Ocean warming and acidification are among the biggest threats to the persistence of coral reefs. Organismal stress tolerance thresholds are life stage specific, can vary across levels of biological organisation and also depend on natural environmental variability. Here, we exposed the early life stages of Pocillopora acuta in Kāne‘ohe Bay, Hawai‘i, USA, a common reef-building coral throughout the Pacific, to projected ocean warming and acidification scenarios. We measured ecological, physiological, biomineralisation and molecular responses across the critical transition from larvae to newly settled recruits following 6 days of exposure to diel fluctuations in temperature and pH in Control (26.8°C–27.9°C, 7.82–7.96 pHTotal), Mid (28.4°C–29.5°C, 7.65–7.79 pHTotal) and High conditions (30.2°C–31.5°C, 7.44–7.59 pHTotal). We found that P. acuta early life stages are capable of survival, settlement and calcification under all scenarios. The High conditions, however, caused a significant reduction in survival and settlement capacity, with changes in the skeletal fibre deposition patterns. Although there was limited impact on the expression of biomineralisation genes, exposure to High conditions resulted in strong transcriptomic responses including depressed metabolism, reduced ATP production and increased activity of DNA damage-repair processes, indicative of a compromised metabolic state. Collectively, our findings demonstrate that coral juveniles living in environments with large diurnal fluctuations in seawater temperature and pH, such as Kāne‘ohe Bay, can tolerate exposure to moderate projected increased temperature and reduced pH. However, under more severe environmental conditions, significant negative effects on coral cellular metabolism and overall organismal survival jeopardise species fitness and recruitment.
Continue reading ‘Thermal and acidification gradients reveal tolerance thresholds in Pocillopora acuta recruits’Posts Tagged 'morphology'
Thermal and acidification gradients reveal tolerance thresholds in Pocillopora acuta recruits
Published 1 October 2025 Science ClosedTags: biological response, corals, laboratory, molecular biology, morphology, mortality, multiple factors, North Pacific, reproduction, temperature
A window into the effect of ocean acidification on molluscan larval shell development using a quantitative approach
Published 30 September 2025 Science ClosedTags: biological response, laboratory, molecular biology, mollusks, morphology, North Pacific, reproduction
Increasing atmospheric CO2 levels have led to decreased pH and calcium carbonate saturation (Ω) of seawater, a process referred to as ocean acidification. Ocean acidification is expected to reduce biomineralization by marine calcifiers, such as molluscs, and many studies have reported serious effects on molluscan shell development. However, it has not previously been possible to quantitatively compare these effects on tiny structures, such as larval shells, among and within species. We applied the measurement technique of micro-focus X-ray computed tomography (MXCT) to larval shells of the limpet Nipponacmea fuscoviridis to quantitatively trace the process of shell growth (shell thickness and shell density). Shell thickness and density significantly decreased in seawater with low Ω levels. Scanning electron microscopy (SEM) revealed that the surface structure of the shell in larvae cultured under low Ω was disturbed. Gene expression analysis showed that the development of shell-forming regions under low Ω was significantly reduced. MXCT analysis can quantify mineralization in tiny larval shells; in combination with other methods such as SEM and gene expression analysis, it can provide a novel perspective in the assessment of the impact and resilience of marine calcifiers to changes in the marine environment.
Continue reading ‘A window into the effect of ocean acidification on molluscan larval shell development using a quantitative approach’4D insights into coral biomineralization: effects of ocean acidification on the early skeleton development of a stony coral
Published 24 September 2025 Science ClosedTags: biological response, corals, laboratory, morphology, Red Sea, reproduction
Coral biomineralization drives the formation of reef structures, but ocean acidification (OA) threatens this process. Coral survival requires effective skeletogenesis in early life stages, through the formation of co joined growth zones: rapid accretion deposits (RADs) and thickening deposits (TDs). Contrasting theories and lack of data on how these zones form hamper our understanding of normal coral growth and under future OA. This study describes growth patterns of RADs and TDs during the early stages of coral calcification under both normal and OA conditions. The work reveals geometric characteristics of RADs and TDs at micro- and sub-micrometer scales, as a basis for learning how OA impacts the early-formed skeletons. By combining material science approaches and Monte-Carlo simulations to model electron interactions that probe mineral phase composition, we show how TDs and RADs form simultaneously, challenging the classical “step-by-step” growth hypothesis. Unexpectedly, under normal pH, TDs comprise ≈65% amorphous calcium carbonate (ACC) and only 35% crystalline aragonite. Under OA, skeletons exhibit higher densities, with only 50% ACC. RADs are underdeveloped under OA, reducing skeletal bending resistance and increasing fracture risk. These findings reveal that the effect of OA on coral skeletogenesis is more complex than previously understood.
