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Volume 38 ， Issue 4 ， 2020
- Abstract：The Indo-Pacific convergence region is the best target to solve the two remaining challenges of the plate tectonics theory, i.e., subduction initiation and the driving force of plate tectonics. Recent studies proposed that the Izu-Bonin subduction initiation belongs to spontaneous initiation, which implies that it started from extension, followed by low angle subduction. Numerical geodynamic modeling suggests that the initiation of plate subduction likely occurred along a transform fault, which put the young spreading ridge in direct contact with old oceanic crust. This, however, does not explain the simultaneous subduction initiation in the west Pacific region in the Cenozoic. Namely, the subduction initiations in the Izu-BoninMariana, the Aleutian, and the Tonga-Kermadec trenches are associated with oceanic crusts of different ages, yet they occurred at roughly the same time, suggesting that they were all triggered by a major change in the Pacific plate. Moreover, low angle subduction induces compression rather than extension, which requires external compression forces. Given that the famous Hawaiian-Emperor bending occurred roughly at the same time with the onset of westward subductions in the west Pacific, we propose that these Cenozoic subductions were initiated by the steering of the Pacific plate, which are classified as induced initiation. Induced subduction initiation usually occurs in young ocean basins, forming single-track subduction. The closures of Neo-Tethys Oceans were likely triggered by plumes in the south, forming northward subductions. Interestingly, the Indian plate kept on moving northward more than 50 Ma after the collision between the Indian and Eurasian continents and the break-off of the subducted oceanic slab attached to it. This strongly suggests that slab pull is not the main driving force of plate tectonics, whereas slab sliding is.Keywords：plate tectonics;subduction initiation;drifting history;Pacific plate;Indian plate;slab sliding5|4|14Updated：2023-04-27
- Abstract：Smart coating for corrosion protection of metal materials (steel, magnesium, aluminum and their alloys) has drawn great attention because of their capacity to prevent crack propagation in the protective coating by releasing functional molecules (healing agents or corrosion inhibitors) on demand from delivery vehicle, that is, micro/nanocontainer made up of a shell and core material or a coating layer, in a controllable manner. Herein, we summarize the recent achievements during the last 10 years in the field of the micro/nanocontainer with different types of stimuli-responsive properties, i.e., pH, electrochemical potential, redox, aggressive corrosive ions, heat, light, magnetic field, and mechanical impact, for smart anticorrosion coating. The state-of-the-art design and fabrication of micro/nanocontainer are emphasized with detailed examples.Keywords：corrosion protection;micro/nanocontainer;stimuli-responsive;smart anticorrosion coating4|0|0Updated：2023-04-27
- Abstract：Corrosion protection has become an important issue as the amount of infrastructure construction in marine environment increased. Photocathodic protection is a promising method to reduce the corrosion of metals, and titanium dioxide (TiO2) is the most widely used photoanode. This review summarizes the progress in TiO2 photogenerated protection in recent years. Different types of semiconductors, including sulfides, metals, metal oxides, polymers, and other materials, are used to design and modify TiO2. The strategy to dramatically improve the efficiency of photoactivity is proposed, and the mechanism is investigated in detail. Characterization methods are also introduced, including morphology testing, light absorption, photoelectrochemistry, and protected metal observation. This review aims to provide a comprehensive overview of TiO2 development and guide photocathodic protection.Keywords：photocathodic protection;corrosion;titanium dioxide (TiO2);photoelectrochemistry;metal4|0|2Updated：2023-04-27
- Abstract：The Western Tropical Pacific (WTP) Ocean holds the largest area of warm water (>28℃) in the world ocean referred to as the Western Pacific Warm Pool (WPWP), which modulates the regional and global climate through strong atmospheric convection and its variability. The WTP is unique in terms of its complex 3-D ocean circulation system and intensive multiscale variability, making it crucial in the water and energy cycle of the global ocean. Great advances have been made in understanding the complexity of the WTP ocean circulation and associated climate impact by the international scientific community since the 1960s through field experiments. In this study, we review the evolving insight to the 3-D structure and multi-scale variability of the ocean circulation in the WTP and their climatic impacts based on in-situ ocean observations in the past decades, with emphasis on the achievements since 2000. The challenges and open questions remaining are reviewed as well as future plan for international study of the WTP ocean circulation and climate.Keywords：Western Tropical Pacific (WTP);ocean circulation;climate;observation4|0|5Updated：2023-04-27
