10 October 2024, Volume 46 Issue 5

    

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• Research Paper
• Joint probability analysis of extreme tide level and storm surge duration

  ZHAO Guanhua, DONG Sheng

  2024, 46(5): 1-8. https://doi.org/10.13984/j.cnki.cn37-1141.2024.05.001

  Abstract ( ) PDF ( )

  Typhoon disaster is one of the most important factors that should be considered in the construction of marine structures. In present study, 31 typhoons affecting the coastal areas of Gudong oil production plant in Dongying City during 1960 and 2019 were simulated and the tide levels near the project site were calculated. The generalized extreme value (GEV) distribution model was applied to fit the marginal distributions of both extreme tide level and storm surge duration. The dependence structure of these two environmental conditions was described by a Gumbel-Hougarrd copula function. Considering the effect of the typhoon frequency on the design values, the Poisson compound extreme value distribution was used to perform the statistical analysis. The results indicate that the joint return period estimated by the proposed model acts as a reasonable representation of the storm surge disaster grade, and thus provides essential information for coastal disaster prevention and mitigation and marine structure design.
• Experimental investigations of sediment suspended by internal solitary waves under the influence of seepage

  REN Ziyin, TIAN Zhuangcai, JIA Yonggang, CHEN Tian

  2024, 46(5): 9-20. https://doi.org/10.13984/j.cnki.cn37-1141.2024.05.002

  Abstract ( ) PDF ( )

  Current researches on the resuspension process of marine sediments were mainly divided into two aspects: the dynamic action of marine fluids and the dynamic response process of sediments under the dynamic action. Internal solitary waves can move hundreds of meters between oceanographic thermocline, which not only has horizontal flow, but also can induce extremely strong vertical flow, which further causes the migration of sediment and pollutants. Therefore, the phenomenon of sediment resuspitation caused by the internal solitary waves shoaling and propagating on the slope has attracted much attention. With the flume experiment based on the researches, the setting up sediment slope and sediment layer in the control group, with controlling seepage condition, controlled the dynamic response of seabed sediment. By making the concave type internal solitary waves, the changing of sediment grain-size composition and internal solitary wave amplitude, comparison and analysis of different internal solitary wave under the condition of shallow broken cause of sediment resuspension phenomenon, were discussed about the influence of the dynamic response process of resuspension of sediments. The main research results were found that under the action of internal solitary waves, the faster the flow rate was, the faster the sediment suspended matter concentration changed; and the increased value of suspended matter concentration presented a positive correlation trend. For sediment slope area, with seepage conditions under the action of internal solitary wave could sustain high suspended sediments concentration for a longer time; the duration of continuous change was obviously longer than that of sediment layer. And with the slower velocity, slope area after achieving the highest suspended sediment concentration, concentration change rate was less than the sediment layer. For sediments with different grain-size composition, with the more clay content, the response speed to the internal solitary waves became more slowly, and the specific variation law was also different. When sediment components were sandy silt, under the action of internal solitary wave, variation of suspended sediment concentration in layer area was larger than it in slope area. And in the gap of two waves, the duration of higher suspended sediment concentration in slope area was much longer, the maximum could reach 2.5 times of that in the layer area. When the composition of sediment was clayey silt, the increased value of suspended matter concentration in the sediment slope area was 1.6-2.2 times of that in the sediment layer area.
• Numerical simulation of wave pressure at submarine slope surface under progressive waves

  ZHU Feiyang, LIU Xiaoli

  2024, 46(5): 21-27. https://doi.org/10.13984/j.cnki.cn37-1141.2024.05.003

  Abstract ( ) PDF ( )

  Wave-induced slope instability can threaten the safety of offshore engineering. The wave pressure distribution at the slope surface directly influences the slope stability. The hydrodynamic numerical model based on the finite volume method was used to simulate the propagating process of progressive wave over submarine sloping bed. After validation of the numerical model, the influence of water depth, wave height and wave period on the characteristics of wave pressure distribution at slope surface was further investigated. The results showed that the smaller water depth, the larger wave height, and the longer wave period would lead to larger wave pressure on the slope prior to wave breaking. For the case of wave breaking, the smaller water depth, the shorter wave period, and the larger wave height and inclination of the slope could cause the wave breaking zone moving toward the offshore. For gentle slopes with an inclination angle of 3°~9°, the maximum wave pressure might increase by 20%~80% of that at the bottom of the slope. The wave pressure before wave breaking increases nonlinearly over the sloping bed, and the increased ratio of the maximum wave pressure to that at the bottom of the slope might be enlarged by 1.2~1.3 times due to wave breaking. The wave pressure decreased significantly after wave breaking, and its value might be smaller than that at the bottom of the slope.
• Research on wave height prediction method based on deep learning and CatBoost

  LU Peng, NIAN Shengquan, ZOU Guoliang, WANG Zhenhua, ZHENG Zongsheng

  2024, 46(5): 28-34. https://doi.org/10.13984/j.cnki.cn37-1141.2024.05.004

  Abstract ( ) PDF ( )

