scholarly journals Deep current structure in the Toyama Deep-Sea Channel in the Japan Sea

2021 ◽  
Author(s):  
Tomoharu Senjyu
Keyword(s):  
Deep Sea ◽  
Water Mass ◽  
Current System ◽  
Japan Sea ◽  
East Side ◽  
The West ◽  
West Side ◽  
Side Slope ◽  
Toyama Bay ◽  
The Japan Sea

AbstractThe flow field in the Toyama Deep-Sea Channel (TDSC) in the Japan Sea was investigated based on mooring observations. An asymmetric current system accompanying offshore and onshore currents over the east- and west-side slopes in the channel, respectively, is suggested. A bottom intensified flow characteristic was observed at the offshore stations in the Yamato Basin. The asymmetric current system in the channel is also suggested by the asymmetric distribution of water characteristics across the TDSC in Toyama Bay; a cold dense water mass with higher dissolved oxygen (DO) and higher transmittance (Tr) was found over the west-side slope of the channel, whereas a water mass with lower DO and lower Tr was distributed over the east-side slope, suggesting a turbidity current from the head of Toyama Bay. The currents facing the shallower depth on their right-hand-side, along with the density distribution in the TDSC, suggest a density current system under the influence of the earth’s rotation. The dissolved oxygen concentration in the TDSC was significantly lower than that in the offshore region of the same temperature range. This suggests that the water mass over the west-side slope in the TDSC is a modified offshore water mass which experienced significant mixing with the low DO water mass over the east-side slope in the TDSC, probably due to strong shear between the offshore and onshore currents in the narrow channel.

scholarly journals Spatial variations in zooplankton community structure along the Japanese coastline in the Japan Sea: influence of the coastal current

Ocean Science ◽  
2018 ◽  
Vol 14 (3) ◽  
pp. 355-369 ◽  
Author(s):  
Taketoshi Kodama ◽  
Taku Wagawa ◽  
Naoki Iguchi ◽  
Yoshitake Takada ◽  
Takashi Takahashi ◽  
...  
Keyword(s):  
Community Structure ◽  
Zooplankton Community ◽  
Japan Sea ◽  
Spatial Variations ◽  
The West ◽  
Zooplankton Community Structure ◽  
Japanese Coast ◽  
Toyama Bay ◽  
The Japan Sea ◽  
Water Species

Abstract. This study evaluates spatial variations in zooplankton community structure and potential controlling factors along the Japanese coast under the influence of the coastal branch of the Tsushima Warm Current (CBTWC). Variations in the density of morphologically identified zooplankton in the surface layer in May were investigated for a 15-year period. The density of zooplankton (individuals per cubic meter) varied between sampling stations, but there was no consistent west–east trend. Instead, there were different zooplankton community structures in the west and east, with that in Toyama Bay particularly distinct: Corycaeus affinis and Calanus sinicus were dominant in the west and Oithona atlantica was dominant in Toyama Bay. Distance-based redundancy analysis (db-RDA) was used to characterize the variation in zooplankton community structure, and four axes (RD1–4) provided significant explanation. RD2–4 only explained < 4.8 % of variation in the zooplankton community and did not show significant spatial difference; however, RD1, which explained 89.9 % of variation, did vary spatially. Positive and negative species scores on RD1 represent warm- and cold-water species, respectively, and their variation was mainly explained by water column mean temperature, and it is considered to vary spatially with the CBTWC. The CBTWC intrusion to the cold Toyama Bay is weak and occasional due to the submarine canyon structure of the bay. Therefore, the varying bathymetric characteristics along the Japanese coast of the Japan Sea generate the spatial variation in zooplankton community structure, and dominance of warm-water species can be considered an indicator of the CBTWC.

scholarly journals Spatial variations in zooplankton community structure along the Japanese coastline in the Japan Sea: influence of the coastal current

2017 ◽  
Author(s):  
Taketoshi Kodama ◽  
Taku Wagawa ◽  
Naoki Iguchi ◽  
Yoshitake Takada ◽  
Takashi Takahashi ◽  
...  
Keyword(s):  
Community Structure ◽  
Zooplankton Community ◽  
Japan Sea ◽  
Spatial Variations ◽  
Coastal Current ◽  
The West ◽  
Zooplankton Community Structure ◽  
Japanese Coast ◽  
Toyama Bay ◽  
The Japan Sea

