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.

Since the 21^st century, the coastline of Laizhou Bay has changed significantly due to coastal reclamation activities such as port dam construction and aquaculture dikes, which have caused the change of the hydrodynamic environment of the bay. In order to investigate the response of the tidal prism and water exchange capacity of Laizhou Bay to its coastline change during the past 20 years, the influence of the coastline change on tidal prism and water exchange capacity was analyzed with two-dimensional flow and advection-diffusion models for the two typical years, 2000 and 2020. The results showed that from 2000 to 2020, aquaculture dikes have caused an increase in the potential energy of tidal waves, and the maximum possible tidal range of Laizhou Bay also shows an increasing trend. The head of the bay between Weifang Port and Guangli Port increased significantly with the maximum increase of 8 cm. The spring tidal prism was decreased by 2.91%, the neap tidal prism by 1.42% and the mean tidal prism by 2.33%, and decreased bay area was the main reason for the decrease of tidal prism. The decrease in the sea area of the bay has led to a reduction in its self-cleaning capacity and water exchange, increasing the bay half-life time by 15 days. As for the local water exchange capacity, the water exchange capacity in the western part of the bay was decreased by port dam construction and a deposition trend of the Yellow River Estuary, resulting in an increase of half-life time in the western part of the bay by 40 d.

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.

Disasters such as strong winds and huge waves caused by typhoons have a significant impact on the offshore area of Shandong peninsula. In this paper, by using the third-generation wave model SWAN, the driving field of the model was formed by ERA5 background wind field and the typhoon model wind field nested with Takahashi and Fujita. t formulas. The typhoon waves in the process of No. 9 typhoon "LIKEMA" in 2019 were simulated. According to the simulation results, the distribution of effective wave height, average period and wave age of typhoon wave was analyzed numerically, and the spatial distribution characteristics of typhoon wave during typhoon "LIKEMA" were preliminarily explored, which provided technical support for typhoon wave warning, disaster prevention and mitigation in Shandong province. The research results have certain scientific significance and application value.

In this paper, the species, distribution area and biomass per unit area of macroalgae in the subtidal zone of Gouqi Island, Zhejiang Province, were investigated through acoustic side scanning and SCUBA diving. At the same time, the organic carbon content of different macroalgae was detected, and based on the biomass per unit area, the biomass and carbon sequestration capacity of the subtidal algal field in Gouqi Island were estimated. The results showed that the distribution area of the subtidal zone algal field is about 22.33 hectares in Gouqi Island, and there were 19 species of 3 phyla of macroalgae are distributed. The content of organic carbon in different species ranged from 29.11% to 36.85%. Brown algae contain a special blue light effect and have the highest average organic carbon content (32.62%) which was followed by Chlorophyta (31.82%) and Chlorophyta (29.39%). The macroalgal carbon sequestration capacity per unit area was estimated to be 176.15g·C/m², and the total carbon sequestration in the sea area is about 38.28 tons, equivalent to about 129.07 tons of CO₂ emission reduction. The results of this study can accumulate basic data for the study of carbon sequestration capacity of macroalgae farms in coastal waters, and also provided a scientific basis for the study of negative emission reduction path in the ocean.

Under the action of waves and currents, offshore wind power foundations may experience local erosion, resulting in an increase in the length of the foundation cantilever, which seriously affects the stability and safety of the foundation. To investigate the local erosion characteristics of offshore wind power tripod foundations under the combined action of waves and currents, local erosion tests were conducted on tripod foundations with different installation angles in a wave current tank. The characteristics of local erosion depth, influencing factors, and the morphology of erosion pits were studied. The research results indicated that under the action of individual waves, the central column provided a certain protective effect on downstream piles, weakening the development of erosion. When waves and currents acted together, waves provided drag force on the bottom bed, while water flow provided sediment transport force, resulting in a significant increase in scouring depth. When the installation angle was 30°, the water blocking effect on the double pile side of the tripod was greater, and some water flow was directed towards the single pile side, resulting in an increase in the scouring depth. As the flow velocity, wave height, and KC increasing, the depth of erosion around the foundation gradually increased. An empirical formula using KC to predict the equilibrium scour depth had been proposed, which could accurately predict the equilibrium scour depth of local scour on a tripod foundation under wave action and wave current combined action.

