• Microbiology and Biotechnology Letters
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• v.47 no.1
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• pp.105-115
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• 2019

Saline or alkaline condition in soil inhibits growth of most crop plants and limits crop yields in many parts of the world. Augmenting an alkaline soil with alkali-tolerant bacteria capable of promoting plant growth can be a promising approach in expanding fertile agricultural land. Near-shore environments of Dokdo Island, a remote island located in the middle of the East Sea, appear to have patches of seawater-influenced haloalkaline soil that is unsupportive for growth of conventional plants. To exploit metabolic capacities of alkali-tolerant bacteria for promoting plant growth in saline or alkaline soils, we isolated of alkali-tolerant bacteria from near-shore soil samples in Dokdo and investigated properties of the isolates. Alkali-tolerant bacteria were selectively cultivated by inoculating suspended and diluted soil samples on a plate medium adjusted to pH 10. Fifty colonies were identified based on their $GTG_5$-PCR genomic fingerprints and 16S rRNA gene sequences. Most isolates were affiliated to alkali-tolerant and/or halotolerant genera or species of the phyla Firmicutes (68%), Proteobacteria (30%) and Actinobacteria (2%). Unlike the typical soil bacterial flora in the island, alkali-tolerant isolates belonged to only certain taxa of terrestrial origin under the three phyla, which have traits of plant growth promoting activities including detoxification, phytohormone production, disease/pest control, nitrogen-fixation, phosphate solubilization or siderophore production. However, Firmicutes of marine origin generally dominated the alkali-tolerant community. Results of this study suggest that haloalkaline environments like Dokdo shore soils are important sources for plant growth promoting bacteria that can be employed in bio-augmentation of vegetation-poor alkaline soils.

• Economic and Environmental Geology
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• v.45 no.6
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• pp.685-695
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• 2012

We studied the detailed bathymetry and the geophysical characteristics of the summit of the Dokdo volcano using mutibeam echosounding and geophysical survey data. The bathymetry around the main east and west islets of the Dokdo volcano shows very shallow within about 10 m water depth. From near islets to about 30 m b.s.l., the shallow water area has very steep slope and many irregular sunken rocks. The area from about 30 m to about 80 m b.s.l. shows gentle rises and falls, and less steep slope. The area from 80 m b.s.l. has gradually flat undulation and smooth slope seabaed and is extended to offshore. The main islets of the Dokdo volcano and the rocky sea bottom elongated from the islets might be the residual part of the eroded and collapsed main crater of the Dokdo volcano. The bathymetry and the seafloor image(from backscattering) data show small craters, assumed to be formed by the eruption of later volcanism. The seafloor images propose that, except some areas with shallow sand sedimentary deposits, there are typical rocky bottom such as rocky protrusions and lack of sediments in the main morphology of the survey area. The stepped slopes of the seabed are deduced to be submarine terraces. The several prominent submarine terraces are found at the summit of the Dokdo volcano, suggesting repetition of sea level changes(transgressions and regressions) in the Quaternary. The results of the magnetic anomaly and the analytic signal have a good coherence with other geophysical consequences regarding to the location of the residual crater.

• Economic and Environmental Geology
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• v.49 no.5
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• pp.381-388
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• 2016

The purpose of this study is to integrate and visualize using mapping techniques based on precise seabed geomorphology, seafloor backscattering images and high-resolution underwater images of the nearshore area around the Dokdo, in the East Sea. We have been obtained the precise topography map using multibeam echosounder system around the nearshore area(~50 m) of the southern part of the Seodo. Side scan sonar survey for analysis seafloor backscattering images was carried out in the same area of topography data. High-resolution underwater images(zone(a), zone(b), zone(c)) were taken in significant habitat scope of the nearshore area of the southern part of the Seodo. Using the results of bathymetry, seafloor backscattering images, high-resolution underwater images, we performed an integrated visualization about the nearshore area of the Dokdo. The integrated visualizing techniques are possible to make the seabed characteristic mapping results of the nearshore area of the Dokdo. The integrated visualization results present more complex and reliable information than separate geological products for seabed environmental mapping study and it is useful to understand the relation between seafloor characteristics and topographic environments of the study area. The integrated visualizing techniques and mapping analysis need to study sustainably and periodically, for effective monitoring of the nearshore ecosystem of the Dokdo.

• Korean Journal of Environmental Biology
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• v.37 no.1
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• pp.19-30
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• 2019

To investigate the characteristics of seasonal environment and phytoplankton community structure in the coastal area of Dokdo, a survey of Dokdo around waters was conducted during the four seasons. Phytoplankton of 4 phylum 72 species in four seasons were collected in Dokdo around water. The seasonal mean abundance of phytoplankton were $3.32{\times}10^4cells\;L^{-1}$ in winter, $1.04{\times}10^4cells\;L^{-1}$ in spring, $0.28{\times}10^4cells\;L^{-1}$ in summer, and $4.86{\times}10^4cells\;L^{-1}$ in autumn in Dokdo around water. During winter, the diatoms Chaetoceros spp. had dominated. During spring, when the nutrients in the euphotic layer were depleted, the nano-flagellates and Cryptomonas appeared at surface layer. In summer, the abundance of phytoplankton was relatively low, which lead to occurrence of diatoms such as genus of Chaetoceros, Rhizosolenia, and Skeletonema. In autumn, Pseudo-nitzschia spp. was the most dominant species and tropical species such as Amphisolenia sp. and Ornithocercus magnificus were observed, implying that they may have introduced within warm water current such as Kurosiwo Current. Therefore, although natural phytoplankton communities in the vicinity water of Dokdo are mainly influenced by Tsushima Warm Current branched Kurosiwo Current, their population dynamics was affected on the spatio-temporal change of physicochemical factors by short-term wind events, namely "island effect". Long-term survey research is needed to facilitate food-web response in marine ecosystem associated with phytoplankton biomass and physicochemical factors including the warm water current in oligotrophic offshore water of Dokdo, which may have significant role for sustainable use of Dokdo.