  Based on deep learning and CatBoost technology, a hybrid model (LACM) was proposed to predict wave heights in the Gulf of Mexico, Bay of Fundy and Gulf of Alaska, which could then be applied to other sea areas. Firstly, the wave data obtained from the National Data Buoy center (NDBC) were preprocessed. Secondly, the LSTM neural network model and CatBoost integrated learning model were constructed. The predicted results were reconstructed. Compared with the LSTM, support vector regression (SVR), CatBoost and other methods, the experimental results showed that the mean absolute error (MAE), root mean square error (RMSE) and mean absolute percentage error (MAPE) of the LACM model were the lowest, and the prediction result was the best and the fitting effect was the closest, and it had a certain robustness.
• Research of the stress characteristics of combined horizontal with arc plate type permeable breakwater

  XIE Xiaomin, LI Xueyan, XIU Chunyi, CHENG Zhi, HOU Fang

  2024, 46(5): 35-43. https://doi.org/10.13984/j.cnki.cn37-1141.2024.05.005

  Abstract ( ) PDF ( )

  This paper designed a combined horizontal with arc plate type open breakwater dike structure. The factors such as different relative diving depth, relative wave height, relative plate width and relative plate spacing were discussed for the new type of open breakwater dike structure and the influence of wave pressure and total wave force received at different measurement points, based on the physical model test. The study results showed that, in most cases, the above-mentioned influencing factors had significant effects on the wave pressure at different measuring points of the new type of open breakwater. The positive pressure value and negative pressure value of each measuring point were small when the relative latent depth was -0.05, and when the relative latent depth was 0. The positive pressure value and negative pressure value of the structure were the largest. When the relative wave height increased from 0.10 to 0.17, the positive pressure value and the negative pressure value increased. As the relative plate width decreased within a certain range, the positive pressure value and the negative pressure value increased in most cases. When the relative plate spacing changed, the pressure on the lower surface of the upper plate and the upper surface of the lower arc plate had a significant impact. In most cases, the above-mentioned influencing factors also had a significant impact on the total wave force of the new type open breakwater. When the relative diving depth was 0, the total positive vertical force was the largest, and when the relative diving depth was 0 and 0.05, the total negative vertical force of the wave was larger. When the relative wave height increased from 0.10 to 0.17, the total vertical force and the total horizontal force both increased. When the relative plate spacing changed, the change of different relative plate spacing had little effect on the total wave force of the combined horizontal with arc plate type open breakwater.
• The seasonal variations of erosion processes off the modern abandoned Yellow River delta lobe

  JI Jinlong, WANG Baoduo, WANG Shixiong, WU Xiao, WANG Houjie, BI Naishuang

  2024, 46(5): 44-55. https://doi.org/10.13984/j.cnki.cn37-1141.2024.05.006

  Abstract ( ) PDF ( )

  Based on the continuous observation and tripod observation data of key stations in the abandoned Diaokou(DK) and Shanxiangou(SXG) delta lobe in August 2017 and in March 2018, the seasonal variations of erosion processes off the modern abandoned yellow river delta lobe were studied. The erosion process in the abandoned delta lobe of the Yellow River had significant seasonal characteristics. Under calm sea conditions in summer, the delta slope was strongly mixed and the delta front was stratified significantly. The average suspended sediment concentration (SSC) of the delta slope was about 25-55 mg/L, which was 1.5-3 times of SSC of the delta front. The erosion flux of the delta slope was about 2 times of that of the delta front. The suspended sediments were mainly transported to Bohai bay, the suspended sediment flux of the delta slope was about twice of that of the front area. The SSC in winter was 5-7 times of that in summer, and the average sediment concentration in the delta slope could reach 175-280 mg/L. The SSC increased significantly during storms and it could be 1-2 orders of magnitude higher than that in summer. Meanwhile, remarkable sediment liquefaction and cross-slope transport might occur during winter storm. Sediment trap records showed that the near bottom deposition flux under storm conditions was much higher than that under calm conditions, up to more than 20 kg/m²/d, which was about 30-50 times of that under calm sea conditions. A storm process could make the seabed sediments change in centimeter scale. The continuous action of tidal current was an important reason for the rapid erosion of the delta lobe in the study area, and the short time scale wave action under extreme weather was also considerable.
• Application and comparison of machine learning algorithms in remote sensing water depth inversion

  RAO Yali, SHEN Wei, LUAN Kuifeng, JI Qian, MENG Ran , HAO Lihua

  2024, 46(5): 56-63. https://doi.org/10.13984/j.cnki.cn37-1141.2024.05.007

  Abstract ( ) PDF ( )

