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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]

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]

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]

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]

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]

Uroteuthis edulis (Hoyle, 1885) was one of the important loliginid squid resources in the East China Sea. This species has a complex population structure and a wide range of migration. Statolith trace elements were widely used in the study on individual life history and the reconstruction of habitat. In this study, the trace elements in the statoliths of the four seasons cohorts of U. edulis in the East China Sea were determined with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The clustering analysis on the trace element ratios in different growth stages was carried out with Euclidean distance method and the optimal relationship between trace element ratios and water temperature was established to predict and calculate the areas and probability of potential habitats. The ratios of Mg:Ca, Sr:Ca, and Ba:Ca in each stock firstly decreased, then increased, and reached the minimum values in the sub-adult stage. The spring and winter stocks were clustered into one group, whereas the summer and autumn stocks were clustered into one group. There were significant differences in the ratios of Mg:Ca, Sr:Ca, and Ba:Ca among the clustering group (P < 0.05). The calculation results of the models indicate that hatching water temperatures of the winter–spring and summer–autumn stocks were, respectively, 19.34 to 23.91°C (55 m) and 15.91 to 19.43°C (25 m). The winter–spring stock hatched in the waters of northeastern Taiwan and the paralarva migrated to the northeastern seas along the Kuroshio Branch Current in the western continental shelf of the East China Sea and the Taiwan Warm Current. The summer–autumn stocks hatched in the waters of Zhoushan, Zhejiang of China, and the paralarva migrated to the central East China Sea under the influence of the Yangtze River, and then followed the Taiwan Warm current to reach the northeastern waters for feeding migration. This study provides the basis for revealing the migration mechanism and strategy of U. edulis. [ABSTRACT FROM AUTHOR]

Extreme oceanic environments such as shallow hydrothermal vents (HVs) have rarely been investigated with respect to their impact on the water column and its organisms, such as zooplankton. We collected mesozooplankton from the near shore shallow HV areas off northeast Taiwan during three distinct monsoonal periods in 2022. The results showed the occurrence of 99 copepod species belonging to 24 families and 49 genera from a one-year study. The results from similarity percentage (SIMPER) and indicator species analysis (IndVal) identified that top 5 species namely Temora turbinata, Oncaea venusta, Clausocalanus furcatus, Macrosetella gracilis, and Canthocalanus pauper showed variations in their abundance between HV and non-HV sites which contributed to 72.12 % dissimilarity with only four of the species with significantly higher contributions during the SW monsoon season. This distinction is explained by the fact that copepods were negatively affected by HV water. Furthermore, Temora turbinata (3530.7 ± 4967.83 ind. m -3 ), Calanus sinicus (70.86 ± 163.78 ind. m -3 ), and Paracalanus parvus (40.47 ± 85.67 ind. m -3 ) emerging as the dominant species with a clear seasonal succession pattern during the southwest monsoon, northeast-southwest monsoon transition, and northeast monsoon prevailing phase, respectively. The total abundance of copepod was significantly higher during the southwest monsoon than during the other two monsoonal periods (p < 0.01, one-way ANOVA). In contrast, the number of species and the richness index were significantly higher during the northeast-southwest and northeast monsoon than during the southwest monsoon period (p < 0.05, one-way ANOVA) indicating temporal succession in the copepod community., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have influenced the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Breaking internal tides and induced mixing are critical to shelf dynamics, including heat and mass exchanges. Spatiotemporal variability of internal tides and modulation factors for the southern East China Sea shelf were examined based on a combination of a three-month mooring velocity and satellite altimeter data. Semidiurnal and diurnal internal tides exhibited distinct temporal trends, with the semidiurnal internal tides enhanced by an order of magnitude during the latter half of the record, while the diurnal internal tides followed quasi spring-neap cycles with a generally stable intensity except for two specific periods of strengthening. These internal tides probably originated remotely over the shelf-slope area northeast of Taiwan. Time-varying stratification was the most important factor for the internal tidal magnitude. In addition, varying background currents influenced the diurnal critical latitude band, which explains the slightly enhanced diurnal internal tides during the two periods. Although both semidiurnal and diurnal internal tides were mode-1 dominated, the semidiurnal internal tides were surface intensified while the diurnal tides were bottom intensified. The proportion of higher mode internal tides increased during robust eddy activities. Stronger background vertical shear corresponded to high-frequency events and energy transfers from tidal frequencies to high frequencies associated with turbulent mixing. [ABSTRACT FROM AUTHOR]

To understand the effects of variable water masses in the northeastern East China Sea (Korea South Sea), planktonic copepods were seasonally sampled. Out of a total of 106 copepod species, 85 were oceanic warm-water species, and the number of species varied in summer, autumn, spring, and winter. The study area was divided into two or three regions according to the degree of influence of the water masses. Canthocalanus pauper, Clausocalanus furcatus, Oithona plumifera, Oncaea venella, Oncaea venusta, and Paracalanus aculeatus showed a positive correlation with water temperature and salinity and were indicator species of warm currents. Calanus sinicus, known as an indicator species of the Yellow Sea Bottom Cold Water, showed a high abundance and occurrence ratio in the western sea of the study area from spring to autumn. Moreover, Acartia pacifica indicated the extension of coastal waters to offshore areas. Several oceanic warm-water species (A. danae, Centropages gracilis, Labidocera acuta, Rhincalanus nasutus, and Temoropia mayumbaensis) were considered indicator species of the Taiwan Warm Current. Our results suggest that the spatiotemporal distribution patterns of indicator species are partly explained by different water masses. [ABSTRACT FROM AUTHOR]

Greater amberjack (Seriola dumerili) is an important fishery resource with a circumglobal distribution from tropical to temperate waters. Here, we investigated the spawning migration and habitat utilization of S. dumerili in the East China Sea (ECS). Archival tags were attached to 22 adult fish to examine their horizontal and vertical movements and estimate the spawning ground. S. dumerili were captured and released in the coastal waters of eastern Taiwan on November of 2016 and 2017. Information from seven pop‐up satellite archival tags and seven depth–temperature recorders was recovered. Almost all of the fish stayed in the Taiwanese exclusive economic zone. Most individuals moved from released site to the southern edge of the ECS and showed behavior associated with the topographic features in winter (November to December). These phenomena may be related to foraging and be driven by oceanographic features such as the seasonal monsoon and the Kuroshio. The fish then migrated to the south offshore area of Taiwan in January and February. During their southward migration, the fish experienced a slowly elevated water temperature regime (SETR), which is one of the environmental factors that induce final oocyte maturation. In the spawning season (February to April), tagged females exhibited continuous diel vertical movements (DVMs) after experiencing the SETR. These continuous DVMs were observed over a wide geographic range from north to south in the Kuroshio off eastern Taiwan. Our study demonstrated that the putative spawning ground of S. dumerili must extend further in a north–south direction than predicted in a previous study. [ABSTRACT FROM AUTHOR]

