Posts Tagged 'mollusks'

Physiological responses of Atlantic surfclams (Spisula solidissima) to moderate ocean acidification across thermal regimes

Published 23 October 2026 Science Leave a Comment
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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.

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Ocean warming and acidification reveal transcriptional plasticity in the gastropod Hexaplex trunculus

Published 23 October 2026 Science Leave a Comment
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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.

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Present but overlooked: biogenic acidification in aquaculture waters and its implication for mollusc mariculture

Published 21 October 2026 Science Leave a Comment
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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.

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Gravity-driven feeding currents in veliger larvae of the eastern oyster

Published 16 October 2026 Science Leave a Comment
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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.

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Bioturbation under stress: linking coastal environmental change to the physiology and function of marine bioturbators

Published 13 October 2026 Science Leave a Comment
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Coastal benthic habitats are increasingly exposed to human-driven environmental changes, resulting in multiple co-occurring stressors. Bioturbators, which provide vital ecosystem services, are particularly vulnerable due to their limited mobility and are directly exposed to these multiple stressors. However, the ecological impacts of these stressors on bioturbators, especially their activity levels, remain poorly understood. This review synthesizes current knowledge on how selected environmental stressors, including extreme weather events, eutrophication, and anthropogenic emissions, affect bioturbation, organismal physiology and survival. Reported impacts vary widely depending on the species and stressors’ intensity. The strongest negative effects were typically observed under high-intensity stressor scenarios, which sometimes exceeded environmentally relevant thresholds. However, only a few studies examined the combined effects of multiple stressors. Their effects on bioturbators can be neutral, antagonistic, synergistic or additive, highlighting the complexity of stressor interactions in natural systems. The summary of this review suggests that key ecosystem functions provided by bioturbators are threatened by constant exposure to multiple environmental stressors and that ongoing environmental changes are further exacerbating this situation. To better understand the risks faced by these organisms, it is important to explore the combined effects of multiple stressors, to support more accurate predictions and effective conservation and restoration efforts.

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Ocean warming and acidification alter larval development and swimming behavior in the Atlantic sea scallop, Placopecten magellanicus

Published 13 October 2026 Science Leave a Comment
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Ocean warming (OW) and ocean acidification (OA) are expected to have wide-ranging consequences for populations in marine systems caused by organism-level responses at a range of life history stages, including early larval stages. The Atlantic sea scallop, Placopecten magellanicus, is an economically important bivalve species that may be vulnerable to ocean change, but larval responses remain unclear. While the effects of OW and OA are known to impact adult sea scallops, little is known about the interactive effects of these two factors on early life stages. Larval dispersal is key to population-level patterns (e.g. abundance and distribution), but is contingent on growth rates and vertical swimming behaviors, which are both influenced by environmental conditions. Here, we evaluate the combined effects of OW and OA on larval development and behavior in a factorial lab experiment. We maintained larval sea scallop cultures up to metamorphosis under a range of physico-chemical conditions (17℃ and 14℃, and pH 7.3, 7.6, 7.9). Sea scallop larval development time was temperature dependent (1 vs. 1.5 months). There was an interactive effect of OW and OA on growth, where OA limited gains in growth experienced in warmer conditions. OA limited a decline in distribution late in development, while OW dominated individual vertical swimming behavior in intermediate development. Finally, ΩAr growth sensitivity was intermediate compared to that of other bivalve taxa. These results contribute to an improved understanding of developmental and behavioral responses to OW and OA, and provide information necessary for improved larval dispersal models under ocean change.

