• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.10
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• pp.6388-6398
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• 2014

To understand size fractioned chlorophyll a and material cycle characteristics in Jeju marine ranching area (JMRA), 4 times of survey were conducted from April to November 2008. Picoplankton on the surface in JMRA was on average, $0.30{\mu}g/L$(annual mean(M):17.3%) in the $0.03{\sim}0.84{\mu}g/L$ range, accounting for 17.3%. Nannoplankton and picoplankton was on average, $1.35{\mu}g/L$(M:78.0%) in the $0.22{\sim}3.93{\mu}g/L$ range, and $1.73{\mu}g/L$(M:4.7%) in the nd ~ 0.24 range, respectively. The 10m layer was similar to the surface. The measured values changed according to the measurement times but the nanoplankton composition ratio was higher throughout the year. In addition, the size fractioned chlorophyll a distribution in JMRA was similar to that of tropical sea area affected by the Monsoon rather than South Korean offshore coast geographically adjacent to the East China Sea and Japan coastal waters affected by the Kuroshio/Tsushima warm currents. That is, the material cycle of JMRA consists of a microbial food web rather than traditional food chain at a lower trophic levels. Primary production is deemed to have a higher possibility of being adjusted by top-down dynamics, such as micro-zooplankton grazing pressure rather than nutrients supply.

• 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 Microbiology
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• v.43 no.2
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• pp.144-151
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• 2005

During the past ten years, Archaea have been recognized as a widespread and significant component of marine picoplankton assemblages. More recently, the presence of novel archaeal phylogenetic lineages has been discovered in coastal marine environments, freshwater lakes, polar seas, and deep-sea hydrothermal vents. Therefore, we conducted an investigation into the archaeal community existing in tidal flat sediment collected from Ganghwa Island, Korea. Phylogenetic analysis of archaeal 16S rDNA amplified directly from tidal flat sediment DNA revealed the presence of two major lineages, belonging to the Crenarchaeota ($53.9\%$) and Euryarchaeota ($46.1\%$) phyla. A total of 102 clones were then sequenced and analyzed by comprehensive phylogenetic analysis. The sequences determined in our samples were found to be closely related to the sequences of clones which had been previously obtained from a variety of marine environments. Archaeal clones exhibited higher similarities ($83.25 - 100\%$) to sequences..from other environments in the public database than did those ($75.22 - 98.46\%$) of previously reported bacterial clones obtained from tidal flat sediment. The results of our study suggest that the archaeal community in tidal flat sediment is remarkably diverse.

• Korean Journal of Environmental Biology
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• v.22 no.3
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• pp.426-437
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• 2004

To understand the phytoplankton community in adjacent waters of Ulchin nuclear power plant (UNPP), abundance and the size fractionated $chl-\alpha$ concentrations were evaluated through seasonal interval sampling from April 2003 to February 2004. A total of 211 different phytoplankton species was observed and mean abundance of phytoplankton in each study period ranged from 244,286 to 1,221,779 cells $L^{-1}$. The contributions of microplankton $(>20\mu{m})$ to total phytoplankton abundance ranged from 42.5 to 83.6% (average 66.1%) and those of nanoplankton $(>20\mu{m})$ ranged from 16.4 to 57.5% (average 33.9%). Total chl-$\alpha$ concentrations of phytoplankton ranged from 0.52 to $2.26\mu{g}\;L^{-1}$. The contribution of chl-$\alpha$ concentrations of microplankton was higher than that of nano- and picoplankton through the study period with exception of July 2008. The results of abundances and $chl-\alpha$ concentrations suggest that microplankton has an important role in adjacent waters of UNPP. The diminution of abundances and $chl-\alpha$ concentrations of phytoplankton was observed after passage through the cooling water system, but it was gradually recovered by mixing with the ambient waters. Our results suggested that the influence of thermal discharges on phytoplankton should be restricted within narrow limits around outlet area of thermal effluents.

• Ocean and Polar Research
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• v.28 no.2
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• pp.107-117
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• 2006

Freshwater algal studies in North polar environments are relatively few. This study presented the algal-flora, -biomass and genetic features of dominant cells collected from temporary ponds around the Polar Research Station (PRS), Norway. Water samples were collected from 4 stations around PRS, and analyzed for their environmental and biological variables. Water temperature, salinity and conductivity ranged from 5 to $10^{\circ}C$, 0.1 to $0.3%_{\circ}$ and 0.21 to $0.36{\mu}S/cm$, respectively. Chlorophyll a concentration ranged from 1.8 to $11.1{\mu}g/l$, and that of the size-fractionated cells was recorded from 0.7 to $1.1{\mu}g/l$ in picoplankton 0.3 to $6.5{\mu}g/l$ in nanoplankton, and 0.4 to $3.9{\mu}g/l$ in microplankton respectively. Algal flora in the present study was recorded as 10 genera, in which Chlamydomonas, particularly, was dominant in all studied sites. By comparison of Chlamydomonas 18S rDNA sequences, including two isolates from PRS, they formed a distinct clade against others: sequence similarity was significantly low (<97.2%) with C. noctigama, being the highest score by BLAST search in GenBank. This study was valuable for basic knowledge regarding the freshwater algae around PRS and their genetic information.

