With the comprehensive utilization of deep reflection and refraction seismic data, ocean drilling program and field outcrops, great progress was made in understanding continental margin. Especially on the structure, evolution and formation mechanisms of passive continental margins, which are undergoing a paradigm shift. Starting from basic concept and classification, this paper reviewed the deep crustal to lithospheric structure, the layer velocity, the subsidence feature, and the breakup pattern of several types of passive continental margins based on recent seismic explorations. Then, mechanisms of passive continental margin formation were discussed. Based on existing research progress, we found that magma-poor and magma-rich margins may have lots of similarities in pre-rift and syn-rift stages, either in lithological components or rifting structures. They just differentiated during breakup depending on whether there was the involvement of hot mantle. During rifting stage, passive continental margin may evolve into four or more types, such as the whole lithospheric breakup type, the upper crust remnant type, the lower crust exhumation type, the upper mantle exhumation type, among others. The different rheological structures, stretching rate and mantle temperature are among the most important factors affecting the marginal structure evolution. Mechanism for high velocity lower crust is summarized. Usually, serpentinization of exhumed mantle is responsible for magma-poor margin, whereas underplating caused by high temperature mantle is responsible for magma-rich margin. Inherited high-grade metamorphic rocks were suggested to be one of the other causes. The above research progresses on passive continental margins provide us references to the research of the South China Sea.

With extensive development of marginal basins and subduction zones, the western Pacific is a key area in scientific ocean drilling. This paper intends to show the current status of scientific ocean drilling and discuss potential future breakthroughs, through summarizing scientific ocean drilling results in geodynamics over the past 40 years in the western Pacific. Drilling results documented the evolution of the marginal basins, including the Japan Sea, the Philippine Sea and the South China Sea. Deep sea sediments and geochemical analysis of basalts provided important information for evolution of basins and mantle processes. Ocean drilling results verified that the dip of a subducting slab not only has an effect on dynamic mechanism of the subduction factory but also controls plate coupling at the subduction zone. A record depth of 3056 mbsf had been drilled into the forearc of Nankai Trough subduction zone and retrieval of rock samples from the seismogenic zone is expected in the next few years. Ocean drilling results support more than one hypothesis of formation of the oceanic plateaus in the western Pacific, including the Shatsky Rise and the Ontong Java Plateau. Pelagic brown claystone occurred in the southwestern Pacific marginal basin, and it’s formation was controlled by seafloor spreading. In both the South China Sea and the Celebes Sea, pelagic brown claystone lie directly above the basement basalt units. Because of the structural complexity and diversity of the western Pacific, many scientific problems still need to be resolved despite a large number of ocean drilling expeditions.

Using sandbox experiment and numerical simulation, we discussed deformation of a subducting seamount. Our results showed that the deformation mainly concentrated at the overlain ocean sediment when a seamount subducted beneath the accretionary wedge. The sediment was scraped into wedge, while the part in the tailing of the seamount was well stored. After the seamount entered the subduction channel, the oceanic crust began to bend downward. The bending provided more space for seamount subduction and caused the subduction angle increased. Above described subduction process decreased the coupling between seamount and continental crust, leading to occurrences of megathrust earthquakes largely reduced. This study also represented an attempt to investigate deformation of a subduction zone by multi-methods.

In the last century, paleomagnetism, especially studies on magnetic properties of oceanic crusts, have greatly promoted the development of the plate tectonics theory and the International Ocean Drilling Program. The oceanic crust carries two kinds of magnetic information: magnetic properties of the magnetic assemblage in the oceanic crust, and the paleomagnetic signals carried by these minerals. Generally, the oceanic crust consists of a lower oceanic lithosphere (including pillow basalt, gabbro and peridotite) and overlying marine sediments. This paper summarized the magnetic structure of the oceanic crust, and then discussed relevant dynamic processes including chronological indications of oceanic magnetic anomalies, dynamic processes of the Earth’s interior, kinematics of the oceanic crust, and evolution of hotspots. Then, we systematically summarized major progresses of magnetic studies of the South China Sea. Key scientific topics related to magnetic properties of oceanic crusts in future studies were also discussed.

We review research on the two- (2D) and three-dimensional (3D) deep seismic structures of the Mariana Trench subduction zone. We find that (1) the bulk composition beneath the basaltic volcanoes is basically consistent along the Izu-Bonin Arc. The seismic velocities of the middle crust in the arc crust are similar to those in continental crust. For the arc crust evolving to normal continental crust, a process, such as delamination, is necessary for the component of lower crust interpreted as mafic to ultramafic crust-mantle transition layer (CMTL) returning to mantle; (2) the intra-oceanic arc crusts with different ages show dissimilar velocity structures, implying different density structures and crustal growth models; (3) the temporal and spatial variation of velocity structure and evolution history in the arc system reveals the features of oceanic crust and mantle at the beginning of subduction and the reasons of subduction. Although the geologic setting of the Mariana Trench is different from that of the Manila Trench subduction, the research method could be borrowed. The critical issues of research are put forward for the Manila Trench, which include: implementing 2D combined with 3D Ocean Bottom Seismometers (OBS) seismic experiments, carrying out Ocean Bottom ElectroMagnetometers (OBEM) surveys, and long-term observations on earthquakes happened near the area. The project of the Manila Trench is promising for making breakthrough in mechanism on a subduction zone.