Continue reading ‘4D insights into coral biomineralization: effects of ocean acidification on the early skeleton development of a stony coral’Microplastic exposure under future oceanic conditions further threatens an endangered coral, Acropora cervicornis
Published 22 September 2025 Science ClosedTags: biological response, BRcommunity, corals, laboratory, morphology, multiple factors, photosynthesis, physiology, phytoplankton, plastics, South Atlantic, temperature
Microplastic pollution is ubiquitous in the oceans. However, little is known about the physiological impact of microplastics on corals, particularly under predicted future ocean conditions. This study investigated the individual impacts of microplastic exposure (MP) and predicted future ocean conditions [ocean acidification and warming (OAW)] as well as the combination of these stressors (OAW+MP) on the growth and physiology of Acropora cervicornis, a threatened Caribbean coral and its associated symbiont, Symbiodiniaceae. After 22 days, the OAW+MP treatment resulted in more pronounced physiological changes than either stressor individually or the control. OAW conditions alone had minimal impacts, despite A. cervicornis generally being sensitive to thermal stress. The OAW+MP treatment and the MP treatment also disrupted the host-symbiont relationship evidenced by the higher symbiont densities relative to the control and the OAW treatments. Additionally, the OAW+MP treatment resulted in lower chlorophyll a per symbiont cell. Microplastic handling is energetically costly, possibly leading to changes in host-symbiont signaling. Photosynthetic efficiency was only marginally lower in the OAW+MP treatment, and values did not indicate photosystem damage. Negative host health impacts were found with the OAW+MP treatment exhibiting lower skeletal growth compared to the control and lower host protein concentrations compared to the OAW treatment. These results indicate that although short term microplastic exposure alone may not pose a significant threat to coral health, when adding additional stressors, it can further threaten the health and recovery of this already vulnerable species.
Continue reading ‘Microplastic exposure under future oceanic conditions further threatens an endangered coral, Acropora cervicornis’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’Opposing physiological performances of two coexisting gastropods to changing ocean climate
Published 18 September 2025 Science ClosedTags: adaptation, biological response, growth, laboratory, mollusks, morphology, multiple factors, otherprocess, physiology, South Pacific, temperature
The impact of climate change on the structure of ecological communities will be influenced by how different species respond to changing environmental conditions. In this study, we investigated the effects of increased temperature (summer Control, 21 °C; HT, 24 °C) and elevated CO2 levels (Control, 400 ppm; OA, 1000 ppm) on two species of co-occurring temperate gastropods – Turbo undulatus and Austrocochlea odontis. Biological responses to simulated future conditions were measured as growth rates (shell and tissue) and metabolic rates across thermal ramps (temperatures ranging from 15 °C to 38 °C) after 8 weeks of exposure. We found that T. undulatus exposed to HT, OA or HT × OA conditions had a higher metabolic rate throughout their thermal curve than control conditions. In addition, the temperature at which individuals had maximum metabolic rate (TMMR) was higher in animals acclimated to HT × OA than in other conditions, potentially demonstrating acclimation. In contrast, A. odontis showed antagonistic effects in response to OA and HT; metabolism was lowest under OA but highest under HT. Furthermore, TMMR was reduced in A. odontis exposed to HT and the combination of HT x OA. In terms of growth, T. undulatus exposed to HT and HT × OA grew three times more in shell length and ∼20-30% in weight compared to the control group or those exposed to only OA. In contrast, no treatment had a significant effect on growth in A. odontis. Overall, our findings suggest that the impact of ocean acidification and heating on metabolic function can differ between coexisting species, possibly depending on their evolutionary and life history strategies, and these differential responses could have significant implications for the structure of ecological communities.
