table isotopes are fundamental proxies for deciphering past environmental conditions and carbon cycle perturbations. However, applying these geochemical tools with a forward-looking perspective can also help predict the resilience of marine biota in future acidified oceans. This study investigates carbon uptake and biomineralization pathways under reduced pH in two ecologically keystone calcifying species: the bivalve Mytilus galloprovincialis and the gastropod Phorcus sp. To unravel these mechanisms, we adopted a dual approach, comparing isotopic trajectories (δ13C) under strictly controlled laboratory mesocosms with observations from natural CO2 vent systems in Ischia, Italy. Our results reveal a striking discrepancy between settings. Under laboratory conditions, both species exhibited a significant depletion in shell δ13C as pH decreased, directly tracking seawater carbonate chemistry. Conversely, specimens from the volcanic vents displayed a paradoxical δ13C enrichment at low-pH sites (pH ~7.4). These divergent trajectories indicate that in complex natural environments, the geochemical signal of ocean acidification can be overridden by metabolic overprints and trophically driven vital processes. Consequently, while laboratory experiments are essential to isolate kinetic fractionation, natural analogues remain crucial to capture the biological resilience and complex ecological feedback of future oceans. Future research combining these geochemical trends with direct, in vivo physiological assessments will be essential to precisely constrain the underlying metabolic kinetics and refine predictive metabolic models.
Continue reading ‘Biological modulation of shell δ13C in Mytilus galloprovincialis and Phorcus sp.: divergent responses between CO2 vents and laboratory mesocosms’Posts Tagged 'mollusks'
Biological modulation of shell δ13C in Mytilus galloprovincialis and Phorcus sp.: divergent responses between CO2 vents and laboratory mesocosms
Published 17 August 2026 Science Leave a CommentTags: biological response, BRcommunity, field, laboratory, Mediterranean, mesocosms, mollusks, physiology, vents
Vulnerability to low salinity but compensatory responses to low pH in an intertidal limpet
Published 7 August 2026 Science ClosedTags: biological response, BRcommunity, laboratory, molecular biology, mollusks, mortality, multiple factors, North Pacific, physiology, salinity
Highlights
- Low salinity linked to warming may intensify coastal pH reduction.
- Low salinity reduced righting and emergence in the limpet Patelloida pygmaea.
- Low salinity reduces Mg/Ca ratios in newly formed shell layers.
- Low pH increases shell thickness and Mg/Ca ratios despite dissolution.
- CHS2 upregulation suggests compensatory resistance to low pH.
Abstract
Rising anthropogenic carbon dioxide emissions have driven ongoing ocean warming and associated climate changes. In the Yellow Sea, this warming is associated with enhanced monsoonal rainfall, which increases freshwater inputs and lowers coastal salinity. Increased freshwater input can weaken seawater buffering capacity, thereby leading to lower pH conditions in coastal environments. Here, we examined the effects of low pH and low salinity on the intertidal limpet Patelloida pygmaea. Adult limpets were exposed for 31 days to four experimental artificial seawater conditions combining two pH levels (8.0 and 7.5) and two salinity levels (30 and 21 psu). Survival and condition factor were not influenced by pH or salinity. However, low salinity reduced righting and emergence behavior. In addition, the Mg/Ca ratio in the M + 1 layer was lower at 21 psu than at 30 psu. Low pH resulted in a thicker M + 2 layer with higher Mg/Ca ratios despite shell dissolution, potentially helping to maintain shell integrity. While there was no change in heat shock protein (HSP70) expression, these shell modifications were accompanied by an upregulation of chitin synthase (CHS2) genes under low pH. These findings suggest that P. pygmaea is negatively influenced by low pH and low salinity, but also demonstrate compensatory mechanisms that enhance resistance to low pH.
The effects of high carbonate alkalinity under low salinity on the survival, physiological metabolism, and redox homeostasis of Crassostrea hongkongensis
Published 28 July 2026 Science ClosedTags: biological response, laboratory, mollusks, mortality, multiple factors, oxygen, performance, physiology, salinity
High carbonate alkalinity can impose composite hydrochemical stress on bivalves by altering inorganic carbon speciation, buffering capacity and ion-exchange conditions. The Hong Kong oyster (Crassostrea hongkongensis) naturally inhabits estuarine areas where low salinity can occur together with carbonate-system disturbance, yet its physiological response to high carbonate alkalinity under a low-salinity background remains unclear. In this study, oysters were exposed at salinity 5 to a Control treatment, A10 (carbonate alkalinity 10 mmol L⁻¹) and A20 (carbonate alkalinity 20 mmol L⁻¹). Salinity was treated as a controlled background condition, whereas the alkalinity treatments represented a composite carbonate-alkalinity perturbation involving alkalinity, pH and carbonate chemistry. Survival, feeding rate, oxygen consumption, ammonia excretion and hemolymph ammonia were measured across Control, A10 and A20. Hemolymph catalase (CAT), glutathione peroxidase (GSH-Px), glucose and ATP were analyzed as A10 and A20 time-course endpoints because a parallel Control was not included for these assays. A 24-h mantle transcriptome was used to screen candidate transcripts associated with innate defense and glutathione metabolism. Oysters under A10 retained partial compensatory capacity, whereas A20 significantly reduced survival. A10 and A20 suppressed early oxygen consumption and ammonia excretion, and altered feeding allocation among microalgae. Within the A10 and A20 biochemical time-course dataset, CAT, GSH-Px, glucose and ATP showed stage-specific variation, suggesting redox and energy-metabolism adjustment under alkalinity stress. Overall, high carbonate alkalinity reduced survival and was associated with metabolic depression, feeding compensation and hemolymph redox-energy remodeling in C. hongkongensis. This study will provide a theoretical basis for water quality regulation in saline-alkaline water aquaculture and the sustainable development of aquaculture.
