• 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.

• Korean Journal of Environmental Biology
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• v.40 no.1
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• pp.54-69
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• 2022

We conducted a field survey from 2018 to 2020 to analyze the spatial distribution of phytoplankton communities at 13 stations in the East Sea. The diatom Chaetoceros curvisetus appeared as the dominant species in winter, and small flagellates less than 20 ㎛ prevailed in all seasons except winter. The seasonal average range of the micro (>20 ㎛), nano (20 ㎛≥Chl-a>3 ㎛), and picophytoplankton (≤3 ㎛) was 20.6-26.2%, 27.1-35.9%, and 40.8-49.0%, respectively. The composition ratio of nano and picophytoplankton was high at the surface mixed layer from spring to autumn when the water columns were strongly stratified. Especially, the stability of the water mass was increased when the summer surface water temperature was higher than that of the previous year. As a result, the nutrient inflow from the lower layer to the surface was reduced as the ocean stratification layer was strengthened. Therefore, the composition ratio of nano and picophytoplankton was the highest at 77.9% at the surface mixed layer. In conclusion, the structure of the phytoplankton community in the East Sea has been miniaturized, which is expected to form a complex microbial food web structure and lower the carbon transfer rate to the upper consumer stage.

• Ocean and Polar Research
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• v.27 no.4
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• pp.397-417
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• 2005

Phytoplankton community structure and distribution pattern in the surface water around the Ieodo Ocean Research Station were investigated during seven cruises carried out from July, 2003 to October, 2004. Samples were analyzed using various tools including a microscope, flow cytometer, and HPLC. Satellite images were used to analyze spatio-temporal phytoplankton biomass distribution. SeaWiFS chlorophyll a (chl a) images showed that spring blooms occurred in April-May near the Ieodo Station, and these waters were under the influence of Changjiang Dilute Water during July-October. Also, during the July-October period, HPLC pigments data showed increasing zeaxanthin concentrations, a marker pigment of cyanobacteria whereas increasing concentrations of various other pigments such as fucoxanthin, peridinin, prasinoxanthia alloxanthin, 19'-hexanoyloxyfucoxanthin and chlorophyll b were noted during spring blooms. Such pigment marker data were consistent with picoplankton data analyzed by flow cytometer and nano-microplankton analyzed by microscope. The pigment-CHEMTAX method was used to drive the phytoplankton group apportioned chi a. Diatoms, chlorophytes, dinoflagellates, and cryptophytes comprised 25.8, 20.7, 15.9, and 14.1%, respectively, of the total chl a in May. Average cyanobacteria concentrations in July-October contributed 25.4% of the total concentration. This was the highest percent contribution and was followed by chlorophytes, diatoms, and prymnesiophytes. This study discusses results from various methods, similarities and differences in the results among those methods, and the application range of the results from different analytical methods. Also, the study reveals a detailed phytolpankton community structure in the waters around the Ieodo Station, and suggests future monitoring considerations in relation to cell morphology, ecology and diversity factors according to taxonomic groups.

• Ocean and Polar Research
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• v.25 no.3
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• pp.315-329
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• 2003

During the 1st Korea-Russia Arctic Expedition from 3 to 26 August, 2000 phytoplankton biomass and nutrient concentration were measured in the Barents and Kara Seas. Total of 57 surface samples were collected f3r the phytoplankton related measurements. Chlorophyll a (chi a) concentraitons were measured to investigate the relations between physico-chemical factors and phytoplankton biomass distribution. Chl a values ranged from 0.14 to $2.34mg\;m^{-3}$ (mean of $0.65{\pm}0.42mg\;m^{-3}$) over the surface stations. The elevated values of the chi a concentrations $(1.49{\sim}2.34mg\;m^{-3})$ were found in the southeastern Barents Sea near the Pechora River. Nanoplanktonic $(<20{\mu}m)$ phytoflagellates were the important contributors for the increase of the chi a. The nano-sized phytoflagellates accounted for more than 80% of the total chi a biomass in the study area. Mean chi a concentration in the Barents Sea $(0.72{\pm}0.57 mg\;m^{-3})$ was higher than in the Kan Sea $(0.52{\pm}0.45mg\;m^{-3})$, but there was no big difference between two areas. Surface temperatures and salinities ranged from 4.1 to $11.7^{\circ}C$ (mean of $8.8{\pm}1.9^{\circ}C$) and from 23.8 to 32.5psu (mean of $30.3{\pm}1.9^{\circ}C$ psu), respectively. The physical factors were not highly correlated with phytoplankton distribution. It is speculated that the insignificant correlation between phytoplankton biomass and physical factor was due to the same current which introduced similar water mass with higher water temperature and lower salinity into the study area. The mean values of major nutrients such as ammonia, nitrite, nitrate, phosphate, and silicate were $0.42{\pm}0.31{\mu}M,\;0.10{\pm}0.03{\mu}M,\;1.44{\pm}1.03{\mu}M,\;0.35{\pm}0.12{\mu}M,\;10.99{\pm}3.45{\pm}M$, respectively. The relations between phytoplankton biomass and nutrient concentration were not close, indicating that the surface nutrient concentrations during the study seem to be controlled by other physical factors such as input of fresh water (i.e. dilution effects).

