In the process of floating objects drifting at sea, the underwater part is mainly affected by surface currents and waves, while the floating part is mainly affected by wind. The results showed that the influence of surface current and wind on the direction and trajectory of floating objects was the main factor, while the influence of waves was small and negligible. In this paper, the FVCOM model was used to numerically predict the surface flow field of the Taiwan Strait, and the FVCOM simulation flow field and ERA5 wind field were used as the background field of drifting buoy movement. At the same time, the influence of wave force on drifting buoy movement was ignored, and the lagrangian particle tracking method was used to simulate the movement track of drifting buoy. The wind-induced drift coefficient was used to correct the trajectory of the simulated drifting buoy. The results showed that when the wind-induced drift coefficient was 0.04, the simulated trajectory of drifting buoy fitted well with the measured trajectory. The simulation error was 1.74 km in 6 hours, 5.78 km in 12 hours, 7.29 km in 24 hours, 0.66 km in 48 hours and 9.54 km in 72 hours. The error of 96 hours was 29.97 km.

The Optimum Interpolation Sea Surface Temperature data (OISST V2) was tested by using the anchor buoy data in the Bohai Sea area from two aspects of data reproducibility and statistical eigenvalue calculation. OISST V2 data has high reliability.The TOISST V2 data was used to study the long-term variation trend of surface sea temperature in the Bohai Sea from 1981 to 2021. The results showed that the whole Bohai Sea area had a warming trend. The annual average variation rate of SST in 41 years was 0.028℃/a, the maximum annual average variation rate appeared in the south of the Bohai Bay, and the minimum annual average variation rate appeared in the east of Liaodong Bay. In winter, the average warming trend of the Bohai Sea was 0.005 1℃/a. The central part showed a warming trend, while the coastal Bohai Bay, Laizhou Bay and Liaodong Bay showed a cooling trend. In summer; the Bohai Sea had a warming trend, with an average warming rate of 0.011℃/a. EOF decomposition of OISST V2 sea surface temperature anomaly data was used to analyze the spatiotemporal characteristics of SST in the Bohai Sea. The main modes of its spatial distribution had overall consistency, and the significant period of time coefficient was annual period.

Wave breaking can induce enhanced turbulent mixing at the ocean surface layer, but whether typhoon enhances wave-induced mixing and how it affects the thermocline below the mixing layer remain unclear. In this paper, taking typhoon Nepartak as the research object, based on the coupled ocean-atmosphere-wave-sediment transport (COAWST) model, the effects of turbulent mixing caused by wave breaking on the depth, thickness, and strength of the thermocline in the northwest Pacific were studied. The results showed that: during typhoon Nepartak, the wave-induced mixing significantly strengthened the turbulent mixing below 100m, resulting in the deepening of the mixing layer, the reduction of SST, the obvious deepening of the upper boundary depth of the thermocline, the small change of the lower boundary depth, the thinning of the thermocline thickness and the slight strengthening of the intensity. In addition, the introduction of wave-induced mixing could significantly improve the simulation effect of COAWST model on SST during typhoon.

Microeukaryotes including algae, protozoa and fungi exhibit high abundance, wide distribution and high diversity, which play crucial roles in marine ecosystems. In September 2020, we collected 16 samples from six stations in the typical raft aquaculture area of Gouqi Island, the East China Sea. Microeukaryote communities were analyzed using 18S rDNA high-throughput sequencing to compare their spatial distribution across three habitats including surface seawater, bottom seawater and sediment samples. Our results showed that diatom and dinoflagellates dominate the phytoplankton community, and ciliates and Noctiluca dominate the zooplankton community. As for microeukaryotes, the dominant species of microeukaryotes were Cerataulina pelagica, Noctiluca scintillans, Alexandrium tamarense, Sargassum fusiforme and Alexandrium catenella. A significant difference among microeukaryote communities was observed between seawater and sediment samples. The microeukaryote communities in sediment samples showed a higher Shannon and evenness diversity than those in seawater samples. Compared with bottom seawater, microeukaryote communities in surface seawater exhibited higher Shannon and evenness diversities but lower species abundance. Redundancy analysis domonstrated that the diversity indices and dominant species distribution in surface seawater were strongly influenced by temperature, salinity and Chl a concentration. At station WRC, higher abundances of diatoms and Phaeophyceae were positively correlated with Chl a concentration. Overall, our findings provided baseline data for researches on the community change and ecological function of microeukaryotes in aquaculture areas of East China Sea.

Based on the continuous observation data obtained by the seabed foundation in the field, this paper systematically analyzed the tidal characteristics of the Qinhuangdao sea area in the summer of 2017. The results showed that the diurnal tides (K₁ and O₁) dominated the sea area and the K₁ tide was the most significant, with average amplitude of 0.28 m. The semidiurnal tides (M₂ and S₂) had smaller amplitudes, and the M₄ tide was more obvious in the shallow water tide. In terms of spatial distribution, except for the small variation of O₁ tide, the fluctuation range of other tides was large. The influence of semi-diurnal tide was increasing from north to south, and the amplitude increased by about 4 to 5 times when the tide wave propagated to the south of the sea area. The tidal type was all-day tide, which was affected by the M₂ tide. The northern part of the sea area was a regular diurnal tide and the southern part was an irregular diurnal tide. The tidal range was small, and the average tidal range of the three stations was less than 0.5 m. The D1 station in the north of the sea area was close to the non-tidal point, and the average tidal range was close to 0. The maximum possible tidal range was about 2 m, indicating that the sea area was a weak tidal zone. The duration of the flood and ebb tides varied greatly, and the flood tide was dominant on the whole. The neap tide period had certain particularity, and the duration of the rising and ebb tides was different from the overall characteristics.

