Posts Tagged 'North Atlantic'

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Coastal ocean acidification in our local waters

Published 19 November 2025 Media coverage Closed
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Off the coast of Long Island, climate change and pollution are making local waters more acidic.

This is from a process known as Coastal Ocean Acidification where carbon dioxide and land-based pollution lower the water’s ph. The problem can also worsen when algal blooms or fast-growing algae feed on that pollution. With lower pH levels, species like clams and phytoplankton have trouble forming their shells.

Christopher Gobler, a professor at Stony Brook’s School of Marine and Atmospheric Sciences explains. “That carbonate that they use to make their shell, becomes less abundant. And so almost like a linear relationship. So it goes down and the carbonate concentrations go down with it. And that makes calcifying a challenge,” he said.

The process or synergy shows how climate change, algal blooms, and local pollution, when combined, can affect our waters to this level. “That’s one of the . . . unintended or unanticipated outcome sometimes, of all these processes. And . . . it’s one of the things that makes climate change less predictable than we would like,” Gobler said.

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A century of change in the California Current: upwelling system amplifies acidification

Published 19 November 2025 Science Closed
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Predicting the pace of acidification in the California Current System (CCS), a productive upwelling system that borders the west coast of North America, is complex because the anthropogenic contribution is intertwined with other natural sources. A central question is whether acidification in the CCS will follow the pace of increasing atmospheric CO2, or if climate effects and other biogeochemical processes will either amplify or attenuate acidification. Here, we apply the boron isotope pH proxy to cold-water orange cup corals to establish a historic level of acidification in the CCS and the Salish Sea, an associated marginal sea. Through a combination of complementary modeling and geochemical approaches, we show that the CCS and Salish Sea have experienced amplified acidification over the industrial era, driven by the interaction between anthropogenic CO2 and a thermodynamic buffering effect. From this foundation, we project future acidification in the CCS under elevated CO2 emissions. The projected change in pCO2 over the 21st century will continue to outpace atmospheric CO2, posing challenges to marine ecosystems of biological, cultural, and economic importance.

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Consequences of climate change for foraminifera and foraminifera communities

Published 11 November 2025 Science Closed
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Single-celled protists called foraminifera perform critical ecosystem functions across the world’s oceans, including cycling of biogeochemically relevant compounds, sequestering carbon, and serving as biological monitoring tools of ecosystem health. However, anthropogenic climate change increases risks for these species in the oceans of the future. As ocean conditions change due to increased carbon dioxide in the atmosphere from anthropogenic sources, dire consequences to the world’s oceans are emerging such as oceanic deoxygenation, or the reduction of dissolved oxygen in water due to increased heat; coastal acidification, or decreases in coastal water pH due to increased dissolved carbon dioxide; and sea-level rise, which is cause by rising temperatures and melting icecaps. Currently, the responses of foraminifera to these important climate change risk-factors have not been well-studied. This study examines the responses of this group to the threats of climate change to predict their ecological success and capacity to serve as bioindicators as oceans continue to change.

In Manuscript I, transcriptomes were collected from two species of foraminifera collected from the Santa Barbara Basin off the coast of California: Nonionella stella and Bolivina argentea. These two species thrive in anoxic to euxinic and hypoxic sediments, respectively. However, the metabolic processes that enable these species to achieve high ecological success in extreme conditions are unclear. This study presented detailed metabolic reconstructions and differential gene expression that illustrated the cellular processes localized to the peroxisome and mitochondria. This metabolism enables survival in oxygen-depleted sediments and suggested that these species are likely to experience range expansion as deoxygenated regions get larger with climate change.

Manuscript II investigated responses of a Rhode Island salt marsh foraminifera, Haynesina sp., to coastal acidification. As carbon dioxide concentrations raise in the atmosphere, chemical equilibria dictate that carbon dioxide concentrations increase in the ocean as well. When carbon dioxide dissolves in seawater, several spontaneous chemical reactions occur that lead to decreased pH, which can have detrimental impacts on calcium carbonate-depositing organisms. These processes can be exacerbated in coastal systems, where conditions fluctuate to higher extremes than in the open ocean. Many foraminifera, including Haynesina sp., have calcium carbonate tests that could leave these species at high risk due to ocean acidification. This study detailed the morphological responses of Haynesina sp. to coastal acidification over biologically relevant timescales to determine that, although Haynesina sp. may be resistant to moderate elevated carbon dioxide, exposure to high elevated pCO2 leads to morphological defects in living cells. Altogether, this study demonstrated that Haynesina are susceptible to extreme coastal acidification and risk dissolution under those conditions.

