The Okinawa Trough (OT), a typical back-arc basin in the western Pacific, preserves continuous sedimentary records since the Quaternary, making it a critical area for investigating sea-level changes, source-to-sink processes, and paleoclimate evolution. However, the controlling mechanisms of terrestrial input to the trough since the Last Glacial Maximum (LGM) remain insufficiently understood. This study conducted major element geochemical analysis on core C1624 from the southern part of the middle OT, combined with AMS 14 C dating, grain size, and mineralogical data, to reconstruct the evolution and dominant controls of terrestrial input since the LGM. Principal component analysis (PCA) indicates that the sediments in the study area are primarily composed of a mixture of two end-members: terrigenous detritus and marine biogenic carbonate. The ratios of TFe 2 O 3 /Al 2 O 3 and CaO/Al 2 O 3 were adopted as reliable proxies for terrestrial input and biogenic contribution, respectively. The results reveal a three-stage response of terrestrial input to sea-level changes since the LGM: Stage 1 (25.4–11.6 ka BP), during low sea-level stands, the paleo-Changjiang river system extended to the outer shelf, supplying the dominant sediment source; Stage 2 (11.6–8.7 ka BP), characterized by rapid sea-level rise, witnessed a transition in provenance from the Changjiang to Taiwan-derived materials, accompanied by a sharp decrease in terrestrial input; Stage 3 (8.7–0 ka BP), with the establishment of modern circulation patterns, Taiwan-sourced materials became predominant. This study demonstrates that sea-level changes on glacial-interglacial scales are the fundamental factor reshaping the depositional pattern and driving provenance transitions in the middle OT. These findings provide a new case for understanding the response of marginal sea sediment source-to-sink processes to global climate change.
冲绳海槽（OT）是西太平洋典型的弧后盆地，自第四纪以来保存了连续的沉积记录，是研究海平面变化、源-汇过程和古气候演化的重要区域。然而，末次盛冰期以来陆源输入槽的控制机制尚不清楚。本文对中第三纪南段C1624岩心进行了主元素地球化学分析，结合AMS 14c测年、粒度、矿物学等资料，重建了LGM以来陆源输入的演化和主控因素。主成分分析（PCA）表明，研究区沉积物主要由陆源碎屑和海洋生物碳酸盐两端元混合组成。采用tfe2o3 / al2o3和CaO/ al2o3比值分别作为陆地输入和生物源贡献的可靠指标。结果表明，自LGM以来，陆地输入对海平面变化的响应分为三个阶段：第1阶段（25.4-11.6 ka BP），在低海平面林分，古长江水系向外陆架扩展，提供主要的沉积物来源；第2阶段（11.6 ~ 8.7 ka BP）以海平面快速上升为特征，物源由长江向台湾转移，陆源输入急剧减少；第三阶段（8.7-0 ka BP），随着现代环流模式的建立，台湾来源的物质占主导地位。研究表明，冰期-间冰期尺度上的海平面变化是重塑中生代中期沉积格局和推动物源转换的根本因素。这些发现为理解边缘海沉积物源-汇过程对全球气候变化的响应提供了新的视角。
{"title":"Sea level controls terrigenous sediment provenance evolution in the Okinawa Trough since the Last Glacial Maximum","authors":"Mingyu Zhang, Libo Wang, Jingtao Zhao, Yong Zhang, Hao Tian, Shanshan Chen, Bangqi Hu, Jing Kan, Fuyu Wu, Xiting Liu","doi":"10.3389/fmars.2026.1781917","DOIUrl":"https://doi.org/10.3389/fmars.2026.1781917","url":null,"abstract":"The Okinawa Trough (OT), a typical back-arc basin in the western Pacific, preserves continuous sedimentary records since the Quaternary, making it a critical area for investigating sea-level changes, source-to-sink processes, and paleoclimate evolution. However, the controlling mechanisms of terrestrial input to the trough since the Last Glacial Maximum (LGM) remain insufficiently understood. This study conducted major element geochemical analysis on core C1624 from the southern part of the middle OT, combined with AMS <jats:sup>14</jats:sup> C dating, grain size, and mineralogical data, to reconstruct the evolution and dominant controls of terrestrial input since the LGM. Principal component analysis (PCA) indicates that the sediments in the study area are primarily composed of a mixture of two end-members: terrigenous detritus and marine biogenic carbonate. The ratios of TFe <jats:sub>2</jats:sub> O <jats:sub>3</jats:sub> /Al <jats:sub>2</jats:sub> O <jats:sub>3</jats:sub> and CaO/Al <jats:sub>2</jats:sub> O <jats:sub>3</jats:sub> were adopted as reliable proxies for terrestrial input and biogenic contribution, respectively. The results reveal a three-stage response of terrestrial input to sea-level changes since the LGM: Stage 1 (25.4–11.6 ka BP), during low sea-level stands, the paleo-Changjiang river system extended to the outer shelf, supplying the dominant sediment source; Stage 2 (11.6–8.7 ka BP), characterized by rapid sea-level rise, witnessed a transition in provenance from the Changjiang to Taiwan-derived materials, accompanied by a sharp decrease in terrestrial input; Stage 3 (8.7–0 ka BP), with the establishment of modern circulation patterns, Taiwan-sourced materials became predominant. This study demonstrates that sea-level changes on glacial-interglacial scales are the fundamental factor reshaping the depositional pattern and driving provenance transitions in the middle OT. These findings provide a new case for understanding the response of marginal sea sediment source-to-sink processes to global climate change.","PeriodicalId":12479,"journal":{"name":"Frontiers in Marine Science","volume":"238 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146222863","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 : 2026-02-20DOI: 10.3389/fmars.2026.1740354
Jennifer K. McWhorter, Lev B. Looney, Matthieu Le Hénaff, Heather L. Roman-Stork, Gregory R. Foltz, Fabian Gomez, Marin Cornec, Madison Soden, Jun A. Zhang, Emily B. Osborne