This study conducts an analysis of the measured wind direction and speed data collected from automatic weather stations in the Xiangshan Port area, spanning 2011 to 2020. The aim is to understand the characteristics of disastrous strong winds across different port areas, with a particular focus on the triggering weather systems, the impact intensity, and the duration of each strong wind event. The analysis incorporated surface and upper-air weather maps. The results suggested that: (1) The inner and outer regions of Xiangshan Port witnessed an annual average of 105.5 hours and 330.0 hours of strong winds, respectively. June and August recorded the least and most occurrences of strong winds, respectively. On a daily basis, strong winds were most probable in the inner port during the afternoon and in the outer port around the evening. (2) The prevailing wind directions for strong winds in both the inner and outer ports were between WNW and NNW. The terrain affected the inner port, with a secondary prevailing wind direction being NE—E. The outer port, frequently influenced by the edge of the subtropical high, exhibited S—SSW as its secondary prevailing wind direction. (3) The average duration of strong wind processed resulting from strong convection, high-pressure edge, low-pressure (vortex) inverted trough, cold air, and typhoon in Xiangshan Port sequentially increases. The weather systems most likely triggering strong winds in the outer and inner ports were low-pressure (vortex), inverted troughs and cold air, respectively. (4) Depending on the influencing weather systems, the wind strength typically exhibited a pattern: outer port surpassing the inner port, which in turn surpassed the surrounding land. The average duration of strong wind events in the outer port could be 2-4 times longer than in the inner port. Nevertheless, in terms of the intensity and frequency of strong convection winds, the inner port significantly surpassed the outer port and surrounding land.

The response of beaches to typhoons and their post-typhoon recovery processes have long been a focal point in coastal research worldwide. Based on three months of continuous field observations at Chu Island beach in Weihai, this study comparatively analyzed the morphological changes of the beach under the influence of Typhoon Lekima and its subsequent recovery. The results indicated that Chu Island beach experienced widespread erosion during the typhoon, characterized by slight accretion in the backshore, severe erosion in the high-to-mid intertidal zone of the foreshore, and overall beach face downcutting. Notably, the northeastern profiles exhibited more pronounced erosion. The severely eroded profiles of Chu Island beach recovered rapidly within one month after the typhoon. However, geomorphological adjustments and sediment dynamics varied across different sections of the beach. The overall trend showed accretion in the upper beach and erosion in the lower beach, with the southwestern section recovering relatively slower and the northeastern section recovering faster.

Jelesniansk is used as typhoon model to simulate wind field, and CCMP wind field is superimposed to reconstruct wind field. The wind field structure characteristics during typhoon Herb were analyzed by reconstructing the wind field. The three-dimensional ocean numerical model FVCOM was used to simulate the astronomical tide and storm surge in Xiamen sea area. Through error comparison, it is found that the simulated values were in good agreement with the measured ones. It showed that the simulation results could well reproduce the characteristics of storm surge in Xiamen sea area. Based on the simulation results, the spatiotemporal variation characteristics of three-dimensional sea current and water level during typhoon were analyzed. It was found that the temporal and spatial variation of the typhoon wind field was the main reason for the change of the flow direction and velocity of the storm surge. The distribution of increasing water was mainly affected by wind field, wind-generated current and shoreline characteristics. The increasing water area was mainly concentrated in the typhoon center and the area where the typhoon onshore wind acts for a long time. Water reduction often occurred in areas where the offshore wind acted for a long time.

The south coast of the Hangzhou Bay had significant ecological functions such as climate regulation, carbon sequestration and sink enhancement, water purification and so on. However, the temporal and spatial distribution pattern of wetland vegetations had changed in recent years, especially the trend was more obvious after the construction of the 11th seawall in 2010, which had a certain impact on the ecological function of the wetland. Thus, our objective was to explore the change and influencing factors of the salt marsh wetland vegetations outside the 11th seawall after its construction. We principally used six remote sensing images from 2010 to 2020 in this paper, we also created and used DSPI formula on the basis of NDVI index to improve the classification accuracy of vegetation, and ENVI expert knowledge decision tree method was used for interpretation and analysis. The results implied that since the construction of the 11th seawall, the vegetation of the salt marsh outside the seawall had been replaced by the distribution pattern of Phragmites australis (high intertidal zone)-Spartina alterniflora (middle and high intertidal zone)-Scirpus mariqueter (middle and low intertidal zone), which was originally dominated by Scirpus mariqueter. The comprehensive analysis showed that the major influencing factors of vegetation distribution pattern change in the study area were the environmental factors, the biological factors and the human activities, in which the influencing factors would gradually change from environmental stress to biological competition with the increase of wetland elevation, while human activities would directly interfere with the natural succession of wetland vegetation.

