10 October 2026, Volume 48 Issue 5

    

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• Research Papers
• Mechanisms of the decadal sea level variation of the Arctic Ocean

  Chen Meixiang, Wang Tao, Jin Ying, Hu Jintang

  2026, 48(5): 1-10. https://doi.org/10.13984/j.cnki.cn37-1141.2026.05.001

  Abstract ( ) PDF ( )

  Sea level variation of the Arctic Ocean is a critical indicator of the Arctic climate change. Based on the ORAS5 reanalysis data, the characteristics and primary mechanisms of the decadal sea level variation in the Arctic Ocean from 1979 to 2018 were investigated. Results indicated a close relationship between the sea level variation in the Arctic Ocean and the Arctic Oscillation (AO). AO-related wind anomalies led to the convergence and divergence of the surface freshwater in deep basins, causing sea level changes in shelf areas and influencing water exchange between the Arctic Ocean and external oceans, driving the mean sea level variations of the Arctic Ocean through mass changes. The convergence and divergence of surface freshwater resulted in regional sea level variations, with steric changes, especially halosteric changes, dominating in the deep basins. The AO phase shifted from positive to negative in 1995, causing a trend shift in the sea level of the Arctic Ocean. From 1979 to 2018, waters of the upper 200 meters in the Canadian and Eurasian basins exhibited significant freshening after 2000, leading to a marked rise in sea levels in these basins. Warming occurred in the upper 1000 meters of both basins after 2004, yet due to the small thermal expansion coefficient of the cold Arctic waters, contributions of the thermosteric changes to sea level rise were insignificant. The dipole anomaly (DA) also influenced the spatial distribution of sea level variations in the deep basins.
• Analysis on the source and accumulation of salt in the submerged brine layer of muddy tidal flat under tidal action

  Chen Lifan, Zhang Yufeng, Guo Xiujun, Guo Daoran, Lei Bingxiao

  2026, 48(5): 11-21. https://doi.org/10.13984/j.cnki.cn37-1141.2026.05.002

  Abstract ( ) PDF ( )

  The intensive exploitation of shallow underground brine in Laizhou Bay has caused widespread attention to environmental issues such as seawater intrusion and land salinization in recent years. Understanding the source and accumulation process of salt in intertidal zone phreatic brine in this area is of great significance for understanding the formation mechanism of shallow coastal underground brine resources, planning the exploitation of brine resources and solving the environmental problems associated with brine. In this study, we used resistivity tomography technology combined with pore water salinity measurement to obtain the salinity change rate profiles of the tidal flats at different tidal periods. Combined with the salt flux calculation results, we analyzed the salt composition of phreatic brine during tidal processes and established a salt transport accumulation model for the phreatic brine layer on the southern coast of Laizhou bay under tidal action. The results showed that: 1) Under the influence of tidal cycle, the salinity of intertidal zone phreatic brine mainly came from the salt accumulated by evaporation on the surface and the deep high salinity water body, and the supply of deep high salinity water body was the main source of the salinity of phreatic brine. In areas with thicker weak permeable layers and deeper depths of confined brine, the recharge of deep salt to phreatic brine was mainly achieved through the release of the weak permeable layer itself, rather than the overflow of confined brine. 2) The resistivity mapping method was an effective method for real-time monitoring of sediment salinity changes during tidal processes. The monitoring results could be directly converted to obtain the changes in sediment salinity at different times during tidal processes. By combining the measured pore water salinity, the estimation of cross-sectional salt flux could be achieved, and the analysis of salt transport and accumulation processes in coastal groundwater systems could be achieved.
• Active-passive fusion of shallow water bathymetry inversion and dynamic monitoring in South China Sea reefs

  Li Xueyin, Hu Lianbo, Chen Shuguo, Duan Zhigang

  2026, 48(5): 22-30. https://doi.org/10.13984/j.cnki.cn37-1141.2026.05.003

  Abstract ( ) PDF ( )

  The shallow bathymetry distribution of the South China Sea reefs is of great significance to guarantee the safety of marine transportation and shipping, the implementation of coastal and marine construction, and the maintenance and protection of the rights and interests in the South China Sea. However, due to technical and practical constraints, there is a large gap in the data of shallow bathymetry in the South China Sea islands and reefs. In this paper, based on the multilayer perceptron neural network (MLP), we used Landsat-8 optical satellite and ICESat-2 LiDAR satellite data to establish the bathymetric inversion model (MLP-SWDIM) for shallow sea bathymetry in the South China Sea islands and reefs. Verified by ICESat-2 bathymetry data, the MLP-SWDIM model was applied to the test set, and the root mean square error (RMSE) of the inversion results was about 1.5 m, and the mean relative difference (MRD) was about 8.2%. Applied to the Landsat-8 optical images of other imaging dates in the training area, the MRD was 5.3%～13.7% in the water depth range of 0～40 m, and the RMSE was 0.8～1.4 m. Application of multiple island areas outside the training area, in the range of 0～35 m water depth, the MRD was 7.5%～11.6%, and the RMSE was between 1.0～1.4 m, showing high inversion accuracy and robustness. Then, the MLP-SWDIM model and the long time series Landsat-8 data were used to dynamically monitor the shallow bathymetry in some reefs in the South China Sea.
• Analysis on the dynamic evolution trend of the Luanhekou sand-bar type island in recent 47 years

  Zhen Yanlong, Qie Xin, Han Xiaoqing

  2026, 48(5): 31-39. https://doi.org/10.13984/j.cnki.cn37-1141.2026.05.004

  Abstract ( ) PDF ( )