  According to the principle of remote sensing water depth inversion, this paper used the WorldView-2 multi-spectral satellite remote sensing image and airborne Lidar data for four machine learning models, including extreme gradient boosting (XGBoost), support vector machine (SVM), kernel ridge regression (KRR) and least absolute shrinkage and selection operator (LASSO), to explore the impact of different machine learning models on the accuracy of water depth inversion. For deepth data, when the training sample and the test sample were the same, the grid search method was used to find the optimal parameter combination of the machine learning algorithm, and the water depth inversion experiment was carried out on the shallow waters around Ganquan island. Through the comparison and analysis of the inversion results of four types of machine learning models, the results were as follows: in the shallow water depth area of 20m, XGBoost model had strong learning ability, with correlation coefficient (R²) of 0.97, root mean square error (RMSE) of 0.85 m, average absolute error (MAE) of 0.63 m and average relative error (RME) of 19%, which was better than the other three machine learning models, and the overall effect was the best. It can be used to predict the water depth around Ganquan island and provide reference for subsequent water depth inversion research.
• Evolution analysis of local scour of umbrella suction anchor foundation under stokes wave and current

  WANG Qigang, LENG Hao, YU Yaqiong, CAO Tonggang

  2024, 46(5): 64-72. https://doi.org/10.13984/j.cnki.cn37-1141.2024.05.008

  Abstract ( ) PDF ( )

  The scour process around submarine pipeline in combined waves and current were experimentally investigated. Furthermore, the coupled waves and current-pipeline-fluid numerical model were built by the FLOW-3D software to study the scour and hydrodynamic characteristics around pipeline in combine waves and current. Based on the numerical results, the effects of water depth, pipeline diameter, pipeline suspended height on the scour depth were analyzed. The results indicated that the pressure difference between the upstream and downstream sides of the pipeline resulted in piping beneath pipeline, promoting the tunnel scour, which indicated the onset of scour. There were three vortex system around pipeline in waves, and it accelerated the scour. The scour depth was significantly influenced by the water depth, pipeline diameter, pipeline suspended height. A greater water depth and pipeline suspended height resulted in a smaller scour depth. The scour depth increased with the increase of current velocity.
• Analysis on water quality changes of buoys in Tangshan coastal waters after a storm surge “Lekima” in 2019

  WANG Jiuliang, LI Zhiyong, LIU Dewu, LI Yue, LI Yansong, LIU Pengfei, LI Jiajun, WANG Qiuyan

  2024, 46(5): 73-79. https://doi.org/10.13984/j.cnki.cn37-1141.2024.05.009

  Abstract ( ) PDF ( )

  In August 2019, affected by storm surge Lekima, there was a sustained heavy rain in Tangshan coastal area. The monitoring data of two buoy stations in the coastal water before and after the storm surge were analyzed. It was found that the daily average of water temperature decreased by 3℃ approximately, and the highest daily average of turbidity reached 38.6 ntu and 50.3 ntu,3.17 times and 12.89 times of those before the storm surge. At the same time, pH, chlorophyll-a and dissolved oxygen as well as salinity all showed small fluctuations, while the fluctuation range of water quality in the buoy station 2# was higher than that in buoy station 1#. The highest daily average of pH, chlorophyll-a and dissolved oxygen in buoy station 2# reached 8.25,2.882 ug/l and 7.7 mg/l, respectively, and the daily average of salinity decreased to 23.96 % as the lowest. The results showed that during the storm surge, the continuous heavy rainfall brought a large amount of land sourced materials and strong wind waves, which led to the intensification of vertical mixing of water bodies and the rise of bottom layer materials, resulting in different amplitude changes of water quality parameters before and after the storm surge in the observed sea area.
• Distribution, sources and ecological risk assessment of polycyclic aromatic hydrocarbons (PAHs) in surface sediments of Shenzhen bay

  WANG Jian, HE Jinxian, LIN Hai, GAN Huayang, SHI Shuai, LI Yang, CAO Wenjie

  2024, 46(5): 80-86. https://doi.org/10.13984/j.cnki.cn37-1141.2024.05.010

  Abstract ( ) PDF ( )

  The GC-MS analysis method was used to analyze the 16 multi-ring aromatic hydrocarbons in the surface deposition samples of Shenzhen bay in June 2020. The results showed that the 16 kinds of polycyclic aromatic hydrocarbon concentrations in the surface deposit in Shenzhen bay were 410 to 2486 ng · g^-1, the average concentration was 977.67 ng · g^-1, the overall was in moderate contamination level, and the polycyclic aromatic hydrocarbon in the sample high ring (4~6 ring) was mainly 5 ring (38.44%)> 3 ring (21.96%)> 6 ring (12.33%)> 2 ring (8.28%). Through the multi-cyclic aromatic hydrocarbon lightric ratio, the combustion of petroleum, coal and wood on the contribution rate of polycyclic aromats in Shenzhen bay's surface sediments was about 88%, which was the main source. Based on the reference method (SQGS), the analysis of the polycyclic aromatic hydrocarbons in the surface sediments of Shenzhen bay showed that the diphenyl (A, H) had great ecological risks. The naphthalene and fluorene had potentially ecological risks. Measures for pollution control must be used.
• Study on a sex bias in gene expression of Rhodeus ocellatus based on RNA-seq

  LIU Kai, FENG Xiaoyu, WU Yanqin, XIE Nan, CHU Tianjiang

  2024, 46(5): 87-95. https://doi.org/10.13984/j.cnki.cn37-1141.2024.05.011

  Abstract ( ) PDF ( )

