• Fisheries and Aquatic Sciences
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• v.11 no.1
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• pp.36-40
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• 2008

We analyzed the nucleotide sequences of about 500 bp of the mitochondrial NADH dehydrogenase subunit 3 (ND3) gene to estimate the genetic variation of Korean masu salmon (Oncorhynchus masou) populations. DNA samples were collected from 104 river-only specimens and 52 anadromous specimens from three hatcheries and one river. There are no records of artificial release into the river. We amplified the ND3 gene by polymerase chain reaction, targeting areas that included parts of the cytochrome oxidase III gene and the NADH dehydrogenase subunit 4L gene, and defined 14 haplotypes based on 12 variable nucleotide sites in the examined region. Among the haplotypes, ten were specific to river-only specimens within hatchery populations. Haplotype diversity of river-only populations in hatcheries was higher than that of anadromous and wild populations. Pairwise population $F_{ST}$ estimates and neighbor-joining tree analyses inferred that anadromous and river-only populations were distinct. These results suggest that sequence polymorphism in the ND3 region may be a useful marker for analyzing the genetic variation and population structure of masu salmon.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.4
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• pp.348-354
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• 2001

This study was conducted to estimation of change characteristics for water quality by the dyke gate operation in the Keum River estuary. The estimation data made use of surveyed data in Keum River estuary by NERDI (National Fisheries Research and Development Institute) during $1990\~1999$. Shown to compare water quality changes at st. A and st. D in Figure 1, the concentrations of TSS, COD and nutrients at st. A were as high as about $2\~4$ times than those at st. D due to affection of fresh water discharge in the Keum River. The percentages of water quality change at surface water by dyke gate operation in the Keum River estuary were shown that TSS (Total Suspended Solid) was decrease to $56\%,\;47\%$ at st. A and D, and COD (Chemical Oxygen Demand) was increase to $68\%,\;71\%$ at st. A and D, respectively. The changes percentage of DIN (Dissolved Inorganic Nitrogen) by dyke gate operation in the Keum River estuary were increase high to $95\%$ at surface water and $7\sim30\%$ at bottom water, but those of DIP (Dissolved Inorganic Phosphorus) were increase to $2.8\sim8.6\%$ at surface water and $28\%$ at bottom water. The range of fluctuation for water quality at each station by dyke gate operation has shown that salinity and TSS are little better than before dyke gate operation, but COD show highly fluctuation. Also we studied estimation of characteristics of water quality change by the season, COD was increased except the summer, TSS was decreased to all season. DIN was increased to about $61\sim172.1\%$ for all season, but DIP was increased to the spring and decreased to the autumn, DIN enrichment in the estuary by dyke gate operation are interpreted to improvement of organic matter decomposition and nitrification by increasing the residence time and to increase nutrient flux in sediments due to decreasing dissolved oxygen and increasing a deposit matter.

• Journal of Ocean Engineering and Technology
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• v.28 no.3
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• pp.199-208
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• 2014

In this study, propeller open water characteristics ($K_P$, $K_T$ and ${\eta}_o$) were compared for three different ducted propellers using a Computational Fluid Dynamics (CFD) analysis, as well as an experimental test at a basin. The best shape of the duct was selected from the three types of specially designed ducts based on the CFD analysis results. The same propeller model (Kaplan type propeller) was used inside all three duct models, and the propeller open water characteristics were compared, predominantly at the design speed for an underwater vehicle. Finally, the results of the CFD test simulations for the selected duct case were verified by experimental open water tests in a towing tank.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.14 no.1
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• pp.10-21
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• 2009

Muan Bay has extensively undertaken artificial influences through a series of construction of dams and dykes nearby resulting in a substantial increase in highest high water level. To unravel sedimentary responses to the water level rise, we collected a number of surface sediment samples and hydrodynamic data from in-situ observations of tidal currents in Muan Bay in 1998 and 2007. Comparison of the data between 1998 and 2007 shows that the relative content of coarse fractions, sand and gravel, in the sediment samples has increased with a decreased mean size, on average, from 6.2 to 5.8${\phi}$ at the expense of silt contents. Such a coarsening trend, which is more evident around high water level, particularly on the tidal flats of Dongam-ri, Guro-ri and Aphae-do, is most likely attributable to rising water level. On the other hand, an increase of fine fractions locally in the western entrance of the bay can be explained with changes in characteristics of tidal currents imposed by construction of bridges therein, such as decreased velocities and varied direction and phase of the tidal currents.