  In order to explore the dynamic evolution trend of sand bar island in the Luanhe River estuary area of Hebei Province and its influencing factors, this study extracted the information of the bar-type island based on the method of human-computer interactive interpretation. Five phase images from 1975 to 2022 were used as data sources, combined with topographic maps and other data. Correlation analysis was carried out using shape index, dynamic attitude model and barycentric migration model. The results showed that: 1) the number of islands increased first and then decreased gradually in recent 47 years. The coastline length and area of the islands were in constant change and both showed a sharp decrease trend. The coastline length decreased by 71.15 km (85.16%), and the island area decreased by 987.27 ha (90.69%) in total, and the dynamic change rates of the islands from 2012 to 2022 were the highest, 7.13% and 7.82% respectively. 2) During the study period, the direction of barycenter migration of different types of islands was completely opposite. From 1975 to 1989, the estuary sand bar island first shifted to the northeast, and then gradually shifted to the southwest. The overall shift of the center of gravity of the offshore sand bar island was 6.59 km to the northeast. 3) A series of large-scale human development and utilization activities in the Luanhe estuary area had led to prominent problems such as the natural environmental conditions, dynamic changes, and fragile ecosystem of the island. It is urgent to strengthen the protection of the island in Hebei province through measures such as island linkage and ecological restoration.
• Typhoon wind refine simulation and turbulence characteristics analysis——a case study during typhoon “Kompasu”

  Liu Tao, Huang Bigui, Xie Botao, Sun Hang, Wang Zhifeng, Jiang Dong

  2026, 48(5): 40-49. https://doi.org/10.13984/j.cnki.cn37-1141.2026.05.005

  Abstract ( ) PDF ( )

  In this paper, ERA5 wind data were used as the initial conditions of the WRF model, and different physical parameterization schemes were used to simulate typhoon “Kompasu”, No. 18 in 2021. By comparing with buoy data, Kessler microphysics and Tiedtke cumulus parameterization were ultimately selected, and adopt WRF_LES refinement of typhoon wind field simulation. Five characteristic points were selected to study and analyze energy spectral density of fluctuating wind speed, turbulence intensity, wind profile and maximum directional variation angle. The results indicated the energy spectrum of fluctuating wind speed in the U and V directions at a height of 10 m satisfies the -5/3 law. The consistency between turbulence intensity and wind speed showed well at a height of 10 m. The turbulence intensity was also highest at the maximum wind speed of a typhoon, with a maximum value of around 0.33. The maximum instantaneous wind speed occurred around 2000 m, and the maximum instantaneous wind speed reached 56.3 m/s. The maximum directional variation angle occurred at the moment of maximum typhoon wind speed, with a maximum value of 1.98 °.
• Studies on hydrodynamic characteristics of square artificial reef with diverter under different spacing

  Yu Dingyong, Zhao Junyi, Zhao Wei, Wang Ziyi

  2026, 48(5): 50-57. https://doi.org/10.13984/j.cnki.cn37-1141.2026.05.006

  Abstract ( ) PDF ( )

  In order to study the flow field effect of two artificial reefs with square baffles under two layout methods and different spacing, the angle of the baffle was set to 15°, and the flow velocity around the artificial reefs with longitudinal layout spacing of 1.0, 2.0, 4.0 L and transverse layout spacing of 1.0 L were measured with physical model methods. The hydrodynamic field of two reefs with 6 horizontal spacings (0.5 - 4.0 L) and 3 vertical spacings (1.0 - 4.0 L) was studied by means of numerical modeling. The influence of different spacings on the upwelling characteristics of reefs was analyzed. The results showed that the upwelling effect of the two reefs is better than that of the vertical ones. When the upwelling effect was optimal, the distance was 0.5 L horizontally and 3.0 L vertically.
• Studies on the flow and rheological property of fluidized solidified soil of dredged sediment

  Liu Shengbang, Wu Xiaoni, Yin Jifu, Chen Jinjian

  2026, 48(5): 58-67. https://doi.org/10.13984/j.cnki.cn37-1141.2026.05.007

  Abstract ( ) PDF ( )

  As the rich waste soil resource, dredged sediment from rivers and lakes holds an important reuse potential. This work focused on the issues of material properties in the design and construction of resourceful utilization of dredged sediment. The flow and rheological properties in the diffusion process of fluidized solidified soil prepared from dredged sediment were investigated through a series of orthogonal experiments. The effects of moisture content of dry basis, organic matter content, and stabilizer dosage on the flow value and rheological properties of fluidized solidified soil were examined. The results indicated that these three factors have a minimal impact on the density of the fluidized solidified soil. The flow value showed a linear relationship with these factors, which is positively correlated with the moisture and organic matter contents, and is negatively correlated with the stabilizer dosage. Based on these findings, a highly reliable linear prediction formula for the flow value was established. Moreover, by comparing the rheological curves of different fluidized solidified soils made from dredged sediment, it was found that there are two distinct stress-strain modes, which differ in the existence of a clear solid-liquid transition phase. Furthermore, a comparative analysis between the Bingham model and the Herschel-Bulkley model for simulating the rheological behavior of flowable solidified soil revealed that the Herschel-Bulkley model describes more accurately the rheological behavior. Based on the linear prediction equations of the three factors on the flow values, the reliable calculation equations between the corresponding rheological parameters and the flow values of these two rheological models were also proposed, and the relationships between the dry basis water content, organic matter content and curing agent dosing and the rheological parameters were further established. These research results provided a theoretical basis and technical support for the resourceful utilization of dredged sediment from rivers and lakes.
• Study of load shedding effect of porous plate based on numerical wave tanks

  Cheng Youliang, Wan Shengquan, Cao Shugang

  2026, 48(5): 68-76. https://doi.org/10.13984/j.cnki.cn37-1141.2026.05.008

  Abstract ( ) PDF ( )

  In order to study the load shedding performance of porous plate, a 2D numerical wave tank was constructed based on Stokes second-order wave theory and damping wave absorption theory. In the numerical wave tank, the influence of different wave absorption parameters on wave simulation results was discussed, and the wave absorption performance and load reduction effect of perforated plates under different porosity and tilt angles were studied. The results showed that the wave dissipation length, damping coefficient and empirical coefficient had an effect on the simulation results. In order to reduce the error, the wave dissipation length should be greater than 1.5 times the wavelength, the damping coefficient could be used as the linear damping coefficient, and the empirical coefficient should be less than 3. The lower the porosity was, the more significant the load reduction ability of the porous plate was. The strongest load reduction was achieved when the plate was placed vertically, and the maximum load reduction of the porous plate was achieved when the total length of the porous plate was eight times the wave height of the incident wave, and the maximum load reduction was achieved. When the total length of the porous plate was 8 times of the incident wave height, the maximum load reduction performance of the porous plate was achieved.
• Numerical simulation analysis of modal characteristics of mooring cables in deep-sea submerged tanks

