Posts Tagged 'biological response'

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Effects of long-term exposure to ocean acidification on the Patagonian scallop Zygochlamys patagonica (P.P. king, 1832), a strategic fishery resource in the Southwest Atlantic ocean

Published 12 March 2026 Science Closed
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Highlights

  • Scallops were resilient to low pH within the present range of natural variability.
  • Negative impacts were observed under true ocean acidification scenario, including:
    • Increased mortality & decreased shell mass condition index
    • Dissolution of the external shell surface modifying shell ornamentation
    • Shell disarticulation leading to the lost ability to swim
  • During depuration time were observed:
    • A recovery of the scallops’ vital functions when the stressor (low pH) was not present
    • No recovery for shell mass condition index, shell ornamentations and disarticulated scallops
    • No new disarticulated scallops

Abstract

Ocean acidification (OA) is a global process leading to a decrease in seawater pH. It is a direct consequence of the increase in CO2 emissions due to human activities with documented impacts on marine species and ecosystems. Effects of a long-term OA exposure (6 months) followed by a 2 months depuration period were evaluated on the Patagonian scallop Zygochlamys patagonica, an important seafood species of the Southwest Atlantic Ocean. Scallops were exposed to three target pHs, (1) pH 7.93, the mean annual pHT at the sampling site, (2) pH 7.83, the minimum value of the natural variability recorded at the sampling site and, (3) pH 7.53, a 0.3 pH unit below the minimum pH. Mortality, shell growth, and shell mass, adductor muscle mass and gonadal mass condition indices were measured at the beginning of the experiment and after 3, 6 and 8 months of exposure. Decreased pH led to a significant increase in mortality and decrease in the shell mass condition index. Shell growth was minimal over the course of the experiment with no effect of pH. The external shell surface showed a gradual dissolution and discolouration over the 6 months exposure to low pH. Shell disarticulation due to ligament damage was also observed in 29% of the animals exposed to low pH after 6 months resulting in loss of swimming ability of scallops, whereas no disarticulated animals were recorded in the high pH treatment. These results show the vulnerability of this species to future OA conditions with implications for the ecosystem services it provides, such as a decline in scallop numbers, greater vulnerability to predation and lower quality of commercial products.

Continue reading ‘Effects of long-term exposure to ocean acidification on the Patagonian scallop Zygochlamys patagonica (P.P. king, 1832), a strategic fishery resource in the Southwest Atlantic ocean’

Multifactorial neural disruption in the brain of the Senegalese sole (Solea senegalensis) under ocean acidification

Published 11 March 2026 Science Closed
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Global ocean acidification, driven by rising atmospheric CO2, threatens marine ecosystems and biodiversity, with increasing evidence of disruptive effects on fish neurobiology and behaviour. However, the precise mechanisms underlying these impacts remain largely unresolved. Here, we reveal how chronic exposure to future-predicted CO2 levels disrupts brain function in the marine teleost Solea senegalensis. Using an integrative approach combining electrophysiology, immunohistochemistry and transcriptomics, we demonstrate that elevated CO2 induce a complex multifaceted disruption in brain physiology.

Contrary to the prevailing GABAA receptor reversal hypothesis, which predicts Cl− loss and heightened excitatory signalling under high CO2, we observed increased Cl− and HCO3− in cerebrospinal fluid and suppressed neural excitability. Immunohistochemistry revealed reduced expression of glial fibrillary acidic protein across multiple brain regions, suggesting glial impairment. Furthermore, transcriptomic profiling of the olfactory bulb uncovered immune modulation, downregulation of neural excitability genes, and upregulation of neuroplasticity, ciliary, and anti-inflammatory pathways, hallmarks of cellular stress adaptation. Notably, genes involved in circadian regulation and thyroid signalling were also dysregulated, pointing to broader neuroendocrine disruption.

These findings challenge simplistic models of ocean acidification impact, unveiling a cascading interplay of enhanced GABAergic inhibition, immune shifts, glial dysfunction, and disrupted timekeeping mechanisms, likely contributing to the behavioural impairments under high CO2.

Unlike prior studies relying on behavioural assays or direct physiological proxies, our integrative approach, combining direct cerebrospinal fluid ionic measurements, electrophysiology, immunohistochemistry and transcriptomics, unveils a multifactorial physiological cascade. Our work advocated for integrative neurophysiological frameworks to predict marine fish resilience and vulnerability in a rapidly changing ocean.

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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 Closed
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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 Closed
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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.