In Manuscript III, the scope of foraminifera examined was expanded from individual species to whole communities by using DNA metabarcoding to examine how communities may shift in response to sea-level rise mitigation efforts. As global climate change proceeds, temperatures are expected to rise, which will result in increases in sea-level as water stored in ice and glaciers continues to melt. Due to increases in sea-level, it is expected that many coastal regions of the United States could be submerged in the next 100 years. To mitigate increases sea-level rise, conservation efforts are underway to raise the elevation of salt marshes through thin layer placement of sediment. This restoration technique involves adding large amounts of sediment to the surface of salt marshes and has been noted to have beneficial impacts for vegetation; however, impacts on other associated ecosystems, such as the subtidal and intertidal regions, are unknown. This study found that each of the three sites examined across the Rhode Island coast had distinct foraminiferal communities. Additionally, in the two restored marshes, TLP seemed to significantly impact foraminiferal alpha diversity. Across the two restored marshes, variable responses in alpha and beta diversity were observed. The results show that Rhode Island salt marshes have divergent responses to thin layer placement and need to be studied individually to determine the impacts of restoration. Despite this, our results suggest that TLP can have positive impacts on the health of some intertidal ecosystems.

In conclusion, these studies demonstrate that foraminifera have complex and varied responses to risk factors associated with climate change and climate change mitigation efforts. In some scenarios, such as oceanic deoxygenation, some taxa are poised to experience success and range expansion. However, other scenarios, such as ocean acidification, may lead to increased risk for species within this group under extreme scenarios. Further, foraminifera have the capacity to act as bioindicators, as is seen in the face of sea-level rise mitigation efforts, where foraminifera demonstrate a strong potential to act as an indicator species for ecosystem health.

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Impact of climate change driven freshening, warming, and ocean acidification on the cellular metabolism of Atlantic cod (Gadus morhua)

Published 27 October 2025 Science Closed
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Climate change is causing increasing sea surface temperature, ocean acidification and, in near shore waters, freshening. We investigated the metabolic effects of all three and their combination in Atlantic cod from the Skagerrak (eastern North Sea) by measuring concentration changes of a wide range of metabolites involved in energy production in the liver and muscles. Liver metabolism was more strongly affected than muscle, reflecting its central regulatory role. Most amino acid concentrations declined in both tissues across all treatments, and metabolomic pathway analysis revealed significant enrichment in ten metabolic pathways. This suggests enhanced amino acid metabolism in a climate change future. Warming and ocean acidification induced increased liver concentrations of lactate, glucose and fructose 1,6-bisphosphate indicating that gluconeogenesis will increase to meet increased production of enzymes to counter future stress. The molar contribution of glutamine to the total change in liver amino acids constituted 49%, 16% and 29% under warming, ocean acidification and their combination accentuating its importance in energy production also under future climate change. We observed contrasting responses in AMP, ADP, and NAD+ concentrations between warming and acidification suggesting possible antagonistic effects. Our findings demonstrate significant and complex metabolic responses to future climate stress in Atlantic cod in northern European waters.

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Two decades of pHT measurements along the GO-SHIP A25 section