  Li Chengxiao, Jiang Jitong

  2026, 48(5): 77-87. https://doi.org/10.13984/j.cnki.cn37-1141.2026.05.009

  Abstract ( ) PDF ( )

  Hydrodynamic analysis of deep-sea submerged silo systems is an important basic work for the design and deployment of submerged silos, as well as their operation and maintenance. The study of the vibration frequency characteristics of the mooring cable has good application value for assessing the deformation and strength of the submerged silo system. This paper established a numerical model of its mooring cable system and studied the modal characteristics of the mooring cable model. The study showed that by comparing the intrinsic frequency of mooring cables in different working conditions, it was found that the wet modal analysis was irreplaceable. The presence of seawater decreased the intrinsic frequency of the system, while the increase of tension and the decrease of the cable diameter both increased its intrinsic frequency. At the same time, in order to study whether the current force can cause vortex vibration phenomenon in the set environment, the two-dimensional model of the mooring cable was subjected to two-dimensional transient bypassing. The frequency domain curve of the lifting force converted by FFT was obtained to get the vortex vibration frequency of the surrounding flow field. It was found that there was a danger of vortex vibration of the mooring cable under the set operating environment after the comparison of the frequency and the analysis of the harmonic response.
• Experimental study on grouting escape of deep-sea crawler mining vehicle

  Chen Liming, Chen Xuguang, Liu Xixi, Jin Shuai, Zhang Xian

  2026, 48(5): 88-99. https://doi.org/10.13984/j.cnki.cn37-1141.2026.05.010

  Abstract ( ) PDF ( )

  The exploitation of deep-sea mineral resources has become an important choice for the sustainable development of global economy and a major strategic demand for China to build a maritime power. On the background of emergency self-rescue for crawler mining vehicle subsidence, this paper proposed the grouting escape method. The grouting model test system was developed, and the deep sea soft soil grouting test and caterpillar plate shear model test were carried out with simulated soil. The diffusion form and reinforcement law of cement grout in deep-sea soft soil were discussed. The results showed that the bearing capacity of deep-sea soft soil was changed after grouting, and the internal friction angle and cohesion were significantly increased, which effectively reduced the soil settlement. In deep-sea soft soil, grout diffusion distance was positively correlated with grout water-cement ratio and grouting pressure. After grouting, the seabed still had the typical characteristics of brittle soil in the process of caterpillar shear. Further analysis showed that the maximum tractive force of the grouted seabed was much greater than that of the ungrouted seabed, and the residual tractive force of the grouted seabed was also greater than that of the ungrouted seabed. The effect of grouting on emergency self-rescue of deep-sea mining vehicle subsidence was fully verified.
• Identification method of ocean tidal fluctuation electromagnetic based on deep learning

  Liu Lanjun, Qiang Jiachen, Chen Jialin, Li Ming, Wu Kunyu

  2026, 48(5): 100-109. https://doi.org/10.13984/j.cnki.cn37-1141.2026.05.011

  Abstract ( ) PDF ( )

  The tide is a periodic movement of seawater. The vertical direction shows tidal level rising and falling, the horizontal direction shows tidal current fluctuation. The electromagnetic signal generated by tide has obvious periodicity and wide frequency band, which can reflect the characteristics of tidal fluctuation. Electromagnetic detection of underwater targets requires synchronous observation of ocean current information. Local observation and synchronization difficulty exist in using current meter and other instruments. Numerical simulation, forward modeling and inversion methods need to establish accurate tidal current electromagnetic model. In this paper, a method of ocean tidal fluctuation electromagnetic identification based on time-frequency analysis and convolution neural network was proposed by using the electromagnetic field information generated by the tidal current fluctuation movement carried simultaneously in the ocean electromagnetic observation data. Conversion of one-dimensional electromagnetic time series signal into two-dimensional electromagnetic time-frequency image by time-frequency analysis method was made based on fast fourier transform and smoothed average periodogram. The electromagnetic time-frequency image data set was obtained by combining the fluctuation information of ocean tidal. A deep learning network based on convolutional neural network was designed for feature extraction and classification of electromagnetic time-frequency images. The deep learning network adopted 112×448 input size and 5-fold cross-validation method to train and evaluate the deep learning network. Based on the measured data of the South Yellow Sea, the test results showed that the proposed OTFEMI/TFA&CNN method had good recognition ability for ocean tidal fluctuations.
• Design wave height estimation based on improved two-source compound extreme value distribution

  Li Yanchun, Dong Sheng, Tao Shanshan, Jiao Chunshuo

  2026, 48(5): 110-119. https://doi.org/10.13984/j.cnki.cn37-1141.2026.05.012

  Abstract ( ) PDF ( )

  The rational calculation of design wave height is of great significance in the design of ocean engineering. On the basis of the traditional compound extreme value distribution, this paper considered the annual extreme value wave height during the non-typhoon periods or during the non-cold wave periods. Differences in the meteorological processes (typhoons or cold waves) from which the wave height extremes originated were into account. This paper established an improved two-source compound extreme value distribution model. The annual maximum method, the traditional compound extreme value distribution and the two-source compound extreme value distribution and the improved two-source compound extreme value distribution were used to calculate the reproduction values of the design wave heights in the Rizhao area, and the results of the different methods were compared. Compared with the traditional compound extreme value distribution, the improved two-source compound extreme value distribution made up for the defect that the lower limit of the traditional compound extreme value distribution was not zero. The non-storm surge was taken into account. Compared with the annual extreme value method, it distinguished the source of data. The improved two-source compound extreme value distribution model provided a new calculation method for the derivation of design wave height.
• Study on the optimization of drag coefficient in WAVEWATCH III wave model in the northwest Pacific Ocean