Satellite observations can reveal chlorophyll blooms in the wake of hurricane disturbances but their subsurface biogeochemical anomalies remain poorly described due to limited in situ observations. Here, we quantify the biogeochemical response across the ocean water column to Hurricane Idalia (2023) in the Gulf of America (also known as the Gulf of Mexico). We compile observations across the eastern Gulf using satellite data and two autonomous platforms: a profiling Biogeochemical-Argo (BGC-Argo) float and saildrone. Prior to the formation of Hurricane Idalia, an anomalously large extension of the Mississippi River plume spanned much of the eastern Gulf, contributing low-salinity and high-chlorophyll conditions. Following Idalia’s passage, the saildrone observed surface chlorophyll increases in the river plume extension, while the BGC-Argo float observed subsurface nitrate depletion and oxygen enrichment. These changes occurred as the float measured background ocean conditions evolving from the edge of the Loop Current to a cyclonic eddy, influenced by the river plume extension. Increases in chlorophyll concentration, decreases in nitrate, and elevated dissolved oxygen levels suggested increased primary production. BGC-Argo float observations revealed enhanced upwelling below the surface layer (~22 m) that shoaled the nitracline, fueling the increase in subsurface primary production (20–50 m depth). Our study provides a glimpse on the surface and subsurface ocean-biogeochemical changes associated with the Hurricane Idalia passage, highlighting the importance of the background mesoscale seascape on shaping the phytoplankton response to hurricane-induced disturbances. The combination of observations underscores the value of continuous in situ monitoring to better understand hurricane-driven impacts on the full ocean water column and the impacts these dynamics have on the base of the marine food web.
{"title":"Subsurface biogeochemical response to Hurricane Idalia within a cyclonic eddy and river plume–stratified environment","authors":"Jennifer K. McWhorter, Lev B. Looney, Matthieu Le Hénaff, Heather L. Roman-Stork, Gregory R. Foltz, Fabian Gomez, Marin Cornec, Madison Soden, Jun A. Zhang, Emily B. Osborne","doi":"10.3389/fmars.2026.1740354","DOIUrl":"https://doi.org/10.3389/fmars.2026.1740354","url":null,"abstract":"Satellite observations can reveal chlorophyll blooms in the wake of hurricane disturbances but their subsurface biogeochemical anomalies remain poorly described due to limited <jats:italic>in situ</jats:italic> observations. Here, we quantify the biogeochemical response across the ocean water column to Hurricane Idalia (2023) in the Gulf of America (also known as the Gulf of Mexico). We compile observations across the eastern Gulf using satellite data and two autonomous platforms: a profiling Biogeochemical-Argo (BGC-Argo) float and saildrone. Prior to the formation of Hurricane Idalia, an anomalously large extension of the Mississippi River plume spanned much of the eastern Gulf, contributing low-salinity and high-chlorophyll conditions. Following Idalia’s passage, the saildrone observed surface chlorophyll increases in the river plume extension, while the BGC-Argo float observed subsurface nitrate depletion and oxygen enrichment. These changes occurred as the float measured background ocean conditions evolving from the edge of the Loop Current to a cyclonic eddy, influenced by the river plume extension. Increases in chlorophyll concentration, decreases in nitrate, and elevated dissolved oxygen levels suggested increased primary production. BGC-Argo float observations revealed enhanced upwelling below the surface layer (~22 m) that shoaled the nitracline, fueling the increase in subsurface primary production (20–50 m depth). Our study provides a glimpse on the surface and subsurface ocean-biogeochemical changes associated with the Hurricane Idalia passage, highlighting the importance of the background mesoscale seascape on shaping the phytoplankton response to hurricane-induced disturbances. The combination of observations underscores the value of continuous <jats:italic>in situ</jats:italic> monitoring to better understand hurricane-driven impacts on the full ocean water column and the impacts these dynamics have on the base of the marine food web.","PeriodicalId":12479,"journal":{"name":"Frontiers in Marine Science","volume":"30 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146222865","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 : 2026-02-20DOI: 10.3389/fmars.2026.1753767
Fang Ye, Xiaodong Sun, Jiaqiang Shen
In the context of addressing climate change and advancing “carbon neutrality,” enhancing marine carbon sink capacity has become a national strategy for many countries. Scientifically evaluating marine carbon sink performance and its driving mechanisms is crucial for optimizing marine environmental governance. This paper employs the Super-SBM model to measure the marine carbon sink performance of 11 coastal provinces (municipalities and autonomous regions) in China from 2008 to 2022, and empirically examines the nonlinear impact of heterogeneous environmental regulations, as well as the mediating mechanisms of technological innovation and industrial upgrading. The results show that: Firstly, China’s marine carbon sink performance has generally improved, but regional development is uneven. Secondly, command-and-control and market-incentive environmental regulations exhibit an “inverted U-shaped” relationship with performance, while social-supervised environmental regulations show a “U-shaped” relationship, indicating that there is an optimal intensity range for regulatory effects. Finally, technological innovation and industrial upgrading are important transmission pathways through which environmental regulations affect carbon sink performance. The research findings provide theoretical references and empirical evidence for governments to develop differentiated and diversified environmental regulation policy portfolios aimed at enhancing marine carbon sink capacity.
