North-western Sea Research Articles

Oceanological studies in the northwest Pacific, Japan and Okhotsk seas in the 73th cruise of the RV Professor Gagarinskiy and 53th cruise of the RV Academic Oparin

During the the 73th cruise of the RV Professor Gagarinskiy and 53th cruise of the RV Academic Oparin oceanological studies of the north-western Pacific, Japan and Okhotsk Seas were conducted. New data on the structure sea bottom, water composition as well as slope convection of the Japan Sea.

Development of Cascade Cyclogenesis in the Northwestern Sea of Japan

Development of Cascade Cyclogenesis in the Northwestern Sea of Japan

The Population Genetic Organization of Pacific Cod Gadus macrocephalus in the North Pacific Based on Microsatellite Analysis

Six groups have been identified in the species' population structure based on the analysis of microsatellite markers' polymorphism in Pacific cod Gadus macrocephalus samples within the entire western part of the North Pacific, including waters of the Pacific coast of Canada. The first group includes cod from waters of the Yellow Sea; the second group consists of cod from the Sea of Japan (eastern coast of Korea and Peter the Great Bay); the third group combines cod from Tatar Strait and the South Kuril Islands (both Sea of Okhotsk and Pacific Ocean sides); the fourth group is formed by cod from the northwestern Sea of Okhotsk and Taui Bay; the fifth-largest group includes cod from waters off western Kamchatka, the North Kuril Islands (Sea of Okhotsk and Pacific Ocean sides), Karaginsky Bay, Navarinsky area in the Bering Sea, and Anadyr Bay; the sixth group is formed by cod from coastal waters of Canada.

Surface Heat Budget over the North Sea in Climate Change Simulations

An ensemble of regional climate change scenarios for the North Sea is validated and analyzed. Five Coupled Model Intercomparison Project Phase 5 (CMIP5) General Circulation Models (GCMs) using three different Representative Concentration Pathways (RCPs) have been downscaled with the coupled atmosphere–ice–ocean model RCA4-NEMO. Validation of sea surface temperature (SST) against different datasets suggests that the model results are well within the spread of observational datasets. The ensemble mean SST with a bias of less than 1 ∘ C is the solution that fits the observations best and underlines the importance of ensemble modeling. The exchange of momentum, heat, and freshwater between atmosphere and ocean in the regional, coupled model compares well with available datasets. The climatological seasonal cycles of these fluxes are within the 95% confidence limits of the datasets. Towards the end of the 21st century the projected North Sea SST increases by 1.5 ∘ C (RCP 2.6), 2 ∘ C (RCP 4.5), and 4 ∘ C (RCP 8.5), respectively. Under this change the North Sea develops a specific pattern of the climate change signal for the air–sea temperature difference and latent heat flux in the RCP 4.5 and 8.5 scenarios. In the RCP 8.5 scenario the amplitude of the spatial heat flux anomaly increases to 5 W/m 2 at the end of the century. Different hypotheses are discussed that could contribute to the spatially non-uniform change in air–sea interaction. The most likely cause for an increased latent heat loss in the central western North Sea is a drier atmosphere towards the end of the century. Drier air in the lee of the British Isles affects the balance of the surface heat budget of the North Sea. This effect is an example of how regional characteristics modulate global climate change. For climate change projections on regional scales it is important to resolve processes and feedbacks at regional scales.

Evaluating resource sharing for offshore wind farm maintenance: The case of jack-up vessels

Offshore wind energy is recognised globally as a viable alternative to finite energy sources. However, large cost reductions are still needed, particularly in the Operations & Maintenance (O&M) phase, which currently accounts for about 30% of the cost of offshore wind. For large component replacements, a jack-up vessel is often leased from the spot market, resulting in high costs and low utilisation. These costs can be lowered when multiple wind farm service providers would share the resources needed to employ jack-up vessels. In this paper, we analyse two types of resource sharing, as an alternative to each service provider leasing its own vessel: (i) vessel purchasing and sharing and (ii) the combined use of vessel and harbour sharing. We design a simulation model and include stochastic processes such as weather patterns and component failures. Results show that cost benefits up to 45% can be achieved compared to a leasing policy, depending on the number of wind farm service providers involved and on the geographical distance between offshore wind farms. Moreover, it is shown that the jack-up vessel should not be fully utilised to minimise costs. The performance benefits of harbour sharing in addition to vessel sharing are generally small, but become more significant if the network faces considerable congestion. Results are illustrated using a case study based on a setting in the Western North Sea.

