The regulation of gene expression by epigenetic markers is a growing area of focus for researchers who seek to explain rapid phenotypic acclimatization to environmental change. Yet even as empirical datasets accumulate exponentially, the mechanistic underpinnings of epigenetic changes and their role in connecting environmental variation with the regulation of gene function remain unclear. Here, we use a stochastic model of epigenetic change to generate three testable predictions: (1) that organisms require environmental feedback to track their environments through epigenetic responses, (2) that this tracking requires coordination between the addition and removal of epigenetic markers, and (3) that epigenetically driven tracking is only effective under specific subsets of environmental variability. Despite the intuitiveness of these postulates, few to no experimental studies directly test them. Using marine invertebrates as a case study, we review correlational evidence consistent with the model’s predictions, describe hypothetical mechanisms by which epigenetic strategies could evolve, and clearly identify knowledge gaps and urgent experimental needs in the field. Overall, the field of environmental epigenetics is poised for major advances, which can be enhanced through the continued synthesis of mathematical frameworks and empirical data.
Continue reading ‘Epigenetic intelligence: how organisms track their environment through molecular memory’Posts Tagged 'mollusks'
Epigenetic intelligence: how organisms track their environment through molecular memory
Published 13 November 2026 Science Leave a CommentTags: adaptation, biological response, corals, individualmodeling, methods, modeling, molecular biology, mollusks, morphology, otherprocess, physiology, reproduction, review, zooplankton
Pteropod preservation reveals carbonate dissolution across the Mid-Pleistocene Transition and an Eemian preservation spike in the Andaman Sea
Published 13 November 2026 Science Leave a CommentTags: abundance, chemistry, dissolution, mollusks, otherprocess, paleo, zooplankton
Highlights
- ∼1.2-Myr record reveals major changes in Andaman Sea pteropod preservation.
- Pteropods show enhanced preservation during several glacial intervals.
- Poor MIS 25–14 preservation preceded variable preservation during the MBDI (MIS 13–11).
- Highest pteropod abundances span Termination II–MIS 5e (∼137–116 ka).
- Pteropod preservation reflects large-scale carbonate-system changes modulated by regional hydrography.
Abstract
Pteropods are aragonitic holoplanktonic molluscs whose shells preserved in marine sediments provide a sensitive archive of past seawater carbonate saturation state, intermediate-water ventilation, and monsoon-driven oceanographic change. Here, we present a ∼1.2 Myr record of pteropod assemblages and preservation from sediment core NGHP-17 (1344 m water depth) in the Andaman Sea. Sixteen species were quantified across 180 samples, together with the Fragmentation Ratio (FR), Limacina Dissolution Index (LDX), epipelagic/mesopelagic (Epi/Meso) ratio, and selected planktonic and benthic foraminiferal abundances. Pteropod preservation is episodic, with pronounced preservation peaks during several glacial intervals. In contrast, generally poor and intermittent preservation during MIS 25–14 characterizes much of the Mid-Pleistocene Transition (MPT), although preservation windows occur during MIS 22, 18, and 16. This pre-MBDI decline was followed by the Mid-Brunhes Dissolution Interval (MBDI; MIS 13–11), within which a pronounced MIS 12 preservation peak demonstrates that unfavorable conditions were not continuous. An earlier preservation event occurs during MIS 26. The highest pteropod abundance is observed across MIS 6–5e, with a maximum at ∼125 ka and species maxima spanning ∼137–116 ka, indicating a transient Termination II/deglacial-to-early-interglacial preservation event. The significant inverse relationship between total pteropod abundance and FR supports a substantial preservation control on the record. Overall, the results indicate that pteropod preservation at NGHP-17 was strongly influenced by changes in bottom-water aragonite preservation conditions, within a broader framework of large-scale carbonate-system changes and regional hydrographic variability.
Continue reading ‘Pteropod preservation reveals carbonate dissolution across the Mid-Pleistocene Transition and an Eemian preservation spike in the Andaman Sea’Ocean acidification impairs embryonic development and disrupts ink sac gene expression in the pharaoh cuttlefish (Sepia pharaonis)
Published 12 November 2026 Science Leave a CommentTags: biological response, laboratory, molecular biology, mollusks, morphology, mortality, North Pacific, physiology, reproduction
Background: Ocean acidification (OA) represents a growing threat to marine biodiversity, particularly affecting the sensitive early life stages of invertebrates. While the physiological impacts of OA are widely recognized, its specific effects on organogenesis and the molecular regulation of defensive traits in cephalopods remain poorly understood. This study investigated the influence of acidified seawater on the embryonic development and ink sac formation in the Pharaoh cuttlefish (Sepia pharaonis).
Methods: Embryos were reared under four pH conditions (8.0, 7.7, 7.3, and 6.5). Embryonic growth, survival, hatching success, and ink sac morphogenesis were monitored throughout development. The expression of melanin synthesis–related genes, including tyr, per, and spNOS, was quantified using qRT-PCR.
