Based on the observations originated from satellites and archived in IFREMER, the sensitivity analysis and adaptive modification were conducted on the wind input source term, dissipation caused by white-capping and bottom friction and their parameters of SWAN model with unstructured mesh grid in the China adjacent sea. The applicability of the modified model was validated by performing 25 years numerical simulation. Results indicated that the reanalysis wind speed data from NCEP were consistent with observations in China sea and could be used as the wind forcing for wave simulation. The Komen pattern with the coefficient of 1.86×10^-5 for both the wind input source term and the dissipation caused by white-capping was considered as the optimal parameter combination for this sea area. As for calculating the dissipation due to the bottom friction, COLLINS model with default parameter was the most suitable. And the calibrated SWAN model was stable and could simulate the significant wave height more accurately in the China adjacent sea.

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.

The seahorse (Hippocampus abdominalis) inhabits southwestern Pacific Ocean and the waters near Oceania and New Zealand. Its large size, strong disease resistance and high survival rate in seedling cultivation make this species high in medicinal and economic values. In recent years, continuous global climate change has been impacting the marine ecosystems and reducing the natural resource of this species. Such scenario is even becoming worse due to the market demand increase. As a result, H. abdominalis has been listed in Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora(CITES). The researches relating to its resource conservation and development, reproductive biology and aquaculture technology are receiving intensifying attentions. In 2016,H. abdominalis was introduced into China where its artificial breeding of seedlings has met success and boomed currently. In this paper, we summarized the research findings in the biology and artificial breeding of H. abdominalis, and prospected the research direction, trying to provide a powerful reference for the resource protection and artificial breeding technology development of H. abdominalis.

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.

Based on coral reef survey in Wenchang waters with line transect method and historical data collected in 2012 and 2018, and using the semi-quantitative coral reef health index (hereafter as CI), the health status of coral reef ecosystem in Wenchang waters, the change trend and its main influencing factors were analyzed. A total of 79 species of hermatypic corals belonging to 11 families and 31 genera were identified, of them the dominants were the environmentally-tolerant massive ones, i.e., Porites lutea, Favia speciosa, Favites abdita, and Platygyra daedalea. However, Acroporidae, the environmental stress sensitive, were less observed, which had a low coverage. Despite the excellent water quality conditions of Wenchang waters, macroalgae were abundant with mean coverage up to 16%. The community structure of hermatypic corals have obviously changed. The CI value estimated ranged from -0.44 to 0.95, suggesting that the whole coral reef ecosystem was poor in Wenchang waters. Coastal engineering construction and aquaculture sewage discharge were perhaps the two driving factors leading to coral reef degradation in the region. However, compared with 2018, the health status of coral reefs in the region recovered significantly as were revealed by increased CI values from -0.59 in 2018 to -0.06 in 2020. Moreover, in this survey, the mean coverage of hermatypic corals was 12.73% and coral recruitment was 0.9 ind./m², displaying a slight increase compared with historical data. More importantly, little short-term dead corals and coral diseases were found in this survey. These signals indicated that the coral reef ecosystem in this area has a good potential for recovery. It was suggested that the ecological control should be strengthened, and coral reef restoration should be carried out to accelerate its natural recovery.

The eastern part of the Barents Sea is rich in oil and gas but covered by sea ice. With climate change, the sea ice continues to melt, making the eastern region maintain open water for longer, and wave characteristics will also change accordingly. It is necessary to carry out corresponding research for the design, construction and operation of marine engineering structures serving in this sea area. In this paper, the sea ice concentration data from the National Snow and Ice Data Center (NSIDC) were collected to drew the sea ice edge lines and analyzed the changes of sea ice extent. According to ice edge lines, one representative point was selected in the eastern sea ice melting zone. The wave data from the ERA5 dataset of the European Center for Medium-Range Weather Forecasts (ECMWF) were collected to study the basic wave characteristics and wave design parameters. The annual and seasonal extreme values of wave height were extract to estimate the return values of significant wave height by the GEV, Gumbel, Weibull and Maximum entropy distribution models, respectively. The results showed that with the reduction of sea ice, the frequency without wave at representative point had decreased significantly, and wave existence was throughout the year in recent years. According to the results of the return values, summer was the most suitable operating season.

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.

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.

