• Ocean and Polar Research
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• v.23 no.3
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• pp.279-284
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• 2001

The natural high productivity of temperate coastal waters in Korea can be used in advantage to reduce the feed costs for the cage-cultured marine carnivorous fish species. By using the night-lights methods an alternative of supplementary feeding strategy can be offered to the cage farmers and maintain sound environmental conditions that could enhance maximum sustainable yields. The aim of this study was to investigate the effects of night-lights which shown positive results on feeding and growth in sea cage cultured rockfish, Sebastes schlegeli. The study showed that for the water around overhead illuminated sea cage, higher zooplankton density was observed at night than during the daytime. Increased amounts of for-age, evidenced by stomach content analyses were observed in the early evening, but decreased amounts were observed in the morning and afternoon. That is, feeding activities of the fish were most intensive from midnight to dawn. In a three month feeding experiment, the results showed that night-lighted groups were superior to groups with the highest feeding efficient. This study suggested that the evidence that night-lights superimposed on only day-lights enhance growth of rockfish in sea cages during summer and winter, with timing of exposure affecting growth of juvenile fish. The capability to control the feeding behavior of marine life via manipulation and external stimuli could considerably benefit the advancement of sea cage aquaculture in coastal areas.

• Ocean and Polar Research
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• v.33 no.3
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• pp.255-263
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• 2011

The aim of this investigation was to evaluate antioxidant activity of crude extracts from the halophyte Vitex rotundifolia, their solvent fractions, and isolated compounds (1-3). Antioxidant capacity was determined by measuring DPPH radical, and authentic $ONOO^-$ and $ONOO^-$ generated from 3- morpholinsydnonimine (SIN-1) in vitro as well as degree of occurrence of intracellular ROS, NO and GSH in mouse macrophage Raw 264.7 cells. From comparative analysis, MeOH extract, n-BuOH, and 85% aq. MeOH solvent fractions showed significant antioxidant effect in DPPH radical and $ONOO^-$ assay systems. Activity-guided purification of n-BuOH and 85% aq. MeOH fractions led to the isolation of flavonoids 1-3. Among them, compound 1 exhibited excellent antioxidant effect in all bioassay systems tested. On the other hand, compounds 2 and 3 revealed potent inhibitory effect against $ONOO^-$ generated from SIN-1, comparable with the positive control penicillamine.

• Ocean and Polar Research
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• v.33 no.spc3
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• pp.337-347
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• 2011

We investigated latitudinal changes in mesozooplankton community structure during a cruise between October 16 and November 30 of 2007 from four distinctive regions in the northwestern Pacific Ocean: Warm pool area (longitude $135^{\circ}$ line), Philippine EEZ (PEEZ), Japan EEZ (JEEZ), and East China Sea (ECS). Major taxa of numerical importance were Clausocalanidae (Clausocalanus spp.), Oncaeidae (Oncaea spp.), and Oithonidae (Oithona spp.) in oligotrophic regions, however Paracalanidae (Paracalanus spp.) was the most abundant group in the ECS. Mesozooplankton size group of <1 mm dominated in PEEZ and WP (48% and 56%, respectively), but mesozooplankton (>1 mm) were of importance in the JEEZ and ECS (34% and 38%, respectively). Mesozooplankton biomass and abundance were high in the JEEZ and ECS, and low in the oligotrophic WP and PEEZ waters, with positive relationship with both total Chl-a and heterotrophic protist biomass. Latitudinal change in mesozooplankton community structure was related with water temperature, with copepods such as Lucicutia spp. and Pleuromamma spp. being present only in warm waters. The geographical expansion of mesozooplankton with a preference for warmer waters could potentially be useful as an indicator for detecting ocean warming.

