The Swan Lake in Rongcheng of Shandong province is a typical lagoon-barriers system. Since 1980s, under the influence of human activities, the environmental system of the Swan Lake has changed with strong erosion of the sand dam. Studying the erosion and deposition of underwater bank slopes is of great significance for understanding the evolution of lagoon-sand dam system and protecting the environment of Swan Lake. This paper focus on the underwater bank slope of the sand dam at the east side of the Swan Lake. Based on the combination of chart data from 1960 to 2014 and geographic information technology, we have obtained multi-year water depth of the coastal waters on the east side of the Swan Lake since 1960, and analyzed the contour changes, scouring and silting changes and topographic changes of the set profile in the sand dam area on the east side of Swan Lake. The results show that the overall depth contours moved towards the sea from 1960 to 1980, while the tendency of contours moving towards the sea from 1980 to 2014 slowed down, the 0 m depth contour at the entrance of the tidal channel retreated 126.70 m to the shore from 1960 to 2014. The underwater bank slope of the Swan Lake was at a state of siltation from 1960 to 1980, the annual siltation rate is 3.60 cm·a^-1. The erosion area increased significantly from 1980 to 2014, and the erosion and siltation phases were distributed, the annual siltation rate is 0.79 cm·a^-1. The underwater bank slope of the Swan Lake sand dam is steep and gentle, and the north side of the tidal channel entrance is more likely to be eroded than the south side. Human activities have changed the environmental state of the Swan Lake, leading to partial erosion and retreat of the underwater bank slope of the Swan Lake.

Coastline dynamic change is a common reflection of global change and human activities. Based on seven Landsat remote sensing images and Google Earth high-resolution images of the Guangdong-Hong Kong-Macao Greater Bay Area, Tokyo Bay and San Francisco Bay from 1980 to 2020, this paper used threshold segmentation combined with water index method and Sobel operator method to extract the coastline of each analysis period. In addition, this study also analyzed the changes of coastline in terms of length, spatial morphology, structure and utilization degree, and analyzed qualitatively and quantitatively the influencing factors with the help of geographic detectors. The results show that: (1) from 1980 to 2020, the intensity of annual average length change in the Tokyo Bay is the largest, which is 0.37%, and the coastline tends to be straight; (2) in the past 40 years, the depth of coastlines in all analyzed bay areas has remained stable, and the structures tend to be complex and the morphology tends to be dispersed. Among them, the difference of fractal dimension of coastlines in the Guangdong-Hong Kong-Macao Greater Bay Area is the smallest and the morphology is the most dispersed; (3) during the past 40 years, the natural coastline of each bay area decreased, while the length of port wharf coastline and other artificial coastline increased significantly, and the biological coastline of the Guangdong-Hong Kong-Macao Greater Bay Area fluctuated, and the coastline utilization index increased the most. The results show that temperature, wave height, tide, area and port throughput are the main factors that affect the coastline change, the interaction of any two factors is greater than the single factor.

In order to investigate the contents and sources of heavy metals in the Xisha waters in the South China Sea, 24 seawater samples at six sites were collected in December of 2021. Vertical profiles of temperature, salinity, turbidity, dissolved oxygen, colored soluble organic matter and chlorophyll were determined by Conductivity-Temperature-Depth instrument. Inductively coupled plasma mass spectrometry was used to measure the contents of heavy metals in seawater samples, and the average Cu, Pb, Zn, Cd, Ni, Cr, As, Fe and Mn contents were 0.22~20.79 µg·L^-1, n.d. (not detected) ~0.25 µg·L^-1, 1.90~15.90 µg·L^-1, 0.13~0.17 µg·L^-1, 0.54~1.31 µg·L^-1, 0.29~0.33 µg·L^-1, 2.93~3.17 µg·L^-1, 0.39~1.23 µg·L^-1 and 0.35~1.14 µg·L^-1, respectively; Hg was not detected. Only Cu or Zn contents in 5m-depth seawater at D2~D4 sites exceeded Class I requirement of National Seawater Quality Standard (GB 3097-1997), and the spatial distribution of heavy metals was influenced by terrestrial inputs, environmental factors and human activities. Principal component analysis indicated that the heavy metals in the Xisha waters are mainly from three sources: ship emission, terrestrial agricultural runoff, as well as terrestrial debris and industrial inputs. The measurements in this study are generally within the range of heavy metal contents previously reported in the South China Sea. However, compared with the background values of the South China Sea in 1998, the contents of Cu, Pb, Zn and Cd in surface seawater have increased by one order of magnitude, reflecting the impact of recent intense human activities in this region.

As a new form of coastal engineering, the artificial island has been receiving increasing attentions from community to the beach erosion and accretion due to its construction. Based on the multi-temporal remote sensing images and four field surveys, the influence of winter waves combined with artificial islands on the erosion and accretion of the Riyue Bay beach has been analyzed. Besides, the mechanism of beach erosion and accretion was explored using the wave data in the adjacent sea area. Our new results show that the average significant wave heights and wave periods in the winter were obviously stronger than those in the summer, and the wave force generally shows an increasing trend year by year, but its variation is not significant around the artificial island before and after the construction of islands. The construction of artificial island has a significant impact on the beach topographic profile, showing the obvious characteristics of accretion in the area sheltered by the artificial island and erosion on two sides of the beach. The beach accreted continuously in the island shadow area, and the shoreline in that area moved up to 200 m towards the sea, which may even be linked with the artificial islands to form a tombolo. The beach was eroded and the maximum erosion distance of shoreline to land is about 50 m on both sides behind the artificial island. The Riyue Bay beach is strongly affected by the winter waves and artificial islands. From north to south, the beach was at a state of stability-erosion-accretion, relative stability, slight erosion or accretion-erosion-accretion.

The Haitan Strait in Fujian province is an important channel for the southward transportation of material from the Minjiang River and the Zhejiang-Fujian Coastal Current to the Xinghua Bay and the south-central coast of Fujian. The topographic data of the Haitan Strait in the past 50 years was analyzed using GIS tools. The results indicate that strong siltation occurred in the Haitan Strait due to the influence of several catastrophic floods in the Minjiang River Basin during 1964~1975. The Haitan Strait experienced strong erosion during 1975~1990 which is caused by water and soil conservation and reservoir constructions in the Minjiang River Basin. After that, the erosion rate declined gradually and the strait maintained slight scouring. Large-scale artificial sand mining started since 2007 that caused severe erosion in the northern part of the Strait. Before 2007, sediment discharge from the Minjiang River was the main factor restricting the geomorphological evolution of the Haitan Strait. Flood, sand mining and reservoir construction had a direct impact on the geomorphologic evolution of the strait. However, after 2007, large-scale artificial sand mining activities and reclamation projects in the strait have gradually become the main factors to affect its geomorphologic evolution.