{"title":"Research on the nonlinear impact of heterogeneous environmental regulations on marine carbon sink performance","authors":"Fang Ye, Xiaodong Sun, Jiaqiang Shen","doi":"10.3389/fmars.2026.1753767","DOIUrl":"https://doi.org/10.3389/fmars.2026.1753767","url":null,"abstract":"In the context of addressing climate change and advancing “carbon neutrality,” enhancing marine carbon sink capacity has become a national strategy for many countries. Scientifically evaluating marine carbon sink performance and its driving mechanisms is crucial for optimizing marine environmental governance. This paper employs the Super-SBM model to measure the marine carbon sink performance of 11 coastal provinces (municipalities and autonomous regions) in China from 2008 to 2022, and empirically examines the nonlinear impact of heterogeneous environmental regulations, as well as the mediating mechanisms of technological innovation and industrial upgrading. The results show that: Firstly, China’s marine carbon sink performance has generally improved, but regional development is uneven. Secondly, command-and-control and market-incentive environmental regulations exhibit an “inverted U-shaped” relationship with performance, while social-supervised environmental regulations show a “U-shaped” relationship, indicating that there is an optimal intensity range for regulatory effects. Finally, technological innovation and industrial upgrading are important transmission pathways through which environmental regulations affect carbon sink performance. The research findings provide theoretical references and empirical evidence for governments to develop differentiated and diversified environmental regulation policy portfolios aimed at enhancing marine carbon sink capacity.","PeriodicalId":12479,"journal":{"name":"Frontiers in Marine Science","volume":"402 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146222866","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 : 2026-02-19DOI: 10.3389/fmars.2026.1685208
Ke Zhang, Er-He Chen, Yu-Lin Chen, Jun-Jie Li, Tao Huang, Wei Liu, Si-Hao Wei, Yu-Kang Tu
The development of a legal system for marine environmental protection in the Guangdong-Hong Kong-Macao Greater Bay Area is a critical issue for cross-border ecological governance under the unique context of "One Country, Two Systems, Three Jurisdictions." This issue directly affects regional ecological security and the high-quality development of the marine economy. This paper uses comparative law and empirical analysis to systematically review the institutional frameworks and current practices of the three regions across four dimensions: Legislation, law enforcement, judicial adjudication, and legal regulation of public participation. The study finds that the current system faces core difficulties, including a disconnect in legislative coordination mechanisms, insufficient effectiveness in joint law enforcement, uncoordinated judicial collaboration, and insufficient legal safeguards for public participation. The root causes lie in the differences between regional legal systems, the absence of coordination mechanisms, poor resource integration, and fragmented participation channels. Based on this, the paper proposes a comprehensive improvement path. At the legislative level, we should establish a normalized coordination mechanism to promote the alignment of rules and standards. At the enforcement level, we should build a unified coordination platform to deepen cross-border collaboration and resource sharing. At the judicial level, we should improve cross-border collaboration norms and improve mechanisms for identifying and repairing ecological damage. At the level of public participation, we should build a unified cross-border platform to strengthen collaborative systems and public interest cooperation. The research aims to provide a governance model for regional marine environmental protection under "One Country, Two Systems, Three Jurisdictions," offering theoretical support and practical guidance for solving cross-border ecological governance problems, and assisting in the construction of a strong maritime nation and the improvement of the global marine governance system.
