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doi: 10.12284/hyxb2025089
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To enhance the accuracy and reliability of extreme wave height inference in ocean engineering, this study systematically compares the applicability and uncertainty of the annual maxima (AM) method and the peak over threshold (POT) method. Utilizing reanalysis wave data from two representative sites in Hangzhou Bay, annual maxima series and POT samples were constructed. These were modeled using the Generalized Extreme Value (GEV) distribution and the generalized Pareto distribution (GPD), respectively; for the POT method, threshold selection was optimized via a tail least squares error (TLSE) criterion. Confidence intervals for model parameters and return period level wave height estimates were further quantified using both the Delta method and the Bootstrap method. The results demonstrate that for high return periods, the POT method yields higher wave height estimates with narrower confidence intervals, rendering it more suitable for engineering design scenarios sensitive to extreme events. In uncertainty analysis, the Bootstrap method more comprehensively captures model uncertainty compared to the Delta method. This work establishes a more robust analytical framework and inferential basis for extreme wave height modeling.
To enhance the accuracy and reliability of extreme wave height inference in ocean engineering, this study systematically compares the applicability and uncertainty of the annual maxima (AM) method and the peak over threshold (POT) method. Utilizing reanalysis wave data from two representative sites in Hangzhou Bay, annual maxima series and POT samples were constructed. These were modeled using the Generalized Extreme Value (GEV) distribution and the generalized Pareto distribution (GPD), respectively; for the POT method, threshold selection was optimized via a tail least squares error (TLSE) criterion. Confidence intervals for model parameters and return period level wave height estimates were further quantified using both the Delta method and the Bootstrap method. The results demonstrate that for high return periods, the POT method yields higher wave height estimates with narrower confidence intervals, rendering it more suitable for engineering design scenarios sensitive to extreme events. In uncertainty analysis, the Bootstrap method more comprehensively captures model uncertainty compared to the Delta method. This work establishes a more robust analytical framework and inferential basis for extreme wave height modeling.
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The tropical Indo-Pacific interocean water exchange, which serves as a critical link in the oceanic thermohaline circulation and the global climate system, is one of the most hotspot oceanography and climate science. Previous observation show that the interocean exchange exhibits a distinct vertical structure, with its subsurface velocity maximum (SVM) occurring in the subsurface layer rather than the surface layer. However, existing studies have insufficient understanding of the variability of this structure as well as the underlying mechanisms. Meanwhile, the impact of SVM induced heat and freshwater transport on the Indo-Pacific climate is unclear. Based on mooring observed sea water velocity profiles, we have identified that the SVM characteristics originating from the Pacific Western Boundary Currents can propagate into the South China Sea and the Indonesian Seas, and persist along the main route of the Indonesian Throughflow from Makassar to the Lombok Strait. We propose the scientific hypothesis that the substantial freshwater and heat fluxes in the Maritime Continent, along with the propagation of equatorial planetary wave, are the key mechanisms governing the maintenance and variability of the SVM in interoceanic exchange. Here, we tried to propose an approach to investigate the SVM and its climate effect, based on observations, numerical simulations, and theoretical analyses. The research outcomes are of great significance for deepening the understanding of the interactions between the tropical Pacific and Indian Oceans, as well as air-sea interactions, and will provide theoretical support for enhancing the predictability of the Indo-Pacific climate system.
The tropical Indo-Pacific interocean water exchange, which serves as a critical link in the oceanic thermohaline circulation and the global climate system, is one of the most hotspot oceanography and climate science. Previous observation show that the interocean exchange exhibits a distinct vertical structure, with its subsurface velocity maximum (SVM) occurring in the subsurface layer rather than the surface layer. However, existing studies have insufficient understanding of the variability of this structure as well as the underlying mechanisms. Meanwhile, the impact of SVM induced heat and freshwater transport on the Indo-Pacific climate is unclear. Based on mooring observed sea water velocity profiles, we have identified that the SVM characteristics originating from the Pacific Western Boundary Currents can propagate into the South China Sea and the Indonesian Seas, and persist along the main route of the Indonesian Throughflow from Makassar to the Lombok Strait. We propose the scientific hypothesis that the substantial freshwater and heat fluxes in the Maritime Continent, along with the propagation of equatorial planetary wave, are the key mechanisms governing the maintenance and variability of the SVM in interoceanic exchange. Here, we tried to propose an approach to investigate the SVM and its climate effect, based on observations, numerical simulations, and theoretical analyses. The research outcomes are of great significance for deepening the understanding of the interactions between the tropical Pacific and Indian Oceans, as well as air-sea interactions, and will provide theoretical support for enhancing the predictability of the Indo-Pacific climate system.
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Mangrove ecosystems play a pivotal role in sustaining coastal ecological stability. However, under the compounded influences of climate change and human disturbance, these ecosystems are experiencing severe degradation. Artificial afforestation has emerged as the predominant restoration strategy. This study focuses on young mangrove plantations along the Guangxi coastline, investigating the ecological strategy differences among various species within these artificial plantations. Utilizing plant functional traits and the CSR (Competitor, Stress-tolerator, Ruderal) strategy theory, the study explores the relationships between functional traits, CSR strategies, and the driving factors behind these ecological patterns. The findings reveal that: (1) There are significant variations in CSR strategies among different species. Aegiceras corniculatum and Kandelia obovata predominantly exhibit the S strategy, Bruguiera gymnorrhiza is more inclined towards the C strategy, while Avicennia marina demonstrates a relatively balanced distribution across the CSR spectrum. (2) A significant correlation exists between CSR strategies and functional trait indicators. Specifically, the C strategy shows a significant positive correlation with chlorophyll content and tree height increment, and a significant negative correlation with leaf phosphorus content. The S strategy is significantly negatively correlated with tree height increment. The R strategy exhibits significant positive correlations with chlorophyll content and tree height increment, and significant negative correlations with leaf nitrogen content and leaf phosphorus content. (3) Flood time and depth are identified as key environmental factors driving the variation in CSR strategies within the young mangrove plantations. This study substantiates the applicability of CSR theory in intertidal artificial mangrove ecosystems, elucidating the mechanistic connections between plant adaptive strategies and ecological niche occupation. The results provide both theoretical insights and practical guidance for optimizing species selection and enhancing the efficiency of mangrove ecosystem restoration.
Mangrove ecosystems play a pivotal role in sustaining coastal ecological stability. However, under the compounded influences of climate change and human disturbance, these ecosystems are experiencing severe degradation. Artificial afforestation has emerged as the predominant restoration strategy. This study focuses on young mangrove plantations along the Guangxi coastline, investigating the ecological strategy differences among various species within these artificial plantations. Utilizing plant functional traits and the CSR (Competitor, Stress-tolerator, Ruderal) strategy theory, the study explores the relationships between functional traits, CSR strategies, and the driving factors behind these ecological patterns. The findings reveal that: (1) There are significant variations in CSR strategies among different species. Aegiceras corniculatum and Kandelia obovata predominantly exhibit the S strategy, Bruguiera gymnorrhiza is more inclined towards the C strategy, while Avicennia marina demonstrates a relatively balanced distribution across the CSR spectrum. (2) A significant correlation exists between CSR strategies and functional trait indicators. Specifically, the C strategy shows a significant positive correlation with chlorophyll content and tree height increment, and a significant negative correlation with leaf phosphorus content. The S strategy is significantly negatively correlated with tree height increment. The R strategy exhibits significant positive correlations with chlorophyll content and tree height increment, and significant negative correlations with leaf nitrogen content and leaf phosphorus content. (3) Flood time and depth are identified as key environmental factors driving the variation in CSR strategies within the young mangrove plantations. This study substantiates the applicability of CSR theory in intertidal artificial mangrove ecosystems, elucidating the mechanistic connections between plant adaptive strategies and ecological niche occupation. The results provide both theoretical insights and practical guidance for optimizing species selection and enhancing the efficiency of mangrove ecosystem restoration.
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Eodemus subtilis is an intertidal to shallow-water crab species belonging to the family Portunidae (Order: Decapoda), primarily distributed along the southeastern coastal waters of China. In this study, we conducted a comprehensive characterization of its mitochondrial genome using high-throughput sequencing and bioinformatic analyses. The complete mitochondrial genome of E. subtilis is 15,878 bp in length and comprises 13 protein-coding genes (PCGs), 22 tRNA genes, 2 rRNA genes, and one non-coding control region. Notably, 24 of these genes are encoded on the heavy strand (H-strand). The mitochondrial genome exhibits a strong A+T bias (69.81%), with negative AT-skew (-0.021) and GC-skew (-0.233). Analysis of relative synonymous codon usage (RSCU) revealed that the codons UCU (Ser2) and UUA (Leu2) are highly frequent, with preferred codons predominantly ending in A/T. The gene arrangement in E. subtilis is highly conserved, maintaining the ancestral gene order typical of Brachyura crabs, with no observed rearrangements. Selection pressure analysis (Ka/Ks) of the 13 PCGs across Portunidae crabs indicated that 11 genes (excluding COIII and ND1) underwent purifying selection. Phylogenetic and divergence time estimation analyses demonstrated that E. subtilis forms a clade with Monomia gladiator, with an estimated divergence time of approximately 44.34 million years ago (Mya). These findings provide significant new insights into the evolutionary history and molecular adaptations of E. subtilis within Portunidae, as well as into the evolutionary relationships of Portunidae within Brachyura.
Eodemus subtilis is an intertidal to shallow-water crab species belonging to the family Portunidae (Order: Decapoda), primarily distributed along the southeastern coastal waters of China. In this study, we conducted a comprehensive characterization of its mitochondrial genome using high-throughput sequencing and bioinformatic analyses. The complete mitochondrial genome of E. subtilis is 15,878 bp in length and comprises 13 protein-coding genes (PCGs), 22 tRNA genes, 2 rRNA genes, and one non-coding control region. Notably, 24 of these genes are encoded on the heavy strand (H-strand). The mitochondrial genome exhibits a strong A+T bias (69.81%), with negative AT-skew (-0.021) and GC-skew (-0.233). Analysis of relative synonymous codon usage (RSCU) revealed that the codons UCU (Ser2) and UUA (Leu2) are highly frequent, with preferred codons predominantly ending in A/T. The gene arrangement in E. subtilis is highly conserved, maintaining the ancestral gene order typical of Brachyura crabs, with no observed rearrangements. Selection pressure analysis (Ka/Ks) of the 13 PCGs across Portunidae crabs indicated that 11 genes (excluding COIII and ND1) underwent purifying selection. Phylogenetic and divergence time estimation analyses demonstrated that E. subtilis forms a clade with Monomia gladiator, with an estimated divergence time of approximately 44.34 million years ago (Mya). These findings provide significant new insights into the evolutionary history and molecular adaptations of E. subtilis within Portunidae, as well as into the evolutionary relationships of Portunidae within Brachyura.
, Available online ,
doi: 10.12284/hyxb202500-0
Abstract:
Isognomonids are widely distributed in the intertidal zones of tropical and subtropical regions, where they play important ecological and economic roles. However, due to significant morphological variability influenced by environmental factors, morphology-based taxonomic classifications of Isognomonidae remain contentious. In this study, mitochondrial COI sequences were obtained from specimens of Isognomonidae collected along the Guangdong coast, supplemented with homologous sequences retrieved from GenBank to construct phylogenetic trees, and DNA molecular barcoding techniques been applied to analyze the species of Isognomonidae distributed in the Guangdong coast. Results demonstrated strong support for the monophyly of Isognomonidae. total of 125 COI sequences yielded 68 haplotypes, which clustered into 16 well-supported species-level units, although their evolutionary relationships remain uncertain. Intraspecific Kimura 2-parameter (K2P) genetic distances ranged from 0 to 0.009, while interspecific distances ranged from 0.029 to 0.595. The average nucleotide composition of the COI fragments showed 55.0% A+T and 45.0% C+G, with variation observed among species. Five species were identified from Guangdong samples, including the previously recorded Isognomon nucleus and four cryptic species. This study confirms that DNA barcoding is an effective tool for supporting and revising the taxonomy of Isognomonidae and reveals cryptic diversity, which is crucial for marine biodiversity conservation.
Isognomonids are widely distributed in the intertidal zones of tropical and subtropical regions, where they play important ecological and economic roles. However, due to significant morphological variability influenced by environmental factors, morphology-based taxonomic classifications of Isognomonidae remain contentious. In this study, mitochondrial COI sequences were obtained from specimens of Isognomonidae collected along the Guangdong coast, supplemented with homologous sequences retrieved from GenBank to construct phylogenetic trees, and DNA molecular barcoding techniques been applied to analyze the species of Isognomonidae distributed in the Guangdong coast. Results demonstrated strong support for the monophyly of Isognomonidae. total of 125 COI sequences yielded 68 haplotypes, which clustered into 16 well-supported species-level units, although their evolutionary relationships remain uncertain. Intraspecific Kimura 2-parameter (K2P) genetic distances ranged from 0 to 0.009, while interspecific distances ranged from 0.029 to 0.595. The average nucleotide composition of the COI fragments showed 55.0% A+T and 45.0% C+G, with variation observed among species. Five species were identified from Guangdong samples, including the previously recorded Isognomon nucleus and four cryptic species. This study confirms that DNA barcoding is an effective tool for supporting and revising the taxonomy of Isognomonidae and reveals cryptic diversity, which is crucial for marine biodiversity conservation.
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Terrain measurement data in shallow water areas provide essential support for marine resource development and water resource investigation and management, making them a focal point in marine surveying and related fields. Airborne LiDAR Bathymetry (ALB) is a high-precision, high-efficiency, and highly mobile measurement technology particularly suited for topographic surveys in shallow water regions. To address the inefficiencies and high costs associated with traditional on-site sampling methods ( Secchi disk transparency measurements) for estimating maximum bathymetric depth using airborne LiDAR, this study proposes a novel method for maximum depth estimation without on-site sampling, integrating satellite remote sensing water color data products with waveform modeling. By retrieving the diffuse attenuation coefficient at 532 nm through inversion of NASA Ocean Color’s Kd(490) product and combining it with a physical model of LiDAR bathymetric echo signals, the method constructs a superimposed waveform model incorporating contributions from the water surface, water column, seabed, and noise. A peak detection algorithm is then employed to automate maximum depth determination. Experimental results from Jiaozhou Bay in Qingdao City, Shandong Province, and Tuosu Lake in Delingha City, Qinghai Province, demonstrate that the proposed method achieves maximum depth estimation with deviations not exceeding 0.4 m and relative errors within 5%, validating its effectiveness. By replacing on-site transparency measurements with satellite remote sensing water color data products, the proposed method eliminates the need for field sampling, significantly reducing the operational costs of airborne LiDAR bathymetry while providing efficient technical support for shallow water mapping and water resource investigations.
Terrain measurement data in shallow water areas provide essential support for marine resource development and water resource investigation and management, making them a focal point in marine surveying and related fields. Airborne LiDAR Bathymetry (ALB) is a high-precision, high-efficiency, and highly mobile measurement technology particularly suited for topographic surveys in shallow water regions. To address the inefficiencies and high costs associated with traditional on-site sampling methods ( Secchi disk transparency measurements) for estimating maximum bathymetric depth using airborne LiDAR, this study proposes a novel method for maximum depth estimation without on-site sampling, integrating satellite remote sensing water color data products with waveform modeling. By retrieving the diffuse attenuation coefficient at 532 nm through inversion of NASA Ocean Color’s Kd(490) product and combining it with a physical model of LiDAR bathymetric echo signals, the method constructs a superimposed waveform model incorporating contributions from the water surface, water column, seabed, and noise. A peak detection algorithm is then employed to automate maximum depth determination. Experimental results from Jiaozhou Bay in Qingdao City, Shandong Province, and Tuosu Lake in Delingha City, Qinghai Province, demonstrate that the proposed method achieves maximum depth estimation with deviations not exceeding 0.4 m and relative errors within 5%, validating its effectiveness. By replacing on-site transparency measurements with satellite remote sensing water color data products, the proposed method eliminates the need for field sampling, significantly reducing the operational costs of airborne LiDAR bathymetry while providing efficient technical support for shallow water mapping and water resource investigations.