The Qinzhou Bay in Guangxi province is an important estuarine bay in south China. With recent intensive engineering construction and coastal reclamations, the topography evolution of the Qinzhou Bay is changed, which may influence the port shipping and shoreline stability. Based on two sets of coastline and underwater topographic data, we developed a coupled hydrodynamic-sedimentary dynamic numerical modelling system to simulate the impact of human activities on the dynamics of underwater topography evolution of the Qinzhou Bay in the past 35 years. Our results show that the reclamations optimize the spatial distribution of the flow field by slightly increasing the tidal flow velocity in the Longmen waterway and the outer bay; meanwhile, the reclamations changed the tidal asymmetry distribution, which may affect the development trend of the channel-beach pattern and the local erosion and deposition, mainly in the area of the northern Maowei Sea, the Longmen waterway, the middle of the outer bay, and around the Sandun Highway; moreover, the coastal reclamations had overall weakened the underwater geomorphology change of the Qinzhou Bay, and slightly increased the changes in the central Longmen waterway, but the spatial distribution of the change is more concentrated. The magnitude of change in the outer bay area decreased slightly, the trend of change was concentrated in the eastern and western waterway, while the change in the central waterway tended to be stable. Overall, maintaining a stable topography of the Qinzhou Bay is of great importance for the sustainable development of port shipping and coastal zone economy in the future.

The beach morphodynamic process under the influence of extreme high-energy events is directly related to coastal stability and seawalls safety. Based on the profile elevation and surface sediments of the Yintan Beach collected before and after the 2020 16^th typhoon “Nangka”, this paper explores the mechanism of morphological changes of a meso-tidal beach in response to typhoon actions. The results show that: (1) In post-typhoon period, the beach morphological changes are manifested by the disappearance of a large sand bar and the flattening of the bar-trough system, leading to a more gentle beach slope; (2) Sediment in Yintan Beach is mainly medium sand, fine sand and very fine sand, which account for more than 95%; The sediment grains become finer in the high tide zone and coarser in the low tide zone, while both increase and decrease in sediment grain size can occur near the sand bar; The morphodynamic process of mid-to-high tide zone of the Yintan Beach in response to a typhoon is similar to that of a macro-tidal beach, which is characterized by dissipative condition. However, the morphodynamic process of low tide zone of the Yintan Beach behaves like a micro-tidal beach due to the existence of a large sand bar; (3) During the typhoon, wave is the main dynamic factor affecting the beach, and the topography affects the manifestation of nearshore hydrodynamics, thereby changing the grain size distribution of sediment.

Zooxanthellae, bacteria, and reef—building corals have a close symbiotic relationship, but the phycosphere bacterial community of zooxanthellae is poorly studied. In this study, six strains of zooxanthellae from five genera were cultured in vitro, among which two were free-living zooxanthellae strains (type E) and four were anchorage-dependent living zooxanthellae strains (type A—D). Bacterial community analysis was performed by collecting three different particle size fractions (0.2-3μm, >3μm, and settling algae cells). Results showed that the phycosphere bacterial communities between the two lifestyle algal strains were significantly different. The bacterial species richness in anchorage-dependent living strains was significantly higher than that in free-living strains. Seven bacterial genera were observed to be present in all the algal strains, representing the core bacterial communities of zooxanthellae. Comparing the core bacterial communities in three particle size samples, we found that the core bacterial communities in >3μm samples and in 0.2-3μm samples are highly similar, but both were significantly different from the “Settling” samples.

Penicillium sp. S2014503 was isolated from a rotten whale bone sample. Constituent analysis and bioactivity evaluation of S2014503 were carried out to find more bioactive compounds from this fungus. Chemical structures of the purified compounds produced by S2014503 were determined by comprehensive analysis of NMR (nuclear magnetic resonance), MS (Mass spectrum) data of each compound. Stereochemistry of chiral compounds were elucidated by comparison of specific rotation value with the reported ones or determined by X-ray diffraction analysis. Ten compounds emodin (1), citreorosein (2), tetrahydro altersolanol B (3), conioxanthone A (4), chrysogine (5), pyramidamycin B (6), germicidin O (7), 2-(6-hydroxy-5,7-dimethylbenzefuranone-4-yl) acetaldehyde (8), astrophenone (9), and chenopodolans A (10) were found in the fermentation product of S2014503 which was cultured on a solid state rice medium. Bioactivities of all the isolated compounds were evaluated for the antibacterial activities and cytotoxicity against brine-shrimp larvae. Compounds 1 and 2 showed weak activity against Gram positive bacteria Micrococcus luteus. Compounds 1, 2 and 4 were significantly cytotoxic against brine-shrimp larvae (Artemia salina) after 6 hours of incubation at room temperature. Interestingly, compound 1 was a well-known laxative ingredient of Traditional Chinese Medicine Rheum officinale and Polygonam cuspidatum. This work is the first report on the emodin analogs from a whale bone derived fungus Penicillium sp.

The embayed sandy and gravel beaches are important tourism resources in the coastal zone of islands, with high socio-economic and ecological values and having received study attention for years. This study focuses on five representative embayed beaches on the east coast of the Zhujiajian Island in Zhejiang Province. The beach topography and sediment data were obtained from three field campaigns in the early, middle and late stages of the 2019 typhoon season, and the nearshore hydrodynamic data were also collected and analyzed. Then, the dynamic changes of topography and sediment characteristics of five different embayed beaches were detected. The results show that the five beaches experienced different volume changes during the typhoon season, i.e., 11.93 m³·m^-1(Dashali), -54.41 m³·m^-1 (Dongsha), -19.75 m³·m^-1 (Qiansha), 2.19 m³·m^-1 (Wushitang) and -1.96 m³·m^-1 (Xiaowushitang), respectively. The gravel beaches were more stable than the sandy beaches, and the sandy beach without human activity is less eroded during the typhoon season. The mean grain size of surficial sediments on Dashali, Dongsha, Qiansha, Wushitang and Xiaowushitang during the typhoon season are 2.47 Փ, 2.24 Փ, 2.64 Փ, -5.96 Փ and -6.03 Փ, respectively, with coarsening and onshore transport being the main performances of their changes. The change of sediment grain size on sandy beaches is more significant than that on the gravel beaches. The sediment grain size, the energy level of typhoon, and the angle between the main wave direction during the typhoon and the beach orientation, and coastal engineering can have impacts on beach morphological variation during typhoon seasons. This research can provide reference for the beach management during typhoon seasons.

