Posts Tagged 'North Atlantic'

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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.

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

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.

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

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.

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Temporal dynamics of the carbonate system in a tropical rhodolith bed from a protected Caribbean bay

Published 1 September 2025 Science Closed
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Coastal zones are key players in the global carbon cycle, yet the temporal dynamics of their carbonate system, particularly in tropical rhodolith habitats, remain understudied. This study assessed seasonal and spatial variability in carbonate chemistry in Gairaca Bay, a protected tropical bay within Tayrona National Natural Park, Colombian Caribbean. Sampling was conducted in 2023–2024 across three habitats: a rhodolith bed (1, 7, 15 m depth), the bay entrance (outer bay, 10 m depth), and a shallow sandy-bottom area (inner bay, 1 and 6 m depths). Temperature, salinity, and total scale pH (pHT) were measured in situ; total alkalinity (TA) was determined via open-cell titration, and dissolved inorganic carbon (DIC), pCO2, bicarbonate (HCO3–), carbonate (CO32-), and aragonite saturation state (Ωarag) were calculated. Seasonal and spatial patterns were analyzed using PERMANOVA. Significant seasonal differences were found in temperature (F = 248.42, p < 0.05), salinity (F = 49.02, p < 0.05), TA (F = 7.65, p < 0.001), and DIC (F = 2.54, p < 0.001), with no significant variation among sites or depths. Upwelling periods were cooler and saltier (25.9 ± 1.14 °C; 34.48 ± 0.46), with elevated TA and DIC, and slightly lower pHT and Ωarag. Non-upwelling periods were warmer (30.0 ± 0.76 °C), less saline (33.36 ± 0.28), and had higher pHT and Ωarag. Seasonal delta analysis indicated greater variability during non-upwelling, linked to enhanced freshwater discharge. The outer bay showed the highest variability in pHT and Ωarag, while the inner bay was most stable for TA and DIC. The rhodolith bed bottom exhibited high TA variability but stability in pHT and Ωarag, especially during non-upwelling. Seasonal processes, including upwelling and freshwater inputs, drive carbonate system variability in Gairaca Bay. The stability of pHT and Ωarag in the rhodolith bed bottom suggests a potential role as a biogeochemical refuge in acidification-prone tropical environments.

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What doesn´t kill you makes you stronger: the sea urchin Arbacia lixula living on volcanic CO2 vents

Published 1 September 2025 Science Closed
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Anthropogenic CO2 emissions drive ocean acidification (OA), which reduces seawater pH and carbonate ion availability, threatening calcifying organisms such as sea urchins. This study examines the long-term effects of OA on Arbacia lixula using a natural volcanic CO2 vent at Fuencaliente, La Palma (Canary Islands) as an analogue of future conditions. We analyzed the external morphology, skeletal strength, mineralogy, and growth of A. lixula across three sites that differed consistently in mean pH (from 8.14 to 7.65 during low tide). Sea urchins from low pH conditions were smaller, with shorter spines and reduced jaw-to-diameter ratios, yet their tests showed higher fracture resistance than those from ambient conditions. Additionally, individuals from acidified zones showed altered growth dynamics, with fewer growth rings. Skeletal changes and growth alterations are consistent with modified mineralization processes and dietary shifts toward non-calcareous food sources. This study highlighting the morphological plasticity and resilience of A. lixula under persistent natural acidification, offering insight into how sea urchins may respond in a high-CO2 ocean.

Continue reading ‘What doesn´t kill you makes you stronger: the sea urchin Arbacia lixula living on volcanic CO2 vents’

Wind control of the interannual ocean-biogeochemical variability in the South Atlantic Bight

