Environmental changes in the ocean can impose significant physiological costs and morphological changes to many marine organisms, and early life stages such as eggs and larvae are predicted to be particularly vulnerable to climate change drivers including warming and acidification. Although sensitivity to ocean change stressors during development has the potential to influence the performance, and ultimately the recruitment, of postlarvae and juveniles, the nature and strength of physiological modifications during embryo development is understudied in the ecologically and economically important American lobster Homarus americanus. We investigated the long-term, interactive impacts of ocean acidification and ocean warming on the development and physiology of brooded lobster embryos. We exposed ovigerous females to a combination of 2 temperatures and 2 pH levels for 5 mo, throughout which we measured development, metabolic rate, biochemical composition, and enzyme activity in their brooded embryos. The physiology of American lobster embryos appears to be robust to ocean acidification conditions but sensitive to warming, particularly for metabolic traits. We also found that warming induced a reduction in the size of freshly hatched larvae. Understanding how environmental change influences these early life stages of lobsters can improve predictions for how this species will fare in a changing ocean environment.
Continue reading ‘Effects of multiple stressors on embryos and emerging larvae of the American lobster’Posts Tagged 'reproduction'
Effects of multiple stressors on embryos and emerging larvae of the American lobster
Published 14 October 2025 Science ClosedTags: adaptation, biological response, crustaceans, laboratory, morphology, multiple factors, North Atlantic, otherprocess, physiology, reproduction, temperature
Identification of chitinase family members in the Crassostrea gigas and the expression patterns of Cgamcase-1 under ocean acidification
Published 14 October 2025 Science ClosedTags: biological response, laboratory, molecular biology, mollusks, morphology, reproduction
Chitinase, as a crucial enzyme for the degradation of chitin, is involved in the construction of the chitin framework during the process of shell formation. In order to identify the members of the chitinase gene family in Crassostrea gigas and investigate their response to acidification, bioinformatic methods were employed to identify the chitinase family members and analyze their expression patterns. Eleven members of the chitinase family were identified from the C. gigas genome. All gene members contained the Glyco-18 domain, and some genes also contained the chitin-binding domain ChtBD2. These genes were predominantly located on chromosome 2, 5, 6, and 7. In the C. gigas, the chitinase family genes were clearly divided into two branches which were endochitinases and exochitinases. The chitinase family expressed across all developmental stages of the C. gigas larvae. With the development of larva, the expression level of five genes increased gradually. The expression levels of most chitinase family genes were higher in the mantle compared to other tissues. The acidic mammalian chitinase (Cgamcase-1) exhibited high expression level in the mantle, with the highest expression level in the outer fold (OF). The expression patterns of Cgamcase-1 in response to acidification were analyzed. After 3, 7, and 14 days of acidification stress, the mRNA expression of Cgamcase-1 in the mantle was 3.010-fold (P < 0.05), 4.557-fold (P < 0.001) and 4.129-fold (P < 0.001) of that in the control group, respectively. After 7 days of acidification stress, the mRNA expression of Cgamcase–1 in OF was 3.598-fold of that in the control group (P < 0.05). In situ hybridization results revealed that the positive signals for the Cgamcase-1 probe were primarily concentrated in the epithelial cell region of the outer fold, and the intensity of the positive signals significantly increased after 7 days of acidification stress, while it significantly decreased after 14 and 28 days. The study suggested that chitinase family genes might be involved in the process of larval development and adult shell formation. Cgamcase-1 participated in chitin degradation and responding to ocean acidification. This research provided important theoretical evidence and reference for understanding the role of chitinase in the shell formation process of the C. gigas and their response mechanisms under ocean acidification.
