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The interannual and season spatial distribution of the peak phase speed of the wave, wave age, wave slope etc, which described for swell and wave-driven wind regime are given by the ERA-40 reanalysis data. The swell speed is the largest in the eastern Pacific equatorial region and other sea, and the propagation from south to north is obvious. The wave boundary layer (WBL) height in the Pacific Ocean shows the distribution situation with the higher in east and lower in the west. The wave-driven wind regime occurs mainly in the equatorial tropical seas, which is stronger in summer and weaker in winter in the northern hemisphere, but that in southern hemisphere is contrary. The northern seas of the northern hemisphere are more prone to the wave-driven wind regime in summer, while the seas near the equator are opposite. The waves in South China Sea is mixture waves of wind waves and swell, therefore it is necessary to discuss separately for the wave climate research.

In the previous studies, some traditional theoretical models and empirical models were used to construct the typhoon dynamic field, and the typhoon wind field and pressure field were used to drive the wave model. It could not reflect the sea-air dynamic process induced by typhoon and it was difficult to provide high-precision wind and pressure field data for the wave model. In order to solve this problem, a mesoscale meteorological model (WRF) and the third-generation wave model (SWAN) had been used to construct a two-way coupled atmosphere-wave model. This coupled model had been applied to the simulation of an idealized typhoon. The results show that the coupled WRF-SWAN model can successfully simulate the distribution of typhoon waves induced by an ideal typhoon and reveal the spatially asymmetric distribution called right side enhancement of typhoon wind field and waves field. This coupled atmosphere-wave model can be further promoted for simulation analysis of actual typhoon.

Gondwana breakup and the complex rift of Madagascar-Seychelles-India were associated with the formation and evolution of the Seychelles micro-continent and Northern Seychelles Plateau. Based on the high resolution multibeam and gravity data acquired from the China-Seychelles continental margin marine science joint cruise in 2016, high resolution topographic and gravity anomaly map were drew at the first time. Combined with the topography and other geological and geophysical data, the evolution of the Northern Seychelles Plateau was discussed by using the method of the tectonic geomorphology. Here, three narrow ridges and flat abyssal plain which were separated by Amirante Trench from the Seychelles micro-continent were found at the Northern Seychelles Plateau. These ridges extend seaward and apparent discontinuity on topography, which approve that the studying area is an independent tectonic unit that doesn't belong to the Seychelles micro-continent natural extension part. By reviewing the geochemical evidence from the scraping rock samples and plate tectonic evolution history, we suggest that Northern Seychelles Plateau are likely formed during the early expansion phase of the Indian Ocean and the seaward discontinuous ridges are affected by the magma eruption along the transform fault.

Submarine canyons are well developed in the northern continental slope of the South China Sea, featured with different evolution history and controlling factors. Four typical submarine canyons in this region, including the Pearl River Canyon system, Dongsha Canyon, Taiwan Bank Canyon, and Penghu Canyon were selected in this study. Based on combined geological interpretations with multi-channel seismic data and high-resolution bathymetric data, as well as previous works, the morphological characteristics, sedimentary structures, the formation processes, and the controlling factors of these submarine canyons were studied. Results show that the formation of various submarine canyons in the northern continental slope of the South China Sea are dominated by various factors, including the tectonic activities, sea level change and sediment gravity flow. The rivers on land and local tectonics (such as magma intrusion, uplifting) also affect their formation. For submarine canyon developed on the active continental margin, such as the Penghu Canyon, is mainly controlled by tectonic activities. While for those developed on the passive margins, their formations are dominated by Cenozoic tectonics, sediment supply, and eustasy. The exogenic process is the main influencing factor.

Abundant information about tectonic evolution in the northeastern South China Sea margin is essentially important for understanding the evolution of the South China Sea. The deep reflection seismic profiles and wide-angle reflection seismic profiles across the northeastern South China Sea were collected, and the crustal thickness and high-velocity lower crustal thickness were extracted respectively. Combining with geological and geophysical information such as bathymetry, gravity and magnetic anomalies, and lithospheric rheology, the crustal thinning of the northeastern South China Sea, nature of the Luzon-Ryukyu Transform Plate Boundary and distribution of the high-velocity lower crust and its origins were discussed. The northeastern crust is unevenly thin in lateral and vertical, dominated with lower crust thinning, like in the Taixinan Basin. There are similar extremely thinned crusts in the Baiyun Sag, Xisha Trough and Zhongjiannan Basin. They are always conjugated with or adjacent to rigid blocks. We agree that lower crust flow and mantle upwell caused by the existence of rigid blocks during initiated breakup are responsible for locally extreme thinning of the crust. Both sides of the Luzon-Ryukyu Transform Plate Boundary are different in the bathymetry, Cenozoic reflections, gravity and magnetic anomalies. The LRTPB intersected high magnetic anomaly zone caused by Mesozoic with a large-angle, indicating the Luzon-Ryukyu Transform Plate Boundary may be a boundary fault converted from the Mesozoic Paleo-Tethys tectonic domain to the Pacific tectonic domain. The distribution range of the extensive HVLC in the northeastern margin consistent with post-rift igneous. Combining with distribution interval of ratios V_p/V_s of the high-velocity lower crust, It is suggested that the high-velocity lower crust primarily consists of mafic rock caused by multiple-epoch underplating.

