• Journal of the Korean Society for Marine Environment & Energy
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• v.8 no.3
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• pp.140-147
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• 2005

We investigated the interactions between coastal waters of the Yeongil Bay, Korea, and oceanic waters of the Eastern Sea, as wet 1 as the development mechanism of vertical circulation currents in the bay. The oceanic waters of the bay have an average water temperature of $12.2{\sim}18.4^{\circ}C$ and salinity of $33.32{\sim}34.43$ PSU. Results of spectral analysis have shown that the period of revolution between oceanic and coastal waters is about 0.84-0.91 years in the surface waters and 1.84 years in the bottom layer. The wind direction in the bay shifts between SW and NE, with the main wind direction being SW during the winter period, and water mass movement is influenced by such seasonal variations in wind direction. Vertical circulation currents in the bay are structured by two phenomena: the surface riverine outflow layer from the Hyeong-san River into the open sea and the bottom oceanic inflow layer with high-temperature and salinity into the bay. These phenomena start the spring when the water mass is stable and become stronger in the summer when the surface cold water develops over a 10-day period. Consequently, tidal currents have little influence in the bay; rather, these vertical and horizontal circulation currents play an important role in the transport of the pollutant load from the inner bay to the open sea.

• Journal of the Korean earth science society
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• v.22 no.1
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• pp.47-64
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• 2001

Water mass classification was conducted using the data of 1985 and 1986 in the East China Sea and the Korea Strait. Kuroshio water (type K) and mixed water (type I) were broadly distributed at 50 m depth in winter and spring, and mixed waters (type I to IV) were distributed in summer and autumn. At 100 m depth of the East China Sea, and mixed water (type I) was broadly distributed in winter and spring, and mixed waters (type I to III) were in summer, and type I was in autumn. Water mass in summer is the most influenced from the Chinese coastal water. In the Korea Strait, the Kuroshio water (type K) was the main water mass in winter and spring, and mixed waters (type I to IV) were in summer and autumn. If temperatures are corrected to remove the cooling effect from the atmosphere, the Kuroshiowater region was diminished, however the mixed water region was expanded in winter and spring. This shows that although the Kuroshio water appears to be a main water mass of the East China Sea and the Korea Strait in winter andspring, in reality the mixed water (type I) which is slightly changed from the Kuroshio water (type K) widely distributed. The tongue-shaped distribution of low density surface water indicates that the water mixed with the Chinese coastal water flows to the Korea Strait and the Okinawa in summer.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.6 no.1
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• pp.40-48
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• 2001

The vertical distributions of temperature, salinity, dissolved oxygen, nutrients, chlorophyll, and primary production were investigated within the top 200m water depth in the south Pacific Ocean in February,2000. The study area ($24^{\circ}-41^{\circ}S,\;81^{\circ}-168^{\circ}W$) can be hydrologically divided into two regions. Upwelling was actively occurring in the eastern region of the $110^{\circ}S$ line, meanwhile it was not active in the western region. Accordingly, chemical properties in the surface waters were different between the two regions; nitrate+nitrite and phosphate concentrations were much higher in the eastern region than in the western region due to the active upwelling, but silicate concentration was higher in the western region. Among the nutrients, the major element influencing primary production was also different between the two regions; silicon would be a major element influencing primary production in the eastern region, but nitrogen may act as a major element for primary production in the western region. Primary production showed similar values in the two regions in spite of the large differences of nutrient concentrations in the surface waters, but the total chlorophyll integrated within the 200 m water depth was almost twice as much as in the western region than that in the eastern legion.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.5 no.1
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• pp.47-58
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• 2000

Geographical distribution of salps was elucidated in the South Sea of Korea with focusing on the April and June, 1997 when swarm of salps occurred. We also discussed on its distributional pattern in relation to environment conditions and its impact on marine ecosystem with emphasizing on trophodynamics. Salps were abundantly distributed in the south-eastern area of Cheju Island where is closely associated with the Tsushima Warm Current. In April and June, 1997, surface water temperature was $2{\sim}5^{\circ}C$ higher than the average over 1961-1998, while surface water salinity was lower. Chlorophyll-a concentration, density of copepods and catches of mackerel sharply decreased in April and June, 1997. These results suggest that the swarm of salps was due to not only transportation by strong Tsushima Warm Current but also supply of abundant foods. Low densities of copepods may be related to the presence of swarm of salps because of food competition between them. The fact that the catches of mackerel were very low in April and May, 1997 suggests that the trophodynamics between salps and copepods also influence the fish resources.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.2
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• pp.85-94
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• 2001

