Posts Tagged 'fisheries'

Drivers of biogenic acidification in oyster cultivation waters: macroalgal photosynthesis raises pH and carbonate saturation state, but not total alkalinity

Published 6 November 2026 Science Leave a Comment
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Highlights

  • Oyster respiration and calcification jointly deplete seawater alkalinity and buffering capacity.
  • High stocking density and low water exchange intensify biogenic acidification.
  • Biogenic acidification reduces short-term CO2 excretion and calcification rates in oysters.
  • Macroalgal photosynthesis raises pH and Ωcal but not the total alkalinity consumed by calcification.

Abstract

Biogenic acidification is a growing concern in large-scale bivalve aquaculture. To investigate its drivers and mitigation strategies, oysters were incubated in a continuous flow-through system with five chambers in series to simulate upstream-to-downstream water flow in a large-scale long-line oyster aquaculture system. Four stocking densities (1, 3, 6, and 9 ind. Chamber−1) and three water exchange rates (3.6, 5.4, and 7.2 L h−1) were tested. The mitigation potential of macroalgal photosynthesis was then evaluated. Results showed that biogenic acidification was observed in experimental waters and higher oyster stocking density intensified seawater acidification, with downstream chambers exhibiting more pronounced acidification than upstream chambers. Compared with the blank control, the terminal chamber at the highest density showed a pH decrease of 0.85 units, a pCO2 increase of 2698 μatm, and decreases in total alkalinity (TA) and TA − DIC of 333 and 349 μmol kg−1, respectively. Lower water exchange rate also exacerbated biogenic acidification. In the terminal chamber at the lowest water exchange rate, pH decreased by 0.52 units, pCO2 increased by 976 μatm, and TA and TA − DIC decreased by 140 and 188 μmol kg−1, respectively. Negative effects were observed: correlation analysis revealed a significant negative correlation between seawater pCO2 and the weight-specific CO2 excretion rate (P < 0.05), alongside a significant positive correlation between Ωcal and the weight-specific calcification rate (P < 0.05). Adding Ulva Lactuca L. to the acidified seawater progressively raised pH (7.75 to 8.06) and Ωcal (2.3 to 4.3) and lowered pCO2 (1306 to 585 μatm) over five days, approaching ambient levels, whereas TA remained at its post-acidification level despite a DIC drawdown of 133 μmol kg−1. CO2 removal therefore raises the pH and saturation -state caused by biogenic acidification but not the TA deficit, indicating that TA must be included when the mitigating effect of macroalgal photosynthesis is evaluated and that supplementary alkalinity sources may be required in large-scale bivalve aquaculture.

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A review: climate, contaminants and disease dynamics in lobster species Homarus americanus, Homarus gammarus and Jasus edwardsii

Published 5 November 2026 Science Leave a Comment
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Climate change, contaminant exposure, and emerging disease dynamics are increasingly recognized as interconnected stressors affecting marine crustaceans, including lobsters. This review compares three commercially and ecologically important species: Homarus americanus, Homarus gammarus, and Jasus edwardsii. Although these species differ taxonomically and ecologically, environmental stressors rarely act in isolation; climate change and contaminants interact to modify metabolic performance, molting, microbial dynamics and pathogen susceptibility. By synthesizing existing literature, this review identifies shared vulnerabilities and species-specific responses. Evidence suggests differences in thermal tolerance, developmental sensitivity and physiological plasticity, with early life stages consistently representing the most sensitive period across species. The American lobster has the strongest evidence linking warming waters to physiological stress and disease prevalence, particularly in Southern New England, whereas extensive research for European and Southern Rock lobsters remain limited. Across species, warming and ocean acidification often interact with contaminant exposure to alter immune function, molting, and recruitment. Key gaps remain in multi-stressor experiments, disease ecology and early life-stage research, emphasizing the need for integrative multi-stressor and cross-species frameworks to improve predictions of lobster resilience under accelerating environmental change.