Continue reading ‘The effects of high carbonate alkalinity under low salinity on the survival, physiological metabolism, and redox homeostasis of Crassostrea hongkongensis’Multi-stressor responses in marine bivalves: integrating climate change, pollutants, and microbiome shifts for aquaculture resilience
Published 27 July 2026 Science ClosedTags: biological response, fisheries, mollusks, review, socio-economy
Marine bivalves play pivotal ecological and economic roles but are increasingly challenged by multiple environmental stressors. Although there is extensive research on the effects of individual stressors, a comprehensive review is needed to synthesize current evidence and clarify how multiple interacting stressors collectively affect the physiology and resilience of marine bivalves. This review integrates evidence from 2010 to 2025, encompassing 178 peer-reviewed studies emphasizing the combined and interactive impacts of climate change drivers (warming, hypoxia, salinity, and ocean acidification), pollutants (heavy metals, persistent organic pollutants, endocrine-disrupting chemicals, antibiotics, nanoparticles, microplastics), and microbiome shifts on future aquaculture resilience. Literature was systematically retrieved from Web of Science, Scopus, PubMed, and Google Scholar in accordance with PRISMA 2020 guidelines. Bibliometric mapping (VOSviewer 1.6.20) revealed a rapid growth in research after 2018, characterized by studies on Mytilus, Crassostrea, and Ruditapes. A systematic evaluation of recent evidence was conducted, combining data from physiological, molecular, and microbial studies, with particular attention to implications for aquaculture. The analysis reveals that stressors rarely act alone. Instead, their cumulative and interactive effects cause oxidative stress, disrupted energy allocation, destabilized host-microbe relationships, lowered tolerance thresholds, and other eco-physiological consequences. These results highlight the vulnerability of bivalve populations to rapid coastal urbanization, declining water quality, and sediment contamination. The review concludes that resilience can be enhanced through selective breeding for stress-tolerant genotypes, integrated monitoring of pollutants and microbial indicators, and multi-omics approaches to guide adaptive aquaculture management.
Continue reading ‘Multi-stressor responses in marine bivalves: integrating climate change, pollutants, and microbiome shifts for aquaculture resilience’The effects of decreased pH and increased temperature on survival and shell development of the larvae of the endemic Hawaiian oyster Dendostrea sandvichensis
Published 17 July 2026 Science ClosedTags: biological response, BRcommunity, growth, laboratory, mollusks, mortality, multiple factors, physiology, reproduction, temperature
Climate change models predict future ocean-wide decreases in pH and increases in temperature, posing a serious threat to calcifying marine invertebrates. In Hawaiʻi, local seawater temperature and pH are predicted to change even more rapidly. The Hawaiian oyster Dendostrea sandvichensis, an endemic species, remains understudied despite its ecological roles in reef- building, biofiltration, and as a food source. While previous studies have revealed the alarming impacts of ocean acidification and warming on bivalves, little is known about how the planktonic larvae of D. sandvichensis will respond to projected climate conditions.
To investigate these effects, the larvae of D. Sandvichensis were reared under present-day conditions in Pearl Harbor, HI (pH 8.1, 26.5 °C) and projected future conditions (pH 7.7, 30.0°C) for one week. Shell growth, density, and degradation were then measured using micro-CT, confocal, and scanning electron microscopy. Additionally, two larval husbandry methods were evaluated, with a static-flow system paired with UV water treatment yielding approximately 11- fold higher survival than an open-flow system. Elevated temperature reduced larval survival (~67%) compared to ambient conditions. Reduced pH significantly decreased shell length (~11.8μm), while both stressors reduced shell density in Experiment 3. Shell density decreased by ~12% under elevated temperature, ~18% under reduced pH, and ~43% under the combined stressors, and was accompanied by increased shell degradation and abnormalities.
These findings indicate that elevated temperature and reduced pH impact larval oysters through multiple pathways, including reduced survival and compromised shell integrity. This study provides new insights into the vulnerability of an endemic Hawaiian species and essential data for predicting its resilience under future climate change scenarios.
