Yellowfin sole (Limanda aspera) support the largest flatfish fishery in the world and contribute substantially to the eastern Bering Sea (EBS) flatfish catch. The EBS has been warming and acidifying, trends that are expected to intensify into the future. Sustainable management of yellowfin sole requires an understanding of how yellowfin sole respond to environmental change, which can be assessed through controlled laboratory investigations. Across four independent trials, yellowfin sole embryos and larvae were incubated at one of six experimental treatments spanning three temperatures (9°C, 12°C, and 15°C) and two pCO2 target levels (low and high), and a range of organismal and physiological responses were measured. Embryonic daily mortality rates and metabolic rates increased with increasing temperature but were not affected by ocean acidification. At- hatch and at- yolk absorption, morphometric measurements (length, dry weight, myotome height, and yolk area) were temperature- sensitive, but the response differed across the four trials. There was a consistent increase in length- based growth and yolk absorption rates with increasing temperature across trials. All morphometric and rate- based measurements were not affected by ocean acidification. Yellowfin sole metabolic enzyme activities were measured at- yolk absorption. Lactate dehydrogenase (anaerobic metabolism) and β- hydroxyacyl CoA dehydrogenase (fatty acid metabolism) both increased with increasing temperature, indicating elevated energy demand. Citrate synthase (aerobic metabolism) declined with increasing pCO2 levels, indicating potential metabolic suppression. Overall, embryonic and larval yellowfin sole demonstrated relatively high tolerance to ocean warming and acidification. We hypothesize the variation in temperature responses across the trials may be driven by maternal effects, which could support tolerance to future ocean conditions.
Continue reading ‘Tolerance of egg and yolk-sac larval yellowfin sole (Limanda aspera) to ocean warming and acidification’Posts Tagged 'growth'
Tolerance of egg and yolk-sac larval yellowfin sole (Limanda aspera) to ocean warming and acidification
Published 23 March 2026 Science ClosedTags: biological response, fish, fisheries, growth, laboratory, morphology, mortality, multiple factors, North Pacific, physiology, reproduction, temperature
Novel in situ CO2 enrichment system reveals seagrass meadows are a refugium against coastal acidification for North Atlantic bivalves
Published 18 March 2026 Science ClosedTags: biological response, BRcommunity, chemistry, growth, laboratory, mollusks, mortality, North Atlantic, phanerogams
While the accumulation of anthropogenic CO2 in the atmosphere is causing a decline in global ocean pH, many eutrophic estuaries are already experiencing acidification due to accelerated respiration driving the consumption of dissolved oxygen (DO) and production of CO2, decreasing available carbonate ions (CO32-) and threatening marine calcifiers. Here, a novel in situCO2 enrichment system was constructed to examine the effects of coastal acidification on the growth and survival of two species of North Atlantic bivalves (Argopecten irradians and Crassostrea virginica) in two distinct estuarine habitats: a seagrass meadow and an unvegetated sandy bottom in an open water estuary. The in-situ system captured natural diel dynamics as ambient chambers displayed chemistry nearly identical to the surrounding water, while CO2-enriched, acidified chambers maintained a consistent ~Δ 0.3–0.5 pH offset. At the unvegetated sandy bottom site, A. irradians and C. virginica displayed significant reductions in growth and survival in the acidified chambers (pHT = 7.3–7.5; saturation state of aragonite, ΩAr = 0.6–0.9) relative to ambient conditions (pHT = 7.6–7.9; ΩAr = 1.6–2). At the seagrass site, while growth of A. irradians and C. virginica in the acidified treatments (pHT = 7.3–7.7; ΩAr = 0.7) receiving the same delivery of CO2 was, again, significantly slowed compared to the control (pHT = 7.5–8.1; ΩAr = 2 – 2.8), the growth reduction, mortality rates, and levels of acidification were attenuated compared to the sandy bottom experiment, evidencing the ability of seagrass to buffer seawater and serve as a potential acidification refuge for bivalves. Collectively, the novel experimental CO2 enrichment system constructed for this project demonstrates that coastal acidification can have deleterious effects on marine bivalve populations, and that future conditions as well as the habitat refuge offered by seagrasses must be considered when developing management and restoration plans for temperate estuaries.