Continue reading ‘Opposing physiological performances of two coexisting gastropods to changing ocean climate’Seasonal impacts of ocean acidification and warming on coral physiology from pre- and post-summer temperature and pCO2 conditions of Acropora digitifera and Montipora digitata
Published 17 September 2025 Science ClosedTags: biological response, corals, morphology, multiple factors, North Pacific, physiology, temperature
This study examines the impact of ocean acidification (OA), ocean warming (OW), and combination of OA + OW on the physiology of branching corals Acropora digitifera and Montipora digitata before and after a summer bleaching event. The experiments were conducted in pre- and post-summer of 2017 to evaluate changing coral calcification rates and the maximum quantum yield of PSII (Fv/Fm). Our finding showed that both species experience reduced calcification rates and Fv/Fm under these stress conditions. Notably, the most severe impacts were observed in the post-summer period, suggesting that the prior summer conditions, including bleaching stress, exacerbated the effects of additional stressors. The increased sensitivity observed post-summer highlights the potential for synergistic impacts of multiple stressors, with prior exposure to high temperatures and bleaching events contributing to diminished thermal tolerance. These findings underscore the importance of considering the timing and cumulative effects of climate stressors on coral physiology. Further research is needed to explore the physiological and ecological mechanisms driving these seasonal responses to better predict and mitigate the impacts of climate change on coral reef ecosystems.
Continue reading ‘Seasonal impacts of ocean acidification and warming on coral physiology from pre- and post-summer temperature and pCO2 conditions of Acropora digitifera and Montipora digitata’Transgenerational plasticity responses differ across genetically distinct families in the Sydney rock oyster, Saccostrea glomerata
Published 12 September 2025 Science ClosedTags: adaptation, biological response, laboratory, mollusks, morphology, otherprocess, reproduction, respiration, South Pacific
Across the globe, marine organisms need to rapidly respond to climate change. Acclimation through the mechanism of transgenerational plasticity (TGP) is now at the forefront of research, providing hope that some marine organisms may persist into the future. To date, however, because most studies have focussed on the average phenotypic species response to climate change, we do not know whether phenotypic responses vary among genotypes. Here, we take a next critical step in TGP research to assess whether TGP responses to ocean acidification (OA) differ among genotypes of the culturally significant and iconic Sydney Rock Oyster (SRO), Saccostrea glomerata. Adults of four genetically distinct families of the SRO were exposed to ambient (410 μatm) and elevated (1000 μatm) pCO2 for 9 weeks during reproductive conditioning. Following this exposure, we performed a within family cross of each family and measured the percentage development, abnormality, shell length and respiration rate of D-veliger larvae after 48 hours in the same ambient and elevated pCO2 treatments. We found significant variability in TGP responses among families to elevated pCO2, with positive, negative, and neutral responses in larval offspring. How well we understand the adaptive potential of oysters and their capacity to mount fast responses through TGP to climate change will determine our ability to ensure the sustainability of SRO populations, marine food security and the cultural heritage of this iconic species. Combined approaches quantifying both genetic and non-genetic TGP responses are needed to determine the total adaptive potential of other marine organisms to climate change.
Continue reading ‘Transgenerational plasticity responses differ across genetically distinct families in the Sydney rock oyster, Saccostrea glomerata’Biological and genomic responses of juvenile Pacific oysters (Crassostrea gigas) to a changing ocean
Published 11 September 2025 Science ClosedTags: biological response, laboratory, molecular biology, mollusks, morphology, multiple factors, North Pacific, reproduction, temperature
Climate change, fueled by greenhouse gas emissions, is causing global atmospheric and oceanic temperatures to rise, accompanied by increased levels of carbon dioxide (CO₂) in the ocean, which has led to ocean acidification (OA). During warmer months, climate stressors (e.g. elevated temperatures), host physiology (e.g. reproductive efforts), and opportunistic pathogens like Vibrio spp. and Ostreid herpesvirus 1 (OsHV-1), coincide with each other, and exacerbate interactions into global phenomenon called oyster summer mortality syndrome, a multifactorial disease affecting oysters, particularly Crassostrea gigas (EFSA Panel on Animal Health and Welfare, 2015; Petton et al., 2015; Pernet et al., 2014). While many marine species, including bivalves (such as oysters, mussels, clams, and scallops), are adversely affected by heat and OA individually, there is relatively limited research on the combined effects of these stressors on either somatic growth or genomic responses. In this study, I investigated the individual and combined effects of temperature and pCO2 on various growth and genomic responses of juvenile Pacific oysters (Crassostrea gigas) (mean ± SD shell height: 16.6 ± 1.7 mm, wet weight: 0.47 ± 0.12 g for growth responses and shell height: 15.2 ± 1.3 mm, wet weight: 0.42 ± 0.09 g for genomic responses). Two factors (temperature and pCO2) at two levels (average summer level and IPCC-projected (RCP 8.5) future summer level) were tested in a fully-crossed experimental design, using six replicate tanks per treatment and 24 oysters per tank. Oysters were sampled at regular intervals (every 2 or 4 weeks) over 16 weeks to examine various shell biometrics (shell height, shell length, shell width, wet total weight, wet and dry shell weights, wet and dry soft-tissue weights, fan ratio, cup ratio, weight ratio) and condition index. A different subset of oysters were sampled at regular intervals (every 2 or 4 weeks) over 16 weeks for transcriptomic (RT-qPCR) analysis. Fourteen genes of interest (GOIs)—covering immunity, cellular stress, and metabolism responses—were chosen for study. The results showed that oysters were significantly impacted mostly by high temperature rather than high pCO2, both in individual and combined treatments, when analyzing both the growth and genomic results.
