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Simple Summary: The life history traits of Uroteuthis edulis, an economically important loliginid squid in the East China Sea (ECS), have always attracted attention, especially its migration. Understanding the early transport process and influencing factors is a prerequisite for grasping population recruitment and dynamics. To address this, this study used statolith microchemical information and particle tracer experiments to indicate changes in individual habitats and simulate early transport processes, respectively. The results showed that there were differences in early transport trajectories between spring stock and summer stock. Velocity, salinity, and temperature were the key environmental variables affecting early transport for spring stock, while mixed-layer depth (MLD), velocity, and chlorophyll a concentration (Chla) were the key environmental variables for summer stock. These results are related to the dominant characteristics of ocean currents during early transport, which in turn affects the growth and development status of paralarvae. This study provides scientific guidance for understanding population dynamic processes and the sustainable development of resources. Uroteuthis edulis (U. edulis) is an important economic loliginid resource in the East China Sea (ECS). Its flexible life history traits enable the population to quickly adapt to changes in habitat. Understanding the early transport process helps us to grasp the habitat requirements of populations at key life history stages. In this study, particle tracing was used to simulate the early transport trajectories (within 120 days). The gradient forest method (GFM) and generalized additive mixed models (GAMMs) were used to analyze the key environmental variables that affect the early transport trajectories and the impact of environmental factors on the transport process, respectively. The results showed that spring stock tracers were transported to the northeast of the release area (Pengjiayu water) and the Pacific side of Japan. Summer stock tracers were transported to the north and northeast of the release area (Zhoushan island). Current velocity, salinity, and temperature were key environmental variables that affected the trace element ratios of spring stock at early life history stages. Mixed-layer depth (MLD), velocity, and chlorophyll a concentration (Chla) were key environmental variables for summer stock. Zonal velocity was positively correlated with the trace element ratio for spring and summer stock (0.14–0.16 m/s), while the meridional velocity showed an opposite correlation. The physical driving mechanisms of the Kuroshio warm current (or the Taiwan warm current) and the Yangtze River determine the paralarva retention location during early transportation. The differences in the dominant factors of the water environment in the retention area may affect the paralarva physiological functions and food availability. This study provides a scientific basis for a comprehensive understanding of the migration characteristics of U. edulis with different stocks. [ABSTRACT FROM AUTHOR]

Maritime disputes among the East Asian States have garnered increasing attention worldwide with expanding offshore activities in the East China Sea. To avoid confrontation and potential conflict, unilateral maritime claims in the East China Sea usually have been non-explicit. While maritime boundary disputes remain unresolved in the region, changes have taken place because of resource shortages, the rise in military assertiveness from Tokyo, and increased alliances with the United States. This article explores the limits of unilateral activities within the disputed maritime area under current international law and how East Asian States should behave when they encounter unilateral activities conducted by other States, including analysis on sovereign entitlement and the limits of unilateral activities in the region. A code of conduct among the East Asian States is needed to ensure peace and prosperity in the region. [ABSTRACT FROM AUTHOR]

Against the background of climate warming, marine heatwaves (MHWs) and terrestrial drought events have become increasingly frequent in recent decades. However, the combined effects of MHWs and terrestrial drought on CO2 uptake in marginal seas are still unclear. The East China Sea (ECS) experienced an intense and long-lasting MHW accompanied by an extreme terrestrial drought in the Changjiang basin in the summer of 2022. In this study, we employed multi-source satellite remote sensing products to reveal the patterns, magnitude, and potential drivers of CO2 flux changes in the ECS resulting from the compounding MHW and terrestrial drought extremes. The CO2 uptake of the ECS reduced by 17.0% (1.06 Tg C) in the latter half of 2022 and the Changjiang River plume region shifted from a CO2 sink to a source (releasing 0.11 Tg C) in July-September. In the majority of the ECS, the positive sea surface temperature (SST) anomaly during the MHW diminished the solubility of CO2 in seawater, thereby reducing CO2 uptake. Moreover, the reduction in nutrient input associated with terrestrial drought, which is unfavorable to phytoplankton growth, further reduced the capacity of CO2 uptake. Meanwhile, the CO2 sink doubled for the offshore waters of the ECS continental shelf in July-September 2022, indicating the complexity and heterogeneity of the impacts of extreme climatic events in marginal seas. This study is of great significance in improving the estimation results of CO2 fluxes in marginal seas and understanding sea–air CO2 exchanges against the background of global climate change. [ABSTRACT FROM AUTHOR]

Over the past two decades, the environmental characteristics of the northern East China Sea (NECS) that make it a crucial spawning ground for commercially significant species have faced substantial impacts due to climate change. Protein (PRT) within phytoplankton, serving as a nitrogen-rich food for organisms of higher trophic levels, is a sensitive indicator to environmental shifts. This study aims to develop a regional PRT algorithm to characterize spatial and temporal variations in the NECS from 2012 to 2022. Employing switching chlorophyll-a and particulate organic nitrogen algorithms, the developed regional PRT algorithm demonstrates enhanced accuracy. Satellite-estimated PRT concentrations, utilizing data from the Visible Infrared Imaging Radiometer Suite (VIIRS), generally align with the 1:1 line when compared to in situ data. Seasonal patterns and spatial distributions of PRT in both the western and eastern parts of the NECS from 2012 to 2022 were discerned, revealing notable differences in the spatial distribution and major controlling factors between these two areas. In conclusion, the regional PRT algorithm significantly improves estimation precision, advancing our understanding of PRT dynamics in the NECS concerning PRT concentration and environmental changes. This research underscores the importance of tailored algorithms in elucidating the intricate relationships between environmental variables and PRT variations in the NECS. [ABSTRACT FROM AUTHOR]

Chlorophyll-a (Chl-a) concentration is a primary indicator for marine environmental monitoring. The spatio-temporal variations of sea surface Chl-a concentration in the Yellow Sea (YS) and the East China Sea (ECS) in 2001–2020 were investigated by reconstructing the MODIS Level 3 products with the data interpolation empirical orthogonal function (DINEOF) method. The reconstructed results by interpolating the combined MODIS daily +8-day datasets were found better than those merely by interpolating daily or 8-day data. Chl-a concentration in the YS and the ECS reached its maximum in spring, with blooms occurring, decreased in summer and autumn, and increased in late autumn and early winter. By performing empirical orthogonal function (EOF) decomposition of the reconstructed data fields and correlation analysis with several potential environmental factors, we found that the sea surface temperature (SST) plays a significant role in the seasonal variation of Chl a, especially during spring and summer. The increase of SST in spring and the upper-layer nutrients mixed up during the last winter might favor the occurrence of spring blooms. The high sea surface temperature (SST) throughout the summer would strengthen the vertical stratification and prevent nutrients supply from deep water, resulting in low surface Chl-a concentrations. The sea surface Chl a concentration in the YS was found decreased significantly from 2012 to 2020, which was possibly related to the Pacific Decadal Oscillation (PDO). [ABSTRACT FROM AUTHOR]

Most annual studies of tintinnid and phytoplankton in coastal habitats are influenced by alien species introduced by water masses exchange, and therefore cannot be used as direct evidence for exploring the mechanism of annual succession in indigenous community. For brackish communities, very limited annual studies exist because of the difficulty of conducting stable sampling in the transition between freshwater and seawater. The special topography of Xiangshan Bay isolates the external water mass and provides a suitable habitat for exploring the annual succession mechanism of the brackish tintinnid community. In this study, samples were collected from seven stations in Tie Harbor, Xiangshan Bay (East China Sea) during 10 months from 2022 to 2023. A total of 23 tintinnid species of five genera were identified throughout the year. These tintinnid species can be clustered into four seasonal groups, winter, summer, autumn and spring-autumn, with three temperature preferences. The Lorica Oral Diameter (LOD) size-class of each tintinnid species, which determines the food item size of tintinnid, separated their different ecological niches within each seasonal group. The seasonal succession of tintinnid community in Xiangshan Bay was organized by both temperature preference and LOD size of the tintinnid species. [ABSTRACT FROM AUTHOR]