Results: Ocean acidification impaired embryonic development in a pH-dependent manner. Severe acidification (pH 6.5) resulted in complete mortality and no surviving embryos by Day 9, while moderate acidification (pH 7.3) led to delayed development and failure to hatch by Day 11, compared to the hatching observed in the control group. Ink sac development was markedly inhibited under acidified conditions, resulting in reduced size and pigmentation. Consistent with these morphological abnormalities, the expression of melanin synthesis markers, including tyrosinase (tyr) and peroxidase (per), exhibited a biphasic response, with early transient induction followed by consistent downregulation across all acidified treatments, while, the expression of the regulatory gene Sepia pharaonis nitric oxide synthase (spNOS) was significantly suppressed under severe acidification.
Conclusions: These findings provide evidence that OA is associated with disrupted embryogenesis and impaired ink sac formation in S. pharaonis, accompanied by altered expression of melanin synthesis-related genes. The resulting reduction in defensive capacity may increase the vulnerability of hatchlings and potentially affect population recruitment under future ocean acidification scenarios.
Continue reading ‘Ocean acidification impairs embryonic development and disrupts ink sac gene expression in the pharaoh cuttlefish (Sepia pharaonis)’Microhabitat-driven variation in predator–prey interactions between the crab Acanthocyclus hassleri and the mussel Perumytilus purpuratus
Published 12 November 2026 Science Leave a CommentTags: biological response, BRcommunity, crustaceans, field, mollusks, morphology, multiple factors, performance, predation, salinity, South Pacific, temperature
Highlights
- Microhabitat variability modulates predator–prey interactions in rocky intertidal systems.
- Tide pool mussels experience recurrent hyposalinity and low pH conditions.
- Reduced shell resistance increases predation vulnerability in tide pool mussels.
- Fine-scale coastal heterogeneity drives trait-mediated trophic interactions.
Abstract
This study evaluates how the microhabitat of origin of the mussel Perumytilus purpuratus is associated with its vulnerability to predation by the crab Acanthocyclus hassleri. A comparison was made of individuals of P. purpuratus from three intertidal microhabitats: higher limit, lower limit, and tide pool (HL, LL, TP, respectively). The latter receives freshwater inputs associated with an adjacent stream and rainfall. Three environmental variables (salinity, temperature, and pH) and prey shell-breaking strength were measured, and predation experiments using single-prey and mixed-prey diets were also conducted. These experiments evaluated attack rate, handling time, attack zone, size of prey consumed, and crushing claw force. The results indicate that TP experience more extreme conditions, with lower salinity and pH during low tide compared with the other microhabitats (HL and LL). These conditions were associated with lower shell-breaking strength, which may reduce prey resistance to predator attacks. While attack rate remained similar across different diets, under a mixed diet, the predator A. hassleri showed greater consumption of mussels from TP. Tide pool prey also tended to require less handling time than prey from the other microhabitats. The anterior region of the prey shell (umbo area) was the most frequently attacked, regardless of the microhabitat. Smaller individuals from LL were more frequently consumed, whereas larger prey sizes were targeted in HL and TP. A. hassleri possesses the strength necessary to attack prey from all three microhabitats. Overall, these findings suggest that microhabitat-associated differences in shell characteristics may influence prey vulnerability to predation and shape prey selection by A. hassleri.
Continue reading ‘Microhabitat-driven variation in predator–prey interactions between the crab Acanthocyclus hassleri and the mussel Perumytilus purpuratus’Ocean acidification impairs the chiton shadow defensive response via degradation of aragonitic lenses
Published 9 November 2026 Science Leave a CommentTags: biological response, dissolution, laboratory, mollusks, morphology, North Pacific, performance, physiology
Ocean acidification (OA) has the potential to disrupt the behavior of marine organisms by altering the function of γ-aminobutyric acid type A (GABAA) receptors. In addition, OA can impair sensory performance by reducing the calcification of mineralized sensory structures. Some species of polyplacophoran mollusks (chitons) possess calcified visual organs (aragonitic lenses) that contribute to shadow defense responses triggered by sudden decreases in overhead illumination. Therefore, we hypothesized that OA affects this response by impairing GABAA-mediated signaling or lens calcification. To test this hypothesis, we exposed chitons to “control” or acidified seawater and examined their shadow defensive behavior with and without gabazine, a GABAA antagonist known to restore OA-induced GABAergic dysfunction. Although gabazine did not eliminate behavioral differences between the control and acidified groups, acidification reduced the response strength, suggesting that factors other than GABAA-mediated signaling may contribute to the observed behavioral impairment. Microscopic observations revealed clouding of aragonitic lenses under acidic conditions, suggesting reduced optical performance. Overall, our results indicate that OA-induced degradation of calcified lens structures is associated with impaired shadow defense responses and may contribute to behavioral dysfunction. To the best of our knowledge, this study provides the first evidence that acidification-induced physical and optical changes in the visual anatomy can alter behavioral performance in animals.
