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  • Title/Summary/Keyword: Dokdo

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Stock Assessment and Optimal Catch of Blackfin Flounder Glyptocephalus stelleri in the East Sea, Korea (한국 동해안 기름가자미(Glyptocephalus stelleri)의 자원평가 및 적정어획량 추정)

  • Sohn, Myoung Ho;Yang, Jae Hyeong;Park, Jeong-Ho;Lee, Haewon;Choi, Young Min;Lee, Jae Bong
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.46 no.5
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    • pp.598-606
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    • 2013
  • The blackfin flounder Glyptocephalus stelleri is a commercially important species in the East Sea of Korea, but its catches and biomass have decreased gradually in recent years. This study estimated the optimal catch (acceptable biological catch, ABC) for the effective management of this species by estimating population ecology parameters and the stock biomass of blackfin flounder in the East Sea of Korea. The estimated instantaneous coefficient of total mortality (Z) of blackfin flounder was 1.0542/year, the survival rate (S) was 0.3485, and the instantaneous coefficient of natural mortality (M) was 0.3637/year. From the values of S and M, the instantaneous coefficient of fishing mortality (F) was calculated to be 0.6905/year. The age at first capture was 1.304 years, and the total length was 11.5 cm at that time. On the basis of these parameters, the annual biomass was estimated by a biomass-based cohort analysis using annual catch data in weight by year for 1991-2012 in the East Sea of Korea. The annual biomass peaked in 1997 at about 12,800 mt and then subsequently declined continuously to a level of 10,500 mt in 2004 and to 9,800 mt in 2011 and 2012. The maximum sustainable yield and F0.1 were estimated as 3,547 mt and 0.3595/year, respectively. Using these estimations, the ABC was estimated to be 3,571 mt in tier 5, 3,397 mt in tier 4, and 2,622 mt in tier 3.

Discharge characteristics of the Seodo Mulgol Spring, Dokdo (독도 서도 물골 지하수의 유출특성)

  • Cho, Byong-Wook;Yun, Uk;Lee, Byeong-Dae;Song, Won-Kyong;Hwan, Jae-Hong;Choo, Chang-Oh
    • The Journal of Engineering Geology
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    • v.21 no.2
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    • pp.125-131
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    • 2011
  • The discharge characteristics of the Seodo Mulgol Spring-the only groundwater-producing area in Dokdo-were evaluated by measurements of discharge rate and electrical conductivity (EC) on five occasions. The Seodo Mulgol Spring is fed by rainfall in upstream areas of the Mulgol cave, and the rainwater of the area moves down along cooling joints developed in trachyandesite II and trachyte, finally discharging at the Mulgol cave. The discharge rate of the Seodo Mulgol Spring varied from 1.12 to 7.02 m3/d during the study period and EC varied from 2,650 to 3,390 μS/cm, showing a sharp increase during heavy rainfall. The observed variations in discharge rate and EC at the Seodo Mulgol Spring are attributed to the relatively short distance between the recharge area and the Mulgol cave, and to the rapid movement of groundwater through columnar joints developed in trachyandesite II and trachyte. Additional discharge measurements, combined with precise rainfall data, are required at Dokdo to elucidate the discharge characteristics of the Seodo Mulgol Spring.

Diversity and Plant Growth-Promotion of Endophytic Fungi Isolated from the Roots of Plants in Dokdo Islands (독도의 자생식물 뿌리에서 분리한 내생진균의 다양성과 생장촉진활성)

