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.

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.

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.

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 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.

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.

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

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

The 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.

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.

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.

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.

Based on the monitored information of seawater quality in the coastal areas of Hainan Province in 2020 and using principal components analysis, we identified the pollution factors dominating the change of seawater quality, characterized spatial-temporal distribution using N/P ratio and eutrophication index methods, and evaluated the nutrient structure and eutrophication level in the coastal areas around Hainan Island. The results showed that dissolved inorganic nitrogen and dissolved inorganic phosphorus are the main pollution factors in the coastal areas around Hainan Island in 2020, both are the highest in concentration in the normal water period. The pollution was mainly due to the terrestrial inputs. The concentrations of dissolved inorganic nitrogen and dissolved inorganic phosphorus in northern coastal areas were generally higher than those in southern coastal areas, especially in Haikou Bay and its adjacent sea areas, and Xinying Bay, where the pollution was mainly due to human activities and hydrodynamic forces. The highest concentrations of dissolved inorganic nitrogen and dissolved inorganic phosphorus appeared in Xiaohai of Wanning in the southern area where the pollution was mainly due to aquaculture activities and hydrodynamic forces. The coastal areas around Hainan Island is considered to be a potential eutrophic area with nitrogen limited, and the eutrophication level in the coastal areas around Hainan Island was generally low, only serious in regional areas, especially in Xiaohai of Wanning.

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.

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.

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.

According to the investigation data of heavy metals in seawater and surface sediments of the proposed marine ranching of Wailingding island, Zhuhai in spring and autumn of 2020, single-factor evaluation method, comprehensive pollution index method and potential ecological risk index method were used to evaluate the quality level of heavy metals. The results showed that the Cu content of very few stations exceeded the class II seawater quality standard, the comprehensive evaluation index of heavy metals in surface seawater of each station was less than 1, the comprehensive evaluation degree of heavy metals in seawater at S16 station was slightly polluted, and the rest stations were clean. There was obvious homology between Hg and As in surface seawater, and obvious heterogeneity among Pb, Hg and As. The content of heavy metals in surface sediments all met the quality standards of class I marine sediments, and heavy metals in sediments had only slight potential ecological risks to marine ecosystems. There were slight potential ecological risks of heavy metals in surface sediments, and the construction of artificial reefs could form an upwelling and proliferating artificial reef system, which was conducive to eliminating the potential ecological impacts brought by heavy metals in surface sediments.

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.

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.

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.

Heavy metal pollution seriously affects the ecological environment and human health. In order to scientifically manage the heavy metal pollution, it is necessary to explore the law of heavy metal migration and transformation in the river basin and predict the whereabouts of heavy metal migration. In this study, the migration and transformation processes of heavy metals in the basin and the main influencing factors were summarized. The literature on the migration and transformation model of heavy metals in the basin was analyzed, the existing models, the research progresses and application of each model were summarized, and the future research direction of the model was prospected. The results showed that the heavy metals simulated by basin heavy metal models were limited and the simulation processes were mainly concentrated between surface water and soil. Future development directions of heavy metal watershed models include adding Tl, Co and other heavy metal simulation modules, improving the migration processes of heavy metals in groundwater and between organisms, and increasing the function of dynamic change of external environment such as land use type and soil physical and chemical properties.

River capture is an important issue in Quaternary geology and geomorphology, which has been widely concerned by scholars at home and abroad. In the upper reaches of the Chaiwen River in Yiyuan, Shandong, a river capture event occurred in the late Pleistocene, and the typical and complete river capture geological remains are still preserved. On the basis of field investigation and high precision DEM data, this paper studies the types, characteristics and causes of typical river capture geological relics resources in this area, and makes a comprehensive quantitative evaluation of river capture geological relics resources by using analytic hierarchy process. The results show that there are 1 world-class, 4 national, 3 provincial and 2 local level geological relics in the upper reaches of The Chaiwen River in Yiyuan, Shandong province. The comprehensive quantitative evaluation of the geological relics resources captured by rivers in this area has reference value for correctly understanding the evolution of the geomorphology captured by rivers, protecting and developing the geological relics resources, and promoting the development of local tourism economy.

High-quality marine management talents are an important guarantee for the development of marine programs, while improving the level of marine management disciplines construction is the fundamental way to cultivate talents. However, there are still some gaps in the research on the disciplinary orientation, development status and evaluation system of marine management disciplines in China. Therefore, the disciplinary orientation of marine management disciplines was clarified in this paper and the construction status of marine management disciplines in China was briefly sorted out. Then, the marine management disciplines evaluation system was initially constructed, including 4 primary indicators and 13 secondary indicators, and the index weight was determined by the analytic hierarchy process. Finally, based on systematic and scientific induction analysis, several suggestions for improving the construction of marine management disciplines in China’s universities have been put forward, to provide theoretical support and practical guidance for the construction of marine management discipline.

