• ALGAE
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• v.23 no.3
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• pp.187-199
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• 2008

A study on the fine structure of the marine diatom Thalassiosira has been carried out during the periods from January 2007 to March 2008 in Korean coastal waters. As the third series of the Thalassiosira species, a fine structure, description, distribution and taxonomic remarks of the six Thalassiosira species were observed by means of light microscope and scanning electron microscope. The critical features of Thalassiosira species were a shape of external tubes of marginal strutted processes and labiate process. Six species showed each different shape of external tubes, marginal strutted processes and labiate process. The shape of external tube was divided into five types: T shape of Thalassiosira curviseriata, small-rounded shape of T. lundiana, double-layer form and flame shape of T. nordenskioeldii, tulip shape of T. punctigera and tooth-shape of T. tenera. This external character may be able to key character for positive identification of the Thalassiosira species. Of these Thalassiosira lundiana, T. minuscula and T. tenera were new records for Korean coastal waters.

• 한국해양학회지
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• v.21 no.3
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• pp.184-192
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• 1986

A study on the fine structure of the marine diatom has been carried out for taxonomical purpose during the period from Fib. 1982 to Feb. 1986 in Korean coastal waters. Fine structure of small Thalassiosira (Bacillariophyceae) was studied by means of light and scanning electron microscopy. Firstly, four species of Thalassiosira were identified and described. Of these Thalassiosira weissflogii, T.minima and T.oestrupii var venrickae were new records for Korean coastal waters.

• 한국해양학회지
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• v.22 no.3
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• pp.179-190
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• 1987

A study on the fine structure of the marine diatoms has been carried out for taxonomical purpose during the periods from September 1983 to March 1987 in Korean coastal waters. Fine structure of smallThalassiosira(Bacillariophyceae) was studied by means of light microscope and scanning electron nisroscopy. Secondarily, six species of Thalassiosira were identified and described. Of these Thalassiosia allenii, T. binata and T. conferta were new records for Korean coastal waters. Thalassiosira aestivalis, T.allenii, T.binata, T.conferta, and T. pacifica have a valve with a single labiate process and one central and one marginal ring of strutted processes, but T.rotula has many central strutted processes close together instead of one central strutted process.

• ALGAE
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• v.25 no.3
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• pp.121-131
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• 2010

Thalassiosira species were collected from October 2007 to January 2009 in an attempt to better understand species diversity of the genus Thalassiosira in Korean coastal waters. A total of 5 Thalassiosira species (T. concaviuscula, T. oceanica, T. partheneia, T. simonsenii and T. nanolineata) were identified here. Most species in this study were of small size, and 5 species were recorded for the first time in Korean coastal waters. Using a scanning electron microscope (SEM), we described distinctive characteristics of fine structure that proved to be important diagnostic characteristics for the identification of each species. The most important diagnostic characteristics for Thalassiosira species identification were the marginal strutted processes, the position of labiate processes, and the areolation. The differential characteristics of the species studied were: T. concaviuscula has a double layered external tubes on the marginal strutted processes; T. oceanica shows marginal ridges that are interlinked between the marginal strutted processes; the valve face of T. partheneia is fairly convex and its labiate process is positioned midway between two strutted processes; T. simonsenii is characterized by two labiate processes and somewhat coarse areolae; and, T. nanolineata has several central strutted processes and linear areolation.

• Ocean and Polar Research
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• v.27 no.2
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• pp.149-159
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• 2005

Samples were collected from five stations in February, May, July, and September 2004 to investigate seasonal variations in the phytoplankton community and the relationship between dominant genera and environmental factors in Asan Bay. In February, microphytoplankton contributed 80% to the total chlorophyll a. Diatom dominated the phytoplankton community, accounting for 85.9% of the total cell number, followed by dinoflagellates (6%). Dominant species were Skeletonema costatum and Thalassiosira spp. Abundant diatom, including S. costatum and Thalassiosira spp., may be affected by water temperature and silicate at Station 1 and 2 in February 2004. In May, the nanophytoplankton contribution to total phytoplankton was higher than in other seasons. However, abundance of S. costatum and Thalassiosira spp. decreased, since the growth of S. costatum and Thalassiosira spp. might be limited by phosphates (P) resulting from low P concentration and a high DIN:DIP ratio in the outer region. In July, dominant phytoplankton groups were diatom (39%), cryptophyceae (28%), and cyanophyceae (20%). Dominant genera were Oscillatoria spp. and phytoflagellate of a monad type in the inner region (Station 1 and 2), whereas S. costatum was dominant in the outer region (Station 4 and 5). In September, dominant phytoplankton were diatom (69%) and cryptophyceae (28%). Dominant genera were phytoflagellate of the monad type, S. costatum in the inner region, while Chaetoceros spp. was dominant in the outer region.