Perfluoroalkyl substances (PFASs) have become an important class of global environmental contaminants, yet their vertical profile in the marine water column is still less understood, especially for the semi-closed seas. In this study, the contamination level and spatial distribution of 8 PFASs were investigated in both surface and vertical water samples from two semi-closed seas, the Japan Sea and the Mediterranean Sea. Similar levels and compositions of PFASs were found between these two seas. The vertical profile of PFASs in the Mediterranean Sea was variable while that was relatively steady in the Japan Sea, probably due to their different pollution sources. The accumulation rate of PFASs from the East China Sea to the Japan Sea was calculated, for which perfluorooctanesulfonic acid and perfluorooctanoic acid were found to have high accumulation potency in both surface and deep water; most of the investigated PFASs were accumulated in the deep water due to the long residence time while they were more likely to escape to the Pacific Ocean in the surface water. This work aimed (i) to study the distribution of PFASs in both surface and vertical water samples in two semi-closed seas, namely the Japan Sea and for the first time the Mediterranean Sea, (ii) to assess the temporal trend in the Japan Sea, and (iii) to firstly investigate the potential transport of PFASs from the East China Sea and Taiwan Strait in order to estimate the inventory of PFASs in whole water mass in the Japan Sea. Image 1 • A remarkable increase in PFASs levels was found in the Japan Sea from 2005 to 2010. • The inventory of PFASs in whole water mass was firstly assessed in semi-closed sea. • The annual ΣPFASs inflow from the East China Sea to the Japan Sea was around 70.8 t. • The PFASs vertical profile in the Mediterranean Sea implied a few pollution sources. • PFOA predominated in the Japan Sea, the Mediterranean Sea, and the East China Sea. [ABSTRACT FROM AUTHOR]

In coastal regions, typhoons are one of the most frequent natural disasters, and instrumental data indicate that they can greatly boost marine primary productivity. Typhoons' long-term ecological repercussions, however, are still little understood. To investigate the ecological effects of typhoons since the mid-Holocene, we focused on the sediment cores in the East China Sea, with key parameters of organic C N and Bio-Si to reveal the paleo-productivity variation. Over a millennium, the occurrence of El Niño-Southern Oscillation (ENSO) has had a substantial impact on primary productivity in the southern East China Sea. The primary productivity in the southern East China Sea was risen by humid climate conditions in ∼3.0–2.0 ka and frequent typhoons in 1.5–0 ka. With a millennial period, ENSO frequency has been significantly influencing primary productivity in the southern East China Sea since the mid-Holocene. During 1.5–0 ka, frequent ENSO events have led to more frequent typhoons, which caused terrestrial materials input and water vertically mix in the southern East China Sea, ultimately increasing primary productivity. Particularly on a centennial time scale, ENSO phases determined how much primary productivity was increased, and this magnitude was bigger during the La Niña-like periods than it was during the El Niño-like periods since La Niña is when typhoons occur more frequently. During the Little Ice Age, the cold climate hindered the reproduction of phytoplankton, but increased human activities in Taiwan resulted in more soil erosion and the supply of terrestrial-derived nutrients into the sea, then amplified the typhoon-induced increase in primary productivity. As a result, this stage showed the highest primary productivity since the mid-Holocene. This study reveals that frequent typhoons promote marine primary productivity on centennial-millennial timescales and emphasizes that human activities amplify the ecological effect of typhoons in recent centuries. [Display omitted] • Frequent typhoons caused by ENSO led to higher primary productivity in the southern East China Sea during 1.5–0 ka. • The La Niña periods exhibited higher primary productivity than the El Niño periods in the southern East China Sea. • The anthropogenic activity amplified the typhoon-induced rise in primary productivity during the Little Ice Age. [ABSTRACT FROM AUTHOR]

Cross-shelf transport is an important material exchange process between the shelf seas and open seas. The distribution characteristics of phytoplankton, surface sediment particle size, minerals, etc., all indicate the possible existence of a cross-shelf transport conduit from the inner shelf to the outer shelf off northern Taiwan. This study confirmed cross-shelf transport off northern Taiwan based on remote sensing sea surface temperature (SST) data and heat flux data, which can be divided into two patterns: cold eddy and cold water tongue. Furthermore, combined with AVISO sea surface level data, CCMP wind field data, the dynamic formation factors of different morphological characteristics of cross-shelf transport are studied. Topographic changes mainly induce cross-shelf transport off northern Taiwan and occur at the curve of isobath to deep water. When there is a strong thermal front along the coast, cross-shelf transport is more likely to occur. Against the steady, strong northerly wind, the Zhe-Min coastal current's southward flow and Kuroshio's invasion strengthened the temperature front and facilitated cross-shelf transport. Typhoon strengthened cross-shelf transport over northern Taiwan after passing through the southern part of the study area. This research has important implications to find the channel and transporting pattern for material exchange between the East China Sea and the West Pacific, which will contribute to the study of ecological environmental protection and seabed muddy area formation. • Confirmed the cross-shelf transport off northern Taiwan. • Dynamic formation factors of cross-shelf transport investigated. • Topographic changes mainly induce cross-shelf transport. • Typhoon Soulik strengthened cross-shelf transport. [ABSTRACT FROM AUTHOR]

Euphausiids are commercial fishery targets and one of the primary preys of an important component of marine food webs. However, knowledge about the natural life history of euphausiids in the East China Sea is limited. To describe the seasonal variation of euphausiids abundance, diversity, life stage, and taxonomic composition, we visited a site northeast of Taiwan (25.5°N, 121.9°E) in 21 cruises from May 2010 to September 2016. This site is known for an all-year-round upwelling due to the impingement of Kuroshio onto the continental shelf break. We found that the overall euphausiids abundance and diversity tended to be higher in summer to autumn (June to November) compared with spring. In terms of life stages, we found that larval stages (furcilia and calyptopis) predominated in spring when upwelling was prominent, while post-larval stages (juvenile and adult) dominated in summer and autumn when upwelling was weak, and stratification was strong. Moreover, we found that, in spring and summer, Euphausia nana was the dominant species accounting for 90% of total euphausiid abundance, whereas in autumn, Pseudeuphausia latifrons was the dominant species occupying 36% of total abundance. This study provides the foundation to better understand the ecological roles of euphausiids under the influences of upwelling northeast of Taiwan. • The euphausiid abundance and diversity tended to be higher in summer to autumn. • The euphausiids larval stages predominated in the winter/spring season. • The euphausiids post-larval stages predominated in the summer and autumn season. • Euphausia nana account for 90% of total euphausiid abundance in spring and summer. • Pseudeuphausia latifrons occupied 36% of abundance in autumn. [ABSTRACT FROM AUTHOR]