Continue reading ‘Novel in situ CO2 enrichment system reveals seagrass meadows are a refugium against coastal acidification for North Atlantic bivalves’Eco-evolutionary dynamics of planktonic calcifying communities under ocean acidification
Published 12 March 2026 Science ClosedTags: adaptation, biological response, BRcommunity, calcification, communitymodeling, growth, modeling, mortality, otherprocess, performance, phytoplankton, primary production, zooplankton
Increasing emissions of CO2 into the atmosphere are causing ocean acidification, threatening calcifying organisms. In this study, we model the physiological responses of coccolithophorids to acidification to understand the ecological and evolutionary outcomes of a system in interaction with zooplankton. Assuming a trade-off between growth and protection against grazing, we show that calcification has bivalent effects on transfers between two trophic levels and that acidity can strongly alter energy transfers. Taking into account the evolution of calcifying phenotypes in response to acidification, we show that the system outcome contrasts with previous results. While the effect of evolution depends on how calcification affects grazing, it nevertheless follows that acidification leads to a decrease in calcifying capacity. This evolutionary decrease may be progressive, but can also lead to tipping points where abrupt shifts may occur. Such a counter-selection of calcification in turn affects ecosystem functioning, enhancing energy transfers within the system and modifying carbon fluxes. We discuss how such eco-evolutionary changes may impact food webs integrity, carbon sequestration into the deep ocean and therefore endanger the carbon pump stability.
Continue reading ‘Eco-evolutionary dynamics of planktonic calcifying communities under ocean acidification’Colony formation sustains the global competitiveness of nitrogen-fixing Trichodesmium under ocean acidification
Published 5 March 2026 Science ClosedTags: biological response, growth, individualmodeling, modeling, nitrogen fixation, photosynthesis, physiology, prokaryotes
Anthropogenic carbon dioxide emissions drive ocean acidification. Trichodesmium, a key marine nitrogen-fixing cyanobacterium, displays contrasting growth responses to ocean acidification across morphotypes: negative in filamentous free trichomes but neutral or positive in colonies. However, lacking mechanistic understanding for these discrepancies has impaired our ability to predict Trichodesmium’s ecophysiological response. Here, we develop ecophysiological models to underpin mechanisms behind these divergent responses. For free trichomes, ocean acidification reduces nitrogen-fixing enzyme activity and photosynthetic energy production. In colonies, however, it alleviates copper and ammonia toxicity within the microenvironment—likely synergizing with enhanced iron acquisition—thereby outweighing minor benefit from relieved inorganic carbon limitation in the colony center. Projections suggest that globally, ocean acidification will reduce nitrogen fixation of trichomes by 16 ± 6% but increase that of colonies by 19 ± 24% within this century. By resolving morphotype-specific mechanisms, our study clarifies Trichodesmium’s adaptive strategies for sustaining its competitiveness and biogeochemical impacts in the changing ocean.
Continue reading ‘Colony formation sustains the global competitiveness of nitrogen-fixing Trichodesmium under ocean acidification’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
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’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’Chronic exposure to low pH negatively impacts blue mussels (Mytilus edulis) from an intertidal zone
Published 20 January 2026 Science ClosedTags: adaptation, biological response, growth, laboratory, mollusks, mortality, North Atlantic, otherprocess, physiology
In intertidal ecosystems, mussels experience daily fluctuations in pH due to the biological activity, intertidal currents, freshwater inflow and anthropogenic influences. This study aimed to determine whether these short-term fluctuations enable blue mussels (Mytilus edulis) to endure long-term exposure to low pH using biological indicators (mortality rates, oxidative stress and enzyme activities). Mussels were collected from an intertidal zone in the western coast of Morocco and exposed for 6 months to seawater pH ranging from 6.6 to 8.0. Our results showed that mortality rates increased exponentially with decreasing pH, while growth rates declined linearly. At pH 6.6, mortality was observed after approximately 15 days and reached 22% at 6 months. Low pH negatively impacted the function of metabolic enzymes (glyceraldehyde-3-phosphate dehydrogenase and succinate dehydrogenase), and caused oxidative stress (elevated lipid peroxidation and protein oxidation) in the mantle, digestive gland, and whole tissues. Additionally, the activity of antioxidant enzymes catalase and superoxide dismutase increased in response to higher levels of reactive oxygen species at low pH. These findings suggest that, although mussels can inhabit intertidal zones with short-term pH fluctuations, this does not equip them with the ability to deal with chronic exposure to low pH (6.6), significantly impairing their fitness.
