Fecal bacteria (FB) contamination poses significant risks to shellfish safety and management in coastal and estuarine waters. Despite extensive pollution identification and correction efforts, FB contamination in shellfish-growing areas persists in the Salish Sea, highlighting the need to identify overlooked sources and better understand FB transport from riverine and shoreline inputs to shellfish beds. To address this, a high-resolution three-dimensional hydrodynamic model coupled with FB kinetics was developed and applied to a case study site in Salish Sea—Portage Bay—to simulate freshwater plume circulation, flushing dynamics, and bacterial transport. Daily FB loading from the major freshwater inflow—Nooksack River was generated by both linear interpolation and integrating a machine learning approach (XGBoost), trained on historical hydrological and meteorological data. The model successfully reproduced both the magnitude and seasonal variation of FB concentrations in Portage Bay for the year of 2021, demonstrating that simplified FB kinetics with first-order decay due to mortality was effective in this dynamic coastal environment with short flushing time. Model results identified the Nooksack River as the dominant far-field FB source, while scenario simulations showed that near-field coastal stormwater outfalls elevated local FB levels following rainfall, particularly under low-flow conditions. The XGBoost prediction provided comparable or superior accuracy to linear interpolation, particularly during periods of missing observational data, by capturing short-term variability and event-driven loading more effectively. Integrating data-driven riverine FB inputs with mechanistic coastal numerical modeling provides a robust framework for operational forecasting of shellfish bed exposure risk and supports adaptive monitoring and management of shellfish growing areas in the Salish Sea and similar coastal systems.
{"title":"Assessing shellfish water exposure to fecal bacteria pollution in Salish Sea: three-dimensional modeling and implications for monitoring","authors":"Wenfei Ni, Lakshitha Premathilake, Tarang Khangaonkar, Catherine Gockel","doi":"10.3389/fmars.2026.1738321","DOIUrl":"https://doi.org/10.3389/fmars.2026.1738321","url":null,"abstract":"Fecal bacteria (FB) contamination poses significant risks to shellfish safety and management in coastal and estuarine waters. Despite extensive pollution identification and correction efforts, FB contamination in shellfish-growing areas persists in the Salish Sea, highlighting the need to identify overlooked sources and better understand FB transport from riverine and shoreline inputs to shellfish beds. To address this, a high-resolution three-dimensional hydrodynamic model coupled with FB kinetics was developed and applied to a case study site in Salish Sea—Portage Bay—to simulate freshwater plume circulation, flushing dynamics, and bacterial transport. Daily FB loading from the major freshwater inflow—Nooksack River was generated by both linear interpolation and integrating a machine learning approach (XGBoost), trained on historical hydrological and meteorological data. The model successfully reproduced both the magnitude and seasonal variation of FB concentrations in Portage Bay for the year of 2021, demonstrating that simplified FB kinetics with first-order decay due to mortality was effective in this dynamic coastal environment with short flushing time. Model results identified the Nooksack River as the dominant far-field FB source, while scenario simulations showed that near-field coastal stormwater outfalls elevated local FB levels following rainfall, particularly under low-flow conditions. The XGBoost prediction provided comparable or superior accuracy to linear interpolation, particularly during periods of missing observational data, by capturing short-term variability and event-driven loading more effectively. Integrating data-driven riverine FB inputs with mechanistic coastal numerical modeling provides a robust framework for operational forecasting of shellfish bed exposure risk and supports adaptive monitoring and management of shellfish growing areas in the Salish Sea and similar coastal systems.","PeriodicalId":12479,"journal":{"name":"Frontiers in Marine Science","volume":"38 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147368196","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-05DOI: 10.3389/fmars.2026.1754952
Bairui Chen, Xuekai Lan, Bin Tian, Wenlong Tang, Jie Li, Dongli Deng
To address the insufficient retrieval accuracy of temperature and humidity profiles from ground-based microwave radiometers, this study develops an improved retrieval method based on intelligent optimization and attention mechanisms under clear-sky conditions. The research first constructs a brightness temperature dataset by performing forward modeling of ERA5 reanalysis data for the Haikou region using the MonoRTM model. Subsequently, five common machine learning algorithms—Ridge Regression, XGBoost, Multilayer Perceptron (MLP), Random Forest, and Support Vector Machine (SVM)—are employed to reconstruct atmospheric temperature and humidity profiles. A systematic evaluation of the retrieval results reveals distinct performance characteristics across the five machine learning models. For temperature retrieval, the Wolf Pack Algorithm (WPA) is introduced to optimize SVM parameters, resulting in a WPA-SVM model that reduces the overall Root Mean Square Error (RMSE) by 13.2% compared to conventional SVM. For humidity retrieval, an innovative MLP model integrated with an attention mechanism is proposed. By incorporating adaptive weighting and oversampling strategies, this model significantly improves retrieval accuracy at high altitudes, achieving a 15.1% reduction in overall RMSE compared to traditional MLP. The hybrid retrieval framework developed in this study integrates swarm intelligence and machine learning, under clear-sky conditions, providing a reliable technical pathway for high-precision and high-robustness atmospheric parameter retrieval. These findings not only hold significant value for advancing high-accuracy atmospheric parameter remote sensing systems, but also establish a foundation for precisely retrieving atmospheric refractivity profiles to resolve atmospheric ducts, thereby carrying important implications for marine wireless communications.