(Objectives) Recreational fisheries development is an important part of advancing the modern fishery construction, as well as an important measure to implement the strategy of rural revitalization and build a powerful marine economy. The evaluation of recreational fishery competitiveness is an important basis for guiding its development. (Methods) In this research, we draw on the relevant theories of economic competitiveness to analyze the concept of recreational fishery competitiveness using a combination of qualitative and quantitative analysis methods, and the process of building-optimizing-testing index system to construct an evaluation index system for the recreational fishery competitiveness of China. (Results) (1) The competitiveness of recreational fishery is a comprehensive reflection of the development strength and development potential of a regional recreational fishery, including the four core elements of economic growth, resource endowment, service industry development level, and consumer market; (2) Competing for fishery resources 11 indicators in four aspects, competitiveness, industrial competitiveness, service competitiveness, and leisure demand competitiveness, to construct a recreational fishery competitiveness evaluation index system; (3) According to correlation analysis, eliminate linearly related repeating indicators, and coefficient of variation analysis eliminates weak discriminative power. Qualitative analysis retains the characteristic indicators of the recreational fishery industry. This qualitative and quantitative method has good applicability in the evaluation of recreational fishery competitiveness. (Conclusion) In this study, we believe that the construction-optimization-testing process of recreational fishery competitiveness index system is reasonable. The optimized index system eliminates the repetitive index and the weakly identifiable index, the competitiveness evaluation result is more objective, and the index reflecting the characteristics of the recreational fishery industry is retained based on the qualitative evaluation.

As one of the economically important cephalopods with obvious diurnal vertical migration characteristics, the jumbo flying squid Dosidicus gigas abundance and habitat distribution are largely affected by the change of vertical water temperature in the habitat. In this study, the maximum entropy model was used to select the water temperature at the depths of the key water layers in each months according to the contribution rate, using the fisheries data of Dosidicus gigas off Peru from January to December during a period from 2006 to 2015 and the water temperature data at different water layers (0, 50, 100, 150, 200, 300, 400, 500, 750, 1000 m). According to the response curves of this squid to key water temperature factors, we further obtained the suitable temperature range at the key water layers in each months, analyzed the monthly variations in the water temperature factors at the key water layers, and identified the potential habitat distribution map in peak fishing season (September to February). The results showed that the water temperature factors at the key water layers in each months strongly affected the temporal and spatial distribution of squid habitat off Peru, especially the water temperature at the depths of 0, 50, 100, 150 m co ntributed the main impacts. The suitable water temperature range at the key water layers changed from month to month. The temporal and spatial distribution of the potential habitat of D. gigas was consistent with the movement of the longitudinal and latitudinal gravity centers of the fishing ground. Both moved southwestward with the month. Our findings suggested that the habitat of D. gigas off Peru sea was affected by the water temperature above the depths of 150 m, and the temporal and spatial distribution of the habitat could be well modeled using the vertical water temperature between 0 and 150 m.

Under the background of rapid urbanization, this paper analyzed the temporal and spatial distribution changes of landscape pattern and habitat quality in Nanhui Dongtan coastal zone of Shanghai, so as to provide a theoretical basis for ecological environment protection and policy planning in the coastal zone. Based on the land use data of Nanhui Dongtan coastal zone interpreted by remote sensing in the years of 2013, 2015, 2017 and 2019, the landscape pattern of Nanhui Dongtan coastal zone in 2021 and 2023 was predicted by MCE-CA-Markov model combined with the actual environment, and the spatio-temporal evolution characteristics of habitat quality in the study area from 2013 to 2023 were analyzed by InVEST model. From 2013 to 2019, the main landscape types in the study area were construction land and tidal flat. The area of sea water, forest land and cultivated land decreased year by year. The part of cultivated land decreased was mainly transformed into construction land, and the area of sea water decreased was mainly transformed into tidal flat. The index of habitat quality in the study area decreased year by year, and the overall habitat quality decreased, and a large number of high habitat areas in the east changed to medium habitat. From 2019 to 2023, the landscape pattern and habitat quality of Nanhui Dongtan coastal zone continued to maintain the change trend from 2013 to 2019, mainly reflected in the increase of construction land area and the decline of habitat quality. The main reason for the decline of habitat quality and the change of landscape pattern in the study area was the economic activities of human society, in which the development of urbanization was an important factor in the landscape ecological change of Nanhui Dongtan coastal zone.