Continue reading ‘Chronic exposure to low pH negatively impacts blue mussels (Mytilus edulis) from an intertidal zone’Ocean acidification and anthropogenic carbon in the Eastern Mediterranean Sea and the effects of acidification on marine organisms
Published 15 January 2026 Science ClosedTags: biological response, chemistry, field, fisheries, growth, laboratory, Mediterranean, mollusks, mortality, photosynthesis, physiology, phytoplankton, respiration
Ocean acidification (OA), driven by rising atmospheric carbon dioxide (CO2) levels, is a critical issue affecting our oceans. The Eastern Mediterranean Sea (EMS) remains poorly understood in terms of the carbonate system and the impact of OA, despite its key role in Levantine Intermediate Water (LIW) formation and its peculiar characteristics in buffering capacity and ongoing OA. This study provides the first comprehensive spatial and temporal assessment of carbonate system in the North-Eastern Levantine Basin, in EMS, providing essential reference data for Total Alkalinity (TA), Dissolved Inorganic Carbon (DIC), and Anthropogenic Carbon (CANT). The mean TA of the measurements was 2622.11 μmol/kg, with higher surface values in summer, reflected also in the surface salinity (S) maximum caused by strong evaporation. A clear vertical gradient was observed, with TA decreasing with depth. Hot and dry meteorological conditions contribute to increased S and TA, resulting in seasonal and vertical variations in the water column. The mean DIC of the measurements was 2291.23 μmol/kg. In contrast to the observations for TA, surface DIC values were higher in winter than in summer. The higher DIC values in winter are attributed to thermodynamic equilibrium and vertical mixing in the surface waters. This study has also investigates the presence of CANT, has infiltrated deep layers, with a mean concentration of 52.07 μmol/kg, decreasing significantly throughout the water column. These findings confirms the ongoing influence of human activities on intermediate and deep layers in EMS. To reconstruct past carbonate system dynamics, the relationships of TA and DIC were determined with salinity (S) and temperature (T) data. Long-term data from METU-IMS Erdemli Time Series (ETS) stations, collected monthly for a decade, provided valuable findings into seasonal patterns and temporal shifts in TA, DIC, and pH. The coastal station displayed clear trends in the carbonate system over time, reflecting its sensitivity to local environmental changes. In contrast, the offshore station exhibited minimal variability, indicating greater stability against seasonal and long-term fluctuations. These results highlight the heightened vulnerability of coastal waters to carbonate system changes, while offshore waters remain more stable. Understanding carbonate chemistry and acidification levels is crucial for assessing impacts on marine life. In addition to the characterization of carbonate chemistry, this study also explores OA’s biological impacts on two key organisms of the Mediterranean ecosystem: phytoplankton and mussels. Firstly, effects of elevated CO₂ on phytoplankton, an essential primary producer in aquatic food webs and global biogeochemical cycles are explored. Specifically, the study explores the impacts on phytoplankton physiology, focusing on growth rates, respiration, and photopigment content in selected species from the coccolithophores, dinoflagellates, and diatoms groups. While growth rates and respiration remained relatively stable under reduced pH conditions, photopigment content was significantly influenced by changes in seawater pH, highlighting the importance of considering environmental influences on photopigment composition. The study further investigated the effects of acidification on calcifying organisms through a global program aimed at understanding the long-term effects of acidification on key seafood species and exploring adaptation strategies with a collaborative approach. This study focused on the long-term (6 months long experiment) physiological impacts of OA on marine calcifiers, specifically Mediterranean mussel, Mytilus galloprovincialis, an abundant species and one of the most consumed non-fish marine species in Türkiye. Results indicate that OA poses a substantial threat to mussel health and survival. Reduced pH levels negatively impacted survival rates, while other physiological parameters like clearance rate, condition index, respiration, and the distribution of a radionuclide, 210Po, did not significantly change. However, lipid content and immune response were affected. Oxygen consumption decreased over time, especially at lower pH. This study underscores the potential risks of OA to the fitness of the commercially important mussel species, indicating that future OA may impact both this key seafood species and its associated ecosystems. The established baseline data are crucial for future monitoring and provide valuable insights into the vulnerability of marine organisms and ecosystems to ongoing OA. By integrating chemical, biological, and ecological perspectives, this dissertation offers a comprehensive assessment of OA in EMS. It establishes baseline data for carbonate system variables, revealing distinct spatial and temporal variations influenced by S, T, and mixing processes. By linking changes in carbonate chemistry to physiological responses in primary producers and a commercially vital shellfish species, this study highlights the ecological and economic impacts of OA in EMS. The findings emphasize the need for continued research and mitigation efforts to protect marine ecosystems and commercially important species. This integrated approach provides valuable insights into the vulnerability of marine organisms and ecosystems to ongoing OA, underscoring the significance of this research for the Mediterranean Sea.