  Understanding the sex bias of gene expression is helpful to understand the dimorphism of sex-related phenotypes, and it is also a significant field in the study of gene-phenotype interactions. To fill the genetic data gap and reveal sex bias in gene expression, RNA-seq of the muscle of Rhodeus ocellatus was carried out for the first time. Three females and three males were collected, respectively, and the muscle tissue was dissected from the fish. The exfoliated tissue was ground in liquid nitrogen, and total RNA was extracted. Then sequences through the Illumina HiSeq sequencing platform, and differential expression gene analyses were performed. The results showed that the Clean Data of 6.39 GB and 6.70 GB were obtained from the female and male R. ocellatus, respectively, and 46 194 Unigenes were obtained after assembly, with 59.68 Mb and an average sequence length of 1 354.67 bp. 24 754 Unigenes were annotated by comparing the databases, accounting for 53.59% of all Unigenes. GO functional annotation results showed that 25 887, 21 822, and 10 008 Unigenes were annotated into three GO classifications: biological process, cellular component, and molecular function. Three thousand thirty transcription factors were predicted, and 22 560 microsatellites were obtained. Differential expression analysis showed 3 216 differentially expressed genes between females and males, of which 1 796 were significantly up-regulated and 1 420 were significantly down-regulated in males. GO enrichment analysis showed that gene expression differences between males and females were mainly concentrated on GO terms such as hydrolase activity, transporter activity, and extracellular region. KEGG pathway enrichment analysis showed that Epstein-Barr virus infection, complement and coagulation cascades, and protein digestion and absorption pathway were the three pathways with the most enriched differential genes. Protein-protein interaction network analysis showed that there were two major protein-protein interaction networks between female and male individuals. One consists of Proteasome Endopeptidase Complex, including PSMD1, Psmd3, Psmd5, and other related genes; the other consists of Fibrinogen, including Fga, Fgb, and Fgg. The gene expression of female and male R. ocellatus had an apparent sex bias. This study's results supplemented the transcriptomic information of R. ocellatus and revealed the sex bias of gene expression in R. ocellatus, and provided data support for further research on the sex bias of gene expression and phenotype interactions.
• A comparative analysis of serum and blood cell elements between Trematomus bernacchii and Chionodraco hamatus

  WANG Yuhang, XU Qianghua, WANG Shuo, HOU Weiwei, ZHAI Wanying

  2024, 46(5): 96-102. https://doi.org/10.13984/j.cnki.cn37-1141.2024.05.012

  Abstract ( ) PDF ( )

  To investigate the concentration differences of serum and blood cell elements between Trematomus bernacchii and Chionodraco hamatus, the contents of macro-elements (Na, K, Mg, Al, Ca, Fe and Zn) and micro-elements (V, Cr, Mn, Ni, Se, As, Pb) in the serum and blood cells of the two Antarctic fish species were determined and analyzed by ICP-OES. The results showed that there were significant differences in the contents of Cr, Mn, Ni and Se between the two Antarctic species serum. Fe and V showed significantly differences between the two fish species serum. And only Fe showed a significantly difference between the two Antarctic fish blood cells. These differences may be related to the lack of hemoglobin in C. hamatus. This experiment was the first trying to measure the contents of elements in the serum and blood cells of Antarctic fish, which complemented the research data of the hemocyte physiology and biochemistry research of Antarctic fish species, and provided the reference data for the further development and utilization of Antarctic biological resources.
• Effects of silver nanoparticle on growth, photosynthetic pigment content and chlorophyll fluorescence parameter of Phaeodactylum Tricornutum

  ZHANG Yunfei, LI Bin, LIU Caili, ZHANG Xinze, HU Yujun, GAO Jiqing, CHEN Lizhu, SUN Chunxiao, TIAN Xiuhui, HU Shunxin

  2024, 46(5): 103-110. https://doi.org/10.13984/j.cnki.cn37-1141.2024.05.013

  Abstract ( ) PDF ( )

  In recent years, the widespread application of silver nanoparticles (AgNPs) has inevitably led to their release into the surrounding environment, ultimately accumulating in nearshore waters through surface runoff. In order to understand the effects of AgNP on the growth and photosynthesis of marine microalgae, in this study, we selected Phaeodactylum tricornutum as the experimental object and investigated the impact of AgNPs on the growth and photosynthesis of P. tricornutum under acute stress for 96 hours. The results showed that at an environmental concentration of 0.01 mg/L, AgNPs had no significant effects on the growth and photosynthesis of P. tricornutum. With the increase of AgNPs concentration, the growth of P. tricornutum was significantly inhibited (P<0.05), and a dose-dependent relationship was observed. At 2 mg/L, the inhibition rate reached 69.57%, and at 4 mg/L, the growth of P. tricornutum was almost completely inhibited (inhibition rate, 96.03%). The high concentration (4 mg/L) of AgNP affected the photosynthetic system of P. tricornutum with a significant decrease in the contents of chlorophyll a, chlorophyll c and carotenoids (45.3%, 36.67%, and 54.47%), respectively. The maximum photochemical quantum yield (Fv/Fm), actual photochemical efficiency (YII) and maximum relative electron transfer rate (rETRmax) in PSII were also inhibited. These findings indicated that AgNPs at high concentrations can inhibit the growth and photosynthesis of P. tricornutum.
• Habitat model optimization of purpleback flying squid inhabiting South China Sea and its seasional change