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Differential gene expression reveals molecular mechanisms for physiological resilience to ocean acidification stress in native and introduced oyster species

Published 9 October 2026 Science Closed
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Coastal-estuarine habitats are rapidly changing with respect to ocean acidification (OA). Along the West Coast of the United States, coastal upwelling regions are high in productivity and rich in nutrients, making them key areas for aquaculture oyster production. The native Olympia oyster Ostrea lurida has experienced population collapse due increased commercial harvest, habitat loss, and the introduction of the non-native Pacific oyster Magallana gigas. Despite intense focus on physiological responses of oysters to OA stress, molecular underpinnings of have yet to be fully described, particularly in niche species. Juvenile oysters of both M. gigas and O. lurida were exposed to a range of experimental OA conditions for six weeks to investigate transcriptomic and biomineralization responses under fluctuating and chronic low pH. Low pH had a significant effect on shell dissolution for both Pacific and Olympia oysters, with no statistical difference observed between the two species. Differential gene expression revealed distinct differences in responses of the Pacific and Olympia oysters to OA on the transcriptomic level, with M. gigas showing elevated molecular responses to OA stress. Our findings suggest that the two species may employ distinct adaptive strategies to mitigate low pH that are informative for species-specific management strategies.

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Carbon dynamics and water quality regulation in Ruditapes philippinarum-Chlorella vulgaris co-culture with cardiac monitoring

Published 8 October 2026 Science Closed
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Highlights

  • Clam addition rapidly altered nitrogen, oxygen and dissolved-carbon dynamics.
  • All chamber treatments maintained negative CO₂ fluxes during incubation.
  • Algal monoculture showed stronger 6-h CO₂ uptake than co-culture.
  • Hydrochemical variables and cardiac activity were recorded concurrently.

Abstract

Global warming and ocean acidification threaten marine aquaculture. Bivalve-microalgae co-culture is considered a promising approach for low-carbon aquaculture, but its effects on water quality, carbon dynamics and bivalve physiology are not fully understood. This study tested Ruditapes philippinarum and Chlorella vulgaris in sealed static chambers with three treatments: sterile seawater (NP-C), Chlorella monoculture (WP-C) and clam-Chlorella co-culture (WP). Water-quality variables, dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), air-water CO₂ flux and clam heart rate were measured in separate 3-h and 6-h incubations. At the end of incubation, WP had higher ammonium concentrations and lower dissolved oxygen than WP-C, indicating that clam addition changed nitrogen and oxygen conditions. DOC and DIC also changed differently in the two biological treatments. All treatments showed negative air-water CO₂ fluxes. In the 6-h experiment, CO₂ uptake was strongest in WP-C and intermediate in WP. Heartbeats were recorded continuously in four clams for 7.07 h. Overall, the co-culture rapidly altered water-quality and dissolved-carbon dynamics but did not result in greater short-term CO₂ uptake than the algal monoculture under the present chamber conditions.

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Long-term exposure to ocean acidification modifies the biochemical composition of the adductor muscle of the commercial scallop Zygochlamys patagonica

Published 7 October 2026 Science Closed
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The scallop Zygochlamys patagonica is an ecologically and economically important seafood species in the Southwest Atlantic Ocean that has been shown to be sensitive to ocean acidification (OA), a global process caused by anthropogenic carbon dioxide emissions. This study experimentally evaluated the effects of a long-term exposure to low pH, including an OA scenario on the scallop adductor muscle— the commercially valuable tissue. We tested three levels of pH, two pH values within the present range of natural variability (high pHT= 8.00 and medium pHT= 7.80) and a lower pH level representing a true OA scenario (low pHT: 7.52). We examined biochemical alterations induced by low pH and assessed the potential for reversibility following a depuration period. No significant effects were observed for medium pH exposure. However, after 14 and 28 weeks of exposure to low pH (OA), significant reductions in protein and total lipid content were observed, resulting in decreased overall energy reserves, while glycogen levels remained unchanged. The fatty acid profile shifted under OA with an increased PUFA/ SFA ratio and higher sums of EPA and DHA. No signs of recovery were detected after the 2-month depuration period. These results indicate that OA-driven changes in biochemical composition may reflect altered physiological status, with potential socio-ecological implications for the sustainable exploitation of this valuable resource.

