• Ocean and Polar Research
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• v.42 no.3
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• pp.263-270
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• 2020

The distribution and genotypes of the sea nettle Chrysaora pacifica have been reported in the South Sea of Korea; however, little research work has been attempted in the East Sea. Here, we collected similar jellyfishes from the East Sea coasts (Goseong, Yangyang and Sokcho), and identified them to the sea nettle morphologically. In addition, the genotypes of these sea nettle were compared with those from the South Sea (Tongyeong and Geoje). Phylogenetic analysis by using the mitochondrial COI sequences showed that the genus Chrysaora was clearly separated from other taxa to be formed a monophyletic group, with each species distinctly separated. C. pacifica in the East and South Seas was separated geographically by the COI phylogeography, representing potentially different populations. The COI gene of the Korean C. pacifica had approximately 7 times more genetic variation than the nuclear ITS rDNA, and thus it might be considered as a useful marker for genetic analysis of the jellyfish population.

• Korean Journal of Ichthyology
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• v.29 no.1
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• pp.80-86
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• 2017

We examined monthly variations in community structure of larval fish assemblage in the coastal waters of south-central Korea in spring and summer, 2016. A total of 31 taxa of larvae were collected during the study period. Engraulis japonicus larvae were predominated in spring than summer. The larvae of Cynoglossus abbreviates, a spring spawners, were exclusively collected in spring, while those of Nibea albiflora, a summer spawners, were exclusively caught in summer. Due to those seasonal differences in abundance of the dominant species, larval fish community was divided into two main seasonal groups (i.e. April~May and June~August). In addition, summer group was divided into two significant subgroups (June~July and August). During August, the larvae of E. japonicus and N. albiflora sharply decreased in abundance due to abnormally high sea water temperature that was raised up to $28^{\circ}C$, with the temperature being out of range of their optimum spawning temperature.

• The Journal of Fisheries Business Administration
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• v.52 no.1
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• pp.1-22
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• 2021

This study aims to face common threats from the depletion of fish resources, the decline of production and employment as well as the increase of life risk in East Sea Rim countries, North Korea, South Korea, Japan and Russia due to the Chinese fishing fleets entering East Sea. The recent competition in fishing among fishing vessels and fleets of national origin operating in the East Sea has induced a significant change in the ecological landscape of the fishing fleets cluster while having influenced production and employment in the fishing industries of South Korea and Japan as well as life threat on the fishermen in North Korea. It seems that the population organizational ecological theory can be applied to this change. It can be seen as the isomorphism of the selection process over the exclusive economic zone (EEZ) to avoid the environment in which these North Korean fishing vessels are pushed against the Chinese fleet in the North Korean part of the East Sea. To resolve the fishery disputes or conflict in the common waters in East Sea, first of all, Chinese fishing fleets will be required to put international pressure so as to solve the unfairness of the illegal fishing and overfishing by the International Fishery Organization or the UN violations of the sanctions against North Korea selling fishing rights to China. Although it is not easy for South Korea to cooperate with North Korea in the short term, South Korea will be able to support the fishery infrastructure in North Korea in the mid- to the long-term to prevent the loss of innocent lives for their fishermen and to raise their incomes.

• Fisheries and Aquatic Sciences
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• v.22 no.6
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• pp.13.1-13.9
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• 2019

Background: Marine invertebrates are well known as pivotal bioresources with bioactive substances such as anti-inflammatory sterols, antitumor terpenes, and antimicrobial peptides. However, there are few scientific reports on chemical compositions and bioactivities of marine invertebrates from the East Sea of South Korea. Methods: In this study, chemical compositions and biological activities were evaluated on both 70% EtOH and hot water extracts of 5 species of marine invertebrates (Crossaster papposus japonicus, Actinostola carlgreni, Stomphia coccinea, Actinostola sp., and Heliometra glacialis) collected from the East Sea of South Korea. The antioxidant activities were measured by ABTS radical scavenging assay. The cytotoxicity and anti-inflammatory activity were evaluated using MTT and Griess reagents. Moreover, the antibacterial effect was evaluated using paper disc assay and minimum inhibitory concentration (MIC) assay. Results: In the results of antioxidant activities, 70% EtOH extract of A. carlgreni showed the highest activity ($IC_{50}\;0.19{\pm}0.03mg/ml$) compared to other extracts. Moreover, 70% EtOH extract of A. carlgreni could significantly suppress the nitric oxide (NO) production in lipopolysaccharide-induced RAW 264.7. All extracts treated under $400{\mu}g/ml$ have no cytotoxic effects on RAW 264.7 macrophages. In the antibacterial test, both 70% EtOH extracts of C. papposus japonicus and H. glacialis showed a significant antibacterial effect on Staphylococcus aureus. The MIC values were evaluated at 256 and $512{\mu}g/ml$, respectively. Conclusions: These results suggested the bioactive potentials of marine invertebrates from the East Sea of South Korea in pharmaceutical and nutraceutical applications.

