• ALGAE
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• v.32 no.3
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• pp.181-187
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• 2017

During a sampling at Nokdong harbor, southern coast of Korea in January 2017, the marine diatom Coscinodiscus wailesii cells infected by a novel parasitoid nanoflagellate were observed. While the development process of the trophosomes of the parasitoid was more similar to that of Pseudopirsonia mucosa, division pattern of the auxosomes was similar to that of Pirsonia species. Phylogenetic analyses inferred from 18S rRNA gene sequences revealed that the parasitoid infecting C. wailesii fell within the cercozoan groups and branched as a sister lineage of the clade consisting of Pseudopirsonia mucosa and the undescribed Cercomonas sp. SIC7235, with the sequence dissimilarity of 7.3% with Pseudopirsonia mucosa. All of these developmental and molecular characteristics suggest that the parasitoid nanoflagellate infecting the diatom C. wailesii is a new Pseudopirsonia species.

• Korean Journal of Environmental Biology
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• v.38 no.4
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• pp.567-577
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• 2020

The infection of marine diatom Coscinodiscus wailesii by a parasitic protist from the Yongho Bay of Busan, Korea was observed during the diatom bloom events in 2017 through 2018. The morphological and molecular features suggested that the parasitic nanoflagellate Pirsonia diadema was responsible for the infection. During the study period, the parasite prevalence ranged from 0.3% to 3.3%, and infected C. wailesii cells were observed only at surface seawater temperatures ranging between 10.9 and 19.9℃, although the host population appeared at temperatures above 25℃. The parasite and host system was successfully established as cultures. Using the cultures, we determined the morphological features over the infection cycle, parasite generation time, parasite prevalence as a function of inoculum size, and zoospore infectivity and survival time. The diatom C. wailesii was readily infected by the parasite P. diadema, with a parasite prevalence reaching up to 100% and a zoospore to host inoculum ratio above 20:1. The survival and infectivity of the parasite zoospores decreased with age. While the zoospores could survive up to 88 hours, they quickly lost their ability to infect after 48 hours. These results could lead to a better understanding of the biology and ecology of the parasitoid infecting the giant-sized diatoms in coastal waters.

• 한국해양학회지
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• v.2 no.1_2
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• pp.1-12
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• 1967

As a part of the primary production in the coastal water of Korea Seas on October-November 1964 and June-July 1965, quantitative phytoplankton materials by the net haul were obtained. This paper deals with a study on the distribution quantity and specific composition of the phytoplankton in the same waters. 76 species of diatoms and 8 species of dinoflagellates in October-November 1964, and 74 species of diatoms and 7 species of dinoflagellates in June-July 1965 were found. In autumn of 1964 and spring of 1965, there occured 90 species of diatoms and 10 species of dinoflagellates, and 60 species of diatoms and 5 species of dinoflagellates were encountered in both seasons. The maximal total quantity of phytoplankton were observed at Pohang (27,844,000 cell/㎥), Ulsan (25,186,000 cells/㎥) and Yosu (12,829,000 cells/㎥) in June-July 1965 and the smallest (16,000 cells/㎥) at Jukbyon in the coast of the Sea of Japan in October-November 1964. The coastal water of Korean Seas, as well as in the primary production study, is divided into four regions by the phytoplankton characters; coastal waters of the Sea of Japan, the east part of the Southern Sea, the west part of the Southern Sea and the Yellow Sea. The coastal waters of the Sea of Japan and the east part of the Southern Sea, in generally, are rich in the phytoplankton. In the coast of the Sea of Japan, species of Chaetoceros and Bacteriastrum prevail and uncommon in species of Coscinodiscus and Rhizosolenia. In the east part of the Southern Sea, on the other hand, uncommon in species of Chaetoceros and Bacteriastrum, and species of Coscinodiscus Rhizosolenia and hemiaulus indicus prevail. The coastal waters of the west part of the Southern Sea and the Yellow sea are both poor in the phytoplankton but Coscinodiscus species prevailed comparatively.