{"title":"Research on rule of law system for marine environmental protection in the Guangdong-Hong Kong-Macao Greater Bay Area","authors":"Ke Zhang, Er-He Chen, Yu-Lin Chen, Jun-Jie Li, Tao Huang, Wei Liu, Si-Hao Wei, Yu-Kang Tu","doi":"10.3389/fmars.2026.1685208","DOIUrl":"https://doi.org/10.3389/fmars.2026.1685208","url":null,"abstract":"The development of a legal system for marine environmental protection in the Guangdong-Hong Kong-Macao Greater Bay Area is a critical issue for cross-border ecological governance under the unique context of \"One Country, Two Systems, Three Jurisdictions.\" This issue directly affects regional ecological security and the high-quality development of the marine economy. This paper uses comparative law and empirical analysis to systematically review the institutional frameworks and current practices of the three regions across four dimensions: Legislation, law enforcement, judicial adjudication, and legal regulation of public participation. The study finds that the current system faces core difficulties, including a disconnect in legislative coordination mechanisms, insufficient effectiveness in joint law enforcement, uncoordinated judicial collaboration, and insufficient legal safeguards for public participation. The root causes lie in the differences between regional legal systems, the absence of coordination mechanisms, poor resource integration, and fragmented participation channels. Based on this, the paper proposes a comprehensive improvement path. At the legislative level, we should establish a normalized coordination mechanism to promote the alignment of rules and standards. At the enforcement level, we should build a unified coordination platform to deepen cross-border collaboration and resource sharing. At the judicial level, we should improve cross-border collaboration norms and improve mechanisms for identifying and repairing ecological damage. At the level of public participation, we should build a unified cross-border platform to strengthen collaborative systems and public interest cooperation. The research aims to provide a governance model for regional marine environmental protection under \"One Country, Two Systems, Three Jurisdictions,\" offering theoretical support and practical guidance for solving cross-border ecological governance problems, and assisting in the construction of a strong maritime nation and the improvement of the global marine governance system.","PeriodicalId":12479,"journal":{"name":"Frontiers in Marine Science","volume":"15 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146222893","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 : 2026-02-19DOI: 10.3389/fmars.2026.1672272
Gregory Pelose, Johanna Calle-Triviño, Ariadna León, Stephanie Schopmeyer, Victor Galván, Austin Stoner, Cullin Burdett, Macarena Blanco-Pimentel
Caribbean coral reefs have experienced significant genetic loss from the effects of stony coral tissue loss disease (SCTLD). Since its emergence in 2014, SCTLD has spread from Florida to the Caribbean, affecting at least 25 species of scleractinian corals. Mitigation strategies are needed to combat this disease that has already altered reef functionality and driven highly susceptible species, such as Dendrogyra cylindrus , to functional extirpation in parts of their native range. Current treatment methods have been shown to be effective at quiescing SCTLD lesions, but they have limitations. This study examines the efficacy of a holistic 10-day ex situ SCTLD treatment approach aiming to arrest lesion progression, support tissue recovery, and promote survival. Coral fragments affected with SCTLD-like lesions from five Caribbean coral species received treatment and experienced 93% survivorship with no signs of reinfection for 352 days post-treatment. Non-treated (control) fragments experienced 70% mortality by day 26 of the study. The same 10-day treatment was conducted on day 26 for the remaining control fragments, resulting in 100% survivorship with no signs of reinfection for 336 days post-treatment. These results suggest that the ex situ treatment examined offers an effective and accessible tool to retain valuable genetic stock for SCTLD-susceptible species, particularly threatened and endangered taxa with already reduced genetic diversity.
{"title":"Ex situ treatment enhances survival and recovery from stony coral tissue loss disease in Caribbean corals","authors":"Gregory Pelose, Johanna Calle-Triviño, Ariadna León, Stephanie Schopmeyer, Victor Galván, Austin Stoner, Cullin Burdett, Macarena Blanco-Pimentel","doi":"10.3389/fmars.2026.1672272","DOIUrl":"https://doi.org/10.3389/fmars.2026.1672272","url":null,"abstract":"Caribbean coral reefs have experienced significant genetic loss from the effects of stony coral tissue loss disease (SCTLD). Since its emergence in 2014, SCTLD has spread from Florida to the Caribbean, affecting at least 25 species of scleractinian corals. Mitigation strategies are needed to combat this disease that has already altered reef functionality and driven highly susceptible species, such as <jats:italic>Dendrogyra cylindrus</jats:italic> , to functional extirpation in parts of their native range. Current treatment methods have been shown to be effective at quiescing SCTLD lesions, but they have limitations. This study examines the efficacy of a holistic 10-day <jats:italic>ex situ</jats:italic> SCTLD treatment approach aiming to arrest lesion progression, support tissue recovery, and promote survival. Coral fragments affected with SCTLD-like lesions from five Caribbean coral species received treatment and experienced 93% survivorship with no signs of reinfection for 352 days post-treatment. Non-treated (control) fragments experienced 70% mortality by day 26 of the study. The same 10-day treatment was conducted on day 26 for the remaining control fragments, resulting in 100% survivorship with no signs of reinfection for 336 days post-treatment. These results suggest that the <jats:italic>ex situ</jats:italic> treatment examined offers an effective and accessible tool to retain valuable genetic stock for SCTLD-susceptible species, particularly threatened and endangered taxa with already reduced genetic diversity.","PeriodicalId":12479,"journal":{"name":"Frontiers in Marine Science","volume":"120 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146222890","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 : 2026-02-19DOI: 10.3389/fmars.2025.1717640
Rémi Millot, Anaïs Esposito, Charlotte Gerbaud, Antoine Aiello, Yann Quilichini, Jean-José Filippi
Otolith shape analysis is an efficient tool for fish stock identification. However, due to insufficient research, it remains still poorly understood concerning the European eel ( Anguilla anguilla ), a highly migratory catadromous and panmictic species. The aim of this study is to discriminate the subpopulations of A. anguilla from rivers and two lagoons (three sites) from Corsican continental waters using morphological variations in otolith shape. The otolith shape was described by indices of shapes and by geometric morphometric shape, to understand how otolith morphology changes with eel growth and across contrasting habitats. In this study, the shape of each otolith (N = 305) was described with one landmark and ninety-nine semi-landmarks and by eight shape indices (form factor, aspect ratio, ellipticity, circularity, roundness, rectangularity, squareness and solidity). Results indicate that otolith shape is highly marked for the larger compared to smaller sizes, particularly for the individuals from the lagoons. The slight differences in the small otoliths appear to be due to the acquisition of the shape during the glass eel stage in the marine environment whereas the difference marked in the shape of the large otoliths would be due to the variability of environmental conditions, underlying marked change in otolith shape during growth.
