• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.6
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• pp.727-732
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• 1994

In the South Sea of Korea, in vivo fluorescence intensity (IVF) and extractable chlorophyll a concentration were measured to determine whether there was significant defference in in vivo fluorescence per unit chlorophyll a (R) between netplankton and nanoplankton size classes (less than $22{\mu}m$). IVF and chlorophyll a were linearly related for both size classes, but R's were significantly different between two size classes. The R of nanoplankton was about 7 times higher than that of netplankton. Therefore, the size dependency of R must be taken into consideration when size fraction of phytoplankton biomass is determined from the measurements of in vivo fluorescence intensity.

• 한국해양학회지
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• v.25 no.4
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• pp.217-228
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• 1990

In order to study on the relative significance of nanoplankton in Chonsu Bay, nanoplankton samples were collected and analyzed monthly from September, 1985 to August, 1986. A total of 33 taxa representing 6 phyla, 8 classes, 13 orders, 17 families, 25 genera, 33 species have been identified. Micromonas pusilla, Pedinomonas mikron, Pyramimonas grosii, Chroomonas lateralis, Pyrenomonas salina (=Chromonas salina), chroomonas sp., Cyclotella sp., Gonyaulax sp., unidentified sphericl monads (2-5um and 6-8um in size), and unidentified naviculiod form were common species. the distribution of nanoplankton standing crops showed a great temporal and spartial variations. Nanoplankton standing crops was highest in October, 1985 and lowest in September, 1985. The abundance of nanoplankton in Chonsu Bay may be within the range of that of most coastal areas. Unidentified spherical monada (2-5um and 6-8um in size) were most dominant. Chlorophyll-a concentrations of nanoplankton ranged from 0.81 to 4.78ug/l and daily primary productivity by nanoplankton, 16.4 to 767.2 mgC/m$^2$/day. Nanofraction of total phytoplankton cell number accounted for 38% to 93% (average 6%), chlorophyll-a and primary productivity of nanoplankton 25 to 87% (average 64%) and 9 to 87% (average 53%), respectively. The results implied that nanoplankton could be a considerable contribution to phytoplankton biomass and primary productivity in Chonsu Bay phytoplankton community.

• Korean Journal of Ecology and Environment
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• v.37 no.3 s.108
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• pp.263-271
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• 2004

To collect the basic ecological information about the microbial food webs in eutrophic water system with different residence time, the monthly variation of bacterioplankon (bacteria and small-sized cyanobacteria) and nanoplankton (phytoplankton and protists) were examined from December 2000 to September 2001. Kyungan stream is shorter in resident time (ca.5.4 d) than Seokchon reservoir (ca.72 d), even though they showed the same pattern in precipitation. With the basic environments, we examined the biomass (standing crops and its carbon content) of each plankton collected from the surface water. Large-sized planktons flourished in the time of low temperature, while small planktons were in the time of the high temperature period. Especially, in the Kyungan stream with much disturbance by rainfall and outflow, high diversity showed in term of species and cell morphology, compared to that of Seokchon lake. The time-lag relationship remarkably showed between phytoplankton and bacteria in Seokchon reservoir, and between protists and bacteria in Kyungan stream, respectively.

• Korean Journal of Environmental Biology
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• v.30 no.3
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• pp.173-184
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• 2012

In order to investigate the fluctuation rates [FR] of phytoplankton after passage through a cooling system, the standing crops, chlorophyll a concentrations and carbon assimilation number of phytoplankton were surveyed at intake and outlet at Wolsong nuclear power plant [NPP] from July 2006 to June 2008. As a result, the total mean standing crops of phytoplankton were $1.0{\times}10^6\;cells\;L^{-1}$ and $7.3{\times}10^5\;cells\;L^{-1}$ at intake and outlet, respectively. The FR of phytoplankton by passage through the cooling system [PTCS] was 27.0%. Among them, the FR of microplankton and nanoplankton were 34.1% and 12.4%, respectively. In addition, the FR of diatoms and dinoflagellateswere 33.9% and 29.7%, respectively. These results showed the entrainment effects on microplankton and diatoms by PTCS were higher than those of nanoplankton and dinoflagellates. The FR of total chlorophyll a concentrations were 54.4%, and the FR of microplankton, nanoplankton and picoplankton were 58.9%, 38.5%, and 52.4%, respectively. So the entrainment effects on microplankton by PTCS were higher than those of nanoplankton and picoplankton. The mean FR of carbon assimilation number of phytoplankton was 57.6%, and the seasonal variations of FR of carbon assimilation number ranged from 47.5% to 76.8%. Our results indicated that the phytoplankton species responded differently to power plant operating conditions such as elevated temperature, chlorination, and mechanical impacts.

