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 Comment

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.

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Acidification of brackish, fresh, and seawater by bipolar membrane electrodialysis: impact of composition on kinetics and energy consumption

Published 20 May 2026 Science Leave a Comment

Highlights

  • Higher salinity and applied voltage accelerated acidification kinetics.
  • Buffer capacity (HCO3−) negatively impacted acidification kinetics.
  • Non-ideal membrane permselectivity allowed considerable transport of co-ions.
  • Natural waters of low conductivity showed lower SEC during acidification.

Abstract

Anthropogenic CO2 emissions have reached unprecedented levels, where approximately 30% is absorbed by aquatic systems. This study investigated the acidification of natural waters using bipolar membrane electrodialysis (BPMED), a crucial step in the extraction of CO2 from water, i.e., key Carbon Dioxide Removal (CDR) technology. Natural waters of different salinity and bicarbonate concentration were selected: seawater (51.2 mS/cm, 140 mg/L HCO3−), brackish groundwater (5.4 mS/cm, 290 mg/L HCO3−), and surface freshwater (0.4 mS/cm, 162 mg/L HCO3−), where BPMED shifted the carbonate equilibrium toward H2CO3/CO2(aq), which could be subsequently extracted, thus making the current approach sustainable. The influence of applied voltage, the acidified:basified volume ratio, and hydrochemical composition on acidification kinetics, energy consumption, and ion transport was analyzed. Results showed that higher salinity and applied voltage accelerated acidification kinetics, whereas buffer capacity (HCO3−) slowed down the acidification process. In addition, waters with lower salinity required lower specific energy (1.02 vs 1.86 kWh/kg CO2 for freshwater and seawater, respectively) to achieve acidification (final pH 4), while increasing the acidified:basified volume ratio led to higher energy consumption. Acidified water exhibited increased Na+ and Cl− concentrations, while K+ and HCO3− decreased across all water sources. These findings contribute to the scientific understanding of electrochemically-based water acidification processes and provide insights into sustainable approaches for managing dissolved CO2 in natural waters.

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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 Comment
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Ca – C model for Stable Ca and Sr isotope responses to ocean acidification during Oceanic Anoxic Event 2 published in Chemical Geology.

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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 Comment
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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.

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PhD opportunity: carbonate chemistry and alkalinity dynamics in the coastal ocean (chemical oceanography/biogeochemistry)

Published 19 May 2026 Jobs Leave a Comment

Employer: University of Otago

The Department of Marine Science was established in 1992, but we have a long history of marine research and teaching at the University of Otago. We are a multidisciplinary department with research strengths across the spectrum of marine sciences. We host the ESNZ national carbonate chemistry facilities. Information about the Department of Marine Science, its staff, current teaching and research, can be obtained from http://www.otago.ac.nz/marinescience.

Earth Sciences New Zealand (ESNZ) is a Crown Research Institute in New Zealand. It specializes in environmental research and consultancy in water, atmospheric, and marine sciences. Established in 1992, ESNZ focuses on providing scientific knowledge and solutions for environmental management, sustainable resource use, and understanding climate and weather patterns. Its work supports decision-making in areas such as climate change, biodiversity conservation, water quality, and natural hazard resilience. ESNZ operates specialized computing facilities, research vessels, atmospheric monitoring facilities, and a network of environmental monitoring stations across New Zealand. Further information about ESNZ is available from Earth Sciences New Zealand.

Homepage: https://www.otago.ac.nz/marinescience

About the project

The Department of Marine Science at the University of Otago (Aotearoa New Zealand) and Earth Sciences New Zealand (ESNZ) seek applicants for a PhD study on coastal ocean alkalinity dynamics to start August 2026 or soon thereafter.

We are looking for a motivated PhD candidate to work within the broader ‘Catching Marine Carbon: testing ocean solutions for climate mitigation using natural analogues’ project, which aims to develop a monitoring, reporting, and verification framework for marine carbon dioxide removal technologies within Aotearoa. Alkalinity determines how much carbon dioxide can be stored in the ocean, yet the alkalinity sources to the ocean and how these sources change with environmental changes (e.g. ocean acidification, ocean alkalinity enhancement) are poorly constrained. The candidate’s role is to apply measurements of stable carbon isotopes to advance our understanding of carbonate chemistry dynamics in the ocean.

About the position

This PhD project will focus on the use of stable carbon isotope (13C) measurements for studying marine carbonate chemistry. The successful candidate will regularly participate in research cruises on the east Otago shelf and occasionally in other coastal areas around Aotearoa, collect and process seawater samples, and determine carbonate chemistry parameters and their isotope signatures.