{"title":"Environmental effects on otolith morphology variability of European eel, Anguilla anguilla (Linnaeus, 1758), for subpopulation discrimination in Corsica","authors":"Rémi Millot, Anaïs Esposito, Charlotte Gerbaud, Antoine Aiello, Yann Quilichini, Jean-José Filippi","doi":"10.3389/fmars.2025.1717640","DOIUrl":"https://doi.org/10.3389/fmars.2025.1717640","url":null,"abstract":"Otolith shape analysis is an efficient tool for fish stock identification. However, due to insufficient research, it remains still poorly understood concerning the European eel ( <jats:italic>Anguilla anguilla</jats:italic> ), a highly migratory catadromous and panmictic species. The aim of this study is to discriminate the subpopulations of <jats:italic>A. anguilla</jats:italic> from rivers and two lagoons (three sites) from Corsican continental waters using morphological variations in otolith shape. The otolith shape was described by indices of shapes and by geometric morphometric shape, to understand how otolith morphology changes with eel growth and across contrasting habitats. In this study, the shape of each otolith (N = 305) was described with one landmark and ninety-nine semi-landmarks and by eight shape indices (form factor, aspect ratio, ellipticity, circularity, roundness, rectangularity, squareness and solidity). Results indicate that otolith shape is highly marked for the larger compared to smaller sizes, particularly for the individuals from the lagoons. The slight differences in the small otoliths appear to be due to the acquisition of the shape during the glass eel stage in the marine environment whereas the difference marked in the shape of the large otoliths would be due to the variability of environmental conditions, underlying marked change in otolith shape during growth.","PeriodicalId":12479,"journal":{"name":"Frontiers in Marine Science","volume":"18 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146222867","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 : 2026-02-19DOI: 10.3389/fmars.2026.1779467
Na Li, Bin Zhang, Jianyu Li
Harmful algal blooms (HABs) are one of the major hazards in aquaculture activities, and modified clay is an effective approach for HAB prevention and control. Based on the DEM-VOF coupled model, this study investigates the synergistic coupling effects of factors such as particle density, particle size, stirring speed, and mixing time on the sedimentation and stirring efficiency of clay particles, analyzes the evolution characteristics of the multiphase flow field structure inside the stirring equipment, and evaluates the mixing effect of modified clay under different key parameter conditions. The results show that particle density is inversely proportional to mixing uniformity, with the lowest relative standard deviation (RSD) value obtained at a density of 1000 kg/m 3 . Reducing particle size can improve mixing efficiency, and the minimum RSD value is observed at a particle size of 3 mm. Stirring speed is significantly positively correlated with mixing performance, and the particle distribution is most uniform at 200 r/min. The mixing process reaches dynamic equilibrium at 25 seconds, and further extending the mixing time thereafter has limited improvement on performance. The synergistic coupling of 3 mm particle size and 200 r/min stirring speed (with 1000 kg/m 3 particle density and 25 s mixing time) achieves the best mixing effect, reducing RSD by 26.5% compared to the baseline condition. The research results provide a reference for the optimization of mixing parameters of modified clay mixing and spraying devices, and offer a theoretical basis for enhancing the operational efficiency of aquaculture HAB control equipment.