Understanding fish's spatial behaviors are important for conservation biology under global warming, as one of the direct responses of fish to climate change is the alterations in distribution. We chose Trichiurus japonicus , which is an ecologically and economically important species in the East China Sea (ECS), to study the vicennial responses of demersal fish to climate change. Eight environmental variables (sea bottom temperature, sea bottom salinity, chlorophyll-a concentration, sea surface height, bathymetry, distance to the coast, slope data, and Terrain ruggedness index) combined with the annual survey data were fitted using integrated nested Laplace approximations and stochastic partial differential equations approach under the Bayesian framework to investigate its distribution shifts in spring during 1999–2019. Based on the distribution model, three spatial behavior indicators (center of gravity, Inertia, and Isotropy) were calculated and correlated with six regional climate indicators (Kuroshio index, Taiwan Warm Current Water index, meridional wind, zonal wind, Pacific Decadal Oscillation, and El Niño/Southern Oscillation) to study the potential cause of its spatial behaviors. During the study periods, the biomass of T. japonicus declined gradually, with a brief increase in 2003, 2007–2008, and 2015–2017. T. japonicus preferred high salinity, warm and deep-water area. The relatively persistent hotspots of T. japonicus in spring were in the offshore waters of eastern Zhejiang Province. The change in the center of gravity during the study periods was not obvious, which implied that the distribution shifts were not necessarily vulnerable for T. japonicus in response to climate change and it has strong adaptability to the environment. We also found that strong Kuroshio Current and Taiwan Warm Current Water as well as cold phased of El Niño/Southern Oscillation were accompanied by weakened spatial aggregation of T. japonicus. Overall, for these types of fish with relatively persistent hotspots, the establishment of seasonally protected areas will contribute to the sustainable utilization of the species. • 20-year-long and almost uninterrupted temporal data were used to develop a distribution model for Trichiurus japonicus in the East China Sea. • T.japonicus preferred high salinity, warm and deep-water area in Spring. • Three spatial indicators showed the spatial behaviors of T.japonicus in spring were mainly affected by wind field, TWC, KI, and ENSO. • T. japonicus has strong adaptability to the environment and its the responses to climate change especially in distribution shifts are not necessarily vulnerable. • Our results have important implications for future fisheries management strategies. [ABSTRACT FROM AUTHOR]

Although much evidence points to a Late Mesozoic large silicic igneous province in SE South China (SESC), diverse Andean-type and non-Andean-type models have been proposed to explain its origins. New age, isotope, and trace element data on zircon from wells in East China Sea (ECS) and offshore-onshore tectonomagmatic comparisons allow reassessment of the geodynamic interactions (ca. 200–86 Ma) between the Cathaysia-based arc and intraplate activity from a large mantle wedge framework. In region, remnants of the West ECS arc, Ryukyu-Taiwan mélange, and SESC intraplate define a trench–arc–intraplate architecture. Changes in arc magmatic states (flare-ups and lulls; high U/Yb, low T , variable εHf (t)) permit identification of a cycle of arc initiation, thickening, decline, arc-root removal, and arc migration, highly correlating with changes of Izanagi subduction beneath East Asia. Voluminous intraplate silicic magmatism operated in response to the slab stagnation dynamics: slab dehydration, lithospheric delamination, fluid-fluxed crustal anataxis, and crustal–mantle melt hybridization in crustal hot zones. Such geodynamic scenarios, unlike an Andean-type continental margin, instead result in the construction of a Late Mesozoic Cathaysian-type active continental margin. • A model of non-Andean-type Cathaysian continental margin is proposed based on offshore-onshore tectonomagmatic correlations. • The model reveals a link between the arc, intraplate, and slab subduction systems from the large mantle wedge perspective. • Drilled data confirm the western East China Sea and Cathaysia domains sharing a unified Paleoproterozoic Cathaysian basement. [ABSTRACT FROM AUTHOR]

The seasonal mean and synoptic fluctuation of the wintertime Taiwan Warm Current (TWC) were investigated using a well-validated finite volume community ocean model. The spatial distribution and dynamics of the synoptic fluctuation were highlighted. The seasonal mean of the wintertime TWC has two branches: an inshore branch between the 30 and 100m isobaths and an offshore branch between the 100 and 200m isobaths. The Coriolis term is much larger than the inertia term and is almost balanced by the pressure gradient term in both branches, indicating geostrophic balance of the mean current. Two areas with significant fluctuations of the TWC were identified during wintertime. One of the areas is located to the north of Taiwan with velocities varying in the cross-shore direction. These significant crossshore fluctuations are driven by barotropic pressure gradients associated with the intrusion of the Taiwan Strait Current (TSC). When a strong TSC intrudes to the north of Taiwan, the isobaric slope tilts downward from south to north, leading to a cross-shore current from the coastal area to the offshore area. When the TSC intrusion is weak, the crossshore current to the north of Taiwan is directed from offshore to inshore. The other area of significant fluctuation is located in the inshore area between the 30 and 100m isobaths. The fluctuations are generally strong both in the alongshore and cross-shore directions, in particular at the latitudes 26.5 and 28° N. Wind affects the synoptic fluctuation through episodic events. When the northeasterly monsoon prevails, the southwestward Zhe-Min coastal current dominates the inshore area associated with a deepening of the mixed layer. When the winter monsoon is weakened or the southwesterly wind prevails, the northeastward TWC dominates in the inshore area. [ABSTRACT FROM AUTHOR]

This study investigated long-term interannual changes in summer circulation and hydrology in the East China Sea (ECS) by performing 35-year high-resolution ocean model simulation from 1981 to 2015. The sea surface temperature (SST) warming trend was considerably weaker in summer than in winter. To the east of the Yangtze Estuary, the interannual variation of SST in summer was mainly dominated by horizontal advection associated with variations in the Taiwan warm current and heat flux in the offshore region north of the Yangtze Estuary. Baroclinic circulation during summer played a crucial role in subsurface mixing. Near the surface, the significant atmospheric wind mode (EOF1) and Kuroshio mode (EOF2) dominate interannual variations in ocean circulation. In the subsurface, local wind around the Tsushima Strait dominated the interannual ocean variation. Anomalous northeasterly winds induced a southwestward pressure gradient due to topographical confinement. These anomalies propagated to the south along the continental shelf through topographic Rossby waves. This study identified two types of anomalous features based on combinations of surface and subsurface EOFs. The combination represents an in-phase contribution between wind and Kuroshio forcings and between the surface and subsurface circulation that enhances the hydrological variability in the ECS. The implication on the relevant biogeochemical and ecological studies in the East China Sea is also very crucial at the interannual time scale. • Surface flow anomalies associated with wind and Kuroshio are represented by EOFs. • Subsurface EOF1 is associated with combined effects of wind stress and Kuroshio. • Hydrological changes associated with wind and Kuroshio anomalies are clarified. [ABSTRACT FROM AUTHOR]

The Kuroshio inflow northeast of Taiwan Island plays an important role in the heat and nutrient balances over the East China Sea (ECS). Based on merged satellite altimeter data and the PCM-1 mooring observation at the East Taiwan Channel (ETC), the study employs a correlation iteration scheme to find the optimal transport index for the Kuroshio inflow. The sea level difference with the highest correlation to the ETC transport is across the ECS shelf break rather than along the PCM-1 line. The counter-intuitive result is caused by large signal noise and poor track coverage of altimeters near the Taiwan coast. The optimal altimetric index is highly correlated with the two-year in-situ measurements as well as the ten-year output of the global assimilation model. It serves as a better estimator of Kuroshio inflow than those using tidal gauge data, and helps pinpoint a 5 cm mismatch of mean sea level in the Keelung tidal record. The mean transport of Kuroshio inflow based on the twenty-year altimetric index is 20.55 Sv with a standard deviation of 3.05 Sv. Wavelet spectrum of the index reveals that semi-annual period dominates the Kuroshio variation northeast of Taiwan Island. [ABSTRACT FROM AUTHOR]

