• Title/Summary/Keyword: southwestern Pacific Ocean

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DNA Barcoding of Isaacsicalanus paucisetus (Copepoda: Calanoida: Spinocalanidae) from the Hydrothermal Vent in the North Fiji Basin, Southwestern Pacific Ocean

  • Park, Chailinn;Lee, Won-Kyung;Kim, Se-Joo;Ju, Se-Jong
    • Animal Systematics, Evolution and Diversity
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    • v.36 no.2
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    • pp.182-184
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    • 2020
  • Isaacsicalanus paucisetus Fleminger, 1983, a monotypic species of the family Spinocalanidae Vervoort, 1951, was first reported from a hydrothermal vent field in the East Pacific Rise off the mouth of the Gulf of California. The mitochondrial cytochrome oxidase I(mtCOI) DNA barcodes are considered a useful tool to assist traditional taxonomy and species discrimination in calanoid copepods. However, the mtCOI DNA barcodes of I. paucisetus have not been reported due to the species rarity and the difficulty of sampling. In this study, we firstly determined the mtCOI DNA barcodes of the I. paucisetus newly collected from a hydrothermal vent in the North Fiji Basin of the southwestern Pacific. All mtCOI DNA barcodes of I. paucisetus were identical and intraspecies variations of spinocalanid species were 0.0-3.0%. Interspecies and intergeneric variations were 13.4-25.2% and 16.7-24.1%, respectively. The DNA barcodes of I. paucisetus obtained in the present study would be helpful for understanding taxonomic relationships of widespread spinocalanid species.

DNA Barcoding for the Hydrothermal Vent Crab Austinograea Species (Crustacea: Bythograeidae) from the North Fiji Basin, Southwestern Pacific Ocean

  • Lee, Won-Kyung;Ju, Se-Jong;Hou, Bo Kyeng;Kim, Se-Joo
    • Animal Systematics, Evolution and Diversity
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    • v.35 no.1
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    • pp.30-32
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    • 2019
  • The brachyuran crab Bythograeidae Williams, 1980 is common in hydrothermal vent fields worldwide and has recorded to sixteen species of six genera. In this study, we firstly determined the cytochrome c oxidase subunit 1 (CO1) DNA barcodes for the fifth species of Austinograea, A. hourdezi, from hydrothermal vent regions of the North Fiji Basin in southwestern Pacific Ocean. All CO1 DNA barcodes of A. hourdezi were identical. The interspecies variations of three bythograeid genera were 10.9-13.3% for Austinograea, 6.6-15.7% for Bythograea, and 9.7% for Gandalfus. These results would be helpful to understand taxonomy of brachyuran crabs living in hydrothermal vent fields using CO1 DNA barcodes.

Additional Records of the Hydrothermal Vent Scale Worm Branchinotogluma segonzaci (Polynoidae: Lepidonotopodinae) from the North Fiji Basin and Tonga Arc

  • Lee, Won-Kyung;Lee, Geon Hyeok;Ju, Se-Jong;Kim, Se-Joo
    • Animal Systematics, Evolution and Diversity
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    • v.37 no.4
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    • pp.273-279
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    • 2021
  • Branchinotogluma segonzaci (Miura and Desbruyères, 1995) occurs in hydrothermal vent fields of the southwestern Pacific Ocean. We morphologically compared B. segonzaci from the North Fiji Basin with the original description from the Lau Basin and a subsequent study of specimens from the Manus Basin. The main characteristics of all B. segonzaci populations were similar having 21 segments, 10 pairs of elytra, cylindrical-shaped anterior lobes, and ventral papillae on segment 12 and ventral lamellae on segments 13-17 in males. However, the specimens from the North Fiji Basin had rounded to sub-renifrom elytra rather than oval in the original description. Additionally, we newly obtained 11 cytochrome oxidase subunit I (COI) DNA barcodes from the North Fiji Basin and Tonga Arc populations and compared them with known COI DNA barcodes of Branchinotogluma species. Thirteen sequences of B. segonzaci showed 0.0-1.07% intraspecific variation and formed two clades in the COI neighbor-joining tree, whereas the interspecific variation among Branchinotogluma species was 8.19-22.4%. The results of this study contribute to biogeographic studies of B. segonzaci and the evolution of polynoid scale worms in chemosynthesis-based ecosystems.

