Numerous studies have found that elevated CO2 levels in marine waters induced significant physiological and behavioral effects in fish. In an earlier study of coho salmon (Oncorhynchus kisutch), we observed that elevated CO2 exposure impaired signaling in the olfactory bulb, through a mechanism likely involving interference of gamma-aminobutyric acid (GABA) signaling. However, the effects of elevated CO2 may be species-specific, and there have been few studies addressing the effects of elevated CO2 on benthic fish. In the current study, we investigated the effects of elevated CO2 exposures on the deep-water benthic species, sablefish (Anoplopoma fimbria). Sablefish were exposed to three different levels of CO2 (700, 1600 and 2700 µatm) for two weeks, followed by behavioral, neurophysiological and gene expression analysis of the olfactory system. Analysis of behaviors mediated by food odors, including swimming activity and food strikes did not differ between fish maintained under elevated or control CO2 conditions. Similarly, electro-olfactogram recordings of odorant signaling did not differ among treatment and controls. mRNA expression patterns of olfactory bulb genes that were altered in coho salmon exposed to elevated CO2 levels, were similarly examined in sablefish. Sablefish mRNAs encoding genes involved in GABA-mediated olfactory bulb signaling were generally unaffected by high CO2, but aldh9a1, an enzyme involved in the synthesis of GABA, was elevated by high CO2. The results of our study contrast other studies demonstrating adverse effects of elevated CO2 in pelagic fish, but support differences among fish species to susceptibility to elevated CO2, potentially associated with life history traits.
Continue reading ‘Tolerance to future elevated CO2 conditions in sablefish (Anoplopoma fimbria), a deep-water benthic dwelling fish species’Posts Tagged 'performance'
Tolerance to future elevated CO2 conditions in sablefish (Anoplopoma fimbria), a deep-water benthic dwelling fish species
Published 26 March 2026 Science Leave a CommentTags: biological response, fish, laboratory, molecular biology, North Pacific, performance, physiology
Effects of rapid acidification in marine seawater: focus on Actinopterygii
Published 17 March 2026 Science ClosedTags: biological response, fish, morphology, mortality, performance, physiology, reproduction, review
Highlights
- The review reports physiological, behavioural, developmental and reproductive effects.
- Studies on Actinopterygii exposure to various pCO₂ levels are integrated.
- Fishes show strong species- and life-stage
specific vulnerability to high pCO2. - Most experiments with extreme CO₂ levels are short-term, limiting current knowledge.
Abstract
The progressive acidification of the world’s oceans has led to widespread concern regarding the potential consequences for marine biosphere. As a result, most research has been focused on the steady increase of dissolved CO₂ and consequent acidification thus on calcifying species while less attention has been paid to the physiological and developmental impacts of teleost fish. However, rapid and massive release of carbon dioxide (CO₂) into the marine environment may occur due to both natural and anthropogenic causes. This review specifically examines the outcomes of rapid but confined CO₂ emissions, with a focus on their role in accelerating the local acidification of seawater and on the related effects on Actinopterygii. It examines the impacts of elevated CO₂ levels on marine fishes, also emphasizing the lack of experimental evidence on embryonic larval and larval phases, which are highly vulnerable to acid-base imbalances and related physiological disruptions. A broad review of literature published between 1963 and 2025, on fishes’ exposure to varying CO₂ conditions, highlights pronounced variability in responses across species and developmental stages. Early life phases frequently exhibit reduced survival, skeletal and sensory anomalies, and shifts in metabolic demand. Although some taxa demonstrate compensatory adjustments, the resulting energetic costs and physiological trade-offs can limit growth, reproduction, and long-term resilience. Advancing our understanding of fish vulnerability and adaptive potential under seawater acidification of marine fishes in an acidifying environment requires long-term, ecologically relevant designs and integrated approaches that link multiple life stages and biological scales.
