This study aimed to investigate the meiofauna community characteristics in coastal waters affected by ocean acidification. Therefore, the meiofauna communities in the coastal waters of Hupo in Uljin-gun, which showed a high ocean acidification trend in the integrated data on the coastal areas of South Korea for the previous ten years, were monitored over five years. During the study period, the mean abundance of total meiofauna communities expressed in population density was 614 individuals (Inds.)/10 cm2. The most dominant taxa were nematodes (65–70%) and harpacticoids (7–20%); these two taxa accounted for approximately 80% of the total meiofauna abundance. Station (St.) 5 and 10, which had the lowest seawater pH values, showed the lowest average abundance values for harpacticoids (average 46 Inds./10 cm2) and nauplius (average 4 Inds./10 cm2) among the major meiofaunal groups over the 5-year period. In addition, St. 5 indicated the lowest meiofaunal diversity index of 0.54. To examine the effect of ocean acidification on meiofauna communities at the species level, species of nematodes, the most dominant taxon, were analyzed. The results indicated that the number of nematode species at St. 10, one of the two stations with the lowest pH, was the lowest compared to those at other stations. Analysis of c-p values for nematode species showed that both species sensitive to environmental disturbance and species resistant to environmental pollution appeared at high rates. According to the feeding type of nematodes, epistrate feeders accounted for a remarkably high proportion at St. 10. This study provides various data on meiofauna community characteristics to understand the effects of ocean acidification on coastal ecosystems.
Continue reading ‘Characteristics of meiofaunal community in the subtidal zone near Hupo, anticipating ocean acidification on the coast of Korea’Posts Tagged 'North Pacific'
Characteristics of meiofaunal community in the subtidal zone near Hupo, anticipating ocean acidification on the coast of Korea
Published 25 March 2026 Science ClosedTags: abundance, biological response, chemistry, community composition, crustaceans, field, nematodes, North Pacific, otherprocess, zooplankton
Tolerance of egg and yolk-sac larval yellowfin sole (Limanda aspera) to ocean warming and acidification
Published 23 March 2026 Science ClosedTags: biological response, fish, fisheries, growth, laboratory, morphology, mortality, multiple factors, North Pacific, physiology, reproduction, temperature
Yellowfin sole (Limanda aspera) support the largest flatfish fishery in the world and contribute substantially to the eastern Bering Sea (EBS) flatfish catch. The EBS has been warming and acidifying, trends that are expected to intensify into the future. Sustainable management of yellowfin sole requires an understanding of how yellowfin sole respond to environmental change, which can be assessed through controlled laboratory investigations. Across four independent trials, yellowfin sole embryos and larvae were incubated at one of six experimental treatments spanning three temperatures (9°C, 12°C, and 15°C) and two pCO2 target levels (low and high), and a range of organismal and physiological responses were measured. Embryonic daily mortality rates and metabolic rates increased with increasing temperature but were not affected by ocean acidification. At- hatch and at- yolk absorption, morphometric measurements (length, dry weight, myotome height, and yolk area) were temperature- sensitive, but the response differed across the four trials. There was a consistent increase in length- based growth and yolk absorption rates with increasing temperature across trials. All morphometric and rate- based measurements were not affected by ocean acidification. Yellowfin sole metabolic enzyme activities were measured at- yolk absorption. Lactate dehydrogenase (anaerobic metabolism) and β- hydroxyacyl CoA dehydrogenase (fatty acid metabolism) both increased with increasing temperature, indicating elevated energy demand. Citrate synthase (aerobic metabolism) declined with increasing pCO2 levels, indicating potential metabolic suppression. Overall, embryonic and larval yellowfin sole demonstrated relatively high tolerance to ocean warming and acidification. We hypothesize the variation in temperature responses across the trials may be driven by maternal effects, which could support tolerance to future ocean conditions.