The vertical distribution and activity patterns of fishes during the evening and morning transitions were investigated acoustically and by pelagic trawling on October 2-10, 1997 in the Korean Eastern Sea. The acoustic data were collected from four stations with a scientific echo sounder operating at a frequency of 38 kHz, and the echogram was used to analyze the diel vertical migration of fish. Biological sampling was accomplished by pelagic trawling to identify fish species recorded on the echograms, and the species and length compositions were investigated. Vertical profiles of water temperature, salinity at the trawl station were taken with a CTD system and were related to the diel movement and the depth distribution of fish. During the day, one group of fish mainly distributed above the depth layer of 50 m, the other group was at deeper water, approximately 250 m, but began to migrate toward the surface before sunset with a time difference. During the night, they were dispersed between the surface and the depth of 125 m. Just prior to sunrise, the scattering layer was divided with 2 groups and began to migrate downwards, respectively. Several trials of pelagic trawling for scattering layers suggest that the most dominant scatterer in the survey area of this study was Japanese flying squid, Todarodes pacificus..

• Korean Journal of Environmental Biology
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• v.25 no.4
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• pp.303-312
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• 2007

In order to investigate the dynamics of phytoplankton standing crops affecting by environmental factors, biological and environmental factors, this study was examined in the marine ranching ground of Tongyeong coastal waters from 2000 to 2007. During the study, mean water temperature and salinity were 16.7$^{\circ}C$ and 32.9 psu, respectively. pH, DO and SS varied from 7.81$\sim$8.09, 3.02$\sim$8.97 mg $L^{-1}$ and 2.7$\sim$32.2 mg $L^{-1}$, respectively. Mean concentrations of dissolved inorganic nitrogen, phosphate and silicate were 21.75 ${\mu}M$, 0.90 ${\mu}M$ and 14.38 ${\mu}M$, respectively. Chlorophyll a concentrations varied from 0.02 ${\mu}g$ $L^{-1}$ to 25.29 ${\mu}g$ $L^{-1}$ with mean a value of 2.0 ${\mu}g$ $L^{-1}$. These factors did show significant differences on each layer and season, while did not show on the sampling stations. Phytoplankton standing crops varied from $4.21\times10^3$ cells $L^{-1}$ to $1.44\times10^6$ cells $L^{-1}$ with a mean value of $1.92\times10^5$ cells $L^{-1}$. Especially, variations of phytoplankton standing crops had an unimodal pattern as only bloomed in autumn rather than a bimodal pattern as generally bloomed in spring and autumn. In results of stepwise multiple regression analysis, the coefficient of determination $(R^2)$ for total standing crops was 0.35 and the standing crops were affected by water temperature, salinity, phosphate and silicate. The factors affected were different seasonally; water temperature in spring, salinity in summer, water temperature, salinity and silicate in autumn and water temperature, salinity and suspended solids in winter. Therefore, the results from the statistical analysis showed that the environmental factors influencing on the variations of the phytoplankton standing crops were predominantly water temperature and salinity.

• Journal of the Korean Society of Marine Environment & Safety
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• v.16 no.4
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• pp.321-337
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• 2010

Long-term trends and distribution patterns of water quality were investigated in the Mokpo coastal areas of the Yellow Sea, Korea from 1979 to 2009. Water samples were collected at 5 stations and physicochemical parameters were analyzed including water temperature, salinity, suspended solids (SS), chemical oxygen demand (COD), dissolved oxygen (DO) and nutrients. Spatial distribution patterns of temperature, pH and DO were not clear among stations but the seasonal variations were distinct except ammonium. The trend analysis by principal component analysis (PCA) during 30 years revealed the significant variations in water quality in the study area. Spatial water qualities were discriminated into 3 clusters by PCA; station cluster 1, 2~4, and 5. Annual water qualities were clearly discriminated into 4 surface water clusters and 2 bottom water clusters by PCA. By this multi-variate analysis, the annual trends were summarized as the followings; water temperature, pH and COD tended to increase from late 1980's, salinity to decrease, phosphate to increase from 1994 and dissolved inorganic nitrogen to increase, due to the input of fresh water same as shown in Kyoungin coastal area, Asan coastal area, Choensoo bay and Gunsan coastal area.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.5 no.3
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• pp.224-232
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• 2000

