• Journal of Environmental Science International
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• v.17 no.10
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• pp.1155-1167
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• 2008

Chlorophyll a (chl a) has been used as an indicator for phytoplankton biomass in pelagic ecosystems due to the relative ease of measurement and selectivity for autotrophs in mixed plankton assemblages. However, the use of chi a as an indicator for phytoplankton biomass is restricted due to its inability to resolve taxonomic differences of phytoplankton and the highly variable relationship of chi a with phytoplankton. Here, we describe the analysis of High-Performance Liquid Chromatography (HPLC) photosynthetic pigment data using CHEMTAX, which is a matrix factorization program that uses chemical taxonomic indices (phytoplankton carotenoids) to quantify the abundance of phytoplankton groups. Compared to direct microscopic counting that can distinguish species within broad groups, the resolution of taxonomic groups by CHEMTAX is generally coarse. It can only distinguish between diatoms, dinoflagellates, cryptophytes, cyanobacteria, chlorophytes, prasinophytes, and haptophytes. However, CHEMTAX analysis is much faster and less expensive than microscopic counting methods. HPLC pigment observations were taken in the spring, summer, fall, and winter in$ 2005\sim2006$ within Gamak Bay, South Korea. CHEMTAX results revealed that diatoms were the dominant taxonomic group in Gamak Bay. In inner Gamak Bay, the ratio between diatoms and cryptophytes was $75\sim80%$, and the ratio between dinoflagellates and cryptophytes was $10\sim15%$. In outer Gamak Bay, the ratio between diatoms and cryptophytes was $85\sim90%$, and the ratio between dinflagellates and cryptophytes was only $1\sim5%$. The population structure was seasonal. Relative diatom populations were less in the summer than the winter season.

• The Korean Journal of Malacology
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• v.32 no.3
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• pp.165-174
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• 2016

Feeding behaviour of the manila clam Ruditapes philippinarum was qualitatively and quantitatively characterized by comparing the contents composition in digestive tract of the clam and the phytoplankton community in surface sea water in Gomso Bay, west coast of Korea. The contents of digestive tract comprised diatoms (71.5%), dinoflagellates (13.1%), nannoplankton (6.6%), and detritus including mesozooplankton. The abundance of food organisms in digestive tract of the clam was high in winter and spring, while low in summer and autumn. But The biomass of phytoplankton in surface sea water revealed the highest value in autumn. Also, the larger the clam size increases the abundance of food organisms in digestive tract. The dominant species in digestive tract were Paralia sulcata and Navicula arenaria such as benthic diatoms and dinoflagellate cysts, whereas the dominant species in surface sea water were Chaetoceros, Skeletonema, Asterionellopsis such as pelagic diatoms in genus, cryptomonads, and P. sulcata. Analyses of digestive tract revealed that benthic diatoms especially represent an important constituent of food organisms in the malina clam and different of phytoplankton size and morphology explain preference for food selectivity.

• ALGAE
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• v.25 no.3
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• pp.133-140
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• 2010

Using chlorophyll fluorescence, the vertical migration of benthic diatoms responding to light intensity and affected by sediment grain size was studied. Minimal fluorescence ($F_o$) of surface sediment was measured by imaging pulse amplitude modulated (Imaging-PAM) fluorometer, and used to monitor diatom biomass variation in surface sediments. The test diatoms, Amphora coffeaeformis (C. Agardh) K$\ddot{u}$tzing and Cylindrotheca closterium (Ehrenberg) Reimann & Lewin, migrated to the sediment surface under irradiance from 50 to 500 ${\mu}mol$ photons $m^{-2}s^{-1}$. However, the diatoms exhibited no evident increase of surface biomass under dark conditions, and even showed slightly decrease of surface biomass under irradiances over 1,000 ${\mu}mol$ photons $m^{-2}s^{-1}$. The light intensity inducing the maximum surface migration of A. coffeaeformis was 100 ${\mu}mol$ photons $m^{-2}s^{-1}$, while the light intensity producing the same effect for C. closterium was 250 ${\mu}mol$ photons $m^{-2}s^{-1}$. C. closterium showed higher motility than A. coffeaeformis. Faster diatom surfacing was observed in larger grain size sediments (125-335 ${\mu}m$) than smaller ones (63-125 ${\mu}m$). This study confirmed the significant influence of light as a main triggering factor behind migration, indicated the distinct effect of different sediment grain size, and highlighted the species-specific migratory ability.

• 한국해양학회지
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• v.21 no.1
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• pp.25-33
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• 1986

Ontogenetic food habits of the four most abundant fish species in seagrass neadows of Redfish Bay, Texas, were examined quantitatively during 1982-1983. The darter goby (Gobionellus bolelsoma) and pinfish (Lagodon rhomboides) were trophic generalists, which used a wide range of food items. The darter goby had relatively diverse, omnivorous diet which included amphipods, copepods, polychaetes, filamentous algae, diatoms, and detritus. This species did not show distinct ontogenetic changes in foodpreferences. Unlike the darter goby, the pinfish showed ontogenetic progression of four feeding stages. An initial feeding stage was a planktivorous stage in which copepods were int major food items, followed by a carnivorous stage in which amphipods became the major food items, an omnivorous stage in which filamentous algae, diatoms, amphipods, and polychaetes were the major food items, and finally a herbivorous stage in which seagrass pieces with attached epiphytes and their debris were the major food items. The code goby (Gobiosoma robustrm) and Gulf pipefish (Syngathus scovelli) appeared to be relatively specialized in food havits as carnivorous. Similar ontogenetic changes in food habits were observed for these two species, i.e.initially, copepods were the major food items, followed by a gradual transition to amphipods with growth.