• Journal of the Korean earth science society
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• v.36 no.2
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• pp.190-197
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• 2015

This study investigated the paleoclimatic change using diatoms that were extracted from the high-resolution laminated layers of diatom ooze sediment cores GC08-EB01 in the eastern basin of the Bransfield Strait, Antarctica. The range of diatom valves per gram of dry sediment was from $0.4-4.2{\times}10^8g^{-1}$ in quantitative diatom assemblage analysis. Laminations are classified using visually dominant diatom species and terrigenous content. Biogenic diatom ooze laminae characterised by bloom of Corethron crilophilum, Eucampia antarctica, Fragilariopsis curta, F. kerguelensis, Odontella weissflogii, Proboscia inermis, R. styliformis, Thalassiosira antarctica, and Chaetoceros resting spores. Terrigenous laminae characterised by mixed diatom assemblage. The ratio of (Fragilariopsis curta+F. cylindrus)/Thalassiosira antarctica increase in horizons, suggesting increased sea-ice cover in the study area during the late Holocene (cold events). As a result, five cold events are identified on the basis of frequency of the critical taxa throughout the section.

• Journal of Ecology and Environment
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• v.37 no.4
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• pp.225-229
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• 2014

Feeding behavior of Temora turbinata was investigated through laboratory experiments with special emphasis on its food preference and consequent clearance rate on diatom and microbial components given as common natural food assemblage of coastal area (Uchiumi, Uwa Sea, Japan). Among available prey items, T. turbinata showed the highest clearance rate for Thalassiosira spp. ($0.23{\pm}0.08L\;Temora^{-1}day^{-1}$) followed by Chaetoceros spp. ($0.11{\pm}0.03L\;Temora^{-1}day^{-1}$), but clearance rates for other diatom, Nitzschia spp. was lower (0.03 to $0.07L\;Temora^{-1}day^{-1}$). Bacterial abundances showed no response against 24-h feeding of T. turbinata. Feeding of T. turbinata on heterotrophic nanoflagellates (HNF) was apparent when clearance rates of T. turbinata on diatoms were relatively low, but T. turbinata did not consume HNF as well as ciliates with Thalassiosira spp. of which clearance rate was highest. The results suggest that HNF and ciliates are possible supplementary prey item for T. turbinata, but their contribution as food sources can be limited by the presence of other prey items such as preferable diatom species.

• Korean Journal of Environmental Biology
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• v.30 no.3
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• pp.245-271
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• 2012

A study on the indigenous diatoms was carried out at 103 sites during August 2008 to April 2011 from the marine and the brackish waters in Korea. A fine structure of small-sized diatoms was examined using a light and scanning electron microscopy. Sixty species of diatoms were newly identified and composed of 3 class, 6 subclass, 16 order, 21 family and 39 genus. The detailed nomenclatures, references, photographs and distributions were here reported. Of 60 species, the most frequent species was Tryblionella coarctata appearing 24 times, and 22 times followed by Thalassiosira lacustris, Cocconeis stauroneiformis was 20 times. In the level of genus, Chaetoceros, Parlibells and Thalassiosira were included 4 species, Actinocyclus, Minidiscus and Licmophora were included 3 species. This study will provide the knowledge of the diversity level of diatom in Korea, the knowledge is important on the diatoms for further studies.

• ALGAE
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• v.18 no.4
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• pp.361-363
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• 2003

This study was conducted at Seomjin River estuary to identify the causative species of algal bloom and their blooming cycles. Field surveys were conducted at 4 stations in every week from April to December of 1999. Thirty species were observed as the causative species of alga bloom. Skeletonema costatum, Thalassiosira sp., and microflagellate spp. (mixed red tide: Chroomonas sp. and two species of Prasinophycea) made algal blooms during the present study period. In addition, toxic algal species of diatom Pseudo-nitzschia multiseries and dinoflagellate Dinophysis acuminata were observed. The algal blooms were caused by microflagellate spp. in June, Thalassiosira sp. in July and Skeletonema costatum in August. Generally, the algal blooms persisted for about 5 days in this area.

• ALGAE
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• v.24 no.2
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• pp.67-77
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• 2009

The marine phytoplankton diatom Thalassiosira species are described from the Korean coastal waters, based onobservations of Fine structutre of its frustules. As a fourth series, this study deals with 5 Thlassiosira species (T. decip-iens, T. ecgentrica, T. mala, T. nodulolinmta, and T. proschinae). The most striking features of these species are also theform and position of two processes on frustules. There is a central strutted process on valve face except T. nodvlolin-eata, which has a modified one on its center. The extemal tubes of marginal strutted processes are divided twoforms: "pile" form in T. decipiens and T. proschkinae, "short straw" form in T. eccentrica and T. nodulolineata. T. maladoes not present the extemal tubes in valve margin. The labiate processes are located in valve margin except T.proschkinae, which has it on valve face. Of theae, thrce species (T. mala, T. nodulineata at a final contentration of 5%and T. proschkinae were newly recorded in the coastal waters of Korea.