- Abstract：El Niño-Southern Oscillation (ENSO) is the strongest interannual signal that is produced by basinscale processes in the tropical Pacific, with significant effects on weather and climate worldwide. In the past, extensive and intensive international efforts have been devoted to coupled model developments for ENSO studies. A hierarchy of coupled ocean-atmosphere models has been formulated; in terms of their complexity, they can be categorized into intermediate coupled models (ICMs), hybrid coupled models (HCMs), and fully coupled general circulation models (CGCMs). ENSO modeling has made significant progress over the past decades, reaching a stage where coupled models can now be used to successfully predict ENSO events 6 months to one year in advance. Meanwhile, ENSO exhibits great diversity and complexity as observed in nature, which still cannot be adequately captured by current state-of-the-art coupled models, presenting a challenge to ENSO modeling. We primarily reviewed the long-term efforts in ENSO modeling continually and steadily made at different institutions in China; some selected representative examples are presented here to review the current status of ENSO model developments and applications, which have been actively pursued with noticeable progress being made recently. As ENSO simulations are very sensitive to model formulations and process representations etc., dedicated efforts have been devoted to ENSO model developments and improvements. Now, different ocean-atmosphere coupled models have been available in China, which exhibit good model performances and have already had a variety of applications to climate modeling, including the Coupled Model Intercomparison Project Phase 6 (CMIP6). Nevertheless, large biases and uncertainties still exist in ENSO simulations and predictions, and there are clear rooms for their improvements, which are still an active area of researches and applications. Here, model performances of ENSO simulations are assessed in terms of advantages and disadvantages with these differently formulated coupled models, pinpointing to the areas where they need to be further improved for ENSO studies. These analyses provide valuable guidance for future improvements in ENSO simulations and predictions.Keywords：El Niño-Southern Oscillation (ENSO);coupled ocean-atmosphere models;simulations and predictions;model biases and uncertainties4|0|0Updated：2023-04-27
- Abstract：In comparison with seasonal sea ice (first-year ice, FY ice), multiyear (MY) sea ice is thicker and has more opportunity to survive through the summer melting seasons. Therefore, the variability of wintertime MY ice plays a vital role in modulating the variations in the Arctic sea ice minimum extent during the following summer. As a response, the ice-ocean-atmosphere interactions may be significantly affected by the variations in the MY ice cover. Satellite observations are characterized by their capability to capture the spatiotemporal changes of Arctic sea ice. During the recent decades, many active and passive sensors onboard a variety of satellites (QuikSCAT, ASCAT, SSMIS, ICESat, CryoSat-2, etc.) have been used to monitor the dramatic loss of Arctic MY ice. The main objective of this study is to outline the advances and remaining challenges in monitoring the MY ice changes through the utilization of multiple satellite observations. We summarize the primary satellite data sources that are used to identify MY ice. The methodology to classify MY ice and derive MY ice concentration is reviewed. The interannual variability and trends in the MY ice time series in terms of coverage, thickness, volume, and age composition are evaluated. The potential causes associated with the observed Arctic MY ice loss are outlined, which are primarily related to the export and melting mechanisms. In addition, the causes to the MY ice depletion from the perspective of the oceanic water inflow from Pacific and Atlantic Oceans and the water vapor intrusion, as well as the roles of synoptic weather, are analyzed. The remaining challenges and possible upcoming research subjects in detecting the rapidly changing Arctic MY ice using the combined application of multisource remote sensing techniques are discussed. Moreover, some suggestions for the future application of satellite observations on the investigations of MY ice cover changes are proposed.Keywords：multiyear sea ice;Arctic Ocean;satellite observation5|0|5Updated：2023-04-27
- Abstract：Seafloor hydrothermal vent fields (SHVFs) are located in the mid-ocean ridge (MOR), backarc basin (BAB), island arc and hot-spot environments and hosted mainly by ultramafic, mafic, felsic rocks, and sediments. The hydrothermal vent fluids of SHVFs have low oxygen, abnormal pH and temperature, numerous toxic compounds, and inorganic energy sources, such as sulfuric compounds, methane, and hydrogen. The geological, physical, and chemical characteristics of SHVFs provide important clues to understanding the formation and evolution of seafloor hydrothermal systems, leading to the determination of metal sources and the reconstruction of the physicochemical conditions of metallogenesis. Over the past two decades, we studied the geological settings, volcanic rocks, and hydrothermal products of SHVFs and drawn new conclusions in these areas, including:1) the hydrothermal plumes in the Okinawa Trough are affected by the Kuroshio current; 2) S and Pb in the hydrothermal sulfides from MOR are mainly derived from their host igneous rocks; 3) Re and Os of vent fluids are more likely to be incorporated into Fe- and Fe-Cu sulfide mineral facies, and Os is enriched under low-temperature (< 200℃) hydrothermal conditions in global SHVFs; 4) compared with low-temperature hydrothermal sulfides, sulfates, and opal minerals, high-temperature hydrothermal sulfides maintain the helium (He) isotopic composition of the primary vent fluid; 5) relatively low temperature (< 116℃), oxygenated, and acidic environment conditions are favorable for forming a native sulfur chimney, and a "glue pudding" growth model can be used to understand the origin of native sulfur balls in the Kueishantao hydrothermal field; and 6) boron isotope from hydrothermal plumes and fluids can be used to describe their diffusive processes. The monitoring and understanding of the physical structure, chemical composition, geological processes, and diverse organism of subseafloor hydrothermal systems will be a future hot spot and frontier of submarine hydrothermal geology.Keywords：vent fields;hydrothermal products;volcanic rocks;vent organisms;seafloor hydrothermal systems4|2|5Updated：2023-04-27