Continue reading ‘Tolerance of egg and yolk-sac larval yellowfin sole (Limanda aspera) to ocean warming and acidification’Influence of ocean warming and acidification on juveniles of the true giant clam, Tridacna gigas, and its microalgal symbionts
Published 19 March 2026 Science ClosedTags: biological response, BRcommunity, laboratory, molecular biology, mollusks, mortality, multiple factors, North Pacific, phytoplankton, reproduction, temperature
Uncontrolled carbon dioxide emissions from human activities contribute to ocean warming and acidification. These alterations in ocean chemistry threaten marine organisms, such as the true giant clam, Tridacna gigas, which is already imperiled due to overharvesting and habitat destruction. To gain an understanding of the physiological and molecular responses of T. gigas and its symbiotic dinoflagellates to ocean warming and acidification, we subjected juvenile individuals to different treatments simulating predicted seawater pH (7.6 and 8.0) and temperature (28°C, 30°C, 32°C and 34°C) levels for the next century. Juvenile giant clams were able to tolerate sustained exposure to temperatures of up to 32°C and pH as low as 7.6, while exposure to higher temperature (34°C), regardless of pH level, resulted in total mortality after a week. However, symbiosis was compromised even in the sublethal treatments, as indicated by the decrease in Symbiodiniaceae density and changes in symbiont gene expression. Symbionts significantly upregulated genes involved in splicing, translation, fatty acid metabolism, and DNA repair, which may constitute an adaptive response, while downregulating genes involved in photosynthesis and transmembrane transport, suggests impaired transfer of photosynthates to the host. These findings demonstrate the vulnerability of the juvenile T. gigas holobiont to heat stress, highlighting the critical importance of continued conservation and management alongside efforts to mitigate global changes in ocean conditions to safeguard this iconic marine bivalve.
Continue reading ‘Influence of ocean warming and acidification on juveniles of the true giant clam, Tridacna gigas, and its microalgal symbionts’Differential impacts of ocean acidification and alkalinization on shell microstructure and molecular responses in Mytilus edulis
Published 18 March 2026 Science ClosedTags: biological response, laboratory, molecular biology, mollusks, morphology, mortality, North Pacific
Anthropogenic CO2 emissions are intensifying ocean acidification (OA), disrupting carbonate chemistry and threatening marine calcifiers such as mussels. Ocean alkalinity enhancement (OAE) has been proposed as a marine carbon dioxide removal (mCDR) strategy that can also mitigate OA, but its ecological safety for aquaculture species remains poorly understood. Here, we examined the short-term (21 days) responses of the blue mussel Mytilus edulis to OA (pH 7.3) and NaOH-based OAE (pH 9.0) using integrated shell microstructure analysis and transcriptomics. The results showed that while survival rates were unaffected, OA caused marked shell degradation and activated stress-related molecular pathways, whereas OAE enhanced shell integrity and stimulated growth-associated processes. Across treatments, a core set of biomineralization-related genes (e.g., VWA7, CA14, ALPL) exhibited expression shifts, suggesting central roles in carbonate homeostasis. In contrast, differential regulations of genes such as CA10 and VWDE revealed pH-specific responses. Notably, OAE induced minimal disruption of biomineralization and alleviated OA-related damage, highlighting its potential to support mussel aquaculture under future ocean conditions. While model simulations and plankton-scale experiments suggest global benefits of OAE, this study provides direct organism-level experimental evidence linking shell ultrastructure and transcriptomic responses under OA and OAE conditions. These findings offer mechanistic insights into mussel resilience and provide a critical empirical basis for evaluating the ecological safety of OAE as both a carbon sequestration strategy and a tool for sustainable aquaculture.
