• Korean Journal of Environmental Biology
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• v.28 no.4
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• pp.202-211
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• 2010

The variations of physico-chemical factors and the species compositions of phytoplanktons were investigated to analyze the marine ecosystem at the depths during summer in the coast of Dokdo (stations DOK 1-3). The mean values of conductivity (48.9 mS $cm^{-1}$), salinity (32.9 psu) and total suspended solids (57.9 mg $L^{-1}$) were the highest in DOK 1. The biomass (Chl-a) of phytoplanktons was the highest in the surface of DOK 1 (2.61 ${\mu}gL^{-1}$). By the means of physicochemical factors (salinity, turbidity, Chl-a, TN, TP and Si), the water estimated in the coast of Dokdo was more eutrophicated than that in 2008. The phytoplanktons were a total of 42 species in Dokdo, which were composed of 33 species (78.6%) for Bacillariophyceae and 9 species (21.4%) for Dinophyceae. The standing crops of phytoplanktons were the highest ($18{\times}10^3$ cells $L^{-1}$) in the surface of DOK 2 and in the surface of DOK 3, while they were the lowest ($2{\times}10^3$ cells $L^{-1}$) at depth of 40 m of DOK1 and at depth of 30 m of DOK 3. The dominant species of phytoplanktons were Chaetoceros castracanei ($6{\times}10^3$ cells $L^{-1}$) in the surface, Rhizosolenia alata f. gracillima ($3{\times}10^3$ cells $L^{-1}$) at depth of 20 m and Protocentrum compressum ($4{\times}10^3$ cells $L^{-1}$) at the depth of 30 m of DOK 1. At the surface of DOK 2, the dominant species was Bacillaria paxillifer ($6{\times}10^3$ cells $L^{-1}$), while it was Hemiaulus indicus ($12{\times}10^3$ cells $L^{-1}$) at the surface of DOK 3. The DOK 1, which is affected by upwelling, whirlpool and circulation due to the East Korean Warm Current, was the most eutrophicated water body among three stations. The monitoring of marine ecosystem in the coast of Dokdo should be continued to propose the alternatives for water quality and species conservation and to purify the eutrophicated water body due to artificial pollutants as well as natural effectors by the global warming, the climatic change, etc.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.3
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• pp.359-367
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• 1999

For investigating the activities of algicidal bacteria, the variations of algicidal bacterial population and chlorophyll-a were checked weekly in Chindong Bay, Korea from May to July, 1998. For identifying their killing characteristics, three strains were selected from the isolated algicidal bacteria. The density of algicidal bacteria kept changing in the range of $6.0\times10^1$ to $6.4\times10^5$ cell $\ell^{-1}$. The density flux of algicidal bacteria coincided with that of chlorophyll-a by a week of lag time. Three algicidal bacteria isolated from field strains, H519S5-4, H605S5-15 and H605S5-22, were investigated in nine microalgal species, Heterosigma akashiwo, Chattonella sp. (Raphidlphyceae), Gymnodinium catenatum, Gyrodinium impudicum, Cochlodinium polyklikoides (Dinophyceae), Chaetoceros sp., Coscinodiscus granii, Ditylum brightwellii, Thalassiosira rotula (Bacillariophyceae). Strain H605S5-22 showed a wide algicidal activities over nine microlgae, strain H605S5-15 over H. akashiwo, G. catenatum, T. rotula, Chattonella sp. and strain H519S5-4 over H. akashiwo, Chattonella sp., Chaetoceros sp., G. catenatum. The activities of the three strains were detected by the secretion of algicidal substances. Therefore, it is suggested that the activities of algicidal bacteria have a significant influence over the population dynamics of phytoplankton and get involved with the sharp decrease in red tides in the coastal area.

• Journal of Wetlands Research
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• v.3 no.2
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• pp.143-151
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• 2001