Since the "13^th Five-Year" Plan, the ecological civilization construction of China has achieved remarkably; however, the environmental problems are still serious. As one of the important contents of ecological civilization construction, water pollution prevention and control need to be further promoted and strengthened during the "14^th Five-Year" Plan period. Constructing an analysis framework by taking the water environment policy texts of China as the research object since 1984 is based on the basic types of water environment policy tools, and combines the three dimensions of water pollution policy, governance process, policy issuance time and policy actors. Through the collection, sorting, coding and quantitative analysis of water pollution prevention and control policy documents, it was found that the water pollution prevention and control policy system of China is relatively comprehensive. However, there are problems such as the imbalance in the use of policy tools, the weak governance links in the whole process of policy tools and the monotonous structure of the actors of policy tools. In the future, it is necessary to adjust the use proportion of flexible and rigid policy tools, strengthen the supply of the whole-process governance tools of water pollution control policies, promote the diverse participation of water pollution control policy actors, and improve existing policy tools and innovate new ones.

Nutrient assay is essential in the routine oceanographic surveys. The nutrients of seawater are determined on a continuous flow analyzer usually requires artificial seawater or aged low-nutrient natural seawater as the basal solution of standard calibration and the rinsing solution of the assaying system when seawater sample is changed. In this study, the concentrations of components (phosphate, nitrite, nitrate, ammonia nitrogen and silicate) in Sigma, Aladdin and Sinopharm sodium chloride (GR grade) solutions and aged West Pacific seawater were determined. The results showed that the concentrations of nitrite, nitrate, ammonia nitrogen and silicate varied in the three commercial sodium chloride salt solutions except phosphate. In contrast, the concentration of silicate was relatively high and trace amount of nitrite was found while the other three nutrients were not detectable in the aged West Pacific seawater.

The finger piers of Dongjiakou protrude out of the open ocean and are vulnerable to extreme sea state without the protection of breakwater. In this study, the abnormal changes and mechanism of hydrodynamic environment caused by typhoon Lekima captured by ADCP and bathythermograph at the front of Dongjiakou finger pier were analyzed, which could provide important reference for the prediction of berthing environment. It was found that the residual water level showed a "V" symmetric distribution with the maximum water reduction as the symmetry center, and its variation was dominated by wind. When the typhoon was close to Dongjiakou, the lag response time for storm surge was short. When the typhoon center was far away, it was the opposite. The observed residual current was generally less than 20 cm/s during typhoon Lekima, the coastal current had little threat to the port. The forehead swell reached the pier 12 h ahead of the extreme wind speed, and the wave spectrum peak period of forehead swell was in the rolling resonance region of 300 000 ton crude oil carrier and 400 000 ton ore carrier berthed at the jetty which needed to be prevented in advance. Due to the mixing effect of typhoon waves, the bottom water temperature of the observation point rose about 1℃, and the thermocline was destroyed. Even after the typhoon, the bottom water temperature dropped slowly, with a cooling trend of 0.15 ℃/day.

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.

The temporal and spatial distribution characteristics, physical parameters, and fallout forecasts of strong convection under different weather typologies in Shandong peninsula from 2015 to 2020 were analyzed and studied. The results showed that: strong convective weather mainly occurred under five weather situations, namely, low trough, high-altitude cold vortex, northwesterly flow, edge of the sub-tropical height and transverse trough; strong convective weather events mainly concentrated in June-August, and were most likely to occur in the afternoon to the nighttime, and were mostly unevenly distributed; the spatial distribution mainly exhibited four characteristics, namely, western-type, eastern-type, area-wide-type, and local-type, with local-type events being the most frequent. The physical parameter characteristics differed greatly among different weather situation configurations, and the physical parameter characteristics varied greatly among different weather situations. The physical parameters of different weather configurations varied greatly, with the CAPE value and K index of the sub-tropical height edge type being larger than those of other situations, the vertical wind shear SHR6 and the total index TT of the high-altitude cold vortex type being the largest, the CAPE value and K index of the northwesterly flow type being small, and the SI value being positive. Strong convection caused by weak cold fronts and sea-breeze fronts was most likely to occur in the western part of Yantai, and then moved eastward to become weaker, and the eastern type was more likely to happen at night. The eastern type mostly occurred at night, mostly due to the influence of the surface convergence line, and the different positions of the inversion trough also determined the different fallout areas of the strong convection. The region-wide type mainly occurred under the influence of the upper-air cold vortex or the strong trough cold front; the local type corresponded to the edge of the subduction plateau and the northwesterly airflow type, with the surface convergence line as the main triggering system, which had a very good correlation with the sea-land topography and the mountainous topography.

