Pacific cod gene expression analysis reveals how changing oceans impact larvae

Published 20 February 2026 Press releases Leave a Comment
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A new study used gene expression analysis to explore how temperature and ocean acidification affect Pacific cod larvae. Scientists discovered that larvae are equipped with genes that allow them to survive cool and acidified conditions. However, warming may cause mortality by depleting energy and triggering inflammatory responses. These mechanisms are possible links between changes in ocean conditions and the recruitment of young fish in the Gulf of Alaska Pacific cod population.

Decrease in Pacific Cod Population

Pacific cod is a highly valued commercial fishery, and cod also play a key role in the ecosystem as both predator and prey. However, cod populations in Alaska have declined in recent years. Decreased population size is likely linked to recent marine heat waves, and early life stages seem to be the most impacted. Scientists predict that marine heatwaves may be more common in the future and that ocean acidification will intensify, particularly at high latitudes.

Experiments have shown that Pacific cod are sensitive to temperature during their early life stages. Temperature influences how their eggs develop, how their bodies use energy, and how they grow and survive as larvae. We don’t know as much about the impacts of ocean acidification.

In a 2024 study at the NOAA Fisheries Alaska Fisheries Science Center, scientists raised Pacific cod from embryos to larvae at multiple temperatures (3°C, 6°C, 10°C). To examine the potential interaction between temperature and ocean acidification, they also raised them in water that replicated current ocean conditions and in more acidified conditions. This mimicked conditions projected for the end of this century. The study found that larval mortality was very high in warm water but the effect of acidification was more complex.

The effects of temperature and acidified conditions depended on the fish’s development stage. Scientists need to better understand how changing ocean conditions can affect important species like Pacific cod, and whether these species can adapt to these changes.

A Deeper Dive with Gene Expression

This new molecular study examined larvae to understand why heat wave temperatures might cause larvae to die at high rates. “Finding larvae that are dying in the field is very unlikely, but we were able to sample experimental larvae that we knew were dying rapidly due to warming,” said Emily Slesinger, researcher at NOAA’s Alaska Fisheries Science Center. They also sampled larvae exposed to other conditions. The experiments simulated more acidified water and colder temperatures which Pacific cod larvae currently experience in some regions and years. Slesinger continues, “The unique thing about this study’s approach is to look beyond whether these larvae live or die under different conditions, but to understand why through gene expression analysis.”

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Blue carbon ecosystems and coral reefs as coupled nature-based climate solutions

Published 20 February 2026 Science Leave a Comment
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Restoring coastal ecosystems offers more than just carbon storage: it can also help bring coral reefs back to life. This Perspective explores how the carbon captured by mangroves and other blue carbon systems could be used to support reef restoration, creating a powerful synergy between climate action and marine conservation. By aligning ecological benefits with innovative funding strategies, this approach offers a practical path towards more resilient coastlines and more durable climate solutions.

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Short-term mechanisms, long-term consequences: molecular effects of ocean acidification on juvenile snow crab

Published 20 February 2026 Science Leave a Comment
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Understanding how marine species tolerate acidified conditions is critical for predicting biological responses to ocean change. A recent one-year experiment (Long 2026) found that juvenile snow crab (Chionoecetes opilio) maintain growth and molting under acidification (pH 7.8, 7.5), and survival begins to decline only after ∼250 days under severe acidification (pH 7.5). In this companion study, we characterized whole-transcriptome responses after 8 hours and 88 days of exposure to identify molecular mechanisms underlying short-term tolerance and chronic effects of ocean acidification. The immediate transcriptional response involved strong activation of genes associated with mitochondrial metabolism and biogenesis, protein homeostasis, cuticle maintenance, and immune modulation, processes shared between moderate and severe treatments but of greater magnitude under severe acidification. After 88 days, expression patterns diverged, revealing sustained upregulation of stress- and damage-mitigation pathways in the severe treatment (pH 7.5) compared to the moderate treatment (pH 7.8). These findings indicate that crabs in severe acidification are likely to experience chronic OA stress that precedes outward physiological effects, and provides a mechanistic basis for delayed mortality. We further highlight potential early indicators of chronic acidification stress in snow crab, among which a gene likely coding for carbonic anhydrase 7 (CA7, GWK47_031192) appears to be the most promising biomarker.