A new round of shoreline survey led by Ministry of Natural Resources has established the legal and managemental basis for the separation of land and sea, which takes the average spring tide high tide line as the boundary between land and sea. Such adjustment of coastline position has made the sea area certificate landside and the land certificate seaside more prominent, resulting in a special situation of regional spatial planning and use control. Based on sorting out these two types of problems, and in combination with relevant research and policies, in this paper, we put forward corresponding policy guidance and work suggestions according to the actual situation. We suggested to (1) accelerate the promotion of the statutory coastline and establish the annual coastline change investigation system and the five-year survey mechanism; (2) guide and control the development and protection of two sides with spatial planning; (3) define the policy of land certificate renewal for reclamation in stock; and (4) issue special documents to clarify the regional management policy of land certificate in the sea, strictly control the new reclamation, ease the ownership contradiction by new ways such as three-dimensional confirmation of rights, and explore the establishment of a voluntary exit mechanism of land certificate on the sea side. On the premise of obtaining land use approval procedures, stock land should be approved once non construction land was determined by the third national land survey, and construction land should be managed once the construction land was determined. Actively exploring the mechanism underlining the linkage of disposal of stock reclamation with the total amount of new construction land indicators in the region, and implementing the requirements of development concession distance and the lower limit control of ecological space reservation were highly appreciated.

Based on major element analysis, combined with correlation analysis and R factor analysis, paleoenvironment evolution records of Core S01-10 in the central Okinawa Trough since late Pleistocene had been obtained. Major elements data indicated that the content of major element oxides showed obvious three depositional units on the Millennium scale: Unit A1(400~143 cm) was formed from Late Deglaciation to Early Holocene, during which the terrigenous sediments mainly came from the Yellow River and a small admixture from the Yangtze River, while the contribution of Taiwan materials could be ignored. Unit A2(143~105 cm) was formed in Early Holocene, and the dominant provenance was still the Yellow River. The contribution of Taiwan materials was relatively increased while the influence of the Yangtze River decreased. Unit A3 (105~0 cm) was formed from Early Holocene to Middle Holocene. The dominant provenance was the mixture of the Yellow River and Taiwan, and the contribution of the Yangtze River material could be ignored. The results of correlation analysis and R factor analysis of major elements showed that the content of typical element oxides was mainly affected by the input of terrigenous sediments, while the effects of marine biologic deposition, hydrothermal activity and volcanic events were minor. Sea level fluctuation and intensity variation of the East Asian monsoon were the main controlling factors of material provenance in the central Okinawa Trough. Based on the test and analysis of Core S01-10 in the central Okinawa Trough, this paper provides a valuable reference for studying the evolution history of terrigenous sediment input in the region since the late Pleistocene.

The fusion detection using the multi-dimensional features of sea surface scattered echoes is one of the effective ways to solve weak target detection problem. Based on the differences of X-band radar sea surface echo features such as the time domain, frequency domain and time-frequency domain in target detection performance, in order to improve the target detection accuracy and achieve the secondary detection of sea surface targets by using the base detector and fusion detector, this paper proposed an open target detection algorithm framework for the multi-dimensional feature decision fusion of sea surface echoes. Firstly, this paper converted the maritime target detection problem into a feature-based binary classification problem and utilized the feature quantities in the time domain, frequency domain and time-frequency domain of the radar echo data for target detection based on the K-Nearest Neighbor (KNN) algorithm, respectively. A multi-dimensional decision probability space was constructed and analyzed based on the multiple detection probabilities of different echo sample data. Then, the KNN was optimized by calculating the target and sea clutter classification thresholds with different false alarm probabilities (P_fa) in order to achieve controllable false alarm of maritime target detection. Further, the optimized KNN was used as a fusion detector to obtain a multi-feature decision fusion detection algorithm. Finally, the experiments on McMaster's IPIX radar real measurement dataset showed that the detection algorithm in this paper could obtain a detection probability of 0.87 when the signal to clutter ratio (SCR) was 0 dB and the P_fa was 10^-3. The detection performance was better than other feature-based detection algorithms. It could better satisfy the target detection requirements under the radar short-time observation and low SCR sea conditions.

In order to recognize the composition of fish and species diversity of the Dianshan Lake, its fishery resources were sampled from 2020 to 2021 using fixed triple gillnets to analyze fish composition, fish community structure and diversity from the perspective of gillnets with different mesh sizes. The results showed that only 38 fish species are collected, which belong to 30 genera, 6 orders and 8 families. Of which, 73.7% were Cyprinidae with small fish accounted for 52.5%. Coilia nasus, Acheilognathus macropterus and Carassius auratus predominated the catch. The number of species and the number of catch in five mesh gillnets decreased with the increase of mesh size, and there were some similarities in their dominant species, Coilia nasus and Carasslus auratus. Hypophthalmichthys molitrix and Cyprinus carpio were dominant in large mesh gillnets. The Shannon Wiener diversity index (H′), Pielou evenness index (J′), Margale richness index (D) and Simpson dominance index (C) trended to decrease gradually with the increase of gillnet mesh size. Cluster analysis (CA) and Non-metric multidimensional scaling (NMDS) divided the fish community structure into small mesh (20 mm and 40 mm) group (group I) and large mesh (60mm, 80mm and 100mm) group (group II). Coilia nasus, Acheilognathus macropterus and Carassius auratus were the main characteristic species causing the differences between the two groups. Compared with the years before enhancement and release activities, the number of species in this survey increased, but the composition of the catch was still dominated by small fish. In order to improve the diversity and stability of the fish community structure of Dianshan Lake, it is recommended to continue to carry out enhancement and release activities, and strictly control the discharge of sewage and wastewater.

