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Based on the results from the previous research on Mesozoic igneous rocks, as well as tectonic environments in the northern South China Sea and southern East China Sea (NSCS-SECS), geophysical parameters, strata, and characteristics of seismic facies in NSCS-SECS were investigated. These findings were combined with results from the analysis of the balanced profile evolution to re-evaluate the tectonic evolution of SECS since the Jurassic. Furthermore, burial history and simulation of wells in the SECS were analyzed using well, seismic and source rock data. Furthermore, favorable models of oil–gas accumulation in the Lower–Middle Jurassic were proposed in combination with studies on elements and conditions of the petroleum system. The results demonstrated that the NSCS-SECS had consistent tectonic settings and comparable strata from the Jurassic to the Cretaceous time. There was a large unified basin in this period. The basin experienced two evolutionary stages, respectively, the fore-arc depression basin in the Early–Middle Jurassic (J1-2) and the back-arc faulted basin in the Late Jurassic–Cretaceous (J3-K). There was considerable deposition of dark mudstones in the SECS during the Lower–Middle Jurassic. The Keelung Sag was the depositional center accumulating the thickest section of the Lower–Middle Jurassic source rocks which entered a high-maturity stage. Hence, it was the hydrocarbon generation center in the SECS. The process of generating hydrocarbons from Lower–Middle Jurassic source rocks was of high complexity from northwest to southeast. The Lower–Middle Jurassic source rock at the northwest edges of the basin experienced two hydrocarbon generation stages, while the Keelung Sag toward the southeast experienced three hydrocarbon generation stages. The models and types of oil–gas accumulation in various evolutionary phases were different due to the control by tectonic evolution. Oil and gas that were generated by Lower–Middle Jurassic source rocks in the Keelung Sag migrated and accumulated in the western high-tectonic units. Research findings provide insights into Mesozoic oil and gas exploration in the NSCS-SECS.

Clarifying eukaryotic microbial spatial distribution patterns and their determinants is an important idea in ecological research. However, information on the distribution patterns of eukaryotic microbial community structures (EMCSs) within oceans remains unclear. In this study, surface water samples from the southern East China Sea (SECS) were collected to investigate the spatiotemporal variation in EMCSs by using 18S rRNA high-throughput sequencing technology and the impact of this variation on Pseudosciaena crocea during the breeding season. The results indicated that the distribution patterns of the eukaryotic microbial community structure were different among the Sansha Bay, Mindong and Wentai reserves and the offshore East China Sea. In addition, there were notable potential effects of EMCSs on fishery activities. The variation partitioning analysis showed the environmental and spatial factors caused 53.4% of the variation in the EMCSs, indicating that spatially structured environmental factors were the key determinants of the EMCSs spatial heterogeneity in the SECS and may have contributed to the general distribution of P. crocea. In addition, all the environmental factors were the main factors driving the distribution of eukaryotic microbes except for total phosphorus. Furthermore, it was noted some phytoplankton such as Poterioochromonas and Rhizophydium of fungi in Sansha Bay can effectively prevent Cyanobacteria blooms. Chrysophyceae are natural high-quality baits for juvenile fish distributed in Sansha Bay, Mindong and Wentai reserves. This study provides a part of the insight into potential eukaryotic community distributions in large water bodies and how they are affected by environmental factors. [ABSTRACT FROM AUTHOR]

The shallow hydrothermal vents (HVs) of Kueishan Island are considered as a template for studying the extremes of sulfide-polluted and acidified water. The present study examined the biological and spatiotemporal aspects of mesozooplankton mortality in waters around this extreme HV environment. Zooplankton sample collection was carried out in three monsoonal periods and the results revealed that there was a significant decrease in the mortality of total mesozooplankton with increasing distance from the HVs. The overall mortality of mesozooplankton showed a significant negative correlation with sea surface temperature and pH. Particularly, mortality of copepods showed a significant negative correlation with pH, whereas it was significantly positive correlated with sea surface temperature in the southwest monsoon prevailing period. Overall, the results may imply a situation that zooplankton will encounter in the more acidified environment of a future ocean. • Hydrothermal vents exert different mortalities on different mesozooplankton taxa. • Low pH significantly increases mesozooplankton mortality. • Lethal mesozooplankton effects decrease with increasing distance from hydrothermal vents. • Mesozooplankton mortalities differ with monsoonal periods. [ABSTRACT FROM AUTHOR]