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Climate-driven reproductive dysfunction in cultured fish and shellfish: endocrine mechanisms, consequences and adaptive strategies

Published 4 November 2026 Science Leave a Comment
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Climate change is altering the environmental conditions experienced by aquatic organisms through rising temperatures, marine heatwaves, hypoxia, salinity fluctuations, ocean acidification and more frequent extreme events. Although the effects of climate change on growth, survival and disease have received considerable attention, reproductive impairment may occur before substantial mortality and can directly threaten aquaculture seed production. Reproduction depends on the coordinated interaction of environmental cues, neuroendocrine pathways, gonadal function, gametogenesis and energy allocation, making it particularly sensitive to environmental instability. In fish, climate-related changes can affect the brain–pituitary–gonad axis, steroidogenesis, sex differentiation, gametogenesis, gamete quality and spawning. Temperature is especially important because it influences endocrine regulation throughout reproductive development, while hypoxia, salinity changes and ocean acidification can further modify endocrine, metabolic and cellular processes. In shellfish, environmental stress can affect gonadal development, gametogenesis, spawning, fertilisation and larval performance through mechanisms that differ from those operating in vertebrate fishes. Multiple climate-related stressors may also act simultaneously, producing additive, synergistic or antagonistic effects. Parental exposure can further influence offspring through maternal provisioning, paternal effects and epigenetic mechanisms. These processes have direct implications for broodstock conditioning, hatchery seed production and the sustainability of aquaculture. This review examines the links between climate-related environmental change, reproductive endocrine regulation and reproductive performance in cultured fish and shellfish, with emphasis on gamete quality, spawning, early development, multiple-stressor interactions and reproductive resilience. Environmental management, broodstock selection, nutrition, acclimation, selective breeding, biomarker-based monitoring and climate-resilient hatchery technologies are considered potential approaches for sustaining reproductive performance under future environmental conditions.

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Climate-driven coral reef change and socio-ecological resilience: a bibliometric and systematic review

Published 4 November 2026 Science Leave a Comment
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Purpose

This study examines the evolution of research on climate-driven coral reef change and socio-ecological resilience through an integrated bibliometric and systematic review of peer-reviewed literature published between 2002 and 2025. The study addresses the fragmentation of existing research across ecological, socio-economic and governance perspectives by synthesizing evidence on climate stressors, ecosystem services, human well-being, adaptation strategies and resilience. It aims to map publication trends, identify dominant thematic structures and provide a comprehensive evidence base to support policy development and sustainable management of coral reef ecosystems and reef-dependent coastal communities.

Design/methodology/approach

The study employed a combined bibliometric and systematic review approach following the PRISMA 2020 framework. A total of 588 peer-reviewed publications published between 2002 and 2025 were retrieved from the Scopus database after a structured screening process. Bibliometric analysis was conducted using Bibliometrix (R) and VOSviewer to examine publication trends, citation patterns, collaboration networks and thematic structures. The systematic review synthesized evidence on ecosystem services, human well-being, adaptation strategies and governance mechanisms, enabling an integrated assessment of climate-driven coral reef change and socio-ecological resilience.

Findings

The findings reveal a rapidly expanding and increasingly interdisciplinary research field, characterized by strong growth in scientific output and extensive international collaboration. Six major thematic clusters were identified, centering on climate stressors, coral biology, ecosystem services, adaptation, governance and resilience. The review shows that fisheries, tourism, biodiversity conservation and coastal protection are the most frequently discussed ecosystem services linking reef health to human well-being. Key adaptation pathways include ecosystem-based management, marine-protected areas (MPAs), participatory governance, restoration initiatives and livelihood diversification, all of which contribute to strengthening socio-ecological resilience under climate change.

Research limitations/implications

This study is limited to publications indexed in the Scopus database and restricted to English-language literature, which may have excluded relevant studies from other databases and regional sources. The findings provide a comprehensive understanding of the intellectual development of coral reef socio-ecological resilience research and highlight the need for greater integration of ecological, economic and governance perspectives. Future research should strengthen links between ecological indicators and socio-economic outcomes, particularly in underrepresented regions, to support more context-specific adaptation strategies and evidence-based coral reef management.