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Indo-Pacific coral reef sponge diversity declines under predicted future ocean conditions

Published 19 February 2026 Science Leave a Comment
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Future oceans are predicted to favor groups like sponges over calcifying taxa such as scleractinian corals. Here, we test this hypothesis by examining the development of coral reef communities in experimental mesocosms over 23 months. 85 sponge species among the calcifying class Calcarea (~33%), and non-calcifying Demospongiae (~60%) and Homoscleromorpha (<10%) recruited to warming (+2°C), acidification (-0.2 pH), and warming+acidification (+2°C, -0.2 pH) future ocean treatments. The diversity of calcifying sponges was unimpacted across any treatment, whereas non-calcifying classes showed greatest declines. 57-66% of demosponges decreased under future ocean conditions, and homoscleromorphs were entirely absent from acidified treatments. Through the sponge loop, sponges play a fundamental role in coral reef nutrient cycling, and altered coral reef community composition likely has functional consequences. This study challenges the assumption that non-calcifying species are less impacted and highlights the importance of understanding how community composition may alter ecosystem functioning under future ocean conditions.

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Metrological assessment of pHT in TRIS buffers within artificial seawater: implications for high-salinity reference materials

Published 19 February 2026 Science Leave a Comment
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Anthropogenic CO2 emissions drive ocean acidification through changes in the carbonate system, lowering seawater pH. In contrast, salinity variations arise from physical processes such as freshwater fluxes and circulation. This study reports the preparation and Harned cell characterization of three equimolal TRIS buffer solutions (0.01 mol·kg−1, 0.025 mol·kg−1, and 0.04 mol·kg−1) in artificial seawater (ASW) matrices with practical salinities of 35 and 50 and temperatures of 20 °C, 25 °C, and 30 °C. Determined pHT values achieved expanded uncertainties (𝑈pHT ≤ 0.006), meeting Global Ocean Acidification Observing Network (GOA-ON) “climate” quality standards. Absolute salinity (SA) was concurrently measured via density (TEOS-10), revealing systematic deviations from practical salinity due to TRIS content. A nonlinear regression model was developed to predict pHT as a function of salinity, temperature, and TRIS molality, with r2 = 0.99998. These results provide a robust dataset for developing Certified Reference Materials (CRMs) for pHT calibration under climate-relevant high-salinity environments at different temperature conditions, offering a practical tool for high-accuracy calibration in variable marine conditions.

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Molecular indicators of warming and other climate stressors in larval Pacific cod

Published 19 February 2026 Science Leave a Comment
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Recent marine heatwaves in the Gulf of Alaska negatively impacted Pacific cod (Gadus macrocephalus) through a series of failed year classes and poor recruitment to the fishery. Experimental work by Slesinger et al. (2024) corroborated the hypothesis that warming directly impacts recruitment by increasing larval mortality rates. In this companion study, we applied transcriptomics with larvae from Slesinger et al. (2024) to better understand how warming affected their physiology and identify potential mechanisms contributing to mortality. RNASeq data reveal that warm-exposed larvae have unique gene expression profiles that may reflect high levels of inflammation, lipid dysregulation or depletion, and altered development of visual systems and neurological pathways. Warming may therefore cause a metabolic mismatch whereby energy-demanding activities (development, inflammation, growth) exceed energy production capacity despite access to prey. We also report the less pronounced transcriptional differences in larvae exposed to cold, acidification, and a combination of stressors reflecting future climate scenarios. This information will guide future genetic and experimental work that will ultimately inform recruitment forecasts in years with conditions similar to those tested here.

