Latest Articles
Articles in press have been peer-reviewed and accepted, which are not yet assigned to volumes/issues, but are citable by Digital Object Identifier (DOI).
Display Method:
, Available online , doi: 10.12284/hyxb20260000
Abstract:
Artemia is important live bait in the cultivation of marine fish and crustacean seedlings, with more than 90% derived from wild Artemia resources. In order to study the effects of environmental changes and the unique aquaculture and harvest management on the morphometrical and genetic characteristics of Artemia in Yuncheng Salt Lake, Shanxi Province in the past 30 years, Artemia cysts collected in 1993 (YC-1993), 2019 (YC-2019) and 2023 (YC-2023) from Yuncheng Salt Lake were cultured and morphometrical measurements were conducted. Specific-locus amplified fragments sequencing (SLAF-seq) was used for population genetics analysis. The results showed that the YC-2023 group was extremely significantly larger than the YC-1993 group in terms of body length, abdominal length, ovary width, interocular distance, eye diameter, second antenna length, and peripheral claspers, while the cyst diameter of the YC-2023 group was significantly smaller than that of the YC-1993 group. The results of genetic analysis showed that the YC-2023 group had the lowest genetic diversity. The polymorphism information content (PIC) of three populations was between 0.252 and 0.305, showing moderate polymorphism (0.25<PIC<0.5). The Fst value of the genetic differentiation coefficient between the YC-2019 and YC-2023 populations is 0.087, indicating moderate genetic differentiation (0.05<Fst<0.15). However, the Fst value between the YC-1993 and the other two populations is 0.151, indicating a high degree of genetic differentiation (0.15<Fst<0.25). Phylogenetic tree, principal component analysis, the kinship heat map and Admixture analysis further revealed that although there was a certain degree of genetic differentiation among the three populations, their genetic information originated from the same original ancestor. The morphometrical traits and genetic variations of Yuncheng Artemia may result from genetic selection and genetic drift caused by the environmental changes that Yuncheng Salt Lake has undergone in recent years, and unique aquaculture and harvest management. This study will provide theoretical support for the conservation and utilization of Artemia germplasm resources in Yuncheng Salt Lake.
Artemia is important live bait in the cultivation of marine fish and crustacean seedlings, with more than 90% derived from wild Artemia resources. In order to study the effects of environmental changes and the unique aquaculture and harvest management on the morphometrical and genetic characteristics of Artemia in Yuncheng Salt Lake, Shanxi Province in the past 30 years, Artemia cysts collected in 1993 (YC-1993), 2019 (YC-2019) and 2023 (YC-2023) from Yuncheng Salt Lake were cultured and morphometrical measurements were conducted. Specific-locus amplified fragments sequencing (SLAF-seq) was used for population genetics analysis. The results showed that the YC-2023 group was extremely significantly larger than the YC-1993 group in terms of body length, abdominal length, ovary width, interocular distance, eye diameter, second antenna length, and peripheral claspers, while the cyst diameter of the YC-2023 group was significantly smaller than that of the YC-1993 group. The results of genetic analysis showed that the YC-2023 group had the lowest genetic diversity. The polymorphism information content (PIC) of three populations was between 0.252 and 0.305, showing moderate polymorphism (0.25<PIC<0.5). The Fst value of the genetic differentiation coefficient between the YC-2019 and YC-2023 populations is 0.087, indicating moderate genetic differentiation (0.05<Fst<0.15). However, the Fst value between the YC-1993 and the other two populations is 0.151, indicating a high degree of genetic differentiation (0.15<Fst<0.25). Phylogenetic tree, principal component analysis, the kinship heat map and Admixture analysis further revealed that although there was a certain degree of genetic differentiation among the three populations, their genetic information originated from the same original ancestor. The morphometrical traits and genetic variations of Yuncheng Artemia may result from genetic selection and genetic drift caused by the environmental changes that Yuncheng Salt Lake has undergone in recent years, and unique aquaculture and harvest management. This study will provide theoretical support for the conservation and utilization of Artemia germplasm resources in Yuncheng Salt Lake.