• Korean Journal of Environmental Biology
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• v.32 no.1
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• pp.35-48
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• 2014

In order to estimate the effect of additional nutrients on phytoplankton growth and horizontal phytoplankton community distribution during the autumn season in 2010 and 2011, we investigated the abiotic and biotic factors of surface and bottom waters at 20 stations of inner and offshore areas in Gwangyang Bay, Korea. Also, nutrient additional experiments were conducted to assess additional nutrient effects on phytoplankton assemblage using the surface water. In both years, the total nutrients were high at the enclosed inner bay and the mouth of Seomjin River, whereas it was low at the St.15~20 where in influenced by the surface warm water current from offshore of the bay. On the other hand, nano- and pico-sized Chl. a were gradually increased towards the outer bay and their trends were significant in 2011 than in 2010. The cryptophyta species occupied more than 85% of total phytoplankton assembleges in 2010, whereas their abundance in 2011 remainds to be 1/10 levels of 2010. Following the cryptophata species, the diatom Chaetoceros spp. and Skeletonema-like spp. were found to be dominant species. Further the biosaasy experimental results shows that the phytoplankton biomass in the +N and +NP treatments was higher compared to control and +P treatments and its trend was significant at St.8 and St.20 where nutrient concentration were low. Based on the bioassay and field survey, providing the high nutrients may have stimulated to phytoplankton growth such as S. costatum-like spp.. In particular, opportunistic micro-algae such as Cryptomonas spp. were able to achieve the high biomass under the relatively mid nutrient condition from bottom after break down of seasonal stratification in the Gwangyang Bay.

• Korean Journal of Environmental Biology
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• v.37 no.1
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• pp.19-30
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• 2019

To investigate the characteristics of seasonal environment and phytoplankton community structure in the coastal area of Dokdo, a survey of Dokdo around waters was conducted during the four seasons. Phytoplankton of 4 phylum 72 species in four seasons were collected in Dokdo around water. The seasonal mean abundance of phytoplankton were $3.32{\times}10^4cells\;L^{-1}$ in winter, $1.04{\times}10^4cells\;L^{-1}$ in spring, $0.28{\times}10^4cells\;L^{-1}$ in summer, and $4.86{\times}10^4cells\;L^{-1}$ in autumn in Dokdo around water. During winter, the diatoms Chaetoceros spp. had dominated. During spring, when the nutrients in the euphotic layer were depleted, the nano-flagellates and Cryptomonas appeared at surface layer. In summer, the abundance of phytoplankton was relatively low, which lead to occurrence of diatoms such as genus of Chaetoceros, Rhizosolenia, and Skeletonema. In autumn, Pseudo-nitzschia spp. was the most dominant species and tropical species such as Amphisolenia sp. and Ornithocercus magnificus were observed, implying that they may have introduced within warm water current such as Kurosiwo Current. Therefore, although natural phytoplankton communities in the vicinity water of Dokdo are mainly influenced by Tsushima Warm Current branched Kurosiwo Current, their population dynamics was affected on the spatio-temporal change of physicochemical factors by short-term wind events, namely "island effect". Long-term survey research is needed to facilitate food-web response in marine ecosystem associated with phytoplankton biomass and physicochemical factors including the warm water current in oligotrophic offshore water of Dokdo, which may have significant role for sustainable use of Dokdo.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.16 no.3
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• pp.117-124
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• 2011

Many studies of the phytoplankton community structure have been conducted using the CHEMTAX program on the basis of the photosynthetic pigment concentrations measured by a HPLC (High-Performance Liquid Chromatography) technique. The CHEMTAX program determines the contribution of each phytoplankton class to total phytoplankton biomass (chlorophyll a) based on the ratios of marker pigment to chlorophyll a of phytoplankton group. In this study, the marker pigment/chlorophyll a ratios were investigated in phytoplankton species isolated from marine waters around the Korean peninsula. These results were used as the input pigment ratios of the CHEMTAX program to investigate phytoplankton community structure in Korean coastal waters (Yeoja and Gamak Bay). There were significant differences in the ratios of marker pigment to chlorophyll a among the different species within the same algal class. There was a significant difference between the values of our ratios and the previously used ratios in other regions of the world. When phytoplankton community composition was calculated using our initial ratios in Yeoja and Gamak Bay, our results were significantly different from the results calculated on the basis of initial ratios of marker pigment in phytoplankton suggested in other marine waters. The estimates of the contributions of the major algal groups (bacillariophyceae and dinophytes) to total chlorophyll a varied within 5% depending on the initial ratios chosen. The variations of estimates for the pico- and nanoplankton (cyanophytes and prasinophytes), which have relatively low contributions to total chlorophyll a, were higher than those for major algal group. Although the HPLC-pigment measurements combined with CHEMTAX analysis are useful for identifying and qualifying phytoplankton community structure, further researches for the pigment ratios of the dominant phytoplankton species presenting in a given area are also needed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.11
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• pp.6008-6014
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• 2013