In this paper, a new type of breakwater structure of semi-elliptic breakwater was proposed, and a series of model tests were carried out on two different size semi-elliptic breakwater models. The aim of this study was to analyze the hydraulic characteristics of elliptic arc-shaped structural plane under wave action. The results provided a reference for the construction design of this new type breakwater. The influencing factors of wave force of semi-elliptic breakwater were determined byπtheorem, including wave steepness H/L, relative wave height H/D and scale parameter b/L. Based on the experimental data, the variation characteristics of wave forces on semi-elliptic breakwater with these three factors were analyzed and the stress characteristics of two semi-elliptic breakwater models were compared. The results showed that the wave force increased with the increase of H/D and decreased with the increase of H/L and b/L. The wave force in model 1 was larger, and the horizontal wave force was much larger than the vertical wave force. The wave force in Model 2 was smaller, and the horizontal wave force was close to the vertical wave force.

The International Commission for the Conservation of Atlantic Tuna (ICCAT) determines the annual total allowable catch of bigeye tuna (BET) and implements the fishing quota system according to the basic principles of the two-year historical average catch from 1991 to 1992. By sorting out the standards of quota allocation, suggestions and reports relating to the quota system over the years, and combining the nominal catch of BET of China and the implementation of the quota system, we have dug out four core standards for the development of ICCAT catch quota system, the average historical catch of the 1991-1992, the undeveloped quota not exceeding 15% of the total of the country can be transferred under ICCAT authorization, the overfishing will be penalized for two consecutive management periods, and the quota for the fishing year will be adjusted to the next year. Four suggestions have been put forward to safeguard the interests of China's Atlantic BET fishery, which included improving the quota allocation system of BET; actively participating in the consultation of quota formulation, strengthening the ability of Chinese administrative departments, scientific research departments to participate in international fishery consultation and negotiation, and strengthening the capacity of fulfilling the Atlantic tuna fishery.

The rice-crab coculture model, as a distinctive rice field cultivation and breeding mode in China, relies on mutual benefits between species and complementary utilization of resources in rice field. It plays a significant role in maintaining soil fertility and rice yield, improving nitrogen use efficiency, and controlling pests, diseases, and weeds. In this paper, we mainly summarizes and analyzes the impact of the rice-crab coculture model on rice field ecosystems from five aspects, rice growth, water quality, soil environment, system nitrogen loss and biodiversity. The main conclusion is that the rice-crab coculture model can stabilize or increase rice yield and improve rice quality although its impact on the rice field ecological environment is complex. Our findings provided a reference for the in-depth development and promotion of rice-crab co-culture model.

In coastal areas with layered heterogeneous aquifers, over-exploitation of the groundwater resource has led to serious seawater intrusion. Based on previous physical model tests in coastal areas with layered heterogeneous aquifers, a two-dimensional numerical model of saltwater rising caused by pumping wells was established by applying the scientific modelling package OpenGeoSys to investigate the behavior of seawater intrusion. With the verified model, the heterogeneity of layered heterogeneous aquifer, the thickness of lower permeability aquifer and the influence of pumping well location on critical pumping rate and seawater intrusion were analyzed. The numerical results indicated that the critical pumping rate of the pumping well in heterogeneous aquifers was lower than that in homogeneous aquifers, and the difference of the critical pumping rate between the two types of aquifers was larger for deep wells and wells near the seawater boundary. In layered heterogeneous aquifer, the influence of seawater intrusion was greater when the thickness of low permeability aquifer was thicker. With the increase of pumping rate of pumping wells, the influence of seawater intrusion was more obvious. The horizontal distance between the pumping well and the seawater boundary was closer, the pumping well depth was deeper and the critical pumping rate was lower. Furthermore, the critical pumping rate of the pumping well was more sensitive to the change of the well depth. This research provided scientific theoretical basis for rational exploitation and planning of groundwater resources in coastal areas with layered heterogeneous aquifers.

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.

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.

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.