Continue reading ‘The effects of decreased pH and increased temperature on survival and shell development of the larvae of the endemic Hawaiian oyster Dendostrea sandvichensis’Climate change and ocean acidification outweigh local stressors in Mediterranean mussels: a multi-method convergence analysis
Published 15 July 2026 Science ClosedTags: biological response, BRcommunity, field, laboratory, Mediterranean, metals, mollusks, multiple factors, physiology
Highlights
- Climate change explains ∼40% of biological stress variance in Mediterranean mussels.
- Ocean acidification drives 67% of metal bioavailability changes via pH-metal speciation.
- 64% of climate effects on biomarkers operate indirectly through metal bioaccumulation.
- Multi-method convergence (LMG, GAM, SEM, Bayesian Networks) confirms stressor ranking.
- Only SSP1-2.6 keeps biological stress below the chronic-stress threshold through 2050.
Abstract
Marine coastal ecosystems face concurrent pressure from climate change and anthropogenic contamination, yet their relative contributions to biological stress remain poorly quantified. Here we present a decade-long (2014–2023) biomonitoring study on Mytilus galloprovincialis in the Ligurian Sea (NW Mediterranean), integrating quarterly biomarker measurements, heavy metal bioaccumulation data (12 metals), and high-resolution oceanographic records at a control site (Gorgona Island Marine Protected Area) and an offshore regasification terminal.
Biological stress variance was partitioned using five complementary analytical frameworks — Lindeman–Merenda–Gold (LMG) variance decomposition, Hierarchical and Generalised Additive Models (HGAM/GAM), Structural Equation Modelling (SEM), and Bayesian Networks — applied to four biomarkers: DNA damage, lysosomal membrane stability, gill tissue integrity, and immune response. A campaign-specific T0 baseline normalisation isolated environmental signals from initial population variability.
Climate change emerged as the dominant driver, consistently explaining ∼40% of variance across all methods, significantly exceeding metal bioaccumulation (∼30%), terminal influence (∼13%), and seasonal effects (∼2%). Ocean acidification was the primary climate mechanism, influencing 67% of analysed metals. Causal mediation analysis revealed that 64% of the climate effect operates indirectly through enhanced metal bioaccumulation (Climate→Metals→Biomarkers), while 36% acts directly. Climate and biological stress indices co-varied strongly (ρ = 0.78, p < 0.001), with marine heatwaves coinciding with peak biomarker responses.
Under IPCC Shared Socioeconomic Pathway (SSP) scenarios, the Biological Stress Index is projected to cross chronic-stress thresholds by 2035–2040 under the high-emission scenario (SSP5-8.5) and the intermediate-emission scenario (SSP2-4.5), with only the low-emission scenario (SSP1-2.6) maintaining stress below critical levels through 2050.
These findings challenge pollution-centric monitoring paradigms and demonstrate that CO2 mitigation now constitutes the highest-leverage intervention for marine invertebrate health in the Mediterranean.
Graphical abstract
This graphical abstract illustrates the main findings of a decade-long field study (2014–2023) on the effects of climate change and metal contamination on Mytilus galloprovincialis in the Ligurian Sea (NW Mediterranean). Three panels summarise the causal chain from environmental drivers to biological outcomes. The first panel depicts the key oceanographic trends recorded at the study site: ocean warming (+0.41°C/decade), acidification (−0.020 pH units/decade), deoxygenation, and a doubling of marine heatwave frequency after 2018. The second panel shows how pH decline enhances the bioavailability of 67% of the metals analysed, driving a predominantly indirect pathway (64%) from climate stressors to biological stress, mediated by metal bioaccumulation, as revealed by structural equation modelling and Bayesian network analysis. The final panel presents the four biomarkers used to compute the Biological Stress Index (BSI), its strong temporal correlation with the Climate Change Index (ρ = 0.78), and BSI projections to 2050 under three IPCC emission scenarios, showing that only SSP1-2.6 keeps BSI below the chronic-stress threshold throughout the projection period.
