• Korean Journal of Ecology and Environment
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• v.37 no.1 s.106
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• pp.12-25
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• 2004

Physicochemical parameters, plankton biomass, and sediment were surveyed from 1998 to 2000 at two months interval in a eutrophic coastal lagoon(Lake Hwajinpo, Korea). The lake is separated from the sea by a narrow sand dune. Littoral zone is well vegetated with leafing-leaved aquatic plants. The lake basin is divided into two subbasins by a shallow sill. It has intrusion of seawater by permeation and stormy waves. Stable chemoclines are formed by salinity difference at 1m depth all the year round. DO was often very low (< 1 mg$O_2\;L^{-1}$) at hypolimnion. Temperature inversions were observed in November. Nitrate and ammonium concentrations were very low(< (1.1 mgN $L^{-1}$), even though TN was usually 2.0 ${\sim}$ 3.5 mgN $L^{-1}$. TN/TP was generally lower than the Redfield ratio. Transparency was 0.2 ${\sim}$ 1.7 m, and COD, TP, and TN of sediment were 3.1 ${\sim}$ 40.3 mg$O_2\;g^{-1}$, 0.91 ${\sim}$ 1.39 mgP $g^{-1}$, and 0.34 ${\sim}$ 3.07 mgN $g^{-1}$, respectively. Phytoplankton chlorophyll- a concentrations were mostly over 40 mg $m^{-3}$. Two basins showed different phytoplankton communities with Oscillatoria so., Trachelomonas sp., Schizochlamys gelatinosa, and Anabaena spiroides dominant in South basin, and with Trachelomons sp., Schroederia so., schizochlamys gelatinosa, and Trachelomonas sp. dominant in the North basin. The seasonal succession of phytoplankton was very fast, possibly due to sudden changes in physical conditions, such as wind, turbidity, salinity and light.

• Journal of the Korean Society of Marine Environment & Safety
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• v.15 no.3
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• pp.187-203
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• 2009

This study monitored marine environments in system coastal waters of the South Sea of Korea during the period of 2005-2007 and analyzed the data from environmental parameters and nutrients, which contributed to fluctuate marine environmental characteristics in aquaculture. On the basis of the fluctuation of temperature depending on seasons and sampling sites, too seasons of winter and summer showed a remarkable temperature gap of $5^{\circ}C$ compared with spring and autumn. Salinity in spring and summer approached 9 psu in Morkpo. Most of sampling sites showed COD below 2mg/L, indicating somewhat optimal environmental conditions. T-N and T-P also had desirable horizontal distributions all year round the concentration of SS was higher, but Chi. a was well-distributed horizontally except for Morkpo. Marone environmental parameters of surface water were similar to those of bottome water except for Morkpo. Most of sampling sites showed the ratio of N/P below 16, impling that nitrogen played an important role in growth of phytoplankton as a limiting factor. The relationship between Chi. a and nutrients was positive linear, whereas the relationship between Chi. a and COD were very strong positive. winder, Spring and Summer showed the strong relationship between Chi. a and COD. In the analysis of dendogram based on environmental parameters using SPSS ver. 10.0, the station 7 did not belong to other stations, and kept an independent place. The relationships of waters between Jindo, Wando and Heanam ware close, compared with other waters. Consequently, these regions except for Morkpo into which fresh water is introduced by the dike showed somewhat optimal environmental parameters and nutrients in year, and were assumed to maintain the desirable marine conditions for aquaculture.

• Korean Journal of Environmental Biology
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• v.23 no.2 s.58
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• pp.191-199
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• 2005

The community structure, vertical distribution and harpacticoids composition of the meiofauna community were observed from five stations in Marian Cove, King George Island and one station on the northeastern side of Nelson Island. Sample was taken by a free-fall corer in December 2002. Generally, 11 taxa of meiofauna were found, and meiofauna abundance ranged from 322 to 1575 indiv. $10cm^{-2}$ (mean 781 indiv. $10cm^{-2}$). Nematodes were the most dominant group, making up $89\%$ of total meiofauna, followed by harpacticoids $(6.8\%)$. Benthic harpacticoids appeared 19 species of nine families at all the stations, and most various taxa appeared at station B (13 species of seven families). For vertical distribution, more than $70\%$ of meiofauna was concentrated in the upper $0\~2cm$ sediment layers, and the density abruptly decreased with depth in all the stations. Total biomass of meiofauna varied between 41 and $360{\mu}gC\;10cm^{-2}$, and overall mean biomass was $205{\mu}gC\;10cm^{-2}$. Also nematodes had the highest percentage of total maiofauna biomass $(62.4\%)$. The analysis results of Canonical Correspondence Analysis between meiofauna community and sediment grain size showed that polychaets, oligochaets and cumaceans were influenced by silt&cray, and sand, granule and pebble had a influence on harpacticoids, kinorhynchs and ostracods respectively. But nematodes were not affected by sediment grain size.