Based on the mangrove plantation data and stand growth monitoring at different periods, we analyzed the spatial and temporal variation of mangrove forests and regional silvicultural growth differences in Zhejiang Province. The results show that: (1) The total area of mangrove forests in Zhejiang Province by 2020 is 386.77 hm², including 257.01 hm² in Wenzhou and 129.76 hm² in Taizhou; the main afforestation species are Kandelia obovata (368.48 hm²) and Myoporum bontioides (18.29 hm²); (2) The proportion of mangrove area at different periods was 0.11% (before 2000), 3.72% (2000-2010), 36.17% (2011-2015) and 59.99% (2016-2020), respectively; (3) The average heights of Kandelia obovata before 2000 and 2000-2010 were 205.5 cm and 246.13 cm, respectively; the cover was as high as 67.69% and 77.9%. And the average heights of Kandelia obovata in 2011-2015 and 2016-2020 was 106.63 cm and 50.17 cm, respectively; the cover was 68.66% and 24.56%; (4) There were significant differences in the alkali-hydrolyzed nitrogen, available potassium, organic matter and salt content in tidal flat sediments of mangrove plantations in different regions; (5) The height of 4-year-old Kandelia obovata in different regions was significantly higher (P<0.05) in the Xinmeizhou village, Longgang city than in the Shupaisha Island, while the diameter was significantly higher (P<0.05) in the Shupaisha Island than in the XimenIsland. The area of mangrove planting in Zhejiang Province has increased significantly in recent years; mangrove populations are growing vigorously, and the depression of early planted stands is high; the growth of Kandelia obovata varies significantly in different regions.

Sea Cucumbers play an important role in marine ecological system and have edible and medicinal values. At present, wild resources of sea cucumbers are greatly depleted in China, and artificial breeding of sea cucumbers provides an essential way to restore the population resources. Understanding the hormones that regulate spawning behaviors of sea cucumbers has great significance for the development of artificial injection hormone. We reviewed the hormones found in sea cucumbers that can regulate their spawning behaviors, and we also provide some new perceptions for the future research. The review can provide some valuable references for revealing the key spawning mechanism of sea cucumbers and developing the artificial spawning induction by injecting hormones.

It was investigated for the spatio-temporal variation of the water quality in the mangroves in Guangdong Province. Surface water samples were collected inside the mangroves from 30 sites during the dry season (Oct., 2017 to Jan., 2018) and 20 sites during the wet season (July to Aug., 2018). Water quality and trophic conditions were highlighted by the single trophic state index (TSI Chl a), and the evaluation standard was: 0<TSI≤30 oligotrophic, 30<TSI≤50 mesotrophic, TSI>50 eutrophic, and >70 high eutrophic. The spatio-temporal variations of the environmental variables were as follows: salinity (2.15‰~27.14‰), pH (6.18~8.65), electrical conductivity (10.87~90.52 µs·cm^-1), turbidity (5.6~272 FTU), nitrate (0~127.2 mg·L^-1), nitrite (0~12.0 mg·L^-1), phosphate (0~34.5 mg·L^-1), silicate (1.22~2.88 mg·L^-1) and Chlorophyll a (0.19~38.08 mg·m^-3). Cluster analysis deduced that the water quality across the right side of the Leizhou Peninsula to the east Guangdong coast during the wet season was relatively better, while the left side experienced mesotrophic conditions. Meanwhile the water quality decreased in the dry season, ranging from high mesotrophic conditions around the Leizhou Peninsula to eutrophic conditions across the east coast. The PCA revealed that nutrient salts, salinity, pH, EC and turbidity contributed significantly to the water quality status in the mangrove ecosystems, which in turn affects the algal communities in the ecosystem.

Plant rhizosphere microbes can be transferred directly from mother to offspring, these vertically-transmitted organisms can affect host phenotype. Field investigation revealed that Sonneratia × gulngai, a natural hybrid of mangrove plants of the genus Sonneratia, usually grew stronger than its parents, and showed stronger survival advantage. In order to explore the reasons for this phenomenon, the offspring's microbiome composition (S. × gulngai) was compared with its parents S. caseolaris and S. alba by the bacterial 16S rRNA gene high-throughput sequencing technology. The sediment samples were collected from the Dongzhaigang Mangrove National Nature Reserve of Hainan Island. The result showed the rhizosphere bacterial communities of the three mangroves were highly diverse and rich, and distributed into 30 phyla, 242 families and 351 genera. Proteobacteria contributed to 40% of all reads and constituted the predominant members, most of the inherited rhizosphere microbiome belonged to this phylum. Significant differences were also observed at the phylum level. In offspring S. ×gulngai, the abundance of Actinobacteria and Acidobacteria was 4.3% and 6.5% respectively, which are significantly higher than parent's 1%~2%; Thermi species were enriched to be dominant populations with relative abundances of 19.8% in the parent S. alba, but the numbers was only 1% in the offspring S. × gulngai, and found Thermotogae phylum (5%) was absent in the rhizosphere bacterial community of S.× gulngai. In short, microbiome composition differed more strongly between offspring S. × gulngai and the parent S. alba than S. caseolaris. The analysis of soil physical and chemical properties found that the soil total nitrogen (TN) content of S. × gulngai was significantly lower than that of the parent, with a difference of more than 3 times. Correlation analysis showed that the concentration of TN was significantly negatively correlated with the abundance of Planctomycetes, Actinobacteria, and Acidobacteria. Through functional prediction, some functional genes related to the basic metabolism in the offspring S. × gulngai microbial community were greatly enriched, S.× gulngai's metabolic capacity was enhanced. These findings showed that the selectively inherited some the rhizosphere soil microorganisms from their parents, which made the offspring's microbiome composition more reasonable and maintained higher diversity, some rhizosphere growth-promoting bacteria particularly enriched and increased the basal metabolic capacity, these changes promoted S. × gulngai to grow better than its parent.

Mesoscale eddies occupy more than 90 % of the kinetic energy in oceans, which significantly impact on the oceanic mass and energy cycle. The prediction of mesoscale eddies remains a very essential, but difficult research topic in the current physical oceanography field. Based upon the sea level anomaly (SLA) data measured by satellite altimeter in the last 30 years, this study develops a model for the mesoscale eddy prediction according to the generative adversarial networks (GAN) method and game theory. The results of 28-day prediction, their spatial-temporal distributions, and energy intensities are analyzed with independent samples. The main factors that affect the spatial and temporal accuracies are discussed. The results show that the temporal accuracy of this method can be accepted in about 15 days. For the mesoscale eddies with a radius of 100 ~ 200 km, the prediction error is generally less than 20 % by this method. The mean eddy kinetic energy in the study domain is about 0.875 m²·s^-2 and the root mean square error (RMSE) is roughly between 0.02 ~ 0.04 m²·s^-2. Furthermore, the results are suggestive of that the prediction is less affected by abnormal weather, and has similar forecasting ability under normal weather conditions and typhoon Nakri. These results provide a reference for further understanding and applying the new method of generative adversarial networks to predict ocean mesoscale eddies.

