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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Meiobenthology is an important component of benthology. In recent 20 years, meiobenthology has advanced rapidly with the development of new methods and amazing progresses in digitization. In 2023, a book entitled as ‘New Horizons in Meiobenthos Research: Profiles, Patterns and Potentials’ was published. It was edited by Olav Giere and Michaela Schratzberger, and over thirty authors with different backgrounds, perspectives and experiences participated writing. This book focuses on meiofauna and attempts to address and summarize recent progresses in various fields of forthcoming importance, emphasizes the role of meiofauna in the world of benthos, and seeks to outline new horizons for future meiobenthology. The content of this book is a summary of the current progresses in meiobenthology, and the prospect of the future meiobentholgy. It will play a substantial role in promoting the development and international exchanges of meiobenthology.

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

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

Seawater intrusion is a common disaster in coastal areas. It is usually associated with other natural disasters, such as deterioration of water quality and soil salinization, which affect normal industrial production, agricultural activities and human life. This study was conducted in three coastal cities in Jiangsu (Ganyu district of Lianyungang, Dafeng district of Yancheng, and Qidong city of Nantong) in November 2019 to determine the monitoring sections for sampling, to analyze the basic monitoring indicators of seawater intrusion and soil salinization, and to get a preliminary grasp. The current situation of seawater intrusion and soil salinization disasters in three coastal cities in Jiangsu were reviewed. The results showed that seawater intrusion and soil salinization disasters had occurred in three coastal cities in Jiangsu: severe seawater intrusion and heavy saline soil had occurred in Ganyu and Qidong parts of the survey area. The chloride ion concentration in Ganyu groundwater was as high as 2260.90 mg/L. The chloride ion concentration in the Qidong area was as high as 1472.30 mg/L. The soil salinization in Qidong and Ganyu was relatively large, and the degree of seawater intrusion and soil salinization in Dafeng was relatively light. Based on the current situation of seawater intrusion and soil salinization intrusion, and the analyzing the causes of intrusion in some regions, it would be helpful for follow-up research.

Harmful algal blooms are frequently caused in the context of global change by phytoplankton, which lead to a series of problems with respect to fisheries, aquacultures, human health and social economy. By utilizing the random forest classification method of machine learning, in this study, we developed two models of shellfish toxic and fish kill basing on the common harmful algal bloom species around the waters of Zhangzi Island in the northern Yellow Sea. The response variable of shellfish toxic model was designated by the cell abundances of Alexandrium tamarense, Dinophysis spp., Gonyaulax spp., Prorocentrum spp. and Pseudo-nitzschia spp. whilst that of the fish kill model was setup by the Karenia mikimotoi, Noctiluca scintillans and Dictyocha fibula. The feature variables for the two models were transparency, temperature, salinity, pH value and dissolved oxygen. The classification performance showed that the accuracy of the shellfish toxic and fish kill models were 87.9% and 89.7%, respectively, while the precision all reached up to over 80%. The analysis of the feature importance indicated that temperature and dissolved oxygen were the key predictive variables for shellfish toxic model with MeanDecreaseGini being 15.4% and 14.3%, respectively, while pH value and salinity were the key variables for fish kill model with that values of 21.6% and 15.5%, respectively. Our findings could provide case study and basic information on discriminating key predictive variables for the harmful algal bloom species and establishing the early monitoring and warning system in the waters of fisheries, aquaculture and crucial habitats.

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

The neon flying squid Ommastrephes bartramii is a short-lived squid species. As an "ecological opportunist", its habitat is regulated by climatic and environmental factors. O. bartramii stocks are mostly distributed at the junction of the Kuroshio and Oyashio Currents. The environmental conditions within this area are complex and changeable. The marine environmental factors had an important impact on the biological characteristics of O. bartramii in the Northwest Pacific, which included population structure, age and growth, ingestion and migration during different life cycle stages. In addition, the abundance and spatial distribution of O. bartramii resources in the Northwest Pacific were very sensitive to the mesoscale marine environments and large-scale climate change, and responded rapidly to these changes. In this study, we suggested that the first step should clarify the complete life history process of squid to explore the response mechanism of O. bartramii to environmental change in the Northwest Pacific, and then examine the dynamic change characteristics of O. bartramii at various scales. One another important step is to accurately determine the suitable range of the key environmental factors that had been widely used for O. bartramii. Under the background of large-scale climate variability research, it was necessary to consider the impacts of various anomalous climatic events, and to quantify the marine dynamic environmental factors at small and medium-sized space-time scales. According to the results, a model suitable for the assessment and prediction of O. bartramii resources in the northwest Pacific should be established. Model outputs can provide a theoretical support for the rational development, efficient utilization and scientific management of O. bartramii resources.