{"title":"Optimization of mixing performance of modified clay for harmful algal bloom control","authors":"Na Li, Bin Zhang, Jianyu Li","doi":"10.3389/fmars.2026.1779467","DOIUrl":"https://doi.org/10.3389/fmars.2026.1779467","url":null,"abstract":"Harmful algal blooms (HABs) are one of the major hazards in aquaculture activities, and modified clay is an effective approach for HAB prevention and control. Based on the DEM-VOF coupled model, this study investigates the synergistic coupling effects of factors such as particle density, particle size, stirring speed, and mixing time on the sedimentation and stirring efficiency of clay particles, analyzes the evolution characteristics of the multiphase flow field structure inside the stirring equipment, and evaluates the mixing effect of modified clay under different key parameter conditions. The results show that particle density is inversely proportional to mixing uniformity, with the lowest relative standard deviation (RSD) value obtained at a density of 1000 kg/m <jats:sup>3</jats:sup> . Reducing particle size can improve mixing efficiency, and the minimum RSD value is observed at a particle size of 3 mm. Stirring speed is significantly positively correlated with mixing performance, and the particle distribution is most uniform at 200 r/min. The mixing process reaches dynamic equilibrium at 25 seconds, and further extending the mixing time thereafter has limited improvement on performance. The synergistic coupling of 3 mm particle size and 200 r/min stirring speed (with 1000 kg/m <jats:sup>3</jats:sup> particle density and 25 s mixing time) achieves the best mixing effect, reducing RSD by 26.5% compared to the baseline condition. The research results provide a reference for the optimization of mixing parameters of modified clay mixing and spraying devices, and offer a theoretical basis for enhancing the operational efficiency of aquaculture HAB control equipment.","PeriodicalId":12479,"journal":{"name":"Frontiers in Marine Science","volume":"3 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146222889","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}
We investigated sex-specific morphometric, structural, and elemental traits of the shallow vent crab Xenograpsus testudinatus from the active shallow-water hydrothermal vents off Kueishan Island, Taiwan, addressing gaps in our understanding of how sex-specific adaptations manifest in extreme vent environments. From 583 collected specimens, 100 adult males and females were analyzed to compare exoskeletal morphology, morphometric indices, and elemental composition. Fifteen morphometric traits revealed pronounced sexual dimorphism, supported by discriminant, regression, and correlation analyses. Carapace width/length-weight relationships exhibited significant allometry pattern (P ≤ 0.00; except ABL P ≤ 0.81) that differed between sexes. Scanning electron microscopy (SEM) revealed that distinct sex-specific external and internal characteristics of the carapace, merus, propodus, and pereiopods, while transmission electron microscopy (TEM) showed unidirectional calcite-chitin organization in males versus multidirectional crystalline structures in females. Energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) further indicated sex-dependent elemental differentiation, with males exhibiting higher elemental concentrations. Collectively, these findings provide novel insights into the morphological, structural, and elemental bases of sexual dimorphism in X. testudinatus , revealing functional divergence and sex-specific adaptive strategies in shallow hydrothermal vent habitats advancing understanding beyond prior studies, which focused primarily on population and ecological patterns without resolving underlying structural and elemental differences.
{"title":"Sex-specific morphological and structural adaptations of the vent crab Xenograpsus testudinatus in a shallow water hydrothermal ecosystem","authors":"Subramani Thirunavukkarasu, Jishnu Panamoly Ayyappan, Poovazhagi Rajendran, Jiang-Shiou Hwang","doi":"10.3389/fmars.2026.1758001","DOIUrl":"https://doi.org/10.3389/fmars.2026.1758001","url":null,"abstract":"We investigated sex-specific morphometric, structural, and elemental traits of the shallow vent crab <jats:italic>Xenograpsus testudinatus</jats:italic> from the active shallow-water hydrothermal vents off Kueishan Island, Taiwan, addressing gaps in our understanding of how sex-specific adaptations manifest in extreme vent environments. From 583 collected specimens, 100 adult males and females were analyzed to compare exoskeletal morphology, morphometric indices, and elemental composition. Fifteen morphometric traits revealed pronounced sexual dimorphism, supported by discriminant, regression, and correlation analyses. Carapace width/length-weight relationships exhibited significant allometry pattern (P ≤ 0.00; except ABL P ≤ 0.81) that differed between sexes. Scanning electron microscopy (SEM) revealed that distinct sex-specific external and internal characteristics of the carapace, merus, propodus, and pereiopods, while transmission electron microscopy (TEM) showed unidirectional calcite-chitin organization in males versus multidirectional crystalline structures in females. Energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) further indicated sex-dependent elemental differentiation, with males exhibiting higher elemental concentrations. Collectively, these findings provide novel insights into the morphological, structural, and elemental bases of sexual dimorphism in <jats:italic>X. testudinatus</jats:italic> , revealing functional divergence and sex-specific adaptive strategies in shallow hydrothermal vent habitats advancing understanding beyond prior studies, which focused primarily on population and ecological patterns without resolving underlying structural and elemental differences.","PeriodicalId":12479,"journal":{"name":"Frontiers in Marine Science","volume":"280 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146222891","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 : 2026-02-18DOI: 10.3389/fmars.2026.1721762