{"title":"A ground-based microwave radiometer temperature and humidity profile retrieval method integrating swarm intelligence optimization and attention mechanism under clear-sky conditions","authors":"Bairui Chen, Xuekai Lan, Bin Tian, Wenlong Tang, Jie Li, Dongli Deng","doi":"10.3389/fmars.2026.1754952","DOIUrl":"https://doi.org/10.3389/fmars.2026.1754952","url":null,"abstract":"To address the insufficient retrieval accuracy of temperature and humidity profiles from ground-based microwave radiometers, this study develops an improved retrieval method based on intelligent optimization and attention mechanisms under clear-sky conditions. The research first constructs a brightness temperature dataset by performing forward modeling of ERA5 reanalysis data for the Haikou region using the MonoRTM model. Subsequently, five common machine learning algorithms—Ridge Regression, XGBoost, Multilayer Perceptron (MLP), Random Forest, and Support Vector Machine (SVM)—are employed to reconstruct atmospheric temperature and humidity profiles. A systematic evaluation of the retrieval results reveals distinct performance characteristics across the five machine learning models. For temperature retrieval, the Wolf Pack Algorithm (WPA) is introduced to optimize SVM parameters, resulting in a WPA-SVM model that reduces the overall Root Mean Square Error (RMSE) by 13.2% compared to conventional SVM. For humidity retrieval, an innovative MLP model integrated with an attention mechanism is proposed. By incorporating adaptive weighting and oversampling strategies, this model significantly improves retrieval accuracy at high altitudes, achieving a 15.1% reduction in overall RMSE compared to traditional MLP. The hybrid retrieval framework developed in this study integrates swarm intelligence and machine learning, under clear-sky conditions, providing a reliable technical pathway for high-precision and high-robustness atmospheric parameter retrieval. These findings not only hold significant value for advancing high-accuracy atmospheric parameter remote sensing systems, but also establish a foundation for precisely retrieving atmospheric refractivity profiles to resolve atmospheric ducts, thereby carrying important implications for marine wireless communications.","PeriodicalId":12479,"journal":{"name":"Frontiers in Marine Science","volume":"1 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147358850","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-05DOI: 10.3389/fmars.2026.1783543
Yutong Guo, Yangjun Wang, Ren Zhang
Accelerated Arctic sea-ice melt is profoundly reshaping global shipping patterns and trade networks, with particularly significant implications for the China–Europe maritime corridor. To assess the resilience of China–EU maritime trade under these evolving conditions, this study develops a dual-dimensional scenario analysis framework that integrates both climate-change and geopolitical risks. We introduce an innovative coupled GTAP-P_D (Global Trade Analysis Project- Equivalent Probability of Delivery Cost) model to simulate the synergistic effects of the Northeast Passage (NEP) and the traditional Suez Canal on bilateral trade flows. Multi-scenario simulations yield three key findings: (1) As Arctic sea ice continues to retreat, the NEP provides substantial strategic backup value during Suez Canal disruptions arising from geopolitical conflict, thereby stabilizing trade flows and enhancing system resilience; (2) Realizing dual-channel synergies depends strongly on aligning cargo time-sensitivity elasticity with route characteristics, with highly time-sensitive goods benefiting the most from improved Arctic navigability; and (3) Distinct tipping-point effects emerge across climate pathways. For example, under the SSP5-8.5 scenario, the NEP could become the primary navigation route in the presence of high-intensity geopolitical risks by approximately 2060. Overall, this study offers quantitative evidence to support sustainable Arctic-route development and the resilient advancement of China–Europe maritime trade, while also providing a generalizable framework for evaluating compound climate–geopolitical risks.