- Abstract：Saccharina japonica is one of the most important economic brown seaweeds. It is intensively cultivated on large scales in a number of Asian countries. The current annual, global production is about 8 million tons valued as about 4 million US dollars. Considerable efforts have been made to S. japonica in China since the 1950s on its cultivation. To further advance the cultivation of this species, detailed research of genetics and breeding studies are required. Recently, with the advancement of sequencing techniques, the genomics and comparative transcriptomics data were yielded, and quantitative trait locus (QTL) mapping has been conducted, along with genetic linkage maps constructed to this species. New strains have been bred and selected, with better characteristics, e.g. higher seawater temperature resistances and higher yields. In this review, we present the current status of genetic and breeding studies that have been performed to S. japonica in China, and provide guidelines for future developments in the areas of genetic selection and breeding for this species.Keywords：Saccaharina japonica;next generation sequencing;genomics;transcriptomics;quantitative trait locus (QTL) mapping;DNA markers;linkage map;breeding;hybridization;cytogenetics4|0|2Updated：2023-04-27
Review
- Abstract：Every institute in the world has its own history, culture, and legacy that show its unique characters. As an oldest, largest, and one of the most advanced institute in marine sciences in China, the Institute of Oceanology, Chinese Academy of Sciences (IOCAS) was established by her founders in 1950 and cherished by her successors ever since. IOCAS has undertaken her own development roadmap over the last seventy years. Many people know its history, achievements, and contributions in marine sciences, but few would know the stories behind the success. This paper intends to reveal the driven factors pushing the institute forward in the past, present, and future.Keywords：mariculture;ocean health;deep sea;Institute of Oceanology, Chinese Academy of Sciences (IOCAS)5|3|0Updated：2023-04-27
Preface
- Abstract：Subsurface mooring allows researchers to measure the ocean properties such as water temperature, salinity, and velocity at several depths of the water column for a long period. Traditional subsurface mooring can release data only after recovered, which constrains the usage of the subsurface and deep layer data in the ocean and climate predictions. Recently, we developed a new real-time subsurface mooring (RTSM). Velocity profiles over upper 1 000 m depth and layered data from sensors up to 5 000 m depth can be realtime transmitted to the small surface buoy through underwater acoustic communication and then to the office through Beidou or Iridium satellite. To verify and refine their design and data transmission process, we deployed more than 30 sets of RTSMs in the western Pacific to do a 1-year continuous run during 2016-2018. The continuous running period of RTSM in a 1-year cycle can reach more than 260 days on average, and more than 95% of observed data can be successfully transmitted back to the office. Compared to the widely-used inductive coupling communication, wireless acoustic communication has been shown more applicable to the underwater sensor network with large depth intervals and long transmission distance to the surface.Keywords：real-time subsurface mooring;underwater acoustic communication;Western Pacific;ocean and climate predictions4|0|2Updated：2023-04-27
- Abstract：Near-inertial oscillation is an important physical process transferring surface wind energy into deep ocean. We investigated the near-inertial kinetic energy (NIKE) variability using acoustic Doppler current profiler measurements from a mooring array deployed in the tropical western Pacific Ocean along 130°E at 8.5°N, 11°N, 12.6°N, 15°N, and 17.5°N from September 2015 to January 2018. Spatial features, decay timescales, and significant seasonal variability of the observed NIKE were described. At the mooring sites of 17.5°N, 15°N, and 12.6°N, the NIKE peaks occurred in boreal autumn and the NIKE troughs were observed in boreal spring. By contrast, the NIKE at 11°N and 8.5°N showed peaks in winter and troughs in summer. Tropical cyclones and strong wind events played an important role in the emergence of high-NIKE events and explained the seasonality and latitudinal characteristics of the observed NIKE.Keywords：near-inertial kinetic energy;Western Pacific Ocean;tropical cyclones;mooring array;seasonal variability4|0|3Updated：2023-04-27