Ocean acidification changes diet effects and differentially impacts two populations of red abalone (Haliotis rufescens)
Published 14 July 2026 Science ClosedTags: biological response, BRcommunity, community composition, laboratory, mollusks, morphology, mortality, multiple factors, nutrients, otherprocess, performance, 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)’Strong effects of sun exposure on oyster shell corrosion and compensatory calcification: a factor confounding coastal acidification responses
Published 13 July 2026 Science ClosedTags: biological response, calcification, field, laboratory, molecular biology, mollusks, North Pacific, physiology
The dynamics of calcium carbonate structures in marine organisms (skeletons and shells) has become increasingly important due to heightened interest in marine environmental acidification. Research into molluscan shell corrosion and calcification in response to acidification is typically carried out in laboratory-controlled settings, which often overlooks the intricate interactions found in natural environments. Mollusks inhabiting intertidal zones are especially susceptible to intense shell weathering caused by tidal cycles of heating, cooling, wetting, and drying, exacerbated by solar radiation during periods of air exposure. We investigated the effect of sun exposure (solar radiative heating) on both outer shell corrosion and inner shell compensatory calcification in the tropical oyster, Saccostrea scyphophilla. Shell properties were compared between oysters from neighboring populations in sun-exposed and shaded habitats. Habitat temperatures were measured using iButtons, and right shell valve corrosion was quantified. Compensatory calcification was assessed through measurements of shell thickness, shell density, shell compression strength, and mineralogical properties. Our results revealed that oysters in the sun that experience global irradiance, higher temperature peaks and broader daily temperature ranges (averaging an increase of 10 °C) show considerably greater outer shell surface corrosion (87%) compared to shaded oysters (31%) that experience only diffuse irradiance. Sun-exposed shells also become thickened in the midsection and around the adductor muscle, and they are slightly stronger, indicating compensation for the outer shell loss. These findings highlight the need for caution when interpreting molluscan shell dynamics based on laboratory marine acidification protocols that fail to account for the many natural environmental factors influencing shell formation and dissolution.
Continue reading ‘Strong effects of sun exposure on oyster shell corrosion and compensatory calcification: a factor confounding coastal acidification responses’Impact of water quality and gear type on Eastern oyster (Crassostrea virginica) growth in Narragansett Bay, RI
Published 1 July 2026 Science ClosedTags: biological response, growth, laboratory, mollusks, mortality, North Atlantic, physiology
Oyster aquaculture is expanding in Rhode Island, yet key farming regions in the lower West Passage of Narragansett Bay (WPNB) lack the in-situ, high-temporal resolution monitoring needed to evaluate emerging stressors and support production. At the same time, the industry is undergoing rapid technological development aimed at improving production while reducing labor and overall costs. In recent years, a low maintenance, alternative surface gear was introduced in WPNB; however, its impact on oyster performance relative to traditional cultivation methods has not been quantified. This study established a 1.5-year continuous water quality time series in WPNB and paired these observations with physiological assessments of Crassostrea virginica grown in three cultivation methods (i.e., traditional surface, alternative surface, and bottom gear). This work aimed to better understand the impact of environmental variability and gear type on oyster health, growth, and survival. Multiparameter sondes and discrete bottle samples were used to monitor water quality and calculate carbonate saturation state (Ω) at a 4-acre oyster farm. Nine mesh bags containing early-life stage C. virginica (16 ± 0.4 mm; n = 300 per bag) were deployed in July 2025, with three replicate bags in each gear type. Subsamples (n = 15) from each gear type were collected over a 6-month period for morphometric measurements and scope for growth (SFG) determinations. Minimal differences in carbonate chemistry were observed among sampling sites and Ω remained supersaturated (Ω >1) for the majority of the study period, indicating that ocean acidification was not a major stressor for farmed oysters. Survival was highest (82 ± 4.5%) in surface gear types compared to bottom gear (27 ± 0.58%), while physical growth (shell and tissue) and SFG were largely similar among all gear types. These results suggest that the alternative surface gear may support comparable production and product quality to traditional gear types, while also reducing maintenance and labor demands. Overall, this study provides important physiological and biological context for oyster aquaculture while informing gear selection and farm management strategies.
Continue reading ‘Impact of water quality and gear type on Eastern oyster (Crassostrea virginica) growth in Narragansett Bay, RI’Will the Mediterranean sea be a cul-de-sac for marine gastropods under climate change?
Published 23 June 2026 Science ClosedTags: biological response, BRcommunity, communitymodeling, individualmodeling, Mediterranean, modeling, mollusks, North Atlantic, physiology, reproduction
Marine ecosystems are undergoing rapid transformation under climate change, yet the responses of many marine invertebrates remain vastly understudied. In particular, for many benthic gastropods there is a striking imbalance between their traditional appreciation by shell collectors—and, consequently, their consistent representation in Natural History Collections—and the limited attention they receive in ecological and conservation studies. Focusing on the northeastern Atlantic and the Mediterranean, the cowries Luria lurida, Naria spurca, Zonaria pyrum and the frog-shell Talisman scrobilator are emblematic examples of this knowledge gap, despite being frequently mentioned as species of conservation concern. Using long-term occurrence records spanning more than a century, we modelled past and present distributions of these species and explored their potential responses to future climate scenarios through a multi-temporal Species Distribution Modelling framework. Our results show that intermediate climatic conditions—both in time (2050–2060 vs. 2090–2100) and scenario intensity (moderate SSP2-4.5 versus high-emission SSP5-8.5)—may represent a critical transition phase, leading to habitat contractions without compensatory gains in newly emerging suitable areas. The Mediterranean Sea is expected to increasingly function as a cul-de-sac, with the dominant circulation patterns strongly limiting outward movements towards cooler regions for species relying on planktic larvae for dispersal. Furthermore, incorporating larval sensitivity to reduced pH suggests that large areas of the Atlantic Ocean may actually result unsuitable for larval persistence, substantially reducing the habitat effectively available for completion of the full life cycle; this highlights the need to account for connectivity, life-history constraints and juvenile-stage sensitivity when assessing climate-driven range shifts in shelled organisms with planktic larvae.