Using the AVISO (archiving validation and interpretation of satellite oceanographic) eddy trajectories atlas product from 1993 to 2020, this study comparatively analyzes the characteristics and evolution patterns of mesoscale eddies during eddy life span in the South China Sea (SCS), a marginal sea of the Pacific Ocean, and the Kuroshio Extension (KE), an open ocean. The results show that there is significant seasonal variation in the eddy characteristics in the SCS, with opposite polarity probability distribution of cyclonic eddies (CEs) and anticyclonic eddies (AEs) in winter and summer, while the distribution in KE has no seasonal variation. The AEs are stronger than CEs in summer in the SCS, while CEs are stronger than AE in the KE both in winter and summer. During the eddy life span, the eddy kinetic energy (EKE) exhibits asymmetrical growth, stable and decay stages both in the SCS and KE. The eddy growth stage in the SCS is shorter than the decay stage, while the decay stage is shorter in the KE. The change rate of EKE during life span has larger values in summer than that in winter in the SCS, but has 1.5 times larger in winter in the KE. The mean propagation velocity curves shown that the AEs move northwestward and then southwestward in the SCS with average zonal speed of 3.3 cm·s^-1, while in the KE, CEs move southwestward and AEs move northwestward in the whole life span, with average zonal speed of 1.3 cm·s^-1, which is slower than that in the SCS. There is a significant negative correlation between the eddy propagation velocity and the EKE in the eddy life cycle in both regions.

Green sea dyke represents a new concept of coastal defense, which combines traditional engineering structure with coastal ecosystem, to cope with the future trend of sea level rise and storm intensification. Before its application, however, the feasibility of such a system must be tested for low-lying coastal areas, where the risk of storm surge, storm-induced waves and shoreline erosion is greatest. The major issue is associated with the process of wave attenuation by the ecosystem and the way of using the ecosystem within the sea dyke system. For many years, wave energy dissipation has been an important research field for tidal flats, a typical environment of low-lying coasts, as well as beaches and rocky coast environments. Theoretical analysis, field observation and physical-mathematical modelling show that the coastal ecosystem indeed plays a significant role in wave energy dissipation: (1) resuspension and fluid mud movement dominate over bed friction in the mud area, in terms of wave height reduction; (2) wave attenuation occurs due to bed friction and bedload transport on the silt-sand flat at the lower part of the tidal flat, while on the upper mudflat it is caused mainly by re-suspension and suspended, fine-grained sediment transport; (3) in the vegetated ecosystems such as salt marsh, mangrove and seagrass beds, the efficiency of plants in reducing flow velocity and dissipating wave energy is higher than that of bare flats, due to plant morphological resistance and stem movement; and (4) wave attenuation is high when passing through biological reefs (e.g., coral and oyster reefs), especially during storms, with bed surface friction and wave breaking being the major mechanisms. Although the wave attenuation theory has been established, the optimization of the way the ecosystem is used within the sea dyke system requires further investigations, especially the techniques of ecological niche reconstruction on eroding coasts and the design of the sea dyke to improve structure safety. The relevant scientific problems include: adaptive biology for salt marsh plants and oysters in conjunction with hard engineering; stability of ecosystem in response to future environmental change; spatial configuration of ecosystem in the green sea dyke and the match between the ecosystem life cycle and the temporal scales of storm events; and the optimization of the sea dyke configuration, on the basis of the equilibrium coastal profile theory.

Carbonate platforms and biological reefs are widely developed in the South China Sea (SCS) since Cenozoic, and the dolomitization is a common phenomenon, which has led to a broad prospect for oil and gas exploration. In this study, the development characteristics and diagenetic environments of reef dolostones in the Well Nanke 1 from Meiji Island were investigated, mainly based on the petrographic observations, mineralogical analysis, major and minor elements analysis, carbon and oxygen isotopes analysis, and the geochemical analyses of Fe speciation and Fe isotope, etc. The results showed that the reef dolostones of the upper Miocene to Lower Pleistocene in the Well Nanke 1 were mainly formed in the near-surface environments, and the dissolved pores were ubiquitous, which were accompanied with obvious residual structures. Several exposed surfaces were found in the dolomite layers, but there was no existence of the gypsum layer. Meanwhile, the reef dolostones were characterized by relatively low concentrations of Sr, Fe and Mn, with the similar REE distribution pattern to that of modern seawater. The δ¹³C and δ¹⁸O values were mostly positive, but there was no correlation between them. It indicated that the dolomitization could largely attributed to the seepage-reflux of slightly evaporated seawater and the sea level fall related to the paleoclimate cooling. In addition, iron dolomite was found in several layers, mainly near the exposed surfaces in the Well Nanke 1. The results of Fe speciation and Fe isotopic composition showed that the iron of reef dolostones was mainly derived from the chemical precipitation from the seawater, and no significant additional sources (e.g., terrigenous or hydrothermal) were present in the diagenetic environments. In general, the iron dolomite was mainly formed in the shallow burial conditions with low temperature. The vital material sources of iron dolomite were mainly from the leaching and dissolution of bioskeletons, bioclasts and authigenic carbonate minerals by meteoric freshwater. As a product of reefs exposure, the positions where the iron dolomite prevalently developed in the core could be an indicator of low sea-level stages.

Tropical cyclones (TCs) and the resultant storm surges and heavy rainfall have posed huge socio-economic threats to the coastal areas of the South China Sea (SCS) and its surrounding areas. Holocene TCs studies before instrumental record help to accurately predict trends in TCs activity in the context of global warming. Here, we presented a new sub-annually resolved paleostorm record from the Anle reef lagoon sediments of the Nansha Islands in the southern SCS since the relative cold Little Ice Age (LIA) and a total of 28 storm event layers were identified. The new reconstruction indicates that the site has witnessed frequent TCs variations on a decadal to centennial-scale since the LIA, and two main storm active periods have been developed. The most intense storm activity period occurred in the early LIA (AD 1471~1620), and the other relatively active period was witnessed in the Current Warm Period (CWP) of AD 1930~1960. Although the storm activity in CWP was strengthened, it was significantly lower than that in the early LIA. Regional comparison with the storm reconstruction record of the Yongshu Reef during the same period reveals distinct spatio-temporal heterogeneity in the southern SCS. More high-resolution storm records from similar or adjacent regions could effectively reduce the uncertainty of storm reconstructions and increase the accuracy of reconstructed records.

Based on the daily mean sea surface temperature (SST) data observed at the Dawanshan Marine Environmental Monitoring Station (DMEMS) in the Pearl River Estuary from 1974 to 2020, the definition of marine heatwaves (MHW) adopted by the World Meteorological Organization, the intensity classification criteria, and the global and northern hemisphere annual mean surface temperature anomaly data, the trends of MHW in the Pearl River Estuary are analyzed using correlation and comparison methods. The results show that: 1) MHW incidents have occurred annually in the Pearl River Estuary in the past 47 years, with an average of 6.5 times per year and up to 13 times in 2020. There is an upward trend in the number of occurrences every year. The average duration is 11.7 days, up to 62 days. 2) MHW days in the Pearl River Estuary have increased significantly in the past 47 years, with an increasing rate of 1.81 d·a^-1. 3) During this period, the proportion of MHW days with each level of intensity to all days is: moderate 18.92%, strong 53.24%, severe 24.06% and extreme 3.77%. 4) The main reasons for the increase of MHW days and the occurrence of extreme MHW in the Pearl River Estuary might be global warming, enhanced high pressure and weakened monsoon in the South China Sea. It is estimated that the MHW days in the Pearl River Estuary will increase in the future.