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Single-larva transcriptomics resolve phenotype-anchored Na+ K+ ATPase expression during first shell formation in Pacific oyster larvae under ocean acidification conditions

Published 5 October 2026 Science Closed
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Bivalve larvae are highly sensitive to ocean acidification (OA) conditions, a global climate shift that applies selective pressure on calcareous marine organisms. Although a growing body of work exists on the effects of OA on bivalve larvae, most studies rely on pooled-larval sampling, which may obscure gene expression patterns by including larvae with severely underdeveloped or deformed phenotypes, which are common in OA conditions but are unlikely to survive to metamorphosis. Here, we tested a combination of single-larva transcriptomic techniques to investigate the expression of a candidate gene previously shown to be upregulated in OA conditions, Na+ K+ ATPase (NKA), in Pacific oyster larvae of known phenotypes. We found that upregulation of the NKA gene is detected primarily in larvae with a developed first shell (prodissoconch I), and was not pronounced in underdeveloped or deformed larvae, suggesting its expression reflects active shell formation under OA conditions, rather than a generalized stress response. Further, NKA mRNA was primarily localized along the dorsal shell hinge, the site of CaCO3 deposition, substantiating its role in early shell development. This study provides a methodological framework for phenotype-anchored sampling to investigate the expressional signatures underpinning successful shell development in OA conditions.

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Involvement of CgPGC-1α in regulating mitochondrial biogenesis in Pacific oyster Crassostrea gigas under ocean acidification

Published 5 October 2026 Science Closed
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Highlights

  • CgPGC-1α with classical RRM domain was identified from Crassostrea gigas.
  • CgPGC-1α mRNA was ubiquitously expressed with the highest level in gill.
  • CgPGC-1α could respond to acidification treatment, promote mitochondrial biogenesis.
  • Acidification enhanced mitochondrial biogenesis and ATP via AMPKα/PGC-1α.

Abstract

Ocean acidification poses a significant threat to calcifying marine organisms. The Pacific oyster Crassostrea gigas is an economically and ecologically important bivalve species. Understanding the molecular mechanisms underlying its physiological adaptation to acidification stress is therefore of great ecological and aquaculture relevance. Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) is a central regulator of mitochondrial biogenesis and cellular energy metabolism, which plays important roles in response to various stressors. In this study, a PGC-1α homolog was identified from Crassostrea gigas (CgPGC-1α), which harbors an evolutionarily conserved RRM domain. The phylogenetic tree indicated that CgPGC-1α first clustered with PGC-1α from molluscs, then grouped with vertebrate PGC-1α, and finally joined with the PGC-1α of arthropods. During larval development, expression level of CgPGC-1α increased from the early embryonic stages, reached its highest level at blastula stage, and subsequently decreased during later development stages. In adult oysters, expression level of CgPGC-1α were detected in haemocytes and all examined tissues, with the highest level in gills. When the oysters were exposed to acidified seawater at pH 7.4, the expression level of CgPGC-1α in gonad was significantly upregulated at 7 and 21 days. Furthermore, at 7 days after acidification treatment, the mtDNA copy number, the expression level of CgMFN mRNA transcripts, the CgPGC-1α protein levels and the pAMPKα (Thr172) phosphorylation levels all significantly increased (p < 0.05), while the relative mRNA expression level of CgDRP1 significantly decreased (p < 0.05). Moreover, a significant increase in the number of mitochondria with morphology changing from elliptical to irregular and cristae becoming swollen was observed, and the ATP content was significantly elevated. After 28d days of acidification, mtDNA copy number and the expression level of CgMFN and CgNRF2 were significantly decreased, whereas the expression level of CgDRP1 was significantly increased. Collectively, these findings reveal a temporal response to acidification, characterized by an early compensatory activation of the AMPKα/PGC-1α axis and enhanced mitochondrial biogenesis, followed by impaired mitochondrial homeostasis under prolonged acidification stress. This study provides new insights into the molecular mechanisms underlying oyster resilience to ocean acidification and highlights the potential importance of mitochondrial adaptation in coping with future environmental changes.