Published 27 October 2025 Science Closed
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The North Atlantic (NA) GO-SHIP A25 OVIDE-BOCATS section is a long-term repeat hydrographic transect extending from Portugal to Greenland. Since 2002, physical and biogeochemical measurements have been carried out biennially along the OVIDE-BOCATS section, contributing to a better understanding of water mass properties, mixing, circulation, carbon storage, and climate change impacts such as ocean acidification (OA) in the NA. In particular, the high-precision pH measurements on the total hydrogen ion scale (pHT) from the OVIDE-BOCATS program represent a key milestone in monitoring OA in this particularly climate sensitive region. The method used for pHT determination relies on adding meta-cresol purple (mCP) dye to the seawater sample and spectrophotometrically measuring its absorbances at specific wavelengths. The OVIDE-BOCATS program has used unpurified mCP dye, which impurities have been proven to bias pHT values. Here we quantified the bias induced by these impurities in pHT measurements. We found that measurements carried out using the unpurified mCP dye tend to be, on average, 0.011 ± 0.002 pHT units higher than those obtained using the purified mCP dye, with this difference slightly decreasing at higher pHT values. Moreover, we tested independent methods to correct the effect of impurities in both the historical and recent OVIDE-BOCATS pHT data, demonstrating that the correction is consistent across methods. The long-term pHT dataset has been updated to include newly acquired data and absorbance measurements, and to standardize corrections for mCP dye impurities. This effort results in a twenty-year dataset of pHT corrected for mCP dye impurities, that demonstrates the possibility of a global effort to improve the reliability and coherency of spectrophotometric pHT measurements made with unpurified mCP dye. The corrections applied to our pHT dataset have negligible implications for the OA rates previously reported, but they do affect the depth of the aragonite saturation horizon, implying a shoaling of approximately 150 m.

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A tri-national initiative to advance understanding of coastal and ocean acidification in the Gulf of Mexico/Gulf of America

Published 23 October 2025 Science Closed
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The Gulf of Mexico’s (also recognized by the United States government as the Gulf of America; herein referred to as “the Gulf”) valuable and diverse marine, coastal, and estuarine environments sustain many habitats, species, and economically important fisheries that are vulnerable to open ocean and coastal acidification (OOCA), including shellfish, coral reefs, and other carbonate reefs and seafloor. OOCA poses an economic threat to the Gulf’s economy, which is estimated to have a combined value of $2.04 trillion (US) per year across Cuba, Mexico and the United States (U.S.). Scientists from Cuba, Mexico, and the U.S. co-organized and co-hosted the first Gulf International Ocean Acidification Summit on Oct. 18-19, 2022 in Mérida, Yucatan, Mexico to exchange information and begin development of a new tri-national network to address the socioeconomic and ecological impacts of OOCA in the Gulf based on common needs. The meeting included representatives from government agencies, universities, research institutes, non-governmental organizations, and was sponsored by the Furgason Fellowship of the Harte Research Institute at Texas A&M University-Corpus Christi. Discussions focused on each country’s challenges, including known and potential socioeconomic vulnerabilities and biological and ecosystem responses to OOCA. Shared priorities were identified for observational, biological, environmental needs, socioeconomic research, outreach, and communications. Priority geographic locations for the study and short and long-term monitoring of OOCA were identified based on the group’s knowledge of oceanographic conditions and vulnerable regions. Longer-term actions that will help support multinational collaborations include: identifying shared data and information platforms; standardizing chemical and biological sampling methodologies; coordinating communications with regulatory agencies and resource managers; and coordinating monitoring activities, collaborative research projects, and tri-national comparisons and synthesis of findings. We present guidance from this effort for an integrated, multinational approach to understanding the causes and consequences of OOCA in the Gulf.

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Ocean change in the northeastern Atlantic and adjacent seas: a multi-dimensional challenge for the environment, society, and economy

Published 17 October 2025 Newsletters and reports Closed
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An ocean narrative is a powerful tool for making complex ocean changes better accessible while informing decision-making and inspiring collective action. This ocean narrative reports on ocean change in the northeastern Atlantic and adjacent seas and discusses its broader implications for Europe’s environment, economy, and society. The region is experiencing warming and acidification at rates exceeding the global average, with rising sea levels and record severe marine heatwaves (MHWs). These changes threaten marine ecosystems, biodiversity, cultural heritage, and key economic sectors, such as aquaculture and coastal tourism, which rely heavily on the balance and the health of the ocean. This ocean narrative emphasizes the importance of regional ocean indicators for the northeastern Atlantic and adjacent seas and underscores the importance of localized responses, as ocean changes affect regions differently, particularly in semi-enclosed seas such as the Baltic Sea, the Black Sea, and the Mediterranean Sea. The findings stress the urgency of timely action and the need to strengthen evidence-based and strategic ocean knowledge transfer at the science and policy interface for informed decision-making that balances environmental sustainability, economic resilience, and social inclusivity to address the growing challenges of ocean change in the northeastern Atlantic and its adjacent seas.