We seek a candidate with a background in marine science, biogeochemistry, physics, or related fields.

The selected candidate will be jointly supervised by Dr. Christina McGraw and Dr. Sebastiaan van de Velde.

  • You are highly motivated to conduct research within an international and interdisciplinary team of researchers, and thus build a professional network and academic career;
  • You will perform fundamental research within the domain of marine biogeochemistry and chemical oceanography;
  • You prepare and participate regularly in sampling campaigns at sea.
  • You have a strong interest in marine biogeochemistry;
  • You are willing to participate in research cruises with lengths of a few days to a few months;

Profile and qualifications

We are looking for a flexible and creative person, who is highly motivated to tackle new and complex questions at the interface between physics and geochemistry.

  • You hold a masters (MSc) and/or BSc (Hons) degree – or are expected to have one before the starting date of the position – in marine science, biogeochemistry, physics, or a related discipline in the Natural Sciences, and have a strong interest in cross-disciplinary research;
  • Candidates who have experience with carbonate system and/or isotopic measurements are particularly encouraged to apply.
  • You are creative, possess excellent organisational skills, and have a cooperative mindset;
  • You are an excellent team player, and enthusiastic to learn new technologies;
  • An international candidate (i.e., non-NZ or non-Australian) will be required to apply for an NZ student visa to be allowed to study in NZ.
  • Where English is not an applicant’s first or native language, evidence of English language proficiency that meets the requirements for Postgraduate Study at the University of Otago (https://www.otago.ac.nz/study/entry-requirements/language-requirements) will be required.

We offer

  • A fully funded 3-year PhD scholarship, which includes a tax-free stipend / scholarship of NZ$35,000 per year and a full university tuition fee waiver;
  • An interdisciplinary work environment in the ‘Centre for Oceanography’ which combines experts from both Earth Sciences New Zealand and the University of Otago;
  • Access to state-of-the-art carbonate chemistry analytical facilities, including the capacity to analyze 13C isotopes from solid and dissolved carbonates;
  • Access to a marine field station equipped with experimental facilities, including climate-controlled rooms;
  • Opportunities to participate in sea-going expeditions;

Want to apply?

  • Applications should be sent by email to sebastiaan.vandevelde@otago.ac.nz(subject: candidature RP-PhD) and should include
    • a cover letter specifying the motivation to apply for the position (max. 2 pages)
    • a short CV, including an abstract of the thesis
    • a copy of your academic transcripts
    • contact details of 2 referees
  • The position will remain open until it is filled
  • Shortlisted candidates will be invited for an interview
  • For informal inquiries, please contact Dr. Sebastiaan van de Velde (sebastiaan.vandevelde@otago.ac.nz)
Continue reading ‘PhD opportunity: carbonate chemistry and alkalinity dynamics in the coastal ocean (chemical oceanography/biogeochemistry)’

Call for four new members of the IOCCP Scientific Steering Group

Published 19 May 2026 Jobs Leave a Comment

Application deadline: 15 June 2026

We are excited to invite you to join the IOCCP Scientific Steering Group!!!

We are looking for four new members to join us for terms beginning on 1 October 2026, to act as leaders responsible for Data and Information Access Services (Position #1), Coordination of Regional Ocean Biogeochemical Observations in South East Asia (Position #2), Coordination of Oxygen Essential Ocean Variable (Position #3), Coordination of activities related to Instruments and Sensors and Technical Training Workshops (Position #4).

To make inquiries and/or to submit your application for one of the positions, please contact the IOCCP Project Office (ioccp@ioccp.org), by 15 June 2026. For more details, read below or download the attached full announcement. Please share with your networks and potentially interested individuals.

The International Ocean Carbon Coordination Project (IOCCP), a program of the Scientific Committee on Oceanic Research (SCOR) and the Intergovernmental Oceanographic Commission (IOC) of UNESCO, is looking for four experts to join its Scientific Steering Group (SSG) for term beginning on 1 October 2026. New SSG members will replace colleagues rotating off from the Panel at the end of 2026, and will be expected to develop and expand a comprehensive and effective set of coordination activities within specific IOCCP Themes, as linked to each Position description below. Moreover, we seek to expand our SSG composition to: (i) better address the needs for coordination in regions currently underrepresented at the IOCCP SSG, especially in the Southern Hemisphere, and (ii) promote outstanding early-career ocean professionals willing to support IOCCP’s mission.

