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.

Based on the Typhoon Hato in 2017, the Himawari-8 AHI infrared radiance data are assimilated under the clear-sky condition in WRFDA system to investigate its impact on the typhoon forecast. The structure, strength, as well as the track forecasts are also studied for the Typhoon Hato. The results show that the clear-sky assimilation of Himawari-8 infrared radiance data provides obvious increment of cyclonic winds in the typhoon core and an obvious increase of typhoon in background field. Compared with the control experiment without assimilating Himawari-8 AHI infrared radiance data, the experiment that assimilates Himawari-8 AHI data strengthens the wind field of Typhoon Hato, 500 hPa pressure field analysis, and typhoon cyclonic circulation. In addition, the AHI radiance assimilation further improves the forecast of track, minimum sea level pressure, and the maximum wind speed of the Typhoon Hato. The average track error, the precipitation distribution, the root mean square error against the conventional data are also improved.

Eddies in the Southern Ocean play a critical role in transporting material and heat across fronts. Scotia Sea is located downstream of the Drake Passage and is an important economic fishery area, hence study on the distribution and role of eddies in this region is of urgent importance. Based on satellite remote sensing data from 2005 to 2019, the characteristics of eddies are statistically calculated, including radius, propagation distance, and lifespan. Their spatial distribution, cross-front movement, and movement characteristics are also analyzed. Meanwhile, the internal hydrographic characteristics of eddies are analyzed based on profile data. Results show that about 92% of eddies have a lifespan shorter than 30 d, with an average radius between 10 km and 30 km. The generating location of eddies are mainly near Polar Front (PF), Southern ACC Front (SACCF), and Sub-antarctic Front (SAF), corresponding to the bottom depth ranging 3 000 m to 5 000 m. Large values of eddy kinetic energy (EKE) concentrate between PF and SAF due to the obstruction of the submarine ridges, and EKE reaches a significant positive anomaly after 2016. The number of equator-ward eddies is dominant in the eddies across PF and SACCF, with most being cyclonic eddies. Anticyclonic eddies are dominant in poleward eddies. The internal hydrographic structures of eddies show that temperature and salinity are relatively low in the subsurface layer of the cold eddies, consistent with the characteristics of water masses at high latitudes. While they are relatively high in the subsurface layer of the warm eddies. It suggests that cold eddies may carry water from high latitudes to low latitudes and warm eddies may carry seawater from low latitudes to high latitudes. This study provides a basis for further understanding of the characteristics of eddies in the Scotia Sea and their effects on the distribution of biological populations and material and energy transport.

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.

We presented an optimized and purification procedure as well as an analytical method for Cu and Zn isotopes measurement in marine sediments. We reported Cu and Zn isotope of 5 samples in a sediment cores and 20 surface sediment samples in the northern and southern Okinawa Trough. Anion exchange resin (AG MP-1M) was applied to separate matrix elements of sediment samples from Cu, Fe and Zn using 8.2 mol/L HCl+0.01% HF+0.001% H₂O₂, 2 mol/L HCl+0.001% H₂O₂ and 0.5 mol/L HNO₃ as eluents. The recoveries of Cu and Zn were both close to 100%. Cu and Zn isotopes were measured on a Nu Plasma multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS). Instrumental mass bias was corrected using a combination of sample-standard bracketing and internal spiking. The long-term reproducibilities were 0.11‰ (2SD) for Cu isotopes and 0.09‰ (2SD) for Zn isotopes. The δ⁶⁶Zn of surface sediments varies from 0.07‰ to 0.67‰, with an average of 0.31‰ ± 0.32‰ (2SD); the δ⁶⁵Cu of surface sediments ranges from −2.26‰ to −0.52‰, with an average of −1.21‰ ± 0.55‰ (2SD). The results show that Cu and Zn isotopes of surface sediments in the Okinawa Trough varies widely, meanwhile, Cu and Zn isotopes in sediment core varies with depth.

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.

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.

In this study, we used stable isotope technology to analyze different species (fish, crustaceans, cephalopods, benthos, etc.) collected in spring, summer and autumn in the coastal waters of Jiangsu Province. We used SIBER model to calculate the trophic niche of consumers, and calculated the quantitative indicators of six metrics in different seasons. The results showed that there were no significant differences in δ¹³C and nitrogen δ¹⁵N values among three seasons (p>0.05). In spring, the δ¹³C values ranged from −24.47‰ to −14.50‰, the δ¹⁵N values ranged from 6.86‰ to (14.98±0.49)‰, and the trophic level ranged from 1.52 to 4.28±0.17. In summer, the δ¹³C values ranged from −19.86‰ to −14.44‰, the δ¹⁵N values ranged from 5.79‰ to (12.54±3.50)‰, and the trophic level ranged from 1.25 to 3.52. In autumn, the δ¹³C values ranged from (−22.17±4.90)‰ to (−14.21±0.36)‰, the δ¹⁵N values ranged from 6.30‰ to (14.60±0.51)‰, and the trophic level ranged from 1.34 to 4.15±0.14. The structure of food web was stable in each season, and the trophic niche of some species overlaps in different degrees. In addition, the food sources are more extensive, and the trophic level and community diversity are higher in spring, the food sources of consumers are more abundant, but the degree of trophic niche differentiation is lower in summer, while in autumn, the structure of food web is relatively simple, but the distribution of trophic niche is wider.

Picasso clownfish is named for its disorderly and abstract distribution of white patches in its skin. At the same time, due to the irregular and scarce formation of white patches, it belongs to a valuable clownfish. Therefore, analyzing the formation mechanism of skin white spots in Picasso clownfish can provide a theoretical basis for the artificial breeding of Picasso clownfish. In this study, we sequences the transcriptome of the skin of three color blocks (black, yellow and white） in the same part of the body between the dorsal fin and hip fin of Picasso clownfish. The results show that there are a large number of differentially expressed genes (DEGs） in white skin compared with yellow and black skin. Among them, the genes in the signal pathways related to melanin production (such as melanin production, hedgehog and Wnt signal pathways） show a downward trend in white skin tissue. The expression of upstream regulatory genes (such as ednrba and mitfa） decrease gradually from black to yellow to white skin tissue, but the expression of downstream core genes involved in melanin synthesis (including Tyr, tyrp1b and dct） decreases significantly in white skin assembly. Finally, the validity of transcriptome data is verified by fluorescence quantitative PCR. The results of this study will provide a theoretical basis for future people to interfere with gene expression to regulate clownfish body color.