• Journal of the Korean Society of Marine Environment & Safety
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• v.16 no.4
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• pp.353-360
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• 2010

The result of analysis of the observed temperature data by the Serial Oceanography Investigation of National Fisheries Research and Development Institute (NFRDI) during last 41 years from 1969 to 2008 showed that sea surface temperatures in the East, West and South Sea of Korea were clearly increased. In case of 100m depth, temperature was increased in the South Sea of Korea, but it was decreased in the East Sea. Especially, the temperature around the coastal area in the East Sea was significantly decreased by the spatial distribution of long-term change of temperature on 100m depth. It should lead to the decreasing trend in the long-term change of temperature on 100 m depth in the entire East Sea. The increasing trend was clearly larger in wintertime than in summertime by a factor of about 2 It means that the long-term increasing trend of sea surface temperature in the Korean Waters is usually caused by the distinctive increasing trend in wintertime. As the results of the analysis of air temperature and wind speed on the 6stations around the coastal area in the Korean Waters, air temperature was found to be continuously increased, but wind speed to be gradually decreased in winter. The weakness of vertical mixing by decreasing of wind speed caused to make the surface mixed layer shallow. it could be considered that the increasing trend of surface temperature was caused by weak mixing between surface and intermediate layers.

• Journal of the Korean Society for Marine Environment & Energy
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• v.10 no.3
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• pp.155-166
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• 2007

We carried out a study on the marine environment, such as water temperature, salinity, density and chlorophyll ${\alpha}$, and the distribution of phytoplankton community, such as species composition, dominant species and standing crops in the Southwestern Sea of Korea during early summer 2005. According to the analysis of a T-S diagram, three characteristics of water masses were identified. We classified them into Korean and Chinese coastal water, the cold water and the oceanic water. The first was characterized by high temperature and low salinity in the surface layer influenced by river run offs from China and Korea, the second by low temperature and salinity in bottom layer originated from the bottom cold water of the Yellow Sea, and the third by high temperature and high salinity influenced by Tsushima warm currents. The internal discontinuous layer among them was formed at the intermediate depth (about $10{\sim}20\;m$ layer). And the thermal front appeared in the central parts between Tsushima warm currents and Korean and Chinese coastal waters in the Southwestern Sea of Korea. Chlorophyll ${\alpha}$ concentration was high values in the Korean coastal waters and sub-surface layers. But It was low concentration in the Tsushima warm currents regions. The $Chl-{\alpha}$ maximum layers appeared in the sub-surface layer below thermocline. The phytoplankton community in the surface and stratified layers was composed of a total of 40 species belonging to 26 genera. Dominant species were 2 diatoms, Paralia sulcata, Skeletonema costatum and a dinoflagellate, Scripsiella trochoidea. Standing crops of phytoplankton in the surface layer were very low with cell density ranging from 5 to $3.8\;{\times}\;10^3\;cells/L$. Diatoms were controlled by the expanded low salinity coastal waters of the low salinity with high concentrations of nutrients. Otherwise phytoflagellates were dominant in the high temperature regions where the Tsushima warm currents approches the Southwestern Sea of Korea in early summer.

• The Korean Journal of Petroleum Geology
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• v.5 no.1_2 s.6
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• pp.27-35
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• 1997

The Gorae II area is located in the southwestern margin of the Ulleung Basin, East Sea and corresponds to the Ulleung Trough. The survey of 3D seismic data in this area was performed to delineate the structural leads confirmed by the previous 2D seismic data. As a part of 3D interpretation, basement related structural movements and their relationship with the stratigraphy were studied. The study shows that eight sequences were identified which are genetically related to the tectonics and sediment supply in this area. The geologic structures characterizing the study area consist of : (1) block faults developed in the early stage of basin opening, (2) late Miocene thrusts, and (3) Pliocene wrench faults. The eight sequences consist of pre-rift (acoustic basement), syn-rift (Sequence $A_1, A_2$), post-rift (Sequence $B_1{\~}B_3$), syn-compressional sequence (Sequence C), and post-compressional sequence(Sequence D) from oldest to youngest. The time structure and isochron maps were constructed for each sequence and also used in seismic facies analysis and interpretation of sedimentary environment. The interpretation results reveal that the relative sea level changes caused by several stages of tectonic movements and sediment supply control the stratal and structural geometry of Ulleung basin.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.41 no.2
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• pp.129-139
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• 2005