Continue reading ‘Ocean acidification impairs the chiton shadow defensive response via degradation of aragonitic lenses’A microRNA catalogue for red abalone larvae reveals developmental and acidification-associated abundance patterns
Published 6 November 2026 Science Leave a CommentTags: biological response, laboratory, molecular biology, mollusks, North Pacific, physiology, reproduction, respiration
Larval development in marine mollusks requires coordinated gene regulation and is particularly sensitive to ocean acidification, yet post-transcriptional regulation remains poorly characterized in non-model gastropods. We characterized the microRNA (miRNA) repertoire and respiratory response of red abalone (Haliotis rufescens) larvae reared at pH 8.0 and 7.6. Small-RNA sequencing was performed at the trochophore (24 h post-fertilization, hpf) and competent veliger (110 hpf) stages, with three biological replicates per stage and pH treatment, while oxygen consumption was measured at 24, 48, 60, and 110 hpf. Genome-anchored annotation identified 147 precursor loci encoding 117 distinct mature miRNA sequences, including 70 matching reference databases and 47 candidate novel miRNAs. The developmental stage was the predominant source of variation in miRNA abundance, with the first principal component explaining 87.3% of the variation, whereas acidification affected a comparatively small subset of miRNAs. Cumulative oxygen consumption from 24 to 110 hpf was 57% higher at pH 7.6 than at pH 8.0. Both intergenic and intragenic miRNAs contributed to the acidification-associated response, with no significant preferential representation of either genomic-origin class. Computational predictions link pH-responsive miRNAs to genes associated with aerobic metabolism, morphogenesis, biomineralization, chromatin regulation, and stress responses. Because these miRNA–target relationships are computational predictions and the physiological and molecular measurements were not biologically paired, they do not establish a direct regulatory relationship. These results provide the first larval miRNA catalogue for H. rufescens and identify developmental- and acidification-associated miRNA abundance patterns and candidate miRNA–target relationships for future functional validation.
Continue reading ‘A microRNA catalogue for red abalone larvae reveals developmental and acidification-associated abundance patterns’Limited post-stress recovery and constrained physiological resilience: multi-biomarker evidence for metabolic trade-offs in a gastropod under ocean acidification
Published 6 November 2026 Science Leave a CommentTags: biological response, laboratory, molecular biology, mollusks, North Pacific, physiology
Highlights
- OA induces severe apoptosis of hepatopancreas cells in Brunneifusus ternatanus.
- IBR index indicates partial but incomplete physiological restoration after recovery.
- Transcriptomics reveals energy downregulation and immunity activation under OA stress.
Abstract
Ocean acidification (OA), driven by increasing atmospheric CO2 absorption, represents a critical environmental stressor that disrupts hepatopancreas function in aquatic organisms, particularly affecting metabolic homeostasis and immune competence. This study employed an integrated multi-biomarker approach combining histopathology, integrated biomarker response (IBR) indices, and transcriptomics to systematically investigate the effects of short-term (14 d), medium-term (28 d) CO2-driven acidification exposure and a subsequent recovery period on the whelk Brunneifusus ternatanus. Hepatopancreatic cells suffered progressive structural and functional damage during 14–28 d of acidification, characterized by reduced hemocyte counts, disruption of rough endoplasmic reticulum membranes, and obscured cell boundaries. During recovery, damage was attenuated yet persistent, manifesting as intracellular matrix edema, hemocyte rebound, and restored membrane integrity—but cell boundaries remained altered relative to controls. The IBR index (integrating oxidative stress markers and hepatopancreas function enzyme indices) increased continuously during early and medium exposure, then decreased significantly during recovery yet remained elevated above control levels, indicating partial but incomplete physiological restoration. Transcriptomic analysis revealed time-specific molecular reprogramming: energy metabolism and mitochondrial function pathways were downregulated during early acidification and recovery stages, whereas medium-term exposure significantly activated immunity- and metabolism-associated pathways. These findings demonstrate that B. ternatanus mounts vigorous physiological regulatory responses to OA stress at a demonstrable energetic cost, characterized by immune-metabolic trade-offs and sustained metabolic reprogramming even after stress removal. This study provides evidence for assessing OA impacts on gastropod mollusks and contributes to predictive frameworks for evaluating marine ecosystem vulnerability under climate change.
Continue reading ‘Limited post-stress recovery and constrained physiological resilience: multi-biomarker evidence for metabolic trade-offs in a gastropod under ocean acidification’Drivers of biogenic acidification in oyster cultivation waters: macroalgal photosynthesis raises pH and carbonate saturation state, but not total alkalinity
Published 6 November 2026 Science Leave a CommentTags: algae, biological response, calcification, chemistry, fisheries, laboratory, mitigation, mollusks, photosynthesis, physiology
Highlights
- Oyster respiration and calcification jointly deplete seawater alkalinity and buffering capacity.
