• Ocean Science Journal
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• 제40권3호
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• pp.109-117
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• 2005

Daily changes in phytoplankton abundance and species composition were monitored from July to September 2003 (n=47) to understand which factors control the abundance at a station in Jangmok Bay. During the study, the phytoplankton community was mainly composed of small cell diatoms and dinoflagellates, and the dominant genera were Chaetoceros, Nitzschia, Skeletonema and Thalassionema. Phytoplankton abundance varied significantly from $6.40{\times}10^4$ to $1.22{\times}10^7$ cells/l. The initially high level of phytoplankton abundance was dominated by diatoms, but replacement by dinoflagellates started when the NIP ratio decreased to <5.0. On the basis of the N/P and Si/N ratios, the sampling periofd could be divided into two: an inorganic silicate limitation period (ISLP, $14^{th}$ $July-12^{th}$ of August) and an inorganic nitrogen limitation period (INLP, $13^{th}$ of August - the end of the study). Phosphate might not limit the growth of phytoplankton assemblages in the bay during the study period. This study suggests that phytoplankton abundance and species composition might be affected by the concentrations of inorganic nutrients (N and Si), and provides baseline information for further studies on plankton dynamics in Jangmok Bay.

• 환경생물
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• 제29권4호
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• pp.312-320
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• 2011

본 연구는 해양 식물플랑크톤의 개체수 및 생체량과 chlorophyll $a$ 농도간의 연관성을 파악하기 위하여 2000년부터 2010년까지 인천, 통영, 울산 해역의 34개 정점에서 1160개 시료를 분석하였다. 연구결과 개체수와 chlorophyll $a$ 농도가 생체량과 chlorophyll $a$ 농도보다 높은 상관성을 보여 우리나라 연안해역에서는 1차 생산의 분석에 있어서 개체수 지표를 사용하는 것이 생체량을 사용하는 것보다 더 효율적일 것으로 판단된다. 그러나 좀 더 자세한 결과를 도출하기 위해서는 시기별로 보다 많고, 정확한 생체량 데이터를 확보하고, 시기별 chlorophyll 함량 자료의 축적과 함께 국내 연안에서 적용 가능한 모델 구축이 반드시 필요하다.

• 환경생물
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• 제22권3호
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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.

• ALGAE
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• 제20권4호
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• pp.345-352
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• 2005

In order to investigate the distribution of phytoplankton community in the coastal waters of the Chuksan Harbor, East Sea, the abundance and biomass of phytoplankton have been evaluated through seasonal interval sampling from April 2000 to October 2002. A total of 363 different phytoplankton species was observed and most of them were composed of diatoms. The mean abundance and chlorophyll-a concentration of phytoplankton during the study period ranged from 56 ${\times}$ $10^3$ to 720 ${\times}$ $10^3$ cells $L^{-1}$ and from 0.78 to 3.29 μg chl-a $L^{-1}$, respectively. The relative contribution of the size-fractionated phytoplankton to phytoplankton community showed difference according to seasons. The average contribution of nano-phytoplankton(<20 $\mu$m) was over 50% in the total abundance and biomass of the phytoplankton. Our results show that nano-phytoplankton play an important role in the southern coastal waters of the East Sea. And the environmental factors such as suspended substances, phosphates and silicates were positively correlated with the abundances and biomass of phytoplankton.

• 한국수산과학회지
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• 제38권1호
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• pp.55-64
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• 2005

Spatio-temporal variations of phytoplankton abundance and nutrient concentrations were investigated in the Namdaechon estuary, Yangyang, from April to December, 2003. A total of 51 phytoplankton species were identified with 32 diatom species in the study area. Phytoplankton abundance ranged from 14 cells/mL to 3,798 cells/mL. Small sized benthic and pennate-type diatoms like Cymbella spp., Fragilaria spp., Navicula spp., Synedra spp. were dominant at throughout the whole study area. Various planktonic species like Chlamydomonas sp., Peridinium spp., Euglena spp., Cryptomonas spp. etc. were abundant especially at the estuary of the Namdaechon, from May to August. Phytoplankton bloom (>3,000 \;cells/mL) occurred from the late May to mid June. After September when the sandbank of estuary was broken by the typhoon 'Maemi', planktonic species disappeared. These planktonic species were followed by oceanic diatoms, Skeletonema costatum and Chaetoceros spp.. Concentrations of dissolved inorganic nitrogen (DIN) and silicate were relatively high at the upstream in summer. In May, before phytoplankton bloom, high concentrations of phosphate $(>3.5\;{\mu}mol/L)$ were observed at all the study area. These results suggested that spatio-temporal variation of phytoplankton in the Namdaechon estuary was related to formation of sandbank at the mouth of the estuary, fluid speed affected by sandbank and nutrients supplied in spring. High correlation $(r^2=0.928)$ between chlorophyll a and biological oxygen demand (BOD) implies that BOD was related to phytoplankton abundance in the Namdaechon estuary.