Using converted shear-wave information recorded by Ocean Bottom Seismometer (OBS) can promote our understanding about lithology and physical properties of crustal rocks. Taking 18 OBS stations along Profile OBS973-1 of Nansha Block in the South China Sea (SCS) as examples, we illustrated the method of OBS converted shear-wave identification. First, noise reduction processing of three-component OBS seismic data was completed using a band-pass filter, Wiener filter and polarization filter. Then, we used energy scanning method to find out the polarization angle, and obtained the optimal radial component data by horizontal component rotation. The results showed that the angle obtained by energy scanning method was more accurate and reliable than the magnetic compass angle recorded by OBS. Finally, the types of converted shear-waves were determined through the comparisons of travel times, particle trajectory and velocity model trial between vertical component and radial component. The method was applied successfully to the experiment in Nansha Block of the SCS for Profile OBS973-1. A few converted shear-wave phase groups, such as PgSs, PnSc and PmS, were identified in 10 OBSs. These results not only provided solid foundation for shear-wave velocity structure, but also offered experience and reference for effective application and promotion of OBS-converted shear-wave in other areas in the future.

Using the International Comprehensive Ocean-Atmosphere Data Set (ICOADS) and Simple Ocean Data Assimilation (SODA) reanalysis, this study investigates the decadal variability of sea surface temperature (SST) over the South China Sea (SCS) associated with El Niño-Southern Oscillation (ENSO) and Indian Ocean Basin (IOB) mode. Four epochs during 1870-2007 were identified with significant differences. The SST anomalies showed single peak of warming during the periods before the 1950s, and double peaks of warming after the 1950s. The results of ocean heat budget indicated that the oceanic advection anomalies contributed little to the SCS warming in an ENSO developing year during Epochs 2, 3 and 4. The SCS warming was mainly due to the latent heat flux and shortwave radiation anomalies associated the ENSO. However, the SCS warming in the summer of an ENSO decay year could attribute to oceanic advection during the periods after the 1950s. The different contributions of oceanic advection to the SST warming in the past 138 years indicated that the ENSO teleconnection to the SCS climate experienced decadal changes.

This study shows some numerical experiments based on the 3^rd generation wave model of MASNUM, in four cases of different wavenumber directional discretization numbers: 12, 24, 36, and 48, respectively in the Pacific Ocean in 2005, and compares the model results with 17 buoy observations. These results indicate that the discretization number of 36 is the best choice for the model setting in the mid-latitude area and the eastern Pacific, while the discretization number of 24 is the best choice in the low latitude region. Comparison shows that the best discretization number is 24 in winter while 36 in summer. We also find that when significant wave height is between 2.0 and 4.0 m, the best discretization number is 24. When significant wave height is lower than 2.0 m, 24 and 36 are both proper choices. We recommend choosing 36 when under poor ocean conditions. All above results show obvious improvements comparing with the case of discretization number 12. Therefore, we believe that the discretization number of the MASNUM wave model should be greater than 12, and that the number of 24 or 36 is a better choice.

Using the synchronous observations of two atmospheric electric field mills on different planes at the straits atmospheric observation center of Xiamen, the vertical distribution of atmospheric electric field was investigated, and the results were tested using other independent observations. The results showed that the intensity of atmospheric electric field increased exponentially with increasing height in the lowest 30 m of the surface layer in the coastal areas of Xiamen. In the same environment, the variation trends of atmospheric electric field at different heights were similar. The results provide a reference for calibrating atmospheric electric field observations at different heights. The change of atmospheric electric field is a good indicator for different weathers.

An NPZD(nutrient, phytoplankton, zooplankton, detritus) model with incorporation of a diazotroph function group was used to simulate the temporal change of ecosystem in the upstream Kuroshio Current. The modeled nutrients, chlorophyll-a, and productivity showed good agreements with the observations. The impacts of N₂-fixation on nutrient concentrations, plankton biomass, and detritus were assessed by comparisons of the modeled simulations with and without diazotrophs. Our results suggested that diazotrophs were most abundant in summer and fall when other phytoplankton were nitrogen limited. The mean growth of phytoplankton could increase by 64% with the input of new nitrogen from N₂-fixation, leading to 30% increase of primary production, regenerated production, and new production, respectively. In summer, N₂-fixation supported 50%~80% of the new production in the upper 50 m, but only 10%~50% in the depths of 50~200 m. This finding suggested that N₂-fixation was an important source of new nitrogen for phytoplankton production above 50 m in the upstream Kuroshio, but new production below 50 m was largely contributed by the vertical nutrient fluxes from below.

Based on the analysis of temperature and salinity survey data in the central South China Sea (SCS) in March2014, we found that there existed a notable low temperature and high salinity water mass in the northern Zhongsha Islands. The core temperature of the water mass was only 25℃ in the surface layer (5 m), which was lower than that at the surrounding stations by at least 1℃, and its core salinity was 34.11 psu, which was higher than that at the surrounding stations by at least 0.74 psu. Furthermore, the water mass had influence on an area of about 1 longitude by 1.5 latitude, just 30 m from the sea surface, and it could last approximately for 13 days. Combining with the topography data, satellite altimeter data and wind data, we demonstrated the forming and decaying processes and dynamic mechanisms of the water mass. In early March, a strong mesoscale cold eddy shed from the Luzon cold eddy system and propagated to the west; it stagnated and deformed when encountering the continental shelf at about 115°E, 18°N. However, under the induction of topography and wind, the southern edge of the strong mesoscale cold eddy shed a small cyclonic eddy again, namely, the low temperature and high salinity water mass that was observed. The water mass propagated to the Zhongsha Islands area around the 3000m isobath. The water mass vanished owing to the wind direction change from the northeasterly on March 29to the southerly at the beginning of April. The southerly wind accelerated the mixing between the southern warm water and the low temperature and high salinity water mass, and then the low temperature and high salinity water mass disappeared at last.