This study aims to investigate the impact of submesoscale vertical advection (SVA) on the primary productivity in the southern East China Sea. The analysis is based on a comparison between two numerical simulations by using a three‐dimensional coupled physical‐biogeochemical model. One simulation directly resolves SVA on a high‐resolution mesh, and the other leaves SVA unresolved on a low‐resolution mesh. The high‐resolution simulation outperforms the low‐resolution simulation in reproducing the observed chlorophyll distribution, particularly in summer. Resolving SVA results in an approximately 40% increase in primary productivity during the summer, though SVA activity is relatively weak in this season than in other seasons. Among multiscale physical processes, SVA, rather than mixing, is found to be the most important vertical nutrient supply pathway from the nutrient‐rich bottom water to the nutrient‐depleted surface water in summer, particularly on the middle and outer shelves. The impact of SVA on the shelf is unique compared to the open ocean in that it efficiently enhances vertical supply of nutrient‐rich subsurface waters to the nutrient‐depleted surface layer. This study highlights the importance of SVA in promoting primary productivity in stratified shelf seas. Plain Language Summary: The southern East China Sea, located on a wide shelf, holds several world‐famous fishing grounds. Algal growth plays a fundamental role in the marine food web. Nutrient elements such as nitrogen and phosphorus are crucial for algal growth. In summer, the stable water column obstructs nutrient‐rich deep water from mixing with the nutrient‐poor surface water. However, scientists found that algal growth in summer remains high. A question arises: How are nutrients supplied to the surface water? This study focuses on how small‐scale (1–10 km) and fast‐changing (days to weeks) ocean currents affect algal growth. Computer‐based models can simulate the interaction between multiple‐scale ocean currents and nutrients, algae, and small animals. In our model, the small‐scale vertical transport forms a significant vertical nutrient supply pathway in the southern East China Sea, particularly in summer. Therefore, in layered shelf seas, the small‐scale vertical transport may become the predominant vertical nutrient transport pathway, thus supporting strong algal growth. This finding contributes to better understanding the impact small‐scale physical processes have on the marine ecosystem. Key Points: Accuracy in modeling chlorophyll is improved by resolving submesoscale vertical advection (SVA)Relatively weak SVA in summer exerts a remarkably positive impact on primary productivityTransport of nutrients to the euphotic layer by SVA is crucial for high primary productivity in a stratified shelf sea [ABSTRACT FROM AUTHOR]

In September and October of 2011, a marine magnetic survey was conducted in the southern East China Sea between 120° and 126°E, 26° and 28°N with the research vessel Kexue-3. New magnetic maps with 5 × 5 km grid spacing were generated after meticulous data processing. Based on an analysis of magnetic anomaly features and further calculation results, including the total horizontal derivatives (THD), second order vertical derivatives (SVD) and analytic signal amplitude (ASA), several new tectonic insights on magnetic sources, basement structures and fault properties were obtained. The NE-SW or NNE-SSW oriented magnetic anomaly highs have different sources: (1) The high amplitude, short wavelength magnetic anomalies of the Zhemin Uplift are caused by shallow buried igneous rocks intruded along NE-NEE oriented faults. (2) The high amplitude, moderate wavelength magnetic anomalies of the Diaoyudao Uplift are caused by the metamorphic basement intruded by magmatic rocks. (3) The magnetic sources of the Yandang Uplift and Taibei Uplift in the shelf basin are shallow buried metamorphic basements and deep buried volcanic bodies, respectively. Several NW-SE or NWW-SEE oriented dextral strike-slip fault belts were identified as important tectonic boundaries. Each is composed of several en echelon and partly overlapping secondary faults. Initially formed in the Cretaceous, these fault belts have evolved through multiple periods, propagated seaward with the migration of the basement rifting and accommodated local stress fields in the Cenozoic. [ABSTRACT FROM AUTHOR]