Continue reading ‘Differential impacts of ocean acidification and alkalinization on shell microstructure and molecular responses in Mytilus edulis’Groundwater-derived carbon promotes hypoxia and acidification in a large tropical estuary
Published 18 March 2026 Science ClosedTags: biogeochemistry, chemistry, field, North Pacific
Abstract
Submarine groundwater discharge (SGD) derived nutrient inputs have been extensively documented. However, SGD-derived carbon fluxes remain largely unconstrained, representing a critical gap in most coastal carbon budgets. Here, we resolve SGD and dissolved carbon budgets in the Pearl River Estuary (PRE), the largest estuary in Southern China surrounded by the world’s largest urban conglomerate. Broadly-defined SGD contributes 89%–96% of the dissolved inorganic carbon (DIC) pool (2–4 times riverine inputs) and 20%–70% of the dissolved organic carbon (DOC) fluxes of the PRE. SGD transports DIC exceeding total alkalinity (TAlk) by 2.7–7 times, potentially driving pH decline and acidification of nearshore waters. Groundwater pCO2 values are 10–36 times higher than estuarine waters. SGD-derived DOC mineralization can decrease estuary water pH by 0.04–0.16 units and increase CO2 by 6.0–90.0 μmol L−1, affecting local coral populations and benthic organisms. SGD also reduces seawater dissolved oxygen (DO) by 12–150 μmol L−1 and fuels the development of hypoxic zones. Overall, SGD regionally intensifies seawater hypoxia and acidification, creating challenging conditions for coral reef survival in an already stressed ecosystem. Our findings demonstrate that SGD should be integrated into carbon budgets and ecological assessments of the land-ocean continuum.
Plain Language Summary
Submarine groundwater discharge can transport large amounts of dissolved carbon into the coastal ocean, but it is often overlooked due to challenges in quantification. Here, we investigate the contribution of groundwater to the dissolved carbon pool in a large tropical estuary using radium isotopes and carbon data. We found that groundwater is a significant source of estuarine dissolved carbon and has the potential to acidify seawater oxygen-depleted waters. These findings emphasize the importance of considering groundwater when evaluating carbon budgets and the ecological health of coastal ecosystems.
Continue reading ‘Groundwater-derived carbon promotes hypoxia and acidification in a large tropical estuary’The economic impact of climate change on coral reef in the Main Hawaiian Islands
Published 18 March 2026 Science ClosedTags: biological response, communitymodeling, corals, modeling, multiple factors, North Pacific, socio-economy, temperature
Coral reefs are highly diverse and productive ecosystems that provide a wide range of ecosystem services, including recreation, coastal protection, and marine biodiversity. Climate change impacts, including ocean warming and acidification, pose a significant threat to coral reefs and the ecosystem services they provide. The variability of these impacts underlines the need to develop more spatially explicit tools in coastal ecosystem management that integrate and assess potential ecological and socio-economic outcomes. To address this, a spatially explicit predictive ecological model is applied to project changes in coral reef cover, using downscaled data from Shared Socioeconomic Pathway (SSP) climate scenarios. Based on these projections, welfare impacts of changes in recreational value are estimated across different populations and landscapes. Cumulative welfare losses for Hawaiʻi residents range from $1.5 to $3.3 billion in 2024$ by 2100. Counterintuitively, cumulative welfare losses are higher under optimistic emissions scenarios, where coral reef degradation is less severe than higher emission scenarios, because more people will experience smaller ecological losses. The approach incorporates site-specific characteristics, income distribution, and projected regional population growth to connect ecological change with welfare outcomes. EJScreen is used to assess variation in welfare impacts, identifying disadvantaged communities based on demographic and environmental indicators such as poverty, minority status, and exposure to environmental risks. These findings can inform policy and resource allocation by supporting ecosystem management strategies that account for both ecological dynamics and community-level socio-economic conditions.
