The family Samaridae in Pleuronectiformes consists of three genera, namely, Plagiopsetta, Samariscus and Samaris. Studies on mitochondrial genomes of Samaris cristatus and Samariscus latus showed that there exist differences in genomic rearrangement and gene number between this two species. To determine whether there are structural differences in the species of the genus Plagiopsetta, Plagiopsetta glossa were used as the representative species for this study, and the mitochondrial genomic characteristics of this species were compared with those of Samariscus and Samaris. The length of its mitogenome is 18,723 bp, and contains 39 genes, including 13 protein-coding genes, two rRNA genes, 24 tRNA genes, two control regions, one light strand replication origin, and 13 more interspaces. Compared with the typical mitogenome in teleosts, P. glossa and S. latus have two more genes of tRNA-Cys and tRNA-Tyr (S. cristatus only one more tRNA-Cys). Additionally, each of the three flatfish has an extra control region, but the gene orders of P. glossa and S. latus mitogenomes are the same. Six genes (tRNA-Cys₁, tRNA-Tyr₁, tRNA-Ser1, tRNA-Lys, tRNA-Arg, and tRNA-Ser2) from different locations are clustered together forming a gene cluster, and following by this genes cluster was ND5-ND6-Glu-Cytb-Thr, all those 11 genes have no gene order change in terms of typical mitogenome.

The model of Double Replications and Random Loss was used to analyze the possible rearrangement mechanism in P. glossa mitogenome. The characteristics of gene number, gene order and 13 more interspaces provided new evidence to support the applicability of this model. The results of this study not only enrich our scientific knowledge of mitogenomic features, but also provide more data for further study on mitochondrial evolution and phylogenetic analysis for flatfish.

To declare intraspecies diversity of Pseudo-nitzschia pungens Hasle, a total of 32 monoclonal strains of P. pungens from Chinese coastal waters were isolated and established. These strains were identified carefully, based on the morphology under both light microscopy and transmission electron microscopy, and on the molecular analysis inferred from the internal transcribed spacer region sequences. Two varieties were identified: P. pungens var. pungens (Grunow) Hasle and P. pungens var. averiensis Lundholm, Churro, Carreira, and Calado. Their morphologies were described and compared with allied taxa. Meanwhile, domoic acid (DA) was detected using a liquid chromatography tandem mass spectrometry (LC-MS/MS) injection, but no detectable DA was found. The results may provide detailed information for further studies of toxin production of Chinese Pseudo-nitzschia strains.

The organizational structural characteristics of digestive system of fish are closely related to diet. To study the digestive physiological characteristics of reef fish Girella leonine, the organizational structural characteristics of digestive system were investigated by H.E staining. The correlation between the structural characteristics of tissue and the adaptability of diet and environment was discussed. The results are summarized as follows. 1) The esophagus tended to the cavity to form six thick folds, which had obvious striated muscle and mucous cells, and the folds had strongly expansion ability. Mucous cells were distributed between mucosa epithelium and were cone-shaped. 2) “V-shaped” stomach was divided into cardia, gastric body and pylorus. The transverse section of gastric gland was round and the lumen was surrounded by several gland cells. The muscular layer of the stomach was well developed, its inner was annulus structure and the outer was longitudinal structure. The stomach glands were mostly developed in the lamina of gastric body, the gastric mucosa formed many folds and the pyloric stomach had multi-level branch folds. 3) There are more than 150 branched diverticulum in the pyloric, and they can be divided into two branches. The cavity of the cecum was filled with mucosal folds. The epithelium of mucosa was composed of single columnar epithelial cells without goblet cells. 4) Liver was divided into two leaves, which showed a general structure of bony fish in histology. The liver cells were large and polygonal, with a size of nearly 30 μm. 5) The intestine had four convolutions, and the ratio of intestine length to body length was 1.52±0.06, the value was between herbivorous and carnivorous fish. There were lots of goblet cells distributing in the whole intestine. The intestine had well-developed villi of small intestine. The epithelium of the villus base caved into the lamina propria to form the intestinal gland. The gland opened to the adjacent villi base. As the main digestible site, the number and height of the villi were greater than those in the hindgut. In this study, we also discussed the relationship between the histology characteristic and the digestion and absorption of digestive system of Girella leonine. Results showed that the characteristics of digestive system of Girella leonina was typical of omnivorous fish digestive system.

Estuaries are important land-sea interaction zones with unique biogeochemical processes and are important places to study the carbon cycle. Little is known on bacterial regulation in carbon cycling in the Pearl River Estuary. To examine the relative contribution of different groups of heterotrophic bacteria (particle-attached bacteria vs free-living bacteria, and high nucleic acid bacteria vs low nucleic acid bacteria), spatial and temporal variation in heterotrophic bacterial abundance was investigated during three contrasting periods (May 2015, August 2015 and January 2016) in the Pearl River Estuary. The total bacterial abundance was the highest in spring (an average of 2.94±1.30×10⁹ cells •L^-1 at the surface and 2.81±1.50×10⁹ cells •L^-1 at the bottom), moderate in summer (2.32±0.43×10⁹ cells •L^-1 at the surface and 1.85±0.50×10⁹ cells •L^-1 at the bottom), and the lowest in winter (1.06±0.33×10⁹ cells •L^-1 at the surface and 9.76±3.44×10⁸ cells •L^-1 at the bottom). Bacterial abundance at the surface was slightly higher than that at the bottom. Bacterial abundance decreased spatially from the upstream to the downstream of the estuary, suggesting that sewage input contributed to high bacterial abundance in the upstream, and that the downstream decrease resulted from the mixing of river discharge and seawater. The peaks of bacterial abundance and Chl a were observed at the frontal zone in the wet season, since a front increased the residence time of nutrients and plankton, and favored plankton growth. According to the spatial variation trend of bacterial abundance, it could be inferred that the heterotrophic bacteria of the estuary mainly came from upstream inputs. Heterotrophic bacterial communities were dominated by particle-attached bacteria, which accounted for 78.65%, 70.32% and 68.17% of the total bacterial abundance in spring, summer and winter, respectively. The metabolically active bacteria with high nucleic acid dominated in the particle-attached bacteria, while the low nucleic acid group was the dominant component of the free-living bacteria.