Continue reading ‘Effects of rapid acidification in marine seawater: focus on Actinopterygii’Eco-evolutionary dynamics of planktonic calcifying communities under ocean acidification
Published 12 March 2026 Science ClosedTags: adaptation, biological response, BRcommunity, calcification, communitymodeling, growth, modeling, mortality, otherprocess, performance, phytoplankton, primary production, zooplankton
Increasing emissions of CO2 into the atmosphere are causing ocean acidification, threatening calcifying organisms. In this study, we model the physiological responses of coccolithophorids to acidification to understand the ecological and evolutionary outcomes of a system in interaction with zooplankton. Assuming a trade-off between growth and protection against grazing, we show that calcification has bivalent effects on transfers between two trophic levels and that acidity can strongly alter energy transfers. Taking into account the evolution of calcifying phenotypes in response to acidification, we show that the system outcome contrasts with previous results. While the effect of evolution depends on how calcification affects grazing, it nevertheless follows that acidification leads to a decrease in calcifying capacity. This evolutionary decrease may be progressive, but can also lead to tipping points where abrupt shifts may occur. Such a counter-selection of calcification in turn affects ecosystem functioning, enhancing energy transfers within the system and modifying carbon fluxes. We discuss how such eco-evolutionary changes may impact food webs integrity, carbon sequestration into the deep ocean and therefore endanger the carbon pump stability.
Continue reading ‘Eco-evolutionary dynamics of planktonic calcifying communities under ocean acidification’Interactive effects of ocean acidification and settlement biofilm on the early development of the European abalone Haliotis tuberculata
Published 3 March 2026 Science ClosedTags: biological response, communityMF, laboratory, mollusks, morphology, multiple factors, North Atlantic, performance, phytoplankton, reproduction, respiration
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’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’Ocean acidification modifies site fidelity and patterns of seagrass habitat use by a herbivorous fish
Published 25 February 2026 Science ClosedTags: algae, biological response, BRcommunity, field, fish, Mediterranean, morphology, performance, physiology, vents
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.
Continue reading ‘Ocean acidification modifies site fidelity and patterns of seagrass habitat use by a herbivorous fish’Core transcriptional plasticity pave the way for fish to succeed in a high-CO2 world
Published 26 January 2026 Science ClosedTags: biological response, BRcommunity, field, fish, molecular biology, performance, South Pacific, vents
Ocean acidification (OA) can alter the physiological and behavioural traits of marine fishes, raising concerns about how wild species will adapt to rising pCO2. Using natural volcanic CO2 vents at White Island, New Zealand, as analogues for future OA conditions, we quantified behaviours in situ and sequenced the brain transcriptomes of four highly site-attached fish species from two vents and a nearby control site with ambient pCO2, of which two species exhibit increased population densities at the vent. We found that two species showed changes in habitat preferences, and all four species with significant changes in gene expression related to circadian rhythm, visual perception, and energy metabolism at the vents. Strikingly, three differentially expressed genes, a heat shock protein (HS90A) and two immediate early genes (IEGs: JUN and FOS), were central regulators for transcriptional changes across all species at the vents. Within the circadian entrainment pathway, expression changes in opsins may act as a trigger, while core clock genes and IEGs function as downstream effectors, suggesting that elevated pCO2 may reset the circadian clock in these fishes. Notably, the two species with increased populations at the vents exhibited distinct transcriptional responses in genes involved in calcium signalling, reproduction, intracellular pH regulation and energy metabolism. Together with convergent evolution in a calcium signalling gene and an HS90 facilitator, these molecular features may confer their reproduction advantages and ability to cope with elevated pCO2. Our study provides novel insights into the molecular mechanisms underlying fish responses to OA and highlights key pathways that may support survival and ecological success under a naturally high-CO2 world.