Growth results revealed that somatic growth, weight ratio and condition indices were negatively impacted by high temperature and minimally impacted by elevated pCO2. I found that shell growth in higher temperature conditions was growing at a faster rate than in ambient temperatures, but the amount of wet tissue in high temperature condition oysters was minimal, resulting in a higher weight ratio. Similarly, condition indices were drastically different when comparing the two temperature treatments, not pCO2. Unsupervised hierarchical clustering with principal component analysis revealed numerous clusters when comparing somatic growth, with most clusters relating to week, pCO2, and temperature. Genomic results revealed that nine of the GOIs (i.e. heat shock protein 23, heat shock protein 70, hypoxia-inducible factor 1-alpha inhibitor, V-type proton ATPase catalytic subunit A, multidrug resistance 1, toll-like receptor 7, transforming growth factor, protein kinase R, macrophage expressed protein 1) were significantly upregulated by temperature, compared to only two GOIs (metallothionein and 6-phosphofructokinase) that were significantly upregulated by pCO2. Heat shock 23 and heat shock 70 genes were deemed as being the most suitable for routine monitoring as early-warning signs of oyster summer mortality. Unsupervised hierarchal clustering with principal components analysis revealed only two major clusters when comparing genomic responses, driven primarily by temperature.
My results indicate that juvenile oysters are much more sensitive to heat exposure than high pCO2, with no additive effect of the two factors. Understanding how oyster growth and genes respond to both individual and combined climate-change stressors is crucial for improving predictions of oyster performance under future climate scenarios and for enhancing the sustainability of shellfish aquaculture systems that are increasingly affected by heatwaves and low-pH upwelling events. Ongoing research is essential to investigate oyster responses in controlled, environmentally-relevant, multi-stressor experiments, providing deeper insights into the potential impacts of concurrent climate change stressors and extremes on both natural and cultivated oyster populations.
Continue reading ‘Biological and genomic responses of juvenile Pacific oysters (Crassostrea gigas) to a changing ocean’Ocean acidification disrupts the biomineralization process in the oyster Crassostrea virginica via intracellular calcium signaling dysregulation
Published 3 September 2025 Science ClosedTags: biological response, laboratory, molecular biology, mollusks, morphology, North Atlantic, physiology, reproduction
Anthropogenically increased atmospheric carbon dioxide (pCO2) leads to ocean acidification, disrupting calcification in marine calcifiers by reducing the saturation state of calcium carbonate. Calcium is not only a crucial component in the shell and skeleton structure but also serves as an essential second messenger for regulating biomineralization across many species. Ocean acidification is well-studied as causing shell dissolution in a diversity of bivalve species by disordering calcium deposition. However, it remains unclear whether the calcium-mediated signaling pathway regulating biomineralization is also affected. This study assessed eastern oyster (Crassostrea virginica) to determine how calcium signaling responds to elevated pCO₂ and influences shell formation. Under elevated pCO2, increased intracellular calcium concentration was found in primary epithelial cell cultures from oyster mantle. Meanwhile, we observed upregulation of calmodulin, a primary sensor of intracellular calcium, while its downstream effector, calcineurin, was downregulated. In addition, four conserved shell matrix proteins (SMPs), representing shell construction conditions, were significantly upregulated in the CO2-exposed mantle cells. In vivo, larval C. virginica exhibited developmental stage-dependent alterations in calcium signaling and SMPs disarrangement stimulated by pCO2. We hypothesize that dysregulation of calcium signaling disrupts the expressions of SMPs and causes oyster shell deformation. Pharmaceutical blockage of the calcium-calmodulin binding induced abnormal expression of related genes and shell matrix changes consistent with those caused by elevated pCO2, both in vivo and in vitro. Importantly, calcineurin restored SMPs expression in CO2-treated mantle cells. These findings suggest that shell deformities under ocean acidification are related to disruption of the calcium-calmodulin signaling pathway, inhibiting calcineurin activity and affecting SMPs production.