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Improving coastal ocean acidification monitoring in Maine

Published 16 October 2025 Web sites and blogs Closed
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Maine Ocean Climate Collaborative’s “Sensor Squad” has issued a two-part report on monitoring acidification.

Written by Dr. Chris Hunt of the University of New Hampshire’s Ocean Process Analysis Laboratory, Curtis Bohlen, Director of Casco Bay Estuary Partnership, Mike Doan, Friends of Casco Bay’s Staff Scientist, and Jeremy Miller of Wells National Estuarine Research Reserve, the report shares the results of their two-year study to identify affordable and reliable tools for monitoring nearshore ocean acidification.

The first part of the report, “Assessment of Coastal Ocean Acidification Monitoring in Maine,” examines the accuracy of glass-electrode data sonde pH sensors. By testing real-world results of these sensors against laboratory-controlled methods, researchers found that sondes can reliably and effectively measure coastal pH when best practices are followed.

The second part of the report outlines those best practices and standard operating procedures.

You can download the report here.

Friends of Casco Bay’s and Wells NERR’s respective continuous monitoring programs use the quality assurance and best practices outlined in the report. The Sensor Squad is committed to sharing what they have learned with organizations, researchers, and agencies that are currently collecting continuous acidification data, or are interested in doing so in the near future.

Contact Mike Doan for more information.

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A collaborative assessment of coastal ocean acidification monitoring in Maine & standard operating procedures and best practices for the collection of continuous pH data in coastal marine environments

Published 16 October 2025 Newsletters and reports Closed
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The ‘Sensor Squad’ of the Maine Ocean Climate Collaborative is the product of a 2023 Maine Coastal and Marine Climate Action Fund grant to conduct “A two-year pilot project designed to address and overcome technological barriers to ocean acidification data collection, develop protocols to elevate quality assurance and ensure comparable data, and meet regularly to discuss project results and data compilation”. The Squad consists of representatives from Friends of Casco Bay (FOCB), Wells National Estuarine Research Reserve (WNERR), and the University of New Hampshire (UNH). This report is a summary of their efforts to assess affordable, repeatable means of continuously monitoring ocean acidification.

Ocean and coastal acidification (OCA) are a growing concern, and efforts to monitor these changing and potentially damaging conditions are still emerging. This project will inform additional organizations that are working in collaborative ways to understand and track OCA and address goals of both the Maine Ocean Acidification Study Commission and the Maine Climate Council. The project involves field and lab studies to evaluate a glass electrode pH sensor, and then investigations into the use of a regression model to calculate total alkalinity as a second carbonate parameter.

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The bacterial community composition of American lobster (Homarus americanus) embryos and recently hatched larvae held under different temperature and acidification conditions

Published 16 October 2025 Science Closed
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Previous research investigating the microbial community of American lobster embryos has long led researchers to believe this habitat comprised only a select few bacterial taxa. However, using 16S rRNA gene sequencing, we show this community to be more diverse than previously thought. We investigated how the bacterial communities of American lobster embryos and larvae change over embryogenesis and hatching in response to two environmental variables. Ovigerous female lobsters caught from Maine and Massachusetts were held under varying temperature and pH regimes that approximated observed and predicted warming and ocean acidification conditions in the Gulf of Maine (GoM) and Southern New England (SNE). The bacterial microbiome associated with the lobster embryos was quantified from two-time points during the experiment, and larvae were collected within 12 hours of hatching. Alpha diversity increased with each life history stage, and embryo and larvae microbiomes shared little community overlap with that in the surrounding tank water. Neither environmental conditions nor lobster origin significantly altered bacterial communities, with life history stage driving alpha and beta diversity. Embryos and larvae shared three core bacterial members identified as members of the genera Rubritalea, Delftia, and Stenotrophomonas. American lobster embryos and larvae appear to have a highly selective microhabitat for bacteria that is not altered by environmental conditions. This leads us to wonder what role the microbiome may have on a developing lobster, and where the microbiome is originating if not from the surrounding seawater.

