Based on eddy dataset, this paper analyzed the spatial distribution and temporal variation characteristics of the generation location, quantity, size, lifetime and moving trajectory of mesoscale eddies in the South China Sea. In terms of the generation location, the eddies were mainly generated in the sea areas to the southwest of Taiwan island and to the west of Luzon island, and the cyclonic and anticyclonic eddies had their own main generation locations in different seasons. In terms of the number of eddies generated, the number of cyclonic eddies was greater than that of anticyclonic eddies. The total number of eddies was relatively the largest in winter, and the prevailing was cyclonic eddies. The total number of eddies was the least in summer, and anticyclonic eddies were prevalent. In terms of eddy size, the average radius of anticyclonic eddies was slightly larger than that of cyclonic eddies. The average radius was the largest in fall and the smallest in spring. Except in fall, the average radius of anticyclonic eddies was greater than that of cyclonic eddies. In terms of eddy life, the average life of anticyclonic eddies was slightly longer than that of cyclonic eddies. The average life was the longest in winter and the shortest in fall. The average life of cyclonic eddies was longer in winter and fall, but opposite in summer and spring. From the perspective of eddy trajectory, most of the eddies to the southwest of Taiwan island moved southwestward along the edge of the continental shelf after generation. Most of the eddies to the northwest of Luzon Island moved locally after generation, and most of the eddies to the southwest of Luzon island moved westward after generation. In addition, the main parameter characteristics of eddies in the South China Sea were also related to the El Niño phenomenon.

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.

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.

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.

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.

In this paper, we investigated the community structure of Zhejiang inshore Larimichthys crocea and its spatial and temporal distribution in relation to environmental factors based on single-vessel bottom trawl surveys and environmental data from spring and autumn (April-May and November) of Zhejiang inshore from 2014 to 2020. The results showed that in spring, the length range of L. crocea varied between 48 and 250 mm, the mean body length was 151.0±26.5 mm, the weight range was from 1.5 to 252.4 g, the mean weight was 60.7±31.2 g in autumn; the length range of L. crocea ranged from 106 to 284 mm, the mean body length was 157.9±21.8 mm, the weight range was from 18.8 to 295.0 g, and the mean weight was 71.6±31.2 g; and significant differences were found in body length and weight of L. crocea in autumn compared with those in spring (P＜0.05). The relationship between body length and body weight of L. crocea was describable with the equation W=4×10^-5L^2.8323 (R²=0.9129, n 564), the b value was less than 3, and L. crocea was experiencing a negative anisotropic growth. The density of L. crocea resources ranged from 0.05 to 447.22 kg·km² during the 7-year period from 2014 to 2020, with a mean of 28.69 kg·km² and a wide distribution range from south to north along the Zhejiang coast. There was a significant difference in the density of L. crocea resources in autumn compared with spring (P<0.05), and they were more widely distributed. The GAM model analysis showed that three factors, latitude, longitude and surface water temperature, had significant effects on the density of L. crocea resources, with surface water temperature being the most significant one. Through the investigation and analysis of the fishery resources of L. crocea in spring and autumn near the coast of Zhejiang Province, we aimed to provide a scientific reference for the restoration of the fishery resources of L. crocea.

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.

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.

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.

The Fukushima nuclear power plant planed to begin diluting Fukushima nuclear wastewater into the ocean in March 2023. However, experts had questioned the safety of the Fukushima nuclear wastewater discharge. Based on the latest research on the Fukushima nuclear wastewater, including the distribution, harm and migration rule of radionuclides, this paper summarized and analyzed the treatment methods of Fukushima nuclear wastewater, the content of dangerous nuclides, the migration path of nuclear wastewater and the impact on the marine ecological environment, and discussed the potential impact of Fukushima nuclear wastewater discharge on the surrounding sea area. It was hoped to provide some suggestions for marine radioactive safety assessment and for coping with the possible effects.

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.

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.

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.

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.

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.

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.

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.

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.