Continue reading ‘Ocean acidification and anthropogenic carbon in the Eastern Mediterranean Sea and the effects of acidification on marine organisms’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’Strength and duration of diel pH and dissolved oxygen cycles control the survival and performance of early life stage North Atlantic bivalves (Mercenaria mercenaria, Crassostrea virginica, Argopecten irradians and Mytilus edulis)
Published 9 January 2026 Science ClosedTags: biological response, growth, laboratory, mollusks, mortality, multiple factors, North Atlantic, oxygen, physiology, reproduction, respiration
Highlights
- Cycling from nocturnal hypoxia – acidification to mild hyperoxia- hypocapnia reduced larval survival in all experiments.
- Cycling from nocturnal hypoxia – acidification to normoxia- normocapnia reduced survival of larvae in 50 % of experiments.
- Nocturnal hypoxia and acidification caused increased clearance and respiration rates in juvenile mussels.
- The impacts of diel DO and pH cycles on early life stage bivalves depend on cycle duration, cycle intensity, and species.
Abstract
Many economically important bivalves spawn during the summer months when diel cycles of dissolved oxygen (DO) and pH occur in estuaries. Little is known, however, regarding how cycles of differing durations and magnitudes affect these organisms. Here, larval bivalves (Mercenaria mercenaria, Crassostrea virginica, Argopecten irradians) and juvenile mussels (Mytilus edulis) were exposed to cycles of low DO and pH of varying duration (4-, 6-, 8-, and 12-h) and strength (moderate: DO range ∼ 6 mg L−1, pH range ∼ 0.6 and severe: DO range ∼ 10 mg L−1, pH range ∼ 0.9) compared to positive (normoxic and normocapnic) and negative (hypoxic and acidified) static controls. Growth, survival, respiration and clearance rates were measured. During experiments, 12 h of nocturnal hypoxia and acidification coupled with mildly hyperoxic (∼11.3 mg L−1 DO) and hypocapnic (∼8.13 pH) conditions by day significantly reduced survival in larval C. virginica, M. mercenaria, and A. irradians in all experiments (p < 0.05), while 12 h of nocturnal hypoxia and acidification without hyperoxic and hypocapnic conditions did so in only half of experiments indicating that hyperoxia and hypocapnia were additional and significant stressors. Six hours of low DO/pH significantly reduced survival in only 16 % of experiments, indicating that larval bivalves are more impacted by longer duration and greater magnitude cycles of DO and pH compared to cycles of shorter duration or lower magnitude. Across species, M. mercenaria larvae were more resilient to nocturnal hypoxia and acidification than A. irradians and C. virginica. The growth and survival of juvenile M. edulis were unaffected by nocturnal hypoxia and acidification but mussels experienced significantly increased clearance and respiration rates under these conditions (p < 0.01) evidencing physiological mechanisms for coping with these stressors. Collectively, this study demonstrates that the impacts of diel DO and pH cycles on early life stage bivalves are dependent upon cycle duration, cycle intensity, bivalve life stage, and bivalve species.
