Perouse Strait Research Articles

Long-term observation of the Soya Warm Current using HF ocean radars: relationship between the Soya Warm Current variability and the sea level anomalies in the Soya/La Perouse Strait

Long-term observation of the Soya Warm Current using HF ocean radars: relationship between the Soya Warm Current variability and the sea level anomalies in the Soya/La Perouse Strait

MODELING THE DYNAMICS OF DISSOLVED OXYGEN CONCENTRATION IN WATERS OF THE ANIVA BAY (THE SEA OF OKHOTSK)

To determine the risks for mariculture farms, the intra-annual change of dissolved О2 concentration was simulated for five zones in the Aniva Bay using the CNPSi model. Zone 1 differed sharply from other zones as the most shallow and freshened. Zone 2 is characterized by a pronounced water exchange with Zone 3 and Zone 4: during spring two layers were formed and stood out in these zones, in the summer the water column was homogeneous. Zone 3 has free water exchange with the open waters of the La Perouse Strait. An outstanding feature of Zone 4, in the deep-water part of the bay, was a distinctive subsidence of waters in the centre of the anticyclonic circulation and the maximum thermocline depth (up to 60-70 m). Zone 5 extends along the western coast of the Tonino-Aniva Peninsula and is characterized by the constant upwelling of waters during the icefree period, which is clearly expressed by lower water temperatures. The calculation showed that in the areas suitable for mariculture farms coastal waters were provided with oxygen throughout the year. Anaerobic conditions developed in spring only in the deepest parts of the bay. An additional source of oxygen in the Aniva Bay is natural thickets of macrophytes, among which the Japanese saccharin (Saccharina japonica) dominates in terms of biomass and area. Annually, Japanese saccharin itself absorbed at least 1200 tons of C in its biomass and supplied at least 3100 tons of О2. Unlike the artificially grown biomass, the biomass of all macrophytes would remain in the system and be destroyed during the life cycle, and the oxygen would be consumed for oxidation. The carbon accumulated in the biomass would again return to the rapid cycle, with the exception of the amount transported to the deep central part of the bay, where it would slowly decompose under nearly anaerobic conditions. It would be possible to place additional algae plantations in the bay, which could absorb up to 49 500 tons of C annually, while supplying up to 132 000 tons of О2. The obtained model estimates could be a starting point for determining the “baseline” of the content of dissolved oxygen and compiling balance equations for gas flows in the ocean-atmosphere system in the Aniva Bay before the development of seaweed plantations, which simultaneously act as carbon farms.

Сейсмичность юга Дальнего Востока России в 2022 году

The paper presents a review of the seismicity of the southern part of the Russian Far East in 2022 based on the data from the catalog of the “Yuzhno-Sakhalinsk” Regional Information Processing Center of the Sakhalin Branch of the Federal Research Center "United Geophysical Survey of the Russian Academy of Sciences". The main parameters of the seismicity, such as the statistical estimation of seismicity level SESL'09, Benioff diagrams, density maps of conditional elastic deformation in 2022 compared to the previous longer time interval, are estimated. A brief analysis of the most significant and interesting earthquakes for detailed study is given. The seismicity of the Kuril-Okhotsk, Sakhalin and the Amur and Primorye regions in 2022 remained within the background values. At the same time, seismic activation was noted in the Sakhalin region, manifested in a number of moderately strong events on the northeastern shelf, in the Uglegorsky district, north of the Schmidt Peninsula, as well as a strong mantle event in the La Perouse Strait with Mw = 5.9. The strongest earthquake of the Kuril-Okhotsk region with Mw = 6.0 occurred in the southern part of the Kuril Island arc. A long series of moderately strong events in the Middle Kurils with Mw up to 5.6 attracts attention. The problem of operational processing of earthquakes in the Amur region and Primorye due to the decreasing number of seismic stations in this region is noted, as well as the systematic underestimation of the energy characteristics of deep-focus earthquakes.

First Satellite Tagging of the Northern Fur Seals (Callorhinus ursinus) on the Tyuleniy Island, the Sea of Okhotsk.