The IOCCP SSG is responsible for development and implementation of activities mandated by the IOCCP Terms of Reference. Acting as focal points for Thematic communities, the SSG members are expected to promote the development of a global network of ocean carbon and biogeochemistry observations, coordinate the development of globally acceptable strategies, and provide technical coordination developing operating methodologies, practices and standards, homogenizing efforts of the research community and scientific advisory groups. In our activities we define biogeochemistry as including the Global Ocean Observing System (GOOS) Essential Ocean Variables (EOVs) for Biogeochemistry. These EOVs enable the understanding and quantification of several phenomena prioritised by the integrated Global Ocean Observing System. The role of the SSG is also to ensure delivery of communication services for the marine biogeochemistry community as well as advocacy and links to a multidisciplinary sustained global ocean observing system.

SSG members serve for a period of three years, with the potential of renewing for an additional 3-year term. Among other things, SSG members are asked to:

  • Gather, share, and act upon the international community needs regarding the IOCCP Theme they are responsible for.
  • Work with the IOCCP Office and members of the community to develop, coordinate, and implement specific activities.
  • Represent IOCCP, particularly in their area of expertise, at international meetings and workshops, and report back to the SSG and the Project Office on relevant actionable outcomes of these meetings.
  • Encourage national and international funding agencies to support existing and newly developed activities.
  • Encourage coordination of efforts and collaboration with organisations and projects involved in marine biogeochemistry observations.
    IOCCP SSG meets once a year in-person, and three times a year remotely. The expected time commitment for IOCCP activities is on average 1-3 days per month, which might occasionally accumulate around specific activities. More information about the current SSG is available at: IOCCP Scientific Steering Group.

IOCCP SSG meets once a year in-person, and three times a year remotely. The expected time commitment for IOCCP activities is on average 1-3 days per month, which might occasionally accumulate around specific activities. More information about the current SSG is available at: IOCCP Scientific Steering Group.

In this call we seek to fill four IOCCP SSG positions described below. The responsibilities of newly appointed SSG members will include the following IOCCP activities: 

Position #1: Coordination of Data and Information Access Services

Continue reading ‘Call for four new members of the IOCCP Scientific Steering Group’

Changes in salinity impact nitrogen removal and carbon preservation in coastal wetlands sediment

Published 18 May 2026 Science Leave a Comment
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Highlights

  • Coastal freshening suppressed N removal via denitrification while accelerating net organic carbon mineralization.
  • Salinity shaped N removal vs. N retention and carbonate vs. alkalinity balance through sulfate availability.
  • Salinity changes had concurrent implications for coastal eutrophication and ocean acidification.

Abstract

Coastal wetlands naturally remediate nitrogen (N) pollution through microbial pathways that either remove reactive N via denitrification and anammox, or retain it via dissimilatory nitrate reduction to ammonium (DNRA). The balance among three processes is closely linked to the carbon (C) cycle, as both heterotrophic denitrification and DNRA consume organic C and release alkalinity. While salinity fluctuations can disrupt these processes through direct ionic stress or sulfur (S) cycling, their net impact on N removal and C preservation services remains unclear. Here, we deployed microcosm experiments using mangrove sediments under a large salinity gradient (0-30 psu). We quantified N transformation rates using 15N isotope tracing technique, combined with geochemical analysis, and functional genes quantification. Freshening from ambient 30 psu to 10 psμ decreased N removal efficiency by ∼20%. This decline was caused by reduced denitrification, whereas anammox and DNRA were unaffected. Meanwhile, lower salinity appears to have stimulated C decomposition via reduced ionic stress. The reduced sulfate input diminished total alkalinity (TA) generation relative to dissolved inorganic carbon (DIC). The stoichiometric shift of TA:DIC ratio could further contribute to acidification in adjacent coastal waters. Additionally, the S-mediated regulation of N partitioning appears to be nitrate-dependent: under nitrate limitation, higher sulfate favored N retention; conversely, with enriched nitrate, it potentially favored N removal. Integrating the coupling effect of salinity on interaction between N, C and S cycles, our study demonstrates that coastal water freshening may weaken wetlands’ ability to remove N and preserve C.