The dynamic process of beach profile changes under the actions of waves and tides is the key to understanding coastal evolution, coastal defence design and tourism resource planning. Taking an artificial beach in the Shajing Peninsula of the Qinzhou Bay in Guangxi province as the study area, the study aims to explore the dynamic process of beach profile changes by analyzing the erosion and single-width volume of beach profile, as well as using EOF (Empirical Orthogonal Function) to reveal its model, based on the monthly surveyed profile elevation data from January 2018 to December 2019 using by GPS-RTK, The main results were shown as followed: (1) during the observation period, the artificial beach profile showed a regular variation characterized by accretion in winter and spring and erosion in summer and autumn; (2) due to the transverse sediment transport over the artificial beach, the single-width volumes of beach profile displayed opposite variation trends in adjacent transversal zones, which was manifested by a alternation between erosion and accretion; (3) the variation modes of artificial beach profiles could be divided into three parts that include the main model that beach profile elevations decreased significantly due to heavy rainfall and typhoon, the secondary model that the beach profile recovered gradually after heavy rainfall and typhoon under the influences of tides and normal waves, and the third model that beach profile changes resulted from wave breaking-induced currents under the action of normal waves.

The outbreak of crown-of-thorns seastar (CoTS, Acanthaster planci) is one of the main causes to coral reef degradation in the South China Sea and the Indo-Pacific region. The density of CoTS larvae is an important indicator to determine whether the outbreak of CoTS adult population occurs or not. However, as the larvae are not visible and thus difficult to be distinguished, conventional investigation and microscope observation cannot effectively detect the CoTS larvae in natural seawaters. Therefore, it is needed to develop a sensitive and specific method for detecting CoTS larvae. This study established specific polymerase chain reaction (PCR) method to detect the CoTS larvae based on CoTS mitochondrial cytochrome oxidase subunit I gene (ApmtCOI), and this method was applied to detect the CoTS larvae in the coral reef around Qilianyu Island, Xisha. The results showed that the designed and screened four pairs of specific primers could succeed in amplifying ApmtCOI gene, and had no cross-reaction with Linckia laevigata, Culcita novaeguineae, Choriaster granulatus and Echinaster luzonicus. Moreover, the primer 2aooniF/2anooiR had the best specificity and higher sensitivity when annealing temperature was 58.5°C, which could detect the CoTS genomic DNA in pictogram grade. Furthermore, this method had succeeded in detecting the CoTS larvae in the Qilianyu Island of Xisha at the end of October, and we found that the distribution of CoTS larvae was not uniform. Therefore, this detection technology can be used as an effective method for monitoring CoTS larvae population in the future.

Marine green macroalga Caulerpa lentillifera (Caulerpaceae, Caulerpa) has attracted significant attention because of its high economic and ecological values. Changes in light and temperature influence the algal physiological metabolism and consequently affect its economic value and ecological function. In this study, biochemical compositions and physiological characteristics of the branch and stolon of C. lentillifera were comparably explored under light intensities of 40, 80, 120 and 160 µmol·photons·m^-2·s^-1, as well as their photosynthetic responses to temperature rise (+3, +6 and +9 ℃) under each light level. The results showed that varying light intensities from 40 to 120 µmol·photons·m^-2·s^-1 had no significant effect on the relative growth rate [i.e., RGR, (7.85 ± 0.26) %·d^-1], but the growth light of 160 µmol·photons·m^-2·s^-1 reduced the RGR by 49 %. Under 40 µmol·photons·m^-2·s^-1 light intensity, chlorophyll a (Chl a) and carotenoids (Car) concentrations of branch were (0.15 ± 0.04) and (0.093 ± 0.020) mg·g^-1, being about 1.52- and 1.49-fold of stolon; both Chl a and Car of branch increased with increasing light intensities, but that of stolon decreased. Protein contents of both branch and stolon increased from low to medium growth lights, then decreased to high light, with the maximum values of (1.03 ± 0.00) and (0.95 ± 0.06) mg·g^-1 under 120 µmol·photons·m^-2·s^-1, respectively. Under 40 µmol·photons·m^-2·s^-1 light intensity, the photosynthetic oxygen evolution rate (P_n), dark respiration rate (R_d) and photosynthetic efficiency (F_V/F_M) of branch were (3.10 ± 0.71), (2.14 ± 0.09) µmol·g^-1·h^-1 and (0.74 ± 0.04), wherein the P_n and R_d were 2-fold and 70 % of stolon, but no significant difference in the F_V/F_M between them. Both P_n and Rd increased with rising growth lights, but the F_V/F_M did not change. Superoxide dismutase (SOD) activity in branch [(11.0 ± 1.32) U·g^-1] was about 20 % lower than that in stolon under 40 µmol·photons·m^-2·s^-1 growth light, while the catalase (CAT) activity [(3.80 ± 0.21) U·g^-1] was similar. The SOD activity increased with increasing growth lights in both branch and stolon, but the CAT activity decreased. Particularly, our results demonstrated that the temperature rise reduced the P_n of both branch and stolon, with the reduction degree (i.e., the slope of P_n versus temperature) decreased with growth lights in branch, but increased in stolon, indicating the temperature rise maybe more harmful to branch in low light and to stolon in high light conditions.

The dissolved heavy metals (As, Cd, Cr, Cu, Hg, Pb and Zn) were investigated based on the geochemical analysis of 106 surface seawater samples in the Northern Bay of Hainan Island. Correlation and factor analysis were used to study the sources and main controlling factors of distribution of heavy metals. The pollution levels of heavy metals were evaluated by the factor index and the Nemero index with weight modified. The results indicate that, the average contents of As, Cd, Cu, Hg, Pb and Zn are 0.58, 0.14, 8.68, 0.057, 2.07 and 26.24 μg·L^-1, respectively. Additionally, the content of Cr is less than the minimum detection limit. The surface seawater, in the Dongzhai Harbor, east and north coast of the Puqian Bay, estuary of both the Maiya River and the Daomeng River, is with high content of dissolved heavy metals. The estuary of Nandu River, surrounding waters of the Ruyi Island and offshore waters of Haikou Bay are highly clean and non-pollution. The periphery of the Haikou Port, the estuary of the Maya River and the Daomeng River, the top and east coast of the Puqian Bay, and the west side of the Mulan Bay, where the pollution levels are low to medium. The pollution of the Dongzhai Port is moderate to serious. Furthermore, the pollution of the estuary of the Yanfeng River is the most serious. The pollution level of 6 heavy metals were sequenced in the decreased order of Pb> Cu> Zn> Hg> Cd> As. Therefore, Pb, Cu and Zn should be regarded as the key environmental monitoring and marine ecological research objects in the future. The heavy metals in the coastal seawater mainly came from terrestrial and ship pollution, meanwhile, the sources of heavy metals also included atmospheric input, agriculture and aquaculture. Higher salinity and lower pH can promote the desorption and release of heavy metals from suspended particles in seawater. In addition, hydrodynamic condition was also one of the main factors that controlled the heavy metals content in seawater.

