• Title/Summary/Keyword: Dokdo

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Stock assessment of starry flounder, Platichthys stellatus and olive flounder, Paralichthys olivaceus in the Uljin marine ranching area, Korea (울진 바다목장 강도다리 (Platichthys stellatus)와 넙치 (Paralichthys olivaceus)의 자원평가)

  • Yoon, Sang-Chul;Lee, Sung-Il;Yang, Jae-Hyeong;Yoon, Byoung-Sun;Kim, Jong-Bin;Cha, Hyung-Kee
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.50 no.4
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    • pp.583-594
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    • 2014
  • This study was performed to estimate biomass and provide management guidance through population ecological characteristics, including growth parameters, instantaneous coefficients of natural and fishing mortalities, and age at first capture of the starry flounder, Platichthys stellatus and olive flounder, Paralichthys olivaceus of Korea. For describing growth of this species, a von Bertalanffy growth model was adopted. The von Bertalanffy growth parameters estimated from a non-linear regression for starry flounder were L=48.25cm, K=0.16/yr, and t0=1.48, respectively and those for olive flounder were L=86.46cm, K=0.26/yr, and t0=0.29, respectively. Biomass of Platichthys stellatus was estimated by direct biomass estimation method was 2.6 M/T, that was estimated by indirect method was 13.4 M/Tt. Those of Paralichthys olivaceus were estimated as 10.1 M/T, 19.3 M/T, respectively. An yield per recruit analysis showed that the current yield per recruit on Platichthys stellatus was about 48.2 g with F=0.646/yr and the age at first capture (tc) 1.35yr, that on Paralichthys olivaceus was about 167.6 g with F=1.121/yr and the age at first capture (tc) 1yr.

Species Composition and Abundance of Zooplankton Community in Spring and Autumn around Dokdo (독도 주변에서 춘계와 추계의 동물플랑크톤 종 조성과 개체수)

  • Kang, Jung-Hoon;Kim, Woong-Seo;Shim, Jae-Hyung
    • Ocean and Polar Research
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    • v.24 no.4
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    • pp.407-417
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    • 2002
  • Species composition and abundance of zooplankton were investigated around Dokdo in the East/Japan Sea in autumn 1999 and spring 2000. Vertical and horizontal hauls of a bongo net (300μm mesh size, 60cm diameter) were made to collect zooplankton sample. Surface temperature and salinity ranged from 24.2Cto25.1C, and from 32.9psu to 33.2psu in September 1999, respectively. In May 2000, surface temperatures were 13.9Cand14.2C at stations of A1 and A8, and salinity was 34.5psu at both stations. Zooplankton community was dominated by copepods which comprised 61% (September) and 60% (May) of total numerical abundance, respectively. The next dominant groups were appendicularians (11%) and chaetognaths (9%) in September 1999, and other crustaceans (27%) and appendicularians (4%) in May 2000. The 15.7% (September) and 23.2% (May) of copepods were in the juvenile stage of copepodites. The most dominant copepods were Oncaea media (10.4%) and Clausocalanus sp. (8.2%) which preferred warm water in September. In contrast, cold-water copepods such as Pseudocalanus minutus (9.4%) and Metridia pacifica (8.0%) were dominant in May. The results of cluster analysis based on Bray-Curtis index showed that zooplankton community were classified into two groups which represented different water mass. The average abundance of zooplankton in September was 2.1 times higher than that in May, and species number of them in September outnumbered that in May by 29 species. Zooplankton community varied in associated with a characteristic of warm waters which affected marine ecosystem differently in the study area depending on seasons.

Characterization of Three Antifungal Calcite-Forming Bacteria, Arthrobacter nicotianae KNUC2100, Bacillus thuringiensis KNUC2103, and Stenotrophomonas maltophilia KNUC2106, Derived from the Korean Islands, Dokdo and Their Application on Mortar

  • Park, Jong-Myong;Park, Sung-Jin;Ghim, Sa-Youl
    • Journal of Microbiology and Biotechnology
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    • v.23 no.9
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    • pp.1269-1278
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    • 2013
  • Crack remediation on the surface of cement mortar using microbiological calcium carbonate (CaCO3) precipitation (MICP) has been investigated as a microbial sealing agent on construction materials. However, MICP research has never acknowledged the antifungal properties of calcite-forming bacteria (CFB). Since fungal colonization on concrete surfaces can trigger biodeterioration processes, fungi on concrete buildings have to be prevented. Therefore, to develop a microbial sealing agent that has antifungal properties to remediate cement cracks without deteriorative fungal colonization, we introduced an antifungal CFB isolated from oceanic islands (Dokdo islands, territory of South Korea, located at the edge of the East Sea in Korea.). The isolation of CFB was done using B4 or urea-CaCl2 media. Furthermore, antifungal assays were done using the pairing culture and disk diffusion methods. Five isolated CFB showed CaCO3 precipitation and antifungal activities against deteriorative fungal strains. Subsequently, five candidate bacteria were identified using 16S rDNA sequence analysis. Crack remediation, fungi growth inhibition, and water permeability reduction of antifungal CFB-treated cement surfaces were tested. All antifungal CFB showed crack remediation abilities, but only three strains (KNUC2100, 2103, and 2106) reduced the water permeability. Furthermore, these three strains showed fungi growth inhibition. This paper is the first application research of CFB that have antifungal activity, for an eco-friendly improvement of construction materials.