• 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.

• Journal of Korean Society on Water Environment
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• v.25 no.6
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• pp.879-885
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• 2009

The present study was carried out to develop biological criteria for water quality assessment using benthic diatoms. Selecting of the indicator diatoms, three parameters were considered: broad distribution (180 taxa occurred over 3% at upper level), species abundance (158 taxa occurred over $1.5{\times}10^5cells/cm^2$), and sensitivity (184 taxa occurred more than once as 1st and 2nd dominant species). Overall, total 208 taxa were selected, including 38 varieties, 170 species, 34 genera, 9 families, 3 orders, and 1 phylum. The most dominant taxonomic group (family) was Naviculaceae (52%), followed by Diatomaceae (15%), Nitzschiaceae (12%) and Achnantaceae (11%). COD and TP were proposed as new water quality standards (draft) to improve the existing BOD standard and to manage and control efficiently non-biodegradable organic pollutants. With this regard, we used TP standard (draft) in developing biological water quality criteria for diatoms. TP standards (draft) proposed as Ia = 0.02 mg/L or less, Ib = 0.05 mg/L or less, II = 0.1 mg/L or less, III = 0.2 mg/L or less, IV = 0.4 mg/L or less, V = 0.6 mg/L or less and VI = above 0.6 mg/L. Biological assessment system (4 class system) was developed and proposed for diatom using modified Tropic Diatom Index (TDI). Biological assessment of TDI appear B grade (Good).

• Journal of The Geomorphological Association of Korea
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• v.24 no.2
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• pp.79-90
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• 2017

This study investigated the correlation between the diatom community and the environmental variables on the tidal flat surface of the eastern part of Gomso Bay in the West coast of Korea in order to utilize the quantitative sea level record as a basic data. 24 sediment samples at 10cm intervals downstream of the Galgok Stream were used for diatom analysis, grain size analysis and CCA. As a result of diatom analysis, marine diatoms dominated at lower altitudes and the ratio of diatoms to fresh water diatoms and brackish diatoms increased toward upland. As a result of CCA, the contribution of environmental variables was analyzed as 25.3% at altitude, 21.6% at sand, 13.3% at skewness, etc. This means that altitude above sea level has the greatest influence on the diatom composition in the tidal flat surface. It suggests that the contribution of environmental variables at altitude above sea level can be used as a basic data for the quantitative records for reconstruction of paleo-sea level.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.26 no.3
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• pp.238-247
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• 2021

Diatoms are a type of microalgae which inhabits a wide variety of environments as one of the most important primary producers of freshwater and marine ecosystems. They have been widely used as bioindicators which represent the environmental characteristics, thus proper quality control of diatom data is very important to ensure for the researches from many scientists from various different regions to have scientific unity and objectivity. At present, diatom data analysis is primarily based both on morphological features and DNA sequences of given species. Challenge for the morphology-based analysis of diatoms is the consistent species identification among different taxonomists who interpret diatom community, while challenge for the molecular analysis of diatoms to secure reliable reference data. In the present study, we have reviewed the current status of data quality control of diatom analysis in Korea as well as the world. Finally, suggestions for the better data quality control for Korean marine diatoms have been also made.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.25 no.4
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• pp.160-172
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• 2020

To understand on-site feeding traits of Noctiluca scintillans with unprecedented high abundances around Dokdo in spring, 2014, the composition and abundance of food items in the digestive vacuole of the species were analyzed. Abundances of N. scintillans ranged from 4,328~17,791 inds.m^-3 around Dokdo during the study. The incidence of preyed items in the vacuole of N. scintillans ranged by averaged 32% (24~50%) in the surface waters around Dokdo. Diverse preyed items consisted of fecal pellet, protozoans, pollen, diatoms, dinoflagellates, copepods and ichtyoplankton, while fecal pellets were dominantly fed by N. scintillans (43%) and next by protozoans (19%), pollen (18%), diatoms (7%) and dinoflagellates (4%). Fecal pellet, protozoans and pollen were relatively preferred by N. scintillans compared to diatoms, dinoflagellates and ichtyoplankton based on the incidence in the food vacuoles. Present results indicated that high abundance of N. scintillans found around Dokdo was likely associated with non-phytoplankton items rather than previously well-known diatoms as prey during the study.

• Journal of the korean society of oceanography
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• v.37 no.2
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• pp.58-65
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• 2002

The study of microbial communities in sediments is impaired by the lack of reliable extraction methods. This study reports on the efficiency of recovery of a method for extracting bacteria, protists and diatoms from sandy sediments using a modified decant/fix method. The best extractions were achieved after fixation with a microtubule stabilising fixative and subsequent sonication for 80 seconds. We estimate that the efficiencies of recovery of bacteria and mixed heterotrophic flagellates were $96.4{\pm}3.5\%$ and $96.9{\pm}4.6\%$, respectively. Diatoms were recovered with an efficiency of 38-83% and varied considerably from species to species. This study suggests that the decant/fix method is effective in extracting small cells such as bacteria and heterotrophic flagellates, and that the efficiency of recovery of the method varies due to cell length and different types of organisms. When microbial carbon biomass had been underestimated by up to 32%, with much of that relating to larger cells such as microalgae and ciliates. We note that the corrected abundances may be still a subset of the total numbers present.