To elucidate the species composition of fishes in the Langhua Reef of Xisha Islands, reveal their evolutionary traits, and ensure the protection and sustainable use of coral reef fishes in this region, a comprehensive survey was conducted in 2023. Employing techniques such as dive-fishing, hand-fishing, underwater videography, and environmental DNA (eDNA) analysis, this study integrated historical data from 1979, 1998—1999, and 2003 to analyze the species composition and temporal fluctuations in the fish population of the Langhua Reef. To date, a total of 259 fish species have been identified in the reef, classified into 12 orders, 47 families, and 115 genera. Among these, the most populous are the perch-like species, accounting for 200 varieties. The results indicate an exponential relationship between the number of fish species in the reef and their corresponding maximum overall length, with a significant decline in species count as the maximum length increases. Predominantly, the reef is inhabited by small-sized and carnivorous fish, constituting 49.03% and 59.07% of the total species, respectively. The 2023 survey highlighted that 77 fish species, previously recorded in historical data, have not been observed in recent years, predominantly among carnivorous types. Notably, almost all large fish in the reef are carnivorous. Seven species, listed on the IUCN Red List and categorized as large fish, were absent from the current study, with the exception of the brown-spotted grouper (Epinephelus fuscoguttatus).The species composition, dietary patterns, and historical similarity indices of the Langhua Reef fish varied significantly, especially among large and carnivorous species, which demonstrated the lowest similarity indices. Furthermore, the study revealed a downward trend in both the mean taxonomic distinctness index (Δ⁺) and the variance in taxonomic distinctness index (Λ⁺), falling significantly below the 95% confidence intervals. These findings suggest that environmental disturbances, climate change, and human activities have led to a notable turnover in the fish composition of the reef, with large carnivorous species being the most severely affected. This research provides a theoretical reference for a deeper understanding, effective management, and conservation of the Langhua Reef coral reef ecosystem. It also offers foundational data and scientific insights crucial for the restoration of the coral reef ecosystem.

With the growing global demand for clean energy, hydrogen energy, as an important renewable energy reserve, has garnered widespread attention for its storage technology. Onshore hydrogen storage systems pose risks such as hydrogen leakage, drinking water contamination, and catastrophic injuries. In contrast, offshore geological environments are relatively stable and well-sealed, leading to widespread attention to and rapid development of offshore hydrogen storage technology. Currently, the main underground gas storage technologies include salt caverns, aquifers, and depleted oil and gas reservoirs. Salt cavern gas storage has been operating for many years in Europe and the USA and has a relatively mature technical foundation. However, there are no suitable locations for constructing salt caverns along China’s coast, which limits the build-up of salt cavern hydrogen storage to inland regions. However, China’s coastal areas have abundant underground aquifers and oil and gas reservoirs, necessitating timely related geological research to promote the development and application of relevant technologies in different marine areas and the comprehensive development of the hydrogen energy industry. Developing offshore hydrogen storage technology requires not only integrating the unique geological conditions of the margin with the special physical and chemical properties of hydrogen, but also considering geological, hydrological, biochemical, and mineralogical factors to ensure a rational planning and safe operation, in addition to using the latest geophysical methods in site selection. Looking ahead, offshore hydrogen storage technology will not only provide theoretical support for the development of renewable energy technologies in China but also play a significant role in promoting a low-carbon, green, and sustainable development.

The global carbon and nitrogen cycles depend heavily on deep-sea microorganisms, and the majority of current, refined research on these organisms is based on high-pressure simulation culture and detection in laboratories. However, when deep-sea samples are brought in for culture and detection, the environmental parameters, such as temperature, pressure, etc, change at various degrees, which has an impact on the results of subsequent experiments and detection. For this reason, a device (ocean automatic series incubation system, OASIS) was developed for in situ automatic series incubation of deep-sea microorganisms. This research emphasizes the accuracy of deep-sea liquid transfer and focuses on the OASIS operating concept, system design, and experimental validation. The device can function normally under 30 MPa high pressure, and it can automatically finish the culture of microorganisms and the fixation of life information in accordance with the chronological order. These test results demonstrate that OASIS has passed the pressure, sea, pool, and other tests. They also accurately provide an understanding of the ecological benefits of deep-sea ecosystems. It offers strong equipment assistance for precisely identifying the ecological advantages of deep-sea environments.

Using in-situ data collected by summer cruises during 2021−2023, summer hydrological variations and their influencing factors were studied. The results show that the summer temperature and salinity were charactered by northeast-southwest distribution pattern, while variations in values were significant during the investigation. Mean sea surface temperature (SST) was lowest in 2021 but highest in 2022. Bottom temperature was highest in 2021, but moderate in 2022 and lowest in 2023. Strong runoff caused a significant outward expansion of diluted waters, sea surface salinity (SSS) was strikingly lower in 2022 than those in 2021 and 2023. Bottom salinity was highest in 2023, moderate in 2021 and lower in 2022. Temperature and salinity variations in the middle and low layers were related to the passage of typhoons and invasion of shelf cold and saline water. Those vertical temperature and salinity observed after Typhoon Lupit passed in 2021 mixed homogeneously, weakening stratification. Bottom shelf water intruded into the Lingding Bay, forming a low-temperature zone and apparent salinity front. Middle and bottom temperature (salinity) decreased (increased) owing to the enhanced bottom shelf water intrusion in sequence in 2022 and 2023. In 2023, strong upwelling inhibited the expansion of diluted water seaward to increase SSS over the shelf higher than those in 2021 and 2022. Bottom temperature and salinity varied with the tide, in which the shoreward movement of cold and saline water tended to decrease temperature and increase salinity during flood tide, while the opposite occurred during ebb tide. The positive correlation between SST and air temperature suggested that SST varied with air temperature.

