Archive Page 34

Robustness of gametogenesis in the scleractinian coral, Tubastraea aurea, in the shallow-water hydrothermal vent field off Kueishan Island, northeastern Taiwan

Published 8 July 2025 Science Closed
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Highlights

  • Stony corals (Tubastraea aurea) can colonize in acidified shallow-water hydrothermal vent fields.
  • T. aurea is a gynodioecious brooder; mostly females with a low percent of hermaphroditism.
  • HV colonies maintained the similar gametogenic process and seasonal timing of reproduction as NHV colonies.
  • Elevated gametogenic activity of vent T. aurea could facilitate success in extreme conditions.
  • Hydrothermal vents as natural laboratories offer insights on the resiliency of scleractinians.

Abstract

Understanding the reproductive resiliency of scleractinian corals is imperative as ocean acidification and rising sea surface temperatures threaten the foundation of coral reef ecosystems. However, the limited temporal scales of laboratory and transplantation-based methods fail to consider evolutionary time frames offered by natural analogues of future climate conditions, like hydrothermal vents (HV). Accordingly, we characterized the presence of scleractinians surrounding a major shallow-water HV near Kueishan Island in northeastern Taiwan, identified a candidate species, Tubastraea aurea, and investigated its sexual reproductive strategies. Since this was the first study to describe the sexual reproduction of T. aurea, we characterized the gametogenetic process of T. aurea colonies from the HV and three non-HV locations (NHV1, NHV2, NHV3). Oogenesis was similar between HV and NHV sites and mature oocytes reached the same size. The seasonal timing of reproduction was comparable between HV and NHV1 colonies, likely related to the similar seasonal variation of water temperatures. HV colonies showed an even higher gametogenetic activity (100 % of polyps containing developing gametes in HV colonies versus 73.5 % in NHV colonies). As assessed by the presence of larvae, T. aurea is a brooder, with mostly female polyps (97.6 %,) and a low percent of hermaphroditism (2.4 %, as observed in 2 in HV and 1 in NHV colonies). This suggests that parthenogenesis may contribute to larval production. Taken together, we demonstrated the robustness of gametogenesis in T. aurea and propose the heightened reproductive effort of T. aurea at the Kueishan Island HV could be facilitating its success in acidified conditions. Overall, this study exemplified the importance of using unique ecosystems to uncover clues on scleractinian resiliency.

Continue reading ‘Robustness of gametogenesis in the scleractinian coral, Tubastraea aurea, in the shallow-water hydrothermal vent field off Kueishan Island, northeastern Taiwan’

Nutritional status and shell properties of the scallop Argopecten purpuratus are sensitive to intense upwelling events

Published 8 July 2025 Science Closed
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Highlights

  • The scallop Argopecten purpuratus cope with permanent environmental fluctuations.
  • Upwelling intensity and duration affect its physiological perfomance.
  • Shell organic matrix was adversely affected by intense upwelling events.
  • The nutritional status of the A. purpuratus is modulated by upwelling intensity.
  • A. purpuratus seems to be partially adapted to colder, low pH and hypoxic conditions.

Abstract

Changes in environmental conditions can be particularly stressful for marine biota. However, marine organisms possess a variety of biological mechanisms (e.g., expression of stress proteins, down or up metabolic regulation, among others) that enable them to adapt to such conditions. This will ultimately determine their resilience and adaptive capacity to the natural environmental fluctuations occurring in their habitats, but also to future climate-driven shifts. In Chile, the scallop Argopecten purpuratus inhabits regions under permanent upwelling conditions causing, at different temporal and spatial scales, cooling, low pH and hypoxic conditions of diverse magnitude. In one-year field experiment, we observed that A. purpuratus was, in some occasions, adversely affected by intense upwelling events during the spring season, when the most intense upwelling events were observed, and thus the lowest temperatures, pH and oxygen levels were registered. These effects were more evident in some shell properties, such as the shell organic matrix, a key component of the biomineralization process. Also, no impacts or positive responses (i.e., up-regulation) were observed on parameters associated to their nutritional status (i.e., carbohydrate and protein muscle content), and periostracum thickness suggesting the presence of physiological trade-offs, but also adaptive mechanisms serving to cope with stressful environmental conditions. Ultimately, our findings also raise concerns about the potential consequences of intensified upwelling due to climate change, particularly for the aquaculture sector that relies on this species, since the majority of impacts were observed in individuals of sizes considered attractive to the market.

Continue reading ‘Nutritional status and shell properties of the scallop Argopecten purpuratus are sensitive to intense upwelling events’

Something in the water: how kelp is helping Maine’s mussels boom

Published 8 July 2025 Media coverage Closed
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On a glimmering May morning, Tom Briggs pilots a 45ft aluminium barge through the waters of Casco Bay for one of the final days of the annual kelp harvest. Motoring past Clapboard Island, he points to a floating wooden platform where mussels have been seeded alongside ribbons of edible seaweed.