Practical implications

The findings provide valuable guidance for policymakers, marine resource managers and conservation practitioners seeking to enhance coral reef resilience under climate change. The study highlights the importance of integrating ecosystem-based management, MPAs, participatory governance and livelihood diversification into coral reef management frameworks. By demonstrating the strong link between reef ecosystem health and human well-being, the study supports the development of adaptation policies that simultaneously protect biodiversity, sustain ecosystem services, strengthen coastal livelihoods and improve the resilience of reef-dependent communities facing increasing climate-related risks.

Social implications

The study underscores the critical role of coral reefs in supporting food security, employment, income generation and coastal protection for millions of people in tropical coastal communities. By highlighting the social consequences of climate-driven reef degradation, the findings emphasize the need for inclusive adaptation strategies that reduce vulnerability and strengthen community resilience. The study also reinforces the importance of participatory governance and livelihood diversification in enhancing social well-being, promoting equitable resource management and improving the capacity of reef-dependent populations to adapt to climate-related environmental change.

Originality/value

This study contributes to the literature by integrating bibliometric analysis and systematic review methods to provide a comprehensive synthesis of climate-driven coral reef change and socio-ecological resilience research. Unlike previous reviews that focus primarily on ecological or social dimensions, it bridges ecological disturbance, ecosystem services, human well-being and governance perspectives within a single analytical framework. By mapping the intellectual structure of the field and identifying key adaptation pathways, the study offers novel insights into the interconnected nature of reef resilience and provides a valuable evidence base for future research, policy, and management.

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Time-variant bioeconomic risks on a gastropod fishery affected by uncertain ocean acidification trajectories

Published 3 November 2026 Science Leave a Comment
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Introduction: In the north-eastern Pacific, high-value abalone fisheries, which are sensitive to pH variations, require in situ pH data to properly assess the bioeconomic effects of their possible dynamic trajectories under alternative fishing mortalities.

Methods: In situ pH data were collected every 15 min using a HOBO® MX2501 sensor in the La Bocana pink abalone fishing grounds and compared them with Argo float and Copernicus Marine Service observations. The observed pH distribution was fitted to the Extreme Value Minimum distribution based on the Anderson–Darling goodness-of-fit statistic. Stochastic pH trajectories were generated through 10,000 Monte Carlo replications under three IPCC ocean acidification scenarios (SSP1-2.6, SSP2-4.5, and SSP5-8.5) and three fishing mortalities (FD = 0.02, 0.04, and 0.06). These trajectories were incorporated into a dynamic age-structured bioeconomic model by making individual growth and age-specific natural mortality functions dependent on pH. Biomass and resource rent per boat were projected from 2025 to 2100, and linear mixed-effects models, sensitivity analyses, and 95% confidence intervals were used to evaluate temporal responses and parameter uncertainty. Dynamic risks were estimated as the probability that biomass and resource rent fell below their respective limit reference points (LRPs: 190 t and USD 15,000 yr-1) across scenarios and fishing mortalities.

Results: The results indicate considerable variability in pH measurements between remote and in situ sources, which may introduce a proportional bias into the bioeconomic modeling if local observations are absent. Also, the effects of ocean acidification on H. corrugata biomass, survival, and fishery resource rent increase with time, IPCC pH scenario, and alternative exploitation intensity. Under the current exploitation rate (FMSY = 0.06), effects were negligible in the short term under SSP1-2.6, whereas by 2100 pH-related growth effects decreased by 4%, 13%, and 26% under SSP1-2.6, SSP2-4.5, and SSP5-8.5, respectively. Over the same period, pH effects on survival rates resulted in a slight increase of 2.14% under SSP1-2.6, but reductions of 6.48% and 22% under SSP2-4.5 and SSP5-8.5, respectively, while age-specific biomass peaks declined by up to 20% and 44% under SSP2-4.5 and SSP5-8.5. Mixed-effects models confirmed significant effects of pH scenario, exploitation rate, and time on biomass and resource rent, including significant interactions (all p < 0.001). By 2100, annual resource rent per small-scale boat was significantly higher under SSP1-2.6 than under SSP2-4.5 and SSP5-8.5 by USD 3,083 and USD 7,482, respectively (p < 0.0001). Under FMSY, the risk of biomass falling below its LRP was <25% during 2025–2040 but increased to 34% and 54% under SSP2-4.5 and SSP5-8.5, respectively, by 2100; corresponding risks for resource rent increased to 27% and 48%.