{"title":"A risk-informed quantitative framework for Arctic navigation: modeling the navigability and resilience of the China-Europe shipping corridor under climate change","authors":"Yutong Guo, Yangjun Wang, Ren Zhang","doi":"10.3389/fmars.2026.1783543","DOIUrl":"https://doi.org/10.3389/fmars.2026.1783543","url":null,"abstract":"Accelerated Arctic sea-ice melt is profoundly reshaping global shipping patterns and trade networks, with particularly significant implications for the China–Europe maritime corridor. To assess the resilience of China–EU maritime trade under these evolving conditions, this study develops a dual-dimensional scenario analysis framework that integrates both climate-change and geopolitical risks. We introduce an innovative coupled GTAP-P_D (Global Trade Analysis Project- Equivalent Probability of Delivery Cost) model to simulate the synergistic effects of the Northeast Passage (NEP) and the traditional Suez Canal on bilateral trade flows. Multi-scenario simulations yield three key findings: (1) As Arctic sea ice continues to retreat, the NEP provides substantial strategic backup value during Suez Canal disruptions arising from geopolitical conflict, thereby stabilizing trade flows and enhancing system resilience; (2) Realizing dual-channel synergies depends strongly on aligning cargo time-sensitivity elasticity with route characteristics, with highly time-sensitive goods benefiting the most from improved Arctic navigability; and (3) Distinct tipping-point effects emerge across climate pathways. For example, under the SSP5-8.5 scenario, the NEP could become the primary navigation route in the presence of high-intensity geopolitical risks by approximately 2060. Overall, this study offers quantitative evidence to support sustainable Arctic-route development and the resilient advancement of China–Europe maritime trade, while also providing a generalizable framework for evaluating compound climate–geopolitical risks.","PeriodicalId":12479,"journal":{"name":"Frontiers in Marine Science","volume":"1 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147358851","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-04DOI: 10.3389/fmars.2026.1688192
Sidra Kanwel, Shen Kaiju
Microplastics (MPs) pollution is a serious environmental problem that affects ecosystems, human health, and biodiversity. In Pakistan, microplastic contamination is especially concerning, with studies showing high concentrations in various water bodies and marine environments. The Indus River, for example, is estimated to carry 10,000 metric tons of MPs annually into the Arabian Sea. Specific locations such as Clifton Beach in Karachi have been reported to contain approximately 300 MPs per gram of sand. Furthermore, MPs are found in table salts, with averages ranging between 30 and 35 particles per kilogram. In freshwater lakes like Rawal Lake, concentrations of up to 8.8 particles per cubic meter have been observed. Despite these alarming statistics, Pakistan lacks a clear legislative framework to address microplastic pollution. Existing environmental laws, such as the Pakistan Environmental Protection Act (PEPA), do not define or regulate MPs specifically. This study highlights the legislative gaps and suggests reforms based on international best practices, particularly from the EU REACH Regulation and Japan’s Act on the Promotion of Resource Circulation for Plastics. Key recommendations include establishing a National Microplastic Monitoring Program, implementing Extended Producer Responsibility (EPR) schemes, and adopting sector-specific controls to reduce microplastic emissions from industries like textiles and tires. By integrating these measures, Pakistan can improve its governance of MPs and contribute to global efforts to mitigate this pervasive pollutant.
{"title":"Microplastic waste governance in Pakistan: administrative, legal, and environmental challenges","authors":"Sidra Kanwel, Shen Kaiju","doi":"10.3389/fmars.2026.1688192","DOIUrl":"https://doi.org/10.3389/fmars.2026.1688192","url":null,"abstract":"Microplastics (MPs) pollution is a serious environmental problem that affects ecosystems, human health, and biodiversity. In Pakistan, microplastic contamination is especially concerning, with studies showing high concentrations in various water bodies and marine environments. The Indus River, for example, is estimated to carry 10,000 metric tons of MPs annually into the Arabian Sea. Specific locations such as Clifton Beach in Karachi have been reported to contain approximately 300 MPs per gram of sand. Furthermore, MPs are found in table salts, with averages ranging between 30 and 35 particles per kilogram. In freshwater lakes like Rawal Lake, concentrations of up to 8.8 particles per cubic meter have been observed. Despite these alarming statistics, Pakistan lacks a clear legislative framework to address microplastic pollution. Existing environmental laws, such as the Pakistan Environmental Protection Act (PEPA), do not define or regulate MPs specifically. This study highlights the legislative gaps and suggests reforms based on international best practices, particularly from the EU REACH Regulation and Japan’s Act on the Promotion of Resource Circulation for Plastics. Key recommendations include establishing a National Microplastic Monitoring Program, implementing Extended Producer Responsibility (EPR) schemes, and adopting sector-specific controls to reduce microplastic emissions from industries like textiles and tires. By integrating these measures, Pakistan can improve its governance of MPs and contribute to global efforts to mitigate this pervasive pollutant.","PeriodicalId":12479,"journal":{"name":"Frontiers in Marine Science","volume":"42 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147358874","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-04DOI: 10.3389/fmars.2026.1760162
Philip A. H. Smith, Anshul Chauhan, Marilaure Grégoire, Luc Vandenbulcke, Filipe Rodrigues, Asbjørn Christensen, Michael A. St John, Patrizio Mariani
We present a spatiotemporal convolutional U-Net emulator model to forecast phytoplankton chlorophyll concentrations and key nutrient fields (nitrate and ammonium) in the Black Sea, using simulation data from 1950–2014. The emulator achieved substantially higher predictive skill compared to baseline approaches, with a 41% improvement for chlorophyll and 59% for phosphate, while accurately capturing both spatial and temporal variability in biogeochemical dynamics. In addition to forecasting, interpretability of the model was obtained through Sobol sensitivity analysis, complemented by derivative-based global sensitivity measures (DGSM) and elasticity analysis. These revealed pronounced spatial and seasonal variations in the dominant environmental drivers across the basin, enabling exploration of “what-if” scenarios through targeted perturbations of key physical and biogeochemical drivers. Overall, light availability and nutrient concentrations (particularly nitrate, ammonium, and phosphate) emerged as key contributors, with a transition from predominantly light-driven short-term sensitivity toward increasing nutrient influence at longer lead times, modulated by strong regional and seasonal variability. The ability of the model to forecast biogeochemical states and to identify their dominant drivers highlights its potential as an early warning tool for detecting ecosystem changes and supporting adaptive management of the Black Sea.
