Posts Tagged 'North Pacific'

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Seawater pH fluctuations during the Ordovician to Silurian transition: insights from δ11B records in carbonates

Published 26 February 2026 Science Closed
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Highlights

  • A positive δ11Bcarb excursion has been observed during the Hirnantian coinciding with Gondwana glaciation.
  • Seawater pH fluctuations during the OST are caused by declining atmospheric pCO₂, sea level fall and carbonate weathering.
  • The fluctuation of seawater pH exerted a crucial role in the climatic changes and biotic evolutions during the OST.

Abstract

Environmental changes during the Ordovician to Silurian transition (OST) and the cause of Late Ordovician Mass Extinctions (LOMEs) remain a subject of debate. This study presents the first continuous seawater pH record spanning the Late Ordovician and Early Silurian, based on carbonate boron isotope (δ11Bcarb) data obtained from a carbonate-dominated section in South China. Our results reveal predominantly stable δ11Bcarb values throughout the Late Ordovician and Early Silurian, punctuated by a positive δ11Bcarb excursion during the Hirnantian coinciding with Gondwana glaciation. The calculated seawater pH pattern indicates a generally low pH baseline across the OST, temporarily interrupted by a transient increase in surface ocean pH coinciding with the glacial episode. These pH fluctuations are interpreted to result from a combination of factors, including declining atmospheric pCO₂ levels, sea level changes, weathering of carbonate rocks, and decomposition of organic matter. This study suggests that the fluctuation of seawater pH exerted a crucial role in the climatic changes and biotic evolution during the OST. The enhanced carbonate weathering and increased seawater pH, together with sea level fall and a reduction in shelf area, likely contributed to the decreased net accumulation of carbonates and represented a negative feedback for the development of glaciation and cooling climate. Given that the living of organisms (e.g. brachiopod, conodont, sponge and radiolarian) was sensitive to the changes in seawater pH, if and how the seawater pH fluctuations affected the LOMEs still needs more detailed work in the future.

Continue reading ‘Seawater pH fluctuations during the Ordovician to Silurian transition: insights from δ11B records in carbonates’

Ocean acidification reduces diatom and photosynthetic gene abundance on plastic in an coastal bay mesocosm experiment

Published 25 February 2026 Science Closed
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Discarded plastics are accumulating in the global ocean and posing threat to marine life. The plastisphere – the community colonizing plastic surfaces – profoundly influences plastic’s environmental behavior, affecting its degradation and entry into marine food webs. Ocean acidification (OA) resulted from anthropogenic CO2 emissions, is also threatening marine ecosystems, but the effect of OA on the structure and ecological function of the plastisphere community remains poorly understood. Here, using a mesocosm experiment, we investigated the effects of OA on the plastisphere colonizing floating PET plastic bottles. The study was conducted using subtropical eutrophic coastal water from Southern China under two CO2 conditions: increased CO2 to 1000 μatm (HC) and ambient CO2 410 μatm (LC). Metagenomic sequencing of the plastic samples, after exposure for 32 days, showed striking changes in relative abundance of eukaryotes and bacteria caused by HC. There was a 75.3 % decrease in eukaryote read abundances at high CO2, most strikingly a 95.6% decrease in the relative abundance of diatoms. In addition, the relative abundance of genes involved in photosystem II light reactions and pigment synthesis decreased under high CO2 conditions. This suggests that OA could reduce the photosynthetic potential within the plastisphere. Shifts in plastisphere community structure and potentially diminished photosynthesis under OA could influence the food chains within plastisphere, plastic degradation, transportation, and carbon cycle involving plastics. Overall, our results suggest that OA can alter the functional ecology of the plastisphere, with potential implications for marine biogeochemical processes and food web dynamics in subtropical eutrophic coastal water.

