The spatial structure characteristics of Zhejiang and Fujian (Zhe-Min) coastal water (ZMCW) were analyzed in this study, using achieved ocean data collected in the offshore area of Zhe-Min during winter 2006. The evolution of the ZMCW was then explored using the CTD data in the Taiwan Strait during winter 2001, spring 2002 and autumn 2002, combined with the salinity data from ocean stations at Sansha, Beijiao, Pingtan, Chongwu, and Nan’ao, all located along the coasts of Fujian and Guangdong. The results indicated that the ZMCW exists in the Zhe-Min coastal area, and its eastern boundary is roughly parallel to the Zhe-Min coastline. The average distance between the eastern boundary of the ZMCW and the Zhe-Min coastline is about 55.8 km, with the maximum being about 94.5 km. The influence depth of the ZMCW increases southward gradually from south of Qiantang Estuary in Zhejiang, which reaches its maximum (42.0 m) in the offshore region of Minjiang Estuary in Fujian, and then decreases gradually southward from there. The ZMCW appears and extends to Sansha and Beijiao first in September, but does not reach Pingtan. In October, it moves further southward to Chongwu. The ZMCW peaks during November and the following February when its southern boundary reaches as far as the adjacent area between Dongshan Island of Fujian and Nan’ao Island of Guangdong. It begins to weaken in March or April. In May, it retreats to the adjacent area of Pingtan Island, and almost disappears in June.

Beach is often the first coastal tourism destination of people, which has important tourism economic value. Rip currents are potential hazard to the visitors who go to the beach, and have caused significant loss of life and property. A rip current hazard assessment method is proposed here based on the beach state model of Masselink and Short (Ω-RTR model, Ω is dimensionless fall velocity, RTR is spring tide range). After collecting morphodynamic parameters (wave parameters, tidal range and sediment grain size) of 51 South China beaches, a preliminary assessment of the rip current hazard was carried out using the Ω-RTR method. Results show that the coast sections of southern Fujian, Shanwei of eastern Guangdong, Yangjiang and Maoming of western Guangdong, eastern and southern Hainan have the highest rip current risk. The evaluation results were compared with remote sensing images and related media reports. Although the results are helpful to select and manage recreational beach locations, more field observations must be taken for a more specific assessment of beach rip current risk hazard.

Drifter data and the Lagrangian coherent structures (LCSs) are used to discuss the upper-layer circulation and water exchange near the Luzon Strait. Our results show that the LCSs, which are extracted from the surface currents, can depict the transport structure of the study area, and explain the motion of drifters reasonably. There exist southeast-northwest orientated LCSs, which extend from the Pacific Ocean to the South China Sea through the Luzon Strait during winter; during the summer, the orientation of those strait-crossing LCSs turns into southwest-northeast. The LCSs-formed transport pathways and barriers give reasonable explanation of the seasonal tendency of water exchange in the Luzon Strait, and the two types of the LCSs act as the pathways of the surface water exchange between the Pacific Ocean and the South China Sea.

Colored dissolved organic matter (CDOM) is an important factor that affects the optical properties of Chinese offshore waters. Based on the absorption coefficient data of CDOM from 895 stations surveyed during China’s offshore marine optical investigation, we analyzed the variation characteristics of the spectral exponential slope (S_g) of CDOM. Results show that the range of the spectral exponential slope of CDOM in Chinese offshore waters is from 0.0066 to 0.0284 nm^-1. The value of S_g obeys a normal distribution in most of the study areas. The average value of S_g is 0.0142 nm^-1 and its standard deviation is 0.0044 nm^-1 in the whole study areas. The component of CDOM is influenced by terrigenous sediment and marine sediment in China’s offshore, and the distribution characteristics of S_g vary spatially. Except for the weak negative correlations in two areas, there is no obvious relationship between S_g and a_g(440) in most of the Chinese offshore waters surveyed.

The Baiyun Sag is located in the northern passive continental margin of the South China Sea. The widespread faults around the sag affect the migration and accumulation of hydrocarbon profoundly. Faults control the sedimentation of source rocks from the Eocene to the Early Oligocene, regulate the range of reservoirs from the Late Oligocene to the Middle Miocene and dominate the seals and traps during the reactivation period in the Late Miocene. We attempt to study the controls of fault activity on hydrocarbon migration and accumulation through faults sealing analysis and basin modeling. Results are as follows. (1) The episodes of fault activity couple well with the generation of hydrocarbon. (2) Overpressure due to hydrocarbon generation may accelerate faulting activity at ~18.5 Ma. (3) Active faults act as perfect conduits for vertical migration of hydrocarbon. (4) Shale smear is much more credible in reflecting the sealing ability of motionless faults than the simple fault activity analysis. (5) The southern faulted area in the deep water tends to be more favorable for hydrocarbon accumulation than the northern area.