  • You, Young-Hyun;Yoon, Hyeok-Jun;Lee, Gil-Seong;Woo, Ju-Ri;Rim, Soon-Ok;Shin, Jae-Ho;Lee, In-Jung;Choo, Yeon-Sik;Kim, Jong-Guk
    • Journal of Life Science
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    • v.21 no.7
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    • pp.992-996
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    • 2011
  • Endophytic fungi were isolated from the roots of plants growing naturally on the island of Dokdo. Plant samples, such as Miscanthus sinensis, Achyranthus japonica and Echinochloa crusgali were isolated from Dongdo, and those such as Honkenya peploides and Artemsia koidzumii were isolated from Seodo. Twenty one strains of endophytic fungi were isolated from these plants. To identify the strains, PCR (polymerase chain reaction) amplification of the partial ITS (Internal Transcribed Spacer) regions was done with universal primers ITS-1 and ITS-4 to determine the nucleotide sequence of the ITS regions. Of the strains isolated from Miscanthus sinensis, 75% were Penicillium sp. and 25% were Aspergillus sp. Fifty five percent of strains isolated from Achyranthus japonica were Penicillium sp., 30% were Aspergillus sp. and 15% were Zygorhynchus sp. Strains isolated from Echinochloa crusgali were Penicillium sp. (50%), Aspergillus sp. (12%), Giberella sp. (13%), Talaromyces sp. (9%) and Umbelopsis sp. (8%). Of the strains isolated from Honkenya peploides, 76% were Penicillium sp. and 24% were Pestalotiopsis sp. Strains isolated from Artemisia koidzumii were Penicillium sp. (81%) and Mucor sp. (19%). As a result of bioassay, Ec-3-1 strain isolated from Echinochloa crusgalli showed plant growth-promotion activity. Of all the endophytic fungi isolated, Penicillium sp. was the most abundantly distributed fungal strain in all plants used in this study.

Plant Growth-Promoting Activity of Endophytic Fungi Isolated from the Roots of Native Plants in Dokdo Islands (독도 자생식물의 뿌리로부터 분리된 내생균의 식물생장촉진 활성)

  • You, Young-Hyun;Yoon, Hyeok-Jun;Woo, Ju-Ri;Seo, Yeong-Gyo;Kim, Mi-Ae;Choo, Yeon-Sik;Kim, Jong-Guk
    • Journal of Life Science
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    • v.21 no.11
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    • pp.1619-1624
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    • 2011
  • Endophytic fungal strains were isolated from the roots of six species plants in the Dokdo islands. Native plant samples, such as Artemisia japonica, Chenopodium album and Solanum nigrum were isolated from Dongdo, and those such as Cyrtomium falcatum, Dianthus longicalyx and Tetragonia tetragonoides were isolated from Seodo. In total, thirty two fungal strains were isolated from these native plants. To identify the fungal strains, polymerase chain reaction (PCR) amplification of internal transcribed spacer (ITS: containing ITS1, 5.8s and ITS2 region) regions was done with universal primers ITS1 and ITS4. Endophytic fungi of four species were isolated from A. japonica, eight species from C. album, three species from S. nigrum, three species from C. falcatum, three species from D. longicalyx and eleven species from T. tetragonoides. Culture filtrates (CF) of isolated endophytic fungi were used to treatwaito-c rice seedlings to test plant growth-promoting activity. As a result of bioassay, Ca-5-2-2 strain isolated from C. album expressed highest plant growth-promotion activity. Of all the endophytic fungi isolated, Penicillium sp., Fusarium sp. and Aspergillus sp. were the most abundantly distributed fungal strains in the six plants used in this study.

A Study on Characteristics of Magnetism from Hydrothermal Vent Area on Esmeralda Bank in Mariana Arc (Mariana 해령 Esmeralda Bank 해저열수분출 지역에서의 지자기 특성 연구)

  • Kim, Ho;Kim, Chang-Hwan;Jeong, Eui-Young;Park, Chan-Hong;Kim, Jong-Uk;Park, Chung-Hwa
    • 한국지구물리탐사학회:학술대회논문집
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    • 2008.10a
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    • pp.27-32
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    • 2008
  • Detailed bathymetry and magnetic survey data for Esmeralda Bank obtained by R/V Onnuri of Korea Ocean Research & Development Institute in September 2007 were analyzed to estimate the locations of possible hydrothermal vents. The shape of Esmeralda Bank is caldera type opened in the western part. The summit is very shallow, about 50 meter b.s.l. and the bottom is about 1300 meter b.s.l. The western part of Esmeralda Bank is more steeper and topographic irregular than eastern part, and showed the valley made by erosion or collapse. The magnetic anomaly patterns of Esmeralda Bank located low anomalies over the north and high anomalies over the south. The magnetic anomalies are steep over the summits and gently smooth over the deep bottom. Two low magnetization zones are located in the summit and westside of Esmeralda Bank. The low magnetization zones of the summits of Esmeralda Bank suggest the possible existence of hydrothermal vent.