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Abstract:
To investigate the resource utilization and interspecific relationships of macrobenthic fauna in the rocky intertidal zones of Zhejiang Province, surveys were conducted at 10 rocky intertidal sites from March 2024 to April 2025. The index of relative importance (IRI), niche breadth (Bi), niche overlap (Oik), variance ratio (VR), chi-square test, association coefficient (AC), percentage of co-occurrence (PC), Spearman rank correlation, and redundancy analysis (RDA) were applied to analyze the ecological niches, interspecific associations, and relationships between dominant species and environmental factors. The results showed: (1) the rocky intertidal zones of Zhejiang host a rich diversity of species, with 17 dominant species identified (IRI > 100); (2) Thais clavigera and Nodilittorina exigua had wide niche breadths and were classified as wide niche breadth species, while Chthamalus challengeri and Crassostrea angulata were narrow niche breadth species. (3) significant niche overlap was observed among T. clavigera, Littorina brevicula, Thais luteostoma, and Notoacmea schrenckii, indicating intense resource competition; (4) salinity and chl-a were key factors influencing species abundance, and a significant negative correlation was found between salinity and chl-a. (5) the community structure of macrobenthos in the rocky intertidal zones appeared to be loosely organized and compositionally unstable, suggesting that it may currently be in a stage of successional recovery.
To investigate the resource utilization and interspecific relationships of macrobenthic fauna in the rocky intertidal zones of Zhejiang Province, surveys were conducted at 10 rocky intertidal sites from March 2024 to April 2025. The index of relative importance (IRI), niche breadth (Bi), niche overlap (Oik), variance ratio (VR), chi-square test, association coefficient (AC), percentage of co-occurrence (PC), Spearman rank correlation, and redundancy analysis (RDA) were applied to analyze the ecological niches, interspecific associations, and relationships between dominant species and environmental factors. The results showed: (1) the rocky intertidal zones of Zhejiang host a rich diversity of species, with 17 dominant species identified (IRI > 100); (2) Thais clavigera and Nodilittorina exigua had wide niche breadths and were classified as wide niche breadth species, while Chthamalus challengeri and Crassostrea angulata were narrow niche breadth species. (3) significant niche overlap was observed among T. clavigera, Littorina brevicula, Thais luteostoma, and Notoacmea schrenckii, indicating intense resource competition; (4) salinity and chl-a were key factors influencing species abundance, and a significant negative correlation was found between salinity and chl-a. (5) the community structure of macrobenthos in the rocky intertidal zones appeared to be loosely organized and compositionally unstable, suggesting that it may currently be in a stage of successional recovery.
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Abstract:
The Madden–Julian Oscillation (MJO), as the primary mode of tropical intraseasonal variability, plays a critical role in improving subseasonal prediction skill. However, due to its multi-scale evolutionary characteristics and highly nonlinear dynamical processes, existing prediction methods still struggle to effectively capture the complex spatiotemporal structure of MJO. To address this issue, we propose a novel prediction model named MISM (Multi-modal data and Integrated Spatiotemporal features for MJO prediction), which integrates multimodal inputs and spatiotemporal feature extraction. The model jointly leverages historical Real-time Multivariate MJO (RMM) indices and multiple meteorological variables as inputs. It incorporates a spatial feature extraction module based on Squeeze-and-Excitation (SE) blocks, convolu-tional layers, and the Swin Transformer, as well as an autoregressive attention mechanism for nonlinear temporal modeling. Experimental results demonstrate that the MISM model extends predictive skill to beyond 30 days and shows overall superior performance compared with traditional dynamical and statistical methods in long-lead forecasts beyond 25 days. Furthermore, saliency maps are utilized to analyze the contribution regions of meteorological factors. The results reveal that the western Pacific and the Indonesian archipelago consistently exhibit high sensitivity across different lead times, with oceanic regions generally contributing more than land areas. Water vapor and sea surface temperature anomalies play a more prominent role in short- to medium-term forecasts, while low-level wind fields and convective activity contribute more significantly in longer-term forecasts. High-level circulation exerts a stable influence across all lead times, highlighting the model’s ability to capture the mechanisms of MJO evolution.
The Madden–Julian Oscillation (MJO), as the primary mode of tropical intraseasonal variability, plays a critical role in improving subseasonal prediction skill. However, due to its multi-scale evolutionary characteristics and highly nonlinear dynamical processes, existing prediction methods still struggle to effectively capture the complex spatiotemporal structure of MJO. To address this issue, we propose a novel prediction model named MISM (Multi-modal data and Integrated Spatiotemporal features for MJO prediction), which integrates multimodal inputs and spatiotemporal feature extraction. The model jointly leverages historical Real-time Multivariate MJO (RMM) indices and multiple meteorological variables as inputs. It incorporates a spatial feature extraction module based on Squeeze-and-Excitation (SE) blocks, convolu-tional layers, and the Swin Transformer, as well as an autoregressive attention mechanism for nonlinear temporal modeling. Experimental results demonstrate that the MISM model extends predictive skill to beyond 30 days and shows overall superior performance compared with traditional dynamical and statistical methods in long-lead forecasts beyond 25 days. Furthermore, saliency maps are utilized to analyze the contribution regions of meteorological factors. The results reveal that the western Pacific and the Indonesian archipelago consistently exhibit high sensitivity across different lead times, with oceanic regions generally contributing more than land areas. Water vapor and sea surface temperature anomalies play a more prominent role in short- to medium-term forecasts, while low-level wind fields and convective activity contribute more significantly in longer-term forecasts. High-level circulation exerts a stable influence across all lead times, highlighting the model’s ability to capture the mechanisms of MJO evolution.
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Since 2008, the South Yellow Sea has been persistently affected by green tide disasters caused by Ulva prolifera, while since 2009, the North Yellow Sea has frequently experienced large-scale macroalgal accumulations. The massive outbreaks of green tides severely damage marine ecosystems and threaten coastal ecological balance and economic structures. However, research on the differences in green tide outbreaks between the South and North Yellow Sea remains limited. This study systematically compares the differences in Ulva prolifera between the two regions from two complementary dimensions—spatiotemporal distribution patterns and genetic basis—using multi-source remote sensing data, UAV monitoring, and molecular biology methods. The results indicate: (1) Significant differences in outbreak timing and scale. Ulva prolifera in the South Yellow Sea first appears in May, reaches its maximum coverage in mid-to-late June, and gradually disappears between July and August, with an entire life cycle lasting approximately 50–90 days. In contrast, Ulva prolifera in the North Yellow Sea is locally sourced, appearing in the coastal waters of Yantai from late June to early July and gradually disappearing in August. It exhibits smaller coverage areas and shorter duration compared to the South Yellow Sea. In recent years, the outbreak area in the South Yellow Sea has consistently exceeded 200 km2, while that in the North Yellow Sea has remained within 2,000 m2, significantly smaller. (2) From 2018 to 2024, the migration paths of Ulva prolifera in the South Yellow Sea can be categorized into two types: northward drifting and northward-then-southward drifting. Spatially, Ulva prolifera blooms in the South Yellow Sea exhibit large-scale, continuous aggregation, whereas those in the North Yellow Sea are characterized by localized, scattered distributions. Ulva prolifera in the South Yellow Sea originates from the Subei Shoal, drifting northward with monsoon winds and ocean currents to accumulate along the southern coast of the Shandong Peninsula. In the North Yellow Sea, Ulva prolifera is mainly concentrated in areas such as the Jinshatan Beach in Yantai Development Zone and the estuary of the Guangdang River in Laishan District, with no large-scale drifting observed. (3) ITS gene sequencing reveals that Ulva prolifera in the North Yellow Sea along the Yantai coast belongs to a novel genetic strain (ITS JST3), which is distinctly different from the South Yellow Sea strain in terms of its light green, short, clustered morphology and underdeveloped air sac structures. By integrating macroscopic spatiotemporal patterns with microscopic genetic foundations, this study systematically demonstrates that the green tides in the South and North Yellow Sea are independent ecological events driven by different mechanisms, providing important insights for targeted regional prevention and control of green tides.
Since 2008, the South Yellow Sea has been persistently affected by green tide disasters caused by Ulva prolifera, while since 2009, the North Yellow Sea has frequently experienced large-scale macroalgal accumulations. The massive outbreaks of green tides severely damage marine ecosystems and threaten coastal ecological balance and economic structures. However, research on the differences in green tide outbreaks between the South and North Yellow Sea remains limited. This study systematically compares the differences in Ulva prolifera between the two regions from two complementary dimensions—spatiotemporal distribution patterns and genetic basis—using multi-source remote sensing data, UAV monitoring, and molecular biology methods. The results indicate: (1) Significant differences in outbreak timing and scale. Ulva prolifera in the South Yellow Sea first appears in May, reaches its maximum coverage in mid-to-late June, and gradually disappears between July and August, with an entire life cycle lasting approximately 50–90 days. In contrast, Ulva prolifera in the North Yellow Sea is locally sourced, appearing in the coastal waters of Yantai from late June to early July and gradually disappearing in August. It exhibits smaller coverage areas and shorter duration compared to the South Yellow Sea. In recent years, the outbreak area in the South Yellow Sea has consistently exceeded 200 km2, while that in the North Yellow Sea has remained within 2,000 m2, significantly smaller. (2) From 2018 to 2024, the migration paths of Ulva prolifera in the South Yellow Sea can be categorized into two types: northward drifting and northward-then-southward drifting. Spatially, Ulva prolifera blooms in the South Yellow Sea exhibit large-scale, continuous aggregation, whereas those in the North Yellow Sea are characterized by localized, scattered distributions. Ulva prolifera in the South Yellow Sea originates from the Subei Shoal, drifting northward with monsoon winds and ocean currents to accumulate along the southern coast of the Shandong Peninsula. In the North Yellow Sea, Ulva prolifera is mainly concentrated in areas such as the Jinshatan Beach in Yantai Development Zone and the estuary of the Guangdang River in Laishan District, with no large-scale drifting observed. (3) ITS gene sequencing reveals that Ulva prolifera in the North Yellow Sea along the Yantai coast belongs to a novel genetic strain (ITS JST3), which is distinctly different from the South Yellow Sea strain in terms of its light green, short, clustered morphology and underdeveloped air sac structures. By integrating macroscopic spatiotemporal patterns with microscopic genetic foundations, this study systematically demonstrates that the green tides in the South and North Yellow Sea are independent ecological events driven by different mechanisms, providing important insights for targeted regional prevention and control of green tides.
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Abstract:
The Changjiang Estuary-East China Sea (ECS) shelf system is one of the world's largest seasonal hypoxia zones, significantly influencing regional biogeochemical and ecological processes. However, the variation processes and controlling mechanisms during its autumn decay phase remain a limited understanding. Using multidisciplinary survey data collected from the ECS shelf in September 2017, this study documents the spatial distribution of the hypoxia zone and the characteristics of physical and chemical environment in autumn. And through analysis of hydrodynamic and biogeochemical processes, the controlling factors of hypoxia are further investigated. Results reveal a northeast-southwest oriented bottom dissolved oxygen (DO) minimum zone (DO ＜ 4 mg·L−1, minimum of 2.52 mg·L−1) over the mid-shelf off Zhejiang within the 40-60-m isobath, showing a certain uplift tendency on its nearshore side. This hypoxia zone is basically within the influence area of the Kuroshio subsurface water (KSSW) nearshore branch (also known as the bottom water of the Taiwan Warm Current). The pycnocline and front structures near the outer edge of this branch restrict oxygen exchange between the hypoxic water and the overlying and surrounding water, providing hydrodynamic conditions that sustain the hypoxia into the autumn. The upwelling of the KSSW nearshore branch is identified as a major cause of the mid-water hypoxia over the inner shelf. Furthermore, the nutrients transported by southeastward offshore expansion of low-salinity water and upwelling at Zhejiang coast serve as a critical material foundation for in situ primary production, which partly modulates the intensity of the hypoxia zone. It is also shown that as the KSSW nearshore branch retreats southward and seaward in autumn, the core of the hypoxia zone moves correspondingly southward and offshore, eventually dissipating. This study provides an important insight into the decay processes and controlling mechanisms of the hypoxia zone in the Changjiang Estuary-ECS shelf system during autumn.
The Changjiang Estuary-East China Sea (ECS) shelf system is one of the world's largest seasonal hypoxia zones, significantly influencing regional biogeochemical and ecological processes. However, the variation processes and controlling mechanisms during its autumn decay phase remain a limited understanding. Using multidisciplinary survey data collected from the ECS shelf in September 2017, this study documents the spatial distribution of the hypoxia zone and the characteristics of physical and chemical environment in autumn. And through analysis of hydrodynamic and biogeochemical processes, the controlling factors of hypoxia are further investigated. Results reveal a northeast-southwest oriented bottom dissolved oxygen (DO) minimum zone (DO ＜ 4 mg·L−1, minimum of 2.52 mg·L−1) over the mid-shelf off Zhejiang within the 40-60-m isobath, showing a certain uplift tendency on its nearshore side. This hypoxia zone is basically within the influence area of the Kuroshio subsurface water (KSSW) nearshore branch (also known as the bottom water of the Taiwan Warm Current). The pycnocline and front structures near the outer edge of this branch restrict oxygen exchange between the hypoxic water and the overlying and surrounding water, providing hydrodynamic conditions that sustain the hypoxia into the autumn. The upwelling of the KSSW nearshore branch is identified as a major cause of the mid-water hypoxia over the inner shelf. Furthermore, the nutrients transported by southeastward offshore expansion of low-salinity water and upwelling at Zhejiang coast serve as a critical material foundation for in situ primary production, which partly modulates the intensity of the hypoxia zone. It is also shown that as the KSSW nearshore branch retreats southward and seaward in autumn, the core of the hypoxia zone moves correspondingly southward and offshore, eventually dissipating. This study provides an important insight into the decay processes and controlling mechanisms of the hypoxia zone in the Changjiang Estuary-ECS shelf system during autumn.
, Available online ,
doi: 10.12284/hyxb2025-05
Abstract:
Water quality monitoring in marine ranching areas is of vital importance for their high-quality and sustainable development. Chlorophyll a (Chla), an important indicator of phytoplankton biomass and water eutrophication, plays a key role in environmental assessment and risk management. Satellite remote sensing, characterized by rapid observation and wide spatiotemporal coverage, offers significant advantages. However, dedicated remote sensing products for marine ranching areas remain lacking, and aquaculture facilities can interfere with satellite signals, introducing errors in the remote sensing inversion of Chla concentration. Using the Gouqi Island marine ranching area (a mussel aquaculture ranching area) in Shengsi, Zhejiang Province, as a case study, Chla concentration inversion models for Landsat8 OLI images were constructed based on in situ data acquired during multiple cruises. The influence of aquaculture facilities on remote sensing reflectance was analyzed and effectively corrected. Validation results demonstrated the good performance of the inversion model. Using the corrected reflectance data, high-precision Chla concentration products were retrieved for the mussel aquaculture ranching area and adjacent waters, and their spatiotemporal variations and potential influencing factors were examined. This study provides methodological support and a technical foundation for high-precision remote sensing monitoring of Chla concentration in mussel aquaculture ranching areas.
Water quality monitoring in marine ranching areas is of vital importance for their high-quality and sustainable development. Chlorophyll a (Chla), an important indicator of phytoplankton biomass and water eutrophication, plays a key role in environmental assessment and risk management. Satellite remote sensing, characterized by rapid observation and wide spatiotemporal coverage, offers significant advantages. However, dedicated remote sensing products for marine ranching areas remain lacking, and aquaculture facilities can interfere with satellite signals, introducing errors in the remote sensing inversion of Chla concentration. Using the Gouqi Island marine ranching area (a mussel aquaculture ranching area) in Shengsi, Zhejiang Province, as a case study, Chla concentration inversion models for Landsat8 OLI images were constructed based on in situ data acquired during multiple cruises. The influence of aquaculture facilities on remote sensing reflectance was analyzed and effectively corrected. Validation results demonstrated the good performance of the inversion model. Using the corrected reflectance data, high-precision Chla concentration products were retrieved for the mussel aquaculture ranching area and adjacent waters, and their spatiotemporal variations and potential influencing factors were examined. This study provides methodological support and a technical foundation for high-precision remote sensing monitoring of Chla concentration in mussel aquaculture ranching areas.