Microbial nitrogen fixation is a crucial part of nitrogen cycling in mangrove ecosystems, it plays an essential role in the nitrogen nutrient supply and primary productivity improvement of ecosystem. This paper reviewed the diazotrophic community structure, nitrogen fixation rate, and the main measurement methods of nitrogen fixation in mangrove ecosystems. We also explored the application of nitrogen-fixing microorganisms in mangrove restoration and the ecological indicators of nitrogen-fixing microorganisms for mangrove habitats, emphasized the vital roles of diazotrophs in coupling carbon, nitrogen, and sulfur cycles in mangrove wetlands, and highlighted new perspectives for nitrogen-fixing microorganisms in the mangrove ecosystem.

Noctiluca scintillans is a key blooms species and widely distributed throughout the world. Previous studies indicated that the plankton community was strongly influenced by the predation of N. scintillans. In this study, eukaryotic plankton community and biological correlation in the Daya Bay were analyzed using environmental DNA technology and Spearman correlate analysis in January 2021. The temperature and salinity of surface sea water were 14.4 ~ 18.3 ℃ and 32.52 ‰ ~ 33.14 ‰, respectively. In the stations with high N. scintillans abundance, the relative abundance of phytoplankton, such as Chattonellaceae and Thalassiosiraceae were 2.41 % and 2.23 %, which is significantly higher than the average values of 0.75 % and 0.62 % at other stations, respectively. While the relative abundances of Paracalanidae and Oithonidae were 8.22 % and 4.46 % at high N. scintillans abundance stations, which is significantly lower than the average value of 64.13 % and 11.12 % at other stations, respectively. These results indicated that N. scintillans reduced the top-down control of Paracalanidae on phytoplankton including Chattonellaceae, Thalassiosiraceae, Prorocentraceae and Geminigeraceae which led to an increase in the abundance of some plankton species in the blooms areas. Meanwhile, Gymnodiniaceae and Stephanopyxidaceae were fed by N. scintillans, which directly affected the community abundance of phytoplankton. Our analysis suggests that eDNA technology provides the methodological basis for understanding the ecological niche of N. scintillans, which would ultimately contribute to understanding the occurrence of blooms strategies.

Mangrove endophytic fungi has evolved a unique metabolic pathway due to its high salt, high temperature, strong light and anoxic living environment, and then produced a large number of secondary metabolites with rich species, novel structure and significant activity, making the secondary metabolites of mangrove endophytic fungi a research hotspot in recent years. In the field of mangrove endophytic fungi, Aspergillus and Trichoderma are two genera that have been studied frequently. This paper reviews the recent advance on the chemical structure and biological activity of new secondary metabolites of the endophytic fungi of genus Aspergillus from mangrove from January 2018 to October 2022 and the endophytic fungi of genus Trichoderma from mangrove from January 2015 to October 2022, summarizes them by polyketones, alkaloids, terpenoids and other compounds, and highlights the challenges in the current research. It can provide reference and guidance for the future study of mangrove endophytic fungi.

On the basis of the weakly nonlinear theory of internal solitary waves (ISWs) and the reanalyzed assimilation data in the Sulu-Celebes Sea in both summer and winter, we calculate the dynamic parameters of the ISWs, including the linear wave speed, the first- and second-order nonlinear parameters and the linear dispersion parameter, and investigate the spatial-temporal variations of these parameters. We find that, although the intrusion from the north Pacific Ocean into the Celebes Sea is very obvious, the spatial-temporal variations of the dynamic parameters of the ISWs in the Sulu Sea is more significant than that in the Celebes Sea. In the Sulu sea, the linear speed of ISW in summer is ~0.1 m·s^-1 larger than that in winter; however, in the Celebes Sea, the linear speed of ISW in summer is ~0.05 m·s^-1 smaller than that in winter. Regardless of the first- and second-order nonlinear parameters, their variations in the Celebes Sea are relatively weak, but in the Sulu Sea, their variations are significant. In the Sulu Sea, the first-order nonlinear parameter in summer is ~3×10^-3 s^-1 higher than that in winter, but the second-order nonlinear parameter in summer is ~3×10^-5 m^-1·s^-1 lower than that in winter. In addition, in both the Sulu and Celebes Sea, the linear dispersion parameter in summer tends to reduce, but the reduction magnitude in Sulu Sea is relatively large. This paper shows that the variation in the depth of the maximum buoyancy frequency in the Sulu-Celebes Sea is the dominant factor that in turn results in the associated spatial-temporal variations of the dynamic parameters of ISWs.

A comprehensive understanding of the geological characteristics of shallow strata of seabed is the basis for identifying and evaluating shallow marine geological hazards, which is of great significance to the development of marine resources and marine engineering construction. Multiple oil and gas fields are being explored and developed in northern Dongsha, South China Sea. However, there is a lack of systematic analysis of the fine geological characteristics of the shallow strata in this place. Based on the diverse data of AUV (autonomous underwater vehicle), multi-beam, AUV shallow stratum profile, 2D seismic data and sediment test, the factors of shallow strata geological hazards were identified and their risks were evaluated in the area of 100~400m water depth in northern Dongsha, South China Sea. The survey found that the seabed surface sediments in the study area were generally relatively stable, and several micro-geomorphologies of the seabed, such as sand waves, steep steps and gullies developed. Shallow gas below the seabed was not observed, and numerous paleovalleys are developed. Significant spatial differences are featured in the shape and distribution characteristics of seabed sand waves. The sand waves with wave height greater than 1m are mainly distributed in the depths of 134~143m, 168~187m and 205m, they can move positions under modern dynamic conditions. The observation results show that the development of seabed sand waves is related to the process of internal waves. The steep steps are more than 20°, which is considered to be related to the faults running through the shallow strata.

Using the GPS sonde data collected at the northwestern part of the South China Sea in the winter of 2012, we studied the influences of cold surge and ocean front on the characteristics of the atmospheric duct. In the investigation period, the main atmospheric ducts were elevated ducts, with an average bottom height of 738.64 m, an average thickness about 185.17 m, and an average strength of 10.21 M-unit. In the early stage of investigation, the weather was stable, and the northeast monsoon was weak in the study area, and the elevated ducts on the warm side of the front were relatively deep and strong but not very high. The main reason for the elevated duct layer is the temperature inversion layer on top of the atmospheric boundary layer from 925 hPa to 850 hPa, which also has significant diurnal characteristics. In the middle of the investigation, a cold surge significantly strengthened the northeast monsoon which destroyed the inversion layer at the top of the atmospheric boundary layer. As a result, the height of the elevated ducts rises significantly, and the duct layer becomes thinner and weaker. Meanwhile, the disturbance of the negative atmospheric modified refractive index gradient was weak due to the depressed turbulence over the cold side of the front. Thus, forming a stable and robust duct layer is difficult, and there is no significant diurnal variation. However, when the warm and humid air flows southwesterly covering the cold side of the front, it is highly possible to form a stable surface duct.