Continue reading ‘Core transcriptional plasticity pave the way for fish to succeed in a high-CO2 world’Neurometabolic rewiring in squid (Sepioteuthis lessoniana) optic lobes drives behavioral plasticity and visual integration under environmental acidification
Published 20 January 2026 Science ClosedTags: biological response, laboratory, molecular biology, mollusks, North Pacific, performance, physiology
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’Interactive effects of ocean acidification and benthic biofilm composition on the early development of the European abalone Haliotis tuberculata
Published 23 December 2025 Science ClosedTags: biological response, communityMF, laboratory, mollusks, morphology, multiple factors, North Atlantic, performance, phytoplankton, reproduction, respiration
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 individual and interactive effects of OA and algal density, acting through biofilm composition, on post-larval and juvenile abalone (Haliotis tuberculata). In a three-month 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 throughout the experiment. Biofilm biomass and composition 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 units) and highlight indirect macroalgal effects through changes in diatom communities. In natural environments, 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 benthic biofilm composition on the early development of the European abalone Haliotis tuberculata’Genotype and symbiont composition rather than environment influence susceptibility to stony coral tissue loss disease in coral restoration broodstock
Published 19 December 2025 Science ClosedTags: biological response, BRcommunity, corals, multiple factors, North Atlantic, performance, phytoplankton, temperature
Over the last several decades, Florida’s Coral Reef has been impacted by global and local stressors causing significant declines in living coral with no signs of natural recovery. Ocean warming, ocean acidification, and infectious diseases are major contributors to the precipitous loss of corals within this region. Since 2014, the stony coral tissue loss disease (SCTLD) outbreak has been particularly devastating, causing unprecedented mortality in over 20 massive coral species. As SCTLD is now endemic in the region, and threats from climate change are likely to persist, studying the disease susceptibility of different coral genotypes under future environmental scenarios is vital for effective restoration. Here, we exposed Orbicella faveolata and Pseudodiploria clivosa genotypes to wild colonies showing signs consistent with SCTLD immediately following a 2-month long exposure to ocean warming (OW) and ocean acidification (OA) scenarios. Corals were exposed to SCTLD for 3 weeks while maintaining the environmental treatments. For both species, pre-exposure to OW and OA scenarios did not make corals more susceptible to SCTLD. However, three genotypes hosting higher levels of Breviolum were at increased risk for showing SCTLD signs under these conditions. One O. faveolata genotype was consistently resistant to SCTLD under the different scenarios, suggesting that natural levels of resistance exist in coral restoration broodstock. Understanding why this genotype could withstand exposure to these stressors may be critical for ensuring survival of restored populations into the future.
Continue reading ‘Genotype and symbiont composition rather than environment influence susceptibility to stony coral tissue loss disease in coral restoration broodstock’A global meta-analysis reveals consistently negative effects of ocean acidification on marine cultured bivalves: implications for future bivalve aquaculture
Published 16 December 2025 Science ClosedTags: biological response, calcification, fisheries, growth, mitigation, mollusks, mortality, performance, physiology, reproduction, review
The exponential rise in atmospheric CO₂ driven by human activities is accelerating climate change and causing ocean acidification (OA). While the effects of elevated CO₂ on a wide range of marine species have been well documented, the implications of OA for bivalve aquaculture have received comparatively little attention. Using a multi-level meta-analytical approach, we evaluated the impacts of two elevated pCO₂ levels—classified as high and extreme—on cultured bivalves, based on 266 observations from 24 species across tropical and temperate regions. Overall, both elevated pCO₂ levels negatively affected bivalves, reducing survival, growth, feeding rates, development, and calcification. Larvae were generally more vulnerable than juveniles and adults. Our analyses further indicated that temperate bivalves were more sensitive to OA than tropical and subtropical counterparts. Among taxa, clams were the most vulnerable under high CO₂ emission scenarios, whereas scallops were the most sensitive under extreme pCO₂ levels. We also discuss potential mitigation strategies for the bivalve aquaculture industry. With advancements in local and regional monitoring, coupled with targeted measures such as buffering sites, selective breeding, and integrated multi-trophic aquaculture, the adverse effects of OA on bivalve farming could be mitigated.
