Ocean acidification (OA) is reshaping marine biogeochemistry and threatens microbial communities that regulate carbon and nutrient cycling. Although existing bibliometric reviews have examined OA in relation to coral reefs, calcifying organisms, and broader marine ecosystems, no study has systematically mapped the specific sub-domain of OA impacts on microbial ecology, a gap that hinders identification of methodological blind spots, collaboration imbalances, and under-explored research frontiers unique to microbial systems. Meanwhile, research progress on OA-driven microbial change remains fragmented and lacks a systematic analysis of the field’s evolutionary trajectory and emerging frontiers. This study presents a comprehensive bibliometric analysis of 495 publications retrieved from the Web of Science Core Collection (2005–2025), utilizing CiteSpace to map the knowledge domain of OA impacts on microbial ecology. Temporal analysis reveals three distinct developmental phases: emergence (2005–2010), exponential growth (2011–2021), and recent stabilization (2022–2025). The global collaboration network spans 53 countries, characterized by a triadic leadership structure involving China, the United States, and Germany, with the GEOMAR Helmholtz Centre serving as a central institutional hub. Keyword co-occurrence and burst detection analyses uncover a significant paradigm shift: the research focus has transitioned from foundational carbonate chemistry parameters to complex ecosystem-relevant microbial processes, including community structure, functional genes, and biogeochemical cycling. Notably, “responses” emerges as the most active contemporary research frontier with the strongest recent citation burst, reflecting a consolidated focus on how microbial communities adapt to acidification stress at physiological, community-structural, and functional levels. However, network analysis also reveals structural blind spots: archaea and viral ecology remain conspicuously absent from high-frequency keyword clusters despite their recognized ecological importance, and research contributions from Africa, Southeast Asia, and Small Island Developing States are markedly limited. Based on these findings, we propose four evidence-linked strategic directions centered on multi-omics integration, spatiotemporal expansion through global observatory networks, factorial multi-stressor experimental designs, and bridging molecular processes to ecosystem-scale biogeochemical cycles. This study provides a data-driven roadmap for next-generation research on OA-microbe interactions, essential for predicting ecosystem resilience in a changing ocean.
Continue reading ‘From carbonate chemistry to community responses: thematic evolution in ocean acidification and microbial research — a bibliometric analysis’From carbonate chemistry to community responses: thematic evolution in ocean acidification and microbial research — a bibliometric analysis
Published 1 June 2026 Science Leave a CommentChemical cues and molecular mechanisms suspected in abiotic stress communication
Published 1 June 2026 Science Leave a CommentFor nearly a century, scientists have tried to resolve the sensory physiology of chemical communication caused by predation stress. Only recently have we evidenced that abiotic stressors from a changing world, such as heat and ocean acidification, also trigger chemical communication between aquatic organisms – which we dubbed abiotic stress communication. Generally, the behavioural and physiological response to stress-induced cues are well understood, whereas the molecular mechanisms – cue identities, pathways of release, and perception – of this stress communication remain unresolved. Here, we propose a framework to organize the existing evidence for candidate mechanisms involved in abiotic stress-induced chemical communication, focusing on heat and acidification as two major abiotic stressors with environmental relevance. Drawing on transcriptomic, metabolomic and behavioural evidence, we propose that stressor-specific communication likely involves multiple cues and parallel routes rather than a single mechanism, such as membrane-related processes. We call for integrative work that links -omics with chemical profiling and ecological function assays to uncover the mechanisms of abiotic stress communication.
Continue reading ‘Chemical cues and molecular mechanisms suspected in abiotic stress communication’Tropical cyclones may soon flip from releasing carbon to absorbing it
Published 29 May 2026 Press releases Leave a Comment
For years, scientists have known that the ocean does a huge amount of the planet’s climate work for us.
The ocean absorbs a large share of the carbon dioxide, taking in roughly 20 to 30 percent of human-caused CO2 emissions since the industrial era. At the same time, tropical cyclones are among the most violent things that happen on Earth’s surface. They churn the upper ocean, stir up deep water, cool the sea surface, and leave behind lingering physical changes that can last for weeks. What has been much less clear is how those storms affect the ocean’s role in the carbon cycle. Do tropical cyclones help the ocean absorb carbon, or do they cause it to release more back into the atmosphere?
A new study suggests the answer is not simple, and it may also be changing.
A role reversal for tropical cyclones
The study was led by experts at the National University of Defense Technology (NUDT), Chinese Academy of Sciences, the NSF National Center for Atmospheric Research, and the GEOMAR Helmholtz Centre for Ocean Research Kiel.