Continue reading ‘Identification of chitinase family members in the Crassostrea gigas and the expression patterns of Cgamcase-1 under ocean acidification’Global meta-analysis reveals the impacts of ocean warming and acidification on kelps
Published 9 October 2025 Science ClosedTags: algae, biological response, multiple factors, physiology, reproduction, review, temperature
Kelp forests are among the most diverse and productive ecosystems in the world, providing critical habitat for numerous ecologically and economically important species. However, kelps are at risk from climate change, and declining populations worldwide demonstrate the need to characterize and quantify the effects of anthropogenic stressors on kelp physiology. Here, we performed a meta-analysis on true kelps (order Laminariales) in response to ocean warming and acidification based on a global synthesis of 7000 data points from 143 experimental studies. Our results show that ocean warming has a strong negative impact on kelps at all life stages and across various physiological levels, including growth, reproduction, and survival. In contrast, ocean acidification generally has no effect, except for its negative impact on reproduction. In most cases, co-occurring warming and acidification acted synergistically. Response to warming, acidification, and multiple driver scenarios increased as the intensity and duration of exposure increased. In our analyses, the genera Eualaria, Hedophyllum, Lessonia, and Postelsia were among the most vulnerable to warming. Studies conducted in the temperate northern Pacific showed extreme negative effects of warming. We also identify key gaps in our understanding of kelp responses to climate change, such as the impacts on microscopic spores and the combined effects of warming and acidification. This analysis synthesizes trends in a rapidly expanding field of literature and provides a deeper understanding of how kelps will respond to a rapidly changing ocean.
Continue reading ‘Global meta-analysis reveals the impacts of ocean warming and acidification on kelps’The impact of an early exposure to 17α-ethynylestradiol on the physiology of the three-spined stickleback (Gasterosteus aculeatus) under current and future climatic scenarios
Published 9 October 2025 Science ClosedTags: biological response, fish, laboratory, molecular biology, morphology, mortality, multiple factors, reproduction, temperature, toxicants
Highlights
- RCP8.5 scenario modulated some of the long-lasting physiological responses to EE2.
- RCP8.5-EE2 group led to sex and tissue specific responses.
- RCP8.5-EE2 scenario resulted in lower body length at five months post-contamination.
- RCP8.5 reduced survival rate of embryo-larval but not juvenile stages.
- Early-life exposure to EE2 led to stickleback feminisation.
- Early-life exposure to EE2, led to long-lasting effect on stickleback physiological responses.
Abstract
Ocean warming and acidification are climate change related drivers that impact the physiology of marine organisms and their ability to cope with future environments. Marine ecosystems are also facing pollution from an ever-growing diversity of chemical contaminants, including endocrine disruptors. A common example is the 17α-ethynylestradiol (EE2), which can affect the endocrine regulation of fish and hence potentially impact their fitness. Thus, fish have to cope to multiple climatic and chemical stresses that can interact, influencing the overall impact on fish physiology. In this study, we investigated whether the direct and carry-over effect of early exposure to EE2 (15 ng.L−1; one month during embryo-larval development) are modulated by the RCP8.5 scenario (+3°C; -0.4 pH unit). Five months post-contamination, we measured survival, growth and reproductive axis of prepubertal sticklebacks. Our findings revealed that the survival of juveniles, when exposed to EE2 during early development, is reduced under Current but not RCP8.5 scenario. Furthermore, under RCP8.5-EE2, a significantly lower body length was observed. Sex and tissue specific responses in terms of the expression profiles of genes related to development and sexual maturation was reported. Interestingly, significant interaction between RCP8.5 and EE2 was observed for the expression of ovarian aromatase (cyp19a1a), suggesting a long-lasting estrogenic effect under RCP8.5 scenario. Additionally, the skewed sex ratios and the presence of intersex individuals in both scenarios early exposed to EE2 suggested a feminization due to EE2, which could potentially disrupt sexual maturation and future reproduction. Hence, the early EE2 exposure had carry-over physiological effects on sticklebacks, and these effects can be modulated by the climate scenario. This underscores the importance of conducting long-term multi-stress studies to comprehensively understand the vulnerability on fish populations in future environments.
Continue reading ‘The impact of an early exposure to 17α-ethynylestradiol on the physiology of the three-spined stickleback (Gasterosteus aculeatus) under current and future climatic scenarios’Climate change and its effects on fish growth and physiology
Published 8 October 2025 Science ClosedTags: biological response, fish, growth, physiology, reproduction, review
Climate change, driven by anthropogenic greenhouse gas emissions, poses significant threats to aquatic ecosystems, particularly impacting fish physiology, growth, reproduction, and distribution. This article explores how rising temperatures, ocean acidification, and declining oxygen levels affect fish by altering metabolic rates, reducing oxygen availability, and disrupting physiological and behavioral processes. Species-specific thermal tolerances and susceptibility to hypoxia and acidification influence growth rates, survival, and reproductive success, especially during early developmental stages. Additionally, shifts in habitat and migration patterns, the introduction of exotic species, and reduced breeding success threaten fish populations and ecosystem stability. The article also emphasizes the importance of adaptation and mitigation strategies, such as habitat conservation, sustainable fisheries management, marine protected areas, and emissions reduction. Understanding these multifaceted impacts is critical to developing resilient fisheries and aquaculture systems in the face of a rapidly changing climate.