To study the effects of culturing and proliferation of Sipunculus nudus on tidal flat sediment, we carried out an investigation in a culturing zone located in Suixi, Beibu Gulf, China in spring and autumn 2016. The organic matter content (OM), grain size and oxidation reduction potential (ORP) of the sediment were determined in the S group (Sipunculus nudus monoculture), P group (polyculture of S. nudus and Meretrix lyrata) and C group (blank zone without S. nudus). The OM and fine sand of the layer (20~30 cm) in the S group accumulated obviously, but only the surface layer (0~3 cm) in the C group had a similar tendency, which indicated that S. nudus can migrate down the surface sediment, and the migration depth was about 20~30 cm in the tidal flat. The ORP of the pore water in the C group had no significant decrease, and most of the layers in the S group had similar changing trends except that the layer of 10~20 cm decreased to some extent, which indicated that the culture of S. nudus in tidal flat will not result in significant deterioration of sediment. The OM and fine sand of the five layers in the P group increased significantly than those in the S and C groups, which indicated that the Meretrix lyrata had strong filter feeding and deposition ability, and the bioturbation of S. nudus can accelerate the migration of OM and fine sand. The ORP value of the two layers (0~3, 3~10 cm) in the P group decreased significantly than that in the S group (p<0.05), and the results indicated that the high density of Meretrix lyrata will result in significant deterioration of their habitat. S. nudus can migrate down and bury surface organic matter, and M. lyrata can promote the deposition of particulate matter; the complementary functions of the two animals help improve the nutrient utilization and carbon sequestration function of the tidal flat.

The four-season environment ecological comprehensive surveys were carried out at 34 stations in the southern South China Sea by the research vessel “NanFeng” from March to December in 2013. Results show that the average chlorophyll a (Chl a) concentration of shallow water at 150 m in early spring (0.14 mg•m^-3) and early summer (0.12 mg•m^-3) were lower than that in early autumn (0.18 mg•m^-3) and early winter (0.16 mg•m^-3). This was mainly due to the smallest spring wind speed in early spring and the highest water temperature in early summer, which were not conducive to vertical mixing, limiting deep nutrients being brought up. The subsurface Chl a maximum in the four seasons all appeared at both 50 m (0.24~0.26 mg•m^-3) or 75 m (0.22~0.26 mg•m^-3), and the difference of Chl a concentration at these two depths was small, with little season change. The 50 m and 75 m layers were located in the middle part and near the bottom of the euphotic seawater, and the light received by the two layers can meet the growth need of phytoplankton. With the combined impact of mixed layer depth and the upper bound of the thermocline, the Chl a concentration in the 50 m layer was mainly controlled by the supply of nutrients, and that in the 75 m layer, by ocean temperature, both being important factors affecting phytoplankton growth.

Two common reef-building coral species in Luhuitou offshore areas, Favites complanata and Pavona decussata, were selected in our experiments. Continuous culture experiments (21 days) were conducted to evaluate the effects of acidification and dissolved organic carbon (DOC) enrichment on coral physiology. The results showed that: 1) acidification (pH 7.6) did not significantly affect the calcification rates and growth rates of these two coral species. However, in the treatment of DOC enrichment (524.03±78.42μmol•L^-1), the coral calcification rates decreased by 67% and 47%, respectively; the growth rates decreased by 59% and 40%, respectively. In the combined effects of acidification and organic matter enrichment, the calcification rates decreased by 67% and 47%, respectively; the growth rates decreased by 59% and 40%, respectively, but the reduction was less than DOC enrichment alone. To some degree, these results reflected some antagonistic action. The maximum quantum efficiency (F_v/F_m) of these two corals all increased in the early, meanwhile; F_v/F_m of Favites complanata decreased first. 2) Favites complanata and Pavona decussata responded differently to acidification and organic matter enrichment, indicating the species would have different fates in a changing environment in future.

Cold-water corals, also known as deep-water corals, are newly found ecological resources with high biological diversity and attract scientific research on environmental changes. In this study, we investigated cold-water corals retrieved from the cold seep area in the northern South China Sea. We identified two species (Crispatotrochus sp.1, Crispatotrochus sp.2) and four genera [Balanophyllia (Balanophyllia), Balanophyllia (Eupsammia), Lochmaeotrochus, and Enallopsammia]. Stable carbon and oxygen isotopic analyses revealed that the δ¹³C and δ¹⁸O of cold-water corals were -7.36‰ ~ -1.15‰ and -1.38‰ ~ 3.67‰, respectively. The δ¹³C and δ¹⁸O results were close to the carbon and oxygen isotopic values of cold-water corals in other parts of the world, but were quite different from those of warm-water corals, cold-seep carbonate rocks and low-temperature hydrothermal carbonate rocks. This research discovered cold-water corals in a cold seep region of the northern South China Sea. This discovery is important for the studies on environmental effects of deep-water currents and of cold springs in the region.