{"title":"Identifying drivers and dynamics of phytoplankton in the Black Sea: application of a neural emulator","authors":"Philip A. H. Smith, Anshul Chauhan, Marilaure Grégoire, Luc Vandenbulcke, Filipe Rodrigues, Asbjørn Christensen, Michael A. St John, Patrizio Mariani","doi":"10.3389/fmars.2026.1760162","DOIUrl":"https://doi.org/10.3389/fmars.2026.1760162","url":null,"abstract":"We present a spatiotemporal convolutional U-Net emulator model to forecast phytoplankton chlorophyll concentrations and key nutrient fields (nitrate and ammonium) in the Black Sea, using simulation data from 1950–2014. The emulator achieved substantially higher predictive skill compared to baseline approaches, with a 41% improvement for chlorophyll and 59% for phosphate, while accurately capturing both spatial and temporal variability in biogeochemical dynamics. In addition to forecasting, interpretability of the model was obtained through Sobol sensitivity analysis, complemented by derivative-based global sensitivity measures (DGSM) and elasticity analysis. These revealed pronounced spatial and seasonal variations in the dominant environmental drivers across the basin, enabling exploration of “what-if” scenarios through targeted perturbations of key physical and biogeochemical drivers. Overall, light availability and nutrient concentrations (particularly nitrate, ammonium, and phosphate) emerged as key contributors, with a transition from predominantly light-driven short-term sensitivity toward increasing nutrient influence at longer lead times, modulated by strong regional and seasonal variability. The ability of the model to forecast biogeochemical states and to identify their dominant drivers highlights its potential as an early warning tool for detecting ecosystem changes and supporting adaptive management of the Black Sea.","PeriodicalId":12479,"journal":{"name":"Frontiers in Marine Science","volume":"16 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147358873","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-04DOI: 10.3389/fmars.2026.1764846
Emma McKinley, Jordi F. Pagès, Helen Lockhart, Judy Mann-Lang
Recent years have witnessed increased interest in human-ocean relationships and the role that understanding these can play in ensuring sustainable ocean futures. Once a concept on the periphery of ocean governance, ocean literacy has become an integral component of ocean discourse and governance. Historically grounded in marine education, ocean literacy has undergone a significant evolution moving beyond its educational roots and individual knowledge development to an effort that seeks ocean literacy as a societal outcome. While interest in ocean literacy has increased, knowledge and research gaps remain, including a tendency for most research being carried out in the Global North. This paper recognises this gap and seeks to address the geographical biases inherent within ocean literacy research, presenting the first assessment of ocean literacy across South Africa. Using an online questionnaire (n=549), this study explored multiple dimensions of ocean literacy, gathering crucial insights into human-ocean relationships in a South African context. Analysis found there to be high levels of concern for the marine environment, with plastic pollution/litter (73%) and overfishing (72%) identified as the leading threats facing South Africa’s ocean, while over 98% of respondents indicated that protecting the marine environment was important to them personally. Through the paper, we explore each of the ocean literacy dimensions, including ‘emoceans’ and emotional responses to the ocean, access and experience, trust, and more. While this study cannot be considered an exhaustive, whole of society, evaluation of ocean literacy in South Africa, and recognising ongoing discourse around the suitability of the concept outside of its Global North origins, the paper presented here contributes valuable insights, adding to the global evidence and understanding of ocean literacy and addressing evidence and knowledge gaps.
