In recent years, artificial islands have been widely constructed in coastal areas to quickly obtain high-quality land resources. However, the construction of artificial islands may exert substantial effects on the distribution patterns and transport processes of offshore seabed sediments. To understand the changes and transport characteristics of sediments after the construction of artificial islands, this article focuses on the impact of Nanhaimingzhu (NHMZ) artificial island on the properties and distribution of offshore seabed sediments in the Haikou Bay. With surface sediments sampled respectively in the offshore of the Haikou Bay before and after the construction of NHMZ artificial island, the changes in sediment characteristics were analyzed. The impact of NHMZ artificial island on the surface sediments properties and transport trend in the Haikou Bay was discussed with sedimentary dynamic and grain size trends analysis. The results showed that the surface sediment properties changed significantly after the construction of NHMZ artificial island, with the fine-grained sediment composition increased, grain size decreased and the sorting worsen. It was found that the weakening of sedimentary dynamic conditions in the Haikou Bay caused by NHMZ artificial island was an important factor for the changes in seabed surface sediments grain size and the trend of sediment transport.

Morphodynamic relationships between fringing reefs and back-reef beach play key roles in understanding the evolution of coral coasts. The fringing reef coasts of Leizhou Peninsula, in Xiluo Port, Xuwen, are taken as the research object in this paper. RTK-GPS and unmanned-surface-vessel are used to measure and analyze the topography of the beach profile and reef as well as the sediment sampling in beach. FUNWAVE-TVD is used to simulate and analyze the hydrodynamic process of short wave and infragravity wave cross the different reef. The results show that the reef topography in the study area has significant effects on the morphology of back-reef beach. Whether the nearshore wave energy dominated by the short wave band or the infragravity band is controlled by the topography. In the narrow reef, there is a predominance of infragravity energy near the back-reef beach. The dominated wave band in the nearshore wave energy is the main factor shape the back-reef beach equilibrium profile. However, the beach equilibrium profile model of coral coast proposed by Muñóz-Pérez did not take this factor into account, it need to further research.

Three monthly altimeter datasets of the Arctic Ocean are compared in this paper. The datasets provided by the Centre for Polar Observation and Modelling (CPOM) and Technical University of Denmark (DTU) are found to be consistent with each other and due to their high spapce coverage, are more suitable for the study of the sea level variation in the Arctic Ocean, the former is better in terms of spatial resolution, smoothness, and consistency with the tide gauge observation. Based on the data of both altimeter and tide gauge, the temporal and spatial characteristics of sea level in the Arctic Ocean are analyzed and the results show that the climatological sea level in the Arctic Ocean is represented by the striking contrast between the high values in the Canadian Basin and low values in the Eurasian basin. The variation of sea level in the Arctic Ocean is dominated by the seasonal variability and low-frequency variability associated with the Arctic Oscillation, large amplitudes of both the seasonal and inter-annual sea level variability are found in the Canadian Basin, and large seasonal variability occurs along the coast of Russia. During the period 2003−2014, the mean sea level of the Arctic Ocean is rising with the largest rising rate is found in the Canadian Basin, while the sea level in the Russian coastal area is declining slightly. It is also found that large uncertainty exists in the altimetry products of the Canadian Basin and the coast of Russia, as the difference both between altimetry products and between altimeter and tide gauge data cannot be ignored, data in these areas should be used with caution.