In October 2018, three Northern fur seals (two adult females and one juvenile male) were deployed with satellite tags on the Tyuleniy Island in the Sea of Okhotsk. The operational time of the tags ranged from 33 to 203 days. The adult females started their winter migration in the first half of November; the initial stage of their winter migration occurred in the Japan/East Sea, which they entered through the La Perouse Strait. The juvenile male left the rookery in mid-October, crossed the Sea of Okhotsk in a north-western direction and returned to the south. The male had reached the coastal areas of Hokkaido Island, Japan by the end of November. From the Sea of Okhotsk, the male entered the Pacific Ocean through the Yekaterina Strait and subsequently entered the Japan/East Sea via the Tsugaru Strait. The winter foraging of the male occurred within the north-eastern part of the Japan/East Sea just off the Tsugaru Strait. After 3 months, the male returned to the Pacific and remained off the Sanriku Coast (Honshu Island).

ПРИЛИВНОЙ АПВЕЛЛИНГ НА ЮГО-ЗАПАДНОМ ШЕЛЬФЕ ОСТРОВА САХАЛИН

The materials of instrumental measurements of the current velocity and water temperature at the horizons of 100 and 10 m near the continental slope of southwestern Sakhalin Island (south of Moneron Island) are considered. At a depth of 100 m, diurnal fluctuations in water temperature with an amplitude of 0.5–1°C were revealed, depending on the intensity of tidal currents (temperature decrease when the flow is oriented southeast, towards the La Perouse Strait), interpreted as tidal upwelling. The materials of hydrological surveys on the T1 oceanological section have been analyzed, vertical distributions of water temperature, chlorophyll-a and biogenic elements have been constructed based on the measurements on April 15, 1999. They are consistent with the concept of tidal mixing.

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).

PAHs in the atmospheric aerosols and seawater in the North–West Pacific ocean and sea of Japan

PAHs were analyzed in samples of atmospheric aerosols and suspended matter in seawater collected in the Sea of Japan, Sea of Okhotsk and the North-Western Pacific in June–July 2012. The concentrations of Σ(15) PAHs in the suspended matter of seawater ranged between 1984.7 pg/L to 30260.3 pg/L. The concentration of Σ(14) PAHs in marine aerosols ranged from 17.09 pg/m3 on June 19–22, 2012 in the northern part of the Sea of Japan, the La Perouse Strait to 142.47 pg/m3 on June 25–28, 2012 near middle Kuril Islands. The results of diagnostic ratios analysis indicate that the primary sources of PAH are pyrogenic. This paper discusses the main anthropogenic (coal-fired power plants and population) and natural sources (wildfires) of PAHs and their effect on the concentration of these compounds in the marine air and suspended matter of seawater. Long-range atmospheric transport of PAHs from the continent to the ocean is shown using HYSPLIT backward trajectories. Active fire products (MODIS and VIIRS) data were used to build a regression model. The model as a whole explains 58% and 75% of the Σ 5-ring PAHs and BaP variations in seawater in June–July 2012, respectively. The analysis shows that anthropogenic sources were not a significant contribution factor for PAHs in the seawater at the Sea of Japan during this period.

The Role of Topographically Induced Form Drag on the Channel Flows Through the East/Japan Sea

AbstractThe dynamics responsible for the East/Japan Sea throughflow are examined using the Finite Volume Coastal Ocean Model. Existing ocean data assimilation models (Δx ~10 km) present overestimates of the volume transport through the Tsugaru Strait, and the outflow partitioning between the Tsugaru and Soya/La Perouse Straits also differs depending on the models. We find that this overestimate occurs when the form drag that is induced by detailed bottom topographic features in the Tsugaru Strait is not adequately resolved. A range of experiments with different horizontal resolutions in the Korea/Tsushima, Tsugaru, and Soya/La Perouse Straits were conducted to examine how detailed bottom topographic features in these three straits may affect the throughflow. We find that the volume transport is highly sensitive to the spatial resolution at the Tsugaru Strait but not at the Korea/Tsushima and Soya/La Perouse Straits. The high‐resolution experiment showed a decreased outflow through the Tsugaru Strait and a reduction in the model bias. The outflow through the Soya/La Perouse Strait increased, while the inflow through the Korea/Tsushima Strait remained relatively unchanged. Additional experiments with modified topography further indicated that the abrupt change of the topography located at the upstream side of the Tsugaru Strait plays an important role in the outflow partitioning of the East/Japan Sea throughflow.