The structure of phytoplankton community was investigated based on morphological identification and high-throughput sequencing in the Nan’ao waters in May 2022. The spatial distribution of phytoplankton in relation to environmental factors was explored and results from two different methods were also compared and discussed. According to the cluster analysis of environmental factors, the survey area can be divided into nearshore area and offshore area. Totally, 105 species belong to 52 genera, 39 families, 27 orders, 8 orders, 5 phyla were morphological identified, while 543 species in 6 phyla, 32 orders, 97 families, 155 families, 272 genera through high-throughput sequencing were identified. Bacillariophyta and Dinophyta were the main groups, composing 74.54% and 24.78% through microscopic identification, and 17.52% and 67.84% through high-throughput sequencing, respectively. The abundance of phytoplankton identified by morphology ranged from 0.11×10⁵ to 6.85×10⁵ cells·L^-1, which was significantly correlated with the distribution of chlorophyll a concentration, and the phytoplankton diversity index was lower than that of the high-throughput sequencing method. 7 dominant species were obtained by both methods, of which the absolutely dominant specie in the morphological identification results was Chaetoceros compressus, and the absolute dominant specie in the high-throughput sequencing identification results was Heterocapsa rotundata. Correlation analysis showed that the main environmental factor affecting phytoplankton community structure in Nan’ao in spring was pH, salinity and DIP (dissolved inorganic phosphorus). Using the combination of morphological identification and high-throughput sequencing technology, the structure and diversity of the phytoplankton community can be described more comprehensively and accurately.

Based on mooring data deployed west of the Xisha Islands from October to November 2020, we investigated the characteristics of near-inertial waves (NIWs) triggered by three consecutive typhoons in detail, including the decay time scales and vertical structures of the NIWs, as well as the modulation of the background vorticity and current fields on the NIWs, etc. The vertical wavelengths of NIWs induced by Typhoon Saudel, Molave and Vamco are 109 m, 133 m and 117 m, respectively, and the vertical group speeds are 29 m·d^-1, 26 m·d^-1 and 18 m·d^-1, respectively. The decay time scales for these internal waves are 3 d, 7 d and 15 d, respectively. It reveals that ocean stratification significantly impacts the vertical group speed of NIWs. The longest decay time in the Vamco case is attributed to the second EOF (empirical orthogonal function) mode of NIW propagated from far field. The results of the dynamical mode decomposition (DMD) and EOF are consistent with each other. Both show that the first modes contribute the most to near-inertial kinetic energy (NIKE), and the distributions of NIKE in different modes obtained from DMD and EOF are comparable. For example, the NIKE is mainly distributed in the first, third and second DMD modes at depths of < 100 m, 100~150 m and 150~350 m. The observed frequencies of the NIWs are all blue-shifted, and the blueshifts in Typhoon Saudel and Molave are due to the combination of the background current and vorticity, while the positive background vorticity due to the cyclonic eddy during the Vamco is the main reason for the observed blueshift. Our results are useful for a deeper understanding of the characteristics, propagation, dissipation and energy distribution of strong wind-induced NIWs and their mechanisms, and they also provide a good reference for numerical simulations.

Using conventional observations and ERA5 reanalysis data, a diagnostic analysis of the thermal and dynamical characteristics of a heavy rainfall process in the eastern coastal area of Shandong on June 14, 2022, was conducted, and the results show that the heavy rainfall process occurred in the context of the cold trough at the bottom of the cold vortex in North China moving eastward to the coast of the Peninsula to induce a cold low vortex. Southeasterly cold and humid advective transport in the boundary layer from the Yellow Sea provides abundant water vapour for the heavy precipitation on the peninsula. The precipitation process was stage-specific. In the first stage of precipitation, the low level was continuously influenced by the western warm advection, and the atmosphere had convective instability, while in the second stage of precipitation, the atmosphere was gradually transformed from neutral laminar junctions to convective instability by the combined influence of the cold and warm advection, and was accompanied by obvious energy fronts. The early stage of both phases of precipitation is caused by the convergence of onshore wind speeds as well as topographic uplift. The cold pool caused by convection in the first stage has an important effect on the maintenance of precipitation in front of the Kunshan Mountains, while the maintenance of the strong precipitation in the second stage is closely related to the generation and maintenance of the mesoscale low eddy in the low altitude, and the obliquely pressurized frontal generation plays an important role in the generation of the mesoscale low eddy. The vorticity analysis shows that the boundary layer low-level convergence and absolute positive vorticity advection are the main vortex sources for the positive vorticity growth of the mesoscale low vortex, and with the emergence of the 500 hPa cutoff cold vortex, the negative effect of the vertical transport of vorticity is obviously strengthened, and the horizontal vorticity tilting effect above the boundary layer, which is related to the mesoscale convective activity, is weaker.