We examined the interannual variations in distribution and abundance of Japanese jack mackerel Trachurus japonicus larvae <5 mm standard length (SL), based on sampling surveys over a broad area of the shelf break region of the East China Sea (ECS) during late winter and spring for 12 years from 2001 to 2012. Larval abundances in late winter were higher than those in spring. In late winter, ratios (expressed as %) of larval abundance in the southern ECS south of 28 °N to the whole study area were highest during the study period, with values ranging from 80.0 to 95.8%. In spring, the ratios in the southern ECS were still high (34.3 - 88.8%), although the values increased slightly in the northern and central ECS. There was no significant interannual variation in the centre of distribution of the larvae, suggesting that the formation of spawning grounds would be related to topographic rather than hydrographic conditions. Habitat temperature of larvae in the central and southern ECS was ~ 3 - 5 °C higher than that in the northern ECS throughout the study period, indicating that larval growth and survival processes may differ between the two areas. In the southern ECS, larval abundances fluctuated largely from year-to-year, and the interannual variations were closely correlated with water temperature and chlorophyll a concentration. However, larval abundance did not correlate with an index of recruited juveniles (~50-75 mm SL) in the ECS, suggesting that mortality during the late larval and early juvenile stages is responsible for recruitment success or failure. [ABSTRACT FROM AUTHOR]

In this paper, two sets of gravity and magnetic data were used to study the tectonics of the southern East China Sea and Ryukyu trench-arc system: one data set was from the 'Geological-geophysical map series of China Seas and adjacent areas' database and the other was newly collected by R/V Kexue III in 2011. Magnetic and gravity data were reorganized and processed using the software MMDP, MGDP and RGIS. In addition to the description of the anomaly patterns in different areas, deep and shallow structure studies were performed by using several kinds of calculation, including a spectrum analysis, upward-continuation of the Bouguer anomaly and horizontal derivatives of the total-field magnetic anomaly. The depth of the Moho and magnetic basement were calculated. Based on the above work, several controversial tectonic problems were discussed. Compared to the shelf area and Ryukyu Arc, the Okinawa Trough has an obviously thinned crust, with the thinnest area having thickness less than 14 km in the southern part. The Taiwan-Sinzi belt, which terminates to the south by the NW-SE trending Miyako fault belt, contains the relic volcanic arc formed by the splitting of the paleo Ryukyu volcanic arc as a result of the opening of the Okinawa Trough. As an important tectonic boundary, the strike-slip type Miyako fault belt extends northwestward into the shelf area and consists of several discontinuous segments. A forearc terrace composed of an exotic terrane collided with the Ryukyu Arc following the subduction of the Philippine Sea Plate. Mesozoic strata of varying thicknesses exist beneath the Cenozoic strata in the shelf basin and significantly influence the magnetic pattern of this area. The gravity and magnetic data support the existence of a Great East China Sea, which suggests that the entire southern East China Sea shelf area was a basin in the Mesozoic without alternatively arranged uplifts and depressions, and might have extended southwestward and connected with the northern South China Sea shelf basin. [ABSTRACT FROM AUTHOR]

We examined larval fish assemblages in the southern East China Sea during late winter where large spawning grounds of several commercial pelagic fishes are formed. Our samples include a total of 187 species or taxa of larval fish belonging to 118 genera, 96 families, and 18 orders. Mesopelagic fish larvae, mainly Stomiiformes, Aulopiformes, and Myctophiformes, accounted for 66.5% of the total catch, while commercial species such as Trachurus japonicus , Scomber spp., and Trichiurus japonicus for 16.6%. Based on the species composition, three assemblages were recognized: Kuroshio (KUR), Shelf-Break (BRE), and Shelf (SHE) assemblages. KUR assemblage was mainly characterized by various mesopelagic fishes such as Sigmops gracilis , Diaphus spp., and Myctophum asperum , BRE assemblage by both commercial pelagic and mesopelagic species, SHE assemblage by demersal species such as Lepidotrigla spp. and Gobiidae spp. Both abundance and diversity were highest in KUR assemblage, although food availability for the larvae would be poorest. The combination of variables of sea surface temperature-chlorophyll a concentrations best explained the larval distribution. Except for Benthosema pterotum , the center of distribution of mesopelagic fish larvae was clearly separated from that of the commercial species by the Kuroshio front. However, a northward intrusion of the Kuroshio transported mesopelagic fish larvae onto the shelf, forming the BRE assemblage. Competition for prey between mesopelagic and commercial pelagic fish larvae would potentially occur if the intrusion is strong. [ABSTRACT FROM AUTHOR]