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Experimental observations on ultrastructure of scales of red seabream (Pagrosomus major) for seawater pH monitoring

Published 18 February 2026 Science Leave a Comment
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Ocean acidification monitoring relies predominantly on field test and numerical modeling, while bioindicators are emerging as practical and economic approaches for seawater pH monitoring. Here, we report indoor dissolution experiments on the scale of red seabream (Pagrosomus major) under varied pH (from 7.1 to 7.9), showing that the mean aspect ratio of ventral ctenii and caudal/ventral lepidonts negatively correlated with pH. We propose to employ these ultrastructures of fish scale to be a novel bioindicator for marine pH reconstruction. This semiquantitative proxy would be applicable to both contemporary biomonitoring and paleo-oceanic pH reconstruction for the extensive occurrences of fish in modern oceans and fossil records.

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Population-level transcriptomic datasets from two benthic invertebrates exposed to long-term experimental warming and acidification

Published 18 February 2026 Science Leave a Comment
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Ocean warming and acidification are major drivers of change in marine ecosystems, with particularly strong impacts on low-mobility benthic organisms. Despite their ecological importance, genomic and transcriptomic resources for sponges (Phylum: Porifera) and marine gastropods (Phylum Mollusca) that capture responses to long-term, combined climate stressors and population-level variability remain limited. Herein, we present population-level RNA-seq datasets from the sponge Chondrilla nucula and the gastropod Hexaplex trunculus, collected from northern and southern Aegean Sea (Eastern Mediterranean) populations and exposed for three months to elevated temperature and reduced pH in a common garden experiment simulating near-future climate change conditions. The datasets comprise high-quality paired-end Illumina reads, a complete de novo transcriptome assembly for C. nucula, and genome-guided alignments for H. trunculus. These datasets provide a valuable resource for investigating transcriptional plasticity and climate change resilience in benthic marine invertebrates.

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A biogeochemical perspective on acidification and buffering capacity in the Piscataqua Estuary

Published 18 February 2026 Science Leave a Comment
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Coastal acidification is influenced not only by rising atmospheric CO2 and river-ocean mixing, but also by metabolic processes that alter seawater carbonate chemistry and buffering capacity. This study examines how sedimentary biogeochemical processes contribute to carbonate system variability in the Piscataqua Estuary, a tidally dynamic channel connecting Great Bay to the Gulf of Maine. The biogeochemical processes considered include sedimentary aerobic respiration, denitrification, sulfate reduction, and carbonate dissolution or precipitation. Two incubation experiments were conducted in September and October of 2024 at the University of New Hampshire’s Coastal Marine Laboratory (CML) to quantify changes in pH, dissolved inorganic carbon (DIC), and total alkalinity (TA) in the overlying water arising from sediment-water biogeochemical exchange. Sediment cores were collected to be paired with overlying water from slack low and slack high tides during each month. Across both experiments, sediment cores consistently exhibited greater acidification and larger shifts in DIC and TA concentrations compared to water-only cores, indicating strong sedimentary biogeochemical influence. Among the processes considered, sulfate reduction is likely the most influential driver of carbonate system variability, contributing to increases in both DIC and TA. Linking experimental results to in-situ measurements at CML revealed that variability observed over individual ebb or flood tides primarily reflected processes associated with tidal advection (ie, river-ocean mixing and water-column biogeochemical activity). However, when evaluating net changes over both tidal transitions (ebb and flood), contributions from sedimentary biogeochemical processes were comparable in magnitude to those of the other processes during September and October. Sedimentary biogeochemical processes also appear to exert more consistent contributions to DIC and TA than water-column biogeochemical processes. Together, these findings demonstrate that sedimentary biogeochemical processes play a major role in regulating carbonate system variability in the Piscataqua Estuary. This study underscores the importance of examining carbonate system variability across multiple timescales to obtain a more comprehensive understanding of estuarine carbonate dynamics. Additional experimental work is needed to further resolve the influence of metabolic processes on coastal carbonate systems under changing environmental conditions.

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Shrinking shellfish? Risk of acidic water in the Indian River Lagoon

Published 17 February 2026 Press releases Leave a Comment
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Researchers, Boat

FAU researchers measured aragonite saturation – a key indicator of water’s ability to support calcifying organisms like clams and oysters – throughout the Indian River Lagoon.