  Sun Zhaofeng, Wei Yongliang, Gao Zhiyi, Pang Denglian

  2026, 48(5): 120-129. https://doi.org/10.13984/j.cnki.cn37-1141.2026.05.013

  Abstract ( ) PDF ( )

  Sea surface drag coefficient is one of the key parameters in the wave numerical model, which has a significant impact on the accuracy of wind and wave simulation. The source of the surge is the wind and waves, so the accuracy of the surge depends on the accuracy of the wind and waves. Based on the ST6 source function scheme of the third generation wave numerical model WAVEWATCH III and the effective wave height data of Jason-3 satellite altimeter, we established the regional wave test model in the northwest Pacific Ocean, proposed the optimization formula of drag coefficient extended to the third side of wind speed, and analyzed the simulation results. The results showed that the optimization formula of drag coefficient produced an inflection point in the wind speed around 15 m/s, in which the constant term and the first order term of wind speed mainly affected the wave height simulation under low wind speed, and the second term and third order terms mainly affected the wave height simulation of wind and wave at high wind speed. In the whole study area, the effective wave height simulated by using the drag coefficient optimization formula had increased significantly compared with the previous results. In the surge area, the simulation results were also significantly improved, which showed that the optimization formula of drag coefficient proposed in this paper adjusted the accuracy of the wind wave, which provides a scientific reference for the optimization of the attenuation coefficient of wave breaking term in the future.
• Study on wave design parameters of Hongdao coastal engineering in Jiaozhou Bay

  Lin Xiaorong, Xie Qinghao, Tong Gaoqiang, Wang Yuanrong, Dong Sheng

  2026, 48(5): 130-136. https://doi.org/10.13984/j.cnki.cn37-1141.2026.05.014

  Abstract ( ) PDF ( )

  With the rapid development of economy, the coastal area of Hongdao in the north of Jiaozhou bay of Qingdao has become an important support for future urban development. Through the long-term annual extreme wind speed observation series of Tuandao meteorological station, the return wind speeds of Jiaozhou bay were estimated. The wave height calculation of the control points in the deep water area of Jiaozhou bay was carried out by using the wind wave calculation method recommended by the code. Wave calculation from deep water to shallow water was carried out using MIKE21 software, and the design parameters of wave height along the coast of Hongdao were obtained. The research results could provide a basis for the design of wind and wave protection and ecological construction projects along the coast of Hongdao.
• Research on wave design parameters in summer ice free region of Laptev Sea

  Xu Baike, Liao Zhenkun, Dong Sheng

  2026, 48(5): 137-146. https://doi.org/10.13984/j.cnki.cn37-1141.2026.05.015

  Abstract ( ) PDF ( )

  Laptev Sea is one of the marginal seas of the Arctic Ocean with potential for oil and gas resources. It also serves as a transit route for the Northeast Passage. With climate change, this region is experiencing new opportunities for summer oil and gas development and shipping. This study utilizes the ERA5 reanalysis dataset from the European Centre for Medium-Range Weather Forecasts (ECMWF) to collect sea ice concentration, significant wave height, and mean wave period data for the Laptev Sea from 1979 to 2022. Based on the assessment of ice conditions and ice zones in the Laptev Sea, wave element return values for ice-free areas during the summer were estimated using traditional annual extreme value distribution models, one-dimensional Poisson compound extreme value distribution models, and two-dimensional Poisson compound extreme value distribution models. The results indicated that the wave element return values estimated by the two-dimensional model were more suitable for practical sea conditions than traditional methods. The estimated joint return values of waves could provide a reference for the design of marine structures.
• Studies on the swimming vorticity of eel with particle image velocimetry technology

  Cao Yugeng, Liu Bilin, Kong Xianghong, Jia Chengnan, Zhang Ying, Huang Xiaoshuang

  2026, 48(5): 147-154. https://doi.org/10.13984/j.cnki.cn37-1141.2026.05.016

  Abstract ( ) PDF ( )

  In order to explore the transfer and change process of vorticity of Anguilla japonica in free swimming state, the particle image velocimetry (PIV) was used to analyze its vorticity change and growth rate during linear swimming at different speeds. The results showed that (1) the vortex generated by the eel swimming is transmitted from the head to the tail along the body, the swimming frequency is consistent with the shedding period of the vortex, and the positive and negative vorticity generated by the whole body gradually increases with time; (2) when the eel swims, only one vortex is gathered in the head and body parts, the two vortices turn in the opposite direction, and the vorticity gathered in the body is greater than that gathered in the head with a ratio of 4.17∶1 as the highest; (3) the growth rate of vorticity in the head of eel is the largest, which is followed by that in body and in tail (the smallest), and the rate can reach as high as 2.98∶1.76∶1. The head played an important role in the swimming process of eel. Our findings are helpful to understand the kinematics mechanism of eel-like swimming fish, and provided a researching direction towards the motion characteristics of bionic robotic fish.
• Effects of acute hypoxia reoxygenation stress on antioxidation and energy metabolism of the Chinese mitten crab

  Su Xianpeng, Zhang Yongan, Tian Lang, Huang Jinlu, Zhang Dan, Zhu Xuan

  2026, 48(5): 155-162. https://doi.org/10.13984/j.cnki.cn37-1141.2026.05.017

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  In order to study the effects of hypoxia reoxygenation stress on the antioxidant and energy metabolism of the Chinese mitten crab Eriocheir sinensis, crab was exposed to acute hypoxia of 1 mg/L and reoxygenation of 6 mg/L, and the effects of antioxidant-energy metabolizing enzymes were measured. At the same time, the muscle tissues were determined by metabonomics, and the significantly different metabolites were clustered and analyzed. The results showed that: 1) After hypoxia stress, the activities of SOD and CAT in hepatopancreas increased significantly, while the activity of T-AOC decreased significantly, and the content of MDA increased significantly (P<0.05). After reoxygenation, there was no significant difference between SOD and CAT activities, but T-AOC activity increased significantly after reoxygenation for 6 hours (P<0.05). 2) After 6 hours of stress, the activities of ACP and AKP decreased significantly (P<0.05), and both activities increased significantly after reoxygenation. 3) After hypoxia stress, the activity of PFK increased significantly (P<0.05). After reoxygenation, the activity of PK and PFK, and ATP content increased compared with that before stress. 4) After hypoxia stress, inositol phosphate metabolism, fructose and mannose metabolism and pentose phosphate pathway expression were significantly up-regulated. After reoxygenation, inositol phosphate metabolism, fructose and mannose metabolism expression were obviously up-regulated. The preliminary results showed that hypoxia/reoxygenation stress could cause oxidative stress to E. sinensis, and reduce the body's non-specific immune defense ability. In the process of coping with hypoxia stress, crab would strengthen anaerobic metabolism pathway and provide energy for the body to cope with hypoxia stress. It was suggested that the dissolved oxygen level of water body should be improved in the process of crab culture to ensure the normal feeding and growth of crab.
• Morphological difference analysis of Scapharca subcrenata in northern waters of China