  FAN Jiangtao, FENG Zhiping, YU Wei, MA Shengwei, CHEN Xinjun

  2024, 46(5): 111-120. https://doi.org/10.13984/j.cnki.cn37-1141.2024.05.014

  Abstract ( ) PDF ( )

  Purpleback flying squid (Sthenoteuthis oualaniensis) is a cephalopod species with high economic values. It is largely exploited by Chinese fishing vessels in the South China Sea. The location of fishing ground showed seasonal differences, which may be related to habitat distribution of this squid species. Based on the fisheries data of S. oualaniensis in the South China Sea from Spring to Autumn, 2014-2017, and by combining with key environmental factors each season including water temperature at 50 m (Temp_50 m), chlorophyll-a concentration (Chla) and mixed layer depth (MLD) in spring, sea surface temperature (SST), Chla and water temperature at 100 m (Temp_100 m) in summer, and SST, Chla and MLD in autumn:, a weighted-based habitat suitability index (HSI) model was developed in this study. The optimal HSI model was selected each season to predict the HSI value. The seasons, spring and autumn, were taken, for example, to compare the habitat patterns and further examine the impacts of the strong El Niño events on S. oualaniensis habitat. The results suggested that the selected optimal HSI model can accurately predict the fishing ground of S. oualaniensis, with the model precision of 86% in spring, 75% in summer and 76% in autumn. The area of the suitable habitat with HSI>0.6 and the optimal suitable habitat with HSI>0.8 enlarged in spring comparing to the autumn, and the optimal habitats were widely distributed in the northern waters of the South China Sea. While the habitat suitability in autumn clearly decreased, the optimal habitats in Zhongsha and Nansha Island mainly disappeared, with a few occurred in the northeastern waters. From a spatial perspective, the latitudinal gravity centers of the optimal habitats in spring during 2014-2016 moved northeastward relative to the habitat in autumn, whereas the poor habitat with HSI<0.2 shifted southwestward. Comparing the year of 2014 with normal climate condition with the year of 2015 with strong El Niño event, it was found that the area of the optimal habitats significantly decreased and the poor habitats dramatically increased. Our findings suggested that the HSI model based on the weighted-based algorithm and key environmental factor could be applied to predict habitat hotspots of S. oualaniensis in the South China Sea. The habitat pattern showed seasonal difference, and the strong El Niño event yielded profound negative effects on habitat suitability of S. oualaniensis.
• Research Report
• Study on the evaluation method of early-warning of the marine resources and environmental carrying capacity of Tianjin maritime space

  MA Yuyan, TU Jianbo, SHI Haiming, SUN Huan, BO Wenjie, JIANG Xujuan, ZHENG Meiling, TAN Xiaoxuan

  2024, 46(5): 121-130. https://doi.org/10.13984/j.cnki.cn37-1141.2024.05.015

  Abstract ( ) PDF ( )

  In this paper the index system, including basic evaluation, specific evaluation and process evaluation of early-warning of the marine resources and environmental carrying capacity of Tianjin maritime space was constructed. The study had referred to the relevant research progress domestically and internationally, and the Technical Manual of Resources and Environment Carrying Capacity Monitoring and Early-Warning (Trial) issued by the National Development and Reform Commission of the People's Republic of China had also been referenced. The basic evaluation was used to conduct an overall evaluation for jurisdictional maritime area and was measured by nine indicators including three categories: marine space resources, marine fishery resources and marine ecological environment. The specific evaluation included four indicators and was used to conduct specific evaluations for different major functional zones, such as optimized development zones and prohibited development zones. The process evaluation included five indicators and divided into three categories: the consumption of marine resources, the changes of ecological environment , and the changes of ecological disaster risk. The process evaluation was often used to indicate the variation tendency of the pressure which could vary with the human activities and was shouldered by marine environmental resource. Buckets effec and the analytic hierarchy process (AHP) comprehensive evaluation were used in this study respectively. The results showed that the evaluation results obtained by the AHP comprehensive evaluation were more in line with the actual situations of Tianjin. The marine resources and environmental carrying capacity of jurisdictional maritime area had been overloaded from 2011 to 2019. The evaluation results of marine resources and environment consumption was slowing down, and the early-warning levels of Tianjin were in the slight warning (blue) state. The corresponding measures were put forward according to the evaluation results. The above results could technically help us to carry out the early-warning evaluation of national marine resources and environmental carrying capacity.
• Influence of sea condition of the Central and Western Pacific on yellowfin tuna (Thunnus albacores) fishery