Continue reading ‘Ocean acidification disrupts the biomineralization process in the oyster Crassostrea virginica via intracellular calcium signaling dysregulation’What doesn´t kill you makes you stronger: the sea urchin Arbacia lixula living on volcanic CO2 vents
Published 1 September 2025 Science ClosedTags: adaptation, biological response, echinoderms, field, morphology, North Atlantic, otherprocess, vents
Anthropogenic CO2 emissions drive ocean acidification (OA), which reduces seawater pH and carbonate ion availability, threatening calcifying organisms such as sea urchins. This study examines the long-term effects of OA on Arbacia lixula using a natural volcanic CO2 vent at Fuencaliente, La Palma (Canary Islands) as an analogue of future conditions. We analyzed the external morphology, skeletal strength, mineralogy, and growth of A. lixula across three sites that differed consistently in mean pH (from 8.14 to 7.65 during low tide). Sea urchins from low pH conditions were smaller, with shorter spines and reduced jaw-to-diameter ratios, yet their tests showed higher fracture resistance than those from ambient conditions. Additionally, individuals from acidified zones showed altered growth dynamics, with fewer growth rings. Skeletal changes and growth alterations are consistent with modified mineralization processes and dietary shifts toward non-calcareous food sources. This study highlighting the morphological plasticity and resilience of A. lixula under persistent natural acidification, offering insight into how sea urchins may respond in a high-CO2 ocean.
Continue reading ‘What doesn´t kill you makes you stronger: the sea urchin Arbacia lixula living on volcanic CO2 vents’Simulated ocean acidification affects shark tooth morphology
Published 29 August 2025 Science ClosedTags: biological response, fish, laboratory, morphology
Changing ecological factors pose a challenge to many organisms. Global changes and the associated environmental changes have major impacts on marine organisms and threaten the biodiversity of marine ecosystems. It has been shown in previous experimental studies that ocean acidification caused by anthropogenic CO2 release into the atmosphere and subsequent dissolution in seawater will have a significant impact on various marine organisms. Here, we investigated the corrosive effects from acidification on the morphology of isolated shark teeth in an eight-week incubation at a pH of 7.3, the expected seawater pH in the year 2300. The typical littoral blacktip reef shark (Carcharhinus melanopterus), which is often kept in display aquaria under controlled conditions, has been used for this purpose, greatly facilitating minimally invasive sampling for in-situ investigation. The teeth of this typical Requiem Shark species are orthodont teeth, which show strong serration in the teeth of the upper jaw. Using scanning electron microscopy (SEM) we could observe the corrosive effects of acidification on the different tooth structures, such as the root, primary and secondary serrations and the crown of the blacktip reef sharks teeth. Our results show that ocean acidification will have significant effects on the morphological properties of teeth, including visible corrosion on the crown, degradation of root structures, and loss of fine serration details under low pH conditions which could lead to changes in foraging efficiency, energy uptake, and ultimately elasmobranch fitness in future oceans.
Continue reading ‘Simulated ocean acidification affects shark tooth morphology’Acclimation mechanisms of reef-building coral Acropora gemmifera juveniles to long-term CO2-driven ocean acidification
Published 27 August 2025 Science ClosedTags: adaptation, biological response, corals, laboratory, molecular biology, morphology, North Pacific, otherprocess, physiology, reproduction
Ocean acidification (OA) is a major threat to the sexual recruitment of reef-building corals. Acclimation mechanisms are critical but poorly understood in reef-building corals to OA during early life stages. Here, Acropora gemmifera, a common Indo-Pacific coral cultured in in situ seawater from Luhuitou reef at three levels of pCO2 (pH 8.14, 7.83, 7.54), showed significantly delayed larval metamorphosis and juvenile growth, but adapted to long-term high pCO2. Differentially expressed genes (DEGs) emerged as a time- and dose-dependent mode of short-term response (3 days post settlement, d p.s.) and long-term acclimation (40 d p.s.), with more DEGs responding to high pCO2 (pH 7.54) than to medium pCO2 (pH 7.83). High pCO2, a presumed threatening seawater baseline for A. gemmifera juveniles, activated DNA repair, macroautophagy, microautophagy and mitophagy mechanisms to maintain cellular homeostasis, recycle cytosolic proteins and damaged organelles, and scavenge reactive oxygen species (ROS) and H+, but at the cost of delayed development through cell cycle arrest associated with epigenetic and genetic regulation at 3 d p.s.. However, A.gemmifera juveniles acclimated to high pCO2 by up-regulating cell cycle, transcription, translation, cell proliferation, cell-extracellular matrix, cell adhesion, cell communication, signal transduction, transport, binding, Symbiodiniaceae symbiosis, development and calcification from 3 d p.s. to 40 d p.s., when energy reallocation and metabolic suppression occurred for high demand but short-term energy limitation in coral cells undergoing flexible symbiosis. All results indicate that acclimation mechanisms of complicated gene expression improve larval and juvenile resilience to OA for coral population recovery and reef restoration.