We report the complete mitochondrial genome of Rhynchocinetes brucei Okuno 1994. The mitogenome was found to contain 16158 bp with 13 protein-coding genes (PCGs), 22 tRNA genes (tRNAs), 2 rRNA genes (rRNAs), and 1 putative control region. Phylogenetic analysis indicated that R. brucei was sister to Rhynchocinetes durbanensis (PP= 1), of the same family Rhynchocinetidae. These results are helpful for research on the phylogenetic and evolutionary studies of this group. [ABSTRACT FROM AUTHOR]

Simple Summary: Monitoring microplastics (MPs) in cetaceans is challenging due to difficulties in obtaining samples, especially for endangered species. In this study, we characterized MPs ingested in nine individuals of four cetacean species stranded along the western coast of the Taiwan Strait including not only small coastal dolphins but also large pelagic and deep-diving cetaceans. A total intestine length of 123.2 m was analyzed, and the color, shape, size, and polymer types of MPs were then identified. The mean abundance of MPs was 86.44 ± 12.22 items individual−1, which was slightly higher compared with the same species from other waters worldwide. Moreover, a strong significant relationship between MPs abundance and intestine contents mass was identified. Transparent, fibrous MPs made from PET and PP were found to be predominant in the present study, indicating that the primary MPs source is from municipal and industrial sewage from clothing production and industry as well as from fisheries and aquaculture. Our study provides more information about the MPs pollution of endangered species in the western Taiwan Strait. It highlights the further risk assessment of MPs consumption in these threatened species. Microplastics (MPs) pollution is of global concern, which poses serious threats to various marine organisms, including many threatened apex predators. In this study, MPs were investigated from nine cetaceans of four different species, comprising one common dolphin (Delphinus delphis), two pygmy sperm whales (Kogia breviceps), one ginkgo-toothed beaked whale (Mesoplodon ginkgodens), and five Indo-Pacific humpback dolphins (Sousa chinensis) stranded along the western coast of the Taiwan Strait from the East China Sea based on Fourier transform infrared (FTIR) spectroscopy analysis. Mean abundances of 778 identified MPs items were 86.44 ± 12.22 items individual−1 and 0.43 ± 0.19 items g−1 wet weight of intestine contents, which were found predominantly to be transparent, fiber-shaped polyethylene terephthalate (PET) items usually between 0.5 and 5 mm. The abundance of MPs was found at a slightly higher level and significantly correlated with intestine contents mass (p = 0.0004*). The MPs source was mainly likely from synthetic fibers-laden sewage discharged from intense textile industries. Our report represents the first study of MPs in pelagic and deep-diving cetaceans in China, which not only adds baseline data on MPs for cetaceans in Asian waters but also highlights the further risk assessment of MPs consumption in these threatened species. [ABSTRACT FROM AUTHOR]

Cross‐shelf penetrating fronts (CPFs) induce significant cross‐shelf exchange of water properties and nutrients, and thus are important to coastal environments. In this study, the characteristics and mechanisms of realistic large‐scale CPFs in the East China Sea in summer were investigated based on a data assimilative model. The model reproduced CPFs matched well with satellite observations. Although the cross‐shelf currents were predominantly offshore off the Zhe‐Min Coast, only three strong large‐scale CPFs occurred in the summer of 2014. The three‐dimensional structure of CPF in the model was similar with that observed in previous research. Two different mechanisms were responsible for the formation of observed CPFs. Two CPFs formed as a result of the convergence of the Taiwan Warm Current (TWC) and the Zhe‐Min Coastal Current (ZMCC), while the other one was caused by the undulation of thermocline. Heat budget analysis suggests that the undulation of thermocline was caused by horizontal and vertical advection. Sensitivity experiments suggest that southerly wind relaxation and tidal forcing are indispensable conditions for CPF formation. Tidal forcing makes the axis of the ZMCC shift offshore by ∼50 km, so that the ZMCC could impinge right against the axis of the TWC. The relaxation of the southerly winds allows the ZMCC to extend southward. Southerly wind relaxation in summer is mostly associated with tropical cyclones. Without winds and synoptic variation of the TWC, CPFs form periodically due to the strengthening of the ZMCC during neap tide period. Plain Language Summary: Coastal ocean currents generally follow isobaths on timescale longer than one day. Cross‐shelf currents induce significant exchange of nutrients and dissolved materials and thus are important to coastal environments. Cross‐shelf penetrating fronts are observed as large‐distance cross‐shelf frontal intrusion from satellite ocean‐color observations. They frequently occurred in the East China Sea, but their key mechanisms are not very clear. Based on results of a numerical ocean model, we investigated several realistic cases of penetrating fronts in the summer of 2014 and revealed two major mechanisms. One mechanism is the convergence of two ocean currents that flow in the opposite direction. The other mechanism is associated with the thermocline undulation, which will induce cross‐shelf currents through dynamic adjustment. The impact of several important factors which include tide forcing, winds, synoptic variation of shelf currents and river discharge were also evaluated with numerical experiments. The results show that tidal forcing and the relaxation of southerly winds are indispensable condition for penetrating fronts. The relaxation of southerly winds in summer is usually associated with the influence of typhoons. The revealed mechanisms advance our understanding of cross‐shelf currents in coastal seas. Key Points: Flow convergence and thermocline undulation are two major mechanisms of the penetrating frontsTidal forcing and relaxation of southerly wind are indispensable conditions for penetrating front formationThe relaxation of southerly winds in summer is mostly associated with tropical cyclones [ABSTRACT FROM AUTHOR]

Lipid biomarkers are amongst the most widely used proxies in studies of the structure and functioning of marine food webs. However, vertical distributions of lipid biomarkers and their controlling mechanisms remain unclear, especially in highly dynamic coastal ecosystems. Here we tested vertical profiles of key lipid biomarkers (sterols and fatty acids) in suspended particles and their correlations with water masses in spring of 2017 and summer of 2018 in the Zhejiang coasts of the East China Sea. The Changjiang Diluted Water, the Taiwan Strait Water and the Kuroshio Subsurface Water showed strong contributions in the surface layer in spring, the surface layer in summer, and the deep layer in both seasons, respectively. Accordingly, lipid biomarker composition also varied between different water layers. Overall, lipid biomarker concentrations in the surface layer were around 2 ~ 7 times higher than those in the deep layer, indicating high phytoplankton biomass in the surface layer. The ratio of docosahexaenoic acid to eicosapentaenoic acid was also higher in the surface layer, especially in the south of our study region, suggesting high nutritional quality of particulate organic matters in the surface layer. Significant correlations between the depth profiles of lipid biomarkers and water masses suggested the control of water masses on lipid biomarker production. The distribution patterns of lipid biomarkers in our study are consistent with previous findings on zooplankton grazing and fish larvae, highlighting the significance of lipid biomarkers as trophic markers to study food web structure and functioning in highly dynamic coasts.

The East China Sea Basin (ECSB) is an integral part of the Western Pacific tectonic system. Its development is linked to the Kula–Pacific Plate and the formation and expansion of the Philippine Sea Basin. Recent advancements in exploration technologies and theory have been applied to Mesozoic basins in the East China Sea. Researchers have posited that the southern basin has great oil and gas exploration potential. However, the characteristics and evolution of fault structures and their influence on hydrocarbon accumulation remain unclear. Here, in-depth geometric and kinematic analyses of Mesozoic fault structures in the southern ECSB were conducted using the latest interpretations of 2D seismic data and structural analysis theory. The findings revealed that the fault system was well developed and predominantly exhibited multiphase extensional and extensional-torsional features. Based on their lateral distribution and morphology, faults were categorized into three structural styles and seven combinations. According to their developmental timing, periods of active faulting were attributed to the Yanshan and Himalayan epochs. Multiphase fault activities strongly controlled the formation of traps and thus hydrocarbon accumulation, while earlier NE-trending faults controlled the formation of structural belts and hydrocarbon source areas.