The team pulled together a large set of observations to build a globally available daily dataset of air-sea CO2 flux. Using that, they were able to track how tropical cyclones have influenced the exchange of carbon between the ocean and the atmosphere over time. Their conclusion is that tropical cyclones have tended to push carbon out of the ocean and into the air. But that effect has been weakening in recent decades, and if warming continues under high emissions, the role of these storms may eventually flip.
A messy carbon signal
At first, the result sounds a little counterintuitive. The researchers found that tropical cyclones generally cause net ocean carbon outgassing. The main reason is that the intense winds of a cyclone greatly strengthen the transfer of CO2 from sea to air. But there is another process happening at the same time. After a tropical cyclone passes, it often leaves behind a cold wake, a patch of sea surface that has cooled because the storm mixed the upper ocean so strongly. That cooling can increase the ocean’s ability to take up carbon dioxide from the atmosphere, partly offsetting the carbon being released. Tropical cyclones are doing two things at once: they are helping CO2 escape because of their winds, while also setting up conditions that can later encourage carbon uptake.
The new study suggests that, historically, the first effect has usually won out. Even so, that balance has not stayed fixed.
Why the balance is shifting
One of the most striking findings is that cyclone-driven carbon outgassing seems to be declining. During the period from 1993 to 1997, tropical cyclones accounted for about 16 percent of the global annual carbon flux linked to these storm-related exchanges. By 2016 to 2020, that number had dropped to about 4.5 percent. That is a big shift in a relatively short amount of time.
The researchers argue that global warming is the key reason. As the climate warms, the surface ocean is heating faster than the water below it, which strengthens the vertical temperature gradient in the upper ocean. That matters because when a tropical cyclone hits a more strongly stratified ocean, the storm can produce stronger surface cooling. And that stronger cooling makes it easier for the ocean to absorb CO2 afterward.
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A reversal may be coming
The study goes a step further and warns that under continued high human emissions, tropical cyclones may eventually stop acting as a net source of ocean carbon release and start doing the opposite. According to the authors, that reversal could happen sometime after about 2035 if anthropogenic carbon dioxide emissions remain high. That sounds, at first glance, like good news. If tropical cyclones begin enhancing ocean carbon uptake instead of release, it might seem as though the ocean is helping more.
But the researchers are careful not to frame it that way.
More carbon in the ocean
More carbon entering the ocean does not just disappear harmlessly. It changes seawater chemistry and worsens ocean acidification, which can be deeply harmful for marine ecosystems. So even if storms begin to drive more ocean uptake overall, that would not represent a climate win. It would mean additional pressure on ocean life. The authors note that this kind of shift could intensify chemical changes in seawater and contribute to habitat loss for marine species.
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Why emissions still matter
The most important point in the study may be that the future role of tropical cyclones depends heavily on what people do next. If carbon emissions remain high, the storms’ contribution to ocean carbon uptake will likely strengthen sooner, pushing more carbon into the sea and worsening acidification risks. If emissions are brought under control quickly, the shift would happen more slowly.
Broader implications of the study
The authors suggest that with immediate mitigation, the downward trend in cyclone-driven carbon flux would probably not reverse until around the 2040s. Even then, it could take until late in the century for ocean carbon uptake linked to these storms to return to today’s levels.
“The role of tropical cyclones in the global carbon cycle has long been obscure, owing to sparse observations during and after tropical cyclones,” said study co-author Zhanhong Ma.
“This work provides a sophisticated global air-sea carbon flux dataset, enabling exploration of the tropical cyclone contribution in the context of global warming.”
The study is published in the journal Nature Geoscience.
Continue reading ‘Tropical cyclones may soon flip from releasing carbon to absorbing it’Reduction of tropical cyclone-induced ocean carbon outgassing since 1993
Published 29 May 2026 Science Leave a CommentThe ocean is a major sink of anthropogenic carbon, absorbing 20~30% of anthropogenic CO2 emissions across the air–sea interface. Intense weather systems, such as tropical cyclones, can strongly perturb the upper ocean and thus critically influence this carbon transfer. Here we develop an approach of synthesizing various observations to quantify the role of tropical cyclones in the global carbon cycle. Two primary, but competing effects are: (1) CO2 efflux (from the ocean to atmosphere) during tropical cyclone passage and (2) CO2 influx after tropical cyclones, associated with disturbed carbon disequilibrium by mixing upwards of colder water (cold wakes). The CO2 efflux more than offsets the influx, resulting in net ocean carbon outgassing to the atmosphere. Annual tropical cyclone-induced carbon outgassing has decreased over the past three decades, from 0.09 ± 0.02 PgC in the 1990s to 0.05 ± 0.01 PgC in the 2010s. A strengthening of the vertical temperature gradient in the upper ocean due to anthropogenic climate warming leads to cold wakes with more intense surface cooling and increased carbon uptake after tropical cyclones. This has implications as the vertical temperature gradient continues to grow under high-emissions scenarios, tropical cyclones will cause net increasing ocean carbon uptake and more severe ocean acidification.