Samples of Polysiphonia scopulorum var. villum (J. Agardh) Hollenberg have been collected from Nan’ao Island, Shantou, Guangdong province during the field survey of November 2013~February 2014, and identified. We found the following combination of the characters: 1. the plants grown densely in tufts on rocks with villous mat shape; 2. the thalli composed with prostrate and erect branches in which the erect branches were less than 1 cm high; 3. the erect branches, sparsely branching out or not, with blunt apical cells; 4)the rhizoids stretching outward from the middle part of the pericentral cells with open connection; 5. the trichoblasts being sparse and short with 1~3 dichotomies, deciduous, often leaving conspicuous scar-cells; 6. mature cystocarps being ovate with a protruding ostiole; 7. the spermatangial branches arising from the entire trichoblast primordium, being arranged in a spiral manner at the tip of the branches, cylindrical without a celled sterile tip; and 8. the tetrasporangia occurring in slightly spiral series of up to 4-6-(10) successively, maturing sporangia spherical with two cover cells in a distal portion of the indeterminate lateral branches. This is the first time the species was recorded at the coast of the South China Sea. In order to observe the intimate internal structure of these filamentous thalli, a set of “dye-press” method to experimental materials was operated originally to be beneficial to the taxonomical research of those similar genera. The morphology and the tetrasporangial development of the species were observed in detail in this study. The results should enrich our knowledge of the morphology and geographical distribution of the species.

Physiological responses to high temperature stress of the thalli of Pyropia dentata, P. haitanensis and P. crispata, which were commonly distributed in South China, were studied by measuring the content of chlorophyll a, carotenoids, phycoerythrin and phycocyanin, the yield of photochemical efficiency, the capacity of total antioxidant, and the scavenging rate of diphenyl picrylhydrazyl (DPPH)radical. Results showed that the content of pigments declined due to high temperature stress, and the thalli became red, white and transparent gradually. Pyropia thallus’ photosynthetic efficiency (maximal photochemical quantum yield and actual photochemical quantum yield) decreased under high temperature stress, especially under 29℃ and 32℃. Being under high temperature stress for a long time (>3d) also resulted in decreases of total antioxidant capacity and DPPH radical scavenging rate. P. haitanensis and P. dentata began to die when they were stressed under 32℃ for three days, and P. crispata could not survive under 32℃ for six days. P. crispata had the strongest resistance to high temperature stress followed by P. dentata, while P. haitanensis was the most sensitive one. Thus, P. crispata and P. dentata had the potential and advantages in extension of cultivation in South China.

In order to elucidate background information on the genetic diversity and population history of Acanthopagrus schlegelii, the genetic diversity, population genetic structure and demographic history of Dongji stock, Aotou stock and Wanning stock of the black porgy were analyzed based on the control region fragment of mitochondrial DNA in this study. The results showed that the sequences of 88 individuals of the three stocks were 715~716 bp in length and that there were 59 haplotypes. The value of haplotype diversity ranged from 0.949 to 0.985 and the nucleotide diversity, from 0.0068 to 0.00901. These results indicated that the three wild stocks presented a high level of genetic diversity. Significant population differentiation was detected for the two populations of Dongji stock and Aotou stock, while there was no significant genetic differentiation between Dongji stock and Wanning stock as well as between Aotou stock and Wanning stock. In addition, no obvious lineages and geographic clusters were found in the neighbor-joining tree, which supported the notion that unique management unit (MU) was recognized on the basis of the southern populations. Both neutrality tests and mismatch distribution analysis suggested a late Pleistocene population expansion for the three stocks. The genetic diversity and population genetic structure revealed were attributed to the absence of geographic barrier, influence of sea currents and human activities.

Deep longline surveys were conducted in the South China Sea from June 2010 to February 2013. The composition, quantity and seasonal variation of fish species were reported using hooking rate and catch per unit effort as index. A total of 33 species were identified, of which six species including Thunnus obesus, Lampris guttatus, Alepisaurus ferox, Scoliodon Palasorrah, Taractichthys steindachneri, and Xiphias gladius were the most abundant ones taking 75.56% of the total weight, and of which five species such as Alepisaurus ferox, Gempylus serpens, Taractichthys steindachneri, Dasyatis atratus, and Thunnus obesus were the most abundant ones taking 82.59% of the total number. The species compositions of the catches did not change with season, but more Thunnus alalunga, Xiphias gladius and Lepidocybium flavobrunneum were caught in winter. The average hooking rate was higher in central western Nansha waters than in other sea areas in all four seasons. The average CPUE was higher in central western Nansha waters in spring and summer, in western Xisha waters in fall and in southeastern waters off Hainan Island in winter. Fish species could be classified into shallow-water group and deep-water group according to catching depth, and 87.33% of the catches came from 80 to 280 m water depths. There are two reasons for low hooking rate with comparison to previous surveys and productions. One is that survey area coverage was not large enough to make us find better fishing ground; the other is that we could not adjust fishing gear and method effectively without knowledge of fish behavior in deep South China Sea . We suggest paying more attention to fishing ground and fishing technology in future surveys.

An application of remote sensing in monitoring and management of coral was developed with reflectance identification of coral substrate. Some foreign scholars have discriminated reflectance of coral substrate, while the reflectance of different coral substrate discrimination in the South China Sea did not exist. This study explored reflectance of Acropora hyacinthus at Luhuitou Sanya using spectrum instrument. Healthy Acropora hyacinthus exhibited positive reflectance features at 570, 600 and 650 nm. Reflectance by dead Acropora hyacinthus was obviously higher than that by healthy Acropora hyacinthus, and did not jave positive reflectance features. The differential analysis of coral substrate reflectance use PRIMER6 software packages Clustering. Healthy Acropora hyacinthus reflectance, dead Acropora hyacinthus reflectance and sand reflectance can be distinguished at the level of 80% Bray-Curits similarity. Based on reflectance derivative analysis, the first derivative of reflectance between 490 and 560 nm provided good identification of healthy and dead Acropora hyacinthus.