  Zhou Hongyu, Yan Long, Kong Yefu, Li Jiandu, Hong Jingyan, Gao Dongkui, Guo Dong

  2026, 48(5): 163-169. https://doi.org/10.13984/j.cnki.cn37-1141.2026.05.018

  Abstract ( ) PDF ( )

  In this study, we conducted a comparative analysis of morphological difference among nine Scapharca subcrenata populations along China's northern coast (Panjin, Huludao, Tianjin, Rizhao, Weifang, Qinhuangdao, Huanghua, Qingdao and Yantai) with multivariate statistical methods. Key findings revealed that the Qingdao, Weifang and Huanghua populations exhibit a more rounded shell shape (higher shell height/length ratio); the Rizhao population shows the highest shell weight coefficient (35.687) among all populations; and the Yantai population displays the maximum shell width coefficient (0.284) but the minimum shell weight coefficient (28.568). Principal component analysis indicated that PC1 explains 62.75% of variance; PC2 explains 20.04% of the variance; and cumulative variance of the first two PCs reachs 82.79%. Discriminant analysis achieved an overall correct classification rate of 67.6% for the nine populations. Cluster analysis demonstrated that Bohai Sea populations (Panjin and Huludao) form one cluster; Tianjin, Qinhuangdao and Qingdao populations group together; Huanghua, Yantai and Weifang populations cluster; and Rizhao population shows the greatest divergence. These results confirmed a significant morphological differentiation among geographically distinct S. subcrenata populations, and validated the effectiveness of multivariate statistical approaches for population discrimination. The findings provided a scientific support for population identification and conservation of S. subcrenata germplasm resource.
• Genetic diversity and genetic structure of Culter alburnus populations inhabiting seven freshwater lakes of Jiangsu

  Yang Ziping, Li Daming, Liu Yanshan, Yang Jiaxin

  2026, 48(5): 170-178. https://doi.org/10.13984/j.cnki.cn37-1141.2026.05.019

  Abstract ( ) PDF ( )

  In this study, the genetic diversity and genetic structure of C. alburnus populations from seven freshwater lakes (Tai Lake, Ge Lake, Changdang Lake, Gaoyou Lake, Baima Lake, Hongze Lake and Luoma Lake) of Jiangsu Province were analyzed based on mitochondrial D-loop gene sequence. The results showed that the full length of D-loop gene was 934 - 936 bp, and the content of A+T was higher than that of G+C. In total, 42 distinct haplotypes were identified among 300 individuals of C. alburnus, and the average haplotype diversity (H_d) and nucleotide diversity (π) were 0.885±0.010 and 0.003 48±0.000 12, respectively. The genetic diversity of Gaoyou Lake population was the highest (H_d: 0.901±0.023, π: 0.003 41±0.000 30) while that of Luoma Lake population was the lowest (H_d: 0.470±0.089, π: 0.001 78±0.000 53) among seven populations. The Neighbor joining phylogenetic tree and haplotype network both revealed that the haplotypes were randomly distributed among seven populations and there was no geographic genetic structure. Analysis of molecular variance (AMOVA) suggested that most of the genetic variation occurred within the populations (84.15%), and only 19.55% of genetic variation occurred among the populations groups. Pairwise Fst showed that genetic differentiation among populations in the same river system was weak (P>0.05) while moderate to high genetic differentiation occurred among populations in different river systems (P<0.01). The neutral tests showed that the Tajima′s D and Fu′s F_s values of C. alburnus were significantly negative (P<0.05), and mismatch distribution curve showed an obvious single peak, which indicated that C. alburnus has experienced a population expansion in history. The research results showed that the genetic structure of seven lake populations was consistent with the distribution pattern of river system. The genetic diversity of C. alburnus from freshwater lakes was low, and it was urgent to take measures to restore the natural resources and genetic diversity of C. alburnus in Jiangsu Province.
• A novel Chlamydomonas sp. ICE-L photolyase with DNA lesion photorepairing activity

  An Meiling, Ding Zhen, Zhang Yongming, Liu Tingting, Miao Jinlai

  2026, 48(5): 179-186. https://doi.org/10.13984/j.cnki.cn37-1141.2026.05.020

  Abstract ( ) PDF ( )

  CPDs and 6-4PPs are UV-induced DNA lesions. DNA photolyase, a class of flavoproteins that utilize light energy, are capable of repairing DNA damages. DNA photolyase recognize and bind to DNA lesion CPDs or 6-4PPs, and accordingly, the photolyase are usually classified into CPD photolyase and (6-4)PP photolyase. The Antarctic microalga, Chlamydomonas sp. ICE-L, can thrive in extreme environments of the Antarctic. DNA photolyases are essential for the Antarctic microalga to survive athe intense UV radiation in Antarctica. In this study, a new photolyase of C. sp. ICE-L was preliminarily explored. Through PCR amplification and cloning, the photolyase gene sequence (CiPhr) from Antarctic ice algae C. sp. ICE-L was obtained, and its bioinformatic analysis showed that CiPhr belongs to photolyase enzyme. Real-time quantitative PCR showed that the transcription level of CiPhr increases under UVB (290-320 nm) and dark conditions. The expression vector loaded with CiPhr was transferred into repair-deficient E. coli strain to detect the in vivo activity of the photorefractive enzyme. It was found that the survival rate of the strain can be improved. The functional verification showed that CiPhr can repair CPDs. Our findings confirmed that CiPhr is a photolyase enzyme with DNA repairing activity.
• The performance of calcium hydroxide-coated nanoscale zero-valent iron in removing two common red-tide algae

