The relationship between invertebrates and Symbiodiniaceae dinoflagellates is the ecological foundation of diverse and productive coral reef ecosystems. Climate change-induced breakdown of this partnership, i.e., bleaching, is repeatedly driving widespread reef degradation. Thus, the future trajectory of this ecosystem depends on the reproduction and dispersal capacity of invertebrate-Symbiodiniaceae symbiosis. This review examines how climate change affects the biology of larvae from three invertebrate phyla—Porifera, Cnidaria, and Mollusca—that host Symbiodiniaceae, focusing on differences in symbiont transmission mode, symbiont location, and the larvae´s reliance on these associations. Due to limited research on Porifera and Mollusca hosts, most knowledge of larvae-Symbiodiniaceae associations stems from coral larvae patterns. The myriads of combinations of genetic and ecophysiologically distinct hosts and symbionts result in highly context-dependent responses to warming, but symbiotic larvae tend to be more susceptible to oxidative stress and show higher mortality than aposymbiotic larvae. While ocean acidification has little direct effect on the algal symbionts, it impacts larvae variably, especially calcifying larvae (e.g., mollusks), which suffer from impaired calcification and higher mortality. Climate change also impairs the reproductive processes of Symbiodiniaceae-bearing invertebrates, reducing gamete output, causing asynchronous spawning, and lowering larval survival. These effects will result in a persistent decline in recruitment with increased larval retention, consequently reducing reef connectivity and genetic diversity, thus weakening ecosystem resilience. This underscores the urgent need to hasten knowledge on larval ecology under climate change and the functional role of symbionts to better inform marine conservation planning and to incorporate larval ecology in the future predictions.
Continue reading ‘The larva-Symbiodiniaceae association at risk: putative impacts of climate change on reproduction, dispersal, and recruitment in coral reefs’Posts Tagged 'mollusks'
The larva-Symbiodiniaceae association at risk: putative impacts of climate change on reproduction, dispersal, and recruitment in coral reefs
Published 24 November 2025 Science ClosedTags: biological response, BRcommunity, cnidaria, corals, mollusks, physiology, phytoplankton, porifera, reproduction, review
A synthesis of Eastern oyster (Crassostrea virginica) growth and calcification responses under changing environmental conditions
Published 21 November 2025 Science ClosedTags: biological response, calcification, mollusks, morphology, North Atlantic, review
Eastern oysters (Crassostrea virginica) are foundational reef builders and ecosystem engineers that provide habitat complexity, enhance biodiversity, and influence biogeochemical cycles by shifting local carbonate chemistry in estuaries along the U.S. Atlantic coast and Gulf of Mexico. However, the environmental ranges governing oyster shell growth and calcification rates remain poorly constrained because available studies vary in the metrics quantified, experimental settings, and spatial coverage. We synthesized existing literature on C. virginica growth and calcification, assessing directional responses to changing environmental conditions. Variability in ecological, spatial, and temporal scales among studies and disparities between laboratory and field-based measurements complicate direct comparisons. Despite heterogeneity in the synthesized data, consistent patterns emerged; shell growth limitations were common at salinities below ~ 12 in U.S. Gulf of Mexico populations, and calcification declines were frequently observed under acidified conditions (pH < 7.7) in U.S. Atlantic populations. By summarizing patterns across life stages, regions, and study types, we highlight environmental stressors likely to impair oyster reef resilience and function. A more integrative research approach, incorporating both individual- and reef-scale processes across experimental and natural settings, is critical for refining predictions of oyster reef resilience. Standardized methodologies and interdisciplinary frameworks will enhance our ability to quantify the role of oyster reefs in carbon cycling and assess their response to future environmental stressors.
Continue reading ‘A synthesis of Eastern oyster (Crassostrea virginica) growth and calcification responses under changing environmental conditions’Impact of ocean acidification on the intestinal microflora of Sinonovacula constricta
Published 20 November 2025 Science ClosedTags: biological response, BRcommunity, community composition, laboratory, molecular biology, mollusks, North Pacific, otherprocess, prokaryotes
The intestinal microflora, which is vital for nutrient absorption and immune regulation, can experience dysbiosis under environmental stress, potentially enhancing host susceptibility to pathogenic invasion. The impact of ocean acidification on bivalves is substantial, but its effects on their intestinal microflora remain poorly understood. To explore the impact of ocean acidification on the intestinal microflora of Sinonovacula constricta, this study used high-throughput 16S rRNA sequencing technology to investigate the variations in the intestinal microflora communities of S. constricta during ocean acidification across different time points. After exposure to ocean acidification, changes in the composition of the intestinal microflora of S. constricta were observed, with no significant difference in α-diversity between the acidified and control groups. The abundance of Proteobacteria in the acidification group increased, whereas that of Cyanobacteria decreased. The abundance of Firmicutes initially decreased and then increased. At the genus level, the relative abundance of Pseudomonas was lower than that in the control group, whereas the relative abundance of Photobacterium, Acinetobacter, and Enterobacter gradually increased. LEfSe analysis identified Serpens as the discriminative biomarker at 7 days of acidification, Enterobacteriales, Rhodobacteraceae, and Martvita at 14 days of acidification, and Serpens, Acidibacteria, and Aeromonadaceae at 35 days of acidification. Functional prediction analysis indicated significant stimulation in various metabolic pathways at different time points following acidification stress. Specifically, pathways involved in biosynthesis were significantly stimulated at 14 days of acidification, while those related to sucrose degradation were disrupted at 35 days. The results further indicated that ocean acidification stress can influence the intestinal microflora of S. constricta, but no severe dysbiosis or digestive system impairment was observed at the microbial level. This study provides new insights into the effects of ocean acidification on the intestinal microflora of marine bivalves.