, Available online
Abstract:
This study examines the mechanism of the unexpected absence of bottom hypoxia in the lower Pearl River Estuary during summer 2023 through integrated analysis of hydrological, biogeochemical and physical drivers. The Pear River discharge during 2023 summer was only 51% of the historical average summer average. This led to a 45% reduction in riverine nutrient fluxes and a sharp decline in marine-sourced organic carbon production. Persistent northeasterly downwelling-favorable winds during the 15 days preceding sampling weakened stratification (stratification factor of 0.074 ± 0.20 during 2023 cruise versus 0.14 ± 0.17, 0.38 ± 0.50 and 0.18 ± 0.20 during other three cruises of 2015, 2017 and 2018 when hypoxia occurred) enhanced vertical mixing and oxygen replenishment in the bottom water. The reduced river discharge also shortened the water residence time in the estuary to 1.8 days, compared to 3.1 days under average summer discharge conditions, thereby limiting the oxygen-depleting effect of organic matter degradation. The synergistic effect of these factors led to the absence of bottom-water hypoxia in the Pearl River Estuary in summer 2023. This study reveals the important regulating role of extreme hydro-meteorological conditions in the formation of estuarine hypoxia.
This study examines the mechanism of the unexpected absence of bottom hypoxia in the lower Pearl River Estuary during summer 2023 through integrated analysis of hydrological, biogeochemical and physical drivers. The Pear River discharge during 2023 summer was only 51% of the historical average summer average. This led to a 45% reduction in riverine nutrient fluxes and a sharp decline in marine-sourced organic carbon production. Persistent northeasterly downwelling-favorable winds during the 15 days preceding sampling weakened stratification (stratification factor of 0.074 ± 0.20 during 2023 cruise versus 0.14 ± 0.17, 0.38 ± 0.50 and 0.18 ± 0.20 during other three cruises of 2015, 2017 and 2018 when hypoxia occurred) enhanced vertical mixing and oxygen replenishment in the bottom water. The reduced river discharge also shortened the water residence time in the estuary to 1.8 days, compared to 3.1 days under average summer discharge conditions, thereby limiting the oxygen-depleting effect of organic matter degradation. The synergistic effect of these factors led to the absence of bottom-water hypoxia in the Pearl River Estuary in summer 2023. This study reveals the important regulating role of extreme hydro-meteorological conditions in the formation of estuarine hypoxia.
, Available online , doi: 10.12284/hyxb20260012
Abstract:
The Arctic is a climate-sensitive region where Arctic Amplification is influenced by aerosol radiative forcing. Aerosol Optical Depth (AOD) as key parameter characterizing the extinction properties of atmospheric aerosols, plays a critical role in understanding the influence of aerosols on environmental and climate systems. However, single-satellite AOD products exhibit large uncertainties and data gaps in the Arctic due to sensor limitations and complex surface conditions. The Bayesian Maximum Entropy (BME) method is commonly used for AOD data fusion, yet the traditional BME approach, which employs least squares to model covariance, struggles to effectively handle the complexity and non-stationarity of high-dimensional parameter spaces. Based on AOD products from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Multi-angle Imaging Spectro Radiometer (MISR), this study introduces a Particle Swarm Optimization (PSO) algorithm with global search capability to improve the covariance modeling process, resulting in a PSO-BME fusion algorithm that enhances the stability and accuracy of data integration. The results demonstrate that the PSO-BME method effectively integrates MODIS and MISR AOD data and successfully fills data gaps. In regions covered by both sources, the fused AOD achieves an RMSE of 0.055, an EE of 78%, an MAE of 0.04, and a correlation coefficient of 0.7, while maintaining acceptable accuracy in unobserved areas. The annual spatial coverage increased from 15.45% (MODIS) and 1.45% (MISR) to 32.7%. Spatiotemporal distribution analysis shows that the fusion product significantly improves spatial continuity and more accurately reflects overall AOD variations. Furthermore, the spatiotemporal evolution patterns reveal that aerosol distribution in the Arctic is influenced by both local meteorological conditions and cross-border transport of pollutants from mid- and low-latitudes.