Fish biomass is a critical component of fishery stock assessment and management and it is often estimated from ocean primary production (OPP). However, the relationship between the biomass of a fish stock and OPP is always complicated due to a variety of trophic controls in the ecosystem. In this paper, we examine the quantitative relationship between the biomass of chub mackerel ( Scomber japonicus) and net primary production (NPP) in the southern East China Sea (SECS), using catch and effort data from the Chinese mainland large light-purse seine fishery logbook and NPP derived from remote sensing. We further discuss the mechanisms of trophic control in regulating this relationship. The results show a significant non-linear relationship exists between standardized CPUE (Catch-Per-Unit-Effort) and NPP ( P<0.05). This relationship can be described by a convex parabolic curve, where the biomass of chub mackerel increases with NPP to a maximum and then decreases when the NPP exceeds this point. The results imply that the ecosystem in the SECS is subject to complex trophic controls. We speculate that the change in abundance of key species at intermediate trophic levels and/or interspecific competition might contribute to this complex relationship. [ABSTRACT FROM AUTHOR]

We report a high-spatial-resolution study on the distributions, characteristics, and environmental risks of microplastics in surface sediments of the southern East China Sea. Microplastics were omnipresent in the sediments (concentration range: 53.3–246.7; mean: 138.4 particles/kg dry-weight sediment) and enriched in nearshore areas close to urban centers relative to lower offshore concentrations. The microplastics identified were dominated by polyethylene (41.2%) and polyethylene terephthalate (19.9%) in polymer type, fibers (45.8%) and fragments (40.3%) in shape, 0.1–0.5 mm (61.0%) in size, and black (52.0%) in color. The benthic environment experienced low to moderate microplastic pollution, with polyvinylchloride exhibiting the highest ecological risk index. The high-resolution sampling revealed highly diverse polymer types and strongly patchy distributions of microplastic abundance and pollution indices in sediments. Results from this study imply that complex physical, biological, and topographic interactions control the distribution of microplastics and the associated environmental risks in coastal sediments. • Highest spatial-resolution study of sedimentary microplastics in China's coastal seas • Microplastics are ubiquitous in sediments of the southern East China Sea. • Fibrous and fragment, polyethylene and polyethylene terephthalate are dominant. • Pollution load index indicates mild microplastic contamination. • Polyvinyl chloride poses the highest ecological risk. [ABSTRACT FROM AUTHOR]

Sediment traps were deployed on the southern East China Sea (ECS) continental slope to measure particle and biogenic fluxes for deriving particulate carbon exports from the ECS continental shelf through the Mien-Hua Canyon (MHC). Particle fluxes are much higher in the MHC than in other non-canyon slopes, ranging from 4.98 g m−2 d−1 on the lower slope to 71.5 g m−2 d−1 in the MHC, indicating that the MHC is a major conduit of particle transport. More than 80% of collected particles are lithogenic, regardless of trap sites. Biogenic contents are diluted by lithogenic materials and therefore decrease with the increase in mass fluxes. However, biogenic fluxes remain significant as they are proportional to mass fluxes, ranging from 21 to 368 mg C m−2 d−1 for particulate organic carbon (POC), 12–750 mg C m−2 d−1 for particulate inorganic carbon (PIC), and 21–755 mg m−2 d−1 for opal. Although particle and biogenic fluxes decrease with distance away from the shelf break, these fluxes increase significantly with water depth, indicating the important contribution of lateral transport to measured fluxes. Most POC collected from the slope is likely derived either from the shelf or from the upper-middle slope. Short-term variabilities of collected biogenic fluxes are likely linked to episodic resuspension and lateral movement from the shelf to the slope. Such cross-shelf and off-slope-directed transport of biogenic particles appears to function via the bottom and intermediate nepheloid layers over the shelf and slope. Total shelf fluxes through the MHC are estimated to be 2.43×1011 g C yr−1 for POC and 4.20×1011 g C yr−1 for PIC; the POC flux accounts for 0.17% of total primary production on the shelf. If these exports are extrapolated to calculate the amount of POC and PIC export through the whole ECS slope, the exported POC and PIC may be estimated to be less than 9.35×1012 and 16.2×1012 g C yr−1, respectively. The shelf export of POC is equivalent to <6.4% of carbon fixed biologically on the shelf. The export of particulate nitrogen is estimated to be less than 1.18×1012 g N yr−1, that is equivalent to <4.6% of total nitrogen required to sustain primary production on the ECS shelf. More than 70% of the nitrogen used for new production (4.11×1012 g N yr−1) may be buried in shelf sediments. [Copyright &y& Elsevier]

