• Journal of the Korean Society of Marine Environment & Safety
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• v.16 no.2
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• pp.141-151
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• 2010

Harmful algal blooms (HABs), commonly known as red tides, are aquatic phenomena caused by the rapid growth and accumulation of certain microalgae, which can lead to marked discoloration of surface waters, and severe impacts on public health, commerce, and the environment. In South Korea, the red tides have been a serious and recurrent problem, especially along the south coast. Plenty of yellow loess was used to control an outbreak of the red tides for 15 years from 1996 until now. Yellow loess was almost sprayed in the vicinity of a large fish farming industry. In this research, the distribution characteristics and density distribution of zooplankton were investigated in autumn (Oct. 2008) and spring (Apr. 2009) using volume backscattering strength (SV) calculated by the zooplankton collected with north pacific standard (NORPAC) net and the echo intensity measured with ADCP at stations on the study area in the spraying ocean of yellow loess (SOYL), and the non-spraying ocean of yellow ocean (NOYL) by the red tide generating every year. The species number and the individuals per unit volume of the zooplankton collected in NOYL was high and it which was collected in SOYL was low. As a result of comparing the volume backscattering strength ($SV_c$) calculated by species and length of the zooplankton collected with NORPAC net with the volume backscattering strength ($SV_m$) calculated by the echo intensity measured with ADCP at stations on the study area, although $SV_c$ and $SV_m$ of NOYL were generally in agreement, $SV_m$ of SOYL was higher than $SV_c$ 4.3dB, i.e. ADCP is greatly influenced by suspended solid in SOYL. The horizontal distribution map of $SV_m$ at the study area in autumn (Oct. 2008) and spring (Apr. 2009) was drawn. $SV_m$ of SOYL is higher than NOYL and autumn is higher than spring. $SV_m$ can suppress the overestimate or underestimate of $SV_c$.

• Korean Journal of Ecology and Environment
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• v.47 no.4
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• pp.247-257
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• 2014

The construction of eight large weirs in the Nakdong River, Korea, caused a decrease in the water flow velocity and several physical changes to the water environment. Here, changes in phyto- and zooplankton communities and water quality in the areas near the eight weirs were investigated from 2011 to 2013, and relationships between phytoplankton abundances and environmental factors were analyzed. Special emphasis was given to the succession patterns in algal abundance based on temperature fluctuations. At the eight weirs, 24 dominant species were found. The most abundant phytoplankton species was Stephanodiscus sp. (39.4% of dominant frequency). Cyanobacteria of the genus Microcystis dominated during the summer, with an dominant frequency of 8.5% and cell abundance ratio of 36.6%. Significant correlations were observed between temperature and abundance of eight of the main dominant species; seven species showed positive correlations with temperature. Stephanodiscus sp., however, showed a negative correlation with temperature (r=-0.26, p<0.01). In addition, this species showed a significant negative correlation with the dominant algal species-Aulacoseira granulata and Aphanizomenon flos-aquae, with the zooplankton Copepoda and with Cladocera. On the contrary, seven other dominant species of algae showed significant positive correlations with zooplankton. Thus, we showed that the seasonal succession of plankton communities in the Nakdong River was related to the water temperature changes.

• Korean Journal of Environmental Biology
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• v.26 no.4
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• pp.392-401
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• 2008

The vertical changes (upper layer: 0$\sim$0.5 m, middle layer: 4$\sim$5 m and lower layer: 8$\sim$10 m) of the limnological variables, zooplankton dynamics and community filtration rate on the phytoplankton were evaluated monthly intervals from November 2004 to June 2007 at the artificiallake (Okjeong Lake). During the study, the annual mean of water temperatures were 15.2$\pm$7.8$^{\circ}C$ (upper layer), 14.5$\pm$7.4$^{\circ}C$ (middle layer) and 13.0$\pm$6.2$^{\circ}C$ (lower layer), respectively (n=30). The vertical variations of most limnological parameters (DO, pH, conductivity and turbidity) were fairly similar, except for chl.-${\alpha}$ concentration. Annual mean of chl.-${\alpha}$ concentration was highest at the upper layer (21.4 ${\mu}g$ L$^{-1}$), while annual means of concentrations were low at the middle layer and lower layer (4.3 ${\mu}g$ L$^{-1}$ and 3.5 ${\mu}g$ L$^{-1}$, respectively). Annual mean of Secchi depth was 261 cm (n=30). A total 45 species of zooplankton were identified (28 rotifers, 12 cladocerans and 5 copepods) during the study. The mean abundance of rotifers was highest (124$\pm$232 ind. L$^{-1}$, n =90) and that of cladocerans and copepods were relatively low (22$\pm$56 ind. L$^{-1}$ and 13$\pm$30 ind. L$^{-1}$) in the whole layer. Total zooplankton abundance increased from late spring to summer, and then declined and remained low throughout the winter. The annual mean of total zooplankton filtration rate for phytoplankton at the lower layer was much higher than that of both layers (upper layer: 44.4$\pm$107.8, middle layer: 95.1$\pm$436.4 and lower layer: 158.2$\pm$436.4 mL L$^{-1}$ day$^{-1}$). Among the major zooplankton community, relative community filtration rate (RCFR, %) of copepods for phytoplankton (50.2$\sim$54.8%) was much higher than that of cladocerans (27.7$\sim$36.3%) and rotifers (8$\sim$17.6%). The seasonal variation of RCFRs of major zooplankton community was observed. The RCFRs of rotifers were high in winter (44.6%, n=9), while the RCFRs of cladocerans were high in summer (58.0%, n=7). In spring and fall, the RCFRs of copepods were high in the whole layer (spring: 67.4%, n=9; fall: 74.4%, n=5).