Bubble curtain is extensively used as an ecology device, which can be treated as breakwater, oil boom, silt curtain, saline barrier, mixer & aerator, acoustic & explosive screen, and fish curtain. In this paper, the generation principle and characters of the bubble curtain were introduced, and the action mechanism in various application was elaborated. Besides, the effect and application condition in practical usage were reviewed. On this basis, the main utilization characteristics of the bubble curtain were summarized, which could provide an important reference for comprehensive understanding on the relative application theories of the bubble screen and promotion of bubble barrier technology application, and lay a foundation for subsequent research.

In this paper, the observed data of the eastern sea area of Shandong Peninsula and the reanalysis data of ECMWF ERA5 were used to compare and verify the accuracy of ERA5 data in the sea area and to analyze the variation rules of wind speed and significant wave height from December 2020 to November 2021. The observed wind field data of polyurea buoy was of the same magnitude as that of the reanalysis wind field data of ERA5, and the coincidence was high. The theoretical value of significant wave height calculated according to the observed wind field data was less than the value of significant wave height in the ERA5 reanalysis data in most of the time, and the observed significant wave height was also less than the significant wave height in the reanalysis data. Finally, this paper compared and analyzed the measured significant wave height of “Langlong” wave measuring instrument and the significant wave height of ERA5 reanalysis data by season. The results showed that the ERA5 data and the observed data had a high coincidence in summer, and the worst coincidence in winter, but the abnormal rise of wave height could be obviously observed during the transit of tropical cyclone and cold wave gale. The analysis results could provide a valuable reference for port construction and marine economic development in the nearby sea area.

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.

In order to understand the water quality pollution status of Laizhou Bay, to achieve total control of land-based pollutants and comprehensive management of pollution in rivers entering the sea, and to protect the water environment of Laizhou Bay, the input fluxes of four typical pollutants from three types of pollution sources, nine major rivers estuarine coastal zones and the port directly discharging into the sea in Laizhou Bay were estimated from 2017 to 2019. The results showed that the annual average marine fluxes of chemical oxygen demand (COD), total nitrogen (TN), total phosphorus (TP) and petroleum were 32.64×10⁴ t/a, 11.45×10⁴ t/a, 2 140 t/a and 442.1 t/a, respectively. Rivers were the most important sources of land-based pollutants in Laizhou Bay. For example, the fluxes of four pollutants into the sea accounted for more than 90% in 2018. The largest input source of pollutants in Laizhou Bay was the Yellow River, followed by the Xiaoqing River, which had the highest proportion of pollutant flux into the sea. The four pollutants fluxed into the sea accounted for 34.3%, 50.8%, 47.7% and 38.9% of the total pollutant flux of the remaining eight rivers. Precipitation was the key factor affecting the flux of land-based pollutants to the sea, and TN was the primary land-based pollutant in Laizhou Bay at present.

In this work, a two-dimensional wave-current coupled sediment transport model was established to investigate the erosion and deposition of the Feng River Estuary and its adjacent waters applying Delft3D model. The simulated results showed a good agreement with the observed data, which revealed that the numerical model could effectively reproduce the erosion and deposition process. Based on the validated sediment transport model, the characteristics of erosion and deposition in the study area was discussed. The results indicated that the scouring phenomenon was mainly concentrated on the downstream of the damming lock and near the south bank near the location of the damming lock. However, the siltation phenomenon was mainly located in the upstream of the damming lock and near the north bank near the location of the damming lock. Moreover, different wave conditions have different effects on the characteristics of erosion and deposition at the river estuary. The results of this paper not only provided a scientific theoretical basis for the dredging and erosion prevention measures when the impoundment gate needed to be closed, but also had important practical significance for the sustainable development of the Feng River Estuary area.

In order to explore the role of constructed wetlands in the ecological restoration of lakeside wetlands in Bosten Lake, based on the field investigation and laboratory test, a comparative analysis of constructed wetlands was conducted before and after construction in Luoxia Bay, west coast of Bosten Lake, about the difference of water quality index, soil nutrient index and plant diversity index in wetland. The results showed that the removal rates of nitrogen and total phosphorus were 54.05%~77.77% and 74.47%, respectively. The soil nutrient content in the study area was low as a whole, and the soil nutrient content of the constructed wetland in Bosten Lake was higher than that of the control group. The content of available phosphorus at the level of “Abundant”, and the content of other indexes were at the level of “Extremely deficient-slightly deficient”. The construction and operation of constructed wetland in Bosten Lake had changed the wetland habitat, the plant species in the wetland had increased, the dominant species had changed, and the ecological environment of Bosten Lakeside Wetland had been improved obviously.