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Characterizing Magnetic Properties of TA (Tofua Arc) 22 Seamount (23° 34′ S) in the Lau Basin, Southwestern Pacific (남서태평양 라우분지 TA 22 해저산(23° 34′ S)에서의 지자기 특성 연구)

  • Choi, Soon Young;Kim, Chang Hwan;Park, Chan Hong;Kim, Hyung Rae
    • Geophysics and Geophysical Exploration
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    • v.21 no.2
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    • pp.67-81
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    • 2018
  • We acquired the magnetic and bathymetry data around the TA (Tofua Arc) 22 seamount in the Lau Basin for finding submarine hydrothermal deposits. From the data, we estimated the magnetic characteristics in the study area. The bathymetry shows that TA 22 seamount consists of the western and eastern summits. Each summit exhibits a caldera. The western caldera is smaller, but deeper than the eastern caldera. The slope gradients of the TA 22 are steeper around ~1000 m depth range and relatively gentle at the summit areas with the small difference of two calderas. The magnetic properties of TA 22 seamount present high anomalies at the summit and the vicinity of the caldera. Low magnetization zones appear over the outer flanks and center of the calderas. These magnetic patterns are similar to the previous studies which had represented high anomalies and low magnetization zones inside of the summit area or on the flank of the outside of the summit area. The results of the 2D magnetic forward modeling with seismic profiles show about 20 nT of RMSEs (root mean square error) between the modeled and observed values. The low RMSEs proposes a good correlation between the modeled 2D structure and the geophysical observation in this study area. Based on the modeling and magnetization distribution, hydrothermal deposits are predicted to be located at the inner area of the calderas or at small mounds around caldera rims.

Marine Algal Flora and Ecological Role of Eisenia bicyclis in Dokdo, East Sea, Korea (한국 동해안 독도의 해조상 및 대황(Eisenia bicyclis) 부착기의 생물상)

  • Park, Seo Kyoung;Lee, Jung Rok;Heo, Jin Suk;An, Dae Sung;Lee, Haeng Pil;Choi, Han Gil
    • Korean Journal of Environment and Ecology
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    • v.28 no.6
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    • pp.613-626
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    • 2014
  • Seaweeds were identified after qualitative sampling at 14 stations of Dokdo coasts from May to July 2013 and seaweeds and animals inhabiting 23 Eisenia bicyclis plants were examined to evaluate its ecological role. Biomass was calculated by using regression between stipe length and weight of E. bicyclis. A total of 128 species were identified, including 18 green, 35 brown, and 75 red algae. Coarsely branched form was dominant functional group occupying 47.66% and 91 species (71.09%) were in ESG I group, growing in stable environmental coast. Also, R/P, C/P, and (R+C)/P were 2.14, 0.51, and 2.66, respectively showing temperate and mixed flora. Biomass and density of E.bicyclis were 23.74kgm2 and 64 fronds m2. Twelve seaweeds and 83 animal species (15 Annelida, 25 Mollusca, 34 Arthropoda, 3 Echinodermata, and 6 others) were observed from 23 holdfasts and Ericthonius pugnax was dominant taxon having 538 (43.11%) of 1,248 animal individuals. These results indicate that E.bicyclis is a keystone species showing very important ecological role. In conclusion, the number of seaweeds increased because of intensive research and dominance of coarsely branched form and ESG I group seaweeds, representing that environmental condition of Dokdo is still intact.

An Analysis on Limited Warfare through the Falkland Islands Dispute (포클랜드제도 분쟁을 통한 제한전 분석)

  • Yang, Seong-sil;Lee, Hee-wan;Shin, Jin
    • Maritime Security
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    • v.3 no.1
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    • pp.211-235
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    • 2021
  • As a result of the Falkland Islands War from April 2 to June 14, 1982, Britain overcame severe economic depression and reclaimed the glory of the former British Empire by winning the war. On the other hand, Argentina was greatly affected by the collapse of a military dictatorship and the birth of a democratic government. This study suggests strategies for responding to maritime disputes that may occur in Dokdo Island in the future by applying "DIME on PMESII" to the Falkland Islands dispute. In particular, the study analyzes how DIME (diplomacy, information, military, and economy) capabilities have an effect as a means of the total national power of a country that effectively controls the disputed territory. Based on the results of this study, the response strategies related to the Dokdo maritime dispute are as follows. First, effective control over the disputed territory should be effectively maintained and strengthened like in Britain. This strategy inspires patriotism, supports the government during warfare, secures a just cause for war, and gains international support. Second, 'DIME on PMESII' was effective in modern warfare by focusing our DIME capabilities on the weaknesses of the other country's PMESII system. That is, wars are not won simply by the conflict of armed forces but by a nation's overall national strength, such as diplomatic, information, and economic capabilities. Third, appropriate strategies for neighboring countries are needed to overcome the possibility of limited warfare in the sea through preparations for Dokdo maritime disputes in the future.