In view of the prominent partial wind effect on islands, the wind profiles of idealized islands topography with three slopes are fitted by means of boundary layer wind tunnel test and numerical simulation. The difference factor is defined to describe the variation of wind profile, the distribution of maximum acceleration ratio and difference factor on the windward side of islands is studied by numerical simulation, and the effects of island slope and height on maximum acceleration ratio and difference factor are discussed comprehensively. Moreover, based on the wind tunnel data, the along-wind, cross-wind and vertical turbulence intensity and gust factor of the windward and leeward sides are studied. The results show that the numerical simulation is basically consistent with the wind tunnel test results and the wind profile exponent (α) is smaller on the windward side of islands. It also shows acceleration effect near the top of the island is particularly obvious and its maximum acceleration ratio is between 0.4 and 1.0. Moreover, the difference factor at the hillside is lower, and with the increase of the angle of the island ridge, the position where the difference factor is 0 tends to approach the slope toe. As the island slope increases to 25°, the maximum acceleration ratio and difference factor on the 0° island ridge are large. The distribution of three-dimensional turbulence intensity on the windward side is relatively regular, while that on the leeward side is disordered especially in the range of 100 m away from the island’s surface. It is worth noting that the trends of gust factor and turbulence intensity are highly consistent.

Water transparency (Z_sd) is an important optical parameter for evaluating water quality. This paper tuned a remote sensing model for estimating Z_sd from MODIS (moderate resolution imaging spectroradiometer) data in the South Yellow Sea. This model was then used to analyze the spatial and temporal variations of Z_sd in the South Yellow Sea based long-term MODIS data in the past 20 years (2002–2020), and their driving factors were examined. The results show that the Z_sd estimation model has good accuracy with R², root mean square error and mean absolute percent error values of 0.91, 1.69 m and 25.1%, respectively. The Z_sd levels are generally high in the offshore but low in the coastal area. Meanwhile, Z_sd indicates high values in summer but low values in winter. In the past 20 years, Z_sd in the central South Yellow Sea, the southern South Yellow Sea and the Changjiang River Estuary showed slowly increase trends, while Z_sd in the Jiangsu coast was decreasing slowly. In general, the Z_sd is negatively driven by the concentration of suspended particulate matter, of which the influence is the greatest. In addition, sea surface temperature and solar radiation have positive driving effects on Z_sd, while wind speed has negative driving effect.

Based on the data of Philippine shallow strata profile, combined with the sample data and borehole data in this area, this paper has a preliminary understanding of the shallow sediment characteristics of Kyushu-Palau Ridge and the West Philippine Basin and Parisi Vera Basin adjacent to the ridge. There are generally three wave impedance interfaces below the seabed, and the reflection characteristics of the shallow stratum profile are divided into four basic types. The causes of the profile characteristics are preliminarily discussed. It is believed that the sediment supply, tectonic activities, topography and hydrodynamic conditions play an important role in the deep-water sedimentation during the sedimentation process. Besides being influenced by the main control factors, most of them are also superimposed with the transformation effects of various factors in the later period. In this paper, the sedimentary characteristics and controlling factors of shallow strata in Philippine Sea are analyzed, which can provide useful reference for further study of deep shallow sediments in Philippine Sea.

According to the bottom trawl survey data of fishery resources in the offshore waters of Shandong from 2016 to 2017, the spatial autocorrelation and spatial heterogeneity of demersal fish in the offshore waters of Shandong were examined by using spatial autocorrelation indices and variogram. The results showed that there were significant spatial aggregation patterns and spatial autocorrelation in the demersal fish in the offshore waters of Shandong. The spatial autocorrelations were strong in spring, summer and winter, and weak in autumn. From the perspective of spatial distribution, the areas of high relative abundance index of demersal fish were mainly located in the southern waters of Shandong in spring and summer, and areas of high relative abundance greatly decreased in autumn and winter, while the areas of low value were mainly in the Laizhou Bay and adjacent waters in four seasons. The parameters of variogram showed that there was a strong nugget effect in autumn, and the spatial heterogeneity of random part accounted for 76.0% of the total spatial heterogeneity. The spatial heterogeneity of random part in spring, summer and winter only accounted for 26.2%, 27.7% and 23.6% of the total spatial heterogeneity. In the spatial autocorrelation and spatial heterogeneity of demersal fish showed seasonal variation in the offshore waters of Shandong, which was to some extent related with changes in environmental factors such as water temperature.