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Acidification stimulates N2O production by oceanic nitrifying bacteria

Published 9 March 2026 Science Closed
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Recent studies have shown changes in the production rates of nitrous oxide (N2O) in aerobic seawater in response to ocean acidification (OA). Understanding how N2O production responds to OA is crucial because N2O is a strong greenhouse gas and stratospheric ozone‐depleting substance emitted from the ocean. The pH dependence of N2O production rates on marine bacteria Nitrosococcus oceani strain NS58, one of the ammonia oxidizing bacteria that are relevant to nitrification occurring in eutrophic seawater, was investigated under several dissolved oxygen (DO) conditions. We also measured abundance ratios of N2O molecules substituted with rare stable isotopes (isotopocules) to distinguish the two major pathways of N2O production by nitrifiers: NH2OH oxidation and NO2⁻ reduction. The ammonium oxidation rate (VNO2 VNO2) and N2O production rate (VN2O VN2O) calculated respectively from the temporal change of the product concentrations were 4–34 × 10⁻¹⁵ mol h⁻¹ cell⁻¹ and 1–15 × 10⁻¹⁷ mol h⁻¹ cell⁻¹. When compared in the stable phase (t = 44–76 hr), VNO2 VNO2 decreased concomitantly with decreasing DO, also exhibiting a slight increase in acidified water. In contrast, VN2O VN2O was highest at 35% DO (air saturation), showing a 5%–60% increase by acidification (pH 7.7 vs. 8.0) depending on DO. Isotopocule ratios showed an increased contribution from NO2⁻ reduction over NH2OH oxidation under 35% and 3% DO, but its pH dependence was negligible except under 3% DO. These results suggest that OA increases N2O emission in particular from eutrophic seawater and that both N2O production pathways can be stimulated to the same degree.

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Applying omics techniques to examine microscopic life fueling Gulf region ecosystems 

Published 6 March 2026 Press releases Closed
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Scientists at NOAA’s Atlantic Oceanographic & Meteorological Lab and the Northern Gulf Institute applied omics techniques to provide the first basin-scale assessment of the microbial communities at the base of marine ecosystems across the Gulf region. The new study from Dr. Luke Thompson’s group, conducted by Dr. Sean Anderson and co-authors, is the largest environmental DNA (eDNA) or microbiome survey of the Gulf of America ever performed.

Scientists collected environmental DNA (eDNA) – genetic material from whole microbes or shed by marine life into the environment – during the 2021 Gulf and Ocean Monitoring Ecosystems and Carbon Cruise (GOMECC). These samples unlock crucial new insights into the microscopic life across an entire basin – from nearshore coastal ecosystems out to the open Gulf. By analyzing the microbial communities throughout the water column, we can better understand how they are being impacted by changing environmental conditions. 

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Changes in the composition of these microbial communities in any given region has cascading effects, influencing the biodiversity and feasibility of commercially viable species to survive and flourish in a specific region. Understanding how microbial diversity throughout the water column varies with changing conditions – changes in salinity, temperature, nutrient levels – could unlock key insights and provide early indicators of how entire ecosystems will be impacted by exacerbated environmental stressors, including ocean acidification. 

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Colony formation sustains the global competitiveness of nitrogen-fixing Trichodesmium under ocean acidification

Published 5 March 2026 Science Closed
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Anthropogenic carbon dioxide emissions drive ocean acidification. Trichodesmium, a key marine nitrogen-fixing cyanobacterium, displays contrasting growth responses to ocean acidification across morphotypes: negative in filamentous free trichomes but neutral or positive in colonies. However, lacking mechanistic understanding for these discrepancies has impaired our ability to predict Trichodesmium’s ecophysiological response. Here, we develop ecophysiological models to underpin mechanisms behind these divergent responses. For free trichomes, ocean acidification reduces nitrogen-fixing enzyme activity and photosynthetic energy production. In colonies, however, it alleviates copper and ammonia toxicity within the microenvironment—likely synergizing with enhanced iron acquisition—thereby outweighing minor benefit from relieved inorganic carbon limitation in the colony center. Projections suggest that globally, ocean acidification will reduce nitrogen fixation of trichomes by 16 ± 6% but increase that of colonies by 19 ± 24% within this century. By resolving morphotype-specific mechanisms, our study clarifies Trichodesmium’s adaptive strategies for sustaining its competitiveness and biogeochemical impacts in the changing ocean.

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Interactive effects of ocean acidification and settlement biofilm on the early development of the European abalone Haliotis tuberculata

Published 3 March 2026 Science Closed
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Highlights

  • Interactive effects of OA and settlement biofilm were investigated on juvenile abalone.
  • Post-larval density and total length decreased significantly under lower pH.
  • Biofilm composition induced indirect effects through changes in diatom biomass.
  • (pH × Ulvella) interaction affected abalone shell resistance and colouration.