Reclamation, as a way to broaden the land space for development, plays a positive role in social and economic development, whereas it will lead serious threat to marine ecological environment. From strong support to strict management and control, China has paid more and more attention to the ecological problems caused by reclamation. However, the one-size-fits-all policy had made a large number of reclamation projects which became historical problems to be solved. This paper reviewed the case of Yue island project in Wanning city, Hainan province and analyzed the causes of historical and problematic reclamation, mainly including: (1) imperfect, conflicting and insufficient laws, regulations policies and systems; (2) government’s ineffective supervision, failure to enforce the law and act of substituting punishment for custody; and (3) weak legal consciousness, insufficient social responsibility consciousness, weak awareness of the ocean in the society. Based on the cause analysis, relevant countermeasures and suggestions for prior prevention, in-process supervision and post-processing were put forward, in order to help solve the historical problems of reclamation properly.

Using the random point process method, this paper made a statistical analysis of the large wave process in the northern Yellow Sea with an effective wave heights of 2.5 m ~ 4.0 m in 30 years (1988-2017), and obtained the statistical laws of cold air cyclone waves and cold wave waves in the northern Yellow Sea from November to next April, and estimated the number of large wave processes in this period. Using the compound extreme value distribution, the represent value of wave heights for 100A and 50A return periods in this period was calculated. The results showed that the large wave process with an effective wave height of 2.5 ~ 4.0 m in the northern Yellow Sea from November to next April was a homogeneous Poisson process, and the extreme wave heights of 100 year return period was about 8.0 m. The research results can provide reference for the research of wave disaster and the engineering design of offshore buildings in the northern Yellow Sea.

As necessary support for coastal engineering, non-submerged pile foundation greatly affects the coastal hydrodynamics and ecological environment. Taking Hangzhou bay as an example, we analyzed the influence of non-submerged pile foundation on the tidal dynamics and suspended sediment characteristics using a three-dimensional hydro-sediment numerical model. The results showed that before and after the construction of pile foundation, the distribution of the suspended sediment concentration (SSC) correlated with the currents. Owing to the blocking effect of pile foundations, there was an obvious cylindrical disturbed flow around the piles. The bridge blocked water and formed a low-flow negative pressure zone at the back side, and increased the order of vorticity near the pile foundation; the flow velocity and SSC increased between the pile foundations. The bridge affected the tidal phase and thus the tidal level and tidal asymmetry. The peak and ebb current direction was basically perpendicular to the axis of the bridge. Variations in the near bottom velocity changed the bottom stress, which affected the sediment resuspension and thus changed the SSC. The construction of the bridge accelerated/slowed down the southward sediment flux on the sea/land side. Turbine piles in the open ocean had similar effects with smaller magnitudes.

We investigated the variation of tintinnid communities in Changjiang River estuary in Jun., 2019 and Dec., 2020), and Dachen Island sea area in Nov., 2020 and Apr., 2021. A total of 83 samples were collected. (1) Eighteen tintinnid species belonging to 9 genera were observed, and the total abundance ranged from 0 to 618 ind./L. (2) Lorica oral diameter (LOD) of the 18 tintinnid species varied between 14.5 and 96.4 μm, and were grouped into 8 size classes. (3) Tintinnid abundance in Dachen Island sea area was significantly and positively correlated to temperature and chlorophyll a concentration (p<0.01) but significantly and negatively to salinity (p<0.01). (4) There were more redundant species and LOD size classes in Dachen Island sea area than in Changjiang River estuary. The existence of redundant species should increase the capability of a community to exploit changes in conditions, leading to the speculation of more stable tintinnid communities in Dachen Island sea area. Our findings provided basic data for further studies on the microbial ecology of Changjiang River estuary and its adjacent areas.