Continue reading ‘Reduction of tropical cyclone-induced ocean carbon outgassing since 1993’Darkness and body size shaped end-Cretaceous marine extinction patterns
Published 29 May 2026 Science Leave a CommentThe Chicxulub asteroid impact at the Cretaceous–Paleogene (K–Pg) boundary (66 Ma) is thought to have caused the extinction of around 75% of species in the fossil record by triggering catastrophic environmental changes1. However, despite decades of research, the mechanisms linking the environmental changes to the selective extinction patterns observed in the marine fossil record remain unresolved. Here we use a global trait-based ecosystem model2,3 to establish this causality for the marine plankton community beyond the fossilized groups. Our model simulates diversity dynamics during the initial 100 years after the K–Pg boundary and represents explicitly extinction based on biomass thresholds that scales with body size. Under K–Pg climatic forcings, the model reproduces successfully key observed extinction patterns, including the high vulnerability of planktic foraminifera and other zooplankton, the survival of small mixotrophs4 and phytoplankton5,6, and potential for reduced diversity loss in high-latitude settings7. Our analysis suggests that impact-driven darkness and body-size-dependent extinction thresholds drove most of the observed extinction patterns. These results suggest that plankton ecologies enhance survival through differences in energy demand and acquisition. Our study bridges the gap between fossil evidence of extinction patterns and the K–Pg impact winter hypothesis, highlighting the value of trait-based models for understanding past biodiversity crises.
Continue reading ‘Darkness and body size shaped end-Cretaceous marine extinction patterns’Effects of acidified seawater on growth, nutritional condition, and olfactory sensory of the Asian seabass (Lates calcarifer) larvae
Published 28 May 2026 Science Leave a CommentMarine ecosystems are increasingly vulnerable to multiple stressors associated with climate change, resulting in significant ecological impact including ocean acidification. A 30-day experiment was conducted to investigate the effect of acidified seawater on the growth performance, nutritional status and free neuromast of olfactory organ condition of early larval stage of Asian seabass (Lates calcarifer) larvae. In this experiment, carbon dioxide (CO2) gas was introduced to lower seawater pH, and a timer system was installed to maintain the pH within specific ranges (5.5, 6.0, 6.5, and 7.0) while, a control treatment (pH fluctuating from 7.8 to 8.5) was also set, mimicking the current pH value of the seawater. Asian seabass larvae (initial total length: 2.13 ± 0.23 mm) were stocked at 30 individual/L in a 7L experimental aquarium in triplicate. The highest survival rate was obtained by Asian seabass larvae reared in control treatment 30.9±8.6% %, while total mortality was observed in pH 5.5 as early as day 1, followed by pH 6.0 and 6.5 at day 2 and 7.0 at day 5, respectively. The larvae in control group showed significantly better growth (14.25±1.02 mm) with excellent nutritional condition. Meanwhile, exposure to acidified seawater significantly reduced the length and density of larval olfactory neuromast hair cells compared to the control. It was concluded that acidified seawater induced mortality at early stage and triggered poor morphological development, resulting from inadequate nutritional condition and impaired sensory function.
Continue reading ‘Effects of acidified seawater on growth, nutritional condition, and olfactory sensory of the Asian seabass (Lates calcarifer) larvae’Long term variability of temperature and pH in the Bay of Bengal: an investigation on acoustic perspective
Published 28 May 2026 Science Leave a CommentThis study comprehensively assesses the long-term variability of temperature, ocean acidity changes, and their implications on sound absorption and acoustic propagation in the Bay of Bengal. The analysis reveals a persistent warming trend in the Indian Ocean over the past 50 years, with a significant increase in temperature observed during the Sagar Maitri cruise in 2019. Thermal structure analysis using HadleySST EN4 data indicates warming in the upper 50m but a cooling trend in the 100-200m depth range. Oceanic Heat Content analysis highlights an increasing tendency of heat storage in the upper 50m, indicative of global warming.
In the context of surface ducted propagation, Sonic Layer Depth (SLD) and gradients in the Sound Speed Profile (SSP) were crucial factors influencing acoustic energy behavior. The study revealed a decreasing trend in in-layer gradient (Gr_SL) since 1990, intensifying after that period. The below-layer gradient (Gr_BL) also exhibited a decreasing trend, implying complex dynamics in the sonic layer with potential implications for sound propagation in the surface duct.