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Ocean acidification, more than warming or heatwaves, constrains shoaling behaviour in a range-extending fish through habitat simplification

Published 18 May 2026 Science Leave a Comment
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  1. Social context is a critical yet underexplored determinant of behavioural resilience to climate change. Group living can buffer individuals against environmental stress through enhanced vigilance, reduced predation risk and improved foraging efficiency.
  2. However, whether these behavioural expressions persist under chronic (warming, acidification) and acute (marine heatwaves) climate stressors remains unclear. Using natural climate analogues spanning present-day, ocean warming and combined warming–acidification reefs, we quantified how shoal size influences behavioural expression in a range-extending reef fish (Pomacentrus coelestis).
  3. Across all climate conditions, fish in larger shoals consistently exhibited higher foraging and activity levels and reduced risk-avoidance behaviours, whereas direct effects of warming, acidification and heatwaves on behaviour were negligible.
  4. In contrast, ocean acidification most likely constrained collective behaviour indirectly by simplifying benthic habitats, where fish densities were 84% lower than at the warming reef, resulting in shoals that were up to 79% smaller than the Warming and Control reefs.
  5. Combined, our data suggest that shoal size mediates behavioural expression between foraging and predator avoidance and that acidification-driven habitat simplification can alter behavioural expression indirectly by reducing fish densities and the formation of large shoals.
  6. We conclude that climate change can indirectly modify behavioural expression in shoal-forming fishes through habitat-driven erosion of social structure.
Continue reading ‘Ocean acidification, more than warming or heatwaves, constrains shoaling behaviour in a range-extending fish through habitat simplification’

Impacts of ocean acidification and warming (OAW) on abalone growth and reproduction: a dynamic energy budget model approach across SSP scenarios

Published 18 May 2026 Science Leave a Comment
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Ocean acidification and warming (OAW) are expected to alter physiology, growth and reproduction of marine ectotherms, yet their combined effects on life-history traits remain unresolved, particularly under poorly defined future food conditions. Using a Dynamic Energy Budget (DEB) model, we investigated how interacting changes in temperature, seawater pH, and food quality may shape somatic growth and reproductive phenology of the European abalone Haliotis tuberculata across four contrasting coastal environments and three Shared Socioeconomic Pathway (SSP) climate scenarios. OAW effects were modeled as increased metabolic maintenance costs, while reduced food quality, driven by OAW, lowered assimilation efficiency, aligning with experimentally-supported limited compensatory feeding.,Our results reveal that warming and food quality strongly drive somatic growth, whit ocean acidification playing a minor role within the modeled range. Food quality remained the primary determinant of maximum body size, while warming amplified growth across all locations, with the largest proportional increases in cooler northern bays. Individuals in the warmest areas remained the largest across scenarios within the model framework. Reproductive timing also shifted consistently, with first spawning occurring markedly earlier under end-of-century conditions, advancing consistently with scenario intensity. Food quality modulated reproductive investment but had weaker effects on the timing of first spawning., These findings highlight that food quality critically mediates organismal responses to OAW and can offset temperature-driven gains in growth and reproduction. By combining expected nutritional constraints with SSP scenarios, our DEB-based approach provide mechanistic insights into the future responses of benthic marine invertebrates to climate change, highlighting the value of these scenario-based projections for better management strategies.

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BMSC and partners receive CRBS grant

Published 18 May 2026 Web sites and blogs Leave a Comment

We are excited to spread the word that BMSC and our partner and neighbor, Nova Harvest, along with the Hakai Institute and the BC Shellfish Growers Association, have received one of the CRBS (Climate Ready BC Seafood) Program Grants! This grant provided funds for research that helps understand the impacts of ocean acidification and hypoxia on the province’s seafood so that we can mitigate the issues and improve the resiliency of organisms that we rely on for food.

The partners are using various ocean observing instruments,  such as the Burke-o-later, to monitor ocean parameters in sea water. This monitoring allows for both research on how shellfish respond to changes and as a daily monitoring tool. Having this live data allows the team to react in real-time, improving the survival of and production of shellfish. 

Watch the video to learn more about the project

Ocean acidification and hypoxia threaten British Columbia’s coastal food security. This short documentary highlights some of the 11 projects funded by a $2M funding envelope provided by the Province of British Columbia to create the Climate Ready BC Seafood Program. Learn more about how these groups are working to further our understand the impacts of ocean acidification and hypoxia in BC to provide knowledge for mitigation and adaptation that supports enhancing the resiliency of BC’s seafood.

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Large-scale atmospheric circulation and its impact on the Baltic Sea region: controls, predictability and consequences

Published 15 May 2026 Science Leave a Comment
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Large-scale Euro-Atlantic variability, shaped by the polar jet stream, governs weather and climate in the Baltic Sea region, thereby impacting the physical and biogeochemical properties of the Baltic Sea ecosystem. This review synthesizes how key atmospheric circulation features and modes of climate variability, including the North Atlantic Oscillation, atmospheric blocking and the Atlantic Multidecadal Variability, influence the Baltic Sea region. By integrating evidence from the published literature, observational datasets, and both global and regional climate model simulations, we assess established as well as potential linkages to key climatic variables, including temperature, precipitation, and storm activity, across temporal scales ranging from synoptic events to multidecadal variability. We then evaluate how these climate controls cascade into ecosystem-relevant processes, namely oxygen dynamics, primary productivity and ocean acidification. Although physical links are already established, the pathways connecting large-scale atmospheric patterns to biogeochemistry are still poorly constrained, partly because dedicated field studies and targeted model experiments are limited. We outline priority research needs to enhance near-term predictability and reduce uncertainty in future projections for the Baltic Sea.