Continue reading ‘A global meta-analysis reveals consistently negative effects of ocean acidification on marine cultured bivalves: implications for future bivalve aquaculture’Behavioral and physiological-biochemical responses of a polychaete (Perinereis aibuhitensis) under severe seawater acidification at different temperatures
Published 11 December 2025 Science ClosedTags: annelids, biological response, laboratory, multiple factors, performance, physiology, temperature
The intertidal zone experiences significant fluctuations in temperature and pH, posing significant challenges to marine organisms. Perinereis aibuhitensis, a eurythermal and euryhaline polychaete inhabiting estuaries, where pH is often lower than in the open ocean and further reduced within sediments, has likely evolved robust adaptations to such stresses. We investigated its behavioral, physiological, and metabolic responses under combined temperature (15°C, 20°C, 25°C) and seawater acidification (pH 5.5, 6.7, 8.0) conditions. P. aibuhitensis exhibited stable behavioral performance and metabolic homeostasis under control conditions (20°C, pH 8.0). It maintained burrowing activity and activated physiological and metabolic regulation at pH 6.7. However, its motion significantly declined with failed behavioral regulation under pH 5.5: radial undulation duration decreased by 97.63% and pumping volume by 97.97%. Energy was reallocated toward antioxidant defense and maintenance of basic physiological functions, reflected in downregulation of the γ-aminobutyric acid (GABA) metabolic pathway alongside upregulation of ABC transporter and arachidonic acid metabolism. At 25°C, combined warming and acidification disrupted energy allocation under pH 5.5. This disruption was accompanied by enhanced motion, which further constrained energy allocation, leading to significant oxidative damage (MDA content increased by 94.54%) and concurrently impairing tryptophan metabolism, glycerophospholipid metabolism, and ABC transporter function, with the entire cascade ultimately collapsing its adaptive mechanisms. This demonstrates that severe acidification, especially under warming, compromises bioturbation and metabolic stability in P. aibuhitensis, with potential negative impacts on polychaete communities and their vital ecological functions in intertidal ecosystems. Our findings provide critical insights for predicting climate change impacts on marine infauna.
Continue reading ‘Behavioral and physiological-biochemical responses of a polychaete (Perinereis aibuhitensis) under severe seawater acidification at different temperatures’Asymmetric effects of acidification and warming on foundation species and their predators in the California rocky intertidal zone
Published 11 December 2025 Science ClosedTags: algae, BRcommunity, calcification, laboratory, mesocosms, mollusks, morphology, multiple factors, North Pacific, performance, photosynthesis, respiration, temperature
The effects of climate change on marine organisms act through multiple pathways, as ocean warming and acidification can affect both their physiology and interspecies interactions. Asymmetries in species-specific physiological responses to climate change may alter the strength of interactions, such as those between predator and prey, which will have cascading effects on ecosystem structure. How foundation species and their interactions are affected by climate change will profoundly affect their community due to their dominance. I assessed the physiological responses of two common California rocky intertidal consumer–resource pairs across multiple trophic levels. I measured metabolic rates after four weeks of exposure to a range of nine pH levels (7.2–8.0) at two temperature levels (ambient, +4°C). At the lowest trophic level, I examined the effects of climate change on a primary producer foundation species, Silvetia compressa (golden rockweed), and its herbivore, Tegula eiseni, under differing upwelling regimes in early and late spring. Rockweed responded more to acidification than warming, decreasing photosynthetic rates in early spring and increasing rates during late spring. Their snail consumer, however, responded most strongly to temperature—increasing both respiration rates and calcification under warm conditions in late spring. In addition to species specific responses to climate stressors, the rockweed–snail pair had context-dependent responses based on background environmental conditions. Greater upwelling during late spring, combined with a younger snail population could explain differences in responses between early and late spring. Next, I examined asymmetries between a calcifying foundation species, Mytilus californianus, and its whelk predator, Nucella emarginata. Specifically, mussels were generally resistant to acute exposure to ocean warming and acidification, while whelks were highly sensitive to temperature. Whelks decreased their calcification, respiration, shell extension, and probability of drilling a mussel under warmer conditions. Across both experiments, I observed asymmetries in response to changes in pH and temperature between consumer and resource, which can shift ecosystems between bottom-up and top-down processes. Overall, I showed that mesopredators, such as herbivorous and carnivorous snails, appeared to be the most sensitive to changes in temperature relative to their foundation species prey. Climate change may reshape rocky intertidal communities by altering predation patterns on foundation species, which could either facilitate or threaten the survival of other associated species in a changing environment.