• Ocean and Polar Research
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• v.32 no.1
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• pp.23-40
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• 2010

This study investigated the effects of imported fisheries products on WTO/DDA tariff negotiations. To calculate the results, the study estimated the demand functions of imported fisheries products by using unit root and cointegration approaches. These approaches allowed us to solve spurious regression problems with macro-economic variables. In addition, this study surmised the effects of change by individually imported fish products from a tariff negotiation model using price elasticities of estimated import demand function. In a process of the analysis for estimating import effects, this study found out that 39 out of 128 imported fish products had positive (+) price elasticities or did not exhibit cointegrations. To cure this problem, this study suggested that the effects of these 39 imported products be estimated with the average variation rate of import volume, rather than by the Ordinary Least Squares approach. In this study, a case-study of tariff formula with coefficient 8 based on a 'Swiss formula' for priority duty rate of 2001 and 2008 was used by to analyze the effect of change in the 128 imported fish products of both years, respectively.

• Ocean and Polar Research
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• v.25 no.1
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• pp.75-87
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• 2003

The water balance calculation in the IRL shows that fresh groundwater discharge is the primary factor, with surface runoff from gaged and ungaged areas as the second freshwater contributor. Precipitation and evaporation are almost in balance fer the entire IRL. Due to high freshwater discharge from ground-water, the annual net flow is outward from the IRL to the continental shelf of the Atlantic Ocean resulting in a relatively short flushing time, denoted as $T_{0.5}$ (50% flushing time) and $T_{0.99}$ (99% flushing time). $T_{0.5}$, and. $T_{0.99}$ without a tidal effect in the Northern IRL are 17 and 114 days, respectively, during the dry season. During the wet season, they are 10 and 65 days, respectively. Tidal flushing effects are considered in central IRL due to the proximity to Sebastian Inlet. In the Northern Central zone during dry season, $T_{0.5}$, and. $T_{0.99}$ are 6 and 43 days, respectively and during the wet season 5 and 33 days. In the Southern Central zone they are 2 and 16 days for the dry season,2 and 15 days for the wet season. High groundwater seepage into the IRL is considered to be a positive effect in maintaining relatively good water quality condition even with few narrow inlets.

• Ocean and Polar Research
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• v.26 no.1
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• pp.77-86
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• 2004

The paper is to estimate the economic value of ecotourism in Anmyeondo tidal wetlands using a double-bounded dichotomous choice (DBDC) model of the Contingent Valuation Method (CVM). For the reliability and the validity of CVM a survey was conducted for 511 visitors by personal interview method in Anmyeondo during August 2000, and respondents were asked for maximum Willingness-To-Pay (WTP) to buy a ticket fer the tidal flat's ecotourism. Overall, respondents answered that they would be willing to pay 55,879 won for a ticket under the study. All equations and results estimated are statistically significant at the 1% or 5% level. For the aggregation of WTP estimates, the sample values are extended to the total annual number of visitors in Anmyeondo area during 1998. A conservative estimate, which considers the calibration factor (0.5) recommended by NOAA (1994) and a positive response rate (83.17%), is 73 billion won.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.5
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• pp.611-621
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• 2014

A nationwide survey was conducted to study the rate of Kudoa septempunctata parasitization in cultured olive flounder, Paralichthys olivaceus, in Korea in 2013. Of 1107 olive flounder sampled randomly from 89 culture farms in five different regions in Korea, K. septempunctata was detected only in Jeju, where 10 of 318 fish (3.14%) were PCR positive, with genomic concentrations of $4.67{\times}10^5$ to $1.48{\times}10^{11}$ rDNA copies/g by real-time PCR. Of the ten Kudoapositive fish, K. septempunctata spores with 5-7 polar capsules were detected only in four fish. No samples of K. septempunctata were detected in olive flounder from the other regions surveyed. Furthermore, K. septempunctata was not detected in 326 samples of olive flounder seeds sampled from 39 hatcheries in seven different regions in Korea. Therefore, the parasite infection is restricted to Jeju and K. septempunctata infection is not spread from hatcheries.