A comprehensive analysis was carried out to investigate the driving factors and influencing mechanisms of spatiotemporal variation of sea level at multiple scales in the East China Sea (ECS) via satellite altimetry datasets from 1993 to 2020. Based on the altimetry grid data processed by the local mean decomposition method, the spatiotemporal changes of ECS sea level are analyzed from the multi-scale perspective in terms of multi-year, seasonal, interannual, and multi-modal scales. The results revealed that the ECS regional mean sea level change rate is 3.41 ± 0.58 mm/year over the 28-year period. On the seasonal scale, the regional mean sea level change rates are 3.45 ± 0.66 mm/year, 3.35 ± 0.60 mm/year, 3.39 ± 0.71 mm/year, and 3.57 ± 0.75 mm/year, for the four seasons (i.e., spring, summer, autumn, and winter) respectively. The spatial distribution analysis showed that ECS sea level changes are most pronounced in coastal areas. The northeast sea area of Taiwan and the edge of the East China Sea shelf are important areas of mesoscale eddy activity, which have an important impact on regional sea level change. The ECS seasonal sea level change is mainly affected by monsoons, precipitation, and temperature changes. The spatial distribution analysis indicated that the impact factors, including seawater thermal expansion, monsoons, ENSO, and the Kuroshio Current, dominated the ECS seasonal sea level change. Additionally, the ENSO and Kuroshio Current collectively affect the spatial distribution characteristics. Additionally, the empirical orthogonal function was employed to analyze the three modes of ECS regional sea level change, with the first three modes contributing 26.37%, 12.32%, and 10.47%, respectively. Spatially, the first mode mainly corresponds to ENSO index, whereas the second and third modes are linked to seasonal factors, and exhibit antiphase effects. The analyzed correlations between the ECS sea level change and southern oscillation index (SOI), revealed the consistent spatial characteristics between the regions affected by ENSO and those by the Kuroshio Current.

In this study, the complete mitochondrial genome of the Taiwan tai Argyrops bleekeri was determined for the first time by next-generation sequencing. The circular mtDNA molecule was 16,646 bp in size and the overall base composition was A (27.77%), C (28.95%), G (16.60%), and T (26.68%), with a slight bias toward A + T. The complete mitogenome encoded 13 protein-coding genes (PCGs), 22 tRNA genes, two rRNA genes, and a control region. Phylogenetic analysis based on the 13 PCGs of the Sparidae family revealed that Argyrops appears to be most closely related to Pagrus and Parargyrops, but further research is needed.

In recent decades, rise of sea surface temperature (SST) in the Kuroshio region of the East China Sea (ECS), which is associated with global warming, has attracted considerable attention. Despite its relevance to air‐sea interaction phenomena, the atmospheric consequences of this SST increase remain largely unexplored. Using the ERA5 reanalysis data set in conjunction with a moisture budget analysis, we found that during 1979–2022, warming in the ECS‐Kuroshio has contributed to the intensification of the East Asian Meiyu‐Baiu rainband in June. This intensification is attributed to augmented wind convergence in the low‐level free troposphere (950–700 hPa). Importantly, the atmospheric responses to ECS‐Kuroshio warming penetrated the deep troposphere (to approximately 300 hPa), suggesting an enhancement of deep convection. Furthermore, ECS‐Kuroshio warming likely strengthened the overlying atmospheric low pressure, resulting in wind convergence enhancement. The findings clarified the important role of the ECS‐Kuroshio in driving East Asian climate change amid global warming. Plain Language Summary: In response to global warming, East Asian summer precipitation is increasing along with an increase in extreme precipitation events, which poses a significant threat to agriculture and economic development. Understanding the mechanisms underlying the increased precipitation trend in East Asia is crucial for sustainable human development in this region. The findings of this study revealed that East Asian precipitation induced by the Meiyu‐Baiu rainband has intensified continuously during the past four decades, particularly in the marine areas around the East China Sea (ECS) and the south of Japan. We further established that the continuous increase in sea surface temperature over the Kuroshio in the ECS, which was related to global warming, strengthened the atmospheric low‐pressure system overlying the current, contributing to an increase in rainfall around the ECS. The findings of this study highlighted the important role of the Kuroshio Current in influencing climate change in East Asia. Key Points: The Meiyu‐Baiu rainband in June intensified over the marine areas around the Kuroshio and south of Japan during 1979–2022The intensified Meiyu‐Baiu rainband was caused mainly by the wind convergence accompanied by enhanced deep convectionKuroshio warming in the East China Sea likely intensified the Meiyu‐Baiu rainband by a pressure adjustment mechanism [ABSTRACT FROM AUTHOR]

Carbon capture, utilization and storage (CCUS) technology is an important means to effectively reduce carbon emissions from fossil energy combustion and industrial processes. With the crisis of climate change, CCUS has attracted increasing attention in the world. CCUS technology as developed rapidly in China is technically feasible for large-scale application in various industries. The R&D and demonstration of CCUS in China Petroleum & Chemical Corporation (Sinopec) are summarized, including carbon capture, carbon transport, CO2 enhanced energy recovery (including oil, gas, and water, etc.), and comprehensive utilization of CO2. Based on the source-sink matching characteristics in China, two CCUS industrialization scenarios are proposed, namely, CO2-EOR, CO2-driven enhanced oil recovery using centralized carbon sinks in East China and CO2-EWR, CO2-driven enhanced water recovery (EWR) using centralized carbon sources from the coal chemical industry in West China. Finally, a CCUS industrialization path from Sinopec's perspective is suggested, using CO2-EOR as the major means and CO2-EWR, CO2-driven enhanced gas recovery (CO2-EGR) and other utilization methods as important supplementary means. [ABSTRACT FROM AUTHOR]

The Yellow Sea (YS) and East China Sea (ECS) are highly dynamic marginal seas of the northwestern Pacific Ocean. To gain an in-depth understanding of zooplankton community structure, zooplankton abundance, biovolume, and size structure in summer 2017 in the YS and ECS were assessed using ZooScan imaging analysis. Zooplankton abundance and biovolume ranged 2.94–1 187.14 inds./m3 and 3.13–3 438.51 mm3/m3, respectively. Based on the biovolume data of the categorized size classes of 26 identified taxonomic groups, the zooplankton community was classified into five groups, and each group was coupled with distinctive oceanographic features. Under the influence of the Yellow Sea Cold Water Mass, the Yellow Sea offshore group featured the lowest bottom temperature (10.84±3.42 °C) and the most abundant Calanoids (mainly in the 2–3 mm size class). In the Yellow Sea inshore group, Hydrozoans showed the largest biovolume and dominated in the 3–4-mm and > 5-mm size classes. The East China Sea offshore group, which was affected by the Kuroshio Branch Current, featured high temperature and salinity, and the lowest bottom dissolved oxygen (2.58±0.5 mg/L). The lowest values of zooplankton abundance and biovolume in the East China Sea offshore group might be attributed to the bottom dissolved oxygen contents. The East China Sea inshore group, which was mainly influenced by the Zhejiang-Fujian Coastal Current and Changjiang Diluted Water, was characterized by high chlorophyll a and the largest biovolume of carnivorous Siphonophores (280.82±303.37 mm3/m3). The Changjiang River estuary offshore group showed the most abundant Cyclopoids, which might be associated with the less turbid water mass in this region. Seawater temperature was considered the most important factor in shaping the size compositions of Calanoids in different groups. [ABSTRACT FROM AUTHOR]