{"title":"Understanding and exploring ocean literacy in South Africa: an initial assessment","authors":"Emma McKinley, Jordi F. Pagès, Helen Lockhart, Judy Mann-Lang","doi":"10.3389/fmars.2026.1764846","DOIUrl":"https://doi.org/10.3389/fmars.2026.1764846","url":null,"abstract":"Recent years have witnessed increased interest in human-ocean relationships and the role that understanding these can play in ensuring sustainable ocean futures. Once a concept on the periphery of ocean governance, ocean literacy has become an integral component of ocean discourse and governance. Historically grounded in marine education, ocean literacy has undergone a significant evolution moving beyond its educational roots and individual knowledge development to an effort that seeks ocean literacy as a societal outcome. While interest in ocean literacy has increased, knowledge and research gaps remain, including a tendency for most research being carried out in the Global North. This paper recognises this gap and seeks to address the geographical biases inherent within ocean literacy research, presenting the first assessment of ocean literacy across South Africa. Using an online questionnaire (n=549), this study explored multiple dimensions of ocean literacy, gathering crucial insights into human-ocean relationships in a South African context. Analysis found there to be high levels of concern for the marine environment, with plastic pollution/litter (73%) and overfishing (72%) identified as the leading threats facing South Africa’s ocean, while over 98% of respondents indicated that protecting the marine environment was important to them personally. Through the paper, we explore each of the ocean literacy dimensions, including ‘emoceans’ and emotional responses to the ocean, access and experience, trust, and more. While this study cannot be considered an exhaustive, whole of society, evaluation of ocean literacy in South Africa, and recognising ongoing discourse around the suitability of the concept outside of its Global North origins, the paper presented here contributes valuable insights, adding to the global evidence and understanding of ocean literacy and addressing evidence and knowledge gaps.","PeriodicalId":12479,"journal":{"name":"Frontiers in Marine Science","volume":"2 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147358852","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-04DOI: 10.3389/fmars.2026.1716162
Mariselvammurugan A, Chandrasekar Selvam, Tari Tejas Santosh, Kamini Jothi Sri N, Linga Prabu D, Sanal Ebeneezar, Adnan H. Gora, Sayooj P, Ambarish P. Gop, Tejpal C. S, Chiranjiv Pradhan, Kajal Chakraborty
Salinity strongly influences osmoregulation energy metabolism, and physiological performance in euryhaline fishes. The marine medaka, Oryzias dancena is an emerging model for investigating the molecular and physiological basis of salinity adaptation. Here, fish were exposed to hypo- (5 ppt), near-isoosmotic (23 ppt), and hyperosmotic (35 ppt) salinities, and assessed integrated physiological, biochemical, and molecular responses. Hepatic histology showed pronounced vacuolization at 5 and 35 ppt, whereas 23 ppt supported more uniform hepatocellular morphology. Whole-body digestive and antioxidant enzymes exhibited salinity-dependent modulation, with elevated protease and SOD activity at 5 ppt and higher lipase activity at 23 ppt. Gene expression analysis showed upregulation of nka under salinity extremes, while lipid oxidation genes ( ppar-δ , cpt1 ) peaked at 23 ppt, indicating a trade-off between osmoregulatory demand and lipid catabolism. Muscle fatty acid composition remained largely conserved; however, hyperosmotic stress (35 ppt) caused a significant decline in docosahexaenoic acid (DHA, 22:6n-3), together with a concomitant increase in monounsaturated fatty acids, particularly palmitoleic acid (16:1), indicating selective changes in membrane lipid composition under high salinity. Although hepatic fatty acid composition was not measured in this study, the combined evidence from hepatocellular morphology and lipid metabolic gene expression provides clear indications of salinity-dependent shifts in hepatic lipid handling. Collectively, this study provides foundational insight into the osmoregulatory and metabolic strategies of O. dancena , establishing its value as a tractable marine model for integrative studies on salinity adaptation.
