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doi: 10.12284/hyxb20260000
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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2026, 48(1): 1-29.
doi: 10.12284/hyxb2026008
Abstract:
China’s marine waters support abundant sea cucumber resources, with 138 species recorded across 7 orders, 16 families and 61 genera, including 39 species of major nutritional and economic value. These species are widely distributed across tropical, subtropical, and temperate waters, where they play essential roles in maintaining benthic ecological processes, regulating sediment structure, and supporting the development of marine ranching systems. At present, research on sea cucumbers in China has largely focused on aquaculture techniques and the bioactive properties of functional compounds, whereas fundamental studies on taxonomy and systematics remain comparatively limited. Since the establishment of the sea cucumber classification system in the 19th century, taxonomic methodologies have undergone a profound shift from traditional morphology-based approaches to modern molecular systematics. Traditional taxonomy relies primarily on external morphology and ossicle characteristics, with as many as 25 recognized ossicle types. However, the complexity of ossicle structures, the pronounced morphological polymorphism, and the high interspecific similarity and substantial intraspecific variation collectively hinder precise identification of closely related taxa and individuals at different life-history stages when using morphology alone.In recent years, the widespread application of molecular barcoding techniques such as COI and 16S rRNA, together with the rapid development of mitogenomic and whole-genome phylogenetic approaches, has significantly improved the accuracy of species identification and phylogenetic reconstruction. Despite these advances, several challenges persist, including insufficient deep-sea and South China Sea sampling, incomplete specimen coverage, limited molecular datasets, and inconsistent identification standards. Future research should strengthen systematic sampling and long-term monitoring in key marine regions, establish an integrative taxonomic framework combining traditional morphological traits, ossicle microstructure, and multi-gene molecular data, and promote the adoption of environmental DNA (eDNA) non-invasive sampling and AI-assisted digital imaging platforms. The establishment of standardized genetic and morphological databases, together with a national DNA barcode library, will provide essential technical support for rapid species identification and sustainable resource management. This study comprehensively reviews the species diversity patterns and taxonomic progress of Chinese sea cucumbers, identifies the current challenges in holothurian taxonomy, and proposes future directions toward a robust classification framework that underpins biodiversity conservation, ecological restoration, and the sustainable utilization of sea cucumber resources.
China’s marine waters support abundant sea cucumber resources, with 138 species recorded across 7 orders, 16 families and 61 genera, including 39 species of major nutritional and economic value. These species are widely distributed across tropical, subtropical, and temperate waters, where they play essential roles in maintaining benthic ecological processes, regulating sediment structure, and supporting the development of marine ranching systems. At present, research on sea cucumbers in China has largely focused on aquaculture techniques and the bioactive properties of functional compounds, whereas fundamental studies on taxonomy and systematics remain comparatively limited. Since the establishment of the sea cucumber classification system in the 19th century, taxonomic methodologies have undergone a profound shift from traditional morphology-based approaches to modern molecular systematics. Traditional taxonomy relies primarily on external morphology and ossicle characteristics, with as many as 25 recognized ossicle types. However, the complexity of ossicle structures, the pronounced morphological polymorphism, and the high interspecific similarity and substantial intraspecific variation collectively hinder precise identification of closely related taxa and individuals at different life-history stages when using morphology alone.In recent years, the widespread application of molecular barcoding techniques such as COI and 16S rRNA, together with the rapid development of mitogenomic and whole-genome phylogenetic approaches, has significantly improved the accuracy of species identification and phylogenetic reconstruction. Despite these advances, several challenges persist, including insufficient deep-sea and South China Sea sampling, incomplete specimen coverage, limited molecular datasets, and inconsistent identification standards. Future research should strengthen systematic sampling and long-term monitoring in key marine regions, establish an integrative taxonomic framework combining traditional morphological traits, ossicle microstructure, and multi-gene molecular data, and promote the adoption of environmental DNA (eDNA) non-invasive sampling and AI-assisted digital imaging platforms. The establishment of standardized genetic and morphological databases, together with a national DNA barcode library, will provide essential technical support for rapid species identification and sustainable resource management. This study comprehensively reviews the species diversity patterns and taxonomic progress of Chinese sea cucumbers, identifies the current challenges in holothurian taxonomy, and proposes future directions toward a robust classification framework that underpins biodiversity conservation, ecological restoration, and the sustainable utilization of sea cucumber resources.