Discussion: These results indicate that ocean acidification may substantially increase the long-term bioeconomic vulnerability of the fishery, particularly under high-emission scenarios. Management actions to mitigate the undesired bioeconomic effects of OA will likely depend on the fishery authority’s risk attitude (i.e., degree of risk aversion) and corresponding exploitation-rate strategy selection.

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Long-term stress induced by low bicarbonate alkalinity causes intestinal oxidative stress, gut microbiota imbalance and metabolic disorder in Scylla paramamosain

Published 3 November 2026 Science Leave a Comment
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Highlights

  • Low bicarbonate induces acid-base imbalance and oxidative stress
  • Opportunistic pathogen Klebsiella is a potential biomarker of the LB group.
  • Low bicarbonate affects chitin synthesis and gut barrier.
  • Low bicarbonate affects NDAA and gut microbiota.

Abstract

To investigate the effects of low bicarbonate alkalinity on intestinal health of Scylla paramamosain, we systematically evaluated the growth survival, intestinal antioxidant enzyme activities, and expression profiles of genes involved in immunity, inflammation, apoptosis and osmoregulation under low alkalinity conditions. Meanwhile, integrated intestinal microbiome and metabolome analyses were performed. The results showed that low bicarbonate alkalinity significantly reduced the survival and molting rates of S. paramamosain. It markedly elevated the activities of intestinal SOD, CAT and GSH-Px, as well as the expression levels of inflammation-related genes (IL-16, RELISH, LITAF), apoptosis-related genes (CASPASE7, BAX, BCL2) and osmoregulation-related genes (NKA, NHE, Cl−/HCO₃−), while suppressing the expression of immune genes (proPO, ALF1, LZM) (P<0.05). Low bicarbonate alkalinity disrupted the intestinal microbiota structure of S. paramamosain, accompanied by a decreased abundance of the phylum Bacteroidota and a significant increase in the abundance of the genus Klebsiella (P<0.05). A total of 714 differential metabolites were identified by metabolomic analysis, which were mainly annotated into Fatty Acyls, Glycerophospholipids, and Steroids and steroid derivatives. Multiple carbohydrate metabolism pathways were significantly enriched and participated in the regulation of Fructose 6-Phosphate (F6P). Integrated microbiome-metabolome analysis revealed that N,N-dimethyl arachidonoyl amine (NDAA) may cooperate with intestinal microorganisms to regulate the stress tolerance of S. paramamosain under low bicarbonate alkalinity stress. Based on the physiological and biochemical characterization of the intestine, this study elucidated the adaptive characteristics of S. paramamosain under low bicarbonate alkalinity. The findings provide important theoretical basis and practical significance for the saline-alkaline aquaculture of S. paramamosain.