“This is our most productive mussel site,” says Briggs, the farm manager for Bangs Island Mussels, a Portland sea farm that grows, harvests and sells hundreds of thousands of pounds of shellfish and seaweed each year. “When we come here, we get the biggest, fastest-growing mussels with the thickest shells and the best quality. To my mind, unscientifically, it’s because of the kelp.”

A growing body of science supports Briggs’s intuition. The Gulf of Maine is uniquely vulnerable to ocean acidification, which can impede shell development in mussels, clams, oysters and lobster, threatening an industry that employs hundreds of people and generates $85m to $100m (£63m to £74m) annually.

Atmospheric carbon dioxide from fossil fuels is the main driver of declining ocean pH, increasing the acidity of the world’s oceans by more than 40% since the preindustrial era and by more than 15% since 1985. Add carbon runoff from growing coastal communities, regular inflows of colder, more acidic water from Canada, and intense thermal stress – the Gulf of Maine is warming three times faster than the global average – and you’re left with a delicate marine ecosystem and key economic resource under threat.

Enter kelp. The streams of glistening, brownish-green seaweed that Bangs Island seeds on lines under frigid November skies and harvests in late spring are a natural answer to ocean acidification because they devour carbon dioxide. Sensors placed near kelp lines in Casco Bay over the past decade have shown that growing seaweed changes water chemistry enough to lower the levels of carbon dioxide in the immediate vicinity, nourishing nearby molluscs.

Continue reading ‘Something in the water: how kelp is helping Maine’s mussels boom’

The coupled oxygen and carbon dynamics in the subsurface waters of the Gulf and Lower St. Lawrence Estuary and implications for artificial oxygenation

Published 7 July 2025 Science Closed
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The Gulf and Lower St. Lawrence Estuary have experienced major environmental change over the past century, including the development of hypoxic bottom waters and their simultaneous warming and acidification. Here, we use biogeochemical observations collected during the 2021–2023 TReX project as well as historical data, combined with a tracer-calibrated 1D Advection-Diffusion model with variable boundary conditions to represent dissolved oxygen (DO) and dissolved inorganic carbon (DIC) dynamics within the core of the oxygen minimum zone (27.15–27.3 kg m-3 isopycnals) of the Laurentian Channel. The rate of in-channel oxygen utilization in the deep layer was nearly invariant from 2003 to 2023 at 21.1 ± 2.5 µmol kg-1 yr-1 and the DIC accumulation rate was estimated to be 18.3 ± 2.5 μmol kg-1 yr-1. Using δ13CDIC data, we assess the effect of microbial organic matter remineralization processes and dilution of the 13CDIC pool (−6.6×10-3 ‰ per μmol of added metabolic DIC). These data and the use of a tracer-calibrated model to resolve advection and mixing dynamics reconcile differences in prior estimates of biogeochemical transformation rates. Finally, we apply the model to the mitigation scenario proposed by Wallace et al. (2023) for artificial re-oxygenation of the Laurentian Channel bottom waters using pure oxygen. We estimate that the injection of ~8.3 × 105 tonnes yr-1 of oxygen, equivalent to an additional 55 μmol kg-1 relative to the 2023 boundary concentration proximal to the Cabot Strait, would be required to achieve and maintain above hypoxic levels (>62.5 μmol kg-1) at the head of the Laurentian Channel. Using the model, we estimate the time required to re-establish steady-state along-channel distributions of DO and DIC following a change in offshore boundary conditions to be about 10 years, or twice the along-channel transit time.

Continue reading ‘The coupled oxygen and carbon dynamics in the subsurface waters of the Gulf and Lower St. Lawrence Estuary and implications for artificial oxygenation’

NOAA hosts newly released surface ocean CO2 data

Published 7 July 2025 Web sites and blogs Closed
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NOAA’s Ocean Carbon Acidification Data System (OCADS) now includes the 2025 version of the Surface Ocean CO2 Atlas (SOCAT) database. SOCATv2025 provides quality-controlled surface ocean carbon dioxide (fCO2; fugacity of CO2) measurements from 1957 to 2024 with 41.4 million observations that can serve as pulse checks on ocean carbon. The new version adds 451 new data sets and updates 44 data sets from ships, yachts, uncrewed surface vehicles, moorings and drifting platforms.  SOCAT data are key for quantifying ocean CO2 uptake and ocean acidification, providing vital information for ocean policy and management.

OCADS is housed and maintained by the National Centers for Environmental information. NOAA’s Ocean Acidification Program funds OCADS as a national repository and much of the SOCAT data collected in the U.S. Exclusive Economic Zone to help inform maritime activities, weather and more related to ocean carbon.