Continue reading ‘Impact of ocean acidification on the intestinal microflora of Sinonovacula constricta’The multiple responses of Mytilus galloprovincialis in the multi-stressor scenario: impacts of low pH, low dissolved oxygen, and microplastics
Published 18 November 2025 Science ClosedTags: biological response, laboratory, Mediterranean, mollusks, multiple factors, oxygen, physiology, plastics, respiration
Highlights
- Low pH, low dissolved oxygen (DO), and microplastics (MPs) did not notably affect organismal parameters or ETS activity.
- Stressors significantly affected hemocytes, genotoxicity, and gill metabolites individually and interactively.
- Hemolymph phagocytic activity, granulocyte/hyalinocyte ratio, and mantle lipid peroxidation were partly affected.
- Metabolomic analyses showed that mussel gills are valuable indicators of metabolic status under stress.
Abstract
Along with high temperatures, acidification, deoxygenation, and microplastics (MPs) pollution represent key drivers in coastal marine ecosystems. Sessile invertebrates living in coastal habitats are primarily exposed to the combination of these drivers, often at severe levels. Here, we investigated the individual and combined impacts of low pH (pHT: 7.35), low dissolved oxygen (DO) (1.91 mg L−1), and MP (26 μg L−1) in the Mediterranean mussel Mytilus galloprovincialis by measuring organismal and cellular parameters after a 15-day exposure period. Organismal parameters (respiration rate, ammonia excretion rate, absorption efficiency) as well as electron transport system (ETS) activity were not impacted by the stressors, either individually or combined. At the cellular level, however, we observed significant effects of these stressors individually and interactively on the hemocyte count, hemocyte viability, genotoxicity (comet assay), and gill metabolite profiles. In addition, we observed partial effects on the hemolymph phagocytic activity (PA) and granulocyte/hyalinocyte (G/H) ratio, and mantle lipid peroxidation (LPO). Metabolomics results manifested that the gill of mussels can serve as a valuable indicator of metabolic status under the stress of low pH, low DO and MP. Metabolites involved in osmoregulation, membrane stability, oxidative stress, energy, amino acid and nitrogen metabolism were significantly affected by the stressors, with low DO being the main driver of metabolic changes. We suggest that the individual and variable interactions of these stressors negatively impact M. galloprovincialis, except for the organismal and, to some extent, biochemical parameters.
Continue reading ‘The multiple responses of Mytilus galloprovincialis in the multi-stressor scenario: impacts of low pH, low dissolved oxygen, and microplastics’Environmental stressors interplay with top-down and bottom-up effects upon shell structure and function of an intertidal marine snail
Published 17 November 2025 Science ClosedTags: biological response, calcification, growth, laboratory, mesocosms, mollusks, morphology, multiple factors, physiology, predation, South Pacific, temperature
Highlights
- Environmental stressors affect shell properties varied across the trophic network.
- OA, OW and predator cues, reduced snail’s shell growth and calcification.
- OA and OW influenced shell structure and resistance more than predator risk.
- Food quality modulates periostracum organic content under OA and OW conditions.
- Biopolymer plasticity aids shell resistance, reducing climate stress vulnerability.
Abstract
Mollusc gastropods have evolved complex shells to protect their soft tissues from biotic and abiotic stress, but the impact of biological and environmental interactions on shell properties is not well understood. This study assessed how the individual and combined effects of increased temperature and pCO2 affect the structural and functional properties in shells of the intertidal snail Tegula atra, considering predator risk from the crab Homalaspis plana and changes in the nutritional quality of its food source, the brown kelp Lessonia spicata. Ocean acidification (OA) and ocean warming (OW) significantly affected growth rate and calcification of snails, with greater impacts under predator risk (top-down) than food quality (bottom-up) influences. FTIR-ATR analyses of the organic composition of shell periostracum indicated that OA conditions increased total organic matter, while polysaccharides, and carbonate content signals showed complex interactive effects under OA and OW conditions, with minor predator cue effects, while the nutritional value of the food source alters polysaccharides and lipids signals. Functional properties (resistance) of the shell material were affected by OA, OW, and predator cues but not by food quality source. These findings provides a novel understanding of how interacting climate stressors and trophic dynamics shape the structural (biomineralization) and functional (biomechanical) resilience of intertidal gastropods.