- High stocking density and low water exchange intensify biogenic acidification.
- Biogenic acidification reduces short-term CO2 excretion and calcification rates in oysters.
- Macroalgal photosynthesis raises pH and Ωcal but not the total alkalinity consumed by calcification.
Abstract
Biogenic acidification is a growing concern in large-scale bivalve aquaculture. To investigate its drivers and mitigation strategies, oysters were incubated in a continuous flow-through system with five chambers in series to simulate upstream-to-downstream water flow in a large-scale long-line oyster aquaculture system. Four stocking densities (1, 3, 6, and 9 ind. Chamber−1) and three water exchange rates (3.6, 5.4, and 7.2 L h−1) were tested. The mitigation potential of macroalgal photosynthesis was then evaluated. Results showed that biogenic acidification was observed in experimental waters and higher oyster stocking density intensified seawater acidification, with downstream chambers exhibiting more pronounced acidification than upstream chambers. Compared with the blank control, the terminal chamber at the highest density showed a pH decrease of 0.85 units, a pCO2 increase of 2698 μatm, and decreases in total alkalinity (TA) and TA DIC of 333 and 349 μmol kg−1, respectively. Lower water exchange rate also exacerbated biogenic acidification. In the terminal chamber at the lowest water exchange rate, pH decreased by 0.52 units, pCO2 increased by 976 μatm, and TA and TA DIC decreased by 140 and 188 μmol kg−1, respectively. Negative effects were observed: correlation analysis revealed a significant negative correlation between seawater pCO2 and the weight-specific CO2 excretion rate (P < 0.05), alongside a significant positive correlation between Ωcal and the weight-specific calcification rate (P < 0.05). Adding Ulva Lactuca L. to the acidified seawater progressively raised pH (7.75 to 8.06) and Ωcal (2.3 to 4.3) and lowered pCO2 (1306 to 585 μatm) over five days, approaching ambient levels, whereas TA remained at its post-acidification level despite a DIC drawdown of 133 μmol kg−1. CO2 removal therefore raises the pH and saturation -state caused by biogenic acidification but not the TA deficit, indicating that TA must be included when the mitigating effect of macroalgal photosynthesis is evaluated and that supplementary alkalinity sources may be required in large-scale bivalve aquaculture.
Continue reading ‘Drivers of biogenic acidification in oyster cultivation waters: macroalgal photosynthesis raises pH and carbonate saturation state, but not total alkalinity’Climate-driven reproductive dysfunction in cultured fish and shellfish: endocrine mechanisms, consequences and adaptive strategies
Published 4 November 2026 Science Leave a CommentTags: biological response, fish, fisheries, mollusks, reproduction, review
Climate change is altering the environmental conditions experienced by aquatic organisms through rising temperatures, marine heatwaves, hypoxia, salinity fluctuations, ocean acidification and more frequent extreme events. Although the effects of climate change on growth, survival and disease have received considerable attention, reproductive impairment may occur before substantial mortality and can directly threaten aquaculture seed production. Reproduction depends on the coordinated interaction of environmental cues, neuroendocrine pathways, gonadal function, gametogenesis and energy allocation, making it particularly sensitive to environmental instability. In fish, climate-related changes can affect the brain–pituitary–gonad axis, steroidogenesis, sex differentiation, gametogenesis, gamete quality and spawning. Temperature is especially important because it influences endocrine regulation throughout reproductive development, while hypoxia, salinity changes and ocean acidification can further modify endocrine, metabolic and cellular processes. In shellfish, environmental stress can affect gonadal development, gametogenesis, spawning, fertilisation and larval performance through mechanisms that differ from those operating in vertebrate fishes. Multiple climate-related stressors may also act simultaneously, producing additive, synergistic or antagonistic effects. Parental exposure can further influence offspring through maternal provisioning, paternal effects and epigenetic mechanisms. These processes have direct implications for broodstock conditioning, hatchery seed production and the sustainability of aquaculture. This review examines the links between climate-related environmental change, reproductive endocrine regulation and reproductive performance in cultured fish and shellfish, with emphasis on gamete quality, spawning, early development, multiple-stressor interactions and reproductive resilience. Environmental management, broodstock selection, nutrition, acclimation, selective breeding, biomarker-based monitoring and climate-resilient hatchery technologies are considered potential approaches for sustaining reproductive performance under future environmental conditions.