Abstract

Ocean acidification (OA) and associated shifts in carbonate chemistry represent major threats to marine organisms, particularly calcifiers. OA effects can be influenced by other environmental variables, including the biotic environment. This study investigated the effects of OA and algal density, acting through an Ulvella-conditioned settlement biofilm, on post-larval and juvenile abalone (Haliotis tuberculata). In a three-month full factorial experiment, abalone were exposed from metamorphosis onward to two pH conditions (ambient 8.0 and reduced 7.7) and two initial densities of the green alga Ulvella lens on settlement plates. Biofilm biomass and composition were characterised using spectral reflectance and HPLC pigment analysis. Biological (density, length), physiological (respiration rate), behavioural (hiding response) and shell parameters (colour, surface corrosion, strength) of abalone were measured. Biofilm biomass and composition assessed with pigment proxies remained relatively stable under both pH conditions, though greater variability in algal biomass occurred at low initial Ulvella density. Post-larval density and total length decreased significantly under low pH, while high Ulvella density reduced juvenile length at 80 days, likely due to competition between algal groups. A pH × Ulvella interaction affected shell fracture resistance and colouration, but not metabolism or behaviour, indicating that juvenile abalone maintained vital functions. Overall, the results confirm the sensitivity of early H. tuberculata stages to moderate OA (−0.3 pH unit) and highlight indirect macroalgal effects through changes in diatom cover. In natural environment, the capacity of abalone to cope with future OA will depend on complex trade-offs between direct acidification effects and food-related biotic interactions.

Continue reading ‘Interactive effects of ocean acidification and settlement biofilm on the early development of the European abalone Haliotis tuberculata’

Persistence of coral reef structures into the twenty-first century

Published 2 March 2026 Science Closed
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Coral reefs provide important socioecological services but are vulnerable to climate change, which shifts the balance between the production and erosion of calcium carbonate (CaCO3). In this Review, we summarize understanding of reef accretion, describe the mechanisms of carbonate production and erosion, and consider the effects of future ocean warming and acidification on key reef-building and eroding taxa. The combined stressors of climate change substantially reduce net carbonate production, with a more pronounced effect on calcifying algae than corals. However, declining coral cover driven by marine heatwaves and mass bleaching will probably be the dominant determinant of future reef carbonate budgets, and thus only reefs with thermally adapted populations are predicted to maintain the ability to sustain positive CaCO3 production under climate change, even if calcareous algal cover increases. As carbonate budgets become net negative in the future, the longevity of pre-existing reef frameworks remains unknown and understudied owing to the timescales required to meaningfully assess framework removal rates. Improving estimates of the rates of biologically driven framework loss and chemical dissolution will also be important in better predicting future reef persistence. Key knowledge gaps exist in understanding the effects of deoxygenation on coral reefs, as well as the influence of climate change on understudied sediment-producing taxa such as foraminifera and tropical molluscs.

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Range-extending fish become competitive dominants under ocean warming but not heatwaves or acidification

Published 27 February 2026 Science Closed
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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.

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The invisible engine of the oceans: marine microorganisms driving climate resilience and ecosystem stability: a literature review

Published 27 February 2026 Science Closed
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Marine microorganisms form the invisible foundation upon which ocean life depends. Despite their microscopic size, they regulate major biogeochemical cycles, sustain primary productivity, and play a decisive role in maintaining the balance and resilience of marine ecosystems. As climate change intensifies and marine pollution expands in scale and complexity, the responses of these microbial communities have become central to understanding the future of the oceans. This work explores the diversity of marine microorganisms and examines how rising sea temperatures, ocean acidification, physical oceanographic changes, and multiple pollution sources interact to reshape microbial structure and function. Current evidence shows that shifts in temperature and seawater chemistry can alter microbial metabolism, community composition, and ecological interactions, with far-reaching consequences for carbon cycling, nutrient availability, and food web dynamics. At the same time, chemical pollutants, plastics, heavy metals, and excess nutrients impose strong selective pressures, often disrupting microbial balance while also promoting the emergence of microorganisms capable of degrading contaminants. These dual responses highlight marine microbes as both sensitive indicators of environmental stress and active contributors to ecosystem recovery. By bringing together recent scientific insights, this study underscores the essential role of marine microorganisms in ocean ecosystem regulation and climate change adaptation and emphasizes the need to incorporate microbial processes more fully into ocean monitoring, climate modeling, and sustainable marine management efforts.