The development and change of a warm pool have close relationships with sedimentary environment. For the lack of integrated modern sedimentary environmental studies on the Warm Pool of Beibu Gulf, the samples of bottom sediments from the study area within the main part of the Warm Pool were collected and laboratory analysis and identification in granularity, geochemical elements and micropaleontology was carried out. The study and comparison using the above data showed that the provenance came from surrounding up continent crust. Median grain size ranged 1.07Φ~6.88Φ; SiO₂ dominated in macro-geochemical elements with maximum 66.61% and followed by Al₂O₃; micro-geochemical elements and REEs ranged 9.05~297.00μg•g^-1, 0.34~69.43μg•g^-1, respectively, and an averaged chemical index of alteration (CIA) 47.33 and (La/Yb)_N 7.46~10.07 and paleo-biodiversity index of foraminifera and diatom 0~2.52 meaning relatively significant spatial variation under gulf scale. There was primary difference between western and eastern parts of the study area: the former with highest concentration of large part of geo-chemical elements, fine grain, significant fractural in REEs, high CIA and relatively rich provenance and the latter being almost opposite with low elements, low CIA, and so on but with high CaO, MnO and Sr revealing limited provenance supply and probably authigenic carbonate sedimentation. Warm-water foraminifera and subtropical-tropical diatom species took advantage in the study area and ratios between the abundance of species also indicated warm and high saline seawater characteristics especially in the eastern part of the study area. This Warm Pool is either a dependent or an open system, and has a positive effect on maintaining the biological activity, biodiversity and sedimentary environment, especially carbonate sedimentation.

The third scientific drilling in the South China Sea (SCS) will be carried out during Feb. to Jun. 2017 under the system of the International Ocean Discovery Program (IODP), namely, IODP Legs 367 and 368. The drilling project will improve the research on geology and geophysics of the SCS and bring it to an unprecedented stage. The combination of Ocean Bottom Seismometers (OBS) deep seismic survey with IODP drilling data will improve drilling achievement, and contribute greatly to our understanding of the specific mechanism of rifting and breakup processes in the northern SCS. We first built three original velocity models based on the three geological presumptions of IODP Legs 367 and 368 as follows. 1) the exhumed lower crust, 2) the oldest oceanic crust and 3) the exhumed upper mantle. Second, the ray-tracing and travel-time modelling were performed for different OBS intervals with employment of Rayinvr and Tomo2d software, as well as check-board tests for the models. The testing results suggest that the ray-tracing paths and ray density with the 7 km interval of OBS stations are better than those with the 10 km interval. However, the seismic survey line is 100 km, enough in length to make sure to detect the crustal structure at 30 km depth. And the results of check-board tests show that the 7 km interval of OBS stations is necessary to difference the 20-km-in-size velocity anomaly, which is the uncertainty zone in the seismic profile. The design analysis on the optimal deployment scheme of OBS stations will not only provide a good suggestion for the design of future seismic survey, but also contribute to our understanding of the mechanism of rifting and breakup processes in the SCS.

In Dongsha slope of the South China Sea, shallow fracture and reefs are numerous. Shallow Cenozoic is composed of carbonate rocks. The internal structure of deep Mesozoic is complex, with a lot of fracture. The conventional single vessel narrow azimuth seismic section shows poor reflection quality in deep sea. Dual vessels can be used to design flexible observation geometry, such as dual-azimuth seismic exploration. For the same reflection point lighting, this method of dual-azimuth seismic exploration is better than the narrow azimuth detection beneath the high acoustic velocity layer and the steep dip angle layer. Through key technology research and development, the dual-azimuth seismic acquisition was carried out by using single source and two streamers on both sides. We successfully implemented the experiment for the deep target seismic exploration in the South China Sea.

The generation and propagation of internal tides in the Indonesian Seas are investigated by using a three-dimensional ocean model of MITgcm. We find that diurnal tides prevail in the Sulawesi Sea and in the northwestern Pacific, whereas semi-diurnal tides are dominant in the Makassar Strait, Ombai Strait, Timor Sea, and northeastern Indian Ocean. The normalized amplitude of internal tides maximizes near the thermocline in the Sulawesi Sea, Makassar Strait, Ombai Strait, Maluku Sea, Banda Sea, northeastern Indian Ocean, and northwestern Pacific with values of about 20~40 m, whereas it maximizes near the depth of 200 m in the Timor Sea with a value of about 25~30 m. The Sangihe Sill, Seram Sea, Ombai Strait, and Timor Sea are the four major sites of internal tide generation, where the depth-integrated baroclinic energy flux reaches 40 kW·m^-1. The internal tide energy in the Sulu Sea is mainly generated from the conversion of local barotropic tides, whereas that in the Sulawesi Sea and Banda Sea is from remotely generated internal tides.

In this paper, the transport of suspended matter in the surface of the Yellow Sea and the East Sea was analyzed through the fourth band reflectivity of the Moderate Resolution Imaging Spectroradiometer (MODIS) from 2002 to 2015. In the meantime, the in situ data of suspended matter content in the Yellow Sea and the East Sea in 2003 as well as the quasi-real time MODIS image data during this period were utilized to establish a remote sensing inversion model of suspended matter content based on MODIS fourth band remote sensing reflectivity. Using this model, the concentration of suspended matter in the surface layer of the Yellow Sea and the East China Sea was reversed, and the diffusion area of suspended matter was calculated. Then, according to the surface suspended matter concentration obtained from the inversion model and the suspended matter concentration of vertical prediction model, the suspended matter in the vertical direction was estimated. Meanwhile, the suspended matter content in the water at a specific time was calculated by taking into account of water depth and diffusion area. Next, the suspended matter content in the water at various moments during the transport was figured out using cubic polynomial interpolation, from which the transport amount at various moments was derived. The estimated transport amount of suspended matter from the Yellow Sea to the East Sea from October 2002 to April 2003 was 0.153 billion tons.