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.

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.

Seawalls play an important role in preventing coastal areas from storm surges, but the seabed in front of seawalls usually suffers serious erosion after their construction, which would threaten the safety of seawalls. To analysis the scour problem in Gudong Seawall, we recovered the scouring process according to the water depth during the past 20 years, discussed the scour mechanism and calculated the maximum scouring depth. The results showed that: (1) Gudong seawall was under the erosion background in the abandoned sub-lobes of the underwater delta of the Yellow River Delta, and the seabed within 500 m offshore suffered more severe erosion, which was called background scouring and toe scouring respectively in this manuscript. The background water depth had deepened from 2-3 m in 2000 to the present depth of 6 m, and the maximum water depth at the toe of the seawall had exceeded 7 m. (2) Background scouring was mainly caused by the diversion of the river course and the reduction of sediment into the sea. Waves were the main driving factor for seabed scouring. Seawall toe scouring was caused by complex hydrodynamic processes in front of the Gudong Seawall, such as wave reflections, wave breaking, turbulence, coastal current, offshore current, etc. (3) It was predicted that the maximum scouring depth for background erosion in the Gudong Sea area was 7 m, whilst for toe scouring was 1.7-2.5 m, so the maximum water depth in front of the Gudong seawall was 8.7-9.5 m.

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.

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.

It is of a great significance for the utilization and protection of Antarctic krill to study the distribution of and predict the suitable habitat of Antarctic krill in the Cosmonaut Sea. Using krill distribution data from the Krillbase and data from the global ocean data assimilation reanalysis system (GLORYS), the spatial distribution characteristics of krill in Astronaut Sea and the characteristics of sea surface temperature, sea surface salinity, chlorophyll and sea ice in krill collection points were analyzed. At last, the suitable habitat of Antarctic krill in Astronaut Sea was obtained. Results showed that the density of krill was high in the south and low in the north, and high in the west and low in the east of the Astronaut Sea. The high density was concentrated in the coastal area to the west of Enderby, and mostly located in the south of 65°S. Results showed that Antarctic krill prefers to habitat sea surface temperature of 271.4K-271.9K, salinity of 33.9-34.1, chlorophyll of 0.28 mg·m^-3~0.36 mg·m^-3, sea ice concentration of 0.67-0.81. The suitable habitat of the Antarctic krill distributed in the south of 65°S, and was paralleled to the coastline.

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.

In this study, according to the human-computer interactive interpretation and GIS analysis, the distribution of coastal wetlands in Shantou city was obtained since 1980s by analyzing the multi-temporal landsat remote sensing image data. According to wetland classification system, Shantou coastal wetland was divided into natural wetlands and constructed wetlands (first classification), including 9 types. They were shallow sea areas, rivers, lakes, beaches/coastal, mangroves forest, reservoirs/ponds, water fields, salterns and aquaculture ponds (secondary classification). The variation characteristics and the influencing factors of coastal wetlands in Shantou city were analyzed by dynamic degrees of single wetland type, wetland transition matrix and correlation analysis. The results showed that: from 1982 to 2020, the coastal wetlands in whole area were increased slightly by 19.08 km². The natural wetlands shrank significantly with a total area loss of 51.18 km², while the constructed wetlands expanded significantly, with a total area increase of 70.26 km². The main driving force of the change came from a series of human activities such as tideland reclamation, land reclamation, sea reclamation and river aquaculture, construction of fishing port wharf and water conservancy facilities in the rapid urbanization process of Shantou city. Secondly, the changes of sediment discharge and sea level rise of the major rivers also played a certain role in the wetland change.

To understand Yangjiang, Guangdong nearshore sea surface water content and potential ecological risk of heavy metals, samples surface waters were collected at 14 stations. The content distribution characteristics of 7 kinds of heavy metals were analyzed in surface waters including Cr, Cu, Zn, Cd, Pb, As, and Hg. The Hakanson method was adopted to evaluate their ecological risk index and potential ecological harm. The results showed that the average concentrations of heavy metals Cr, Cu, Zn, Cd, Pb, As and Hg in the surface waters off Yangjiang were 1.10 μg/L, 5.25 μg/L, 9.91 μg/L, 0.027 μg/L, 0.945 μg/L, 1.06 μg/L and 0.027 μg/L, respectively. Among them, Cr, Zn, Cd, Pb, As and Hg met the quality standards for class I seawater, while Cu met the quality standards for class II seawater. There was a strong correlation among the 7 heavy metals, and each heavy metal also had a certain correlation with different environmental parameters. Based on the analysis of the potential ecological risk index, the average value of RI was calculated to be 6.59, which was a slight ecological hazard and the overall level of cleanliness.