2026, 48(1): 42-55.
doi: 10.12284/hyxb2026006
Abstract:
In this study, two fibroblast growth factor (FGF) genes, named as PdFGF1 and PdFGF17, were identified and cloned from the coral Pocillopora damicornis. Sequence analysis showed that PdFGF1 and PdFGF17 encode 195 and 149 amino acids, respectively. Both contain a signal peptide and a typical FGF domain, with characteristic β-sheets and η-loops in their topological structures. The FGF family in higher animals can be divided into seven subfamilies (FGF1, FGF4, FGF7, FGF8, FGF9, FGF11, and FGF19). Multiple sequence alignment and phylogenetic analysis revealed that PdFGF1 belongs to the FGF1 subfamily, sharing 30.15% sequence identity with HsFGF1 (Homo sapiens), whereas PdFGF17 clusters with the FGF8 subfamily, sharing 29.36% identity with HsFGF17. To further elucidate their biological roles, transcriptomic analysis was performed on P. damicornis under heat stress induced polyp bailout. The results showed that the expression levels of FGF family genes (PdFGF1, PdFGF2, PdFGF9, PdFGF17, PdFGF18, PdFGFR1, PdFGFR2, PdFGFR3 and PdFGFR4) were significantly upregulated during the detachment process. Moreover, the FGF signaling pathway was found to activate the downstream Ras/MAPK cascade, thereby regulating cytoskeletal remodeling and cell adhesion. Gene co-expression network analysis using Cytoscape further revealed significant co-expression relationships between FGF genes and extracellular matrix (ECM) degrading genes in the coenosarc tissue, including ADAMTSs, COL21A1, CTSZ, and P4HA. Collectively, these findings suggest that heat stress activates the FGF signaling pathway in P. damicornis, promoting ECM degradation and ultimately mediating coenosarc dissociation and polyp bailout.
In this study, two fibroblast growth factor (FGF) genes, named as PdFGF1 and PdFGF17, were identified and cloned from the coral Pocillopora damicornis. Sequence analysis showed that PdFGF1 and PdFGF17 encode 195 and 149 amino acids, respectively. Both contain a signal peptide and a typical FGF domain, with characteristic β-sheets and η-loops in their topological structures. The FGF family in higher animals can be divided into seven subfamilies (FGF1, FGF4, FGF7, FGF8, FGF9, FGF11, and FGF19). Multiple sequence alignment and phylogenetic analysis revealed that PdFGF1 belongs to the FGF1 subfamily, sharing 30.15% sequence identity with HsFGF1 (Homo sapiens), whereas PdFGF17 clusters with the FGF8 subfamily, sharing 29.36% identity with HsFGF17. To further elucidate their biological roles, transcriptomic analysis was performed on P. damicornis under heat stress induced polyp bailout. The results showed that the expression levels of FGF family genes (PdFGF1, PdFGF2, PdFGF9, PdFGF17, PdFGF18, PdFGFR1, PdFGFR2, PdFGFR3 and PdFGFR4) were significantly upregulated during the detachment process. Moreover, the FGF signaling pathway was found to activate the downstream Ras/MAPK cascade, thereby regulating cytoskeletal remodeling and cell adhesion. Gene co-expression network analysis using Cytoscape further revealed significant co-expression relationships between FGF genes and extracellular matrix (ECM) degrading genes in the coenosarc tissue, including ADAMTSs, COL21A1, CTSZ, and P4HA. Collectively, these findings suggest that heat stress activates the FGF signaling pathway in P. damicornis, promoting ECM degradation and ultimately mediating coenosarc dissociation and polyp bailout.
