• Ocean and Polar Research
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• v.29 no.4
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• pp.283-295
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• 2007

We investigated the longitudinal variations in zooplankton abundances and their related physicochemical properties at nine stations located between $136^{\circ}W$ and $128^{\circ}W$ at $10.5^{\circ}N$ in the northeastern Pacific in summer 2004. Temperature, salinity, inorganic nutrients, chlorophyll-a (hereafter chl-a) and zooplankton ($>200\;{\mu}m$) were sampled within the depth from the surface to 200 m depth at $1^{\circ}$ longitude intervals. Zooplankton($>200\;{\mu}m$) samples were vertically collected at two depth intervals from surface to 200 m, consisting of surface mixed and lower layers (thermocline$\sim$200 m). Longitudinal distributional pattern of hydrological parameters (especially salinity) was physically influenced by the intensity of westward geostrophic current passage relating to the NEC (North Equatorial Current). Data from the longitudinal survey showed clear zonal distributions in the hydrological parameters(temperature, salinity and nutrients). However, spatial patterns of the chl-a concentrations and zooplankton abundances were mostly independent of the zonal distributions of hydrological parameters. The two peaks of zooplankton abundance in the surface mixed layer were characterized by different controlling factors such as bottom-up control from nutrients to zooplankton ($129^{\circ}W$) and accumulation by increment of friction force and taxonomic interrelationship ($133^{\circ}$ and $134^{\circ}W$). Divergence-related upwelling caused introduction of nutrients into surface waters leading to the increment of chl-a concentration and zooplankton abundances ($129^{\circ}W$). Increased friction force in relation to reduced flow rates of geostrophic currents caused accumulation of zooplankton drifting from eastern stations of study area($133^{\circ}$ and $134^{\circ}W$). Besides, high correlation between immature copepods and carnivorous groups such as chaetognaths and cyclopoids also possibly contributed to the enhanced total abundance of zooplankton in the surface mixed layer (p<0.05). Zooplankton community was divided into three groups (A, B, C) which consecutively included the eastern peak of zooplankton($129^{\circ}W$), the western peak($133^{\circ}$ and $134^{\circ}W$) and high nutrient but low chl-a concentration and zooplankton abundance ($136^{\circ}W$). Moreover, Group B corresponded to the westward movement of low saline waters(<33.6 psu) from 128 to $132^{\circ}W$. In summary, longitudinal distributions of zooplankton community was characterized by three different controlling factors: bottom-up control ($129^{\circ}W$), accumulation by increased friction force and relationships among zooplankton groups ($133^{\circ}$ and $134^{\circ}W$), and mismatch between hydrological parameters and zooplankton in the high nutrient low chlorophyll area ($136^{\circ}W$) during the study period.

• Ocean and Polar Research
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• v.29 no.4
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• pp.401-410
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• 2007

In Korea the study of marine heterotrophic protists started in the late 1980s, and since the early 1990s many studies have been conducted in various marine environments. In this article, studies on the distribution and abundance of protists and the biotic interactions(bacteria-protists, phytoplankton-protists) conducted in Korean coastal waters are reviewed, and a field study is reported and discussed. The field study in Masan Bay was carried out from February 2004 to November 2005 at seven selected stations representative of the bay. During the study, the mean abundance of heterotrophic bacteria and the mean concentration of chlorophyll-a were $2.1{\times}10^6\;cells\;mL^{-1}$ and $9.8{\mu}g\;L^{-1}$, respectively. Heterotrophic protists consisted of heterotrophic dinoflagellates, heterotrophic nanoflagellates(excluding dinoflagellates) and ciliates, and their abundances were means of $7.9{\times}10^4\;cells\;L^{-1}$, $1.2[\times}10^3\;cells\;mL^{-1}$, and $4.0{\times}10^4\;cells\;L^{-1}$, respectively. Generally, the chlorophyll-a concentra+CZ14tions and the abundances of heterotrophic bacteria and protists were higher in the inner zone of the bay, where there are high concentrations of organic matters, than in the middle and outer zones. Using the grazing rates of heterotrophic nanoflagellates on bacteria previously reported in this area, it can be calculated that about 69% of bacterial producton was removed by HNF grazing activity. About 24% of initial chlorophyll-a concentration was removed by microzooplankton grazing activity. In conclusion, this study suggests that in Masan Bay heterotrophic protists control the growth of bacteria and phytoplankton, and heterotrophic protists represent an important link of bacterial & microalgal biomass to higher trophic levels.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.3
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• pp.480-487
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• 1997