An unstructured grid finite-volume coastal ocean model (FVCOM) was applied to simulate the saltwater intrusion from Lingdingyang into the Humen estuary. Measurements of water level and salinity at multiple stations obtained in February 2001 were used for model calibration and verification, aiming at the hydrodynamic characteristics and spatiotemporal variation of salinity. The results showed that 1) the correlation coefficients between the predicted and measured water level exceeded 0.93 with a mean absolute bias less than 0.1 m, while the relative error of the simulated salinity was within 10%; 2) at Station Dahu, the flow direction in the surface layer was consistent with that in the bottom layer most of the time, but there was apparent salinity gradient in the vertical. However, for Station Zhangpeng, opposite flow directions between the surface and bottom layers occurred repeatedly while the salinity was more uniform vertically; and 3) the maximum distance of saltwater intrusion was well simulated. The intrusion distance as well as the strength at spring tide was greater than that at neap tide in the Humen estuary, and saltwater wedge movement was significantly affected by the tidal strength.

There is evidence showing a long-term weakened trend of the tropical Pacific Walker Circulation under global warming condition, consistent with the expectation that the circulation will be weakened further. But recent research shows that the Walker Circulation has intensified over the recent decades. Is there any contradiction between the two? We analyzed the strength change of the Walker Circulation during the last decades using the reanalysis data of the tropical Pacific over the 36-year period from 1979 to 2014. The result showed an overall trend towards a stronger La Niña-like Walker Circulation. On the interannual timescale, the El Niño-Southern Oscillation (ENSO) accounts for much of the variability in the Pacific Walker Circulation; but the strengthening of the Pacific Walker Circulation in the recent decades cannot be explained by global warming or ENSO. The Indo-West Pacific sea surface temperature (SST), the Indian Ocean-Pacific Walker Circulation, the SST over the Indo-Pacific region, and Maritime Continent area’s upward movement constituted a simple positive feedback system: stronger Walker Circulation accelerates more warm water to the warm pool area. Warmer SST in the warm pool region strengthens the convergence and upward motion over the Maritime Continent, which makes the Walker Circulation stronger. Besides, the Pacific Decadal Oscillation (PDO) was in the transition from cold phase to warm phase over the past decades, which intensified Pacific zonal SST gradient. The tropical Indo-West Pacific warming, tropical central eastern Pacific cooling and a closer connection between the two basins were the reasons of enhancement of Pacific Walker Circulation over the past decades.

Scale-selective data assimilation (SSDA), through considering multiscale features in both observational data and model variables during assimilation, can selectively adjust certain scales of motion while keeping other scales unchanged. To test the effectiveness of SSDA in ocean data assimilation, an exceptional anticyclonic eddy event in August 2010 over the sea area of the Xisha Islands (referred to as Xisha Warm Eddy) is chosen. In this study, we compared the effects of assimilating sea level anomaly (SLA) and its derived geostrophic currents. Geostrophic currents were assimilated in two ways, applying the SSDA or not. Results showed that assimilating SLA or geostrophic currents can both improve the simulation of Xisha Warm Eddy. On one hand, assimilating SLA improved the horizontal size of Xisha Warm Eddy since the velocity field followed the change of pressure field, permitting divergence of sea water. On the other hand, assimilating geostrophic currents improved the intensity of Xisha Warm Eddy because SSDA can adjust pressure field according to velocity field, which helped maintain the convergence of Xisha Warm Eddy. Simultaneously assimilating both geostrophic currents and SLA improved the simulation most significantly. Therefore, SSDA is necessary for assimilating geostrophic currents.

Based on in-situ observations supported by the National Natural Science Foundation of China during the summer of 2013 as well as satellite data, the summer coastal upwelling off eastern Hainan Island is examined in details, including its spatial structure, evolution process and the response to a tropical cyclone during the cruise. The results suggest that the upwelling anchored off eastern Hainan Island, with relatively weak signals at the sea surface. The observed strong upwelling mainly took place between the depths of 30-50 m below the surface. The temperature difference between the cooling center and the offshore non-upwelling water was more than 7°C, and the salinity difference was more than 0.7 psu. Moreover, the analysis of a tropical cyclone onset indicates that the structure of coastal upwelling in the upper ocean was completely destroyed, due to the shutdown of upwelling-favorable winds and intensive mixing induced by the tropical cyclone. Throughout these processes, the coastal upwelling lagged behind alongshore wind by 2-4 days

To obtain a continuous high-resolution oceanic precipitation data, eight different oceanic precipitation products, including COADS, ECMWF, NCEP, GPCP_GPI, SSM/I_EMISS, SSM/I_SCATT, TRMM_PR, and TOPEX-TMR, were merged using an optimal weighted coefficient method to produce a new merged precipitation product. The product was obtained based on the spatial-temporal characteristics of these precipitation products and the principle of data merging. The merged product was validated using actual precipitation data from nine coastal rain gauge stations and the eight products. The merged precipitation product is better than the other data sets in terms of accuracy, and can compensate for the limitation of other multi-source precipitation products, suggesting that the optimal weighted coefficient method is an important scheme for reducing information redundancy and increasing the complementation of multi-source oceanic precipitation data sets.