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Microbacterium elymi sp. nov., Isolated from the Rhizospheric Soil of Elymus tsukushiensis, a Plant Native to the Dokdo Islands, Republic of Korea

  • Ye-Ji Hwang;Soo-Yeong Lee;Jin-Soo Son;Jin-suk Youn;Woong Lee;Jae-Ho Shin;Mi-Hwa Lee;Sa-Youl Ghim
    • Journal of Microbiology and Biotechnology
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    • v.33 no.2
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    • pp.188-194
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    • 2023
  • Microbacterium elymi KUDC0405T was isolated from the rhizosphere of Elymus tsukushiensis from the Dokdo Islands. The KUDC0405T strain was Gram-stain-positive, non-spore forming, non-motile, and facultatively anaerobic bacteria. Strain KUDC0405T was a rod-shaped bacterium with size dimensions of 0.3-0.4 × 0.7-0.8 ㎛. Based on 16S rRNA gene sequences, KUDC0405T was most closely related to Microbacterium bovistercoris NEAU-LLET (97.8%) and Microbacterium pseudoresistens CC-5209T (97.6%). The dDDH (digital DNA-DNA hybridization) values between KUDC0405T and M. bovistercoris NEAU-LLET and M. pseudoresistens CC-5209T were below 17.3% and 17.5%, respectively. The ANI (average nucleotide identity) values among strains KUDC0405T, M. bovistercoris NEAU-LLET, and M. pseudoresistens CC-5209T were 86.6% and 80.7%, respectively. The AAI (average amino acid identity) values were 64.66% and 64.97%, respectively, between KUDC0405T and its closest related type strains. The genome contained 3,596 CDCs, three rRNAs, 46 tRNAs, and three non-coding RNAs (ncRNAs). The genomic DNA GC content was 70.4%. The polar lipids included diphosphatydilglycerol, glycolipid, phosphatydilglycerol, and unknown phospholipid, and the major fatty acids were anteiso-C17:0 and iso-C16:0. Strain KUDC0405T contained MK-12 as the major menaquinone. Based on genotypic, phylogenetic, and phenotypic properties, strain KUDC0405T should be considered a novel species within the genus Microbacterium, for which we propose the name M. elymi sp. nov., and the type strain as KUDC0405T (=KCTC 49411T, =CGMCC1.18472T).

Long-Term Monitoring and Analysis of Changes in the Soil Layer on Dokdo (장기 모니터링을 통한 독도 자연사면의 토층 변화 분석)

  • Kyeong-Su Kim;Young-Suk Song;Dae-Seong Yun;Eunseok Bang
    • The Journal of Engineering Geology
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    • v.34 no.2
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    • pp.163-171
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    • 2024
  • Changes in the soil layer on Dokdo are important both academically and with regard to sustainable conservation and utilization of the islands. Continuous investigation and observation are necessary, as the soil layer is essential to the growth of plants and, therefore, the islands' ecosystem. Such work was carried out for about 8 years using soil erosion measuring bars, which are durable and facilitate simple monitoring of changes in the soil layer. Each bar comprised a rod measuring 30~50 cm long and 1.5 cm in diameter, and the use of stainless steel afforded resistance to corrosion caused by sea breezes. Six measuring bars were installed in the soil layers of each of two islands, Dongdo and Seodo, and measurements were taken one to three times a year from 2014 to 2021. The field measurements indicate that soil was deposited on Dongdo but eroded on Seodo during the observation period. As the measuring bars on Dongdo were located in the central and lower parts of the island, the observed changes in the soil layer resulted mainly from sedimentation of material eroded by weathering or soil runoff from the upper part of the island. In contrast, the measurement locations on Seodo were located in the upper and central parts of the island, where soil erosion and runoff diminished the soil layer at the observation points.