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

To systematically reveal the change of organs of Oplegnathus punctatus at its early stage of digestive system development, continuous histological sections of O. punctatus aged from 1 to 49 days were analyzed. The results showed that the digestive tract of 1-day-old O. punctatus was located inside the yolk sac and was only a simple tubular structure. The development of the digestive system of O. punctatus can be roughly divided into three stages. At 1~3 days of age, the digestive system was still in the primitive stage. At this age, the mouth fissure was closed, and only the yolk sac was used as the nutrient source, thus presented a complete endogenous nutrition. At 4~20 days of age, the digestive system was preliminarily developed, and it was in the transition stage with basic feeding, digestion and absorption capacity. At this stage, the mouth fissure opened, the yolk sac gradually disappeared, and the hepatopancreas developed rapidly. The fish gradually developed the ability to digest food. The transition to exogenous nutrition began. Tt 21 to 35 days of age, the digestive system developed further and the gastric glands appeared, forming a complete digestive system. After that, the tissues and organs of the digestive system only increased in cell scale rather than structural changes.

To explore the similarities and differences of different permeable plate breakwaters in terms of structural forces, this paper investigated a physical model tests of twin-flat-plate (TFP) and twin-arc-plate (TAP) permeable breakwaters in a wave flume. Under different diving depth conditions, the results indicated that the wave pressure distribution characteristics of the upper and lower plate of the TAP breakwater were markedly different. Except for the upper surface of the upper plate, the positive wave pressure on the TAP breakwater was less than the TFP breakwater for the 77.8% cases. Under the different submergence condition, the negative wave pressures on the upper surface of the upper plate of the TAP breakwater was greater than the TFP breakwater. The lower surface of the lower plate in the emerged state (h/d=-0.05) and at the still water level (h/d=0), except for the upper surface of the upper plate in the submerged state (h/d=0.05), the negative pressure on the twin-arc-plate breakwater was less than those on the TFP breakwater. The positive and negative vertical wave forces on the twin-arc-plate breakwater were less than those of the TFP breakwater, and the differs notably between the negative vertical wave forces. The results of this study could be used as a reference for the application of plate permeable breakwaters in engineering.

Due to the interference of human activities and the change of environment, the area of oyster reef in China keeps shrinking, which seriously affects the stability of marine ecosystem. To restore oyster reef, 440 mu of oyster reef was first established by oyster shell material in June 2021 in the intertidal zone of Yellow River Delta. Four months later, the development of oyster reef was investigated and analyzed. The results showed that the sinking depth of oyster reef varied between 15 and 20 cm, but the height of the whole oyster reef was above 1m; and the average oyster density on oyster reef was 0.216±0.128 ind/cm². The amount of oyster on the oyster shell was distinctly higher than that in bamboo rod and polyethylene rope. These results indicated that oyster shells are suitable for the attachment of oyster, and the reef based on oyster shells is suitable for oyster reef restoration in the intertidal zone of Yellow River Delta.

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

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

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

In this paper, the characteristics of the turbidity maximum zone (TMZ) in the Jiaojiang estuary before and after channel dredging and the influence of the TMZ on channel siltation were studied. Firstly, the hydrodynamic and sediment of the Jiaojiang estuary was numerically simulated, and the model could simulate the complex terrain and hydrodynamic sediment conditions well. Secondly, the mechanism of suspended sediment transport in the Jiaojiang estuary, the movement process of the TMZ and the changes after dredging were analyzed. The calculation of net sediment fluxes showed that the tidal pumping dominated the suspended sediment transport near the outer channel of the Jiaojiang estuary. The net sediment fluxes near sea side of channel were mainly in the sea direction, while that in the near land side were in the land direction. The TMZ moved back and forth with spring-neap tide and flood-ebb tide near the outer channel. The suspended sediment concentration (SSC) in the TMZ was the highest at the flood peak in a tidal cycle. After channel dredging, the position of the TMZ and SSC changed little, and there was always a high siltation area in upstream of the dredged channel.