In four different seasons during March-December 2014, four oceanic function areas in Daya Bay, including in an artificial reef area, an aquaculture area, a thermal discharge area, and a petrochemical sewage discharge area, as well as the bay mouth area, were selected as the survey areas. Data of surface temperature, salinity, pH, and total alkalinity (TA) were analyzed to show the distribution of dissolved inorganic carbon (DIC) system, and to estimate sea-air CO₂ flux (F_CO2) and its influential factors. The results showed that the concentrations of surface DIC, HCO₃^-, CO₃^2-, and p_CO2 ranged from 1248.8 to 1841.9 μmol·kg^-1 (1624.8±143.1 μmol·kg^-1), 1069.2 to 1615.7 μmol·kg^-1 (1382.5±126.1 μmol·kg^-1), 152.7 to 283.5 μmol·kg^-1 (236.2±35.4 μmol·kg^-1), 11.4 to 44.9 Pa (21.2±7.4 Pa), respectively. There were no significant differences among the surveyed areas in terms of concentrations of DIC, HCO₃^-, CO₃^2-, and p_CO2 (P > 0.05). F_CO2 ranged from -37.3 to 4.5 mmol·(m²·d) ^-1 [-22.4± 9.8 mmol·(m²·d)^-1]. The seasonal variation of F_CO2 showed an order of summer > autumn > spring > winter, according to positive or negative data; and this parameter in summer was significantly higher than those in the other seasons (P < 0.05). At the annual scale, F_CO2 in each investigated area had a negative value, indicating a sink of atmosphere CO₂. The distribution of regional carbon sink was in the order of bay mouth area > artificial reef area > petrochemical sewage discharge area > thermal discharge area > aquaculture area, no significant difference being found among these areas (P > 0.05). Based on partial regression coefficients, salinity was the main influencing factor for F_CO2 in the bay mouth area and agriculture area; water temperature was, in the artificial reef area and thermal discharge area; and pH was, in the petrochemical sewage discharge area.

In this study, based on fish samples collected in Beibu Gulf in July 2012, diet composition, feeding habits and trophic niche breadth of nine economic fish species were analyzed using the Shannon-Wiener index, Levins index and evenness index. Results showed that nine economic fish species could be classified into three types according to feeding habits, referred to as plankton predators (including Acropoma japonicum, Trachurus japonicus, Decapterus maruadsi, and Polydactylus sextarius), benthic predators (including Evynnis cardinalis, Upeneus japonicus and Psenopsis anomala) and nekton predators (Saurida tumbil and Pennahia argentata). Trophic niche breadth of Pennahia argentata was the highest (Shannon-Wiener index=0.938 and Levins index=2.238), while trophic niche breadth of Saurida tumbil was the lowest (Shannon-Wiener index=0 and Levins index=1). The trophic niche breadth of the nine economic fish species in summer in Beibu Gulf was strongly influenced by feeding habits and feeding foundation of surrounding environments.

A survey of macroalgal resources in the Xisha Islands was carried out from March to April 2014. A species of Gelidium sp. was collected and identified as Gelidium pusillum var. pacificum Taylor. The main characters of this species were as follows: 1. thallus purple-red, caespitose; 2. plants up to 1-2 cm high, composed of creeping and erect axes, creeping axes slender cylindrical, and the upper part of erect axes compressed, with irregular or pinnated branches; 3. in transverse sections, cortices consist of 2-3 layers, and rhizoidal filaments were abundant in medulla; 4. tetrasporangium ovoid in transverse view, embedded in the cortical cells, divided cruciately and developed on the apical part of branchlets, forming sori; and 5. the apical cell of the main axis was globose, dome-shaped, protruding out of cortical cells. Gelidium pusillum var. pacificum can be segregated from other variants within Gelidium pusillum by combining characters 1 to 3. Characters 5 can be used to distinguish Gelidium pusillum var. pacificum from small sized Pterocladiella species, such as Pterocladiella caerulescens. Characters 4 cannot be used to discriminate it from its related species, because the size and shape of sori vary similarly. Thus, apical morphology may be a promising vegetative attribute to segregate small sized Gelidium species from some similar Pterocladiella species found in China. Gelidium pusillum var. pacificum was the first record in Sansha region of the South China Sea, which enriched the species diversity of this marine algal flora and further facilitated the analysis of general aspects of this marine algal flora.

Tidal inlet, which connects water inside and outside a bay, and maintains water exchange and channel’s navigation, is the core and foundation of an inlet system. Based on observational data, sea charts and topographic maps, the hydrodynamic and sediment transport processes affected by natural and human activities in Zhelin Bay were studied with SELFE (semi-implicit Eulerian-Lagrangian finite-element) model, and the evolutions of the tidal inlets were revealed. It was confirmed that tidal areas of Zhelin Bay with 125 km² before the reclamation were independent and large for each inlet, whose stability was maintained. After the 1970s, the reclamation made the tidal water areas dropped to 50%, the hydrodynamic structure of tidal inlets changed accordingly, and the suspended sediments from the outside of the bay transported into Zhelin Lagoon and deposited into the Sanbaimen Channel. The tidal area of Xiaojinmen Inlet changed little, so the hydrodynamic and sediment transport of inlet was still ebb-tidal dominant. The circulation of Xiaojinmen Inlet was enhanced, which resulted in the adjustment of erosion and deposition. The tidal area induced by Dajinmen Inlet dropped 1/3 to 40 km², which weakened the asymmetry of flow velocity. The circulation of Dajinmen Inlet promoted the deposition in the west and the erosion in the east of the inlet section. The tidal area of Xiaomen Inlet collapsed by more than half, which resulted in narrowed inlet width, extended length and shallower water depth; and the circulation between Dajinmen Inlet and Xiaomen Inlet intensified the deposition and instability of Xiaomen Inlet.