Continue reading ‘Ocean acidification reduces diatom and photosynthetic gene abundance on plastic in an coastal bay mesocosm experiment’

Understanding the resilient carbon cycle response to the 2014–2015 Blob event in the Gulf of Alaska using a regional ocean biogeochemical model

Published 24 February 2026 Science Closed
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Marine heatwaves (MHWs), characterized by anomalously high sea surface temperatures, are occurring with increasing frequency and intensity, profoundly impacting ocean circulation, biogeochemistry, and marine ecosystems. The MHW known as the Blob, which persisted in the subarctic NE Pacific from 2014 to 2015, significantly affected surrounding ecosystems. Warming-induced solubility reduction is expected to raise the partial pressure of carbon dioxide (pCO2) in the surface water, causing outgassing of CO2 to the atmosphere. Outgassing of CO2 is another source of atmospheric CO2 in addition to anthropogenic fossil fuel burning. However, moored observations at Ocean Station Papa (OSP; 145° W, 50° N) shows a moderate decrease in oceanic pCO2 during the Blob, resisting the warming-induced outgassing of CO2. This response is opposite of what is expected from warming alone, and instead has been attributed to reductions in dissolved inorganic carbon (DIC), although the mechanisms driving this reduction have remained unclear. We employed a regional model that accurately reproduces the temporal variability of oceanic pCO2 at OSP to investigate the cause of decrease pCO2 during the Blob. The analysis of model outputs indicates that the observed oceanic pCO2 decline resulted from the offset between warming-induced solubility reduction (increasing pCO2) and weakened physical transport of DIC (decreasing pCO2), with the latter dominating. Both horizontal and vertical transports played important roles. The near-surface carbon budget over the broad region was primarily driven by changes in the vertical transport. The decrease in DIC during the Blob resulted from the suppression of upwelling of DIC-rich subsurface waters in the winter of 2013. In this period, the horizontal transport also contributed substantially to DIC reduction. In particular, at OSP, the effect of the horizontal transport was comparable to that of the vertical transport, reflecting the northward advection of low-DIC water masses. These findings indicate that changes in physical circulation were the primary driver of the moderately enhanced CO2 uptake observed during the Blob. This study provides a critical insight into the complexity of biogeochemical response to extreme warming events and underscores the importance of resolving physical transport processes in assessing oceanic carbon uptake during MHWs.

Continue reading ‘Understanding the resilient carbon cycle response to the 2014–2015 Blob event in the Gulf of Alaska using a regional ocean biogeochemical model’

Shell-shocked: local oyster farmers confront a changing climate

Published 24 February 2026 Media coverage Closed
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For more than a century, oyster aquaculture has thrived in Morro Bay’s waters, but our changing climate now poses a significant threat to this multi-million-dollar industry. Local farmers are implementing innovative solutions to protect their operations as ocean acidification becomes an increasing concern.

Beneath the waves in Morro Bay, nearly 5 million oysters are growing. Onshore, the hands of shuckers work quickly to keep up with demand.

…

However, changing climate conditions are putting aquaculture at risk. Temperature and pH changes, particularly ocean acidification, are creating new challenges for oyster farmers.

Nick Soares from the Morro Bay National Estuary Program works closely with the farmers in the bay and with the research teams keeping a close eye on the bay. He stated, “Temperature, pH being the big one, like ocean acidification, these are all things that we’re very aware of.”

At Cal Poly’s Center for Coastal and Marine Science, researchers are studying these impacts. In Dr. Emily Bockmon’s research lab, students and professors are documenting how rising atmospheric CO2 levels are affecting seawater chemistry. Learn more about her research here!

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Pacific cod gene expression analysis reveals how changing oceans impact larvae

Published 20 February 2026 Press releases Closed
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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.”

Continue reading ‘Pacific cod gene expression analysis reveals how changing oceans impact larvae’

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

Published 20 February 2026 Science Closed
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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.

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

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

Published 19 February 2026 Science Closed
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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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Molecular indicators of warming and other climate stressors in larval Pacific cod

Published 19 February 2026 Science Closed
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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 Closed
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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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Seasonal air-sea CO2 flux dynamics in Colombia’s Gorgona Marine Area during La Niña 2021–2022

Published 17 February 2026 Science Closed
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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.