Typical tropical marine ecosystems are composed of unique habitats and organisms, such as coral reefs, mangroves and seagrass beds. These ecosystems are mainly distributed in tropical and subtropical marine areas worldwide. It is characterized by high material cycling efficiency, unique ecological functions, rich biodiversity and extremely high productivity, and thus a key object of marine scientific research and resource utilization. Under the multiple pressures of human activities and global changes, its degradation trend has become increasingly prominent. How to restore the function of these typical ecosystems and maintain their sustainable development for the benefit of mankind has attracted increasing amounts of attention from the academic community and the international society. In this paper, the distribution patterns, degradation trends and influencing factors of such typical marine ecosystems in the world are described, with an emphasis on the distribution patterns and biodiversity characteristics of coral reef, mangrove and seagrass bed ecosystems in China. Focusing on coral reef ecosystems, this paper discusses the causes of degradation in the ecosystems and relevant action measurements for restoration and protection in China. According to the global action plan for biodiversity conservation and the actual situation of China, countermeasures and suggestions for the restoration, reconstruction and protection of the typical marine ecosystems were proposed: 1) Establishment of a research center for typical ecosystems in the South China Sea, an intelligent monitoring system and database, and an expert think tank; 2) establishing a demonstration zone for the restoration and protection of the typical marine ecosystems, and inviting experts from multiple disciplines to work together on research-experimentation-demonstration-estimate--promotion-monitor; and 3) optimizing policies and regulations, strengthening law enforcement and management, increasing efforts in science popularization and education, raising public awareness of environmental protection, and promoting conscious social actions. This study aims to provide references for strengthening the conservation and management of typical marine ecosystems and biodiversity, maintaining their sustainable development and implementing the 30×30 goals of the Kunming-Montreal Global Biodiversity Framework.

There are rich fishery resources and complicated hydrologic environment in the coastal waters of eastern Guangdong. In order to systematically improve the level of oceanic observation and the knowledge of ecological dynamic processes in the coastal waters of eastern Guangdong under the changing climate, a comprehensive investigation of ecological and environmental factors such as hydrodynamics, biology and chemistry during four seasons was carried out in May (spring), July (summer), October (autumn) 2022 and January 2023 (winter). Based on the taxonomic identification of zooplankton, the characteristics of community structure of zooplankton in the surveyed area were analyzed, and the effects of environmental factors on their spatial and temporal distribution were discussed. According to the environmental parameters, the survey area can be divided into the near-shore (mainly affected by human activities) and off-shore (mainly affected by ocean currents) areas, and the zooplankton were characterized by the seasonal and regional pattern. Seasonally, the species, biomass and abundance of zooplankton in spring and summer were higher than those in autumn and winter. Regionally, the species, biomass and abundance of zooplankton in the off-shore waters are generally higher than those in the near-shore waters. Moreover, there are differences in the contribution groups and dominant species to the total zooplankton abundance in different seasons in the off-shore waters. Although copepods and chaetognaths were the main groups of zooplankton, the abundance of planktonic larvae and fish eggs in spring was higher than in other seasons, and the peak value is concentrated in the southwestern Hanjiang Estuary, indicating that this surveyed area was still an important spawning ground in the coastal waters of eastern Guangdong. The increase in copepods species and abundance in summer is related to the high chlorophyll a concentration improved by coastal upwelling in eastern Guangdong. Warm-temperate species carried by Fujian and Zhejiang coastal currents in winter are the main contributors to zooplankton abundance. Although chlorophyll a concentrations are higher in the near-shore waters, zooplankton species, biomass and abundance are lower. Under the effect of anthropogenic activities and climate change, long-term systematic monitoring and analysis of the response of zooplankton to the dynamics of the marine environment are needed in the coastal waters of eastern Guangdong.

The health of aquaculture ecosystem and the ecological effects of aquaculture activities have been paid increasing attentions in recent years. As an important part of marine aquaculture ecosystem, ciliates play a key role in matter cycling and energy flow in aquaculture water. In this paper, the research progress about ciliates in mariculture water was reviewed. The biodiversity of ciliates, ciliates diseases, the impact of aquaculture activities on ciliates, and the indication of ciliates to aquaculture environment were introduced. In addition, the limitations of past studies are considered, and the potential research hotspots are prospected for ciliates in aquaculture. This review is aimed at providing some updated information on the ecological effects of mariculture and offering available reference for further understanding the ecological role of ciliates in mariculture.