  Ge Zhanyu, Fan Jiajia, Chen Xuegang

  2026, 48(5): 187-195. https://doi.org/10.13984/j.cnki.cn37-1141.2026.05.021

  Abstract ( ) PDF ( )

  Owing to eutrophication increase of water bodies and global climate change, harmful algal blooms (HABs) outbreak frequently in recent decades, impacting negatively aquatic ecosystems and water quality. In this study, calcium hydroxide-coated nanoscale zero-valent iron (nZVI@Ca(OH)₂, NCa) was successfully prepared and used for the removal of two common algal species, Amphidinium carterae and Heterosigma akashiwo. The results showed that NCa efficiently removed the two harmful red-tide algae, and the removal efficiency increased with increasing NCa dosage and initial pH value. Both A. carterae and H. akashiwo can be completely removed through 80 mg·L^-1 NCa treatment at pH10.0 in 1.5 h. The results of transmission electron microscopy showed that the change of cellular structure induced by NCa can be negligible in 12 h. In addition, we found that NCa is efficient in removing phosphorus. The removal efficiency (>85%) of phosphorus achieved by NCa in a wide range of acidity (pH4.0~10.0) was higher than that achieved by nZVI. In summary, our findings demonstrated that NCa removes both harmful algal cells and nutrients in water bodies, holding a high potential of HAB control.
• Isolation, expression and RNA interference of seawi of sea urchin (Mesocentrotus nudus)

  Su Weiyi, Liu Bingzheng, Zhang Jian, Chang Yaqing, Sun Zhihui

  2026, 48(5): 196-205. https://doi.org/10.13984/j.cnki.cn37-1141.2026.05.022

  Abstract ( ) PDF ( )

  To identify sex-related genes and analyze the molecular mechanism underlying gonadal development of sea urchins, in present study, we isolated the homologous gene seawi of piwi, and elucidated the molecular characteristics and evolutionary relationships of sea urchin (Mesocentrotus nudus). The dynamic expression patterns were analyzed through real-time quantitative PCR (RT-qPCR), and we found that seawi is a maternal factor. It expressed ubiquitously in adult tissues, but its transcripts were 23-fold more abundant in testis than in ovary. Results from in situ hybridization of tissue sections showed that seawi highly express in the germ cells of testis and ovary of M. nudus. In addition, we found also that the downregulation of seawi expression in testes leads to dynamic changes of dmrt 1, soxE and seali expression, suggesting that seawi plays a significant role in testis differentiation and maintenance. Overall, our findings laid a foundation for deciphering the mechanisms underlining the gonadal development of sea urchin.
• Population genetic diversity analysis of Charybdis feriata inhabiting the southeast coast of China based on mitochondrial COI sequences

  Tang Di, Yang Mingqiu, Zou Xiong, Liu Hongtao

  2026, 48(5): 206-214. https://doi.org/10.13984/j.cnki.cn37-1141.2026.05.023

  Abstract ( ) PDF ( )

  To understand the current status of the germplasm resource of Charybdis feriata inhabiting the coast of China, in present study, we analyzed the genetic diversity of five wild Charybdis feriata geographic populations, namely, Sanya of Hainan, Beihai of Guangxi, Yangjiang of Guangdong, Zhangzhou of Fujian and Ningbo of Zhejiang based on mitochondrial COI gene sequences. The results showed that a total of 44 sites including 17 parsimony-informative ones varied among 150 Charybdis feriata COI sequences (651bp in length). A total of 42 haplotypes were defined with Hap2 as the dominant one. The average haplotype diversity index ( H_d ) of the five C. feriata populations was 0.544±0.106, and the average nucleotide diversity (π) was 0.00142±0.00026, indicating a high level of haplotype diversity and limited nucleotide diversity. Genetic distance and genetic differentiation coefficient among different populations were less than 0.05. The molecular phylogenetic tree did not show a clear genealogical structure, and the results of the AMOVA showed that the genetic variations mainly occurred within the populations. Neutrality tests with the distribution of nucleotide mismatches indicated that there is selection pressure or a significant expansion event among C. feriata populations along the southeastern coast of China. In summary, there is no significant genetic differentiation among C. feriata populations along the southeast coast of China, and Hainan population is the richest in genetic diversity ( H_d=0.680, π=0.00179).
• Heavy metal enrichment characteristics of Pelophylax nigromaculatus in the Wanshan mercury mining area, Guizhou province

  Zhang Xiaodong, Lu Zhihong, Wang Ting, Yang Chuandong

  2026, 48(5): 215-223. https://doi.org/10.13984/j.cnki.cn37-1141.2026.05.024

  Abstract ( ) PDF ( )

  To understand the bioaccumulation characteristics of heavy metal elements in Pelophylax nigromaculatus, the tissues of Pelophylax nigromaculatus (liver, kidney, skin, bone, muscle and stomach) were collected from Xiaxi river, Aozhai river and Wawu river in Wanshan mercury mining area. The contents of Cr, Mn, Ni, Cu, Zn, Cd, Pb, As, Se and Hg in the sampled tissues were compared and analyzed, and the hepatosomatic index (HSI) was used to evaluate the health status of Pelophylax nigromaculatus. The results showed that the content of essential trace elements was significantly higher than non-essential elements in the tissues of Pelophylax nigromaculatus. Its active absorption of essential elements was relatively obvious. The liver and kidney were the main organs of heavy metal enrichment. Cr, Cd and As were primarily accumulated in the kidney, Cu and Hg in the liver, Se in the liver and kidney, Mn, Pb and Ni in the bone, Zn in the skin and kidney. The heavy metals in tissues were mainly ingested by the skin from the water environment, but absorbed from foods was lower. The correlation analysis showed that the contents of seven heavy metals were negatively correlated with HSI in this study. This was due to the heavy metal pollution in the Wanshan mercury mining area, which may have affected the health status of Pelophylax nigromaculatus. However, when Pelophylax nigromaculatus were dissected, we did not find any obvious lesions in its tissues. This may be related to the higher Se content in tissues, which can alleviate the toxicity of heavy metals, and species in this area may have evolved resistance to environmental heavy metal pollution. The results provided a scientific basis for environmental pollution control and animal protection in Wanshan mercury mining area.
• Research Report
• An ecological risk study on the geological sequestration of carbon dioxide in ocean

