Brown tides have recurred in estuary areas globally, but trophic interactions between the causative species Aureococcus anophagefferens and planktonic copepods remain poorly understood. In this study, we investigated performance (ingestion, growth, development and reproduction) of the planktonic copepod, Pseudodiaptomus poplesia, offered either mono-algal or mixed-algal diets containing a Chinese strain of A. anophagefferens. A typical Michaelis-Menten pattern existed between ingestion rate and food level when copepod fed on the mono-algal diet of this species. Nauplii exhibited the highest maximum ingestion rate (I_max) than copepodids and adult females. In addition, I_max value was higher in nauplii feeding on A. anophagefferens than on Skeletonema costatum. When fed mixtures of A. anophagefferens and S. costatum, P. poplesia selected against A. anophagefferens cells, but less strongly at the naupliar stage. Nauplii did not undergo metamorphosis and died at late naupliar stages feeding on A. anophagefferens alone, similar to those under starvation. Furthermore, the presence of A. anophagefferens greatly reduced the reproduction rate of females in mixtures but did not influence the growth rate of copepodids. These results suggest that P. poplesia nauplii may exert grazing pressure on A. anophagefferens population during a brown tide, which, however, may not be persistent because of copepod population decline.

The chromosomes of spinyhead croaker Collichthys lucidus (Richardson, 1844) were characterized for the first time by fluorescence staining, self genomic in situ hybridization (self-GISH), and multicolor fluorescence in situ hybridization (FISH) with 18S rDNA, 5S rDNA and telomeric sequence probes. The female karyotype has exclusively 24 pairs of acrocentric chromosomes (2n=48a, NF=48), while the male one consists of 22 pairs of acrocentric chromosomes, 2 monosomic acrocentric chromosomes and a metacentric chromosome (2n=1m+46a, NF=48). The difference between female and male karyotypes indicates the presence of a sex chromosome of X₁X₁X₂X₂/X₁X₂Y type, where Y is the unique metacentric chromosome in the male karyotype. As revealed by FISH, 5S rDNA and 18S rDNA sites were mapped at syntenic position of the largest acrocentric chromosome (X₁), and the short arms of the Y chromosome as well. An X₁-chromosome specific interstitial telomeric signal (ITS) was detected overlapping the 5S rDNA sites. In addition, self-GISH revealed that the repetitive DNAs accumulated on all the putative sex chromosome. Chromosome fusion accompanied by a partial deletion in the ancestral karyotype (2n=48a) is hypothesized for the origin of such multiple sex chromosome system. The present study, as the first description of differentiated sex chromosome in family Sciaenidae, will give clues to the studies on the sex chromosome of other Sciaenids.

The unique survey in December 1998 mapped the entire western boundary area of the South China Sea (SCS), which reveals the three-dimensional structure and huge volume transport of the swift and narrow winter western boundary current of the SCS (SCSwwbc) in full scale. The current is found to flow all the way from the shelf edge off Hong Kong to the Sunda Shelf with a width around 100 km and a vertical scale of about 400 m. It appears to be the strongest off the Indo-China Peninsula, where its volume transport reached over 20×10⁶ m³/s. The current is weaker upstream in the northern SCS to the west of Hong Kong. A Kuroshio loop or detached eddy intruded through the Luzon Strait is observed farther east where the SCSwwbc no more exists. The results suggest that during the survey the SCSwwbc was fed primarily by the interior recirculation of the SCS rather than by the “branching” of the Kuroshio from the Luzon Strait as indicated by surface drifters, which is likely a near-surface phenomenon and only contributes a minor part to the total transport of the SCSwwbc. Several topics related to the SCSwwbc are also discussed.