  SI Wen, YANG Guo, WANG Xuehua, ZHANG Chunling, HU Song

  2024, 46(5): 131-138. https://doi.org/10.13984/j.cnki.cn37-1141.2024.05.016

  Abstract ( ) PDF ( )

  The sea condition has a decisive influence on the difficulty of fishery production and the safety of fishing vessels. The meteorological condition is also one of the important inducement for the formation of fishing area and the change of resources. Choosing the yellowfin tuna as the studying object and based on the ten-year meteorological satellite observation and reanalysis data set from 2008 to 2017, in this paper, we systematically analyzed the characteristics of wind and wave in the fishing area。 By combining with the production data of yellowfin tuna during the same period, we analyzed and evaluated the influence of sea condition on fishery production. The results showed that the average wind speed in the Central and Western Pacific is about 5~6 m/s, the instantaneous wind speed varies between 4 and 6 m/s, the average significant wave height is less than 2 m, and the instantaneous local significant wave height changes from 1 to 3 m. Essentially, the monthly average wind speed and average significant wave height are inversely proportional to the number of fishing operations. The grade of sea condition in most of the fishing area varied between III and IV. And the sea condition of grade III in summer and autumn is more suitable for fishing vessel operation than that in winter and spring.
• Heavy metals in the surface sediment of the coastal waters along the Shandong peninsula and their pollution evaluation

  GUANG Xia, CHU Zhongxin, MIAO Anyang, HUO Suxia, ZHU Longhai

  2024, 46(5): 139-145. https://doi.org/10.13984/j.cnki.cn37-1141.2024.05.017

  Abstract ( ) PDF ( )

  In order to understand the concentrations characteristics of heavy metals in surface sediments of the coastal waters along the Shandong peninsula, the concentrations of heavy metals including Hg, Cu, Pb, Cd, Cr, Zn, As in 40 samples were measured by flame spectrophotometry and atomic fluorescence spectrometric. The index of geoaccumulation (Igeo) and the potential ecological risk index were then employed to evaluate the pollution degree and potential ecological risk of heavy metals in the sediments. The results indicated that the average mass concentration (mg/kg) of Hg, Cu, Pb, Cd, Cr, Zn, As in the coastal waters along the Shandong peninsula were 0.05, 16.51, 15.04, 0.16, 27.69, 28.16, 5.72, respectively. The pollution level of heavy metals in sediment by Igeo followed the order: Cd>Cu>Pb>Hg>Zn>Cr>As. The Igeo of most area was clean or in low level, except Cd and Cu were in low to medium level. The potential ecological risk of heavy metals in sediments by the potential ecological risk factors (Eⁱ_r) followed the order: Cd>Hg>As>Pb>Cu>Cr>Zn. The potential ecological risk of most study area was in the low level, except for 24 stations which was in the medium level.
• Current status of phytoplankton community in green tide area of radial sand ridges during prevention of Ulva prolifera

  ZHU Xuyu, GE Yuehao, YANG Bo, DING Yanzhe, BEN Chengkai, XIAO Yueyue, ZHANG Hu

  2024, 46(5): 146-154. https://doi.org/10.13984/j.cnki.cn37-1141.2024.05.018

  Abstract ( ) PDF ( )

  From November 2019 to May 2020, a continuous human intervention was carried out in the occurrence of Ulva prolifera in the green-tide area of radial sand ridges. To understand the change of phytoplankton community, we documented phytoplankton composition and environmental parameters in green-tide area (120°00′0″~124°00′0″E, 32°00′0″~34°00′0″N) in April in 2019 (before prevention of U. prolifera) and 2020 (after prevention of U. prolifera). A total of 4 phyla, 33 genera, 53 species were identified in 2019, which mainly included 43 diatom species, 7 dinoflagellate species, and 5 other taxonomic (Chrysophyta and Cryptophyta) species. A total of 6 phyla, 49 genera, 72 species were identified in 2020, which included 51 diatom species, 13 dinoflagellate species and other taxonomic (Euglenophyta, Chlorophyta, Chrysophyta, Cryptophyta) species . A total of 11 dominant phytoplankton species were found. Diatoms dominated the phytoplankton community, of them Paralia sulata was the top dominant species in 2019 and 2020. The average cell abundance in spring 2019 (1.39×10⁴ cells/L) was lower than that in spring 2020 (2.06×10⁴ cells/L). Both the phytoplankton community parameters (species number, Shannon-Wiener diversity index, Margalef richness index) and environmental factor (temperature, suspended solids, pH, dissolved oxygen, turbidity) were different between the two years. Spearman analysis and redundancy analysis showed that pH, dissolved oxygen, salinity, nutrients and suspended solids were the main factors influencing phytoplankton community.
• Study on turbidity and stabilization time of effluent from calcium carbonate mineralization process

  ZHANG Chengyi, WANG Lin, MU Chunxia

  2024, 46(5): 155-161. https://doi.org/10.13984/j.cnki.cn37-1141.2024.05.019

  Abstract ( ) PDF ( )