Copepods play important roles in maintaining the structure of marine ecosystem due to their key position in food chain and their numerous species, quantities and wide distribution. The nutrients obtained by copepod larvae can directly affect their development, then the complement of adult copepods and even their population stability. In this study, in situ feeding of copepodites was evaluated by molecular methods in the waters near the nuclear power plant in Daya Bay (S1: control station, S2: outfall station) in summer 2015. The results showed that 16 prey species in total were identified in both stations, including diatoms (11 species), tunicate (two species), fungi (one species), ichthyosporea (one species), and oomycetes (one species). Diatoms (47.30%) and tunicate (41.89%) were the most abundant food types revealed by the significant proportion of the clones. Similar feeding diversity was discovered in copepodites at S1 and S2, with nine prey species at S1 and 10 at S2, but significant differences in diet composition were revealed, with metazoan (61.54%) and diatoms (68.57%) dominating the diets of copepodites at S1 and S2, respectively. In addition, copepodites appeared to be more herbivorous at S2 with a lower Omnivory Index (0.31) than at S1 (0.72). These results suggested that copepodites could optimize their diet composition by consuming a reasonable percentage of animal and plant materials according to available food sources. More phytoplankton, especially diatoms as diet of copepodites at the outfall station implied that copepodites might change their feeding habits with global warming development.

Nucleic acid indices can indicate nutrition status and growth of copepods; yet, lack of comparison among different phylogenetic groups and indices constrains application of nucleic acid proxies in field investigation. In this study, ingestion rate, growth rate of copepodid at Stage Ⅱ and egg production rate were studied in brackish copepod Pseudodiaptomus annandalei at different food levels (0.2~2.0 μg C·mL^-1). Biochemical indices including mass specific RNA content, DNA content, RNA:DNA, and RNA: protein ratios, as well as elemental composition (mass specific phosphorus content, nitrogen content, atomic C:P, and C:N ratios ), were also measured and described. Ingestion rate, growth rate, egg production rate, and RNA-related indices in copepodids increased with increasing food level hyperbolically, so did RNA:DNA ratio in female adults. Ingestion and growth rates were significantly correlated with RNA-related indices in copepodids in a linear manner and the strength of correlation ranked as RNA:DNA>RNA:PRO>RNA content. Egg production rate, however, was correlated with RNA:DNA and RNA:PRO ratios in female adults with high and moderate significance, respectively. Our results suggested that RNA:PRO ratio is suitable to be an indicator of growth and reproduction rate in copepod besides RNA:DNA ratio and RNA content, which have been applied in field investigation. However, RNA:DNA as proxy of somatic growth should be confined to the same-aged copepod. In addition, the finding of hyperbolic correlation between RNA-related indices and food concentration implied that they may help prediction of food environment for copepod, but may be confined to food levels at unsaturated phase of functional responses of variables.

Surface water samples were collected monthly for a total of 12 months from three stations in Sanya. Their virioplankton and bacterioplankton abundances were measured by flow cytometry and their correlationships with evnironmental factors were also studied. The results show that the abundance of virioplankton (7.63×10⁶ viruses·mL^-1 on average) was higher than bacterioplankton abundance (1.52×10⁶ cells·mL^-1 on average). Virioplankton and bacterioplankton abundances in the Estuary of Sanya River were significantly different from those on the west side of the Luhuitou Peninsula and Xiaodonghai. The highest virioplankton and bacterioplankton abundances appeared in the Estuary of Sanya River, with obvious seasonal variation(P<0.01). The abundances of virioplankton and bacterioplankton were significantly positively correlated (r = 0.800, P<0.01); and chlorophyll a, N nutrients (NO- 2, NO- 2+NO- 3, NH+ 4) are their key ecological factors (P < 0.01).

According to the three elements of “exposure-sensitivity-adaptive capacity,” an index system framework of mangrove ecosystem vulnerability assessment was established based on a VSD (vulnerability scoping diagram) evaluation model. Redefining the vulnerability classification criteria, improved comprehensive index method and fuzzy evaluation method were applied to quantitatively evaluate the mangrove ecosystem vulnerability of Tieshangang Bay in 1989, 2003 and 2014, respectively. The results showed that the mangrove ecosystem vulnerability comprehensive evaluation index values in these three years were 0.145, 0.255 and 0.334, respectively; the scores increased over the years, indicating the Tieshangang Bay ecosystem vulnerability tended to be increasingly vulnerable. First, the mangrove ecosystem exposure index of Tieshangang Bay was increasing, and the major artificial stress factors were reclamation areas and the discharge of wastewater. Second, the sensitivity of Tieshangang Bay mangrove ecosystem was obviously intense, the main sensitive factors were comprehensive index of marine life quality, biological diversity indexes of benthos and intertidal organisms. Last but not least, the adaptive capacity of the ecosystem increased slightly, but is generally weaker.

The monosaccharide composition, functional groups and molecular weight of five crude algal polysaccharides were analyzed by using fourier transform infrared spectroscopy (FTIR), gas chromatography (GC) and gel permeation chromatography (GPC). The results showed that five crude algal polysaccharides contained both xylose and fucose. Padina australis polysaccharide, which was the high molecular weight uniformity-polysaccharide, contained the rich sorbitol, whereas Ulva lactuca polysaccharide had a wide molecular weight distribution and was the poor uniformity-polysaccharide. The analysis of FTIR indicated that five crude polysaccharides were both acidic polysaccharides. Caulerpa sertularioides, Sargassum polycystum and Betaphycus gelatinum polysaccharide had obvious absorption peak of sulfate group. The structure of Betaphycus gelatinum polysaccharide included furanose and pyranose, and the glycosidic bond might include beta and alpha types. The sulfate content of Padina australis polysaccharide was 38.43% (±2.38%), which was significantly higher than that of the other kinds of algal polysaccharides, whereas the sulfate content of Caulerpa sertularioides polysaccharide was only 8.92%(±1.04%).