The concentration of nutrients such as nitrogen and phosphorus in water, sulfide content in sediment and dissolved oxygen content in water may be the limiting factors for aquaculture capacity in baiting type offshore cage aquaculture. However, studies on nitrogen, phosphorus, sulfide content in sediment and other limiting factors are all based on the perspective of meeting environmental standards. From the perspective of aquaculture itself, the content of dissolved oxygen is often the key factor to control aquaculture density and limit aquaculture capacity. For this purpose, A dimension analysis model of dissolved oxygen was established and the aquaculture capacity of Trachinotus ovatus was calculated as an example in Houshui bay offshore cage aquaculture in this paper. The results showed that the theoretical cage culture capacity of Trachinotus ovatus was about 22500 tons. Compared with the existing fish production, it can be seen that the aquaculture capacity has reached saturation in Houshui bay offshore cage aquaculture. According to the results of the aquaculture capacity and the proportion of current cage culture specifications, the estimated number of cages with a circumference of 40 m and 60 m were about 2127 and 435, respectively, and the total number was about 2562 which could be judged that the number of cage culture in Houshui bay has also reached saturation, and it was not suitable to be further developed. Due to the limitations of each method, the aquaculture capacity should not be exceeded in practice, and the number of cage culture could be comprehensively considered according to the calculation results of the two methods. The development trend was to eliminat cages with 40 m circumference year by year and developed large-scale cages, which could not only reduced the number of cage culture, but also reasonably adjusted the density of single cage according to the aquaculture capacity, so as to obtain the maximum economic and environmental benefits.

Based on the simple frame reef, a square diagonal plate separated reef was improved in this paper. In order to study its beach protection effect, the flow blocking effect, flow field effect and local scour condition were analyzed by the combination of physical test and numerical simulation. The experimental results showed that the new reef had different blocking effects under different upstream angles, and the angle arrangement of 0 upstream was obviously better than that of 45. At a distance of the length of reef from the center of the reef, upwelling began to appear. The ratio of maximum rising velocity to incoming velocity hardly changed with the change of incoming velocity. In a certain range, the smaller the opening of the reef, the better the flow blocking effect; the more obvious the internal vortex, the more obvious the water exchange between different layers, and the richer the flow field. The flow and sediment movement around the reef was complex, and the dynamic scouring equilibrium was reached about 2 h when the inflow velocity was controlled at 0.35 m/s. Therefore, when launching this type of reef, the opening size should be reduced as much as possible and the 0°upstream layout should be selected as much as possible, so as to achieve the best effect.

A strain of benthic algae was isolated from the sediment samples collected in Danjiangkou Reservoir using dilution separation and small droplet separation methods. Based on morphological observation and homologous analysis of 18S rDNA, LSU rDNA and rbcL sequences, the strain of diatom SG0529 obtained from Danjiangkou Reservoir was identified as Navicula cryptocephala. Using sodium nitrate, ammonium chloride and urea as nitrogen sources, the change characteristics of the growth and chlorophyll fluorescence parameters (Fv/Fm, α, Ik, ETRmax) of N. cryptocephala under different nitrogen conditions were analyzed. The results showed that the strain of N. cryptocephala grew normally in sodium nitrate, ammonium chloride and urea medium, but the responses to different nitrogen forms were quite different. In sodium nitrate and urea medium, the specific growth rate and the cell density of N. cryptocephala increased with increment of nitrogen concentration. Under ammonium chloride culture condition, the growth rate of N. cryptocephala increased firstly and then reduced as nitrogen concentration increased in culture medium. With the increase of sodium nitrate and urea concentration, the photosynthesis performance of N. cryptocephala increased, and the high concentration of ammonium chloride condition inhibited its photosynthesis reaction, indicating that increasing the concentration of nitrogen within a certain range is beneficial to the growth of N. cryptocephala, improving its photochemical reaction, and high concentration of ammonium nitrogen inhibited its growth and photosynthesis reaction. Compared with ammonia and urea, nitrate was more able to promote the growth of N. cryptocephala. Under the condition of nitro nitrogen culture, the maximum cell density and growth rate of N. cryptocephala are optimal. In addition, N. cryptocephala improved the rate of PSII electron transfer, accelerate the use of light energy, to provide energy for the absorption of nitrate. Moreover, N. cryptocephala improved α value to increase the utilization efficiency of light energy in response to nitrogen deficiency with the consumption of nitrogen for resisting adverse conditions. Our findings provided not only an experimental basis for the molecular identification of N. cryptocephala in fresh water, but also basic data for water quality protection and ecosystem management in Danjiangkou Reservoir.