Florida’s Indian River Lagoon (IRL), one of the state’s most ecologically productive estuaries, is facing a growing but invisible threat that could reshape its marine ecosystems. Over the past decade, the lagoon has suffered severe degradation caused by nutrient pollution, excessive freshwater runoff, harmful algal blooms (HABs), and declining water quality. These changes have led to the loss of tens of thousands of acres of seagrass and have negatively impacted shellfish, fish, dolphins, manatees and other key species.

A new study from Florida Atlantic University’s Harbor Branch Oceanographic Institute now reveals that these pressures are also contributing to coastal acidification, a chemical shift in the water that threatens the ability of shell-building marine organisms to grow and thrive. 

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To understand these changes, FAU Harbor Branch researchers studied the IRL from 2016 to 2017, measuring Ωarag and other water chemistry factors. They examined how nutrients, freshwater inputs, and other environmental conditions affect the lagoon’s ability to support shell-building marine life.

The study used two approaches. First, researchers conducted a broad survey across the lagoon, from nutrient-rich northern areas to southern regions affected by freshwater inflows. Second, they did weekly sampling at three central sites with different salinity and land-use conditions: an urban-influenced canal, a river mouth affected by urban and agricultural runoff, and a relatively natural reference site with strong ocean exchange.

Results of the study, published in the journal Marine Pollution Bulletin, revealed clear patterns. Northern sites with high nutrient concentrations and frequent HABs had lower aragonite saturation. Southern sites, influenced by freshwater discharges, also had lower Ωarag, primarily due to reduced salinity and dilution of aragonite. In the weekly surveys, Ωarag was positively correlated with salinity and negatively correlated with nutrient levels, confirming that both freshwater input and nutrient pollution play a role in controlling water chemistry.

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The silent shift: how ocean acidification and rising temperature affect marine organisms

Published 17 February 2026 Science Leave a Comment
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The increased absorption of carbon dioxide from the atmosphere is the cause of ocean acidification. This has an adverse effect on marine calcifiers such as corals and shelled mollusks by lowering ocean pH and altering carbonate chemistry. Global warming-induced increases in ocean temperatures have serious repercussions for marine life as well, upsetting food webs, changing species ranges, and compromising physiological functions. The early life stages of shelled mollusks, such as gastropods and bivalves, are the most susceptible to the effects of ocean acidification. The growth, shell production, and survival of both juvenile and adult mollusks can be adversely affected by ocean acidification. The nutritional value of phytoplankton, the foundation of the marine food chain, may be impacted by ocean acidification. This may limit zooplankton’s ability to develop and reproduce, and higher trophic levels. The detrimental effects on marine ecosystems can be intensified by the interaction of ocean acidification, heat, deoxygenation, eutrophication, and pollution. Marine resources like fisheries and aquaculture are seriously threatened by ocean acidification and climate change, which might have negative social and economic effects. Reducing CO2 emissions, preserving and repairing marine habitats, and putting sustainable resource management techniques into practice are some ways to deal with these problems.

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Linking surface pCO2 variability to physical processes along a continental shelf–ocean transect in the southwestern Atlantic Ocean during austral autumn and winter