{"title":"Salinity-induced modulation of hepatic morphology, enzymatic responses, muscle fatty acid composition, and gene expression in the euryhaline teleost Oryzias dancena","authors":"Mariselvammurugan A, Chandrasekar Selvam, Tari Tejas Santosh, Kamini Jothi Sri N, Linga Prabu D, Sanal Ebeneezar, Adnan H. Gora, Sayooj P, Ambarish P. Gop, Tejpal C. S, Chiranjiv Pradhan, Kajal Chakraborty","doi":"10.3389/fmars.2026.1716162","DOIUrl":"https://doi.org/10.3389/fmars.2026.1716162","url":null,"abstract":"Salinity strongly influences osmoregulation energy metabolism, and physiological performance in euryhaline fishes. The marine medaka, <jats:italic>Oryzias dancena</jats:italic> is an emerging model for investigating the molecular and physiological basis of salinity adaptation. Here, fish were exposed to hypo- (5 ppt), near-isoosmotic (23 ppt), and hyperosmotic (35 ppt) salinities, and assessed integrated physiological, biochemical, and molecular responses. Hepatic histology showed pronounced vacuolization at 5 and 35 ppt, whereas 23 ppt supported more uniform hepatocellular morphology. Whole-body digestive and antioxidant enzymes exhibited salinity-dependent modulation, with elevated protease and SOD activity at 5 ppt and higher lipase activity at 23 ppt. Gene expression analysis showed upregulation of <jats:italic>nka</jats:italic> under salinity extremes, while lipid oxidation genes ( <jats:italic>ppar-δ</jats:italic> , <jats:italic>cpt1</jats:italic> ) peaked at 23 ppt, indicating a trade-off between osmoregulatory demand and lipid catabolism. Muscle fatty acid composition remained largely conserved; however, hyperosmotic stress (35 ppt) caused a significant decline in docosahexaenoic acid (DHA, 22:6n-3), together with a concomitant increase in monounsaturated fatty acids, particularly palmitoleic acid (16:1), indicating selective changes in membrane lipid composition under high salinity. Although hepatic fatty acid composition was not measured in this study, the combined evidence from hepatocellular morphology and lipid metabolic gene expression provides clear indications of salinity-dependent shifts in hepatic lipid handling. Collectively, this study provides foundational insight into the osmoregulatory and metabolic strategies of <jats:italic>O. dancena</jats:italic> , establishing its value as a tractable marine model for integrative studies on salinity adaptation.","PeriodicalId":12479,"journal":{"name":"Frontiers in Marine Science","volume":"28 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147358875","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-04DOI: 10.3389/fmars.2026.1767697
Emma C. Johnson, Juliet M. Wong
Marine and freshwater ecosystems are undergoing rapid transformations propelled by human activity, placing unprecedented pressure on aquatic species and threatening critical ecosystem services. Aquatic invertebrates, which underpin aquaculture industries, shape habitat structure, and contribute to biomedical discovery, are particularly vulnerable, yet their capacity to respond to environmental change remains understudied. Epigenetic mechanisms have emerged as potential mediators of rapid acclimatization, but their roles in aquatic invertebrates are not well defined. In this review, we systematically analyzed 223 studies that examined epigenetic responses of aquatic invertebrates to environmental or anthropogenic stress. For each study, we recorded taxonomic representation, stressor type, exposure duration, experimental design, and major molecular and phenotypic outcomes. DNA methylation was the most frequently investigated mechanism, mollusks were the dominant study phylum, and infection was the most common stressor; however, substantial variation and ongoing debate were evident across molecular findings. Epigenetic processes are increasingly recognized as key regulators of gene expression and phenotypic plasticity, yet their functional significance, temporal stability, and heritability in aquatic invertebrates remain uncertain. By synthesizing existing evidence and compiling a comprehensive database of current research, this review establishes a foundation for advancing environmental epigenetics toward a predictive, mechanistic framework capable of informing conservation, aquaculture, and ecosystem management under accelerating global change.
{"title":"From stress to response: a systematic review of epigenetic pathways underlying gene expression and phenotypic plasticity in aquatic invertebrates","authors":"Emma C. Johnson, Juliet M. Wong","doi":"10.3389/fmars.2026.1767697","DOIUrl":"https://doi.org/10.3389/fmars.2026.1767697","url":null,"abstract":"Marine and freshwater ecosystems are undergoing rapid transformations propelled by human activity, placing unprecedented pressure on aquatic species and threatening critical ecosystem services. Aquatic invertebrates, which underpin aquaculture industries, shape habitat structure, and contribute to biomedical discovery, are particularly vulnerable, yet their capacity to respond to environmental change remains understudied. Epigenetic mechanisms have emerged as potential mediators of rapid acclimatization, but their roles in aquatic invertebrates are not well defined. In