Continue reading ‘Acclimation mechanisms of reef-building coral Acropora gemmifera juveniles to long-term CO2-driven ocean acidification’Impacts of ocean acidification on survival of the brown mussel (Perna perna) in Brazil
Published 27 August 2025 Science ClosedTags: adaptation, biological response, fisheries, growth, laboratory, mollusks, morphology, mortality, otherprocess, South Atlantic
The impacts of ocean acidification (OA) on seafood are recognized globally as a major threat, and OA is explicitly mentioned in the United Nations 2030 Agenda for Sustainable Development. One target of Goal 14 (SDG 14.3), life below water, is to minimize and address the impacts of OA using all levels of scientific cooperation. In 2018, the International Atomic Energy Agency launched a Coordinated Research Project (CRP), which gathered researchers from 13 different countries and aimed to evaluate the quantitative and qualitative impacts of OA on seafood. The Brazilian brown mussel Perna perna (Linné, 1858) was selected as the target species for these experiments. Low pH can disrupt the life cycle, affect survival and growth rates, and lead to a decline in mussel populations over time. Based on an agreed protocol within the CRP network, brown mussels were exposed to pH scenarios covering the present and future range of pH variability at the sampling site. The impacts on mortality, growth rate, and morphological parameters of juvenile mussels (seed) were evaluated after a 15-wk exposure in the laboratory, followed by an 8-wk recovery period in situ. Although no effect was detected for growth rate and allometric relationships during the laboratory experiment, mussel mortality was significantly higher at low pH. This effect on mortality disappeared when mussels were transferred to the field for a recovery period, and the acclimation to low pH had no carry-over effect on growth, allometric relationships, or sensory quality. Evidence of impacts from chronic lowering of pH is still needed to address species adaptation for long-term changes, which limit the prognostic power of short-term experiments.
Continue reading ‘Impacts of ocean acidification on survival of the brown mussel (Perna perna) in Brazil’Within and cross-generational effects of elevated seawater pCO2 on larval bay scallops Argopecten irradians (L)
Published 27 August 2025 Science ClosedTags: adaptation, biological response, growth, laboratory, mollusks, morphology, mortality, North Atlantic, otherprocess, reproduction
Bivalve larvae are highly susceptible to ocean acidification (OA), but there is little knowledge of the capacity of bivalve species to acclimate or adapt to changing ocean conditions. It is challenging to compare results among studies of OA reported in the literature, as there is little consistency among studies in water chemistry across OA treatments used or how OA conditions were determined. In addition, it is difficult to predict from short-term experiments how populations might respond across generations. The bay scallop, Argopecten irradians, is a good model species for such experiments because of its short generation time and importance commercially and ecologically. Bay scallops were exposed to OA conditions from embryos to metamorphosis across two generations. Ocean acidification treatment levels included historical or preindustrial “low” (pCO2 ∼450 µatm), current average “moderate” (∼800 µatm), and future “high” (∼1,350 µatm). In the first generation, high OA had negative effects on larval performance, with no survival to metamorphosis, preventing its inclusion in the second generation. Moderate OA reduced performance (survivorship and growth) relative to the low OA. In the second generation, however, there was no difference in survival between the moderate and low OA treatments, but the difference in size at metamorphosis remained. These results suggest that over two generations, bay scallops either acclimated or adapted to moderate OA. Further work is needed to determine the extent to which long-term, generational adaptation to OA is possible in the bay scallop.
Continue reading ‘Within and cross-generational effects of elevated seawater pCO2 on larval bay scallops Argopecten irradians (L)’Metabolomics analysis provides new insights into the impacts of long-term ocean acidification and warming on the sensory qualities of sea urchin (Strongylocentrotus intermedius) gonads
Published 26 August 2025 Science ClosedTags: biological response, echinoderms, fisheries, laboratory, morphology, multiple factors, North Pacific, physiology, temperature
Highlights
- Ocean acidification and warming (OAW) alter the color of sea urchin gonads.
- OAW reduce the size and weight of sea urchin gonads.
- OAW alter contents of flavor and odor-related compounds in sea urchin gonads.
- OAW affect the quality of female gonads more seriously than that of males.