A total of 95% ethanol extract from the fruits of Sonneratia apetala Buch. Ham was isolated by a variety of chromatographic methods, and the structures of the isolated compounds (1~16a/16b) were elucidated by a series of spectroscopic techniques. These structures were identified, including one phytosterols, β-sitosterol (1); one triterpenoid, (betulinic acid, 2); eight phenolic acids, cis-hinkiresinol (3), 4°-O-methyl-cis-hinokiresinol (4), vanillic acid (5), methyl gallate (6), 3-O-methyl gallic acid (7), syringaldehyde (8), syringic acid (9), methylparaben (10); and nine malate compounds, 4-ethoxy-3-hydroxy-4-oxobutanoic acid (11), dimethyl malate (12), ethylmethyl malate (13a/13b), butylethyl malate (14a/14b), bibutyl malate (15), butylmethyl malate (16a/16b). The compounds 14a/14b were new; compound 11 was a new natural product; the compounds 3~16a/16b were obtained from S. Apetala for the first time; and the compounds 3, 5~16a/16b were obtained from genus Sonneratia for the first time.

The full-length cDNA sequence of copper-zinc superoxide dismutase (CuZnSOD) gene was obtained from Galaxea astreata using RT-PCR and RACE methods. The results revealed that the full-length cDNA of CuZnSOD gene was 730 bp including 111 bp 5°-UTR, 188 bp 3°-UTR and 471 bp open reading frame (ORF) encoding 156 amino acids. The deduced amino acid sequence contained two CuZnSOD protein family signals. Cu²⁺ integrated with His49, His51, His66, and His123, and Zn²⁺ integrated with His66, His74, His83, and Asp86. The only intrachain disulfide bond was formed between Cys60 and Cys149. The signal peptides were not predicted by SignalP 3.0 Server, the transmembrane domains were not predicted by TMHMM Server v. 2.0, and the possibility of 56.5% was located in the cytoplasm by means of PSORT II Prediction, indicating that the deduced protein was intracellular CuZnSOD. The results will help to further reveal antioxidant molecular mechanism in Sceratinian corals.

Based on a BP neural network (NN) model, we investigated the possibility to derive the tide level at one site using the tide observation at a nearby site. As an example, the application of the neural network model to predict the tide level at Station Sanya using the observed data at Station Xisha is presented. The observed tide level at different hours ahead of the prediction time (t-N+1, …, t-1, t) are used as the input vector. Combinations of different numbers of input-layer nodes (2 to 10) and hidden-layer nodes (3, 4, 5, 10, 15) are used, and the outputs are compared with field data. For the specific case used in this study, four nodes in the hidden layer lead to the best prediction while 15 nodes performs the worst; two nodes in the input vector are the most suitable while more input nodes lead to degraded performance. The model setup with a hidden layer of four nodes and an input vector of two variables (t-1, t) has the best prediction accuracy in this case, with a correlation coefficient of 0.9901, a root-mean-square (RMS) error of 0.06 m, and a prediction error of -0.16~0.15 m (between prediction and observation). The proposed NN model is examined for its applicable to predict tides at a station using the observed tide data of a nearby station if they are physically coherent with similar tidal type.

Typhoon Haikui (1211) was the first typhoon that made landfall in Zhejiang province since 2009, which was also the strongest landfall typhoon in China in 2012. After touch-down in the Xiangshan coast, Typhoon Haikui moved to the northwest slowly, and crossed the Xiangshan Harbor. There was a marine monitoring buoy in the Xiangshan Harbor. Using the data of meteorological and water quality parameters collected by the marine monitoring buoy, we analyzed the reliability of the marine monitoring buoy in the Xiangshan Harbor during Typhoon Haikui. The results showed that during the influence of Typhoon Haikui, the water temperature dropped due to a near-inertial oscillation, which generated by the wind stress in the Xiangshan Harbor. The air temperature, pH and dissolved oxygen content collected by the marine monitoring buoy showed little change. The air pressure continued to decline until two hours after the landfall. Wind and rainfall fluctuated. Due to the heavy rainfall brought by Typhoon Haikui, the amount of water, water depth and water turbidity increased due to runoff; the water temperature dropped; and the salinity decreased. Typhoon Haikui weakened slowly after the landfall, and one of the main reasons for the weakening was the terrains in Jiangsu, Zhejiang and Anhui provinces. The near-inertial oscillation with a shorter duration was not sufficient to cause a large position change of the marine monitoring buoy．During the typhoon event, the buoy basically remained in its position. The marine monitoring buoy whose ability to resist typhoon met the design requirements functioned as a relatively stable real-time monitoring system.