Pisodonophis cancrivorus is an important fish species in the southeast coast of China. In this study, the complete mitochondrial genome of P. cancrivorus was obtained by high-throughput sequencing technique, as well as the structural characteristics and phylogenetic relationships were also analyzed. The total length of the complete mitochondrial DNA is 17650bp, and the base compositions are A (31.72%), G (15.58%), T (26.26%) and C (26.44%), respectively, showing an obvious anti-G bias and A+T preference. Similar to the published mitogenomes of Ophichthidae species, some genes have undergone a tandem duplication-random loss (TDRL) event due to the natural selection, causing the ND6 gene and its conjoint tRNA-Glu(E) to be translocated between tRNA-Thr(T) and tRNA-Pro(P). Besides, another D-loop region with length of 966bp is located upstream of the ND6 gene, and these two D-loop regions show a trend of independent evolution. There are two start codons (ATG, GTG) and four stop codons (TAG, TAA, TA-, T--) among the 13 protein-coding genes (PCGs), and only COI gene is initiated with GTG. In the total of 3 824 encoded amino acids, the content of Leu is the highest, while the content of Cys is the lowest. There are 17 DNA mismatches in the secondary structures of 22 tRNAs. All tRNAs can form the clover-leaf structures, excepting tRNA-Ser^AGY(S) because of lacking the DHU arm. The origin of L-strand replication region (O_L) with the length of 21bp is situated in the “WANCY” region, and the conserved motif 3'-GGCGG-5' is detected in the 3' end of its hairpin secondary structure. The sequences of 12 PCGs (without ND6) are concatenated by removing stop codons, and the interspecific genetic distances of 17 Ophichthidae fishes are calculated to be 0.128-0.297 based on the Kimura two-parameter (K2P) model. The phylogenetic trees constructed by the maximum likelihood (ML) and Bayesian inference (BI) methods show a complex evolutionary relationship of Ophichthidae fishes. P. cancrivorus is located at the base of the phylogenetic tree and closely related to Ophichthus brevicaudatus and O. evermanni, suggesting that it may diverge later than other snake eels.

In this experiment, the conditions for amplifying polyp populations and strobilation of Phyllorhiza sp. were studied. The asexual reproductive process and the metamorphosis of ephyra into medusa were observed and described. Phyllorhiza sp. is characterized by two asexual reproduction modes: swimming buds and strobilation. Polyps can be permanently stored in laboratory. Both the producing swimming buds and strobilation can be observed at 20~25°C. It takes 10~12 days for metamorphosis to mature polyps after swimming buds attachment. It takes 2~3 days to produce swimming buds for polyp asexual reproduction. Monodisc is the strobilation mode of Phyllorhiza sp. and it takes 4~5 days before the ephyra gets rid of the residual polyp. The edge of the central disc of strobila keeps blue-purple from the formation of rhopalia to the disappearing of polyp tentacles. It takes 12 days for ephyra to develop into juvenile medusa under 25°C, 29‰~32‰ (salinity).

The marine engineering survey focuses on the geological hazards that threaten the marine engineering. In the process of moving towards the deep water, it has also been found that several unique geological phenomena, distinct from shallow water areas, have a certain impact on the positioning of drilling platforms, the design of jacket platforms and floating platforms, and the optimization of submarine pipeline and cable routes. Based on the results of many deepwater well site surveys and deep-water oil and gas field development project surveys, this paper expounds the characteristics of deep-water geological hazards, the methods of research and evaluation and the impact on marine engineering through the results of engineering geophysical survey, engineering geological survey and marine environmental survey, and provides a better idea for the investigation and design of deep-water marine engineering. The researches show that the deep water is widely developed with sand waves, scarps, hard seabed, faults, submarine canyons, mass transport deposits and other geological disaster phenomena. When conducting engineering geophysical survey, the use of autonomous underwater vehicle (AUV) and other survey methods to obtain centimeter resolution survey results can effectively reduce the observation period of seabed sand wave movement rate, and obtain more accurate water depth topographic data to support the marine engineering design. Combined with the shallow soil sample results and shallow profile results of the engineering geological survey, the seabed strata can be effectively divided and the slope stability analysis can be carried out, providing the design basis for the offshore engineering construction.

The seaweed bed composed of macroalgae serves as a vital biological habitat in the coastal rocky zone and plays an ecological role as coral reefs, mangroves, seagrass beds and salt marshes do. Additionally, it constitutes a significant component of blue carbon. This study exemplified the Hainan Eucheuma Reserve to investigate and evaluate the distribution characteristics and carbon storage capacity of seaweed in this area, while establishing an investigation and evaluation method for Hainan's seaweed bed carbon storage. The results showed that the average coverage of macroalgae in the subtidal zone reached 50%. There were 34 species of macroalgae in 23 genera, and the dominant species were Zonaria diesingiana, Sargassum polycystum etc. The average biomass of marcoalgae was 267.75 g·m⁻². The dry-wet ratio of the collected macroalgae was 11.58%~43.54%, and the organic carbon content was 14.25%~39.19%. As a result, the carbon storage of seaweed in the Hainan Eucheuma Reserve was (2252.77±19.37) Mg C, and average carbon density of seaweed bed was (0.49±0.004) Mg C·hm⁻².

To investigate the behavior and related factors of hermit crabs in selecting shells for settlement, this study collected 81 empty gastropod shells and 72 hermit crab samples from the intertidal zone of the Xisha Islands. Results obtained through morphometric measurements and statistical methods on two species of hermit crabs and the shells of Turbo argyrostomus show that in the environments where the types and abundance of shells are relatively rich, both Dardanus deformi and Calcinus laevimanus preferentially choose shells from the family Turbinidae for settlement. Specifically, the shells of T. argyrostomus are more likely to become settlement sites for both hermit crab species. Statistical analysis of morphological parameters reveals significant differences between the two species in shell weight, shell length, shell width, shell height, aperture length, and aperture width during shell selection. Standardized data indicate differences in shell size preferences between the two hermit crab species. D. deformi primarily considers the ratio of cephalothoracic length to shell length, while C. laevimanus focuses on the ratios of cheliped width to shell width, shell height, and aperture length. In summary, this study provides an in-depth exploration of the complex process of hermit crab shell selection, revealing differences in shell preferences among different hermit crab species. The findings contribute valuable insights into the ecological behavior of hermit crabs, aiding in understanding their roles and adaptive mechanisms in intertidal ecosystems.

