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Samples of the holothurian Eupentacta fraudatrix (Djakonov & Baranova in Djakonov, Baranova & Saveljeva, 1958) from the Sea of Japan were studied and the relationships of the genera Eupentacta and Sclerodactyla, as well as related taxa, were evaluated on the basis of phylogenetic analysis of the mitochondrial DNA COI and 16S rRNA genes. Using three methods, phylogenetic trees were constructed, and the degree of reliability of topological reconstructions was estimated by means of a nonparametric bootstrap test for the neighbor joining (NJ) and maximum likelihood (ML) techniques, as well as by a posteriori probability for Bayesian inference (BI) analysis. Genetic data confirm the validity of the assignment of Cucumaria fraudatrix to the genus Eupentacta Deichmann, 1938. The study of sequences obtained from the holothurian specimens collected in Russian waters, near the city of Vladivostok, and determined by morphological characters clearly indicate that these specimens belong to the genus Eupentacta and are assigned as E. fraudatrix. The specimens from China in GenBank named as Sclerodactyla multipes and used in the present study, were likely misidentified, and after re-examination they may be assigned to the genus Eupentacta, either as E. fraudatrix or another taxon. Analyses of morphological characters of S. multipes unequivocally affirm that this species must be excluded from Sclerodactyla Ayres, 1851 and is provisionally assigned to the genus Sclerothyone Thandar, 1989 based on the external morphological characters and the body wall ossicles. [ABSTRACT FROM AUTHOR]

The velocity sections and acoustic parameters of the sedimentary cover in the Central (Japan), Yamato (Honshu), and Tsushima basins, and the Kita–Yamato Trough of the Sea of Japan, as well as the rocks of the basement and the Cenozoic cover of the submarine Yamato Rise were studied. A comparative analysis of similar parameters of the Cenozoic basins in the South China and East China marginal seas was performed. The relationship between the acoustic properties (P-wave velocity, Vp) of the basal horizons and the age of the Cenozoic cover in the above basins was analyzed. The values of Vp = 3.0–3.6 km/s have been validated as the acoustic parameter of Paleocene–Eocene sedimentary strata. According to the studies we performed, the basal layers in the supposed depocenters of the Japan basins (Central, Yamato, and Tsushima) have Vp = 3.0–3.3 km/s, which indicates the Paleocene–Eocene age of the onset of their formation. [ABSTRACT FROM AUTHOR]

The history of coastal catastrophic floods was reconstructed for the first time using the geochemical proxy in shelf sediments. The reconstruction is based on the identification of sediment layers accumulated on the shelf during the intensive discharge of the river runoff suspended matter from the land which does not contain bromine. The set of isotopic (AMS 14C, 210Pb, 137Cs), tephrastratigraphic, and paleomagnetic methods was used for the detailed chronology of sediments. The scanning of chemical composition of sediments with the step of 0.5–0.8 mm is performed using the synchrotron radiation X-ray fluorescence in the VEPP-3 storage of the Institute of Nuclear Physics of Siberian Branch of Russian Academy of Sciences. The history of catastrophic floods for the past 1800 years is reconstructed based on the typical variations in bromine concentration in one of the cores from the Amur Bay (the Sea of Japan). New methodological approaches to the flood signal extraction are proposed. The revealed inverse correlation between the frequency of floods caused by typhoons over the coast of the Sea of Japan and southern China agrees with the existing assumption on the change in their trajectories in different periods of global climate change. [ABSTRACT FROM AUTHOR]