- Abstract：We investigated the intraseasonal variability of equatorial Pacific subsurface temperature and its relationship with El Niño-Southern Oscillation (ENSO) using Self-Organizing Maps (SOM) analysis. Variation in intraseasonal subsurface temperature is mainly found along the thermocline. The SOM patterns concentrate in basin-wide seesaw or sandwich structures along an east-west axis. Both the seesaw and sandwich SOM patterns oscillate with periods of 55 to 90 days, with the sequence of them showing features of equatorial intraseasonal Kelvin wave, and have marked interannual variations in their occurrence frequencies. Further examination shows that the interannual variability of the SOM patterns is closely related to ENSO; and maxima in composite interannual variability of the SOM patterns are located in the central Pacific during CP El Niño and in the eastern Pacific during EP El Niño. These results imply that some of the ENSO forcing is manifested through changes in the occurrence frequency of intraseasonal patterns, in which the change of the intraseasonal Kelvin wave plays an important role.Keywords：intraseasonal variability;equatorial Pacific;El Ni?o-Southern Oscillation (ENSO);SelfOrganizing Maps (SOM)4|0|0Updated：2023-04-27
- Abstract：The equatorial wave dynamics of interannual sea level variations between 2014/2015 and 2015/2016 El Niño events are compared using the Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics Climate Ocean Model (LICOM) forced by the National Centers for Environmental Prediction (NCEP) reanalysis Ⅰ wind stress and heat flux during 2000-2015. In addition, the LICOM can reproduce the interannual variability of sea surface temperature anomalies (SSTA) and sea level anomalies (SLA) along the equator over the Pacific Ocean in comparison with the Hadley center and altimetric data well. We extracted the equatorial wave coefficients of LICOM simulation to get the contribution to SLA by multiplying the meridional wave structure. During 2014/2015 El Niño event, upwelling equatorial Kelvin waves from the western boundary in April 2014 reach the eastern Pacific Ocean, which weakened SLA in the eastern Pacific Ocean. However, no upwelling equatorial Kelvin waves from the western boundary of the Pacific Ocean could reach the eastern boundary during the 2015/2016 El Niño event. Linear wave model results also demonstrate that upwelling equatorial Kelvin waves in both 2014/2015 and 2015/2016 from the western boundary can reach the eastern boundary. However, the contribution from stronger westerly anomalies forced downwelling equatorial Kelvin waves overwhelmed that from the upwelling equatorial Kelvin waves from the western boundary in 2015. Therefore, the western boundary reflection and weak westerly wind burst inhibited the growth of the 2014/2015 El Niño event. The disclosed equatorial wave dynamics are important to the simulation and prediction of ENSO events in future studies.Keywords：Pacific Ocean;equatorial waves;western boundary reflection;El Ni?o6|0|0Updated：2023-04-27
- Abstract：Based on field hydrological, microstructural, and shipboard Acoustic Doppler Current Profiler data, we quantified the spatial and temporal variability of turbulent mixing in the near-field Changjiang (Yangtze) River plume. The surface dissipation rate (ε) changed by three orders of magnitude from near-field (10-4 W/kg) to far-field (10-7 W/kg) plumes, indicating a decrease with distance from the river mouth. Below the river plume, ε changed with depth to 10-8 W/kg, and increased to 10-6 W/kg at the layer where the Taiwan Warm Current (TWC) intruded. Thus, ε in the near-field plume showed three layers:surface layer in the river plume, middle layer, and lower TWC layer. In the river plume, the strongest ε and turbulent diffusivity (Kz) were greater than 10-4 W/kg and 10-2 m2/s, respectively, during strong ebb tides. A three-orders-of-magnitude change in ε and Kz was observed in the tidal cycle. The depth of the halocline changed with tidal cycles, and stratification (N2) varied by one order of magnitude. Stratification in the TWC layer followed the distribution of the halocline, which is opposite to the dissipation structure. Tidal currents led to intrusion and turbulent mixing in the TWC layer. During ebb tides, ε and Kz were as strong as those measured in the river plume, but did not last as long. The structure of the velocity shear was similar to the dissipation rate in both the river plume and TWC layer, whereas the velocity shear in the TWC layer did not match the stratification structure. In the high dissipation rate area, the gradient Richardson number was smaller than the critical value (Rig < 1/4). The Rig structure was consistent with shear and dissipation distributions, indicating that turbulent mixing in the near-field plume was controlled by a combination of shear induced by the discharged river flow and tidal current.Keywords：Changjiang River;near-field plume;turbulent mixing observation;microstructure4|0|1Updated：2023-04-27
Physics
- Abstract：Detrital sediments derived from the Philippine Islands are one of the main sources of deep-sea sediments in the western Philippine Sea. However, systematic research on their characteristics and transport mechanisms are lacking. We used parametric end-member analysis to quantitatively partition the grain size of detrital sediments in core MD06-3052 from the Bicol Shelf in the western Philippine Sea; three endmembers EM1, EM2, and EM3, whose respective modes were at 2, 10, and 45 μm, were separated. We also measured the Sr and Nd isotopic compositions of different size fractions (< 4 and >20 μm) of the detrital sediments and the results showed that the detrital sediments mainly originate from the Philippine Islands. Components EM1 and EM2 are transported to the Bicol Shelf mainly by surface and bottom currents from the islands, and component