• ALGAE
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• v.23 no.4
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• pp.257-268
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• 2008

Species composition, standing crop and dominant species of phytoplankton were investigated at 6 sites of Galgok stream and Incheon river which run into Gomso Bay, Jeollanam-do in April, August and November 2007. Total of 210 taxa were found which were classified as 6 classes, 12 orders, 25 families, 66 genera, 177 species, 27 varieties, 5 forms and 1 unidentified species. These river and stream had lower concentration of T-N and T-P compared to that of others; however, the site 2 of Galgok stream in summer was hypertrophic in T-P and also near hypertrophic in TN, and the site 1 in Incheon river during fall appeared to be hypertrophic in T-N, and the site 3 in summer showed near hypertrophic level in T-P. Determining the trophic status of the water quality based on chlorophyll a (chl-a), the site 3 of Galgok stream in spring and the site 3 of Incheon river in fall were oligotrophic; moreover, 6 sites including the site 2 and 3 of Galgok stream in summer were mesotrophic, and 9 sites including all sites of Galgok stream in fall turned out to be eutrophic. Particularly, the site 1 of Galgok stream in summer was hypertrophic, having 58.19 mg chl-a m$^{-3}$. There was a conspicuous difference between two values of standing crops based on chl-a and cell counting. This discrepancy may have occurred because of abundant cyanophytes and exclusion of picoplankton cells in cell counting. In the study, 5 cyanophytes, Synechocystis aquatilis, Microcystis aeruginosa, M. flos-aquae, Oscillatoria angustissima, O. limnetica and 2 diatoms, Thalassiosira bramaputrae and Navicula viridula var. rostellata were abundant. Based on the T-N, T-P values, standing crops and cell counting in Galgok stream and Incheon river were between mesotrophic and eutrophic conditions.

• 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.

• Journal of Wetlands Research
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• v.12 no.2
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• pp.47-57
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• 2010

The purpose of this study is to investigate the seasonal variation of water quality parameters in Suncheon bay. We investigated at fifteen stations from October 2008to July 2009. picoplankton The salinity in the bay ranged from 8.8 to 31.9psu, DO ranged from 6.34 to 11.84 mg/L and the pH ranged from 7.80 to 8.34. The mean concentration of suspended solids ranged from 52.1 to 104.0 mg/L and COD concentration ranged from 2.27 to 5.33 mg/L. The total coliform group ranged from 6 to 37CFU. The concentrations of COD and total coliform group were relatively higher in the upper part of the Suncheon bay than lower one. The concentrations of nutrients such as nitrogen, phosphorus, silicate were also higher in the upper part of the bay, because the large amount of fresh water was inflowed into the bay from the Dong stream and Isa stream. Because the N/P ratio was ranged from 4.54 to 9.61 in this study, the limiting nutrients was nitrogen in the Suncheon bay comparing to the Redfield ratio.

• Korean Journal of Ecology and Environment
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• v.33 no.4 s.92
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• pp.358-365
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• 2000

To evaluate the influences of stocking and removal of silver carp on plankton communities and physicochemical parameters, fish biomanipulation was conducted in six enclosures constructed on the coast of a hypertrophic lake during the summer of 1997. Of these, three enclosures were established for the fish-stocking experiment; one fishless enclosure used as a control and two enclosures with high and low densities of fish. The other three enclosures for the fish-removal experiment were prepared in an entirely converse process compared to that for fish stocking. The results of randomized intervention analysis (${\alpha}=0.05$) showed significant changes in several physicochemical parameters and plankton communities after fish stocking and removal. Fish stocking decreased water transparency, DO, pH and chi-a (> $40\;{\mu}m$), while increasing the concentration of nitrogen and chi-a (<$2\;{\mu}m$). However, water transparency did not increase by fish removal. Small plankton communities, such as picocyanobacteria, eukaryotic picoplankton and ciliates (<$2\;{\mu}m$) showed significant reciprocal changes after both fish treatments: increase by the presence of fish and decrease by the absence of fish. No count of large sized phytoplankton and zooplankton showed significant change in the presence of fish, while large zooplankton, Diaphanosoma, Cyclopida and nauplii were significantly increased by fish removal. Although the frequent heavy-winds and endless supply of phosphorus from the lake sediment strongly disturbed the fish behavior and enclosure management, the stocking and removal of silver carp showed an obvious reciprocal influences on plankton communities and its physico-chemical parameters in a shallow-hypertrophic lake.

• 한국해양학회지
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• v.27 no.2
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• pp.91-100
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• 1992

For the study on the structure and characteristics of the primary production system in the southern waters of the East Sea, chlorophyll, phytoplankton standing stocks. nutrients and hydrographic properties were investigated and analyzed in conjunction with measurement of C-14 based primary productivity. The primary productivity was relatively high in comparison with the previous studies, ranging from 284 to 4,574 mgC$.$m/SUP -2/$.$day /SUP -1/ and averaged to be 2,000 mgC$.$m/SUP 02/$.$day/SUP -1/. The standing stocks within the euphotic zone were fairly high, but ambient inorganic nitrogenous nutrient concentrations were too low to support the high production. This implied that there might be active recycling of nitrogenous nutrients by heterotrophic processes and the upward flux of nutrients by vertical mixing. Subsurface chlorophyll maxima were continuously observed in the lower parts of the euphotic layer and the depth coincided with the nutricline rather than isopycnal surfaces, supporting the view that chlorophyll distributions and primary production were primarily influenced by nutrient supply. Despite low nutrient concentrations, phytoplankton standing stocks and production were fairly high and the fraction of autotrophic nano- and picoplankton production was significant.