Continue reading ‘Climate-driven reproductive dysfunction in cultured fish and shellfish: endocrine mechanisms, consequences and adaptive strategies’Oxidative stress as a potential mechanistic link between climate change and aquatic biodiversity loss
Published 4 November 2026 Science Leave a CommentTags: abundance, adaptation, algae, biological response, calcification, community composition, corals, echinoderms, fish, light, mollusks, mortality, multiple factors, nutrients, otherprocess, oxygen, performance, photosynthesis, physiology, phytoplankton, plastics, protists, reproduction, review, temperature, zooplankton
Climate change is rapidly altering aquatic ecosystems through rising temperatures, ocean acidification, hypoxia, ultraviolet radiation, salinity fluctuations, and interacting environmental stressors. These changes impose substantial physiological challenges on aquatic organisms, with oxidative stress representing an important mechanistic pathway linking environmental disturbances to biological responses across multiple levels of organization. This review synthesizes current evidence on oxidative stress responses associated with climate change-related environmental stressors across aquatic taxa, including fish, aquatic invertebrates, corals, phytoplankton, macroalgae, amphibians, and polar and deep-sea organisms. We examine the mechanisms underlying reactive oxygen species production, disruption of antioxidant defenses, and oxidative damage, while critically evaluating biochemical, molecular, and omics-based biomarkers for environmental stress assessment. Particular emphasis is placed on how oxidative stress may translate from cellular and organismal responses into changes in growth, reproduction, behavior, survival, species distributions, population dynamics, community structure, biodiversity, and ecosystem resilience. We also highlight limitations of current biomarker approaches, including species-specific variability, methodological inconsistencies, and difficulties in extrapolating laboratory findings to natural ecosystems. Future research should prioritize integrated multi-biomarker and multi-stressor approaches, long-term ecological monitoring, standardized protocols, and the integration of omics, environmental DNA, remote sensing, and artificial intelligence. Overall, oxidative stress biomarkers provide complementary tools for assessing climate-change impacts on aquatic biodiversity and ecosystem resilience.
Continue reading ‘Oxidative stress as a potential mechanistic link between climate change and aquatic biodiversity loss’Time-variant bioeconomic risks on a gastropod fishery affected by uncertain ocean acidification trajectories
Published 3 November 2026 Science Leave a CommentTags: abundance, biological response, chemistry, field, fisheries, growth, modeling, mollusks, mortality, North Pacific, otherprocess, regionalmodeling, socio-economy
Introduction: In the north-eastern Pacific, high-value abalone fisheries, which are sensitive to pH variations, require in situ pH data to properly assess the bioeconomic effects of their possible dynamic trajectories under alternative fishing mortalities.
Methods: In situ pH data were collected every 15 min using a HOBO® MX2501 sensor in the La Bocana pink abalone fishing grounds and compared them with Argo float and Copernicus Marine Service observations. The observed pH distribution was fitted to the Extreme Value Minimum distribution based on the Anderson–Darling goodness-of-fit statistic. Stochastic pH trajectories were generated through 10,000 Monte Carlo replications under three IPCC ocean acidification scenarios (SSP1-2.6, SSP2-4.5, and SSP5-8.5) and three fishing mortalities (FD = 0.02, 0.04, and 0.06). These trajectories were incorporated into a dynamic age-structured bioeconomic model by making individual growth and age-specific natural mortality functions dependent on pH. Biomass and resource rent per boat were projected from 2025 to 2100, and linear mixed-effects models, sensitivity analyses, and 95% confidence intervals were used to evaluate temporal responses and parameter uncertainty. Dynamic risks were estimated as the probability that biomass and resource rent fell below their respective limit reference points (LRPs: 190 t and USD 15,000 yr-1) across scenarios and fishing mortalities.
Results: The results indicate considerable variability in pH measurements between remote and in situ sources, which may introduce a proportional bias into the bioeconomic modeling if local observations are absent. Also, the effects of ocean acidification on H. corrugata biomass, survival, and fishery resource rent increase with time, IPCC pH scenario, and alternative exploitation intensity. Under the current exploitation rate (FMSY = 0.06), effects were negligible in the short term under SSP1-2.6, whereas by 2100 pH-related growth effects decreased by 4%, 13%, and 26% under SSP1-2.6, SSP2-4.5, and SSP5-8.5, respectively. Over the same period, pH effects on survival rates resulted in a slight increase of 2.14% under SSP1-2.6, but reductions of 6.48% and 22% under SSP2-4.5 and SSP5-8.5, respectively, while age-specific biomass peaks declined by up to 20% and 44% under SSP2-4.5 and SSP5-8.5. Mixed-effects models confirmed significant effects of pH scenario, exploitation rate, and time on biomass and resource rent, including significant interactions (all p < 0.001). By 2100, annual resource rent per small-scale boat was significantly higher under SSP1-2.6 than under SSP2-4.5 and SSP5-8.5 by USD 3,083 and USD 7,482, respectively (p < 0.0001). Under FMSY, the risk of biomass falling below its LRP was <25% during 2025–2040 but increased to 34% and 54% under SSP2-4.5 and SSP5-8.5, respectively, by 2100; corresponding risks for resource rent increased to 27% and 48%.