Continue reading ‘Strength and duration of diel pH and dissolved oxygen cycles control the survival and performance of early life stage North Atlantic bivalves (Mercenaria mercenaria, Crassostrea virginica, Argopecten irradians and Mytilus edulis)’Reproduction of the viviparous marine isopod Cirolana harfordi held in seawater with raised temperature and lowered pH
Published 2 January 2026 Science ClosedTags: biological response, crustaceans, growth, laboratory, mortality, multiple factors, reproduction, temperature, zooplankton
Cirolanid isopods play important ecological roles as predators and scavengers, but when populations increase, they can form swarms that attack fish and humans. Understanding how the reproduction of cirolanid isopods will be affected by future warmer and more acidic oceans is therefore important. Samples of the viviparous species Cirolana harfordi were held in 4 combinations of 2 temperatures (18 and 24°C) and 2 pH levels (7.7 and 8.1), and the development of embryos and mancas was investigated by microscopic examination of each pregnant female through the transparent ventral cuticle of their thorax. Higher temperature increased the rate of development, thereby reducing pregnancy duration and accelerating the growth of mancas postpartum. By contrast, increased acidity had no significant effect on these parameters and had no deleterious effects on the development of the mancas. Higher temperature did not have a significant effect on the number of postpartum mancas after the 22 weeks that the adults spent in treatments. Increased temperature and/or lowered pH had no effect on the adult survival or growth. These data are in keeping with the hypothesis that C. harfordi may be able to withstand future warmer and more acidic oceans. Longer-term studies are needed to determine whether decreasing pregnancy durations in higher temperatures increases the number of times females can become pregnant over their lifetime, potentially leading to greater population numbers.
Continue reading ‘Reproduction of the viviparous marine isopod Cirolana harfordi held in seawater with raised temperature and lowered pH’A global meta-analysis reveals consistently negative effects of ocean acidification on marine cultured bivalves: implications for future bivalve aquaculture
Published 16 December 2025 Science ClosedTags: biological response, calcification, fisheries, growth, mitigation, mollusks, mortality, performance, physiology, reproduction, review
The exponential rise in atmospheric CO₂ driven by human activities is accelerating climate change and causing ocean acidification (OA). While the effects of elevated CO₂ on a wide range of marine species have been well documented, the implications of OA for bivalve aquaculture have received comparatively little attention. Using a multi-level meta-analytical approach, we evaluated the impacts of two elevated pCO₂ levels—classified as high and extreme—on cultured bivalves, based on 266 observations from 24 species across tropical and temperate regions. Overall, both elevated pCO₂ levels negatively affected bivalves, reducing survival, growth, feeding rates, development, and calcification. Larvae were generally more vulnerable than juveniles and adults. Our analyses further indicated that temperate bivalves were more sensitive to OA than tropical and subtropical counterparts. Among taxa, clams were the most vulnerable under high CO₂ emission scenarios, whereas scallops were the most sensitive under extreme pCO₂ levels. We also discuss potential mitigation strategies for the bivalve aquaculture industry. With advancements in local and regional monitoring, coupled with targeted measures such as buffering sites, selective breeding, and integrated multi-trophic aquaculture, the adverse effects of OA on bivalve farming could be mitigated.
Continue reading ‘A global meta-analysis reveals consistently negative effects of ocean acidification on marine cultured bivalves: implications for future bivalve aquaculture’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’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’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’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’Newly discovered CO2 (carbon dioxide) vent cave drives r-strategy shift in a Mediterranean aphotoendosymbiotic coral
Published 14 November 2025 Science ClosedTags: abundance, biological response, chemistry, corals, field, growth, Mediterranean, morphology, reproduction, vents
Highlights
- Characterization of an unexplored CO2 vent cave
- CO2 vents chemical-physical parameters affect ecological traits of calcifiers
- Aphotoendosymbiotic solitary coral naturally inhabiting a CO2-rich gas environment.