The Arctic is a climate-sensitive region where Arctic Amplification is influenced by aerosol radiative forcing. Aerosol Optical Depth (AOD) as key parameter characterizing the extinction properties of atmospheric aerosols, plays a critical role in understanding the influence of aerosols on environmental and climate systems. However, single-satellite AOD products exhibit large uncertainties and data gaps in the Arctic due to sensor limitations and complex surface conditions. The Bayesian Maximum Entropy (BME) method is commonly used for AOD data fusion, yet the traditional BME approach, which employs least squares to model covariance, struggles to effectively handle the complexity and non-stationarity of high-dimensional parameter spaces. Based on AOD products from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Multi-angle Imaging Spectro Radiometer (MISR), this study introduces a Particle Swarm Optimization (PSO) algorithm with global search capability to improve the covariance modeling process, resulting in a PSO-BME fusion algorithm that enhances the stability and accuracy of data integration. The results demonstrate that the PSO-BME method effectively integrates MODIS and MISR AOD data and successfully fills data gaps. In regions covered by both sources, the fused AOD achieves an RMSE of 0.055, an EE of 78%, an MAE of 0.04, and a correlation coefficient of 0.7, while maintaining acceptable accuracy in unobserved areas. The annual spatial coverage increased from 15.45% (MODIS) and 1.45% (MISR) to 32.7%. Spatiotemporal distribution analysis shows that the fusion product significantly improves spatial continuity and more accurately reflects overall AOD variations. Furthermore, the spatiotemporal evolution patterns reveal that aerosol distribution in the Arctic is influenced by both local meteorological conditions and cross-border transport of pollutants from mid- and low-latitudes.
, Available online , doi: 10.12284/hyxb2026000
Abstract:
Settling velocity is a key parameter in the dynamic characteristics of fine-grained cohesive sediments, holding significant importance for understanding the movement patterns of fine sediments and predicting the evolution of scour and fill in port channels. Due to their small particle size, large specific surface area, and tendency for flocculation between particles, the settling velocity of fine-grained cohesive sediments is influenced by multiple factors, with salinity and sediment concentration exerting particularly significant effects. Using in situ sediment samples collected from the Jiaxing Port channel, 42 sets of hydrostatic settling velocity tests were conducted in a sedimentation tank. These tests covered a salinity range of 0–15‰ and a sediment concentration range of 1–20 kg/m3, examining the combined effects of varying salinity and sediment concentration. The results indicate that when salinity is below 7–9‰, settling velocity increases gradually with rising salinity. beyond this range, settling velocity gradually decreased and stabilised with further salinity increases. For sediment concentrations below 8–10 kg/m3, velocity increased with concentration; above this threshold, velocity progressively decreased. Furthermore, compared to the influence of individual factors, salinity and sediment concentration exhibit synergistic effects, with their combined impact exerting a greater influence on sedimentation velocity. A comparative analysis was conducted on the effects of salinity and sediment concentration on sedimentation velocity under varying conditions. A formula for the hydrostatic sedimentation velocity of fine-grained sediments under different salinity and sediment concentration conditions was established through fitting, and validated against previous research findings. These results may provide relevant reference for studies on sediment transport patterns within the Jiaxing Port channel.
Settling velocity is a key parameter in the dynamic characteristics of fine-grained cohesive sediments, holding significant importance for understanding the movement patterns of fine sediments and predicting the evolution of scour and fill in port channels. Due to their small particle size, large specific surface area, and tendency for flocculation between particles, the settling velocity of fine-grained cohesive sediments is influenced by multiple factors, with salinity and sediment concentration exerting particularly significant effects. Using in situ sediment samples collected from the Jiaxing Port channel, 42 sets of hydrostatic settling velocity tests were conducted in a sedimentation tank. These tests covered a salinity range of 0–15‰ and a sediment concentration range of 1–20 kg/m3, examining the combined effects of varying salinity and sediment concentration. The results indicate that when salinity is below 7–9‰, settling velocity increases gradually with rising salinity. beyond this range, settling velocity gradually decreased and stabilised with further salinity increases. For sediment concentrations below 8–10 kg/m3, velocity increased with concentration; above this threshold, velocity progressively decreased. Furthermore, compared to the influence of individual factors, salinity and sediment concentration exhibit synergistic effects, with their combined impact exerting a greater influence on sedimentation velocity. A comparative analysis was conducted on the effects of salinity and sediment concentration on sedimentation velocity under varying conditions. A formula for the hydrostatic sedimentation velocity of fine-grained sediments under different salinity and sediment concentration conditions was established through fitting, and validated against previous research findings. These results may provide relevant reference for studies on sediment transport patterns within the Jiaxing Port channel.