Published 29 August 2025 Science Closed
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In the South Atlantic Bight (SAB), changes in the strength and proximity to the coast of the Gulf Stream are thought to be primary factors determining the shelf-break upwelling rate. However, it is still not clear if and to what extent those factors influence cross-shelf nutrient fluxes and shape the ocean biogeochemistry at interannual and longer timescales. Here, we use a high-resolution regional ocean-biogeochemical model, an ocean reanalysis product, and a satellite-derived chlorophyll dataset to investigate the interannual ocean-biogeochemical variability in the SAB during 1993-2022. Regional model outputs suggest that year-to-year changes in phytoplankton production are indeed largely driven by upwelling of cold and nutrient-rich water to the shelf-break. The upwelling variability, reflected in bottom temperature and vertically integrated production patterns, is strongly linked to surface velocity changes in the Gulf Stream near the shelf break, but weakly related to the depth-integrated Gulf Stream transport. The Gulf Stream’s velocity changes, and the temperature and production anomalies, are well correlated to the alongshore wind stress, suggesting that local wind is the leading driver of the shelf-break upwelling variability. Those relationships are also supported by circulation patterns from ocean reanalysis and satellite chlorophyll anomalies. Finally, we examine the simulated carbonate system changes linked to the slope-shelf interchanges, finding that shelf-break upwelling significantly increases bottom acidification, a pattern linked to the low carbonate concentration in the slope waters. Our study thus provides new insight to better constrain the impacts of the Gulf Stream and local wind on the SAB biogeochemical variability.

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Within and cross-generational effects of elevated seawater pCO2 on larval bay scallops Argopecten irradians (L)

Published 27 August 2025 Science Closed
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Bivalve larvae are highly susceptible to ocean acidification (OA), but there is little knowledge of the capacity of bivalve species to acclimate or adapt to changing ocean conditions. It is challenging to compare results among studies of OA reported in the literature, as there is little consistency among studies in water chemistry across OA treatments used or how OA conditions were determined. In addition, it is difficult to predict from short-term experiments how populations might respond across generations. The bay scallop, Argopecten irradians, is a good model species for such experiments because of its short generation time and importance commercially and ecologically. Bay scallops were exposed to OA conditions from embryos to metamorphosis across two generations. Ocean acidification treatment levels included historical or preindustrial “low” (pCO2 ∼450 µatm), current average “moderate” (∼800 µatm), and future “high” (∼1,350 µatm). In the first generation, high OA had negative effects on larval performance, with no survival to metamorphosis, preventing its inclusion in the second generation. Moderate OA reduced performance (survivorship and growth) relative to the low OA. In the second generation, however, there was no difference in survival between the moderate and low OA treatments, but the difference in size at metamorphosis remained. These results suggest that over two generations, bay scallops either acclimated or adapted to moderate OA. Further work is needed to determine the extent to which long-term, generational adaptation to OA is possible in the bay scallop.

Continue reading ‘Within and cross-generational effects of elevated seawater pCO2 on larval bay scallops Argopecten irradians (L)’

The development and plasticity of acid excretion mechanisms in early life stage red drum, Sciaenops ocellatus

Published 21 August 2025 Science Closed
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Highlights

  • Components of acid-base pathways are present and stable in very early development.
  • NHE3 is localized to the apical pit of epithelial ionocytes.
  • Epithelial proton excretion is responsive to elevated CO2 and governed by NHEs.
  • nhe2/3 transcript abundance is elevated following development in high CO2.
  • Low level CO2 causes reductions in survival.

Abstract

Ocean acidification (OA) has been shown to affect early life stage fishes in a variety of ways, including reduced survival and growth, and increased tissue damage. Yet, there is also substantial interspecies variability in the sensitivity of early life stage fishes to high CO2, and it has been theorized that this may relate to the ontogeny of systemic acid-base regulatory pathways; an area that has been surprisingly understudied in obligate marine species. Here, we used an integrative set of approaches to describe the development and plasticity of acid excretion pathways in developing red drum (Sciaenops ocellatus), a marine fish native to the Gulf of Mexico. We observed mRNA expression of relevant transporters and ionocytes immediately post-hatch (36 h post-fertilization, hpf) with relatively stable abundance throughout the pre-metamorphic stages. Consistent with work in adults and seawater acclimated euryhaline larvae, we demonstrate strong co-localization of acid excretion proteins within a single epithelial ionocyte cell-type. Measurements of epithelial Δ[H]+, an indicator of proton efflux, showed that by 72 hpf larvae had CO2-responsive EIPA-sensitive acid excretion, confirming the presence of sodium proton exchanger (NHE)-mediated acid excretion. Elevated mRNA expression of nhe2 and nhe3 was induced following exposure to 5500 and 12,000 μatm CO2, which coincided with the absence of further survival effects relative to lower dose CO2. Overall, these data confirm that red drum have fully functional epithelial acid excretion pathways in early life, and that plasticity in these pathways may offer survival benefits.