Continue reading ‘Will the Mediterranean sea be a cul-de-sac for marine gastropods under climate change?’Marine invertebrates and fishes exhibit inconsistent body size responses to ocean acidification
Published 18 June 2026 Science ClosedTags: algae, annelids, biological response, BRcommunity, bryozoa, cnidaria, community composition, corals, crustaceans, echinoderms, fish, Indian, laboratory, mollusks, morphology, North Pacific, otherprocess, physiology, vents
Body size is a fundamental characteristic of all living organisms that determines physiological functions and life-history traits. Ecological theory predicts that ocean acidification can cause body size reductions, confirmed by several studies reporting miniaturization in ectotherms. Based on this prediction, we would expect a broad suite of species to show similar plastic body-size responses to elevated CO2. Using four natural climate change analogues of ocean acidification across the northern and southern hemispheres, we quantified body size alterations across 18 marine invertebrate and fish taxa to test for climate-driven miniaturization. Only three species consistently showed body-size reductions under ocean acidification: one urchin and two fish species. In contrast, 15 other species, ranging from highly calcified to non-calcified, displayed unchanged or increased body sizes or inconsistent miniaturization. If body-size miniaturization responses were consistently reproducible across taxa we would have observed it more frequently, suggesting that species responses to ocean acidification are more variable than previously thought and likely vary depending on a species’ physiology and life history. Thus, rather than entire communities undergoing miniaturization, species are likely to display a spectrum of responses, with some exhibiting size reductions, others demonstrating physiological resistance to elevated CO2, and others potentially benefiting from the indirect effects of ocean acidification.
Continue reading ‘Marine invertebrates and fishes exhibit inconsistent body size responses to ocean acidification’Pteropod vulnerability to ocean acidification in the eastern Arabian Sea
Published 18 June 2026 Science ClosedTags: biological response, BRcommunity, Indian, laboratory, mollusks, zooplankton
Highlights
- First study on pteropod response to ocean acidification in the eastern Arabian Sea.
- High pteropod abundance during fall inter monsoon season due to food availability.
- pH in the Arabian Sea was low during south west monsoon with pHT upto 7.75
- Pteropod shell dissolution was observed under acidified conditions
- Protrusions through the pteropod shell were observed under acidified conditions
Abstract
The rapid rise in atmospheric CO2 and its subsequent uptake by the oceans has led to ocean acidification and other associated changes in the marine ecosystem. The recent reports of the shoaling of the aragonite saturation horizon in the northern Indian Ocean are particularly alarming, as they pose a serious threat to the survival of calcareous organisms. Pteropods, also known as sea-butterflies, are believed to be highly susceptible to ocean acidification due to their thin aragonite shell. In our study in the eastern Arabian Sea, we found low pH conditions with surface pHT as low as 7.751 during late South-west monsoon (SWM). The pteropod abundance is high during the fall inter-monsoon (FIM), suggesting that the system continues to sustain productivity even after the cessation of peak monsoon activity. This also implies that the food availability regulates pteropod abundance in the eastern Arabian Sea. As pteropods are key components of food sources for many marine species, such as fish, any changes in their abundance can have cascading effects on the marine food web. To show how pteropods will be affected in futuristic elevated CO2 conditions, a CO2 manipulation experiment was conducted in the eastern Arabian Sea during December 2024. Pteropods belonging to Creseis acicula from the eastern Arabian Sea were subjected to pHT = 7.470, and pCO2 = 1734 μatm under controlled conditions. Our findings suggest that acidification led to the dissolution of pteropod shells. Acidification also led to protrusion through the shells, and these protrusions varied in length up to 88 μm. These structural alterations represent an acute response of pteropod shells to reduced pH, highlighting their rapid vulnerability to acidification stress. These observed protrusions need to be assessed further to determine if they provide any competitive advantage in combating or minimizing the impact of ocean acidification.
Continue reading ‘Pteropod vulnerability to ocean acidification in the eastern Arabian Sea’Response mechanism of Sepia esculenta larvae under global warming, ocean acidification and salinity fluctuation: Integrated biochemical and transcriptome profiling
Published 12 June 2026 Science ClosedTags: biological response, growth, laboratory, molecular biology, mollusks, North Pacific, physiology, reproduction
Highlights
- Analysis based on global warming, ocean acidification and salinity fluctuation.
- Multi-angle analysis of Sepia esculenta under temperature, pH and salinity stress.
- Different stress enhanced the immune defense and antioxidant defense of S.esculenta.
- The hub genes closely related to stress resistance were identified and screened out.