Based on the survey data of fishery resources and hydrological environment in the Yangtze River Estuary from 2017 to 2021, five different habitat suitability index (HSI) models were built to explore the suitable environment and habitat distribution characteristics of Coilia nasus in different seasons. The results showed that the suitable water depth of C. nasus population was below 15m, the suitable salinity varied between 0 and 19.2, and the suitable surface water temperature ranged from 8.2℃ to 30.3 ℃. There were some differences in the best habitat models in different seasons. The geometric mean model (GMM) has a better fitting effect in spring, the continuous product model (CPM) has a better fitting effect in summer and winter, and the minimum model (MINM) has a better fitting effect in autumn. In addition, according to the prediction results of the optimal model, the distribution of the most suitable habitat of C. nasus also changes in different seasons, and the high HSI value area of the whole year appears in summer. In spring, the suitability index of the waters outside the estuary is higher than that in the estuary. In summer, the habitat suitability index of the South Branch was higher than that of the North Branch. In autumn, there are two high HSI waters outside the estuary, which are slightly higher than those inside the estuary. In winter, similar to autumn, the distribution trend outside the estuary is higher than that in the estuary. By exploring the distribution and change of C. nasus habitat in different seasons in the Yangtze River Estuary, our findings can provide a scientific basis for the sustainable utilization of C. nasus in the Yangtze River Estuary, and are of a great significance to the protection and restoration of resources in the Yangtze River Estuary.

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.

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.

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.

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.

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, 32 strains of halophilic bacteria from Xiaoqaidan Salt Lake, Qinghai Lake and Keke Salt Lake were fermented with their intracellular products extracted. The bacterial strains performing antibacterial activity were screened with filter paper method (K-B method). Six strains of halophilic bacteria including K-20, X-32, Q-10, Q-19 and Q-31, were found to inhibit Bacillus subtilis, E. coli and Staphylococcus aureus and Enterococcus faecalis while B. zhangzhou showed an antibacterial activity. The active strains were characterized biologically under different culturing conditions. The results showed that 6 active strains are all Gram negative and shape as a long rod or arcuate. The optimal growth salt concentration (NaCl) of the 6 strains ranged from 0.5 to 2.5 mol/L, belonging to the moderate halophilic. Of them, Q-31 was halophilic with the optimal growth acidity varied between pH6.0 and pH8.0, and the optimal growth temperature 37 ℃. Biochemical identification revealed that these strains can grow using yeast extract, casein, tryptone and other nitrogen sources. K-20, X-20, X-32 and Q-31 can liquefy gelatin (GEL) while X-20, X-32, Q-10 and Q-31 produce urease (URE) and reduce nitrate. The phylogenetic analysis of 16S rRNA gene sequence showed that the active strains belong to Halomonas, Bacillus, Vibrio and Sphingomonas, respectively.

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.

A physical model experiment was carried out to study the landslide-generated waves, and the FLOW-3D software was used to simulate the measured wave surface, and the results were in good agreement. On this basis, the experimental study of caisson sliding of breakwater under surge was carried out. By solving the dynamic equation of caisson sliding, the caisson sliding under landslide-generated waves was obtained, and compared with the experimental results. The results showed that the experimental values were basically consistent with the theoretical values. Based on the verified theoretical method, the countermeasures to reduce the caisson sliding in practical engineering were put forward, including increasing the caisson mass, reducing the height of the caisson center of gravity and increasing the moment of inertia.

In this paper, we reviewed the sources, distribution, pollution characteristics and ecological risks of microplastics in coastal blue carbon ecosystems (BCEs), and the impacts of microplastics on the carbon cycle of coastal BCEs. In future, it is necessary to strengthen the research on the occurrence and influencing factors, the sources, environmental fate and ecological risks of microplastics in the coastal BCEs. Moreover, future efforts are needed to explore the influencing mechanism of microplastics on the carbon cycle of BCEs. Our understanding provided theoretical supports for the pollution monitoring, ecological risk assessment, ecological effects research, and prevention and control management policies of microplastics in coastal BCEs.