Long-term monitoring site was deployed in the southern Sanya Bay of the South China Sea, and continuous wave observations covering four seasons were carried out in April ~ October 2020 and December 2021 ~ February 2022. Based on the observational data, the basic statistical features of the wave in the sea area and their response characteristics to typhoon processes are systematically analyzed. The results show that the waves at the site are affected by local factors, such as wind field, bottom topography, shoreline, and current dynamics, thus showing characteristics of nearshore waves. Due to the weakening effect of shallow water topography and the control of shoreline boundary, the waves maintain long-term shoreward (i.e., northward) propagation with relatively small wave heights and periods, in which the significant wave heights and mean periods are less than 1 m and 4 s, respectively, for most of the time. Due to the influence of dynamic factors such as tidal current and sea-land breeze, the wave heights show a strong diurnal variation, and both wave heights and steepness increase (decrease) significantly when the flow direction is opposite to (the same with) the wave direction; driven by the strong wind speed in the same direction, the wave height and steepness also increased significantly. Waves respond significantly to the typhoon process, and the wave height increases significantly under the synergy of current. When the typhoon process is close to the site, the wave energy extends to both low and high frequencies, with the direction distribution changing significantly. If the path is far from the site, the wave energy mainly propagates to the site by the swell, and the energy distribution expands to low frequency while the direction distribution remains unchanged.

A total of 88 threatened fish species were selected for the study, and their spatial distribution was predicted using publicly available data and the MaxEnt model. The conservation gap analysis was performed based on the predicted distribution, and recommendations for the conservation of the East China Sea and adjacent sea areas were proposed. The results showed that the hotspot areas of threatened fish covered 1.58×10¹¹m², mainly located in the southern coastal area of the Yangtze estuary and the Taiwan Strait. Among them, the top 10%of the hotspot areas was about 5.68×10¹⁰m², mainly located in the coastal waters of Fujian and Guangdong provinces, and sea areas adjacent to Taiwan Island and Penghu Islands. Further investigation of the distribution patterns revealed that there were six different zones in the current distribution of threatened fish in the East China Sea. The existing marine protected areas are mainly concentrated in zones I and Ⅳ, while no protected area has been established in zones Ⅱ and Ⅲ, indicating that habitats of most threatened fish have not been effectively protected. These results provide a scientific basis for improving and optimizing the fish biodiversity conservation strategies in the East China Sea and adjacent sea areas.

Coral growth is essential for maintaining the coral reef ecosystem and coral reef development. Seawater temperature is one of the key environmental factors to control coral growth. With global warming, the persistent rise of seawater temperature has become a global threat to coral growth. Coral reefs are widely distributed in the South China Sea (SCS), and there is a significant regional difference in coral growth in the SCS. The Zhongsha Atoll, located in the central SCS, is the largest atoll in the SCS. The coral community is well developed, but little is known about the history of coral growth in this reef area. In 2020, we drilled a core sample of coral Porites lutea at water depth of ~16 m at the Zhongbei Ansha of the Zhongsha Atoll. The sample growth rate was analyzed which revealed a 165-year growth history of the coral Porites and its changing pattern at the Zhongbei Ansha. Compared with growth rate of the coral Porites at the Yongxing Island, Xisha Islands, the regional difference of coral growth in the middle part of the SCS and their response to the rise of the sea surface temperature (SST) was discussed. The average SST is about (27.4 ± 0.37) ℃ and (27.09 ± 0.36) ℃, respectively, at the Zhongbei Ansha and the Yongxing Island during the past over a hundred years. SST shows a linearly rising trend at both the two reef areas with a similar rate of about 0.43 ℃·ha^-1. The average growth rate of coral Porites is about (0.70 ± 0.16) cm·a^-1 and (1.19 ± 0.16) cm·a^-1 respectively at the Zhongbei Ansha and the Yongxing Island during the past over a hundred years. The growth rate has a linearly declining trend with a rate of about 9.4 %·ha^-1 at the Zhongbei Ansha in the same period, while the growth rate has increased linearly by 10.9 %·ha^-1 at the Yongxing Island. In addition, there are interdecadal fluctuations in growth rate in both two areas in the past over a hundred years, approximately corresponding to the interdecadal fluctuations in SST. A nonlinear responding relationship is found between the growth rate of coral Porites and SST within the linear trends at the two areas during the past over a hundred years, and there is an optimum temperature of about 27.25 ℃ for the growth of coral Porites. Moreover, a linear positive correlation exists in the interdecadal fluctuations between growth rate and SST. In the past over a hundred years, seawater warming has exceeded the appropriate temperature range for the growth of coral Porites at the Zhongbei Ansha, limiting the growth trend of coral Porites. At the Yongxing Island, however, the seawater temperature is still suitable for the growth of coral Porites. And then the interdecadal rise of the seawater temperature is conducive to the growth of coral Porites at both areas. Under the condition of continuous seawater warming in the SCS in the future, the declining trend in coral growth will be further aggravated at the Zhongbei Ansha, which will seriously threaten the maintenance and development of the coral reef ecosystem at the Zhongsha Atoll.

In order to clarify the influence of hydrological dynamics and environmental changes caused by human activities on the zooplankton community structure in the coastal waters of Guangdong-Hong Kong-Macao Bay Area, zooplankton samples were collected in 3 transections (in the Pearl River Estuary, Daya Bay and Huangmao Sea) in July 2019 (summer) and December 2020 (winter). The characteristics of meso- and micro-zooplankton community were analyzed, and the influencing factors of their seasonal and regional differences were discussed. A total of 211 zooplankton species (including larvae) were identified in the study area, among which copepods accounted for 42.18%. The diversity and abundance of zooplankton showed obvious seasonal and regional differences. The number of species and average abundance of zooplankton were higher in summer than that in winter, and the species diversity in offshore waters was higher than that in nearshore waters. The high values of zooplankton abundance were located in the interface of saline- and plume- waters of the Pearl River Estuary in both seasons. In summer, the average abundance in estuarine waters was obviously higher than that in the Daya Bay, while in winter there was no such difference in the nearshore waters. The results of cluster analysis showed that the zooplankton community could be divided into three groups, i.e. the estuarine group, the bay group and the far-shore group in summer. The estuarine waters was greatly affected by runoff, and the community structure was significantly different from that of the Daya Bay. However, there was no significant difference in community structure between the estuarine and the bay in winter. Parvocalanus crassirostris and Oithona brevicornis were dominant species in both seasons, Bestiolina amoyensis, Acartiella sinensis and Oithona simplex were also dominant in the wet season, while Paracalanus parvus was also dominant in the dry season. Pearson correlation analysis and RDA analysis results showed that there were interspecific and seasonal differences in the correlations between the abundance of different species and temperature, salinity, phytoplankton biomass and nutrients, suggesting that the complex water environment in the Greater Bay Area had a potential influence on the differentiation of meso- and micro-zooplankton community structure.