In order to evaluate the assimilation results from a global high resolution ocean model, the buoy observations from tropical atmosphere ocean (TAO) during August 2014 to July 2015 are employed. The horizontal resolution of wave-tide-circulation coupled ocean model developed by The First Institute of Oceanography (FIOCOM model) is 0.1°×0.1°, and ensemble adjustment Kalman filter is used to assimilate the sea surface temperature (SST), sea level anomaly (SLA) and Argo temperature/salinity profiles. The simulation results with and without data assimilation are examined. First, the overall statistic errors of model results are analyzed. The scatter diagrams of model simulations versus observations and corresponding error probability density distribution show that the errors of all the observed variables, including the temperature, isotherm depth of 20°C (D20), salinity and two horizontal component of velocity are reduced to some extent with a maximum improvement of 54% after assimilation. Second, time-averaged variables are used to investigate the horizontal and vertical structures of the model results. Owing to the data assimilation, the biases of the time-averaged distribution are reduced more than 70% for the temperature and D20 especially in the eastern Pacific. The obvious improvement of D20 which represents the upper mixed layer depth indicates that the structure of the temperature after the data assimilation becomes more close to the reality and the vertical structure of the upper ocean becomes more reasonable. At last, the physical processes of time series are compared with observations. The time evolution processes of all variables after the data assimilation are more consistent with the observations. The temperature bias and RMSE of D20 are reduced by 76% and 56% respectively with the data assimilation. More events during this period are also reproduced after the data assimilation. Under the condition of strong 2014/2016 El Niño, the Equatorial Undercurrent (EUC) from the TAO is gradually increased during August to November in 2014, and followed by a decreasing process. Since the improvement of the structure in the upper ocean, these events of the EUC can be clearly found in the assimilation results. In conclusion, the data assimilation in this global high resolution model has successfully reduced the model biases and improved the structures of the upper ocean, and the physical processes in reality can be well produced.

The condensate and bunker oil leaked from the Sanchi collision would cause a persistent impact on marine ecosystems in the surrounding areas. The long-term prediction for the distribution of the oil-polluted water and the information for the most affected regions would provide valuable information for the oceanic environment protection and pollution assessment. Based on the operational forecast system developed by the First Institute of Oceanography, State Oceanic Administration, we precisely predicted the drifting path of the oil tanker Sanchi after its collision. Trajectories of virtual oil particles show that the oil leaked from the Sanchi after it sank is mainly transported to the northeastern part of the sink location, and quickly goes to the open ocean along with the Kuroshio. Risk probability analysis based on the outcomes from the operational forecast system for years 2009 to 2017 shows that the most affected area is at the northeast of the sink location.

This study presents an analysis of the CTD data and the turbulent microstructure data collected in 2014, the turbulent mixing environment above the Atlantic Water (AW) around the Chukchi Borderland region is studied. Surface wind becomes more efficient in driving the upper ocean movement along with the rapid decline of sea ice, thus results in a more restless interior of the Arctic Ocean. The turbulent dissipation rate is in the range of 4.60×10^–10–3.31×10^–9 W/kg with a mean value of 1.33×10^–9 W/kg, while the diapycnal diffusivity is in the range of 1.45×10^–6–1.46×10^–5 m²/s with a mean value of 4.84×10^–6 m²/s in 200–300 m (above the AW). After investigating on the traditional factors (i.e., wind, topography and tides) that may contribute to the turbulent dissipation rate, the results show that the tidal kinetic energy plays a dominating role in the vertical mixing above the AW. Besides, the swing of the Beaufort Gyre (BG) has an impact on the vertical shear of the geostrophic current and may contribute to the regional difference of turbulent mixing. The parameterized method for the double-diffusive convection flux above the AW is validated by the direct turbulent microstructure results.

Polymetalic sulfide is the main product of sea-floor hydrothermal venting, and has become an important sea-floor mineral resources for its rich in many kinds of precious metal elements. Since 2007, a number of investigations have been carried out by the China Ocean Mineral Resources Research and Development Association (COMRA ) cruises (CCCs) along the Southwest Indian Ridge (SWIR). In 2011, the COMRA signed an exploration contract of sea-floor polymetallic sulfides of 10 000 km² on the SWIR with the International Seabed Authority. Based on the multibeam data and shipborne gravity data obtained in 2010 by the R/V Dayang Yihao during the leg 6 of CCCs 21, together with the global satellite surveys, the characteristics of gravity anomalies are analyzed in the Duanqiao hydrothermal field (37°39′S, 50°24′E). The “subarea calibration” terrain-correcting method is employed to calculate the Bouguer gravity anomaly, and the ocean bottom seismometer (OBS) profile is used to constrain the two-dimensional gravity anomaly simulation. The absent Moho in a previous seismic model is also calculated. The results show that the crustal thickness varies between 3 and 10 km along the profile, and the maximum crustal thickness reaches up to 10 km in the Duanqiao hydrothermal field with an average of 7.5 km. It is by far the most thicker crust discovered along the SWIR. The calculated crust thickness at the Longqi hydrothermal field is approximately 3 km, 1 km less than that indicated by seismic models, possibly due to the outcome of an oceanic core complex (OCC).