Pseudo-nitzschia species (Bacillariophyceae) and the domoic acid concentration in Pseudo-nitzschia cultures and bivalves from the northwestern Sea of Japan, Russia

Pseudo-nitzschia species (Bacillariophyceae) and the domoic acid concentration in Pseudo-nitzschia cultures and bivalves from the northwestern Sea of Japan, Russia

The mixed‐bed glacial landform imprint of the North Sea Lobe in the western North Sea

AbstractDuring the last glacial cycle an intriguing feature of the British‐Irish Ice Sheet was the North Sea Lobe (NSL); fed from the Firth of Forth and which flowed south and parallel to the English east coast. The controls on the formation and behaviour of the NSL have long been debated, but in the southern North Sea recent work suggests the NSL formed a dynamic, oscillating terrestrial margin operating over a deforming bed. Further north, however, little is known of the behaviour of the NSL or under what conditions it operated. This paper analyses new acoustic, sedimentary and geomorphic data in order to evaluate the glacial landsystem imprint and deglacial history of the NSL offshore from NE England.Subglacial tills (AF2/3) form a discontinuous mosaic interspersed with bedrock outcrops across the seafloor, with the partial excavation and advection of subglacial sediment during both advance and retreat producing mega‐scale glacial lineations and grounding zone wedges. The resultant ‘mixed‐bed’ glacial landsystem is the product of a dynamic switch from a terrestrial piedmont‐lobe margin with a net surplus of sediment to a partially erosive, quasi‐stable, marine‐terminating, ice stream lobe as the NSL withdrew northwards.Glaciomarine sediments (AF4) drape the underlying subglacial mixed‐bed imprint and point to a switch to tidewater conditions between 19.9 and 16.5 ka cal BP as the North Sea became inundated. The dominant controls on NSL recession during this period were changing ice flux through the Firth of Forth ice stream onset zone and water depths at the grounding line; the development of the mixed‐bed landsystem being a response to grounding line instability. © 2018 John Wiley & Sons, Ltd.

Morphological and genetic variability of Skeletonema dohrnii and Skeletonema japonicum (Bacillariophyta) from the northwestern Sea of Japan

ABSTRACTSpecies of the genus Skeletonema are one of the most common marine planktonic diatoms of the temperate zone of the World Ocean. Despite the worldwide distribution of the genus, there are only fragmentary data on its ecology and quantitative characteristics of habitats, as well as limited information on the species diversity in the northeastern Pacific Ocean. In the present study, 13 strains of Skeletonema were obtained from planktonic and benthic samples of microalgae collected during the period from 2009 to 2017 from the northwestern Sea of Japan. We identified Skeletonema dohrnii and S. japonicum based on light and electron microscopic observations and molecular genetic analysis of 28S rDNA sequences. A detailed description, as well as new data on water temperature, salinity and species distribution, is provided for each species and their morphological features are discussed. The presence of several rimoportula processes on the terminal valve of Skeletonema species is shown for the first time. Our results support the usage of the topological criterion for the delimitation of the S. dohrnii–marinoi, as opposed to the distance-based criterion.

Current Data on the Taxonomic Composition and Distribution of the Trawl Macrozoobenthos in Russian Waters of the Sea of Japan