Based on seven stations’ monthly precipitation data in Yunnan and the NCEP/NCAR monthly atmospheric circulation data, as well as ERSST V3b monthly sea surface temperature (SST) data, the Indian-Pacific SST mode that impacts Yunnan precipitation during rainy season was investigated using composite and correlation analysis. Of El Niño-Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) mode, which plays a more important role on Yunnan precipitation in rainy season? Finally, the physical mechanism through which Indian-Pacific SST mode impacts Yunnan precipitation in rainy season was discussed. The results are as follows. Both ENSO and IOD have influences on Yunnan precipitation in rainy season, but the IOD plays a more important role. When the western India Ocean’s SST is warmer (positive IOD), the easterly wind appears in the tropical Indian Ocean and a cyclonic anomalous circulation is in the western Indian Ocean. The warm and moist airflow in the western Indian Ocean enters the Mainland China along the west side of the Tibet Plateau, then goes around the Tibet Plateau and from the north to the south, and finally enters the Bay of Bengal, which limits the development of the trough over the Bay of Bengal. So, the water vapor transportation to Yunnan is less. Yunnan is in the water vapor flux divergence area and has less precipitation. When the tropical Indian Ocean has lower SST (negative IOD), no easterly wind is in the tropical Indian Ocean, the trough over the Bay of Bengal is strong, and the water vapor transportation to Yunnan is more; Yunnan is in the water vapor flux convergence area and has more precipitation.

Since the start of operation of Daya Bay Nuclear Power Plant, a distinct temperature increase has happened in the surrounding waters, resulting in changes of phytoplankton community structure. To evaluate the warming effects on the phytoplankton community structure and photosynthetic efficiency, warming-up and recovery experiments were conducted on different granulometric classes (micro-, nano-, pico-) from the waters infall and outfall of the plant in the summer of 2013. The results are as follows. In the warming-up experiments, the dominant community changed from the diatom on the early stage to the cyanobacteria (Nostoc sp. and microcystis sp.) on the later stage in all of the three groups (35℃, 33℃ and 29℃). In the high-temperature incubation groups (35℃ and 33℃), the phytoplankton biomass increased continuously while the maximum quantum yield maintained almost at the normal state on the first two days. Then, both parameters began to decline, and the effects of 35℃ were stronger than those of 33℃. Photosynthetic efficiency of micro- and nano-phytoplankton was stronger than that of pico-phytoplankton in both groups of 35℃ and 33℃. However, the biomass and photosynthetic efficiency showed no significant differences among different granulometric classes in the control group (29℃). In the recovery experiments, photosynthetic efficiency of the micro- and nano-phytoplankton recovered quickly at normal (29℃) or lower (25℃) temperatures after experiencing the temperature stress from thermal discharge, while that of the pico-phytoplankton was relatively weak. In summary, the high temperature stress happened to phytoplankton at 35℃ and 33℃, and the threatening effects of 35℃ were more seriously. Both micro- and nano-phytoplankton showed greater capacity than pico-phytoplankton in terms of tolerance to high temperature and recovery. Our results suggested that the short-term stimulus of high temperature could promote rapid growth of phytoplankton from the outfall of the Daya Bay Nuclear Power Plant, and photosynthetic damage could be recovered after phytoplankton being carried away from the high temperature region.

Stable isotope analysis has emerged as one of the primary means to analyze the structure of food webs. Size fractionated zooplankton biomass and stable isotopes in the southern South China Sea during spring and summer 2013 were investigated. The results showed that zooplankton biomass in spring was higher than those in summer at most sites (p<0.05), while the maximal value was found in the southwestern continental shelf (influenced by coastal upwelling) with increased mean value of zooplankton biomass during summer. Zooplankton was divided into three groups according to size. Macro- zooplankton contributed more to the total zooplankton biomass during summer, while meso- and micro-zooplankton contributed more during spring. Mean δ¹⁵N value in spring was higher than that in summer, and the δ¹⁵N value of macro-zooplankton was higher than those of meso- and micro-zooplankton at most sites. Zooplankton biomass was negatively related to mixed layer depth and seawater temperature at 75-m depth, and positively related to salinity at 75 m, indicating that zooplankton biomass was influenced by vertical mixing. The result of GAM (generalized additive model) indicated that the δ¹⁵N value of micro-zooplankton was affected by combined impacts by environmental and biological factors.

The research on coexistence between marine gas hydrates and deepwater petroleum systems has great significance to exploration and exploitation of both deepwater hydrocarbon reservoirs and shallow gas hydrates, to the inducement of submarine slide and to the development of new insights on global climate change and earth’s carbon cycle. The new advances in leaking, capping and capping side-accumulation coexistence relationship are systematically summarized. According to the investigation, for the most part, the contributions of deep-seated oil and gas to shallow gas hydrate field have likely been underappreciated. The restricted discrimination among different sources of carbon trapped within gas hydrate confines the recognition of leaking coexistence between deepwater petroleum systems and shallow gas hydrates. Significant attention has been paid to the hydrocarbon supply from deflected hydrocarbon migration by low-permeability hydrate-bearing sediments and gas hydrates dissociation during geological history to conventional petroleum accumulations. Except for very few geological provinces, the resource potential of free gas trapped beneath gas hydrate is not significant. In most cases, gas hydrate-bearing sediments are not a high quality seal, unless structural, stratigraphic, lithologic, or/and permafrost traps have been involved, forming a relatively effective trap for upward hydrocarbon flow. We suggest as additional research on how to assess hydrate-bound gas sources from sub-biogenetic gas and secondary biogenic gas produced by anaerobic biodegradation of crude oil and thermogenic gas, and to illuminate the low trapping capacity of gas hydrate-bearing sediments by mathematic model.