The present climate simulations of the mixed layer depth (MLD) and the subduction rate in the subtropical Northeast Pacific are investigated based on nine of the CMIP5 models. Compared with the observation data, spatial patterns of the MLD and the subduction rate are well simulated in these models. The spatial pattern of the MLD is nonuniform, with a local maximum MLD (>140 m) region centered at (28°N, 135°W) in late winter. The nonuniform MLD pattern causes a strong MLD front on the south of the MLD maximum region, controls the lateral induction rate pattern, and then decides the nonuniform distribution of the subduction rate. Due to the inter-regional difference of the MLD, we divide this area into two regions. The relatively uniform Ekman pumping has little effect on the nonuniform subduction spatial pattern, though it is nearly equal to the lateral induction in values. In the south region, the northward warm Ekman advection (–1.75×10^–7 K/s) controls the ocean horizontal temperature advection (–0.85×10^–7 K/s), and prevents the deepening of the MLD. In the ensemble mean, the contribution of the ocean advection to the MLD is about –29.0 m/month, offsetting the sea surface net heat flux contribution (33.9 m/month). While in the north region, the southward cold advection deepens the MLD (21.4 m/month) as similar as the heat flux (30.4 m/month). In conclusion, the nonuniform MLD pattern is dominated by the nonuniform ocean horizontal temperature advection. This new finding indicates that the upper ocean current play an important role in the variability of the winter MLD and the subduction rate.

The rip currents induced by waves off arc-shaped coastlines are seriously harmful to humans, but understanding of their characteristics is lacking. In this study, the FUNWAVE model was used to calculate the wave-induced currents in the Haller experiment and the ideal arc-shaped coast similar to Sanya Dadonghai, Hainan Province, China. The results showed that the FUNWAVE model has considerable ability to simulate the rip currents, and it was used to further simulate rip currents off arc-shaped coastlines to investigate their characteristics. The rip currents were found to be stronger as the curvature of arc-shaped coastline increased. Coastal beach slope exerts a significant influence on rip currents; in particular, an overly steep or overly mild slope is not conducive to creating rip currents. Furthermore, the rip currents were found to become weaker as the size of arc-shaped coast decreased. When the height and period of waves increase, the strength of rip currents also increases, and, in some cases, wave heights of 0.4 m may produce dangerous rip currents.

The routine operational sigma0 regrouping method is proposed for a HY-2A scatterometer (HSCAT) that maps time-ordered sigma0s and related parameters into a subtrack aligned grid of wind vector cells (WVCs). The regrouping method consists of two critical steps: ground grid generation and sigma0 resampling. The HSCAT uses subtrack swath coordinates, in which the nadir track of the satellite represents the center and the designated positions are specified in terms of a pair of along-track and cross-track coordinates. To calculate the subtrack coordinates for each sigma0, a “triangle marking” resampling method is developed. Three points, including the point of intersection, the center of a pulse footprint, and the origin of the subtrack coordinate system, form a right triangle; the length of the two right-angled sides is used to represent the cross-track and the along-track coordinates in the subtrack coordinate system. In addition, a nadir point interpolation correction is used to ensure the operation of the regrouping algorithm when the nadir point positional information is missing. To illustrate the ability of the proposed regrouping algorithm, the distribution of the WVC positions and wind vector retrieval results are analyzed, which show that the proposed regrouping algorithm meets the requirements for high-quality sea surface wind field retrieval.