Predicting Future Shifts in the Distribution of Tropicalization Indicator Fish that Affect Coastal Ecosystem Services of Japan

Tropicalization characterized by an increase in marine species originating from the tropical waters affects human society in various ways. An increase in toxic harmful species negatively affects fisheries and leisure use, and an increase in herbivorous fish affects fisheries and carbon sink capacity by decreasing seagrass/seaweed beds. On the other hand, an increase in tropical reef fish attracts more tourism. This study aimed to predict future shifts in the distribution of functional groups of tropicalization indicator fish that can affect marine ecosystem services in temperate coastal waters of Japan. We estimated the distribution of harmful fish Aluterus scriptus and Scarus ovifrons, herbivorous fish Kyphosus bigibbus and Siganus fuscescens, and tropical reef fish Amphiprion frenatus and Chaetodon auriga by collecting their distribution data from open databases. Distributions in 2000–2018 and the future (2046–2055 and 2091–2100) under different climate change scenarios (the representative concentration pathways; RCPs) were estimated using a species distribution model. We used environmental variables such as minimum sea surface temperature (SST), depth, slope, coral reef area, and seagrass/seaweed bed area as predictors and carried out future predictions using the future ocean regional projection (FORP) dataset. The minimum SST was the factor most responsible for the estimated distribution patterns for all species. The depth, slope, and seagrass/seaweed bed were also important for some species. The estimated probability of occurrence was high along the Pacific coast, which was affected by the warm Kuroshio Current and Tsushima Current along the coast of the Sea of Japan. Projected shifts in distributions based on different RCP scenarios showed that these indicator species would significantly increase their distribution in the middle to northern parts of Japan (32–37°N). By the 2090s, their habitat range was estimated to increase to 1.2–1.9 times that of 2000-2018 with severe warming (RCP8.5). However, the target species habitat range would not change significantly with stringent mitigation (RCP2.6). Our results suggest that ambitious commitment to reducing CO2 and other greenhouse gas emissions, such as following the Paris Agreement, will alleviate future tropicalization. Moreover, the fine resolution results can also be directly used for planning climate adaptation programs for local decision makers.

The economic situation of the Arctic in the Chinese energy market

Over the past decade, the Chinese economy has grown at a faster pace (up to 8 % per year), which is a consequence of the unprecedented expansion of China in world markets. Such a competitive position presupposes the same significant (up to 15 %) growth in energy consumption, which is ensured by both an increase in domestic production (to a lesser extent) and imports of energy resources — oil, pipeline and liquefied natural gas and coal. In the context of aggravated competition between the leading economies of the world (China and the United States), the security of transporting energy resources from the Persian Gulf and other regions through the narrows of the Strait of Hormuz and Malacca, as well as through the regions of the South China Sea and the Taiwan Strait controlled by the United States, acquires a new sound for China. To solve this problem, China is building up its naval presence in the direction of the Southern Silk Road, but mainly in the waters of the Pacific Ocean seas — the Yellow, East China and South China, that is, in the operational zones of the three fleets of the Chinese Navy — the North, East and South, from the exits to the operational zone of the Russian Pacific Fleet in the waters of the Sea of Japan and the Sea of Okhotsk. Demonstration of strength and flag during joint sailing of the two fleets is carried out within the framework of the exercises of the “Maritime Interaction” format from 2012 to 2021 inclusive, except for 2020 due to the aggravation of the epidemiological situation in connection with COVID-19. The latent goal of these exercises is to practice coastal defense missions in the zone where China's strategic oil reserve is located.

Knowledge on the Biological and Fisheries Aspects of the Japanese Sardine, Sardinops melanostictus (Schlegel, 1846)

Japanese sardine (Sardinops melanostictus) is a significant small pelagic fish and a valuable resource that plays an essential ecological role in the marine ecosystem. It is present in the far Eastern Asian maritime waters, including the Pacific Ocean, Sea of Japan, and the East China Sea. Encircling nets, particularly purse seines, are the most used fishing equipment to catch this species. Their fishing grounds are located entirely in coastal areas. Japanese sardine catches have shown varying trends over the last five decades, with a high frequency of captures occurring in the 1980s before collapsing in the early 1990s. The economic and ecological importance of this species has prompted much research, which provided additional information about their spawning migration, distribution, fisheries, and biology. This research was mostly undertaken in the Sea of Japan and its adjacent waters spanning in the north Pacific Ocean. Despite all this research and the importance of this species in its habitats and in commercial fisheries, there is a lack of a recent review presenting the status of global fisheries and biological information for this species. This paper summarizes and updates information on the global geographical distribution, biological aspects, trends in catches, stock fluctuations and assessment, and management measures of the Japanese sardine population. This paper also summarizes information related to the influence of environmental factors on the occurrence of this species and also identifies information gaps. Further research directions are also discussed in this work, which may help improve the knowledge of Japanese sardine and establish rational management measures for their conservation.