The distribution and δ¹³C composition of long chain n-alcohols from the late Last Glacial Maximum (LGM) to the Holocene in Site 4B core sediments from the continental slope of the northern South China Sea was discussed in this paper. The distribution of carbon preference index (CPI, 10.49~24.56), average chain length (ACL, 28.91~29.99) and average carbon isotope (-28.85‰±0.97‰ to -32.92‰±1.38‰) of long chain n-alcohols reflected a C₃ higher plant source and a dominated terrigenous input of organic materials into the sediments. The relatively low terrigenous input was related to the extensive melt water pulse (MWP) events (19ka-MWP, MWP-1A and MWP-1B), and Bølling-Allerød (B/A) warming event from the end of the LGM to the end of the Late Pleistocene in Site 4B sediments (65~102cm, 19.343 to ~ 11.636 ka BP) without glacial period/interglacial period cycle. However, the distribution of the terrigenous input reflected intensified/weakened winter monsoon/summer monsoon cycle during the late LGM and Holocene, with the winter monsoon maximum periods recorded during the late LGM and the summer monsoon maximum periods in about 9.940ka BP. Compared with the cycle climate change of global glacial period/interglacial period, the distribution of the terrigenous input from the end of the LGM to the end of the Late Pleistocene in Site 4B sediments (19.343 to ~ 11.636 ka BP) reflected ambiguous regional comparability, probably related to the regional environmental activity in low latitudes.

An ocean bottom seismometer (OBS) was placed on the seafloor by free fall from the sea surface. Due to the impact of current and bottom topography, the actual position of OBS is usually deviated from the designated position. OBS relocation is the key part of OBS data processing, since the inaccurate position will introduce errors to the geometry and to the following processing. The direct water wave contains the information of OBS position, and the OBS position is inverted from the travel time of direct water wave by the least-square method. The accuracy of shot position, the delay of shot time, the distribution of shots, OBS time drift, errors in picking of first break and the sea water velocity all have impacts on the accuracy of OBS relocation. In this paper, we show the impacts of these factors on OBS relocation, and use some actual OBS in the Dongsha sea area as an example. Numerical results show that to invert the OBS position accurately, the shots should be distributed along a non-straight line. When the offset is less than 10 km, the influence of sea water velocity structure can be ignored. The most influential factor comes from the right-hand error consisting the delay of shot time, OBS drift and picking error. And 5 ms error may lead to 40 m digression. The numerical result agrees with the actual OBS data.

At present, theoretical calculation and model test about resistance and space state basically focus on a single underwater towed body, while the comprehensive resistance and stance of towed objects of multi-streamer seismic survey vessels are less concerned. For the convenience of the operators to predict the state of towed bodies in the sea quickly, the structure of multi-streamer seismic survey vessels for towed objects and the character of fluid resistance are analyzed on the basis of existing research on the fluid resistance of underwater towed objects. A simplified way to calculate the resistance and to estimate the horizontal stance is presented. This paper takes the configuration of common towed objects as an example, and the difference between estimation result and actual working status is within the permitted scope. The effectiveness of the proposed method is confirmed.

In order to study the deep tectonic characteristics along the line of Bohai Sea-Shandong Peninsula-South Yellow Sea, using marine air gun source and land explosive source detection, the Bohai Sea-Shandong Peninsula-South Yellow Sea onshore-offshore joint deep seismic survey profile was carried out in 2013. The onshore-offshore deep seismic profile comprises two ocean bottom seismometer (OBS) seismic lines in the Bohai Sea and the South Yellow Sea and one onshore seismic line. This is the first OBS seismic line in the South Yellow Sea. After data preprocessing of South Yellow Sea OBS, including data decoding and data cutting, etc., the results show that the OBS recording quality is good. We can not only identify the seismic phases such as Ps, Pg and PmP but also observe the P-wave seismic phases from the Qianliyan uplift zone for the first time, which means the data processing is feasible. Combined with geological and geophysical data, a preliminary analysis of the phase character in different structural units of the South Yellow Sea was carried out, laying a good foundation for future simulation and interpretation of crust velocity structure.

Recent studies have shown that temperature plays an important role in the process of accumulation and distribution of natural gas hydrate. Some natural gas hydrate resources in sea area coexist with geothermal resources, and distribution patterns exist. This paper puts forward the viewpoint of combined use of these two kinds of resources on the base of exploitation of natural gas hydrate by using geothermal energy. It proposes related research methods about combination evaluation of natural gas hydrate and geothermal resources. In this study, we also build the model of combination evaluation and put it into practice. Examples of applications enrich the feasibility study of exploiting methods as well as making the evaluation of the prospective areas of two resources’ complex utilization.

Using the global monthly mean datasets from the Coupled Model Intercomparison Project Phase 5 (CMIP5), the characteristics of non-uniform sea surface temperature warming over the tropical Pacific, Indian and Atlantic oceans and its causes are analyzed. We use various meteorological statistical methods, such as synthetic analysis and correlation analysis. Multi-model results show that annual mean spatial distributions of the variation in SST exhibit non-uniform patterns over the three tropical oceans under global warming. However, the causes responsible for these non-uniform patterns are quite different. The oceanic dynamic processes play a leading role in the equator and over the area north of the equator in the tropical Pacific Ocean, while the atmospheric thermal effect becomes more important over the area south of the equator. In addition, the oceanic upwelling/downwelling processes play different roles in the eastern and western tropical Pacific. For most part of the tropical Indian Ocean, variation in sea surface temperature is not well explained by the air-sea heat fluxes and oceanic dynamics such as upwelling/downwelling, and temperature advection also plays an important role. For the tropical Atlantic Ocean, the SST variability in the area near the equator mainly results from oceanic dynamics such as temperature advection and upwelling/downwelling. Temperature advection plays a leading role in the variation of sea surface temperature north of the equator, while upwelling/downwelling plays a dominant role south of the equator.