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Extending planktic foraminiferal Mg/Ca palaeothermometry into polar temperature ranges: crust- and lamellae specific calibrations and non-thermal controls

Published 15 May 2026 Science Leave a Comment
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The rapidity of climate change in the polar regions underscores the need for improved understanding of its impacts on ocean circulation at both regional and global scales. Reconstructions of past polar ocean-cryosphere interactions can provide this context, but large uncertainties in existing proxies limit the utility of such studies. For instance, there are currently no low-temperature (<9 °C) culture-based Mg/Ca-calibrations for planktic foraminifera, a key tool for reconstructing past changes in ocean temperatures. There is also limited understanding of non-thermal influences on Mg/Ca in Neogloboquadrina pachyderma, the only modern polar planktic foraminifera. Moreover, this species exhibits considerable levels of heterogeneity in composition precipitating a thick lower-Mg/Ca outer crust over higher Mg/Ca inner lamellae calcite; specimens with predominantly, albeit variable crust–lamellae proportions, are thus thought to introduce substantial uncertainty into high-latitude palaeotemperature reconstructions. Here, we used N. pachyderma cultured across a range of temperatures, salinities, and carbonate chemistry conditions including experiments in which pH and [CO32-] either covaried or were decoupled. By using a laser ablation approach to analyse crust and lamellae separately, we present new Mg/Ca-temperature calibrations for each component that extend culture-based calibrations in N. pachyderma down to the lower temperature-range (2–9 °C). The crust-specific calibration is of particular importance in high-latitude downcore records where N. pachyderma are commonly observed to preserve predominantly or only crust. Our results show significant carbonate chemistry influence on Mg/Ca with opposite influences from pH and carbonate ion concentration, when these variables changed in isolation. Additionally, we show that environmental conditions regulate crust-lamellar proportions, where increased salinity and temperature, and lower pH lead to less crust formation with implications for future ocean acidification and Arctic Atlantification, and for downcore reconstructions.

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Newly discovered microbial world helps protect developing lobsters

Published 15 May 2026 Press releases Leave a Comment

As ocean temperatures rise and marine ecosystems change, scientists are working to understand how valuable species like the American lobster will respond. New research from William & Mary’s Batten School of Coastal & Marine Sciences & VIMS suggests one source of resilience may come from the microscopic bacterial communities living on lobster embryos.

The study, published in Scientific Reports, found that lobster eggs host surprisingly diverse microbiomes that change as the embryos develop but otherwise remain remarkably stable even under conditions simulating future environmental conditions. The findings challenge decades of assumptions that lobster eggs contained only a few key bacterial species and could help scientists better understand disease risks in one of North America’s most valuable fisheries.

“We were hoping to discover one dominant microbe early on,” said study coauthor Jeffrey Shields, a professor at the Batten School & VIMS who collaborated with several of his students on the research, including lead author Sarah Koshak. “Instead, it was a mishmash, a rich community of different bacteria whose roles we don’t yet fully understand.”

The exterior surface of a late-stage lobster embryo covered by filamentous bacteria at 400x magnification.Credit: Jeffrey Shields.

A hidden ecosystem on lobster eggs

Using advanced genetic sequencing techniques, researchers analyzed microbial communities on lobster embryos and newly hatched larvae raised under varying temperatures and pH conditions designed to mimic present-day and future ocean conditions in the Gulf of Maine.

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High-resolution temporal biogeochemical variations in a seagrass-coral cohabitate ecosystem: day-night, rain, and coral spawning

Published 14 May 2026 Science Leave a Comment
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Highlights

  • Seagrass-coral habitats act as CO2 sources driven by intense nighttime respiration
  • High-resolution data enable predictive modeling of DIC, DOC, and POC dynamics
  • Metabolic cues govern DIC, while temperature and alkalinity regulate POC and DOC
  • Episodic coral spawning and rainfall trigger rapid ocean acidification
  • Short-term disturbances dramatically shift organic and inorganic nutrient loads