Reproduction and distribution of Chionoecetes crabs (C. opilio and C. japonicus) in the East Sea (동해에 서식하는 대게류(Chionoecetes spp.)의 재생산 및 분포 특성)

  • Cha, Hyung Kee;Yang, Jae Hyeong;Lee, Sung Il;Yoon, Sang Chul
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.47 no.5
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    • pp.637-644
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    • 2014
  • Two Chionoecetes crabs, C. opilio and C. japonicus are primary targets of trap fisheries in the East Sea. To promote the sustainable management of these species, we investigated their reproductive biology and spatial distribution based on samples collected in standardized traps in the coastal waters of eastern Korea from September 2007 to August 2008. The estimated spawning season of C. opilio was March-April, whereas that of C. japonicus continued year-round. The estimated molting period of both species was September-October. Fecundity of C. opilio was proportional to female, size, ranging from 44,791 to 151,538 eggs, and the estimated body size at 50% sexual maturity was 63.9 mm carapace width. Egg bearing female C. opilio were mostly collected depths of 200-300 m, particularly off Hupo and Chuksan, suggesting that these areas are their major spawning grounds. In contrast, female C. japonicus were mostly collected at depths of 400-600 m, peaking at 600 m. The species-specific catch rate was higher for C. opilio above 400 m, similar at ca. 450 m, and higher for C. japonicus below 500 m. These vertical differences indicate apparent spatial segregation of the species, suggesting that spatially-explicit fisheries management plans may be necessary for mitigating conflicts between the respective crab fisheries and maintaining these crabs.

Feeding Habits of the Black-edged Sculpin Gymnocanthus herzensteini in the Coastal Waters off Mukho, Gangwondo of Korea (강원도 묵호 연안에서 출현하는 대구횟대(Gymnocanthus herzensteini)의 식성)

  • Yang, Jae Hyeong;Yoon, Sang Chul;Park, Jeong-Ho;Yoon, Byoung Sun;Choi, Young Min;Lee, Jae Bong
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.46 no.2
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    • pp.168-175
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    • 2013
  • The feeding habits of the black-edged sculpin Gymnocanthus herzensteini were studied using 944 specimens collected from February 2011 to January 2012 in the coastal waters off Mukho, Gangwondo, Korea. The G. herzensteini ranged from 11.8 to 36.3 cm in total length (TL). The percentage of empty stomachs in G. herzensteini was 40.2%, and the main prey items were Pisces, Euphausiasea, and Macrura. The smallest size group (11.8-15.0 cm TL) consumed mainly Polychaeta and Amphipoda. The quantity of prey increased in proportion to sculpin size. The composition of prey items and feeding habits of G. herzensteini exhibited seasonal fluctuations, that is, the main prey items during spring were Euphausiasea, whereas those during other seasons were Pisces.

Four newly reported ophichthid leptocephali species revealed by mitochondrial 12S rDNA, with implications of their occurrence in Korea

  • Ji, Hwan Sung;Lee, Hae Won;Hong, Byung Kyu;Kim, Jin Koo
    • Animal cells and systems
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    • v.16 no.5
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    • pp.415-424
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    • 2012
  • Four species of ophichthid leptocephali were identified using 12S rDNA sequences, and their morphological descriptions were first provided based on six individuals (S1-S3,M1, and E1-E2) collected from the East Sea and the Korea Strait between September 2008 and October 2010. Mitochondrial 12S rDNA 859-861 base pairs of ophichthid leptocephali were compared with those of 16 ophichthids adult and 2 outgroups (Anguilla japonica and Conger myriaster). Leptocephali of S1 and E1 were very closely clustered with adult of Scolecenchelys borealis (D=0.002) and Echelus uropterus (D=0.000), respectively. However, leptocephali of S2-S3 andM1 were slightly far clustered with leptocephalus of S1 (D=0.006) and adult of Muraenichthys gymnopterus (0.034), respectively. We believe that S1 and E1 are S. borealis and E. uropterus, respectively, in which the former is unrecorded species in Korea. However, S2-S3 and M1 may be undescribed species belonging to genus Scolecenchelys and Muraenichthys, respectively, because total numbers of myomeres for S2-S3 (148-158) and M1 (151) were not consistent with total numbers of vertebrae or distribution for any adult of Scolecenchelys spp. and Muraenichthys spp. in the world. We propose the new Korean name 'Dong-hae-mul-baem' for S. borealis.