• 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.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.6
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• pp.570-581
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• 2013

To improve productivity of aquaculture animals with management of culturing grounds, survey of mariculture management area in Ongjin-gun about water quality and sedimentary environment had been conducted on June, August and November in 2011. Water temperature in surface and bottom waters ranged from 9.49 to $24.14^{\circ}C$. Salinity and dissolved oxygen concentrations were in the range of 23.19~31.49 and 5.48~9.36 mg/L, respectively, depending on the variation of water temperature. The average concentration of COD was 1.57 mg/L and the concentrations of DIN and DIP showed entirely low level. As the result of grain size analysis, sand(56.66 %) and silt(34.60 %) were predominated. The Mz of sediment showed a variation of 2.59 to $6.62{\O}$ and sorting appeared to be poorly sorted. The concentrations of COD and IL in surface sediment ranged from 1.00 to $11.03mg/g{\cdot}dry$ and 0.72 to 5.29 %, respectively, which showed relatively good positive correlations. On the environmental assessment of trace metals in surface sediment, geoaccumulation index ($I_{geo}$) class indicated that sediments were not contaminated by most of metallic elements except Cr and As. Our result implies that this study area showed good water quality and sediments were not polluted by organic matters and metallic elements.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.2
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• pp.226-244
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• 1998

The relationship between the transport of eggs and larvae of Anchovy (Engraulis japonica) and the oceanic condition in the southern sea of Korea was examined on August and November 1996. In summer (August), when the Tsushima Warm Current is strong near to the coast, the warm waters such as warm streamers from the Tsushima Warm Current intrude into the coastal area, and cyclonic circulations are formed. The warm water intrusions also generate wakes around Komun Island, Sori Island and Koje Island. In the coastal area where the warm water intrusions occur, the nutrients, dissolved oxygen, suspended solid and chlorophyll are concentrated in probably relation to the upwelling concerned with this warm streamer and/or the wakes. Anchovy eggs and larvae are transported to the coastal area by the cyclonic circulations. The hatching and growth of anchovy larvae are increased because of high primary production in the cyclonic circulations. However, as the amount of Copepods which are a main food for anchovy larvae decrease in the coastal area, anchovy larvae seem to move to the Isushima Warm Water area for seeking a prey. In autumn (November), the Tsushima Warm Current is far away from the coast. In this season the warm water intrusions almost disappear, and the small scaled frontal eddies are formed between the coastal water and the Tsushima Warm Water. As the surface water moves towards offshore, few anchovy eggs and larvae were sampled in the survey area. Chemical and biological substances are concentrated in the leftdown sides of the small scaled frontal eddies because of eddy formation.

• The Korean Journal of Malacology
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• v.28 no.3
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• pp.197-213
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• 2012

This study was performed to know the community structure of macrobenthos and environmental factors at each 16 stations in the subtidal sandy bottoms of the southern coastal water of Jeju Island from July to November, 2011. Mean temperature and mean salinity were $20.2-22.7^{\circ}C$, 33.7-34.9 psu which shows stable water messes. Chlorophyll a concentrations of phytoplankton ranged from 0.71 to 1.71 mg/L (1.11 mg/L), showing higher July than September and November with a blooming in summer. The mean concentration values (the ranges in parentheses) of nitrate, phosphate, and silicate are 0.029-0.206 mg/L (0.101 mg/L), 0.001-0.027 mg/L (0.007 mg/L), 0.024-0.682 mg/L (0.454 mg/L), respectively. However, the values higher coastal zone due to influxes from the land. A total of 37 species was identified. of these mollusca comprised 29 secies (78.4%); Echinodermata 5 (13.5%); Arthropoda 3 (8.1%). density and biomass were estimated to be 550 ind./$m^2$ and 20,951.8 gwwt/$m^2$, respectively. Mollusca were the most dominant faunal group in terms of abundance (481 ind./$m^2$) and number of species as well, whereas bivalves were predominant in biomass (16,647.6 gwwt/$m^2$). The dominant species were Vasticardium burchardi, Oblimopa japonica, Mactar achatina, Bornatemishistrioiw akawai, Paphia vernicosa, Amusium japonicum, Glycymeris albolineata, Astriclypeus manni in 15-30 m. The seasonal variation appeared as distinct, Mollusca of individual and biomass. When summer was make a slow increase, after the highest decrease in autumn. The abundance of macrobenthic invertebrates showed significant correlation with environmental factors (Chlorophyll a, DIN, $SiO_2$, Fine sand, Very fine sand) in almost all sampling depths. The biodiversity, evenness richness index were appeared 1.56-2.50 (H'), 0.49-0.80 (E'), 4.12-4.67 (R) in each stations. The dominace index were appeared Highest in November and lowest in September.