• ALGAE
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• v.30 no.2
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• pp.103-119
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• 2015

Photosynthetic rates of the large centric diatom Coscinodiscus granii were measured by means of multicolor variable chlorophyll fluorescence imaging, single cell $^{14}C$ assimilation, and optical $O_2$ sensor measurements during light acclimatization of cultures grown at five different irradiances: 50, 150, 235, 332, and $450{\mu}mol$ photons $m^{-2}\;s^{-1}$. Photo-acclimatization was evident from changes of cellular chlorophyll a content, growth rates, and light response curves. Each of the applied methods evaluates different parts and reactions in the photosynthetic apparatus, which makes a direct quantitative comparison of rates difficult, although a different degree of correlation were found between all three methods. However, when used in combination, they provide information about the internal relationship of photosynthetic pathways as well as the variation in photosynthetic capacity between individual cells within a single algal culture.

• Journal of Plant Biology
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• v.3 no.2
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• pp.26-28
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• 1960

Electron-Microscopical Observalion on Fine Structure of Diatom Frustules which is collected in the East Coast of Kyung-Pook Province. Kor. Jour. Bot. 3(2) 26-28 lllus. 1960 The fine structure of Diatom frustules which is collected in the east coast of Yungil and Wul Sung, Kyung-Pook Province, is ovserved by the light microscope and hte electron-microscope, and the materials collected by auther are 1 family, 2 genus and 2 species. Coscinodiscus elegans. Greville Actinoptychus undulatus Rals Those were havitated in sea water as the plankton which were found in diatomite.

• Journal of Environmental Science International
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• v.12 no.7
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• pp.715-724
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• 2003

Distributional patterns of microalgae were studied in the tidal flats of Gamami Beach(Young-Gwang, Korea) from November 1999 to 2000 July. The tidal flats of Gamami Beach was composed mainly of sandy sediment. The concentrations of nutrients were low compared with other tidal flats. In the present study, 68 species of microalgal flora were identified. These were comprised of 25 species of benthic microalgae and 59 species of planktonic microalgae. Diatoms predominated the benthic microalgae with 96.0% of total species occurred. Dominant species were Amphora sp., Cocconeis sp., Coscinodiscus asteromphalus, Coscinodiscus sp., Nitzschia sigma var. intermedia, Nitzschia distans, Navicula spp., Paralia sulcata, Pleurosigma sp. Skeletonema coastatum, and Surirella sp. Among them, Amphora sp., Paralia sulcata, and species of Pleurosigma and Nitzschia were observed throughout the studied period. Planktonic microalgae of Gamami Beach was also predominated by diatoms. They occupied 88.1% of total planktonic microalgae. The density of microalgal population was higher in silty sediment than in sandy sediment. The population density of microalgae was higher in high tide zone than that in low tide zone. The density of the benthic microalgae in the surface layer of tidal flats showed increasing tendency for 2 hours after the beginning of ebb tide. On the contrary, benthic microalgal density of subsurface layer was decreased during the period. Concentrations of chlorophyll ${\alpha}$ from sediment and water were not synchronized during the study period. Therefore, the distributional patterns of the benthic microalgae and planktonic algae seemed not to be related. Chlorophyll ${\alpha}$ of water was highly related with the concentration of NH$_4$-N, whereas, chlorophyll ${\alpha}$ of sediment uas related with NO$_3$-N concentration.

• Journal of Environmental Science International
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• v.12 no.7
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• pp.725-733
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• 2003

This survey was carried out to assess important species of phytoplankton in the ocean and bay in Korea from 32 references. The number of important species assessed from 50 genera 116 species. Of them, Bacillariophycea(diatoms) 34 genera 89 speceis(76.6%), Dinophyceae(dinoflagellates) 11 genera 22 species(18.9%), Chrysophyceae 2 genera 2 species(1.7%), Cyanophycea(blue-green algae), Raphidophyceae, Euglenophyceae(euglenoids) 1 genera 1 species(0.9%) respectively. By ecological characters, the number of dominant species were 79 species including Actinoptychus seranius, 50 species including Coscinodiscus centralis were recorded as frequently apperaing species and 36 species including Cochlodinium polykrikoides were recorded as red-tide causative organism. Also, 11 species including Prorocentrum micans were surveyed as the indicator including all ecological characters.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2003.05a
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• pp.85-87
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• 2003