  The dissolving limestone in CO₂ acidified desalination seawater can effectively mineralize the seawater. The experiment studied the flow rate of CO₂ acidified water, the size of limestone filler, and the height of filler column on turbidity and stability time of the effluent, which can provide a reference for the process operation of calcium carbonate mineralization reactor. The results showed that increasing the size of limestone, the height of limestone filler, the ratio of CO₂ inflow, and washing the filler layer of the limestone multiple times are beneficial to reduce the turbidity of the mineralized effluent. Increasing the particle size of the limestone filler, the flow of CO₂ acidified water, and reducing the height of the limestone filler can shorten the mineralization effluent stabilization time. The limestone particles are 1-2 cm, the limestone filler height is 36.8 cm, the CO₂ inflow ratio is 0.12, and the hydraulic retention time is 3-4 min, all of which are better operating conditions.
• Investigation and evaluation of plankton resources and estimation of fish productivity of Doushan Reservoir

  DING Yuting, ZHOU Yanfeng, ZHANG Xizhao, ZHOU Yifan, GUO Shiyue, XUE Junjian, YIN Fangkai , YOU Yang

  2024, 46(5): 162-170. https://doi.org/10.13984/j.cnki.cn37-1141.2024.05.020

  Abstract ( ) PDF ( )

  The plankton resources, water nutritional status and fish productivity of Doushan Reservoir were investigated, analyzed and evaluated during the dry and wet periods from 2020 to 2021. A total of 45 species (including variants) of 8 phyla of phytoplankton, mainly green algae, diatoms and cyanobacteria; and 33 species of zooplankton, mainly protozoa and rotifers were identified. The analysis of community characteristics showed that the density and biomass of diatoms accounted for more than 85% in the dry period and the algae phase was diatoms type; the density and biomass of Cyanophyta accounted for more than 70% in the wet period and the algae phase was cyanophyte and cryptophyte type; the protozoan density accounted for more than 61% in the two periods, the rotifer biomass accounted for more than 76% and the small zooplankton accounted for a relatively high proportion. The nutritional type of the water was moderate to mild eutrophicated, and the pollution level was moderate to heavy polluted. CCA analysis showed that the main environmental impact factors of plankton were SD, DTN, TN and CODMn. According to the estimation of bait biology method, the fish productivity provided by plankton was 308.29 kg/hm². These findings are relatively complete records of the current status of aquatic biological resources and their water environment nutrition, which should aid to providing a necessary reference for the subsequent maintenance of the water environment of Doushan Reservoir and the ecological management of fishery.
• Discussion on new techniques of artificially breeding stable yield triploid Crassostrea gigas

  LI Qi, ZOU Duo, LI Chunhua, LI Haikun, YU Ruihai

  2024, 46(5): 171-175. https://doi.org/10.13984/j.cnki.cn37-1141.2024.05.021

  Abstract ( ) PDF ( )

  To solve the problems like low larval survival rate and low metamorphosis rate met in the artificial seedling production of triploid oyster (Crassostrea gigas), in this paper, we detailed the technical elements and key problems in the cultivation of tetraploid and diploid stocks, artificial insemination, hatching and larval cultivation. First, the detection of tetraploid oyster, and the cultivation of tetraploid and diploid stocks should be strengthened to promote the development and maturation of their gonads. During artificial insemination and hatching, the dissection and sex discrimination of diploid oyster should be strengthened, and uncontrolled fertilization should be eliminated to ensure the completeness (triploid rate 100%) of triploid larvae. At the same time, the hatching density should be strictly controlled to improve the hatching rate of larvae. During the larval culture, larval growth and larval survival rate can be promoted by reasonably controlling larval culture density, enhancing feeding of single-celled algae, ensuring stable breeding water quality and regular screening seedlings. In the attachment stage, the attachment metamorphosis rate can be improved by regulating the quality and quantity of attachment base, increasing the amount of water and bait, and reversing the string in time. In the middle stage of cultivation, water quality and density should be controlled to ensure the rapid growth and development of juvenile. A series of technical measures and key problems were proposed in this paper, which are of a great significance for improving the success rate of artificial seedling breeding of triploid oyster.
• Research Review
• Researching progresses on carbon sequestration capacity of typical coastal wetlands and its investigation and monitoring methods

  LIU Shujin, JING Junping, JU Lijun, WANG Qiuyan, HU Nan, Wu Shanshan

  2024, 46(5): 176-183. https://doi.org/10.13984/j.cnki.cn37-1141.2024.05.022

  Abstract ( ) PDF ( )