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Report presenting the data quality aspects in relation with the submission mechanism requested to report towards the SDG indicator 14.3.1

Published 7 July 2025 Newsletters and reports Closed
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This document is MINKE’s Deliverable 9.12 “Report presenting the data quality aspects in relation with the submission mechanism requested to report towards the SDG indicator 14.3.1”. It describes MINKE perspectives on the monitoring of carbonate system variables, in particular pHT, in order to address the SDG 14.3 request regarding ocean acidification. The D9.12 summarises the carbonate chemistry Best Practices, uncertainty concepts and calculations discussed within MINKE and will be useful for reporting carbonate variables to the SDG ocean acidification portal.

Continue reading ‘Report presenting the data quality aspects in relation with the submission mechanism requested to report towards the SDG indicator 14.3.1’

How the ‘evil twin’ of the climate crisis is threatening our oceans

Published 7 July 2025 Media coverage Closed

On a clear day at Plymouth marina you can see across the harbour out past Drake’s Island – named after the city’s most famous son, Francis Drake – to the Channel. It’s quite often possible to see an abundance of marine vessels, from navy ships and passenger ferries to small fishing boats and yachts. What you might not spot from this distance is a large yellow buoy bobbing up and down in the water about six miles off the coast.

This data buoy – L4 – is one of a number belonging to Plymouth Marine Laboratory (PML), a research centre in Devon dedicated to marine science. On a pleasantly calm May morning, Prof James Fishwick, PML’s head of marine technology and autonomy, is on top of the buoy checking it for weather and other damage. “This particular buoy is one of the most sophisticated in the world,” he says as he climbs the ladder to the top. “It’s decked out with instruments and sensors able to measure everything from temperature, to salinity, dissolved oxygen, light and acidity levels.”

It’s the hourly recordings of this last measurement, the pH of the water, that are adding to a picture locally and globally that is increasingly concerning scientists.

The results show that ocean acidification is rising – and it is doing so at an alarming rate. Ocean acidification, often called the “evil twin” of the climate crisis, is caused when carbon dioxide is rapidly absorbed into the ocean, where it then reacts with water molecules leading to a fall in the pH of the seawater.

Continue reading ‘How the ‘evil twin’ of the climate crisis is threatening our oceans’

Data-driven modeling of 4D ocean and coastal acidification in the Massachusetts and Cape Cod Bays from surface measurements

Published 7 July 2025 Science Closed
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Abstract

A significant portion of atmospheric  emissions is absorbed by the ocean, resulting in acidified seawater and altered carbonate composition that is harmful to marine life. Despite detrimental effects, assessing ocean and coastal acidification (OCA) is difficult due to the scarcity of in situ measurements and the high costs of computational modeling. We develop a parsimonious data-driven framework to model indicators of OCA and test it in the Massachusetts Bay and Stellwagen Bank, a region with fishing and tourism industries affected by OCA. First, we trained a neural network to predict in-depth fields for temperature and salinity  using surface quantities from satellites and in situ measurements . The relationship between 2D surface and 3D properties is captured through the in-depth modes and coefficients obtained from principal component analysis applied to a high-resolution historical reanalysis data set. Next, we used Bayesian regression methods to estimate region-specific relationships for in-depth total alkalinity (TA), dissolved inorganic carbon (DIC), and aragonite saturation state  as functions of temperature, salinity, and chlorophyll. Lastly, 4D daily field predictions are generated from surface measurements with a spatial resolution of 4 km horizontally and 45 sigma levels vertically. The model’s performance is evaluated using withheld measurements across depths, locations, and seasons with RMSEs of 1.59°C, 0.31 PSU, 37.54 mol, 39.40 mol, and 0.42 for temperature, salinity, TA, DIC, and , respectively, at one withheld location. The framework is useful for understanding OCA and includes uncertainty quantification for future planning and optimal sensor placement.

Plain Language Summary

About a quarter of carbon dioxide emissions in the atmosphere is absorbed by the oceans. When this carbon dioxide dissolves in seawater, it results in ocean acidification (OA). A useful indicator of OA is the saturation state of aragonite, a type of calcium carbonate used by organisms that form shells. However, understanding the effects of OA is difficult due to the lack of observations and the high cost and complexity of modeling. We present a data-driven approach to model carbonate chemistry using readily available observations from satellites and low-cost sensors. Given surface measurements of temperature, salinity, and chlorophyll, our machine learning model produces temperature, salinity, total alkalinity, dissolved inorganic carbon, and aragonite saturation state covering spatial (latitude, longitude, and depth) and temporal domains for these variables. Compared to withheld observations, our model achieved reasonable accuracy across many seasons and depths, a level of resolution not matched by other models for the same set of inputs. Our model is useful for monitoring, decision-making, and future planning.