Continue reading ‘Environmental stressors interplay with top-down and bottom-up effects upon shell structure and function of an intertidal marine snail’Sediment topography enhances the response of coral reef carbonate sediment dissolution to ocean acidification
Published 13 November 2025 Science ClosedTags: annelids, biological response, BRcommunity, calcification, chemistry, community composition, laboratory, mollusks, otherprocess, primary production, respiration, sediment
The interaction between water flow and sediment topography (e.g., surface ripples) in shallow, permeable coral reef carbonate sediments establishes pressure gradients that increase the rate of sediment–water solute exchange relative to water flow along a flat bottom. It is unknown how this effect from surface ripples may modify the rate at which the sediment porewater is exposed to future chemical changes in the overlying water column, such as elevated pCO2 that is causing ocean acidification (OA). To address this question, this study used a series of 22-h incubations in flume aquaria with live permeable calcium carbonate sediment communities and examined the interactive effect of pCO2 (400 and 1000 µatm) and surface topography (flat and rippled sediments) on invertebrate infaunal activity, carbonate sediment microbial metabolism, and inorganic carbonate dissolution. Results show that the introduction of oxygen into flat sediments was largely driven by infaunal activity, whereas introduction of oxygen into rippled sediments was largely driven by physical flow processes. Rippled sediments exhibited rates of respiration and gross primary production that were ~ 45% and ~ 50% higher, respectively, than flat sediments. An increase in pCO2 shifted the sediments in the flat flumes from net calcifying to net dissolving, an effect that was amplified an additional ~ 60% in rippled sediments. These results suggest that current estimates of coral reef carbonate sediment calcification may be underestimating the dissolution response to OA where the carbonate sediment environment exhibits ripples in the topography.
Continue reading ‘Sediment topography enhances the response of coral reef carbonate sediment dissolution to ocean acidification’Mothers know best: maternal signaling boosts larval resilience under ocean acidification conditions
Published 12 November 2025 Science ClosedTags: adaptation, biological response, fisheries, molecular biology, mollusks, morphology, mortality, otherprocess, physiology, reproduction
Highlights
- Environmental priming effectively rescued larval phenotype under OA conditions.
- Egg ‘omics were investigated to elucidate mechanism of priming across generations.
- Clam egg lipidomes were largely unperturbed by maternal low-pH exposure.
- Differentially expressed genes were identified in eggs of low-pH primed clams.
Abstract
Bivalve aquaculture is a growing sector worldwide, producing sustainable animal protein to meet growing demand from consumers. Yet, the industry remains vulnerable to environmental changes that can impact their product across life stages, especially at the larval stage. Parental priming, or the exposure of broodstock to adverse environmental conditions as they undergo gametogenesis, holds promise as a method to increase resilience in bivalve offspring. We exposed Manila clam (Ruditapes philippinarum) broodstock to low pH conditions (pH 7.4 for 78 days during gametogenesis). Larvae were produced from primed (low pH) and unprimed (ambient pH) broodstock and exposed to ambient or low pH conditions in a full factorial design. Larval phenotype in response to low pH was partially rescued by broodstock priming: larvae from low pH-exposed broodstock had better survival and growth than larvae from broodstock held under ambient conditions. Clam egg lipidomic and transcriptomic analyses were performed to determine the physiological differences associated with broodstock environmental conditions. Egg lipid abundance profiles were not significantly different between parental treatments. The egg transcriptome revealed 48 differentially expressed transcripts associated with parental environmental conditions. These genes are involved in important processes for early larval physiology, including metabolism, cell cycle, and transcriptional regulation. Broodstock clams were minimally impacted by their exposure to low pH for 78 days, however we show here that subtle maternal signals may contribute to the vastly improved larval performance observed under low pH conditions.
Continue reading ‘Mothers know best: maternal signaling boosts larval resilience under ocean acidification conditions’Impact of crustose coralline algae, ocean acidification, and ocean warming on larval pinto abalone settlement and juvenile survival
Published 11 November 2025 Science ClosedTags: algae, biological response, BRcommunity, communityMF, laboratory, mollusks, morphology, mortality, multiple factors, North Pacific, reproduction, temperature
Highlights
- Ocean acidification reduced pinto abalone settlement and survival in the hatchery.
- Ocean acidification is likely a greater threat than warming to Washington pinto abalone.
- Use of a natural settlement inducer improves abalone settlement and survival.
- Coralline algae may improve survival of pinto abalone under ocean acidification.
Abstract
Since 1994, Washington State (USA) has experienced a 97 % drop in the native pinto abalone population. Since 2007, conservation aquaculture initiatives have been underway to return the population to a self-sustaining level. Successful restoration, however, depends on both the ability to successfully raise juveniles in hatchery settings and the capacity of outplanted pinto abalone to survive and reproduce in the wild as threats of ocean acidification and warming continue to increase. Crustose coralline algae (CCA) can play an important role in restoration efforts by acting as natural inducers of larval settlement. Additionally, studies have shown that CCA can create a boundary layer with elevated pH, potentially providing a refuge for benthic species. We examined the settlement of pinto abalone under different environmental conditions (7.90 pH/14 °C (ambient), 7.90 pH/18 °C, 7.55 pH/14 °C; and 7.55 pH/18 °C) using two substrates: CCA-covered rocks and clean rocks with GABA (a chemical settlement inducer). Low pH negatively impacted larval settlement. Though settlement was higher with CCA than with GABA, this difference was not statistically significant. Juvenile survival was negatively impacted by low pH, but positively impacted by CCA presence, demonstrating the potential of CCA to increase juvenile pinto abalone survival and ameliorate the negative effects of low pH. Using CCA in hatchery culture and selecting sites with CCA cover for pinto abalone outplants may improve the efficiency of restoration in Washington.