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Spat origin does not affect phenotypic plasticity in the farmed mussel Mytilus chilensis facing experimental acidification

Published 2 November 2026 Science Leave a Comment
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Phenotypic plasticity allows organisms to cope with environmental variability, yet its role in sustaining aquaculture systems in the face of global change stressors remains poorly understood. We conducted a 90-day mesocosm experiment to test whether spat origin influences morphological, physiological, and periostracum responses in the Chilean mussel Mytilus chilensis under sustained experimental acidified conditions. Juveniles were collected from two contrasting habitats: an estuarine and dynamic/fluctuating environment, strongly influenced by freshwater discharges, and a marine, more stable environment; and then exposed to two pH regimes (8.0 and 7.5). Morphological traits showed subtle origin effects: estuarine mussels tended to exhibit higher shell length and calcification rates, though origin × pH interactions were not significant. Physiological responses were largely similar between both seed sources, with metabolic rates remaining stable while the clearance rate increased under acidified conditions in both populations. Periostracum analyses revealed some non-significant variation in organic composition, but no consistent effects of the pH were detected. Together, these results suggest that M. chilensis relies on conservative metabolic maintenance combined with flexible clearance responses possibly to cope with natural acidification pulses, while also tolerating sustained low-pH conditions, with only weak signals of origin-driven divergence. Our findings highlight the importance of phenotypic adjustments over local origin, suggesting that spat provenance may not be a primary determinant of performance under projected acidification scenarios tested here.

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Critical swimming speed in fish: measurement, determinants, and applications in aquaculture and fisheries management

Published 2 November 2026 Science Leave a Comment
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Critical swimming speed (Ucrit) is widely used as a non-invasive and practical metric for quantifying swimming performance in fish. This review summarizes current advances in Ucrit research, focusing on measurement methods, environmental and biological determinants, and the underlying genetic and molecular mechanisms. We highlight key methodological developments, including step and ramp protocols, while addressing ongoing challenges such as the lack of standardized procedures and the limited comparability across studies. Environmental factors, including temperature, dissolved oxygen, salinity, and ocean acidification, strongly influence Ucrit, while intrinsic traits such as body size, sex, and physiological capacity further shape its variation. Recent studies have begun to uncover the genetic architecture of Ucrit, with evidence from heritability estimates, genome-wide association studies, and transcriptomic analyses pointing to a polygenic basis and a central role of energy metabolism and mitochondrial function. We further discuss the applications of Ucrit in aquaculture and fisheries management, including selective breeding, exercise training, fish passage design, and stock enhancement. Finally, we outline future research directions, emphasizing the need to establish standardized measurement frameworks, develop high-throughput phenotyping technologies integrated with artificial intelligence, and achieve multi-omics integration. Advancing these approaches will deepen our understanding of swimming performance and facilitate the development of more efficient and sustainable aquaculture, while promoting continued innovation in fisheries science.

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Green total factor productivity and ocean health: a global panel analysis of institutional, environmental and economic drivers

Published 2 November 2026 Science Leave a Comment
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The deterioration of ocean health has become a critical global challenge due to increasing pressures from economic activities, environmental degradation, and institutional weaknesses. This study examines the impacts of economic growth, capture fisheries production, greenhouse gas emissions, and government effectiveness on ocean health at the global level during the period 2012–2022, using the Ocean Health Index (OHI) as a multidimensional measure of marine sustainability. A quantitative research design based on panel data analysis is employed using secondary data collected from the Ocean Health Index database, the World Bank, and Our World in Data. Descriptive statistics, correlation analysis, panel unit root tests, multicollinearity diagnostics, and panel model specification tests are conducted, followed by fixed-effects estimation with country-clustered standard errors. An environmentally extended Solow-residual method is then employed to calculate the Green Total Factor Productivity (GTFP) growth and added to an extended model of ocean health. The results indicate that there is a positive and significant relationship between economic growth and ocean health, and a negative and significant relationship between government effectiveness and ocean health. Ocean health is statistically significant and negatively associated with the growth of GTFP, while both capture fisheries production and GHGs are statistically insignificant. The study demonstrates that ocean health is a multidimensional socio-ecological phenomenon shaped by the interaction of economic, environmental, institutional factors and productivity related aspects. These findings contribute to the literature by integrating economic, environmental, institutional and productivity related dimensions to provide a broader understanding of the factors associated with ocean health across countries.