, Available online ,
doi: 10.12284/hyxb2025-02
Abstract:
Understanding regional tidal processes is of great significance for ensuring the safety of marine engineering construction and mitigating marine environmental pollution. In recent years, frequent marine development activities, particularly land reclamation projects, have been implemented in Sanmen Bay, resulting in measurable alterations to the hydrodynamic environment within the bay. In this study, a three-dimensional unstructured-grid Finite Volume Community Ocean Model (FVCOM) was developed for Sanmen Bay and its adjacent waters. The model was validated against observed current data from three stations and tidal elevation data from two stations at the bay mouth. Based on this validation, the tidal and current distribution characteristics as well as tidal wave propagation in Sanmen Bay and its adjacent waters were analyzed. Furthermore, by comparing the results of sensitivity experiments under the 2000 and 2020 shoreline conditions, the impacts of shoreline changes induced by reclamation on the hydrodynamic environment within the bay were quantitatively assessed. Results demonstrate that the study area exhibits predominantly semidiurnal tides, with the M2 constituent showing the largest amplitude (1.5-2 m), followed by S2, both propagating from southeast to northwest. The tidal currents within the bay are primarily rectilinear, with the maximum semi-major axis of the M2 tidal current ellipse reaching 1 m/s. Residual currents in topographically complex regions can reach 0.4 m/s, generally flowing northeastward into the bay and southwestward out of the bay. The tidal energy flux density gradually decays during its propagation toward the bay mouth, weakening to about 20 kW/m at the entrance. Comparative analysis reveals that shoreline modifications have enhanced flood dominance within the bay, reduced M2 amplitude by 0.2 m in the bay-head region. The residual current direction has reversed from outward to inward flow along the northeastern bay mouth, while tidal energy flux density decreased by approximately 40 kW/m in some deeper channels. The numerical simulations show good agreement with field measurements, effectively reflecting recent hydrodynamic conditions in Sanmen Bay and providing scientific support for studying the impact of typical coastal reclamation on hydrodynamics.
Understanding regional tidal processes is of great significance for ensuring the safety of marine engineering construction and mitigating marine environmental pollution. In recent years, frequent marine development activities, particularly land reclamation projects, have been implemented in Sanmen Bay, resulting in measurable alterations to the hydrodynamic environment within the bay. In this study, a three-dimensional unstructured-grid Finite Volume Community Ocean Model (FVCOM) was developed for Sanmen Bay and its adjacent waters. The model was validated against observed current data from three stations and tidal elevation data from two stations at the bay mouth. Based on this validation, the tidal and current distribution characteristics as well as tidal wave propagation in Sanmen Bay and its adjacent waters were analyzed. Furthermore, by comparing the results of sensitivity experiments under the 2000 and 2020 shoreline conditions, the impacts of shoreline changes induced by reclamation on the hydrodynamic environment within the bay were quantitatively assessed. Results demonstrate that the study area exhibits predominantly semidiurnal tides, with the M2 constituent showing the largest amplitude (1.5-2 m), followed by S2, both propagating from southeast to northwest. The tidal currents within the bay are primarily rectilinear, with the maximum semi-major axis of the M2 tidal current ellipse reaching 1 m/s. Residual currents in topographically complex regions can reach 0.4 m/s, generally flowing northeastward into the bay and southwestward out of the bay. The tidal energy flux density gradually decays during its propagation toward the bay mouth, weakening to about 20 kW/m at the entrance. Comparative analysis reveals that shoreline modifications have enhanced flood dominance within the bay, reduced M2 amplitude by 0.2 m in the bay-head region. The residual current direction has reversed from outward to inward flow along the northeastern bay mouth, while tidal energy flux density decreased by approximately 40 kW/m in some deeper channels. The numerical simulations show good agreement with field measurements, effectively reflecting recent hydrodynamic conditions in Sanmen Bay and providing scientific support for studying the impact of typical coastal reclamation on hydrodynamics.
, Available online ,
doi: 10.12284/hyxb2025-01
Abstract:
The rapid expansion of oxygen minimum zone (OMZ) in recent decades represents a microcosm of the global ocean deoxygenation problem, exerting profound impacts on marine ecosystems. This study systematically reviewed the ecological effects of OMZ from the perspectives of their linkages with biogeochemical cycles, biological activities, and climate change. Within OMZ, nitrogen cycling is primarily governed by denitrification and anammox, which act synergistically to drive nitrogen removal from the ocean. OMZ can enhance the efficiency of the biological pump, influence microbial carbon transformation, and alter the balance of the carbonate pump, thereby exerting significant control over the marine carbon cycle. Furthermore, the redox alterations induced by OMZ strongly affect the cycling of key elements such as phosphorus, iron, and sulfur. From an ecological standpoint, OMZ suppress diel vertical migration of zooplankton, impose physiological stress and habitat compression on nektonic organisms, alter the diversity, community structure, and physiological responses of benthic fauna, and restructure the metabolic pathways of microbial communities. OMZ also exhibit a bidirectional feedback relationship with climate change. Climate warming reduces oxygen solubility, enhances biological oxygen consumption, and intensifies stratification, collectively accelerating OMZ expansion. Conversely, OMZ can influence climate by altering oceanic carbon sequestration efficiency and enhancing the emission of greenhouse gases such as N2O and CH4. Future research should focus on elucidating the quantitative relationships between OMZ and various forms of carbon, assessing the ecological impacts of OMZ on biological activity, exploring their coupled interactions with climate change, and improving the methodologies of OMZ research. These ways will be essential for deepening our understanding of OMZ.
The rapid expansion of oxygen minimum zone (OMZ) in recent decades represents a microcosm of the global ocean deoxygenation problem, exerting profound impacts on marine ecosystems. This study systematically reviewed the ecological effects of OMZ from the perspectives of their linkages with biogeochemical cycles, biological activities, and climate change. Within OMZ, nitrogen cycling is primarily governed by denitrification and anammox, which act synergistically to drive nitrogen removal from the ocean. OMZ can enhance the efficiency of the biological pump, influence microbial carbon transformation, and alter the balance of the carbonate pump, thereby exerting significant control over the marine carbon cycle. Furthermore, the redox alterations induced by OMZ strongly affect the cycling of key elements such as phosphorus, iron, and sulfur. From an ecological standpoint, OMZ suppress diel vertical migration of zooplankton, impose physiological stress and habitat compression on nektonic organisms, alter the diversity, community structure, and physiological responses of benthic fauna, and restructure the metabolic pathways of microbial communities. OMZ also exhibit a bidirectional feedback relationship with climate change. Climate warming reduces oxygen solubility, enhances biological oxygen consumption, and intensifies stratification, collectively accelerating OMZ expansion. Conversely, OMZ can influence climate by altering oceanic carbon sequestration efficiency and enhancing the emission of greenhouse gases such as N2O and CH4. Future research should focus on elucidating the quantitative relationships between OMZ and various forms of carbon, assessing the ecological impacts of OMZ on biological activity, exploring their coupled interactions with climate change, and improving the methodologies of OMZ research. These ways will be essential for deepening our understanding of OMZ.
, Available online ,
doi: 10.12284/hyxb2025-00
Abstract:
Sexual reproduction in scleractinian corals is essential for sustaining coral reef ecosystem structure and function, governing population dynamics and genetic diversity critical to ecosystem persistence and evolution. This review synthesizes current research on: (1) reproductive strategies, (2) gonadal development, (3) spawning and fertilization, (4) embryogenesis, (5) larval settlement, and (6) juvenile development. While endogenous mechanisms and environmental factors jointly regulate this process, underlying molecular mechanisms remain poorly characterized. Future priorities include elucidating environmental controls on spawning timing, larval settlement triggers, establishment/plasticity of early symbiosis, and developing molecular-assisted breeding for thermotolerant corals.
Sexual reproduction in scleractinian corals is essential for sustaining coral reef ecosystem structure and function, governing population dynamics and genetic diversity critical to ecosystem persistence and evolution. This review synthesizes current research on: (1) reproductive strategies, (2) gonadal development, (3) spawning and fertilization, (4) embryogenesis, (5) larval settlement, and (6) juvenile development. While endogenous mechanisms and environmental factors jointly regulate this process, underlying molecular mechanisms remain poorly characterized. Future priorities include elucidating environmental controls on spawning timing, larval settlement triggers, establishment/plasticity of early symbiosis, and developing molecular-assisted breeding for thermotolerant corals.
, Available online
Abstract:
To address the problem of low prediction accuracy for Arctic sea ice concentration during the melting season, this study proposes a method for predicting Arctic sea ice concentration based on an improved SA-ConvLSTM model, enabling two-dimensional spatiotemporal prediction of monthly mean sea ice concentration data for the coming year. The method uses the SA-ConvLSTM model as the core unit, incorporating a Seq2Seq prediction structure and a VGG16-like encoder–decoder architecture to specifically address the uncertainty in selecting the output step length of time series predictions. In addition, a composite loss function is designed to optimize the training process, further enhancing the spatiotemporal prediction accuracy of sea ice concentration distribution. Using the Arctic Ocean as the study area, and based on monthly climate sea ice concentration data jointly released by the National Snow and Ice Data Center (NSIDC) and the National Oceanic and Atmospheric Administration (NOAA), the model predicts the spatiotemporal distribution of Arctic sea ice concentration in 2023 and compares the results with real observations. The results show that, compared with traditional LSTM, ConvLSTM, and the unmodified SA-ConvLSTM models, the improved model achieves significant advantages in all evaluation metrics: root mean square error decreases by 33.52%, 36.10%, and 22.58%; correlation coefficient increases by 8.56%, 5.97%, and 3.31%; structural similarity index improves by 9.71%, 15.00%, and 10.30%; and sea ice area error decreases by 83.46%, 76.53%, and 60.30%, respectively. Furthermore, analysis of predictions for the extreme melting years of 2012 and 2020 further verifies the model’s stability and robustness under abnormal climatic conditions, demonstrating strong adaptability and practical application potential. The proposed spatiotemporal prediction model can more accurately capture the spatial distribution of sea ice during the melting season and effectively represent complex spatiotemporal variations and fine-scale details.
To address the problem of low prediction accuracy for Arctic sea ice concentration during the melting season, this study proposes a method for predicting Arctic sea ice concentration based on an improved SA-ConvLSTM model, enabling two-dimensional spatiotemporal prediction of monthly mean sea ice concentration data for the coming year. The method uses the SA-ConvLSTM model as the core unit, incorporating a Seq2Seq prediction structure and a VGG16-like encoder–decoder architecture to specifically address the uncertainty in selecting the output step length of time series predictions. In addition, a composite loss function is designed to optimize the training process, further enhancing the spatiotemporal prediction accuracy of sea ice concentration distribution. Using the Arctic Ocean as the study area, and based on monthly climate sea ice concentration data jointly released by the National Snow and Ice Data Center (NSIDC) and the National Oceanic and Atmospheric Administration (NOAA), the model predicts the spatiotemporal distribution of Arctic sea ice concentration in 2023 and compares the results with real observations. The results show that, compared with traditional LSTM, ConvLSTM, and the unmodified SA-ConvLSTM models, the improved model achieves significant advantages in all evaluation metrics: root mean square error decreases by 33.52%, 36.10%, and 22.58%; correlation coefficient increases by 8.56%, 5.97%, and 3.31%; structural similarity index improves by 9.71%, 15.00%, and 10.30%; and sea ice area error decreases by 83.46%, 76.53%, and 60.30%, respectively. Furthermore, analysis of predictions for the extreme melting years of 2012 and 2020 further verifies the model’s stability and robustness under abnormal climatic conditions, demonstrating strong adaptability and practical application potential. The proposed spatiotemporal prediction model can more accurately capture the spatial distribution of sea ice during the melting season and effectively represent complex spatiotemporal variations and fine-scale details.
, Available online ,
doi: 10.12284/hyxb2025093
Abstract:
To ensure the structural stability of subsea infrastructure under prolonged exposure to marine dynamic loads (e.g., waves, ocean currents, and seismic activities), it is essential to understand the rheological behavior of deep-sea soft clay in the surface layer of the seabed. In this study, deep-sea soft clay was selected as the research subject, and dynamic shear tests were conducted under varying salinity and temperature conditions using a strain-controlled rheometer. The variation patterns of storage modulus (G'), loss modulus (G''), and cross-strain were systematically analyzed. By integrating liquid and plastic limit tests and free settlement tests, the influence mechanisms of salinity and temperature on the rheological properties of deep-sea soft clay were explored. The experimental results indicate that as the concentration of NaCl solution increases and temperature decreases, the liquid limit, plastic limit, settlement volume, G', G'', and cross-strain of deep-sea soft clay all exhibit an upward trend. This behavior is closely associated with the formation of a flocculated clay structure and the reduction in thickness of the double electric layer. Under increasing shear strain, deep-sea soft clay demonstrates a distinct two-step yielding behavior: the first yield occurs during the initial stage of modulus reduction, corresponding to the breakdown of the flocculated network; the second yield appears in the subsequent modulus reduction phase, associated with the disruption of the shear-induced hollow cylindrical structure. The plateau phase between the two yielding stages reflects the shear resistance provided by the hollow cylindrical structure. The findings of this study provide a scientific foundation for the design and stability evaluation of engineering foundations in ultra-deep marine environments.
To ensure the structural stability of subsea infrastructure under prolonged exposure to marine dynamic loads (e.g., waves, ocean currents, and seismic activities), it is essential to understand the rheological behavior of deep-sea soft clay in the surface layer of the seabed. In this study, deep-sea soft clay was selected as the research subject, and dynamic shear tests were conducted under varying salinity and temperature conditions using a strain-controlled rheometer. The variation patterns of storage modulus (G'), loss modulus (G''), and cross-strain were systematically analyzed. By integrating liquid and plastic limit tests and free settlement tests, the influence mechanisms of salinity and temperature on the rheological properties of deep-sea soft clay were explored. The experimental results indicate that as the concentration of NaCl solution increases and temperature decreases, the liquid limit, plastic limit, settlement volume, G', G'', and cross-strain of deep-sea soft clay all exhibit an upward trend. This behavior is closely associated with the formation of a flocculated clay structure and the reduction in thickness of the double electric layer. Under increasing shear strain, deep-sea soft clay demonstrates a distinct two-step yielding behavior: the first yield occurs during the initial stage of modulus reduction, corresponding to the breakdown of the flocculated network; the second yield appears in the subsequent modulus reduction phase, associated with the disruption of the shear-induced hollow cylindrical structure. The plateau phase between the two yielding stages reflects the shear resistance provided by the hollow cylindrical structure. The findings of this study provide a scientific foundation for the design and stability evaluation of engineering foundations in ultra-deep marine environments.
, Available online ,
doi: 10.12284/hyxb2025091
Abstract:
A two-dimensional numerical model of ocean internal waves is established by using the non-static governing equations of the waves without seafloor topography to study the generation, development and evolution characteristics, as well as the structure and properties of internal waves under the background flow, which is the superposition of steady vertical shear flow and the strong barotropic semi-diurnal tidal currents. The main research results are as follows: When there is an initial disturbance and only the tidal currents is used as the background flow, the disturbance will not develop. When the barotropic semi-diurnal tidal currents and the steady vertical shear flows are superimposed as the background flow, the disturbance shows shear instability, and its energy shows an increasing trend and a wave-like change in the same phase as the tidal current. After the internal waves were generated, showing a moving in the direction of forward and reverse shear flow synchronized with the period of the tidal current. The forward moving was much faster than the reverse moving, and overall it moved along the direction of forward shear flow, indicating that the tidal current had a modulating effect on the development of internal waves. The flow function disturbance of the internal wave presents a wave packet shape composed of multiple closed positive and negative circles, with the circulation center appearing in the middle of the water body. The main body of density disturbance appears near the pycnocline and is captured by the pycnocline. Due to the interaction between tidal currents and disturbances, a single frequency harmonic wave can be transformed into a wave packet containing many frequencies, known as the frequency conversion effect of currents. This effect significantly reduces the growth rate of internal wave shear instability and has the characteristics of maintaining stability. The overall trend of the group velocity of internal waves is along the direction of shear flow. The horizontal scale of the unstable internal waves is basically independent of the initial disturbance value. The nature of this internal waves are non-equilibrium gravitational (inertial) waves.