Michael N. Burgess, Ryan Adams, James Knighton, Eric T. Schultz
Introduction Nursery habitats sustain populations only when individuals are able to move to habitats used by later life stages. For anadromous fishes such as Alewife ( Alosa pseudoharengus ), anthropogenic barriers and drought can disrupt this connectivity, entrapping juveniles and potentially depressing year-class success. We hypothesized that drought, by preventing juveniles prepared to emigrate from the nursery, maintains them at relatively high densities and keeps forage at relatively low levels, thus depressing growth rates and body condition. Methods Juvenile Alewife were sampled at the outlet of Bride Lake in East Lyme, Connecticut during a non-drought year and a prolonged drought year. We measured total length and dry mass, determined daily age from otoliths, quantified condition using the residual mass index, and estimated daily growth over the lifetime as well as in stanzas from 0 to 30 days, 0 to 100 days, and 70 to 100 days post hatch. Our sampling design enabled us to distinguish between year differences between early migrants and late migrants, who would be most affected by entrapment in the drought year. Results The hypothesis was supported by data. Seasonal increase in size of emigrating fish was 50% lower in the year of drought than the previous year. Late emigrants that had been entrapped had reduced condition, grew less over their lifetime, and had lower condition than their counterparts the previous year. While growth over the first 30 days post-hatch, prior to the onset of drought, did not differ between years, growth from 70 to 100 days post-hatch, coincident with a period of drought in the second year, was less than that in the previous year. Discussion Drought-induced entrapment curtailed growth and reduced size and condition of late-season juveniles, consistent with density-dependent competition, diminished forage, and declining autumn temperatures. Conservation of species of concern like the Alewife should prioritize maintaining juvenile connectivity. Future work should quantify entrapment-related mortality, extend drought forecasting to guide water management that minimizes the probability of entrapment, and integrate entrapment processes into population models to evaluate long-term consequences for Alewife recovery.
{"title":"Trapped in the nursery: poor growth and condition in juvenile alewives (Alosa pseudoharengus) stemming from drought-imposed loss of connectivity to marine habitat","authors":"Michael N. Burgess, Ryan Adams, James Knighton, Eric T. Schultz","doi":"10.3389/fmars.2026.1721762","DOIUrl":"https://doi.org/10.3389/fmars.2026.1721762","url":null,"abstract":"Introduction Nursery habitats sustain populations only when individuals are able to move to habitats used by later life stages. For anadromous fishes such as Alewife ( <jats:italic>Alosa pseudoharengus</jats:italic> ), anthropogenic barriers and drought can disrupt this connectivity, entrapping juveniles and potentially depressing year-class success. We hypothesized that drought, by preventing juveniles prepared to emigrate from the nursery, maintains them at relatively high densities and keeps forage at relatively low levels, thus depressing growth rates and body condition. Methods Juvenile Alewife were sampled at the outlet of Bride Lake in East Lyme, Connecticut during a non-drought year and a prolonged drought year. We measured total length and dry mass, determined daily age from otoliths, quantified condition using the residual mass index, and estimated daily growth over the lifetime as well as in stanzas from 0 to 30 days, 0 to 100 days, and 70 to 100 days post hatch. Our sampling design enabled us to distinguish between year differences between early migrants and late migrants, who would be most affected by entrapment in the drought year. Results The hypothesis was supported by data. Seasonal increase in size of emigrating fish was 50% lower in the year of drought than the previous year. Late emigrants that had been entrapped had reduced condition, grew less over their lifetime, and had lower condition than their counterparts the previous year. While growth over the first 30 days post-hatch, prior to the onset of drought, did not differ between years, growth from 70 to 100 days post-hatch, coincident with a period of drought in the second year, was less than that in the previous year. Discussion Drought-induced entrapment curtailed growth and reduced size and condition of late-season juveniles, consistent with density-dependent competition, diminished forage, and declining autumn temperatures. Conservation of species of concern like the Alewife should prioritize maintaining juvenile connectivity. Future work should quantify entrapment-related mortality, extend drought forecasting to guide water management that minimizes the probability of entrapment, and integrate entrapment processes into population models to evaluate long-term consequences for Alewife recovery.","PeriodicalId":12479,"journal":{"name":"Frontiers in Marine Science","volume":"90 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146222894","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 : 2026-02-18DOI: 10.3389/fmars.2026.1711689
J. L. García, J. Arístegui, M. J. Pazó, V. Vieitez dos Santos, N. Hernández-Hernández, Mar Nieto-Cid, M. D. Gelado-Caballero, A. Martínez-Marrero, X. A. Álvarez-Salgado