• 한국환경과학회지
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• 제17권12호
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• pp.1403-1411
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• 2008

Wangdol-cho, located 23 km offshore of Hupo in southwest of East Sea, is underwater rock floor, called to Wangdol-Am or Wangdol-Jam and has three tops as Mat-Jam, Middle-Jam and Set-Jam. The composition, abundance, diversity and community structure were investigated in winter and summer in 2002 around Wangdol-cho. The temperature around the Northwest and Southeast part of Wangdol-cho was influenced by the North Korea Cold Current (NKCC) and East Korea Warm Current (EKWC), respectively. Nutrient and chlorophyll-a concentration were higher at the top of Wangdol-cho than other area. A total of 41 genera and 78 species of phytoplankton were identified. The average cell abundance of phytoplankton in winter and summer were $286{\times}10^3\;cells/m^3,\;432{\times}10^3\;cells/m^3$ respectively. The largest community was Bacillariophyta containing 52 taxa. The dominant species were Lauderia anulata and Coscinodiscus spp. which preferred cold water in winter. In contrast, warm water species such as Rhizosolenia stolterfothii and Ceratium spp. were dominant in summer. The average species diversity index of phytoplankton in winter was higher than that in summer. According to dominant species and standing crops, phytoplankton community resulted in a clear separation. One group was western area, which showed low density, and the other was eastern area, which showed the higher density. The abundance and species composition of phytoplankton. were affected by topological characteristics around Wangdol-cho.

• Ocean and Polar Research
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• 제34권2호
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• pp.111-123
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• 2012

To understand the phytoplankton community in the eastern part of the Yellow Sea (EYS), in the summer, field survey was conducted at 25 stations in June 2009, and water samples were analyzed using a epifluorescence microscopy, flow cytometry and HPLC method. The EYS could be divided into four areas by a cluster analysis, using phytoplankton group abundances: coastal mixing area, Anma-do area, transition water, and the central Yellow Sea. In the coastal mixing area, water column was well mixed vertically, and phytoplankton was dominated by diatoms, chrysophytes, dinoflagellates and nanoflagellates, showing high abundance ($>10^5\;cells\;l^{-1}$). In Anma-do coastal waters characterized by high dominance of dinoflagellates, high phytoplankton abundance and biomass separated from other coastal mixing area. The southeastern upwelling area was expanded from Jin-do to Heuksan-do, by a tidal mixing and coastal upwelling in the southern area of Manjae-do, and phytoplankton was dominated by benthic diatoms, nanoflagellates and Synechococcus group in this area. Phytoplankton abundance and biomass dominated by pico- and nanophytoplankton were low values in the transition waters and the central Yellow Sea. In the surface of the central Yellow Sea, high dominance of photosynthetic pigments, 19'-hexanoyloxyfucoxanthin and zeaxanthin implies that haptophytes and cyanobacteria could be the dominant group during the summer. These results indicate that the phytoplankton communities in the EYS were significantly affected by the formation of tidal front, thermal stratification, and coastal upwelling showing the differences of physical and chemical characteristics during the summer.

• 한국패류학회지
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• 제20권1호
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• pp.27-34
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• 2004

Based on both field and laboratory experiments, seasonal changes in the species composition and abundance of phytoplankton in the gut contents of the jedo venus clam, Protothaca jedoensis, and its feeding selectivity were investigated. The phytoplankton in the gut contents comprised Bacillariophyceae (diatom), Chlorophyceae, Chrysophyceae, and Dinophyceae, of which the diatoms being the most predominant throughout the year. Although the number of species and the abundance of phytoplankton in the sea water were always more diverse and more abundant than in the gut contents, the relative number and abundance were generally similar in the seawater and in the gut contents. In the laboratory experiments, the relative abundances of Coscinodiscus marginatus and Thalassirosira eccentrica were much more higher in the gut contents than any other algal species, while Paralia sulcata, Skeletonema costatum, and Eucampia zodiacus were abundant in order of cell density in the ambient water. These results suggest that P. jedoensis may feed preferably on single algal cell or smaller chains of algal cells.