A complex bottom trawl survey (430 stations) was conducted over all of the shelf and continental slope (within a depth range of 10–750 m) in the Russian waters of the Sea of Japan from April 1 to July 8, 2015. A total of 211 taxa of invertebrates were recorded from trawl catches. The most widely represented of them were starfish (36), shrimps (32), gastropods (27), bivalves (23), brachyuran and anomuran crabs (11), polychaetes (11), coral polyps (10), and sponges (10). The total recorded biomass of macrozoobenthos in benthic biotopes of the northern Sea of Japan reached 1 572 500 t (136 600 t in Peter the Great Bay, 341 500 t in the Southern Primorye area, 686 000 t in the northern Primorye area, and 408 400 t in the Western Sakhalin subzone), which is higher than the mean long-term level. The total stock of commercial invertebrates was estimated at 630 000 t. Its largest portion (265 200 t, or 42.1%) was concentrated in the northern Primorye area (western Tatar Strait). The mean specific biomass of the trawl macrozoobenthos constituted 13.5 ± 1.1 g/m2 (including 6.3 ± 0.5 g/m2 of commercial benthic species). The most abundant groups were brittle stars (372 200 t), brachyuran crabs (231 600 t), anomuran crabs (48 700 t), shrimps (226 900 t), sponges (182 900 t), sea lilies (167 500 t), starfish (77 200 t), sea urchins (59 000 t), and bivalves (49 500 t). The vertical distribution of the total benthos and its commercial portion was characterized by maxima in the upper shelf (10–50 m) and within a depth range of 300–400 m. In the northwestern Sea of Japan, 18 biocenotic complexes of trawl macrozoobenthos were identified. The largest areas were occupied by the group of the sedentary seston-feeding sea lily Heliometra glacialis (biomass 5.5 g/m2, depth range of 104–692 m, 131 stations), the group of the polyphagous snow crab Chionoecetes opilio (4.4 g/m2, 27–552 m, 71 stations), the group of the mobile seston-feeding basket star Gorgonocephalus eucnemis (6.6 g/m2, 58–372 m, 40 stations), and the group of the polyphagous pale yellow sea urchin Strongylocentrotus pallidus (4.7 g/m2, 17–351 m, 40 stations).

Bioindication of Heavy-Metal Pollution in the Coastal Marine Waters of Russky Island (Peter the Great Bay, Sea of Japan)

The first assessment of the condition of coastal waters around Russky Island, Peter the Great Bay, in the vicinity of Vladivostok, has been made based on the data on concentrations of Fe, Zn, Cu, Cd, Pb, and Ni in the brown algae Sargassum miyabei and S. pallidum collected along the coast of the island in July and August 2016. It has been found that the concentrations of heavy metals in algae from waters off Russky Island mostly exceed their background levels in Sargassum algae from the northwestern Sea of Japan. On the southeastern side of the island, facing Ussuri Bay, which is distinguished by a rocky/bouldery coast and beds of S. pallidum, algae are characterized by lower concentrations of trace elements than those on the other sides.

Sex change in scallop Patinopecten yessoensis: response to population composition?

Sex structure is very labile between populations and specific for each population because it is a result of genetic, ontogenetic and biocenotic influences on the mollusks. In this study, the age frequency distribution, age-sex structure, and sex ratio were assessed in the wild populations of the Yeso scallop Patinopecten yessoensis (Jay) observed at fifteen sites in the northwestern Sea of Japan (=East Sea). The sex ratio varied between the populations from 0.83:1 to 1.52:1 (males/females), with the mean sex ratio being 1.03 ± 0.05:1. Within a population, the proportions of males and females in term of number differed between age classes. Males were more numerous than females in the younger age classes, and females prevailed over males in the older age classes. It was found that in different scallop populations the sex change occurred at different ages. In the populations that predominantly consisted of young (two- to four-year-old) individuals, males prevailed over females in the age class 2 yr.; the equal male/female proportion was found in the age class 3 yr.; and in older age classes, females prevailed over males. Another pattern was observed in the populations that consisted mainly of middle-aged (five- to six-year-old) individuals. Here, the age-sex ratio became equal at an age of 4–6 years. In the old populations (mainly 6–12-year-olds) the equal male/female proportion was observed at an age of 8–10 years. Thus, the age of sex change was not uniform for the scallop populations. It depended on the age structure of the population and, thus, was socially controlled. The greater number of females in the older age classes suggests a protandric sex change.

Genetic and Morphometric Variability in Settlements of Two Mussel Species (Mytilusex. gr.Edulis),Mytilus trossulusandMytilus galloprovincialis, in the Northwestern Sea of Japan