The investigation into pH changes spanning 65 years demonstrates a declining trend, particularly since the 1990s, attributed to increased atmospheric CO2 dissolution. The study linked this decrease to anthropogenic activities, aligning with global trends. The analysis of sound absorption illustrated a nonlinear relationship between absorption, frequency, and pH, emphasizing a significant impact of ocean acidification on sound absorption in the Bay of Bengal. The acoustic propagation modeling further highlighted a decrease in transmission loss with reducing pH, leading to increased sound travel and potentially noisier oceans. Salinity variations play a more significant role than temperature in influencing sound absorption.
Continue reading ‘Long term variability of temperature and pH in the Bay of Bengal: an investigation on acoustic perspective’A review of volcanic activity and the evolution of coral reefs
Published 27 May 2026 Science Leave a CommentCoral reefs are among the most extraordinary ecosystems on Earth. They are living structures built by countless tiny polyps, yet they rival tropical rainforests in biodiversity, productivity, and ecological importance. They are subject to global, well-known, nonhuman disturbances, such as intense ocean currents, storm impacts, extreme weather events, climatic variations, disease, and predator outbreaks. They are recognized by the global human society for their care and preservation in a variety of Protected Areas. Coral reefs are also affected by the deleterious effects of diverse human activities, including local activities such as fisheries and tourism, and regional activities such as deforestation – illustrated by the unexpected impact of large logs on the coral crest – agriculture, the oil industry, coastal urban development, river outflow quality and quantity, nutrients, and contaminants. These factors collectively cause a harmful synergistic effect. Additionally, coral reefs are vulnerable to the long-term effects of climate change, including sea level rise, acidification, and high temperatures. Over evolutionary timescales, several forces have shaped coral reefs. For instance, Hamilton et al. [1] note that deforestation on tropical islands releases sediments that travel through rivers into the ocean. These sediments settle into reef crevices, effectively “suffocating” the habitat. Furthermore, this research emphasizes that water quality is degraded not only by land-based runoff (sedimentation) but also by the transport of agricultural nutrients. These nutrients promote macroalgal blooms, which directly compete with coral for space and sunlight. Knowledge of volcanic activity today still focuses on human risk to infrastructure and human life, while attention to potential effects on natural resources remains minimal. For example, Loughlin et al. [2] discuss how risk is calculated based on “Exposure” and “Vulnerability,” traditionally measured by human population density and capital assets.
Continue reading ‘A review of volcanic activity and the evolution of coral reefs’Feeding and excreting ecology in coastal systems
Published 26 May 2026 Science Leave a CommentTags: biological response, community composition, growth, laboratory, mollusks, morphology, mortality, otherprocess, performance, physiology
Oysters (Crassostrea virginica) are critical foundation species in estuaries, providing numerous ecological and economic benefits. However, oyster populations have diminished worldwide. Effective oyster restoration and aquaculture require a mechanistic understanding of the physiological and environmental factors that govern oyster feeding, growth, and resilience under changing coastal conditions. We investigated how oyster ploidy and environmental conditions influenced oyster feeding and investigated how changes in abiotic conditions affected behavioral performance of oyster drills (Stramonita spp.), a key oyster predator. To better understand feeding responses and behaviors of both predator and prey we 1) used in-situ filter feeding assays to determine feeding differences existed amongst diploid and triploid oysters, 2) gathered a baseline for growth and in-situ feeding rates of oysters across Mississippi Sound in the Northern Gulf in the Spring, Summer, and Fall, 3) simulated present-day and projected future pH conditions (7.0-8.8) to analyze oyster feeding responses, and 4) introduced oyster drills to acidified conditions (7.0-8.8) to monitor behavior and foraging rates. Diploid oysters exhibited higher overall feeding rates, yet equivalent absorption efficiency between ploidies demonstrates a difference in energy allocation which might be the key to triploids’ ability to grow quickly. These findings highlight the role of intrinsic genetic and physiological traits in shaping oyster performance and provide a baseline for interpreting responses to environmental variability. Across spatial and seasonal variation in oyster in-situ feeding and growth across three contrasting sites in Mobile Bay and Mississippi Sound, in the Northern Gulf on the western border of Alabama and Mississippi, results revealed strong spatial and seasonal variability in feeding and growth. This was driven primarily by seston composition and salinity. Under present-day and projected future ocean acidification conditions, overall oyster feeding rates declined with lower pH’s, absorption efficiency remained stable, suggesting partial physiological compensation. These results indicate that pH can impose sublethal constraints on energy acquisition and growth, with individual variability at extreme pH highlighting potential acclimation or tolerance thresholds. When subjecting the oyster’s predator, the oyster drill, to similar pH conditions (7.0-8.8) experimental results indicate that decreased pH may increase drill foraging times. Behaviors like inactivity and climbing out of the water indicate a stress response under both high and low pH, demonstrating the complexity of predicting predator-prey outcomes under more acidic conditions. Collectively, these chapters demonstrate that oyster feeding, growth, and survival are shaped by both intrinsic traits, such as ploidy, and extrinsic factors including environmental variability and ocean acidification. Understanding the interplay between physiological plasticity, seston quality, and predator-prey interactions is essential for informing restoration and aquaculture strategies that sustain ecological function and the ecosystem services oysters provide.