Continue reading ‘The economic impact of climate change on coral reef in the Main Hawaiian Islands’Seasonal variations and key controls on seawater aragonite saturation state in the Northern Yellow Sea, China
Published 17 March 2026 Science ClosedTags: chemistry, field, North Pacific
Based on four field surveys conducted from August 2022 to May 2023, seasonal distribution and dynamics of the seawater aragonite saturation state (Ωarag) were investigated in the northern coastal zone of the Northern Yellow Sea, an important fishery region, to assess impacts of ocean acidification especially in river-dominated coastal systems. Results revealed seawater Ωarag had significant spatiotemporal variability with surface values ranging from 1.42 to 3.76 in summer, 1.22 to 2.34 in autumn, 1.71 to 2.48 in winter, and 2.03 to 3.56 in spring. Subsurface seawater Ωarag was generally lower than surface values, while seawater with Ωarag < 1.5—a critical threshold for severe biological stress—were predominantly found in the nearshore areas and in the southwestern offshore bottom waters. Persistent seasonal acidification was observed across the study area. While seawater temperature played an important role in seasonal Ωarag variation, its effect was masked in the nearshore zones by river-diluted water inputs, especially in summer, and in offshore bottom waters by community respiration during summer and autumn. These mechanistic insights clarify key drivers of coastal acidification and provide a scientific basis for developing targeted strategies to detect acidification trends and ecosystem responses in anthropogenically impacted coastal regions.
Continue reading ‘Seasonal variations and key controls on seawater aragonite saturation state in the Northern Yellow Sea, China’Multi-level holobiont dysregulation increases the ecological risk of combined ocean acidification and benzo[a]pyrene pollution to the reef-building coral Porites lutea
Published 17 March 2026 Science ClosedTags: archaea, biological response, BRcommunity, community composition, corals, laboratory, molecular biology, multiple factors, North Pacific, otherprocess, photosynthesis, physiology, phytoplankton, prokaryotes, toxicants
Highlights
- Combined ocean acidification and BaP induce holobiont dysregulation, evidencing by a decoupled Symbiodiniaceae proliferation and a collapse of the archaeal Nanoarchaeota-Halobacterota symbiosis.
- The coral host shifts its defense strategy from antioxidant capacity to cellular homeostasis, while the bacterial community increases functional redundancy, revealing a costly acclimation mechanism.
- The multi-level dysregulation demonstrates an underestimated ecological risk, highlighting that current single-stressor risk assessments are inadequate for protecting corals under complex pollution scenarios.
Abstract
Reef-building corals are increasingly threatened by the combined effects of global climate change and localized organic pollutants. However, the holistic impacts of co-exposure to ocean acidification (OA) and benzo[a]pyrene (BaP) on coral holobionts remain poorly understood. Here, we investigated the multi-level responses of the reef-building coral Porites lutea to short-term (7-day) exposure to OA (pH 7.80), BaP (10 µg/L), and their combination, by integrating physiological measurements with microbiome profiling (ITS2 and 16S rRNA). We found that combined stress was associated with a dysregulated response in Symbiodiniaceae, characterized by a significant increase in cell density without a parallel rise in chlorophyll content, suggesting a possible compensatory but inefficient proliferation response. Despite this, the dominant symbiont Cladocopium C15 remained stable. The bacterial diversity increased (e.g., enrichment of Ruegeria and Acanthopleuribacter, decline of Endozoicomonas), which may suggest enhanced functional redundancy, while the archaeal community was significantly restructured, most notably a marked decline of the putative obligate Nanoarchaeota–Halobacterota symbiosis. At the host level, combined stress was associated with suppressed antioxidant enzyme activities (SOD/POD) but upregulated genes related to protein folding (Hsp90) and calcium homeostasis (NCX1, VAMP4). These findings suggest a complex holobiont reconfiguration under combined stress, involving a stabilized core symbiont, altered microbiomes, and a shifted host defense strategy. Our study suggests that the ecological risk of combined OA and organic pollution may not be extrapolated from single-stressor responses, indicating the need to incorporate multi-stressor frameworks into coral reef risk assessments.