Inorganic nutrient concentrations in relation to springtime physical parameters of the Yellow Sea were investigated during April 1996. Three major water masses, i.e., the Yellow Sea Warm Current Water (YSWC), Coastal Current Water (CCW) and Changjiang River Diluted Water (CRDW), prevailed in the study area. Water masses were vertically wel1 mixed throughout the study area, and nutrients were supplied adequately from bottom to surface layer. As result of ample nutrients supplied by vertical mixing together with progressed daylight condition, springtime phytoplankton blooms were observed, which was responsible for the depletion of inorganic nutrients in surface water column. Low nutrients concentration in bottom water of the central Yellow Sea (Stn. D9; nitrate: <2 ${\mu}$M, phosphate: <0.3 ${\mu}$) was associated with the entrance of YSWC which is characterized by high temperature and salinity. Influenced by runoff and vertical tidal mixing, CCW with high nutrient concentrations probably associated with China and Korea coastal waters with high nutrients concentration. For the local scale of inorganic nutrient distribution, nutrient transfers from coast to central areas were limited due to restriction imposed by tidal fronts (Stn. D6) and thus affected the horizontal nutrient profiles. Relatively high phytoplankton biomass was observed in the tidal front (Chl-${\alpha}$=12.38 ${\mu}$gL$^{-1}$) during the study period. Overall, the springtime nutrient distribution patterns in the Yellow Sea appeared to be affected by: (1) Large-scale influx of YSWC with low nutrient concentrations and CCW with high nutrient concentrations influenced by Korea and China coastal waters; (2) vertical mixing of water mass and phytoplankton distribution; and (3) local-scale tidal front as well as phytoplankton blooms alongthe tidal front.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.3
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• pp.393-407
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• 1997

A survey of biological and chemical characteristics in the middle-northern East Sea of Korea was carried out at 28 stations in October, 1995 on board R/V Tam-Yang. On the basis of the vertical profiles of temperature, salinity and dissolved oxygen, water masses in the study area were divided into 5 major groups; (1) Low Saline Surface Water (LSSW), (2) Tsushima Surface Water (TSW), (3) Tsushima Middle Water (TMW), (4) North Korean Cold Water (NKCW), (5) last Sea Porper Water (ESPW). Other 4 mixed water masses were also observed. It is highly possible that the LSSW which occured at depths of $0\~30m$ in the most southern part of the study area is originated from the Yangtze River (Kiang) of China due to very low salinity $(<32.0\%_{\circ})$ relatively high concentration of dissolved silicate and no sources of freshwater input into that area. Oxygen maximum layer in the vertical profile was located near surface at northern cold waters and became deeper at the warm southern area. Oxygen minimum layer af depths $50\~100m$, which is TMW, were found in only southern area. In the vortical profiles of nutrients, the concentrations were very low in the surface layer and increased drammatically near the thermocline. The highest concentration occurred in the ESPW. The relatively low value of Si/P ratio in the ESPW (13.63) compared to other reports in the East Sea was due to continuous increase of P with depth as well as Si. The N : P ratio was about 6.92, showing that nitrogenous nutrient is the limiting factor for phytoplankton growth. The exponential relationship between Si and P, compared to the linear relationship between N and P, indicates that nitrate and phosphate have approximately the same regenerative pattern, but silicate has delayed regenerative pattern.

• Korean Journal of Ichthyology
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• v.2 no.1
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• pp.36-46
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• 1990

Samples were obtained with a set net during 7 months between March and October in 1987 off the coast of Hwasun, southern part of Cheju Island. Most of organisms, representing 36 species, were less than 20cm(96%) in length, and 30g(74%) in weight. The four most abundant species were jack mackerel, Trachurus japonicus ; squid, Todarodes pacificus ; mackerel, Scomber japonicus ; and Apogon semilineatus, which comprised about 89% of the total individuals and about 70% of the total weight. Diversity index, the number of species and information index for individual were high in early spring, even though biomass was not abundant. On the other hand, diversity index and information index for individual were relatively high in August in spite of low occurrence of the species number. A cluster analysis of 24 species which appeared more than twice during the 7 samplings were illustrated from the similarity matrix. All of the 24species were grouped at the 0.14 similarity level. They were divided into four groups at 0.50 level.