Probability assessment of possible ice encounters during the petroleum hydrocarbons transportation in the Sea of Okhotsk

The increase in freight traffic along the Northern Sea Route necessitates the study of the ice regime of the freezing seas of Russia, including the Far Eastern ones (Bering Sea, the Sea of Okhotsk and the Sea of Japan). This paper, on the basis of the analysis of the Sea of Okhotsk’s ice cover and the location of the edges of the Sea of Okhotsk’s ice massif, evaluates the probability of an encounter with ice for the ships in transit during cargo transportation on the Northern Sea Route through the Far Eastern seas along two basic routes from the southern tip of the Kamchatka Peninsula: 1) traverse Cape Lopatka–Sea of Okhotsk–La Perouse Strait; 2) traverse Cape Lopatka–Sangarsky Strait. It was shown that at the stage of ice cover maximum development in the Sea of Okhotsk (February-March), route No. 2 was the most adequate and the safest for ships of ice class Arc4 and below. The section of route No. 1 with a 70 % ice encounter probability was 421 km long in February and 382 km long in March. That section of the route was dominated by very cohesive first-year thin ice up to 70 cm thick with inclusions of first-year ice of average thickness (up to 120 cm).

Trace element composition of the Southwestern Sakhalin Chum Salmon

The study is devoted to the microelement composition of organs and tissues of chum salmon (Oncorhynchus keta), which came for spawning in September 2018 in the r. Lovetskaya on the southwestern coast of Sakhalin. Samples of organs and tissues of fish, prepared in Sakhalin, were frozen and delivered to Vladivostok for chemical analysis. Trace elements were determined from acid mineralizates by atomic absorption on a Shimadzu AA 6800. It was found that the content of microelements indicating anthropogenic impact on the environment (Zn, Cu and Ni) in the Sea of Japan chum was significantly higher than the content of those in the Okhotsk Sea fish. So, for example, the amount of zinc in the muscles of the Sea of Japan chum salmon was 2.5 times higher than in those of the Sea of Okhotsk fish. In the liver, the effect was even greater - the difference between the content of this element in the Sea of Japan and the Sea of Okhotsk reached 19 times. At the same time, in the organs and tissues of the Okhotsk chum salmon, which crossed the impact geochemical zone in the Kuril-Kamchatka region at least twice during its life cycle, the content of lead and cadmium, witnesses of underwater and surface volcanism in the Kuril straits, prevailed. The content of lead in the muscles of chum salmon from r. Raidovaya was 4 times more than in the muscles of chum salmon from the river. Lovetskaya; in the liver, the difference was 5 times.

The shores of the contact zone of the Subarctic and moderately cold seas

Longitude sectorality and latitudinal zonality of morpholithogenesis on the coast of Sakhalin is the result of the unique geographical position of the island, which is a zone of mutual influences and interactions of neighboring geosystems of the subarctic Sea of Okhotsk and the moderately cold northern part of the Sea of Japan – a contact geographical structure. Based on the digitizing of maps of morphogenetic types of shores, modern morpholithodynamic settings and lithological complexes of the coast, geomorphological and morphodynamic differences of the shores of Sakhalin Island are shown, the eastern shores of which have a subarctic appearance, and the western shores are washed by the temperate sea.

Methane Fluxes at the Water–Atmosphere Interface and Gas-Geochemical Anomalies in the Bottom Sediments in the Northwestern Part of the Sea of Japan

—We present results of an integrated research into the spatial distribution of methane in the area of the northern closure of the Central Basin of the Sea of Japan and in the southern part of the Tatar Trough. Methane emissions have been revealed in the study area. The methane fluxes are distributed unevenly within the area (1 to 23 mol/(km2·day)). The discrete high-frequency measurements and calculation of methane fluxes at the water–atmosphere interface, combined with the study of the content of natural gases and microbiologic parameters in sediment cores, allow us to explain the formation of local methane emission zones in the water area. Despite the great sea depths, there are sources and fluid-conducting zones that determine methane concentrations (exceeding the equilibrium ones) and high methane emissions from the water area. The data obtained provide new information and suggest the presence of deep gas sources, which determine gas dispersion in the bottom sediments, the methane content in the surface water layer, and the distribution of methane fluxes at the water–atmosphere interface in the study area. This study is part of the integrated program of geological and geophysical expeditionary research performed by V.I. Il’ichev Pacific Oceanological Institute (Vladivostok) in the northern part of the Sea of Japan.