Continue reading ‘Multi-level holobiont dysregulation increases the ecological risk of combined ocean acidification and benzo[a]pyrene pollution to the reef-building coral Porites lutea’Marine heatwaves, ocean warming and acidification reshape reef fish gut microbiomes
Published 16 March 2026 Science ClosedTags: biological response, BRcommunity, community composition, field, fish, molecular biology, multiple factors, North Pacific, otherprocess, physiology, prokaryotes, temperature, vents
Extreme climatic events and gradual climate change are increasingly anticipated to interact and reshape ecological communities. However, the combined effects of ocean warming, acidification and marine heatwaves on host‐associated microbial communities and their potential role in host adaptation remain poorly understood. Here, we assessed shifts in gut microbiome communities and their associations with physiological performance in one tropical ( Abudefduf vaigiensis ) and one subtropical ( Microcanthus strigatus ) reef fish species, across three temperate reefs representing natural analogues of climate change: a present‐day baseline (‘cool reef’), a chronically warmed reef (‘warm reef’) and a reef experiencing combined warming and extreme acidification (‘extreme reef’). We also examined gut microbiome changes in A. vaigiensis before and during a severe marine heatwave. A. vaigiensis had lower gut microbiome evenness and diversity at the warm (43% and 44% decrease, respectively) and extreme (38% and 31% decrease) reefs compared to the cool reef, and its gut microbiome community shifted at the extreme reef with a 122% increase in abundance of opportunistic bacteria Vibrio. A. vaigiensis also had lower gut microbiome richness at the warm (42% decrease) and extreme (52% decrease) reefs during the heatwave compared to pre‐heatwave individuals. In contrast, M. strigatus showed higher microbiome evenness (99% increase) and diversity (98% increase) at the warm reef compared to the cool reef; however, these gains were lost at the extreme reef, with microbiome diversity and evenness returning to cool reef levels. Microbiome changes in both species were generally not associated with their physiological performance (protein content, oxidative stress, antioxidant capacity or body condition). Our findings suggest that marine heatwaves, ocean warming and acidification can reshape reef fish gut microbiomes, driving simplification in Abudefduf vaigiensis but distinct restructuring in Microcanthus strigatus . We conclude that climate‐driven microbiome reshuffling may alter host–microbiome relationships and functions in fishes in a future ocean.
Continue reading ‘Marine heatwaves, ocean warming and acidification reshape reef fish gut microbiomes’Stony coral symbioses show variable responses to future ocean conditions
Published 16 March 2026 Science ClosedTags: adaptation, biological response, BRcommunity, community composition, corals, laboratory, mesocosms, multiple factors, North Pacific, otherprocess, phytoplankton, temperature
Coral reefs support over a quarter of marine species and nearly a billion people worldwide but are also among the ecosystems most threatened by anthropogenic impacts. There is long-standing debate about whether coral symbioses will be disrupted or respond adaptively under future ocean conditions. Using a factorial 2.5-year future-ocean mesocosm experiment across eight coral species representing the major coral lineages, we tracked symbiont community shifts within replicate fragments from the same individual coral. Some corals exhibited stochastic divergence consistent with dysbiosis, whereas others showed deterministic, thermally adaptive shifts. Heat stress generally reduced symbiont diversity and promoted predictable restructuring, supporting deterministic processes under moderate stress but stochastic dysbiosis under extreme conditions. We propose that adaptive and stochastic responses represent endpoints along a continuum of host-orchestrated symbiont sorting. This study bridges coral reef ecology with broader host–microbiome theory, offering an integrated perspective on how symbiotic systems may respond to environmental change.
Continue reading ‘Stony coral symbioses show variable responses to future ocean conditions’Environmental controls and nonlinear responses of the diatom-dinoflagellate ratio in Jiaozhou Bay
Published 13 March 2026 Science ClosedTags: abundance, biological response, BRcommunity, chemistry, community composition, field, North Pacific, otherprocess, phytoplankton
Highlights
- Dia/dino abundance, biomass, and diversity ratios exhibited similar temporal patterns;
- All ratios showed considerable heterogeneity without a consistent distributional trend;
- Dia/dino ratios responded distinctly to DO, nutrients, and their interactions;
- Shifting seawater properties exerted large influence on diatom-dinoflagellate dynamics.