Continue reading ‘Impact of crustose coralline algae, ocean acidification, and ocean warming on larval pinto abalone settlement and juvenile survival’Effects of ocean acidification on fatty acid composition in the Antarctic snail Neobuccinum eatoni
Published 31 October 2025 Science ClosedTags: adaptation, Antarctic, biological response, laboratory, mollusks, otherprocess, physiology
Introduction: Ocean acidification (OA), resulting from the absorption of increasing atmospheric CO2 by the oceans, represents a major threat to marine organisms. Despite growing concern, the biochemical responses of Antarctic species to OA remain poorly understood.
Methods: This study investigated the impact of OA (pH 7.70 ± 0.09) on the fatty acid (FA) composition of the Antarctic snail Neobuccinum eatoni over a two-month experimental period (December 2015–March 2016). Fatty acid profiles were analyzed in multiple tissues to assess potential alterations induced by low-pH (LpH) conditions.
Results: Significant tissue-specific changes in FA composition were detected, particularly in the mantle and gill. Under LpH exposure, notable modifications occurred in long-chain polyunsaturated fatty acids (LC-PUFAs) such as 22:5n-3, 22:6n-3, and 24:5n-6. Elevated LC-PUFA levels in the mantle suggested a compensatory response to oxidative stress, while shifts in the n-3/n-6 ratios in the gill pointed to potential alterations in immune and anti-inflammatory functions.
Discussion: Indicators of homeoviscous adaptation (HVA), including PUFA/SFA ratios and mean chain length (MCL), revealed biochemical strategies used by N. eatoni to maintain membrane fluidity under acidified conditions. This study provides the first evidence of FA-based responses to elevated pCO₂ in an Antarctic gastropod, highlighting the potential of fatty acids as sensitive biomarkers of physiological adaptation to environmental stressors.
Continue reading ‘Effects of ocean acidification on fatty acid composition in the Antarctic snail Neobuccinum eatoni’Calcifying plankton: from biomineralization to global change
Published 28 October 2025 Science ClosedTags: biological response, mollusks, physiology, phytoplankton, protists, review, zooplankton
BACKGROUND
The production and dissolution of calcium carbonate (CaCO3) is a key component of the ocean carbon cycle. In the open ocean, nearly all CaCO3 is produced by three groups of calcifying plankton: coccolithophores, foraminifers, and pteropods. These taxonomically and functionally diverse organisms play a major role in ocean biogeochemistry by modulating air-sea CO2 exchange, and facilitating the export of carbon and alkalinity to depth.
Despite their biogeochemical importance, these groups are typically considered separately, precluding an integrated understanding. Yet the pathways by which CaCO3 is produced and cycled through the ocean have important consequences for the carbon cycle and ecosystem functioning. Notably, none of the Earth system models included in the current Coupled Model Intercomparison Project (CMIP6) explicitly represents these groups of organisms. Here, we review the distinct functional traits of coccolithophores, foraminifers, and pteropods to elucidate how these traits shape their global distributions, vulnerabilities to climate change and acidification, and their role in modulating ocean chemistry and the Earth system.
ADVANCES
Recent advances in data compilation at multiple levels offer a comprehensive but still incomplete view of the CaCO3 cycle, from biomineralization up to the global ocean, with different traits leading to differing vulnerabilities to environmental change. For example, coccolithophores, as primary producers, are relatively less affected by changes in oxygen concentration compared with heterotrophs, but are particularly sensitive to ocean acidification because of the proton load generated during intracellular calcification, which requires effective pH regulation and proton expulsion. Differing resource requirements contribute to the geographic distributions of each group, while traits such as body size and turnover rate are fundamentally linked to global production, export, dissolution, and burial. Compiling these data allows us to compare the markedly different fates of the CaCO3 produced by each group, from surface production through export to eventual sediment burial. A major imbalance exists in the global CaCO3 cycling related to each calcifying plankton group, with key uncertainties, especially in rates of group-specific production and shallow biologically mediated dissolution. Current best estimates indicate that a large fraction of coccolithophore-derived CaCO3—the dominant source of CaCO3 in the ocean—is dissolved and recycled in the upper ocean. This underscores the central role of ecological processes such as predation, particle aggregation, and microbial respiration in shaping ocean carbonate chemistry.
We suggest that the overlooked process of shallow dissolution, mainly of coccolithophores, is also likely at play within the geological record of this group.
OUTLOOK
The three major groups of calcifying plankton play essential but distinct roles within ocean ecosystems and the marine carbon cycle. Their diverse traits govern global distributions, production, export, and their differing response to environmental change. The magnitude of biologically mediated CaCO3 dissolution in the upper ocean remains broadly unrecognized, with implications for both the global alkalinity budget and interpretations of the fossil record. Sediment cores provide a fossil record going back 65 million years, revealing large variation in organism size and diversity likely linked to changes in seawater carbonate chemistry (acidification) and warming. The extent to which shallow, selective dissolution has biased this record remains an important unresolved question. Addressing discrepancies between CaCO3 production and export from the upper ocean will require renewed focus on both quantifying and understanding the individual and combined contribution of these groups, as well as the biological processes driving shallow dissolution. These efforts are also critical for incorporating a mechanistically resolved CaCO3 cycle into future climate models, thereby supporting a more integrated view of ocean biogeochemistry under climate change.