Key Points

  • We present a data-driven approach to rapidly model 4D carbonate chemistry fields given readily available surface observations
  • By using training data from both physics simulations and field observations, the model achieves very high resolution with minimal inputs
  • The step-by-step method can be reproduced in other regions or for new data, and includes uncertainty quantification for decision-making
Continue reading ‘Data-driven modeling of 4D ocean and coastal acidification in the Massachusetts and Cape Cod Bays from surface measurements’

Increased temperature and acidification elevate the risk of starvation in American lobster larvae 

Published 4 July 2025 Science Closed
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The geographic range of the American lobster, Homarus americanus, spans a steep thermal gradient along the coastal Northwest Atlantic. As CO2 emissions increase globally, this range is rapidly warming and acidifying. Larval H. americanus hatch with a finite amount of maternally sourced lipid stores in their yolk sac, which provide an energetic buffer during the intermediate period between hatch and first feed. This study examines the response of newly-hatched, unfed H. americanus larvae to the combined effects of elevated pCO2 and temperature. Using a space-for-time approach, we compared larvae of two distinct sub-populations from thermally contrasting regions: Rhode Island, at the warmer, southern limit of the species range, and Midcoast, Maine, a cooler northern region. Average larval initial post-hatch weight was similar across regions and variability therein could be explained by maternal effects. Under 6 days of starvation, larvae from the two regions lost ∼14% of their initial dry weight and 25% of their Carbon weight. Still, end-century elevated temperature or acidification did not substantially alter those rates for larvae from either region. However, under an identical range of conditions over the 6-day experiment, larvae from the warmer regime maintained relatively stable oxygen consumption rates, while those from the cooler regime started 50% higher, then dropped by 80% within 2 days. If depressed metabolic functioning translates to reduced feeding efficiency for cool regime larvae, our findings suggest that subpopulations in the southern edge of the species range have a relative advantage in food-scarce environments under these conditions, adding to previous evidence for countergradient variation in this species. Further analysis of total fatty acid losses conducted on Midcoast larvae suggested starved larvae exposed to elevated temperature (19°C) experienced considerably greater losses of key lipid groups than larvae under ambient conditions (16°C, 400 ppm), particularly within the first 2 days of exposure. Our results highlight the short time frames over which ocean warming can accelerate the depletion of energy stores and make larvae more vulnerable to starvation.

Continue reading ‘Increased temperature and acidification elevate the risk of starvation in American lobster larvae ‘

Dissolved inorganic carbon entrainment into the mixed layer of the western subarctic North Pacific: a key process of ocean acidification under historical carbon dioxide emissions

Published 4 July 2025 Science Closed
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This study investigated processes responsible for the acidification of the mixed layer water at station K2 (N, E) in the western subarctic North Pacific by analyzing physical and biogeochemical variables during 1850–2014 in a Geophysical Fluid Dynamics Laboratory Earth system model of Coupled Model Intercomparison Project Phase 6 under historical carbon dioxide () emissions. Analysis revealed an accelerated pH decline at a rate of −0.0015 , which began around 1960. An increase in dissolved inorganic carbon (DIC) is found to be the principal factor of the pH decline. DIC budget analysis of the mixed layer identified the primary physical process accelerating the DIC increase during 1960–2014: enhanced vertical entrainment of the DIC-rich deep water into the mixed layer during autumn–winter (rate of 3.1 μ). This enhancement is attributed to the equatorial Pacific frequent high sea surface temperature condition due to global warming and El Niño events through the model’s atmospheric teleconnection.  gas exchange at the sea surface contributes secondarily to the DIC increase (0.16 μ). Meanwhile, horizontal advection (−0.6 μ) and biological consumption (−2.6 μ) partially counteract DIC input. These physical and biological processes collectively resulted in a simulated DIC increase of 0.043 μ (i.e., 0.52 μ), consistent with the observed increase rate.

Continue reading ‘Dissolved inorganic carbon entrainment into the mixed layer of the western subarctic North Pacific: a key process of ocean acidification under historical carbon dioxide emissions’

Magnesium (Mg∕Ca, δ26Mg), boron (B∕Ca, δ11B), and calcium (Ca2+) geochemistry of Arctica islandica and Crassostrea virginica extrapallial fluid and shell under ocean acidification