Based on the data of the acoustic and physical properties of seafloor sediments obtained on the continental shelf area of the East China Sea (ECS), prediction equations of the sediment sound speed based on single and dual parameters were established, and the correlation of the sound speed with physical parameters was discussed. The results show that the sediment sound speed (c) is strongly correlated with water content (w), density (ρ), void ratio (e), mean grain size (Mz) and median grain size (Md), and the coefficient of determination R2 of the empirical regression equation is generally greater than 0.80, while the empirical regression equation coefficient of determination R2 of the compression coefficient (a) and compression modulus (E) are slightly lower, with 0.79 and 0.73, respectively. The coefficients of determination of the dual parameter regression equations between sediment sound speed with physical property parameters are generally higher than those of the single parameter equations, which are all higher than 0.90 indicating better prediction performance. The sensitivity of the physical parameters to the sound speed was analyzed, and the result shows that the sequence of sensitivity from high to low influence on sediment sound speed is void ratio, density, compressibility coefficient, median grain size and mean grain size. The prediction equations established in this study are a good extension and supplement to marine geoacoustic models and is of great significance for obtaining the acoustic properties of the seafloor sediments on the shelf of the East China Sea. [ABSTRACT FROM AUTHOR]

The relocation of the controversial Marine base at Futenma on Okinawa to Henoko in the north of the same island has been framed by Japanese politicians, officials, and analysts as crucial to deterrence. Critics respond that deterrence is merely a pretext, and the relocation is a politically convenient solution that perpetuates discrimination against Okinawa by the central government in Tokyo. This article draws on deterrence theory to evaluate the deterrence claims made by relocation proponents. It finds little evidence to support them: the Marines' capabilities pale against the massive US forward deployment, including the Seventh Fleet and the Fifth Air Force. As for the local balance of forces, the Marines are unlikely to participate immediately in a local conflict, and their geographical location leaves them vulnerable; current US strategy is to down-scale and disperse Marine units. If one were focusing on defence rather than political convenience, the Marines would be relocated off Okinawa. In terms of credibility, the article finds that other US bases in Japan play a much more important 'tripwire' role, and ultimately, given inter alia the security treaty, joint exercises, and deep interoperability, US extended deterrence to Japan is as credible as possible under the circumstances. [ABSTRACT FROM AUTHOR]

The cross‐shelf carbon transports across a section along the 100 m isobath from Taiwan to Cheju are estimated based on carbon concentration observations and ocean currents simulated by a regionally zoomed ocean‐atmosphere coupled model. Results show that the net cross‐shelf particulate organic carbon, dissolved organic carbon, and dissolved inorganic carbon transports are in the offshore direction at 1.81 ± 0.22, 51.8 ± 2.85, and 783 ± 58.9 TgC yr−1, respectively, which are high in spring and summer and low in winter and fall following the seasonality of the offshore volume transport. The carbon is transported into the East China Sea (ECS) mainly by the Taiwan Warm Current and the Yellow Sea Warm Current, whereas they are carried out of the ECS mainly by the East China Sea Current extension and the recirculation north of Taiwan. Assuming steady biological activity, future net total organic carbon transports are projected to increase by 5%∼19% offshore at the end of the 21st century, with the maximum increase in winter, in a high greenhouse gas emission scenario of RCP8.5. The increased carbon transports are due to the increased offshore volume transport, transferring more carbon‐rich coastal water away from the shelf in the warming future than at present. The results quantify cross‐shelf carbon burial in the ECS in the background of global warming. Plain Language Summary: Carbon transport due to water exchange between the continental shelf and the open ocean is one of the most important components of the world ocean carbon budgets. In this study, the cross‐shelf carbon transport in the East China Sea (ECS) is estimated based on in situ carbon concentration observations and simulated ocean currents by an ocean‐atmosphere coupled model. The use of the simulated currents is to avoid a bogus volume surplus in the estimates of the carbon transports. The offshore and the onshore volume transports, with significantly different carbon concentrations, are found to have a strong seasonal cycle and increase in the background of global warming, both of which are much larger than their difference, a.k.a. the net volume transport. As a result, the net cross‐shelf carbon transports are in the offshore direction and are high in spring and summer and low in winter and fall. The organic carbon transports are projected to increase due to the ongoing global warming. These changes in the carbon burial need to be considered when assessing the impact of human activities and warming on the global carbon cycle. Our work would provide scientific evidence for increasing carbon sinks in the ECS in the warming future. Key Points: Carbon transports across the ECS shelf were estimated based on carbon concentration observations and simulated currentsOffshore carbon transports are found induced by the ECSC from the inner shelf to the shelf breakThe organic carbon transports are projected to increase with the global warming at the end of the 21st century [ABSTRACT FROM AUTHOR]

Tremendous amounts of materials and energy are transported from the East China Sea (ECS) to the East/Japan Sea (EJS) through the Korea/Tsushima Strait (KTS). Tides undoubtedly play an important role in regulating ocean circulation on the broad continental shelf of the ECS, while the effects of tides on the water exchange between the ECS and EJS remain unclear. Using a three-dimensional Regional Oceanic Modeling System (ROMS) circulation model, we conducted numerical experiments with tides, without tides, and only barotropic tides. The results showed that the water flux across the KTS can increase by up to 13% (in summer) when excluding tides from the numerical simulation. To understand how tidal forcing regulates the KTS water flux, we performed a dynamic diagnostic analysis and revealed that the variation in sea surface height under tidal effect is the main reason for the water flux variation across the KTS. The tidal effect can adjust the sea surface height, weaken the pressure gradient and reduce the water flux across the KTS, which affect the intensity of water exchange between the ECS and EJS. The tidal effect can alter sea level difference between the Taiwan Strait and the KTS, which influences the KTS water flux. Tides can also influence the KTS water flux by altering the sea surface height through interaction with topography and stratification. We also found that tidal effect weakens the northward intrusion of the Yellow Sea Warm Current in winter and in turn enhances the water flux across the KTS according to volume conservation. These modeling results imply that tides must be considered when simulating the ocean environment of the northwestern Pacific Ocean. [ABSTRACT FROM AUTHOR]

Continental marginal seas are key systems in the global carbon cycle. Carbon stocks represent the ability to store carbon, thus quantifying the carbon stocks in marine sediments would help to better understand their importance in the carbon cycle. In this study, 17 sediment cores in the mud areas of the South Yellow Sea and the East China Sea were measured for total organic carbon (TOC) and its stable isotope (d13C), and dry bulk density; and from which the carbon stocks and carbon stock accumulation rate as well as marine/terrestrial carbon stocks/carbon stock accumulation rate were calculated. The carbon stocks in the mud area of the South Yellow Sea showed a decreasing trend during 1855 to 1950 caused by the relocation of the Yellow River Estuary in 1855, but increased after 1950s due to increased sediment input via the enhancement of South Shandong Coastal Current. In the Min-Zhe belt of the East China Sea, carbon stocks showed an overall high marine proportion due to the phytoplankton bloom induced by high nutrient level, but the decreased carbon stocks in recent decades were mainly caused by the construction of reservoirs in the Yangtze River that reduced sediment transports. The average carbon stocks in 1 m sediments from the South Yellow Sea (45.2 t ha-1) and Min-Zhe belt (52.8 t ha-1) were low compared to that of global marine sediments (66.6 t ha-1), while the carbon stock accumulation rate showed much higher values (0.1 t ha-1 yr-1 in South Yellow Sea and 0.31 t ha-1 yr-1 in the Min-Zhe belt) because of higher sedimentation rates. Although carbon stocks of Chinese marginal seas were also lower than that of the tidal flats (70.7 t ha-1) and wetland (123.6 t ha-1) in China, their much larger area could store 0.75 Pg C in marine sediments. Our temporal records suggest that anthropogenic activities have reduced carbon stocks in the marginal seas since 1950, causing carbon to re-enter the atmosphere to impact climate changes. [ABSTRACT FROM AUTHOR]