This study used the cross-section topographic data of the river channel of the lower Yellow River reaches to systematically calculate the inter-annual and seasonal erosion-deposition volume of the main river channel from 1992 to 2011. The major results were presented as follows. From 1992 to 1999, the river channel of the lower Yellow River reaches silted continuously, with a cumulative siltation volume of 1.090 km³. After 2000, the channel shifted from siltation to erosion with a total volume of 1.597 km³ by 2011. On seasonal scale, two-stage pattern of channel evolution was presented. During the flood season from 1992 to 1999, the lower reaches of the Yellow River accumulated 1.471 km³, about 1.4 times of the annual siltation volume. Erosion dominated during dry seasons with a total of 0.473 km³, accounting for 32% of the siltation volume during the flood season. During the flood season from 2000 to 2011, the channel shifted from siltation to erosion with an accumulated volume of 1.148 km³, accounting for 75% of the annual erosion of the lower Yellow River. The erosion flux during dry seasons in 2000-2011 gradually decreased, and the cumulative erosion during the period was 0.381 km³, only 25% of the annual amount. Changes in water and sediment conditions as well as river channel features played critical roles in the evolution process of the river channel in the lower Yellow river reaches. After the implementation of the Xiaolangdi reservoir, the coefficient of sediment incoming decreased significantly, resulting that the river channel turned from siltation to erosion. The river regime coefficient of the lower river channel had dropped overall, and the lower river channel had become more stable.

In the past 40 years, with the continuous development of space technology and sensor technology, ocean remote sensing and fishery have entered the era of big data. Accurate, efficient, and intelligent mining of useful information in these ocean remote sensing and fishery data is a challenging problem that needs to be solved. As a powerful technology emerging in the field of machine learning in recent years, deep learning has achieved good results in many industrial applications. Compared with traditional image information extraction algorithms based on physics or statistics, its advantages are more obvious. As the beginning to expand the application in ocean remote sensing and fishery, in this study, we introduced the key theories and methods of artificial intelligence into ocean remote sensing and fishery. In the direction of ocean remote sensing and fishery, we summarized the use of deep learning in marine environmental parameter inversion, remote sensing image classification and identification, marine phenomenon prediction, population identification, fishery biology and research progresses in fishery forecasts, and prospects for the future development of deep learning in ocean remote sensing and fishery.

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.

In order to investigate the influence of various aquaculture mode on the carbonate system in Sanggou bay, a field survey, including seaweed, shellfish-seaweed, shellfish-fish and shellfish culture, was conducted in the open sea area in Sanggou bay in April, July, October and December, 2019. Temperature, salinity, pH, dissolved oxygen, total alkalinity (TA), dissolved inorganic carbon (DIC) and partial pressure of carbon dioxide (pCO₂) were analyzed. In addition, the air-sea carbon dioxide flux (FCO₂) was calculated. The results showed that the main influencing factors of carbonate system in Sanggou bay algae culture area were algae growth and offshore seawater exchange. The carbonate system in the shellfish culture area was affected by both shellfish respiration and calcification. Because of the FCO₂ in Sanggou bay shellfish culture area was negative and was a CO₂ sink area, the calcification of shellfish in this area could be stronger than respiration. The FCO₂ of Sanggou bay aquaculture area in spring, summer, autumn and winter were -66.60±16.82, -52.44±21.66, -74.00±11.45 and -92.65±34.13 mmol·m^-2·d^-1 respectively, indicating that they were the sink of CO₂. The carbonate system in Sanggou bay was affected by aquaculture action, and there were significant differences among different aquaculture modes.

Nansi lake west plain (Tengxi plain), located in the northwest of Zaozhuang city, Shandong province, is one of the "eight water sources" of Zaozhuang city. In this paper, the monitoring data of 41 groundwater monitoring wells in Tengxi plain from 2011 to 2020 were sorted and calculated, and the dynamic variation trend of groundwater depth and hydrochemical characteristics of Tengxi plain were analyzed. The results showed that the variation of groundwater depth in Tengxi plain was small in the year, generally ranging from 1 to 5 m. The annual variation of groundwater depth showed seasonal fluctuation. The groundwater depth began to increase from March to April in normal and dry years, which was mainly affected by agricultural irrigation. The groundwater depth was smaller in August and September in wet, normal and dry years, which was related to precipitation recharge. Combined with the dynamic method of water level, the groundwater level in Tenxi plain showed a rising trend in the past ten years, with an average rising rate of 0.41 m/a, and the area with the largest rise of groundwater level was in the southwest of Tenxi plain. According to the analysis of Piper diagrams and Gibbs diagram, the groundwater type in Tengxi plain was HCO^-₃·SO^2-₄-Ca²⁺, which was mainly affected by rock weathering. In order to provide some basis for groundwater management in Tengxi plain, this paper responds to the gradual attention of the state to groundwater in recent years.