, Available online
Abstract:
The Miaodao Archipelago in Shandong Province are rich in seaweed resources and hold great potential for nearshore marine carbon sinks. However, fundamental data and research related to the seaweed beds in this region remain scarce, which astricts the calculation and evaluation to carbon sink of seaweed beds. Therefore, this study aimed to complement the gap in baseline information regarding seaweed beds in the Miaodao Archipelago. In this study, 10 residential islands of Miaodao archipelago in Shandong Province were selected and the distribution of seaweed fields in the subtidal zone was investigated and sampled by scuba diving. Seaweed resource information in the seaweed beds, including the distribution and area of seaweed beds, species composition, biomass, dominant species, and community diversity, was identified and counted, and then combined with the environmental context, the community structure characteristics of the seaweed beds in the 10 islands were clustered. A total of 34 species of macroalgae were collected, belonging to 21 families and 25 genera. Among them were 18 species of red algae (11 families, 15 genera), 4 species of green algae (2 families, 2 genera), and 12 species of brown algae (8 families, 8 genera). The dominant macroalgal species in the region included Saccharina japonica, Undaria pinnatifida, Sargassum muticum, Gelidium amansii, Chondrus nipponicus, Ulva lactuca, Dictyopteris divaricata, Sargassum pallidum, and Desmarestia viridis. The results of statistical analysis revealed that Tuoji Island and Xiaoqin Island had relatively high biomass density. Nouth Changshan Island exhibited the highest species richness, followed by Miao Island and South Huangcheng Island. South Huangcheng Island had the highest diversity index, with Nouth Changshan Island and Tuoji Island ranking next, and also showed the highest evenness index among the surveyed sites. Cluster analysis results indicated significant differences in community structure between the five southern islands (South Changshan Island, North Changshan Island, Miao Island, Daheishan Island, Xiaoheishan Island) and the five northern islands (Tuoji Island, Daqin Island, Xiaoqin Island, South Huangcheng Island, North Huangcheng Island), mainly due to geographic variation. This study helps complement the gap in baseline information regarding seaweed beds in Shandong Province, thus providing essential data for the carbon sink evaluation and theoretical support for development of nearshore blue carbon sink of seaweed beds in Shandong Province.
The Miaodao Archipelago in Shandong Province are rich in seaweed resources and hold great potential for nearshore marine carbon sinks. However, fundamental data and research related to the seaweed beds in this region remain scarce, which astricts the calculation and evaluation to carbon sink of seaweed beds. Therefore, this study aimed to complement the gap in baseline information regarding seaweed beds in the Miaodao Archipelago. In this study, 10 residential islands of Miaodao archipelago in Shandong Province were selected and the distribution of seaweed fields in the subtidal zone was investigated and sampled by scuba diving. Seaweed resource information in the seaweed beds, including the distribution and area of seaweed beds, species composition, biomass, dominant species, and community diversity, was identified and counted, and then combined with the environmental context, the community structure characteristics of the seaweed beds in the 10 islands were clustered. A total of 34 species of macroalgae were collected, belonging to 21 families and 25 genera. Among them were 18 species of red algae (11 families, 15 genera), 4 species of green algae (2 families, 2 genera), and 12 species of brown algae (8 families, 8 genera). The dominant macroalgal species in the region included Saccharina japonica, Undaria pinnatifida, Sargassum muticum, Gelidium amansii, Chondrus nipponicus, Ulva lactuca, Dictyopteris divaricata, Sargassum pallidum, and Desmarestia viridis. The results of statistical analysis revealed that Tuoji Island and Xiaoqin Island had relatively high biomass density. Nouth Changshan Island exhibited the highest species richness, followed by Miao Island and South Huangcheng Island. South Huangcheng Island had the highest diversity index, with Nouth Changshan Island and Tuoji Island ranking next, and also showed the highest evenness index among the surveyed sites. Cluster analysis results indicated significant differences in community structure between the five southern islands (South Changshan Island, North Changshan Island, Miao Island, Daheishan Island, Xiaoheishan Island) and the five northern islands (Tuoji Island, Daqin Island, Xiaoqin Island, South Huangcheng Island, North Huangcheng Island), mainly due to geographic variation. This study helps complement the gap in baseline information regarding seaweed beds in Shandong Province, thus providing essential data for the carbon sink evaluation and theoretical support for development of nearshore blue carbon sink of seaweed beds in Shandong Province.