Published 17 February 2026 Science Leave a Comment
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The southwestern South Atlantic Ocean is an important global sink of atmospheric carbon dioxide (CO2), driven by increased primary productivity in a nearby region where oligotrophic warm currents converge with nutrient-rich cold waters. However, uncertainties remain regarding CO2 dynamics and the role of physical processes in CO2 uptake across this region. Here, we assess variations in surface partial pressure of CO2 (pCO2) and air–sea CO2 fluxes in the Southwest Atlantic, along a transect from the continental shelf to the open ocean at 34.5°S during austral autumn 2018 and winter 2019. High-resolution spatial measurements of the temperature, salinity, and molar fraction of surface CO2 were conducted. In autumn 2018, the shelf region acted as a source of CO2 to the atmosphere (median of 3.2 mmol CO2 m-2 d-1), which was partially offset by a sink (median of –2.5 mmol CO2 m-2 d-1) in the open ocean. In contrast, the entire transect in winter 2019 presented median CO2 emissions of ~1.5 mmol CO2 m-2 d-1, which differs from climatological estimates. The spatial and seasonal variations in surface ocean pCO2 were linked to variable hydrodynamic processes, including water masses and mesoscale structures. Our findings reveal that, in one of the most productive oceanic waters worldwide, pCO2 may be influenced by distinct continental inputs (e.g., rivers, runoff, and groundwater discharge) and water masses (e.g., Tropical Water, Plata Plume Water and Subtropical Shelf Water). Therefore, the local hydrodynamic processes can modulate high spatial and seasonal variability in CO2 exchange at the ocean–atmosphere interface, with potential implications for regional and global carbon budgets. General results, such as climatological, cannot fully capture the influence of regional upwelling and continental water input, which highlights the importance of high-resolution regional observations.

Continue reading ‘Linking surface pCO2 variability to physical processes along a continental shelf–ocean transect in the southwestern Atlantic Ocean during austral autumn and winter’

Seasonal air-sea CO2 flux dynamics in Colombia’s Gorgona Marine Area during La Niña 2021–2022

Published 17 February 2026 Science Leave a Comment
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Air–sea CO₂ fluxes in tropical coastal zones are strongly influenced by ENSO variability, but in situ measurements in the Eastern Tropical Pacific remain scarce. We assessed seasonal CO₂ dynamics around Gorgona Island (Panama Bight, Colombian Pacific) under La Niña 2021–2022. From November 2021 to July 2022, we conducted monthly sampling at seven stations spanning the Guapi River plume to the open ocean, measuring physical (SST, SSS, thermocline depth), chemical (TA, DIC, pH, carbonate system parameters), and biological (chlorophyll-a) variables, and estimating net CO₂ fluxes (FCO₂) with the Liss and Merlivat (1986) parameterization and atmospheric CO₂ from NOAA. La Niña featured a cool-water anomaly (−0.78 °C), enhanced precipitation (+59%) and river discharge (+44%) relative to multi-year means. The nine-month mean CO₂ flux was near neutral (−0.01049 ± 0.00014 mol C m⁻²) but strongly seasonal: six post-upwelling months showed slightly positive fluxes (0.00929 ± 0.000147 mol C m⁻²) associated with high precipitation (746.4 ± 214.7 mm), warmer SST (27.5 ± 0.4 °C), elevated pCO₂w (567 ± 97.5 µatm) and lower pH (7.869 ± 0.040), whereas three upwelling months showed slightly negative fluxes (−0.00119 ± 0.00010 mol C m⁻²) with reduced precipitation (165.8 ± 82.4 mm), cooler SST (26.5 ± 0.2 °C), lower pCO₂w (461 ± 92.8 µatm) and higher pH (7.968 ± 0.048). La Niña amplified pCO₂w variability (316–839 µatm) via vertical Ekman pumping, horizontal transport (Zonal Ekman Transport, tides), and freshwater inputs, while a persistent thermocline (10–40.1 m) restricted deep CO₂-rich waters from reaching the surface. Biological uptake further modulated outgassing, as evidenced by chlorophyll-a and ΔDIC dynamics. Overall, CO₂ fluxes were relatively low compared with other tropical estuarine and oceanic sources. These results underscore the need for sustained in situ observations in estuarine–ocean systems to refine predictive models of CO₂ fluxes under ENSO conditions.

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Seaweeds (Ulva, Gracilaria) significantly increase the growth rates of North Atlantic oysters, scallops, and clams grown in an aquaculture setting

Published 17 February 2026 Science Leave a Comment
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Highlights

  • Seaweeds significantly increased the growth rates of oysters by 20–70%, of clams by 60–70%, and of scallops by 130–140%.
  • Seaweeds caused significant increases in pH, DO, and the saturation state of calcium carbonate (Ω).
  • Seaweeds caused a significant increase in the concentrations of suspended chlorophyll a.
  • Co-culture of seaweeds with bivalves accelerates the growth rate of bivalves by increasing pH, DO, Ω, and food availability.