Based on the data collected in Oujiang River Estuary from 2021 to 2022, the population structure, the length-weight relationship and the growth and mortality of Coilia nasus were analyzed. A total of 1,153 individuals were caught, from which the length-weight relationship were derived as W = 0.001 0L^3.4151 (R² = 0.9845), showing a positive allometric growth pattern. The growth parameters of von Bertalanffy formula estimated by ELEFAN I of FISAT II were 38.90cm(L_∞), 0.44(k) and -0.56a(t₀). The total mortality Z estimated by length-converted catch curve was 2.47 while the natural mortality M and fishing mortality F were 0.79 and 1.68, respectively, and the exploitation rate was 0.68. Beverton-Holt yield per recruitment model simulation showed that Y_w/R trends to increasing and then decreasing with the increase of fishing mortality (F). The biological reference points F_max and F_0.1 were 1.54 and 0.64, respectively. C. nasus stock has been over-exploited. We propose that the body length at first capture should be increased to 22cm, and the fishing pressure reduced to ensure sustainable use of the resource.

It is important to understand the near-shore hydrodynamic processes under the influence of super typhoons to guide the construction of coastal engineering, coastal disaster prevention and mitigation. In this paper, a numerical model based on the FVCOM-SWAVE was established in the China Seas to simulate the offshore hydrodynamic processes under the influence of three super typhoons. The distribution characteristics of marine elements under the influence of super typhoons were analyzed, and the influence of wave-current interaction on the simulation of hydrodynamic processes was investigated. The results showed that: the location of the maximum significant wave height was related to the tracks of the typhoons, and the maximum significant wave height was generally located in the right of the typhoon centre; the distribution of typhoon waves on both sides of the typhoon path was related to the landing sites of typhoons; the coupled model could better consider the impact of wind and air pressure; the wind speed and direction were the main factors which affected the distribution of nearshore surge, and the storm surges and wave heights were significantly correlated under the effects of super typhoons.

In human being's disordered exploitation and utilization activities, the resources in the natural coastline have been constantly consumed and the coastline ecological functions have been destroyed seriously. This article studied the method of coastline occupation and compensation, including putting forward the proportion of the method, discussing the proportion coefficient of the method, analyzing the influences factors on the value of coastline, finally establishing the index system of the coastline occupation and compensation proportion, and applying this index system to three sea-use projects for empirical analysis. According to the research conclusions, this article offered the opinion on the method in order to provide a reference for the coastline occupation and compensation mechanism and the coastline refined management.

According to 11 water quality monitoring data from 2006 to 2019, the pollution degree and eutrophication degree of Huanghua offshore during this period were studied through the analysis and evaluation of a series of water quality indexes, to understand the influence of sea reclamation activities on the water quality of coastal waters. The water quality indexes included the inorganic nitrogen, phosphate, dissolved oxygen (DO), chemical oxygen demand (COD), pH value, petroleum and heavy metal elements. The results indicated that the water quality of this area was polluted to some extent, and recovered after the end of sea reclamation activities. Moderate eutrophication was reduced to poor eutrophication, and COD was the main pollutant of seawater eutrophication. The heavy metal elements in this area all met the second class of water quality standards. Except for the serious pollution of DIP, the water quality indexes basically met the first class of water quality standards.

In this paper, the high-order spectral model HOS was used to simulate the waves in the northern South China Sea. First, the wave model WAVEWATCH III was used to simulate the waves in the target sea area, extracted the two-dimensional wave spectrum of the extreme process, and used it as an open boundary condition to simulate the wave surface time series of 12 typhoons in the northern South China Sea under extreme wave conditions. Through the processing and analysis of the wave surface time series, it was concluded that the waves in the target sea area were strongly nonlinear, and abnormal waves appeared at some measuring points.

Focusing on the disasters of storm surge, wave disaster and sea ice disaster during 1949—2015 which affected North China Sea (government jurisdiction areas to the north of Xiuzhen river estuary located on borderline between Shandong and Jiangsu province), the loss index system of historical marine disaster and the index system of nature variations were constructed on the basis of collection and integration of historical marine disaster literature,observed data during the disaster process and the image data. Using Oracle database platform, historical marine disaster database was built up. The marine disaster data management platform of North China Sea which synthesizes the spatial query, graphical statistics and digital data management was established using ArcGIS platform. The platform can provide critical technical supports for marine disaster prevention &mitigation and relevant technical references on risk area cataloging, risk assessment, disaster forecasting and disaster losses post-assessment, and can also be an important reference to standardize the construction of marine disaster database domestically.

Seagrass beds perform important ecosystem services like climate regulation, water quality purification, carbon sequestration and benthic food web stablization. The complex interaction between seagrasses and macrobenthos is important to understand the ecological function of seagrass beds. According to the related researches on the macrobenthos inhabiting seagrass beds, we summarized the research progress of macrobenthic community diversities, including the food source and shelter supplied by seagrasses for benthic fauna, and the spatial distribution of macrobenthos diversity in seagrass beds. The influence of macrobenthos on seagrasses was discussed. Firstly, macrobenthos densities had different effects on seagrasses. Secondly, macrobenthos may affected the photosynthesis of seagrasses. Finally macrobenthos could lead to changing sulfide and nutrient concentrations in the sediment of seagrass beds. Agianst the background of global climate change and anthropogenic activities, the influence of temperature, salinity, ocean acidification, eutrophication and reclamation on the interaction between seagrasses and macrobenthos was clarified. Future researches should direct to the diversity of macrobenthos in seagrass beds, macrobenthos utiulization in monitoring and evaluating seagrass ecosystems, effects of interactions between macrobenthos and seagrasses on seagrass beds restoration, and response of seagrass and macrobenthos interaction to global climate change and anthropogenic activities.