Analysis of island reefs’ land cover evolution plays an important role in the exploitation of island reef, the conservation of marine resources and the development of marine economy. This paper is based on high resolution remote sensing images. With the usage of technologies of remote sensing and GIS (geographic information system), a series of experiments of land cover classification, extraction and change detection were done for Zhaoshu Isle, which belongs to the Xisha Xuande Isles, from 2008 to 2014; eventually Zhaoshu Isle long phase surface coverage status was formed. A classification system of island reefs’ land cover was built as the basis. With the usage of land cover and transfer matrix, along with the consideration of change parameters such as net changes, exchange variation and total amount of changes, an analysis of the land cover variation of Zhaoshu Isle has been performed.

Understanding biogeochemical processes associated with oceanic eddies is important, and ocean-color remote sensing has been used as a tool to provide large-scale data for such studies. Based on the latest regional bio-optical inversion algorithm in the South China Sea, we used Moderate Resolution Imaging Spectroradiometer (MODIS) to track and monitor a cold eddy originated in the late winter around the Luzon Strait. In the early stage, the eddy carrying high nutritional and high biomass seawater moved toward northwest. Then, the eddy stayed in an area for a month. During this period, with the continuous suction of the eddy, the concentration of chlorophyll-a (Chl-a) increased from 0.26 to 0.33 mg•m^-3 in the eddy area and decreased from 0.24 to 0.15 mg•m^-3 outside the eddy. The concentration of particulate organic carbon (POC), phytoplankton absorption coefficient (a_ph(443)), diffuse attenuation coefficient (K_d(490)) and colored dissolved organic matter (CDOM) showed the same variation trend with Chl-a, while the POC∶Chl-a ratio and fraction of picoplankton (F_p) exhibited opposite trends. When the eddy moved westward, Chl-a, POC, a_ph(443) and K_d(490) decreased slowly because of the weakening of eddy intensity and nutrient supply. Our results demonstrated that the special bio-optical response induced by eddy pumping and advection can be an additional tool to track and study oceanic eddies.

In this study, we conducted barotropic detiding of the summertime shipboard ADCP (SADCP) dataset in the southern Taiwan Strait (TWS) from June to September during 2004-2013, employing the widely used spatiotemporal fitting by the least squares method (STF-LSM). The results show that the mean flow derived from STF-LSM and that derived from averaged vectors by dataset gridding both flowed northeastward. Moreover, these two mean flows had similar spatial distribution patterns of strong and weak flows, but their maximum velocities were slightly different: 0.46 and 0.34 m·s^-1 for the former and the latter, respectively. Besides, the strong currents (about 0.3 m·s^-1) were characterized by the narrow mainstream confined around the depth of 30 m off the sea at Dongshan and Longhai as well as the Taiwan Bank (TWB) with drastic topographic change, whereas the weak currents (less than 0.1 m·s^-1) were mainly distributed in the central TWB. Estimation of the volume transport based on the above mentioned mean flows revealed similar results, up to (0.71±0.24) ×10⁶ m³·s^-1. The strong M₂ tidal currents derived from SADCP were near the TWB and extended to the offshore of Dongshan, with a maximum M₂ current amplitude as large as ~0.64 m·s^-1, which was located in the TWB. The cotidal chart for M₂ currents demonstrates the characteristics of progressive wave, which was delayed successively from the southwest to the northeast along the direction of the tidal wave as the wave propagated (about 2 h). Besides, there was a boundary line along northwestward to southeastward direction with ellipticity equal to zero at the offshore of Dongshan. The M₂ currents rotated counterclockwise in the southern region of this boundary line and clockwise in the northern region.

The influence of different melting time of Greenland ice sheet on sea level of the global and regional oceans were studied using the ocean model parallel ocean program (POP) under the representative concentration pathway 4.5 (RCP 4.5) scenario for the 21^st century. Results showed that the Greenland ice sheet melting with 7%•a^-1 acceleration in the year round has more notably influence on the global and regional sea level variation than melting only in the summer months from May to October. The dynamic sea level rise shows acceleration in the Arctic and subpolar North Atlantic, but it decreases in the west coast of Europe and subtropical North Atlantic. The steric sea level rises fast along the coast of North America, subpolar North Atlantic, tropical Atlantic, and the subtropical South Atlantic, but falls in the Arctic, the west coast of Europe and subtropical North Atlantic. The different influences of the Greenland ice sheet melting on sea level change between the year round and the summer months cases mainly due to the notably weakened meridional overturning caused by strengthened stratification of the upper ocean and weakened deep convection because of a lot of freshwater input regions near Greenland in the high rate of melting Greenland ice sheet. The accumulation of water in the subpolar North Atlantic caused by weakened meridional overturning, which leads to dynamic sea level rise in the subpolar North Atlantic. The weakened transport of heat and salt from the tropical Atlantic to high-latitude ocean was caused by weakened meridional overturning, so that more high temperature and saline water was stranded in the tropical Atlantic; part of high temperature and high salinity water was brought by the Gulf Stream to the Gulf Stream region, leading to accelerated thermosteric sea level rise and significant halosteric sea level decrease in the Gulf Stream and tropical North Atlantic. The waters of the subpolar North Atlantic and Arctic cool and become less saline, some cold and less saline water was brought by the wind-driven circulation to the subtropical North Atlantic, which led to opposite change of thermosteric and halosteric sea level to tropical North Atlantic.