The northern part of the South China Sea (SCS) is one of the important oil and gas bearing areas in China. However, the evolution history of the basins located in the northern SCS and their relationship with the surrounding tectonic events are still unclear. Based on the drilling and seismic data, the tectonic stress evolution characteristics and the initial crustal thickness of the Qiongdongnan Basin and Pearl River Mouth Basin are calculated by using mathematical simulation. The results show that the basins of the northern SCS have thinner initial crust thickness and lithospheric thickness. There exist two stress relaxation periods in the Pearl River Mouth Basin, and two stress relaxation periods in the Qiongdongnan Basin, one in shallow water and the other in deep water. The first period of stress relaxation in the northern SCS was continuous in space, which is mainly distributed in the deep water area, and was earlier in the east and later in the west. The second period was different in the east and west. The analysis shows that the stress relaxation periods in the deep water of the northern SCS were related with shear rifting from east to west of the northwest sub-basin of the SCS. The second period of stress relaxation in the Pearl River Mouth Basin was related to local magmatic intrusion, and the stress relaxation period in the shallow water of the Qiongdongnan Basin corresponded to the quiet period of the Red River fault.

Well LF14, drilled in the Lufeng Sag of the northern South China Sea, discloses marine sediment archives ranging from the mid-to-late period of the early Miocene to the early Pliocene. An abrupt rise in paleo-water depth up to 275 m during the early Miocene is recorded at the lowermost part of the well, followed by several fluctuations thereafter. The early Miocene to early Pliocene deposits are interpreted as formed under middle-to-outer shelf environment, and five complete transgressive-regressive sea-level cycles are identified. The results of backstripping calculations indicate a rapid subsidence in the study area during 17.5-10 Ma. The high sedimentation rate in this period may be caused by rapid tectonic subsidence and high terrigenous input. The subsidence rate was low from 10 to 4.53 Ma, characterized by a low sedimentation rate mainly due to less supply of terrigenous materials and less accommodation space caused by the Dongsha Movement. Finally, several short-lived uplift events were identified in the well based on quantitative reconstruction of paleo-water depth.

Marine geological survey is the strategic demand of our country to build a powerful marine nation. The survey data have important application values. With the rapidly developing technologies of computer, database and network, combining the ways of digital management, application and sharing of marine geological survey data has become an important indicator to measure the level of marine science and technology in China. In view of disadvantages of poor interactivity and low scalability in traditional WebGIS application, the sharing service platform of marine geological survey data in the South China Sea on the web was developed by Flex API and ArcGIS Flex Viewer, to develop widget for functional expansion based on the application framework. The users can browse and inquire these data easily. In this paper, the centralized management, display and service of the marine geological survey data in the South China Sea are illustrated. The results show that the platform can meet information service demands of marine users.

In order to study the trend, shape and tectonic setting of the Changle—Nan’ao fault and Binhai (littoral) fault, the Earthquake Administration of Fujian Province expanded seismic sounding into the southwest Taiwan Strait using large volume air-gun arrays and Ocean Bottom Seismometers (OBSs), which formed a relatively complete observation system in conjunction with onshore explosions and portable seismometers. In this paper, we introduce in detail the six profiles collected between 2013 and 2015, including the observation system, acquisition parameters, and data preprocessing. Due to rational choice of shooting parameters and receiver position, a variety of seismic phases, including Pg, PmP, Pn, Sg, and SmS, can be clearly identified in most common receiver gathers of the portable seismometers and OBSs. By multiple shooting the air-gun array at fixed site, we obtained several stacked common shot gathers, of which the signal-to-noise ratios were as high as those acquisition with ton-level explosions. Compared with the data recorded by onshore seismometers, the data recorded by OBSs have a relative low signal-to-noise ratio, which probably means that the seabed in this area has a higher absorption. In light of low velocity and acute variety of deposition thickness in the southwest Taiwan Strait, we transfer the travel times, which were picked up on the common receiver gathers to shot domain, in order to avoid the errors of sediment model, which resulted in pseudo deep structures.

Because of the influence of strong reflection interfaces such as free surface, seabed, etc., the ghost produces obvious notches in ocean bottom cable (OBC) spectra. It degrades the quality of sections, and increases the difficulty of processing and interpretation. According to different responses of hydrophone and geophone to down-going wave field, we present a new dual-sensor summation method based on pseudo-multichannel matching filter. Compared with traditional methods, the proposed method is totally data driven, so it does not depend on the reflection coefficient. In practical applications, the method can effectively suppress ghosts, remove notches and expand spectral bandwidth. The good results reveal the effectiveness of this method.

Temporal variation characteristics of ocean waves in the coastal area of Dongfang, Hainan are analyzed based on observations of ocean waves for a whole year from Aug 1, 2014 to Jul 31, 2015. During the observation period, the maximum height of the significant wave height was 4.03m, the average was 0.79m; the maximum value of the mean period was 6.32s, and the average was 3.58 seconds. In this sea area, the wave height was higher in winter, with minimum in autumn. The normal wave direction was SSW, and the strong wave direction was WSW. Based on the one-year observation data, the relation between the mean period and significant wave height was studied, and the relation between the significant wave height and its mean duration was also established. Finally, the variation characteristics of wave energy density in the observation period were discussed. We found that the frequency of wave energy density above 2kW·m^-1 in one year was 26%, and the wave energy at the observation location increased faster in December, but the total wave energy resources were not rich enough. The results obtained in this study are of great significance for understanding the wave characteristics and engineering design of the coastal area of Dongfang, Hainan.