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

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 Closed
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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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Ocean acidification, hypoxia, and harmful algal Bbloom solicitation now open – letters of intent due March 6, 2026

Published 4 February 2026 Jobs Closed
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OPC is pleased to announce the release of a California Climate Investments solicitation: Monitoring, Research, and Modeling to Support Ocean Acidification, Hypoxia, and Marine Harmful Algal Bloom Management in California. Projects should enhance scientific understanding of ocean acidification and hypoxia (OAH) and/or marine harmful algal blooms (HABs) to advance the State’s response related to these two growing threats to California’s coastal ecosystems and communities.

The solicitation will support projects that will strengthen California’s capacity to track, assess, and address the impacts of OAH on marine biota and ecosystems (Track 1); as well as support state management actions to prevent, mitigate, and control the impacts of HABs (Track 2). More detailed research priorities can be found in the solicitation.

Upcoming events & important dates:

OPC staff will be hosting a public webinar about the solicitation on Tuesday, February 10, 2026 from 2:00 p.m. to 3:00 p.m. Learn about solicitation priorities, timeline, and application process.

Register for the Webinar

Join OPC staff for office hours on Thursday, February 12, 2026 from 1:00 p.m. to 2:00 p.m. Applicants will have the opportunity to ask questions and receive guidance ahead of the upcoming deadlines.

Register for the Office Hours

Submit a Letter of Intent 

Letters of intent (LOI) are due Friday, March 6, 2026 by 5:00 p.m. LOI applicants invited to submit a full proposal will be notified by April 13. Full proposals are due Friday, June 12, 2026 by 5:00 p.m. (only applicants who have submitted an LOI may submit a full proposal). See the solicitation for the full timeline.

Contact

For more information, please contact Kyla Kelly, OPC Water Quality Program Manager (kyla.kelly@resources.ca.gov) with the subject line “OPC OAH/HABs solicitation”.

Continue reading ‘Ocean acidification, hypoxia, and harmful algal Bbloom solicitation now open – letters of intent due March 6, 2026’

Parental exposure to ocean acidification impacts the larval development and transcriptome of the Pacific oyster Crassostrea gigas

Published 2 February 2026 Science Closed
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Atmospheric carbon dioxide (CO2) levels are escalating at an unprecedented rate, leading to the phenomenon of ocean acidification (OA). Parental exposure to acidification has the potential to enhance offspring resilience through cross-generation plasticity. In this study, we analyzed larval growth and transcriptomic profiles in the Pacific oyster, Crassostrea gigas, a species of significant ecological relevance, under both control and elevated CO2 conditions experienced by their parental generation. Our findings indicate that the oyster populations exposed to OA exhibited a higher incidence of abnormalities during the D-shaped larval stage, followed by accelerated growth at the eyed stage. Through a comparative transcriptomic investigation of eyed larvae (25 d after fertilization), we observed that parental exposure to OA substantially influenced the gene expression in the offspring. Genes associated with lipid catabolism and shell formation were notably upregulated in oysters with parental OA exposure, potentially playing a role in cross-generational conditioning and conferring resilience to OA stressors. These results underscore the profound impact of OA on oyster larval development via cross-generational mechanisms and shed light on the molecular underpinnings of cross-generation plasticity.