Abstract
The Sepia esculenta occupies a significant economic proportion in the squid family, and it is also the squid with the largest economic value in the northern sea area of China. With the occurrence of global warming, ocean acidification and ocean salinity fluctuations, it has caused serious negative effects on the development of the S. esculenta artificial breeding industry. Therefore, in the research, we employed weighted gene co-expression network analysis (WGCNA) to investigate the effects of three environmental factors, including salinity, temperature and pH, on the molecular mechanism of S. esculenta larvae, and proved the reliability of transcriptome results through physiological indicators. Enrichment analysis of each module indicated that environmental exposure markedly influenced immune function, oxidative stress responses, and other physiological processes in S. esculenta larvae. Our research elucidates the comprehensive response mechanism of S. esculenta under different environmental stresses, clarifies the significant molecular pathways essential for its growth and development.
Continue reading ‘Response mechanism of Sepia esculenta larvae under global warming, ocean acidification and salinity fluctuation: Integrated biochemical and transcriptome profiling’Ocean acidification effects on larval development and survival in commercially important shellfish
Published 10 June 2026 Science ClosedTags: biological response, fisheries, growth, mitigation, molecular biology, mollusks, mortality, physiology, reproduction, socio-economy
This paper studies the consequences of ocean acidification (OA) on the growth and survival of the larvae of commercially significant shellfish species such as oysters, mussels, and scallops. The authors of the study are particularly concerned with the negative processes of OA with respect to the growth of larvae, shell development, and behavior, which result in decreased survival rates, particularly the consequences of the reduced availability of calcium carbonate on the weakening of shells and larvae, which are preyed upon. The paper also studies the interference with the behavior of larvae, particularly with respect to the adequate detection of sites to settle, which is harmful to recruitment success. Additionally, the study looks at the OA-induced metabolic stress, where the larvae are expected to expend higher energy to maintain homeostasis at the expense of growth and immunity. By focusing on this issue, the paper outlines the OA’s impacts on the shellfish populations and industries. The paper also looks at the available soft measures, such as the implementation of buffering solutions to limit the acidification in hatcheries, the use of genetic selection to incorporate acidification-resistant traits, and coastal management measures to limit local sources of acidification. The paper also suggests some potential new ways to increase the resilience of shellfish stock, including more flexible adaptive aquaculture practices. With commercial shellfish interests emerging, this paper fills some of the more critical gaps in the existing literature and offers insight into the impact of OA on the sustainability of the shellfish industry. It also provides OA mitigation strategies to preserve shellfish stocks in a changing climate.
Continue reading ‘Ocean acidification effects on larval development and survival in commercially important shellfish’Environmental, phylogenetic, and palaeogeographic impact on relative septal thickness in Devonian ammonoids from Morocco
Published 3 June 2026 Science ClosedTags: biological response, BRcommunity, laboratory, mollusks, paleo, physiology
Building upon previous research, this study examines potential relationships between septal thickness in Devonian ammonoids from the Anti-Atlas of Morocco and isotopic proxy data from the literature for atmospheric CO2, sea surface temperature, oceanic pH, and weathering (δ18O, δ13C, δ11B, 87Sr/86Sr). Recent studies have demonstrated that various mollusc groups show some growth sensitive to environmental factors. Our results indicate no significant correlation between septal thickness and the examined proxies, except for significantly thinner septa in the genus Phoenixites following the environmental perturbations during the Kellwasser Event, which included anoxic conditions and possibly ocean acidification. This supports the hypothesis that a positive selection for reduced shell material occurred in response to changing seawater chemistry. Additionally, our results align with published data and may support a correlation between septal thickness and palaeolatitude. This study contributes to our understanding of the evolutionary impacts of environmental stressors such as ocean acidification on ammonoids and their adaptive strategies to changing environmental conditions.