• Fisheries and Aquatic Sciences
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• v.7 no.3
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• pp.130-135
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• 2004

The marine dinoflagellate genus Alexandrium, which produces PSP toxins, has a global distribution. As human-assisted dispersal of the species has been suggested, it is important to develop molecular tools to trace the dispersal pathway. To screen population-specific DNA sequences that differentiate Korean and Japanese A. catenella, we targeted the area downstream of the chloroplast psbA gene using PCR with population-specific DNA primers followed by RFLP (restriction fragment length polymorphism) analysis and sequencing. The RFLP patterns of the PCR products divided Korean and Japanese A. catenella regional isolates into three types: Korean, Japanese, and type CMC3, isolated from Korea. We sequenced the PCR products, but found no similar gene in a homology search. The molecular phylogeny inferred from the sequences separated the Korean and Japanese A. catenella strains, as did the RFLP patterns. However, the Japanese isolates included two slightly different sequences (types J and K), while the Korean sequence was the same as the Japanese K type. In addition, a unique sequence was found in the Korean strains CMC2 and CMC3. Population-specific PCR amplification with Japanese A. catenella type-specific PCR primers designed from the type J sequence yielded PCR products for Japanese strains only, showing that the unknown gene can be used for a population analysis of Korean and Japanese A. catenella.

• Environmental Analysis Health and Toxicology
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• v.24 no.2
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• pp.119-125
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• 2009

This study was carried out to investigate the toxic effect of WSF (water soluble fraction) in crude oil on the hatch, survival rate, abnormality and physiological activity of fertilized eggs and early larvae in Paralicthys olivaceus. The time required in hatching the fertilized eggs exposure to crude oil was 50.8${\sim}$53.2 hours both in control group and experimental group, showing no significant difference(p>0.05). The hatching rate in the control group was more than 80% in 1.9 ${\mu}g/mL$ WSF concentration, but hatching rate was less than 55.7% in below of 3.9 ${\mu}g/mL$ WSF concentration, showing significant difference (p<0.05). The survival rate on the 3rd day of early larval stage was 61.96% with 1.9 ${\mu}g/mL$ WSF, 11.1% with 3.9 ${\mu}g/mL$ WSF, and they all died with other concentration levels. The oxygen consumption rate in experimental groups was lower than control group. The heart rate (no./min) was 47.4${\sim}$52.8 before hatching and there was no significant difference between control group and experimental group, but heart rate reduced with the decrease of WSF concentration after hatching. The abnormality was 1.1% in the control group whereas 36.7% with 3.9${\mu}g/mL$ WSF, and abnormality was mostly comprised of incomplete spinal formation and spinal curvature. The results of this study suggest that even low concentration to WSF affects the early development of the flounder, Paralicthys olivaceus.

• Animal cells and systems
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• v.14 no.3
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• pp.197-206
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• 2010

The population structure of brown sole was examined in a total of 308 samples collected from three geographical groups: one locality (Gangneung) on the east side of the Korean Peninsula, two localities (Erimo and Tomakomai) on the southeastern side and four localities (Onishika, Teshio, Tomamae and Yoichi) on the northwestern side of Hokkaido Island, Japan, by using sequences of 484 bp from the 5' end of the control region of mtDNA. We detected 225 haplotypes, but 183 of them were unique to an individual. A total of 116 nucleotide sites were variable. Haplotype diversity (h) was very high, ranging from 0.989 to 1.000, and nucleotide diversity (${\pi}$) was detected between 0.015 and 0.022. Genetic distances (${\Phi}_{ST}$) within populations, among populations and among geographical groups were low (0.0002 to 0.0014). No significant difference was detected by the AMOVA test (P < 0.05). Pairwise $F_{ST}$ values between sampling localities were also low and not significant. Genetic differentiation was not detected among sampling localities.