Feeding habits of the Pacific bluefin tuna, Thunnus orientalis in the southern sea of Korea (한국 남해안에 출현하는 태평양참다랑어 Pacific bluefin tuna, Thunnus orientalis의 식성)

  • YOON, Sang Chul;YOO, Joon Taek;LEE, Sung Il;KIM, Zang Geun;CHOI, Kwang Ho
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.51 no.4
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    • pp.553-560
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    • 2015
  • The feeding habits of the Pacific bluefin tuna, Thunnus orientalis were examined based on the stomach contents of 330 specimens caught by offshore large purse seine fishery in the southern sea of Korea, 2011. The size of Pacific bluefin tuna used in this study ranged from 34.1 to 67.3 cm in fork length (FL). The percentage of empty stomachs was 41.8%. The main prey items were Pisces and Cephalopoda based on percentage IRI (index of relative importance). The main fish preys were Trachurus japonicus, Bregmaceros japonicus, Engraulis japonicus, and Cephalopoda were Todarodes pacificus, Loligo edulis, Watasenia scintillans. T. orientalis showed ontogenetic change in diet composition. Although Pisces dominated the diet of all length classes the portion of Cephalopoda was relatively higher in size between 40 and 50 cm other than length classes. In terms of seasonal variation in feeding habits, Pisces was the main prey group in all seasons, but Cephalopoda was also frequently consumed during spring and autumn based on %IRI.

Study on the Annual Reproductive Cycle of the Comb Pen Shell, Atrina pectinata (Linnaeus, 1767) (Mollusca: Bivalvia: Pinnidae) on the Southern Coast of Ulleungdo Island, Korea (울릉도 남해역에 서식하는 키조개의 연중 번식주기에 관한 연구)

  • Yang, Hyun-Sung;Noh, Choong Hwan;Yoon, Sung Jin;Kim, Yun-Bae;Choi, Kwang-Sik;Kang, Do-Hyung
    • Ocean and Polar Research
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    • v.38 no.1
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    • pp.21-33
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    • 2016
  • Gametogenesis of the comb pen shell, Atrina pectinata (Linnaeus, 1767) (Bivalvia: Pinnidae) on the southern coast of Ulleungdo Island, Korea was assessed monthly (November 2013 to October 2014) using histology. Gametogenesis commenced in January when the surface water temperature was 12.6C and pen shells evidenced an early development phase with small oogonia from January to April, although few females exhibited ripe eggs in their follicular epithelium. In April, the oocyte diameter increased rapidly, and fully mature eggs appeared in May. First spawning males and females were observed in June as the surface water temperature reached 19.3C and July (23.2C) respectively. The spawning activity continued until the end of September. Histology indicated that the spawning peak of the females in Ulleungdo Island was July to August. During October to January, most of the pen shells were in spent and resting stages. Our data suggested that A. pectinata is a summer spawner, and their annual gametogenesis is closely associated with the seasonal variation in the surface water temperature. The present study is the first provided fundamental information on the life history of A. pectinata in Ulleungdo Island, and this can be put to good use in the management of this pen shell in the study area.

Intraspecific sequence variation of trnL/F intergenic region (cpDNA) in Sedum takesimense Nakai (Crassulaceae) and aspects of geographic distribution (섬기린초에서 엽록체 DNA 염기서열의 종내 변이와 지리적 분포 양상 연구)

  • Lee, Woong;Pak, Jae-Hong
    • Korean Journal of Plant Taxonomy
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    • v.40 no.3
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    • pp.157-162
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    • 2010
  • Sequences of the trnL/F intergenic spacer of chloroplast DNA were used to investigate the intraspecific evoution and phylogeography of Sedum takesimense (Crassulaceae). The trnL/F intergeneric spacer sequences from 32 individuals of S. takesimense were either 291 bp (17 samples "without indel" in the following) or 297 bp (15samples "with indel 1") in length due to an indel of 6 bp. Two main cpDNA haplotypes were detected within S. takesimense. The haplotype with indel was found on Ulleung Island and without indel on Ulleung Island and Dok Island. This confirmed the existence of two cpDNA lineages with different geographical distributions. The cpDNA sequence analysis also suggested a putative long-distance dispersal event between Ulleung Island and Dok Island.

First Record of the Trans-Pacific Sebastes, S. glaucus(Scorpaeniformes: Scorpaenidae) in the Korean Waters (한국산 환태평양 볼락속(Genus Sebastes), Sebastes glaucus의 최초 보고(쏨뱅이목: 양볼락과))

  • Jeong, Moon Kyung;Ji, Hwan Sung;Kim, Jin-Koo;Lee, Sujin;Hwang, Seon Jae;Hwang, Kangseok;Park, Jeong-Ho
    • Korean Journal of Ichthyology
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    • v.28 no.4
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    • pp.283-286
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    • 2016
  • A single specimen (276.9 mm standard length) of the scorpaenid Sebastes glaucus was collected by a gill net from Dokdo, East Sea, Korea. The specimen is characterized by yellowish brown body color, deep body, convex frontal region and nape, board occipital region, 14 spines at dorsal fin, and no scales at maxilla. This is the first record of S. glaucus in Korea; we therefore add the species to the Korean fish fauna. According to the NFRDI (1999), we propose the Korean name, "Cheong-hoebol-rak" for this species.