Abstract
Diatoms and dinoflagellates are widely recognized as key indicators of marine ecosystem status and play central roles in ecosystem functioning and biogeochemical cycling. Yet how these two major phytoplankton groups adjust to changing coastal environments, and whether such adjustments occur coherently in different ecological dimensions, remains poorly constrained. Hence, we studied the temporal and spatial dynamics of diatom-dinoflagellate (dia/dino) ratios in Jiaozhou Bay during 2021 and 2024, integrating abundance-, carbon biomass-, diversity-, and richness-based metrics. Although abundance, biomass, and diversity ratios exhibited broadly similar temporal trajectories, the richness ratio displayed an opposite pattern, highlighting a decoupling between numerical dominance and species composition. Spatially, all four ratios exhibited significant heterogeneity, without a consistent nearshore-offshore gradient, reflecting complex local regulation. Correlation analyses revealed distinct controls on dia/dino ratios. The abundance ratio increased under conditions of elevated dissolved inorganic nitrogen (DIN) and reduced dissolved oxygen (DO), whereas the diversity ratio was associated with high DIN and low dissolved inorganic phosphorus (DIP). In contrast, the carbon biomass ratio was primarily linked to reduced DO and lower pH, while the richness ratio responded most strongly to the combined influence of low DO and elevated DIP. These contrasting responses indicated that dia/dino ratios captured different facets of phytoplankton community reorganization rather than reflecting a single environmental driver. Overall, our results suggested that the balance between diatoms and dinoflagellates in Jiaozhou Bay emerged from the coupled and nonlinear interactions among nutrient availability and oxygen dynamics. This study highlighted the dia/dino balance as an integrative indicator of coastal ecosystem condition and implied the importance of considering multiple ecological dimensions when assessing phytoplankton responses to ongoing eutrophication and environmental change.
Continue reading ‘Environmental controls and nonlinear responses of the diatom-dinoflagellate ratio in Jiaozhou Bay’Two decades of skeletal density decline in Pocillopora spp. corals in the Mexican Pacific Ocean: insight into a tropical eastern Pacific acidification scenario?
Published 10 March 2026 Science ClosedTags: biological response, chemistry, corals, field, morphology, North Pacific
Corals demonstrate vulnerability to environmental changes, exhibiting the capacity to substantially modify coral calcification. In this study, we estimated declines in the density of Pocillopora coral species in the Mexican Pacific. The samples utilized in this study encompass both recently collected corals and those stored in Mexican repositories collected in the northeastern and southern Mexican Pacific regions. Density estimates indicate a 28.6% decline in coral density over the past 23 years (−0.0227 g CaCO3 cm-3 y-1) in the southern Mexican Pacific, while at the entrance to the Gulf of California, density has decreased by 15.4% over the past 20 years (−0.017 g CaCO3 cm-3 y-1). A comprehensive evaluation of environmental data reveals that the observed decline in Pocillopora skeletal density in Mexican Pacific reefs is concomitant with decreases in Ωar and pH, and an increase in ocean temperature on a substantial regional scale. When considered in conjunction with the previously documented reductions in coral growth of Pocillopora spp. skeletons in the eastern Tropical Pacific, our findings indicate a potential decline in CaCO3 production within the region’s reef systems. The results of this study underscore the significance of generating long-term series of coral growth parameters for relevant reef-building species and the carbonate system in key and representative coastal areas, particularly those that are already challenging for coral survival and reef maintenance.
Continue reading ‘Two decades of skeletal density decline in Pocillopora spp. corals in the Mexican Pacific Ocean: insight into a tropical eastern Pacific acidification scenario?’Sex-specific physiological-biochemical and multi-omics responses of Sargassum thunbergii to ocean acidification
Published 10 March 2026 Science ClosedTags: algae, biological response, laboratory, molecular biology, North Pacific, photosynthesis, physiology
Highlights
- A multi-omics study on sexual dimorphism of macroalgae under OA.
- Male S. thunbergii adopted a growth-oriented strategy under OA.
- Female S. thunbergii showed a defense-oriented survival strategy under OA.
- Fundamental trade-off between growth and defense underlay sex-specific responses.