During the propagation of the Hinnamnor typhoon from September 5 to 6, 2022, swell waves were recorded that arrived at the recording point 20 h before the typhoon entered the Sea of Japan. While analyzing the field data of the laser meter of fluid pressure variation, it was possible to calculate the area of the formation of the main group of swell waves generated by the propagating typhoon and to localize the region of generation of forerunner waves and also to describe the mechanisms of their formation and propagation. [ABSTRACT FROM AUTHOR]

Investigating the paleoenvironment and characteristics of source rocks in sedimentary basins is crucial for understanding organic matter accumulation and guiding hydrocarbon exploration. The Lishui Sag, a significant hydrocarbon-bearing depression in the East China Sea, has experienced extensive marine transgression and increasing salinity in the Paleocene, but the changes in accumulation factors of organic matter during this evolution process remain unclear. Through a comprehensive analysis of total organic carbon (TOC), major and trace elements, and biomarker data, this study investigates the characteristics of source rocks from two lithostratigraphic units, namely the Paleocene Yueguifeng and Lingfeng formations, to gain deep insight into the effects of paleoenvironment on organic matter accumulation and hydrocarbon distribution. Our results indicate that the Lishui Sag transitioned from a closed lake to an open-marine environment in the Paleocene, with a shift from warm-humid to arid climate conditions. The biomarker distribution suggests a change in the origin of organic matter, with a higher input of terrestrial organic matter in the Lingfeng Formation. During the early stage, the lacustrine source rocks in the lower Yueguifeng Formation were formed in a relatively humid and anoxic environment within brackish water, resulting in a substantial influx of terrestrial and lacustrine algae organic matter. In contrast, in the late stage, the marine source rocks in the overlying Lingfeng Formation were developed in an arid and oxidizing environment. The lacustrine source rocks in the Yueguifeng Formation were notably more favorable to developing good-quality source rocks. Compared with the other regions, the western and northeastern parts of the study area have greater hydrocarbon generation potential due to the wider distribution of high maturity and organic-rich source rocks, with higher terrestrial and algal organic matter input. Moreover, considering the practical circumstances in the exploration, the northeastern part of the Lishui Sag is recommended as the next exploration target zone. [ABSTRACT FROM AUTHOR]

Oil spill prediction is critical for reducing the detrimental impact of oil spills on marine ecosystems, and the wind strongly influences the performance of oil spill models. However, the wind drift factor is assumed to be constant or parameterized by linear regression and other methods in existing studies, which may limit the accuracy of the oil spill simulation. A parameterization method for wind drift factor (PMOWDF) based on deep learning, which can effectively extract the time-varying characteristics on a regional scale, is proposed in this paper. The method was adopted to forecast the oil spill in the East China Sea. The discrepancies between predicted positions and actual measurement locations of the drifters are obtained using seasonal statistical analysis. Results reveal that PMOWDF can improve the accuracy of oil spill simulation compared with the traditional method. Furthermore, the parameterization method is validated with satellite observations of the Sanchi oil spill in 2018. [ABSTRACT FROM AUTHOR]

Copyright of South China Fisheries Science is the property of South China Fisheries Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Uroteuthis edulis is a widespread neritic cephalopod with a complex population structure and wide migration range. The life history of this species is still ambiguous. Statolith microchemistry is an effective indicator to reveal individual life history and migration route. In this study, the statolith microchemistry of U. edulis in different stocks was determined by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), and the statolith diameter was clustered by using a multiple regression tree model (MRT) to analyze differences in the ratio of various elements to Ca at different life history stages. The analysis results showed that sodium (Na), magnesium (Mg), iron (Fe), strontium (Sr), and Barium (Ba) were the effective elements in four stocks. Five clusters were divided according to MRT and represented five ontogenetic stages. The Sr/Ca, Ba/Ca, and Mg/Ca ratios in summer and autumn stocks were significantly different from those of spring and winter stocks (P < 0.05). From the embryonic stage to sub-adult stage, the Sr/Ca ratio in spring and winter stocks was higher than those of summer and autumn stocks. The Sr/Ca ratio in spring, summer, and winter stocks were significantly different among different ontogenetic stages (P < 0.05). The Ba/Ca ratio in the four stocks were significantly different between larva and adults (P < 0.05). Therefore, the Sr/Ca and Ba/Ca ratios can be selected as the key indicators to speculate on the migration route of U. edulis. This study improves understanding of the statolith microchemistry differences among different stocks of U. edulis. [ABSTRACT FROM AUTHOR]

The giant jellyfish Nemopilema nomurai is the largest and most dangerous jellyfish species in East Asian waters, and the N. nomurai bloom causes serious problem in coastal industries, fisheries, and tourism. In the previous surveys, we found N. nomurai could not be observed in the south of 30°N. In this paper, we analyzed the mechanism of this phenomenon. After exploring the possible impacts of different environmental factors, we found that physical processes are essential to the distribution pattern of N. nomurai rather than biological or chemical factors in the East China Sea. The combination of the location of the initial breeding places of N. nomurai and the current system determine the distribution pattern. This study could provide important insights to the potential control of the giant jellyfish in the Chinese coastal waters. [ABSTRACT FROM AUTHOR]

Phaeocystis is an important bloom-forming species and over 100 blooms have occurred since 1997 along the Chinese coasts, while only the species P. globosa was described. In this project, a total of 246 phytoplankton samples collected from the Bohai Sea, the Yellow Sea, and the East China Sea in April 2021 were analyzed to evaluate the species diversity and geographical distribution of the genus Phaeocystis based on metabarcoding 18S rDNA sequence. Four described Phaeocystis species were recognized, including P. globosa, P. pouchetii, P. jahnii, and P. cordata, and each has distinguished geographical distribution characteristics. P. globosa was the most widespread and abundant species, and P. pouchetii was found in the Bohai Sea and the northern Yellow Sea with substantially elevated abundance. P. cordata was also a widespread species, but its abundance was relatively low, while P. jahnii gathered only in the southeastern East China Sea. Water temperature, phosphate as well as ammonium contents were found to be associated with the abundance of P. globosa, P. pouchetii, and P. jahnii significantly. Moreover, two uncharacterized Phaeocystis species were detected in the Chinese seas, indicating the diversity of the genus remains underestimated worldwide. [ABSTRACT FROM AUTHOR]

Sea surface salinity (SSS) is a master variable in oceanography and important to understand marine biogeochemical and physical processes. In the East China Sea (ECS), a random forest based regression ensemble model (RF) was developed to estimate the SSS with a spatial resolution of ∼1 km based on a large synchronous data set of in situ SSS observations, MODIS‐derived remote sensing reflectance (Rrs) and sea surface temperature (SST). The model showed the best performance when the Rrs(412), Rrs(488), Rrs(555), Rrs(667), SST and Julian day (JD) were used as inputs, with a root mean square error (RMSE) of 0.84, mean absolute error (MAE) of 0.31 and coefficient of determination (R2) of 0.81 for model training (N = 4,504), and a RMSE of 0.77, MAE of 0.30 and R2 of 0.86 for the model test (N = 1,153). The accuracy of the SSS model was examined using an independent data set during the period of 2020–2022 with a RMSE of 0.66 and MAE of 0.39 (N = 2,151). The interannual and seasonal signal of modeled SSS of the ECS, showed that important drivers of variability are the Changjiang discharge and the East‐Asian monsoon. Applications of the model to other Chinese marginal seas (Yellow and Bohai seas) showed good agreement in distribution patterns when compared with the estimated SSS from NASA Soil Moisture Active Passive. Once more empirical oceanographic data is made available, this robust model can be applied to other regions retraining the model with informed local data sets. Key Points: A random forest based regression ensemble model is developed to estimate the sea surface salinity for the East China Sea from MODIS productsThe model is evaluated using an independent data set from the East China Sea and its sensitivity to input parameter errors are quantifiedThe model is successfully applied in the Chinese marginal seas, indicating it is an efficient tool to monitor the spatiotemporal variations in SSS [ABSTRACT FROM AUTHOR]