ANALYSIS OF INTERANNUAL AND SEASONAL VARIABILITY OF ICE COVER IN ANIVA BAY AND LA PEROUSE STRAIT ACCORDING TO EARTH REMOTE SENSING DATA

Based on the data of satellite observations of the ice cover with the use of geoinformation technologies, an analysis of the interannual and seasonal variability of ice cover in Aniva Bay and La Perouse Strait has been made. It is established that there is a tendency for a decrease in ice cover by 2.5% in Aniva Bay, and in La Perouse Strait – by 11% for the period from 1979 to 2016. It is revealed that Aniva Bay is the only water area with a tendency of increasing ice cover. Based on the analysis of the dynamics of ice cover anomalies relative to the climatic standard norm of 1981- 2010, periods with the predominance of its positive and negative values and years with the highest and lowest values have been marked. It is shown that the ice cover of La Perouse Strait and Aniva Bay has the greatest interrelation with the ice cover in the extreme southern part of the Sea of Okhotsk with a correlation coefficient of 0.76 and 0.66, respectively. The typing of winters according to the severity of ice conditions has been performed according to which it is determined that the sum of severe and extremely severe types of winters in Aniva Bay is higher than that in La Perouse Strait. Analysis of the intra-seasonal course of ice cover made it possible to determine the mean dates for the appearance and disappearance of the ice in Aniva Bay and La Perouse Strait, as well as the duration of the ice period. Aniva Bay is characterized by almost complete filling with ice, which occurs here in severe winters from February 10 to March 10. La Perouse Strait is filled with ice in the severe winters only by 70% - from 15 to 25 of February.

The current status of demersal fish resources in the Russian waters of the Sea of Japan

A bottom trawl survey was conducted over all of the shelf and continental slope in the Russian waters of the Sea of Japan, from Peter the Great Bay to the La Perouse Strait, from March 31 to July 8, 2015. The species composition and biomass of demersal fish were determined for Peter the Great Bay, waters of southern and northern Primorye, and the West Sakhalin subzone. The bulk of the biomass (over 90% of the estimated biomass in the study areas) was formed by four families: Gadidae, Pleuronectidae, Cottidae, and Clupeidae. The highest biomass, 218000 t, was recorded from the West Sakhalin subzone; the lowest, 77400 t, was found from Peter the Great Bay. The proportions of biomasses of the considered species varied substantially between areas: walleye pollock and plain sculpin dominated by biomass in Peter the Great Bay; walleye pollock and scale-eye plaice dominated off southern Primorye; herring dominated off northern Primorye; and scale-eye plaice and speckled founder were dominant in the West Sakhalin subzone. The density of the fish concentration was determined for several bathymetric ranges in the considered areas. In the period of studies, the pattern of distribution of fish in Peter the Great Bay was still of the winter type, which is characterized by high concentrations over the continental slope. There was some shift towards shallower depths in Primorye waters; however, taking the great latitudinal span of the area of the research and the early spring into account, these migrations were not so clearly pronounced, as would be observed in later periods. The most distinct differences in the bathymetric distribution were found in the West Sakhalin subzone, where the distribution pattern corresponded mostly to the summer type with its high concentrations in shallow waters and low ones over the continental slope. According to the estimates in 2015, the biomass of demersal fish slightly increased as compared to the values of the 1980s–1990s.

Postglacial colonisation and diversification of the Jungle Crow (Corvus macrorhynchos) in its north-eastern frontier as revealed by morphological analysis

The Jungle Crow (Corvus macrorhynchos) is a widespread species in Asia that underwent remarkable postglacial recolonisations during the Pleistocene and Holocene. In order to better understand the pattern of its settling and diversification, we investigated the morphological differences among adult Jungle Crow samples obtained from locations in northern Japan and the Russian Far East: Hokkaido, Sakhalin Island, the continental seaboard adjacent to the Tatarsky Strait and the region to the west of the Sikhote-Alin Mountains. We studied four cranial measurements and five bill measurements, as well as body mass from 195 samples. We found clear differences among most populations for both males and females when the various characteristics were observed, especially on Hokkaido and Sakhalin Island; crows from Hokkaido had larger bills and lighter body mass. The differences between the Hokkaido and Sakhalin populations correspond to Bergman’s and Allen’s rules, but this was not the case with the longitudinal cline revealed among the three populations from the Russian Far East. In conclusion, our results suggest that La Perouse Strait separates two assumed recolonisation movements, the first being along the mainland via Ussuriland to Sakhalin and the second along the Japanese Archipelago to Hokkaido. It is evident that this strait is a more effective barrier between Jungle Crow populations than either the Tatarsky Strait or the Sikhote-Alin mountain range.