Genetic and morphometric variability in mussels are the important issues that attract the attention of numerous researchers with special emphasis in recent years on hybrid occurrence and genetic introgression. Here, the genetic and multidimensional discriminant function analysis (DFA) that included morphometric traits (MT) were performed on mussels, Mytilus trossulus and Mytilus galloprovincialis, taken from the northwestern Sea of Japan (NWSJ). The analysis, based on eight polymorphic enzyme loci and two nuclear DNA markers, used samples from eight settlements in 2011 and samples from six settlements in 2012 to 2013 for a smaller set of loci but jointly with MT analysis. If the average generation length is taken as three years, the number of immigrants (Nm) per generation was estimated approximately as Nm = 5. Assuming that interspecific gene flow is from the offspring of generations such as F2, F3, and Fb rather than F1, the fraction of interspecific migrants estimated as Fb F2 etc. are equal to 0.9% ± 0.7%. The data suggest a continuing invasion of M. galloprovincialis into NWSJ. Judging from the occurrence of hybrids of all types, it is clear that rate of genetic introgression between two taxa is at a low level, varying across 14 y in the sampled Vostok Bay area from 0% in 2012 to 2013 (this study) to 8.95% ± 1.68% back in 1999. The data support the concept of a bimodal hybrid zone, with the contact zone showing a limited degree of hybridization of two species. Analysis by DFA, using GLU-5 genotypes as a diagnostic grouping variable, allows the determination of the extent to which indigenous phenotypes and hybrids differ; M. trossulus and F1 offsprings in the 2012 to 2013 data were detected correctly with a high accuracy, near 94%. Despite that, DFA showed generally weak differentiation of settlements even with the use of a combined set of traits and indices.

The Parasitic Fauna of Common Species of Hermit Crabs of Vostok Bay (Sea of Japan)

The parasitic fauna of common species of hermit crabs was investigated in Vostok Bay (the northwestern Sea of Japan). Pagurus proximus and Areopaguristes hirsutimanus had no parasites. The average prevalence of rhizocephalan infestation in other five species of hermit crabs ranged from 5.67 to 20.83%. The prevalence of the isopod Parapseudione lata on hermit crabs did not exceed 1%, the prevalence of infestation with the isopod Athelges takanoshimensis was significantly higher, reaching 14.58% in Pagurus middendorffii. Parasitism by the isopod P. lata on the hermit crabs Pagurus minutus and P. ochotensis, as well as parasitism by the rhizocephalan Peltogaster reticulata on P. minutus were recorded for the first time. Several variants of simultaneous infestation with two parasitic species were found. The decline in the abundance of P. middendorffii accompanied by the high prevalence of parasites, primarily the colonial rhizocephalan Peltogasterella gracilis, suggests that parasite invasion may play a more significant role in regulating the abundance of hermit crabs than was previously assumed.

Smooth lumpsucker Aptocyclus ventricosus in the northwestern Sea of Japan: distribution and some life history traits

Abstract This paper is focused on horizontal, vertical, and temperature-dependent distributions, size composition of bottom and mid-water trawl catches, and biomass estimations of smooth lumpsucker Aptocyclus ventricosus (Pallas) (Cyclopteridae) within the Russian Exclusive Economic Zone (EEZ) of the northwestern Sea of Japan. This species is distributed very widely throughout the study area inhabiting both near-bottom layers and water column. It is less abundant in small bays and in the northern Tatar Strait (north to 50°N). Despite wide bathymetric (0 to 940 m) and temperature (-1.1 to +12.2 °C) ranges this species occurred mainly within the lower mesopelagic zone of 400-800 m depths and cold temperatures of -0.5-1°C. In the near-bottom layer catches of smooth lumpsucker were represented by fish with TL 5-45 cm (mean 28.1 cm, dominant lengths 29-37 cm) while in water column its TL varied 4 to 41 cm with mean 17.9 cm, most abundant were fish with TL 8-15 and 24-31 cm; the difference is associated with specific life history aspects of the species considered. Recent increase of smooth lumpsucker biomass in the study area was observed with estimated value of 3000 t in the northern Primorye.

Роль трещиноватости молодого возраста в формировании и пространственном размещении углеводородных залежей на Северо-Западном Каспии

Роль трещиноватости молодого возраста в формировании и пространственном размещении углеводородных залежей на Северо-Западном Каспии

The Morphological, Genetic and Physiological Characteristics of a Benthic Dinoflagellate of the Genus Ostreopsis Isolated from Coastal Waters of the Northwestern Sea of Japan