Abstract
Sea urchin gonads are popular raw, ready-to-eat seafood known for their fresh, sweet taste and high nutritional value. To investigate the impacts of ocean acidification and warming (OAW) on the sensory qualities of sea urchin gonads, farmed Strongylocentrotus intermedius were incubated separately and jointly in acidic (ΔpHNBS = −0.5 units) and thermal (ΔT = +3.0 °C) seawater for 90 days under lab-controlled conditions based on the ocean pH and temperature for 2100 projected by the Intergovernmental Panel on Climate Change (IPCC). Sensory properties (gonad size, color, and flavor-related metabolites) were subsequently determined and compared between groups. The results showed that: 1) The gonad size and gonad index (GI) decreased sharply (−49 % in female; −46 % in male) under OAW conditions in both sexes of adult S. intermedius. There were significant negative additive effects of acidification and high temperature on the GI. 2) OAW had no significant interaction effects on five gonadal color-related parameters; however, the redness (a*) of male gonads was significantly less than that of female gonads in both the separate and joint OAW groups. 3) Significant alterations to metabolome profiles, exhibiting sex-specific variations, were observed in adult S. intermedius incubated under separate/joint OAW conditions. Twenty-two significantly differentially expressed metabolites (SDMs) related to color, odor, and flavor were identified, primarily enriched in metabolic pathways associated with the biosynthesis and accumulation of odor and flavor compounds. To sum up, the data from this study indicate that OAW affect sensory qualities of sea urchin gonads negatively especially the gonads of females.
Continue reading ‘Metabolomics analysis provides new insights into the impacts of long-term ocean acidification and warming on the sensory qualities of sea urchin (Strongylocentrotus intermedius) gonads’The influence of cross-generational warming on the juvenile development of a coral reef fish under ocean warming and acidification
Published 20 August 2025 Science ClosedTags: adaptation, biological response, fish, laboratory, morphology, multiple factors, otherprocess, performance, physiology, reproduction, South Pacific, temperature
Marine ecosystems are facing escalating chronic and acute environmental stressors, yet our understanding of how multiple stressors influence individuals is limited. Here, we investigated how projected ocean warming (+1.5°C) during grandparental (F1) and parental (F2) generations of the spiny chromis damselfish (Acanthochromis polyacanthus), influences the sensitivity of F3 juveniles to ocean warming (present-day vs +1.5°C) and/or elevated CO2 (490 μatm vs 825 μatm). After 16 weeks of exposure, aerobic physiology (resting oxygen consumption, maximum oxygen consumption, and absolute aerobic scope), behaviour (boldness and activity), and growth (length and physical condition) were measured in F3 juveniles and the relationships between these performance traits was explored. We found that warming during F3 development resulted in juveniles that were shorter, bolder, and in better physical condition, while elevated CO2 resulted in shorter juveniles with a reduced resting oxygen consumption. However, across juvenile performance traits there was no interaction between ocean warming and acidification, demonstrating the additive nature of these two environmental stressors. Although we found limited signs of transgenerational plasticity, there was evidence of parental and grandparental carry-over effects which resulted in juveniles that were larger and/or in better condition when grandparents and parents experienced warming during their development regardless of the F3 juvenile developmental treatment. These finding illustrate the significant role phenotypic plasticity has on juvenile performance under projected future climate change.
Continue reading ‘The influence of cross-generational warming on the juvenile development of a coral reef fish under ocean warming and acidification’Ocean acidification changes diet effects and differentially impacts two populations of red abalone (Haliotis rufescens)
Published 15 August 2025 Science ClosedTags: adaptation, biological response, mollusks, morphology, mortality, multiple factors, North Pacific, otherprocess, physiology, reproduction
Absorption of CO2 by global oceans is decreasing pH resulting in ocean acidification (OA). Impacts on shellfish have been documented in ecologically and commercially important species. We examined the influence of diet and OA between two populations of red abalone (Haliotis rufescens) a species of aquaculture importance and declining wild populations. Populations experience different exposure histories: strong upwelling (Van Damme, California [VD]) historically exposed to low-pH conditions and weak-intermittent upwelling (Santa Barbara, California [SB]). Abalone were cultured under control-pH or OA-conditions and fed crustose coralline algae (CCA) or diatoms used in aquaculture. We tested treatment effects of population, settlement diet, and OA-exposure on survival as influenced by larval-energy stores. Survival in both populations was enhanced by CCA when cultured under both treatment conditions; however, by later stages, this effect remained only for SB. SB had reduced post-settlement survival when cultured under OA-conditions, whereas post-settlement survival of VD was not. Diet affected the relationship between larval-energy and post-settlement survival; a positive relationship when fed diatoms and a negative relationship with CCA. The relationship between larval-energy and post-settlement survival was stronger in VD. CCA enhanced juvenile growth in SB cultured abalone at both three-months and one-year post-settlement. Settlement diets can reduce the impacts of OA on early-life stages of abalone, but population differences driven by underlying energetics affect the consistency of this outcome. These findings illuminate the impacts from OA, suggesting populations may be at risk, and inform strategies for developing and sustaining shellfish aquaculture in the face of changing ocean conditions.