Using the retrieved data from CloudSat during August 3-11, 2006, the vertical distributions of ice particles in the clouds of different parts of tropical cyclone (TC) Saomai (2006) were analyzed, in their formation period, development-to- mature period and weakening period. The results are as follows. When the space-borne radar swept through different parts of TC Saomai (2006), ice particles in the clouds mainly distributed from the height of 5 to 16.5 km. The ice particle effective radius (r_e) reduced with increasing altitude and the large particles were mainly concentrated at the bottom of the ice clouds. The ice particle number concentration (C_in) increased with increasing altitude and large particles were mainly at the top of the ice clouds; the vertical distribution of the ice water content (C_iw) had a shape of unimodal or bimodal. The heights of the maximum r_e, C_in and C_iw were different from each other, and the ranges of the maximum what for r_e, C_in and C_iw were 107.9~177.7 μm, 123.8~827.9 L^-1 and 211~2858 mg•m^-3, respectively.

Using the satellite sea surface temperature (SST) from 1991 to 2015 over the equatorial Pacific Ocean, the variation of tropical instability waves (TIWs) and its relationship to El Niño-Southern Oscillation (ENSO) were investigated. The activity of TIWs was measured by the root-mean-square value of the 20~50 day band-pass-filtered SST perturbations. Remarkable TIWs were found in the Niño3 area (150°W-90°W, 5°S-5°N), where the mean TIW activity was approximately 0.20°C, with its maximum exceeding 0.35 ℃ between the equator and 3°N. In addition, the TIW activity was weaker south of the equator, in which its strength reached 0.2 only in the winters of 1998, 2007 and 2010 when La Niña events occurred. The pattern that the TIWs were more active during La Niña and less active during El Niño events was confirmed. Meanwhile, we found that the TIW activity, while in phase with the strength of the surface zonal current shear and the cold tongue front, led the ENSO amplitude about 2~3 months due to its more rapid response than the Niño3 SST to dynamic and thermal processes in the equatorial Pacific associated with ENSO. This implies that the phase and activity of ENSO can be predicated by the TIW activity a few months earlier from satellite SST observations.

Acoustic and physical properties of surficial marine sediments are mainly influenced by the grain size and show obvious regional variations. This study was conducted on the mutual relationship between the parameters of offshore sediments in the southeastern Hainan Island by measuring the sound velocity, porosity and grain size. The results exhibited that the compression wave velocity of the seafloor sediment was variable between 1455 m•s^-1 and 1773 m•s^-1. From the northeast to the southwest in this study area, the wave velocity of seabed sediments decreased and four zones with different sound-velocity could be divided. The regression analyses showed that the grain size had a negative relationship with the porosity and positive relationship with the sound velocity. The finer sediments had larger porosity and lower sound velocity.

Distribution of p_CO2 in the surface water of the western South China Sea (SCS) was examined using data for autumn 2012. In this study, the control factors of surface p_CO2 were investigated and sea-air CO₂ flux in the study area was estimated. The results showed that sea surface p_CO2 values of 37.8 to 57.1 Pa were observed in the western SCS. The sea surface p_CO2 was always higher than that in the atmosphere, which indicated the western SCS acted as a source of the atmosphere CO₂ in autumn. In the study area, sea surface p_CO2 was mainly controlled by carbonate thermodynamics, and sea surface temperature (SST) was the predominant factor that controlled p_CO2 distribution. However, sea surface p_CO2 was also influenced by other factors in some areas. The transport of Mekong River diluted water led to low surface salinity water located in the Vietnamese eastern offshore region. Water mixing between Mekong River diluted water with high p_CO2 and offshore water affected the regional surface p_CO2 distribution directly. Furthermore, calcification process of coral reef organisms caused extremely high sea surface p_CO2 to exist in the western Swallow Reef of the Nansha Islands. The CO₂ outgassing rate of the western SCS in autumn was mainly influenced by sea surface wind speed, with average CO₂ outgassing rate of 2.9 mmolC·m^-2·d^-1 in the northern continental shelf and northern basin and of 0.9 mmolC·m^-2·d^-1 in the central and southern basins. The effect of metabolism of coral reefs in regional areas should not be neglected in CO₂ flux estimation.

To detect the relationship between horizontal distribution of fish assembles and water masses or between seasonal distribution of fish assembles and water masses, three fish trawl surveys were conducted in the southwest waters of the Nanri Islands in December 2009 and in April and August 2010. Density and distribution pattern of fish assemblages, body length, body weight, juvenile ratio, dominant species, index of relative importance, and contribution to the total number of dominant species were analyzed in the study. The results showed that fish densities in terms of both weight and number were higher in summer (2599.60 kg·km^-2, 22.6×10³ ind·km^-2) than those in spring (601.26 kg·km^-2, 17.3×10³ ind·km^-2) and winter (730.36 kg·km^-2, 22.6×10³ ind·km^-2). The average body length of fish was the highest in spring (14.95 cm), while the average body weight was the highest in winter (49.76 g). The proportion of juvenile was the highest in summer (as high as 81.72%). The variation in distribution pattern and biological parameters of fish assembles was probably associated with spawning and forging activities of fish. For example, it was mainly composed of spawning adult assembles in spring, while foraging juveniles were predominant in summer. Distribution pattern of fish assemblages was related to the seasonal variation in water mass and food availability in the coast water of Fujian. Fish densities were higher on the offshore side of Zhejiang-Fujian coastal water and Taiwan Strait warm current water. While in summer fish was more abundant in the nearshore region where food was particularly abundant. The distribution pattern of fish assemblages was consistent with the distribution pattern of dominant fish species.