, Available online
Abstract:
Based on the observations of 3 wave buoys deployed in Liaodong Bay in winter of 2023−2025 and wave numerical model, this paper analyzes the characteristics of waves during freezing winter of Bohai Sea. According to the statistic results, the mean significant wave heights (mean significant wave periods) observed by 2 buoys in the center of Bohai Sea are about 1 m (4−5 s). Observations from the located buoy in Liaodong Bay indicates that waves are great affected by sea ice. When the buoy locates in a freezing region, the observed mean significant wave heights (mean significant periods) are 0.2 m (9 s), indicating a 54% reduction (98% increase) compared to the measurements without sea ice. The existence of sea ice may also lead the peak wave direction differ from the dominant wind direction. On the perspective of numeric modeling, the error of simulated wave heights can be reduced to 33% by adding ice-wave terms compared to the model without ice terms. By comparing two wind input terms (Komen and ST6), this paper finds that the simulations match the observations well and the error is comparable. Based on observations of buoys, the results rich the acknowledgements of people in the wave features in Bohai Sea during the freezing winter.
Based on the observations of 3 wave buoys deployed in Liaodong Bay in winter of 2023−2025 and wave numerical model, this paper analyzes the characteristics of waves during freezing winter of Bohai Sea. According to the statistic results, the mean significant wave heights (mean significant wave periods) observed by 2 buoys in the center of Bohai Sea are about 1 m (4−5 s). Observations from the located buoy in Liaodong Bay indicates that waves are great affected by sea ice. When the buoy locates in a freezing region, the observed mean significant wave heights (mean significant periods) are 0.2 m (9 s), indicating a 54% reduction (98% increase) compared to the measurements without sea ice. The existence of sea ice may also lead the peak wave direction differ from the dominant wind direction. On the perspective of numeric modeling, the error of simulated wave heights can be reduced to 33% by adding ice-wave terms compared to the model without ice terms. By comparing two wind input terms (Komen and ST6), this paper finds that the simulations match the observations well and the error is comparable. Based on observations of buoys, the results rich the acknowledgements of people in the wave features in Bohai Sea during the freezing winter.
, Available online
Abstract:
High-quality underwater optical images are crucial for tasks such as digital twins of seabed scenes, benthic habitat protection, seabed mineral resource detection, and understanding unknown underwater phenomena. However, due to factors such as complex aquatic environments and lighting conditions, underwater optical images suffer from degradation issues including color distortion, blurred details, and low contrast. Existing underwater image enhancement methods often focus on optimizing enhancement algorithms themselves, lacking systematic analytical mechanisms for tracing, classifying, and grading different types of degradation. To address this, considering the complexity and heterogeneity of underwater optical imaging environments, this paper proposes an image quality enhancement strategy that takes degradation types into account. First, a degradation-type-aware network is constructed to identify underwater hazy and blurred images, achieving an accuracy of 97%, and also demonstrating a high distinguishing capability for illumination degradation types. Second, for the identified underwater hazy images, an adaptive color correction method is designed based on the statistical distribution of color bias values in real underwater images, effectively restoring varying degrees of color attenuation. Finally, a block indexing strategy is introduced to obtain more precise background light estimates, further addressing the hazy blur issue in underwater images in conjunction with the underwater dark channel prior. Experimental results on various real underwater image datasets, including UIEB and RUIE, indicate that compared to representative underwater image enhancement methods, the PSNR and SSIM metrics are improved by 22.17% and 4.5%, respectively.