The Changjiang (i.e., Yangtze River) distal mud is a typical region for studying source-to-sink systems in the world. The coupling between climate change and the sedimentary system evolution of the Changjiang distal mud since the Holocene is widely debated. In this study, based on a 14C chronological framework, we investigated the sedimentary system evolution of the Changjiang distal mud since 8 ka. The provenance identification and climate conditions indicated that the climate oscillation largely determined the sediment source-to-sink processes. The sedimentary system was controlled by monsoon system oscillation from 8 to 3 ka. Specifically, during 8–5.4 ka, the prevailing Indian and east Asian summer monsoons increased the sediment flux to the Changjiang distal mud, and the proportion of the Changjiang sediments increased across the entire Changjiang distal mud. Notably, the southern regions were significantly influenced by western Taiwan rivers. Additionally, the prevailing east Asian winter monsoon enhanced the Zhejiang-Fujian coastal current, resulting in the deposition rates increased in south while declined in north. During 5.4–3.0 ka, the summer monsoon systems attenuated, causing decreased sediment discharges from the Changjiang and Taiwan, and the deposition rates declined across the entire Changjiang distal mud. In the southern regions, the intensified Taiwan warm current increased the proportion of Taiwan sediments. Since 3 ka, the monsoon system has become stable, and anthropogenic activities in south China have increased remarkably. The anthropogenic activities resulted in increased Changjiang sediments and rose deposition rates across the entire Changjiang distal mud. During 1.2–0 ka, the frequent floods in the Changjiang basins and typhoons in Taiwan, caused by increased El Niño–Southern Oscillation (ENSO) frequency, resulted in provenance fluctuation at the Changjiang distal mud. In addition, the attenuated east Asian winter monsoon caused a northward depocenter shift, which was reflected in spatially different deposition rates, i.e., retained high values in the north but declined in the south. Our findings emphasized the dominant roles of different climatic factors in different stages, and enhance our understanding of the east Asia land-ocean interactions and the relationships among the Earth's spheres since the mid-Holocene. • Sedimentary system of Changjiang distal mud displayed spatiotemporal difference. • The monsoons controlled sedimentary system of Changjiang distal mud before 3 ka. • Human activity has led to increased sediment supply from Yangtze River since 3 ka. • The frequent ENSO resulted in fluctuant provenance in the Changjiang distal mud. [ABSTRACT FROM AUTHOR]

An upwelling center has been frequently observed on the shelf break of the East China Sea (ECS) off northeastern Taiwan, where the Kuroshio encounters an abrupt shoaling topography. The region is also located under the track of Asian dust (AD) storms and frequently disturbed by typhoons. To examine the seasonal nutrient dynamics of the upwelling and the potential impacts of these episodic events, transect stations across the upwelling center were visited at intervals of 1–3 months from November 2003 to January 2005. The results of the water temperature profiles indicated that the upwelling persisted throughout the year with the most intensified events occurring in winter. Seasonally, a higher nitrate concentration was observed during the stronger upwelling period. The highest nitrate value was however observed during an AD storm, with an average value of 8.3 μM for the top 30 m. Interestingly, the N/P ratio was larger than 16 during these episodic events, and the N/P ratios were equal to or smaller than 16 during other periods. On average, the estimated values from wet deposition constituted 17.3% of the total estimated nitrogen input. This suggests that atmospheric deposition, particularly during the episodic events, might be an important external nutrient source. [ABSTRACT FROM AUTHOR]

The East China Sea offers rich fishery resources and is a very important fishing ground for both Taiwan and Japan. However, both parties have claimed 200-nautical-mile Exclusive Economic Zones (EEZ) consistent with the United Nations Convention on the Law of the Sea, resulting in overlapping EEZ claims. Additionally, an issue of disputed sovereignty exists with regards to the eight uninhabited Islands between Taiwan, Japan and China in the southern part of the East China Sea, a situation further complicated by the fact that Taiwan and Japan have no formal diplomatic relations. Against this context, Taiwan and Japan have chosen to shelve their territorial disputes and address their fisheries conflict by signing a fisheries agreement in 2013, with the hope of resolving, or at least managing, the fisheries dispute within their shared waters. This paper aims to provide the analysis of the fisheries dispute caused by overlapping EEZs between Taiwan and Japan, the challenges encountered during the two sides׳ fishery negotiations, as well as the scope and the significance of the fisheries agreement signed by Taiwan and Japan. [ABSTRACT FROM AUTHOR]

The East China Sea remains a Sino–U.S. hotspot. The welcome diminishment of the possibility of an East China Sea conflict over Taiwan has been offset by the emergence of the Senkaku/Diaoyu Islands dispute between Japan and China as the new Sino–U.S. flashpoint. The United States could become militarily involved if China and Japan come to blows over sovereignty. Washington officially takes no position on the disputed sovereignty claim but, because the uninhabited islands are under Japanese administrative control, the Mutual Security Treaty with Japan would apply. There is no obvious road to resolution since Tokyo argues that its claim is “indisputable” and, as a result, does not want to discuss the sovereignty question, while China does everything short of actually seizing the islands to demonstrate that sovereignty is, indeed, in dispute. The possibility of an accident between the two countries’ coast guards or air forces is real. [ABSTRACT FROM PUBLISHER]

Quantitative calculation of the supply ratio of nutrients by different water masses suggests that the intrusion of Kuroshio subsurface water (KSSW) may indeed be an important factor in the formation of harmful algal blooms (HABs) in the Min-Zhe coastal area. This region in China has a complex hydrographic structure as well as a high incidence of HABs. The results of the calculations of the dissolved neodymium and its isotopes show that KSSW is an important provider of dissolved inorganic nitrogen (30–90 %) and phosphates (80–100 %) compared to the cases of the Taiwan Warm Current and the Changjiang Diluted Water. Sensitivity analysis results indicate that the percent contribution of KSSW in volume increased to 50–60 % in June, supplying favorable conditions for the growth of harmful algae. Our study implies that the invasion of the Kuroshio is likely to be a driving factor of HABs and, accordingly, a key factor in predicting HABs. [Display omitted] • An isotope model was applied to evaluate the supply ratio of nutrients by water masses. • KSSW is an important provider of dissolved inorganic nitrogen and phosphates. • Contribution of nutrients from the TWC can be neglected although it is a key water mass in spring. • Kuroshio is likely to be a driving factor for HABs in the East China Sea. [ABSTRACT FROM AUTHOR]