The site southwest of Taiwan Island is one of the places where warm core eddies originate. Extensive studies on warm eddies have been conducted; however, a majority of these studies focused on eddy characteristics, such as radius, generation area and lifetime. Some discussed generation mechanisms while the investigation of transport by warm eddies remains scarce. We observed a warm eddy during autumn 2003 to spring 2004 using both AVISO (Archiving Validation and Interpretation of Satellite Oceanographic Data) altimetry data and the Regional Ocean Modeling System (ROMS) output data. A total of 10, 000 particles were released inside the warm eddy at 10, 50 and 100 m, respectively. The lifespan of the warm eddy was 121 days, with a mean radius of 50.4 km; and it traveled 1437.5 km at a mean speed of 13.5 cm·s^-1. Most of the tracers were trapped inside the eddy and were carried southwestward along 1000-2000 m isobaths. Because of the terrain and its interaction with the flow, the eddy was more unstable during its terminal stage. Many of the tracers were expelled from the eddy, and the number of remaining tracers dropped to only 18.6%-35.6%. Although this ratio may seem small, the accumulative effects of transport were considerable. The number of tracers in the warm eddy had a strong positive correlation with potential vorticity (PV) with a correlation coefficient of 0.63. The tracers were trapped by the outmost PV contour The tracers inside the eddy sank in a spiral. Within the first 5 days, only 3.9% of the particles sank deeper than 15 m. The mean depth of tracer particles inside the eddy was observed to to 48.7, 88.7 and 130.6 m for those released at 10, 50 and 100 m, respectively.

Mesoscale energy can be effectively extracted from geostrophic flows via sub-mesoscale processes and forward cascade to smaller dissipation scales. These ubiquitous sub-mesoscale processes in the upper ocean play an important role in the transport of mass and energy, mesoscale variability and re-stratification of mixed layer. Using the high-resolution (500-m) ROMS results, we preliminarily analyze the sub-mesoscale dynamic processes of typical anticyclonic eddy in the northern South China Sea in winter. Our results show that the strong lateral buoyancy gradient at eddy periphery can efficiently reduce the Ertel potential vorticity of the front, which exacerbates frontal instabilities and is favorable for the development of symmetric instability (SI). In this case, one of the most important mechanisms is the frontogenesis for the generation of frontal SI. Furthermore, sub-mesoscale processes and associated instabilities can trigger a strong vertical secondary circulation across the front. The vertical velocity is up to 95 m·d^-1, suggesting significant vertical exchanges of mass and energy in the mixed layer.

We selected two rapidly intensifying, locally-originated typhoons Wutip (1321) and Mirinae (1603), and analyzed upper- and low-level circulations, vertical wind shear, and ocean heat content in and around the South China Sea during typhoons’ passages over the sea. We also used WRF (Weather Research and Forecasting Model) model to discuss the environmental factors for their different intensities. Although the underlying conditions were more favorable for Mirinae, it did not develop into a strong typhoon due to weak upper- and low-level circulations and strong vertical wind shear. On the contrary, Wutip developed into a super typhoon rapidly due to the cold southward airflow and the outburst of warm humid air from the southwest. The results from WRF model’s sensitivity experiments about the effect of sea surface temperature (SST) on the intensity of locally-originated typhoon indicated that locally-originated typhoon intensity and SST have nonlinear positive correlation. However, as SST increases, the intensification trend of locally-originated typhoon slows down. From July to September, the SST in the South China Sea is higher than 28℃, meeting the condition for typhoon intensification. Therefore, attention should be paid to different environmental factors other than SST in locally-originated typhoons’ forecast in the South China Sea.

Using remote sensing to accurately estimate phytoplankton absorption coefficient a_ph(l) can provide basic data and useful method to distinguish different functions of phytoplankton species for long time and large spatial scale. In this paper, the characteristics of a_ph(l) spectral are compared and analyzed in four typical areas of the South China Sea (SCS), east area of Qiongdong (QD), Guangdong Coastal area (GD), and the Pearl River Estuary (PE) by using field data collected during2003-2012.Then, the phytoplankton population structure differences are preliminarily identified. Furthermore, the performances of MODIS-Aqua a_ph(l) products derived from the semi-analytical algorithm QAA and empirical algorithm PL by using MODIS-Aqua remote sensing reflectance R_rs(l) products are compared in the SCS and QD waters based on the relaxed match-ups between MODIS-Aqua products and field data. The results show the differences of a_ph(l) spectral features are obvious among the clear water represented by the SCS and QD and turbid waters represented by GD and PE. In the clear waters, the a_ph(l) value is small but in a dominant position of particle absorption, while in the GD and PE areas, the a_ph(l) value is relatively large but not in a dominant position. The a_ph(l) coefficient have obvious spatial differences, and the possible causes are pigment packaging effect and the variation of pigment composition and concentration. MODIS-Aqua a_ph(l) products derived from the empirical algorithm PL perform better than those from the semi-analytical algorithm QAA. The algorithm QAA-derived a_ph(l) products underestimate the results compared to the field data, while the algorithm PL overestimate the results, with the average relative error (APD)less than 22% for both algorithms. There is a great improvement in the accuracy of the PL algorithm by using the Chl-a products derived from the optimized algorithm of OCI (named algorithm NOCI), with the APD less than 14%. In summary, there are strong application prospects to discuss different functions of ocean phytoplankton species by using remote sensing products.