In this study, based on the field survey data of the Guangxi Shankou National Mangrove Ecological and Natural Reserve (hereinafter referred to as the Shankou Mangrove Reserve) in 2022, six time-phase remote sensing images during 1987—2021 were selected, and an object-oriented image classification method was used to analyze the status of the land-use and land-cover change (LUCC) and to calculate the landscape pattern index (LPI) based on the LUCC. This study combined LPI with LUCC to focus on exploring the wetland change process and its important influencing factors in the Guangxi Shankou Mangrove Reserve. There has been a continuous transition between land types over the past 35 years, including cultivated land continued to decrease, and Spartina alterniflora and aquaculture ponds increased, with Spartina alterniflora mainly encroaching on the former coastal mudflats, and aquaculture ponds mainly converted from forested land and cultivated land. In terms of landscape, landscape fragmentation increased, connectivity decreased, landscape shape became more complex, and landform succession became more frequent; Based on Pearson's correlation analysis, there were highly significant or significant correlations between land use change and landscape indices for coastal mudflats, mizuna mudflats, and aquaculture ponds. Significant land use changes have occurred in the Shankou Mangrove Reserve over the past 35 years, with invasive species (Spartina alterniflora) and anthropogenic disturbances (aquaculture ponds) being the main factors influencing changes in mangrove wetlands in the area, and the main contributors to the continued increase in landscape fragmentation. This study reveals the influencing factors of regional landscape changes, which can provide a theoretical basis for the environmental management and protection of typical mangrove ecosystems.

The distribution characteristics of marine heatwaves in the northwest Pacific Ocean, from July 1 to September 30, 2022, were analyzed based on the coral reef watch (CRW) heatwaves monitoring dataset using satellite remote sensing. The typical marine heatwaves processes at single stations and formation mechanism of regional heatwaves in three regions with strong heatwaves were mainly explored. A composite analysis of atmospheric and ocean variables was used to investigate the mechanism of marine heatwaves. The results indicate that: (1) The spatial distribution of various attributes of marine heatwaves in the northwest Pacific has certain similarities except for the maximum intensity, and overall, the high values are relatively concentrated. (2) The properties of marine heatwaves in the offshore area of Jiangsu are significantly higher than those in other regions; the Kuroshio basin near Taiwan has a lower maximum intensity but longer duration of marine heatwaves; the values of various attributes of marine heatwaves in the offshore area of Guangdong are above the spatial mean of Northwest Pacific Ocean. (3) The generation of a marine heatwave in the offshore area of Jiangsu within 92 days is closely related to the combined effect of atmospheric forcing under the expansion of the Western Pacific Subtropical High and the transport process of atmospheric wind field with a large amount of sensible heat and latent heat from the Kuroshio basin. The marine heatwaves in the Kuroshio basin near Taiwan and the offshore area of Guangdong are mainly caused by the increased solar radiation under the control of the Western Pacific Subtropical High.

Heat shock protein 70 (HSP70) is a highly conserved protein that plays a key role in protecting biological cells or tissues from heat or oxidative stress. Due to the continuous warming of the global environment and the widespread bleaching and death of corals, how corals respond to the stress resistance mechanism of continuous warming is a scientific research hotspot. However, current research on the characteristics of the HSP70 family in corals are relatively rare. In this study, 28 members of the HSP70 family were identified by analysis of the Sinularia acuta protein sequences under high temperature stress, all of which were acidic hydrophilic proteins with relatively stable structure. Subcellular localization showed that HSP70 was mainly found in coral nuclei and cytoplasm, with lesser amount in mitochondria and endoplasmic reticulum. Signal peptide predictions showed that 26 of the 28 HSP70 members did not have signal peptides, most of them do not secrete proteins and did not have a transmembrane structure. The phylogenetic tree showed that the members of the S. acuta HSP70 family can be clustered into 5 classes. Analysis of the structure and conserved regions of the hsp70 gene family of S. acuta predicted 10 motifs which could be divided into 5 subfamilies. The main secondary structure of the HSP70 protein in S. acuta was α-helix followed by random coiling. N-glycosylation sites were predicted in 25 of the 28 HSP70 family proteins, with the number of sites ranging from 1 to 9. All 28 HSP70 family proteins were predicted to have phosphorylation and O-glycosylation sites, with a total number in the range of 41~96 and 1~23, respectively. The results of this study on the HSP70 family lay the foundation for future research on the adaptive mechanisms of corals in response to global warming stress.