Continue reading ‘Feeding and excreting ecology in coastal systems’Demonstration of an automated bioreactor for controlled acid dosing to enhance marine algae productivity
Published 26 May 2026 Science Leave a CommentTags: algae, biological response, fisheries, laboratory, socio-economy
Microalgae are an important feedstock in aquaculture with significant economic potential in generating a diversity of bioproducts. To facilitate expansion of microalgal cultivation, a continuous automated bioreactor that uses waste acid to increase carbon bioavailability in seawater for enhanced biomass production was designed and tested with Tetraselmis suecica UTEX2286. Carbon bioavailability was inferred from culture pH and bioreactor headspace CO2 concentration measurements and controlled via acidification and seawater dilution. Operating over a period of several days, the culture exhibited greater biomass productivity at a pH setpoint of 7-7.5. Outside of this range, algal activity slowed, accompanied by greater CO2 released to the headspace and lower pH during incubation. Increasing the carbon introduced to the bioreactor by increasing the dilution factor did not significantly increase the algal productivity. Importantly, acidification led to statistically significant gains in biomass productivity. Preliminary cost analysis showed while seawater is inexpensive, the acid cost drives the overall cost of the designed bioreactor system. Thus, the designed bioreactor and control scheme supports algal cultivation but requires low-cost acid to be economical, which may be achieved by strategically integrating microalgae cultivation with other coastal industries.
Continue reading ‘Demonstration of an automated bioreactor for controlled acid dosing to enhance marine algae productivity’Microbial communities associated with two populations of the sponge Chondrilla nucula under present and projected climate conditions in the Aegean Sea
Published 25 May 2026 Science Leave a CommentTags: biological response, BRcommunity, community composition, laboratory, Mediterranean, molecular biology, otherprocess, porifera, prokaryotes
This data paper describes bacterial and fungal communities associated with the sponge Chondrilla nucula collected from two Eastern Mediterranean populations (North and South Aegean Sea) and maintained under controlled common-garden conditions simulating present and projected climate scenarios over a period of 3 months. Microbial composition was characterised using two complementary ribosomal marker approaches: Illumina (MiSeq) sequencing of the 16S rRNA gene for Bacteria and Oxford Nanopore (MinION) sequencing of a long 18S-ITS-28S rRNA fragment for Fungi. A total of 24 sponge libraries (3 climate conditions x 2 populations x 4 biological replicates) along with six control libraries (water from three experimental tanks, extraction and PCR blanks) were constructed for each group of microsymbionts. The resulting reads were processed using custom and publicly available bioinformatic pipelines and databases, followed by initial taxonomic assignment. This dataset represents the first fungal community associated with C. nucula and the first bacterial community for this species from the Aegean Sea.
Continue reading ‘Microbial communities associated with two populations of the sponge Chondrilla nucula under present and projected climate conditions in the Aegean Sea’Carbon allocation strategy of Thalassiosira weissflogii in response to elevated pCO2
Published 25 May 2026 Science Leave a CommentTags: adaptation, biological response, laboratory, molecular biology, otherprocess, photosynthesis, physiology, phytoplankton
Diatoms are of significance in the marine ecosystem, playing a pivotal role in the sustenance of marine life and the transfer of carbon from the surface ocean to deeper waters. Although numerous studies have investigated the effects of elevated carbon dioxide (CO2) on marine diatoms across both short- and long-term adaptation scales, the molecular mechanisms governing chitin metabolism in response to ocean acidification remain poorly understood. In this study, we employed an integrated approach combining transcriptomic, metabolomic, and physiological analyses to examine the marine diatom Thalassiosira weissflogii following 40-day acclimation to high-CO2 conditions. Physiological studies have demonstrated that ocean acidification has the capacity to result in an augmentation of the C/N ratio, chitin content, maximum PSII quantum yield (Fv/Fm), and photosynthetic pigment content of T. weissflogii. Analysis of chlorophyll fluorescence dynamics further demonstrated enhanced primary photochemical efficiency of PSII in the acidified treatment group. Consistent with this, the transcriptome results also showed that the photosynthesis-related pathways were upregulated to meet the increased material and energy requirements after adaptation to elevated CO2 levels. More importantly, it was determined that acidification treatment resulted in the upregulation of chitin synthesis and the downregulation of chitin degradation in T. weissflogii, consequently leading to an augmentation in chitin content. These findings indicate that ocean acidification (high CO2, low pH) prompts T. weissflogii to prioritize the allocation of carbon resources to the synthesis of chitin. The synthesis of chitin may reinforce cell wall formation as an adaptive response to ocean acidification. Our research provides new insights into the marine acidification adaptation strategies of T. weissflogii.