Continue reading ‘Environmental, phylogenetic, and palaeogeographic impact on relative septal thickness in Devonian ammonoids from Morocco’Feeding and excreting ecology in coastal systems
Published 26 May 2026 Science ClosedTags: biological response, community composition, growth, laboratory, mollusks, morphology, mortality, otherprocess, performance, physiology
Oysters (Crassostrea virginica) are critical foundation species in estuaries, providing numerous ecological and economic benefits. However, oyster populations have diminished worldwide. Effective oyster restoration and aquaculture require a mechanistic understanding of the physiological and environmental factors that govern oyster feeding, growth, and resilience under changing coastal conditions. We investigated how oyster ploidy and environmental conditions influenced oyster feeding and investigated how changes in abiotic conditions affected behavioral performance of oyster drills (Stramonita spp.), a key oyster predator. To better understand feeding responses and behaviors of both predator and prey we 1) used in-situ filter feeding assays to determine feeding differences existed amongst diploid and triploid oysters, 2) gathered a baseline for growth and in-situ feeding rates of oysters across Mississippi Sound in the Northern Gulf in the Spring, Summer, and Fall, 3) simulated present-day and projected future pH conditions (7.0-8.8) to analyze oyster feeding responses, and 4) introduced oyster drills to acidified conditions (7.0-8.8) to monitor behavior and foraging rates. Diploid oysters exhibited higher overall feeding rates, yet equivalent absorption efficiency between ploidies demonstrates a difference in energy allocation which might be the key to triploids’ ability to grow quickly. These findings highlight the role of intrinsic genetic and physiological traits in shaping oyster performance and provide a baseline for interpreting responses to environmental variability. Across spatial and seasonal variation in oyster in-situ feeding and growth across three contrasting sites in Mobile Bay and Mississippi Sound, in the Northern Gulf on the western border of Alabama and Mississippi, results revealed strong spatial and seasonal variability in feeding and growth. This was driven primarily by seston composition and salinity. Under present-day and projected future ocean acidification conditions, overall oyster feeding rates declined with lower pH’s, absorption efficiency remained stable, suggesting partial physiological compensation. These results indicate that pH can impose sublethal constraints on energy acquisition and growth, with individual variability at extreme pH highlighting potential acclimation or tolerance thresholds. When subjecting the oyster’s predator, the oyster drill, to similar pH conditions (7.0-8.8) experimental results indicate that decreased pH may increase drill foraging times. Behaviors like inactivity and climbing out of the water indicate a stress response under both high and low pH, demonstrating the complexity of predicting predator-prey outcomes under more acidic conditions. Collectively, these chapters demonstrate that oyster feeding, growth, and survival are shaped by both intrinsic traits, such as ploidy, and extrinsic factors including environmental variability and ocean acidification. Understanding the interplay between physiological plasticity, seston quality, and predator-prey interactions is essential for informing restoration and aquaculture strategies that sustain ecological function and the ecosystem services oysters provide.
Continue reading ‘Feeding and excreting ecology in coastal systems’Immunosuppression and gill damage of acidification and hypoxia on the Pacific oyster Magallana gigas
Published 22 May 2026 Science ClosedTags: biological response, laboratory, mollusks, mortality, physiology
Highlights
- Combined acidification and hypoxia trigger significant mortality in Magallana gigas.
- Seawater acidification suppresses the nonspecific immune response in Magallana gigas.
- Gill histopathology and immunosuppression are most pronounced with combined exposure.
Abstract
Rising atmospheric carbon dioxide leads to oxygen depletion and increased acidification in marine areas worldwide. The combined effects of these two stressors on the health of commercially important bivalves have not been sufficiently studied. We experimentally studied the effects of water acidification in combination with normoxic and hypoxic conditions on the parameters of cellular immunity and the gills microstructure of the Magallana gigas. We evaluated the hemolymph cellular composition, the total number and phagocytosis capacity of hemocytes, and also evaluated the histopathology of oyster gills during an 8-day experimental period. The oysters were exposed to low pH conditions (7.3), either under normoxic conditions (dissolved oxygen concentration of 8.0 mg/L) or hypoxic conditions (dissolved oxygen concentration of 2.0 mg/L). The parameters were assessed at days 1, 3, 6, and 8 of the experiment. It was shown that acidification of the aquatic environment causes significant suppression of oyster immunity in both normoxia and hypoxia, leading to a decrease in phagocytic capacity and ROS production by hemocytes. The combined effect of these factors increased the negative impact, ultimately leading to the oyster death at the end of the experiment. In addition, the effects of acidification caused serious and progressive histopathological damage to the oyster gills, while the most severe and frequent pathologies, such as almost complete expansion of the water chambers and severe dilation of the hemal sinuses, were caused by the combined effects of acidification and hypoxia. Therefore, the synergistic impact of acidification and hypoxia poses a substantial threat to oyster health.
Continue reading ‘Immunosuppression and gill damage of acidification and hypoxia on the Pacific oyster Magallana gigas’Genome-wide identification and expression analysis of calmodulin and calmodulin-like (CaM and CML) gene family in Magallana gigas
Published 21 May 2026 Science ClosedTags: biological response, laboratory, molecular biology, mollusks
Highlights
- 7 CaM family members and 55 CML family members were identified in Magallana gigas.
- MgCaM and MgCML genes showed tissue-specific and developmental stage-specific expression patterns.
- Distinct expression patterns emerged under heat and acidification stresses.
Abstract
Ca2+ is a multifunctional second messenger that can regulate the activities of hormones and environmental signals related to biotic and abiotic stresses, playing a role in a wide range of cellular processes and influencing almost all aspects of life. In organisms, calmodulin (CaM) and calmodulin-like proteins (CML) can sense and decode the regulatory signals of Ca2+ through the EF-hand (a helix-loop-helix structure) domain. In this study, 7 CaM family members and 55 CML family members were identified in Magallana gigas. All MgCaM and MgCML genes distributed unevenly on 7 chromosomes, with 90% of the genes located on chromosomes 6 and 5. Furthermore, the expression of MgCaMs and MgCMLs was tissue-specific in M. gigas, and most of the genes expressed highly in gill, labial palp, adductor muscle and female gonad. Through the analysis of transcriptome data, it was found that the MgCaM and MgCML genes showed specific expression patterns in response to abiotic stress. When encountering heat-shock stress, different genes responded at different time points. In response to acidification stimulation, genes in the outer edge of mantle could respond to the stimulus obviously. The expression patterns of five representative genes were validated by RT-qPCR under acidification. This study systematically analyzed the characteristics of oyster CaM and CML gene families, revealing their crucial roles in the environmental adaptation mechanisms of M. gigas.