Sargassum wightii is a common species in the Weizhou Island of Guangxi, Xuwen of Guangdong and other sea areas, and is an economic macroalgae. Understanding the annual growth and early development of macroalgae can predict the mature time of thalli and provide scientific basis for artificial seedling and cultivation of macroalgae. This paper reports the annual growth characteristics, the effect of temperature on ovulation and the early developmental process of sexual reproduction of S. wightii in the sea area of Xuwen, Guangdong. The results show that the annual growth of S. wightii can be divided into 4 periods: fast growing period, mature period, decline period and resting period. The average length of thalli reaches its maximum [(188.32±43.77) cm] in early April, exceeding 180 cm in both April and May, and less than 5 cm in late July to early November. The male and female reproductive parts of S. wightii are in the same receptacle, and the egg cell development belongs to 8-nucleui type. The culture temperature is very important to the ovulation process. Ovulation could not be achieved at 15, 27 and 30 ℃, but could be achieved at 18~24℃. The ovulation time is shortest at 24 ℃, only 3 d. The zygotes develop into germlings with rhizoid buds at 24 ℃ for about 24h, and the seedlings develop a fourth leaflet after 30 d of culture. The results of this study provide basic information for the biology, ecology, artificial seedling and cultivation of S.wightii.

The intensification of extreme wave marine hazard induced by global ocean change is very likely to accelerate the geo-hazard risk of cliff erosion in Hainan Island. Shore platforms are expected to effectively attenuate wave energy approaching the shore and consequently reduce the erosive impact of extreme waves on cliff. Shore platforms are commonly observed in volcanic rocky coasts on NW Hainan Island, providing an ideal natural laboratory to evaluate the effect of shore platform morphology on cliff erosion. This study employs the Wucaiwan Bay rocky coastline in the E’man Town, Danzhou City, Hainan Island as the study area. Time-lapsed marine remote sensing images revealed the cliff erosion rate is about 0.26 m·a^-1 in the last decade in the area. Physical oceanography analysis suggested a maximum significant wave height of 7.8 m could be expected visiting the area in a 100-years return level. The geomorphological characteristics of the sloping shore platform and the rock strength of cliffs were further surveyed via coastal geomorphological approaches. Numerical computation outputs suggest the shore platforms is capable of reducing the wave erosional forces on cliff by over 80% under future extreme wave conditions. This study further discusses the natural coastal protection from sediment beaches, vegetations and in situ deposition of eroded boulders at rock cliff foot.

This paper reviews the basic concepts of data security governance, summarizes the current status and challenges for data security in marine science in China, points out its basic characteristics, and extracts possible security risks for security process areas in the data life cycle. With the whole life cycle of marine scientific data as the core, a data security governance framework is constructed from three levels of governance objectives, security capabilities and governance systems, and specific security strategies are proposed, which provide theoretical support and practical reference for improving the security governance capabilities of data centers in marine science in China.

Coastal wetland restoration is an important measure to improve the blue carbon function in the coastal zone. Zhejiang Province has continuously carried out a series of large-scale mangrove introduction and afforestation projects. Yet, the carbon sink capacity and influence of factors for the high-latitude artificial mangroves still remain unclear. In this study, the soil organic carbon (SOC) content, organic carbon stock per unit area and their vertical distribution characteristics of the Kandelia obovata forests with different ages were investigated. The SOC content and stock in the mangroves were also compared with the Spartina alterniflora salt marsh and bare mudflat. The results showed that the SOC content and stock were the highest in the adult mangroves. The SOC content and stock in both mangroves and salt marshes were significantly higher than those in the mudflat. The SOC content in salt marshes was higher than that in the young mangroves, but due to the significant lower bulk density of Spartina alterniflora salt marsh soils compared to young mangrove forests, the SOC stock in the young mangroves was slightly higher than that of salt marshes. The SOC content and stock in the different habitats showed the distribution characteristics of first increasing and then decreasing with the soil depth, reaching the highest values at the soil depth of 20~50 cm. Site location and habitat type had a significant relationship with SOC content and stock, with significant interaction between site location and habitat type. Dissolved oxygen in pore water, soil total nitrogen, soil pH and pore water salinity were significantly associated with the SOC content. The results of this study can provide scientific basis and data support for assessing the carbon sequestration potential of artificial mangrove forests after northward migration, as well as wetland protection and restoration strategy.

Marine heatwaves are extreme high temperature events that occur on the oceans and have devastating impact of marine environment and ecosystems. Using the fifth generation of European centre for medium-range weather forecasts atmospheric reanalysis data (ERA5) and the Hadley Centre Global Sea Ice and Sea Surface Temperature (HadISST) dataset during the period of 1960-2020, and data from the North Atlantic idealized experiments performed with the CESM1 model, this study investigated the variation of the interannual relationship between the El Niño-Southern Oscillation (ENSO) and the following early summer marine heatwaves in the western Pacific, and the possible reasons for their decadal variation based on correlation, synthetic analysis and other statistical methods. The results are shown as follows. 1) The interdecadal relationship between the ENSO and the following early summer marine heatwaves months in the western Pacific displays a prominent decadal variation, which is modulated by the Atlantic Multidecadal Oscillation (AMO). A high correlation between the ENSO and the following early summer marine heatwaves in the western Pacific appears during the positive AMO phase, while no significant correlation is found during the negative AMO phase. 2) AMO mainly affects the response of atmospheric circulation in the Northwest Pacific by modulating ENSO amplitude, thereby affecting the relationship between the ENSO and the following early summer marine heatwaves in the western Pacific. During the negative (positive) AMO phases, the Northwest Pacific anomalous anticyclone/cyclone appears strong (weak), and its position shifts toward east (west) in the following early summer, due to the relatively strong (weak) ENSO events through strong (weak) wind-evaporation-SST positive feedback mechanism. Thus, the position and intensity of anomalous anticyclones/cyclones led to significant differences in the distribution of early summer marine heatwaves in the western Pacific between the positive and negative AMO phase.