This study investigated copepod assemblages in the regime around Turtle Island off northern Taiwan to trace South China Sea water (SCSW) flowing northward with the Kuroshio Current. Seasonal variations of copepod assemblages demonstrated a dynamic succession of changes in copepod populations; the average abundance for total copepods ranged from 102.58 ± 53.38 in December to 1669.89 ± 1866.17 in March (individuals m). A total of 87 copepod species representing 36 genera and 21 families were identified. Among all samples, Temora turbinata dominated the copepods by a relative abundance (RA) of 26.89 %, followed by Paracalanus parvus (RA: 22.34 %) and Corycaeus ( Ditrichocorycaeus) affinis (RA: 12.77 %). Only the Acrocalanus gracilis species was recorded in all samples. Results of one-way ANOVA revealed that the number of copepod species, indices of richness, evenness, and Shannon-Wiener diversity differed significantly in five different cruises. The density of five copepod species ( Gaetanus minor, Calanus sinicus, Eucalanus elongates, Rhincalanus nasutus, and Rhincalanus rostrifrons) exhibited a significant negative correlation with seawater temperature. In contrast, the density of Canthocalanus pauper and Undinula vulgaris was significantly positively correlated with seawater temperature. The cold-water indicator species, C. sinicus, recorded in samples of March and May indicated the effect of China Coast Water (CCW) on copepod communities in the study area. Furthermore, the presence of Calanoides philippinensis in May samples strongly indicated that the SCSW may reach the Turtle Island area. Consequently, C. philippinensis and C. sinicus can be used to trace SCSW and CCW, respectively, in the study area. [ABSTRACT FROM AUTHOR]

During the last two decades, large-scale high biomass algal blooms of the dinoflagellate Prorocentrum donghaiense Lu have occurred frequently in the East China Sea (ECS). The role of increasing nutrient concentrations in driving those blooms is well-established, but the source population that initiates them is poorly understood. We hypothesized that the front of Taiwan Warm Current (TWC) may serve as a ‘seed bank’ that initiates P. donghaiense blooms in the ECS, as the physiochemical conditions in the TWC are suitable for the growth of P. donghaiense. In order to test this hypothesis, two surveys at different spatio-temporal scales were conducted in 2010 and 2011. We found a strong correlation in space and time between the abundance of P. donghaiense and the TWC. The spatial extent of the P. donghaiense bloom coincided with the TWC front in both 2010 and 2011. During the early development of the blooms, P. donghaiense concentration was highest at the TWC front, and then the bloom mass shifted inshore over the course of our 2011 survey. The TWC also moved inshore, albeit after the appearance of P. donghaiense. Overall, these results support our hypothesis that P. donghaiense blooms develop from the population at the TWC front in the ECS, suggesting the role of the ocean current front as a seed bank to dinoflagellate blooms. [ABSTRACT FROM AUTHOR]

Time series of landings may provide information crucial to achieving a better understanding of temporal variations in the abundances and compositions of exploited species and ecosystems. The waters off northern Taiwan, located in the southern East China Sea, are one of the most important fishing grounds for Taiwan's coastal and neritic fisheries. Temporal variations in the abundances of the species exploited in this region are rarely studied because of the multi-gear fisheries involved. In this study, trends in the landing per unit effort (LPUE) time series for 13 trawl-targeted species (groups) off northern Taiwan from 1976 to 2007 were explored using dynamic factor analysis (DFA). Potential effects of fishing effort (number of vessels) and environmental factors [Southern Oscillation Index, sea surface temperature (SST) near northern Taiwan, and river discharge] were examined. The optimum DFA model included three common trends and three explanatory variables (excluding SST). A general decreasing pattern was identified from among the common trends, and this was observed in the LPUE time series for most of the species. Fishing effort is an important explanatory variable in the model, suggesting that it plays a critical role in explaining LPUE variations of trawl-targeted species. The common trends identified here could lead to new strategies for fisheries management, particularly where multi-gear fisheries operate and multiple species are targeted. [ABSTRACT FROM AUTHOR]

Adult Japanese anchovies ( Engraulis japonicus) migrate from the East China Sea to the coastal region of Taiwan to spawn around late winter and early spring and, later, their larvae constitute important fisheries in Taiwan. However, their migration route and its mechanism remain unclear. To investigate their spawning migration, we used a coupled fish behavior-hydrodynamic modeling approach. The physical field is simulated by the Pacific Ocean adaptation of the TaIwan Multi-scale Community Ocean Model (TIMCOM) and the fish migration by Lagrangian tracer tracking with the aid of approximation of fish swimming behavior. We investigated three fish behavioral scenarios: (i) passive tracking of the current, (ii) swimming along with the current, and (iii) swimming along with the current and then changing to swimming toward the optimal spawning temperature. The comparison with and without Changjiang discharge is used to investigate the impacts of discharge reduction due to the Three Gorges Dam. Our results suggest that spawning migration of Japanese anchovy from the East China Sea to Taiwan may be aided by the China Coastal Current and that adult anchovies cannot reach the spawning site by passive advection alone. Thus, the swimming behavior of anchovies is crucial during the spawning migration, as it provides extra velocity and the orientation to the favorable spawning grounds. In addition, the adult anchovy is unlikely to reach the coastal area of Taiwan without Changjiang discharge. Our findings indicate that a coupled fish behavior-hydrodynamic model can help understand the influences of physical environment on the migration of Japanese anchovies. [ABSTRACT FROM AUTHOR]

River in the East China Sea (ECS), using a regional ECS model. Comparison between the results for 1996 and 1998 clearly shows that the summer monsoon winds play a significant role in spreading the freshwater discharge offshore and determining the dispersal of freshwater in the ECS. Analysis of 10-year simulation demonstrates that a northeastward freshwater transport to Jeju Island across the northwestern shelf of the ECS dominates during the summer period due to the surface Ekman flow by the southeasterly along-shore wind. Meanwhile, there is virtually no relationship between the amount of the summer discharge and the freshwater pathway toward Jeju Island. Our analysis also suggests that when the summer wind is relatively weak, another freshwater pathway toward the central ECS appears with the ambient along-shelf current between the Taiwan Strait and the Korea Strait. [ABSTRACT FROM AUTHOR]

Abstract: Typhoon Morakot, which first made landfall in central Taiwan on Aug. 7th and then in Fujian on Aug. 9th after crossing through the Taiwan Strait was the strongest typhoon to impact the East China Sea (ECS) in 2009. Two surveys were conducted, respectively on Aug. 1st and Aug. 12th, in the mud deposition center off the Zhejiang–Fujian coast to study the impacts of the typhoon on the marine environment and sediment transport. Continuous in-situ hydrographic data (water temperature, salinity, depth and turbidity) were recorded at 29 stations during the first survey and 23 stations during the second survey. The water and surface sediment samples were collected at the same time. A comparison of the measurements from the two surveys shows that significant variations in temperature, salinity and turbidity distributions occurred in the water column. The upper water layer was well-mixed after the passage of Morakot. The water temperature and salinity dropped approximately 0.2–1.4°C and 0.3–3.3psu, respectively, while the water turbidity increased from less than 1FTU to 1–30FTU. In the bottom layer, the temperature increased approximately 2.5–4.0°C, and the salinity dropped approximately 0.2–0.6psu due to the water mixing. The water turbidities generally increased to greater than 50FTU (greater than 150FTU in some locations), which were several times to more than tenfold greater than those in the first survey, which were generally between 10 and 60FTU. The thermocline, which existed at a depth of approximately 10m during the first survey, disappeared after the typhoon. A halocline appeared at approximately 10m depth in the near-shore area due to abundant fresh water supply, whereas the salinity was generally homogeneous during the first survey. Concurrently, the relatively warm and fresh water extended downward to the whole medial water layer due to the water mixing. The turbidity and volume of the bottom turbid layer was greatly increased at the second survey compared with the first survey. The intrusion of the low-temperature and high-salinity deep water (below 50m depth) was significantly reduced at the same time. [Copyright &y& Elsevier]