Dopamine receptor is an important neurotransmitter receptor, playing a key role in organism growth, development, metabolism, and other physiological processes. In this study, we obtained a fragment of dopamine receptor gene from transcriptome library of razor clam (Sinonovacula constricta), and cloned the full-length cDNA of dopamine receptor gene using RACE (rapid-amplification of cDNA ends) and Touchdown PCR (polymerase chain reaction). The full-length cDNA sequence contains two isoforms of alternative polyadenylation (APA), named as ScDopR2a and ScDopR2b, with a length of 1824 bp and 2758 bp, respectively. Both isoforms contain a 24 bp 5′untranslated region (UTR), and a 1440 bp open reading frame encoding 479 amino acid residues. However, the 3′UTR length is 360 bp and 1294 bp for ScDopR2a and ScDopR2b, respectively, with an insertion of 936 bp in front of the polyA tail for ScDopR2b. Primers were designed in open reading frame (ORF)to detect the expression level of dopamine receptor gene (ScDopR2) by quantitative real-time PCR. The results revealed the expression in waterpipe, gill and foot were higher than that in the other tissues. Then, primers were designed in 3′UTR to detect the expression level of ScDopR2b, showing similar expression pattern with ORF region. In the tissue damage experiment, the samples were selected at 4, 8, 12, 24, 48, 60, and 72 h after injuring waterpipe. The fluorescence quantitative results showed that a significant increase in 12 and 48 h, and a significant decrease in 8, 24 and 72 h. The trend of ScDopR2b gene’s expression level was similar to that of ORF. The results suggested that dopamine receptors are involved in the damage-healing process, and the expression pattern may be due to a role of dopamine as compensatory neurotransmitters.

Marine ecological effects induced by thermal discharge of nuclear plants in Daya Bay are attracting increasingly attention. Based on in situ data and laboratory experiments, distribution characteristics of phytoplankton size structure within the thermal-discharge-affected area and their responses to warming and nutrients input were explored. The results indicated that phytoplankton growth could be promoted by moderate warming but inhibited in extremely high temperature (36ºC). Chl-a concentrations near the outfall of thermal discharges were obviously low in both summer and winter. There were seasonal discrepancies between two important environmental factors, i.e., warming and nutrient enrichment, on their contributions to phytoplankton growth based on simulation results. Nutrients inputs showed more obvious impacts on phytoplankton than temperature in summer, and vice versa in winter. The increasing proportion of small-size phytoplankton (< 20μm) might be induced by warming and/or nutrient enrichment in Daya Bay, which confirmed the miniaturization trend within the plankton community and indicated its potential impacts on energy flow and material cycle, ecosystem stability, and production of marine fisheries in the bay.

Genetic diversity and genetic differentiation among 90 individuals of Penaeus monodon from three wild populations (Zhanjiang, Sanya, and Qionghai) were investigated by using 14 pairs of simple sequence repeat (SSR) specific primers. The number of alleles detected by each pair of primers ranged from 2 to 4, with the average of 2.7. The mean polymorphism information contents of the three populations were 0.3864, 0.3926, and 0.4078, respectively; and the mean effective numbers of alleles were 1.9081, 1.9715 and 2.0185, respectively. The average expected heterozygosity (0.4605) of the three populations was significantly higher than the observed heterozygosity (0.40469), indicating moderate polymorphism and the existence of heterozygosity deficiency among the three populations. The results of genetic distances and genetic similarity showed that the genetic differentiation among the three populations was low; genetic variation occurred mainly within populations, not among populations. The genetic relationship of Sanya and Qionghai populations was the closest, while that of Sanya and Zhanjiang populations was the farthest. Analysis of molecular variance (AMOVA) revealed that most of the genetic variation resided within populations (92%), and less, among populations (8%), suggesting rich genetic diversity level within populations.

We deal with four confused species from the China seas. Nerita chamaeleon Linnaeus, 1758 and Nerita histrio Linnaeus, 1758 have similar shell characters and are often confused and misidentified as each other. The classification of Nerita polita Linnaeus, 1758 and Nerita litterata Gmelin, 1791 had been confused for quite a long time, and both were usually identified as Nerita polita. Our comparative study is conducted on the Nerita specimens deposited in the Marine Biodiversity Collections of South China Sea (SCSMBC, Guangzhou) and the Marine Biological Museum (MBM, Qingdao), Chinese Academy of Sciences. The taxonomic confusion of the four species is clarified on shell morphology, distribution and habitat; and species statuses of the two are confirmed.

The shallow gas reservoir in the northern deep water area of the South China Sea (SCS) is a new type of oil-gas reservoir associated with gas hydrate, which has the characteristics of shallow burial and large scale, and its burial depth is generally less than 300 m. The shallow gas reservoir was formed by the gas hydrate cap in the deep cracking gas along the fault, and the identification of bottom simulating reflector is an effective method to find the shallow gas reservoir. The gas sources mainly include: pyrolysis gas, biogas and mixture. Slope tensile rupture is a major channel for gas migration, a sand layer at the bottom of the hydrate is the main reservoir of shallow gas accumulation, and the hydrate layer is blocked. Looking from gas hydrate distribution characteristics found in the SCS, shallow gas reservoir, widely distributed in slope deep-water area, with big reservoir thickness, and potentially significant resources, is a new type of reservoir while mining costs are relatively low.

The water around submarine hydrothermal vents has significant turbidity and chemical composition anomalies, providing an important indicator for finding hydrothermal vents. In this paper, a detection method of submarine hydrothermal vents was proposed, and a low-power chemical sensor hydrothermal detection system was designed. The chemical sensor can detect real-time potential values of pH, H₂S, Eh, and CO₃^2- when mounted on the relevant detection platform. Combined with abnormal turbidity, we can infer the location of hydrothermal vents. The results of the testing in the Southwest Indian Ridge showed that the chemical sensor can effectively detect chemical abnormalities caused by hydrothermal activity, which is an effective technique for detecting hydrothermal vents.