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Effects of multiple stressors on embryos and emerging larvae of the American lobster

Published 14 October 2025 Science Closed
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Environmental changes in the ocean can impose significant physiological costs and morphological changes to many marine organisms, and early life stages such as eggs and larvae are predicted to be particularly vulnerable to climate change drivers including warming and acidification. Although sensitivity to ocean change stressors during development has the potential to influence the performance, and ultimately the recruitment, of postlarvae and juveniles, the nature and strength of physiological modifications during embryo development is understudied in the ecologically and economically important American lobster Homarus americanus. We investigated the long-term, interactive impacts of ocean acidification and ocean warming on the development and physiology of brooded lobster embryos. We exposed ovigerous females to a combination of 2 temperatures and 2 pH levels for 5 mo, throughout which we measured development, metabolic rate, biochemical composition, and enzyme activity in their brooded embryos. The physiology of American lobster embryos appears to be robust to ocean acidification conditions but sensitive to warming, particularly for metabolic traits. We also found that warming induced a reduction in the size of freshly hatched larvae. Understanding how environmental change influences these early life stages of lobsters can improve predictions for how this species will fare in a changing ocean environment.

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From small-scale variability to mesoscale stability in surface ocean pH: implications for air–sea CO2 equilibration

Published 10 October 2025 Science Closed
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One important aspect of understanding ocean acidification is the nature and drivers of pH variability in surface waters on smaller spatial (i.e. areas up to 100 km2) and temporal (i.e. days) scales. However, there has been a lack of high-quality pH data at sufficiently high resolution. Here, we describe a simple optical system for continuous high-resolution surface seawater pH measurements. The system includes a PyroScience pH optode placed in a flow-through cell directly connected to the underway supply of a ship through which near-surface seawater is constantly pumped. Seawater pH is measured at a rate of 2 to 4 measurements min−1 and is cross-calibrated using discrete carbonate system observations (total alkalinity, dissolved inorganic carbon, and nutrients). This setup was used during two research cruises in different oceanographic conditions: the North Atlantic Ocean (December 2020–January 2021) and the South Pacific Ocean (February–April 2022). By leveraging this novel high-frequency measurement approach, our findings reveal fine-scale fluctuations in surface seawater pH across the North Atlantic and South Pacific oceans. While temperature is a significant abiotic factor driving these variations, it does not account for all observed changes. Instead, our results highlight the interplay between temperature, biological activity, and waters with distinct temperature–salinity properties and their impact on pH. Notably, the variability differed between the two regions, suggesting differences in the dominant factors influencing pH. In the South Pacific, biological processes appeared to be mostly responsible for pH variability, while in the North Atlantic, additional abiotic and biotic factors complicated the correlation between expected and observed pH changes. While our findings indicate that broader ocean-basin-scale analyses based on lower-resolution datasets can effectively capture surface ocean CO2 variability at a global scale, they also highlight the necessity of fine-scale observations for resolving regional processes and their drivers, which is essential for improving predictive models of ocean acidification and air–sea CO2 exchange.

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Interspecific vulnerabilities to elevated pCO2 in the northwestern Gulf of Mexico, a baseline of sensitivity and geochemical regimes

Published 9 October 2025 Science Closed
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Marine organisms rely on stable seawater conditions and vary in taxa-specific tolerances to environmental change. The capacity for acclimatization in marine taxa is dependent on local adaptation. Our ability to generate accurate global predictions starts in identifying regional responses, informing facets that fit globally in a mosaic of response to environmental extremes. The northwestern Gulf of Mexico (nwGoM) has not previously been isolated as a region with significant multi-taxon level comparisons under geochemical extremes. Therefore, we aim to procure a nwGoM regional baseline via a literature search in all known marine taxa’s response to elevated CO2 partial pressure (pCO2) coupled with real-time ecosystem modeling of this region. The baseline carbonate chemistry conditions indicate that pH, aragonite saturation state (Ωarag), and pCO2 exhibit greater temporal and spatial variability within the upper 20 m of the water column, with nearshore waters showing more pronounced seasonal spatial variation than offshore waters. Of the taxon reported, 68.5% reported a negative response to increased pCO2, whereas 31.4% showed a neutral or mixed neutral response (positive or negative). Only 11.4% of reported taxa showed a positive response to elevated pCO2. Shown here is a holistic negative response to increased pCO2 through collating external studies. Data was only found on 1.0% of the total species we recorded in the nwGoM region, highlighting a significant gap in our understanding of regional ecosystem wide sensitivity. Of the species shown here, 83% have habitat ranges within the top 20 m of the water column, and with seasonal variability they may be exposed to several extremes, modeled here but overlooked when compared to global predictions. Continuing experimental work on the reported species here will inform regional predictions to fit the global mosaic predicting the state of our oceans to future conditions.