In this study, we explore the upper-ocean responses to Typhoon Tembin in 2012 with three drifting buoys’ data, high-resolution global temperature and salinity profile data, and satellite data. Results show that in the 50 km from the typhoon’s center, there was a near-surface flow velocity of 2.3 m•s^-1. In other similar typhoon cases, however, flow velocity was often less than 1 m•s^-1, much weaker than Typhoon Tembin. The reason is the drifting buoy in the frontal area of the intersection of cold and warm water masses encountered large variability of flow. So, the average flow velocity was small in other similar typhoon cases. There was strong vertical mixing, making temperature decreased and salinity increased at both left track and right track 1~2 days after the super strong typhoon passed by, and at the right track 5~6 days after the strong typhoon passed by. There was obvious upwelling below the mixed layer.

In regions of internal waves, topography is commonly an important factor for internal waves’ generation, propagation and evolution. Based on incompressible primitive Navier-Stokes equations, a non-hydrostatic oceanic hydrodynamics model is employed to study internal solitary waves (ISWs). Generation and evolution processes of nonlinear internal waves are simulated in the numerical model forced by barotropic tide. Using the simulation results, topological structure changes of single-ridge terrain on the generation and propagation of solitary waves are presented. According to the simulations of various topographic depths and extended parameters, analysis is done in terms of arrival time and intensity of ISWs. Following that, an “L-depression” structure would appear on the opposite side of the ridge before ISW generation is proposed, and a -“accumulation” and “releasing” mechanism on energy with the “L-depression” structure is also indicated.

Using NOAA OISST V2.0 reanalysis data, we studied the interannual variability of tropical instability waves (TIWs). Results show that: TIWs usually appear during May and July and are absent in December or next January. A negative relationship is identified between the year-to-year variations of TIWs activity and that of ENSO intensity, with stronger TIWs activity in La Nina years and weaker TIWs activity in El Niño years. The negative relationship is more evident in the active period of TIWs during June and December, and the biggest correlation coefficient is in December. Applying lead/lag correlation analysis on TIWs index and NINO 3.4 SSTA, the results suggest that the maximum correlation coefficient appears when TIWs index leads the ENSO index by 2~3 months, which indicate that the TIWs may modulate the cycle of the ENSO.

Tropical disturbances are part of the important weather systems in the tropical regions and have the potential to develop into tropical cyclones. In this study, the characteristics of developing and non-developing tropical disturbances over the South China Sea (SCS) were compared using satellite observations and reanalysis datasets. The results revealed that developing and non-developing tropical disturbances have significant regional and seasonal characteristics. The developing tropical disturbances have slower moving speeds and persist for a longer lifetime, compared with the non-developing tropical disturbances over the SCS. By investigating the meteorological variables for tropical disturbances over the SCS, five key environmental factors that could determine a tropical disturbance to develop or not are found, including the 850-hPa relative vorticity, vertical wind shear, the temperature difference between 850 and 500 hPa, the outgoing long wave radiation (OLR), and the mid-level atmospheric relative humidity. A forecasting equation has been developed based on these key meteorological factors to predict whether a tropical disturbance over the SCS will develop or not. These results can help us to better predict tropical disturbance development and tropical cyclone formation over the SCS.

Organic reef, widely developed since the Miocene around the Xisha Islands, provides rich information of tectonic movement and activity. Using single-channel seismic profiles acquired and combining with other research in this area, this paper discusses the tectonic movement and activity around the Xisha Islands. The results show that there are NE-NEE and NW trending faults along the Xisha block boundary and NE and EW trending faults in the Xisha block. These faults are inherited from old ones, and the reactivation of the faults accompanied by volcanicity is affected by multiphase tectonic movements. Result from the NW direction stress caused by the opening of the Southwest Sub-basin, the Zhong-Xisha block is in a compression environment. The seismic profile shows that there is a distinct difference between the two sides of the EW fault in terms of formation, which indicates that the two sides of the formation are in different tectonic environments. After the Pleistocene, volcanic and most of faulting activity stopped, and the Xisha Islands behave as a stable tectonic entity.

Gas hydrate has attracted great interest from the scientists for the impact of its fossil fuel resource potential, the extent of submarine geohazard and global climate change. Thickness of a hydrate-bearing layer is an important parameter in resource evaluation. Quantitative identification of potential gas hydrate accumulation needs to pay urgent attention to the technology in pre-drilling assessment. Thickness of a hydrate occurrence can be identified by the time-frequency analysis method. The result suggests that the time-frequency analysis method, guiding by the logging data, may be an effective tool to identify thick hydrate-bearing layers. A hydrate-bearing layer tends to appear as a low-frequency low intensity zone, underlying a low-frequency high intensity and high-frequency low intensity zone.