The selection of universal primers is very important for by environmental DNA (eDNA) metabarcoding in monitoring fish biodiversity. In this study, the eDNA samples were taken from Lake Dianchi, the amplification performance of six pairs of universal primers (Teleo, Meta, CY45M, 1634M, MiFish, FishCB) were compared. The results showed that 1634M, Meta and Teleo amplify the eDNAs well, yielding bright, clear and single target bands suitable for subsequent high-throughput sequencing. With 1634M, Meta and Teleo, eDNA samples from Lake Dianchi in dry and wet periods were amplified and sequenced. A total of 37 species of fish belonging to 8 orders, 13 families and 36 genera were annotated, which include common fish in Lake Dianchi like Misgurnus anguillicaudatus, Carassius auratus, Monopterus albus, Cyprinus carpio, Pseudorasbora parva and endangered rare Sinocyclocheilus grahami. There was a significant difference in the composition of fish species annotated with the data from the three primers, 24 (1634M), 9 (Meta) and 10 (Teleo) species, respectively. In total, 33 fish species including Sinocyclocheilus grahami, Cultrichthys erythropterus, Ctenopharyngodon idella among others were specifically annotated by one of the three primers. The fish annotated by all three primers were Hyporhamphus intermedius and Cyprinus carpio. The fish annotated by 1634M and Meta is Rhinogobius similis. The fish annotated by Teleo and Meta is Carassius auratus. The monitoring results based on all the three primers could clearly reflect the seasonal variations of fish diversity in Lake Dianchi, and the difference of fish species composition in the wet period was smaller than that in the dry period. Combination of multiple universal primers would improve coverage rate of fish species composition and the effect of diversity monitoring.

Fish composition diversity is an important part of aquatic biodiversity, and it is difficult to investigate fish diversity with traditional resource investigation methods. In order to understand the main fish species and structural characteristics in Liuheng sea area, in this study, we used environmental DNA technology to investigate the fish communities in Liuheng sea area of Zhejiang Province. Water samples were collected from different stations and the environmental DNA was extracted. Through PCR amplification and high-throughput sequencing, 37 common fish species were detected among 23 samples of environmental DNA, whicn belong to 36 species in 30 genera of 8 orders, 18 families and 8 orders of Actinopterii, and 1 species in 1 order, 1 family and 1 genus of Chondrichthyes. Among them, Harpadon nehereus, Larimichthys polyactis, Sebastiscus marmoratus, Muraenesox cinereus and Engraulis japonicus had relatively high abundance. The results showed that the environmental DNA technology has a high similarity with the traditional survey methods. Although it can not completely replace the traditional resource survey methods, it can be used as a supplementary tool to evaluate the existing situation of fish resources in Liuheng sea area and provide a basis for supplementing the diversity of fish resources and population structure in Liuheng sea area.

The implementation of riprap protection for submarine cables is one of the important measures to ensure the safe and stable operation of the power grid. Aiming at the navigation and anchoring behavior of typical ships in offshore waters, this paper took random polyhedron particles as the basic unit based on the theory of discrete element correlation. The PFC^3D software was used to establish the calculation model of anti-anchorage system of submarine cable riprap protective layer. Aiming at two different forms of anchor damage, i.e., anchor smashing and anchor dragging, the anti-anchor damage performance of submarine cable was quantitatively analyzed according to the pressure limit of the side wall of submarine cable, with the thickness of riprap layer, anchor weight and anchor speed as the influencing factors. The simulation results showed that the riprap protective layer dissipated the work of the external load of the anchor when the anchor was damaged and finally stopped the anchor through the formation, development, rupture, and reorganization of the particle force chain inside the rockfill, which could effectively protect the submarine cable. At the same time, it was proposed to detect and to repair the riprap protection in the submarine cable project with the riprap layer thickness of 0.9 m as the threshold, which provided a reference for the actual project.

Based on the analysis of the carbon and oxygen isotopic characteristics of planktonic foraminifera and magnetic susceptibility in the columnar samples of TS6 core from the southern part of southwest Taiwan basin of the South China Sea, the climate evolution history of the area since the last deglaciation was discussed. Oxygen isotope and magnetic susceptibility showed multiple climatic fluctuations since the last deglaciation, and these climatic fluctuations included Heinrich event 1, Blling-Allerd, Younger Dryas, and multiple cold events in the Holocene. Carbon isotope records showed high productivity of surface seawater in the periods of 16 kaBP～8 kaBP, which was related to the prevalence of winter and summer monsoons. Since the last deglaciation, the overall trend of the magnetic susceptibility was very consistent with that of the winter monsoon. The analysis showed that the change of the magnetic susceptibility was mainly controlled by the strength of the winter monsoon.

Murray cod (Maccullochella peelii) has been considered as one of the freshwater fish species that is suitable for aquaculture due to its high nutritional value and suitable attributes for aquaculture. In recent years, several breakthroughs have been made in the breeding technology of Murray cod, and the breeding scale has also been expanding. As a dominant breeding species in the industry of freshwater aquaculture in future, Murray cod aquaculture has great potentials. In this review, we introduced the biological characteristics, nutritional value, breeding status, nutritional requirements, diagnosis and prevention of infectious diseases, and the current breeding modes of Murray cod. Meanwhile, we put forward prospects and several suggestions on the existing problems in Murray cod aquaculture.