Discussion: These results indicate that ocean acidification may substantially increase the long-term bioeconomic vulnerability of the fishery, particularly under high-emission scenarios. Management actions to mitigate the undesired bioeconomic effects of OA will likely depend on the fishery authority’s risk attitude (i.e., degree of risk aversion) and corresponding exploitation-rate strategy selection.
Continue reading ‘Time-variant bioeconomic risks on a gastropod fishery affected by uncertain ocean acidification trajectories’Spat origin does not affect phenotypic plasticity in the farmed mussel Mytilus chilensis facing experimental acidification
Published 2 November 2026 Science Leave a CommentTags: biological response, calcification, fisheries, mesocosms, mollusks, morphology, multiple factors, origin, physiology, South Pacific
Phenotypic plasticity allows organisms to cope with environmental variability, yet its role in sustaining aquaculture systems in the face of global change stressors remains poorly understood. We conducted a 90-day mesocosm experiment to test whether spat origin influences morphological, physiological, and periostracum responses in the Chilean mussel Mytilus chilensis under sustained experimental acidified conditions. Juveniles were collected from two contrasting habitats: an estuarine and dynamic/fluctuating environment, strongly influenced by freshwater discharges, and a marine, more stable environment; and then exposed to two pH regimes (8.0 and 7.5). Morphological traits showed subtle origin effects: estuarine mussels tended to exhibit higher shell length and calcification rates, though origin × pH interactions were not significant. Physiological responses were largely similar between both seed sources, with metabolic rates remaining stable while the clearance rate increased under acidified conditions in both populations. Periostracum analyses revealed some non-significant variation in organic composition, but no consistent effects of the pH were detected. Together, these results suggest that M. chilensis relies on conservative metabolic maintenance combined with flexible clearance responses possibly to cope with natural acidification pulses, while also tolerating sustained low-pH conditions, with only weak signals of origin-driven divergence. Our findings highlight the importance of phenotypic adjustments over local origin, suggesting that spat provenance may not be a primary determinant of performance under projected acidification scenarios tested here.
Continue reading ‘Spat origin does not affect phenotypic plasticity in the farmed mussel Mytilus chilensis facing experimental acidification’Tolerance measured at one developmental stage mispredicts climate resilience in an animal with a complex life cycle
Published 2 November 2026 Science Leave a CommentTags: adaptation, biological response, dissolution, growth, laboratory, mollusks, morphology, mortality, North Atlantic, otherprocess, physiology, reproduction
Forecasts of whether marine species can evolve fast enough to survive climate change rely largely on single-stage tolerance assays, tacitly assuming that tolerance measured at one developmental stage reflects adaptive capacity across the organism’s life cycle. We test this assumption in a common marine bivalve (Mercenaria mercenaria) and find that it fails in sign, not degree: larval and post-metamorphic tolerance to end-century ocean acidification are strongly negatively correlated (r = −0.53, 95% CI [−0.69, −0.33]) across family-level, pedigree-conditioned and animal model estimates, with pervasive rank reversals among the top performers of each stage. A multivariate analysis of the among-family covariance matrix G shows why: under acidification, 57% of the among-family variance collapses onto a single dominant axis that loads positively on every larval trait and negatively on every post-metamorphic trait, whereas under ambient conditions the same families show no cross-stage covariance at all. Acidification therefore does not merely depress performance—it reorganizes the genetic architecture into a cross-stage conflict. Under ramping RCP 8.5 forcing this conflict geometry dictates the direction—not merely the magnitude—of adaptation: only balanced multi-stage selection preserves family diversity, whereas single-stage selection systematically erodes the opposite axis. In complex life cycles, resilience is a geometric property of ontogeny that forecasts cannot compress into a single-stage without inverting the sign of the answer.
Continue reading ‘Tolerance measured at one developmental stage mispredicts climate resilience in an animal with a complex life cycle’Closer to danger: southern Ocean pteropods build their shells deeper in the water column during winter-spring
Published 29 October 2026 Science ClosedTags: Antarctic, biological response, chemistry, mollusks, morphology, zooplankton
Shelled pteropods are at risk from ocean acidification, with known effects on their shell durability and calcification. Pteropods typically form their aragonitic shells over specific depth ranges known as the “calcification depth,” which varies depending on species and habitats. Some Southern Ocean waters are already undersaturated with respect to aragonite and this could negatively affect shelled pteropods. However, the calcification depths of pteropods have not been determined nor used to infer consequences of changing seawater carbonate chemistry in the Southern Ocean. In this study, we analyzed the stable oxygen isotopic composition of Limacina rangii shells, collected by sediment traps in the sub-Antarctic zone, to estimate their calcification depth. Shallow calcification depths (13–126 m) were detected in summer–autumn, while L. rangii calcified their shells deeper in the water column during winter–spring (302–525 m). Recent shoaling of the aragonite saturation horizon is likely to negatively affect pteropods that calcify their shells in deep water. Such shoaling could affect pteropod calcification, shell integrity and threaten population viability.