Based on elongata poatholefish Gonostoma elongatum samples collected by middle water trawl in the central- southern part of the South China Sea during 2013 and 2014, body length and body weight composition, age and growth, gonad maturity composition, feeding stage of G. elongatum were studied. The results are as flows. At 150 m depth, the range of body length is 80~128 mm, and the dominant size is 80~100 mm that is 84.2% of the total. At 200 m water layer, the range of body length is 43~195 mm, and the dominant size is 80~140 mm that is 76.9% of the total. At 400 m water layer, the range of body length is 86~186 mm, and the dominant size is not obvious. The mean size of G. elongatum has an increasing tendency from shallow to deep water, first increasing and then decreasing tendency from south to north. T-test indicates that the body length distribution at 150, 200 and 400 m presented significant differences (p<0.01). In spring, the mean body length and mean weight were 111 mm and 3.84 g, respectively. In autumn, the mean body length and mean weight were 140 mm and 5.50 g, respectively. In winter, the mean body length and mean weight were 134 mm and 7.44 g, respectively. The growing parameter, b value, is 3.0726, which indicates isometric growth in G. elongatum. A total of 45 statoliths of G. elongatum were identified, including 35 individual of one year old and 10 individual 1⁺ years old. The minimum age was six months old with mean body length of 128 mm; the maximum age was 16 months old with body length of 187 mm. The mean body length and mean body weight of fish of one year old were 138 mm and 5.12 g, respectively. The mean body length and mean body weight of fish of 1⁺ year old were 157 mm and 7.53 g, respectively. The gonad maturity of G. elongatum is mainly at stagesⅠand Ⅱ, and the highest stage appears in spring. The feeding stage of G. elongatum is mainly at stages 0 and 1, and the highest feeding stage is 3. On the whole, the feeding stage of G. elongatum is not much different at these depths.

Ultrastructure changes of oocytes during oogenesis and vitellogenesis in sea cucumber Holothuria scabra were studied by scanning electronic microscopy (SEM) and transmission electronic microscopy (TEM). The results show that oocyte of H. Scabra belongs to isolecithal egg and its oogenesis includes following three stages: oogonium, pre-vitellogenic oocyte and vitellogenic oocyte, and that the stage of vitellogenic oocyte includes early vitellogenic oocyte, mid vitellogenic oocyte and late vitellogenic oocyte. Besides a large and oval nucleus, oogonium contains fewer mitochondrias in this stage. The nuclear of pre-vitellogenic oocyte contains a vacuolated nucleoli, also known as a germinal vesicle. At the early stage of vitellogenesis, various well-developed organelles emerge in cytoplasm. At the stage of mid vitellogenic oocyte, active endogenous yolk formation greatly occurs and many kinds of organelles directly participate in this process. At the stage of late vitellogenic oocyte, the oocytes are the biggest and contain fewer numbers of organelles, and the germinal vesicle of eccentric position is near the basal protuberance. Golgi apparatus, mitochondrias and ribsome are the dominant organelles, which take part in the formation of endogenous yolk, while active microphagocytosis of plasma membrane play the main role in forming exogenous yolk.

This study analyzes the heavy metals in the sediments, including Zn, Pb, Cu, Cr, and sediment grain size. It evaluates the degree of pollution and ecological risks of the four heavy metals in the Pearl River Delta and the Beibu Gulf using sediment accumulation coefficient method and HÀKANSON L potential ecological hazard index method. We compare the results between the Pearl River Delta and the Beibu Gulf. The comparison shows that the clay and silt enrichment of heavy metals in sediment is large; Cu in the two regions reached the serious level of pollution, Zn, Pb and Cr reached the middle level of pollution in the Pearl River estuary and in part of the Beibu Gulf. The potential ecological risks in the Pearl River estuary range from lower to higher level, and those in the Beibu Gulf are lower. The Pearl River estuary has been severely damaged due to human activities, and the Beibu Gulf, as a national development site, should receive priority to prevent pollutions, and adapt policies to develop and protect the natural environment.

Four kinds of climatological monthly wind stresses, including SCOW (Scatterometer Climatology of Ocean Winds), CFSR (NCEP Climate Forecast System Reanalysis), ERA-Interim (the Interim ECMWF Re-Analysis), and NCEP [the National Centers for Environmental Prediction (NCEP)/National Center for Atmospheric Research (NCAR) Reanalysis 1] were used to force the South China Sea (SCS) circulation using the Regional Ocean Modeling System (ROMS). The differences among the simulated upper circulation in the SCS from the four experiments and their dynamical relationships with the differences of these wind stresses were explored. Significant differences exist in wind stress and its curl in terms of patterns, and these differences are reflected in the upper-ocean model responses. The results show that seasonal variation of the basin-scale circulation in the SCS can be well represented in all the experiments. The major differences are in sub-basin or mesoscale circulations. It is the significant local positive wind stress curl that leads to the generation of the Luzon cold eddy in winter. The dipole structure of the upper circulation off the Vietnam coast can be clearly seen in all four experiments in summer; but the strength of the dipole varies with the forcing and is related to the local wind stress curl dipole. Moreover, it is shown that the Luzon Strait transports are consistent in the experiments, which indicates that there is little impact from the differences of local wind stresses on the Luzon Strait transport. But the simulated Taiwan Strait transports differ great in both autumn and winter. Strong northeasterly wind impedes the water transport from south to north. Further analysis shows that large northward seawater transport through the Taiwan Strait in winter is in favor of the existence of the SCS warm current (SCSWC) in the northern SCS in the model results. Overall, this study helps us to more deeply understand the responses of upper-ocean circulation in the SCS to atmospheric wind forcing. At the same time, it provides some references to the choice of wind field in simulating the SCS circulation.