문헌 32편에서 조사된 출현종수는 43종에서 200종까지였고, 그 중에서 주요종수는 2종에서 27종까지로 조사되었다. 본 조사에서 기록한 주요종은 모두 50속 116종이었고, 규조류 34속 89종(76.6%), 와편모조류 11속 22종(18.9%), 황갈색조류 2속 2종(1.7%), 남조류, 라피도조류, 유글레나조류가 각각 1속 1종(0.9%)이었다. 생태적 특성을 반영하는 주요종으로서는 우점종이 Actinoptychus serunius를 비롯하여 79종, 출현빈번종이 Coscinodiscus centralis를 비롯하여 50종, 적조원인종이 Cochlodinium polykrikoides를 비롯한 36종이었다. 또한 3가지의 주요 특성을 모두 지닌 종은 Prorocentrum micans를 비롯한 11종이었다. 여러 문헌에서 주요종으로 언급했던 종은 규조류인 Skeletonema costatum이었고 단일 속(genus)으로서 18종의 많은 종이 조사된 속은 Chaetoceros속이었다.

• Ocean and Polar Research
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• v.28 no.2
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• pp.95-105
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• 2006

To clarify the seasonal changes of the phytoplankton community in seagrass beds, the abundance and distribution of phytoplankton, and environmental factors were measured in seagrass beds: in the Dongdae Bay and Aenggang Bay on the southern coast of Korea, and off Seungbong Island on the western coast of Korea, in October 2002, January, March, and June 2003. Water temperature, salinity, SPM, chlorophyll a, aboveground biomass of seagrass, DIN and DIP concentrations significantly changed within the sampling time. The taxa of phytoplankton observed in seagrass beds were classified as 3 divisions, 3 classes,4 orders,16 families, 27 genera, 65 species. 50 species of diatoms were recognized with 14 species of dinoflagellates, and 1 species of silicoflagellate. The species of genera Coscinodiscus and Thalassiosira were dominant all around the study areas but Peridinium granii, Eucampia zodiacus and Pleurosigma elongatum were seasonally dominant. Phytoplankton standing crops varied from minimum of $0.6{\times}10^3\;cells\;l^{-1}$ (June, Dongdae Bay) to maximum$21.1{\times}10^3\;cells\;l^{-1}$(March, Aenggang Bay). The standing crops and species composition of phytoplankton were relatively lower and simpler than those of other southern and western coastal areas. Seasonal variations of diatom standing crops in seagrass beds were attributed to seasonal changes in DIN and in DIP of water column.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.8
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• pp.579-592
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• 2020

This study was designed to assess the water quality and phytoplankton community including chlorophyll a in blood cockle (Tegillarca granosa) farms in May, August and November of 2017 in the northwestern Yeoja Bay, Korea. As a result, the seasonal characteristics of water types by water temperature and salinity were clear. Nutrients were abundant in silicate throughout the season, but phosphate was scarce in spring and summer, and nitrogen sources were scarce in autumn. The species composition of phytoplankton community was a very simple distribution, and the standing crop was also very low. The annual dominant species is dominated by the diatoms, with Skeletonema costatum-ls, Nitzschia longissima in spring, Pleurrosigma normanii, Coscinodiscus gigas in summer, and N. longissima, Pseudonitschia pungens, Chaetoceros curvisetus, Eucampia zodiacus in autumn. In summer the results were different from other coastal waters of Korea. The principal component analysis(PCA) and correlation analysis showed that the characteristics of water quality and biological environments differed according to the season. Furthermore, it was determined by the supply of materials through fresh water on land, seawater congestion caused by the refueling of surface sediments with lower depth, and the balance of biological production and mineralization of organic matters in blood cockle farms.