Effects of Cu²⁺ and ocean acidification on the photosynthesis of Phaeodactylum tricornutum have been widely studied, but the studies on their coupling effects are less. The effects of different CO₂ concentration (400 and 1500 μatm CO₂) on the specific growth rate (μ), photosynthetic pigment content and photosynthetic performance of P. tricornutum under different Cu²⁺ concentrations (0.1, 0.25, 0.5 mgL^-1Cu²⁺) were measured. The results showed that the μ, photosynthetic pigment (chlorophyll A and C) content, maximum photochemical quantum yield (Fv/Fm), maximum relative electron transfer rate (rETRmax), energy captured per unit reaction center for electron transfer (ETo/RC) and energy captured per unit reaction center for electron transfer to the PSI electron acceptor side (REo/RC) were inhibited by 0.5 mgL^-1 Cu²⁺ under 400 μatm CO₂ condition, respectively. These parameters were significantly lower than those at 1,500 μatm CO₂ (p<0.05), respectively. Our findings suggested that high concentrations of Cu²⁺ not only restricted the growth of P. trichodensis but also inhibited the activity of photosystem II (PSII) while ocean acidification alleviated the these inhibitions. In the coastal waters where ocean acidification and heavy metal pollution are more serious, ocean acidification could improve the tolerance of P. tricornutum to Cu²⁺ and assist it to survive the complex and changeable environment.

The contents of carbon, nitrogen and phosphorus of Saccharina japonica at different growth stages are of great ecological significance to reveal the material circulation and energy flow. Through field investigation and indoor analysis, we measured the contents of C, N, P and the environmental characteristics of aquaculture waters at different growth stages of cultured S. japonica in Xihu harbor. at different growth stages, the content of C in S. japonica ranged from 37.62% to 38.62%, with an average of 37.98 ± 0.38%. With the growth of seaweed, the contents of N and P decreased gradually. N content ranged from 2.33% to 4.25% with an average of 3.33 ± 0.75%. P content varied between 0.15% and 0.30% with an average of 0.20 ± 0.06%. The N / P of seaweed remained stable, with an average of 14.54 ± 1.31. C / N and C / P increased gradually with the growth of S. japonica. The C / N ranged from 9.10 to 16.43 with an average of 12.10 ± 3.00, and C/P ranged from 126.50 to 248.53 with an average of 175.10 ± 51.51. The contents of nitrogen and phosphorus in S. japonica respond significantly to environmental factors and growth characteristics. The main factors are salinity, pH and nutrients. The changes of C / N and C / P reflect that the nutrient utilization efficiency to N and P increases with the rapid growth of S. japonica.

In this study, we investigated the abundance and distribution of dissolved inorganic phosphorus (DIP) in Meishan bay. We collected water samples from the bay and its sediments (16 stations in the bay and the cecum segment) as well as the input rivers (15 stations in estuaries entering the bay) during the summer of 2019. The dissolved inorganic phosphate was mainly analyzed to reveal the spatial distribution characteristics in the surface water, overlying water, and sediment pore water in Meishan bay and the estuary. Our results showed that the content of dissolved inorganic phosphorus in the estuary and cecum of Meishan bay was generally higher than that in the bay implying riverine transportation as a possibly major external source of phosphorus. Moreover, the P levels in the sediment pore water of the estuary and cecum were overall higher than the overlying water. Our estimation using Fick’s First Law showed that the dissolved inorganic phosphorus would tend to diffuse from the sediment to the overlying water, and the average diffusion flux was on average 0.39 μmol·m^-2·d^-1 (estuary) and 0.98 μmol·m^-2·d^-1 (cecal segment). Therefore, the sediments may be an important source of dissolved inorganic phosphorus in the bottom water. The overall diffusion flux of dissolved inorganic phosphorus in the Meishan bay sediments was smaller than that of other sea areas and estuaries. Thus, our data suggests that the P pollution of the Meishan bay sediment was relatively lighter than its counterparts.

Weihai has rich beach resources which are very suitable for the development of coastal tourism. Beach quality evaluation is an important basis for the further development of coastal beaches. Based on analytic hierarchy process (AHP) and Fishbein-Rosenberg model, in this study, we established a quality evaluation system suitable for Weihai tourist beaches by collecting the data of 14 Weihai tourist beaches. The system consisted of three categories, beach tourism social factors, beach dynamic characteristics and safety, and beach natural resource conditions, included 22 evaluation factors, and was divided into five levels. The quality evaluation results of 14 beaches in Weihai showed that a good average score of social factors of beach tourism, 76.59, a excellent average score of beach dynamic characteristics and safety, 83.94, and an average score of beach natural resource conditions, 81.20, of 14 beaches, 9 excellent, 3 good and 2 qualified. The existing tourist beaches in Weihai have superior natural conditions and high safety. The existing problems are mainly social factors, such as low degree of supporting service facilities and less leisure and entertainment projects. According to the evaluation results, some suggestions on the development of tourist beaches in Weihai were put forward.