Published 4 July 2025 Science Closed
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The geochemistry of biogenic carbonates has long been used as proxies to record changing seawater parameters. However, the effect of ocean acidification (OA) on seawater chemistry and organism physiology could impact isotopic signatures and how elements are incorporated into the shell. In this study, we investigated the geochemistry of three reservoirs important for biomineralization – seawater, the extrapallial fluid (EPF), and the shell – in two bivalve species: Crassostrea virginica and Arctica islandica. Additionally, we examined the effects of three ocean acidification conditions (ambient: 500 ppm CO2, moderate: 900 ppm CO2, and high: 2800 ppm CO2) on the geochemistry of the same three reservoirs for C. virginica. We present data on calcification rates, EPF pH, measured elemental ratios (Mg/Ca, B/Ca), and isotopic signatures (δ26Mg, δ11B). In both species, comparisons of seawater and EPF Mg/Ca and B/Ca, Ca2+, and δ26Mg indicate that the EPF has a distinct composition that differs from seawater. Shell δ11B did not faithfully record seawater pH, and δ11B-calculated pH values were consistently higher than pH measurements of the EPF with microelectrodes, indicating that the shell δ11B may reflect a localized environment within the entire EPF reservoir. In C. virginica, EPF Mg/Ca and B/Ca, as well as absolute concentrations of Mg2+, B, and Ca2+, were all significantly affected by ocean acidification, indicating that OA affects the physiological pathways regulating or storing these ions, an observation that complicates their use as proxies. Reduction in EPF Ca2+ may represent an additional mechanism underlying reduction in calcification in C. virginica in response to seawater acidification. The complexity of dynamics of EPF chemistry suggests boron proxies in these two mollusk species are not straightforwardly related to seawater pH, but ocean acidification does lead to both a decrease in microelectrode pH and boron-isotope-based pH, potentially showing applicability of boron isotopes in recording physiological changes. Collectively, our findings show that bivalves have high physiological control over the internal calcifying fluid, which presents a challenge in using boron isotopes for reconstructing seawater pH.

Continue reading ‘Magnesium (Mg∕Ca, δ26Mg), boron (B∕Ca, δ11B), and calcium (Ca2+) geochemistry of Arctica islandica and Crassostrea virginica extrapallial fluid and shell under ocean acidification’

Seasonal and interannual variability of the aragonite saturation horizon in the California Current System of Baja California

Published 4 July 2025 Science Closed
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Abstract

Hydrographic data from cruises of the Investigaciones Mexicanas de la Corriente de California (IMECOCAL) program since 1998 were used to assess the chemical conditions associated with carbon variables in the water column in the transect “Line 100.” Seasonal climatologies along the IMECOCAL line highlight the upwelling season, during which water with different chemical characteristics is transported to the surface. Additionally, interannual events influenced the amplitude and timing of wind-driven coastal upwelling and the region’s relative volumes of dominant water mass. Seasonal climatologies of pH, calcium carbonate saturation states, and dissolved inorganic carbon (DIC) concentration were estimated from hydrographic proxy variables. The strength of seasonal upwelling was reflected in the depth of the aragonite saturation horizon (ASH), which was variable nearshore: 90 m (±29 m) in spring and 133 m (±32 m) in winter. Offshore (>50 km), the effect of upwelling diminished, and the ASH was deeper and less variable (spring: 152 m ± 25 m; winter: 151 m ± 28 m). However, aragonite saturation values <1 were found at depths >250 m and were associated with Equatorial Subsurface Water (ESsW) dominance. At seasonal timescales, Subarctic Water (SAW) was found to modulate ASH depth. At interannual scales, ASH was found to be deeper (180 m) during periods of El Niño and shallower (120 m) during La Niña conditions. However, the impacts of El Niño and La Niña events give notable differences in the ASH depth.

Key Points

  • Advection of surface water masses modulate the cross-shore aragonite saturation horizon depth and minimize the biological influence
  • Aragonite saturation values <1 were found at 50 m nearshore due to the strength of upwelling and equatorial subsurface water
  • The aragonite saturation horizon depth tended to be shallower during fall under La Niña conditions than under El Niño conditions

Plain Language Summary

In the California Current System, where nutrient and carbon rich subsurface waters are brought to the surface and support a productive ecosystem, higher seawater carbon dioxide levels result in a reduction of the carbonate ion concentrations, which serve as building blocks for marine species that create calcium carbonate shells or skeletons. Therefore, it is more difficult for these organisms to form carbonate structures when the saturation states of aragonite or calcite, two forms of calcium carbonate created by marine species, are low. Here, we investigated drivers of seasonal and interannual variability of the aragonite saturation horizon (ASH; below this depth, conditions are corrosive to aragonite) since 1998 along a cross-shelf transect in the Southern California Current System to ∼220 km offshore off Ensenada using IMECOCAL surveys. We found that variability in coastal upwelling intensity and the relative dominance of regional water masses were important factors influencing the depth of the ASH. Seasonal and interannual patterns of variability of seawater carbonate chemistry have implications for how southern California Current ecosystems will be affected by human activities.