A previous molecular-genetic analysis of clonal cultures and single cells of Ostreopsis spp. that were isolated from Peter the Great Bay (the Sea of Japan) revealed three different genotypes according to the nucleotide sequences of ribosomal DNA (rDNA). Of these, Ostreopsis sp. 1 was earlier found only off the coast of Japan and described as being the most common and highly toxic. We have obtained further molecular evidence and have studied the morphological features of cells from one of the Ostreopsis strains with this genotype and some aspects of its growth at salinities of 24, 28, and 32‰. The results showed that in cells from the Russian coast of the Sea of Japan, the third apical (3') and the third precingular (3") plates do not adjoin one another, being separated by the elongated second apical (2') plate. Cells of Ostreopsis sp. 1 from the Russian coast are significantly larger than Ostreopsis sp. 1 cells with the same genotype from the coast of Japan. Salinity did not have a substantial effect on the growth of Ostreopsis sp. 1. The growth rate varied from 0.24 to 0.35 divisions per day, with maximum values at a salinity of 24‰. When salinity decreased to 24‰, the exponential growth phase was significantly extended and the maximum cell concentration doubled.

Possible impacts of a changing climate on intense Ligurian Sea rainfall events

ABSTRACTThe region near the Ligurian Sea in northwestern Italy occasionally experiences extreme rainfall events that can lead to catastrophic flooding. These events are often caused by back‐building mesoscale convective systems whose occurrence peaks during the autumn. Rapid warming of the Mediterranean Sea in recent decades has raised concerns that the warmer water may change the frequency or intensity of these rainfall events. To gain insight into possible impacts of the warming climate, surface wind and precipitation output from 12‐km horizontal grid spacing EXPRESS‐Hydro simulations of past and future climate are used to examine trends in the frequency of strong convergence and heavy rainfall events during both the past and the future climate. Strong convergence events are not found to increase in frequency in the future climate, but the rainfall associated with these events does increase. The area that experiences rainfall above a specified threshold along with the duration over which such conditions are experienced increases, especially during the autumn when increases are statistically significant. Peak 3‐hourly rainfall at a grid point does not increase in the future climate but total rain volume associated with these events does, reflecting the larger areal coverage and duration of the events.

Poputnye vctrechi kitoobraznykh v severo-zapadnoj chasti Tikhogo okeana i Okhotskom more v mae–iyune 2017

Poputnye vctrechi kitoobraznykh v severo-zapadnoj chasti Tikhogo okeana i Okhotskom more v mae–iyune 2017

Identifying stock structuring in the sandeel, Ammodytes marinus, from otolith microchemistry

Identifying the scale of population processes is important for sustainable fisheries management. In the North Sea, the lesser sandeel, Ammodytes marinus, is now managed as seven stocks delineated on the basis of biophysical model predictions of the limited scale of larval mixing. This study used otolith chemistry to evaluate whether the stock units defined from these predictions actually reflect the degree of isolation of early life stages. Elemental composition near the core, settlement check and summer opaque zone were examined using laser ablation-inductively coupled plasma mass spectrometry in young of the year, sampled across 8 grounds within three of the main fished stocks in 2011. There were significant spatial differences in otolith chemistry enabling post-settled juveniles to be discriminated among stock areas and even between some grounds. Clustering of near core chemistry pointed to four natal sources, with dominant clusters in each of the three stocks studied and one unique to the Central Western North Sea (sandeel assessment area 4). Moreover, near core chemistry was similar to that of post-settled juveniles at the stock area level. Consistency in the scaling of early life mixing predicted by biophysical models and otolith chemistry supports the present stock units used in assessments.

Phytoplankton and Hydrochemical Parameters Near Net Pens with Beluga Whales in a Shallow Bay of the Northwestern Sea of Japan

The dynamics of phytoplankton composition and main hydrochemical parameters have been studied in Paris Bay, northwestern Sea of Japan. This body of water draws particular attention due to the captive beluga whales, Delphinapterus leucas, which are kept in open net pens here. According to the results of investigations conducted, the main factors that influence the hydrochemical parameters in this area are the water exchange, terrestrial runoff, ice melting, and phytoplankton blooms. Phytoplankton has the most pronounced effect in early spring, when its destruction is accompanied by a significant increase in concentration of dissolved nutrients, and in early summer, when proliferation of diatoms causes a depletion of nutrients. An analysis of the hydrochemical parameters and phytoplankton composition has shown that the marine mammals kept in captivity exert no impact on trophicity of the waters in Paris Bay. The dynamics of abundance of micro-algae are characterized by two or three peaks a year; the pattern of these dynamics is typical of most shallow bays in the northwestern Sea of Japan. Diatom species of the genus Skeletonema (S. dohrnii and S. japonicum), which are new to the marine waters of Russia, have been found for the first time.