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.

With the bibliometric method and the help of the literature analysis function of CiteSpace software, in this study, we took 662 literatures using key word combination of Acipenser sinensis and protection included in China National Knowledge Network (CNKI) as the data source, and collated and analyzed their annual distribution, publishing institutions and cutting-edge trends. The results showed that the academic research results on Acipenser sinensis showed a general trend of fluctuating upward in recent years. The number of papers published in the core journals of related literature was small. Fisheries research institutes and universities were the main publishing institutions. Current researched focus on the hot points such as the protection of the Yangtze River estuary and Yangtze River. The academic protection of Acipenser sinensis in China needs to be further studied, and multi-disciplinary interaction and communication should be carried out to expand research methods, so as to provide new ideas for the future research and protection of Acipenser sinensis.

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.

Based on the synchronized data of suspended sediment and sea current, this paper analyzed the suspended sediment transport mechanism and the main mechanical control factors in study areas using sediment flux mechanism decomposition method. The sedimentary dynamic environment was divided into different zones using Flemming triangle diagram method on the basis of the distribution characteristics of the surface sediments in the study area. The results showed that the Lagrangian advection transport was the main governing factor in transport of suspended sediment and the vertical net circulation came second. And the transport direction of the tidal average single-width net sediment transport was in SW, which corresponds to the direction of the remaining flow in the study area. The average single tidal-width sediment transport at the outer station showed a decreasing trend from northeast to southwest, while the inner station showed the opposite, the average single tidal-width sediment transport increased from the northeast to the southwest. It was indicated that there was nearshore erosion or river sand transport. Observation showed that the study area was covered largely by sand and the local area was silty sand, gravel sand, and sandy gravel, with a small number of shells or coral reefs. The dynamic environment could be divided into zone S, zone A and zone B. The motion of surface sediments were three types: moving, jumping, and overhanging. The jumping was the main route of the surface sediment. The surface sediments had a lower content of transitional components in sediments and the increase of suspended-transition components with the hydrodynamic environment became weaker.

Towards the problems of color distortion of the marine ranching observation video and low accuracy of traditional fish identification methods, a marine ranching fish identification and classification method based on Faster-RCNN was proposed. SDI (Serial Digital Interface) signal color compensation system was used first to improve the poor video quality caused by the particularity and complexity of the marine environments, and then the optimized video was applied to produce data sets with diverse qualities. The Faster-RCNN works following a deep learning model with the feature extraction network and region proposal network (RPN) optimized and used to identify and classify marine ranching fish. The tentative experimental results showed that the mean average precision (mAP) of this method reached 81.63%, significantly improved the accuracy of recognition compared with traditional machine learning target detection algorithms.

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.

The relations about BOD₅, DO and COD were researched, which were acquired from water of marine outfalls near a coastal city, south China. The results indicated that preferable one-variable linearity existed between COD and BOD₅, but relatively weak linearity between BOD₅ and DO, as weakly between DO and COD. A binary linear function was established to express the relation about the three parameters, with a better linear determination coefficient and a larger F-test value. When COD ≥ 100mg/L, the fitting degree of the binary linear function was better than the one-variable linear function between COD and BOD₅. Monitoring data of BOD₅, DO and COD from water of marine outfalls of this city in 2015 year was used to verify the binary linear function. The relative error between COD values fitted by the binary linear function and COD values detected in a lab, was less than 25%, which accorded with the precession of quality control criterion, and verified the binary linear function reliable.