Continue reading ‘Parental exposure to ocean acidification impacts the larval development and transcriptome of the Pacific oyster Crassostrea gigas’

Photoaged microplastics disrupt the response of marine medaka (Oryzias melastigma) to ocean acidification: perspectives from energy metabolism and ammonia production

Published 2 February 2026 Science Closed
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Ocean acidification (OA) and microplastics (MPs, <5 mm) are co-occurring stressors that threaten marine ecosystems. Although the marine environment contains multiple pollutants, OA can alter the environmental behavior of MPs, influencing their toxicity and environmental fate. Therefore, investigating the interactive effects of OA and MPs is essential. Fish can activate physiological compensatory mechanisms to adapt to OA; however, it remains unclear how MPs affect these mechanisms. In this study, marine medaka were exposed to acidified seawater (pH 7.70) containing environmentally relevant concentrations of MPs (0.1 mg/L) for 90 days to investigate the disruptive effects of MPs on responses to OA. The results showed that while OA triggered compensatory energy metabolism reprogramming to enhance ammonia production, MPs disrupted this process, reducing the TCA cycle intermediate α-ketoglutarate. This α-ketoglutarate deficiency limited the glutamate supply for ammonia production. Simultaneous inhibition of glutamate dehydrogenase activity further limited glutamate availability. As a result, MPs reduced the level of ammonia production by 25.29%, compromising the ability to neutralize excess H+. Crucially, photoaging exacerbated this toxicity, leading to a 32.04% reduction in ammonia production. This study demonstrates that MPs interfere with fish responses to OA via α-ketoglutarate-mediated metabolic reprogramming, highlighting a vulnerability in marine organisms facing climate change scenarios.

Continue reading ‘Photoaged microplastics disrupt the response of marine medaka (Oryzias melastigma) to ocean acidification: perspectives from energy metabolism and ammonia production’

Ocean acidification effects on growth, survival and physiological immunity of farmed Larimichthys crocea

Published 29 January 2026 Science Closed
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Ocean acidification has become a significant global ecological issue, particularly in coastal regions with intensive aquaculture. Fish farming is a crucial component of global food security, yet research on the impact of acidification on the aquaculture performance of economically important teleosts remains limited. In this study, we reared the fast-growing large yellow croaker (Larimichthys crocea) for 30 days under three different pH conditions: severe acidification (LA, pH 7.4), moderate acidification (MA, pH 7.8), and control (HA, pH 8.1). We comprehensively evaluated growth performance, survival rate, tissue structure, antioxidant enzyme activity, and innate immunity. The results showed that the LA group exhibited suppressed growth (significantly lower than the MA group, p < 0.05), elevated cortisol and T4 levels (p < 0.05), and trends of reduced antioxidant enzyme and innate immune enzyme activities, along with organ-specific pathological changes (vacuolation, structural loosening) in gills, liver, kidneys, and intestines, though most indices showed no significant difference from the HA group. Notably, the MA group showed optimal growth performance, stable physiological and immune responses. In conclusion, while acidification did not markedly affect the survival rate of L. crocea, severe acidification (pH 7.4) induces stress responses and tissue damage. These findings suggest that L. crocea exhibits a certain degree of tolerance to the acidification conditions tested, as several physiological parameters were not significantly affected. However, when considering the overall set of observations, including histological alterations across multiple tissues and changes in plasma and tissue parameters, long-term exposure to severe acidification (pH 7.4) appears to induce tissue damage and stress-related physiological disturbances, indicating potential health risks. This study provides empirical evidence regarding the potential risk posed by projected ocean acidification on L. crocea aquaculture and supports the development of climate change adaptation strategies for coastal mariculture.

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Flow as a mediator of ecosystem engineering: hydrodynamics shape chemical modification by kelp and mussel beds

Published 28 January 2026 Science Closed
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Ecosystem engineers are organisms that modify their physical and chemical surroundings in ways that shape the structure and function of ecological communities. Physically, they build biogenic structures that modify flow, light, and habitat complexity. Chemically, they change oxygen and pH levels through metabolic processes such as photosynthesis and respiration. These modifications can either facilitate the presence of associated species by creating favorable microhabitats or inhibit them by amplifying environmental stress. Understanding the circumstances under which and how these shifts occur has become increasingly important as climate change intensifies environmental variability in coastal ecosystems. Advancing our understanding of how ecosystem engineers shape their communities requires considering how external factors, particularly flow, mediate their influence on the surrounding environment. Driven by tides, waves, and currents, flow regulates water residence time and thus the accumulation or dispersion of biologically modified water. Yet despite its central importance, the role of flow in controlling the strength and direction of ecosystem engineering remains poorly understood.