  Liu Tao, Zhou Xingzheng, Lou Qi, Du Peng, Miao Fengkai, Li Zhengyan

  2026, 48(5): 224-233. https://doi.org/10.13984/j.cnki.cn37-1141.2026.05.025

  Abstract ( ) PDF ( )

  Large emissions of greenhouse gases such as carbon dioxide (CO₂) have led to rising global temperature due to the overuse of fossil fuel since the Industrial Revolution. To cope with global warming, many developed countries and regions such as the United States and Europe have put forward carbon neutral targets in the past two decades. China also proposed the dual-carbon strategy in 2020, requiring both emission reduction and sink increase for CO₂. Similar to green energy development and carbon emission reduction, carbon sequestration and utilization are also crucial. The potential capacity for geological storage of CO₂ in the ocean is huge, but it may also cause ecological and environmental risks. In this paper, we analyzed the background of geological storage of CO₂ in ocean, elucidated the biological effects and ecological risks caused by storage leakage, summarized the knowledge gap of the current research, and prospected the future research direction. Our works can provide a scientific basis for ecological risk management and environmental policy formulation of geological storage of CO₂ in ocean.
• Climatic characteristics of high temperature over Zhoushan area during 1963—2017 and assessment of extreme high-temperature event

  Xu Zheyong, Ma Hao, Fu Na, Sun Yi, Wang Jiankan, Lu Qi

  2026, 48(5): 234-243. https://doi.org/10.13984/j.cnki.cn37-1141.2026.05.026

  Abstract ( ) PDF ( )

  Traditional high-temperature threshold-value (35 ℃) is usually hard to represent and describe high temperature phenomenon over island areas. Based on station observations over Zhoushan region during 1963-2017, the suitable threshold-value (named real threshold-value afterward) of high-temperature in Zhoushan was identified as 32 ℃ through the percentile rank detection. Under the real threshold-value constraint, annual mean number of high-temperature days (NHTD) was 13.5d and yearly NHTD mainly distributed within 5~30 d. In 2017, NHTD over Zhoushan got the maximum value of 41d. As for extreme high temperature (EHT), in all of the years, EHT over Zhoushan was above 32 ℃; besides, it could exceed 35 ℃ in most years and be even higher than 40 ℃ in 2007 and 2013. The EHT in Zhoushan experiences shifted suddenly in 2005 and jumped to a new stage with larger values. An extreme heat wave (EHW) appeared over Zhoushan in 2017 with NHTD was distinctly more than its climatological value. NHTD and EHT ranked the first and the forth respectively in observation record, and the percentage of HTD anomaly in Zhoushan was much more than that in other cities in Zhejiang province. Radiative heating induced by prominent sunshine was the direct cause for the formation of EHW. Besides, persistent anomaly of western Pacific subtropical high (WPSH) provided critical large-scale circulation background. Especially, the ridge line of WPSH was located to the south of its climatological position firstly and then to the north after 1 month nearby. The westward-extension ridge point stayed consistently to the west of its climatological range. Both factors helped to make Zhoushan under the control of WPSH and finally triggered the EHW event.
• Studies on the paleoenvironment of Yellow River alluvial plain through on element analysis

  Cao Yanling, Cui Su, Zhao Bo, Li Jie, Wu Bo, Zhu Xin, Sun Shuang, Jing Lu

  2026, 48(5): 244-253. https://doi.org/10.13984/j.cnki.cn37-1141.2026.05.027

  Abstract ( ) PDF ( )

  The formation and geomorphology evolution of lakes in the lower reach of Yellow River are closely related to the course-changing and outburst of Yellow River. Based on the geochemistry survey and mapping in Dingtao District, Heze, we analyzed the strontium-rich soil samples. We found that the ratio of Mn/Sr is less than 10, the ratio of Sr/Cu is mostly less than 10, the ratio of Mg/Ca varies between 0.28 and 0.40, the ratio of Sr/Ca ranges from 0.0022 to 0.0047, the ratio of Sr/Ba varies between 0.27 and 0.57, the ratio of V/(V + Ni) varies between 0.54 and 0.82, the most of V/Cr values are less than 2, the Ni/Co values are less than 5, the ratio of ⁸⁷Sr/⁸⁶Sr varies between 0.714893 and 0.715572, and the ratio of Rb/Sr ranges from 0.35 to 0.66. The analysis of the data showed that the sediments in the studied area have not undergone a strong alteration after deposition, the paleo-depositional environment is wet and lacustrine, and the paleo-depositional environment is oxidizing environment. The source of sediment in the studied area was the loose material with higher weathering degree of the basin crust source. The sediments a 2.0 m depth were 14C dated back to about 5, 167±77 a, belonging to the Middle Holocene of Quaternary. The analysis of strontium at 2.0 m depth sediments of the studied area showed that the redox environment and climate conditions in the alluvial plain of lower Yellow River are represented by the Heze Dingtao District region. The source of strontium-rich rocks in the upper reach of Yellow River was deposited after weathering and transported to the old channel of Yellow River.
• Mechanism and empiricism of the transformation of new and old marine kinetic energy and economic development

  Di Qianbin, Chen Xiaolong

  2026, 48(5): 254-263. https://doi.org/10.13984/j.cnki.cn37-1141.2026.05.028

  Abstract ( ) PDF ( )