Continue reading ‘Closer to danger: southern Ocean pteropods build their shells deeper in the water column during winter-spring’Interactive effects of ocean acidification and benzophenone-3 on mussel physiology: a biomarker-based approach
Published 27 October 2026 Science ClosedTags: biological response, laboratory, mollusks, multiple factors, physiology, toxicants
Highlights
- Ocean acidification was the primary driver of biomarker responses.
- Low pH enhanced BP3-induced cytotoxicity in hemocytes.
- BP3 detoxification mainly involved the GST/GSH pathway.
- Lipid peroxidation occurred in gills and digestive gland despite antioxidant response.
- Acidification impacts biomineralization enzymes more strongly than BP3.
Abstract
Benzophenone-3 (BP3), a widely used ultraviolet (UV) filter in personal care products and industrial applications, is an emerging concern in aquatic ecosystems due to its lipophilicity, bioaccumulation potential, and toxicity to marine biota. Its occurrence in marine environments coincides with ocean acidification driven by rising atmospheric CO2 emissions, which disrupts the bicarbonate buffer system and reduces pH. This study investigated the acute effects (96 h exposure) of BP3 (at realistic concentrations of 0.2 and 2 μg/L) under 3 pH conditions (8.1- the current South Atlantic condition- and 7.6 and 7.3 as projected acidification scenarios for 2100 and 2300, respectively) in the brown mussel Perna perna. The effects were investigated through analysis of hemocyte viability and biomarkers related to detoxification (glutathione S-transferase, glutathione, glutamate cysteine ligase, and reduced glutathione), oxidative stress (antioxidant capacity against peroxyl radicals and lipid peroxidation), and biomineralization (carbonic anhydrase and Ca2+ATPase), measured in the gills, digestive gland, and mantle. Despite BP3-induced activation of glutathione-related detoxification pathways, as evidenced by increased GSH levels and GST activity, particularly in the gills, hemocyte viability decreased after BP3 exposure, with the greatest reduction at pH 7.3. Lipid peroxidation (LPO) also increased in the gills and digestive gland under acidified conditions, with the magnitude of the response varying according to BP3 concentration. CA and Ca2+ATPase activities were more strongly influenced by acidification than by BP3 exposure, although their responses were tissue-specific and, in some cases, modulated by BP3 exposure. Multivariate analyses identified pH as the primary driver of biomarker responses.
Graphical abstract
Physiological responses of Atlantic surfclams (Spisula solidissima) to moderate ocean acidification across thermal regimes
Published 23 October 2026 Science ClosedTags: biological response, chemistry, fisheries, growth, laboratory, mollusks, morphology, multiple factors, North Atlantic, performance, physiology, respiration, temperature
Highlights
- Interactive effects of warming and acidification tested in surfclams.
- Growth, feeding, and metabolic rates measured after 6-week exposure.
- Moderate acidification had limited effects under warming conditions.
- Surfclams showed resilience to near-future ocean acidification.
- Multi-stressor design improves ecological relevance of lab studies.
Abstract
Understanding marine organismal responses to co-occurring climate stressors is critical for predicting changes in ecosystems and commercial fisheries. The Atlantic surfclam supports a major commercial fishery in the Northeastern United States, where ocean warming and acidification are rapidly altering marine habitats. To evaluate how changing ocean conditions may affect bivalve physiology, surfclams were exposed to conditions reflective of ocean warming and acidification, respectively. One-year-old surfclams were exposed to nine conditions in a fully crossed design of temperature (ambient, +2 °C, and + 5 °C) and pH (7.88 ± 0.05, 7.76 ± 0.05, and 7.51 ± 0.07) for six weeks in a flow-through laboratory experiment using natural seawater. We quantified several physiological responses including growth, feeding, digestion, respiration rates, and shell weight and thickness to assess organismal performance across treatments.
Surfclams generally exhibited resistance to moderate ocean acidification across warming, but non-thermally stressful, temperatures. No effects of ocean acidification were observed on surfclam growth or respiration, although other physiological metrics (shell thickness and absorption rate) decreased with decreasing pH at some temperatures. These findings provide experimentally-derived insight into species-specific responses to interacting climate stressors. Further, the experimental design highlights the importance of integrating natural environmental variability into laboratory studies and studying multiple environmental stressors concurrently. This study contributes a basis for refining models of surfclam growth and distribution in potential future climate scenarios, with implications for sustainable fisheries management.