Continue reading ‘Asymmetric effects of acidification and warming on foundation species and their predators in the California rocky intertidal zone’Depth-resolved vertical distribution of the pteropod Limacina helicina in the Northeast Pacific and its implications for exposure to ocean acidification
Published 27 October 2025 Science ClosedTags: abundance, biological response, BRcommunity, field, mollusks, North Pacific, otherprocess, performance, review, zooplankton
The pteropod Limacina helicina has become an important bioindicator for the impacts of ocean acidification on marine ecosystems, yet its vertical distribution and diel vertical migration (DVM) patterns remain poorly understood. Understanding these behaviours is critical to accurately predict the risks of ocean acidification to pteropods since the depth ranges they inhabit strongly influence their exposure to water corrosive to aragonite shells (i.e. ΩAr <1), given the natural vertical gradients in pH and ΩAr. To resolve the vertical distribution of L. helicina, we utilized an existing dataset consisting of 179 vertically stratified zooplankton net tows from the Northeast Pacific spanning 1983–2019. Using conventional observational analyses and Bayesian statistical models, we determine and compare the average day and night vertical distributions of two size ranges of L. helicina, plus those of the strong vertical migrator euphausiid Euphausia pacifica and a non-migratory control group of mollusc larvae. We show that the average day and night vertical distributions and mean depths of L. helicina do not differ and closely match those of the non-migratory control, indicating that L. helicina does not perform DVM in this region. Typical mean depths of L. helicina are ∼50–70 m, with ≥ 75% of the population occupying the upper ∼100 m, and ≥ 50% being found in the upper ∼50 m, regardless of body size and time of day. Given the typical shape of ΩAr profiles in the ocean, we estimate that pteropod exposure to low ΩAr may be overestimated if calculated using the standard vertically integrated approach (i.e. a homogeneous depth distribution) as opposed to our depth-resolved vertical distribution.
Continue reading ‘Depth-resolved vertical distribution of the pteropod Limacina helicina in the Northeast Pacific and its implications for exposure to ocean acidification’Oxidative stress and histological alterations in coral Briareum violacea co-exposed to ocean acidification and microplastic stressors
Published 17 October 2025 Science ClosedTags: biological response, BRcommunity, corals, laboratory, morphology, multiple factors, North Pacific, performance, physiology, phytoplankton, plastics
Ocean acidification and microplastic pollution are two major stressors threatening coral health, yet their combined impacts and underlying mechanisms remain poorly understood. This study investigated the combined effects of ocean acidification and microplastics exposure to coral health. Briareum violacea was exposed to pH at 7.7, 7.5, and 7.3 combined with polyethylene microplastic (PE-MP; 50 mg/L) for 21 days. Polyp length and behavioral adaptability were monitored daily, while coral was collected on days 14 and 21 to assess Symbiodiniaceae density, antioxidant enzyme activity, and histopathological alterations. Results showed that combined exposure to different pH (7.7, 7.5, and 7.3) and PE-MP significantly impaired coral condition, reduced polyp length and Symbiodiniaceae density, along with intensified oxidative stress and tissue damage compared to single stressors. These findings underscore coral vulnerability under combined stressors, emphasizing the necessity for future research to address long-term ecological consequences and resilience mechanisms in coral reef ecosystems.