• KCID journal
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• v.18 no.1
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• pp.33-43
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• 2011

Jundae reservoir has basin area of 234ha, average depth of 3.77m and total storage of $619{\times}10^3m^3$, and is located in Dangin-gun, Chungcheongnam-do. The water quality of Jundae reservoir exceeded the IV grade of water quality standard as available for irrigation water in COD, TN, TP, Chl-a. COD and Chl-a were higher in spring season, because the algal bloom by phytoplankton increased. And the algal blooms in October by inflow non-point pollution during summer rainy season. The most dominant zooplankton was rotifers during study period at all stations. Dominant species were Keratella cochlearis, Polyarthra spp., and Trichocerca spp. We successfully established 2 isolated clone cultures as predator. One is Rotifer, Euchlanis sp. and another is cladocerans, Bosmina sp. To test the removal rate of 2 cultures against Microcystis aeruginosa, we inoculated Euchlanis sp. and Bosmina sp. separately when the abundance reached at $1.0{\times}10^6$cells/ml. Euchlanis sp. removed M. aeruginosa around 98.9% and Bosmina sp. removed it around 98.4%. They are useful grazers for controling algae blooms, Euchlanis sp. and Bosmina sp. feeding on M. aeruginosa highly.

• Fisheries and Aquatic Sciences
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• v.26 no.12
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• pp.689-697
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• 2023

This study used a multi-frequency acoustic method to assess the density and spatial distribution of dominant zooplankton, euphausiids and copepods, which are representative species of the zooplankton immigrating the sea around Republic of Korea. Acoustic surveys were carried out in the East Sea and South Sea from June 16 to 29, 2017, using the research vessel Tamgu 20th from the National Institute of Fisheries Science. From the results of the acoustic survey, the distribution of euphausiids was relatively higher in the East Sea than in the South Sea. Additionally, although the distribution of copepods was low in all areas, they were abundant in certain areas in the East Sea and the southern area of the Jeju Sea. Euphausiid and copepod density was estimated to be 1.2 g/m² (CV = 19.1%) and 2.8 g/m² (CV = 23.5%), respectively.

• Journal of Environmental Health Sciences
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• v.7 no.2
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• pp.97-105
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• 1981

Water Pollution of Gwangju Stream was examined for four months from 22 March 1981 to 7 June, 1981. For checking the water pollution, 6 sampling positions were selected 5 from main stream. We assumed that the water pollution of Gwangju stream was due to the organic materials, which came from the domestic sewage. The apparatus for this test were pH meter (Orion model 301), Dissolved Oxygen & Temperature meter(Delta model 1010). The results we obtained are as follows: 1. The average range for mid-stream(sp. 3, 4) was 3. 10~2.73ppm of Dissolved Oxygen(DO), 80.23~102.95ppm of Biochemical Oxygen Demand (BOD), 195. 10~165.90ppm of Suspended Solid (SS), 6.6~6.7 of pH. 2. The plankton identification in this survey period showed Cyanophyceae is 4 genera 5 species, Bacillariophycea 11 genera 14 species, Chlorophyceae 8 genera 15 species and Zooplankton 6 genera 7 species: total 29 genera 41 species. 3. To appear dominant plankton in polluted water, there were Paramecium, Euglena and Oscillatoria. 4. The results of biological water analysis were as follows: st. 1 was B-mesosaprobic to oligosaprobic, but st. 4 and st. 5 at stream in the midtown area seemed to be polysaprobic.

• ALGAE
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• v.20 no.2
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• pp.133-140
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• 2005