Abstract
Ocean acidification (OA), driven by increasing atmospheric CO2 concentrations, poses significant threats to the ecologically important intertidal macroalgae. Multiple previous studies have indicated species-specific responses to OA, the sex-specific physiological-biochemical responses and underlying molecular mechanisms in dioecious macroalgae remain poorly understood. In this study, we investigated the responses of male and female Sargassum thunbergii to acidification treatment (2000 ppm CO2) by integrating physiological-biochemical, transcriptomic, and metabolomic analyses. Both sexes maintained photosynthetic performance, with increased maximum relative electron transport rates (rETRmax). Males exhibited a growth-oriented strategy, characterized by higher accumulation of storage compounds like triglycerides and up-regulation of genes related to the photosynthesis and biosynthesis pathways. In contrast, females displayed a survival-oriented strategy, with reduced carbon storage, increased soluble protein and phenolic substance contents, and up-regulation of genes related to defense- and stress-response pathways. These findings provided physiological-biochemical and molecular evidence for a growth and defense trade-off between male and female S. thunbergii under acidification treatment. Our study provided the mechanistic insights into the sex-specific responses of marine macroalgae to global climate change and highlighted the importance of accounting for sexual dimorphism in predicting the ecological resilience of intertidal macroalgae populations under future ocean conditions.
Continue reading ‘Sex-specific physiological-biochemical and multi-omics responses of Sargassum thunbergii to ocean acidification’Ocean acidification and changes in biological production in the western subarctic region of the North Pacific over the quarter century, 1999–2023
Published 2 March 2026 Science ClosedTags: Arctic, biogeochemistry, chemistry, field, North Pacific
Changes in the physical and biogeochemical conditions of the ocean over time can affect marine ecosystems. In this study, we use biogeochemical observational data for the past 25 years (1999–2023) to investigate ocean acidification and changes in biological production at site K2 (47˚ N, 160˚ E) in the western subarctic region of the North Pacific Ocean. During this period, satellite-derived sea surface temperatures increased at a rate of 0.056 °C yr–1, while the surface mixed-layer salinity decreased by 0.004 yr−1. As a result of the oceanic uptake of anthropogenic CO2 from the atmosphere, the deseasonalized annual mean surface mixed-layer pH and saturation states of calcium carbonate minerals of calcite and aragonite decreased at rates of 0.0013 ± 0.0004, 0.007 ± 0.003, and 0.004 ± 0.002 yr−1, respectively. These rates are consistent with those calculated for winter. Under these acidification conditions, no significant trends were observed in either the annual mean or winter concentrations of nutrients (phosphate, nitrate, and silicate), or in total alkalinity in the surface mixed layer. However, the decadal trends in nutrient concentrations show a significant increase in May and decrease in July. Net community production (NCP), which is an index of biological production, was estimated from differences in nutrient concentrations between winter and May or July. This analysis revealed significant decreasing trends in NCP from winter to May, followed by increasing trends from winter to July. The stoichiometric molar ratio of Si associated with the July NCP increase (P:N:Si = 1:15:55) is higher than the previously reported ratio (1:16:40). A significant decreasing trend in satellite-derived photosynthetically active radiation (PAR) was observed in May (0.20 ± 0.08 yr−1), which may be linked to reduced biological production during that month. This decrease may be offset by increased production in summer that is likely due to a shift in the timing of the diatom bloom. These findings highlight the effects of long-term changes of potential drivers of both atmospheric and deep oceanic origin on oceanic biological production.