EM3 is delivered by gravity flow from the exposed shelf during low sea-level stands. The content of the total detrital fraction and the three end-members, as well as the mass accumulation rates (MARs) of the coarse detritus (EM2 and EM3), were considerably higher during glacial periods (40-14 ka and 150-130 ka) than during other intervals; the glacials corresponded to a low sea level, while the MAR of the fine detritus (EM1) did not increase remarkably during 40-14 ka. We therefore concluded that the input of coarse detritus to the Bicol Shelf from the islands was mainly controlled by sea-level change. Variations of the input of fine-grained detritus (EM1) was influenced not only by sea level but also by ocean currents and regional precipitation. Overall, our results help understand "source-to-sink" processes in the western Pacific marginal seas and their response to global change.Keywords：Bicol Shelf;late Pleistocene;grain size;sea level change6|0|0Updated：2023-04-27
- Abstract：The South Yellow Sea Basin (SYSB) has multiple sets of proven source rocks and good hydrocarbon prospects, but no industrial oil and gas has been explored at present. To solve this puzzle for petroleum geologists, we systematically investigated the marine hydrocarbon geological conditions based on cores and testing data from borehole CSDP-2, the first exploration well with continuous coring in SYSB. The qualities of source rocks are evaluated in detail according to organic matter abundance, type, and maturity. The reservoir characterization mainly includes porosity, permeability, and reservoir space. Displacement pressure test and stratum thickness are the main foundations for defining the caprocks. Then, the oil-source rock correlation in the Permian and stratum model are analyzed to determine the favorable source-reservoir-caprock assemblages. The results show that three sets of effective source rocks (the Lower Triassic, Upper Permian, and Lower Permian), two sets of tight sandstone reservoirs (the Upper Permian and Lower Silurian-Upper Devonian), and two sets of caprocks (the Lower Triassic and Carboniferous) combine to constitute the hydrocarbon reservoir-forming assemblages of "lower-generation and upper-accumulation" and "self-generation and self-accumulation", thus laying a solid foundation for promising petroleum prospects. The three sets of marine source rocks are characterized by successive generation and expulsion stages, which guarantees multistage hydrocarbon accumulation. Another three sets of continental source rocks distributed across the Middle Jurassic, Upper Cretaceous, and Paleogene depression areas, especially in the Northern Depression, may supplement some hydrocarbons for the Central Uplift through faults and the Indosinian unconformity. The favorable Permian exploration strata have been identified in the Central Uplift of SYSB. First, the Lower Permian and Upper Permian source rocks with high organic matter abundance and high thermal maturity supply sufficient hydrocarbons. Secondly, the interbedding relationship between the source rocks and sandstones in the Upper Permian strata ensures that hydrocarbons have been migrated into the nearby Upper Permian sandstones, reflecting near-source hydrocarbon accumulation. Finally, the good sealing property of the Lower Triassic Qinglong Formation caprocks plays an indispensable role in hydrocarbon preservation of the Permian reservoirs. This conclusion is supported by direct oil shows, gas logging anomalous layers, and hydrocarbon-bearing fluid inclusions.Keywords：hydrocarbon geological conditions;near-source accumulation;relay hydrocarbon generation;multistage accumulation;favorable Permian;South Yellow Sea Basin;borehole CSDP-24|0|4Updated：2023-04-27
- Abstract：New acquired and reprocessed three-dimensional (3D) seismic data were used to delineate the distribution and characterization of bottom simulating reflections (BSRs) in the Chaoshan Sag, in the eastern part of Dongsha Island, South China Sea. Three submarine canyons with different scales were interpreted from the 3D seismic data, displaying three stages of canyon development and are related with the variation of BSR. Abundant faults were identified from the coherence and ant-tracing attributions extracted from 3D seismic data, which provide the evidence for fluid migration from deeper sediments to the gas hydrate stability zone (GHSZ). The uplift of Dongsha Island created a large number of faults and leads to the increased seafloor erosion. The erosion caused the cooling of the seafloor sediments and deepening of the base of the gas hydrate stability zone, which is attributed to the presence of paleo-BSR and BSR downward shift in the study area. Hence, methane gas may be released during the BSR resetting and gas hydrate dissociation related with seafloor erosion.Keywords：bottom simulating reflections (BSRs);downward shift;seafloor erosion;gas hydrate dissociation6|0|9Updated：2023-04-27