We investigated the characteristics of the thermohaline structure and phytoplankton community from the southwestern areas of Jeju to the nothern areas of Taiwan in the Ease China Sea, in June 2004. According to the analysis of a T-S diagram, three characteristic of water masses were identified. We classified them into the mixed water mass by the Chiness continental coastal waters and Yellow Sea cold water (Region A), Chinese continental coastal waters (Region B) and Taiwan warm current (Region C). Region A was characterized by low temperature, low salinity, high density and high Chl-a concentration. Region B was characterized by high temperature, low salinity, low density and high Chl-a and Region C was characterized high temperature, high salinity, low density and low Chl-a concentration. The phytoplankton community identified a total of 56 species belonging to 31 genera. The dominant species was mainly dinoflagellates, Gymnodinium breve, Scrippsiella trochoidea, Ceratium fusus, Prororcentrum triestinum, centric diatoms, Chaetoceros lorenzianus, Leptocylindrus danicus, Proboscia alata, Skeletonema costatum and pennate diatoms, Pseudonitzschia pungens, Cylidrotheca closterium. Standing crops of phytoplakton fluctuated between $0.1{\times}10^2$ cells/L and $5.7{\times}10^4$ cells/L by dominance of dinoflagellates. In the phytoplankton community, the Region A was characterized by the various species composition in 39 species, the dominint species with di-atomes, Pn. pungen, Ch. lorenzianus and standing crops from 6.9 cells/$m\ell$ to 56.6 cells/$m\ell$, Region B by the various species composition in 37 species, the dominant species with dinoflagellates, G.breve, S. trochoidea and standing crops from 4.6 cells/$m\ell$ to 26.7 cells/$m\ell$, and the Region C by low species number with 28 species, the dominant species with one dinoflagellate, S.trochoidea and one diatom, L.danicus and very low standing crops from 0.1 cells/$m\ell$ to 5.7 cells/$m\ell$. Phytoplankton productivity in the East China Sea was controlled by Chinese continental coastal waters which include a high concentrations of nutrients.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.441-453
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• 2017

This paper described the spatio-temporal distributions in the phytoplankton community, such as species composition, standing crops, and dominant species, from July 2012 to April 2013 in the Coastal Waters of Central South Sea (CWoCSS) of Korea. A total of 87 species of phytoplankton belonging to 52 genera were identified. In particular, diatoms and phytoflagellates comprised more than 62.1% and 37.9% of the total species, respectively. The phytoplankton cell density fluctuated with an annual mean of $7.9{\times}10^4cells{\cdot}L^{-1}$ between the lowest value of $1.0{\times}10^3cells{\cdot}L^{-1}$ in spring and the highest value of $4.5{\times}10^5cells{\cdot}L^{-1}$ in winter. The seasonal succession of the dominant species were Chaetoceros curvisetus, Ch. debilis in summer, Eucampia zodiacus in autumn, E. zodiacus, Thalassiosira curviseriata in winter and Skeletonema costatum -ls (like species), Leptocylindrus danicus in spring. According to principal component analysis, the phytoplankton community of the CWoCSS was characterized by the mixing rate between the freshwater inflow from Somjin River and the seawater of the South Sea, Korea.

• Korean Journal of Environmental Biology
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• v.34 no.4
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• pp.292-303
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• 2016

This study described the spatial distributions of marine environmental factors such as water temperature, salinity, chlorophyll a concentration and turbidity, and characteristics of phytoplankton community such as species composition, standing crops and dominant species at 19 fishing ports around Jeju Island during the early summer of 2016. I analyzed bio-oceanographical characteristics using principal component analysis (PCA) of the environmental factors and biological parameters. Water temperature, salinity, chlorophyll a and turbidity ranged from 17.6 to $20.7^{\circ}C$, from 26.19 to 32.33 psu, from 0.76 to $7.13{\mu}g\;L^{-1}$, and from 0.51 to 14.49 FTU, respectively. A total of 51 species of phytoplankton belonging to 35 genera were identified. In particular, diatoms and dinoflagellates accounted for more than 56.8% and 27.4% of all the species, respectively. Moreover, the number of phytoplankton species was controlled by salinity. Phytoplankton cell density ranged from $2.9cells\;mL^{-1}$ to $185.9cells\;mL^{-1}$. The dominant species were Navicula spp. Stephanopyxis turris, Eutreptiella gymnastica and Mesodinium rubrum. Environmental factors and the phytoplankton community varied greatly between sampling sites. According to PCA, the biological oceanographic characteristics of the around Jeju Island were characterized by meteorological factors such as air temperature, precipitation and discharge of ground water during early summer.