According to the data collected in April (spring) and October (autumn) of 2018 in the eastern sea area of Zhoushan Islands (29°10′25.54′′−30°45′00′′N, 122°53′3.88′′−124°48′28.31′′E) based on the crab data obtained from bottom trawl survey of fishery resources, the community structure characteristics of crab resources such as species composition, dominant species and biodiversity were studied, and the relationship between crab quantity distribution and community structure and environmental factors such as temperature and salinity was analyzed. The results show that there are 40 species of crabs in spring and autumn, belonging to 23 genera and 12 families; among them, the dominant species in spring is Charybdis bimaculatus, and in autumn are C. bimaculatus and Portunus trituberculatus; the richness index (D) and Shannon Wiener-diversity index (H′) in autumn are higher than those in spring, while Pielou evenness index (J') is similar in spring and autumn; independent sample t-test show that there is significant difference between spring and autumn; according to cluster analysis and non metric multi-dimensional scaling analysis, spring can be divided into four communities, and autumn can be divided into four communities; canonical correspondence analysis show that bottom water temperature and surface salinity are the main environmental factors affecting the community structure and quantity distribution of crabs in the investigated sea area.

Corals are one of the carriers for recording information about changes in the marine environment. For example, determining U/Ca to reconstruction of sea water temperature or measure the Th/U isotopic ratio for dating to reconstruction sea level etc. However, measuring the U and Th contents and isotopic ratio of corals is a prerequisite for extracting the recorded marine environmental change information, the difficulty lies in the separation of Ca matrix and enrichment and purification of trace U and Th. Based on this, this study modified the pretreatment method of separation and purification U and Th with single column stage of UTEVA resin, and then combined with high resolution inductively coupled plasma mass spectrometry to determine U and Th contents of corals. The results demonstrate that the HNO₃ medium concentration decrease from 3 mol/L to 2 mol/L will not affect the absorption efficiency of U and Th; 2 mL Milli-Q water can completely elute U, which significantly reduces the procedure blank value of the entire process of U; the improved method is used to determine the U and Th contents of three Hainan littoral corals (n=6, 1σ): U are (3.46±0.02)μg/g, (2.67±0.05)μg/g, (2.15±0.07)μg/g, respectively, Th are (10.12±0.24)ng/g, (4.82±0.10)ng/g, (5.65±0.12)ng/g, respectively; and the determination accuracy is below 3.3%, recovery rate of standard addition of U, Th are 97.9%–100.9%, 97.3%–99.7%, respectively. The method has high accuracy and good precision. This study provides a more accurate, convenient and rapid experimental method for the analysis of U and Th content and isotopic ratio in corals and other carbonate samples.

Cynoglossus semilaevis as a representative species of Pleuronectiformes, is an important marine economic fish in Chinese coastal areas. The abnormal body color of C. semilaevis has been perplexing the practitioners for a long time. There are many reasons leading to abnormal body color, among which the genetic factors are thought to be the most fundamental reasons. The present researches on hypermelanosis of the blind side of C. semilaevis mainly focus on environment, nutrition, physiology, cloning of known pigmental genes and so on, while the digging of new funtional genes is still lacking. In this study, skin samples with different colors of C. semilaevis are selected for transcriptome sequencing. Through GO and KEGG functional enrichment and comparative analysis of different genes, differential expressed genes are screened in six melanogenesis-related KEGG pathways and the top ten genes are verified by qPCR. In this study, we find five functional genes with significant changes in the hypermelanotic skin on the blind side of C. semilaevis, which refer to txndc, alox15b, ptgs2, ptgis, and atp1a2a (p<0.05). The expression levels of txndc, alox15b, ptgs2, and ptgis genes in the melanization group are higher than those in the control group. In terms of function, three of these five genes are related to arachidonic acid (AA) to some extent. This provides theoretical support for the hypothesis that nutritional regulation related to unsaturated fatty acids may be involved in the molecular mechanism of abnormal body color in C. semilaevis.