA group is correlated with the downregulation of L-homocystine, suggesting that pH-driven microbial interactions are disrupted. These findings demonstrate that gut microbiota reconfigure community structure and metabolic landscapes to buffer hosts against climate stress synergies, highlighting the importance of microbiome-mediated resilience in marine ecosystems under global climate change.
Continue reading ‘Gut microbial community plasticity as a climate shield mediating sea cucumber resilience to ocean acidification and warming’Impact of climate change driven freshening, warming, and ocean acidification on the cellular metabolism of Atlantic cod (Gadus morhua)
Published 27 October 2025 Science ClosedTags: biological response, fish, laboratory, multiple factors, North Atlantic, physiology, salinity, temperature
Climate change is causing increasing sea surface temperature, ocean acidification and, in near shore waters, freshening. We investigated the metabolic effects of all three and their combination in Atlantic cod from the Skagerrak (eastern North Sea) by measuring concentration changes of a wide range of metabolites involved in energy production in the liver and muscles. Liver metabolism was more strongly affected than muscle, reflecting its central regulatory role. Most amino acid concentrations declined in both tissues across all treatments, and metabolomic pathway analysis revealed significant enrichment in ten metabolic pathways. This suggests enhanced amino acid metabolism in a climate change future. Warming and ocean acidification induced increased liver concentrations of lactate, glucose and fructose 1,6-bisphosphate indicating that gluconeogenesis will increase to meet increased production of enzymes to counter future stress. The molar contribution of glutamine to the total change in liver amino acids constituted 49%, 16% and 29% under warming, ocean acidification and their combination accentuating its importance in energy production also under future climate change. We observed contrasting responses in AMP, ADP, and NAD+ concentrations between warming and acidification suggesting possible antagonistic effects. Our findings demonstrate significant and complex metabolic responses to future climate stress in Atlantic cod in northern European waters.
Continue reading ‘Impact of climate change driven freshening, warming, and ocean acidification on the cellular metabolism of Atlantic cod (Gadus morhua)’