Vitellogenin (Vg) was purified from plasma of $estradiol-17\beta(E_2)-treated$ spotted flounder, verasper variegatus, by preripitation with cold distilled water, followed by fractionation using a Sepharose CL-6B column chromatography. $E_2-induced$ protein was identified as Vg by SDS-PAGE and western blot analysis. The molecular weight of the purified Vg was estimated 175 kD as determined by SDS-PAGE. In order to measure the Vg level, monoclonal antibodies against Vg were produced by hybridoma technique. Purified Vg was immunized into Balb/c mice and then the spleen cells from mice were fused with NS-1 myeloma cells. The hybridoma cells were screened by enzyme-linked immunosorbent assay (WLISA) and subcloned by limiting dilution. The hybridoma clones which secreted antibodies highly reactive to the purified Vg were designated as 4D6. Its specificity was demonstrated by western blot from plasma of untreated, $E_2-treated$ male fish, and purified Vg.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.3
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• pp.388-392
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• 1997

The random amplified polymorphic DNAs (RAPD) technique was used to characterize seven isolates of the green seaweed Ulvales collected from Songjeng, Haeundae, Jumunjin, Dadaepo and Wando in Korea. Total DNA was extracted by the LiCl extraction method from thalli of green seaweed. The extracted DNA (3 ng) in $25{\mu}\ell$ reaction volume was amplified by 45 cycles of the polymerase chain reaction with arbitrary primers. Thirty-four primers resulted in 1227 PCR products ranged 240 bp to 1.5 kb of both conserved and polymorphic bands. Genetic similarities of the seven isolates calculated by Jaccard's equation were ranged from $7\%\;to\;36\%$. Monostroma nitidum (Wando) was shown to be most distantly related with the others based on genetic similarity and did not produce the amplified band of 630 bp, common in Ulvales using primer OPB-01 (CATCCCCTG).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.6
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• pp.605-610
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• 2001

We investigated the effects of salinity on an estuarine cladoceran, Diaphanosoma celebensis as a substitute live food organism of Artemia, which has been used for the next step of rotifer, in the course of seedling production of marine fishes, Culture density for growth, possibility of stable culture (RPGI: Relative Population Growth Index) and food feeding activity (RCN: Remaining Cell Numbers) of D. celebensis were investigated at intervals of 5 ppt under 10 steps of different saline conditions from 0 to 45 ppt. According to the results, the experimental group, which was regarded as the best condition of culture density for growth, stable culture possibility (RPGI) and good food feeding activity (RCN), was salinity culture condition of 20 put, and relative stable culture conditions were observed under saline concentrations $15\~35\;ppt$. Their functions under culture conditions of lower or higher salinities than 20 ppt appeared remarkably to be decreased, while all individuals were dead under the saline condition of 0 ppt after the beginning of the experiment. From these results of this study, it is assumed that estuarine cladoceran, D. celebensis can be cultured easily as a substitute live food organism of Artemia in the course of seedling production of marine fishes.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.6
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• pp.697-704
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• 2001

In this study, we investigated that the survival and growth responses of freshwater cladoceran Moina macrocopa and estuarine cladoceran Diaphanosoma celebensis on the saline culture conditions after transferring for using as live food organism. Estuarine cladoceran D. celebensis was survived and grew on the all salines except to saline jump culture condition of 0 ppt. However, freshwater cladoceran M. mcrocopa was died or decline on the over saline jumping culture conditions of 4 ppt within 5 minutes. These suggest the possibility of using the estuarine cladoceran D. celebensis compare with freshwater cladoceran M. macrocopa as a substitute live food organism for Artemia in the marine larval rearing.