Abstract

Seagrass meadows and coral reefs are global hotspots for productivity, yet they are often studied in isolation despite their intense biogeochemical connectivity. Significant gaps remain in understanding how coupled inorganic and organic processes within the water column drive blue carbon services in such mixed habitats, particularly during rapid environmental disturbances. Here, we investigated a unique, intertwined ecosystem in the Dongsha Atoll, where massive Porites corals are distributed on seagrass meadows, creating a natural laboratory for studying water column carbon biogeochemistry. During a 10-day sampling period, we collected continuous hydrological and discrete biogeochemical data at two- to four-hour intervals. Our results reveal that the dissolved inorganic carbon (DIC) covaried with dissolved oxygen and pH in strong diurnal patterns, which were governed by photosynthesis and respiration. As an outcome, variable but mostly high pCO2 values (141–2070 μatm) indicate the seagrass meadow was a source of CO2 to the atmosphere due to strong night-time respiration. Particulate organic carbon (POC) increased with temperature but showed no diurnal pattern. Dissolved organic carbon (DOC) showed a weak diurnal pattern and was linked to variations in POC and total alkalinity, highlighting the tight coupling between the organic production of the meadow and the inorganic chemistry of the calcification framework. Additionally, coral spawning led to a surge in organic content and changed inorganic nutrient levels. Rainfall events significantly acidified the ocean and enhanced submarine groundwater discharge to the seagrass-coral habitat. The distinctive contributions of this study are the extremely high temporal resolution of discrete samples, allowing the simultaneous tracking of multiple organic and inorganic pools during natural disturbances. The high-resolution data provide fundamental information for parametrizing models that explain DIC, POC, and DOC, which yield insights into organic carbon cycling in seagrass meadow-coral habitats.

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Mechanistic drivers of climate-induced reproductive collapse in African catfish: multi-stressor interactions under IPCC scenarios

Published 14 May 2026 Science Leave a Comment
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Climate change is increasingly disrupting freshwater ecosystems in sub-Saharan Africa, posing severe threats to the reproductive success and population viability of key fish species. This study investigated the mechanistic effects of elevated temperature across a gradient and the combined impact of elevated temperature, acidification and hypoxia under a simulated future climate scenario (IPCC SSP5-8.5) on the reproductive physiology and early life stages of Clarias gariepinus in the Cross River Estuary. Single-stressor trials examined the effect of temperature (28–38°C) on oestrogen synthesis, cortisol levels and gonadosomatic index (GSI). A combined-stressor scenario (35°C, pH 6.2, dissolved oxygen 2 mg/L) was used to simulate predicted climate conditions. Each treatment was replicated across triplicate tanks, with 10 broodstock per tank, over an 8-week period. Environmental parameters were tightly controlled using aquarium heaters, aerators and pH regulators. Combined stressors markedly disrupted reproductive function. Oestrogen synthesis ceased at 34°C, coinciding with a sharp decline in GSI (r2 = 0.81, p < 0.001). Cortisol concentrations increased fourfold under concurrent heat and hypoxia. Cortisol concentrations increased fourfold under heat and hypoxia co-stress. Larval performance also declined sharply, with prey capture efficiency reduced by 33% at pH 6.0 and cumulative mortality reaching 82% by day 5 under combined-stressor conditions. Habitat suitability models projected a 71% reduction in spawning habitat availability in the estuary by 2070 under the SSP5-8.5 scenario. Genetic screening revealed a significant correlation (r2 = 0.63, p = 0.004) between heat shock protein 70 (HSP70) allele frequency and larval survival, indicating potential for adaptive resilience. These findings suggest a compounded vulnerability of C. gariepinus to climate-related stressors and highlight the potential need for targeted conservation efforts. Recommended interventions include habitat restoration, enhancement of dissolved oxygen regimes and selective breeding programmes to support thermal and hypoxic tolerance in vulnerable populations.

Continue reading ‘Mechanistic drivers of climate-induced reproductive collapse in African catfish: multi-stressor interactions under IPCC scenarios’

Understanding natural ecosystems: biogeochemical modelling

Published 14 May 2026 Web sites and blogs Leave a Comment

Why do we study ocean biogeochemistry?

The ocean has a huge and diverse range of ecosystems, from shallow coastal waters to the vast open sea and the deep seafloor. Each one supports life that’s adapted to its own specific environment and food webs. Ultimately, at the base of almost all marine ecosystems are tiny, microscopic organisms: the phytoplankton.

Why Does the Ocean’s Carbon Cycle Matter?

The ocean plays a dominant role in the Earth’s carbon cycle. It holds more than 90% of the planet’s carbon and absorbs around 25% of our carbon dioxide (CO₂) emissions. This uptake reduces the amount of CO₂ left in the atmosphere to cause climate warming. Understanding how the ocean’s carbon cycle works is a critically important area of research.