Continue reading ‘Ocean acidification changes diet effects and differentially impacts two populations of red abalone (Haliotis rufescens)’Molecular markers of stress in the sea urchin embryo test: analysing the effect of climate change and pollutant mixtures on Paracentrotus lividus larvae
Published 15 August 2025 Science ClosedTags: biological response, echinoderms, laboratory, molecular biology, morphology, multiple factors, North Atlantic, plastics, reproduction, temperature, toxicants
Highlights
- Combined effects of ocean stressors on sea urchin larvae were analysed.
- RNA-seq revealed key transcriptional changes under stressor combinations.
- Larval growth and deformities worsened with acidification and warming.
- Biomarkers for early detection of stress in marine larvae were identified.
- Insights contribute to predicting organismal responses to climate change.
Abstract
Climate change and pollution represent critical stressors for marine ecosystems, particularly for calcifying organisms such as the sea urchin Paracentrotus lividus. This study examines the combined effects of ocean acidification (OA), ocean warming (OW), and microplastics (MP) loaded with chlorpyrifos (CPF), a broad-spectrum organophosphate insecticide, on sea urchin larvae, evaluating growth and molecular endpoints. Experimental treatments simulated future ocean conditions predicted for 2100, exposing larvae to varying temperature and pH levels, alongside CPF-contaminated MP. RNA sequencing (RNA-seq) was utilized to assess gene expression changes, revealing significant transcriptional shifts in metabolic, cellular, and developmental pathways. Morphological responses showed reduced larval growth, exacerbated under OA and OW conditions. Molecular analyses identified key upregulated pathways associated with stress response, including nitrogen metabolism and extracellular matrix remodelling, while downregulated genes involved DNA stability, cell cycle regulation, and enzymatic activities. These findings suggest a dual compensatory and deleterious response to combined stressors. Notably, temperature acted as a modulator of stressor effects, amplifying oxidative stress and metabolic costs at higher temperatures. Potential biomarkers, such as genes involved in actin regulation and embryonic development, were identified, offering possible tools for early detection of environmental stress. This study highlights the compounded impacts of anthropogenic and climate-induced stressors on marine invertebrates, emphasizing the need for integrative molecular approaches in ecotoxicology. Our findings contribute to the understanding of organismal adaptation and vulnerability in the face of global climate change and pollution, informing conservation strategies for marine ecosystems.
Continue reading ‘Molecular markers of stress in the sea urchin embryo test: analysing the effect of climate change and pollutant mixtures on Paracentrotus lividus larvae’Tubastraea coccinea (Lesson, 1830), a coral species with high invasive potential, can benefit from the synergistic effects of ocean warming and acidification
Published 14 August 2025 Science ClosedTags: biological response, calcification, corals, laboratory, morphology, multiple factors, North Atlantic, reproduction, respiration, temperature
Temperature rise and pH decrease, coupled with increasing maritime traffic, are inducing modifications in the distribution of many exotic species, such as Tubastraea coccinea, a species with high invasive potential recently recorded in the Canary Islands. This study assessed the effect of the expected end-of-century temperature and pH (26°C and pH 7.50) on this coral species through manipulative laboratory experiments conducted over different time periods (30 days vs. 80 days). The impact of acidification, warming, and time on variables such as weight, buoyant weight, number of new polyps, area, respiration, calcification and reproduction rates were analysed. Results revealed a negative effect of acidification on growth and respiration rates of T. coccinea, with significant differences between experimental treatments in weight, buoyant weight, number of polyps, area, and respired carbon. However, in future, T. coccinea may not be adversely affected by low pH values, as the negative effect is mitigated when colonies are exposed to 26°C. Using different experimental periods showed how this species’ response is liable to change over time under future climate change conditions.
Continue reading ‘Tubastraea coccinea (Lesson, 1830), a coral species with high invasive potential, can benefit from the synergistic effects of ocean warming and acidification’