Estimation of wind drift current in the Soya Strait

Three high-frequency (HF) ocean radars were deployed around the Soya (La Perouse) Strait in 2003 to monitor the Soya Warm Current (SWC). Surface current observed by the HF radars contains a wind drift component, which must be removed in order to estimate the interior SWC. The wind drift parameters, speed factor and turning angle were derived from the surface current measured by the HF radars, the vertical current profile measured by a bottom-mounted acoustic Doppler current profiler (ADCP), and wind data from the numerical weather analysis system operated by the Japan Meteorological Agency (JMA) from October 1, 2006 to July 24, 2008. The ensemble-mean turning angle and speed factor from the entire dataset (excluding August 2007) were estimated to be 28° and 0.66 %, respectively. No significant seasonal variations were discernible in the wind drift parameters. After removal of the wind drift current estimated from the wind with the ensemble-mean drift parameters, the correlation coefficient between the along-shore current speed and sea level difference between the Sea of Japan and Sea of Okhotsk improved from 0.791 to 0.825. It was revealed that the magnitude of wind drift current reaches 45 % of that of the interior current in winter and approximately 20 % in summer, indicating the importance of wind drift current estimation in this region.

The composition and distribution of pelagic ostracods (Ostracoda: Myodocopa) in the Sea of Japan

In the waters of the subarctic structure of the Sea of Japan, the fauna of planktonic ostracods of the Halocyprididae family occurs within the oceanic zone of the sea. In contrast to halocypridids of other Far Eastern seas of Russia, this fauna is depauperated and isolated from the Pacific fauna. Deep-water species of halocypridids are absent; the only inhabitant of deep water is an interzonal eurytopic, Discoconchoecia pseudodiscophora (Rudjakov, 1962), which is found in the open part of the Sea of Japan from the surface to great depths. The maximum abundance of pelagic ostracods in the Sea of Japan was observed in the mesopelagic zone. The northern boundary of the distribution of tropical-subtropical species of halocypridid ostracods runs along 38°–40° N in the southern Sea of Japan and along the La Perouse Strait in the eastern part of the sea (based on the data for the 1970s–1980s). Benthic ostracods of the families Philomedidae and Cypridinidae (which are found in the meroplankton only during their spawning period) inhabit the neritic zone of the cold-water and warm-water parts of the Sea of Japan.

Estimation of biogenic substance transport by water masses in Tatar Strait

The conditions of transformations of biogenic substances and the redistribution of their concentrations in the shelf water of Sakhalin Island are studied. Preliminary works have given the results for the water area of La Perouse Strait and Aniva Bay (the Sea of Okhotsk), while this paper gives such results for Tatar Strait (the Sea of Japan). Three electronic instruments of oceanographic studies are applied: an adapted version of Bergen Oceanic Model (for the reconstruction of the space and time distribution of seawater temperature, salinity, and density; the circulation intensity of water masses; and water exchange parameters with nearby water areas and within the strait); GIS “Sakhalin Shelf” (for the reconstruction of annual variations in thermohaline characteristics on a standard grid and horizons of oceanographic stations, and the parameters of the aquatic environment); hydroecological CNPSi-model (for studying the annual dynamics of biogenic element compounds, the biomasses, biohydrochemical activity and bioproduction of microorganisms—bacteria, phytoplankton, and zooplankton, taking part in transformation of biogenic substances and petroleum hydrocarbons, as well as the internal fluxes of biogenic substances governed by the activity of microorganisms and the external load on the marine ecosystem). The results of modeling the spatial transport of biogenic substances through the outer boundaries of Tatar Strait water area and the boundaries of the three areas identified within it are presented and discussed.