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Remote sensing of coastal acidification: UAS and satellite-based estimation in the Mississippi Sound and landscape change impact assessment

Published 7 October 2025 Science Closed
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Ocean acidification results from atmospheric CO₂ absorption, while coastal acidification is more localized, influenced by nutrient runoff, freshwater input, and organic matter decomposition. Due to its complexity, specialized monitoring is essential. The present research estimated two key carbonate system parameters total alkalinity (TA) and partial pressure of carbon dioxide (pCO₂) using uncrewed aircraft systems (UAS) imagery and autonomous surface vessel (ASV) observations over an oyster reef in the Western Mississippi Sound (WMS). Field campaigns were conducted from 2018 to 2022 to collect high resolution aerial imagery over the largest oyster reef in WMS, utilizing a multispectral sensor mounted on a drone. An ASV was deployed during June, July, and September 2021 UAS missions over the same sites to collect in situ data, including pH, partial pressure of carbon dioxide (pCO2), sea surface temperature (SST), sea surface salinity (SSS), colored dissolved organic matter (CDOM), and chlorophyll-a (Chl-a). Random forest models developed and accurately estimated TA and pCO₂ (R² > 0.91). Time-series maps were generated using Chl-a images derived from UAS imagery and SSS images derived from CDOM maps, employing salinity-CDOM linear regression model developed in this study. Results demonstrate UAS effectiveness in small-scale coastal monitoring due to its high spatial resolution. However, UAS lacks spatial coverage needed for broader regions like Mississippi Sound. To address this, MODIS imagery and HYCOM model outputs were integrated with ASV data collected in June and August 2023 in this research. Random forest models using SST, SSS, and Chl-a performed well (R² = 0.81 for TA, 0.87 for pCO₂). By incorporating MODIS Level 3 SST and Chl-a (1 km) and HYCOM SSS (downscaled 4 km to 1 km), this research generated annual and monthly time-series maps of mean TA and pCO₂ over the entire Mississippi Sound for the period 2002–2020. These maps reveal spatial seasonal dynamics and long-term trends. This research also investigated how land use and land cover (LULC) changes influenced TA and pCO₂ across the entire Mississippi Sound from 2002 to 2020. Spatial correlation and trend maps revealed associations between eight LULC class type changes and TA and pCO₂ patterns. The findings suggest connections between environmental changes and carbonate system responses but do not confirm causation, instead providing a basis for hypothesis generation and further study of biogeochemical processes. Overall, this dissertation highlights how combining remote sensing, in situ measurements, machine learning technique, and LULC analysis improves coastal acidification assessment in the Mississippi Sound.

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Elevated pCO2 and temperature levels modulate the ratios of the photosynthetic methane production to CO2 fixation in the coccolithophorid Emiliania huxleyi

Published 6 October 2025 Science Closed
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Most phytoplankton species have been shown to release methane (CH4) during photosynthesis; however, little has been documented on how changed levels of CO2 at different temperatures affect their CH4 production along with photosynthetic C fixation. Here, we examined CH4 production and photosynthetic performance in the most cosmopolitan coccolithophorid, Emiliania huxleyi, grown under high (1000 μatm, HC) and ambient (415 μatm, LC) pCO2 levels at five temperatures (16, 20, 22, 24 and 27°C). The HC treatment slightly lowered the optimal temperature for growth and CH4 production, and temperature changes significantly affected both carbon fixation and CH4 production. Under suboptimal temperatures, increasing temperature from 16 to 20°C led to about 96% increase in CH4 production per POC and HC treatment further enhanced this increase by an additional 9%. In contrast, under super-optimal temperatures, a temperature rise by 4°C reduced the microalgal CH4 production per POC under HC treatment by about 24% compared to the control. The calculated CH4 production quotient (MPQ, CH4 released vs. CO2 fixed) ranged between 2 × 10−5−6 × 10−5, and showed a decreasing trend with increasing temperature under both pCO2 levels, implying that the CH4 production by this microalga is being affected by global ocean changes, and the CH4 produced by phytoplankton should be quantified and included in assessing the feedback of marine phytoplankton to climate change.