Two types of cold-air outbreaks over the Yellow and East China Seas are investigated using a regional mesoscale model. Distinct patterns of surface turbulent heat fluxes and precipitation are identified between the two cases. The sea surface heat flux and frictional velocity are strongly influenced by mesoscale differences between high- and low-resolution datasets of sea surface temperature (SST). The influence of the SST difference on atmospheric water is spread to the downstream area of the outbreak with the phase transition of water. The air mass transformation around 800 hPa over the Kuroshio is partly influenced by the upstream SST difference. In particular, the SST difference near the mouth of the Yanzi River strongly modifies the air mass around Taiwan. Thus, in addition to the Kuroshio front, the mesoscale Chinese coastal SST structure is also important in the air mass transformation over the East China Sea. [ABSTRACT FROM AUTHOR]

Abstract: Two cruises were carried out to collect copepod samples from the coastal waters of Northern Taiwan, the Taiwan Strait and the southern East China Sea extending to the Okinawa Trough where the Kuroshio waters intrude. The copepod samples were analyzed for community structure and the dominant copepod species were further analyzed for their trace metal concentration. In total, 106 species of copepods, belonging to 22 families and 43 genera, were recorded. The dominant copepod species were Acartia pacifica, Canthocalanus pauper, Cosmocalanus darwini, Undinula vulgaris, Temora discaudata, Temora turbinata, and Oncaea venusta and exhibited a spatial variation among the study areas. The metal concentration ranges for the analyzed copepods were as follows: Cd, 0.39–142μg/g; Co, 0.03–91.9μg/g; Cr, 2.26–284μg/g; Cu, 3.03–196μg/g; Fe, 19.96–3118μg/g; Mn, 3.98–994μg/g; Ni, 1.69–955μg/g; Pb, 0.04–97.5μg/g; and Zn, 1.52–1140μg/g. The same metal content of copepods showed considerable variation between the intra and inter species. The inter species trace metal content sequence was: O. venusta > A. pacifica > C. darwini > T. turbinata > T. discaudata > C. pauper > U. vulgaris. In addition, the copepod metal quota also exhibited spatial variation: coastal water>the southern East China Sea>the Kuroshio Water. [Copyright &y& Elsevier]

Abstract: The cold-dome off northeastern Taiwan is commonly observed by remote-sensing of Sea Surface Temperature (SST) and in-situ observation. The recent remote-sensing SST and subsurface Argo profiles were analyzed to investigate possible formation mechanisms and dynamics. The observed time series of SST anomaly suggested that the surface cold-dome occurred more frequently in summer, including an unusual contribution due to the cold water residual associated with typhoon events. Subsurface hydrographic features from Argo float data indicated that the near-shore thermocline can be lifted up about 85m by Kuroshio dynamics, and the cold saline deep water (100m deep off northeastern Taiwan) can only result from subsurface Kuroshio. We examined the possible formation mechanisms using a duo-grids North Pacific Ocean model (DUPOM) with a horizontal resolution of 1/8° for the East Asian Seas and 1/4° for the remaining North Pacific. The model reproduced several cold-dome formation events and displayed typical cold-dome features. Further analysis shows that the geostrophic component of Kuroshio transport is the main contributor to the cold-dome formation (57.4% of the total isotherm uplift) and dominates seasonal occurrence of the cold-dome. The contribution resulting from the associated cyclonic eddy is only 3.3% of the total isotherm uplift. Additional sensitivity tests suggested that the remaining contribution (39.6% of the total isotherm uplift) is mainly due to the topographically controlled upwelling in this region. Moreover, the local boundary Ekman transport may enhance the surface appearance of the cold-dome, but plays only a minor role. [Copyright &y& Elsevier]

The seasonal variation in the larval fish community related to the hydrography in the East China Sea (ECS) off northern Taiwan was studied from February to November 2004. Hydrographic conditions in the southern ECS are strongly influenced by the different water masses due to the seasonal monsoon system. A total of 173 taxa of larval fish belonging to 68 families and 105 genera were identified during the study period. The highest abundance of larval fish was recorded in winter, a moderate abundance was seen in late spring and summer, and the lowest abundance in autumn. Significantly higher abundances were usually found in the mixing zone than in ECS and the Kuroshio Current, and the number of species of larval fish was greater during the warm period than during the cold period. The larval fish fauna in the southern ECS is a mixture of endemic and exotic species; the latter come from the coastal waters of mainland China when the northeasterly monsoon prevails, from the South China Sea during the southwesterly monsoon, and from the Kuroshio waters year-round. The succession of water masses induced by the monsoon systems and the high nutrient levels caused by frontal turbulence and topographic upwelling may determine the distributions of larval fish in terms of abundance and composition. [ABSTRACT FROM AUTHOR]

Kobayashi, D. R., Cheng, I-J., Parker, D. M., Polovina, J. J., Kamezaki, N., and Balazs, G. H. 2011. Loggerhead turtle (Caretta caretta) movement off the coast of Taiwan: characterization of a hotspot in the East China Sea and investigation of mesoscale eddies. – ICES Journal of Marine Science, 68: 707–718. Satellite tags were attached to 34 non-reproductive loggerhead turtles (Caretta caretta) caught as bycatch in the Taiwanese coastal poundnet fishery from 2002 to 2008. Transmission durations ranged from 6 to 503 d (median 172 d), with 5860 d tracked in total. Horizontal track data were processed using the Bayesian state-space modelling to extract the most likely daily positions, taking into account ARGOS data quality and other forms of statistical error. A region of high occupancy in the East China Sea, covering 433 549 km2 of coastal and pelagic area next to Taiwan, China, Japan, and South Korea, was characterized from the tracking data. Various attributes of this hotspot are described using satellite tracks and remotely sensed data. The tracks were merged with oceanographic data, emphasizing a new global dataset characterizing mesoscale eddies from satellite altimetry data. A proximity-probability approach coupled with odds ratio testing was used to infer orientation to eddy features. Comparisons against random points, simulated particle tracks, and drifter buoys were used to demonstrate turtle differential responses to eddies inside and outside the hotspot, depending on eddy features (i.e. cyclonic vs. anticyclonic, edges vs. centres). Turtles inside the hotspot utilize fewer strong cyclonic eddy edges than those outside. [ABSTRACT FROM PUBLISHER]

Abstract: Sailfish (Istiophorus platypterus) are of substantial economic importance to Taiwan because of their seasonal abundance (April to October, with a peak from May to July) off the island''s eastern coast. They are harvested by drift gill nets, set nets, harpoons, and as incidental bycatch by inshore longline fisheries. Although the biology of sailfish has been investigated in eastern Taiwan, there is a paucity of data on movement patterns. Pop-up satellite archival tags (PSATs) were used to study the vertical and horizontal movements of three sailfish in 2008. The fish were tagged near the southeastern coast of Taiwan and linear displacements ranged from 1050 to 1400km (~40kmday−1) from deployment to pop-up locations and all movements were confined to the East China Sea. Sailfish spent 88% of their time in the upper uniform mixed layer above 50m, but made more extensive vertical movements during the nighttime ( =60.61m±48.24 SD) than daytime ( =35.21m±35.37 SD). Depths and ambient water temperatures visited ranged from 0 to 214m and 30.0° to 17.8°C, respectively. However in all cases, the depth distribution appeared primarily limited by an 8°C change in water temperature. Diel diving patterns also suggested basking behavior. Sailfish behavior makes them particularly vulnerable to surface fishing gears. [Copyright &y& Elsevier]

The article describes a parasitic species of Acanthobothrium, a hyperapolytic tapeworm, which was collected from the spiral intestine of the Japanese wobbegong, Orectolobus japonicus, in the East China Sea off Magong, Taiwan. Because of the absence of comparative morphological features in the adult worms, the investigation of developed genitalia was found to be extremely difficult. Using light and scanning electron microscopy (SEM), a new species of cestode is identified. Figures showing SEM of the species with enlarged view of each part are presented.