• 한국해양학회지
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• v.24 no.4
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• pp.194-205
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• 1989

In order to study the biomass of primary producer, phytoplankton is collected monthly September 1985 to August 1986 in Ch$\check{o}$nsu Bay. Phytoplankton carbon contents which are calculated from phytoplankton volume were ranged from $26.7{\mu}gC/l$ to $960.7{\mu}gC/l$, and average carbon contents of each month lie in the range of $58.6-684.7{\mu}gC/l$(annual mean $208.5{\mu}gC/l$). For net plankton analysis with the carbon contents, cell numbers, and chlorophyll concentrations show a close correlation, while for nanoplankton the correlation was low, indicating that nano-fraction includes a significant portion of picoplankton. Also, the multiple regression analysis with carbon content, cell number, and chlorophyll concentration to size fraction well illustrate the prime importance of the net-fraction in phytoplankton group. C/Chl-a ratios ranged from 9.1 to 100.5, average rations of net- and nanoplankton are 111 and 6.4, respectively. The greater net plankton faction is, the higher C/Chl-a ratio is, however in case of high nanoplankton portion C/Chl-a ratio show low level. These results indicate that the difference of C/Chl-a ratio per phytoplankton cell size be main factor for the variation of C/Chl-a ratio in Ch$\check{o}$nsu Bay. As C/Chl-a ratio fluctuates greatly in coastal ecosystem, that use of a direct conversion of convert chlorophyll to organic carbon may lead erronous estimation.

• Journal of Environmental Science International
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• v.16 no.7
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• pp.855-863
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• 2007

In order to understand the temporal distribution of pico- and nanoplankton and factors controlling its distribution at a station in Okkye Bay of Masan Bay located in the southern part of Korea, this study was conducted on two weeks interval from April 2005 to April 2006, and several abiotic and biotic factors were measured. During the study, picoplankton consisted of picoflagellates, cyanobacteria and heterotrophic bacteria, and nanoplankton consisted of nanoflagellates excluding dinoflagellates. The concentration of chlorophyll-a (chl-a) was a mean of $4.33\;{\mu}g/L$, and the nanoplanktonic ($<20\;{\mu}m$) chl-a size fraction was a mean of 39.5 % and significantly correlated with water temperature. The abundances of cyanobacteria and photosynthetic flagellates (PF) were means of $24.4{\times}10^{3}\;cells/mL\;and\;2.87{\times}10^{3}\;cells/mL$, respectively. The contribution of picoflagellates to the PF abundance varied among the sampling occasions and was a mean of 29 %, but to the PF carbon biomass was 2.6 % only. The PF abundance had significant relationships with water temperature, and silicate and TIN concentrations, suggesting that the PF abundance seemed to be primarily bottom-up regulated. The abundance of heterotrophic bacteria was a mean of $3.18{\times}10^{6}\;cells/mL$ and unlike other ecosystems it did not have relationships with chl-a and heterotrophic flagellates (HF), suggesting that bacterial abundance did not seem to be bottom-up or top-down regulated. HF mostly consisted of cells less than $5{\mu}m$ and its abundance was a mean of $2.71{\times}10^{3}\;cells/mL$. Of the HF abundance, picoflagellates occupied about 31 %, and occupied about 9 % of the HF carbon biomass. HF grazing activity on heterotrophic bacteria was relatively low and removed about 10 % of bacterial abundance, suggesting that HF might not be major consumers of bacteria and there seems to be other consumers in Okkye Bay. These results suggest that Okkye Bay may have a unique microbial ecosystem.

• ALGAE
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• v.23 no.1
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• pp.31-52
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• 2008

This study analyzes characteristics of phytoplankton communities around Wolseong nuclear power plant by selecting 16 stations from July 2006 to June 2007 and understands the influences on standing crops and chlorophyll a of phytoplankton by passing through the cooling water system. The total species number is 283, among which diatoms is 208 occupying 73.5% of total taxa. The mean of total standing crops is 469,380-3,704,114 cells L-1. It is the highest in April 2007 because blooming of Chaetoceros socialis occurs during this period. The mean standing crops of microplankton and nanoplankton are average 129,666-3,392,640 cells L-1 and 240,943-650,505 cells L-1 respectively, which occupy 54.01% and 46.54% of total standing crops. The mean concentrations of total chlorophyll a is 0.64-5.39 μg L-1. The mean concentrations of chlorophyll a of microplankton, nanoplankton and picoplankton are 1.33 μg L-1, 0.21 μg L-1 and 0.49 μg L-1 respectively. Dominant species around Wolseong neclear power plant during this study are Chaetoceros debilis, Chaetoceros socialis, Leptocylindrus danicus, Pseudo-nitzschia fraudulenta, P. subfraudulenta and Thalassiosira decipiens. Fluctuation rates of standing crops and chlorophyll a concentrations of phytoplankton passing through the cooling water system are 22.80% and 50.48% respectively. Decrease of standing crops and chlorophyll a concentrations of phytoplankton means that community structure of phytoplnakton may change at the discharge areas.