• 한국환경과학회지
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• 제15권6호
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• pp.539-562
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• 2006

The clarification of spatial-temporal patterns of phytoplankton from southern coastal waters during the period of March to November in 2004 was carried out. Total cell numbers were shown in 5,286 cells $ml^{-1}$ on March and reached to encounter a peak of 27,775 cells $ml^{-1}$ on July. Mean cell number was also shown in maximum of 1,587 cells $ml^{-1}$ on July, which recorded approximately two times higher than on June. The cell number of phytoplankton from southmiddle waters attained an abundance of ${\geq}35%$ regardless of months, which was the highest the abundance of phytoplankton in 2004 than any other waters in this study. Southwestern waters were lower the cell number of 2-5 times than those of southmiddle and southeastern waters. In particular, Prorocentrum occurred in southeastern waters on June and the highest cell number of 8,200 cells $ml^{-1}$ around Tongyeong region on July, which was recorded to occupy the value of 60.9% in southeast waters. The abundance of Skeletonema costatum as a dominant taxa in southwest was shown in ${\geq}60%$ on March, July, September, and October, whereas was also recorded to achieve the abundance of above 80% in southmiddle waters on March, July, and September. The majority of the taxa in southeastern waters was diatom: Eucampia zoodiacus, and Chaetoceros spp.. They occupied above 45%. On November, most of southern waters were abundant to Chaetoceros spp. On the basis of cluster analysis using SPSS ver 10.0, phytoplankton occurring on March showed somewhat no correlation with all of southern waters. In contrast to on March, the relationship between southwestern and southmiddle waters was shown on August and November, indicating a distinction from southeastern waters. However, the distance between southwestern/middle and southeastern waters appeared to be less than 5. Consequently, the abundance of phytoplankton in southern waters showed much fluctuations in temporal and spatial assays. In particular, southwestern and southmiddle waters during the periods of summer and winter appeared to be a similar to environmental characteristics.

• Journal of the korean society of oceanography
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• 제37권1호
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• pp.35-44
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• 2002

To assess the relative contribution of bacterial and phytoplankton biomasses to particulate organic matter (POM) in the water column, microbial abundance and biomass were from two transects in the western channel of the Korea Strait in 1996. Bacterial abundance had a mean value of $5.9{\times}10^5$ cells/ml and chlorophyll-a averaged 0.14 ${\mu}g/l$. Bacterial abundance in the Korea Strait showed a positive relationship with chlorophyll-a concentration, while the distribution of POM did not covary with chlorophyll-a. Particulate organic carbon (POC) and nitrogen (PON) concentrations were greater in August than in October. Bacterial carbon (POC) and nitrogen (PON) concentrations were greater in August than in October. Bacterial carbon and nitrogen biomasses were 7.29 ${\mu}gC/l$ and 1.24 ${\mu}gN/l$, respectively, during the study periods. Bacterial biomass was larger in October than in August due to the autumn phytoplankton bloom. Phytoplankton biomass based on chlorophyll-a was 7.67 ${\mu}gC/l$ for carbon and 1.10${\mu}gN/l$l for nitrogen. The ratio of bacterial carbon (BC) to phytoplankton carbon (Cp) averaged 0.95 in the Korea Strait in 1996. Bacteria may play a more significant role in the dynamics of POM than phytoplankton do in August, with BC/Cp ratio of 1.26. The ratio of BC to Cp increased with a decrease in chlorophyll-a concentration. Averaged over all the samples in both cruises, the contribution of microbial biomass to POC and PON was about 43% and 51%, respectively. Bacterial assemblage constituted a significant fraction of POC (21%) and PON (27%). Phytoplankton accounted for 22% of POC and 24% of PON. Microbial biomass played a more important role in the dynamics of POC and PON in October than in August due to a significant increase in microbial biomass in the southern transect (transect-B) in October by the autumn phytoplankton bloom. This study showed that marine microbes may constitute a significant part in the reservoir of POM in the Korea Strait.