High-quality underwater optical images are crucial for tasks such as digital twins of seabed scenes, benthic habitat protection, seabed mineral resource detection, and understanding unknown underwater phenomena. However, due to factors such as complex aquatic environments and lighting conditions, underwater optical images suffer from degradation issues including color distortion, blurred details, and low contrast. Existing underwater image enhancement methods often focus on optimizing enhancement algorithms themselves, lacking systematic analytical mechanisms for tracing, classifying, and grading different types of degradation. To address this, considering the complexity and heterogeneity of underwater optical imaging environments, this paper proposes an image quality enhancement strategy that takes degradation types into account. First, a degradation-type-aware network is constructed to identify underwater hazy and blurred images, achieving an accuracy of 97%, and also demonstrating a high distinguishing capability for illumination degradation types. Second, for the identified underwater hazy images, an adaptive color correction method is designed based on the statistical distribution of color bias values in real underwater images, effectively restoring varying degrees of color attenuation. Finally, a block indexing strategy is introduced to obtain more precise background light estimates, further addressing the hazy blur issue in underwater images in conjunction with the underwater dark channel prior. Experimental results on various real underwater image datasets, including UIEB and RUIE, indicate that compared to representative underwater image enhancement methods, the PSNR and SSIM metrics are improved by 22.17% and 4.5%, respectively.
, Available online
Abstract:
Taking the Caofeidian seagrass bed—the largest existing seagrass bed in China—as the research object, this study adopted a combined method of remote sensing interpretation, field investigation, and model analysis to carry out research on the quantitative zoning of density and the formation mechanism of spatial heterogeneity of the Caofeidian seagrass bed. Through the interpretation of high-resolution satellite remote sensing images and combined with on-site field verification, the quantitative data of three core zoning types under the spatial pattern of “dense in the north and sparse in the south” of the Caofeidian seagrass bed were obtained, namely the dense area (with an area of 7.31 km2, accounting for 18.34%), the moderately dense area (with an area of 10.36 km2, accounting for 26.00%), and the sparse area (with an area of 22.18 km2, accounting for 55.66%). On the whole, it shows the characteristics of patchy mosaic distribution. Based on 10 environmental data items (including illumination, ammonium, and sediment density) obtained from field investigations, an MLP-ANN (Multilayer Perceptron-Artificial Neural Network) model was used for analysis, and it was found that the internal friction angle of sediment (contribution: 18%), water temperature (contribution: 15%), and sediment phosphate (contribution: 15%) were the core driving factors affecting the density zoning of the seagrass bed, with a cumulative influence accounting for 48%. The research results indicated that the density zoning of the Caofeidian seagrass bed is formed by thejoint effect of natural dynamic factors and human activities: in the southern region, strong tidal currents cause sediment scouring, and superimposed on the impacts of engineering activities such as oilfield exploration and channel dredging, as well as land-based pollution, forming the degradation chain of “sediment disturbance - nutrient imbalance”; the northern region is far from these disturbance sources, and through ecological restoration, the sediment conditions have been optimized, thus providing support for the formation of the medium-to-high density seagrass bed areas. This study fills the gaps in the quantitative research on the density zoning of the Caofeidian seagrass bed and the research on its formation mechanism, and provides a scientific basis and technical paradigm for the scientific assessment and effective restoration of seagrass beds in the Bohai Bay.
Taking the Caofeidian seagrass bed—the largest existing seagrass bed in China—as the research object, this study adopted a combined method of remote sensing interpretation, field investigation, and model analysis to carry out research on the quantitative zoning of density and the formation mechanism of spatial heterogeneity of the Caofeidian seagrass bed. Through the interpretation of high-resolution satellite remote sensing images and combined with on-site field verification, the quantitative data of three core zoning types under the spatial pattern of “dense in the north and sparse in the south” of the Caofeidian seagrass bed were obtained, namely the dense area (with an area of 7.31 km2, accounting for 18.34%), the moderately dense area (with an area of 10.36 km2, accounting for 26.00%), and the sparse area (with an area of 22.18 km2, accounting for 55.66%). On the whole, it shows the characteristics of patchy mosaic distribution. Based on 10 environmental data items (including illumination, ammonium, and sediment density) obtained from field investigations, an MLP-ANN (Multilayer Perceptron-Artificial Neural Network) model was used for analysis, and it was found that the internal friction angle of sediment (contribution: 18%), water temperature (contribution: 15%), and sediment phosphate (contribution: 15%) were the core driving factors affecting the density zoning of the seagrass bed, with a cumulative influence accounting for 48%. The research results indicated that the density zoning of the Caofeidian seagrass bed is formed by thejoint effect of natural dynamic factors and human activities: in the southern region, strong tidal currents cause sediment scouring, and superimposed on the impacts of engineering activities such as oilfield exploration and channel dredging, as well as land-based pollution, forming the degradation chain of “sediment disturbance - nutrient imbalance”; the northern region is far from these disturbance sources, and through ecological restoration, the sediment conditions have been optimized, thus providing support for the formation of the medium-to-high density seagrass bed areas. This study fills the gaps in the quantitative research on the density zoning of the Caofeidian seagrass bed and the research on its formation mechanism, and provides a scientific basis and technical paradigm for the scientific assessment and effective restoration of seagrass beds in the Bohai Bay.