• Korean Journal of Environmental Biology
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• v.30 no.1
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• pp.71-76
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• 2012

Spills of $M/V$ Hebei Spirit on $7^{th}$ December 2007 caused a seriously damage to the ecosystem of Korean coast. Of these, microbial communities (i.e., attached benthic micro-algae) were reported to be sentive to the environmental change so it can be used for ecological risk assessment. Our experiment was designed to examine the ecological risk assessments for oil pollutant using benthic attached algal community on the artificial substrates of acrylic plates. Field monitoring in the culture system was conducted in Jangmok Bay. The abundances of attached micro-algae on artificial substrates gradually increased with increasing of sampling times. Among them, diatoms were the most important colonizer of coastal water, with the genera $Cylindrotheca$ and $Navicular$ most abundant. In particular, developed the culture system has correctly measured qualitative and quantitative abundance of attached micro-algae because same acrylic plates as artificial substrates were used. Thus, this culture system may be directly applied to the ecological risk experiments of microbial community structure from oil pollutants.

• The Korean Journal of Malacology
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• v.20 no.1
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• pp.35-43
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• 2004

To know the effects on temperature and body size on the clearance rate (CR) of a small tidal flat bivalve, Coecella chinensis, laboratory experiments were performed with 20 individuals of different sizes (ranging from 7 to 25 mm) at 3 different temperatures (10, 15, $20^{\circ}C$). The relationship between body size and CR was determined by an allometric equation. The CR of C. chinensis varied greatly ranging from 0.003 to 0.103 L/individual/hr. Both temperature and body size affected significantly on the CR of C. chinensis. The CR at $20^{\circ}C$was 1.5 times higher than that at $15^{\circ}C$ and 2.8 times than $10^{\circ}C$. The temperature coefficient ($Q_10$) between 10 and $15^{\circ}C$ was higher than that between 15 and $20^{\circ}C$, which indicates that C. chinensis changes its CR more rapidly in lower temperature range. As body size increased, the CR increased more than 10-fold at all temperatures. The CR relative to flesh dry weight (FDW) were fitted well to the power function: CR = a ${\times}$ $(FDW)^b$. The exponent value (b) of the fitted equation ranged from 0.64 to 0.70, which are similar to those of other bivalves. The weight-specific CR ($CR_w$) was still affected by body size (p < 0.05). This implies that smaller individuals require more energy per unit biomass for growth, and the energy requirement for growth decreases as body size increases.

• Fisheries and Aquatic Sciences
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• v.12 no.4
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• pp.331-338
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• 2009

This study presents physiological rates of respiration and excretion, clearance rate, and assimilation efficiency of the ark shell Scapharca broughtonii, determined during 2007 from specimens collected in Gamak Bay on the south coast of Korea. Physiological parameters were measured monthly under static, laboratory controlled conditions with ambient conditions, and measurements were performed seasonally in order to estimate scope for growth and its probable sources of variation. Temperature directly influenced respiration and excretion. Clearance rates showed a tendency to be low during May-August, which is a period of gametogenesis. Assimilation efficiency was not significantly different seasonally and was independent of the concentration of chlorophyll a. The scope for growth was negative during high-temperature months (July-August), reflecting the high temperature and low clearance rate, and had its highest positive values during spring and autumn. The energy budget or growth potential of bivalves has been applied to other economically important species. Data on the physiological parameters and scope for growth of S. broughtonii obtained in this study will be used to assess the carrying capacity for ark shell cultivation.

• Journal of Korea Port Economic Association
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• v.20 no.1
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• pp.95-122
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• 2004