• The Korean Journal of Malacology
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• v.31 no.4
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• pp.279-283
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• 2015

This study investigated spectroscopic characteristics of shell crystals of eight marine bivalve species using X-ray diffraction (XRD) analysis; moreover, the Family level relatedness of shellfish was investigated. In XRD analysis, the shells of Ruditapes philippinarum, Meretrix lusoria, Anadara granosa, and Fulvia mutica were found to have orthorhombic aragonite $CaCO_3$ crystals, while shells of Patinopecten yessoensis and Crassostrea gigas had trigonal-rhombohedral calcite crystals. The shells of Mytilus coruscus and Atrina pectinata were determined to have a mixture of aragonite and calcite crystals. XRD information revealed the Family level-specific characteristics of shellfish; the results agreed with the current taxonomic system. In conclusion, spectroscopic characteristics of shell crystals indicated Family-level characteristics of shellfish and suggested a more intense species-level investigation; this technology may be useful in identifying shellfish species using small quantities of shells.

• Journal of fish pathology
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• v.21 no.1
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• pp.35-43
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• 2008

Pathological symptoms and hematological parameters of red sea bream, Pagrus major and water temperature in the culture ground was investigated to clarlify the cause of winter moratility. Dead fish showed green liver and accumulation of ascites in the cavity. A few Bivagina tai were also found on the gill but either bacteria or virus were not. When hematological parameters from fish taken before/after the winter mortality were compared, blood glucose, serum AST and ALT, and total cholesterol, trigyceride and total protein were significantly decreased in the fish after the winter mortality. These results may explain that the nutritional level of fish was decreased because fish could not fed during winter season. According to the CORI monitoring system operating by KODC, NFRDI a long term water temperature from Dec. 25, 2005 to Feb. 24, 2006 (60 days) were exposed the low water temperature environments to the red sea bream. First of all, mass mortality began at Sarayngdo where low temperature below 8℃ continued for 42 days. The winter mortality did not occured in the depths of 9 m to 19.2 m where difference of water temperature in the surface and bottom was only within 0.1℃. But in the depth of 7.5 m to 11 m winter mortality occured where water temperature in the surface and bottom showed much variation ranged from 0.2℃ to 1.4℃. From these results, great difference of water temperature in the surface and bottom of the culturing area might results in winter mortality of red sea bream.

• Korean Journal of Ichthyology
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• v.19 no.2
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• pp.112-119
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• 2007

A histological study on development and transformation of the oocyte' follicle cell for Korean four sillurid fishes, Liobagrus obesus, L. mediadiposalis, Pseudobagrus koreanus, and P. brevicorpus was performed by light and electron microscopes. The follicular layer surrounding the oocyte consisted of an outer theca cell and an inner follicle cell (granulosa cell). The follicle cells of the oocyte were flatten cells at early oocyte but during vitellogenesis they were transformed it to a single layer of cuboidal cell, then to a single columnar cell layer, and finally to a layer covered with a substance secreted by themselves. Although the development and transformation of the follicle cells was similar to four species, the secreted materials, called an adhesive membrane, were divided into two types in its appearance and nature. Firstly, a jelly coat-like type was found in L. obesus and L. mediadiposalis, which they are presumed to be polysaccharides and mucoproteins in its nature and secondly, a granular type in P. koreanus and P. brevicopus, being mucoprotein. A zona radiata with about $0.6{\sim}3.1{\mu}m$ thin was present below the adhesive material secreted by the transformed-follicle cell's activity. The zona radiata was composed of two layers, a thin externa and a thick interna.