, Available online
Abstract:
To investigate the differences in wave attenuation characteristics among rigid, flexible, and rigid-flexible composite vegetation under regular waves, a series of physical model tests were conducted in a laboratory flume. The wave attenuation effects of these three vegetation types were quantitatively analyzed, and the relationships between the drag coefficient (CD) and Reynolds number (Re), Keulegan–Carpenter number (KC), and Ursell number (Ur)—were determined. Results show that all three configurations induce a progressive along-flume reduction in wave height. Increasing incident wave period or vegetation submergence ratio consistently weakens wave dissipation for all vegetation types. The response to wave height differs by configuration: dissipation by rigid vegetation increases markedly and continuously with wave height, whereas flexible vegetation exhibits a nonlinear behavior, strengthening at first and then weakening as wave height further increases. The rigid–flexible combined configuration integrates these advantages and also shows enhanced dissipation with increasing wave height. Moreover, CD for the three vegetation types can be represented using a unified theoretical expression; the primary distinction among configurations is the value of the influence factor γ, which accounts for the effect of vegetation swaying on wave-height attenuation. Statistically significant dependencies of CD on Re, KC, and Ur are observed and can be parameterized by a unified empirical formulation. These results provide a theoretical basis and design reference for optimizing vegetation configurations in coastal ecological protection and restoration engineering.
To investigate the differences in wave attenuation characteristics among rigid, flexible, and rigid-flexible composite vegetation under regular waves, a series of physical model tests were conducted in a laboratory flume. The wave attenuation effects of these three vegetation types were quantitatively analyzed, and the relationships between the drag coefficient (CD) and Reynolds number (Re), Keulegan–Carpenter number (KC), and Ursell number (Ur)—were determined. Results show that all three configurations induce a progressive along-flume reduction in wave height. Increasing incident wave period or vegetation submergence ratio consistently weakens wave dissipation for all vegetation types. The response to wave height differs by configuration: dissipation by rigid vegetation increases markedly and continuously with wave height, whereas flexible vegetation exhibits a nonlinear behavior, strengthening at first and then weakening as wave height further increases. The rigid–flexible combined configuration integrates these advantages and also shows enhanced dissipation with increasing wave height. Moreover, CD for the three vegetation types can be represented using a unified theoretical expression; the primary distinction among configurations is the value of the influence factor γ, which accounts for the effect of vegetation swaying on wave-height attenuation. Statistically significant dependencies of CD on Re, KC, and Ur are observed and can be parameterized by a unified empirical formulation. These results provide a theoretical basis and design reference for optimizing vegetation configurations in coastal ecological protection and restoration engineering.
, Available online
Abstract:
Infragravity waves (with periods of 25−250 s) are critical components of nearshore hydrodynamic processes and have significant influence on coastal geomorphological evolution and engineering safety. Based on the conservation equations of mass, momentum, and energy, this paper systematically reviews the latest research progress on the generation mechanisms and evolution characteristics of infragravity waves. Regarding generation mechanisms, the review elaborates on four primary mechanisms: bound long waves, moving breakpoint forcing, bore merging, and wind gusts. Particular attention is given to the theoretical development from the classical equilibrium solution to non-equilibrium solutions for bound long waves, along with the recently proposed unified Green's function approach. In terms of propagation and evolution, the phase variation and energy transfer, nonlinear shoaling, nearshore dissipation, and shoreline reflection of infragravity waves on sloping beaches are introduced. Then, the amplification of infragravity waves over offshore raised topographies and coral reefs is also examined. The article further points out the inherent randomness present during the evolution of infragravity waves. Finally, future research directions are outlined, providing a theoretical reference for further study and application in terms of infragravity waves.