A two-dimensional numerical model of ocean internal waves is established by using the non-static governing equations of the waves without seafloor topography to study the generation, development and evolution characteristics, as well as the structure and properties of internal waves under the background flow, which is the superposition of steady vertical shear flow and the strong barotropic semi-diurnal tidal currents. The main research results are as follows: When there is an initial disturbance and only the tidal currents is used as the background flow, the disturbance will not develop. When the barotropic semi-diurnal tidal currents and the steady vertical shear flows are superimposed as the background flow, the disturbance shows shear instability, and its energy shows an increasing trend and a wave-like change in the same phase as the tidal current. After the internal waves were generated, showing a moving in the direction of forward and reverse shear flow synchronized with the period of the tidal current. The forward moving was much faster than the reverse moving, and overall it moved along the direction of forward shear flow, indicating that the tidal current had a modulating effect on the development of internal waves. The flow function disturbance of the internal wave presents a wave packet shape composed of multiple closed positive and negative circles, with the circulation center appearing in the middle of the water body. The main body of density disturbance appears near the pycnocline and is captured by the pycnocline. Due to the interaction between tidal currents and disturbances, a single frequency harmonic wave can be transformed into a wave packet containing many frequencies, known as the frequency conversion effect of currents. This effect significantly reduces the growth rate of internal wave shear instability and has the characteristics of maintaining stability. The overall trend of the group velocity of internal waves is along the direction of shear flow. The horizontal scale of the unstable internal waves is basically independent of the initial disturbance value. The nature of this internal waves are non-equilibrium gravitational (inertial) waves.
, Available online ,
doi: 10.12284/hyxb2025130
Abstract:
To comprehensively understand and analyze the current status and developmental trends of capture resource utilization in China's coastal waters, this study constructs individual ARIMA models and their hybrid models with XGBoost, using fishery production data from 1980, 1985, 1991, 1997, 2003, 2009, and 2016 as temporal reference points. The model demonstrating the highest fitting accuracy was selected to forecast the marine catch in China's coastal waters from 2024 to 2028. The results indicate that the individual ARIMA models exhibited Mean Absolute Percentage Errors (MAPE) ranging from 0.11% to 12.12% and coefficients of determination (R2) between0.4561 and 0.9794 , while the hybrid models showed MAPE values of 0.12%−12.12% and R2 values of 0.7584 −0.9933 . Notably, the ARIMA(1,2,1) hybrid model constructed with 1980 capture data demonstrated optimal fitting performance, with MAPE and R2 values of 0.12% and 0.9933 , respectively. This model forecasts a marine catch of 9.5*106 tons in China’s coastal waters from 2024 to 2028, indicating a gradual upward trend. The research findings reveal that the predictive accuracy of both model types initially decreases and subsequently increases with the extension of time series data, achieving optimal prediction accuracy and fitting degree with the longest time series. The hybrid model demonstrates significantly superior predictive accuracy compared to the individual ARIMA model. The forecasted catch values for 2024−2028 indicate an increase of less than 0.1%.
To comprehensively understand and analyze the current status and developmental trends of capture resource utilization in China's coastal waters, this study constructs individual ARIMA models and their hybrid models with XGBoost, using fishery production data from 1980, 1985, 1991, 1997, 2003, 2009, and 2016 as temporal reference points. The model demonstrating the highest fitting accuracy was selected to forecast the marine catch in China's coastal waters from 2024 to 2028. The results indicate that the individual ARIMA models exhibited Mean Absolute Percentage Errors (MAPE) ranging from 0.11% to 12.12% and coefficients of determination (R2) between
, Available online ,
doi: 10.12284/hyxb2025-00
Abstract:
Diatoms, as an important component of biofilms, can induce the settlement of invertebrates such as mussels. Extracellular polymeric substances (EPS) secreted by diatom play important roles in the induction process. However, the mechanism by which diatoms promote mussel settlement remains unclear. Diatom EPS typically consists of polysaccharides, proteins, nucleic acids, and other substances, with specific composition varying among species. To investigate the biological characteristics of different diatom biofilms and their ability to induce the settlement of Mytilus coruscus, two strains of diatoms were isolated and purified from natural biofilms in this study. After a cultivation period of 21 days, the chlorophyll a content and density of the diatom biofilm were measured. Moreover, its inducing activity on mussel settlement was investigated. Bound EPS from marine diatom biofilms was extracted using a hot solvent extraction method, and the content of polysaccharides and proteins was measured. The results showed that the biofilm of Navicula pelliculosa had high induction activity for mussel larvae settlement (63.8%), while the biofilm of Nitzschia traheaformis showed no difference from the blank group. Analysis by confocal laser scanning microscopy revealed that Navicula pelliculosa biofilm contained more extracellular polysaccharides, with water-insoluble polysaccharide components accounting for 51.49%. In contrast, Nitzschia traheaformis biofilms contained a higher proportion of protein components. This study preliminarily explored the biological characteristics of different marine diatom biofilms, providing theoretical support for understanding how diatom biofilm extracellular substances induce mussel larvae settlement.
Diatoms, as an important component of biofilms, can induce the settlement of invertebrates such as mussels. Extracellular polymeric substances (EPS) secreted by diatom play important roles in the induction process. However, the mechanism by which diatoms promote mussel settlement remains unclear. Diatom EPS typically consists of polysaccharides, proteins, nucleic acids, and other substances, with specific composition varying among species. To investigate the biological characteristics of different diatom biofilms and their ability to induce the settlement of Mytilus coruscus, two strains of diatoms were isolated and purified from natural biofilms in this study. After a cultivation period of 21 days, the chlorophyll a content and density of the diatom biofilm were measured. Moreover, its inducing activity on mussel settlement was investigated. Bound EPS from marine diatom biofilms was extracted using a hot solvent extraction method, and the content of polysaccharides and proteins was measured. The results showed that the biofilm of Navicula pelliculosa had high induction activity for mussel larvae settlement (63.8%), while the biofilm of Nitzschia traheaformis showed no difference from the blank group. Analysis by confocal laser scanning microscopy revealed that Navicula pelliculosa biofilm contained more extracellular polysaccharides, with water-insoluble polysaccharide components accounting for 51.49%. In contrast, Nitzschia traheaformis biofilms contained a higher proportion of protein components. This study preliminarily explored the biological characteristics of different marine diatom biofilms, providing theoretical support for understanding how diatom biofilm extracellular substances induce mussel larvae settlement.
, Available online
Abstract:
Coral reef ecosystems are the most biologically diverse marine ecosystems on Earth and form the basis for coral reef research and conservation. Underwater monitoring is an important method for obtaining coral reef data. For underwater environments characterized by spectral complexity and high structural complexity, this paper proposes a residual SuperPoint underwater coral reef image registration method based on adaptive equalization sample. To address the issue of Visual Geometry Group (VGG) networks causing partial loss of high-frequency features and low feature extraction efficiency, a residual module is introduced into the encoding network to retain original features while reducing fitting difficulty and improving the accuracy of image feature point extraction. To address the issue of feature point extraction easily neglecting negative samples, we propose an adaptive equalization sample comparison loss function that incorporates a difficult negative sample mining mechanism. This improves parameter optimization efficiency, accelerates convergence speed, and enhances feature point extraction accuracy. Experiments conducted using the Hainan Jiajing Island underwater coral reef optical dataset, COCO, and HPatches datasets demonstrate that on the HPatches dataset, the residual SuperPoint algorithm achieves a feature point overlap rate of 61.7%, outperforming comparison algorithms by 4.8% to 23.1%. In underwater coral reef scenarios, Residual SuperPoint achieved a 11.8% improvement in structural similarity index measure (SSIM) and a 22.60% increase in mutual information (MI) compared to the classic SuperPoint at the image-level registration evaluation metrics, while maintaining comparable root mean square error (RMSE). Compared to other traditional algorithms, it demonstrated optimal performance in both structural similarity index and mutual information metrics, with suboptimal RMSE. The proposed method provides technical support for coral reef surveys, ecological monitoring, and related fields.
Coral reef ecosystems are the most biologically diverse marine ecosystems on Earth and form the basis for coral reef research and conservation. Underwater monitoring is an important method for obtaining coral reef data. For underwater environments characterized by spectral complexity and high structural complexity, this paper proposes a residual SuperPoint underwater coral reef image registration method based on adaptive equalization sample. To address the issue of Visual Geometry Group (VGG) networks causing partial loss of high-frequency features and low feature extraction efficiency, a residual module is introduced into the encoding network to retain original features while reducing fitting difficulty and improving the accuracy of image feature point extraction. To address the issue of feature point extraction easily neglecting negative samples, we propose an adaptive equalization sample comparison loss function that incorporates a difficult negative sample mining mechanism. This improves parameter optimization efficiency, accelerates convergence speed, and enhances feature point extraction accuracy. Experiments conducted using the Hainan Jiajing Island underwater coral reef optical dataset, COCO, and HPatches datasets demonstrate that on the HPatches dataset, the residual SuperPoint algorithm achieves a feature point overlap rate of 61.7%, outperforming comparison algorithms by 4.8% to 23.1%. In underwater coral reef scenarios, Residual SuperPoint achieved a 11.8% improvement in structural similarity index measure (SSIM) and a 22.60% increase in mutual information (MI) compared to the classic SuperPoint at the image-level registration evaluation metrics, while maintaining comparable root mean square error (RMSE). Compared to other traditional algorithms, it demonstrated optimal performance in both structural similarity index and mutual information metrics, with suboptimal RMSE. The proposed method provides technical support for coral reef surveys, ecological monitoring, and related fields.
, Available online ,
doi: 10.12284/hyxb2025126
Abstract:
Massive Porites corals, widely inhabiting in tropical oceans, are considered ideal archives for high-resolution environmental records and have garnered significant attention in the fields of paleoclimate and paleoenvironmental reconstruction. The fluorescence emitted by coral skeletons under long-wave ultraviolet (UV) light, due to its sensitivity to terrestrial runoff, pollutants, and climatic events, has emerged as an another tool for revealing various environmental changes related to rainfall, river discharge, and other factors. This review synthesizes the formation mechanisms of fluorescent substances in coral skeletons, measurement techniques, applications in environmental reconstruction, as well as current challenges and future research directions. Overall, the fluorescent signals in coral skeletons primarily originate from terrestrially derived organic matter dominated by fulvic acids and humic-like substances produced by symbiotic algal metabolism. Additionally, coral skeletal structure, mineral properties, and interactions with environmental factors such as rainfall and runoff influence fluorescence characteristics. By combining high-precision micro-sampling techniques with fluorescence analysis, scientists have successfully reconstructed environmental histories of terrestrial runoff, precipitation, and human activities across different timescales. Based on current international research progress, this paper suggests that future studies should explore novel analytical techniques, develop more accurate fluorescence-hydrological quantitative models by integrating multi-source data, and strengthen cross-validation with other proxy indicators to establish a high-precision, high-resolution global coral fluorescence database.
Massive Porites corals, widely inhabiting in tropical oceans, are considered ideal archives for high-resolution environmental records and have garnered significant attention in the fields of paleoclimate and paleoenvironmental reconstruction. The fluorescence emitted by coral skeletons under long-wave ultraviolet (UV) light, due to its sensitivity to terrestrial runoff, pollutants, and climatic events, has emerged as an another tool for revealing various environmental changes related to rainfall, river discharge, and other factors. This review synthesizes the formation mechanisms of fluorescent substances in coral skeletons, measurement techniques, applications in environmental reconstruction, as well as current challenges and future research directions. Overall, the fluorescent signals in coral skeletons primarily originate from terrestrially derived organic matter dominated by fulvic acids and humic-like substances produced by symbiotic algal metabolism. Additionally, coral skeletal structure, mineral properties, and interactions with environmental factors such as rainfall and runoff influence fluorescence characteristics. By combining high-precision micro-sampling techniques with fluorescence analysis, scientists have successfully reconstructed environmental histories of terrestrial runoff, precipitation, and human activities across different timescales. Based on current international research progress, this paper suggests that future studies should explore novel analytical techniques, develop more accurate fluorescence-hydrological quantitative models by integrating multi-source data, and strengthen cross-validation with other proxy indicators to establish a high-precision, high-resolution global coral fluorescence database.
, Available online
Abstract:
Mesoscale eddies, as an important phenomenon in the ocean, significantly influence the distribution of water masses and material transport within their regions. Obtaining the three-dimensional distribution of mesoscale eddies is of great significance for marine resource development, maritime transportation, and military applications. However, existing intelligent identification models for mesoscale eddies typically rely on sea surface data such as sea surface height and sea surface temperature, and are only used to identify mesoscale eddies at the ocean surface. This paper proposes a multi-scale feature adaptive fusion model based on multi-source data, including flow fields, temperature, and salinity. In the encoder stage, the model uses a multi-branch structure to independently extract features from the multi-source data. In the decoder stage, an attention mechanism is employed to perform weighted adaptive fusion of multi-layer features from each branch. During training, a hybrid loss function combining classification probability gradient loss and Dice coefficient loss is used to improve the identification accuracy of the model. Experimental validation is conducted using data from the South China Sea region. The model achieves a global accuracy of 98.49%, an average Dice coefficient of0.8777 , and a weighted Dice coefficient of 0.8225 , demonstrating the model’s effectiveness and high accuracy in identifying the distribution of mesoscale eddies at both the sea surface and various water depths.
Mesoscale eddies, as an important phenomenon in the ocean, significantly influence the distribution of water masses and material transport within their regions. Obtaining the three-dimensional distribution of mesoscale eddies is of great significance for marine resource development, maritime transportation, and military applications. However, existing intelligent identification models for mesoscale eddies typically rely on sea surface data such as sea surface height and sea surface temperature, and are only used to identify mesoscale eddies at the ocean surface. This paper proposes a multi-scale feature adaptive fusion model based on multi-source data, including flow fields, temperature, and salinity. In the encoder stage, the model uses a multi-branch structure to independently extract features from the multi-source data. In the decoder stage, an attention mechanism is employed to perform weighted adaptive fusion of multi-layer features from each branch. During training, a hybrid loss function combining classification probability gradient loss and Dice coefficient loss is used to improve the identification accuracy of the model. Experimental validation is conducted using data from the South China Sea region. The model achieves a global accuracy of 98.49%, an average Dice coefficient of
, Available online
Abstract:
In the context of global warming, the intensity of typhoon activity has exhibited an increasing trend. Typhoons are typically associated with heavy rainfall and strong winds, which can result in significant alterations to the nearshore hydrodynamical environment over a short period, thereby triggering pronounced ecological responses. In this paper, a three-dimensional hydro-biogeochemical model was constructed based on the unstructured-grid, Finite Volume Community Ocean Model (FVCOM) to study the impact of Typhoon Lekima (No. 1909) on residual currents, salinity, water quality and nutrient transport in Laizhou Bay (LZB). Sensitivity experiments were conducted to quantify the contributions of river inputs and winds to water quality during the passage of Lekima. The results show that a strong southwest coastal current developed south of the Yellow River Estuary (YRE), and the pattern of residual currents in LZB was characterized by westward inflow and eastward outflow. The heavy rainfall led to a marked increase in freshwater and dissolved inorganic nitrogen (DIN) fluxes from the surrounding rivers into the bay. Consequently, the surface salinity near the YRE and the southwest coast of LZB decreased rapidly, while DIN concentrations increased. The surface salinity reached the minimum value of 25.91 PSU two days after the passage of Lekima, which was 1.57 PSU lower than pre-typhoon levels. Conversely, surface DIN concentrations peaked at 0.61 mg/L eight days after the passage of Lekima, approximately 1.51 times higher than pre-typhoon levels. Calculations of DIN fluxes through the bay mouth section revealed that the DIN exchange between LZB and the Bohai Sea (BS) occurred in two distinct phases: strong inflow and outflow during the passage of Lekima, with a total of 1.88 kt of DIN transported from LZB to the BS. The contributions of river inputs and winds to water quality were 70.15% and −18.47%, respectively. River input was identified as the primary factor of changes in water quality in LZB, while the direction of residual currents was landward due to the force of typhoon winds, which was adverse to the transport of DIN from LZB to the BS. This study underscores the crucial role of typhoons in regulating water quality changes in coastal bays and provides scientific support for sustainable development and ecological protection in coastal regions.