Based on the data of the comprehensive scientific cruise survey in eastern Indian Ocean from 2010 to 2019, Argo (array for real-time geostrophic oceanography) and SODA (simple ocean data assimilation), the interannual variability of subsurface high salinity water (SHSW) in eastern equatorial Indian Ocean was studied and its formation mechanisms was explored. The observation results limited to spring show that the high salinity water from Arabian Sea is distributed in 70~130m in eastern Indian Ocean equatorial section and exhibits significant interannual variations. And the result based on monthly SODA reveals that the trend of anomalous salinity of SHSW varies significantly in different periods, with a relatively stable trend from 2010 to 2015 and an obvious increasing trend from 2016 to 2019. Wind field and subsurface zonal current are dominant factors that control the interannual variability of the high salinity water by regression analysis of SHSW. Further analysis indicates that the anomalous easterly wind in equatorial Indian Ocean leads to the westward accumulation of water masses, then generates an eastward pressure gradient force, which in turn stimulates the anomalous subsurface eastward flow, and causes the increases of anomalous salinity of SHSW eventually. The dynamical connection is particularly remarkable in Indian Ocean Dipole, which further indicates that the interannual variability of SHSW is modulated by Indian Ocean Dipole.

The change characteristics of physio-biochemical indexes of four mangrove plants Rhizophora stylosa, Kandelia obovata, Bruguiera gymnorhiza and Ceriops tagal seedlings after 28 days of heavy metal aqueous solution stress at different concentrations were studied, including soluble protein content, superoxide dismutase (SOD), and peroxidase (POD) activity and oxidative damage marker malondialdehyde (MDA) content. The study results showed that the SOD and POD activities in the leaves of the four plants all increased first and then decreased. When the Rhizophora stylosa were treated with 10 times the heavy metal aqueous solution, the Kandelia obovata and Bruguiera gymnorhiza were treated with 5 times the heavy metal aqueous solution, the Ceriops tagal were treated with 1 time the heavy metal aqueous solution, it has good antioxidant enzyme activity during heavy metal aqueous solution treatment, which can effectively remove active oxygen and reduce oxidative damage. Under the same concentration of heavy metal aqueous solution treatment, the results of MDA content showed that the damage of the Rhizophora stylosa was the least, the Kandelia obovata and the Bruguiera gymnorhiza were equally damaged, and the Ceriops tagal were the heaviest. The ability of Rhizophora stylosa to resist heavy metal stress is stronger than Kandelia obovate and Bruguiera gymnorhiza, while the ability of Ceriops tagal to resist heavy metal is the weakest. These results show that mangrove plants have strong ability for anti-pollution, which has important guiding significance for mangrove ecological restoration and protection in China.

Storm surge disasters occur frequently along the Pearl River Estuary and are significantly affected by typhoon. This study analyzed the extreme surge at the Chiwan Station in the Pearl River Estuary during the past 30 years (1990-2019). The results show that the average annual storm surge in this region has not changed significantly recent years, but the extreme storm surge (99.9 quantile) has increased greatly (1.62 cm·a^-1), which means that the extreme storm surge disasters have continued to increase. In the past 30 years, the annual maximum storm surge in 20 years occurred during typhoons (accounting for 66.7%). In 2018, the maximum storm surge caused by super typhoon “mangkhut” reached 254 cm, which was the largest storm surge disaster in the past 30 years. The maximum response distance of storm surge to typhoon is about 500~800 km. Within the influence range of typhoon, the storm surge has an approximate linear relationship with typhoon intensity, and an exponential relationship with the distance from typhoon center. Different indexes of typhoon intensity (minimum pressure, maximum wind speed and maximum wind speed radius of typhoon center) were used to fit the storm surge with the distance from the observation station to the typhoon center, and it was found that the combination of wind speed and distance had the best description effect on storm surge (S_w=3.23e^-0.0036D×Γ_w-3.90)+4.48, R²=0.78, RMSE=9.69 cm). These results can improve the understanding of local storm surge disaster, provide validation data for typhoon storm surge simulation and reference for storm surge disaster risk assessment and response decision.

The effects of warming on the metabolism and photosynthetic physiology of symibiodiniaceae of two morphological types (H and S) of a reef-building coral, Galaxea fascicularis, were studied. The results showed that the physiological responses of H-type and S-type to warming were clearly different. At the symibiodiniaceae level, H-type lost a large number of symibiodiniaceae, and reduced the burden of respiratory metabolism of symbionts. In S-type, the number of zooxanthellae could still maintain the needs of symbionts for respiratory metabolism, while increasing the content of chlorophyll b to enhance light absorption. At the host level, the H-type made full use of nutrients delivered by zooxanthellae and compensated for energy consumption through heterotrophic feeding. The nutrients stored by the S-type host could assist the symbionts to adapt to the thermal environment. Galaxea fascicularis adapted itself to environmental changes through different energy utilization modes, i.e., H-type tended to maintain the metabolic balance of the symbiont, while S-type intended to improve the energy distribution of symbiotic algae.

This study investigates the characteristics of the east Guangdong shelf front and its dynamical regime using in-situ measurements, satellite data, and high resolution simulations by the regional ocean modeling system (ROMS). Observation results show active upwelling thermal fronts with horizontal scale of 50km on the northern shelf of the South China Sea in summer. The horizontal temperature gradient at the front is up to 0.06 ℃∙km^-1 and is stronger than satellite observed results in the same period. The front can reach 20m depth, and has the characteristics of the order-one Richardson number. Further diagnostic analysis using ROMS model output also show that the horizontal buoyancy gradient is enhanced at the front, with order-one Richardson number, which is favorable for frontal instabilities. High-resolution simulation results indicate that driven by the southwest wind in summer, the Ekman transport across the continental shelf caused by down-front wind, will accumulate cold water of upwellings to the warm water, enhancing the horizontal buoyancy gradient and front sharpness, and change the frontal baroclinicity, which leads to negative Ertel potential vorticity (EPV). As such, the Ekman buoyancy flux caused by summer monsoon may significantly contribute to the formation and instability of the continental front in the northern South China Sea, and it has an important impact on the local dynamic environment.

Coral reef ecosystems are important components of marine ecosystems and play a crucial role in maintaining marine ecological balance and biodiversity. This article summarizes the current international and domestic development status of coral reef ecology through literature review. The major international research focuses include global change and coral reef ecosystems, establishment and maintenance of coral symbiosis, development and evolution of coral reef biotic systems, coral reef biodiversity and species distribution patterns, as well as coral reef ecosystem conservation and management. The major domestic research focuses include global change and coral reef ecosystems, coral-algal symbiosis under global change, diversity of coral symbiotic relationships, human activities and the South China Sea coral reef ecosystem, and coral reef biodiversity and community patterns. The future development trends in coral reef ecology research will emphasize the coral and coral reef ecosystems under the context of global change, coral symbiotic mechanisms, marginal coral reefs, and coral reef conservation and restoration. Future research in coral reef ecology in China should enhance global perspectives, strengthen domestic and international collaborations, explore underlying mechanisms, improve systematic research, and enhance coral reef conservation and restoration studies.