Infragravity waves (with periods of 25−250 s) are critical components of nearshore hydrodynamic processes and have significant influence on coastal geomorphological evolution and engineering safety. Based on the conservation equations of mass, momentum, and energy, this paper systematically reviews the latest research progress on the generation mechanisms and evolution characteristics of infragravity waves. Regarding generation mechanisms, the review elaborates on four primary mechanisms: bound long waves, moving breakpoint forcing, bore merging, and wind gusts. Particular attention is given to the theoretical development from the classical equilibrium solution to non-equilibrium solutions for bound long waves, along with the recently proposed unified Green's function approach. In terms of propagation and evolution, the phase variation and energy transfer, nonlinear shoaling, nearshore dissipation, and shoreline reflection of infragravity waves on sloping beaches are introduced. Then, the amplification of infragravity waves over offshore raised topographies and coral reefs is also examined. The article further points out the inherent randomness present during the evolution of infragravity waves. Finally, future research directions are outlined, providing a theoretical reference for further study and application in terms of infragravity waves.
, Available online
Abstract:
Toxic algal species pose significant threats to ecological environmental safety and human health. Azadinium dexteroporum, one of the main producers of azaspiracid toxins, remains poorly studied in China, and its distribution in Chinese coastal waters is still unclear. In this study, environmental DNA (eDNA) methods were used to obtain occurrence records of A. dexteroporum in Chinese coastal areas. Using the 2050s and 2100s as future projection periods, the Maximum Entropy (MaxEnt)model was applied to simulate the potential suitable habitats of this species under current and three future climate scenarios (SSP126, SSP245, and SSP585). The results indicated that nitrate concentration, silicate concentration, and sea surface temperature were the primary environmental factors influencing the distribution of A. dexteroporum. Under current conditions, the suitable habitat area was estimated to be 63.71 × 104 km2, mainly concentrated in the northern South China Sea. With climate change, the potential suitable area of A. dexteroporum is projected to shrink, decreasing to 5.58×104 km2～32.21×104 km2 by the 2100s. The spatial distribution pattern of suitable habitats shows an overall “southward contraction and northward expansion” trend: the extensive suitable areas in the South China Sea are expected to disappear, while new suitable areas may emerge in the Yellow and Bohai Seas. The centroid of suitable habitats is projected to shift up to 1,439 km, migrating from the northern South China Sea to north of the Yangtze River estuary. These findings provide important scientific insights for the ecological risk monitoring, forecasting, and management of harmful dinoflagellates.
Toxic algal species pose significant threats to ecological environmental safety and human health. Azadinium dexteroporum, one of the main producers of azaspiracid toxins, remains poorly studied in China, and its distribution in Chinese coastal waters is still unclear. In this study, environmental DNA (eDNA) methods were used to obtain occurrence records of A. dexteroporum in Chinese coastal areas. Using the 2050s and 2100s as future projection periods, the Maximum Entropy (MaxEnt)model was applied to simulate the potential suitable habitats of this species under current and three future climate scenarios (SSP126, SSP245, and SSP585). The results indicated that nitrate concentration, silicate concentration, and sea surface temperature were the primary environmental factors influencing the distribution of A. dexteroporum. Under current conditions, the suitable habitat area was estimated to be 63.71 × 104 km2, mainly concentrated in the northern South China Sea. With climate change, the potential suitable area of A. dexteroporum is projected to shrink, decreasing to 5.58×104 km2～32.21×104 km2 by the 2100s. The spatial distribution pattern of suitable habitats shows an overall “southward contraction and northward expansion” trend: the extensive suitable areas in the South China Sea are expected to disappear, while new suitable areas may emerge in the Yellow and Bohai Seas. The centroid of suitable habitats is projected to shift up to 1,439 km, migrating from the northern South China Sea to north of the Yangtze River estuary. These findings provide important scientific insights for the ecological risk monitoring, forecasting, and management of harmful dinoflagellates.
, 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.
Email alert
RSS