Abstract: Images of 8-day mean chlorophyll-a concentrations of the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard of Aqua Satellite from 2002 to 2007 and of the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) satellite from 1998 to 2007 are used to study the variability of the cross-shelf penetrating fronts (CPFs) in the East China Sea. The analysis suggests that the generation of the CPFs has strong seasonal-to-interannual variations, with more CPFs in summer and winter than in spring and fall. Each CPF lasts for a few days to a month. The majority of the fronts are triangle-shaped with their broad bases nearby the coast and their sharp heads penetrating into the middle shelf. There are over 40 CPFs with penetrating distances exceeding 100km over the East China Sea during the past 10 years of the satellite era, with the maximum ones reaching the Kuroshio at the edge of the continental shelf. Of all the low cloud scenes of the satellite images, more than 25% contain at least one CPF. The high-frequency occurrence of the CPFs suggests that the CPFs play an important role in cross-shelf transport of heat, effluent, and land-derived materials in the East China Sea. The generation of the CPF is found to be influenced by winds and by intrinsic oceanic variability. In particular, the collision of wind-forced coastal jet with the Taiwan Warm Current is suggested as one of the mechanisms that generate the CPFs in the East China Sea. [ABSTRACT FROM AUTHOR]

erosol samples (205) were collected from January 2005 to November 2006 at a coastal site at Keelung City (Taiwan), on the southern East China Sea. The atmospheric concentrations of major ions indicated that the area was dominated by different air masses at different times of the year: continental Asia from January to May and November to December; air masses from Indonesia and surrounding islands (south-eastern region) dominated during early-summer (July 2005 and June 2006), and air masses directly from the adjacent ocean dominated during late-summer (July to August 2006) and early-autumn (September to October 2005). The atmospheric concentrations of water soluble organic nitrogen (WSON) corresponded to the different sources and weather conditions. The results of a factor analysis of combined major ions, water soluble inorganic nitrogen (WSIN) and WSON indicated that a fossil fuel combustion source and biomass burning were the two major controlling factors during the sampling period. We discuss the correlations between WSON, WSIN and major anthropogenic ions in relation to the different formation mechanisms for the various sources. We propose a mechanism whereby biomass burning is the major input of aerosols derived from mainland China. Fossil fuel combustion was found to be important during periods when aerosols were derived from the south-eastern area. Our data indicate that WSON was predominantly associated with aerosols derived from biomass burning when the origin of the air mass was mainland China. [ABSTRACT FROM AUTHOR]

Abstract: X-ray diffraction (XRD) mineralogical and grain-size analyses indicate that inner continental shelf sediments in the East China Sea (ECS) represent a unique mixing of clays derived from the Yangtze River and silts/sands from small western Taiwanese rivers. Taiwanese (e.g., Choshui) clays (<2μm) display no smectite but the best illite crystallinity and are only distributed along southeastern Taiwan Strait. Both Yangtze and Taiwanese river clays are illite-dominated, but the poor illite crystallinity and the presence of smectite and kaolinite indicate that Taiwan Strait clays are mainly Yangtze-dominated. In contrast, medium silts (20–35μm) and very fine sands (63–90μm) in the Taiwan Strait are characterized by low feldspar/quartz, low K-feldspar/plagioclase and high kaolinite/quartz, indicating their provenance from Taiwanese rivers. Taiwanese silts and sands are introduced primarily by the way of typhoon-derived floods and transported northward by the Taiwan Warm Current during summer–fall months. Yangtze clays, in contrast, are widely dispersed southward about 1000km to the western Taiwan Strait, transported by the China Coastal Current during winter–spring months. Since most Taiwan Strait samples were collected in May 2006, clay results in this paper might only represent the winter–spring pattern of the dispersal of Yangtze sediments. [Copyright &y& Elsevier]

Abstract: An analysis of surface current data obtained from 2002 to 2005 using long-range high-frequency radar provides the first evidence for the presence of biweekly (11–14 day) periodic variations of the Kuroshio axis northeast of Taiwan. This analysis clarifies the spatiotemporal characteristics of these variations and reveals that cyclonic/anticyclonic eddies propagating along the shelf slope from the vicinity of the deep channel east of Taiwan induce these variations northeast of Taiwan. The behavior of the cyclonic/anticyclonic eddies on the shelf slope is well explained by 2nd-mode interior shelf waves advected by the Kuroshio''s mean flow. Remote effects from the vicinity of the deep channel east of Taiwan, or from outside the East China Sea, are believed to play an important role in the generation of these biweekly periodic variations of the Kuroshio axis northeast of Taiwan. Moreover, on the shelf slope, these variations cause an onshore current across the shelf slope, suggesting topographically controlled upwelling. Therefore, the biweekly periodic variations of the Kuroshio axis northeast of Taiwan might contribute not only to the onshore transport of Kuroshio surface water but also to transport nutrient-rich Kuroshio subsurface water onto the shelf in the East China Sea. [Copyright &y& Elsevier]

Abstract: We investigated the movement of the Kuroshio axis on the northeast shelf of Taiwan associated with the passage of typhoons, using sea surface current data observed by the ocean radar system on Yonaguni and Ishigaki islands. First, we examined daily Kuroshio axis variation on the northeast shelf of Taiwan during typhoon events. The ocean radar data showed that the Kuroshio axis moved onto the shelf after passages of typhoons. The Kuroshio moved onto the shelf and stayed there after the passage of Typhoon Hai-Tang; while the Kuroshio maintained this pattern, southerly wind blew continuously for 4 days. The mean current speed northeast of Taiwan after the typhoon''s passage increased by 18cms−1. In addition, the sea level difference between two satellite altimetry tracks east of Taiwan increased by 14.4cm. These results suggest that coastal upwelling east of Taiwan caused by the southerly wind generated an east–west sea level difference that, in turn, generated a northward geostrophic current. This current could have enhanced the Kuroshio east of Taiwan, and pushed it onto the shelf. [Copyright &y& Elsevier]

