Onekotan Research Articles

МОРСКАЯ ЭКСПЕДИЦИЯ НА КУРИЛЬСКИЕ ОСТРОВА ЛЕТОМ 2022 Г.

This report presents a brief description of the expeditionary work performed by the staff of the Institute of Volcanology and Seismology, Far Eastern Branch of the Russian Academy of Sciences as part of the research topic and the Russian Science Foundation project on the Kuril Islands in the summer of 2022. In order to study the chemical erosion of volcanic islands and to assess the hydrothermal removal of magmatic volatiles, in addition to the works carried out in 2020 and 2021, hydrological and hydrochemical studies were comducted on the rivers draining the slopes of the volcanic ridges of the Paramushir, Onekotan and Shiashkotan islands. For the first time, with the help of a quadrocopter, sampling of the endorheic Lake Koltsevoe, which occupies the caldera of the Tao-Rusyr volcano (Onekotan Island), was carried out. A detailed hydrochemical testing on the thermal fields of the active volcanoes Sinarka and Kuntomintar (Shiashkotan Island) was performed, a number of regime observations of the Upper Yuryevsk springs (Paramushir Island) were replenished. In order to construct orthophotomaps and determine the boundaries of thermal anomalies, aerial and infrared surveys were carried out at the main study sites in parallel with geochemical sampling. A large number of water and gas samples were taken for further analytical studies during the expedition and the collection of sediments was replenished.

Kurilosides A1, A2, C1, D, E and F-Triterpene Glycosides from the Far Eastern Sea Cucumber Thyonidium (= Duasmodactyla) kurilensis (Levin): Structures with Unusual Non-Holostane Aglycones and Cytotoxicities.

Six new monosulfated triterpene tetra-, penta- and hexaosides, namely, the kurilosides A1 (1), A2 (2), C1 (3), D (4), E (5) and F (6), as well as the known earlier kuriloside A (7), having unusual non-holostane aglycones without lactone, have been isolated from the sea cucumber Thyonidium (= Duasmodactyla) kurilensis (Levin) (Cucumariidae, Dendrochirotida), collected in the Sea of Okhotsk near Onekotan Island from a depth of 100 m. Structures of the glycosides were established by 2D NMR spectroscopy and HR-ESI mass spectrometry. Kurilosides of the groups A and E contain carbohydrate moieties with a rare architecture (a pentasaccharide branched by C(4) Xyl1), differing from each other in the second monosaccharide residue (quinovose or glucose, correspondingly); kurilosides of the group C are characterized by a unique tetrasaccharide branched by a C(4) Xyl1 sugar chain; and kurilosides of the groups D and F are hexaosides differing from each other in the presence of an O-methyl group in the fourth (terminal) sugar unit. All these glycosides contain a sulfate group at C-6 of the glucose residue attached to C-4 Xyl1 and the non-holostane aglycones have a 9(11) double bond and lack γ-lactone. The cytotoxic activities of compounds 1–7 against mouse neuroblastoma Neuro 2a, normal epithelial JB-6 cells and erythrocytes were studied. Kuriloside A1 (1) was the most active compound in the series, demonstrating strong cytotoxicity against the erythrocytes and JB-6 cells and a moderate effect against Neuro 2a cells.

Two new species of holothurians of the genus Echinopsolus Gutt, 1990(Echinodermata: Dendrochirotida: Cucumariidae) from the North-Western Pacific.

Two new species of the genus Echinopsolus-E. sanamyanorum and E. onekotanensis are described. This genus is new for North-Western Pacific marine fauna. Echinopsolus sanamyanorum was collected in the Avacha Gulf (south-east coast of Kamchatka), E. onekotanensis-near the Onekotan Island (The Kuril Islands).