Daily variation of phytoplankton community and environmental parameters were investigated at the lower Nakdong River (Mulgum) from January 2002 to December 2003 to investigate the dynamics of a phytoplankton community in detail. The daily results of water quality in this investigation showed pH (8.1 $\pm$ 0.7), DO (10.3 $\pm$ 2.7 $mg{\cdot}l^{-1}$), water temp. (18.8 $\pm$ 7.4°C), BOD (2.4 $\pm$ 1.0 $mg{\cdot}l^{-1}$), COD (5.3 $\pm$ 1.2 $mg{\cdot}l^{-1}$) and chl. a (43.5 $\pm$ 35.1 mg ${\cdot}m^{-3}$). The results of nutrient factors were the following: TN (3.1 $\pm$ 0.8 $mg{\cdot}l^{-1}$), NO3-N (2.5 $\pm$ 0.5 $mg{\cdot}l^{-1}$), TP (90 $\pm$ 48 ${\mu}g\;{\cdot}\;l^{-1}$), PO4-P (43 $\pm$ 30 ${\mu}g\;{\cdot}\;l^{-1}$). Dominant phytoplankton species during the study period were diatom (Stephanodiscus hantzschii, Aulacoseira granulata var. angustissima and A. italica) and cyanobacteria (Microcystis aeruginosa, Aphanizomenon flos-aquae). The small centric diatom, Stephanodiscus hantzschii, was repeatedly dominant from late fall to the following spring (mean and maximum cell density, 2.3 × 103 $\pm$ 3.8 × 103, 4.5 × 105 cells $ml^{-1}$, respectively). Pinnate diatom, Aulacoseira granulata var. angustissima and A. italica, were frequently observed all season except January to March. Cyanobacteria, Microcystis aeruginosa and Aphanizomenon flos-aquae, proliferated in summer of 2002 except in 2003 due to heavy precipitation. The dominant zooplankton species (March-early May) was rotifer (Brachionus, Keratella, Polyarthra) and cladocerans (Diaphanosoma). The daily observed dynamics of the phytoplankton community in the lower Nakdong River in this study may play an important role in increasing the detailed resolution of limnological information and serving as ecological data for future studies.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.16 no.4
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• pp.316-329
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• 1983

The formation and structure of the shelf front in the eastern part of the Yellow Sea are studied on the basis of oceanographic data collected in August, 1982 and February, 1983. This paper also describes the distribution of planktonic organisms of the shelf front. In summer the shelf front is formed in the area ($126^{\circ}02^'E-126^{\circ}05^'E$) ca. 20 miles from the shore at the depths of 15-25 m. in winter, however, no distinct shelf front is formed. Based on the cluster analysis of surface phytoplankton the species composition shaws a discontinuous pattern in the vicinity of the shelf front in summer, 1982. A similar trend is observed in distribution of some copepod species in winter, l983.

• Journal of Korean Society on Water Environment
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• v.31 no.6
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• pp.665-679
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• 2015

Yearly mean temperature in the 29 lakes surveyed ranges from 12.6 (Suncheon) to 13.9℃ (Mokpo), the lowest in −2.7℃ (January) and the highest in 25.9℃ (July). Monthly mean the amount of rainfall recorded the highest of 336.7 mm in August and the lowest with 4.9 mm in January. A total of 424 species of phytoplankton were identified. They were 157 Chlorophyceae, 161 Bacillariophyceae, 39 Cyanophyceae, and 67 other algal taxa. The phytoplankton diversity were low in stream type reservoirs such as Guemho, Youngsan and Youngam. The population density of phytoplankton ranged from 19 to 53,161 cells/ml. Annual mean of total zooplankton abundance in 45 sites was 369±827 ind./L (n=180). Rotifers were the most common taxa and their relative abundance was high (65~77%). The benthic microinvertebrate fauna of 10 reservoirs of Jeonnam province were 71 species of 61 genera of 44 families of 16 orders of 7 classes of 4 phyla. Aquatic insects of Phylum Arthropoda were 50 species of 44 genera of 28 families of 6 orders. The number of individuals was 6,132. Diptera was highiest (41.3%), and Ephemeroptera (31.0%), Trichoptera (17.5%), Anellida (3.8%), Mollusca (3.3%), Crustacea (0.4%). Large hydrophytes were identified 32 taxa, 2 varieties 30 species 26 genera and 20 families. Especially, Jijung and Juam lakes require management such as physical remove of this ecosystem disturbance field plants. Fishes were identified total 44 taxa, such as 25 Cyprinidae (56.8%), 8 Cobitidae (17.0%), 3 Gobiidae (6.4%), 2 Bagridae (4.3%), 2 Osmeridae (4.3%), 2 Odontobutidae (4.3%), 2 Centrachidae (4.3%), 1 Siluridae (2.1%), and 1 Centropomidae (2.1%). A pale chub was dominant species (18.9%).

• 한국해양학회지
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• v.25 no.2
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• pp.49-61
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• 1990

The family Corycaeidae in the neighbouring seas of Korea was taxonomically studied based on the zooplankton samples collected in August, 1986. In this study, nine species belonging to two genera and three subgenera of the Corycaeidae were identified and described with illustrations; Corycaeus (Corycaeus) speciosus, G.(C.) crassiusculus, C. (Ditrichocorycaeus) affinis, C.(D.) andrewsi, C.(D.) erythraeus, C.(Onychocorycaeus) pacificus, c.(O.) catus, C.(O.) agilis, and Farranula gibbula. The distribution patterns of these species showed that C.(D.) affinis appeared to be and indicator species of the coastal waters, and C.(C.) speciosus, C.(C.) crassiusculus, c.(O.) catus, C.(D.) andrewsi, and Farranula gibbula appeared to be indicator species of the warm-oceanic waters.