- Abstract：The alkaline oceanic island basalts (OIBs) with under-saturated SiO2 and high contents of CaO and alkaline are usually attributed to mantle sources different from typical tholeiitic OIBs. Based on the results of high pressure and temperature experiment study, the genesis of silica under-saturated alkaline basaltic melts could be explained by the role of CO2, thus, the genetic relationship of alkaline basalts with CO2 has become a topic of relevance because it is closely related to the deep carbon cycle. The Magellan Seamount chain in the West Pacific Seamount Province has wide distribution of alkali basalts. For the first time, we collected alkaline basalt samples from the Kocebu Seamount of the Magellan Seamount chain and found that magmatic apatites widely occur in the less evolved volcanic rock samples, and the high contents of phosphorus should be a feature of the alkaline OIBs of the Magellan Seamounts. Compared with typical OIBs, these alkaline volcanic rocks have higher CaO and P2O5, lower SiO2 content, negative anomaly of high field strength elements (HFSEs), more distinctly negative anomaly of potassium (K) and the ubiquity of titanaugite, indicating a CO2-rich mantle source. Based on the relatively high K2O and TiO2 contents and La/Yb ratio and low MgO content of these alkaline rocks, we suggest that the volcanic rocks of the Magellan Seamounts are originated from carbonated eclogites derived possibly from ancient subducted altered oceanic crust.Keywords：alkaline oceanic island basalts (OIBs);carbonatite;geochemistry;mantle source;Magellan Seamounts4|0|2Updated：2023-04-27
Geology
- Abstract：An investigation was carried out in the Y3 seamount area of the Western Pacific Ocean in December 2014, and the distribution of dissolved inorganic carbon (DIC) and its relationship with environmental factors in this area were explored. The results show that DIC concentration was higher in the adjacent waters of the Y3 seamount area, and the uplift of DIC isolines at the stations was close to the seamount. Meanwhile, interaction between the North Equatorial Current (NEC) and the Y3 seamount affected the DIC distribution, i.e., the upwelling in the same direction of the NEC was obvious, resulting in a decreasing trend of average concentration of DIC in the 200 m water column from the top to the two sides in this direction but in the cross direction. The DIC concentration increased with the water depth increase, and its distribution was affected by various environmental factors. In the surface water, high temperature was a decisive factor for the decrease of the DIC concentration, but the photosynthesis of phytoplankton showing only a weak influence. In the North Pacific Tropic Water (NPTW), DIC production rate from organic matter decomposition was higher than that of DIC consumption by phytoplankton photosynthesis, leading to a continual increase of DIC. In the North Pacific Intermediate Water (NPIW), organic matter decomposition played a leading role in the increase of DIC. In the deep water, decomposition of organic matter weakened, and the dissolution of CaCO3 controlled the carbonate system, and DIC had the smallest variation range.Keywords：dissolved inorganic carbon (DIC);Western Pacific Ocean;Y3 seamount;water masses;environmental factors4|0|3Updated：2023-04-27
- Abstract：A new acyclic peroxide derivative asperoxide A (1), along with 13 known compounds, namely, microperfuranone (2), 9-hydroxymicroperfuranone (3), gibellulin A (4), lecanoric acid (5), terrequinone A (6), sterigmatocystin (7), isosecosterigmatocystin (8), arugosin C (9), curvularin (10), 3, 3'-diindolylmethane (11), austinol (12), austin (13), and dehydroaustin (14), were isolated and identified from the culture extract of Aspergillus nidulans SD-531, a fungus obtained from the deep-sea sediment of cold spring in the South China Sea. Their structures were determined based on detailed interpretation of nuclear magnetic resonance (NMR) spectroscopic and mass spectrometry data analysis. All the isolated compounds were evaluated for antimicrobial activities against human and aquatic bacteria as well as plant pathogenic fungi. Compounds 1-8, 10, and 11 exhibited antimicrobial activities against some of the tested strains with minimum inhibitory concentration (MIC) values ranging from 2 to 64 njg/mL. Compounds 4 and 6 displayed strongest activities among the tested samples and might be used as promising molecules for the development of natural antimicrobial agents.Keywords：acyclic peroxide;Aspergillus nidulans;cold spring fungus;antimicrobial activity4|0|6Updated：2023-04-27
- Abstract：Marine biofouling is an expensive problem that needs evolved chemical or physical antifouling strategies. However, most of the current antifouling materials that would damage the environment through metal leaching and bacteria resistance are being halted. Nanozyme is one kind of environmental antifouling materials through generating reactive oxygen species (ROS). We prepared various contents of CeO2 that could uniform disperse compounding with Co3O4 and CoAl2O4 to form a stable Co-Al-Ce mixed metal oxide (MMO) by a layered double hydroxide derived method. We find that coupling with CeO2 can improve the peroxidase (POx) activity. When the molar ratio of Ce is 2.5% and the calcination temperature is 200¦, the POx activity of Co-Al-Ce MMO is the best caused by the good dispersion of catalytically active components and the high specific area (150.10±4.95 m2/g). This novel Co-Al-Ce MMO also exhibits an antibacterial mode of action Gram-negative bacteria in near-neutral pH solution through generating ROS (mainly ·O2-) in the presence of H2O2. Ce containing MMO can be utilized as potential green marine antifouling material.Keywords：mixed metal oxide;ceria;enzyme mimic;antibacterial;marine biofouling4|2|0Updated：2023-04-27