Continue reading ‘Carbon allocation strategy of Thalassiosira weissflogii in response to elevated pCO2’Present and future seawater CO2 chemistry across multiple coral reef habitats and scales at Dongsha Atoll and Taiping Island in the South China Sea
Published 22 May 2026 Science Leave a CommentTags: biogeochemistry, chemistry, corals, field, laboratory, North Pacific, sensor
Coral reefs consist of diverse benthic habitats that influence seawater CO2 chemistry variability on multiple spatial and temporal scales. Understanding the present-day seawater CO2 chemistry variability across both habitat-specific and reef-wide scales is critical to accurately predict the effects of future environmental change. Here, we utilize autonomous sensors and discrete seawater samples across diverse habitats at multiple scales ranging from habitat-specific (inner lagoon, patch reefs and seagrass beds; 0.02–0.72km2) to reef-wide scales at Dongsha Atoll (250km2) and Taiping Island (20km2) to characterize seawater chemistry. Across all habitats, daily mean pH ranged from 7.79–8.60 with mean diel variability ranging from 0.19–0.91. Spatially, pH variability ranged from 0.08 (patch reef) to 1.29 (inner lagoon). Biogeochemical modification of seawater chemistry was dominated by organic carbon cycling at individual habitat scales, whereas inorganic carbon cycling dominated at the scale of Dongsha Atoll. The largest alkalinity depletion (net calcification) was associated with patch reef habitats, whereas the highest alkalinity repletion was associated with a semi-enclosed lagoon. Under two climate change scenarios (linear dissolved inorganic carbon increase derived from historical observations and the CMIP6 SSP5-8.5 pathway), pH and/or aragonite saturation state (ΩAr) observations across all habitats in this study are projected to be below proposed thresholds for net reef accretion (pH < 7.7: inner lagoon ~ 10–13%; seagrass beds ~ 21–44%; patch reefs ~ 0–100%; atoll-wide ~ 4–98% of observations) or net dissolution (ΩAr < 2.92: inner lagoon ~ 10–18%; seagrass beds ~ 44–75%; patch reefs ~ 77–100%; atoll-wide ~ 94–100% of observations) by the year 2100. The results highlight the importance of habitat-specific and scale-conscious assessments of future coral reef environmental conditions.
Continue reading ‘Present and future seawater CO2 chemistry across multiple coral reef habitats and scales at Dongsha Atoll and Taiping Island in the South China Sea’Immunosuppression and gill damage of acidification and hypoxia on the Pacific oyster Magallana gigas
Published 22 May 2026 Science Leave a CommentTags: biological response, laboratory, mollusks, mortality, physiology
Highlights
- Combined acidification and hypoxia trigger significant mortality in Magallana gigas.
- Seawater acidification suppresses the nonspecific immune response in Magallana gigas.
- Gill histopathology and immunosuppression are most pronounced with combined exposure.
Abstract
Rising atmospheric carbon dioxide leads to oxygen depletion and increased acidification in marine areas worldwide. The combined effects of these two stressors on the health of commercially important bivalves have not been sufficiently studied. We experimentally studied the effects of water acidification in combination with normoxic and hypoxic conditions on the parameters of cellular immunity and the gills microstructure of the Magallana gigas. We evaluated the hemolymph cellular composition, the total number and phagocytosis capacity of hemocytes, and also evaluated the histopathology of oyster gills during an 8-day experimental period. The oysters were exposed to low pH conditions (7.3), either under normoxic conditions (dissolved oxygen concentration of 8.0 mg/L) or hypoxic conditions (dissolved oxygen concentration of 2.0 mg/L). The parameters were assessed at days 1, 3, 6, and 8 of the experiment. It was shown that acidification of the aquatic environment causes significant suppression of oyster immunity in both normoxia and hypoxia, leading to a decrease in phagocytic capacity and ROS production by hemocytes. The combined effect of these factors increased the negative impact, ultimately leading to the oyster death at the end of the experiment. In addition, the effects of acidification caused serious and progressive histopathological damage to the oyster gills, while the most severe and frequent pathologies, such as almost complete expansion of the water chambers and severe dilation of the hemal sinuses, were caused by the combined effects of acidification and hypoxia. Therefore, the synergistic impact of acidification and hypoxia poses a substantial threat to oyster health.