With the continuous progress of ecological civilization construction, fishery resource conservation in Huaihe River Basin has been paid more and more attentions. Fish health is closely related to fish resources with the intestinal flora as a key part. However, the report on the characteristics of fish intestinal flora in Huaihe River Basin is very scarce. To explore the composition and influencing factors of fish intestinal flora in Anhui section of Huaihe River, in March 2019, 90 intestinal samples were collected from 6 fish species, Acheilognathus chankaensis, Abbottina rivularis, Coilia nasus, Hemiculter bleekeri, Pelteobaggrus nitidus,and Parabramis pekinensis), and analyzed using 16S rRNA high-throughput sequencing technologies. Result display, Proteobacteria, Cyanobacteria and Verrucomicrobiota were the dominant bacteria in the gut of the six fish species. Furthermore, Bacteroidetes and Firmicutes also occupy a relatively high proportion in fish gut. Affected by feeding habits, the flora structure each group had significant difference (P＜0.01). LEfSe analysis found that the intestinal flora of herbivorous fish species were enriched into 46 iconic differentiating bacteria including Aminobacter, Planctomicrobium, Blastopirellula among others. Pseudomonas and Sphingomonas had significant differences in the intestinal tracts of fish in different resident water layers, and a large number of distinctive differential bacteria were enriched in the fish species of bottom water layer where 17 species of bacteria such as Arenimonas, Blastopirellula and SH-PL14 were documented. In addition, there was no significant difference in the dominant bacteria genera of the fish intestinal tracts among different reaches, but many rare groups were found in the fish intestinal tracts of the middle reaches. In general, the composition of fish intestinal flora is closely related to feeding habits, habitat water layer and habitat reaches, among which phytopherbivorous fish, benthic fish and midstream fish showed obvious differences between their respective groups. Our studies clarified potential influencing factors of fish intestinal flora in the natural environment, provided data support for the establishment of fish intestinal flora database and new ideas for the conservation of fish resources in Huaihe River.

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.

We conducted a comparative study between the projected and perceived images of Weizhou Island through content analysis and social network analysis. The research showed that (1) the projected image focuses on the tourism environment and tourism resources, and emphasizes the promotion of the overall image of Weizhou Island while the perceived image highlights the external elements and endowments such as geological and landform and island environment, the activity of tourism activities and tourism environment and the acquisition and expression of inner experience; (2) both projected and perceived images showed obvious power exponential distribution characteristics, and experiential characteristics of the long tail in the perceptual image curve are particularly obvious; (3) network centralization trend of the projected image is not obvious,the interaction within the subgroup is weak, and perceived image subgroups have strong internal interaction, and the correlation among subgroup is relatively high; (4) emotional analysis of perceived image showed positive emotions overall while negative emotions are mostly concentrated on tourism management and services. Accordingly, we propose to strengthen the publicity of tourism activities and develop characteristic tourism products; introduce PGC content to guide and correct tourists′ perception image; strengthen the construction of infrastructure and improve the quality of tourism security; strengthen the standardized management of scenic spots, scenic spots and island tourism practitioners.

Sea fog is an important weather phenomenon that affects horizontal visibility at sea. The remote sensing monitoring of sea fog is of great significance to marine activities such as maritime traffic and oil development. Based on the FY-3D polar-orbiting meteorological satellite data, this paper proposed a deep learning-based daytime sea fog remote sensing detection model CA-LinkNet. The model used the LinkNet network as the backbone, and introduced the coordinate attention mechanism (CA) in the skip connection part of the encoder and decoder to make full use of the position and channel information of the node feature map, and to enhance the localization and recognition capabilities of the network. The experimental results showed that compared with FCN, U-Net and LinkNet segmentation networks, the CA-LinkNet network proposed in this paper had higher accuracy in sea fog detection on the test set, with the mean intersection over union, probability of detection, false alarm rate, critical success index and Heidke skill score reaching 0.911, 0.900, 0.046, 0.862, 0.905, respectively. The model was used to detect sea fog in the Yellow Sea, the Sea of Japan and the Sea of Khozik and sea fog near the Chiba Islands, and the detection results were in good consistent with the CALIOP data.