Continue reading ‘Seasonal and interannual variability of the aragonite saturation horizon in the California Current System of Baja California’

Call for two new members of the IOCCP Scientific Steering Group

Published 4 July 2025 Jobs Closed

To make inquiries and/or to submit your application for one of the positions, please contact the IOCCP Project Office (ioccp@ioccp.org), by 1 August 2025. 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 two experts to join its Scientific Steering Group (SSG) for term beginning on 1 October 2025. New SSG members 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 the following phenomena of interest: ocean acidification, ocean deoxygenation, eutrophication, exchanges between the ocean and the atmosphere, surface ocean and deep ocean, and carbon and nutrient remineralization and sequestration. 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 2-3 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 two IOCCP SSG positions described below. The responsibilities of newly appointed members will include the following IOCCP activities: 

Position #1: Coordination of Optimal Global Design for Ocean Carbon Observations

In particular, we seek individuals with experience/expertise and interests in:

  • using model- and/or statistical-based approaches, such as OSEs, OSSEs, or ensemble models, to evaluate simulated observing networks;
  • participation in and coordination of modeling and/or mapping intercomparison studies across different research groups;
  • collaborative projects across ocean carbon modeling and observing communities;
  • using observational data to evaluate models and/or data-based interpolated products;
  • enabling open access to modeling and/or machine learning tools for training and research collaboration.
  • Liaison with ocean carbon from space community to establish needs and requirements for an integrated carbon observing system

Position #2: Coordination of Regional Ocean Biogeochemical Observations in Latin America

In particular, we seek individuals with experience/expertise and interests in:

  • reducing barriers to collaborating across nations, institutions, or research groups;
  • leading collaborative funding proposals to expand regional capacity to collect and share ocean biogeochemical data;
  • facilitating further development and promoting the use of common best practices;
  • serving as conduit for information sharing between the region and the international groups coordinating ocean biogeochemical observations.

For both positions we seek individuals who would expand IOCCP’s capabilities to address issues related to better integration between open ocean and coastal observations of marine biogeochemistry resulting in high quality, interoperable data of use for many applications ranging from climate science, through operational services, to ocean health. We seek individuals who are familiar with the ongoing community initiatives and needs. Ideally candidates would have research experience on an international level and a working overview of the global landscape within the selected Theme. We encourage applications from individuals with strong leadership skills and past experience in providing strategic guidance, e.g. through international working groups or steering committees participation.

To make inquiries and/or to submit your applications, please contact the IOCCP Project Office (ioccp@ioccp.org) by 1 August 2025. Please provide the following information in your application:

  1. CV including (at a minimum)
    1. Full name, nationality, contact information (incl. email and institutional website link if available)
    2. Affiliation and held positions in the past 5 years (with brief description of tasks and responsibilities)
    3. Membership in national and international networks, programs, expert working groups, etc.
    4. Up to 10 most relevant publications
  2. Brief description (approx. 300 words) of how you see yourself contributing to IOCCP Terms of Reference and what is your proposed vision for activities related to the advertised position.
Continue reading ‘Call for two new members of the IOCCP Scientific Steering Group’

CO2 enrichment enhances biomass density and C:N:P ratios in phytoplankton assemblage in the coastal water of the Taiwan Strait

Published 3 July 2025 Science Closed
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Seawater CO2 concentrations are steadily increasing in the Taiwan Strait of the Southeast China, while the effects of rising CO2 on carbon fixation and elemental composition of phytoplankton assemblages in this area are still poorly understood. Here, we enriched the seawater CO2 concentrations to 808 μatm and above to simulate the CO2–induced ocean acidification, and investigated the effects of CO2 enrichment on concentrations of chlorophyll (Chl) a, particulate organic carbon (POC), nitrogen (PON) and phosphorus (POP), the C:N:P ratio, and phytoplankton community composition in the coastal surface seawaters of the northwest Taiwan Strait in autumn 2023 and spring 2024 through an outdoor incubation experiment. After three days of incubation, CO2 enrichment increased the concentrations of Chl a by 1–14%, POC by 21–32% and PON by 21–56%, whereas reduced the POP concentrations by 1–37%, leading to elevated ratios of POC:POP and PON:POP. Furthermore, elevated CO2 level enhanced cell abundances of the dominant diatom genera at three stations. These results suggest that phytoplankton has the potential to buffer against rising atmospheric CO2 level and can help us to understand the elemental biogeochemistry in the Taiwan Strait under future ocean acidification scenarios.

Continue reading ‘CO2 enrichment enhances biomass density and C:N:P ratios in phytoplankton assemblage in the coastal water of the Taiwan Strait’

Seaweed responses to ocean acidification: global impacts on growth, biochemical composition, and CO2 mitigation potential