Continue reading ‘Calcifying plankton: from biomineralization to global change’Depth-resolved vertical distribution of the pteropod Limacina helicina in the Northeast Pacific and its implications for exposure to ocean acidification
Published 27 October 2025 Science ClosedTags: abundance, biological response, BRcommunity, field, mollusks, North Pacific, otherprocess, performance, review, zooplankton
The pteropod Limacina helicina has become an important bioindicator for the impacts of ocean acidification on marine ecosystems, yet its vertical distribution and diel vertical migration (DVM) patterns remain poorly understood. Understanding these behaviours is critical to accurately predict the risks of ocean acidification to pteropods since the depth ranges they inhabit strongly influence their exposure to water corrosive to aragonite shells (i.e. ΩAr <1), given the natural vertical gradients in pH and ΩAr. To resolve the vertical distribution of L. helicina, we utilized an existing dataset consisting of 179 vertically stratified zooplankton net tows from the Northeast Pacific spanning 1983–2019. Using conventional observational analyses and Bayesian statistical models, we determine and compare the average day and night vertical distributions of two size ranges of L. helicina, plus those of the strong vertical migrator euphausiid Euphausia pacifica and a non-migratory control group of mollusc larvae. We show that the average day and night vertical distributions and mean depths of L. helicina do not differ and closely match those of the non-migratory control, indicating that L. helicina does not perform DVM in this region. Typical mean depths of L. helicina are ∼50–70 m, with ≥ 75% of the population occupying the upper ∼100 m, and ≥ 50% being found in the upper ∼50 m, regardless of body size and time of day. Given the typical shape of ΩAr profiles in the ocean, we estimate that pteropod exposure to low ΩAr may be overestimated if calculated using the standard vertically integrated approach (i.e. a homogeneous depth distribution) as opposed to our depth-resolved vertical distribution.
Continue reading ‘Depth-resolved vertical distribution of the pteropod Limacina helicina in the Northeast Pacific and its implications for exposure to ocean acidification’Seasonal and interannual variability of Atlantidae heteropods along the west coast of Baja California, Mexico
Published 23 October 2025 Science ClosedTags: biological response, chemistry, community composition, field, mollusks, North Pacific, otherprocess, zooplankton
Highlights
- Atlantid species richness was higher in winter than in spring.
- Maximum species diversity was associated with the 2013–2016 anomalous warm period.
- Distribution associated with seawater masses, hypoxia, and aragonite saturation.
- Atlantid species are potential biological indicators of environmental changes.
Abstract
The Atlantidae are holoplanktonic gastropods with aragonitic shells that inhabit the epipelagic habitat primarily in tropical and subtropical oceans, as well as in certain transitional and temperate regions, such as the California Current System. However, there is limited knowledge about how their diversity, distribution, and abundance respond to environmental changes over different time scales. The strongest seasonal changes of zooplankton species composition and environmental conditions in the southern California Current System occur between winter and spring. El Niño Southern Oscillation and marine heat waves are two additional environmental change drivers of interannual scale. Our aim was to infer the effect of the seasonal (winter-spring) and interannual (2012–2016) environmental variability on the diversity, distribution, and abundance of the Atlantidae species assemblage along the Pacific coast off the Baja California peninsula, Mexico. Atlantidae diversity was higher during winters than during springs. Their horizontal distribution recorded during winter was statistically correlated with temperature, salinity, and the seawater masses distribution, and during spring was correlated with the depth of hypoxic conditions (<60 μmol O2/kg oxyline) and the depth of Ω aragonite saturation horizon. Atlanta californiensis was the most abundant species, mainly during spring and its relative abundance decreased during anomalously warm periods, while tropical/subtropical species showed an opposite abundance pattern. The maximum species richness was associated with the 2013–2015 marine heat wave and El Niño 2015–2016 events, when tropical species were observed in the study area. Differences in the species community structure, their response to Ω aragonite undersaturated waters and hypoxia, and their seawater mass affinity showed that atlantids are useful biological indicators of environmental changes, ocean acidification, and deoxygenation conditions.