The relative expressions of stress genes Hsp70, Hsp90 and choloplast psaA, psbA (SAM as reference gene) in Galaxea astreata endosymbiotic zooxanthella (Symbiodinium spp.) under heat stress were detected by using real-time PCR technique. All samples were exposed to elevated temperature at 32 ℃ over a 7-day period, and then the temperature was reduced to 28 ℃ gradually, with the temperature change from 28 ℃ to 32 ℃ at a rate of 1 ℃ per 24 hours. The results showed that the expression patterns of Hsp70 and Hsp90 were similar. The induced expression levels were upregulated but showed no significant difference compared to the control group (p>0.05) during the early stage of temperature climbing, subsequently reaching the maximize level after 168h tolerance period at 32 ℃. The lowest abundance of the gene products was detected when returned to the normal condition of 28 ℃ after 5-day recovery. Moreover, we examined the expression levels of chloroplast psaA and psbA genes stimulated by heat. Both were increased at the initial stage of thermal stress, and reached maximize at 31 ℃ for 24 h, with 1.2 and 1.9 folds compared to the level of the untreated group, respectively. Subsequently at 32 ℃, psbA transcripts maintained the high level until 24 h consecutive hours of stress, while psaA immediately decreased significantly (p<0.01). When temperature recovery reached 28 ℃, the transcripts of the two genes were significantly lower than the initial level (p<0.01), which indicates that the photosynthetic function of endosymbiotic zooxanthella may be injured (or inhibited).

Based on the samples collected in surface waters from three functional areas including 13 sites (cage fish culture area, oyster-algae mixed culture area and non-aquaculture area) in Baisha Bay in April 2014, species composition and abundance of planktonic ciliate were investigated. They were combined with environmental data to obtain spatial pattern of the ciliate community and its relationship with environment variables. A total of 19 species belonging to 11 genera and six orders were identified. The mean abundance of ciliate was 995.4±123.1 ind•L^-1 (80~3740 ind•L^-1), and Tintinnida, Stombidiida and Cyclotrichida were the most abundant in terms of both number and abundance. There were six dominant species (dominance Y≥0.02), including Mesodinium rubrum, Strombidium conicum, Tintinnopsis beroidea, Strombidium globosaneum, Tintinnopsis minuta, and Spirotontonia turbinata. Clear spatial distributions in terms of species composition and abundance were observed. Planktonic ciliate was more abundant and diverse in the oyster-algae mixed culture area and non-aquaculture area, but lowest abundance and species occurred in the cage fish culture area. Clustering analysis also indicated that the total samples could be separated based on spatial distribution. Redundancy analysis demonstrated that the nutrient level and Chlorophyll a concentration were the most important factors affecting the spatial pattern of planktonic ciliate community in Baisha Bay.

The bacterial strain HSY-03 is closely related to the genus Bacillus sp. and capable of inhibiting the toxic dinoflagellate Heterosigma akashiwo. It was isolated from the mangrove area in Yunxiao, Fujian Province, China. Based on 16S rRNA gene sequences and morphological characteristics, the strain HSY-03 was determined to be Bacillus sp. on the basis of 99.0% similarity with reference strain sequences from the NCBI. HSY-03 indirectly attacked Heterosigma akashiwo by secreting extracellular substances. The algicidal compounds could not be proteinaceous, nucleate and polysaccharide, which showed heat tolerant and being stable in UV as well as acidic and alkaline conditions. The bacterial strain was species-specific among the 13 algae tested. There was a close interaction between initial bacterial and algae cell densities. Bacterial HSY-03 showed strong algicidal activity when the initial concentration was above 5.0%. HSY-03 showed certain algicidal effects on Heterosigma akashiwo during different growth periods, especially during its stable and decline phases. These findings provided a novel viewpoint on biological control of harmful algal blooms and the relationship between the bacteria and algae.

Genetic diversity of several wild and hatchery populations of Crassostrea angulata from Fujian and south Guangdong coast was analyzed by 10 microsatellite markers with high polymorphism and non-genetic-linkage among them. Three hatchery populations were sampled from Zhangpu of Fujian Province (zp1), Raoping (zp2) and Daya Bay (zp4) of Guangdong Province, and the wild population (zp3) was collected from Zhangpu of Fujian Province. The results revealed that high level of genetic diversity existed not only in wild population but also in the three hatchery populations with the expected heterozygosity ranged from 0.769 to 0.857 in the hatchery populations and 0.878 in the wild population. The observed heterozygosity ranged from 0.410 to 0.518 in the hatchery populations and 0.529 in the wild population. The gene diversity was also high in the hatchery populations (ranged from 0.769 to 0.857) and wild population (0.878). The results showed that the germplasm recession problems did not exist in both wild and hatchery populations. Significant genetic differentiation existed among these four populations, suggesting that genetic exchanges were limited among them. Since the genetic diversity of the hatchery populations was lower than that of the wild population, germplasm recession of C. angulata should be concerned and prevented.

This paper dealt with a new record species of the Conus collected form South China Sea, Conus tagaroae (Limpalaër & Monnier, 2013). Detailed descriptions of shell morphology and comparison with similar species were presented. All specimens were deposited at the Marine Biodiversity Collections of South China Sea, Chinese Academy of Sciences.