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Current knowledge of marine crustaceans in Mauritius and their global importance in a changing climate

Published 30 October 2026 Science Leave a Comment
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Marine crustaceans are ecologically and socio-economically important components of coastal and marine ecosystems; however, in Mauritius, knowledge of their biodiversity, functional roles, and responses to climate change remains limited and fragmented. This narrative review synthesizes available information on Mauritian marine crustaceans, with particular emphasis on the class Malacostraca, while identifying key knowledge gaps and research priorities relevant to their ecological importance and climate-change vulnerability at both local and global scales. Although existing records document 61 crustacean families in Mauritius, these data are sparse, outdated, and largely based on historical surveys, highlighting the urgent need for updated inventories and long-term monitoring. Globally, marine crustaceans act as trophic intermediaries, ecosystem engineers, and scavengers, contributing to nutrient cycling, sediment dynamics, and habitat stability. They support fisheries, aquaculture, tourism, and cultural practices, and provide valuable bioresources such as chitin, chitosan, and other bioactive compounds with applications in regeneratiom engineering, medicine, agriculture, environmental remediation, and biotechnology. Trade patterns further emphasize their economic importance, revealing export-oriented dynamics in Mauritius, instead of local consumption, that result in a net reliance on imports. Climate change poses an escalating threat through ocean warming, acidification, and increasing environmental variability, affecting DNA repair, protein synthesis, haemolymph, metabolic performance, calcification, reproduction, immunity, behavior, and species interactions. These stressors are further compounded by habitat degradation, altered symbiotic interactions and food-web disruption. The scarcity of empirical studies from Mauritius underscores the need for integrative, multi-stressor, and long-term research to support effective conservation, fisheries management, and climate resilience.

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Navigating uncertainty in the Pacific Arctic region: toward adaptive fisheries management under climate change and ocean acidification impacts

Published 30 October 2026 Science Leave a Comment
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Fisheries management under climate change in the Pacific Arctic Region faces profound uncertainties, particularly concerning the trajectory of environmental drivers and the biological responses of fish species to ocean acidification (OA), which affect both stock productivity and spatial distributions. Here, we employed the Dynamic Bioclimate Envelope Model to project century-scale changes in abundance, maximum catch potential, and species distributions for key commercial fish under two climate scenarios (SSP1-2.6 and SSP5-8.5) and two alternative assumptions about OA responses, namely without OA effect and with OA effect parameterized as increases in basal metabolic rate and elevated larval mortality. Fishing mortality was treated as a management control variable, and the minimax regret criterion was applied to select the fishing mortality strategy that minimizes the worst-case loss in landed value relative to the scenario-specific optimal strategy across all climate and OA response scenarios. Results indicate strong regional heterogeneity: southern LMEs (East Bering Sea, West Bering Sea, and Aleutians) experienced persistent declines in abundance and maximum catch potential, with negative responses to OA further amplifying reductions, whereas the northern LME (Northern Bering–Chukchi Seas) exhibited substantial gains. These poleward shifts were accompanied by increased spatial aggregation, highlighting that species are not only shifting northward but also becoming more spatially concentrated within suitable habitats. Assessments that ignore OA effects risk overestimating long-term yields and exposing fisheries to productivity and revenue losses. Precautionary reductions in fishing mortality consistently minimized long-term regret across most species and LMEs. These findings highlight the critical interplay between climate change, OA effects, and management decisions, providing a scientific basis for adaptive fisheries management in the rapidly changing Pacific Arctic Region.

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How ocean acidification makes marine fish reproduction vulnerable: physiological mechanisms and ecosystem consequences

Published 29 October 2026 Science Leave a Comment
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Highlights

What are the main findings?

  • Ocean Acidification (OA) disrupts the HPG axis, reducing sex steroids and vitellogenesis.
  • OA impairs gamete quality, sperm motility, egg integrity, and Ca²⁺ signaling.
  • pH decline may weaken Dax1 repression of P450arom, but this remains unvalidated.
  • OA plus warming often worsens reproductive dysfunction; multigenerational recruitment effects are still unknown.