Silky shark (Carcharhinus falciformis) is caught as an important bycatch in tropical tuna longline fishery, which situates at the top of the marine food chain as an apex predator and plays an important role in maintaining the balance of the marine ecosystem. Silky shark stock is in decline under overfishing and it has been listed for protection under Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora in 2017. Based on the sample data (5 617 ind.) collected by Chinese longline fishery observers in tropical Pacific (90°55′W~139°58′E, 37°20′N~36°49′S), preliminary analyses of catch rate, sex ratio and fork length were conducted. Higher catch per unit effort (CPUE) was found in area of 105°W~165°E and 10°N~20°S. There was a decline trend of CPUE of silky sharks from year 2015 to year 2019 (the highest in 2017). There was a significant difference between years (P<0.05), but monthly CPUE was higher from June to October, with a significant difference in CPUE between months (P<0.05). The overall dominant fork length (FL) of females and males ranged from 90 to 170 cm. The ratio of females to males conformed to 1∶1 (P>0.05). The dominant fork lengths varied between 90 and 110 cm for females and males in tropical western and central Pacific, and between 150 and 170 cm for females and males in tropical eastern Pacific. There were significant differences between the mean fork lengths of females and males in both seas (P<0.05).

Extreme wave height is an important environmental condition in offshore and ocean engineering design, and the study of the design values of wave height is of great significance. Based on the traditional compound extreme value distribution, this paper classified the maximum wave height data of the wave disaster process according to their source, and selected the optimal extreme value distribution by fitting various wave height sequences respectively. Finally, the design value of wave height was calculated jointly and compared with the design value of Poisson compound extreme value distribution model and annual extreme value model. The results showed that the Pearson type 3 distribution had the best fitting effect on the wave height in the Beihai area. Compared with the traditional model, the design wave height of the multi-source compound extreme distribution model was more conservative. The multi-source compound extreme distribution model proposed in this paper can provide some reference for the design of offshore and ocean engineering.

To know the community structure of zooplankton in the sea area near Xiaoqing River estuary of Laizhou Bay and its relationship with environmental factors, the eutrophication degree of water quality, species composition, dominant species, community structure of zooplankton and the correlation between species diversity and environmental factors were analyzed based on the investigation data in March (spring), 2022. The results showed that eutrophication occurred in all stations in the investigated sea area, and a total of 12 species and 3 taxa of zooplankton were found. The average individual density of zooplankton was 1100.0 inds./m³, the average biomass (wet weight) was 732.0 mg/m³, the average Shannon-Wiener index (H′), Margalef's species richness diversity (d) and Pielou's evenness index (J′) were 1.71, 0.93, 0.67, respectively. The dominant species were Pseudodiaptomus poplesia, Sinocalanus tenellus, Acartia omorii and Eurytemora pacifica. Cluster analysis showed that the zooplankton in the investigation area can be divided into three groups. The results of correlation analysis showed that water temperature was an important environmental factor affecting the biomass and individual density of zooplankton in the sea area.

Against the background of "dual carbon", how to alleviate the pressure of "dual carbon" by effectively developing and utilizing the blue carbon resources has become an important practical problem. Establishing a balanced mechanism of utilization and management of blue carbon resources is the key to promote the sustainable development of blue carbon. In this paper, we analyzed blue carbon resource use and management using the method of game theory and simulation and by constructing a dynamic game model of evolution for both the government and enterprises, and determined the agent in view of the simulation under different parameters and comprehensive exploration blue carbon resource utilization (enterprise) and management (the government), and the main body of strategy selection and evolution path, to provide a reference for the blue carbon scientific and reasonable utilization of resources. It was found that there is a long-term stable strategy in the evolutionary game between government and enterprise, and a possibility of long-term stable cooperation between them. The government's strategic choice was closely related to its reputation for environmental change caused by blue carbon. The participation of enterprises made it possible for the government to carry out blue carbon policies. In addition, the governmental strategic choice was also affected by its regulatory costs and subsidies to enterprises. Excessive regulatory costs and excessive subsidies to enterprises may slow down its stability. The strategic influence of the government was mainly influenced by the additional income and social resources obtained, and the participation of the government made it possible for enterprises to obtain additional income. In addition, the strategic choice of enterprises was also affected by governmental subsidies, governmental supervision and their own "collaborative" investment. The greater their "collaborative" investment, the stricter the government supervision and the slower the stabilization strategy of enterprises. Even the withdrawal of cooperation may happen. When the government subsidy was higher, the enterprise stabilized the strategy faster.

Tuna fishery occupies an important position in the world fishery, and is the key development industry of fishery countries and regions in the world. Based on the major tuna catch data of the world from 1950 to 2019, combined with tuna trade data, population data and GDP data of countries and regions around the world, the status of the world tuna fishery was summarized. The results showed that the catch of major tuna trends obviously to increase from 1950 to 2019, but the catch each species vary each other. The cumulative total catch of Katsuwonus pelamis was the highest and its average growth rate each generation was the highest. The catch of the three major bluefin tuna was low, and the average growth rate of Thunnus thynnus and Thunnus orientalis was negative each decade. The catch of tuna was greatly different among countries and regions. The total catch of major tuna of 6 developed countries and regions including Japan and the United States accounted for 56.68% of the total while that of Chinese mainland only accounted for 1.02%. In addition, the total tuna catch of 11 island countries with the highest per capita tuna catch and Marshall Islands sparsely populated and rich in resources was only 4.30×10⁴t in 2013, Less than 10% of Japanese catch. The United States, Japan and other developed countries and regions stood at the top of the world in the global economic development firmly controled the fisheries regulations of tuna in the high seas and the right to set quotas, and then the global trade in tuna. Among them, the trade volume of major tuna in Japan accounted 25% of the global trade volume. The results also indicated that the tuna in the high seas are the precious resources for universal, not specific to a small number of countries and regions. To truly realize the sustainable development for world tuna fishery and the blue growth target advocated by FAO, the existing system of rule of inequality and injustice should be broken, the principle of humanity sharing blue ocean economy of new rules and new order should be formulated newly.