• Geophysics and Geophysical Exploration
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• v.9 no.4
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• pp.261-270
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• 2006

Two-dimensional (2-D) inversion of magnetotelluric (MT) data for two survey lines having south-north direction from Jeju Island has been carried out. Broad band MT sounding curves with good quality could be gathered by performing audio-frequency magnetotelluric (AMT) survey during the MT survey and by operating the remote reference in Kyushu Island, Japan. Comparison of the 2-D inversion model using MT band only and that using both AMT and MT bands for the field data as well as for the data from numerical 2-D modeling said that high frequency information from AMT survey can be useful for interpreting not only the shallow part but also the deep structures, especially when the formation is resistive. The 2-D inversion models of field data show a thick layer having around 10 ohm-m in the depth of a few hundred meters throughout the survey area, which can be considered as the unconsolidated sedimentary layer. And they also show a conductive anomaly at the central part of each survey lines. It can be either the effect of the surrounding sea water, or the structures due to ancient volcanic events. But unfortunately by now, we do not have any further information about the anomaly.

• Journal of the Korean Association of Geographic Information Studies
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• v.20 no.4
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• pp.139-151
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• 2017

The habitat preference of roe deers(Capreolus pygargus) in Jeju island, South Korea was analyzed by using their occurrence probability in MaxEnt model in this study. Totally 490 surveying data were gathered and 15 environmental variables were chosen for the model in which 6 variables out of 15 ones were filtered and finally removed because of there being higher correlation(over 0.7 in correlation coefficient). According to the modeling, roe deers were known to prefer the area ranging from 200 to 700 meter and over 1,500 meter in sea level, where there were not many dominant tree and/or dominant vegetation with low density so that understory vegetation can grow well with plentiful sunlight and can be used as a food of herbivore like roe deers. Otherwise, the region ranging from 700 to 1,500 meter was mostly covered with high density vegetation which cut off sunlight trying to penetrate through the dominant vegetation. It can cause a lower density of vegetation on surface, which can not attract to roe deers.

• Journal of Navigation and Port Research
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• v.27 no.2
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• pp.233-238
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• 2003

Due to the impermeability of outer wall facilities such as Breakwaters which dissipates the wave energy and keeps harbor tranquility, the enclosed area of harbor becomes partially blocked and the water exchange can be reduced. Recent trends of port development protect water quality and emphasize Water-Front, so the method which enhances the circulation of harbor waters and the dilution of the water pollutants are studied. The best improvement of water quality is a remove of pollutant source on land, but an enclosed port must be enhanced the tidal exchange. For this end, the best improvement may be made a drain-route on the existing outer wall facilities. In this study, the numerical computations were carried out to predict the circulation of harbor waters and the tidal exchange through the drain-rout in the polluted harbor(Samchonpo-guhang) located at the east coast of South Sea. Computational models adopting FDM(Finite Difference Method) were used here and were already verified from the previous studies und ocean survey. As a result of this study, circulation and the tidal exchange at the harbor before and after introduction of drain-route were assessed.

• Journal of Navigation and Port Research
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• v.41 no.4
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• pp.195-206
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• 2017

In situ capping technology for marine sediment pollution control has never been applied in South Korea. In this study a pilot project for the capping was carried out in Busan N Harbor. Pipeline and clamshell capping technologies were implemented for the pollution control. Changes of capping shapes, sediment contamination, and the time and costs required for the two constructions were compared. Both the pipeline and clamshell technologies were found to satisfy the target thickness of 50 cm on average. However, the pipeline method did not operate sensitively in terms of change of the sea floor topography, resulting in an uneven shape and a thickness. Organic carbon and ignition loss quite decreased after the pipeline or the clamshell capping while pH showed no significant change. Organic and residual fraction of Cd, Ni, and Zn in the sediments appeared to decrease after all cappings. The pipeline method took a construction time four times as much as the clamshell method. The clamshell method was demonstrated to reduce the construction cost by about 40% compared with the pipeline method. However, a monitoring for all the parameters needs to be conducted at least two years in order to better evaluate an efficiency of the pollution control by these capping constructions.