Самые крупные озера Курильских островов: морфометрия и географическое распределение (материалы к базе данных)

The work presents modern data on the location, morphometry, and genesis of the largest lakes basins of the Kuril Islands obtained in the volcanological expeditions of the IMGG FEB RAS during 2005– 2018 and using open geographic information resources. 1099 lakes were sampled according to the criterion S ≥ 1 km², the list of studied objects included 20 reservoirs, represented by 7 volcanic and 13 lagoon lakes. The considered lakes are clearly divided according to their origin, area and height of the mirror, and maximum depth. The most part of large lakes falls on the Southern Kurils, and the largest water body – the volcanic lake Koltsevoe – is located on Onekotan Island, which is a part of the group of the Northern Kurils. Volcanic lakes occupy an area of 48.26 km² (60 % of the total area of 20 lakes), the depth varies in the range from several tens to several hundred meters. This category of lakes is characterized by relatively high levels of the mirror, which range from 50 to 648 m above sea level. Lagoon lakes occupy an area of 32.15 km² (40 % of the total area of 20 lakes), the depth of water bodies is small – from 1 to 23 m, the absolute height of the lake mirror is from 1–5 to 8–9 m.

Floristic findings on the Onekotan island clarify biogeographic subdivision of the Northern Kurils, Russian Far East

Floristic subdivision of the northern part of the Kuril archipelago (Russian Far East) remains controversial. Such uncertainty in biogeographical subdivision could be caused by insufficient floristic data due to poor accessibility of mainly uninhabited northern Kuril islands. We aimed to explore the flora of the largest uninhabited northern Kuril island Onekotan to clarify its position in floristic subdivision. All the 19 species that we added to the known flora of Onekotan island grow on Paramushir and often on some other northern Kurils. Additionally, we revealed two species (Minuartia rubella and Poa lanata) that are new for the whole Kuril archipelago. Our findings demonstrated that floristic similarity between Onekotan and the both large northern continental Kuril islands (Shumshu and Paramushir) is higher than it was demonstrated before. However, discussion of floristic subdivision of the Northern Kurils is premature unless all the islands are sufficiently studied.

Feeding Habits of the Atka Mackerel Pleurogrammus monopterygius in Waters off the Central Kuril Islands

The diet composition, stomach fullness, and condition factor of different size groups of the Atka mackerel Pleurogrammus monopterygius were studied in the area of the submarine plateau located in the Pacific waters off the central Kuril Islands, southeast of Onekotan Island, in June–July 1996. According to previously published data, mesopelagic fish forms the major part of the diet of Atka mackerel in this area, but the present study has revealed the leading role of Copepoda and Appendicularia, which is explained by different sites of material sampling: respectively, in the areas adjacent to the edge of the plateau and in its central part. It is assumed that the substantially lower condition factor of fish, as compared to previously published values, with the similar stomach fullness indices may result from the consumption of mainly low-calorie food (copepods and appendicularians).

Psolusosides C1, C2, and D1, Novel Triterpene Hexaosides from the Sea CucumberPsolus fabricii (Psolidae, Dendrochirotida)

Three new triterpene glycosides, psolusosides C1 (1), C2 (2) and D1 (3) have been isolated from the sea cucumber Psolus fabricii collected in the Sea of Okhotsk in the shallow waters of Onekotan Island (Kurile Islands). Five known glycosides: cladolosides B, M1, P2, isolated earlier from the sea cucumbers of genus Cladolabes and holotoxin A1 with 27- nor-25-oxo-holotoxin A1, isolated earlier from Apostichopus japonicus have also been found. The glycoside structures were elucidated by 2D NMR spectroscopy and HR mass-spectrometry. Compounds 1–3 possess hexasaccharide carbohydrate chains, identical for 1 and 2 and different in the third monosaccharide residue for 3. All the glycosides comprise holostane type aglycones with a 9(11)-double bond and a 16-keto-group and differ from each other in the side chains structures.

Кальдерное озеро Кольцевое: современное состояние и строение котловины (о. Онекотан, Курильские острова)

Кальдерное озеро Кольцевое: современное состояние и строение котловины (о. Онекотан, Курильские острова)

Marker tephra layers in the late quaternary deposits of the Sea of Okhotsk as evidence of catastrophic eruptions in the Nemo caldera complex (Onekotan Island, Kuril Islands)

On the basis of complex studies of tephra layers (morphology of volcanic glass particles, chemical composition of glass particles and minerals, and REE distribution), marker tephra layers (K2, K3) were distinguished in the stratigraphic columns in the area of the Sea of Okhotsk. The areas of distribution of tephra layers and their age datings were determined. Tephra layers are shown to be similar in their chemical composition. They are correlated with strong explosive eruptions in the Nemo caldera complex on Onekotan Island (northern part of the Kuril Islands) in the Late Pleistocene.