Continue reading ‘Immunosuppression and gill damage of acidification and hypoxia on the Pacific oyster Magallana gigas’Genome-wide identification and expression analysis of calmodulin and calmodulin-like (CaM and CML) gene family in Magallana gigas
Published 21 May 2026 Science Leave a CommentTags: biological response, laboratory, molecular biology, mollusks
Highlights
- 7 CaM family members and 55 CML family members were identified in Magallana gigas.
- MgCaM and MgCML genes showed tissue-specific and developmental stage-specific expression patterns.
- Distinct expression patterns emerged under heat and acidification stresses.
Abstract
Ca2+ is a multifunctional second messenger that can regulate the activities of hormones and environmental signals related to biotic and abiotic stresses, playing a role in a wide range of cellular processes and influencing almost all aspects of life. In organisms, calmodulin (CaM) and calmodulin-like proteins (CML) can sense and decode the regulatory signals of Ca2+ through the EF-hand (a helix-loop-helix structure) domain. In this study, 7 CaM family members and 55 CML family members were identified in Magallana gigas. All MgCaM and MgCML genes distributed unevenly on 7 chromosomes, with 90% of the genes located on chromosomes 6 and 5. Furthermore, the expression of MgCaMs and MgCMLs was tissue-specific in M. gigas, and most of the genes expressed highly in gill, labial palp, adductor muscle and female gonad. Through the analysis of transcriptome data, it was found that the MgCaM and MgCML genes showed specific expression patterns in response to abiotic stress. When encountering heat-shock stress, different genes responded at different time points. In response to acidification stimulation, genes in the outer edge of mantle could respond to the stimulus obviously. The expression patterns of five representative genes were validated by RT-qPCR under acidification. This study systematically analyzed the characteristics of oyster CaM and CML gene families, revealing their crucial roles in the environmental adaptation mechanisms of M. gigas.
Continue reading ‘Genome-wide identification and expression analysis of calmodulin and calmodulin-like (CaM and CML) gene family in Magallana gigas’Genome-wide characterization of the Pacific oyster Crassostrea gigas SLC4 gene family and expression profiles in response to acidification
Published 20 May 2026 Science Leave a CommentTags: biological response, laboratory, molecular biology, mollusks, reproduction
Highlights
- Eight CgSLC4 genes family members were identified.
- CgSLC4s exhibited tissue-specific and developmentally variable expression patterns.
- CgSLC4 gene family responds to acidification stress in different mantle folds.
- CgSLC4A10-1 shows marked acidification responsiveness, especially in mantle epithelium cell.
Abstract
The solute carrier 4 (SLC4) family represents a category of integral membrane transporters responsible for bicarbonate mediation, which is vital for numerous fundamental biological functions. In this study, eight SLC4 genes were identified and annotated in Crassostrea gigas genome, comprising one member of Cl−/HCO3− exchanger, five genes coding Na+-dependent HCO3− transporters, and two Na+-coupled borate transporter copies, which were located on three chromosomes. In general, the expression of CgSLC4s showed tissue specificity, and differential expression patterns of CgSLC4s was observed at different developmental stages. The CgSLC4 family genes displayed divergent responses to acidification across different mantle folds. Among these family members, CgSLC4A10-1 exhibited the most dramatic and statistically significant expression changes in response to acidification across mantle folds, with fold changes ranging from 0.008-fold down-regulation to 85.95-fold up-regulation. According to the results of RT-qPCR and immunofluorescence, after 14 days of acidification treatment, CgSLC4A10-1 mRNA expression level was significantly increased, immunoblotting signal intensity was also enhanced in the epithelial cells. These results provide a general characterization of the SLC4 gene family in C. gigas, which may provide a systematic overview of the SLC4 gene family in C. gigas, and lay a foundation for future studies to explore its potential involvement in ion homeostasis and acidification adaptation in bivalve mollusks.
Continue reading ‘Genome-wide characterization of the Pacific oyster Crassostrea gigas SLC4 gene family and expression profiles in response to acidification’Ca C code for Stable Ca and Sr isotope responses to ocean acidification during Oceanic Anoxic Event 2
Published 20 May 2026 Science Leave a CommentTags: chemistry, paleo
Ca – C model for Stable Ca and Sr isotope responses to ocean acidification during Oceanic Anoxic Event 2 published in Chemical Geology.