  Mangroves, seagrass beds and salt marshes are important components of marine "blue carbon" and marine ecosystems with strong carbon sinks. Based on the relevant studies at home and abroad, in this paper, we reviewed the studies on the carbon sequestration capacity of several typical coastal wetlands like mangrove, seagrass beds and salt marshes, the impact of wetland damage on such capacity, and the difficulties met in restoring and improving their carbon sequestration capacity. The reviewed included also the existing monitoring methods of coastal wetland carbon sink at home and abroad. We put forward suggestions and prospects from several aspects which include current monitoring of coastal wetland carbon sink, wetland protection and sink enhancement. Globally, coastal wetlands have a strong carbon sequestration capacity, 10 times that of terrestrial ecosystems. With urban expansion, human exploitation and utilization, the coastal wetlands may be transformed into industrial and construction lands, which is the main influencing factor for the loss of carbon sequestration capacity of coastal wetland ecosystem. Wetland restoration is difficult, has a long cycle and holds more uncertainties. At present, the monitoring methods of coastal wetland carbon source and sink mainly include inventory, direct measurement, remote sensing monitoring and ecosystem model methods. While countries are constantly exploring and improving the researches on coastal wetland carbon sink survey, there are still many problems. Therefore, the researches on coastal wetland survey should be strengthened in the following aspects including conduction of coastal wetland carbon sink and habitat quality surveys, establishment of the blue carbon survey system of coastal wetland, changing wetland use into account, integration of existing carbon sink survey data into databases supporting the optimization of policy making model, and exploring continuously the application of new survey methods in carbon sink investigation.
• A review of the impacts of oceanic fronts and mesoscale eddies on pelagic fisheries resources

  ZHANG Yuchen, CHEN Xinjun

  2024, 46(5): 184-191. https://doi.org/10.13984/j.cnki.cn37-1141.2024.05.023

  Abstract ( ) PDF ( )

  Oceanic fronts and mesoscale eddies, as two significant features in the open seas, are ubiquitous in the global ocean and make profound impacts on global ocean circulation and ocean ecology. Ocean fronts and mesoscale eddies are closely related to pelagic fishery resources. The foraging, migration, and stock recruitment of fishery resources are all influenced by these mesoscale oceanographic structure. The in-depth study of mesoscale oceanographic processes helps overcome the limitations of the researches of fisheries oceanography at large scales, lay the foundation for ecosystem-based fishery management as well. This paper provided a concise review of the impacts of ocean mesoscale variability, including fronts and mesoscale eddies, on pelagic fishery resources with feature extraction methods applied in researches involved briefly summarized. This review focused on the fish responses to fronts and mesoscale eddies and the underlying scientific mechanisms. The response of fishery resource organisms to fronts and mesoscale eddies varied, and it was speculated that they were dominated by feeding conditions and temperature suitability. The suggestions for the future research on the ecological effects of ocean fronts and eddies should be as follows: 1) considering the effects of fronts and mesoscale eddies together to obtain more comprehensive results; 2) making a more detailed discrimination of fronts and mesoscale eddies of different properties and development stages; 3) establishing a more complete observation, investigating and tracking system for marine organism.
• Quantitative evaluation of the resettlement policy of fishermen along Yangtze River

  ZHANG Zuping, WU Liuxiang

  2024, 46(5): 192-200. https://doi.org/10.13984/j.cnki.cn37-1141.2024.05.024

  Abstract ( ) PDF ( )

  The ten-year ban on fishing in the Yangtze River is an important measure to reverse the depletion of fishery resources and achieve sustainable development of fishery resources. Fishermen resettlement is an important follow-up to the implementation of the ten-year fishing ban plan on Yangtze River. To quantify and understand the advantages and disadvantages of the policy and the direction of improvement, in this paper, we adopted the PMC index model for quantitatively studying the policy of resettlement of fishermen who quit fishing in Yangtze River. The results showed that the overall score of the policy is not high; the scores of the first-level indicators of policies are different; and there is a large room for improvement in the nature, effectiveness, tools, areas, contents and objects of policies. Specific policies score was relatively low. Based on the results, in this paper , we put forward six suggestions on releasing policy effect, paying attention to policy effectiveness, making good use of policy tools, enriching policy content, broadening policy areas, expanding policy objects, and the specific direction of policy improvement.
• Researches on the sea use rights transaction among local governments: Based on evolutionary game analysis and simulation

  YU Xuan, SHEN Manhong, WEI Xinyi

  2024, 46(5): 201-210. https://doi.org/10.13984/j.cnki.cn37-1141.2024.05.025

  Abstract ( ) PDF ( )

  The sea use rights (SUR) transaction mechanism is the core of the marine property rights system. Under the current background of the reform of the natural resource asset property rights system, studying the issue of the SUR transaction mechanism is of a great significance for optimizing the marine property rights structure, improving the efficiency of marine resource allocation, and promoting the sustainable development of the marine economy. In this paper, we put forward a new idea of marine property rights arrangement under the existing two-level trading mechanism of SUR, that is, the transaction of SUR among local governments. We also embeded it into the existing framework and expanded the trading mechanism of SUR to three levels. Through the construction of a game model of SUR transactions among local governments and analysis, it was found that it is a rational choice of local governments to achieve SUR transactions under the premise that the transaction price and transaction volume of SUR are determined. The conclusion of SUR transactions among local governments can be facilitated by reducing the transaction cost in the transaction process, improving the sea use efficiency of the SUR demanding government, reducing the marine management cost of the SUR demanding government, and increasing the investment income of the SUR supplying government. The results based on Matlab simulation further confirmed these conclusions.