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Ocean acidification remodels the mantle phosphoproteome and weakens shell mechanical resilience in Mytilus edulis

Published 2 October 2026 Science Closed
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Highlights

  • Ocean acidification causes pH- and time-dependent disruption of nacreous and prismatic microstructures.
  • Shell compressive strength declines progressively with decreasing pH and exposure duration.
  • Quantitative mantle phosphoproteomics identified 3720 phosphoproteins and 10,780 phosphosites.
  • Differential phosphorylation is associated with signaling, vesicular trafficking, autophagy, and metabolic pathways.
  • Molecular and shell-level responses support a proof-of-concept dual-indicator framework.

Abstract

Ocean acidification (OA), driven by rising atmospheric CO2, threatens the structural integrity and ecological performance of calcifying marine organisms, yet the mechanistic links between environmental acidification and compromised shell mechanical resilience remain insufficiently understood. Here, we integrate microstructural imaging, mechanical testing, and quantitative phosphoproteomics to characterize the structural, mechanical, and phosphorylation responses of Mytilus edulis to OA and examine their relationships. Adult mussels were exposed to near-future pH conditions (8.1, 7.9, 7.7) for up to 40 days. OA produced progressive disorganization of nacreous tablets and prismatic columns without altering aragonite–calcite polymorphs, indicating that acidification drives structural degradation rather than mineralogical shifts. Correspondingly, shell compressive strength declined in a pH- and time-dependent manner, with an approximately 60% reduction at pH 7.7 after 40 days. Phosphoproteomic profiling identified 3720 phosphoproteins (10,780 sites), revealing extensive acidification-induced remodeling of phosphorylation networks. Proteins corresponding to differentially phosphorylated peptides were predominantly nuclear and were enriched in kinase-, PH-, PDZ-, and RNA-recognition-domain-containing proteins. Functional analyses implicated MAPK signaling, vesicular trafficking, ion transport, glycolysis/gluconeogenesis, autophagy, and calcium-associated processes. Phosphoproteomic remodeling was associated with the deterioration of shell microstructure and compressive strength, supporting an association between mantle phosphorylation responses and compromised biomineralization under acidification. The enriched pathways and protein domains were functionally related to calcium-dependent signaling, vesicular trafficking, cytoskeletal organization, and cellular metabolism, providing testable candidates for future mechanistic validation. Together, these findings support a working model in which ocean acidification is accompanied by coordinated phosphorylation remodeling and progressive loss of shell mechanical resilience. We further propose a proof-of-concept dual-indicator framework that integrates candidate molecular sentinels with organismal metrics, providing a conceptual basis for future assessment of aquaculture resilience and ecosystem vulnerability under progressive ocean acidification.

Graphical abstract

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Survival costs flavor: microplastics reprogram metabolic resource allocation and compromise oyster quality under ocean acidification

Published 30 September 2026 Science Closed
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Ocean acidification (OA) and microplastic (MP) pollution are widespread marine stressors, yet their interactive effects on seafood quality and molecular metabolism remain unclear. This study investigated the combined effects of OA (pH 7.7) and MPs (2 and 200 μg/L) on the Pacific oyster (Magallana gigas). OA was the primary driver of textural deterioration, significantly reducing springiness and chewiness, while combined stress synergistically depleted protein and lipid reserves. Distinct lipid remodeling strategies were identified: OA induced DHA accumulation potentially associated with membrane stabilization, whereas MPs triggered EPA and ARA upregulation associated with stress and immune responses. The flavor profile was severely compromised, characterized by depletion of umami amino acids, nucleotide redistribution, and altered succinate contribution. Transcriptomic analysis revealed that high MP exposure activated genome maintenance and DNA repair-associated pathways, including the Fanconi anemia pathway, superimposed on OA-associated metabolic suppression. Concurrent upregulation of nucleotide salvage (APRT, HPRT) and amino acid catabolic genes (GLS, GDH) suggests increased utilization of flavor metabolites for energetic demands. These findings support a bioenergetic trade-off in which oysters exposed to OA and MPs reallocate resources from nutritional and sensory quality toward cellular maintenance and stress adaptation, highlighting underrecognized consequences of climate change and plastic pollution for seafood quality.