In the context of global warming, the intensity of typhoon activity has exhibited an increasing trend. Typhoons are typically associated with heavy rainfall and strong winds, which can result in significant alterations to the nearshore hydrodynamical environment over a short period, thereby triggering pronounced ecological responses. In this paper, a three-dimensional hydro-biogeochemical model was constructed based on the unstructured-grid, Finite Volume Community Ocean Model (FVCOM) to study the impact of Typhoon Lekima (No. 1909) on residual currents, salinity, water quality and nutrient transport in Laizhou Bay (LZB). Sensitivity experiments were conducted to quantify the contributions of river inputs and winds to water quality during the passage of Lekima. The results show that a strong southwest coastal current developed south of the Yellow River Estuary (YRE), and the pattern of residual currents in LZB was characterized by westward inflow and eastward outflow. The heavy rainfall led to a marked increase in freshwater and dissolved inorganic nitrogen (DIN) fluxes from the surrounding rivers into the bay. Consequently, the surface salinity near the YRE and the southwest coast of LZB decreased rapidly, while DIN concentrations increased. The surface salinity reached the minimum value of 25.91 PSU two days after the passage of Lekima, which was 1.57 PSU lower than pre-typhoon levels. Conversely, surface DIN concentrations peaked at 0.61 mg/L eight days after the passage of Lekima, approximately 1.51 times higher than pre-typhoon levels. Calculations of DIN fluxes through the bay mouth section revealed that the DIN exchange between LZB and the Bohai Sea (BS) occurred in two distinct phases: strong inflow and outflow during the passage of Lekima, with a total of 1.88 kt of DIN transported from LZB to the BS. The contributions of river inputs and winds to water quality were 70.15% and −18.47%, respectively. River input was identified as the primary factor of changes in water quality in LZB, while the direction of residual currents was landward due to the force of typhoon winds, which was adverse to the transport of DIN from LZB to the BS. This study underscores the crucial role of typhoons in regulating water quality changes in coastal bays and provides scientific support for sustainable development and ecological protection in coastal regions.
, Available online ,
doi: 10.12284/hyxb2025000
Abstract:
Ocean buoy observations serve as a vital means of acquiring data for marine research. However, direct measurements from buoys are subject to significant biases induced by factors such as sensor baseline drift, biofouling, and seawater corrosion, necessitating rigorous bias correction to ensure data reliability. While numerous quality control (QC) schemes for physical oceanographic parameters from buoy data have been extensively studied and reported, robust and practical sensor QC measures for more complex and variable chemical parameters remain lacking. To address this gap, this study analyzed 90-day laboratory monitoring data for parameters including dissolved oxygen, chlorophyll concentration, pH, and partial pressure of CO2 (pCO2). The analysis revealed that the drift bias in these monitored parameters exhibits a strong linear correlation with fundamental sensor parameters such as conductivity and sensor output voltage and with biological factors to varying degrees. Building upon these findings, we developed a drift bias correction method based on machine learning algorithm to fit the nonlinear relationships between drift bias and fundamental sensor parameters. This method effectively validates buoy sensor data for chemical parameters. Application of this method to observational data across different parameters significantly reduces the deviation between drifted data and true values. It thus provides a novel QC approach for achieving sustained, stable, and high-quality acquisition of marine chemical parameter data from buoy observations.
Ocean buoy observations serve as a vital means of acquiring data for marine research. However, direct measurements from buoys are subject to significant biases induced by factors such as sensor baseline drift, biofouling, and seawater corrosion, necessitating rigorous bias correction to ensure data reliability. While numerous quality control (QC) schemes for physical oceanographic parameters from buoy data have been extensively studied and reported, robust and practical sensor QC measures for more complex and variable chemical parameters remain lacking. To address this gap, this study analyzed 90-day laboratory monitoring data for parameters including dissolved oxygen, chlorophyll concentration, pH, and partial pressure of CO2 (pCO2). The analysis revealed that the drift bias in these monitored parameters exhibits a strong linear correlation with fundamental sensor parameters such as conductivity and sensor output voltage and with biological factors to varying degrees. Building upon these findings, we developed a drift bias correction method based on machine learning algorithm to fit the nonlinear relationships between drift bias and fundamental sensor parameters. This method effectively validates buoy sensor data for chemical parameters. Application of this method to observational data across different parameters significantly reduces the deviation between drifted data and true values. It thus provides a novel QC approach for achieving sustained, stable, and high-quality acquisition of marine chemical parameter data from buoy observations.
, Available online ,
doi: 10.12284/hyxb2025124
Abstract:
To reveal the effect of high temperature on the ammonia assimilation of Pocillopora damicornis and elucidate the thermal adaptation mechanism of scleractinian coral, we identified and cloned an ammonia transporter gene PdRhp-1 from P. damicornis. The open reading frame (ORF) of PdRhp-1 is1410 bp, encoding a polypeptide chain composed of 469 amino acid residues. Sequence analysis showed that PdRhp-1 was a hydrophobic transmembrane protein, containing 12 transmembrane domains, belonging to the Rhesus-type ammonia transporter. Its amino acid sequence shares 44.14% identity with Homo sapiens ammonia transporter gene RhCG. In order to analyze the biological function of PdRhp-1, its recombinant expression vector was transfected into HEK293T cells, and ammonium chloride was added to the culture medium. It was found that the total ammonia uptake rate in the cells expressing PdRhp-1 was significantly higher than that in the control group, indicating that PdRhp-1 has ammonia transport function. At the same time, the transcriptome data of high temperature treated P. damicornis were analyzed, and it was found that high temperature significantly inhibited the expression of PdRhp-1 and some genes related to ammonia assimilation. The above results demonstrate that PdRhp-1 is a Rhesus-type ammonia transporter, and high temperature may affect the symbiotic homeostasis of corals and zooxanthellae by inhibiting the ammonia transport process mediated by PdRhp-1.
To reveal the effect of high temperature on the ammonia assimilation of Pocillopora damicornis and elucidate the thermal adaptation mechanism of scleractinian coral, we identified and cloned an ammonia transporter gene PdRhp-1 from P. damicornis. The open reading frame (ORF) of PdRhp-1 is
, Available online ,
doi: 10.12284/hyxb2025114
Abstract:
In order to compare the seawater quality, the growth and nutrient composition of harvesting period Pacific oysters (Crassostrea gigas) under two different culture model of oyster monoculture or polyculture with Laminaria japonica (L. japonica) in Longkou. The indicators such as physicochemical factors, bacteria and phytoplankton in seawater from aquaculture areas (monoculture area M1, polyculture area M2) were detected during a period time, the growth and nutrient composition of oysters in M1 and M2 were assayed and compared when oysters were harvested. The results showed that there had no significant difference in water temperature, salinity, pH, dissolved oxygen (DO) and vibrio abundance between M1 and M2, and they were all in line with the national seawater quality standard of Class II. The content of chemical oxygen demand (COD), nitrogen and phosphorus nutrient salts, heterotrophic bacterial abundance content in M2 were lower than that in M1 in most of months, we inferred that L. japonica in M2 could effectively absorb organic nitrogen and phosphorus from oyster metabolic wastes. The diatom content was higher in M2 than that in M1, it maybe be related to the fact that the nitrogen to phosphorus ratio in M2 was more suitable for diatom growth, and oysters in M2 indirectly reduce their consumption of phytoplankton by filter feeding on L. japonica detritus. The oyster’s plumpness, soft body wet weight and protein content in M2 were significantly (P ＜ 0.05) higher than that in M1, the oyster’s shell width and fat content in M2 were extremely significantly (P ＜ 0.01) higher than that in M1, it was believed that oysters in M2 could filter-fed the L. japonica detritus at the same time the L. japonica reduced seawater COD in M2 and purified the seawater, all above factors were beneficial for oyster growth. The water content, ash content and shell dry weight were significantly higher (P ＜ 0.05) in oysters from M1 than M2, total sugars in oysters from M1 were extremely significantly higher (P ＜ 0.01) than from M2, the above results were speculated to be related to the low phytoplankton densities in M1, which increased filter feeding frequency and energy consumption of oyster in M1. EAA was significantly higher (P ＜ 0.05) in oysters from M1 than from M2, it was believed that rich species of phytoplankton and higher nutrient salts content could promote EAA accumulation. The study suggested that shellfish-algae polyculture can increases the consumption of oyster metabolites, prevent seawater pollution, and facilitate oyster growth.
In order to compare the seawater quality, the growth and nutrient composition of harvesting period Pacific oysters (Crassostrea gigas) under two different culture model of oyster monoculture or polyculture with Laminaria japonica (L. japonica) in Longkou. The indicators such as physicochemical factors, bacteria and phytoplankton in seawater from aquaculture areas (monoculture area M1, polyculture area M2) were detected during a period time, the growth and nutrient composition of oysters in M1 and M2 were assayed and compared when oysters were harvested. The results showed that there had no significant difference in water temperature, salinity, pH, dissolved oxygen (DO) and vibrio abundance between M1 and M2, and they were all in line with the national seawater quality standard of Class II. The content of chemical oxygen demand (COD), nitrogen and phosphorus nutrient salts, heterotrophic bacterial abundance content in M2 were lower than that in M1 in most of months, we inferred that L. japonica in M2 could effectively absorb organic nitrogen and phosphorus from oyster metabolic wastes. The diatom content was higher in M2 than that in M1, it maybe be related to the fact that the nitrogen to phosphorus ratio in M2 was more suitable for diatom growth, and oysters in M2 indirectly reduce their consumption of phytoplankton by filter feeding on L. japonica detritus. The oyster’s plumpness, soft body wet weight and protein content in M2 were significantly (P ＜ 0.05) higher than that in M1, the oyster’s shell width and fat content in M2 were extremely significantly (P ＜ 0.01) higher than that in M1, it was believed that oysters in M2 could filter-fed the L. japonica detritus at the same time the L. japonica reduced seawater COD in M2 and purified the seawater, all above factors were beneficial for oyster growth. The water content, ash content and shell dry weight were significantly higher (P ＜ 0.05) in oysters from M1 than M2, total sugars in oysters from M1 were extremely significantly higher (P ＜ 0.01) than from M2, the above results were speculated to be related to the low phytoplankton densities in M1, which increased filter feeding frequency and energy consumption of oyster in M1. EAA was significantly higher (P ＜ 0.05) in oysters from M1 than from M2, it was believed that rich species of phytoplankton and higher nutrient salts content could promote EAA accumulation. The study suggested that shellfish-algae polyculture can increases the consumption of oyster metabolites, prevent seawater pollution, and facilitate oyster growth.
, Available online
Abstract:
The influence of suspended particulate matters (SPM) on denitrifying metabolism and potential of nearshore waters were investigated in the sea area outside Dagu River estuary and southern mouth of Jiaozhou Bay based on 15N-isotopic tracing incubation experiments. Sediment cores and overlying waters were collected from two sampling sites and then incubated under in situ conditions and simulated SPM gradient (i.e., 50 mg/L, 100 mg/L, 150 mg/L, 200 mg/L, 300 mg/L and 400 mg/L in setting concentration). Detection of denitrification rates combined with relative abundances of narG and nirS genes measurement were conducted to reveal the denitrification potential. The results showed that significant denitrification occurred in all incubations. Under SPM gradient simulated condition, the denitrifying rates as well as narG and nirS gene abundances increased with SPM concentrations, and the abundance of particle-associated denitrifying bacteria probably played a dominated role on potential enhancement, implying that SPM should act as important media on promoting denitrification potential in the Jiaozhou Bay waters. The variance between two study sites was obvious with denitrification rate measured in estuary area being higher than that in southern mouth, while the functional gene abundances just the opposite. It could be well explained by the composition and grain size difference of the SPM, indicating a complicated regulation of SPM to the denitrification potential in Jiaozhou Bay waters. This study suggests that SPM will expand the spatial activity of denitrifying metabolism and then more release the denitrification potential in the nearshore ecosystem, which is ecologically meaningful for the relief of eutrophication level and risk in coastal environments.
The influence of suspended particulate matters (SPM) on denitrifying metabolism and potential of nearshore waters were investigated in the sea area outside Dagu River estuary and southern mouth of Jiaozhou Bay based on 15N-isotopic tracing incubation experiments. Sediment cores and overlying waters were collected from two sampling sites and then incubated under in situ conditions and simulated SPM gradient (i.e., 50 mg/L, 100 mg/L, 150 mg/L, 200 mg/L, 300 mg/L and 400 mg/L in setting concentration). Detection of denitrification rates combined with relative abundances of narG and nirS genes measurement were conducted to reveal the denitrification potential. The results showed that significant denitrification occurred in all incubations. Under SPM gradient simulated condition, the denitrifying rates as well as narG and nirS gene abundances increased with SPM concentrations, and the abundance of particle-associated denitrifying bacteria probably played a dominated role on potential enhancement, implying that SPM should act as important media on promoting denitrification potential in the Jiaozhou Bay waters. The variance between two study sites was obvious with denitrification rate measured in estuary area being higher than that in southern mouth, while the functional gene abundances just the opposite. It could be well explained by the composition and grain size difference of the SPM, indicating a complicated regulation of SPM to the denitrification potential in Jiaozhou Bay waters. This study suggests that SPM will expand the spatial activity of denitrifying metabolism and then more release the denitrification potential in the nearshore ecosystem, which is ecologically meaningful for the relief of eutrophication level and risk in coastal environments.
, Available online
Abstract:
To elucidate nitrogen cycling processes and identify dominant nitrogen pollution sources in the Pearl River Estuary (PRE), seawater samples were systematically collected from 40 stations in coastal waters (the western of Lingdingyang, Modaomen and Huangmaohai) during July 2020. By integrating hydrochemistry parameters and nitrogen-oxygen dual stable isotope (δ15N-\begin{document}${\mathrm{NO}}_3^- $\end{document} ![]()
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To elucidate nitrogen cycling processes and identify dominant nitrogen pollution sources in the Pearl River Estuary (PRE), seawater samples were systematically collected from 40 stations in coastal waters (the western of Lingdingyang, Modaomen and Huangmaohai) during July 2020. By integrating hydrochemistry parameters and nitrogen-oxygen dual stable isotope (δ15N-
, Available online
Abstract:
Transparent exopolymer particles (TEP) are a special class of extracellular polymeric substances which is ubiquitous in seawater, characterized by transparency; high carbon content and stickiness; with colloidal and particulate characteristics, play a significant role in marine carbon transportation. In this review, we describe the Biogeochemistry characteristic and contribution to carbon transportation of Transparent Exopolymer Particles (TEP) in the ocean systematically. Marine TEP are amorphous, their size is variable, mainly generated by self-assembly of precursors which is released by phytoplankton and removed from ocean through processes such as biological metabolism, air-sea exchange and settlement, their abundance and distribution driven by the activity of organisms such as phytoplankton such as phytoplankton and bacteria, as well as the physicochemical environment and hydrodynamic processes. TEP concentrations in coastal waters exhibit considerable variability(0-14,800 μg XG eq L-1) and decrease with increasing offshore distance and closely related to productivity, thus demonstrating marked seasonal variations; In the open ocean, TEP concentrations are usually lower (0-200 μg XG eq L-1) and decrease with depth in epipelagic waters, while remaining relatively steady in Mesopelagic and Bathypelagic waters. As an important component of particulate organic carbon (POC), TEP typically account for less than 40% of the POC pool and its sinking flux in coastal areas, but can contribute more than 50% in the open ocean. In addition to altering particle sinking rates and affecting vertical carbon transport, TEP can also mediate air-sea carbon exchange through enrichment in the sea surface microlayer, though the underlying mechanisms and their significance in carbon transport require further investigation. Future research should focus on improving quantitative detection methods for TEP, analyzing their composition and morphology, and optimizing carbon conversion factors. to better understand the biogeochemical behaviors of TEP and their mechanisms in marine carbon transportation.