- Abstract：Marine corrosion and biofouling seriously affect the service life of marine structural materials, resulting in performance failure, enormous economic loss, and even catastrophic safety accidents. It is worthwhile and desirable to develop high-efficiency strategy for anti-corrosion and anti-biofouling. In this paper, superhydrophobic 5083 aluminum alloy (AA5083) surface with micro-nano hierarchical morphology was fabricated through anodization followed by 1H, 1H, 2H, 2H-perfluorooctyltriethoxysilane (POTS) modification. The surface morphologies, roughness, and chemical compositions were revealed by scanning electron microscopy, atomic force microscopy, and X-ray diffraction. The self-cleaning ability, corrosion resistance and algae adhesion suppression ability of the fabricated surfaces were investigated, indicating an excellent water-proofing, anti-corrosion and anti-biofouling performance. We believe the superhydrophobic creation of metallic materials is expected to have potential applications in marine corrosion and antibiofouling fields.Keywords：5083 aluminum alloy;anodization;superhydrophobic;corrosion resistance;anti-biofouling4|0|4Updated：2023-04-27
Chemistry
- Abstract：The population explosion of jellyfish Aurelia coerulea occurred in Jiaozhou Bay, China in 2009. The potential predation impact of A. coerulea on zooplankton was investigated. Population clearance potential and residence time (t1/2) for copepods were calculated from laboratory clearance rates and measurements of jellyfish size and abundance from May to August 2009 in Jiaozhou Bay. Clearance rates varied widely with prey organisms, but they were not significantly different among various prey concentrations. Medusae captured rotifers, fish larvae and hydromedusae more efficiently than fish eggs, copepods and chaetognaths. Ephyrae captured rotifers and hydromedusae more efficiently than fish larvae and copepods. Clearance rate linearly increased with the cross sectional area of A. coerulea (size from 0.3 to 7.1 cm). Water temperature also had a marked effect on clearance rate and this was related to the increased beat frequency as water temperature increased. In early May 2009, A. coerulea potentially cleared the volume of water in the Bay less than 0.001 times a day, but this value was estimated to be more than 0.3 times a day in July. The t1/2 for copepods was less than 6 d in June and July. Abundances of copepods, hydromedusae and chaetognaths were extremely low in 2009 compared to 2008 and 2010 (jellyfish non-bloom years). Large predation pressure by the A. coerulea population occurred to control zooplankton communities in Jiaozhou Bay. A. coerulea, when present at a high population level, can be a keystone species in Jiaozhou Bay and control the trophic structure here.Keywords：scyphomedusae;predation pressure;prey selection;zooplankton control;jellyfish bloom4|0|2Updated：2023-04-27
- Abstract：Phaeocystis globosa is a harmful algal bloom (HAB) species worldwide. Using modified clay (MC) to control HABs and to mitigate their adverse effects is currently a commonly used method in China. In this paper, the effects of oxidized composite modified clay (OXI-MC) on P. globosa were studied from different perspectives. The results show that the OXI-MC could effectively remove P. globosa and inhibit both the growth of residual algal cells and the formation of new colonies. The P. globosa algal biomass removal efficiencies after 3 h reached 90% at a dose of 0.1 g/L, and the number of colonies with different particle sizes was greatly reduced. Compared with those of the control, the superoxide dismutase (SOD) activity, catalase (CAT) activity, and malondialdehyde (MDA) content of the residual algae significantly increased, indicating that OXI-MC caused oxidative stress in the algal cells. In addition, we evaluated the effects of OXI-MC on the photosynthesis of residual microalgae and found that the maximal photochemical efficiency of photosystem Ⅱ (PSⅡ) under dark adaptation (Fv/Fm) and actual photochemical efficiency of PSⅡ (ФPSⅡ) decreased, severely damaging the photosynthesis efficiency, implying that OXI-MC effected the photosynthesis system of P. globosa. The results of this study clarify that OXI-MC could remove the most of algal cells and break up the colonies of P. globosa by collision, flocculation, and releasing active substances, as well as inhibit effectively the growth and colony formation of residual P. globosa by causing oxidative stress, reducing photosynthesis activity, accelerating the degradation of polysaccharides, and inhibiting the formation of colonies.Keywords：Phaeocystis globosa;modified clay;colony disruption;oxidative stress;photosynthesis4|0|1Updated：2023-04-27
- Abstract：Microscopic propagules of Ulva species (UMPs) spread on Subei Shoal are believed to play a significant role in the formation of the Yellow Sea green tide. Previous laboratory and ship-based studies indicated that modified clay (MC) can effectively remove UMPs from the water column and restrict their germination. To evaluate the effectiveness of this method under natural conditions, a mesocosm experiment was conducted on the Zhugensha sandbank on Subei Shoal. The results show that the suspended particles on the sandbank would partially disturb the flocculation process between the MC and UMPs. However, the MC at a proper dose could effectively remove UMPs from the water column and decrease the adhesion and germination of UMPs on the nylon ropes that comprised the mariculture rafts by > 75%. This method was proven a potential strategy to restrict the initial biomass accumulation of green algae on Subei Shoal. However, field trials in larger time-space scales are still needed to assess the efficiency of this method when used in the open sea.Keywords：green tide;Ulva;modified clay;microscopic propagules4|0|0Updated：2023-04-27
Ecology