Obliquogobius trifasciatus sp. nov. (Teleostei: Gobiidae) is described on the basis of three specimens (29.5–30.5 mm in standard length) collected in the East China Sea, northwest of the Ryukyu Islands, southern Japan, in a depth of 115–124 m. The new species is characterized by the following combination of characters: 2nd dorsal and anal fins each with I, 9 rays; head moderate in size, its length 32.8–34.1% of standard length; lateral surface of nape scaled; postorbital pore G of cephalic sensory canal present; gill opening moderate in size, extending anteriorly to level with posterior margin of eye; pelvic fins united medially, with a well-developed connecting membrane (between innermost rays) and frenum (between spines); caudal fin dorsoventrally asymmetrical, lacking a distinct obliquely pointed tip, and with three lowermost branched rays much shorter than other branched rays; three broad black (dark brown in preserved specimens) bands, superposed by yellow chromatophores, on lateral surface of body, anteriormost band located under 1st dorsal-fin base, middle band just behind a vertical line through posterior end of 2nd dorsal-fin base, and posteriormost band on caudal-fin base; a small faint, yellow-tinged dusky blotch on center of caudal peduncle (between middle and posteriormost bands on body); a large black blotch, covering almost entirety of 1st dorsal fin; 2nd dorsal and caudal fins generally pale yellow, without a barred pattern. [ABSTRACT FROM AUTHOR]

The distribution patterns of the paleo-Changjiang River deltas formed during the MIS 3 period before the last glacial maximum (LGM) contain important information about the deltaic deposits in response to climate and sea-level changes. However, so far, they are still poorly understood. Here, we reconstruct the stratigraphic and chronological framework of the deltaic system based on the analysis of 1835 km of high-resolution seismic profiles obtained from the northern East China Sea, together with a comparison with the research results from four existing boreholes and three groups of published seismic profiles from the study area. Within the strata from MIS 5 to MIS 1 that are preserved on the northern shelf of the East China Sea, we discovered a large-scale paleodeltaic complex formed during the MIS 3 period. During MIS 3, sea level dropped slowly; the paleodelta formed was large in scale and was distributed between water depths of 40 and 150 m. It is now directly exposed at the seabed at a depth of more than 100 m. The paleodelta had extended from the northwest to the southeast, with maximum thickness of the deposits around 55 m. The extensions in the east–west and south–north directions both exceeded 300 km, with a total area around 1.35 × 105 km2. Since the late Pleistocene, the tectonic structure beneath the East China Sea has been relatively stable. As such, sea-level fluctuations, sediment supply, and original topography were the main controlling factors for the development of the delta. [ABSTRACT FROM AUTHOR]

Using observational and reanalysis data sets, we investigated interannual variability in the Kuroshio in the East China Sea (ECS‐Kuroshio). We exhibited that the surface velocity and position of the ECS‐Kuroshio were synchronized on a quasi‐3‐year interannual timescale during 2005–2016. We further demonstrated that: (a) during 2005–2016, wind stress curl variability related to the El Niño–Southern Oscillation (ENSO) played a leading role in the interannual ECS‐Kuroshio variability by exciting baroclinic Rossby waves along the subtropical countercurrent (STCC) zone east of Taiwan; (b) mesoscale eddy activities in the STCC zone, especially long‐lived (≥150‐day lifetime) cyclonic eddies, probably played a secondary role in the interannual ECS‐Kuroshio variability. In addition, we showed that the occurrence of the quasi‐3‐year interannual variability of the ECS‐Kuroshio since 2005 was likely linked to the following changes in the ENSO‐related atmospheric circulation: (a) The primary ENSO timescale changed from a quasi‐5‐year period in 1993–2004 to a quasi‐3‐year one in 2005–2016; (b) Over the central equatorial Pacific along with the eastern tropical Indian Ocean, the sea surface temperature in 2005–2016 varied with a more intense amplitude than in 1993–2004, which resulted in a different western North Pacific atmospheric response to the ENSO in 2005–2016 from that in 1993–2004. Plain Language Summary: The Kuroshio, which serves as the western boundary current of the North Pacific subtropical gyre, is one of the most important elements that control the oceanic and atmospheric conditions around the East China Sea (ECS). In this study, we found that the surface velocity and position of the ECS‐Kuroshio were synchronized on a quasi‐3‐year interannual timescale during 2005–2016. We further determined that, during 2005–2016, baroclinic Rossby waves along the subtropical countercurrent (STCC) zone east of Taiwan, which were excited by wind forcings related to the El Niño–Southern Oscillation (ENSO), played a leading role in the interannual ECS‐Kuroshio variability, and mesoscale eddy activities in the STCC zone probably played a secondary role. Moreover, we suggested that, since the mid‐2000s, the change of the primary ENSO timescale and the amplification of the sea surface temperature variability in the tropical ocean have led to the occurrence of the quasi‐3‐year interannual variability of the ECS‐Kuroshio through the western North Pacific atmospheric response to the ENSO. Key Points: Kuroshio in the East China Sea varied on a quasi‐3‐year interannual timescale during 2005–2016El Niño–Southern Oscillation‐related atmospheric circulation played a leading role in this interannual variability by exciting baroclinic Rossby wavesMesoscale eddy activities, especially long‐lived (≥150‐day) cyclonic eddies, probably contributed secondarily to this interannual variability [ABSTRACT FROM AUTHOR]

Methane is a greenhouse gas, and the East China Sea acts as a source of emissions to the atmosphere. On the other hand, the distribution of methane concentration in the Ryukyu Arc shelf and forearc region has not been clarified. Therefore, we investigated the continental slope and continental shelf areas from the Okinawa Trough to the landward side and the island shelf and forearc areas to the seaward side of the East China Sea. The methane concentration in the Kuroshio Current region was very low, and the methane concentration in the seawater just above the seafloor in the area directly above the hydrothermal systems was exceptionally high. In addition, methane concentration in seawater just above the seafloor where cold seeps and mud volcanoes are known is higher than the background, and higher methane concentrations were found in continental slope area and the island shelf area. The results suggest the existence of previously unreported methane sources such as cold seeps and mud volcanoes in the continental slope region and the island shelf region.

The frequency of cetacean strandings is increasing, with multiple causes identified. We examined temporal and spatial trends in stranding numbers along the coastal areas of the East China Sea from 1990 to 2021. Using structural equation models, we analyzed the relationships between strandings and climate, oceanic properties, and human activities. Our findings revealed time-dependent interannual variability in strandings but no linear trend, indicating relative stability in cetacean strandings. Seasonal patterns were observed only in narrow-ridged finless porpoises (Neophocaena asiaeorientalis), with significant spring increases (March to May). Clustering of strandings occurred in central Fujian and northern/southern Taiwan, according to spatial analysis. The impact of variables on cetacean strandings varied across time periods. Storm surges, coastal fishing, and the Pacific decadal oscillation were associated with stranding events from 1990 to 2006. However, from 2006 to 2021, the influence of storm surges weakened, while the climate index only indirectly affected strandings through sea surface temperature and salinity, with an increased intensity in the effects of winter sea surface temperature and salinity. Structural equation models unveiled the cascading effects of environmental changes on strandings. This study reports changing trends in cetacean strandings and identifies relevant variables. Although not exhaustive, understanding the reasons behind strandings enhances our comprehension of cetacean responses to environmental changes, supporting targeted conservation and management efforts. [ABSTRACT FROM AUTHOR]