Continue reading ‘Seasonal and interannual variability of Atlantidae heteropods along the west coast of Baja California, Mexico’Dulse seaweed Devaleraea mollis mitigates effects of ocean acidification on larval Pacific oysters Magallana gigas
Published 21 October 2025 Science ClosedTags: algae, biological response, BRcommunity, chemistry, laboratory, mitigation, molecular biology, mollusks, morphology, North Pacific, reproduction
Ocean acidification (OA), driven by upwelling and climate change, can negatively impact the ecological and economic contribution of marine calcifiers along coasts worldwide. OA interferes with calcification, particularly in early life stages, causing mortality, reduced growth, and morphological abnormalities in shellfish such as the Pacific oyster (Magallana gigas). This issue is gaining traction as climate change intensifies, placing shellfish in wild populations and farms alike at risk. Macroalgal photosynthesis by seaweed such as Pacific dulse (Devaleraea mollis) has been proposed to provide small-scale OA refuges, but few controlled experiments quantify this effect, and none have focused on larval shellfish. This study examines the potential for Pacific dulse to mitigate OA and its effects on Pacific oyster larvae. Under continuous light for 23 days, the presence of dulse resulted in a consistent increase in seawater aragonite saturation state by 0.1-0.9, and pH by 0.1-0.5 units, depending on OA condition. Newly fertilized oysters were reared for 48 hours in the absence or presence of dulse under treatments corresponding to ambient (pH 7.8, 450 μatm CO₂), future OA (pH 7.6, 800 μatm CO₂), and future OA + upwelling (pH 7.4, 1200 μatm CO₂) seawater conditions. Dulse fully mitigated OA effects on larval size that ranged from decreases of 5% to 10%. Under the future OA + upwelling treatment, dulse presence reduced the odds of underdeveloped oyster larvae at 14 hours post fertilization (hpf), and larvae with hinge abnormalities at 24 hpf, by over 50%. Dulse induced minor changes to immune response gene expression at 48 hpf. These findings highlight the benefits of seaweed when adjacent to organisms sensitive to OA. These findings will be particularly useful for shellfish farms, habitat restoration efforts, and ocean stewardship practices as a potential mitigation strategy under the changing climate.
Continue reading ‘Dulse seaweed Devaleraea mollis mitigates effects of ocean acidification on larval Pacific oysters Magallana gigas’Physiological and metabolic plasticity in Patella caerulea enables survival in the CO2 vent systems of the Castello Aragonese (Ischia Island)
Published 20 October 2025 Science ClosedTags: adaptation, biological response, field, Mediterranean, mollusks, otherprocess, physiology, respiration, vents
Highlights:
- OA induced physiological and metabolic adjustment in P. caerulea to allow survival
- Increased RR at low pH only during summer to potentially boost energy production
- Reduced ER at low pH during summer and transplant to preserve more energy resources
- Induction of carnitine metabolism to produce more energy in low pH
- Increase of osmoregulation, oxidative stress, and nucleic acid metabolites at low pH
Abstract
Ocean acidification (OA) represents a major threat to marine ecosystems, causing detrimental effects mainly on calcifying organisms. However, the limpet Patella caerulea is one of the few calcifiers that can inhabit the naturally acidified areas of the Castello Aragonese vent systems (Ischia Island, Italy). Its presence suggests that this species may have developed tolerance or adaptive strategies to cope with OA.
Nevertheless, the specific biological mechanisms remain largely unknown. To address this gap of knowledge, in our study we conducted physiological and metabolomics analyses on resident limpet populations collected along the acidification gradient of the Castello vent systems. Additionally, we investigated the same mechanisms in specimens transplanted for 30 days from ambient pH conditions to the different pH sites of the vent.
Only during summer, OA increased respiration rates in limpets from the most acidified site and, simultaneously, reduced excretion rates and likely protein catabolism, probably to preserve more energy resources while coping with this environmental stress. Furthermore, the individuals up-regulated carnitine metabolism, potentially enhancing energy production through β-oxidation, and several metabolites involved in osmoregulation, oxidative stress, and nucleic acid mechanisms. Similar results were obtained also in limpets transplanted to low pH sites.
Overall, our results suggest that limpets exposed to acidified conditions may have developed tolerance strategies to maintain energetic reserves and allocate them among metabolic processes, which are fundamental in maintaining biological and ecological traits and distribution when facing environmental disturbance such as OA.
Continue reading ‘Physiological and metabolic plasticity in Patella caerulea enables survival in the CO2 vent systems of the Castello Aragonese (Ischia Island)’Low pH does not impact reproductive success but leads to negative carry-over effects between parents and larvae in a Mediterranean gastropod
Published 15 October 2025 Science ClosedTags: biological response, laboratory, Mediterranean, mollusks, morphology, reproduction
Understanding how marine organisms respond to ocean acidification across all life stages is essential for assessing the future resilience of ecosystems. We investigated the effects of long-term exposure to low pH conditions (pHT ranging from 7.95 to 7.22) on the reproductive traits and intracapsular development of Hexaplex trunculus, a predatory Mediterranean gastropod. Spawning success, fecundity, and capsule morphology were not affected by pH. However, larval development was significantly impaired at pHT lower than 7.51, with observed delayed development and fewer larvae developing successfully to the hatchling stage. Cross-transplantation of spawns between pHs indicated a negative carryover effect of parental exposure to low pH on larval development, although this was partially reversible when spawns were transferred back to the ambient pH. Notably, we observed inter-individual variability in larval growth, suggesting that phenotypic plasticity or genotype-specific tolerance may play a role in moderating sensitivity to future ocean acidification. Our study highlights the importance of considering parental exposure, natural pH variability, and within-population variation when assessing species responses to global drivers
Continue reading ‘Low pH does not impact reproductive success but leads to negative carry-over effects between parents and larvae in a Mediterranean gastropod’Impact of ocean acidification on the biology of marine bivalves
Published 14 October 2025 Science ClosedTags: biological response, mitigation, mollusks, physiology, reproduction, review
Ocean acidification, resulting from increased atmospheric CO₂ levels, poses a significant threat to marine ecosystems, particularly to shell-forming organisms such as marine bivalves. This review synthesizes current knowledge regarding the impacts of ocean acidification on bivalves, including oysters, clams, and mussels, focusing on their physiology, development, and ecological interactions. Acidification impairs shell formation, disrupts energy metabolism, alters feeding and respiration patterns, and inhibits the growth and recruitment of larvae. These changes can destabilize bivalve populations and impair the ecosystem services they offer, such as water filtration, habitat creation, and support for fisheries and aquaculture. The report discusses potential strategies to mitigate the impacts of climate change, including the reduction of carbon emissions, selective breeding, and habitat management. This underscores the necessity of interdisciplinary research to comprehend the long-term impacts of climate change and to promote sustainable resource management that benefits the environment.