This dissertation examines how local hydrodynamics influences the capacity of marine ecosystem engineers to modify their surrounding chemical environments. It focuses on two contrasting but complementary systems: an autotroph, bull kelp (Nereocystis luetkeana), and a heterotroph, mussels (Mytilus spp.). Looking across these systems provides a broader view of how different types of engineers—those that produce oxygen through photosynthesis and those that consume it through respiration—shape their local chemical environments. By studying both systems, this work links two aspects of ecosystem engineering: 1) oxygen production and depletion, and 2) explores how flow determines when these species have the potential to act as facilitators or inhibitors within their communities. I combined field observations with laboratory and field experiments to explore how flow dynamics interact with biological traits, such as canopy structure, density, and behavior, to determine when these engineers act as facilitators or inhibitors within their communities. Across chapters, the work progresses from identifying environmental controls on kelp-driven chemical modification (Chapter 1) to isolating mechanistic feedbacks between flow, mussel behavior, and chemistry (Chapter 2), and then investigating density effects on chemistry and behavior by out-planting manipulated mussel aggregations in natural conditions (Chapter 3).

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Transgenerational effects of extreme weather on Manila clam resilience: implications for aquaculture sustainability

Published 27 January 2026 Science Closed
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Highlights

  • SAE+MHW synergistically impaired clams during reproduction.
  • Progeny exhibited lasting developmental delays and high mortality.
  • Long-term physiological dysfunction persisted into later life stages.
  • Compound extremes threaten bivalve aquaculture resilience.

Abstract

Extreme environmental events, including sea acidity extremes (SAE) and marine heatwaves (MHW), pose increasing threats to coastal aquaculture species. This study examined the individual and combined effects of SAE and MHW on Manila clams (Ruditapes philippinarum) and their transgenerational impacts. Adults exposed to SAE+MHW showed reduced survival, decreased condition index, lower clearance rate (CR) and assimilation efficiency (AE), elevated ammonia excretion (ER), and negative scope for growth, indicating disrupted energy budgets. Reproductive output and gonadal development were also compromised. Offspring from stressed parents exhibited lower larval survival, stunted shell growth, reduced metamorphic success, smaller settlement size, reduced juvenile (6-month-old) survival rate and disrupted energy homeostasis, revealing persistent transgenerational impacts on development and energy homeostasis. These findings suggest that parental exposure to synergistic SAE+MHW alters energy allocation and may involve epigenetic mechanisms, ultimately impairing offspring fitness. Overall, our study demonstrates that compound extreme events can severely affect metabolic resilience and cross-generational performance in Manila clams, highlighting the need for multigenerational assessments, selective breeding, and aquaculture strategies to enhance climate resilience.

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Neurometabolic rewiring in squid (Sepioteuthis lessoniana) optic lobes drives behavioral plasticity and visual integration under environmental acidification

Published 20 January 2026 Science Closed
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Ocean acidification’s impacts on marine animal behavior have substantial implications for ecosystem stability. Understanding how key predators respond to acidification is crucial for predicting future ocean food web dynamics, yet the underlying neural mechanisms remain poorly understood. Here, we show that prolonged exposure to projected year 2100 acidification conditions substantially impairs predatory behavior in bigfin reef squid (Sepioteuthis lessoniana), a key invertebrate predator. Chronic acidification exposure reduces expression of acetylcholine receptors in optic lobes and alters systemic HCO₃⁻ levels and metabolic rates. Using custom electroretinogram recordings, we find that while basic visual processing remains intact, behavioral impairments likely stem from changes in downstream neural integration pathways. Transcriptomic expression analysis reveals broad reductions in energy metabolism and synaptic signaling under acute exposure, while chronic exposure induces compensatory upregulation of cellular maintenance pathways. Our findings demonstrate that while squids maintain visual capabilities through adaptive mechanisms, the energy-intensive processes of neural integration and behavioral execution are compromised. These results highlight the complex physiological trade-offs marine predators face under ocean acidification, with implications for understanding future shifts in marine ecosystem structure and function.