• Korean Journal of Environmental Biology
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• v.40 no.4
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• pp.374-386
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• 2022

Phytoplankton communities, with emphasis on picoplankton and nanoplankton, were investigated in Gamak Bay, South Korea, where freshwater input and coastal water intrusion shape ecosystem functions. Shellfish farms and fish farms are located in the inner bay and outer bay, respectively, and tides translocate uneaten food and urine production from aquaculture farms toward the inner bay. Water masses were distinctly different based on a significantly different density between the surface and bottom layer and among three water masses, including the inner bay, outer bay, and Yeosu Harbor. Phytoplankton communities were quantified using flow cytometry and size-fractionated chlorophyll-a (chl-a) was measured. Salinity was a principal variable separating phytoplankton communities between the surface and bottom layer, whereas Si(OH)₄ controlled the communities in the inner bay, and NH₄⁺ and PO₄^3- governed the outer bay communities. While phycocyanin-containing (PC) cyanobacteria dominated in the outer bay, phycoerythrin-containing (PE) cyanobacteria dominance occurred with cryptophyte dominance, indicating that nutrients affected the distribution of pico- and nanoplankton and that cryptophytes potentially relied on a mixotrophic mode by feeding on PE cyanobacteria. Interestingly, picoeukaryotes and eukaryotes larger than 10 ㎛ were mostly responsible for the ecological niche in the western region of the bay. Given that chl-a levels have historically declined, our study highlights the potential importance of increased small phytoplankton in Gamak Bay. Particularly, we urge an examination of the ecological role of small phytoplankton in the food supply of cultivated marine organisms.

• Journal of Plant Biology
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• v.35 no.4
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• pp.323-332
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• 1992

Chlorophyll-a concentrations of phytoplankton and primary productivities in closed marine ecosystem, Inchon Dock, were measured and analyzed monthly from August, 1990 to December, 1991. Chlorophyll-a concentrations ranged from 1.61 to $28.67\;\mu\textrm{g}\;Chi-a/I$, where nanoplankton ($2-20\;\mu\textrm{m}$) fractions contributed in 19.0-82.3% and picoplankton ($0.2-2\;\mu\textrm{m}$) fractions in 4.5-51.4%. Primary productivities measured by $^{14}C$ method ranged from 49.4 to $4359.4\;mg\;C{\cdot}m^{-2}{\cdot}day^{-I}$, where nanoplankton ($20\;\mu\textrm{m}$) contributed in 18.8-94.6%. These results implied that very tiny cell-sized phytoplankton populations were important in point of chlorophyll-a concentration and primary productivity of phytoplankton community. In monthly variations of chlorophyll-a concentration by phytoplankton, the first peak occurred in March and the second in August. Nitrogen requirement by phytoplankton ranged from 0.7 to $60.7\;mg\;at-N{\cdot}m^{-2}{\cdot}day^{-I}$ and the turnover time of inorganic nitrogen showed maximum during winter and minimum in summer. Carbon assimilation number increased in summer and decreased in winter.winter.

• Korean Journal of Ecology and Environment
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• v.34 no.4 s.96
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• pp.277-284
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• 2001

Since a substantial part of the total planktonic primary production is due to the activity of the picoplankton, seasonal change of chlorophyll a in the picoplankton, nanoplankton and microplankton was determined at four locations in Daechung Reservoir from September in 1998 to September in 1999. Chlorophyll a concentration (<$200\;{\mu}m$) was $0.7{\sim}36.9\;{\mu}g/l$ In TAE (Taejeon site), $0.5{\sim}23.5\;{\mu}g/l$ in MAN (Man site), $1.9{\sim}20.1\;{\mu}g/l$ in HOE (Hoenam site), and $0.5{\sim}17.4\;{\mu}g/l$ in DAM (Dam site). Generally it was observed the highest concentration of chlorophyll a was in September and the lowest in April to June. The relative contribution of chlorophyll a of each fraction was changed dramatically through the year. Relative contribution of chlorophyll a of microplankton was high from June to October, and low in March in all locations except HOE. However chlorophlyll a concentration of picoplankton fraction was $2.0{\sim}24.3%$ of total chlorophyll a (<$200\;{\mu}m$) through the year and did not show any dramatic changes at all locations.