Abstract. This study evaluates spatial variations in zooplankton community structure and potential controlling factors along the Japanese coast under the influence of the coastal branch of the Tsushima Warm Current (CBTWC). Variations in the density of morphologically-identified zooplankton in the surface layer in May were investigated for a 15-year period. The density of zooplankton (individuals per cubic meter) varied between sampling stations, but there was no consistent west–east trend. Instead, there were different zooplankton community structures in the west and east, with that in Toyama Bay particularly distinct: Corycaeus affinis and Calanus sinicus were dominant in the west and Oithona atlantica was dominant in Toyama Bay. Distance-based redundancy analysis (db-RDA) was used to characterize the variation in zooplankton community structure, and four axes (RD1–4) provided significant explanation. RD2–4 only explained

Biodiversity in midwater cnidarians and ctenophores: submersible-based results from deep-water bays in the Japan Sea and north-western Pacific

2005 ◽  
Vol 85 (3) ◽  
pp. 503-517 ◽  
Author(s):  
Dhugal J. Lindsay ◽  
James C. Hunt
Keyword(s):  
Deep Sea ◽  
Japan Sea ◽  
Western Pacific ◽  
Sagami Bay ◽  
Survey Period ◽  
Depth Layer ◽  
Toyama Bay ◽  
The Japan Sea ◽  
North Western ◽  
North Western Pacific

Biodiversity of cnidarian and ctenophore forms in Toyama Bay, Japan Sea, was lower than that in Sagami Bay, north-western Pacific, according to all the indices investigated. Highest richness of forms occurred in the 400—600 m depth layer in Sagami Bay, while in Toyama Bay richness was low in most layers. New forms continued to occur with increasing depth in Sagami Bay but not in Toyama Bay and species composition differed remarkably between the two bays. Putative secondary deep-sea gelatinous forms were identified. Horizontal patchiness in normalized abundances was the rule rather than the exception and for accurate calculations of biodiversity indices incorporating evenness or equitability, the necessity for multiple submersible dives in a single area and survey period was noted. Vertical migration and predation were identified as possible factors contributing to the higher diversity in the 400—600 m depth layer in Sagami Bay.

scholarly journals Fabric and Origin of Lateral Moraines, Bethartoli Glacier, Garhwal Himalaya, India

1978 ◽  
Vol 20 (84) ◽  
pp. 547-553 ◽  
Author(s):  
Gerald D. Osborn
Keyword(s):  
Garhwal Himalaya ◽  
Lateral Moraine ◽  
East Side ◽  
The West ◽  
West Side ◽  
Lateral Ridge ◽  
Moraine Ridge

AbstractUnusually strong till fabrics in lateral moraines of Bethartoli Glacier provide information on the genesis and growth of the moraines. On the west side of the valley, down-stream of the present glacier snout, several lateral moraine crests are juxtaposed. Because the crests generally become higher towards the valley axis, they must represent re-advances of the glacier rather than recessional stages. On the east side of the valley only a single lateral ridge is found; presumably the ridge is composed of debris from several glacial advances. On the eroded proximal flank of this ridge a strong fabric is visible; the plane defined by a- and b-axes of stones is parallel to the distal flank of the moraine ridge, indicating that the moraine grew mainly by accretion of debris on to its distal flank. On the eroded proximal flank of the innermost west-side ridge the equivalent fabric is weaker, suggesting that distal flank accretion was less significant and proximal flank accretion more significant than on the east side.

scholarly journals Paleoseismology of deep-sea faults based on marine surveys of northern Okushiri ridge in the Japan Sea

2005 ◽  
Vol 110 (B9) ◽  
Author(s):  
Yukinobu Okamura ◽  
Kenji Satake ◽  
Ken Ikehara ◽  
Akira Takeuchi ◽  
Kohsaku Arai
Keyword(s):  
Deep Sea ◽  
Japan Sea ◽  
The Japan Sea

scholarly journals Phylogeography of a deep-sea demersal fish, Bothrocara hollandi, in the Japan Sea

2001 ◽  
Vol 217 ◽  
pp. 135-143 ◽  
Author(s):  
S Kojima ◽  
R Segawa ◽  
I Hayashi ◽  
M Okiyama
Keyword(s):  
Deep Sea ◽  
Japan Sea ◽  
Demersal Fish ◽  
The Japan Sea
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