Based on the hydro-topographical data of the area from 1989 to 2019, the study area is 34369 m². Establishing the DEM model, the paper used Kriging Interpolation and mathematical statistics to quantitatively analyze the mechanism of the erosion and deposition of Lvsi area. The results showed that the subsea terrain of Lvsi Area had turned from deposition to erosion in the past 30 years. The total sediment deposition volume was 54 million cubic meters from 1989 to 2006. The erosion started since 2006, and the total volume of the eroded sediment had been maintained between -5 and -13 million cubic meters. On the one hand, the erosion was attributed to the decreasing of the regional sediment supply due to the declining of the rate of sediment transport in Yangtze basin and along the coastline of northern Jiangsu. On the other hand, the hydrodynamic change of current and tide due to the reclamation projects along the coastline also caused the erosion.

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.

The lower reaches of the Huangshui river was selected as a typical study area, and the hydrochemical composition of shallow groundwater in this area was analyzed employing multivariate statistical analysis, Piper three-line diagram, Gibbs diagram, silicate stability field diagram, ion ratio, calculation of water-soluble composition and reverse hydrogeochemical simulation. The results show that: (1) From the southeast to northwest of the study area, the concentrations of TDS and Cl gradually increased, and the water quality changed from freshwater to salt water. The dominant anion types of groundwater were along HCO₃→HCO₃·Cl→Cl·HCO₃→Cl changes. Na⁺ and Ca²⁺ were the major cation in most regions. (2) The weathering and dissolution of carbonate rock, evaporite and aluminosilicate were the main hydrogeochemical processes in the groundwater in this area. Besides, there was the positive cation alternate adsorption. (3) The results of reverse hydrogeochemical simulation quantitatively verified that the chemical composition of groundwater in the upper and middle reaches of Huangshui river was mainly controlled by rock weathering, the groundwater in the lower reaches was mainly affected by seawater intrusion, and cation exchange occurred under the influence of seawater intrusion.

As an integral part of national territory, islands play an important role in safeguarding maritime rights and interests. However, in recent years, with the development of islands by mankind, the ecological environment of the islands has been destroyed, and the construction of ecological civilization is not optimistic. Therefore, the ecological protection of islands should be strengthened, and the construction of islands’ ecological civilization should be emphasized. China has a large number of islands and the ecological environment is complex. To protect the island’s ecological civilization, it is necessary to establish a complete and effective evaluation index system for the construction of island ecological civilization. This study applied the SAVEE method, took five major aspects of ecological civilization as primary indicators, selected 21 secondary indicators to construct an indicator system, and used the constructed evaluation indicator system to select Shigongliao island and Hailing island for comparative evaluation and analysis. This study put forward countermeasures and suggestions based on the evaluation results. The results showed that the level of ecological civilization construction on Hailing island was significantly higher than that of Shigongliao island, especially in terms of ecological protection and infrastructure construction. The model quantified the level of island ecological civilization construction, consistent with the actual island ecological civilization development status, verified the applicability of the model in the field of island ecological civilization, and provided data support for the ecological civilization construction of Chinese islands.

Infectious hypodermal and hematopoietic necrosis virus (IHHNV) is one of the main viruses affecting shrimp culture. It is generally believed that IHHNV mainly infects organs originating from ectoderm and mesoderm, and does not infect endoderm organs, such as hepatopancreas. In this study, Penaeus vannamei was artificially infected by feeding challenge, and PCR method was used to analyze the infection of IHHNV to different organs such as gill, hepatopancreas, pleopods and muscle. The results showed that the hepatopancreas of P. vannamei was more susceptible to IHHNV, and the positive infection rate was 86.7%. The virus load of IHHNV was 9.8copies/μL DNA. The infection rate of gill was 46.7%. The viral load of gill IHHNV was 3.0copies/μL DNA. Muscles and pleopods had a similar sensitivity to IHHNV, and the infection rate was 13.3%. The viral load of them was 0.8copies/μL and 0.3copies/μL DNA, respectively. Our findings showed that the hepatopancreas can also be infected with IHHNV, and the degree of IHHNV infection was higher compared with other organs. These results provided a new perspective for the study of the mechanism of IHHNV infection. Due to only the small amount of tissue samples were taken, the histopathological examination of the different organs each shrimp was not carried out. Therefore, the study of IHHNV on the different organs of P. vannamei, especially the organs from the endoderm, appreciates further researches in combination with histopathology and other molecular biological tools.