The community of phytoplankton, dominant species and environmental factor were investigated in Motjae-neup from January to September, 1996. A total 45 taxa were identified during the investigation period and composed of 5 classes, 8 orders, 13 families, 24 genera, 37 species, 6 varieties, 2 formation. The most important group was Chlorophyceae with 19(42.2%) taxa, followed by the Bacillariophyceae with 13(28.9%) taxa, Euglenophyceae with 7(15.6%) taxa, Cyanophyceae with 5(11.1%) taxa and Dinophyceae with 1(2.2%) taxon. Frustulia rhomboides, Eunotia lunaris, and Stauroneis anceps were important dominant species at Motjae-neup. The common species of all season are Microsystis aeruginosa, Melosira. varians, Frustulia rhomboides, Pinnularia braunii var. amphicephala, Stauroneis anceps. Ranges of environmental factors were measured : temperature, $3^{\circ}C{\sim}38^{\circ}C$; water temperature, $3.3^{\circ}C{\sim}26.5^{\circ}C$; pH, 5.7~6.38; BOD, $4.3{\sim}19.6mg/{\ell}$; chlorophyll a, $6.9mg/m^3{\sim}25.9mg/m^3$; SS, $26mg/{\ell}{\sim}52mg/{\ell}$; COD, $24{\sim}46mg/{\ell}$; total-N, $0.9538mg/{\ell}{\sim}2.3036mg/{\ell}$; total-P, $0.1057mg/{\ell}{\sim}0.1909mg/{\ell}$; electron conductivity, $25.5{\mu}s/m^3{\sim}2.3036{\mu}s/m^3$.

• Korean Journal of Ecology and Environment
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• v.47 no.4
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• pp.273-281
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• 2014

We conducted the weekly monitoring (December 2012~April 2013) to evaluate the temporal variation and identification of Stephanodiscus spp. that are generally dominant during winter in the Yeongsan River. Phytoplankton species were identified and counted using the optical microscope and scanning electron microscope (SEM). Phytoplankton in the river were grouped into 6 classes (bacillariophyceae, chlorophyceae, cryptophyceae, cyanophyceae, dinophyceae, euglenophyceae), 30 genus and 41 species. Phytoplankton composition showed high abundance of diatoms in winter and Aulacoseira sp., Cyclotella sp. and Stephanodiscus spp. were dominant. Among the species, Stephanodiscus spp. was relatively abundant compared to other diatom species. Stephanodiscus spp. appeared from December 2012 to April 2013 and their abundance peaked in January. Abundance of diatoms especially peaked ($21,080cells\;mL^{-1}$) in January 15, 2013 when Stephanodiscus spp. also bloomed ($20,560cells\;mL^{-1}$). The abundances of Stephanodiscus spp. were gradually decreased from March and reached as low as $60cells\;mL^{-1}$ in April 26. Cyclostephanos (C. invisitatus), Cyclotella (C. meneghiniana), Discostella (D. pseudostelligera, D. woltereckii) and Stephanodiscus (S. hantzschii, S. minutulus, S. parvus) were classified in the circular diatoms. Abundance of S. hantzschii was extremely high compared to S. minutulus and S. parvus.

• 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%).

• Journal of Life Science
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• v.18 no.12
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• pp.1671-1678
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• 2008

We investigated the effect of the turbid water on the phytoplankton community in the 4 sites of Imha reservoir. The turbidity of water was proportional to the concentrations of $SiO_2$-Si. Therefore, as the turbidity of water grow, the concentration of $SiO_2$-Si increased. And the both the turbidity of water and the concentrations of $SiO_2$-Si were increased as the water run deep. The concentration of chlorophyll-a decreased as the depth of water increased. Seventy phytoplankton taxa were identified and the most abundant group was Chlorophyceae consisting of 32 taxa (46%), and Cyanophyceae and Bacillariophyceae consisted of 12 taxa (17%). And Euglenophyceae, Synulophyceae, Cryptophyceae and Dinophyceae consisted of 6 taxa (9%), 4 taxa (6%), 3 taxa (4%) and 1 taxon (1%), respectively in Imha reservoir. The concentrations of phytoplankton were increased according to the turbidity of water because of the high amount of organic nutrition which is presented with turbid water. And especially, the concentrations of nitrogen increased easily because of the weak binding to the soil particle. In conclusion, total nitrogen and $SiO_2$-Si flowed into the Imha reservoir with soil particle, and these inorganic nutritions affect the growth of algae.

• Korean Journal of Ecology and Environment
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• v.42 no.3
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• pp.295-302
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• 2009

This study was conducted to identify the influences of light-to-nutrients ratio on the zooplankton and phytoplankton community. Various experiment conditions such as HL (high-light and without zooplankton), HLZ (high-light and with zooplankton), LL (low-light and without zooplankton), and LLZ (low-light and with zooplankton) were adjusted. Changes in biomass of phytoplankton species with the incubation time showed a similar tendency in the continuous cultures, but the change of species composition in the continuous cultures was detected. Cyanophyeeae (Phormidium sp.) seems to be affected by the existence of zooplankton. Also, the predominant species were Chlorophyceae (Staurastrum spp., S. dorsidentiferum, Coelastrum cambricam, Chlorella sp., Krichnerialla sp.) in a high-light environment and Bacillariophyceae (Melosyra granulata, Synedra acus, Fragilaria crotonensis) in a high-light environment. The estimated mean POC concentration (after twenty days) in a high-light environment was two times higher than that for a low-light environment. P : C ratio of seston component in a low-light environment was higher than that for a high-light environment. Changes in biomass of zooplankton species during the incubation time were higher than that for a high-light environment.