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New Jersey ocean acidification action plan

Published 3 October 2025 Science Closed
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The NJDEP created an Ocean Acidification Action Plan  to address ocean and coastal acidification. Left unchecked, this global issue will negatively impact the balance of the ecosystem as well as the state’s fish and shellfish industries. Shellfish are particularly vulnerable through the impacts of acidification on shell formation.

The New Jersey Ocean Acidification Action Plan identifies steps that the NJDEP has already taken that can help mitigate ocean and coastal acidification and outlines the Department’s next steps to better understand the current conditions and prepare for additional impacts of ocean and coastal acidification.

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In-situ measurements reveal alkalinity release from cold-temperate seagrass meadows

Published 25 September 2025 Science Closed
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Highlights

  • Cold-temperate seagrass meadows are net sources of alkalinity
  • Alkalinity generation exceeds soil organic carbon accumulation by fourfold
  • Seagrasses buffer ocean acidification locally during the day
  • Alkalinity generation in seagrasses is lower than in mangroves and saltmarshes

Abstract

Understanding the carbon sequestration potential of blue carbon ecosystems is important to inform climate policies and to guide restoration and protection efforts. Alkalinity generation is an often overlooked carbon sequestration mechanism, especially in seagrass meadows. Here, we quantified total alkalinity (TA) and dissolved inorganic carbon (DIC) fluxes in two cold-temperate Zostera marina seagrass meadows in Sweden using 24-hour in-situ chamber incubations at the end of the high-productivity season. The seagrass meadows were similar net sources of TA (16 ± 45 mmol m-2 d-1 in Smalsund, 17 ± 16 mmol m-2 d-1 in Bökevik), whereas DIC fluxes were highly variable (34 ± 59 mmol m-2 d-1 in Smalsund, -43 ± 35 mmol m-2 d-1 in Bökevik). Fluxes followed a diurnal cycle consistent with photosynthesis-respiration cycles. As a result, seagrass meadows ameliorated ocean acidification locally during the day, but not during the night. The large CO2 uptake provided higher buffering levels compared to mangroves and saltmarshes. The TA fluxes were comparable to those reported for Mediterranean and tropical seagrass meadows, but 16-times lower than in mangrove forests and 5-times lower than in saltmarshes. Alkalinity generation in these cold-temperate seagrasses exceeded soil organic carbon stocks accumulation by fourfold, potentially contributing to their carbon sequestration potential and warranting inclusion in seagrass meadow carbon budgets.

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Development of a chemical sensor for the measurement of dissolved inorganic carbon in seawater

Published 18 September 2025 Science Closed
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The thesis presents the development of a novel, autonomous DIC sensor for seawater measurements. The work details a stepwise sensor development process from a bench-top prototype to a fully submersible system. Both versions operate on a conductometric detection principle in combination with a gas diffusion sequential injection analysis : (i) a custom-made four-hollow brass electrode detection cell, and (ii) a custom-made gas exchange unit with a “Tube In A Tube” configuration. 

The bench-top analyzer was validated through laboratory experiments and tested in multiple field trials. Each measurement required 15 minutes. It achieved an analytical precision of measurement of ± 4.9 and 9.7 μmol kg-1 in laboratory and field deployments, respectively, meeting ‘Weather Quality’ standards for ocean carbonate measurements. Based on the success of the bench-top analyzer, an in-situ version was developed, retaining the core architecture. It featured a compact and pressure-resistant housing suitable for shallow water deployments. The in-situ sensor was deployed in multiple field trials and demonstrated an analytical precision of measurement of < 20 μmol kg-1, with each measurement completed in 20 minutes. 