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.

Based on the monthly tide level data and the hydrological synchronous survey data in spring and neap tides in Haitan strait in spring, summer, autumn and winter, characteristics of the tide and tidal current in sea area near Haitan strait were analyzed, and the influencing factors of residual current variation characteristics in Haitan strait were discussed. The results showed that the tide in the sea area near Haitan strait belonged to the regular semi-diurnal tide, and the ebb tide duration was generally slightly longer than the flood tide duration. The tidal current belonged to the regular semi-diurnal tidal current, the shallow water sub tidal current was relatively significant, and the main direction of the ebb and flow tidal current was obvious, which was a reciprocating current. The tidal waves in Haitan strait were standing waves. The seasonal variation of residual current was significantly affected by the coastal current of Fujian and Zhejiang in the East China Sea and monsoon, the residual current was generally southward in winter and northward in summer.

The Mann-Kendall method, moving t-test technique, and wavelet analysis were used to determine the water level mutation point of Dongping Lake, analyze the trend of the annual average water level change, and characterize the daily water level change based on the daily water level sequence of Dongping Lake from 1960 to 2020. The impact of water level change on the spatial evolution of Dongping Lake wetland was discussed. The ecological water level of Dongping Lake was studied using the annual spreading method and the variability range method (RVA) in combination. The results showed that (1) the abrupt change of water level occurred in 1989, and the rise of the water level has caused a significant evolution in the wetland space at the entrance and exit of Dongping Lake; (2) the monthly ecological water levels calculated with the annual spreading methods 1 and 2 before the water level mutation varied between 38.11 and 39.46 m and between 36.94 and 38.24 m, respectively,the monthly protection degree of the ecological water level before the mutation was relatively high, and the water level remained high for a long time after the water level mutation; (3) the ecological water level of Dongping Lake was calculated based on the water level sequence after the abrupt change, the monthly ecological water level calculated by the annual spreading methods 1 and 2 within the year ranged from 39.83 to 40.55 m and from 37.59 to 38.27 m, and the duration of high and low water levels varies greatly in different years; (4) the ecological water level of Dongping Lake calculated with annual spreading method 1 during the year ensured that the wetland will not degrade, at the same time, by combining the underwater elevation of the wetland with the growth period of the reeds, the suitable water level of Dongping Lake can be determined; (5) by setting the dynamic water level of the Dongping Lake flood limit, the Dawen River flood can be resourced and the health of Dongping Lake ecosystem can be guaranteed.

Using Citespace software, 2496 and 135 literatures in the field of marine carbon sequestration searched in Web of Science core collection and CNKI database were analyzed by bibliometrics visualization, and the research development process, research hotspots and frontiers in the field of marine carbon sequestration were analyzed from the aspects of published volume, countries and regions, institutions, periodicals and keywords. The volume of articles published abroad showed a linear growth trend, while the trend of domestic articles did not conform to the linear growth trend. From the perspective of national and regional cooperation, Germany, Canada, Australia and the Netherlands cooperated most closely and had the greatest impact on this field. In terms of the level of institutional scientific research, the United States had the largest volume of papers and the most influential, Woods Hole Oceanog. Inst. had the strongest influence in this field. The main international journals were Global Biogechemical Cycles, Biogeo Sciences and Geophysical Reasearch Letters. The main domestic journals were Scientia Sinica (Terrae), Progress in Fishery Sciences, Marine Sciences and so on. Foreign research hotspots mainly focused on marine carbon sequestration and its role in dealing with climate change, the frontier of research was the impact of global storage of blue carbon on climate change. Domestic research hotspots were the mechanism of marine carbon sequestration and ocean acidification, and the research frontier was roughly the same as abroad.