This study focuses on analyzing the potentiality of economic integration and the changes in logistics circumstances in Northeast Asia. So far as the changes in logistics circumstances in it, it is emphasized a complex transport system by sea and by land, according to the connection with the Railroad of South-North in Korean Peninsula and the Railroad of the Continent of Siberia. It first considers the propriety of economic integration among Korea, China and Japan in Northeast Asia. The first stage of the economic integration in Northeast Asia means it is started from contracting of FTA(Free Trade Agreement) which just agreed at the Summit Conference among Korea, China and Japan in ASEAN＋3(Korea China. Japan). At that time, the Summit Conference between the three countries have agreed to study on the propriety of FTA charging by own country's research organization. At first China has been hesitated to join with FTA in spite of high growth in his economy, because the time is not yet for it. After all, China also decided himself to participate to FTA together with Korea and Japan by reacted to the stimulus at the conference atmosphere between every country of ASEAN. The discussion on the changes in logistics circumstances also is needed to deal simultaneously with a situation in the economic integration in Northeast Asia. It is worthy to be paid our attention to the restoration of the Railroad of South-North in Korean Peninsula, which was disconnected for a long time from the dispute between South Korea and North Korea. Therefore, it needs to be investigated together with the movement of economic integration in Northeast Asia. The reaction on the restoration of the Railroad of South-North in Korean Peninsula is not only limited to the transport of trade cargo between South Korea and North Korea, but also it is reached to all of Northeast Asia, so far as to all of the area of Russia, Europe, and the other neighbor countries. Because this railroad is connected with the Railroad of the Continent of Siberia. The transport of trade cargo in Northeast Asia have been mostly depended upon the transport by sea until now. However, it would be divided into the transport by sea as well as by land from now. As its economic effect, the restoration of the Railroad of South-North in Korean Peninsula could be not only contributed to reduce the cost of logistics within South Korea and North Korea, but also within or without in Northeast Asia, Russia, and Europe. Consequently, it could be improved the power of international competitiveness of goods in Northeast Asia, according to the formation of a complex transport system together with the transport by sea and by land.

• Hwankyungkyoyuk
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• v.5 no.1
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• pp.112-137
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• 1993

As the concern with the creation of environmental problems and regulations about them becomes internationally growing, environmental cooperations with countries concerned are emerging as the first item on the political agenda. In case of South Korea, cooperations with countries in the Asian region is needed urgently. In particular, cooperations with North Korea will be an important factor to reunify the Korean peninsula as well as to solve environmental problems in South Korea. Accordingly, it is necessary to seek feasible alternatives and possibilities of coping with international environment in South and North Korea. This study is limited to literature study based on collecting materials and the testimony of former residents in North Korea. The period of study ranges from May to December in 1992. The research findings show the following environmental problems and alternatives : It is recognized in South Korea that the creation of environmental problems is product of economic development. Currently, the Korean government makes an effort to revise environmental administration and law, to encourage environmental education, and to proceed with environmental technology policies by establishing environmental policies together with economic development plans. North Korea ascribes the cause of environmental problems to colonial exploitation by Japan and the U.S. Environmental pollutants in North Korea is relatively less than South Korea, provisions such as environmental conservation movement, environmental education, and environmental administration and law are not well organized in the country. However, North korea will speed up its economic development to solve economic crises. Therefore, it is expected that industrial wastes, corrosion of nature, and water pollution will result in serious environmental problems. The fields expected to cooperate with South and North Korea are in the following : South Korea may adopt the model of the former East and West Germany and proceed to cooperate with North Korea in public sector as well as private sector. The possible programs are such as academic exchange to conserve environment, joint research in the area of the Demilitarized Zone, conservation of ecosystems around Imjin and Pukhan Rivers, South Korea's support of advanced environmental technology and industrial and financial aid to North Korea. Conflicts between countries concerned in the North East Asian region will be caused by the responsibilities of pollutions because of the seashore development of the Yellow Sea by South Korea and increasing seashore industrial complexes around the Yellow Sea in China, Therefore, it is desirable that the two countries will participate in organizations related to environment. Joint projects between South and North Korea will be as follows : 1. Construction of long-range monitoring system : 2. Investigation of the state of pollutions around the Yellow Sea and alternatives : 3. Construction of joint monitoring system to regulate the movement of pollutants : 4. Cooperation of environmental technology and exchange of information ; and 5. Support of Cooperation of environment in private sector. Efforts to cooperate with North korea is expected to overcome differences between the two countries as well as to encourage unification of the korean peninsula, which will lead to reducing the cost of environmental recovery. These efforts will also contribute to the maintenance for peace and stability on the korean peninsula as well as in the North East Asian region.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.54 no.3
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• pp.262-270
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• 2018

We examined the characteristics of egg and larval distributions and catch changes of anchovy in relation to abnormally high sea temperature in the South Sea of Korea in summer 2015 and 2016. The densities of anchovy eggs and larvae in the southern coastal region were lower in July-August 2016 than in July-August 2015. In particular, anchovy eggs and larvae (approximately 5 mm TL) were rarely observed in the coastal region in August 2016 due to the abnormally high SST (up to $28^{\circ}C$), which was above the optimum spawning temperature of anchovy. The catch of non-swimming stage (< 2 cm TL) larval anchovy was lower in July-August 2016 than in July-August 2015. The decreased catch of larval anchovy in July-August 2016 could be attributed to decreased spawning density in June-July 2016. In contrast, the catch of swimming stage (> 2 cm TL) anchovy was increased in July-August 2016. In the summer of 2016, prominent sea temperature near the southern coast of Korea and sea temperature higher than $30^{\circ}C$ in the offshore region of the South Sea of Korea could greatly enhance the retention of swimming anchovies in the coastal fishing grounds.