Abstract

While bivalve populations are threatened by climate change stressors including ocean acidification and hypoxia, the photosynthetic activity of seaweeds can raise the pH and dissolved oxygen (DO) of seawater, combatting these stressors. Here, three commercially important North Atlantic bivalves (Eastern oysters, Crassostrea virginica; hard clams, Mercenaria mercenaria; bay scallops, Argopecten irradians) were grown in the presence and absence of two common seaweeds (Ulva sp. and Gracilaria sp.) in replicated 300 L outdoor aquaculture tables with flow-through seawater. Environmental conditions including pH, DO, and chlorophyll a were continuously monitored and levels of dissolved inorganic carbon and the complete carbonate chemistry of seawater were quantified. The presence of seaweeds significantly increased shell- and tissue-based growth rates of oysters by 20–70%, of clams by 60–70%, and of scallops by 130–140% (p < 0.05) with both seaweeds being similarly effective. Both seaweed species caused significant increases in pH, DO, and the saturation state of calcium carbonate (Ω) during the day (p < 0.05) whereas differences at night were muted with night-time Ωaragonite levels being at or below saturation in all treatments. In some experiments, the presence of seaweeds caused a significant increase in the concentrations of suspended chlorophyll a, suggesting that seaweeds increased the total amount and diversity of food available to bivalves. Collectively, this study demonstrates that the co-culture of seaweeds with bivalves in a land-based aquaculture setting can significantly accelerate the growth rate of bivalves by increasing pH, DO, Ω, and food availability.

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Metabolic rate measurements of two benthic invertebrates under simulated climate change conditions

Published 16 February 2026 Science Leave a Comment
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Climate change is profoundly altering marine ecosystems through ocean warming and acidification. These stressors are especially pronounced in the Mediterranean Sea, a climate change hotspot projected to warm faster than the global average. Increased temperatures and reduced pH directly affect metabolic processes in marine invertebrates by elevating respiration rates up to species-specific thermal limits, beyond which physiological performance declines. Ocean acidification further disrupts metabolic processes by increasing energetic maintenance costs. Sessile and sedentary marine invertebrates, such as sponges and benthic gastropods, are particularly exposed to such environmental shifts due to their limited ability to escape unfavorable conditions, making physiological plasticity and local adaptation crucial for persistence.

This manuscript presents a dataset of oxygen consumption rates and wet weight measurements for two low-mobility marine species, the gastropod Hexaplex trunculus and the sponge Chondrilla nucula. Using a common garden experiment, individuals from North and South Aegean populations were exposed for three months to simulated climate change conditions combining increased temperature and reduced pH. The dataset documents respiration measurements obtained using metabolic chambers after three months of exposure, allowing comparisons across species, geographic origin, and experimental treatments.The dataset accounts for intraspecific variation in these responses, providing insight into potential adaptive differences among geographically distinct populations. These data provide a resource for future analyses of metabolic responses of marine invertebrates to combined warming and acidification conditions.

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Acute microbial and nutrient responses to elevated temperature and pCO2: a coastal UK microcosm study

Published 13 February 2026 Science Leave a Comment
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The coastal ocean’s ecosystem resilience is consistently hampered by the compounding impacts of projected climate change and anthropogenic perturbation. In this microcosm study, we investigated how elevated temperature and pCO2, together with episodic nutrient pollution and a short-term marine heatwave, affect the nano- and picoplanktonic community of primary producers and subsequent changes in coastal biogeochemistry. Our study demonstrates that future elevated temperature and pCO2 conditions impact the planktonic community, first by a ∼ 50 % decreased autotrophic abundance, and second by a shift from larger eukaryotic to smaller cells. When combined with a heatwave, total primary producers experienced an additional 37–38 % decrease, indicative of a negative synergistic effect beyond either stressor alone. Picoeukaryotes were particularly sensitive, declining by 44–50 %. Short-term nutrient pollution under ambient conditions induced a 41 % increase in cell abundance, but failed to stimulate biomass under elevated temperature and pCO2, and instead led to altered organic matter dynamics, including significantly lower carbon fixation. These findings emphasize the need for further evaluation of multi-stressor interactions to better understand biogeochemical vulnerability, nutrient retention, and ecological functioning in coastal ecosystems undergoing rapid climatic and anthropogenic change.