The jumbo flying squid (Dosidicus gigas) is one of the largest cephalopods with high economical values, which is an important fishing target by Chinese squid-jigging fisheries. According to the sea surface temperature (SST) and sea surface height anomaly (SSHA) data obtained from 8°-20°S,95°-75°W off Peru from Sept, to Dec. during a period from 2006 to 2015, the weighted habitat suitability index model (HSI) was developed, and the optimal HSI model was selected and validated. Furthermore, the optimal HSI model was used to predict the habitat suitability for D. gigas, the differences of spatial and temporal distribution in potential habitat of D. gigas in the years with El Niño events at different intensity were further examined. The fisheries data from Sept. to Dec., 2015, were used to validate the optimal model, and the model outputs exhibited a good prediction performance. The environmental conditions combined with spatial and temporal variations of potential habitats of D. gigas were compared between year 2006 with weak El Niño event and year 2015 with very strong El Niño event. The results showed that relative to year 2015 with strong El Niño event, year 2006 with weak El Niño event experienced colder SST, lower SSH, and wider range of suitable SST and SSH. The environments in 2006 were favorable for squid survival, leading to a significant increase in suitable habitat in 2006. Our findings suggested that the impacts of El Niño events at different intensity on habitat suitability of D. gigas are dramatically different. The studies on evaluating climate variability on squid species in the future should consider the characteristics each anomalous climatic event.

A prefabricated artificial reef connected with Ruban lock was designed in view of the large size and low transportation efficiency of the cast-in-place concrete artificial reef. The small size rod could be assembled into large empty space bodies by mortise and tenon, which could effectively save transportation and delivery costs. The stability calculation was made according to the sea conditions of an artificial reef area near Rizhao, Shandong province. The results showed that under the joint action of waves and flow, the maximum force was 7.252 kN and the maximum moment of action was 8.702 kN·m. The anti-slip safety coefficient of the reef was 3.4 and the anti-overturning safety coefficient of the reef was 4.5, which met the reef stability conditions, and the reef would not slip and overturn in this area. This study provided an important reference value for designing prefabricated artificial reefs suitable for the environmental characteristics of China's offshore waters.

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.

The development and utilization of the ocean in China cannot be separated from its effective management by the main body of marine administration. However, the central government and local governments are still not fully cooperative. In this paper, we made a game analysis of marine administrative subjects in marine spatial planning. First, we defined the main body of marine management in current system. Second, against the perspective of marine space planning, we analyzed the main body of marine administration and its centralized and decentralized management system by game. The results showed that the marine administration in China can adopt the approach of setting up marine spatial planning. Centralized management system is appropriate. In other words, the central government may directly participate in the unified management of marine spatial planning in a straight and vertical way.

In order to understand the potential of carbon sink fishery of Tianjin, the fishery production and carbon removal of carbon sink organisms identified from 2013 to 2022 were calculated. The results showed that the average yield of fishery output of Tianjin is 335300 tons in this period, of which the average annual freshwater aquaculture output is 271200 tons, accounting for 80.89% of the total. The overall carbon removal from fishery was stable at first, then decreased, and finally stabilized. The average annual carbon removal was 16500 tons. The average annual carbon removal of freshwater aquaculture was 10900 tons, accounting for 66.42%. The carbon removal of silver carp was the highest, 4900 tons. The average annual carbon removal of freshwater fishing industry was 900 tons, accounting for 5.39%. There was no seawater carbon sink organism was cultured, much less the carbon sink varieties of shellfish and algae. The carbon removal amount of mariculture was not discussed. The average annual carbon removal of seawater fishing industry was 4700 tons, accounting for 28.19% of the total. The rice-fish integrated farming is developing rapidly. Tianjin may take this opportunity to improve further the carbon sink capacity by practicing of carbon sink fishery strategy, thus improving the feeding efficiency, leveraging the carbon sink function of natural fisheries and optimizing aquaculture structures. In this way, Tianjin may respond well the double carbon strategy of China, and contribute significantly to carbon neutrality targeting.

As China's marine economy accounts for an increasing proportion of the national economy,the protection of marine resources and the environment has become more important. It is particularly important to realize the coordinated development of marine economy and resources and environment. This paper built a evaluation index system of marine economy and resource environment, established the evaluation model of the coupling coordination degree of marine economy and resource environment, evaluated the coordinated development level of marine economy and resource environment in coastal provinces, and analyzed the temporal and spatial distribution characteristics of the coordinated development of China′s marine economy and resource environment. The research results showed that the coupling degree of marine economy and resource environment in 11 coastal provinces from 2007 to 2016 was developing towards a good coupling. The spatial distribution of marine economy and resource-environment coupling coordination degree was obviously different, and provinces with similar coupling coordination degrees had a certain clustering phenomenon. From north to south, they are: medium coordination type (Liaoning, Hebei) and high coordination type (Jiangsu, Zhejiang, Fujian, Shanghai, Guangdong).