2026, 48(1): 56-63.
doi: 10.12284/hyxb2026010
Abstract:
In order to study the biological characteristics of Rhopilema esculentum and its environmental influencing factors, this study analyzed the biological characteristics of R.esculentum in different years according to the monitoring data of R. esculentum resources in Shengsi sea area of Hangzhou Bay from June to July 2022 to 2024, and explored the relationship between the umbrella diameter, body weight and environmental influencing factors of R. esculentum by GAM model. The results showed that there were significant differences between umbrella diameter and body weight of R.esculentum before the special fishing permits during the summer fishing moratorium, and the growth rate of R. esculentum body weight showed different growth trends at different growth stages. The results of the GAM showed that umbrella diameter and body weight of R. esculentum increased gradually with the increase of sea surface temperature from 21.18℃ to 26.81℃. Sea surface salinity has a significant effect on the growth of R. esculentum umbrella diameter. In the salinity range of 9.3−25.2, the umbrella diameter of R. esculentum increases, and the optimum salinity is 17.7−22.7. In the interaction between sea surface temperature and salinity, the high value area of umbrella diameter and the middle value area of body weight of R. esculentum are in the range of sea surface temperature 24−26.3℃ and sea surface salinity 15−22. There were significant differences in umbrella diameter and body weight among years after the special fishing permits during the summer fishing moratorium. Comprehensive analysis showed that the growth of umbrella diameter and body weight of R. esculentum was affected by sea surface temperature and salinity, and the initial fishing time could be determined based on the level of sea surface temperature.
In order to study the biological characteristics of Rhopilema esculentum and its environmental influencing factors, this study analyzed the biological characteristics of R.esculentum in different years according to the monitoring data of R. esculentum resources in Shengsi sea area of Hangzhou Bay from June to July 2022 to 2024, and explored the relationship between the umbrella diameter, body weight and environmental influencing factors of R. esculentum by GAM model. The results showed that there were significant differences between umbrella diameter and body weight of R.esculentum before the special fishing permits during the summer fishing moratorium, and the growth rate of R. esculentum body weight showed different growth trends at different growth stages. The results of the GAM showed that umbrella diameter and body weight of R. esculentum increased gradually with the increase of sea surface temperature from 21.18℃ to 26.81℃. Sea surface salinity has a significant effect on the growth of R. esculentum umbrella diameter. In the salinity range of 9.3−25.2, the umbrella diameter of R. esculentum increases, and the optimum salinity is 17.7−22.7. In the interaction between sea surface temperature and salinity, the high value area of umbrella diameter and the middle value area of body weight of R. esculentum are in the range of sea surface temperature 24−26.3℃ and sea surface salinity 15−22. There were significant differences in umbrella diameter and body weight among years after the special fishing permits during the summer fishing moratorium. Comprehensive analysis showed that the growth of umbrella diameter and body weight of R. esculentum was affected by sea surface temperature and salinity, and the initial fishing time could be determined based on the level of sea surface temperature.
2026, 48(1): 64-82.
doi: 10.12284/hyxb2026016
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.
2026, 48(1): 83-96.
doi: 10.12284/hyxb2026018
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. A 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. A 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.
2026, 48(1): 97-108.
doi: 10.12284/hyxb2026002
Abstract:
Species of the family Maldanidae are widely distributed across various marine environments, ranging from shallow to deep-sea habitats. However, due to the fragility of their bodies during collection, obtaining intact specimens is often uneasy, and morphological research is difficult to conduct fully. As a result, there are differing viewpoints and ongoing debates among researchers regarding their taxonomic classification. To clarify the evolutionary relationships within Maldanidae, this study assembled and analyzed the complete mitochondrial genome (mitogenome) of Praxillella sp. using second-generation genome sequencing data. The mitogenome of Praxillella sp. is15539 bp in length, with a base composition of A (33.7%), T (32.6%), G (13.6%), and C (20%), showing a pronounced AT bias. Similar to most metazoans, the genome contains 13 protein-coding genes (PCGs), 22 tRNA genes (including a duplicated tRNA-M), two rRNA genes, and a control region (CR). The codon usage is mainly driven by natural selection. The topological structures of the ML tree and the Bayesian tree constructed based on 13 PCGs are almost all consistent, but the position of P. praetermissa within the subfamily Euclymeninae being uncertain. Phylogeny based on the 13 PCGs overall supports the monophyly of Maldaninae, in contrast, no monophyletic clade is formed within Euclymeninae, being paraphyletic with Nicomachinae, Among the 14 analyzed Maldanid species, four types of gene order are identified, three of which involve changes in tRNA arrangements, driven by tandem duplication and random loss mechanisms. The results offer novel insights into in clarification of taxonomy and phylogenetic relationships of Praxillella sp. in Maldanidae.