Transparent exopolymer particles (TEP) are a special class of extracellular polymeric substances which is ubiquitous in seawater, characterized by transparency; high carbon content and stickiness; with colloidal and particulate characteristics, play a significant role in marine carbon transportation. In this review, we describe the Biogeochemistry characteristic and contribution to carbon transportation of Transparent Exopolymer Particles (TEP) in the ocean systematically. Marine TEP are amorphous, their size is variable, mainly generated by self-assembly of precursors which is released by phytoplankton and removed from ocean through processes such as biological metabolism, air-sea exchange and settlement, their abundance and distribution driven by the activity of organisms such as phytoplankton such as phytoplankton and bacteria, as well as the physicochemical environment and hydrodynamic processes. TEP concentrations in coastal waters exhibit considerable variability(0-14,800 μg XG eq L-1) and decrease with increasing offshore distance and closely related to productivity, thus demonstrating marked seasonal variations; In the open ocean, TEP concentrations are usually lower (0-200 μg XG eq L-1) and decrease with depth in epipelagic waters, while remaining relatively steady in Mesopelagic and Bathypelagic waters. As an important component of particulate organic carbon (POC), TEP typically account for less than 40% of the POC pool and its sinking flux in coastal areas, but can contribute more than 50% in the open ocean. In addition to altering particle sinking rates and affecting vertical carbon transport, TEP can also mediate air-sea carbon exchange through enrichment in the sea surface microlayer, though the underlying mechanisms and their significance in carbon transport require further investigation. Future research should focus on improving quantitative detection methods for TEP, analyzing their composition and morphology, and optimizing carbon conversion factors. to better understand the biogeochemical behaviors of TEP and their mechanisms in marine carbon transportation.
, Available online
Abstract:
In recent years, the rapid development of the marine economy has led to intensified environmental pollution in coastal areas. As an important aquaculture base, the water environment status of Xiangshan Bay directly affects local economic development and the ecological environment. This study established a BP neural network model based on four water quality monitoring indicators DO, COD, DIN and DIP to analyze the spatial distribution and variation characteristics of the water environmental carrying capacity in Xiangshan Bay from 2020 to 2023. Results show that the Water Environmental Carrying Capacity Index (WECCI) exhibited significant interannual fluctuations, reaching its peak in 2022. Spatially, the inner bay exhibited significantly lower water environmental carrying capacity than the outer bay, attributable to diminished hydrodynamic exchange capacity and prolonged pollutant retention duration. Additional analysis incorporating three water quality evaluation indices NQI, A, and E also indicated improved water environmental quality in 2022. Analysis of the 2022 drought conditions revealed that reduced river runoff and saltwater intrusion led to decreased nutrient concentrations, consequently enhancing the water environmental carrying capacity. Compared to traditional water quality index evaluation methods, the BP neural network model demonstrated superior performance in comprehensively assessing water environmental carrying capacity and its spatial heterogeneity.
In recent years, the rapid development of the marine economy has led to intensified environmental pollution in coastal areas. As an important aquaculture base, the water environment status of Xiangshan Bay directly affects local economic development and the ecological environment. This study established a BP neural network model based on four water quality monitoring indicators DO, COD, DIN and DIP to analyze the spatial distribution and variation characteristics of the water environmental carrying capacity in Xiangshan Bay from 2020 to 2023. Results show that the Water Environmental Carrying Capacity Index (WECCI) exhibited significant interannual fluctuations, reaching its peak in 2022. Spatially, the inner bay exhibited significantly lower water environmental carrying capacity than the outer bay, attributable to diminished hydrodynamic exchange capacity and prolonged pollutant retention duration. Additional analysis incorporating three water quality evaluation indices NQI, A, and E also indicated improved water environmental quality in 2022. Analysis of the 2022 drought conditions revealed that reduced river runoff and saltwater intrusion led to decreased nutrient concentrations, consequently enhancing the water environmental carrying capacity. Compared to traditional water quality index evaluation methods, the BP neural network model demonstrated superior performance in comprehensively assessing water environmental carrying capacity and its spatial heterogeneity.
, Available online ,
doi: 10.12284/hyxb2025006
Abstract:
Studying the occurrence and dynamics of microplastics on coastal beaches is crucial for the integrated management of coastal zones and the assessment of ecological risks. Previous research has highlighted that physical processes play a pivotal role in influencing the occurrences of microplastic on coastal beaches. However, the impact of extreme meteorological events such as typhoons on the distribution of microplastic pollution has yet to be explored. This study conducted field fixed-plot experiments on the coastal beaches of Xiamen City before and after Typhoon "Haikui" to analyze the variations in the abundance, composition, and diversity of microplastic on beaches. The results showed that the abundance of microplastics on the beaches in Xiamen City before Typhoon Haikui was (251.5 ± 27.9) n/kg, and this value significantly decreased to (127.0 ± 18.8) n/kg post-typhoon. Before and after the typhoon, the composition of microplastics on the beaches showed distinct variations, with the abundance of microplastics of different shapes and sizes responding differently to the typhoon. In particular, the abundance of smaller particles (<500 μm) significantly decreased, while the proportion of fibrous particles increased. Moreover, the typhoon event led to a general decrease in the Shannon-Wiener diversity index, while an increase in the Pielou’s evenness index. The impact of typhoons on the distribution of microplastics on beaches arises from the complex coupling of multiple dynamic physical processes in extreme weather, and it is also closely related to factors such as the location and substrate conditions of the coasts. To achieve simulation and prediction of the dynamics of microplastic pollution during typhoon processes, systematic and comprehensive research on the relevant mechanisms is still required in the future.
Studying the occurrence and dynamics of microplastics on coastal beaches is crucial for the integrated management of coastal zones and the assessment of ecological risks. Previous research has highlighted that physical processes play a pivotal role in influencing the occurrences of microplastic on coastal beaches. However, the impact of extreme meteorological events such as typhoons on the distribution of microplastic pollution has yet to be explored. This study conducted field fixed-plot experiments on the coastal beaches of Xiamen City before and after Typhoon "Haikui" to analyze the variations in the abundance, composition, and diversity of microplastic on beaches. The results showed that the abundance of microplastics on the beaches in Xiamen City before Typhoon Haikui was (251.5 ± 27.9) n/kg, and this value significantly decreased to (127.0 ± 18.8) n/kg post-typhoon. Before and after the typhoon, the composition of microplastics on the beaches showed distinct variations, with the abundance of microplastics of different shapes and sizes responding differently to the typhoon. In particular, the abundance of smaller particles (<500 μm) significantly decreased, while the proportion of fibrous particles increased. Moreover, the typhoon event led to a general decrease in the Shannon-Wiener diversity index, while an increase in the Pielou’s evenness index. The impact of typhoons on the distribution of microplastics on beaches arises from the complex coupling of multiple dynamic physical processes in extreme weather, and it is also closely related to factors such as the location and substrate conditions of the coasts. To achieve simulation and prediction of the dynamics of microplastic pollution during typhoon processes, systematic and comprehensive research on the relevant mechanisms is still required in the future.
, Available online
Abstract:
This study focuses on the physical process of a sea fog event during Typhoon Lekima in the Northern Yellow Sea by using observation data, reanalysis data and backward trajectory model. The analysis indicates that the typhoon circulation was the decisive factor determining whether fog formed offshore and developed inland. The warm and humid southerlies from the south Yellow Sea condensed into fog on the colder sea surface besides the typhoon center, which not only provided sufficient moisture for the formation and development of the sea fog but also formed a significant inversion layer over the fog area with the downdraft in the center of the typhoon. The "stable up and turbulent down" structure in the atmospheric boundary layer improved the development of sea fog on the coast and inland area. However, the horizontal wind steering and the strengthening wind speed behind the typhoon strengthened the wind shear in the atmospheric boundary layer, resulting in the enhanced turbulent mixing and the decrease of the stability in the bottom atmospheric boundary layer, which was the main cause of the fog dissipation.
This study focuses on the physical process of a sea fog event during Typhoon Lekima in the Northern Yellow Sea by using observation data, reanalysis data and backward trajectory model. The analysis indicates that the typhoon circulation was the decisive factor determining whether fog formed offshore and developed inland. The warm and humid southerlies from the south Yellow Sea condensed into fog on the colder sea surface besides the typhoon center, which not only provided sufficient moisture for the formation and development of the sea fog but also formed a significant inversion layer over the fog area with the downdraft in the center of the typhoon. The "stable up and turbulent down" structure in the atmospheric boundary layer improved the development of sea fog on the coast and inland area. However, the horizontal wind steering and the strengthening wind speed behind the typhoon strengthened the wind shear in the atmospheric boundary layer, resulting in the enhanced turbulent mixing and the decrease of the stability in the bottom atmospheric boundary layer, which was the main cause of the fog dissipation.
, Available online
Abstract:
The possibility of the Indonesian submarine wreck on 20 April 2021 was analyzed based on satellite remote sensing observation and numerical simulation. The results indicate that large-amplitude oceanic internal waves, estimated to be approximately 50 m using satellite images, originate from the Lombok Strait. They are widely distributed to the north of the Bali Island and are suggested to cause an abrupt sinking of the Indonesian submarine.
The possibility of the Indonesian submarine wreck on 20 April 2021 was analyzed based on satellite remote sensing observation and numerical simulation. The results indicate that large-amplitude oceanic internal waves, estimated to be approximately 50 m using satellite images, originate from the Lombok Strait. They are widely distributed to the north of the Bali Island and are suggested to cause an abrupt sinking of the Indonesian submarine.
, Available online
Abstract:
Abstract：The potential fish production was controlled largely by ocean primary production (OPP) and there were a lot of research findings of estimating fish production by using OPP in China. The relationships between the biomass of fishery stock and OPP were often complicated by the varieties of trophic control in the ecosystem. In this paper, we examined the relationship between biomass of chub mackerel (Scomber japonicus) and net primary production (NPP) and discussed mechanism of trophic control in the ecosystem of chub mackerel fishing ground in south East China Sea by using catch and effort data from the large purse sense of China fishery and NPP derived from remote sensing. The results showed there was a significant non-linear relationship between NPP and standardized CPUE (Catch Per Unit Effort) (P<0.05) instead of the linear trend. The non-linear relationship could be described by a reversed parabolic curve, which meant the biomass of chub mackerel increased with NPP and then decreased when the NPP exceeded a point. The results implied there were other trophic controls in addition to bottom-up control occurred in the ecosystem in south East China Sea. We speculated the change of abundance of the key species at intermediate trophic levels or/and interspecific competitions contribute to the relationship.
Abstract：The potential fish production was controlled largely by ocean primary production (OPP) and there were a lot of research findings of estimating fish production by using OPP in China. The relationships between the biomass of fishery stock and OPP were often complicated by the varieties of trophic control in the ecosystem. In this paper, we examined the relationship between biomass of chub mackerel (Scomber japonicus) and net primary production (NPP) and discussed mechanism of trophic control in the ecosystem of chub mackerel fishing ground in south East China Sea by using catch and effort data from the large purse sense of China fishery and NPP derived from remote sensing. The results showed there was a significant non-linear relationship between NPP and standardized CPUE (Catch Per Unit Effort) (P<0.05) instead of the linear trend. The non-linear relationship could be described by a reversed parabolic curve, which meant the biomass of chub mackerel increased with NPP and then decreased when the NPP exceeded a point. The results implied there were other trophic controls in addition to bottom-up control occurred in the ecosystem in south East China Sea. We speculated the change of abundance of the key species at intermediate trophic levels or/and interspecific competitions contribute to the relationship.
Display Method:
2025, 47(9): 1-22.
doi: 10.12284/hyxb2025120
Abstract:
The Asian continental marginal seas are among the most representative “source-to-sink” coupled systems globally. Understanding their organic carbon (OC) burial processes under the context of Quaternary climate change is of great significance for unraveling the evolution of the global carbon cycle. This study provides a comprehensive review of the sources, burial flux variations, and driving mechanisms of OC in sediments from major Asian marginal seas. The results indicate that during glacial periods, most marginal seas exhibit increased OC content and burial fluxes. In many regions, total organic carbon (TOC) content, organic carbon isotopic composition (δ13Corg), and TOC/total nitrogen (TOC/TN) ratios display cyclic variations on orbital timescales. Mechanistically, sea-level changes regulate the process and intensity of terrigenous material delivery, monsoon systems influence watershed erosion and water column structure, while ocean currents and the distribution of oxygen minimum zones (OMZs) jointly control the spatial variability of carbon sink efficiency. Sedimentary records from representative sites suggest that increased terrigenous input, OMZ development, or higher sedimentation rates during glacials often enhance the preservation and burial of OC. However, in certain high-latitude or deep-water regions (e.g., the Sea of Okhotsk and the Sea of Japan), reduced marine productivity during glacials may lower OC burial efficiency. Furthermore, this study employs combined proxies such as δ13Corg and TOC/TN ratios to quantify the mixing characteristics and evolutionary history of different OC sources, and estimates of OC burial fluxes reveal the differential responses of regional carbon sinks to glacial–interglacial cycles. Despite significant progress, challenges remain in end-member construction, proxy standardization, and high-resolution spatiotemporal reconstructions. Future research should focus on cross-regional comparisons, coupled mechanistic modeling, and refined chronological controls. These efforts will enhance our understanding of the evolution of carbon sinks in Asian marginal seas and their geological roles in the global carbon cycle, contributing to more accurate predictions of oceanic carbon sink dynamics under future climate change scenarios.
The Asian continental marginal seas are among the most representative “source-to-sink” coupled systems globally. Understanding their organic carbon (OC) burial processes under the context of Quaternary climate change is of great significance for unraveling the evolution of the global carbon cycle. This study provides a comprehensive review of the sources, burial flux variations, and driving mechanisms of OC in sediments from major Asian marginal seas. The results indicate that during glacial periods, most marginal seas exhibit increased OC content and burial fluxes. In many regions, total organic carbon (TOC) content, organic carbon isotopic composition (δ13Corg), and TOC/total nitrogen (TOC/TN) ratios display cyclic variations on orbital timescales. Mechanistically, sea-level changes regulate the process and intensity of terrigenous material delivery, monsoon systems influence watershed erosion and water column structure, while ocean currents and the distribution of oxygen minimum zones (OMZs) jointly control the spatial variability of carbon sink efficiency. Sedimentary records from representative sites suggest that increased terrigenous input, OMZ development, or higher sedimentation rates during glacials often enhance the preservation and burial of OC. However, in certain high-latitude or deep-water regions (e.g., the Sea of Okhotsk and the Sea of Japan), reduced marine productivity during glacials may lower OC burial efficiency. Furthermore, this study employs combined proxies such as δ13Corg and TOC/TN ratios to quantify the mixing characteristics and evolutionary history of different OC sources, and estimates of OC burial fluxes reveal the differential responses of regional carbon sinks to glacial–interglacial cycles. Despite significant progress, challenges remain in end-member construction, proxy standardization, and high-resolution spatiotemporal reconstructions. Future research should focus on cross-regional comparisons, coupled mechanistic modeling, and refined chronological controls. These efforts will enhance our understanding of the evolution of carbon sinks in Asian marginal seas and their geological roles in the global carbon cycle, contributing to more accurate predictions of oceanic carbon sink dynamics under future climate change scenarios.