Published 3 July 2025 Science Closed
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Ocean acidification, driven by the absorption of elevated atmospheric CO2 levels, significantly affecting the growth and nutritional composition of marine biota, including seaweeds. The increasing expansion of the cultivation of seaweed is a promising method for removing carbon dioxide through both government and private sectors. There are notable comprehensive assessments that evaluated the effectiveness of seaweed farming to achieve significant climate change mitigation and it ended with positive outcome. Hence the present article reviews about the global impacts of ocean acidification on seaweed communities including growth dynamics, nutritional trends, and their potential for CO2 mitigation. The ecological consequences of ocean acidification and providing an overview of its status. Amplified CO2 levels affect seaweed physiology and ecosystem dynamics that have an influence on biodiversity, carbon cycling, and nutrient flows. The review highlights the trends in seaweed growth under elevated CO2 conditions, through identification of both opportunities and challenges for maintenance of productivity and nutritional quality. Seaweeds exhibit potential for CO2 sequestration, that whorls to offset carbon emissions through aquaculture practices. Furthermore, integrated seaweed farming practices can enhance environmental benefits, such as biodiversity conservation, nutrient remediation, and improved carbon storage. Finally, yet importantly this article emphasizes the necessity for targeted research that aimed at optimization of seaweed cultivation techniques, decipher species-specific responses to ocean acidification, and leveraging biotechnological advancements for maximation in mitigation of CO2. The findings underscore the role of seaweed aquaculture as a sustainable strategy to combat climate change and protect marine ecosystems.

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Brachiopods and forams reduced calcification costs through morphological simplification during mass extinction events

Published 3 July 2025 Science Closed
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Environmental stressors have exacerbated the collapse of marine ecosystems during mass extinctions. However, the survival strategies of marine species during mass extinctions remain unclear. Here, we investigated morphological evolution of brachiopods across the Permian–Triassic mass extinction (PTME) using a database of 3,225 specimens representing 1,061 species and foraminifera across the PTME and early Toarcian oceanic anoxic event (T-OAE) using a database of 757 specimens representing 12 species. We found a significant reduction in the number and proportion (plicae length/shell length) of shell plicae of brachiopods (36.4% and 60.0%, respectively) across the PTME and a significant decrease in the shell thickness of foraminifera (18.9% and 42.4% across the PTME and 36.9–61.8% across the T-OAE). We calculated that these adaptive strategies could reduce the energetic costs of calcification by more than half for brachiopods across the PTME, and by ~20–62% for foraminifera across the PTME and T-OAE, to compensate for the elevated cost of calcification due to environmental and ecological pressures. We propose that simplification of morphological features, such as reduced shell ornamentation and shell thinning, serves as a potential economic strategy for calcifying organisms to cope with extinction events by reducing energy demands, but further studies with a broader range of taxa and extinction events are needed to confirm the generality of this bioenergetic strategy.

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Decreased dimethylsulfide and increased polybrominated methanes: potential climate effects of microplastic pollution in acidified ocean

Published 3 July 2025 Science Closed
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Microplastic (MP) pollution and ocean acidification (OA) are pressing marine environmental concerns, but their combined impacts on short-lived biogenic climate-active gases and the resulting climate effects remain unclear. To address this gap, a ship-based microcosm experiment was conducted, where OA and MP pollution were simulated under in situ conditions to explore their effects on the production of dimethylsulfide (DMS), bromoform (CHBr3), and dibromomethane (CH2Br2). The results indicated that both MP and OA inhibited phytoplankton growth and DMS concentration, with OA inducing further reductions in the production rate and yield of DMS. MP addition led to extra dissolved organic matter, and the acidified condition enhanced bromoperoxidase activity, both of which promoted the production of CHBr3 and CH2Br2. When OA and MP addition were combined, DMS concentrations decreased by 61%, whereas CHBr3 and CH2Br2 concentrations increased by 132% and 45%, respectively. Based on the results, MP pollution under OA conditions might directly reduce DMS accumulation or decrease the formation of DMS-derived sulfate aerosols by increasing CHBr3 and CH2Br2 levels, which finally weaken DMS’s climate-cooling capabilities. This study underscores the potential for MP pollution in future acidified oceans to exacerbate global warming by disrupting the cycle of marine biogenic climate-active gases.

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Impacts of ocean acidification and altered prey fatty acids on the early development of northern rock sole (Lepidopsetta polyxystra) larvae

Published 3 July 2025 Science Closed
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Highlights

  • Carbon dioxide (CO2) and dietary fatty acids (FAs) had stage-specific effects on northern rock sole larvae.
  • After 2-weeks of feeding, larvae had faster growth under elevated CO2 conditions.
  • After 5-weeks of feeding, larvae had higher lipid storage when fed a diet with balanced-essential FAs.

Abstract

Ocean acidification (OA) is predicted to affect the physiological rates of larval fish and invertebrates and is also expected to significantly impact marine fisheries through alteration of food webs. We examined whether mortality rates, body size, and condition of first-feeding larval northern rock sole, Lepidopsetta polyxystra, were synergistically influenced by prey quality (essential fatty acids, EFAs) and high carbon dioxide (CO2) exposure. Larvae were exposed to ambient and high CO2 levels (∼ 330 vs. 1020 μatm) and were fed diets with balanced or unbalanced EFA ratios for 7 weeks immediately following hatch. After 2 weeks, significant effects from CO2 and diet were observed, with the largest larvae occurring in the high CO2 exposure group that received a balanced EFA diet. After 5 weeks of exposure, the effects of elevated CO2 had a diminished impact on larval size, but larvae reared on the balanced EFA diet maintained higher lipid-based condition metrics than those fed an unbalanced EFA diet. Survival was variable across replicate tanks and not significantly different between treatments. This study suggests that L. polyxystra larvae are most vulnerable to OA and food web change at different points in their development. Further understanding of these ecosystem effects will be required to predict the impacts of OA on northern rock sole fisheries.