Species of the family Maldanidae are widely distributed across various marine environments, ranging from shallow to deep-sea habitats. However, due to the fragility of their bodies during collection, obtaining intact specimens is often uneasy, and morphological research is difficult to conduct fully. As a result, there are differing viewpoints and ongoing debates among researchers regarding their taxonomic classification. To clarify the evolutionary relationships within Maldanidae, this study assembled and analyzed the complete mitochondrial genome (mitogenome) of Praxillella sp. using second-generation genome sequencing data. The mitogenome of Praxillella sp. is
2026, 48(1): 109-123.
doi: 10.12284/hyxb2026020
Abstract:
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 (Ma). 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 (Ma). 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.
2026, 48(1): 124-136.
doi: 10.12284/hyxb2026022
Abstract:
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.
2026, 48(1): 30-41.
doi: 10.12284/hyxb2026004
Abstract:
Gross Oxygen production (GOP) in the surface ocean is a key indicator for evaluating the intensity of phytoplankton photosynthesis and the efficiency of marine biological carbon sequestration. However, photosynthesis and respiration occur simultaneously. It is very difficult to distinguish the total photosynthetic O2 production from respiration O2 consumption. Therefore, in situ measurement of marine GOP is extremely challenging. The triple oxygen isotope anomaly (17Δ) of dissolved oxygen does not change with respiration, providing a new isotopic indicator for evaluating marine GOP. Due to the extremely low natural abundance of 17O and its susceptibility to mass interference from N2, high precision measurement for triple oxygen isotopes (δ18O, 17Δ) of O2 is very difficult. In this study, we developed a high-vacuum pretreatment system and a gas chromatographic purification line. We successfully separated N2 from O2 and Ar for dissolved gases. By precisely controlling the temperature and collection time, we ensured 100% collection of O2 and avoided oxygen isotopic fractionation from purification. Based on this method, the observed long-term external precision of the air standard was ±2.6 per meg for 17Δ. Then, we analyzed the triple oxygen isotopic compositions of 5 dissolved gas samples collected in Prydz Bay, Southern Ocean, in January 2021. The mean 17Δ value of dissolved oxygen in the mixed layer was 66 per meg, corresponding to an average GOP of 181 mmol O2 m−2 day−1. Our observation is consistent with the relatively low GOP of the high-latitude Southern Ocean during summer. The high-precision analytical method for triple oxygen isotopes of O2 in this study demonstrates great potential for applications in marine GOP research and also provides valuable support for atmospheric and ice core trapped gas studies.
Gross Oxygen production (GOP) in the surface ocean is a key indicator for evaluating the intensity of phytoplankton photosynthesis and the efficiency of marine biological carbon sequestration. However, photosynthesis and respiration occur simultaneously. It is very difficult to distinguish the total photosynthetic O2 production from respiration O2 consumption. Therefore, in situ measurement of marine GOP is extremely challenging. The triple oxygen isotope anomaly (17Δ) of dissolved oxygen does not change with respiration, providing a new isotopic indicator for evaluating marine GOP. Due to the extremely low natural abundance of 17O and its susceptibility to mass interference from N2, high precision measurement for triple oxygen isotopes (δ18O, 17Δ) of O2 is very difficult. In this study, we developed a high-vacuum pretreatment system and a gas chromatographic purification line. We successfully separated N2 from O2 and Ar for dissolved gases. By precisely controlling the temperature and collection time, we ensured 100% collection of O2 and avoided oxygen isotopic fractionation from purification. Based on this method, the observed long-term external precision of the air standard was ±2.6 per meg for 17Δ. Then, we analyzed the triple oxygen isotopic compositions of 5 dissolved gas samples collected in Prydz Bay, Southern Ocean, in January 2021. The mean 17Δ value of dissolved oxygen in the mixed layer was 66 per meg, corresponding to an average GOP of 181 mmol O2 m−2 day−1. Our observation is consistent with the relatively low GOP of the high-latitude Southern Ocean during summer. The high-precision analytical method for triple oxygen isotopes of O2 in this study demonstrates great potential for applications in marine GOP research and also provides valuable support for atmospheric and ice core trapped gas studies.
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