宗谷海峡のミズダコの資源管理とたこ漁家経営の両立を目指した資源管理システム

宗谷海峡のミズダコの資源管理とたこ漁家経営の両立を目指した資源管理システム

Observation of the Soya Warm Current using HF ocean radar

Three High Frequency (HF) ocean radar stations were installed around the Soya/La Perouse Strait in the Sea of Okhotsk in order to monitor the Soya Warm Current (SWC). The frequency of the HF radar is 13.9 MHz, and the range and azimuth resolutions are 3 km and 5 deg., respectively. The radar covers a range of approximately 70 km from the coast. The surface current velocity observed by the HF radars was compared with data from drifting buoys and shipboard Acoustic Doppler Current Profilers (ADCPs). The current velocity derived from the HF radars shows good agreement with that observed using the drifting buoys. The root-mean-square (rms) differences were found to be less than 20 cm s−1 for the zonal and meridional components in the buoy comparison. The observed current velocity was also found to exhibit reasonable agreement with the shipboard ADCP data. It was shown that the HF radars clearly capture seasonal and short-term variations of the SWC. The velocity of the Soya Warm Current reaches its maximum, approximately 1 m s−1, in summer and weakens in winter. The velocity core is located 20 to 30 km from the coast, and its width is approximately 40 km. The surface transport by the SWC shows a significant correlation with the sea level difference along the strait, as derived from coastal tide gauge records at Wakkanai and Abashiri.

Thermohaline analysis of the La Perouse Strait water

Sakhalinskii Shel’f information and analytical GIS based on observational data is used to simulate hydrological parameter values at standard horizons of stationary stations in the La Perouse Strait. The spatial and temporal distribution pattern for oceanographic parameters has been obtained. Water masses and water structures have been identified using classic T, S-analysis. Volumetric T, S-analysis of waters is used to evaluate the volumes, heat content, and salinity of the water masses chosen. For the first time, information for the winter season, which is the least investigated season and for which no generalizations whatsoever have been made until the present, has been obtained.

Studying the Ecosystem Functioning Conditions in Aniva Bay–La Perouse Strait

An atlas of oceanographic data on the shelf zone of Sakhalin Island and a mathematical model describing the transformations of nutrient compounds (N, P, Si, C) are used to study the biotransformation and transport of organic and mineral components of these elements in the La Perouse Strait. To make the analysis more convenient, the area under examination was divided into four zones, which differ in the conditions of transport of matter in water flows. Transport calculations are made using a complex graphic method with geostrophic approximation, which takes into account the results of instrumental observations of flow velocities, sea level variations, and annual variations in the water volumes. The obtained patterns of dynamics of nutrient compounds are compared with the results of modeling of internal and external fluxes of those components. Calculated fluxes of the elements were used to assess the rate of chemicals and biomass transport through the boundaries of water areas (in particular, between the Seas of Japan and Okhotsk).

Structure of terrestrial crust in southern Sakhalin and adjacent aquatoria

Recent deep seismic sounding and other data suggest presence of a deep rift which cuts across southern Sakhalin, Aniva Bay, La Perouse Strait, and Hokkaido Island, a suboceanic type of crust in the Sea of Okhotsk, and a continental one in Sakhalin. The density-velocities relationship determined here may account for the observed gravity anomalies as due primarily to variations in thickness of the crust (fig. 6), without resorting to other hypotheses.

極東亞産スゲ屬植物の分布 (續報)

1. Carices of this region are much more connected to the outer regions through Saghalien than the Kurile Isls..2. The Kurile Isis. may be divided into three districts on the phytogeographical point of view.3. Some Saghalien species are found in south-eastern Hokkaido or Isl. Shikotan, and the species existing in Honshiu are partly found only in the central to eastern Hokkaido.4. La Perouse Strait and Tsugaru Strait divide the distributions, but not so evidently.5. Quelpaert are more closely related to Japan than the Korean peninsula.6. Some species grow in Central China, (Southern Korea) and Japan.7. Utricles float for a long time, showing the most important factor for the distribution, and the sea currents are useful for this purpose.8. The distributions have much references along with the climatic and edaphic conditions since Tertiary period, and also width of habitats in respective species.9. Some Australian species resemble those of this region, and the endemic species in the small islands show remarkable features. These facts suggest us the formation of the new species of Carices rather in short times.