Continue reading ‘Oxidative stress and histological alterations in coral Briareum violacea co-exposed to ocean acidification and microplastic stressors’Warming, but not acidification, increases metabolism and reduces growth of redfish (Sebastes fasciatus) in the Gulf of St. Lawrence
Published 16 October 2025 Science ClosedTags: biological response, fish, fisheries, growth, laboratory, multiple factors, performance, physiology, temperature
Understanding the effects of global change, including temperature, pH, and oxygen availability, on commercially important species is crucial for anticipating consequences for these resources and their ecosystems. In the Gulf of St. Lawrence (GSL), redfish (Sebastes spp.) were under moratorium from 1995 to 2023, but the fishery has reopened in 2024 following massive recruitment observed in 2011–2013. Despite current high abundance, little is known about their metabolic and thermal physiology. To address this, we quantified the effects of four acclimation temperatures (2.5, 5.0, 7.5, and 10.0 °C) and two ocean acidification scenarios (current and future) on standard and maximum metabolic rates (SMR and MMR), aerobic scope (AS), factorial aerobic scope, hypoxia tolerance (O2crit), food consumption, growth and food conversion efficiency (FCE) in redfish (Sebastes fasciatus Storer, 1854). SMR, MMR, and AS increased with temperature, but growth and FCE decreased with temperature, likely due to increased cost of maintenance. Food consumption was lower at 2.5 °C, but similar at higher temperatures. Redfish were less hypoxia-tolerant at higher temperatures. Except for SMR, no significant effect of pH was observed. These results suggest that future changes in the GSL will challenge redfish, with potential long-term effects on growth due to increased energy requirements.
Continue reading ‘Warming, but not acidification, increases metabolism and reduces growth of redfish (Sebastes fasciatus) in the Gulf of St. Lawrence’Acute, static, and fluctuating ocean acidification effects on the olfactory system of the yellow shore crab, Hemigrapsus oregonensis
Published 8 October 2025 Science ClosedTags: biological response, crustaceans, laboratory, North Pacific, performance, physiology
Increases in atmospheric carbon dioxide (CO2) accelerate ocean acidification (OA), which has been shown to alter olfactory behaviours in marine organisms. Coastal regions currently experience pCO2 greater than end-of-century open ocean predictions with daily and seasonal fluctuations. Therefore, we hypothesized that marine organisms inhabiting the coastal regions are tolerant to the effects of OA. The acute, static, and fluctuating effects of acidification on the olfactory system were investigated in the coastal yellow shore crab (Hemigrapsus oregonensis (Dana, 1851)). After exposures, the olfactory behaviour to a food cue, putrescine, was measured, and changes in olfactory sensory receptors and neurons (OSNs) were determined using immunohistochemistry. Crabs took 3 times longer to locate the odorant and preferred it less after acute (minutes) and long-term (14 days) static exposures to OA. This impairment was correlated with a 16 to 30% decrease in olfactory receptor protein (IR25a) immunoreactivity and a 20% decrease in OSN volume. Crabs exposed to daily fluctuating pCO2 (7 days) displayed behavioural responses intermediate to crabs in control or static acidification conditions, and showed no changes in IR25a. These results indicate that despite their variable natural environment, yellow shore crabs are affected by acidification, being particularly vulnerable during sustained upwelling events (long-term static high pCO2).
Continue reading ‘Acute, static, and fluctuating ocean acidification effects on the olfactory system of the yellow shore crab, Hemigrapsus oregonensis’Effects of simulated ocean acidification on the activity, escape response, and muscle physiology of marine threespine stickleback (Gasterosteus aculeatus)
Published 19 September 2025 Science ClosedTags: biological response, fish, laboratory, North Pacific, performance, physiology
Rapidly increasing anthropogenic CO2 can impose physiological challenges for fish species that are thought to be tolerant. We tested the hypothesis that elevated pCO2 will affect the routine activity and escape response by affecting energy metabolism and/or the muscle physiology of coastal fish. We exposed threespine stickleback (Gasterosteus aculeatus) to pCO2 of ~ 700 µatm (pH 7.9 representing current levels), ~ 1400 µatm (pH 7.6 representing upwelling events) and ~ 3500 µatm (pH 7.3 representing a future predicted scenario for coastal areas) for 2 weeks. Baseline activity was significantly higher in fish exposed to 1400 µatm compared to the control at both sampling points, while the escape response was lower (p < 0.05). Metabolic rate was not different (p > 0.05), but lactate dehydrogenase activity was significantly higher at 3500 µatm compared to control fish after the first week (p < 0.05), while no difference was found in muscle histology between treatments or time points. Our study demonstrates that the baseline activity and escape responses of adult marine coastal fish were temporarily affected by the current level of ocean acidification, but this was not due to changes in metabolism or muscle function, but potentially neuronal effects of high pCO2. Our study shows that ocean acidification might affect predator‐prey interactions during current upwelling events and in the future.