The high-frequency DIC data collected during field deployments in the North Sea and the Kiel Fjord provided new insights into the short-term variability and environmental drivers of carbonate system dynamics in coastal and estuarine systems. These data resolved high spatial and temporal resolution which overcomes the limitations of traditional discrete sampling method and demonstrated the potential of the analyzer to enhance carbonate system monitoring.

Overall, the work in this thesis showed the development of a novel, cost-effective, and autonomous DIC analyzer with an aim to address a critical technological gap in marine biogeochemical research.

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Statistical models for the estimation of pH and aragonite saturation state in the Northwestern Gulf of Mexico

Published 4 September 2025 Science Closed
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Historical water column carbonate measurements have been scarce in the Gulf of Mexico (GOM); thus, the progression of ocean acidification (OA) is still poorly understood, especially in the subsurface waters. In the literature, statistical models, such as multiple linear regression (MLR), have been created to fill OA data gaps in different ocean regions. Additionally, machine learning techniques such as random forest (RF) have been used in model creations for both the open ocean and marginal seas. However, there is no statistical model for subsurface carbonate chemistry parameters (i.e., pH and ΩArag) in the GOM. By creating models with various architectures built upon the relationships between commonly measured hydrographic properties (e.g., salinity, temperature, pressure, and dissolved oxygen or DO) and carbonate chemistry parameters (e.g., pH and aragonite saturation state, or ΩArag), data gaps can be potentially filled in areas with insufficient sampling coverage. In this study, two statistical models were created for pH and ΩArag in the northwestern GOM (nwGOM) within the range of 27.1–29.0˚N and 89–95.1˚W using both MLR and RF methods. The calibration data used in the models include salinity, temperature, pressure, and DO collected from seven cruises that took place between July 2007 and February 2023. The models predict ΩArag with R2 ≥ 0.94, mean square error (MSE) ≤ 0.04, and pH with R2 ≥ 0.93, MSE ≤ 0.0005. Both the MLR and RF models perform similarly. These models are valuable tools for reconstructing pH and ΩArag data where direct chemical observations are absent but hydrographic information is available in the nwGOM. Nevertheless, potential shifts in circulation, water mass changes, and accumulation of anthropogenic CO2 need to be accounted for to improve and revise these models in the future.

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Ocean acidification disrupts the biomineralization process in the oyster Crassostrea virginica via intracellular calcium signaling dysregulation

Published 3 September 2025 Science Closed
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Anthropogenically increased atmospheric carbon dioxide (pCO2) leads to ocean acidification, disrupting calcification in marine calcifiers by reducing the saturation state of calcium carbonate. Calcium is not only a crucial component in the shell and skeleton structure but also serves as an essential second messenger for regulating biomineralization across many species. Ocean acidification is well-studied as causing shell dissolution in a diversity of bivalve species by disordering calcium deposition. However, it remains unclear whether the calcium-mediated signaling pathway regulating biomineralization is also affected. This study assessed eastern oyster (Crassostrea virginica) to determine how calcium signaling responds to elevated pCO₂ and influences shell formation. Under elevated pCO2, increased intracellular calcium concentration was found in primary epithelial cell cultures from oyster mantle. Meanwhile, we observed upregulation of calmodulin, a primary sensor of intracellular calcium, while its downstream effector, calcineurin, was downregulated. In addition, four conserved shell matrix proteins (SMPs), representing shell construction conditions, were significantly upregulated in the CO2-exposed mantle cells. In vivo, larval C. virginica exhibited developmental stage-dependent alterations in calcium signaling and SMPs disarrangement stimulated by pCO2. We hypothesize that dysregulation of calcium signaling disrupts the expressions of SMPs and causes oyster shell deformation. Pharmaceutical blockage of the calcium-calmodulin binding induced abnormal expression of related genes and shell matrix changes consistent with those caused by elevated pCO2, both in vivo and in vitro. Importantly, calcineurin restored SMPs expression in CO2-treated mantle cells. These findings suggest that shell deformities under ocean acidification are related to disruption of the calcium-calmodulin signaling pathway, inhibiting calcineurin activity and affecting SMPs production.

Continue reading ‘Ocean acidification disrupts the biomineralization process in the oyster Crassostrea virginica via intracellular calcium signaling dysregulation’

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