Distribution of Dissolved Organic Carbon (DOC) in the Southwestern East Sea in Summer

  • Kim, Tae-Hoon;Kim, Gue-Buem
    • Ocean and Polar Research
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    • v.32 no.3
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    • pp.291-297
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    • 2010
  • In the summer of 2008 (August 4-14), vertical and horizontal distributions of inorganic nutrients and dissolved organic carbon (DOC) were measured in the southwestern East Sea. Concentrations of DOC were determined for the first time in the southwestern East Sea using the high-temperature combustion oxidation (HTCO) method, and results were compared with those measured by another laboratory. Concentrations of DOC ranged from 58 to 104 ${\mu}M$ in the upper 200 m, showing a typical decreasing pattern with depth. Generally, concentrations of DOC were relatively lower, with higher nutrient concentrations, in the upper layer of the coastal upwelling zone. Concentrations of DOC ranged from 54 to 64 ${\mu}M$ in the deep Ulleung Basin (200-1500 m), and were higher than those in the Pacific and Atlantic oceans. In association with rapid vertical ventilation of the euphotic, this difference indicates a larger accumulation of semi-labile DOC in the deep East Sea than in the major oceans. A correlation between apparent oxygen utilization (AOU) and DOC in the deep ocean of the East Sea revealed that only a small portion (<10%) of the sinking DOC, relative to the sinking particulate organic carbon (POC), contributes to microbial degradation. Our results present an important data set of DOC in the East Sea, which plays a critical role in carbon cycle modeling and sequestration.

Variations in species composition of fishes caught by trawl survey in the northwestern East Sea of Russian EEZ and southwestern East Sea of Korean EEZ (러시아측 동해 북서부 해역과 한국측 동해 남서부 해역 트롤 조사에 어획된 어류의 종조성 및 양적변동)

  • SOHN, Myoung Ho;YOON, Sang Chul;LEE, Sung Il;YOON, Byung Sun;CHA, Hyung Kee;KIM, Jong Bin;Kalchugin, Pavel;Solomatov, Sergey
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.51 no.3
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    • pp.355-369
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    • 2015
  • To examine species composition, abundance and biomass of fishes in the northwestern East Sea of Russian EEZ, trawl survey were conducted at 31 sampling stations from 2006 to 2008. Also, trawl survey were conducted at 21 sampling stations in the southwestern East Sea of Korean EEZ from 2006 to 2008. A total of 67 fishes were collected in the northwestern East Sea of Russian EEZ, a total of 39 fishes were collected in the southwestern East Sea of Korean EEZ. Among them, a total of 53 fishes were collected in the northwestern East Sea of Russian EEZ only, and a total of 25 fishes were collected in the southwestern East Sea of Korean EEZ only. Mean abundance per area which caught by trawl survey in the northwestern East Sea ranged from a high of $116,478inds./km^2$ in 2008 to a low of $19,737inds./km^2$ in 2006. And mean abundance per area in the southwestern East Sea ranged from a high of $89,129inds./km^2$ in 2006 to a low of $8,234inds./km^2$ in 2008. Mean biomass per area which caught by trawl survey in the northwestern East Sea ranged from a high of $11,333kg/km^2$ in 2008 to a low of $2,439kg/km^2$ in 2006. And mean biomass per area in the southwestern East Sea ranged from a high of $6,273kg/km^2$ in 2006 to a low of $1,062 kg/km^2$ in 2008. Cluster analysis, based on a Bray-Curtis similarity matrix of fourth root transformed data of number of species and individuals per area, showed division into three different groups by depth in the northwestern and southwestern East Sea.