The Indo-Pacific Convergence Region is the center of the origin in marine biodiversity and has extremely high biodiversity. With the dramatic changes in global climate and human activities intensify, ecosystems are gradually fragmenting. In this context, marine fish play important ecological functions in connecting fragmented ecosystems and protecting biodiversity. Exploring the genetic structure and connectivity of typical fish species in the Indo-Pacific Convergence Region will clarify the genetic diversity patterns and diffusion paths among different populations, thereby providing scientific support for the protection of biological diversity. In this study, 8 fish species (Acanthurus japonicus, Balistapus undulatus, Cephalopholis urodeta, Ctenochaetus striatus, Gnathodentex aureolineatus, Lutjanus kasmira, Melichthys vidua and Parupeneus multifasciatus) were collected from 5 representative areas in the Indo-Pacific Convergence Region (Zhongsha Islands, Nansha Islands, Xisha Islands, Hainan Island, and the Philippines), totaling 309 samples, 515 mitochondrial COI genes and 16S sequences were obtained; To broaden the scope of the study, cytochrome C oxidase subunit I (COI ) gene sequences from the Taiwan Island in China and Indonesian were downloaded from GenBank, amounting to 86 sequences. Based on this, we analyzed the genetic diversity and genetic differentiation structure among different groups in the above seven study regions. The overall results show that 8 fish species have high levels of genetic diversity and low genetic differentiation, among which Parupeneus multifasciatus and Balistapus undulatus are the most obvious; Indonesia, Taiwan Island in China and South China Sea Island populations also have high genetic diversity. The study further developed the species distribution models and the least-cost paths model to explore the population connectivity. Based on this, distribution information for the eight fish species (collected from a total of 133, 047 points) was used to predict suitable distribution areas under current climate using the MaxEnt algorithm, and the connectivity between different populations was calculated using the ArcGis 10.2 software SDMtoolbox v2.5. Population connectivity reveals that the east coast of the Philippines-Sulawesi is an important dispersal path for the above eight typical fish species in the Indo-Pacific Convergence Region. The South China Sea Islands (Nansha, Zhongsha and Xisha Islands) connect Taiwan Island in China, the Philippines and Indonesia, and serve as connecting hubs for species spread. In summary, the Philippines, Indonesia, Taiwan Island in China, and the South China Sea should become priority protected areas for maintaining genetic diversity and protecting connectivity. When protecting biodiversity, population connectivity and genetic diversity should be comprehensively considered, and different research results reflected at the macro and micro levels should be combined to achieve more effective biodiversity conservation.

The Weizhou Oilfield in Beibu Bay, South China Sea, has a complex structure, developed faults and fractured strata, resulting in a non-uniform velocity structure. To meet production requirements, this area has undergone multi-round traveltime tomography velocity modeling, including velocity modeling of dual-azimuth streamer seismic data. However, imaging quality remains poor. Full waveform inversion (FWI) builds a more accurate velocity model by making full use of the amplitude and traveltime information of the seismic wavefield. However, this process usually requires that the seismic data contain long offset components. Given the limited offset of streamer seismic data in the Weixi exploration area, this paper develops a high-precision velocity modeling technique process that combines FWI and traveltime tomography. Firstly, multi-scale FWI from low to high frequency is used to invert shallow and intermediate layer velocity models derived from high-SNR turning and refracted wave signals. Reflection traveltime tomography is then used to update the deep-layer velocity model. Compared to conventional reflection traveltime tomography modeling, the accuracy of the velocity model is improved, which in turn improves the structural imaging of the target area, making the fault structure more discernible. This work lays a solid data foundation for the oilfield to increase storage and expand production and realize benefit exploitation.

To investigate the trophic structure characteristics of the main fish species in the coral reefs of the Nansha Islands, twenty three fish species were collected from waters of the Yongshu Reef and Meiji Reef during the spring of 2023, and the stable isotopes of carbon and nitrogen of fish were measured and used to analyze their trophic structure, and a trophic level spectrum was constructed for the fish. The δ¹³C and δ¹⁵N values of fish from the Yongshu Reef ranged from -18.74‰ to -14.33‰ and 5.96‰ to 9.37‰, with an average value of (-16.33±1.28)‰ and (8.46±0.48)‰, respectively. The δ¹³C and δ¹⁵N values of fish from the Meiji Reef ranged from -18.01‰ to -12.70‰ and 7.31‰ to 8.82‰, with an average value of (-15.02±1.53)‰ and (8.21±0.93)‰, respectively. The δ¹³C values of fish from the Yongshu Reef and Meiji Reef showed significant differences, indicating a wider food source for fish in the Meiji Reef. However, there was no significant difference in the δ¹⁵N values of fish between the two the reefs, indicating no difference in trophic structure composition between them. Cluster analysis based on the values of carbon and nitrogen stable isotope of fish divided the fishes from the two reefs into the benthic fish group and the mixed group of benthic and pelagic fishes. The trophic groups in the Meiji Reef were more vaguely defined, with evident feeding competition among carnivorous fishes. The trophic levels of fish from the Meiji Reef and the Yongshu Reef were (2.79-3.23) and (2.39-3.39), respectively. Both coral reefs were dominated by carnivorous fish at medium and low trophic levels. Most carnivorous fish were in relatively narrow ecological niches. These results suggest that the fish from the coral reefs of the Nansha Islands had a more complex trophic structure composition, wider food sources and lower community redundancy, compared with the fish from coastal tropical and subtropical bays. This study provides basic data and scientific basis for the protection and sustainable management of fishery resources in the coral reef waters of the Nansha Islands.