Based on the NOAA (National Oceanic and Atmospheric Administration, NOAA) monthly global Extended Reconstruction sea surface temperature (ERSST V3) data and using the Rotated Empirical Orthogonal Function (REOF) method, the spatiotemporal variability of the dominant modes of the global sea surface temperature anomalies (SSTA) from 1900 to 2009 is studied. The results show that the first mode of global SSTA with significant interannual variability represents the variability of El Niño and Southern Oscillation (ENSO) and the relationship between ENSO and the global SSTA. The second and fifth modes show pronounced interdecadal variability in the North Pacific. The second mode may have a close spatial relationship with both the Pacific Decadal Oscillation (PDO) and the Pacific Interdecadal Pathway (PIP), while the fifth mode may have a close temporal relationship with the PDO. The third and sixth modes represent multidecadal fluctuations in the North Atlantic; the former may have a close relationship with the Atlantic Multidecadal Oscillation (AMO) that is connected to the tripolar SSTA pattern of the North Atlantic, and the latter is associated with the uniform SSTA pattern of the North Atlantic. The fourth mode represents interdecadal variability with a large response in the South Pacific, poleward of 30°S, and this mode seems to have no relationship with the PDO.

Typhoon Haiyan was a supertyphoon rarely seen in history. Based on HYCOM and remote-sensing data, we investigated the role of barrier layer in the developing phase of typhoon Haiyan evolution. Typhoon Haiyan moved westward over the warm water with a thick barrier layer underneath after it was generated in the eastern part of the Northwest Pacific warm pool. It became a tropical depression on November 3 and developed into a supertyphoon on November 5, 2013. Due to the warm water in barrier layer, the barrier layer reduced vertical mixing and entrainment caused by Typhoon Haiyan, preventing the cold thermocline water from entering the mixed layer. As a result, self-induced sea surface temperature cooling associated with Typhoon Haiyan was suppressed. Further, high sea surface temperature continued to provide heat to Typhoon Haiyan in the form of latent heat flux releasing, which favored quick intensification of typhoon. As Typhoon Haiyan passed by, large amount of precipitation resulted in the shoaling of mixed layer, which favored a new barrier layer to form along its path.

According to the applicability conditions for three types of internal solitary wave theories including Korteweg-de Vries, extended KdV and Miyata-Choi-Camassa, the double push-pedals wave-generating method, the velocity-inlet wave-generating method and the mass source wave-generating method were developed y in a two-layer fluid of finite depth. Series of numerical simulations were presented to compare the results and efficiency of the three wave-generating methods. Results showed that even though all three methods can generate internal solitary waves, the velocity-inlet method and the mass source method were better than the double push-pedals method in terms of numerical simulations. The efficiency of simulation was the highest for the velocity-inlet method, followed by the mass source method, and the lowest for the double push-pedals method.

In this study, a support vector machine (SVM) model was introduced to retrieve phytoplankton size classes (PSCs), from phytoplankton absorption spectra and total chlorophyll-a concentration.The performance of this model was validated with the South China Sea andNASA bio-Optical Marine Algorithm Dataset(NOMAD) datasets. The results of the model, which used phytoplankton absorption spectra as the only input parameter, showed that the absolute percentage differences (APD) were 46.1% (pico), 61.6% (nano) and 36.3% (micro) for the South China Sea dataset, and were 36.3% (pico), 44.6% (nano) ,44.3% (micro) for NOMAD dataset; It also showed that the determination coefficents (R²) were 0.604 (pico), 0.423 (nano) and 0.491 (micro) for the South China Sea dataset, and were 0.460 (pico), 0.702 (nano) and 0.829 (micro) for the NOMAD dataset. The SVM model that used both absorption spectra and chlorophyll-a concentration of phytoplankton showed that the APD were 19.2%, 31.9%, 31.6% and determination coefficents of phytoplankton size classes (pico, nano, and micro) were 0.837, 0.805, 0.600 for the South China Sea data-set. Using the same method, the result of SVM model showed that the APD were 35.3%, 35.4%, 38.2% and determination coefficents of phytoplankton size classes (pico, nano, and micro) were 0.713, 0.758, 0.810 for the NOMAD data set. The SVM model trained using phytoplankton absorption spectra and total chlorophyll-a concentration performed more effectively than that using only phytoplankton absorption spectra. The performance of the SVM model was shown to be satisfactory, and the model opens the way to an appliaction to estimate PSCs by using hyperspectral measurements.

To detect and recognize passive fish acoustic signals from noisy marine environment, sparse decomposition is used to realize the endpoint detection by coherent ratio feature. This algorithm extracts feature of fish and wave acoustic as test object under different signal-to-noise (SNR) ratios in the training; feature from noisy signal segment is extracted in the testing to classify test object; finally, it is realized by threshold endpoint detection method. Experimental results show that the algorithm in low SNR can accurately realize effective signal segments, compared with the power spectrum feature extraction algorithm.

Reliability of ocean bottom seismometer (OBS) data depends on the performance of OBS, but there is no OBS performance detection equipment in China currently. The OBS controllable audio test instrument refer to the performance testing system for towing seismic acquisition system, and uses pulse signal and fixed frequency audio signal as the source signal. OBS performance is tested in terms of performance index before sailing. These indexes include the waveform consistency, time consistency, frequency deviation, spectral analysis, signal-to-noise ratio, gain analysis and pulse spectral analysis. The OBS controllable audio test instrument can determine the reliability of OBS, ensure the high quality of data collected by OBS, and provides technical support for field operation.