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Asymmetric metabolic responses of rockweed and herbivores reveal seasonal vulnerabilities to warming and acidification

Published 22 September 2026 Science Closed
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Macroalgal-herbivore interactions are fundamental to the stability of coastal ecosystems and their vulnerability to climate-driven shifts will affect biodiversity and ecosystem functioning. However, the effects of climate change on species interactions may be context dependent and vary by seasonal oceanographic processes. We examined the effects of warming and acidification on an intertidal primary producer foundation species, Silvetia compressa, and its herbivore, Agathistoma eiseni, under differing upwelling regimes in early (low upwelling) and late spring (high upwelling). We measured metabolic rates including photosynthesis, respiration, and calcification after four weeks of exposure to a range of nine pH levels (7.2–8.0) at two temperature levels (16°C, 20°C). Rockweed responded more to acidification than to warming, but showed different seasonal responses, decreasing photosynthetic rates in early spring and increasing rates during late spring. Their snail consumer, however, responded most strongly to temperature, increasing both respiration and calcification rates under warm conditions in late spring. Our findings demonstrate that seasonal differences can modulate responses of macroalgae and herbivores to changing environmental conditions. Warming may increase top-down effects through increased snail metabolism, while acidification affects rockweed production to affect bottom-up forcing. By assessing physiological responses across different ecological regimes, our study advances understanding of how top-down and bottom-up processes interact in intertidal ecosystems under global change.

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TNF-NF-κB signaling mediates immune-biomineralization crosstalk during shell repair under ocean acidification in Mytilus edulis

Published 17 September 2026 Science Closed
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Highlights

  • Day-15 shell closure ≠ functional repair: pH 7.7 disrupts microstructure, delays crystallization, and causes ∼87% strength loss.
  • Hemocytes: early divergence (pH 7.9 inflammatory vs. pH 7.7 stress), late convergence with weak effectors; mantle upregulates immunity, suppresses OXPHOS/ECM.
  • TNF-NF-κB (TNFSF14/TRAF6/IκBα) mediates immune-mineralization crosstalk, linking immunity to repair impairment.
  • Multi-tissue dysregulation causes repair failure – not a single bottleneck, but decoupling of recruitment from deposition.

Abstract

Ocean acidification (OA) impairs biomineralization in bivalves, but its effects on immune-biomineralization crosstalk during shell repair remain unknown. Here, we exposed adult Mytilus edulis bearing standardized shell perforations to three pH levels (8.1, 7.9, and 7.7) for up to 40 days. OA slowed early repair and caused microstructural disorganization and an approximately 87% reduction of compressive strength at pH 7.7, yet the damaged area appeared largely closed by day 15, suggesting a decoupling between morphological closure and functional recovery. In addition, transcriptomic profiling of hemocytes and mantle tissue, based on an average of 6.5 Gb of clean reads per sample mapped to the M. edulis reference genome (NCBI Assembly GCF_000511035.1), revealed that these shell-level defects were accompanied by coordinated immune and metabolic reprogramming. Hemocytes, the primary immune effector cells of bivalves, exhibited pH- and time-dependent shifts with moderate acidification (pH 7.9) promoting inflammatory transcripts, whereas severe acidification (pH 7.7) suppressed these signals while upregulating stress-associated pathways; both treatments consistently downregulated lysosomal proteases and NF-κB negative regulators. The mantle, a primarily mineralizing organ, paradoxically upregulated immune-related genes while suppressing oxidative phosphorylation and extracellular matrix pathways. This tissue-level imbalance, with hemocytes recruited but functionally constrained and mantle metabolically suppressed yet immunologically activated, points to TNF-NF-κB pathway modulation as a key mediator of shell repair under acidification. Our findings demonstrate that visible shell closure masks underlying structural and mechanical failure, and that immune regulation, rather than simple suppression or activation, critically shapes the repair outcome. These results advocate for multifunctional indicators beyond closure area to assess shell integrity in acidified marine environments.