Benthosema pterotum is one of the most abundant myctophids and an important species link in the food web between producers and consumers in the continental shelf of the southern East China Sea (ECS). This study used R/V Ocean Researcher 1 and 5 to investigate the spatial distribution of B. pterotum larvae and the associated environmental factors affecting the continental shelf of the southern ECS between 2006 and 2017. A generalized additive model (GAM) was used to evaluate potential habitats of B. pterotum. In total, 6690 B. pterotum larvae were collected during nine cruises. The density varied from 0.88 to 2488.19 individuals per 1000 m3 (ind. 1000 m−3) during the study period. The median density was highest in June 2009 (65.68 ind. 1000 m−3) and lowest in July 2010 (5.78 ind. 1000 m−3); it was highest at 18.42 ind. 1000 m−3 in flexion larvae but lowest at 7.01 ind. 1000 m−3 juveniles. The density of B. pterotum in juveniles did not significantly differ according to different sampling depths and between daytime and nighttime. These results suggest that diel vertical migration commences in the juvenile stage. The GAM results indicated that influential variables, namely salinity, temperature, zooplankton biomass, and chlorophyll a concentration affected B. pterotum larval distribution on the continental shelf of the southern ECS. Benthosema pterotum in the preflexion and flexion stages inhabit optimum temperatures ranging from 28.2 to 28.8 °C and salinity value ranges of 32–33.6 in the waters of the south and central shelf region of the southern ECS (25–29° N, 121–125° E). They then moved to relatively low temperature and low salinity areas in the waters of the north and peripheral shelf region. In addition, some juveniles moved to the south of the Changjiang River estuary, which has high primary productivity. In short, B. pterotum larvae's patterns of growth and habitat distribution might relate to a survival strategy that seeks to optimize environmental factors and food availability during summer. [ABSTRACT FROM AUTHOR]

Parinya Limviriyakul, Li-Chun Tseng, Jiang-Shiou Hwang, and Tung-Wei Shih (2016) Symbiotic anomuran and brachyuran crabs were identified after extensive surveys of reef zones, especially from sponges, scleractinian corals, crinoids, and sea urchins, in the coastal areas of the southern East China Sea. Twenty-nine species belonging to 17 genera, 9 families, and 2 infraorders were identified (3 were identified to the generic level). More crabs belonged to the infraorder Brachyura (82.8%) than to Anomura (17.2%). Two anomuran symbionts ( Allogalathea elegans and Petrolisthes virgatus ) and 5 brachyuran symbionts ( Tetralia glaberrima , Tetralia rubridactyla , Trapezia cymodoce , Trapezia septata , and Cymo melanodactylus ) are common in this area. Two species of Anomura ( Lauriea simulata , Petrolisthes virgatus ) and 3 of Brachyura ( Gonatonotus nasutus , Tetralia aurantistellata and Tetralia nigrolineata ) were identified for the first time from waters adjacent to Taiwan. These records represent the northernmost recorded of L. simulata and T. aurantistellata . The occurrence of P. virgatus is the second in the western Pacific Ocean. This study revealed the geospatial distribution of symbiotic crabs, which connects the region from the southern Ryukyu arc to the Coral Triangle, and provides the supporting taxonomic account of symbiotic anomuran and brachyuran crab fauna inhabiting the reef zone in northern Taiwan.