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Carbon concentration mechanisms in Canary Islands macroalgae and their implications for future benthic community structure under ocean acidification

Published 12 February 2026 Science Leave a Comment
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In recent decades, due to the anthropogenic CO2 concentration increase in the atmosphere, the chemistry of seawater has been seriously altered, producing the phenomenon known as Ocean Acidification (OA). Of all the dissolved inorganic carbon (DIC) present in seawater, only 1% is in the form of CO2. However, if anthropogenic CO2 emissions to the atmosphere continue, it will no longer be a limiting resource. Part of the response of marine photosynthetic organisms to these changes depends on their carbon physiology. The presence and effectiveness of carbon concentration mechanisms (CCM) can define the production and growth of macroalgae under OA conditions. Although CCMs are not essential when the seawater concentration of inorganic carbon is high, species that do not use them can see their performance improved. Our goal was to determine the presence or absence of CCMs in a total of 19 species of common macroalgae in the Canary Islands through a pH drift experiment and to establish their primary production rates through incubations and measurements of the O2 variation. Samples of each species were incubated during 8, 24 and 32 h in isolated containers and under controlled lighting and temperature conditions. Of the 19 species studied, 11 presented CCM and 8 did not present CCM. Five of the eight species that did not show the presence of CCMs in the present study are present in the CO2 seeps of Fuencaliente and one of them, H. scoparia is a dominant species.

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A systematic review of the ocean acidification research in India: research trends, gaps and recommendations

Published 11 February 2026 Science Leave a Comment
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Ocean acidification, a consequence of climate change, has become a significant threat to marine organisms. Globally, tremendous efforts have been made to understand its impact on different ecological and biological processes. In India, this research area is still not fully explored, but expanding at an exponential rate. Hence, it is essential to consolidate the fragmented knowledge into a systematic review, which will assist future researchers to develop their work. In this study, we utilized the Scopus, Web of Science and Ocean Acidification-International Coordination Centre bibliography to conduct a systematic review of ocean acidification research in India. We used the Biblioshiny package in R to conduct a bibliometric analysis, identify spatial and temporal research trends, and highlight the growth of literature in ocean acidification research, as well as existing knowledge gaps. We used the following keywords: ocean acidification, lowered pH, acidifying ocean, elevated carbon dioxide, elevated CO2, marine carbonate chemistry, shell decalcification and affiliation as India to obtain relevant publications. We selected 353 publications by applying relevance filtering and adherence to PRISMA guidelines. Almost one-third of the publications were non-primary articles. Among research articles, only 71 publications were found to investigate the response of marine organisms to ocean acidification. Majority of them involved single stressors, for a short term on very limited taxa. Lack of molecular-level investigation, multifactorial experimental design, and long-term observations were major gaps. This review aims to support researchers, policymakers, and other stakeholders involved in the planning, monitoring, and developing adaptation strategies. Finally, it provides recommendations for future research and policy development.