Continue reading ‘Impact of ocean acidification on the biology of marine bivalves’Identification of chitinase family members in the Crassostrea gigas and the expression patterns of Cgamcase-1 under ocean acidification
Published 14 October 2025 Science ClosedTags: biological response, laboratory, molecular biology, mollusks, morphology, reproduction
Chitinase, as a crucial enzyme for the degradation of chitin, is involved in the construction of the chitin framework during the process of shell formation. In order to identify the members of the chitinase gene family in Crassostrea gigas and investigate their response to acidification, bioinformatic methods were employed to identify the chitinase family members and analyze their expression patterns. Eleven members of the chitinase family were identified from the C. gigas genome. All gene members contained the Glyco-18 domain, and some genes also contained the chitin-binding domain ChtBD2. These genes were predominantly located on chromosome 2, 5, 6, and 7. In the C. gigas, the chitinase family genes were clearly divided into two branches which were endochitinases and exochitinases. The chitinase family expressed across all developmental stages of the C. gigas larvae. With the development of larva, the expression level of five genes increased gradually. The expression levels of most chitinase family genes were higher in the mantle compared to other tissues. The acidic mammalian chitinase (Cgamcase-1) exhibited high expression level in the mantle, with the highest expression level in the outer fold (OF). The expression patterns of Cgamcase-1 in response to acidification were analyzed. After 3, 7, and 14 days of acidification stress, the mRNA expression of Cgamcase-1 in the mantle was 3.010-fold (P < 0.05), 4.557-fold (P < 0.001) and 4.129-fold (P < 0.001) of that in the control group, respectively. After 7 days of acidification stress, the mRNA expression of Cgamcase–1 in OF was 3.598-fold of that in the control group (P < 0.05). In situ hybridization results revealed that the positive signals for the Cgamcase-1 probe were primarily concentrated in the epithelial cell region of the outer fold, and the intensity of the positive signals significantly increased after 7 days of acidification stress, while it significantly decreased after 14 and 28 days. The study suggested that chitinase family genes might be involved in the process of larval development and adult shell formation. Cgamcase-1 participated in chitin degradation and responding to ocean acidification. This research provided important theoretical evidence and reference for understanding the role of chitinase in the shell formation process of the C. gigas and their response mechanisms under ocean acidification.
Continue reading ‘Identification of chitinase family members in the Crassostrea gigas and the expression patterns of Cgamcase-1 under ocean acidification’Interactions of multiple abiotic stresses exacerbate mollusk diversity loss in a high-discharge coastal mangrove wetland
Published 9 October 2025 Science ClosedTags: biological response, chemistry, community composition, field, mollusks, North Pacific, otherprocess
Highlights
- A long-term study of mangrove water and mollusk diversity in Chinses Daya Bay
- Water temperature, chlorophyll-a, total nitrogen and phosphorus rise significantly
- Water pH, salinity, dissolved oxygen and mollusk diversity reduce greatly
- Long-term high emission cause multiple stressors and biodiversity loss
- Interactions between multi-water factors exacerbate mollusk diversity loss
Abstract
Coastal regions, as a hotspot region of biodiversity and the most densely populated areas in the world, are increasingly threatened by anthropogenic disturbances, including warming, acidification, eutrophication, salinity fluctuation, and oxygen loss. Although massive single-factor studies have revealed the ecological catastrophe caused by these impacts, how these impact stressors interact to endanger coastal biodiversity that is critical for ecosystem stability and human well-being is still poorly understood. To investigate whether and how water warming, acidification, eutrophication, salinity fluctuation and oxygen loss interact with each other to impact the mangrove mollusk diversity, a long-term study was conducted in the mangroves of Chinese Daya Bay from 1987–1993 to 2017–2021. We found that water temperature, chlorophyll-a, total nitrogen (TN) and total phosphorus (TP) increased significantly, while the water pH, salinity, dissolved oxygen (DO) and mollusk species richness decreased obviously, reflecting water warming, eutrophication, acidification, salinity fluctuation, oxygen loss and biodiversity loss occurred in the Daya Bay. The mangrove mollusk diversity had a significant response to the water warming, eutrophication, acidification, salinity fluctuation, oxygen loss (p < 0.001). The average incidences of mollusk diversity loss due to the changes in water pH, temperature, TP, TN, chlorophyll-a, salinity and DO were 47.11 %, 35.56 %, 35.53 %, 34.48 %, 34.22 %, 34.15 % and 33.05 %, respectively. Moreover, the average effect of interactions between any two water factors on the mollusk diversity was 0.998, which was 22.5 % larger than their single effect on biodiversity of 0.814. The findings suggest that interactions between global change stressors can exacerbate biodiversity loss in coastal wetlands. Quantifying those effects in terms of multi-factor interactions will contribute to the coastal management and restoration based upon combined evidence rather than a one-sided single perspective.