What is the implication of the main finding?

  • OA threatens fish recruitment, community structure, and fishery productivity/food security.
  • Long-term, multigenerational, multi-stressor field studies are needed for effective management.

Abstract

Ocean acidification, driven by the absorption of anthropogenic carbon dioxide into seawater, poses a significant threat to marine environments and biodiversity. This comprehensive review examines the specific impacts of acidification on the reproductive physiology of fish, integrating recent advances in our understanding of gonadal development, gametogenesis, and early embryonic development. We synthesize current findings on how altered carbonate chemistry disturbs the reproductive system from gametogenesis and fertilization to larval development and beyond. Our analysis reveals that ocean acidification affects multiple physiological pathways, including disruption of the hypothalamic–pituitary–gonadal (HPG) axis, impairment of calcium signaling, and alterations in sex hormone synthesis. We propose a mechanistic model in which pH reduction may weaken Dax1-mediated repression of P450arom transcription, thereby dysregulating aromatase activity and leading to sex hormone imbalance that impairs gonadal development; however, this proposed mechanism requires direct experimental validation under ocean acidification, as the net outcome may be modulated by additional regulatory layers such as epigenetic modifications and other transcription factors. Furthermore, we discuss the synergistic effects of ocean acidification with temperature elevation and other stressors, which often exacerbate reproductive dysfunction. This review concludes that no multi-generational study has yet evaluated HPG axis disruption to population-level recruitment failure, a critical gap for fishery resource assessment. We emphasize the critical importance of multi-generational and field-based studies to fully understand these impacts, which is essential for forecasting consequences for global marine biodiversity and the long-term sustainability of fisheries.

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

Published 23 October 2026 Science Closed
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Highlights

  • Interactive effects of warming and acidification tested in surfclams.
  • Growth, feeding, and metabolic rates measured after 6-week exposure.
  • Moderate acidification had limited effects under warming conditions.
  • Surfclams showed resilience to near-future ocean acidification.
  • Multi-stressor design improves ecological relevance of lab studies.

Abstract

Understanding marine organismal responses to co-occurring climate stressors is critical for predicting changes in ecosystems and commercial fisheries. The Atlantic surfclam supports a major commercial fishery in the Northeastern United States, where ocean warming and acidification are rapidly altering marine habitats. To evaluate how changing ocean conditions may affect bivalve physiology, surfclams were exposed to conditions reflective of ocean warming and acidification, respectively. One-year-old surfclams were exposed to nine conditions in a fully crossed design of temperature (ambient, +2 °C, and + 5 °C) and pH (7.88 ± 0.05, 7.76 ± 0.05, and 7.51 ± 0.07) for six weeks in a flow-through laboratory experiment using natural seawater. We quantified several physiological responses including growth, feeding, digestion, respiration rates, and shell weight and thickness to assess organismal performance across treatments.

Surfclams generally exhibited resistance to moderate ocean acidification across warming, but non-thermally stressful, temperatures. No effects of ocean acidification were observed on surfclam growth or respiration, although other physiological metrics (shell thickness and absorption rate) decreased with decreasing pH at some temperatures. These findings provide experimentally-derived insight into species-specific responses to interacting climate stressors. Further, the experimental design highlights the importance of integrating natural environmental variability into laboratory studies and studying multiple environmental stressors concurrently. This study contributes a basis for refining models of surfclam growth and distribution in potential future climate scenarios, with implications for sustainable fisheries management.