Paleomagnetism of Deep-sea Core Sediment in Southwestern Pacific (남서태평양 심해분지 주상퇴적물의 지자기 층서 연구)

  • Moon, Jai-Woon;Kim, Ki-Hyune;Chi, Sang-Bum;Lee, Gun-Chang;Doh, Seong-Jae;Park, Cheong-Kee
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.6 no.3
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    • pp.135-141
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    • 2001
  • A paleomagnetic investigation was carried out to analyze magnetostratigraphic information and to evaluate the relationship between paleoenvironment and magnetic properties in sedimentary sequences of piston cores recovered from the abyssal basin of the southwestern Pacific. Pateomagnetic results revealed that the sediments had a stable remanent magnetization and recorded both normal and reversal polarities. The age of sediments was from late Pliocene and Pleistocene determined by matching the polarities with the geomagnetic time scale. The sedimentation rates were in the range of 0.63-1.85 mm/$10^3$ year which were extremely low rates. The results of the paleomagnetic analyses indicated that intervals of the magnetically stable layers as well as high value of susceptibility were significantly affected by the input changes which resulted input of large-quantity materials of relatively stable magnetic carriers.

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Change of Coastal Upwelling Index along the Southeastern Coast of Korea (동해 남부 연안용승지수의 변화)

  • SHIN, CHANG-WOONG
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.24 no.1
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    • pp.79-91
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    • 2019
  • Long-term trends and recent variations of upwelling index (UI), which affects significantly ecosystem in southwestern part of the East Sea, were investigated. The UI was calculated with the NCEP/NCAR reanalysis data from January 1948 to September 2018. The mean UI has positive value that causes upwelling in April to August with a peak in July. The long-term reducing trend of UI was in statistically significant in June and July, and the sum of UI in May, June and July also showed same result. Through the atmospheric pressure analysis around the Korean peninsula, it was found that the trend of the UI was the influence of the pressure change trend in the northwestern region ($35-50^{\circ}N$, $114-129^{\circ}E$) of the southwestern part of the East Sea. Investigating UI in recent 7 years from 2012 to 2018, it was revealed that the UI was bigger than 3 times of standard deviation in July 2013. This was result from the sea level pressure difference became larger in the southwestern part of the East Sea than normal year due to the lowered air pressure in the northeastern region of China and the strengthened high air pressure of western peripheral of the North Pacific High. On the other hand, the UI in July 2018 was negative when the impact of the North Pacific High and the low air pressure in the northeastern China was weak. Due to the decreasing trend of UI and its large year-to-year variation in southwestern part of the East Sea, continuous monitoring is necessary to know the influence of coastal upwelling on the ecosystem.

The Exploitation of World Fishery Resources for 10 Years under the New Regime in the Sea (신해양질서 10년후 세계어업자원 이용동향)

  • 이장욱;허영희
    • The Journal of Fisheries Business Administration
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    • v.23 no.1
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    • pp.43-87
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    • 1992
  • In this paper, state of exploitation of world fishery resources after 10 years under the new regime in the sea, called the era of exclusive economic zone (EEZ) expending up to a 200 nautical miles from coastal line, was reviewed to determine effect from establishing EEZ in the world fishery production and its export/import volume based on the fishery statistics annually published by the Food and Agriculture Organization (FAO) of United Nation. The world total production from marine living resources had a trend showing a waned increase during 1970's when most of coastal states were translated into the reality of EEZ. From mid-1980's onwards, it increased rapidly, reaching about 85 million tons . Such increase in production was basically from the Pacific Ocean, accounting for more than 60% of the world total production. Fishing areas where showed increase in the production after the new regime in the sea were the southwestern Atlantic (FAO area 41) , the eastern Indian (FAO area 57) and the whole fishing areas in the Pacific except the eastern central Pacific (FAO area 77). Increase in the production from distant-water fishing countries came from the regions of the southwest Atlantic (FAO area 41) and the southwest Pacific (FAO area 81) . The production from coastal states was up from the regions of the eastern Indian (FAO area 57) , the northwest and northeast Pacific (FAO areas 61 and 67) and the southeast Pacific (FAO area 87) . It was likely that the exploitation of the fishable stocks was well monitored in the areas of the northwest Atlantic (FAO area 21) , the eastern central Atlantic (FAO area 34) and the northeast Pacific (FAO area 67) through appropriate management measures such as annual harvest level, establishment of total allowable catch etc. The marine fisheries resources that have made contribution to the world production, despite expansion of 200 EEZ by coastal states, were sardinellas, Atlantic cod, blue whiting and squids in the Atlantic Ocean : tunas which mainly include skipjack, yellowfin and bigeye tuna, croakers and pony fishes in the Indian Ocean : and sardine, Chilean pilchard, Alaska pollock, tunas (skipjack and yellowfin tuna) , blue grenadier and blue whiting including anchoveta in the Pacific Ocean. It was identified that both fishery production and its export since introduction of the new regime in the sea were dominated by such coastal states as USA, Canada, Indonesia, Thailand, Mexico, South Africa and Newzealand. But difficulties have been experienced in the European countries including Norway, Spain, Japan and Rep. of Korea. Therefore, majority of coastal states are unlikely to have yet undertaken proper utilization as well as rational management of marine living resources in their jurisdiction during the last two decades. The main target species groups which led the world fishery production to go up were Alaska pollock, cods, tunas, sardinellas, chub and jack mackerel and anchoveta. These stocks are largely expected to continue to contribute to the production. The fisheries resources which are unexploited, underexploited and/or lightly exploited at present and which will be contributed to the world production in future are identified with cephalopods, Pacific jack mackerel and Atlantic mackerel, silver hake including anchovies. These resources mainly distribute in the Pacific regions, especially FAO statistical fishing areas 67, 77 and 87. It was likely to premature to conclude that the new regime in the sea was only in favour of coastal states in fishey production.