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Brood chamber carbonate chemistry in the oyster Ostrea edulis is dynamically shaped by warming, acidification, and ventilation

Published 14 September 2026 Science Closed
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Brooding organisms can modify the chemical environment experienced by developing offspring, potentially altering their exposure to climate change. In marine systems, however, the carbonate chemistry of brood chambers, and the mechanisms governing it, remain poorly resolved. Here, we combine high-resolution pH and CO2 measurements of the empty brood chamber (i.e., mantle cavity above gills) in the European flat oyster (Ostrea edulis) while also tracking valve gape to quantify how warming, ocean acidification, and ventilation interact to shape the internal environment experienced by larvae during incubation. Brood chamber pH was consistently lower than that of the surrounding seawater and responded to external conditions in a state-dependent manner governed by ventilation and respiration. When oysters were actively ventilating, brood chamber chemistry tracked ambient seawater with a persistent offset, whereas valve closure led to rapid CO2 accumulation and pronounced declines in pH. These dynamics generated highly variable and behaviorally mediated exposure regimes, in which metabolic processes distorted ambient chemical signals over short timescales. Paired pH and CO2 measurements provided preliminary constraints on aragonite saturation state (Ωar), revealing that brood chambers can remain undersaturated (Ωar < 1) for prolonged periods even in ventilating oysters and while overlying seawater remains favorable. Together, these results demonstrate that brood chambers function as dynamic microenvironments in which larval exposure to ocean acidification is governed not only by external conditions, but also by behavior. Because warming enhances metabolic CO2 production and intensifies acidification within the chamber, future climate change is likely to amplify both the magnitude and variability of larval exposure. These findings help explain the apparent resilience of brooding species to ocean acidification, while also highlighting potential limits as environmental conditions move beyond historical bounds.

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Ocean acidification and nanoplastics disrupt mussel calcification in synergy: a multi-omics analysis

Published 14 September 2026 Science Closed
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Highlights

  • Ocean acidification disrupts calcium homeostasis in the mantle of mussels.
  • Ocean acidification and N-NPs together intensify the inhibition of calcification.
  • Surface charge determines distinct, mechanism-specific response pathways.
  • Both omics reveal key roles for calcium transport, CA, and ECM synthesis.

Abstract

Ocean acidification (OA) and nanoplastics (NPs) increasingly co-occur in coastal ecosystems, yet their combined mechanistic impacts on calcifying invertebrates remain poorly resolved. Here, the mussel Mytilus coruscus was exposed for 30 days to factorial combinations of OA (pH 7.7 vs 8.1), surface-modified polystyrene NPs at a concentration of 100 μg/L (positively and negatively charged), and experimental shell damage to assess effects on shell repair, ion homeostasis, and energy metabolism. OA reduced shell repair quality by thinning repair layers, increasing porosity, and lowering calcium content, effects that were further enhanced by co-exposure to NPs, particularly negatively charged particles. OA and NPs jointly altered Ca2+ and Mg2+ levels, alkaline phosphatase activity, Ca2+Mg2+-ATPase activity, and key indicators of energy metabolism, including ATP content and cellular energy allocation. Transcriptomic and proteomic analyses revealed enrichment of ion transport, extracellular matrix, TGF-β signaling and other pathways, with divergent patterns linked to NPs surface charge. Together, these results suggest that nanoplastic surface charge under OA may impair mussel shell repair through associated alterations in ion homeostasis and energy metabolism. These findings highlight that particle surface properties shape how organisms respond to combined environmental stressors in acidifying marine environments.