Continue reading ‘Climate change and its effects on fish growth and physiology’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
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’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’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’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’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)’The development and plasticity of acid excretion mechanisms in early life stage red drum, Sciaenops ocellatus
Published 21 August 2025 Science ClosedTags: biological response, fish, laboratory, molecular biology, North Atlantic, physiology, reproduction
Highlights
- Components of acid-base pathways are present and stable in very early development.
- NHE3 is localized to the apical pit of epithelial ionocytes.
- Epithelial proton excretion is responsive to elevated CO2 and governed by NHEs.
- nhe2/3 transcript abundance is elevated following development in high CO2.
- Low level CO2 causes reductions in survival.
Abstract
Ocean acidification (OA) has been shown to affect early life stage fishes in a variety of ways, including reduced survival and growth, and increased tissue damage. Yet, there is also substantial interspecies variability in the sensitivity of early life stage fishes to high CO2, and it has been theorized that this may relate to the ontogeny of systemic acid-base regulatory pathways; an area that has been surprisingly understudied in obligate marine species. Here, we used an integrative set of approaches to describe the development and plasticity of acid excretion pathways in developing red drum (Sciaenops ocellatus), a marine fish native to the Gulf of Mexico. We observed mRNA expression of relevant transporters and ionocytes immediately post-hatch (36 h post-fertilization, hpf) with relatively stable abundance throughout the pre-metamorphic stages. Consistent with work in adults and seawater acclimated euryhaline larvae, we demonstrate strong co-localization of acid excretion proteins within a single epithelial ionocyte cell-type. Measurements of epithelial Δ[H]+, an indicator of proton efflux, showed that by 72 hpf larvae had CO2-responsive EIPA-sensitive acid excretion, confirming the presence of sodium proton exchanger (NHE)-mediated acid excretion. Elevated mRNA expression of nhe2 and nhe3 was induced following exposure to 5500 and 12,000 μatm CO2, which coincided with the absence of further survival effects relative to lower dose CO2. Overall, these data confirm that red drum have fully functional epithelial acid excretion pathways in early life, and that plasticity in these pathways may offer survival benefits.
Continue reading ‘The development and plasticity of acid excretion mechanisms in early life stage red drum, Sciaenops ocellatus’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’The influence of maternal size/age effects on the physiological responses of adult female gopher rockfish (Sebastes carnatus) to ocean acidification and hypoxia
Published 13 August 2025 Science ClosedTags: biological response, fish, laboratory, multiple factors, North Pacific, oxygen, physiology, reproduction
Climate change is rapidly reshaping the chemistry of the ocean. Fishes living in California coastal waters are experiencing increased ocean acidification and hypoxia (OAH) due to more frequent and intense upwelling. Nearshore rockfish may be particularly threatened by these conditions due to their long generational times. However, it is unknown how OAH may impact maternal physiology and reproduction in these viviparous fish. To understand the physiological effects of OAH during gestation, adult female gopher rockfish, Sebastes carnatus, were exposed to a variety of combined OAH stress treatments during different gestational stages. Routine metabolic rate (RMR), maximum metabolic rate (MMR), blood hematocrit (Hct), hemoglobin (tHb), pCO2, HCO3–, Na+, K+, Cl–, and metabolites, were measured to assess physiological responses to OAH stress. Ovarian oxygen was measured to examine the ability to buffer embryos against low oxygen. Fish exposed to higher OAH stress displayed elevated blood Hct, tHb, pCO2 and HCO3–, and decreased MMR, indicating attempted compensation for low pH and hypoxia (with varying levels of success), at increased physiological costs. Fish showed signs of buffering their ovaries against hypoxia. Lastly, pregnancy altered Hct and RMR under OAH exposure and size/age did not have a consistent effect on maternal physiology. By evaluating responses of maternal physiology to OAH stress, we can better understand how climate change affects fecundity, larval condition, and survival, influencing nearshore fisheries in an ever-changing climate.
Continue reading ‘The influence of maternal size/age effects on the physiological responses of adult female gopher rockfish (Sebastes carnatus) to ocean acidification and hypoxia’