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Ocean and coastal acidification monitoring priorities for the Northeast US and Eastern Canada

Published 20 August 2025 Newsletters and reports Closed
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The Interagency Working Group on Ocean Acidification Monitoring Prioritization Plan 2024 calls for Coastal Acidification Networks to identify the ocean and coastal acidification (OCA) monitoring needs most important for their regions. The Northeast Coastal Acidification Network (NECAN) organized a webinar series to study regional needs, which culminated with a workshop in November 2023. This workshop led to the identification of six priority new Monitoring Needs in addition to the maintenance of current monitoring efforts:

  • Improve spatial and temporal scale of monitoring co-located OCA variables and biological measurements to better resolve variability of acidification dynamics in concert with biological processes
  • Increase subsurface monitoring to understand how conditions vary at depth
  • Increase the number of high-frequency monitoring assets that measure at least two of four carbon parameters
  • Increase near-real-time and rapid response observing capacity for episodic events
  • Determine fluxes and rates that would help parameterize and constrain regional modeling efforts to understand past conditions and project future trends
  • Increase spatial coverage of “climate”-quality observations

This report presents monitoring needs and opportunities for consideration by coastal managers, decision makers, researchers, and monitoring groups. It offers options to apply new capacity or funding to the expansion of OCA monitoring in the NECAN region. Writing the report led to the identification of eight cross-cutting actions which will lead to the implementation of these Monitoring Needs:

  1. Expand monitoring beyond carbonate chemistry to provide a complete assessment of OCA, its effects, and future trends.
  2. Enhance or leverage existing monitoring platforms for a cost-effective and collaborative approach to creating a more complete OCA monitoring system in the NECAN region.
  3. Expand the NECAN membership to include protected area experts, terrestrial biogeochemists and hydrologists, fisheries experts, social scientists, Tribal liaisons, project leads from large assessments, and other important stakeholders, rights holders and decision makers.
  4. Increase funding in the Northeast to both sustain currently-stretched efforts and grow a more robust ocean acidification monitoring program.
  5. Pursue immediate implementation of proxy approaches or interim strategies for measurements with technological or capacity limitations, while new technologies are being developed.
  6. Synthesize monitoring information to advance the understanding of OCA in the region.
  7. Deploy monitoring assets strategically, with end-user needs in mind, ensuring that the collected data is accessible, relevant, and useful for decision-making.
  8. Share NECAN’s experience in developing these recommendations with other Coastal Acidification Networks and regional monitoring programs.
Continue reading ‘Ocean and coastal acidification monitoring priorities for the Northeast US and Eastern Canada’

A climate vulnerability assessment for U.S. highly migratory fishes in the Atlantic Ocean

Published 18 August 2025 Science Closed
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Climate change will continue to alter key physical and biological oceanographic processes throughout the global ocean, modifying environmental conditions for U.S. highly migratory fish species found in the Atlantic Ocean. The Atlantic Highly Migratory Species Climate Vulnerability Assessment evaluated the vulnerability of 58 species and stocks to projected ocean conditions, using a combined qualitative and quantitative analysis of species sensitivity (physiological, ecological, and behavioral attributes) and estimated exposure to possible future ocean stressors. Key modeled environmental variables included bottom and sea surface temperature, sea surface oxygen, and ocean acidification (pH), whereas the most influential biological attributes considered were population growth rate, stock size, and stock status. We produced vulnerability rankings (i.e., low, moderate, high, and very high) based on biological attribute sensitivity and exposure to the environmental variables, and separate analyses including estimated ability of distributional shifts, predicted directional effects of climate change, certainty, and data quality scores for the species and stocks assessed, with exceptions for species with undetermined geographic distributions. Of the 58 species and stocks assessed, 4 had very high vulnerability to climate change, 14 had high vulnerability, 22 had moderate vulnerability, 6 had low vulnerability, and 12 could not be assigned a rank. The majority (n = 45) of species and stocks had high ability for distributional shifts in response to projected changes in climate. Further, directional effect results suggest that climate change impacts on the majority of species and stocks will be neutral, implying that these species have life history or behavioral traits that impart some level of resilience and adaptability to the impacts of climate change. These results provide information for use in ecosystem-based fisheries management, particularly for prioritization of vulnerable species and stocks in conservation activities and research endeavors.

Continue reading ‘A climate vulnerability assessment for U.S. highly migratory fishes in the Atlantic Ocean’

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