Marine ecosystems play a significant part in the ocean’s natural carbon cycle by transporting carbon from the surface to the deep ocean. This process is known as the “biological carbon pump” (BCP). However, climate-driven changes in ocean temperature, circulation, and mixing are expected to reduce the supply of deep nutrients that fuel the BCP. This may disrupt its vital role in storing carbon.”

How Does Ocean Biogeochemistry Affect Human Communities?

Focusing more directly on human concerns, marine productivity is ultimately what provides us with resources like fisheries. Marine ecosystems support global fisheries, which collectively employ 62 million people and feed about 3.2 billion, sustaining regional economies.

In coastal areas, seaweeds provide ecosystem services like pollution remediation and have a natural value we can all appreciate. On top of that, the wider ocean carbon cycle could potentially be leveraged by marine carbon dioxide removal (mCDR) technologies. These aim to remove CO₂ from the atmosphere and eventually help reduce the extent of climate warming.

So, studying how marine ecosystems operate, and how they might change, is a major goal for our ecosystems modelling group.

What is MEDUSA?

MEDUSA (Model of Ecosystem Dynamics, nutrient Utilisation, Sequestration and Acidification) describes the surface ocean ecosystem with a simple, size-based model (nutrient-phytoplankton-zooplankton-detritus). It simulates the linked biogeochemical cycles of carbon, nitrogen, silicon, iron, and oxygen. We use MEDUSA in detailed, high-resolution simulations to help understand how human systems, including fisheries, may change in the future.

MEDUSA is typically run inside physical models of the ocean. This means its components respond to properties like temperature and salinity, and are transported around the ocean by currents. We can then compare the geographical and seasonal output from our models with observational data from ships, autonomous platforms, or satellites. This helps us work out how good a job the model is doing and how we can improve it.

Visit the MEDUSA website

How Does MEDUSA Contribute to Climate Research?

An important part of our work comes from MEDUSA serving as the marine biogeochemistry component of the UK’s state-of-the-art Earth system model, UKESM. Through UKESM, MEDUSA contributes to the international climate simulations that inform the Intergovernmental Panel on Climate Change (IPCC) Assessment Reports. This helps improve our global understanding of how the ocean influences climate.

Using UKESM also allows our group to better study the links between marine ecosystems and the wider atmosphere and land systems. This integrated approach lets us examine how changes in one part of the Earth system cascade through to affect others.

Why is the Research Important for the Future?

Ocean biogeochemistry is important for understanding the ocean’s carbon cycle and its ecosystems, so crucial for both tackling global-scale challenges such as climate change and knowing how we can mitigate these or adapt to them.

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Anti-predatory responses of Mytilus coruscus to the combined effects of ocean acidification and microplastics

Published 13 May 2026 Science Leave a Comment
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Highlights

  • 1.Predator cues can significantly induce byssal secretion in Mytilus coruscus.
  • 2.Ocean acidification inhibits the anti-predatory responses of Mytilus coruscus.
  • 3.Microplastics exerts sublethal effects on the byssus of Mytilus coruscus.
  • 4.The presence of predators amplifies the mild disturbances caused by ocean acidification and microplastics.
  • 5.The combined stress shows a synergistic inhibitory trend on the anti-predatory capability of Mytilus coruscus.

Abstract

Ocean acidification (OA) and microplastics (MPs) pollution are major abiotic stressors in coastal ecosystems. Byssus is the core structural trait for Mytilus coruscus to defend against predators, and it is vulnerable to environmental stress, which in turn impairs its anti-predator function. However, the anti-predator response characteristics of M. coruscus byssus and the interaction mechanisms among OA, MPs and predation pressure from Charybdis japonica remain unclear under their combined stress. The study conducted acute exposure experiments, measuring five key byssus indicators: secretion frequency, quantity, diameter, volume and tensile strength, to explore the variation characteristics of the byssus-based anti-predator function of M. coruscus under multi-stressor conditions. Results showed that predators served as a key biological signal to trigger the anti-predator responses and significantly promoted byssus secretion; OA had the most prominent inhibitory effect on byssus function; MPs exposure only induced sublethal disturbances with no significant effects on core anti-predator indicators. Furthermore, the combined stress of ocean acidification and microplastics exhibited a synergistic trend, impairing the byssus-centered anti-predatory defense capacity of M. coruscus. This study provides experimental evidence for analyzing the variation patterns of mussel byssus under multiple stressors and suggests that future marine ecological risk assessments should focus on the interactions between biotic and abiotic stressors to more accurately predict the dynamic changes of coastal ecosystems.