This study aimed to understand seasonal variation of physico-chemical factors and biomass of size-fractionated phytoplankton at Ulsan seaport during the period from February 2007 to November 2009. Water temperature, salinity, dissolved oxygen (DO), pH, chemical oxygen demand (COD) and total suspended solid (TSS) varied in the range of 8.94-$24.26^{\circ}C$, 25.06-34.54 psu, 4.30-10.73 mg/L, 7.97-8.53, 0.66-40.70 mg/L and 57.4-103.3 mg/L, respectively. These factors showed no clear spatial variation unlike spatial pattern of inorganic nutrients and total chlorophyll-a (chl-a) concentration as biomass. Concentration of phosphate, nitrate and silicate ranged from 0.01 to 3.03 ${\mu}M$, 0.05 to 21.62 ${\mu}M$, and 0.01 to 27.82 ${\mu}M$, respectively, with 2 times higher concentration at inner stations than that at outer stations during the study period. Within the range of total chl-a concentration (0.36-7.11 ${\mu}gL^{-1}$), higher concentration (avg. 1.88 ${\mu}gL^{-1}$) of total chl-a were observed at inner stations compared to that (avg. 0.90 ${\mu}gL^{-1}$) at outer stations. Micro-sized phytoplankton dominated total biomass of phytoplankton in spring (34.0-81.2%), summer (35.1-65.6%) and winter (3.9-62.0%). Nano- and pico-sized phytoplankton contributed 58.2-74.5% and 22.4-38.2% to total biomass of phytoplankton in autumn, respectively. However, contribution in biomass of size-fractionated phytoplankton to total phytoplankton biomass showed no clear difference between inner and outer stations. Consequently, these results indicated that spatio-temporal distribution of phytoplankton biomass at Ulsan seaport was dominated by micro-phytoplankton (avg. 52.3%) during the study period except autumn, which was closely dependent on the concentration of inorganic nutrients (p<0.05).

• Ocean and Polar Research
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• v.25 no.2
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• pp.213-226
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• 2003

Kongsfjorden near Korean Arctic Station, Dasan, is a glacial fjord in the Svalbard archipelago, Arctic that is influenced by both Atlantic and Arctic water masses. During the Arctic field season August 2002, surface temperature, salinity, density, and phytoplankton biomass (chi a) was measured in Kongsfjorden. A total of 15 surface samples were collected for the phytoplankton related measurements. Chl a values ranged from 0.08 to 1.4mg chi a $m^{-3}$ (mean of 0.53mg chl a $m^{-3}$) in the overall surface stations. The highest values of the chi a concentrations (> 1.0mg chi a $m^{-3}$) were found near glacier in the northeastern part of Kongsfjorden. Nanoplanktonic (< $20{\mu}m$) phytoflagellates were important contributors for the increase of the chi a. The nano-sized phytoflagellates accounted for more than 90% of the total chi a biomass in the study area. Surface temperatures and salinities ranged from 2.5 to $7.18^{\circ}C$ (mean of $4.65^{\circ}C$) and from 22.55 to 32.97 psu (mean of 30.16 psu), respectively. The physical factors were not highly correlated with phytoplankton distribution. The character of surface water due to down-fjord wind was highly similar to phytoplankton distribution. Drifting ice, freshwater, and semdiment inputs from large tidal glaciers located in the inner part of Konsfjorden create steep physico- and biogeochemical environmental gradients along the length of this ford. The glacial inputs cause reduced biodiversity biomass and productivity in the pelagic community in the inner fjord. Primary production of benthic and pelagic microalgae is reduced due to the limited light levels in the turbid and mixed inner waters. The magnitude of glacial effects diminishes towards the outer fjord. Kongsfjorden is an important feeding ground fer marine mammals and seabirds. Especially, seabirds play the largest energy intake and also export nutrients for primary production of the marine microalgae. Kongsfjorden has received a lot of research attention as a site for exploring the impacts of climate changes. Dasan Station in Kongsfjorden will be an important Arctic site for monitoring and detecting future environmental changes.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.4
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• pp.333-341
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• 2008

Three embankments are located in the Chunggye Bay, each named as Changpo, Bokkil and Kuil and environmental changes are expected due to freshwater input. To investigate this phenomenon, three sample sites in front of each embankment gate were selected in Nov. 2006(autumn), Feb. 2007(winter), May. 2007(spring) and Aug. 2007(summer). At every point of embankment spot, large cells(micro-size, >$20\;{\mu}m$) of phytoplankton were turned out to be a major cause of algal bloom in Feb. 2007 and nano-size($2-20\;{\mu}m$) phytoplankton became dominant during rainy season. In rainy season, each point of embankment showed low salinity and transparency with higher ammonium and phosphorus concentrations than dry season. However, the number of phytoplankton has decreased and it is expected that freshwater influx has more influence on high turbidity and radical decrease of salinity than nutrient. According to the results of this study, therefore, nutrient could have more influence on growth of phytoplankton in dry season, but high turbidity and radical changes of salinity have more influence in rainy season.