The East China Sea (ECS), which is located in the transitional zone between land and ocean, is the main site for the burial of sedimentary organic carbon. Despite good constraints of the modern source to the sinking process of organic carbon, its fate in response to changes in climate and sea level since the last deglaciation remains poorly understood. We aim to fill this gap by presenting a high-resolution sedimentary record of core EC2005 to derive a better understanding of the evolution of the depositional environment and its control on the organic deposition since 17.3 kyr. Our results suggest that sedimentary organic carbon was deposited in a terrestrial environment before the seawater reached the study area around 13.1 kyr. This significant transition from a terrestrial environment to a marine environment is reflected by the decrease in TOC/TN and TOC/TS ratios, which is attributed to deglacial sea level rise. The sea level continued to rise until it reached its highstand at approximately 7.3 kyr when the mud depocenter was developed. Our results further indicate that the deposition of the sedimentary organic carbon could respond quickly to abrupt cold events, including the Heinrich stadial 1 and the Younger Dryas during the last deglaciation, as well as 'Bond events' during the Holocene. We propose that the rapid response of the organic deposition to those cold events in the northern hemisphere is linked to the East Asian winter monsoon. These new findings demonstrate that organic carbon deposition and burial on the inner shelf could effectively document sea level and climatic changes. [ABSTRACT FROM AUTHOR]

A new 3D S-velocity model for the crust and upper mantle beneath the Yellow Sea, the East China Sea, the Japan Sea, and the Philippine Sea is determined by means of Rayleigh-wave analysis for depths ranging from 0 to 400 km, and the most conspicuous features of the earth structure in this region are revealed from this model. In the depth range from 5 to 30 km, the S-velocity is principally affected by the thickness of the crust. In the areas with thin crust (oceanic crust), the highest S-velocity values are determined, while the lower S-velocity values are shown for the areas with a transitional crust. For the Japan Sea, the decrease observed in crustal thickness towards the north can be the result of the back-arc spreading that formed this sea from 32 to 10 Ma. Thus, from the four models proposed to explain the oceanic structure of this sea, the model supported by the results determined in the present study is the back-arc spreading model. For the Philippine Sea, the difference in the type of crust determined for the western part and the eastern-northeastern part is consistent with the two different theories, proposed to explain the origins of both parts of this sea. In the depth range from 30 to 60 km, the western part of the Philippine Sea shows higher S-velocity values than the eastern part, because the age of western part of this sea is greater than that of eastern part. The S-velocity difference of 0.2 km/s determined between both parts of this sea implies that the temperature difference within the lithosphere may reach ~370°C. For the western part of this sea, the controversy between the previous different lithospheric-thickness determinations is solved in the present study determining a lithosphere thickness of 90 km. The Japan Sea, the East China Sea, and Okinawa Trough are characterized by thin lithosphere, thick asthenosphere, and low S-velocities. These results and other evidence suggest that from the two models proposed to explain the formation of East Asian rifting system, the model of the back-arc spreading is the most realistic model. The asthenosphere beneath all study area has been precisely located and mapped in S-velocity, for the first time. The Pacific and Philippine Sea slabs and their corresponding mantle wedges above the slabs are also mapped with S-velocities. [ABSTRACT FROM AUTHOR]

Simple Summary: As one of the important economic fishery resources in the East China Sea, Uroteuthis edulis has attracted extensive attention from scholars around the world, but there is no relevant research on the fecundity characteristics and spawning strategies of U. edulis in the East China Sea. Therefore, this study takes the fecundity as the starting point to explore the fecundity characteristics and spawning strategies of U. edulis. Our study showed that the ovary oocytes of U. edulis mature in batches, after which the eggs are laid in batches. The dorsal mantle length (ML), water temperature at 25 m depth (T25) and sea surface height (SSH) are important indicators to measure the fecundity of U. edulis. The results of this study provide important fecundity information for understanding the population dynamics of U. edulis under the changing marine environment, and have important significance for the sustainable development and utilization of fishery resources. The fecundity characteristics and spawning strategy of Uroteuthis edulis in the East China Sea were investigated by observing the potential fecundity (PF), relative fecundity by dorsal mantle length (PFML) and relative fecundity by body weight (PFBW). The relationship between fecundity and a single biological indicator was measured, and generalized additive models (GAMs) were fit by adding environmental variables to help better understand this comprehensive relationship. The long diameter and short diameter of the ovarian oocytes ranged from 0.72 mm to 4.74 mm and from 0.46 mm to 3.67 mm, respectively. The long and short diameters of oviducal eggs ranged from 0.61 mm to 5.12 mm and from 0.39 mm to 3.81 mm, respectively. The egg diameter had a unimodal distribution. The PF, PFML and PFBW ranged from 540 to 13,743 cells, 5 to 86 cells/mm and 6 to 53 cells/g, respectively. Three fecundity indicators were unimodally distributed, and the PFBW was more stable than the PFML (δ2PFBW < δ2PFML). The fecundity and single biological indicators were fitted, and it was found that the PF and PFML were positively correlated with dorsal mantle length (ML) and body weight (BW). The generalized additive model (GAM) fitting showed that when considering the interaction between dorsal mantle length and sea surface height (M13), the deviation explanation rate of the PF and PFML was the highest. Studies have shown that the ovary oocytes of U. edulis mature in batches, and then the eggs are laid in batches. The dorsal mantle length (ML), water temperature at 25 m depth (T25) and sea surface height (SSH) are important indicators to measure the fecundity of U. edulis. These findings allow for a deeper understanding of the U. edulis population dynamics for the future management of this economically and ecologically important species. [ABSTRACT FROM AUTHOR]

Wave climate is important for marine disaster prevention and marine development. The East China Sea is open to the Pacific Ocean and is considered to be greatly affected by swells. In this study, the variation of swell height and wind-wave height distribution was examined using ERA5 reanalysis data. In addition to the EOF (Empirical Orthogonal Function) analysis, the variability of wave height anomaly was examined by SOM (Self-Organizing Map). In this study, we clarify what phenomena can be detected by both SOM and EOF or only by either of them, in the area such as the East China Sea where the influence of swells is large. Patterns of SOM arrays corresponding to the eigenvector distribution maps of the first and second modes of the EOF of wave height anomaly were identified. However, there were some patterns in the major SOM array patterns of swell height anomaly that were not found in the EOF analysis. The most major wave height anomaly distributions are particularly frequent during the summer. Both the frequency of the most frequent SOM pattern of swell height anomaly and the first mode of EOF shows an increasing trend in swell height. In the East China Sea, the increasing trend of swell heights is more prominent during certain periods. The optimal region of the wind speed anomaly pattern was determined to best link with the swell height anomaly pattern in the East China Sea. The relationship between swell height anomaly patterns and wind speed anomaly patterns in the East China Sea varies with the seasons. Some climatic indices and wave height anomaly EOF time coefficients are correlated. The correlation is particularly high between the summer ENSO index and the swell height anomaly EOF first mode. This indicates that swell heights are higher during the ENSO period. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, the complete mitochondrial genome of the Taiwan tai Argyrops bleekeri was determined for the first time by next-generation sequencing. The circular mtDNA molecule was 16,646 bp in size and the overall base composition was A (27.77%), C (28.95%), G (16.60%), and T (26.68%), with a slight bias toward A + T. The complete mitogenome encoded 13 protein-coding genes (PCGs), 22 tRNA genes, two rRNA genes, and a control region. Phylogenetic analysis based on the 13 PCGs of the Sparidae family revealed that Argyrops appears to be most closely related to Pagrus and Parargyrops, but further research is needed. [ABSTRACT FROM AUTHOR]