• ALGAE
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• v.19 no.1
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• pp.69-78
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• 2004

This study was to clarify the variations in a marine ecosystem through examining the species composition of benthic algae in the coast of Dokdo Island during summer (June & August, 2003). The total number of species found in benthic algae was 45 composed of 11% green algae, 29% red algae and 60% brown algae. The dominant species were Enteromorpha linza, Cladophora spp. and Codium frgile for green algae, Ecklonia cave, Eisenia bicyclis, Sargassum confusum, S. patens, S. horneri, Myagropsis myagroides for brown algae and Amphiroa cphedrace. A pusilla, Lithophyllum okamurae, Corallina spp. Laurencia pinnata, L. hamata, Chondria crassicaulit, C. dasyphylla, Gelidium amansii, Neosiphonia yendoi and Polysiphonia yendoi for red algae. The number of benthic algal species decreased more in this study than in previous researches. The whitening of the rocky shore might provoke the decrease of benthic algal biomass and species.

• Ocean and Polar Research
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• v.24 no.4
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• pp.443-448
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• 2002

A study on the ichthyoplankton assemblage was conducted around Dokdo in the East Sea in September 1999 and May 2000. Sixteen species of fish larvae including eggs were collected during the surveys. Anchovy (Engraulis japonicus) eggs and larvae were comprised of 2.0% and 94.5% of total samples in number, respectively. Muller's pearlside (Maurolicus muelleri) eggs and larvae were comprised of 95.0% and 3.2%, respectively. The other species mostly composed of warm water species were less than 2% of total samples in number. The number of species and abundance of the fish lawae and eggs were higher in September than in May. Although there were limited data on the ichthyoplankton around Dokdo in summer and winter, this study area seems to be used for the spawning or nursery ground of fishes.

• Journal of the Speleological Society of Korea
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• no.80
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• pp.5-9
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• 2007

Ulleungdo and Dokdo is special island to all Korean people, The purpose of this study is to collect, sorting, analysis and rearrangement the photo data. The data collected from the published books and new photos. The quantity of data is so big, that it is necessary to divide the volume to publishing the books. For example, aerial photos(including marine topography), the relief of surface, culture and history, urban and settlement, sightseeing and economy, maps and figure and etc. The effect of the study is clear to the civics and students about patriotic sentiment etc.

• Tunnel and Underground Space
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• v.19 no.4
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• pp.318-327
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• 2009

Accelerated weathering tests was executed to understand the physical characteristics of rocks in Dokdo. For the tests rock samples including trachytic andestes, andesite dyke and ash tuff were taken in place. Double soxhlet extractor and peristatic pump were used for accelerating the weathering processes. After the tests for 4 months, the variations of superficial structure, microscopic structure and strength of rock samples were observed.

• Animal Systematics, Evolution and Diversity
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• v.39 no.2
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• pp.61-66
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• 2023

Through a taxonomic study on solitary corals collected from subtidal zones of South and East Seas from 2019 to 2022, Paracyathus rotundatus, an unrecorded species belonging to family Caryophylliidae, is newly added to the anthozoan fauna of Korea. In addition, comparing partial 16S rRNA sequences with a length of 269 bp according to color variation clarified that there were no sequence differences among specimens with color variation, indicating that the color variation is due to intraspecific variation. As a result of this study, a total of 7 genera and 8 species belonging to the Caryophylliidae family have been reported in Korean waters so far.

• Journal of the Korean association of regional geographers
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• v.16 no.3
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• pp.324-337
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• 2010

We believe, 'Dokdo is clearly an inherent territory of Korea, in the light of geographical and historical facts', This paper aims to discuss Japanese multidimensional approach on the Issues of Dokdo(Takeshima) in the context of Territory Education. We considered the matter from various angles that supported by the ministry of Foreign affairs and the ministry of Education in national scale, as well as shimane prefecture government and municipality scale. Therefore, It is likely that the approach of territory education on Dokdo in Japan is variable and potential, and is temporary state of condensation, depends on Korea-Japan's political, economical, social, and international conditions. More studies of the new approach must be done for the new implications of Territory Education that embraces all meanings and events according to the disposition of neighbouring condition of Dokdo in world context, keeping out emotional and nationalist sympathies. The result of consideration in this paper are as follows. First, Territory Education in japan was focused on geography, history, Civil, Social Studies, compared with focusing on History in Korea. Second, It is centered on "korea is illegally occupying Dokdo, against which Japan has been consistently making strong protests" rather than simple historical approach. Thirdly, Their approaches seek to be succeeded the identity and importance of Territory Education to next generation rather than the present solving problem.