On the spawning of Pacific cod Gadus macrocephalus in the southeastern waters off Onekotan Island

On the spawning of Pacific cod Gadus macrocephalus in the southeastern waters off Onekotan Island

Reanalysis of long-term surveys on the ecology and biology of mud skate (Rhinoraja taranetzi Dolganov, 1985) in the northwestern Pacific (1993-2002)

Summary Based on data sampled in 1992–2002, the occurrence, spatial distribution, bathymetry, bottom temperatures preferences, size composition, feeding, and some features of reproductive biology of mud skate Rhinoraja taranetzi in the Pacific waters off the northern Kuril Islands and southeastern Kamchatka are considered. Throughout the year, the mud skate was most abundant in the central part of the study area, from the coast of Onekotan Island to the southern tip of Kamchatka peninsula. The proportion of this species in bottom trawl catches in different seasons has changed slightly. However, maximum catch occurred in September–December. In April–May mud skates occupied shallower depths (mean 230–270 m), moving deeper in the summer period (mean 340–390 m). In December–March the skate occurred at lower bottom temperatures (mean 0.8–1.6°C) whereas the rest of the year it inhabited warmer waters with mean bottom temperatures of 2.5–3.1°C. Throughout the year decreasing body weight with depth was observed, indicating that adult and juvenile mud skates inhabit different depths. Total length of mud skates in catches ranged from 17 to 70 cm with a mean of 51.71 cm. Relation between total length (TL, cm) and body weight (W, g) was: W = 0.0029TL3.1614 (r2 = 0.978). Males were more abundant among small skates ( 30 cm) comprising about 70% in 60–70 cm length class. Female mud skates were longer and heavier than males (mean length 56.9 vs 51.2 cm and mean weight 1206 vs 807 g, respectively). This species is considered to be benthophagous, consuming mostly amphipods (34.9% by weight), polychaete worms (27.6%), decapod crustaceans (12.7%), and fishery discards (13.9%). Small skates (20–40 cm) fed mostly on amphipods (85.4%); medium-sized (40–60 cm) ate amphipods (40.2%), polychaetes (29.1%) and decapods (19.3%); the largest individuals (>60 cm) consumed fishery offal (27.9%) and less amphipods (26.6%) and polychaetes (27.7%). Preliminary data on the maturation of the species in the western Bering Sea showed that males and females become mature at lengths above 61 cm TL.

Polar Steroidal Compounds from the Far‐Eastern Starfish Lethasterias nanimensis chelifera.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Polar steroidal compounds from the Far-Eastern starfish Lethasterias nanimensis chelifera

In addition to the salts described previously (with a sulfated steroid as the anion and the alkaloid salsolinol as the cation), nine other steroidal compounds including three new compounds were isolated from the Far-Eastern starfish Lethasterias nanimensis chelifera collected near the coast of the Onekotan island (Kuril isles). A nonsteroidal compound found in this starfish is (1S,3S)-1-methyl-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid. The structures of the isolated compounds were determined by NMR spectroscopy and mass spectrometry.

Seismic stratigraphy, BSR distribution, and venting of methane-rich fluids west off Paramushir and Onekotan Islands, northern Kurils

Single-channel seismic recording, water chemistry determination, and sediment sampling were carried out off the northern Kuril Islands and the southern tip of Kamchatka. A bottom simulating reflector (BSR) was mapped in detail. The shipboard analyses of bottom water samples yielded methane concentrations up to 1000 nl/1. West off Paramushir Island, venting of methane-rich fluids from the seafloor into the water column is related to unusual trajectories of the BSR which emerges towards the seafloor. The destabilisation of gas hydrates and the origin of the vent site may correspond to anomalous high heatflow caused by recent volcanic intrusions into the sediment. No venting was found in the areas off the southern tip of Kamchatka and off Onekotan Island.