  The conversion of the new and old kinetic energy of marine economy is an important symbol of implementing the new development concept and promoting the transformation and upgrading of marine economy. According to the inherent requirements of the transformation and development process of new and old kinetic energy of marine economy, the index system of the transformation and development process of new and old kinetic energy of marine economy was constructed. The improved TOPSIS model and the composite system synergy model were used to measure the index and relationship of the transformation and development process of new and old kinetic energy of marine economy from 2006 to 2020, and the geographical detector was used to explore the influencing factors and interactions. The index of new and old kinetic energy conversion and development process of marine economy showed an increasing trend. The marine green development was at a high level, and the cultivation of marine knowledge was the most significant. The input-output efficiency of the development process gradually increased also. The order degree of the two showed a continuous upward trend. The order degree of the development process was higher than that of the old and new kinetic energy conversion, but the degree of synergy was low. In 2015, it was in a mildly uncoordinated state while in other years it was in a mildly coordinated state. The factors driving the transformation and development of new and old kinetic energy in the ocean were mainly the level of marine consumption capacity, the ability of opening up to the outside world and the scale of marine market. The interaction of different influencing factors had a greater influence on the development than the influencing factors themselves.
• An evaluation of the tourism development suitability in Mauritius based on land-sea coordination

  Huang Xu, Yu Jing, Zhang Kuncheng, Chen Peixiong, Wang Zhiwen

  2026, 48(5): 264-272. https://doi.org/10.13984/j.cnki.cn37-1141.2026.05.029

  Abstract ( ) PDF ( )

  Considering the characteristics of island tourism and the resource and environmental conditions of Mauritius, a land-sea coordinate island tourism development suitability evaluation index system was constructed, which was consisted of three aspects, natural environment, tourism resources and development conditions, and its tourism development suitability was evaluated using the Analytic Hierarchy Process and comprehensive index method quantitatively in order to reflect the tourism development suitability in island areas more comprehensively. We concluded that the spatial variation of the tourism development suitability in Mauritius is obvious. The suitable area is 331.26 km², accounting for 10.31% of the total, which mainly distributes in the northern and eastern coastal areas of Mauritius. The relatively suitable, basic suitable and relatively unsuitable areas are 550.22, 727.11, 790.75 km², respectively, accounting for 17.11%, 22.61%, 24.59% of the total each. These areas are distributed along the coastline of Mauritius and extend from the western coast to the central part of the island. The unsuitable area is 816.16 km², accounting for 25.38% of the total, which is mainly distributed in the central and southeastern part of Mauritius and in the sea area away from the coastline.
• Research Review
• Research progresses in the vertical stratification of water body physical and chemical factors

  He Dilin, Qin Yu, Mao Yufeng, Li Zhaoxia, Li Weiqing

  2026, 48(5): 273-281. https://doi.org/10.13984/j.cnki.cn37-1141.2026.05.030

  Abstract ( ) PDF ( )

  Water body stratification takes place mostly in lakes, reservoirs and other deep-water bodies with low mobility. Stratification of physical and chemical properties of water bodies is closely related to water quality change. The stratification documented in lakes, reservoirs and rivers was studied, and the methods of evaluating water stratification stability were summarized. The summarized included also the seasonal characteristics and vertical distribution characteristics of water temperature, chlorophyll a and dissolved oxygen stratification. Water stratification stability can be judged with the aids of index, buoyancy frequency square value, water retention time, water relative stability (RWCS), thermal stratification stability index (RWCS/H), density Froude number, width to depth ratio and APE reservoir potential energy index. Water temperature, chlorophyll a and dissolved oxygen are often positively correlated with each other when water is stratified. In spring and summer, water temperature, chlorophyll a and dissolved oxygen concentration drop down with depth in general. The phenomenon of vertical stratification gradually disappears in autumn and winter, and tends to stabilize finally. Water temperature stratification, the main reason for the vertical stratification of chlorophyll a and dissolved oxygen, is caused by the atmospheric temperature. Meanwhile, phytoplankton, light condition, organic matter and nutrient, zooplankton, anaerobic bacteria and stratified density flow influence also the water temperature stratification.
• A review of compound extreme events based on CiteSpace

  Liu Chang, Yang Shuguo, Chen Qiaojun, Yin Baoshu, Li Delei

  2026, 48(5): 282-291. https://doi.org/10.13984/j.cnki.cn37-1141.2026.05.031

  Abstract ( ) PDF ( )

  The extreme events have posed significant challenges to human society and the ecological environment. Compound extreme events are more complex and severe in their destructive nature, which are the focus of attempts to better understand their development and address effectively the risks posed by climate change. The findings indicated that the number of publications on compound extreme events has been steadily increasing since 2012 in three distinct phases, stable growth, slow increase and rapid growth. The publication output in this field is mainly from China and the United States although China has a lower centrality and needs to strengthen international cooperation. Analysis of the Web of Science (WOS) categories revealed that the research in this field is primarily concentrated in multidisciplinary subjects such as meteorology, environmental science and earth science. The current research focuses on various combinations of extreme precipitation, droughts, floods, heatwaves and storm surges as were determined by keyword and citation analysis. In this study, we presented a unique review of research in this field, and provided scientific references for and insights into further investigation of compound extreme events.
• Research progress on ecological impact and restoration of marine oil and gas development

  An Mingming, Wang Shumin, Zhou Bin, Liu Tao

  2026, 48(5): 292-300. https://doi.org/10.13984/j.cnki.cn37-1141.2026.05.032

  Abstract ( ) PDF ( )

  The potential for offshore oil and gas development is enormous. The huge demand for energy in China's economic development has continuously accelerated the pace of offshore oil and gas exploration and development. In the process of developing and utilizing marine oil and gas resources, construction, production, and other processes have a wide range of impacts and great harm to the marine ecological environment, and corresponding ecological restoration measures need to be taken to restore the balance of the ecosystem. This article elaborated on the impact of marine oil and gas development to marine ecosystems and ecological restoration measures. It analyzed the possible impacts of the four stages of marine oil and gas development and the impact of marine oil and gas pollution on marine ecology. It reviewed the current research progress of restoration measures and prospects for future research directions. The impact of oil pollution on typical marine ecosystems such as mangroves, seagrass beds, coral reefs, oyster reefs, and salt marshes, as well as corresponding restoration measures, were emphasized.