Continue reading ‘Effects of simulated ocean acidification on the activity, escape response, and muscle physiology of marine threespine stickleback (Gasterosteus aculeatus)’Effects of ocean acidification on intestinal homeostasis and organismal performance in a marine bivalve: from microbial shifts to physiological suppression
Published 18 September 2025 Science ClosedTags: biological response, BRcommunity, community composition, laboratory, molecular biology, mollusks, morphology, North Pacific, otherprocess, performance, physiology, prokaryotes
Highlights
- OA stimulates the colonization of the pathogenic bacterium Mycoplasma.
- Microbiota dysbiosis and oxidative damage trigger intestinal inflammation.
- OA causes significant epithelial damage to the intestines of C. nobilis.
- Physiological suppression of C. nobilis is decreased in a pH-dependent manner.
Abstract
Ocean acidification (OA) poses significant threats to marine calcifiers through multifaceted physiological disruptions. While bivalve mollusks are particularly vulnerable, the intestinal defense mechanisms against OA-induced stress remain poorly characterized. This study systematically investigated the intimate associations between the organismal physiological toxicity responses and intestinal homeostasis of Chlamys nobilis (C. nobilis) under simulated OA situations (pH 7.3–8.0) to reveal the potential physiological and biochemical damage. The results revealed that acidification stimulated pathogenic bacteria(Mycoplasma)colonization, disrupted microbiota homeostasis, and induced oxidative responses, thereby triggering intestinal inflammation and epithelial damage. Furthermore, the filtration rates and oxygen consumption rates of C. nobilis were significantly decreased in a pH-dependent manner across all the treatments, which might result from the intestinal dysfunction and the inhibition of acetylcholinesterase activities. These findings establish a link between OA-induced intestinal dysbiosis and organismal physiology, providing novel insights into the interplay between physiological performance and intestinal homeostasis under OA scenarios. The results advance our understanding of bivalve mollusk adaptation strategies and inform predictive models for its sustainability in acidifying marine ecosystems.
Continue reading ‘Effects of ocean acidification on intestinal homeostasis and organismal performance in a marine bivalve: from microbial shifts to physiological suppression’Effect of ocean acidification on the metabolism and behavior of tropical sea cucumbers
Published 16 September 2025 Science ClosedTags: biological response, echinoderms, mitigation, performance, physiology, respiration, review
In recent years, CO₂ emitted by human activities has continued to rise. The ocean absorbs these CO₂ and has caused seawater acidification. It is expected that the pH of the sea surface will drop by 0.3~0.4 by the end of this century. Tropical sea cucumbers are the “engineers” of the subsea ecosystem, promoting organic degradation and nutrient circulation through feeding disturbances. This study reviews the effects of marine acidification on the metabolism and behavior of tropical sea cucumbers. Studies have shown that under low pH conditions, sea cucumbers have increased respiratory metabolic pressure, digestive enzyme activity is reduced, and more energy is used to maintain the acid-base balance in the body, and their growth and reproduction are limited. At the same time, sea cucumber feeding rate and defense behavior are inhibited, and habitat distribution may change. These changes will have a chain effect on tropical ecosystems such as coral reefs, weaken the nutrient circulation function, and affect ecological balance. In-depth research on the impact mechanism of marine acidification on sea cucumbers will help predict the response of marine ecosystems under climate change and provide scientific basis for resource conservation and aquaculture management.
Continue reading ‘Effect of ocean acidification on the metabolism and behavior of tropical sea cucumbers’