Based on the quality-controlled wind speed from automatic weather station (AWS), this study used statistical methods to find that there was an obvious linear relationship between the hourly maximum wind speed and the hourly 10-minute maximum wind speed. Subsequently, refined maximum wind speed forecast equations for each station in Zhoushan port were established. In addition, the error relationship between the 10-meter wind speed from the ECMWF (European Centre for Medium-Range Weather Forecasts) model and the hourly 10-minute maximum wind speed was analyzed to further optimize the maximum wind speed forecast equations. Evaluation of the maximum wind speed from May 1, 2016 to May 30, 2017 showed that the 10-meter wind speed forecast by the ECMWF model was overestimated for stations with low annual winds, but matched well for those with high annual winds. The station-specific maximum wind speed forecast equations after average wind correction were significantly better than the universal equation. ECMWF's 10-meter wind forecast performance varied little across different initiation times. Forecast performance decreased linearly with longer lead time for high-wind stations, but stayed stable for low-wind stations. The regression equation simulated better for stations with relatively high wind but the error became larger as the forecast timeliness increased.

Based on the ANSYS Workbench platform, the three-dimensional internal solitary wave (ISW) numerical flume was established. Considering the different propagation directions of the ISW, the numerical simulation of the flexible riser with different tilt angles under the action of ISW was carried out, and the dynamic response laws of the flexible riser with different arrangements were analyzed. The point displacement, support reaction and section shear stress of the flexible riser in different working conditions were compared and analyzed. And the results showed that the vertical component of the fluid force on the inclined flexible riser in ISW could not be ignored, and the support reaction of the flexible riser would be affected. As the arranged flexible riser tends to be vertical, the displacement, support reaction and section shear stress of the flexible riser all gradually decreased. Compared with these indicators of different tilt directions of the flexible riser, the above three indicators were greater when the tilt direction of the flexible riser was consistent with the propagation direction of the ISW. Therefore, when the riser was arranged in sea areas with frequent ISW, it should be arranged as close to the vertical as possible, and the tilt direction of the riser should be avoided from the same as the propagation direction of the ISW.

During the penetration process of the side-rounded caisson, the soil in the caisson will be high. Too high soil height will make the bucket foundation unable to be installed to the specified depth, thus failing to provide the designed bearing capacity. In practical project, bucket boots are used to improve the penetration capacity of the caisson. Therefore, it is necessary to analyze the penetration resistance of the caisson under different bucket boots forms and the height of the soil in the caisson to provide a reference for engineering applications. This paper used the Coupled Euler-Lagrangian (CEL) method to simulate the penetration process of the side-rounded caisson, and compared it with the field test data. The result fitted well, which confirming the effectiveness of this method. The influence of the bucket boots form on the end resistance and the height of the soil in the bucket, the influence of the wall thickness and soil weakening parameters on the volume of the soil in the bucket were analyzed. The results showed that the larger the chamfer of the bucket boot, the smaller the end resistance, and the outer chamfer of the bucket base was easier to reduce the height of the soil in the bucket during the penetration process. The greater the wall thickness of the caisson and the sensitivity coefficient of the soil, the greater the soil volume increased ratio of the caisson, the greater the ductility coefficient of the soil, and the smaller the soil volume increased ratio. Finally, the soil volume increased ratio in the bucket was fitted according to the calculation results. The formula of the soil volume provides a reference basis for the engineering installation.

Poyang Lake is the largest freshwater lake with seasonal throughput in China. In this paper, the following data of the Poyang Lake were collected and analyzed, the water level data of hydrological stations, the wind field observation data of the meteorological station and the bathymetry measured in the lake area. Then, the wave height distribution in Poyang Lake was calculated and analyzed with numerical simulation methods based on wave action conservation equation. The calculation results of numerical methods and standard methods were compared. The results of the comparison showed that the calculation results of the two methods are generally close to each other, and the calculation results of the numerical method are slightly larger than that calculated with the standard method. Finally, we concluded that the significant wave height (H_13%) around Poyang Lake under extreme high water level conditions varied between 1.70m and 2.08 m and the mean wave period (Tm) varied between 4.39s and 5.25s.

Industry chain coordination is an urgent problem to be solved in aquaculture industry, and effective coordinated operation is the inevitable choice and direction of aquaculture industry development. Through literature review and theoretical analysis, the influencing factors of aquatic product industry chain coordination of China were summarized from the perspectives of industry chain structure, relationship, governance and culture. Exploratory factor analysis was used to identify 17 main factors of aquatic product industry chain synergy. The first order single factor model, the first order four-factor uncorrelated model, the first order four-factor fully correlated model and the second order four-factor model were established for confirmatory factor analysis. The empirical results showed that the second-order four-factor model has a good degree of model fit, which verified the rationality of the collaborative structure of the aquatic product industry chain of China, which included four dimensions, industry chain structure, industry chain relationship, industry chain governance and industry chain culture. The developed scale can provide a reference and operational tools for the research and practice of aquatic product industry chain.