By using the method of multi-index extension comprehensive evaluation, the various factors affecting the development and utilization grade of the inhabited islands were analyzed,the matter-element model of the comprehensive evaluation of the development and utilization grades of the inhabited island were established, and its correlation degree was calculated. Quantitative numerical evaluation results were obtained. Taking the four inhabited islands in Taizhou City, Zhejiang Province as an example, the results show that the evaluation of the exploitation and utilization level of the inhabited islands by this method is more objective and reasonable. It can be used as evaluation models of development and utilizing classification for the inhabited islands.

In order to objectively evaluate the management and control effect of marine ecological red line zone in China, the management and control evaluation system for marine ecological red line zone was established to evaluate the effect of Bohai Sea region and three provinces and one city (Shandong, Liaoning, Hebei and Tianjin), and timely to find the problems in the management and control. PSR model was used to evaluate the management and control effect of Bohai Sea marine ecological red line area, and empirical analysis was made on three provinces and one city. The results show that in the overall situation, the management and control continues to improve in Bohai Sea, the stability of pressure layer is poor, the state layer is constantly optimized, and the response layer is greatly affected by the policy. Among them, the pressure layer of Bohai Sea is mainly affected by the population and industry of Shandong Province, the status layer is mainly derived from the rich natural resources of Liaoning Province, and the response layer is mainly derived from the efforts made by Shandong Province for ecological security. Finally, according to the current situation of marine ecological environment in various provinces and cities, management suggestions are put forward from the aspects of management and control as well as the restricted development in the marine protected areas.

To evaluate the effects of hypersalinity and its fluctuation on the photo-physiological and the performances of marine “green tide” algae on salt tolerance, Ulva prolifera was selected as the experimental material. We set up three salinity conditions: salinity 25 as control (CK); treatment 1 (T1), salinity 30 for 3 d, then increased to salinity 35; treatment 2 (T2), salinity 35 for 6 d. The relative growth rate, the content of photosynthetic pigments, the photosynthetic and dark respiration rates and the gene expression levels of ribulose-1, 5-bisphosphate carboxylase/oxygenase (Rubisco) and calmodulin (CaM) were measured. The results showed that compared with control groups, hypersalinity significantly inhibited the relative growth rates and photo-physiological performances. Both T1, T2 treatments inhibited the relative growth rates and net photosynthesis rates of U. prolifera, and the inhibition effects of T2 was much stronger than that of the former one. The effect of hypersalinity stress on the dark respiration rate was not significant, which also had no significant effect on the content of photosynthetic pigments and their ratio of photosynthetic pigments. However, the dark respiration rate was significantly increased and photosynthetic pigments was significantly decreased along with the algae grow up. And the gene expression levels of rbcL and cam were also affected by hypersalinity. U. prolifera cultured in T1 treatment showed better resistance to hypersalinity than T2 treatment after 3 d and 6 d. It showed that U. prolifera could adapt to hypersalinity when the salinity was increased gradually. These results could explain the adaptation ability on hypersalinity stress of U. prolifera at the period of green tide formed and low tide.

According to the numerical forecast data of ECMWF in the past 10 years, we analyzed the spatial distribution of sea surface temperature, sea surface wind field and effective wave height of the four seasons and the whole year of the tuna purse seine fishery in the Western and Central Pacific Ocean, and studied the spatial and temporal variation characteristics using Empirical Orthogonal Function (EOF) and Empirical Mode Decomposition (EMD). Research shows that the spatial and temporal distributions of sea surface temperature, sea surface wind field, effective wave height have significant changes; the first, second, third modal variance contribution rates of sea surface temperature are 62.59%, 10.98%, 6.7%, and have 0.5 year, 1 year, 3 year cycle changes; the first, second, third modal variance contribution rates of sea surface wind field are 40.29%, 18.39%, 9.36%, and have 0.2-0.25 year, 0.5 year, 1 year cycle changes; the first, second, third modal variance contribution rates of effective wave height are 44.17%,17.35%, 10.96%, and have 0.2-0.3 year, 0.5-1 year, 1 year cycle changes.

chlorophyll a concentration is an important index of eutrophication. It becomes very necessary to timely and effectively monitor and evaluate the water chlorophyll a concentration for the environmental protection. Based on the satellite data from 2011 to 2016, the temporal and spatial distribution characteristics of the sea surface chlorophyll a concentration in the Beibu Gulf were analyzed. The results show that the chlorophyll a concentration in the Beibu Gulf has obvious monthly and seasonal variation, the monthly average chlorophyll a concentration reaches its peak in August and January, respectively, the average chlorophyll a concentration in the Beibu Gulf during winter and summer is higher than that during the spring and autumn, the chlorophyll a concentration in the Beibu Gulf sea surface begins to rise rapidly in summer, and the chlorophyll a concentration in the central and southern part of the Beibu Gulf slightly descend in autumn. In the spatial distribution, in the coastal waters of Beibu Gulf, the average chlorophyll a concentration is relatively higher, the high value area of chlorophyll a concentration is basically in the shallow water area along the western coast of the Leizhou Peninsula in the northern part of the Beibu Gulf, while the low value area lies in center and the deep waters of the south of the Gulf.