Pressure gradient across the Luzon Strait, or depth-integrated dynamic height difference (DHD) between its northern end at the continental slope southwest of Taiwan and its southern end at the continental slope northwest of Luzon, is commonly regarded as the most direct dynamics of the intrusion of waters from the Pacific into the South China Sea through the Luzon Strait. Such a positive DHD is determined by seasonal occurrence of a meso-scale cyclonic cold eddy off west Luzon (Luzon cold eddy, LCE), and a positive wind stress curl (WSC) over the LCE active area or direct Ekman pumping may play a major role in generating the LCE. Based on the above ideas, prominent interannual (roughly 3 years and 7 years) and decadal (roughly 14 years) variability in the upper-layer Luzon Strait transport (LST) was first revealed using the 62-year (1950-2011) hindcast outputs from an eddy-resolving ocean general circulation model. To seek local factors affecting the interannual and decadal variability of LST, deseasonalized anomaly field of WSC over the LCE active area was analyzed using empirical orthogonal function (EOF). Dominant EOF modes of WSC anomaly were obtained. Spatio-temporal variability of the first EOF mode is of prominent decadal oscillation with a period of roughly 14.2 years and decadal southward shift of positive phase of the WSC anomaly, while the second EOF mode is of interannual oscillation of roughly 3.3 years and interannual northward shift of positive phase of the WSC anomaly. On the other hand, the near 7-year interannual oscillation was noticeable and can be regarded as an imprint of the variability of Kuroshio volume transport at its origin.

The dynamic characteristics of time-mean meridional overturning circulation in the Indian Ocean was examined using six reanalysis datasets. The results showed consistent time-mean features of the deep meridional overturning circulation, which is an anticlockwise overturning cell with inflows in the bottom and deep layers and outflows in the intermediate and upper layers. Dynamic decomposition of meridional overturning circulation was applied to examine the similarities and differences of every dynamic component. The structure of Ekman component is an anticlockwise overturning cell in the South Indian Ocean with maximum strength at ~10°S. In the region south of 10°S, geostrophic and external components show clockwise and anticlockwise overturning cells, respectively, they both reach maximum strengths at ~27°S. Based on different products of heat and momentum fluxes used, the dynamic components resulted from the six datasets show some inconsistent features as follows. The overall structures of Ekman component are similar since the wind fields of the six datasets have few differences. The discrepancies of the geostrophic component in the six datasets are due to the strength of the baroclinic flows in the interior ocean and the structure of the western boundary current: the greater the baroclinic flows in the interior ocean, the stronger the strength of the geostrophic component; the wider the western boundary current, the greater impact on the baroclinic flows in the interior ocean, and then on the strength of the geostrophic component. The strength of the external component is affected by the intensity of the western boundary current: the greater the western boundary current, the stronger the strength of the external component.

The energy of winds into surface waves in the South China Sea during 1871-2008 was estimated by using the ocean reanalysis data of SODA (simple ocean data assimilation) 2.2.4 (1871-2008). The results showed that the annual wind energy input is about 0.2 TW, and that the spatial pattern of this kind of input is mainly located in the northern parts of the South China Sea during winter and in the southern parts in summer; and the intensity of summer input is much weaker than that of winter. Similar results were obtained by using the ERA-40 (European Centre for Medium-Range Weather Forecasts re-analysis-40) (1957-2002) and ERA-20C (1900-2010) data sets. The secular trend of wind energy input into waves was reduced at the rate of 0.43% per year since 1950. We also studied the swells and wind waves, which are two categories of the waves, by using the ERA-interim data. The spatial pattern of wind energy input into the swells and wind waves is mainly located in the northern parts of the South China Sea, but there is also a high wind energy input into the wind waves area in the southern parts of the South China Sea. The secular trend of the wind energy input into swells was increasing, and the same trend of wind energy input into the wind waves was reducing; the total energy input was also reducing by the joint effect of swells and wind waves. All of this was thanks to the weakening East Asian monsoon, which dominated in the South China Sea, in recent decades. These results are significant for understanding the variation of the surface waves in the South China Sea.

HF shore-based radar was deployed to investigate the real-time effect on the marine environment of the Beibu Gulf during typhoon period. Wind field parameters retrieved from sea echo, by means of the forming mechanism of sea echo Doppler spectrum and wind-driven principle of echo spectrum, were applied to study the marine environment of the Beibu Gulf during Typhoon Usagi. The dta contained real-time wind field information in the Beibu Gulf, which provided support for the deep current inversion of the Beibu Gulf under typhoon condition.

There are great quantities of natural gas hydrate beneath seawater, which are giant resources potentially and capable of damaging environment; and special species is also discovered in related area. So, the detection and quantification of an underwater gas release are becoming increasingly important for oceanographic and industrial applications. According to the characters of acoustic attenuation when acoustic wave propagates through bubbles, detection of different flow rate of bubbles was conducted, and result of the relation of bubbles flow rate and acoustic attenuation was presented. In addition, the rising velocity of bubbles was estimated using the relate flow method of two signals received at different depths. Then, the flux of bubbles was inversed by acoustic signal, and the bubble distribution was calculated by the rising velocity and flux, which provided a new method for detection and quantification of undersea bubbles.

Seasonal distributions of particulate organic carbon (POC) and dissolved organic carbon (DOC) concentrations, as well as their sources, transports and mixing behaviors, in the Pearl River estuary (PRE) are reported in this paper. Samples were collected in November 2013, and in February, May and August 2014. The results suggest that the sources of POC were mainly in situ aquatic phytoplankton, and the source of DOC was mainly input from terrigenous organic carbon. However, aquatic phytoplankton might have contributed less to POC in May than in other months due to intensified erosion by high rainfall during May, and terrigenous organic carbon contribution to DOC increased in August. DOC was always the main portion, i.e., higher than POC, in the total organic carbon. The conservative mixing process of riverine and marine organic carbon occurred from the low salinity zone (salinity of 1‰~5‰) near the Humen Outlet to the open sea area out of the PRE. Biological degradation may have played an important role in reducing POC and DOC concentrations in the upper reach of the Humen Outlet. Preferential consumption of fresh phytoplankton organic carbon, reduction of phytoplankton production, and flocculation and sinking of particulate matter might have collectively resulted in the much more reduction of POC than DOC in the upper reach.