The intrusion of Kuroshio into the South China Sea through Luzon Strait has been of enormous interest in western boundary current studies. Here we show that this intrusion can be remotely influenced by the downstream intrusion of the Kuroshio northeast of Taiwan into the East China Sea, at a lead time of about 220 days. This remarkable finding is first revealed by a quantitative causality analysis which is rigorously established from first principles in physics; it is originally motivated by the observation of a wake southeast of Taiwan, whose influence on the loop current, also revealed by causality analysis, is traced downstream to the Kuroshio intrusion into the East China Sea. Further analysis suggests that the two important Kuroshio intrusions are connected via a coastal trapped wave mode with a period of 1.5 years propagating southward along the eastern Taiwan coast, as supported by both theoretical and numerical models. Upon approaching the Luzon Strait, its negative (positive) phase functions to intensify (reduce) the loop current. At a speed of 1.37 km day−1, the mode takes about 220 days for the disturbances northeast of Taiwan to travel along the coast to Luzon Strait, leading to the same time delay for the downstream‐upstream causal relation. Plain Language Summary: Kuroshio is the western boundary current of the North Pacific. When the Kuroshio current passes marginal seas including the South China Sea and the East China Sea, branches of the Kuroshio may penetrate into the seas, leading to the well known Kuroshio intrusions. Using a rigorous causality analysis based on information flow, we find that the Kuroshio intrusion into the South China Sea through Luzon Strait can be remotely influenced by the downstream Kuroshio intrusion into the East China Sea. Results show that the influence from the downstream intrusion first reaches a wake structure southeast of Taiwan which usually accompanies the Kuroshio intrusion into the South China Sea, then reaches the upstream intrusion. The causal relation is attributed to one mode of the southward propagating coastal trapped waves along the east coast of Taiwan. Upon approaching the Luzon Strait, its negative (positive) phase functions to intensify (reduce) the loop current, regulating the Kuroshio intrusion on a 1.5‐year time scale. Since the speed of the mode is 1.37 km day−1, it takes about 220 days to travel along the coast to Luzon Strait. As a result, the downstream‐upstream causal relation has a time delay of about 220 days. Key Points: A wake structure southeast of Taiwan usually accompanies the Kuroshio intrusion into the South China SeaInfluence of the downstream Kuroshio on the wake and further on the upstream Kuroshio intrusion is revealed by a rigorous causality analysisCoastal trapped waves are responsible for the counterintuitive downstream‐to‐upstream causal relation [ABSTRACT FROM AUTHOR]

Simple Summary: Understanding the factors that influence the behavior and distribution of creatures is essential for studying the interaction between environment and biology. In this study, we focused on the main environmental factor, water temperature, and its impact on the distribution of hairtail, a specific species. By examining the spatial limits of the hairtail's temperature range, we found that temperature alone does not fully explain its distribution. We expanded our investigation to include salinity and water depth as additional factors. The results showed that the combination of multiple factors significantly reduced the intersection range between hairtail and the defined environmental factors. This suggests that each factor contributes differently to hairtail distribution. To further explore differences in organism aggregation, future research might compare aggregated and non-aggregated variables related to specific areas of water in terms of specific factors. Moreover, we observed that hairtail distribution varied seasonally, with different levels of coverage and proximity to shore. These findings emphasize the complexity of the organism's habitats and the need for a comprehensive understanding of environmental influences. An organism's habits are formed primarily as a result of environmental circumstances. Analyzing an organism's habits and examining their causes requires a thorough understanding of the peculiarities of an organism's living environments. Analyzing the environmental factors necessary for an organism's survival is a crucial component of studying how the environment and biology interact. The favorable temperature range for the species has been discovered in previous investigations of the hairtails' main water temperature distribution range, covering both the water regions with and without the hairtails. It is implied that there may be other elements besides water temperature that also affect dispersion. The hairtail, though, is still the subject of the study. To investigate and confirm the corollaries, salinity and water depth were added as variables. We observed that the intersection of the main ranges of two environmental factors, as well as the main hairtail range of interest, were greatly reduced when compared to a single factor range; the sum of the three factors will further increase the reduction. The primary cause is that the main range of hairtail relative to each factor is incomplete, and the target bodies specified by various factors are very varied. To further investigate the factors that affect the distribution of the organism's active areas, a comparison between aggregated and non-aggregated waters relative to one factor can be done in the next step. A good sequence of environmental elements, namely temperature>salinity>water depth, is obtained in the above analysis procedure by comparing the accuracy and significance of each factor for the primary range of the hairtail. Additionally, it was noted that the main population of the hairtail covered different areas depending on the season, with less coverage in spring and autumn and greater coverage in summer and winter. The main part of the hairtail population also tended to be distributed closer to the coast in summer and winter, and farther offshore in spring and autumn. These seasonal variations may be related to the two distinct reproductive cycles of hairtail, occuring in spring and autumn. [ABSTRACT FROM AUTHOR]

The composition of marine aerosol is quite complex, and its sources are diverse. Across the East China Sea (ECS) and the Yellow Sea (YS), multi-dimensional analysis of marine aerosols was conducted. The characteristics of carbonaceous aerosols and gaseous pollutants were explored through in situ ship-based observation, MERRA-2 reanalysis datasets and TROPOMI data from Sentinel-5P satellite. Black carbon (BC)'s average concentration is 1.35 ± 0.78 μg/m3, with high-value BC observed during the cruise. Through HYSPLIT trajectory analysis, sources of BC were from the northern Eurasian continent, the Shandong Peninsula, the ECS and Northwest Pacific Ocean (NWPO). The transport of marine sources like ship emissions cannot be ignored. According to the absorption Angstrom exponent (AAE), BC originates from biomass burning (BB) in the shortwave band (~370 nm) and from fossil fuel combustion in the longwave band (~660 nm). Organic carbon (OC), sulfate (SO42−) and BC report higher Angstrom exponent (AE) while dust and sea salt reveal lower AE, which can be utilized to classify the aerosols as being fine- or coarse-mode, respectively. OC has the highest AE (ECS: 1.98, YS: 2.01), indicating that anthropogenic activities could be a significant source. The process of biomass burning aerosol (BBA) mixed with sea salt could contribute to the decline in BBA's AE. Ship emissions may affect the distribution of tropospheric nitrogen dioxide (NO2) in the ECS, especially during the COVID-19 pandemic. Tropospheric NO2 over the YS has the highest value (up to 12 × 1015 molec/cm2). Stratospheric NO2 has a ladder-like distribution from north to south, and the variation gradient was lower than that in the troposphere. Carbon monoxide (CO) accumulates in the south and east of the ECS and the east of the YS, while the variation over the eastern YS is relatively frequent. Seas near the Korean Peninsula have extremely high CO concentration (up to 1.35 × 1017 molec/cm2). [ABSTRACT FROM AUTHOR]

Spatiotemporal information is crucial for cetacean research and conservation, particularly for wide-ranging and migratory species. Sperm whales (Physeter macrocephalus) are distributed worldwide in deep oceans; however, little is known about the species in the western margin of the Pacific Ocean. Here, we examined the available information related to the occurrence, distribution, and potential habitats of sperm whales in the waters off China. Historical whaling information (18th-20th century) indicates that sperm whales have been captured in the East China Sea (ECS) and South China Sea (SCS). Furthermore, sporadic strandings have been recorded since the 1910s, and more frequently from 1990 onwards. Since 1990, accidental sightings have been documented in the eastern ECS, northeastern and southern SCS, and their adjacent waters. More recently (2019-2022), field encounters have been reported in dedicated ship-based investigations in the Xisha and Nansha waters, providing robust evidence of the regular existence and potential residency of sperm whales in the northwestern and central areas of the SCS. Female nursery groups suggest that the Xisha waters might be an important nursing ground for sperm whales. Satellite tracking data from four adults showed that sperm whales in the SCS might display both fine-scale and long-distance movements. Taken together, it appears that sperm whales are currently active in the waters off China, and that deep waters (depth >200 m) in the ECS and SCS may provide the species with critical habitats. This review provides crucial baseline information on sperm whales in the waters off China, which may help to facilitate future research efforts and conservation initiatives for the species at national and cross-regional scales. More field investigations and other monitoring approaches including acoustic monitoring, biologging, photo-identification, and genetics are required to reveal the distribution, movement, and habitat use patterns of sperm whales in these waters. [ABSTRACT FROM AUTHOR]