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Physiology and survival of intertidal calcifiers in two contrasting upwelling systems

Published 27 February 2026 Science Closed
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Climate change alters the oceans’ temperature, pH, and oxygen concentration. These changes are expected to increase globally over the coming decades, affecting a wide range of marine organisms. Coastal upwelling zones, characterized by their high environmental variability, serve as ideal natural laboratories to study the potential impacts on marine organisms and ecosystems of temperature change, acidification, and ocean deoxygenation. The estimation of survival using capture‐mark‐recapture (CMR) data has been commonly applied to vertebrates, and to date, very few studies have been done on marine invertebrate organisms. In this study, we combined field CMR data and laboratory measurements to assess the physiological responses (metabolic rate and heart rate) and survival probability of individuals in two populations of intertidal mollusks, Chiton granosus and Scurria zebrina, in contrasting upwelling environments (i.e., semi‐permanent vs. seasonal). We found that (1) there are no differences between the two studied populations for heart rate in both species, (2) the S. zebrina population subjected to seasonal upwelling has a higher metabolism, (3) there are no differences in the calcification rate between the two studied populations of both species, and (4) survival is significantly higher in the semi‐permanent upwelling location for both species. Our findings highlight species‐specific responses to contrasting upwelling regimes, suggesting that phenotypic plasticity and survival differences may influence resilience under ongoing climate change.

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Natural analogues of climate change can reveal fish responses across multiple levels of biological organisation

Published 26 February 2026 Science Closed
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Anthropogenic climate change is threatening ecosystem functionality and biodiversity globally. While significant research has been dedicated to understanding how organisms may respond to future climate change, most of these studies focus on individual levels of biological organisation in controlled laboratory settings, which often fail to capture the complexity of natural ecosystems. Organisms respond to climate stressors across various levels of biological organisation, which also involve complex interactions or feedback mechanisms among levels, making it difficult to generalise responses to climate change from laboratory experiments or single levels alone. Natural analogues provide a unique opportunity to observe complex ecological interactions in real-world environments with long-term exposure to climate change stressors. Here, we provide a systematic literature review to reveal how natural analogues of ocean warming and ocean acidification can be used to assess fish responses to climate change across multiple levels of biological organisation (from molecular to biogeographical scales) and to assess how cross-level buffering and feedback mechanisms may shape fish species persistence in a future ocean. We identify key knowledge gaps and propose research frameworks that integrate natural analogues with laboratory experiments, mesocosms, and predictive models to better capture the complexity of fish responses to climate stressors in a more holistic way. Finally, we highlight the importance of coordinated, cross-system research using multiple natural analogues to reveal adaptive mechanisms and strengthen predictions of fish community reorganisation under climate change.

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A standardised experimental setup for simulating ocean warming and acidification in benthic marine invertebrates

Published 26 February 2026 Science Closed
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Recent studies identify ocean warming and acidification as major drivers of ecological change in the Eastern Mediterranean, posing serious threats to marine biodiversity, particularly for sessile or low-mobility organisms that cannot escape unfavourable conditions. At the same time, the need for standardised experimental approaches capable of generating high-quality data on organismal responses to multiple climate stressors has become increasingly evident. This manuscript presents a fully detailed and replicable experimental framework for simulating ocean warming and acidification in benthic marine invertebrates under controlled laboratory conditions. Detailed protocols include the technical set-up, experimental design, selection of climate scenarios, monitoring procedures and criteria for species selection and demonstrating its application through a validation case study from the MACCIMO project.

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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.

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Ocean acidification modifies site fidelity and patterns of seagrass habitat use by a herbivorous fish

Published 25 February 2026 Science Closed
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Ocean acidification (OA), characterized by changes in seawater chemistry and a concomitant decline of pH due to the uptake by seawater of the atmospheric CO2, will profoundly shape marine ecosystems. The lower pH/higher pCO2 can act negatively (as a stressor for organisms with a calcareous exoskeleton) or positively (as a direct resource for primary producers like macrophytes). Consequently, herbivores may indirectly benefit from OA counteracting the direct negative effects of living under high pCO2/low pH conditions. Here, we investigated how OA may influence site fidelity, habitat use, and trophic behaviour patterns of Sarpa salpa, the main herbivorous fish associated with Posidonia oceanica meadows in the north-western Mediterranean Sea. We assessed if and how OA influences the habitat use of S. salpa by comparing natural tags, in otoliths and muscle tissues, between CO2 vents and reference pH sites. We did not find differences in otolith elemental composition and shape among fish exposed to different pH conditions (CO2 vent vs ambient pH sites). However, otolith isotopic signatures differed between life stages (young vs sub-adults), consistent with the variations observed in seawater-dissolved inorganic carbon across sites. Finally, comparisons of the nutritional value marine vegetation (macroalgae, P. oceanica, epiphytes) showed that P. oceanica and epiphytes were more nutritious at CO2 vents, along with increased consumption by S. salpa. This trophic separation indicates that S. salpa spent more time exploiting the trophic resources in the CO2 vents. Together, our findings shed new light on plant–herbivore interactions within P. oceanica meadows under future OA scenarios.