In order to test the performance of fiber optic hydrophone array in marine seismic exploration, we carried out a test in the South China Sea. We used the same mode of operation in the same location for marine seismic exploration, using the 1024 channels fiber-optical hydrophone array and the 360 channels piezoelectric hydrophone imported marine seismic exploration devices. Then, we compared the marine seismic exploration data collected by the two setups. The test results show that the frequency range of the data collected by the fiber optic hydrophone array reached 10-120 Hz, which is wider than 10-80 Hz of the piezoelectric hydrophone marine seismic exploration devices. The resolution ratio of seismic section is better than that of piezoelectric hydrophone marine seismic exploration devices. After some adaptive improvements, the fiber optic hydrophone array can satisfy the performance requirements of marine seismic exploration.

With the increase of marine plastic waste, marine microplastics have attracted more and more attention as a new type of marine pollution. At present, studies of the source, distribution and analytical approach of microplastics are well recognized. Most research focuses on plastic ingestion by marine organisms, and on the effects of microplastics adsorbing and releasing toxic chemicals. However, the role of microplastics as a vector for pelagic microorganism, phytoplankton and micozooplankton is poorly understood. In this review, we address three functions of microplastics as a biological vector. 1) Aggregation, it is easy for biofilms to form a microbial community on the surface of microplastics, which provide the means for horizontal transfer of organisms and genes, and may lead to the transformation or transduction of pathogenic gene, antibiotic resistance gene (ARGs), called genetic exchange. 2) Dispersal, the spread of harmful algal species, pathogenic bacteria and drug-resistant bacteria as well as other microorganisms may happen when the microplastics are freshly from the waste water flow, which potentially poses a risk of invasion when arriving in a new habitat with favorable condition. 3) A feeding enhancement concept, we propose this concept because a piece of microplastics is full of the attached biofilms, nutrients and organisms, which may attract large grazers or predators and can also improve their predation efficiency. As a result, these grazers/predators may seek pieces of microplastic as foods, which may cause more serious toxicological effects. The review focuses on the ecological effects of “microplastic + biology”.

Our Argo trajectory simulation system for the South China Sea (SCS) contains the high-resolution ambient velocity field, a Lagrangian particle tracking model and the parameterization that represents the vertical motions of profiling Argo floats. This system is applied to simulate both conventional Argo floats (typically parked at 1000 m depth and profiling to 2000 m depth) and Deep Argo floats (parked at 500 m above the seafloor) within the SCS. By conducting the simulation with the counterparts of six core Argo floats serviced in the SCS, we find the displacements of synthetic floats from the simulation system resemble the real float displacements over 100-day time intervals. We therefore judge the simulations for core Argo are robust and further apply the system to simulate a potential Deep Argo array (with the resolution of 2°×2°×30 day). The results explore both the representativeness and the predictability of float displacements, which may provide a basis to understand float displacements in the deep layer as well as to contribute to planning deep Argo array program.

In this study, we comparatively analyzed four designed wave recurrence levels of bivariate joint distribution of wave height and wave period by using Archimedean copula function, Kendall distribution function and survival Kendall distribution function. The annual maximum wave height and corresponding wave period of US Army Corps of Civil Engineers Field Research Facility (FRF) at Duck of North Carolina, US as an example, the “OR” primary return periods, “AND” primary return periods, Kendall return periods and survival Kendall return periods of bivariate joint distribution and the most likely designed wave quantiles were computed by using the optimally fitted Gumbel-Hougaard copula. The main conclusions of this study are summarized as follows: Comparing different specific wave return periods, the Kendall return periods can more accurately reflect wave risks relative to “OR” primary return periods, while the survival Kendall return periods can more accurately reflect wave risks when two wave variables are supercritical at the same time with respect to “AND” primary return periods. The univariate wave height or wave period designed value has reached a higher design standard according to the relevant specifications of the current design requirements. The estimated wave design quantiles of the “OR” primary return periods and two variables with the same frequency are obviously higher than those of univariate wave elements. The most-likely design realizations of the Kendall return periods and the survival Kendall return periods can serve as the new selections for safety and risk management of coastal engineering projects.

To clarify the causative species of a diatom bloom occurred in Hongcheng Lake of Haikou City, Hainan Province during 4-10 May 2016, several water samples were collected from bloom regions. Based on the morphological features under light and electron microscopy, the causative species was identified as Actinocyclus exiguus Fryxell & Semina, a newly recorded diatom species in China. Its bloom was also new in China, and was the second case globally. Actinocyclus exiguus belongs to centricae diatom, and their cells are usually solitary, or sometimes form colonies in mucilage. The cells are small in size, with diameter around 6.4~11.1 µm. There are 2~3 rimoportulae at valve margin, as well as a pseudonodulus. It is speculated that rich density of ammonia-nitrogen (average of 2880 µg•L^-1) and high water temperature (average of 31℃) could be important induced factors for this A. exiguus bloom. About 40 tons of dead fishes (Clupanodon thrissa) was reported during the bloom; and algal toxins, mechanical injury and dissolved oxygen in the water were excluded as the mortal factors, after body check of dead fishes. Physical stress reactions, such as acute change of salinity, might be responsible for the death of the fishes.

According to the morphological and anatomical procedures, the marine red algal genus Gracilaria was studied using the samples collected from the southeastern coast of Hainan province, China. Four species were identified, namely, Gracilaria eucheumoides, G. blodgettii, G. salicornia, and G. spinulosa. Their morphological characteristics were described in detail. Combined with the Cryo-sectioning Technique, the anatomical figures of all species were obtained, including distinctive cystocarps of Gracilariophila deformans on G. salicornia. These findings provide science and technology support for the protection and utilization of these resources in Hainan province, China.