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OA-ICC bibliographic database updated

Published 12 May 2026 Science Leave a Comment

An updated version of the OA-ICC bibliographic database is available online.

The database currently contains 9,838 references and includes citations, abstracts and assigned keywords. Updates are made every month.

The database is available as a group on Zotero. Subscribe online or, for a better user experience, download the Zotero desktop application and sync with the group OA-ICC in Zotero. Please see the “User instructions” for further details.

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Leveraging AI-driven predictors of enzyme pH optima to unravel microbial adaptation to environmental pH

Published 12 May 2026 Science Leave a Comment
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It is well-known that pH (potential of hydrogen) influences enzyme catalytic activity (Schomburg and Salzmann, 1991; Nelson et al., 2021). The pH optimum (pHopt), at which an enzyme displays maximal catalytic activity, is therefore critical for enzyme design and applications (Zhang et al., 2025). To identify suitable enzymes for target pH environments or optimize enzymatic performance in biotechnology, enzyme engineering requires efficient characterization of kinetic properties across large numbers of amino acid sequences. However, experimental determination of pHopt for numerous sequences is time-consuming, labor-intensive, and costly. To address these limitations, computational approaches based on machine learning have been developed for rapid prediction of enzyme pHopt, supporting applications in protein engineering.

Recent advances, exemplified by EpHod (enzyme pH optimum prediction with deep learning) (Gado et al., 2025), enable prediction of the enzyme pHopt directly from protein sequences. The EpHod model leverages embeddings from the protein language model (PLM) ESM-1v and achieves a root mean squared error (RMSE) of 1.25 pH units on the held-out test data (Gado et al., 2025). To further improve predictive performance, an increasing number of AI-driven tools have been developed. For instance, (Zhang et al. 2025) introduced the model VENUS-DREAM, which employs the PLM ESM-2 and reduces the RMSE to 0.809. These AI-powered tools are revolutionizing enzyme discovery and design by enabling high-throughput prediction of pHopt.

Similarly, studies of microbial adaptation to environmental pH frequently require knowledge of enzyme pHopt. This information can be used to investigate the underlying adaptive mechanisms. However, experimental determination of pHopt for large-scale enzyme sequences remains impractical due to high costs and low throughput. Fortunately, the high-throughput predictive capacity of these AI-driven tools offers a powerful alternative for obtaining enzyme pHopt values, which can facilitate investigations into the mechanisms by which microorganisms adapt to environmental pH. The potential applications are illustrated with examples below.

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Scientists collaborate with aquaculture industry on ocean acidification resiliency

Published 12 May 2026 Web sites and blogs Leave a Comment

An innovative new research project led by William & Mary’s Batten School & VIMS is bringing together scientists, shellfish farmers and community planners to prepare for emerging environmental challenges related to ocean and coastal acidification (OCA) in the Chesapeake Bay.

“It isn’t something that we’re thinking about on a daily basis, but that doesn’t mean that we shouldn’t begin planning for it now,” said Marcia Berman, co-founder of Cappahosic Oyster Company. “Aquaculture is a vulnerable industry, and more science is always welcome in helping us prepare.”

Supported by a $1.2 million grant from the National Oceanic and Atmospheric Administration’s Ocean Acidification Program, the Regional Vulnerability Assessment (NOAA RVA) study combines traditional coastal and marine science with community research to develop adaptation resources and strategies for the aquaculture industry.

With an advisory committee comprised of Batten School & VIMS experts, members of the region’s shellfish industry and community planners, work is now underway to develop a dynamic, web-based dashboard featuring user-friendly tools that will support businesses and municipalities through complex decision-making processes in the decades ahead.

An invisible shellfish stressor approaches from both land and sea  

OCA is the result of both global and local processes. On a global scale, acidification occurs when the ocean absorbs excess carbon dioxide from the atmosphere, reducing the water’s pH and making it more acidic. In coastal regions like the Chesapeake Bay, freshwater runoff introduces nutrients to coastal waters, inducing processes that can lead to further acidification.

“It’s this hidden stressor sneaking up on us and on the shellfish,” said Rivest, an associate professor at the Batten School of Coastal & Marine Sciences & VIMS and the project’s primary investigator (PI). “Animals like oysters and clams that build their shells out of calcium carbonate provide valuable environmental services and are particularly vulnerable to acidification. Understanding the impact of [OCA] on shellfish, and on shellfish farmers, is critical if we want to support the ecosystems and communities that depend on them.”

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