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Additional Description of the Vent Scale Worm Thermopolynoe branchiata (Polychaeta: Polynoidae) from the North Fiji Basin

  • Won-Kyung Lee;Geon Hyeok Lee;Se-Jong Ju;Se-Joo Kim
    • Animal Systematics, Evolution and Diversity
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    • v.39 no.1
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    • pp.47-52
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    • 2023
  • Thermopolynoe Miura, 1994 is a monotypic genus in Lepidonotopodinae that comprises species endemic to chemosynthesis-based ecosystems. Here, we examined T. branchiata collected from the hydrothermal vents in the North Fiji Basin. For the first time in Thermopolynoe, we report sexual dimorphism detecting nephridial papillae on segments 11-13 in males, additionally describe the morphology on elytra with round to conical microtubercles on the surface, and distinguish presence of small neuropodial lobes on segments 3-26. We also revised couple of errors and ambiguities in the original description: incongruence between the description and figure and existence of individual variation in ratio of tentacular cirri and palps. In addition, three COI sequences of T. branchiata specimens from the North Fiji Basin were newly obtained and sequences divergence with other Lepidonotopodinae species were determined. These results would contribute to the taxonomy of polynoids in a chemosynthesis-based ecosystem.

A Study of Three-dimensional Magnetization Vector Inversion (MVI) Modeling Using Bathymetry Data and Magnetic Data of TA (Tofua Arc) 12 Seamount in Tonga Arc, Southwestern Pacific (남서태평양 통가열도 TA (Tofua Arc) 12 해저산의 해저지형과 자력자료를 이용한 3차원 자화벡터역산 모델 연구)

  • Choi, Soon Young;Kim, Chang Hwan;Park, Chan Hong;Kim, Hyung Rae
    • Geophysics and Geophysical Exploration
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    • v.23 no.1
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    • pp.22-37
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    • 2020
  • We analyze the comprehensive three-dimensional (3D) magnetic structure characteristics from the seafloor to the deep layer of the Tofua Arc (TA) 12 seamount in the Tonga Arc, Southwestern Pacific, using bathymetric and geomagnetic data, and magnetization vector inversion (MVI) results. The seafloor features surrounding TA 12 highlight a NW-SE-oriented elliptical caldera at the summit of the seamount, two small cones in the depressed area. A large-scale sea valley is present on the western flank of the seamount, extending from these caldera cones to the southwestern base of the seamount. TA 12 seamount exhibits a low magnetic anomaly in the caldera depression, whereas a high magnetic anomaly is observed surrounding the low magnetic anomaly across the caldera summit. It is therefore presumed that there may be a strong magnetic material distribution or magma intrusion in the caldera. The 3D MVI results show that the high anomaly zones are mainly present in the surrounding slopes of the seamount from the seafloor to the -3,000 m (below the seafloor) level, with the magnetic susceptibility intensity increasing as the seafloor level increases at the caldera depression. However, small high anomaly zones are present across the study area near the seafloor level. Therefore, we expect that the magma ascent in TA 12 seamount migrated from the flanks to the depression area. Furthermore, we assume that the complex magnetic distribution near the seafloor is due to the remnant magnetization.