• Journal of Microbiology and Biotechnology
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• v.20 no.2
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• pp.410-414
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• 2010

A bacterial strain, 13-$25^T$ with xylanolytic activity isolated from a single soil sample, was characterized with respect to its phenetic and phylogenetic characteristics. The cells of the isolate are Gram-staining variable rods, but spore formation was not observed. This strain is catalase- and oxidase-positive, and able to degrade starch and xylan. The predominant fatty acids are anteiso-$C_{15:0}$, $C_{16:0}$, and iso-$C_{16:0}$. The major respiratory quinone is menaquinone 7(MK-7), with a polar lipid profile consistent with the genus Cohnella. The DNA G+C content is 54.3 mol%. The 168 rRNA gene sequence analysis indicates that this organism belongs to the genus Cohnella, with Cohnella panacarvi as the closest phylogenetic neighbor. Low levels of 168 rRNA gene sequence similarity (<97.0%) with respect to other taxa with published names and the identification of distinctive phenetic features in the isolate indicate that the strain 13-$25^T$ represents a novel species of the genus Cohnella, for which the name Cohnella damensis sp. novo is proposed. The type strain is 13-$25^T$ (=CCTCC AB $208103^T$=KCTC $13422^T$).

• Plant Disease and Agriculture
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• v.5 no.1
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• pp.1-7
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• 1999

The grain rot of caused by Bukholderia glumae was fist reported in japan in 1955 and then reported in other countries as well as in Korea in 1986. The pathogen causes both seedling and grain rot of rice but it cannot attack any other parts of adult rice plant. Bacterial colonies grow slowly, and are circular and greyish white. The causal bacterium is Gram-negative and rod shape with 1-3 polar flagella, and produce a diffusible yellow-greenish nonfluorescent pigment on King's medium B. Biochemical characteristics such as negative in arginine dehydrolase, oxidase reaction and nitrate reduction and positive in lecithinase, and the utilization of L-arginine and inositol are useful in differentiation of this from other nonfluorescent bacteria pathogenic to rice. This pathogenic bacterium had belonged to the genus of Pseudomonas but recently was transferred to the new genus Burkholderia on the basis of physiological characteristics and DNA-DNA hybridization data. However, other characteristics such as colony heterogenicity or colonial variation after subcultures, phytotoxin, secreting antibiotics, and relationship between yellow greenish pigment production and pathogenicity need to be clarified more. To develop an effective control strategy for this disease, understanding of detailed life cycle of the disease and critical environmental factors affecting disease development is prerequisite. Although 5,435 ha of rice paddy in Korea was infested during 1998, there is no exact estimation of yield losses and distribution of the pathogen. The review will focus on recent progress on the understanding of the bacteriological and ecological characteristics of the causal bacterium and control means of the disease.

• Journal of Microbiology and Biotechnology
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• v.11 no.5
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• pp.756-762
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• 2001

As a component for a recirculating aquaculture system, a new strain of denitrifying bacterium was isolated from municipal sewage. The isolate was motile by means of one polar flagellum, catalase-positive, and a Gram-negative rod-shaped cell measuring $0.5-0.6{\mu}m$ in width and $1.3-1.9{\mu}m$ in length. The isolate was identified as Pseudomonas fluorescens and produced dinitrogen gas via the reduction of nitrate. The optimal growth conditions (pH, temperature, carbon source, and C/N ratio) of the isolate were found to be 6.8, $30^{\circ}C$, malate, and 3, respectively. Under optimal growth conditions of P. fluorescens, dinitrogen gas was first detected in the exponential growth phase, then a small amount of nitrite was developed and converted to dinitrogen gas in the stationary phase. Pseudomonas fluorescens cells were immobilized in modified polyvinyl alcohol (PVA) gel beads, and the maximum denitrification rate was measured as $36.6 {\mu}lN_2h^-1$ per bead with an optimum cell loading of $20mg {\mu}l^-1$ and $2\%$ sodium alginate added to the PVA gel. The operating stability of the modified PVA gel beads remained unchanged for up to 43 repeated batches.