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Chapter 23 – Climate change: effects and implications

Published 10 September 2026 Science Closed
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The coastal zone is an epicenter of climate change impacts, including rising sea levels, an increase in sea temperature, and a decrease in salinity through precipitation and ice melt. In addition, changes in carbon chemistry will result in the “acidification” of seawater. Direct physiological effects of extreme weather events will likely cause some sub-optimal changes in Manila clam abundance, with implications for aquaculture production, especially in warmer waters such as the Adriatic and the west coast of the Korean penisula. Indirect effects on food and predator species and synergistic impacts of multiple pollutants may also prove influential. Currently predicted acidification will, in itself, be within the tolerances of R. philippinarum, although it may contribute to increased oxidative stress and energetic demand, especially when in combination with other challenges. Overall, while Manila clam distributions, locally, regionally, and globally, will adjust, the species is considered resilient within temperate conditions and is expected to extend its global distribution northwards in Alaska, Europe, and probably Siberia.

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Environmental regulation and disruption of shell biomineralization in bivalves and gastropods: a mechanistic review

Published 10 September 2026 Science Closed
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Molluscan shells are increasingly threatened by a complex array of environmental stressors—climate-related drivers, changes in seawater chemistry, contaminants, and biotic cues. This review provides a mechanistic synthesis of how these stressors disrupt the biomineralization process across life stages. We develop a conditional hierarchical response framework from the reviewed evidence. The framework links ionoregulatory and acid-base disturbances with molecular, microstructural, and shell-level responses, while allowing for compensatory, nonlinear, species-specific, and life-stage-specific outcomes. This molecular disruption manifests as defects in calcium carbonate (CaCO3) crystalline microstructure, which may in turn compromise shell macro-scale physical properties (strength, hardness, growth). We synthesize combined and context-dependent effects of co-occurring stressors and distinguish formally tested interactions from qualitative comparisons of combined treatments. Future research must leverage integrated multi-omics, advanced in vivo imaging, and multi-stressor experimental designs to unravel candidate molecular and physiological thresholds and predict adaptive potential. This framework may help identify testable mechanisms, evidence gaps, and context-dependent vulnerabilities relevant to conservation.

Highlights

  • A conditional framework links molecular, microstructural, and shell-level responses.
  • Early stages often show high sensitivity, although direct ontogenetic comparisons remain limited.
  • Energy limitation is a recurrent, but often indirectly inferred, physiological constraint.
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Elevated pCO2 impairs overall byssus attachment strength in the blue mussel (Mytilus edulis) without altering byssus thread quality

Published 8 September 2026 Science Closed
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Increasing atmospheric carbon dioxide (CO2) is driving global ocean acidification (OA). This process may threaten the persistence of bed-forming mussels by weakening the byssal system that anchors them to the seafloor. Here, blue mussels (Mytilus edulis) were exposed to present-day (∼460 ppm pCO2) normocapnic and projected end-century (∼1200 ppm pCO2) hypercapnic conditions for four weeks at 12 °C. Byssus production, thread morphology, whole-byssus mechanics and the underlying physiological condition index (CI) were quantified. Unlike previous studies, this study analysed the byssus as an intact functional unit. This approach better reflects its mechanical performance in situ. Median thread production fell by 50% under elevated pCO2 and the number of individuals producing no threads at all increased from 3% to 23% of the population. Thread diameter and plaque area were unaffected. Whole byssus tensile testing revealed a distinctive mechanical pattern (elastic loading, force plateau, and structural failure) regardless of environmental CO2 concentration. Whole byssus attachment strength scaled linearly with thread number in both treatments, and the mechanical work required to detach mussels under hypercapnia dropped by 42%. Elevated pCO2 reduced mussel condition index by 19% relative to the control, indicating an energetic burden. These results show that near-future ocean acidification weakens mussel attachment primarily by lowering individual physiological condition, which directly drives the reduction in total attachment energy, rather than by lowering individual thread quality. This likely results from a shift in energy use away from thread production, as seen in poorer mussel condition. As a result, mussels may become more prone to being dislodged by waves or predators. The findings of this study indicate that ocean acidification can reduce the overall strength of M. edulis beds, with important effects on rocky shore ecosystems and the viability of mussel farming in a changing climate.

Continue reading ‘Elevated pCO2 impairs overall byssus attachment strength in the blue mussel (Mytilus edulis) without altering byssus thread quality’

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