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Summary of ocean acidification data collected by the National Coral Reef Monitoring Program in the U.S. Pacific Islands, 2021—2023

Published 10 February 2026 Newsletters and reports Leave a Comment
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Coral reefs are among the most biologically diverse and economically valuable ecosystems on earth. They provide billions of dollars annually in food, jobs, recreation, coastal protection, and other critical ecosystem services (Brander & van Beukering, 2013; Costanza et al., 2014). However, these ecosystems are also among the most vulnerable to ocean acidification (OA). Even under the most optimistic model projections, increasing atmospheric and seawater carbon dioxide concentrations are likely to occur over the next few decades, decreasing seawater pH and reducing the availability of the carbonate ion (CO32-) building blocks that corals and other marine calcifiers use to construct reef habitat (Chan & Connolly, 2013; Jiang et al., 2023). OA threatens the persistence of coral reefs by reducing rates of coral and crustose coralline algae (CCA) calcification and accelerating rates of bioerosion, thereby lowering net production of calcium carbonate (CaCO3) and compromising the structural complexity and integrity of three-dimensional reef habitat (Cornwall et al., 2021; Hill & Hoogenboom, 2022). As a result, many of the ecological, economic, and cultural values offered by coral reefs could be significantly impacted by OA over the next century.

NOAA’s National Coral Reef Monitoring Program (NCRMP) provides a framework for long-term, national-level monitoring of the U.S.-affiliated coral reef areas. Funded jointly by the NOAA Coral Reef Conservation Program and Ocean Acidification Program, NCRMP assesses the status and trends of U.S. coral reef ecosystems and supports the management of the nation’s reefs (NOAA Coral Program, 2021). NCRMP’s long-term monitoring of OA and related coral reef ecosystem responses (NCRMP-OA) evaluates patterns and trends in carbonate chemistry and key ecosystem indicators across gradients of biogeography, oceanographic conditions, habitat types, and human impacts. These data sets are used to inform the efficacy of place-based coral reef management in close collaboration with federal, state, and jurisdictional partners.

To assess the progression of OA and impacts on coral reef ecosystems in the U.S. Pacific Islands, NCRMP-OA monitoring includes the following objectives:

  • Conduct carbonate chemistry sampling to monitor spatial variability and temporal change in pH, aragonite saturation state (Ωar), and other carbon system parameters;
  • Conduct diel carbonate chemistry water sampling and oceanographic instrument deployments at select sites;
  • Conduct census-based carbonate budget assessments to estimate rates of coral reef biological carbonate production and erosion.

This report summarizes the monitoring effort and results from 2021–2023 NCRMP-OA sampling and surveys. Additional NCRMP environmental, benthic, and fish data are not included in this report, but they can be accessed at the links provided in the Data Availability section.

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Microbial community dynamics over large spatial and environmental gradients in a subtropical ocean basin

Published 9 February 2026 Science Leave a Comment
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Microbes are fundamental to ocean ecosystem function, yet they remain understudied across broad spatial and environmental scales in dynamic regions like the Gulf of America/Gulf of Mexico (GOM). We employed DNA metabarcoding to characterize prokaryotes (16S V4–V5) and protists (18S V9) across 51 stations, spanning 16 inshore–offshore transects and three depths. Cluster analysis revealed three clusters corresponding to depth zones that integrated vertical and horizontal sampling: photic zone (inshore near surface–bottom and offshore surface), deep chlorophyll maximum (offshore), and aphotic zone (offshore near bottom). We applied group-specific generalized additive models (GAMs) to log-transformed abundance data of major taxa in the photic zone, identifying key environmental factors that explained 42%–82% of the variation in abundance. SAR11 and SAR86 were positively associated with temperature and dissolved inorganic carbon, while cyanobacterial genera (Prochlorococcus and Synechococcus) were differently impacted by nutrients, salinity, and pH in ways that often followed their expected ecological niches. Representatives of protist parasites (Syndiniales) and grazers (Sagenista) showed group-specific nonlinear associations with salinity, oxygen, nutrients, and temperature. Using GAMs, we expanded the spatial resolution of DNA sampling and predicted surface log abundances at 84 cruise sites lacking amplicon data. Indicator analysis was performed with sequence-level data, revealing several protists that were indicative of more acidic waters and the absence of any significant prokaryote indicators. Our results provide the first basin-scale survey of microbes in the GOM and highlight the need for coordinated omics and environmental sampling to improve predictions of microbial responses to changing conditions.

Continue reading ‘Microbial community dynamics over large spatial and environmental gradients in a subtropical ocean basin’

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