Concentrations of 13 phase-partitioned polycyclic aromatic hydrocarbons (PAHs) in seawater were monitored monthly off Oki Island, Japan, during 2015-2019 to elucidate seasonal variations, main source, and transport pathways of PAHs in the southwestern Sea of Japan. Total PAH (dissolved plus particulate) concentrations in surface seawater at 36°09.0'N, 133°17.3'E (site OK) were in the range 0.49-9.36 ng L -1 (mean 2.77, SD 2.05 ng L -1 ) with higher levels in summer-autumn, an order of magnitude lower than those in the East China Sea during 2005 and 2009-2011 and about one-third of those recorded in the Sea of Japan in 2008 and 2010. The main sources of dissolved and particulate PAHs were combustion products. Increasing dissolved PAH levels during July-October indicate that the area around southern Oki Island is impacted by PAH-rich summer continental-shelf water transported by the Tsushima Warm Current flowing from the East China Sea., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Abstract: The contribution of physical processes in the distribution of the giant jellyfish Nemopilema nomurai in the northern East China (ECS) Yellow (YS) and East/Japan (EJS) seas in summer 2005 was simulated by a Lagrangian particle-tracking experiment based on ROMS (Regional Ocean Modeling System). The particles representing jellyfish were released in the western YS between the Shandong Peninsula and the Changjiang River mouth from May to July 2005, and then tracked. Particles released in May–June in the Changjiang mouth moved mostly east-northeastward to the Korea/Tsushima Strait, and thereafter they moved to the Tsugaru Strait along the west coast of Japan from summer to fall. About 80% of the particles entered the EJS in this period. However, most of the particles from the northern Changjiang distributed in the YS, drifting anticlockwise, and thus only about 13% of the total particles entered the EJS area. The particle-tracking analysis shows that the observed distributions of the giant jellyfish in the northern ECS and EJS are quite similar to those of particles driven by wind forcing and ambient along-shelf currents in this area. The results with and without wind conditions differ fundamentally. With wind forcing, the eastward summer movement of the particles was enhanced; this determined the spatial distribution pattern of the particles and jellyfish in the waters around the Korean Peninsula. Moreover the particle distribution over time strongly suggests the Changjiang mouth as one of the jellyfish seeding places. The results show that a particle-tracking experiment can be used to determine jellyfish drift and that wind forcing and along-shelf currents are the factors determining the distribution. [Copyright &y& Elsevier]

The phylogenetic relationships within the genus Takifugu Abe, 1949 (Tetraodontiformes, Tetraodontidae) remain unresolved. Because of the use of Takifugu as model organisms, the resolution of these relationships is crucial for the interpretation of evolutionary trends in biology. Pufterfishes of this genus are comprised of a comparatively small number of species and are mainly distributed along the coastal region of the western part of the Sea of Japan and the coastline of China. Mitochondrial gene sequences were employed to test the phylogenetic hypotheses within the genus. Seventeen species of the genus were examined. Molecular phylogenetic trees were constructed using the maximum parsimony, neighbor-joining, maximum likelihood and Bayesian methods. Our hypothesis of internal relationships within the genus differs from previous hypotheses. Our results indicate that (1) the genus Takifugu is a monophyletic assemblage; (2) the genus is divided into 6 subgroups based on the molecular data; and (3) there is low genetic diversity among the species within this genus. In addition, speciation within Takifugu appears to be driven by hybridization and isolation by distribution. Our results also suggested that the taxonomy in the genus should be clarified based on both molecular and morphological data. [ABSTRACT FROM AUTHOR]

Discusses the possibility of the renewal of Bottom Water formation in the Japan/East Sea (JES) due to the diversion of rivers, such as the Yellow or the Yangtze, for agricultural use by China. Effect of the increase of salinity on Bottom Water formation even at present-day cooling rates; Comparison of the convection in the Mediterranean Sea to that in the JES; Final equilibrium state.

The article offers information on the delimination of the continental shelf and two hundred-mile zones in the East China Sea and the Sea of Japan. The Third Law of the Sea Conference Conference became the basis of two hundred-mile fishery zones or economic zones of coastal states. To avoid territorial conflicts between South Korea and China, Japan did not set the two hundred miles fishing zone in the Sea of Japan. The three countries maintain stable fisheries relationship, but territorial disputes remains a major concern between the three countries. The delimination of two hundred-mile zone did not prevent the risk of possible armed conflict the Sea of Japan.