Continue reading ‘Interactions of multiple abiotic stresses exacerbate mollusk diversity loss in a high-discharge coastal mangrove wetland’A window into the effect of ocean acidification on molluscan larval shell development using a quantitative approach
Published 30 September 2025 Science ClosedTags: biological response, laboratory, molecular biology, mollusks, morphology, North Pacific, reproduction
Increasing atmospheric CO2 levels have led to decreased pH and calcium carbonate saturation (Ω) of seawater, a process referred to as ocean acidification. Ocean acidification is expected to reduce biomineralization by marine calcifiers, such as molluscs, and many studies have reported serious effects on molluscan shell development. However, it has not previously been possible to quantitatively compare these effects on tiny structures, such as larval shells, among and within species. We applied the measurement technique of micro-focus X-ray computed tomography (MXCT) to larval shells of the limpet Nipponacmea fuscoviridis to quantitatively trace the process of shell growth (shell thickness and shell density). Shell thickness and density significantly decreased in seawater with low Ω levels. Scanning electron microscopy (SEM) revealed that the surface structure of the shell in larvae cultured under low Ω was disturbed. Gene expression analysis showed that the development of shell-forming regions under low Ω was significantly reduced. MXCT analysis can quantify mineralization in tiny larval shells; in combination with other methods such as SEM and gene expression analysis, it can provide a novel perspective in the assessment of the impact and resilience of marine calcifiers to changes in the marine environment.
Continue reading ‘A window into the effect of ocean acidification on molluscan larval shell development using a quantitative approach’Using boron isotopes to examine calcification fluid pH changes in marine calcifiers under environmental change
Published 23 September 2025 Science ClosedTags: biological response, calcification, laboratory, light, mollusks, multiple factors, physiology, South Pacific, temperature
CO₂-driven ocean acidification (OA) decreases seawater pH and carbonate ion concentrations, which can impact the calcification and physiology of marine calcifiers. These organisms form calcium carbonate skeletons and shells from a specialized calcification fluid that is, to varying degrees, isolated from surrounding seawater. The carbonate structures serve as archives, preserving the chemical signature of the calcification fluid, which can be analyzed using geochemical proxies. In the following thesis, I examine how different taxa respond to future ocean changes by exposing them to predicted future acidification scenarios. Additionally, I aim to understand if an organism’s resilience to the impacts of ocean acidification is linked to their ability to regulate their calcification fluid chemistry using geochemical proxies.
In Chapter 1, I investigate the geochemistry of three reservoirs important for biomineralization – seawater, the extrapallial calcification fluid (EPF), and the shell – of two commercially important bivalve species: Crassostrea virginica and Arctica islandica to understand if the boron isotope proxy is probing calcification fluid pH. Additionally, I examined the effects of three ocean acidification conditions (ambient: 500 ppm, moderate: 900 ppm, and high: 2800 ppm CO2) on the calcification and chemistry of the calcification fluid of the same three reservoirs for C. virginica. Comparisons of seawater and extrapallial fluid geochemistry indicated that the EPF has a distinct composition that differs from seawater. Additionally, our OA experiments show that EPF chemistry is significantly affected by ocean acidification, demonstrating that the biological pathways regulating or storing these ions are impacted by ocean acidification. I also found that shell δ11B does not faithfully record seawater pH, but rather was correlated with EPF pH, despite an offset from in situ microelectrode pH measurements. However, the δ11B-calculated pH values were consistently higher than microelectrode pH measurements, indicating that the shell δ11B may reflect pH at a more localized site of calcification, rather than pH of the bulk EPF.
In Chapter 2, I investigate the effects of four different seawater pH levels (8.03, 7.93, 7.83, and 7.63) on seven complexes of temperate coralline algae collected from New Zealand. I examined the photophysiology, calcification, and geochemical proxies to probe the internal carbonate chemistry of seven different species of coralline algae under simulated end-of-century ocean acidification scenarios. Under ambient conditions we found clear physiological differences between branching and encrusting species. We found that OA treatments only had a significant effect on calcification of three of the seven species, Corallina berteroi, Corallina spp., and Jania “bottlebrush.” Additionally, OA only affected the calcification fluid pH (pHCF) of two species, decreasing pHCF for both Corallina beteroi and Jania “feather.” Nonetheless, for all species pHCF was constantly upregulated compared to seawater pH, indicating a strong control over calcifying fluid chemistry. My results underscore the high resilience of coralline algae calcification under the different end-of-century ocean acidification scenarios. This tolerance to OA is related to the species’ ability to maintain a stable carbonate chemistry to support calcification as seawater pH declined.
Continue reading ‘Using boron isotopes to examine calcification fluid pH changes in marine calcifiers under environmental change’