Continue reading ‘Ca C code for Stable Ca and Sr isotope responses to ocean acidification during Oceanic Anoxic Event 2’Stable Ca and Sr isotope responses to ocean acidification during Oceanic Anoxic Event 2
Published 20 May 2026 Science Leave a CommentTags: chemistry, paleo
Volcanism-driven ocean acidification has repeatedly disrupted Earth’s carbon cycle and ecosystems. Calcium isotopes (δ44/40Ca) provide a potential means of tracking these perturbations, since both the weathering and burial of CaCO3 and the isotopic compositions associated with these fluxes are sensitive to changes in seawater pH. However, the use of δ44/40Ca to reconstruct acidification and infer biocalcification stress is often complicated from overprinting by diagenetic processes. In this paper, we investigate stable Ca (δ44/40Ca) and Sr (δ88/86Sr) isotope responses to ocean acidification during Oceanic Anoxic Event 2 (OAE 2) in a pelagic marine carbonate succession from the Western Interior Seaway. The records are reconstructed using the Iona-1 core in Texas, which fully captures Os isotope evidence for the onset of LIP volcanism that is missing from a previously published Ca isotope record in the Western Interior Seaway in Colorado. Here we show that a negative Ca isotope excursion occupies the missing part of the previously published Western Interior Seaway record, and that it the begins with the onset of large igneous province volcanism as represented by the abrupt shift to lower initial 187Os/188Os isotopic ratios in the core. Box-model simulations show that the negative Ca isotope excursion could be produced through reduced Ca isotope fractionation affecting pelagic carbonate production under conditions of transient acidification stress, followed by rapid recovery through carbonate alkalinity feedback. δ88/86Sr values broadly covary with δ44/40Ca values but deviate from the expected kinetic slope, instead defining a mixing array consistent with seawater-buffered recrystallization. Together, the coupled stable Ca-Sr isotope systematics distinguishes primary acidification-driven signals from diagenetic modification and demonstrate the utility of dual-isotope approaches for tracing volcanism-induced perturbations to the marine carbon cycle.
Continue reading ‘Stable Ca and Sr isotope responses to ocean acidification during Oceanic Anoxic Event 2’Impacts of coinciding ocean acidification and warming on the fatty acid profile of the pteropod Limacina helicina within the Northeast Pacific coastal region
Published 19 May 2026 Science Leave a CommentTags: biological response, laboratory, mollusks, mortality, North Pacific, physiology
Under global climate change, co-occurrence of ocean acidification (OA) and warming poses a substantial threat to marine ecosystems. The present study focused on the Strait of Georgia within the Northeast Pacific region, where conditions of aragonite undersaturation exist year-round across the majority of the water column, with further intensification expected under OA. These conditions coincide with persistent rises in mean seasonal seawater temperatures and increased prevalence of acute stressor events, such as marine heatwaves and low-pH upwelling events. Limacina helicina, a pteropod species well-represented within the region’s zooplankton communities, is susceptible to OA and warming, with documented impacts including altered shell development, growth, and survival. To date, however, there has been minimal investigation into the effects of OA and warming on the species’ fatty acid profile under regionally-relevant conditions, thereby contributing to a lack of understanding of how impacts at lower trophic levels may relay across ecosystems. To address this knowledge gap, we examined the survival and fatty acid profile of L. helicina under future conditions via a laboratory experiment during which pteropods were exposed to singular and coinciding warming (mean summer seawater temperature + 4 °C) and OA (Ωarag < 1) conditions, with fatty acid analyses carried out via gas chromatography at 48-h and 5-d timepoints. OA conditions significantly altered fatty acid proportions at 48 h, and there was an additional interactive effect of OA and warming. Temperature significantly affected survival at 5 d, although experimental starvation conditions likely confounded this result. Additionally, fatty acid analyses of L. helicina picked from historical plankton samples collected in the region over 2014–2023 were carried out to examine time-series changes in fatty acid profiles in relation to temperature records. Results indicated no significant differences in fatty acid fractions among years, though there was suggestion of a changing proportion of myristic acid over a number of year groups. Overall, findings suggest that short-term OA conditions may result in altered fatty acid composition in pteropods, potentially leading to shifts in nutritional quality and associated impacts on trophic energy transfer.
Continue reading ‘Impacts of coinciding ocean acidification and warming on the fatty acid profile of the pteropod Limacina helicina within the Northeast Pacific coastal region’