Continue reading ‘Genome-wide identification and expression analysis of calmodulin and calmodulin-like (CaM and CML) gene family in Magallana gigas’Genome-wide characterization of the Pacific oyster Crassostrea gigas SLC4 gene family and expression profiles in response to acidification
Published 20 May 2026 Science ClosedTags: biological response, laboratory, molecular biology, mollusks, reproduction
Highlights
- Eight CgSLC4 genes family members were identified.
- CgSLC4s exhibited tissue-specific and developmentally variable expression patterns.
- CgSLC4 gene family responds to acidification stress in different mantle folds.
- CgSLC4A10-1 shows marked acidification responsiveness, especially in mantle epithelium cell.
Abstract
The solute carrier 4 (SLC4) family represents a category of integral membrane transporters responsible for bicarbonate mediation, which is vital for numerous fundamental biological functions. In this study, eight SLC4 genes were identified and annotated in Crassostrea gigas genome, comprising one member of Cl−/HCO3− exchanger, five genes coding Na+-dependent HCO3− transporters, and two Na+-coupled borate transporter copies, which were located on three chromosomes. In general, the expression of CgSLC4s showed tissue specificity, and differential expression patterns of CgSLC4s was observed at different developmental stages. The CgSLC4 family genes displayed divergent responses to acidification across different mantle folds. Among these family members, CgSLC4A10-1 exhibited the most dramatic and statistically significant expression changes in response to acidification across mantle folds, with fold changes ranging from 0.008-fold down-regulation to 85.95-fold up-regulation. According to the results of RT-qPCR and immunofluorescence, after 14 days of acidification treatment, CgSLC4A10-1 mRNA expression level was significantly increased, immunoblotting signal intensity was also enhanced in the epithelial cells. These results provide a general characterization of the SLC4 gene family in C. gigas, which may provide a systematic overview of the SLC4 gene family in C. gigas, and lay a foundation for future studies to explore its potential involvement in ion homeostasis and acidification adaptation in bivalve mollusks.
Continue reading ‘Genome-wide characterization of the Pacific oyster Crassostrea gigas SLC4 gene family and expression profiles in response to acidification’Impacts of coinciding ocean acidification and warming on the fatty acid profile of the pteropod Limacina helicina within the Northeast Pacific coastal region
Published 19 May 2026 Science ClosedTags: biological response, laboratory, mollusks, mortality, North Pacific, physiology
Under global climate change, co-occurrence of ocean acidification (OA) and warming poses a substantial threat to marine ecosystems. The present study focused on the Strait of Georgia within the Northeast Pacific region, where conditions of aragonite undersaturation exist year-round across the majority of the water column, with further intensification expected under OA. These conditions coincide with persistent rises in mean seasonal seawater temperatures and increased prevalence of acute stressor events, such as marine heatwaves and low-pH upwelling events. Limacina helicina, a pteropod species well-represented within the region’s zooplankton communities, is susceptible to OA and warming, with documented impacts including altered shell development, growth, and survival. To date, however, there has been minimal investigation into the effects of OA and warming on the species’ fatty acid profile under regionally-relevant conditions, thereby contributing to a lack of understanding of how impacts at lower trophic levels may relay across ecosystems. To address this knowledge gap, we examined the survival and fatty acid profile of L. helicina under future conditions via a laboratory experiment during which pteropods were exposed to singular and coinciding warming (mean summer seawater temperature + 4 °C) and OA (Ωarag < 1) conditions, with fatty acid analyses carried out via gas chromatography at 48-h and 5-d timepoints. OA conditions significantly altered fatty acid proportions at 48 h, and there was an additional interactive effect of OA and warming. Temperature significantly affected survival at 5 d, although experimental starvation conditions likely confounded this result. Additionally, fatty acid analyses of L. helicina picked from historical plankton samples collected in the region over 2014–2023 were carried out to examine time-series changes in fatty acid profiles in relation to temperature records. Results indicated no significant differences in fatty acid fractions among years, though there was suggestion of a changing proportion of myristic acid over a number of year groups. Overall, findings suggest that short-term OA conditions may result in altered fatty acid composition in pteropods, potentially leading to shifts in nutritional quality and associated impacts on trophic energy transfer.
Continue reading ‘Impacts of coinciding ocean acidification and warming on the fatty acid profile of the pteropod Limacina helicina within the Northeast Pacific coastal region’