• Journal of Wetlands Research
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• v.14 no.2
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• pp.255-263
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• 2012

The stream has various environments and they are serving as main habitats of aquatic organisms. The distribution of phytoplankton is affected by water environment, especially pH, nitrogen and phosphorus. To reveal the relationship between phytoplankton distribution and water environment, we measured pH, $NO_3{^-}$ and $PO{_4}^{3-}$ concentration, and abundance of phytoplankton at 10 sites in the upper stream of Dorim-cheon. pH value ranged 5.05 to 7.56. $NO_3{^-}$ and $PO{_4}^{3-}$ concentrations ranged 0.4 ~ 4.9ppm and 0.02 ~ 0.99ppm, respectively. A point source of $NO_3{^-}$ was Seoul National University but concentration was not high and dropped to normal range at 400m downstream. $NO_3{^-}/PO{_4}^{3-}$ ratio ranged 28 to 152 except site 4 (0.4) where was affected by $PO{_4}^{3-}$ point source. Water pH, $NO_3{^-}$ and $PO{_4}^{3-}$ concentrations increased with downstream and were related to the input of irrigation water from Han-river between site 5 and 6. Bacillariophyceae alge dominated this stream. Phytoplankton density increased abruptly at downstream of site 5. In general, phytoplankton density did not increase until the $NO_3{^-}$ concentration of 3.5ppm and $PO{_4}^{3-}$ concentration of 0.07ppm. Phytoplankton density was low at sites where $NO_3{^-}/PO{_4}^{3-}$ ratio was larger than 50.

• Korean Journal of Ecology and Environment
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• v.38 no.1 s.110
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• pp.18-29
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• 2005

This study was conducted to understand seasonal dynamics of phyto- and zooplankton communities in a shallow eutrophic reservoir (Shingu reservoir) from November 2002 to February 2004. Cyanophyceae dominated throughout the year, except for spring (March ${\sim}$ May) when Bacillariophyceae (Melosira varians) and Chlorophyceae (Dictyosphaerium puchellum) were dominant. The change of dominant species in Cyanophytes occurred in June and December 2003, and the increase of phytoplankton cell density in July and November was observed when the P loading through two inflows was high. In May, Oscillatoria spp. and Aphanizomenon sp. were dominant, but replaced by Microcystis spp. in the end of May. Dominant Microcystis spp. sustained until December and shifted to Oscillatoria spp. and Aphanizomenon sp. TN/TP ratio ranged from 13 to 46 (Avg. $27{\pm}6$) from June to December when cyanobacteria (Microcystis spp.) dominated. Rotifers such as Keratella cochlearis, Keratella valga, Polyarthra spp., Conochilus unicornis, Pompholyx complanata dominated in average 67.8% of the zooplankton community. Abundance of zooplankton was the highest in June 2003, when Pompholyx complanata (12,388 ind $L^{-1}$) was dominant. In May, the significant increase of Conochilus unicornis biomass ($1,048{\pm}28\;{\mu}g\;C\;L^{-1}$) was observed with distinct improvement of transparency ($Z_{eu}/\;Z_m=\;1.1$). These results suggest that the seasonal variation of phytoplankton communities in this reservoir are to be understood as results of multi-interactive factors such as temperature, light condition and nutrients, and small-sized rotifers as important predator.

• Korean Journal of Ecology and Environment
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• v.50 no.1
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• pp.148-156
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• 2017

In this study, we analyzed the relationship between phytoplankton community and physicochemical factors in 12 lakes located in Jeollanam-do based on the data surveyed from March to November 2014. Totally, 297 species of phytoplankton were identified including 98 Bacillariophyceae, 148 Chlorophyceae, 23 Cyanophyceae and 28 other phytoplankton taxa. The standing crops ranged from 124 to $59,148cells\;mL^{-1}$ and showed the highest in August with the increase of Cyanophycean cells. The self-organizing map (SOM) was optimized into $9{\times}6$ grid and was classified into 5 clusters based on the similarity of environmental factors and phytoplankton indices. The SOM results showed that phytoplankton communities had positive relationship with water temperature, SS, DO, BOD, TP and Chl-a, whereas low relationship with pH, TN, $NH_3-N$, $NO_3-N$, $PO_4-P$ and Conductivity. In Pearson's correlation coefficient, relationship between environmental factors and phytoplankton communities showed similar results with SOM.