Continue reading ‘Neurometabolic rewiring in squid (Sepioteuthis lessoniana) optic lobes drives behavioral plasticity and visual integration under environmental acidification’

Integrated biochemical profiling, comparative transcriptome and weighted gene co-expression network analysis to explore the response mechanism of global warming and ocean acidification to the stress of Sepia esculenta larvae

Published 16 January 2026 Science Closed
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Highlights

  • Multi-angle analysis of Sepia esculenta under global warming and ocean acidification.
  • Stress enhanced the immune defense and antioxidant defense of S.esculenta.
  • The hub genes closely related to stress resistance were identified and screened out.
  • Provided a theoretical basis for the breeding of fine varieties and pond culture.

Abstract

The Sepia esculenta has high economic value and nutritional value, and accounts for a high proportion of the catch of cephalopods in China ‘s coastal waters. Global warming and ocean acidification, as major environmental problems currently facing the world, have a serious negative influence on the survival and breeding of S. esculenta. Therefore, in the research, transcriptome sequencing and biochemical quantitative analysis were performed on the larvae of S. esculenta after high temperature, low pH and combined stress at different time points, and the differential expressed genes (DEGs) and response mechanisms were identified. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that these DEGs were mainly involved in a large number of immune-related biological processes and signaling pathways, including Immune response、Phagocytosis、Regulation of DNA-templated transcription and Positive regulation of DNA-templated transcription. Then, we further explored the functional relationship between these DEGs by constructing weighted gene co-expression network and protein-protein interaction networks. We identified ten hub genes including HSP90AA1, ALDH1L1, VPS13A, MAPK8IP1 and KDM6A. These hub genes may play an important role in the face of high temperature, low pH and their combined stress at different times. Our findings not only elucidate the molecular response mechanisms of S. esculenta to environmental stress and delineate the key regulatory pathways underlying its adaptation, but also provide a theoretical foundation for advancing pond cultivation.

Continue reading ‘Integrated biochemical profiling, comparative transcriptome and weighted gene co-expression network analysis to explore the response mechanism of global warming and ocean acidification to the stress of Sepia esculenta larvae’

Interannual variability of oceanic pH in a highly human-perturbed bay in China

Published 15 January 2026 Science Closed
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Due to anthropogenic carbon dioxide (CO2) emissions, open oceans are acidifying, and the acidification rate is relatively stable. While coastal waters experience even greater pH fluctuations from terrestrial inputs, upwelling, and biological activity, this variability necessitates detailed long-term research in these regions. Based on field observations and historical literature data from 1980 to 2016, the interannual variability of seawater pH and its driving mechanisms were analyzed in Jiaozhou Bay, a highly human-perturbed bay in China. The results revealed an overall decreasing trend in pH over the three-decade period, with a decline rate of 0.0062 years−1, which is 3.6 times faster than that observed in the open ocean, indicating significant anthropogenic impacts on pH variations in Jiaozhou Bay. The long-term pH changes showed strong correlations with coastal environmental pollution status, characterized by three distinct phases: a decline from 1980 to 1986, followed by an increase during 1991 to 2004, and subsequently another decreasing trend from 2004 to 2016. Terrestrial (including wastewater) inputs were identified as predominant anthropogenic factors influencing these pH variations. Furthermore, this study highlights that while future management should focus on reducing organic matter and nutrient inputs, particular attention should be paid to the direct impacts of dissolved inorganic carbon (DIC) from treated wastewater discharge on pH reduction.

Continue reading ‘Interannual variability of oceanic pH in a highly human-perturbed bay in China’

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