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Ocean acidity extremes retard shell formation of bivalve larvae: insights from transcriptomics and lipidomics

Published 2 July 2025 Science Closed
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Highlights

  • Effects of ocean acidity extremes (OAX) on early development of clams were assessed.
  • OAX retarded shell formation of clam larvae.
  • Reduced Ca2+ uptake and HCO3− production led to larval developmental retardation.
  • OAX decreased cell membrane fluidity, limiting the uptake of calcification substrates.
  • Larval shell formation under OAX was inhibited by depletion of energy reserves.

Abstract

In view of climate change and human activities, ocean acidity extreme (OAX) events have been increasingly reported worldwide over the last decades, which possibly retard the growth and development of marine organisms, particularly at their early life-history stages (e.g., embryos or larvae). Thus, understanding whether they can adjust to the sudden increase in seawater acidity has drawn growing attention. Using a commercially and ecologically important bivalve species (Ruditapes philippinarum) with a widespread distribution in the world, we assessed the impact of OAX on its embryonic and larval development as well as expressions of functional genes and lipids to indicate physiological and cellular performance. We found that embryonic development and larval shell formation were inhibited by OAX mainly due to the downregulation of key genes responsible for the uptake of calcium ions from ambient seawater (e.g., NCX, VGCC and SERCA) and the reduced production of bicarbonate ions through the catalytic action of carbonic anhydrase. In addition, a major remodelling in membrane lipids (e.g., PC, PE, PG, PI and PS) indicated that OAX impacted the fluidity and stability of cell membrane, hindering the uptake of calcification substrates. The depletion in energy reserves, such as triacylglycerol, can also account for the impairment in larval shell formation under OAX conditions. By integrating transcriptomics and lipidomics, our findings illustrate a novel molecular mechanism underlying the detrimental effect of OAX on larval development and hence population maintenance of marine organisms, which can have profound implications for sustaining ecosystem stability and aquaculture management.

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Phenotypic plasticity in Mediterranean gorgonians Eunicella singularis and Paramuricea clavata at high temperature and low pH

Published 2 July 2025 Science Closed
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Highlights

  • The oxygen consumption of the gorgonian corals increased at high temperatures.
  • Energy reserves were not affected by high temperature, low pH or their interaction.
  • The global DNA methylation in Eunicella singularis was not affected by high temperature, low pH, or their combination.
  • Global DNA methylation in Paramuricea clavata decreased under high temperature and low pH.
  • High temperature alone caused more DEGs in E. singularis than low pH or combined treatment.

Abstract

The Mediterranean gorgonian octocorals are threatened by acidification, warming and marine heat waves. Phenotypic plasticity is critical for slow-growing gorgonians, as adaptation through natural selection might not be fast enough to cope with rapid environmental changes. DNA methylation (DNAm) is a type of (trans)generational phenotypic plasticity mechanism that may help slow-growing corals better withstand the effects of environmental changes by adjusting gene expression. This study aimed to assess the physiological responses and epigenetic modifications associated with phenotypic plasticity in the Mediterranean gorgonians Eunicella singularis and Paramuricea clavata exposed to warming (+4 °C), acidification (−0.35 pHT units) and their combination over two weeks. In addition, RNA-Seq-based differential gene expression analysis was performed for E. singularis.

High temperature, low pH and their combination did not cause tissue death or necrosis in the corals. Polyp activity in E. singularis increased at high temperatures. Warming increased oxygen consumption in both species. Energy reserves (protein, lipid, carbohydrate contents) were not affected by temperature, pH or their interaction in either species. The global DNA methylation (gDNAm) rate was ten times higher in P. clavata than in E. singularis. There was no effect of temperature, pH or their interaction on gDNAm in E. singularis. gDNAm in P. clavata decreased at high temperatures and low pH. Differential gene expression analysis indicated that high temperature induced the most extensive transcriptional changes in E. singularis, while low pH alone had the least impact. The combined stress of high temperature and low pH also led to notable up- and downregulation of gene expression. Heat stress in E. singularis caused widespread downregulation of transcription factors (TFs), particularly those in the zf-C2H2, AP-2, and HMG families. Conversely, the IRF, RFX, P53, and NRF1 families were upregulated, highlighting the complex transcriptional response to thermal stress. Overall, these physiological, transcriptomic and epigenetic alterations have the potential to negatively impact the fitness of these emblematic species and their associated ecosystems.

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