Abstract: Horizontal distribution patterns of jack mackerel Trachurus japonicus larvae were investigated extensively in the East China Sea (ECS) along the shelf-break region between 26° and 30°N during February–March based on fine-scale larval sampling in 2002 and 2003. A total of 2363 T. japonicus ranging from 1.2 to 12.4mm body length (BL) were collected at 310 bongo net sampling stations, of which larvae <10mm BL accounted for 99.1%. In both years, newly hatched larvae (<3mm BL) were concentrated in the shelf-break region mainly in the southern part of ECS between 26° and 27°N in warm water of 21–23°C, suggesting that their primary spawning ground existed in and around this area. With growth, larvae were transported in two different directions, i.e., northward and northeastward, corresponding closely with the direction of the Kuroshio Branch Current north of Taiwan (KBCNT) and the Kuroshio, respectively. Replicate sampling cruises at 2 week intervals were conducted in 2003, and the larval distribution pattern changed significantly between the sampling cruises, suggesting that the transport process fluctuates over relatively short periods in relation to oceanographic processes. The transport speed by the KBCNT was estimated to be 0.13–0.28knots based on the larval distribution, which is one order of magnitude slower than that by the Kuroshio (1.5–3knots). Habitat temperature gradually declined with growth in both the Kuroshio and KBCNT, but in the KBCNT it was 1–2°C lower than in the Kuroshio. Our results suggest that the two different larval transport processes lead to a significant difference in the transport route, habitat conditions (such as temperature and food), and site where young fish recruit to the demersal habitat, which will result in different survival and recruitment processes. [Copyright &y& Elsevier]

The East China Sea is one of the last unexplored high-potential resource areas located near large markets. But the development of oil and gas in much of the area has been prevented for decades by conflicting claims to boundaries and islets in the area by China, Taiwan, and Japan. Competition between China and Japan for gas resources in the East China Sea is intensifying and hampering improved relations. However, conflict is not inevitable. A compromise--joint development--is motivated by the realization that a positive China-Japan relationship is simply too important to be destroyed by these disputes. Although both agree in principle on joint development, the two sides have different interpretations of what joint development means or implies, and what area should be jointly developed. The article spells out three basic agreements in principle that are necessary before details of any solution can be negotiated. The alternative to a solution is continued mutual suspicion, unstable relations, unmanaged and undeveloped resources, and an increasing frequency and intensity of incidents, fueling nationalist sentiments and resultant political conflict. [ABSTRACT FROM AUTHOR]

The distributions of dissolved iron (DFe) and organic iron-binding ligands (L Fe) in the Kuroshio Current and its neighboring waters were elucidated from four cross-sectional surveys from the eastern coast of Taiwan to Sagami Bay. The Kuroshio surface water was characterized by a high salinity, low concentration of DFe, high concentration of L Fe , and low fluorescence of humic-like substances, in comparison to the neighboring waters. The neighboring waters of the Kuroshio can be categorized into two types: the East China Sea water and coastal water. The East China Sea water was found near the Okinawa Trough, and characterized by a steep vertical gradient of DFe concentration, almost as low as that in the Kuroshio within the surface mixed layer, but reached ~0.5 nM below the mixed layer. Coastal water was observed on the southern coast of Japan, and its DFe concentration was high throughout the upper 200 m. The concentration of L Fe in the Kuroshio water was significantly higher at 10-m depth than in the deeper layers. This suggests that humic-like substances, which are a major component of L Fe in estuarine and deep waters, play a relatively minor role in the Kuroshio surface waters. Mixing with coastal waters can increase the concentration of bioavailable inorganic ferric ions in the Kuroshio surface water in two ways, by increasing the DFe concentration and decreasing the L Fe concentration. • Mixing with coastal waters increases dissolved iron in the Kuroshio surface water. • Mixing with coastal waters decreases iron-binding ligands in the Kuroshio. • Humic-like substances are minor in iron complexation in the Kuroshio surface water. [ABSTRACT FROM AUTHOR]

• The interaction of Kuroshio and Taiwan Strait Current have been extensively studied. • Taiwan Warm Current has inshore and offshore branches over the East China Sea shelf. • Coastally trapped waves greatly regulate the Yellow Sea Warm Current. In recent years, advances have been made toward understanding the oceanic circulation dynamics in the Taiwan and Tsushima straits, as well as over the central shelf of East China Sea (ECS) and southern Yellow Sea. ECS shelf circulation between the 50 m and 100 m isobaths is attributed to the confluences of the northeastward Taiwan Strait Current (TSC) and Kuroshio intrusion over the shelf to the northeast of Taiwan. Although the relative importance and interaction of these two currents have not been well documented, the driving mechanisms underlying the northeastward TSC have been extensively studied in recent decades. The first set of long-term (2009–2011) observations showed that a stronger/weaker TSC (~2.37 Sv/~0.64 Sv) appears in summer/winter. However, the dynamics underlying the northeastward TSC against the northeasterly winds in winter are still debatable. The destination of the ECS shelf current in the formation of the Tsushima Warm Current is better understood. The volume transport of this current is ~2.67 Sv. The northeastward-flowing Taiwan Warm Current has two branches over the 50 m and 100 m isobaths. The northwestward Yellow Sea Warm Current (YSWC) characterizes the shelf circulations in the Yellow Sea Trough in winter, and the propagation of coastally trapped waves greatly regulates the flow pattern of the YSWC. The Yellow Sea Cold Water Mass alters the shelf circulations in the southern Yellow Sea in summer. [ABSTRACT FROM AUTHOR]

210Po and 210Pb are well-known tracer pairs for some biomass and chemical processes in the marine system. In this study, 210Po and 210Pb were analyzed in surface seawater collected from the East China Sea (ECS), in atmospheric deposition, and in riverine input water collected along the ECS coast. The atmospheric fallouts of 210Po and 210Pb were higher in the dry season, due to the arrival of storm dust from the northwestern region of China. In the riverine input water, the particulate 210Po and 210Pb dominated (corresponding to 33–94% and 50–92% of the total, respectively), especially during the flood season. In the surface seawaters, the percentage of particulate 210Po (17–85%) was generally greater than that of 210Pb (10–76%). Additionally, in the Changjiang Estuary, log K d (Po) and log K d (Pb) were negatively correlated with log suspended particulate matter (SPM) (R = 0.71, P = 0.013 for Po, R = 0.67, P = 0.019 for Pb). 210Pb showed a stronger "particle effect" than 210Po when SPM <1.00 mg L−1, and vice versa when SPM >1.00 mg L−1. The deficit of 210Po relative to 210Pb gradually decreased from the Changjiang Diluted Water, to the Shelf Merged Water and the Taiwan Warm Current Water. The mass balance of 210Po and 210Pb in the water column of the estuary indicated that the Changjiang River was the dominating input source (providing 91% and 88% of the 210Po and 210Pb, respectively); meanwhile, the shelf export was the dominating output source (accounting for 68% and 78% of the 210Po and 210Pb, respectively). • Particulate 210Po and 210Pb were dominant in the high-turbidity surface water of ECS. • The deficiency of 210Po relative to 210Pb decreased with offshore water masses. • 210Pb showed a stronger "particle effect" than 210Po when SPM < 1.00 mg L−1, and vice versa when SPM > 1.00 mg L−1. • The predominant source and sink of 210Po and 210Pb in the estuary are the river input and shelf report. [ABSTRACT FROM AUTHOR]