2025, 47(9): 23-42.
doi: 10.12284/hyxb2025108
Abstract:
Global warming and extreme thermal events have induced widespread coral bleaching, leading to the rapid degradation of coral reef ecosystems across the globe. Identifying functional genes associated with thermotolerance is crucial for elucidating coral adaptation mechanisms to climate warming and enabling scientific predictions regarding coral reef ecosystem trajectories. However, the current understanding of the molecular mechanism of coral holobiont in response to heat stress is very insufficient. Therefore, this paper reviews the research progress of functional genes related to coral thermal adaptation. Initially, pattern recognition receptors (PRRs), including Toll-like receptors (TLRs), play a crucial role in detecting heat stress and activating downstream signaling cascades, thereby initiating the immune response process. These responses primarily involve: upregulation of heat shock proteins (HSPs) to facilitate the refolding of denatured polypeptides; induction of antioxidant protein genes to mitigate oxidative damage caused by reactive oxygen species (ROS); genes associated with apoptosis and pyroptosis play a crucial role in eliminating “harmful” cells. As thermal stress intensifies, corals initiate a sophisticated network of cellular processes to maintain. As heat stress intensifies, corals initiate a series of complex processes to jointly maintain cellular homeostasis. This includes: rapid activation of photoprotective protein genes to repair the photosynthetic apparatus of Symbiodiniaceae; expression of host fluorescent proteins to maintain redox balance; calcium channel proteins maintain the stability of intracellular Ca2+ levels; modulation of metabolic pathways to ensure adequate nutrient supply; inhibition of cell cycle progression to conserve energy; maintenance of cytoskeletal integrity to preserve structural stability; and regulation of ubiquitin-proteasome system for protein quality control. Furthermore, recurrent thermal stress events can induce acclimatization in corals, potentially enhancing their thermal tolerance through multiple mechanisms: downregulation of host metabolic rate, protection of heat-sensitive proteins, and upregulation of antioxidant enzymes and ammonium assimilation pathways.
Global warming and extreme thermal events have induced widespread coral bleaching, leading to the rapid degradation of coral reef ecosystems across the globe. Identifying functional genes associated with thermotolerance is crucial for elucidating coral adaptation mechanisms to climate warming and enabling scientific predictions regarding coral reef ecosystem trajectories. However, the current understanding of the molecular mechanism of coral holobiont in response to heat stress is very insufficient. Therefore, this paper reviews the research progress of functional genes related to coral thermal adaptation. Initially, pattern recognition receptors (PRRs), including Toll-like receptors (TLRs), play a crucial role in detecting heat stress and activating downstream signaling cascades, thereby initiating the immune response process. These responses primarily involve: upregulation of heat shock proteins (HSPs) to facilitate the refolding of denatured polypeptides; induction of antioxidant protein genes to mitigate oxidative damage caused by reactive oxygen species (ROS); genes associated with apoptosis and pyroptosis play a crucial role in eliminating “harmful” cells. As thermal stress intensifies, corals initiate a sophisticated network of cellular processes to maintain. As heat stress intensifies, corals initiate a series of complex processes to jointly maintain cellular homeostasis. This includes: rapid activation of photoprotective protein genes to repair the photosynthetic apparatus of Symbiodiniaceae; expression of host fluorescent proteins to maintain redox balance; calcium channel proteins maintain the stability of intracellular Ca2+ levels; modulation of metabolic pathways to ensure adequate nutrient supply; inhibition of cell cycle progression to conserve energy; maintenance of cytoskeletal integrity to preserve structural stability; and regulation of ubiquitin-proteasome system for protein quality control. Furthermore, recurrent thermal stress events can induce acclimatization in corals, potentially enhancing their thermal tolerance through multiple mechanisms: downregulation of host metabolic rate, protection of heat-sensitive proteins, and upregulation of antioxidant enzymes and ammonium assimilation pathways.
2025, 47(9): 67-81.
doi: 10.12284/hyxb2025104
Abstract:
The coastal estuarine ecosystem is a unique ecosystem formed at the confluence of rivers and oceans. It has high primary productivity, can provide food and habitat for many organisms, and plays an important role in maintaining the stability of ecosystem structure. In order to explore the temporal and spatial dynamics of phytoplankton community and its environmental impact factors in Liuqing River Bay, four cruises were carried out at seven sampling sites in Liuqing River Bay in winter (March), spring (May), summer (August) and autumn (October) of 2023. The results showed that a total of 97 species of phytoplankton belonging to 56 genera and 3 phyla were identified in the four cruises. The phytoplankton community structure was mainly composed of diatoms and dinoflagellates. The cell abundance of phytoplankton in Liuqing River Bay has obvious temporal and spatial dynamic changes. From the time dimension, the average abundance of phytoplankton in the four seasons from high to low is winter, autumn, summer and spring. In terms of spatial distribution, the phytoplankton abundance in Liuqing River Bay reflects seasonal spatial distribution differences. The high abundance areas in spring, autumn and winter are concentrated in the northeast coastal waters, which are mainly driven by terrestrial input. The low abundance area is continuously distributed in the northwest sea area, which is mainly related to turbulent mixing. The overall spatial pattern is characterized by near-shore enrichment and offshore decline. Dominant species mainly include Bacillaria paradoxa, Coscinodiscus argus, Chaetoceros decipiens f. decipiens, Chaetoceros curvisetus, Coscinodiscus asteromphalus var. asteromphalus, Coscinodiscus granii of the phylum Bacillariophyta, and Ceratium macroceros, Ceratium tripos of the phylum Dinophyta. The biodiversity in summer and autumn was significantly higher than that in spring and winter. The results of redundancy analysis showed that salinity, DIN (dissolved inorganic nitrogen) and DIP (dissolved inorganic phosphorus) were the key environmental factors affecting the changes of phytoplankton community structure.
The coastal estuarine ecosystem is a unique ecosystem formed at the confluence of rivers and oceans. It has high primary productivity, can provide food and habitat for many organisms, and plays an important role in maintaining the stability of ecosystem structure. In order to explore the temporal and spatial dynamics of phytoplankton community and its environmental impact factors in Liuqing River Bay, four cruises were carried out at seven sampling sites in Liuqing River Bay in winter (March), spring (May), summer (August) and autumn (October) of 2023. The results showed that a total of 97 species of phytoplankton belonging to 56 genera and 3 phyla were identified in the four cruises. The phytoplankton community structure was mainly composed of diatoms and dinoflagellates. The cell abundance of phytoplankton in Liuqing River Bay has obvious temporal and spatial dynamic changes. From the time dimension, the average abundance of phytoplankton in the four seasons from high to low is winter, autumn, summer and spring. In terms of spatial distribution, the phytoplankton abundance in Liuqing River Bay reflects seasonal spatial distribution differences. The high abundance areas in spring, autumn and winter are concentrated in the northeast coastal waters, which are mainly driven by terrestrial input. The low abundance area is continuously distributed in the northwest sea area, which is mainly related to turbulent mixing. The overall spatial pattern is characterized by near-shore enrichment and offshore decline. Dominant species mainly include Bacillaria paradoxa, Coscinodiscus argus, Chaetoceros decipiens f. decipiens, Chaetoceros curvisetus, Coscinodiscus asteromphalus var. asteromphalus, Coscinodiscus granii of the phylum Bacillariophyta, and Ceratium macroceros, Ceratium tripos of the phylum Dinophyta. The biodiversity in summer and autumn was significantly higher than that in spring and winter. The results of redundancy analysis showed that salinity, DIN (dissolved inorganic nitrogen) and DIP (dissolved inorganic phosphorus) were the key environmental factors affecting the changes of phytoplankton community structure.
2025, 47(9): 82-90.
doi: 10.12284/hyxb2025092
Abstract:
This study is based on survey data of fish communities in the Zhoushan fishing ground and uses a resampling technique to simulate the random loss of rare and common species. It also employs a biomass proportion reduction method to simulate scenarios of biomass loss, in order to explore the mechanisms by which the loss of different ecological groups affects functional diversity in fish communities. The results show that although rare species account for only 3% of the total community biomass, their species richness constitutes nearly 40% of the community, indicating an important ecological niche within the community structure. The simulation of species loss scenarios revealed that the loss of rare species’ richness directly impacts the functional diversity indices, specifically leading to a decrease in functional richness and an increase in functional evenness, while functional divergence and Rao’s quadratic entropy indices showed no significant changes. In contrast, the loss of common species’ richness resulted in a decline in functional richness, while the other three functional diversity indices remained relatively stable. Under the biomass loss scenarios, the reduction in rare species’ biomass led to unchanged functional richness but declines in functional evenness, functional divergence, and Rao’s quadratic entropy indices. The functional evenness index exhibited a nonlinear decline that started slowly and then accelerated, while the other two indices showed linear decreasing patterns. In contrast, the loss of common species’ biomass caused the latter three indices to decline in a pattern that started rapidly and then slowed down. Rare species occupy unique functional niches in the community, with their functional traits distributed at the edges of the multidimensional functional space. They play a unique role in maintaining community functional diversity. Strengthening the protection of rare species and their habitats is a key strategy for maintaining regional ecosystem diversity and stability.
This study is based on survey data of fish communities in the Zhoushan fishing ground and uses a resampling technique to simulate the random loss of rare and common species. It also employs a biomass proportion reduction method to simulate scenarios of biomass loss, in order to explore the mechanisms by which the loss of different ecological groups affects functional diversity in fish communities. The results show that although rare species account for only 3% of the total community biomass, their species richness constitutes nearly 40% of the community, indicating an important ecological niche within the community structure. The simulation of species loss scenarios revealed that the loss of rare species’ richness directly impacts the functional diversity indices, specifically leading to a decrease in functional richness and an increase in functional evenness, while functional divergence and Rao’s quadratic entropy indices showed no significant changes. In contrast, the loss of common species’ richness resulted in a decline in functional richness, while the other three functional diversity indices remained relatively stable. Under the biomass loss scenarios, the reduction in rare species’ biomass led to unchanged functional richness but declines in functional evenness, functional divergence, and Rao’s quadratic entropy indices. The functional evenness index exhibited a nonlinear decline that started slowly and then accelerated, while the other two indices showed linear decreasing patterns. In contrast, the loss of common species’ biomass caused the latter three indices to decline in a pattern that started rapidly and then slowed down. Rare species occupy unique functional niches in the community, with their functional traits distributed at the edges of the multidimensional functional space. They play a unique role in maintaining community functional diversity. Strengthening the protection of rare species and their habitats is a key strategy for maintaining regional ecosystem diversity and stability.
2025, 47(9): 91-100.
doi: 10.12284/hyxb2025098
Abstract:
Nearshore coral reefs are frequently subjected to prolonged exposure to high levels of suspended particulate matter (SPM). However, the tolerance threshold of scleractinian corals to SPM remains inadequatedly understood, complicating the protection and management of nearshore scleractinian coral communities. In this study, we investigated the physiological responses of Dipsastraea speciosa and Cyphastrea sp., the dominant species of scleractinian corals in the Dongshan waters, which represent the northern distribution limit of scleractinian coral communities, under varying SPM mass concentrations (0 mg/L, 35 mg/L, 50 mg/L and 100 mg/L). A SPM-controlled simulated system was employed by injecting SPM into experimental tanks to regulate its concentration over a 28-day period. Morphological characteristics and a series of photosynthetic physiological parameters were used as indicators. The results indicated that the polyps of both coral species exposed to three groups of SPM treatments exhibited shrinkageduring the initial stages of the experiment, but quickly recovered over time. No individual of coral bleaching or mortality were observed. Additionally, both coral species demonstrated significant photosynthetic physiological plasticity, evidenced by rising ΦPSⅡ values with SPM mass concentration increased, reaching a maximum at 100 mg/L. This suggests that the two coral species can mitigate light shading by enhancing their photosynthetic efficiency in response to high SPM mass concentrations. Furthermore, Fv/Fm ratios, chlorophyll content, and zooxanthella density for both coral species remained relatively stable under high SPM exposure, indicating that their photosynthetic performance remained healthy despite elevated SPM levels. This implies that the tolerance threshold for SPM mass concentration of these two scleractinian corals to SPM may exceed 100 mg/L. This study is the first experiment in China to successfully maintain high SPM levels over an extended period, and the findings provide essential data for the protection and management of scleractinian coral communities in China.
Nearshore coral reefs are frequently subjected to prolonged exposure to high levels of suspended particulate matter (SPM). However, the tolerance threshold of scleractinian corals to SPM remains inadequatedly understood, complicating the protection and management of nearshore scleractinian coral communities. In this study, we investigated the physiological responses of Dipsastraea speciosa and Cyphastrea sp., the dominant species of scleractinian corals in the Dongshan waters, which represent the northern distribution limit of scleractinian coral communities, under varying SPM mass concentrations (0 mg/L, 35 mg/L, 50 mg/L and 100 mg/L). A SPM-controlled simulated system was employed by injecting SPM into experimental tanks to regulate its concentration over a 28-day period. Morphological characteristics and a series of photosynthetic physiological parameters were used as indicators. The results indicated that the polyps of both coral species exposed to three groups of SPM treatments exhibited shrinkageduring the initial stages of the experiment, but quickly recovered over time. No individual of coral bleaching or mortality were observed. Additionally, both coral species demonstrated significant photosynthetic physiological plasticity, evidenced by rising ΦPSⅡ values with SPM mass concentration increased, reaching a maximum at 100 mg/L. This suggests that the two coral species can mitigate light shading by enhancing their photosynthetic efficiency in response to high SPM mass concentrations. Furthermore, Fv/Fm ratios, chlorophyll content, and zooxanthella density for both coral species remained relatively stable under high SPM exposure, indicating that their photosynthetic performance remained healthy despite elevated SPM levels. This implies that the tolerance threshold for SPM mass concentration of these two scleractinian corals to SPM may exceed 100 mg/L. This study is the first experiment in China to successfully maintain high SPM levels over an extended period, and the findings provide essential data for the protection and management of scleractinian coral communities in China.
2025, 47(9): 101-114.
doi: 10.12284/hyxb2025100
Abstract:
Symbiodiniaceae are indispensable partners in the coral symbiotic system, and different species exhibit varying sensitivities to environmental stress, thereby influencing the environmental adaptability of their coral hosts. This study investigates the stress response patterns of two widely distributed coral symbiotic Symbiodiniaceae species—environmentally sensitive Cladocopium goreaui and environmentally tolerant Durusdinium trenchii—under heat stress from the perspective of lipid metabolism. The results showed that heat stress significantly affected their cell density, photosynthetic pigment content, photochemical efficiency of photosystem Ⅱ (Fv/Fm), and antioxidant activity, with statistically significant differences (P < 0.05). Lipidomics revealed that lipid-differentiated metabolites such as phosphatidylcholine, triglycerides, phosphatidylethanolamine and lysophosphatidylcholine were significantly enriched in glycerophospholipid metabolism, triglyceride metabolism, and polyunsaturated fatty acid-related metabolic pathways in response to heat stress in C. goreaui and D. trenchii. Notably, the two species exhibited significant differences in sphingolipid metabolism: D. trenchii downregulated ceramide levels to reduce oxidative stress damage, regulate autophagy, and adapt to changes in membrane fluidity, whereas C. goreaui primarily upregulated lipid molecules rich in polyunsaturated fatty acids to maintain membrane stability and regulate signal transduction. A deeper understanding of the lipid metabolic stress response mechanisms of Symbiodiniaceae with different environmental sensitivities under heat stress provides new insights into enhancing coral adaptability to environmental changes from a symbiotic partner perspective.
Symbiodiniaceae are indispensable partners in the coral symbiotic system, and different species exhibit varying sensitivities to environmental stress, thereby influencing the environmental adaptability of their coral hosts. This study investigates the stress response patterns of two widely distributed coral symbiotic Symbiodiniaceae species—environmentally sensitive Cladocopium goreaui and environmentally tolerant Durusdinium trenchii—under heat stress from the perspective of lipid metabolism. The results showed that heat stress significantly affected their cell density, photosynthetic pigment content, photochemical efficiency of photosystem Ⅱ (Fv/Fm), and antioxidant activity, with statistically significant differences (P < 0.05). Lipidomics revealed that lipid-differentiated metabolites such as phosphatidylcholine, triglycerides, phosphatidylethanolamine and lysophosphatidylcholine were significantly enriched in glycerophospholipid metabolism, triglyceride metabolism, and polyunsaturated fatty acid-related metabolic pathways in response to heat stress in C. goreaui and D. trenchii. Notably, the two species exhibited significant differences in sphingolipid metabolism: D. trenchii downregulated ceramide levels to reduce oxidative stress damage, regulate autophagy, and adapt to changes in membrane fluidity, whereas C. goreaui primarily upregulated lipid molecules rich in polyunsaturated fatty acids to maintain membrane stability and regulate signal transduction. A deeper understanding of the lipid metabolic stress response mechanisms of Symbiodiniaceae with different environmental sensitivities under heat stress provides new insights into enhancing coral adaptability to environmental changes from a symbiotic partner perspective.