this review, we systematically analyzed 223 studies that examined epigenetic responses of aquatic invertebrates to environmental or anthropogenic stress. For each study, we recorded taxonomic representation, stressor type, exposure duration, experimental design, and major molecular and phenotypic outcomes. DNA methylation was the most frequently investigated mechanism, mollusks were the dominant study phylum, and infection was the most common stressor; however, substantial variation and ongoing debate were evident across molecular findings. Epigenetic processes are increasingly recognized as key regulators of gene expression and phenotypic plasticity, yet their functional significance, temporal stability, and heritability in aquatic invertebrates remain uncertain. By synthesizing existing evidence and compiling a comprehensive database of current research, this review establishes a foundation for advancing environmental epigenetics toward a predictive, mechanistic framework capable of informing conservation, aquaculture, and ecosystem management under accelerating global change.","PeriodicalId":12479,"journal":{"name":"Frontiers in Marine Science","volume":"53 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147358917","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-04DOI: 10.3389/fmars.2026.1777787
Xiao Li, Xiaoxia Hu, Qingsheng Miao, Yangyi Ai, Lu Yang, Wenhai Lu
Bohai Bay, a semi-enclosed and ecologically vital bay in northern China, is increasingly threatened by multiple anthropogenic stressors and nutrient enrichment and pollution, particularly excessive nutrient enrichment (cultural eutrophication) from land-based sources (e.g., aquaculture wastewater, riverine input). This study presents a spatially explicit, pressure–sensitivity-based framework to quantify the cumulative impacts of physical loss, physical damage, and eutrophication on subtidal benthic habitats. By integrating spatial data on human uses, eutrophication indices (E), and habitat-specific sensitivity scores, we identified significant spatial heterogeneity in ecological risks, with benthic communities in high-impact zones showing distinct shifts toward pollution-tolerant taxa and degraded ecological quality (e.g., 75% dominance of pollution-tolerant polychaetes). The infralittoral mud habitat, covering ~60% of the bay, was most affected by environmental pressure (31.96% of its area), primarily driven by eutrophication (E>9 in nearshore areas), followed by physical damage (4.72%) and physical loss (0.17%). Although physical loss had a limited spatial extent, its irreversible nature poses high ecological risks. The circalittoral zone, in contrast, faced minimal physical disturbance but remained vulnerable to eutrophication. Our findings highlight the need for differentiated, spatially explicit marine management strategies, particularly for muddy infralittoral habitats where long-term pollution control (e.g., C DIN < 0.5 mg/L) and habitat restoration should be prioritized. This study provides a scientific foundation for conservation planning and ecological risk mitigation in Bohai Bay and similar nutrient-enriched coastal ecosystems globally.
渤海湾作为中国北方半封闭的生态重要海湾，正日益受到多种人为压力源和营养物富集与污染的威胁，特别是陆源（如水产养殖废水、河流输入）的过度营养物富集（养殖富营养化）。本研究提出了一个空间明确的、基于压力敏感性的框架来量化物理损失、物理破坏和富营养化对潮下底栖生物栖息地的累积影响。通过整合人类利用、富营养化指数(E)和栖息地特异性敏感性评分的空间数据，我们发现了生态风险的显著空间异质性，高影响区的底栖生物群落表现出明显的向耐污染类群和生态质量退化的转变（例如，耐污染多毛类占75%的优势）。滨下淤泥生境受环境压力影响最大（占总面积的31.96%），主要是富营养化（近岸地区为E&；gt;9），其次是物理破坏（4.72%）和物理损失（0.17%）。虽然物质损失的空间范围有限，但其不可逆性构成了较高的生态风险。相比之下，环流区面临最小的物理干扰，但仍然容易富营养化。我们的研究结果强调，需要有区别的、空间明确的海洋管理策略，特别是对于泥泞的沿海下栖息地，长期污染控制（例如，C - DIN &;lt; 0.5 mg/L）和栖息地恢复应优先考虑。本研究为渤海湾及全球类似富营养化沿海生态系统的保护规划和生态风险缓解提供了科学依据。
{"title":"Cumulative impact assessment of human and environmental stressors on subtidal benthic habitats in Bohai Bay using a spatially explicit framework","authors":"Xiao Li, Xiaoxia Hu, Qingsheng Miao, Yangyi Ai, Lu Yang, Wenhai Lu","doi":"10.3389/fmars.2026.1777787","DOIUrl":"https://doi.org/10.3389/fmars.2026.1777787","url":null,"abstract":"Bohai Bay, a semi-enclosed and ecologically vital bay in northern China, is increasingly threatened by multiple anthropogenic stressors and nutrient enrichment and pollution, particularly excessive nutrient enrichment (cultural eutrophication) from land-based sources (e.g., aquaculture wastewater, riverine input). This study presents a spatially explicit, pressure–sensitivity-based framework to quantify the cumulative impacts of physical loss, physical damage, and eutrophication on subtidal benthic habitats. By integrating spatial data on human uses, eutrophication indices (E), and habitat-specific sensitivity scores, we identified significant spatial heterogeneity in ecological risks, with benthic communities in high-impact zones showing distinct shifts toward pollution-tolerant taxa and degraded ecological quality (e.g., 75% dominance of pollution-tolerant polychaetes). The infralittoral mud habitat, covering ~60% of the bay, was most affected by environmental pressure (31.96% of its area), primarily driven by eutrophication (E&gt;9 in nearshore areas), followed by physical damage (4.72%) and physical loss (0.17%). Although physical loss had a limited spatial extent, its