Tidal data reflects changes in coastal sea level, and plays a very important role in various fields. The lack of tidal data brings inconvenience to the use of tide level data. Based on the tidal data of the Chongwu and Jinjiang ocean stations in 2017, this paper proposed a method of filling missing data based on the LSTM model (long short-term memory neural network model). Compared with traditional interpolation methods such as linear interpolation and spline interpolation, the LSTM method had stable performance, high accuracy and easy implementation. Especially when the lack of measurement time was long, the LSTM method was obviously better than the traditional interpolation method. At the same time, this method was also suitable for filling other missing data including water temperature.

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.

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.

Vulnerability represents a certain state of a system, and vulnerability analysis is an inevitable requirement for each system to respond to global changes and a necessary path to practice sustainable development. In order to make the fishery system better respond to external changes and maintain the sustainability of fishery resources and its economy, in this paper, we studied the vulnerability theories and methods and their application research progresses in fishery. Through the collation of relevant literature, it is found that vulnerability research has been applied and developed in multiple disciplines and fields, and the theoretical system such as conceptual methods is rich, but there is no unified standard ye. Fishery vulnerability research is still in its infancy, mainly about the vulnerability analysis of species, ecosystem, and coupled systems, with a relatively mature concept definition and a variety of evaluation methods. The literature mainly focuses on the quantitative research on the vulnerability of the coupled system and the qualitative and semi-quantitative research on the vulnerability of the species. Only a small amount of literatures studies the vulnerability of the ecosystem. The studies have been conducted on different scales and angles around inland, marine, and special fishery (especially coral reef fishery). Among them, there are more studies on marine fishery, and less on inland fishery, all of which focus on the vulnerability to climate change. The findings of this study can provide a reference for fishery vulnerability assessment in China.

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.

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.

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.

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.

A field survey was carried out in Qingdao coastal area in spring (May) and summer (August) in 2019. Variation characteristics of phytoplankton community structure in coastal areas of Qingdao and their relationship with environment were studied, and the reasons of variation were analyzed based on the historical data. The results showed that a total of 109 taxa which belong to 52 genera of 4 phyla were identified in spring and summer. Compared with the historical data, the survey results of the phytoplankton community in costal waters of Qingdao showed obvious species succession, and the dominance of predominant species, Skeletonema costatum, remarkably decreased. The cell abundance of phytoplankton in Jiaozhou Bay was significantly higher than that in Laoshan Bay, and the diversity index of Laoshan Bay was higher than that in Jiaozhou Bay in summer. Correlation analysis and redundancy analysis of phytoplankton community structure and environmental factors showed that the phytoplankton cell abundance showed a positive correlation with phosphate and DIN (P<0.01), the phytoplankton cell abundance showed a positive correlation with COD (P<0.05) while the phytoplankton cell abundance showed a negative correlation with salinity and pH (P<0.05).

The emission trading system is an important measure for the government to use market mechanisms to control environmental pollution. The current operating mechanism of emissions trading under government control has problems such as insufficient trading market activity, high corporate transaction costs and weak monitoring of emissions trading. The PPP mode (Public-Private Partnership) is an institutional innovation that the government and social capital cooperate to solve the construction of public infrastructure. The introduction of the PPP mode into the operating mechanism of emissions trading has certain feasibility from the perspective of system, technology and organization. It can be substantively embedded in the licensing management, trading and verification, and evaluation of emissions trading. In order to ensure the smooth operation of the PPP mode, the government should also fully play the role of regulating the emission trading and the cooperation between the government and social capital by way of revising and enacting relevant laws and regulations, building a complete guarantee system. Follow the rules above, the construction of cooperation of the emission trading operation mechanism between the government and social capital can be realized.

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.

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.

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.

In order to further cultivate marine industry, promote the development of marine economy and build a powerful marine power, in this paper, we analyzed the current situation of Chinese marine industrial structure and its developmental prospects through deviation share, industrial structure deviation and grey correlation analyses. The results showed that (1) Chinse marine industry presents the "three two one" structure model, the development of marine secondary industry is slow, lagging behind the development of the second industry of national economy, and is in a weak position; (2) the employment structure and output structure of marine industry are asymmetric, and the industrial structure benefits are low; (3) the subdivision industry in the three marine industries needs to be further optimized and upgraded. We suggested to improve the structural benefit of the primary industry, enhance the competitiveness of the secondary industry and consolidate the dominant position of the tertiary industry.

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.

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.

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.