- Prolonged acidified conditions did not affect C. inornata growth rate
- Shift towards an r-demographic strategy in response to acidified conditions
Abstract
Submarine CO2 volcanic vents represent peculiar environments with varying seawater chemical-physical parameters that may affect the ecological traits of calcifying organisms, such as growth and demographic characteristics. The present study focused on exploring the growth and population dynamics of a temperate, solitary and aphotoendosymbiotic coral Caryophyllia inornata (Duncan, 1878) living in a CO2 vent cave at 14 m depth. The volcanic emissions in and around the cave led high levels of pCO2, resulting in lower calcium carbonate saturation state (Ωa: 2.1–2.2) values compared to those observed in the ambient seawater of the Mediterranean Sea, not affected by venting activity. Prolonged acidified conditions (pHT: 7.5) did not affect C. inornata growth rate but resulted in a population with higher percentage of juvenile individuals, lower average ages and a lower age at maximum biomass percentage, thus suggesting a transition in its population dynamics towards an r-demographic strategy. This study provides a detailed characterization of a previously unexplored CO2 vent cave, highlighting the importance of these sites as natural laboratories to offer valuable insights into understanding the full ecological impact of aphotoendosymbiotic corals under ocean acidification.
Continue reading ‘Newly discovered CO2 (carbon dioxide) vent cave drives r-strategy shift in a Mediterranean aphotoendosymbiotic coral’Colony formation sustains the global competitiveness of N2-fixing Trichodesmium under ocean acidification
Published 10 November 2025 Science ClosedTags: biological response, growth, individualmodeling, modeling, nitrogen fixation, photosynthesis, primary production, prokaryotes
Anthropogenic CO2 emissions drive ocean acidification (OA). Trichodesmium, a key marine N2 fixer, displays contrasting growth responses to OA across morphotypes, with negative responses in free trichomes but neutral or positive in colonies. However, the lack of mechanistic understanding for these discrepancies has impaired our ability to predict the ecophysiological response of Trichodesmium in the changing ocean. Here, we developed ecophysiological models of Trichodesmium and underpin mechanisms behind contrasting responses to OA by distinct morphological adaptations. For free trichomes, our diurnal model corroborated previous findings that OA impairs nitrogenase efficiency and photosynthetic energy production. In colonies, however, OA alleviated copper and ammonia toxicity within the microenvironment, potentially with increased iron acquisition synergies, outweighing the minor effects of inorganic carbon limitation relief in the colony center. Projections suggest that globally, OA will reduce N2 fixation of trichomes by 16±6% but increase that of colonies by 19±24% within this century. By resolving morphotype-specific mechanisms, our study clarifies Trichodesmium’s adaptive strategies, which may enable it to sustain its competitiveness and biogeochemical impacts in the changing ocean.
Continue reading ‘Colony formation sustains the global competitiveness of N2-fixing Trichodesmium under ocean acidification’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’Warming, but not acidification, increases metabolism and reduces growth of redfish (Sebastes fasciatus) in the Gulf of St. Lawrence
Published 16 October 2025 Science ClosedTags: biological response, fish, fisheries, growth, laboratory, multiple factors, performance, physiology, temperature
Understanding the effects of global change, including temperature, pH, and oxygen availability, on commercially important species is crucial for anticipating consequences for these resources and their ecosystems. In the Gulf of St. Lawrence (GSL), redfish (Sebastes spp.) were under moratorium from 1995 to 2023, but the fishery has reopened in 2024 following massive recruitment observed in 2011–2013. Despite current high abundance, little is known about their metabolic and thermal physiology. To address this, we quantified the effects of four acclimation temperatures (2.5, 5.0, 7.5, and 10.0 °C) and two ocean acidification scenarios (current and future) on standard and maximum metabolic rates (SMR and MMR), aerobic scope (AS), factorial aerobic scope, hypoxia tolerance (O2crit), food consumption, growth and food conversion efficiency (FCE) in redfish (Sebastes fasciatus Storer, 1854). SMR, MMR, and AS increased with temperature, but growth and FCE decreased with temperature, likely due to increased cost of maintenance. Food consumption was lower at 2.5 °C, but similar at higher temperatures. Redfish were less hypoxia-tolerant at higher temperatures. Except for SMR, no significant effect of pH was observed. These results suggest that future changes in the GSL will challenge redfish, with potential long-term effects on growth due to increased energy requirements.
Continue reading ‘Warming, but not acidification, increases metabolism and reduces growth of redfish (Sebastes fasciatus) in the Gulf of St. Lawrence’