irreversible nature poses high ecological risks. The circalittoral zone, in contrast, faced minimal physical disturbance but remained vulnerable to eutrophication. Our findings highlight the need for differentiated, spatially explicit marine management strategies, particularly for muddy infralittoral habitats where long-term pollution control (e.g., C <jats:sub>DIN</jats:sub> &lt; 0.5 mg/L) and habitat restoration should be prioritized. This study provides a scientific foundation for conservation planning and ecological risk mitigation in Bohai Bay and similar nutrient-enriched coastal ecosystems globally.","PeriodicalId":12479,"journal":{"name":"Frontiers in Marine Science","volume":"13 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147358872","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-03DOI: 10.3389/fmars.2026.1757991
Idham Nugraha, Freya M. E. Muir, Larissa A. Naylor, Martin D. Hurst
Monitoring vegetation edges in dynamic coastal zones is essential for understanding long-term shoreline change and supporting effective coastal management, particularly as climate change accelerates erosion, sea-level rise, and ecosystem shifts. This study provides the first validation of VedgeSat, an automated Vegetation Edge (VE) detection toolkit, in contrasting tropical coastal environments, with relevance for coastal monitoring worldwide. In Sumatra, Indonesia, fifteen sites were assessed, encompassing diverse vegetation and sediment types, a range of water clarity, and varying wave exposures in both open and sheltered coastal settings. Vegetation edge detection was conducted with high-resolution PlanetScope imagery and differential Global Positioning System (dGPS) field surveys. VedgeSat performed reliably in areas with dense vegetation, regardless of the type of vegetation or sediment, and water clarity achieving sub-pixel root mean square errors (RMSE) of less than 7 m, R 2 values up to 0.89 and minimal positional bias. Performance declined in areas with sparse and patchy vegetation, such as pioneer mangroves and grasses in sandy environments, resulting in higher RMSE and reduced R 2 values. A sensitivity analysis demonstrated that tuning the threshold of Normalized Difference Vegetation Index (NDVI) values can optimize edge detection across diverse vegetation types and environments. Overall, the results confirm the robustness of VedgeSat for scalable monitoring of vegetated coasts without retraining, while also identifying limitations in sparsely vegetated settings. This study provides the first benchmark for automated vegetation edge detection in tropical systems and demonstrates the potential of satellite-based approaches to enable large-scale, repeatable, and cost-effective coastal monitoring in data-scarce regions.
{"title":"Extending a scalable satellite-based vegetation edge detection framework to diverse tropical coasts","authors":"Idham Nugraha, Freya M. E. Muir, Larissa A. Naylor, Martin D. Hurst","doi":"10.3389/fmars.2026.1757991","DOIUrl":"https://doi.org/10.3389/fmars.2026.1757991","url":null,"abstract":"Monitoring vegetation edges in dynamic coastal zones is essential for understanding long-term shoreline change and supporting effective coastal management, particularly as climate change accelerates erosion, sea-level rise, and ecosystem shifts. This study provides the first validation of VedgeSat, an automated Vegetation Edge (VE) detection toolkit, in contrasting tropical coastal environments, with relevance for coastal monitoring worldwide. In Sumatra, Indonesia, fifteen sites were assessed, encompassing diverse vegetation and sediment types, a range of water clarity, and varying wave exposures in both open and sheltered coastal settings. Vegetation edge detection was conducted with high-resolution PlanetScope imagery and differential Global Positioning System (dGPS) field surveys. VedgeSat performed reliably in areas with dense vegetation, regardless of the type of vegetation or sediment, and water clarity achieving sub-pixel root mean square errors (RMSE) of less than 7 m, R <jats:sup>2</jats:sup> values up to 0.89 and minimal positional bias. Performance declined in areas with sparse and patchy vegetation, such as pioneer mangroves and grasses in sandy environments, resulting in higher RMSE and reduced R <jats:sup>2</jats:sup> values. A sensitivity analysis demonstrated that tuning the threshold of Normalized Difference Vegetation Index (NDVI) values can optimize edge detection across diverse vegetation types and environments. Overall, the results confirm the robustness of VedgeSat for scalable monitoring of vegetated coasts without retraining, while also identifying limitations in sparsely vegetated settings. This study provides the first benchmark for automated vegetation edge detection in tropical systems and demonstrates the potential of satellite-based approaches to enable large-scale, repeatable, and cost-effective coastal monitoring in data-scarce regions.","PeriodicalId":12479,"journal":{"name":"Frontiers in Marine Science","volume":"55 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147358876","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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