Marine environmental data is an important strategic resource for mankind to understand, protect and exploit the ocean. With the rapid development of digital economy and science and technology, marine environmental data has become a new and important factor of production. As a new form of asset, how to value marine environmental data assets has become a new problem. Through the in-depth investigation and research of the value assessment of domestic marine data assets, it is concluded that the traditional cost method and the benefit method and their combination are the basis for the current valuation of marine environmental data, and it is found that the method of value assessment of marine environmental data in the new era has complexity, flexibility and multi-dimensional evaluation methods, which have very important economic value for the development of marine economy and the sustainability of marine scientific research.

As a result of climate change and human intervention, jellyfish outbreaks have become a serious ecological disaster that threatens coastal economies and marine ecosystems. Globally, there is an urgent need to prevent jellyfish blooms. Microorganisms play an important role in the growth and development of marine invertebrates. Co-culture experiments revealed that Bacillus paranthracis SG49 inhibits the settlement and metamorphosis of Aurelia coerulea planula larvae. The key metabolic pathways and mechanisms behind this inhibition, however, require further investigation. Using non-targeted metabolomics technology, the intracellular and extracellular metabolites of SG49 were detected, differences between the two groups were analyzed, and potential metabolites affecting planula larval metamorphosis were identified. Our results showed that SG49 intracellular and extracellular metabolites were significantly different. Specifically, seven substances were screened for their potential inhibitory activities, including 3-hydroxy-2-oxindole, kanamycin, apramycin, streptomycin, streptomycin sulfate, gallic acid, and coniferyl alcohol. Bacterial biofilms and microorganism growth can be inhibited by these metabolites. Our findings provide a theoretical basis and strain resources to prevent jellyfish outbreaks in the future.

Based on the best typhoon track data provided by the China Meteorological Administration, according to K-means clustering analysis, typhoons entering the coastal waters of China from the West Pacific Warm Pool from 2002 to 2021 are divided into three types, and the three types are named as westward path typhoon, northwestward path typhoon and turning path typhoon according to typhoon path characteristics. In addition, the optimal daily product of sea surface temperature interpolation provided by remote sensing systems (REMSS) and simulation results of coupled ocean atmosphere wave sediment transport modeling system (COAWST) are used to study the changes of upper ocean temperature caused by these three typhoons with different path. The results show that the influence characteristics of three different typhoon paths on sea surface temperature (SST) are mainly reflected in the cooling amplitude and recover time: the turning typhoon exhibits the largest cooling amplitude and the longest-lasting effect on sea surface temperature, followed by the northwestward typhoon, the westward typhoon has the smallest cooling amplitude and the shortest duration of impact. The difference of three different typhoon paths on the mixed layer thickness (MLT) and thermocline thickness (TT) are mainly reflected in the rangeability of thickness and recovery time: for the rangeability of MLT and TT, the turning typhoon is the largest, followed by the northwestward typhoon, and the westward typhoon is the least. For the recovery speed of MLT and TT, the northwestward typhoon is obviously faster than the westward typhoon and the turning typhoon.

The monitoring of water quality is very important to understand the changes in marine ecosystem. Based on the continuous monitoring data of two buoys in the southwest of the Daya Bay from 2022 to 2023, this paper analyzes the time series changes in water quality environment. The results showed that the temperature and salinity in the southwest of the Daya Bay were affected by solar radiation and precipitation, with obvious seasonal differences. The temperature and salinity were high in summer and low in winter; chlorophyll a, dissolved oxygen and pH showed obvious diurnal changes. In summer and autumn, the Dapeng Cove was characterized by high temperature, low salinity, low dissolved oxygen, low pH, and high chlorophyll a compared with the Yangmeikeng. Pearson correlation analysis showed that there was a significant correlation among temperature, salinity, dissolved oxygen, pH, and chlorophyll a in summer and autumn, and there were regional differences. Near the bay mouth, waves, upwelling, and other water movements may be the main influencing factors; nearshore, the increase of runoff input may be the primary dominant factor causing changes of water quality. In addition, this article also recorded the impact of distant typhoons causing waves and precipitation events, thus affecting the environment of the Daya Bay. Analyzing the characteristics of the changes in the time series of coastal environmental parameters has important implications for studying the evolutionary characteristics of marine ecosystems.