Continue reading ‘Physiological responses of Atlantic surfclams (Spisula solidissima) to moderate ocean acidification across thermal regimes’Ocean warming and acidification reveal transcriptional plasticity in the gastropod Hexaplex trunculus
Published 23 October 2026 Science ClosedTags: biological response, molecular biology, mollusks, multiple factors, performance, physiology, respiration, temperature
Coastal ecosystems, particularly in the rapidly warming Mediterranean Sea, are increasingly impacted by climate change driven by ocean warming and acidification. Calcifying marine invertebrates are especially vulnerable, yet their molecular responses remain poorly understood. Gene expression dynamics in the ecologically and commercially important gastropod Hexaplex trunculus were investigated under simulated scenarios combining elevated temperature and reduced pH. High-throughput RNA sequencing was used to generate a de novo assembly of the foot transcriptome, followed by differential gene expression analyses to characterize molecular responses to individual and interactive stressors under high-emission (RCP 8.5) projections. The foot tissue – central to locomotion, adhesion, and environmental interaction – exhibited pronounced transcriptional changes in genes associated with calcium signaling, ion transport, aerobic respiration, muscle contraction, and transmembrane transport. Ocean acidification emerged as the dominant driver of transcriptional change, inducing substantial shifts in metabolic demand and ion regulatory pathways, which might suggest increased energetic costs and potential functional constraints. The results demonstrate marked transcriptional plasticity in H. trunculus under combined climate stressors. By providing foundational transcriptomic resources for this species and mechanistic insight into its response to projected environmental changes, this study advances the understanding of molecular processes in vulnerable Mediterranean gastropods and informs ecological assessment efforts in rapidly warming marine ecosystems.
Continue reading ‘Ocean warming and acidification reveal transcriptional plasticity in the gastropod Hexaplex trunculus’Present but overlooked: biogenic acidification in aquaculture waters and its implication for mollusc mariculture
Published 21 October 2026 Science ClosedTags: biological response, calcification, chemistry, fisheries, mitigation, mollusks, morphology, physiology, review
Mollusc mariculture, a critical global source of high-quality protein, is increasingly threatened by seawater acidification. While climate-driven ocean acidification (OA) has been widely studied, intensive aquaculture systems face an additional, locally exacerbated phenomenon: biogenic acidification. In this review, we comprehensively compare biogenic acidification with OA and other seawater acidification types, highlighting its occurrence across various aquaculture systems and its capacity to induce conditions more corrosive than end-of-century OA projections under densely stocked settings. Driven by the respiration and calcification of high-density mollusc populations, biogenic acidification leads to distinct alterations in the carbonate chemistry of mollusc farming systems—notably a reduction in total alkalinity (TA)—that are mechanistically different from OA. We further discuss how biogenic acidification imposes stronger physiological stresses on molluscs, impairing calcification, growth, and energy allocation, and how it synergistically interacts with climate change. Finally, we propose practical mitigation strategies, including TA supplementation and integrated multi-trophic aquaculture, to enhance the resilience and sustainability of mollusc farming. This review underscores the necessity to address biogenic acidification as a distinct and ongoing challenge in global mariculture.
Continue reading ‘Present but overlooked: biogenic acidification in aquaculture waters and its implication for mollusc mariculture’Gravity-driven feeding currents in veliger larvae of the eastern oyster
Published 16 October 2026 Science ClosedTags: biological response, individualmodeling, modeling, mollusks, reproduction
Feeding by marine invertebrate larvae depends critically on the low-Reynolds-number fluid mechanics of the feeding currents they generate. Yet the relative importance of gravity-driven versus drag-driven mechanisms in small invertebrate larvae has remained unresolved. Here, high-speed microscale imaging, micro-particle image velocimetry (μPIV), and an analytical axisymmetric Stokes-flow model are combined to quantify the feeding currents of free-swimming veliger larvae of the eastern oyster Crassostrea virginica. Despite their small body size (<330µm), the larvae possess a high excess density (∼181g/m3), shifting the force balance such that gravity-driven feeding currents dominate. μPIV measurements reveal flow fields with first-order (Stokeslet-type) spatial decay, yielding ecologically sufficient body-volume-specific maximal clearance rates of ∼2.5×106/day. These values agree with predictions from the Stokes-flow model, which decomposes the clearance into gravity-driven and drag-driven components and shows that the former consistently outweighs the latter across observed swimming speeds. The model further explains how slow swimming modulates clearance by ±44% relative to hovering. Together, these results demonstrate that C. virginica veligers operate in a gravity-dominated feeding regime similar to that of larger calanoid copepods, and that their feeding strategy is shaped by an interplay of excess weight, swimming kinematics, and ciliary propulsion. This work highlights the fundamental role of gravity in larval feeding mechanics and underscores the need to incorporate excess weight when evaluating form-and-function relationships in marine invertebrate larvae, particularly for shelled bivalve and gastropod larvae with high excess density.
Continue reading ‘Gravity-driven feeding currents in veliger larvae of the eastern oyster’