• 한국해양학회지
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• v.27 no.2
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• pp.123-136
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• 1992

As a result of faunal analysis on 50 bottom samples bearing a total of 183 species of the Recent benthonic foraminifers from the West and South Sea of korea, five bioassociations (groups of species) and five biotopes (groups of samples) were discriminated. From the areal distribution of biotopes in combination with bioassociations and the available ecological data of foraminiferal species, five biofacies are recognized: (1) Southern Inner Shelf Biofacies; (2) Southern Coast Biofacies; (3) Northern Middle Shelf Biofacies; (4) Central Middle Shelf Biofacies; and (5) Southern Outer Shelf and Upper Slope Biofacies. The biofacies are defined by a group of sampling stations containing a diagnostic species association and can be related to the major current pasterns and water masses in the West and South Sea of Korea: Southern Inner Shelf Biofacies is related to the Coastal Waters and drainage from China; Southern Coast Biofacies is related to the Coastal Waters and drainage from Korea; Northern Middle Shelf Biofacies is related to the Coastal Waters and Yellow Sea Cold Water, Central Middle Shelf Biofacies is related to the Yellow Sea Warm Current; and Southern Outer Shelf and Upper Slope Biofacies is related to the Tsushima Warm Current.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.17 no.2
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• pp.59-75
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• 2012

The species composition of plankton is essential to understand the material and energy cycling within marine ecosystem. It also provides the useful information for understanding the properties of marine environments due to its sensitivity to the physicochemical characteristics and variability of water masses. In this study we adopted metagenomics to evaluate eukaryotic plankton species diversity from coastal waters off Busan. Characteristics of water masses at sampling sites is expected to be very complex due to the mixing of various water masses; Nakdong River runoff, Changjiang diluted water (CDW), South Sea coastal water, and Tsushima warm current. 18S rDNA clone libraries were constructed from surface waters at the three sites off Busan. Clone libraries revealed 94 unique phylotypes from 370 clones; Dinophyceae(42 phylotypes), Ciliophora(15 phylotypes), Bacillariophyta(7 phylotypes), Chlorophyta(2 phylotypes), Haptophyceae(1 phylotype), Metazoa(Arthropoda( 17 phylotypes), Chaetognatha(1 phylotypes), Cnidaria(2 phylotypes), Chordata(1 phylotype)), Rhizaria (Acantharea(2 phylotypes), Polycystinea(1 phylotype)), Telonemida(1 phylotype), Fungi(2 phylotypes). The difference in species diversity at the closely located three sites off Busan may be attributed to the various physicochemical properties of water masses at these sites by the mixture of water masses of various origins. Metagenomic study of species composition may provide useful information for understanding marine ecosystem of coastal waters with various physicochemical properties in the near feature.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.20 no.2
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• pp.83-90
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• 1984

The secular fluctuations of catches and fishing grounds of mackerals and the oceanographic conditions for the fishing grounds are examined by using the data of catches of mackerals by middle and large class purse-seiner during 1951 to 1981 and those of oceanographic observation carried out by Japan Meteorological Agency. The results are as follows; The fishing grounds of mackerals are respectively distributed at northeastern and southwestern areas from the central part of the East China Sea through every season of the studied years: 1968, 1974 and 1980. The narrow belt type of fishing grounds were formed inside of the Kuroshio in spring and winter of the three years. In summer mackeral species move northward and the fishing grounds are formed in the southern sea of Korea. In winter, however, mackeral species move southward and the fishing grounds are appeared in the Tsushima Current region. The dispersion of fishing grounds is generally larger in summer and smaller in spring, and especially it is the largest in summer in 1980. It seems that the concentration and dispersion of fishing grounds are related to the depth of thermocline and the position of horizontal temperature gradient in this area.

• Korean Journal of Environmental Biology
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• v.38 no.3
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• pp.355-370
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• 2020

We conducted a field survey to analyze the ecological structure and spatial distribution of microplankton (phytoplankton and ciliates) in relation to water masses at 21 stations on the surface and chlorophyll-a maximum layers (CML) in the Northern East China Sea (nECS; 32°-33°N; 124°00'-127°30'E) from August 3 to August 6, 2019. The results showed that the water masses were divided into Chinese Coastal Waters (CCW) and the Tsushima Warm Current (TWC). The CCW showed the environmental characteristics of high temperature and low salinity, and the TWC showed high temperature and high salinity. The characteristics of the phytoplankton community in the CCW showed various community structures related to the nutrients supplied from the large rivers of the Chinese continent. However, the TWC had simple community structures because it originated near the equator and moved northward. The standing crops of phytoplankton and ciliates were very high in the CCW but showed low at the TWC. In particular, from the higher standing crops of protozoa than plant plankton at the TWC, the energy flow at the lower tropic levels caused by the microbial loop that fed on heterotrophic bacteria played an important role in the production of resource organisms. In other words, the marine ecological structure of the nECS in summer could be estimated as a bottom-up system at the CCW and a top-down system at the TWC.