The Canary Islands region exhibits intense mesoscale activity, with eddies generated south the islands by perturbations of the Canary Current. After detachment, these eddies drift southwestward along the Canary Eddy Corridor (CEC), exporting their properties into the open ocean. While mesoscale dynamics in the region are well documented, associated submesoscale structures and their role in the production, transport and remineralization of organic matter remain poorly understood. We investigated meso- and submesoscale variability of dissolved organic carbon (DOC), suspended particulate organic carbon (POCsus), and the chromophoric (CDOM) and fluorescent (FDOM) fractions of dissolved organic matter (DOM), at high spatial resolution across four eddies sampled in 2022. In summer, we studied three newly formed or developing eddies: the cyclonic Garajonay eddy, trapped between La Gomera and El Hierro Islands and sustaining an intense phytoplankton bloom and a developing eddy pair south of Gran Canaria (cyclonic Nublo) and Tenerife (anticyclonic Anaga). In autumn, we sampled Bentayga, a five- month-old anticyclonic intrathermocline eddy drifting along the CEC. Cyclonic eddies showed decreasing DOC, CDOM and protein-like FDOM with age, whereas anticyclonic eddies accumulated humic-like FDOM. At the submesoscale, DOC decreased above the pycnocline and humic-like FDOM below it across the Nublo-Anaga front, while Bentayga exhibited pronounced intra-eddy submesoscale variability in DOC, CDOM, and humic-like FDOM. The residuals of the multiple regression with the thermohaline variables of apparent oxygen utilization (ΔAOU), ΔDOC, ΔPOC, ΔCDOM and ΔFDOM, are independent of water mass mixing and physical motions, and therefore retain the biogeochemical variability associated with local processes. Significant correlations among the residuals of DOC/AOU, CDOM/AOU and FDOM/AOU highlight the central role of DOM in local remineralization, which accounts for up to 68 ± 15% of mesopelagic oxygen demand, resulting in the accumulation of humic-like substances and substantial consumption of chromophoric and protein-like materials. Furthermore, the combined residual relationships of DOC/AOU and POCsus/AOU indicate that up to 88% of mesopelagic oxygen demand in the CEC is driven by local remineralization of DOC and POCsus, suggesting only a minor contribution from sinking POM. Our results demonstrate that meso- and submesoscale processes strongly regulate organic matter transport, remineralization and oxygen consumption in the CEC.
{"title":"Mesoscale and submesoscale variability of organic matter in island-induced eddies across their life cycle: implications for the biological carbon pump","authors":"J. L. García, J. Arístegui, M. J. Pazó, V. Vieitez dos Santos, N. Hernández-Hernández, Mar Nieto-Cid, M. D. Gelado-Caballero, A. Martínez-Marrero, X. A. Álvarez-Salgado","doi":"10.3389/fmars.2026.1711689","DOIUrl":"https://doi.org/10.3389/fmars.2026.1711689","url":null,"abstract":"The Canary Islands region exhibits intense mesoscale activity, with eddies generated south the islands by perturbations of the Canary Current. After detachment, these eddies drift southwestward along the Canary Eddy Corridor (CEC), exporting their properties into the open ocean. While mesoscale dynamics in the region are well documented, associated submesoscale structures and their role in the production, transport and remineralization of organic matter remain poorly understood. We investigated meso- and submesoscale variability of dissolved organic carbon (DOC), suspended particulate organic carbon (POCsus), and the chromophoric (CDOM) and fluorescent (FDOM) fractions of dissolved organic matter (DOM), at high spatial resolution across four eddies sampled in 2022. In summer, we studied three newly formed or developing eddies: the cyclonic Garajonay eddy, trapped between La Gomera and El Hierro Islands and sustaining an intense phytoplankton bloom and a developing eddy pair south of Gran Canaria (cyclonic Nublo) and Tenerife (anticyclonic Anaga). In autumn, we sampled Bentayga, a five- month-old anticyclonic intrathermocline eddy drifting along the CEC. Cyclonic eddies showed decreasing DOC, CDOM and protein-like FDOM with age, whereas anticyclonic eddies accumulated humic-like FDOM. At the submesoscale, DOC decreased above the pycnocline and humic-like FDOM below it across the Nublo-Anaga front, while Bentayga exhibited pronounced intra-eddy submesoscale variability in DOC, CDOM, and humic-like FDOM. The residuals of the multiple regression with the thermohaline variables of apparent oxygen utilization (ΔAOU), ΔDOC, ΔPOC, ΔCDOM and ΔFDOM, are independent of water mass mixing and physical motions, and therefore retain the biogeochemical variability associated with local processes. Significant correlations among the residuals of DOC/AOU, CDOM/AOU and FDOM/AOU highlight the central role of DOM in local remineralization, which accounts for up to 68 ± 15% of mesopelagic oxygen demand, resulting in the accumulation of humic-like substances and substantial consumption of chromophoric and protein-like materials. Furthermore, the combined residual relationships of DOC/AOU and POCsus/AOU indicate that up to 88% of mesopelagic oxygen demand in the CEC is driven by local remineralization of DOC and POCsus, suggesting only a minor contribution from sinking POM. Our results demonstrate that meso- and submesoscale processes strongly regulate organic matter transport, remineralization and oxygen consumption in the CEC.","PeriodicalId":12479,"journal":{"name":"Frontiers in Marine Science","volume":"180 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146222896","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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