- Abstract：Deep-sea mussels of the subfamily Bathymodiolinae are common and numerically dominant species widely distributed in cold seeps and hydrothermal vents. During long-time evolution, deep-sea mussels have evolved to be well adapted to the local environment of cold seeps and hydrothermal vents by various ways, especially by establishing endosymbiosis with chemotrophic bacteria. However, biological processes underlying the establishment and maintenance of symbiosis between host mussels and symbionts are largely unclear. In the present study, Gigantidas platifrons genes possibly involved in the symbiosis with methane oxidation symbionts were identified and characterized by Lipopolysaccharide (LPS) pull-down and in situ hybridization. Five immune related proteins including Toll-like receptor 2 (TLR2), integrin, vacuolar sorting protein (VSP), matrix metalloproteinase 1 (MMP1), and leucine-rich repeat (LRR-1) were identified by LPS pull-down assay. These five proteins were all conserved in either molecular sequences or functional domains and known to be key molecules in host immune recognition, phagocytosis, and lysosome-mediated digestion. Furthermore, in situ hybridization of LRR-1, TLR2 and VSP genes was conducted to investigate their expression patterns in gill tissues of G. platifrons. Consequently, LRR-1, TLR2, and VSP genes were found expressed exclusively in the bacteriocytes of G. platifrons. Therefore, it was suggested that TLR2, integrin, VSP, MMP1, and LRR-1 might be crucial molecules in the symbiosis between G. platifrons and methane oxidation bacteria by participating in symbiosis-related immune processes.Keywords：Gigantidas platifrons;endosymbiosis;innate immunity;pull-down assay;immune recognition;methane oxidation bacteria4|0|3Updated：2023-04-27
- Abstract：Gigantidas platifrons (Bivalvia, Mytilidae), the dominant species at the Formosa cold seep, relies on methanotrophic symbionts dwelling in its gills for nutrition. The reproductive patterns of G. platifrons provide fundamental information for understanding the population recruitment of this species. However, we know very little about important processes in reproduction, such as gametogenesis and symbiotic bacteria transmission. To this end, we described the developmental patterns of the gonads from nine surveys and juvenile length-distribution from one-year larval traps and detected bacteria in gonad from G. platifrons samples. Our results show that G. platifrons is a functionally dioecious species. The reproduction of G. platifrons is discontinuous, with spawning maturity peak around the fourth quarter of the year. The seasonal reproduction of G. platifrons was further supported by the unimodal shell length distribution of the trapped juvenile mussels. Given the small oocyte size (48.99-70.14 μm), which was comparable to that of coastal mussels, we proposed that G. platifrons developed via a free-living, planktotrophic larval stage before settlement. The blooms at the water surface can also supply the development of the planktonic larvae of G. platifrons. Meanwhile, no bacteria were observed in gonads, suggesting a horizontal symbiont transfer mode in this mussel. Collectively, these results provide fundamental biological information for an improved understanding of the early life history of G. platifrons in the Formosa cold seep.Keywords：cold seep;gametogenesis;Gigantidas platifrons;reproductive;South China Sea (SCS)4|0|0Updated：2023-04-27
- Abstract：The elpidiid holothurian Peniagone leander Pawson and Foell, 1986 is recorded for the first time from the Mariana Trench area at a depth of 5 571 m. The type description of this species was based on only in-situ photographs. P. leander is re-described and illustrated based on a preserved material and in-situ photographs taken on the seabed. The 16S rRNA was also obtained from the specimen and submitted to GenBank. This is the fourth discovery of this species, extending its bathymetric range in the western Pacific Ocean.Keywords：Elpidiidae;abyssal zone;deep-sea holothurian;benthopelagic species;new record4|0|0Updated：2023-04-27
Biology
- Abstract：A water flow simulation device capable of adjusting flow velocity was designed in flow velocity range of 0-30 cm/s, with which an indoor experiment was conducted to simulate the movement and adhesive behaviors of different-sized Apostichopus japonicus under different flow velocities. Observation showed that, in slow flow (~5 cm/s), A. japonicus moved more distance than in still water, and hardly moved in the riptide (~30 cm/s); and the adhesive capacity of A. japonicus was related to the flow velocity and attachment time. A. japonicus were able to attach to the bottom after any attachment time in the slow flow, after 10 s in the medium flow (~15 cm/s), and after 60 s in the riptide (~30 cm/s). In addition, larger A. japonicus were stronger with adhesive ability than smaller ones. The transcriptome data showed that the expression of transient receptor potential cation channel subfamily A, member 1 (TRPA1) in the tube feet was increased significantly in a flowing water, but those in the tentacles and tube feet were not significantly changed. Fluorescence in-situ hybridization results showed that TRPA1 was expressed around the watervascular of tentacles, tube feet, body wall, and spines. Therefore, tube feet were important for sea cucumbers to keep themselves stable in relatively swift flow with adhesion ability.Keywords：sea cucumber;Apostichopus japonicus;flow velocity;transient receptor potential cation channel subfamily A, member 1 (TRPA1)4|0|0Updated：2023-04-27
Aquaculture and Fisheries
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