• Journal of Aquaculture
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• v.11 no.3
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• pp.391-400
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• 1998

This study was performed to investigate the effects of environmental parameters on the growth of Pacific oyster, Crassostrea gigas at old suspended culturing grounds of Korsung Bay and newly deveoped bottom, culturing grounds of Haenam region located in southern coast of Korea. The Kosung Bay was semiclosed and water exchange occurred through the small mouth and the current speed was very slow as the value of below 0.5kn. Haenam was opened and littoral zone. Current speed of the surroundings of this Bay about to 5.0knand transparency was low with the mean depth of 1.2m by the resuspension of the sediments. Water temperature and salinity regimes were suitable for oysters at those sites, however the mean value of those parameters and seasonal fluctuations was high at Kosung. The mean concentration of dissolved oxygen in survey area was above $5.0mg/\ell$. In Kosung, however, it was decreasing in June and showed the minimum with the concentration of $4.0mg/\ell$ in August at the bottom layer and recovered in September. Eutrophication parameters such as COD were 1.44 mg/l at this location. This mean value was higher than that of the Haenam Bay's $0.96mg/\ell$. The men value of chlorophyll-$\alpha$ at Haenam was two times higher than the other sites. Growth of shell height and meat weight of oysters at Kosung Bay were higher and the fatness was lower compared to thost of Haenam. As a result, absolute growth of oysters was high at Kosung and allometric growth, such as fatness, was good at Haenam. Low water temperature and frequent exposure of oysters to the air during ebb tide may retard the shell growth. On the other hand, relatively high food availability was profitable for the fatness at haenam site.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.7 no.3
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• pp.129-139
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• 2002

We investigated the outbreak of red tides dominated by harmful dinoflagellates from August to November 1999 in the coastal waters off the southern Saemankeum areas where a huge red tide dominated by Cochlodinium polykrikoides had been first observed in 1998. We took water samples from 2~5 depths of 4 stations (with 3-4 additional stations during red tides) in this study period and then measured the abundance of phytoplankton, water temperature, salinity, and the concentrations of nutrients. In the study period harmful dinoflagellates Alexandrium tamarense, C. polykrikoides, Gymnodnium catenatum, Gyrodinium aureolum, Gymnodnium impudicum were present, and of these G. aureolum and C. polykrikoides formed red tide patches on September 16 and October 18, respectively. The date of the outbreak of red tide dominated by C. polykrikoides in the study area was approximately 50 days later than that off the Kohung areas in 1997 and the surface water temperature when the red tides outbroke in the former area was 6$^{\circ}C$ lower than that fur the latter area. The maximum abundance of C. polykrikoides on September 16, October 7 and 18 were 5, 14, and 463 cells $m\ell$$^{-1}$ , respectively. The growth rate of C. polykrikoides, isolated from the study area, was 0.3~0.4 d$^{-1}$ at 20~$25^{\circ}C$, which enable this species to reach the maximum concentration without being transported from the adjacent waters containing already made red tide patches. The outbreaks of red tides dominated by C. polykrikoides in the study area and off Kohung have occurred when and/or where the concentrations of diatoms were low. This evidence suggests that the outbreak of red tides dominated by C. polykrikoides is adversely affected by the high diatom concentrations or the conditions favorable for the growth of diatoms.

• Korean Journal of Ecology and Environment
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• v.38 no.4 s.114
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• pp.461-474
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• 2005

Physicochemical parameters, plankton community structure, and sediment were surveyed from 1988 to 2002, at two months interval, in a eutrophic coastal lagoon (Lake Songji, Korea). The lake basin is separated from the sea by a narrow sand dune, and a shallow sill divides the lake basin into two sub-basins. The stable stratifications and chemoclines are maintained all through the year at 1-2 m depth. DO was often very low (<1 $mgO_2\;{\cdot}\;L^{-1}$) in the monimolimnion. Secchi disc transparency was in the range of 0.5-2.7 m. TP, TN, and Chl. a concentration in the mixolimnion were 0.015-0.396 $mgP\;{\cdot}\;L^{-1}$), 0.223-3.521 $mgN\;{\cdot}\;L^{-1}$, and 0.5-129.8 mg ${\cdot}\;m^{-3}$, respectively. TSI was in the eutrophic range of 54 to 62. Sediment was composed of silt and coarse silt. COD, TP, and TN content of the sediment were 51.4-116.9 $mgO_2\;{\cdot}\;gdw^{-1}$, 0.04-1.46 $mgP\;{\cdot}\;gdw^{-1}$ and, 0.12-1.03 $mgN\;{\cdot}\;gdw^{-1}$, respectively. The 49 phytoplankton species were identified. The maximum phytoplankton abundance obscured the lake in September 2001 (max. density: 23,350 cells ${\cdot}\;mL^{-1}$. The Chlorophyte Schroederia judayi was dominant species in summer (max. density: 20,417 cells ${\cdot}\;mL^{-1}$). The lake showed unique limnological features of a brackish lagoon in respect to biological community, chemical characteristics, and physical phenomena.