Delta wetlands play an important role in maintaining ecological balance, sequestration and sequestration, and ensuring the coordinated development of regional ecological economy. Using the relevant index data of ecological restoration in the Yellow River delta from 2019 to 2021, this paper evaluated the ecological restoration efficiency of the Yellow River delta based on the input-output model from the perspective of Blue Carbon, and the results showed that the ecological restoration input level was good, the ecological restoration output level was average, the input-output ratio of ecological restoration efficiency was 0.87, the input-output ratio was less than 1, and the restoration efficiency was average, and the restoration efficiency of the blue carbon function was 1.05, which was slightly higher than the overall ecosystem restoration efficiency.

Dredging is a common marine engineering operation, which has negative impacts on the marine ecosystems, especially on marine mammals. In present paper, we reviewed the direct and indirect impacts of dredging activities on marine mammals. The direct impacts include temporary and permanent damages to the auditory system and hearing masking of marine mammals; the potential threat of dredging vessels to marine mammals, and the change of seabed topography which influences the habitat use of marine mammals. Indirect impacts include changes in water quality, pollutants and food resources, and further one on marine mammals. Dredging may also play positive roles in local ecological restoration, improving the habitat quality of marine mammals. According to the negative impacts, we proposed corresponding mitigation measures to protect marine mammals, which may significantly aid to environmental impact assessment of dredging and conservation and management of marine mammals.

In this study, the effects of spatial-temporal and environmental factors on the abundance and distribution of Scomber japonicus were analyzed using a generalized additive model based on the production data of lighting purse seine capturing in summer and autumn from 2009 to 2018 in combination with the marine environmental data obtained by remote sensing. Catch Per Unit Effort (CPUE) of S. japonicus showed a significant difference from 2009 to 2018. From July to October, the center of gravity of S. japonicus moved northeast, and tended to move to the outer sea. The GAM analysis showed that four factors including year, longitude, latitude and sea surface temperature had significant effects on the CPUE of S. japonicus, and the significance can be ordered by year, sea surface temperature, longitude and latitude. The synoptic analysis showed that the high CPUE of S. japonicus was distributed on both sides of the diagonal line with low longitude, low latitude and high longitude, high latitude, and the temperature ranged mostly from 27.2 to 29.7 ℃, which was the central fishing ground for S. japonicus. Our findings provided a reference for finding the central fishing ground and the management of lighting purse seine fisheries.

The dynamic changes caused by climate change and anthropogenic activities have induced a variety of groundwater environmental problems, as well as a series of environmental and geological hazards in the coastal zone. Meanwhile, the seawater intrusion and the accompanying process of soil salinization are of great concerns. Clarifying the water and salt transportation pattern during the occurrence of seawater intrusion-soil salinization disaster chain is crucial for the prevention and control of this environmental geohazard. In this study, we simulated the seawater intrusion process on the silty coasts and characterized the water-salt transportation law during the disaster chain with the high-density resistivity method. The results showed that the invasion speed, distance and area increased with the increase of hydraulic gradient. When the depth of groundwater is shallow, the saltwater intrusion has an obvious exacerbating effect on the accumulation of salts in the overlying soil, resulting in a salt peak in the soil profile. The salt peak moves upwards under the capillary action, easily leading to soil salinization. In the process of freshwater replacement of salt water, freshwater firstly replaces the saline water in the upper soil layer of the sediment layer, resulting in salt peak, which then moves downwards and gradually disappears. In summary, water storage should be enhanced to increase the infiltration of surface water during the wet season, and water exploration should be slowed down to reduce the groundwater gradient during the dry season in order to prevent the occurrence of the saltwater intrusion-soil salinization disaster chain.

In this study, 46 Japanese mackerel (Scomber japonicus) individuals collected from the northwest Pacific were used to explore the necessity of the lipid extraction for the stable isotope analysis of Japanese mackerel, and to determine the influence of lipid extraction on the carbon and nitrogen stable isotope ratios (δ¹³C, δ¹⁵N) of the muscle and liver of thie fish.The relationship between the ratio of carbon and nitrogen content (C:N) and the constant 3.50 was compared and analyzed to determine whether this species needs lipid extraction pretreatment. The δ¹³C correction model of muscle with liver was proposed.After lipid extraction, δ¹³C and δ¹⁵N of muscle increased by 0.41‰ and 0.61‰, respectively, while C:N decreased by 0.21, δ¹³C of liver increased by 0.73‰, δ¹⁵N kept unchenged and C:N decreased by 0.31.Individual analysis of muscle and liver C:N below 3.50 showed significant differences in δ¹³C after lipid pumping.Accodingly, the relationship between C:N and constant 3.50 is not appropriate for determing whether Japanese mackerel needs a lipid extraction pretreatment. Lipid extraction is necessary before δ¹³C analysis for studying Japanese mackerel muscle and liver.The optimal calibration models are Δδ¹³C=-0.53×δ¹³C_bulk-9.85 and Δδ¹³C=-0.79×δ¹³C_bulk-14.88.Lipid extraction was not performed when δ¹⁵N of Japanese mackerel in muscle was analyzed while lipid extraction was not necessary for the analysis of δ¹⁵N in Japanese mackerel liver.