Continue reading ‘Ocean acidification and changes in biological production in the western subarctic region of the North Pacific over the quarter century, 1999–2023’Pathways to adaptation for shellfish aquaculture on the U.S. West Coast
Published 2 March 2026 Science ClosedTags: fisheries, mitigation, North Pacific, socio-economy
Understanding how shellfish growers adapt to environmental and socioeconomic stressors is critical for food security, especially with growing impacts from climate change. However, we know relatively little about the supporting factors that lead shellfish growers who experience stressors to make adaptive choices. Through interviews conducted with US West Coast (California and Oregon) shellfish farm owners and managers (growers), we document environmental and socioeconomic stressors that growers experience and investigate whether they can adapt, react, or cope (ARC response) to these stressors. We further identify growers’ strategies for adaptation and link these strategies to theoretical adaptive capacity domains (ie, assets, flexibility, social organization, learning, agency, and governance) using qualitative comparative analysis (QCA). We found regulatory stressors were the most impactful to growers overall. These stressors caused financial burdens and time delays to operations for growers in both states. Ocean acidification and/or hypoxia (OAH) was the most frequently reported environmental stressor. Ocean acidification and/or hypoxia impacts include increased mortality and shellfish die-off events. Out of 125 responses to stressors, growers were able to adapt in just over half of stressor responses (54.4%). Agency, flexibility, learning, and social organization supported adaptation most frequently, while governance was employed the least. Growers responded with cope responses (35.2%) more frequently than react responses (10.4%). Growers combined adaptive capacity domains in various ways to adapt. For example, the adaptive capacity domain of agency was frequently employed, but almost always in combination with other adaptive capacity domains (eg, assets, governance, flexibility, and learning). This study demonstrates that US West Coast shellfish growers combine adaptive capacity domains in creative ways to form adaptive pathways and illuminates pathways to better support adaptive capacity in shellfish aquaculture.
Continue reading ‘Pathways to adaptation for shellfish aquaculture on the U.S. West Coast’Range-extending fish become competitive dominants under ocean warming but not heatwaves or acidification
Published 27 February 2026 Science ClosedTags: biological response, field, fish, multiple factors, North Pacific, performance, temperature, vents
Ocean warming is driving species range extensions into cooler regions. The direct physiological influence of warming on species performance can accelerate such extensions into novel ecosystems; however, indirect effects of invader–resident interactions in cooler regions may counter these positive effects. Here, we examined the foraging performance and densities of competing warm‐water and cool‐water fishes across a latitudinal temperature gradient spanning 1500 km from tropical to temperate reefs subjected to rapid ocean warming in the southern hemisphere, and across natural analogs of temperate, tropicalized, and acidified reef localities in the northern hemisphere, and during a severe marine heatwave at a temperate reef. While current levels of ocean warming have allowed the warm‐water fish to extend their ranges into temperate ecosystems at both hemispheres, their foraging performance was reduced at both the cold‐ and warm‐temperate reefs compared to the (sub)tropical reefs. However, at the (warmer) tropicalized reef, the warm‐water fish had higher foraging performance and maintained densities, even under extreme pH reduction, compared to the temperate reef. In contrast, the cool‐water species struggled at the warmer tropicalized and extreme reefs with reduced foraging performance and lower population densities compared to the temperate reef. Contrastingly, the severe heatwave experienced at the temperate reef did not alter the foraging behaviors of either species. We suggest that ocean warming boosts the foraging performance of the range‐extending warm‐water fish and impairs that of their cool‐water competitor at temperate reefs, irrespective of acidification and heatwaves, leading to a shift in dominance hierarchies on temperate reefs. We conclude that warming‐driven increases in foraging performance of the warm‐water species may alleviate foraging limitations and enhance its establishment at its leading range edges under climate change, to the detriment of its cool‐water competitors.
Continue reading ‘Range-extending fish become competitive dominants under ocean warming but not heatwaves or acidification’Seawater pH fluctuations during the Ordovician to Silurian transition: insights from δ11B records in carbonates
Published 26 February 2026 Science ClosedTags: chemistry, field, North Pacific, paleo
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 ClosedTags: abundance, biological response, BRcommunity, community composition, laboratory, mesocosms, molecular biology, North Pacific, otherprocess, phytoplankton, prokaryotes
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 ClosedTags: chemistry, modeling, North Pacific, regionalmodeling
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 ClosedTags: fisheries, North Pacific
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.
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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!
Continue reading ‘Shell-shocked: local oyster farmers confront a changing climate’