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

Published 21 October 2026 Science Closed
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Mollusc mariculture, a critical global source of high-quality protein, is increasingly threatened by seawater acidification. While climate-driven ocean acidification (OA) has been widely studied, intensive aquaculture systems face an additional, locally exacerbated phenomenon: biogenic acidification. In this review, we comprehensively compare biogenic acidification with OA and other seawater acidification types, highlighting its occurrence across various aquaculture systems and its capacity to induce conditions more corrosive than end-of-century OA projections under densely stocked settings. Driven by the respiration and calcification of high-density mollusc populations, biogenic acidification leads to distinct alterations in the carbonate chemistry of mollusc farming systems—notably a reduction in total alkalinity (TA)—that are mechanistically different from OA. We further discuss how biogenic acidification imposes stronger physiological stresses on molluscs, impairing calcification, growth, and energy allocation, and how it synergistically interacts with climate change. Finally, we propose practical mitigation strategies, including TA supplementation and integrated multi-trophic aquaculture, to enhance the resilience and sustainability of mollusc farming. This review underscores the necessity to address biogenic acidification as a distinct and ongoing challenge in global mariculture.

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

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

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

Published 8 October 2026 Science Closed
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Highlights

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

Abstract

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

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

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

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

Mitigation of biogenic acidification via increased total alkalinity in high stocking density culture waters of Strongylocentrotus intermedius: effects on growth and metabolism

Published 6 October 2026 Science Closed
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Highlights

  • Biogenic acidification increases with stocking density in sea urchin culture.
  • Total alkalinity mitigates acidification and promotes growth and gonadal development.
  • Higher alkalinity shifts metabolism toward biosynthesis and energy storage.

Abstract

Among cultured sea urchins in China, Strongylocentrotus intermedius has the highest annual production, with seed production and grow-out primarily conducted under high-density intensive conditions where biogenic acidification readily develops. To investigate its development, effects, and mitigation, we conducted a short-term incubation experiment (1 d) and a 20-day cultivation experiment. In the short-term incubation experiment, a control group with initial pH ≈ 8.1 and TA ≈ 2300 μmol/kg and a TA-elevated group with initial pH ≈ 8.1 and TA ≈ 3600 μmol/kg were established, and sea urchins were cultured across a density gradient of 20–80 g/3 L. In the 20-d experiment, stocking density was 88 g/3 L with the same initial pH and TA settings. The short-term experiment showed that seawater acidification occurred in the control group, and stocking density was significantly correlated to pCO2, ΔpH (pH reduction), TA–DIC, and Ωarag. With increasing stocking density, pCO2 increased significantly, whereas ΔpH and TA–DIC significantly decreased simultaneously. In the TA-elevated group, all parameters except pCO2 were higher than those in the control group across all stocking densities. At the lowest stocking density, ΔpH, TA–DIC, and Ωarag in the control group were −0.09 ± 0.01, 111.48 ± 1.73 μmol/kg, and 1.43 ± 0.00, respectively, whereas the corresponding values in the TA-elevated group were 0.11 ± 0.01, 252.26 ± 6.98 μmol/kg, and 3.23 ± 0.08. These results indicate that increasing TA mitigates biogenic acidification and works to strengthen the buffering capacity of the carbonate system. At the end of the 20-day cultivation experiment, urchins from the TA-elevated group showed significantly higher specific growth rate (1.60 ± 0.08% vs. 1.27 ± 0.06%), weight gain rate (37.72 ± 2.25% vs. 29.04 ± 1.48%), and gonad index (6.09 ± 1.58% vs. 3.54 ± 0.49%) than those from the control group. Metabolomics analysis revealed that TA elevation enriched pathways related to protein biosynthesis, glycerophospholipid metabolism, and sphingolipid signaling, with higher abundances of essential amino acids (L-methionine, DL-isoleucine), sphingomyelins, and the antioxidant indole-3-pyruvic acid. In contrast, the oxidative stress marker DL-2-aminoadipic acid was upregulated in the control group. Overall, increasing seawater TA mitigates biogenic acidification in high-density sea urchin culture, shifting metabolism from stress defense toward biosynthesis and reserve accumulation, thereby supporting growth and gonadal development in juvenile sea urchins.

Continue reading ‘Mitigation of biogenic acidification via increased total alkalinity in high stocking density culture waters of Strongylocentrotus intermedius: effects on growth and metabolism’

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

Published 5 October 2026 Science Closed
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Highlights

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

Abstract

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

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

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

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

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

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