2025, 47(9): 115-128.
doi: 10.12284/hyxb2025106
Abstract:
To evaluate the toxicological effects of polystyrene microplastics (PS-MPs) on the intestinal health of Sebastiscus marmoratus, individuals were exposed to PS-MP solutions at concentrations of 0, 1, and 10 mg/L for 21 days. A combination of analytical approaches, including enrichment analysis, histological examination, transcriptomic profiling, and 16S rRNA gene sequencing, was employed to assess alterations in intestinal morphology, gene expression, and microbial community composition. The results demonstrated a time-dependent accumulation of PS-MPs in the intestines, with mass fraction reaching 16.20 × 10–6 (μg/g) by day 7. Histopathological analysis revealed dose-dependent intestinal damage: at 1 mg/L, necrosis, detachment, and vacuolar degeneration of mucosal cells were observed; at 10 mg/L, severe villus atrophy, necrosis, vacuolization, and significant reductions in intestinal wall thickness, muscle layer thickness, and villus length and width were evident. Transcriptomic analysis identified 313 and 169 differentially expressed genes (DEGs) after 7 and 21 days of exposure, respectively. KEGG pathway enrichment revealed that DEGs at day 7 were primarily involved in the p53 signaling pathway, starch and sucrose metabolism, and Toll-like receptor signaling pathway. By day 21, enrichment was observed in pathways related to steroid biosynthesis, arachidonic acid metabolism, and NOD-like receptor signaling pathway. Although no significant changes in microbial composition were detected at the phylum level, notable increases in the relative abundances of Fusobacteriaceae, Vibrionaceae at the family level and Cetobacterium, Prevotella at the genus level were observed, potentially indicating enhanced intestinal barrier repair and anti-inflammatory responses. In conclusion, PS-MP exposure resulted in structural damage to intestinal tissues, disruption of the mucosal barrier, and inflammatory responses in S. marmoratus, ultimately compromising organismal health.
To evaluate the toxicological effects of polystyrene microplastics (PS-MPs) on the intestinal health of Sebastiscus marmoratus, individuals were exposed to PS-MP solutions at concentrations of 0, 1, and 10 mg/L for 21 days. A combination of analytical approaches, including enrichment analysis, histological examination, transcriptomic profiling, and 16S rRNA gene sequencing, was employed to assess alterations in intestinal morphology, gene expression, and microbial community composition. The results demonstrated a time-dependent accumulation of PS-MPs in the intestines, with mass fraction reaching 16.20 × 10–6 (μg/g) by day 7. Histopathological analysis revealed dose-dependent intestinal damage: at 1 mg/L, necrosis, detachment, and vacuolar degeneration of mucosal cells were observed; at 10 mg/L, severe villus atrophy, necrosis, vacuolization, and significant reductions in intestinal wall thickness, muscle layer thickness, and villus length and width were evident. Transcriptomic analysis identified 313 and 169 differentially expressed genes (DEGs) after 7 and 21 days of exposure, respectively. KEGG pathway enrichment revealed that DEGs at day 7 were primarily involved in the p53 signaling pathway, starch and sucrose metabolism, and Toll-like receptor signaling pathway. By day 21, enrichment was observed in pathways related to steroid biosynthesis, arachidonic acid metabolism, and NOD-like receptor signaling pathway. Although no significant changes in microbial composition were detected at the phylum level, notable increases in the relative abundances of Fusobacteriaceae, Vibrionaceae at the family level and Cetobacterium, Prevotella at the genus level were observed, potentially indicating enhanced intestinal barrier repair and anti-inflammatory responses. In conclusion, PS-MP exposure resulted in structural damage to intestinal tissues, disruption of the mucosal barrier, and inflammatory responses in S. marmoratus, ultimately compromising organismal health.
2025, 47(9): 129-144.
doi: 10.12284/hyxb2025110
Abstract:
Anchisquilla fasciata belongs to the Squillidae (Latreille, 1802). In this study, the complete mitochondrial genome of Anchisquilla fasciata was obtained through next-generation sequencing technology. Analysis of the basic structural characteristics of the genome revealed that it contains a total of 37 genes, including 13 protein-coding genes (PCGs), 2 rRNA genes, and 22 tRNA genes. Analysis of nucleotide composition showed that A had the highest content at 35.42%, while G had the lowest content at 12.83%. Selection pressure analysis was conducted on the mitochondrial genomes of 11 species within the Squillidae, and it was found that all PCGs were under purifying selection. Additionally, a phylogenetic tree was constructed using the 13 PCGs of mitochondrial genomes from two subclasses of Malacostraca, revealing that the Squillidae forms a monophyletic group with species within the family branching off into a distinct clade, showing clear differentiation from other related Hoplocarida (such as the Lysiosquillidae). Comparison of mitochondrial gene rearrangements within Malacostraca showed that the Stomatopoda did not exhibit any rearrangements. The reconstructed chronogram of divergence times within the Hoplocarida indicated that the earliest diversification of existing species occurred during the Cretaceous period of the Mesozoic era, with a significant diversification of species in the Cenozoic era. These results will provide better insights into the phylogenetic relationships among different species of Squillidae and the evolutionary positions and relationships among subclasses within Malacostraca.
Anchisquilla fasciata belongs to the Squillidae (Latreille, 1802). In this study, the complete mitochondrial genome of Anchisquilla fasciata was obtained through next-generation sequencing technology. Analysis of the basic structural characteristics of the genome revealed that it contains a total of 37 genes, including 13 protein-coding genes (PCGs), 2 rRNA genes, and 22 tRNA genes. Analysis of nucleotide composition showed that A had the highest content at 35.42%, while G had the lowest content at 12.83%. Selection pressure analysis was conducted on the mitochondrial genomes of 11 species within the Squillidae, and it was found that all PCGs were under purifying selection. Additionally, a phylogenetic tree was constructed using the 13 PCGs of mitochondrial genomes from two subclasses of Malacostraca, revealing that the Squillidae forms a monophyletic group with species within the family branching off into a distinct clade, showing clear differentiation from other related Hoplocarida (such as the Lysiosquillidae). Comparison of mitochondrial gene rearrangements within Malacostraca showed that the Stomatopoda did not exhibit any rearrangements. The reconstructed chronogram of divergence times within the Hoplocarida indicated that the earliest diversification of existing species occurred during the Cretaceous period of the Mesozoic era, with a significant diversification of species in the Cenozoic era. These results will provide better insights into the phylogenetic relationships among different species of Squillidae and the evolutionary positions and relationships among subclasses within Malacostraca.
2025, 47(9): 145-154.
doi: 10.12284/hyxb2025102
Abstract:
Calcium carbonate (CaCO3), as a major component of shells, interacts with the organic matter framework to form shells and provide protection for mollusks. Ca2+ is an important component of CaCO3, and its acquisition, transport, and precipitation processes can significantly affect calcium carbonate deposition in mollusks. However, there is still a lack of clarity regarding the process of calcium carbonate deposition and mechanism of related genes in forming shells. Calmodulin (CaM) is a protein widely found in eukaryotic cells and specifically binds to Ca2+, which is mainly involved in a variety of physiological processes such as cellular signal transduction, regulation of target enzyme activities and regulation of Ca2+ homeostasis. In order to investigate the relationship between CaM gene and calcium carbonate deposition in shells, we performed molecular identification and expression characterization of CaM gene in Sinonovacula constricta (ScCaM), and investigated the Ca2+-binding activity of the recombinant protein ScCaM and its role in calcium carbonate deposition. The results showed that the ScCaM gene encoded a total of 149 amino acids and contained four consecutive EF-hand structural domains. ScCaM was expressed in all tissues, with the expression level in gill and mantle tissues being significantly higher than in foot, siphon, adductor muscle and hepatopancreas tissues (P < 0.05). Furthermore, the content of calcium carbonate in shells was positively proportional to their shell weight. Meanwhile, individuals with larger shell weights had higher expression levels of ScCaM. ScCaM recombinant protein had calcium ion binding activity, which can accelerate the rate of calcium carbonate deposition, and the promotion effect showed an obvious protein concentration dependence. The results showed that ScCaM gene/protein expression was closely related to shell calcium carbonate content: elevated ScCaM gene/protein expression could enhance Ca2+ transport efficiency, promote shell calcium carbonate deposition, and thus increase shell weight. This study preliminarily investigated the role of ScCaM gene in shell calcium carbonate deposition, and provided a theoretical basis for analyzing the molecular mechanism of shell formation in S. constricta.
Calcium carbonate (CaCO3), as a major component of shells, interacts with the organic matter framework to form shells and provide protection for mollusks. Ca2+ is an important component of CaCO3, and its acquisition, transport, and precipitation processes can significantly affect calcium carbonate deposition in mollusks. However, there is still a lack of clarity regarding the process of calcium carbonate deposition and mechanism of related genes in forming shells. Calmodulin (CaM) is a protein widely found in eukaryotic cells and specifically binds to Ca2+, which is mainly involved in a variety of physiological processes such as cellular signal transduction, regulation of target enzyme activities and regulation of Ca2+ homeostasis. In order to investigate the relationship between CaM gene and calcium carbonate deposition in shells, we performed molecular identification and expression characterization of CaM gene in Sinonovacula constricta (ScCaM), and investigated the Ca2+-binding activity of the recombinant protein ScCaM and its role in calcium carbonate deposition. The results showed that the ScCaM gene encoded a total of 149 amino acids and contained four consecutive EF-hand structural domains. ScCaM was expressed in all tissues, with the expression level in gill and mantle tissues being significantly higher than in foot, siphon, adductor muscle and hepatopancreas tissues (P < 0.05). Furthermore, the content of calcium carbonate in shells was positively proportional to their shell weight. Meanwhile, individuals with larger shell weights had higher expression levels of ScCaM. ScCaM recombinant protein had calcium ion binding activity, which can accelerate the rate of calcium carbonate deposition, and the promotion effect showed an obvious protein concentration dependence. The results showed that ScCaM gene/protein expression was closely related to shell calcium carbonate content: elevated ScCaM gene/protein expression could enhance Ca2+ transport efficiency, promote shell calcium carbonate deposition, and thus increase shell weight. This study preliminarily investigated the role of ScCaM gene in shell calcium carbonate deposition, and provided a theoretical basis for analyzing the molecular mechanism of shell formation in S. constricta.
2025, 47(9): 43-54.
doi: 10.12284/hyxb2025094
Abstract:
Stable carbon isotope (δ13C) and nitrogen isotope (δ15N) compositions are powerful tools for elucidating fish physiology, trophic interactions, and origin. However, pretreatment methods can substantially influence isotopic results, and the underlying mechanisms remain poorly understood. This study investigates the effects of lipid removal from muscle and acid leaching of scales on the δ13C and δ15N values of large yellow croaker (Larimichthys crocea), a major mariculture species in China. We found that lipid extraction significantly increased muscle δ13C, while acid leaching decreased scale δ13C. An isotope mixing model effectively explained these δ13C variations. Conversely, both pretreatments increased δ15N, suggesting potential losses of specific nitrogen isotope signals. Utilizing a dynamic equilibrium model, we established a theoretical relationship between carbon and nitrogen isotopes in muscle and scales, validating scales as a muscle proxy for nitrogen isotope analysis. This research provides critical baseline data for understanding stable isotope heterogeneity in large yellow croaker, contributes to our understanding of inter-tissue metabolic dynamics, and supports the application of non-lethal sampling in fish stable isotope studies.
Stable carbon isotope (δ13C) and nitrogen isotope (δ15N) compositions are powerful tools for elucidating fish physiology, trophic interactions, and origin. However, pretreatment methods can substantially influence isotopic results, and the underlying mechanisms remain poorly understood. This study investigates the effects of lipid removal from muscle and acid leaching of scales on the δ13C and δ15N values of large yellow croaker (Larimichthys crocea), a major mariculture species in China. We found that lipid extraction significantly increased muscle δ13C, while acid leaching decreased scale δ13C. An isotope mixing model effectively explained these δ13C variations. Conversely, both pretreatments increased δ15N, suggesting potential losses of specific nitrogen isotope signals. Utilizing a dynamic equilibrium model, we established a theoretical relationship between carbon and nitrogen isotopes in muscle and scales, validating scales as a muscle proxy for nitrogen isotope analysis. This research provides critical baseline data for understanding stable isotope heterogeneity in large yellow croaker, contributes to our understanding of inter-tissue metabolic dynamics, and supports the application of non-lethal sampling in fish stable isotope studies.
2025, 47(9): 55-66.
doi: 10.12284/hyxb2025096
Abstract:
A self-developed separation and enrichment device was employed to investigate the pretreatment method for isolating and concentrating 15 trace elements (Al, Sc, V, Fe, Co, Ni, Cu, Zn, Ga, Cd, Nd, Pb, Bi, Th, and U) from seawater using Toyopearl AF-Chelate 650M chelating resin. Key parameters including sample loading pH, washing solution composition and volume, and eluent type and volume were optimized. High-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) was used for accurate determination. The results demonstrated that when 8.92 mL of seawater sample was mixed with acetic acid-ammonium acetate buffer solution at a 1:1 ratio (loading pH = 5.25) and loaded onto the resin, matrix impurities could be effectively removed by washing with 8.0 mL of Milli-Q water. After matrix removal, the adsorbed trace elements were quantitatively recovered by elution with 2.25 mL of 0.8 mol/L HNO3. Rh was added as an internal standard to the eluent prior to HR-ICP-MS analysis. Method blanks ranged from 0.27 pg (Cd) to 52.5 pg (Al), with method detection limits between 0.06 ng/L (Cd) and 1.67 ng/L (Zn). Excellent linearity (R2 > 0.999) was achieved across the concentration range of 0.01−50.0 μg/L. The method was validated using certified reference materials GBW(E)080040 and CASS-6. For GBW(E)080040, measured mass concentrations of Cu, Zn, Cd and Pb agreed well with certified values (relative error < 4.1%, RSD < 4.1%), with spike recoveries of 92.6%−107% for all 15 elements. Results for CASS-6 also showed good agreement with certified and reported values (RSD < 6.4%). This method features simple and rapid pretreatment, efficient matrix removal, low detection limits, high accuracy and good precision, making it suitable for simultaneous determination of 15 trace elements in various water matrices including natural freshwater, drinking water, estuarine and marine waters.
A self-developed separation and enrichment device was employed to investigate the pretreatment method for isolating and concentrating 15 trace elements (Al, Sc, V, Fe, Co, Ni, Cu, Zn, Ga, Cd, Nd, Pb, Bi, Th, and U) from seawater using Toyopearl AF-Chelate 650M chelating resin. Key parameters including sample loading pH, washing solution composition and volume, and eluent type and volume were optimized. High-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) was used for accurate determination. The results demonstrated that when 8.92 mL of seawater sample was mixed with acetic acid-ammonium acetate buffer solution at a 1:1 ratio (loading pH = 5.25) and loaded onto the resin, matrix impurities could be effectively removed by washing with 8.0 mL of Milli-Q water. After matrix removal, the adsorbed trace elements were quantitatively recovered by elution with 2.25 mL of 0.8 mol/L HNO3. Rh was added as an internal standard to the eluent prior to HR-ICP-MS analysis. Method blanks ranged from 0.27 pg (Cd) to 52.5 pg (Al), with method detection limits between 0.06 ng/L (Cd) and 1.67 ng/L (Zn). Excellent linearity (R2 > 0.999) was achieved across the concentration range of 0.01−50.0 μg/L. The method was validated using certified reference materials GBW(E)080040 and CASS-6. For GBW(E)080040, measured mass concentrations of Cu, Zn, Cd and Pb agreed well with certified values (relative error < 4.1%, RSD < 4.1%), with spike recoveries of 92.6%−107% for all 15 elements. Results for CASS-6 also showed good agreement with certified and reported values (RSD < 6.4%). This method features simple and rapid pretreatment, efficient matrix removal, low detection limits, high accuracy and good precision, making it suitable for simultaneous determination of 15 trace elements in various water matrices including natural freshwater, drinking water, estuarine and marine waters.
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