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Climate change impacts on coral reefs and emerging resilience pathways: a systematic review

Published 25 February 2026 Science Closed
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Highlights

  • Rising temperatures, acidification, sea level rise and storms are accelerating coral bleaching and reef weakening worldwide.
  • Review of 220 studies from 1996–2025 reveals major biodiversity loss and high risk of reef collapse under warming.
  • The 2023–2025 global bleaching event impacted about 84 percent of reefs, the most severe on record.
  • Coral gardening, larval restoration, assisted evolution and connected marine protected areas boost reef resilience.
  • Emission cuts combined with local conservation, community stewardship and adaptive management are vital for reef survival.

Abstract

Coral reefs are one of the ecosystems that are most affected by climate change, but they also support biodiversity, coastal stability, fisheries, and tourism around the world. This review uses a structured narrative literature review based on PRISMA protocols to put together evidence from 220 peer-reviewed articles (1996 to 2025) to see how warming seas, ocean acidification, rising sea levels, and stronger storms change coral ecology, structure, and ecosystem functioning. The results indicate that heightened thermal stress is the principal catalyst of mass bleaching and mortality, occurring with greater frequency and at larger spatial scales, whereas ongoing acidification persists in diminishing calcification, skeletal density, and recruitment success. The rise in sea level and damage caused by storms make habitat loss happen even faster, make reefs less complex, and make communities of reef-associated species less stable. Even though things are going this way, new interventions like coral gardening, larval propagation, assisted evolution, marine protected areas, and community-led co-management show promise for making things more resilient in the face of future climate change. The review emphasizes the necessity of immediate global carbon reduction in conjunction with customized conservation and restoration strategies at the local level. If no strong action is taken, coral reefs may not last long, and the economic security they provide may also go down.

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Plasticity and adaptation in a changing ocean: a review of research trends and challenges

Published 24 February 2026 Science Closed
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Climate change and ocean acidification pose significant challenges to both terrestrial and aquatic ecosystems, making it critical to understand species’ vulnerability. Phenotypic plasticity and evolutionary adaptation are key mechanisms enabling organisms to cope with environmental shifts, with marine species appearing particularly susceptible. This semi-quantitative bibliometric review, conducted following PRISMA guidelines, examines research on climate change and ocean acidification impacts on marine organisms, focusing on plasticity and adaptation. We analysed 168 peer-reviewed articles published between 1995 and 2024 from Web of Science and Scopus. Publications remained low until 2013, then increased threefold, peaking in 2019, with the US, Australia, and China leading. Research predominantly addressed marine animals, especially fish, bivalves, and other invertebrates. Most studies focused on plasticity (57%) and examined molecular traits as response variables. Temperature, pH, and their combination were the most studied environmental drivers, whereas salinity and dissolved oxygen received little attention. Conceptual ambiguities in the use of plasticity and adaptation were noted. Our review highlights research gaps and emphasizes the need for integrated studies on plasticity and adaptation to better understand marine species’ vulnerability to climate change and ocean acidification and guide effective conservation and management strategies.

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Ocean acidification in Canada: the current state of knowledge and pathways for action

Published 23 February 2026 Science Closed
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Ocean acidification (OA) generally receives far less consideration than other climate stressors and related hazards, such as global warming and extreme weather events. Canada is uniquely vulnerable to OA given its extensive coastal oceans, the oceanographic processes in its three basins, accelerated warming and sea-ice melt, and extensive coastal communities and maritime economic sectors. Canada’s coastline is also home to extensive and diverse First Nations peoples with distinct histories, rights, title, laws, governance and whose traditions and cultures are extrinsically linked to the sea. However, there are currently very limited pathways to support OA action, mitigation, and/or adaptation in Canada, particularly at the policy level. Here, we present a first synthesis of the current state of OA knowledge across Canada’s Pacific, Arctic, and Atlantic regions, including monitoring, modelling, biological responses, socioeconomic and policy perspectives, and examples of existing OA actions and efforts at local and provincial levels. We also suggest a step-wise pathway for actions to enhance the coordinated filling of OA knowledge gaps and integration of OA knowledge into decision-making frameworks. The goals of these recommendations are to improve our ability to respond to OA in Canada, and minimize risks to coastal marine environments and ecosystems, vulnerable sectors, and communities.

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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’

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