• ALGAE
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• 제21권4호
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• pp.471-477
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• 2006

Amphora costata W. Smith 1853 is a down thrown diatom species and also known as metal corrosive ship-fouling organism. A. costata was isolated from Alang ship breaking yard, Alang and evaluated the toxicity tolerance and growth responses of the cultures exposed to different doses of toxic and relatively accessible heavy metals, such as Fe, Mn, Cd, Co, Cu, Zn, Ni, and Pb in the constantly monitored laboratory culture conditions. The strongest toxic effect was observed on A. costata exposed to Cd even at relatively low concentrations as compared to other metals. The following trend of decreasing order of toxicity i.e. Cd>Zn>Ni>Co>Pb>Cu>Fe was observed, when they were exposed to equal concentration and expose time.

• 한국해양학회지
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• 제26권1호
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• pp.24-37
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• 1991

Marine benthic diatoms and environmental factors were studied at 60 sites on the Mangyung-Dongjin tidal flat of the west coast of Korea. Sediment samples were taken quantitatively from the upper 5 mm layer to obtain a representative estimate of the epipelic and epipsammic cell concentration. Surface sediments taken simultaneously with the quantitative diatom samples were analysed for the grain size. Exposure duration of study sites were calculated by the tide data recorded at Kunsan Outer-Harbour. Coarse sediments dominated mainly on the offshore coastal and lower tidal flat, whereas fine sediments occurred on inner and higher tidal flat. Total 371 diatom taxa were collected and the genera represented by a great number were Navicula and Nizschia. The 16 abundant species occupying more than 1% of total cell number are of the following: Paralia sulcata, Navicula sp. 1, Navicula arenaria, Cymatosira belgica, Amplora holsatica, Amphora coffeaeformis, Achnanthes hauckiana, Rhaphoneis amphiceros, Thalassionema nitzschioides. Navicula sp. 2, Dimeregramma minor, Amphora sp. 1, Cyclotella atomus, C, striata, Nitzschia kuetzingiana, Stephanodiscus sp. 1. The distribution pattern of these dominant species are described in relation to the habitat condition. Most of these species showed high densities in fine sediments. However, they occurred even silty sand and sandy sediments in low abundance. The epipsammic forms belonging to the Araphidineae and Monoraphidineae were restricted on the lower tidal flat. The typical species found in coarse sediments were: Cocconeis sp. 1, Opephora martyi, Amphora sabyii, Dimeregramma minor var. nana, Fragilaria virescens var. oblongella, F. virescens, Cocconeis grata. The higher tidal flat consisting of fine sediments showed relatively higher cell numbers than the lower tidal flat. River mouth region was the highest in abundance.

• ALGAE
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• 제21권1호
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• pp.141-148
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• 2006

Benthic diatoms are known as a good food for shellfish in nature and in commercial hatchery of Jeju Island, Korea. Grammatophora marina is commonly found as dominant benthic micro-algae in Jeju coastal waters throughout the year. To know the best growth conditions of this species, culture was done in terms of three parameters; water temperature, salinity and nutrients. Each parameter was controlled by temperature of 15, 20 and 25°C; salinity of 25, 30 and 35 psu; and nutrient concentrations of 50, 100 and 200%. F/2 media was used with artificial seawater for the culture, which was continued for two weeks with L:D cycle 12:12 by using fluorescent light. Maximum specific growth rate was recorded 1.68 d–1 at temperature of 25°C with salinity of 35 psu and nutrient concentration of 200% on 6th day during the culture period. Maximum biomass was also observed 4.9 × 105 cells mL–1 in the same condition. This species may belong to the euryhaline and eutrophic habitat with warm condition. For nutritional aspects of this species, protein, lipid and carbohydrate were measured. The value of protein, lipid and carbohydrate was 4.96%, 15.82% and 5.65%, respectively. The antioxidant activities of 80% methanolic extract were 46.7%, 23.7% and 23.8% on DPPH (1,1-Diphenyl-2-picrylydrazy) radical, superoxide anion radical and hydrogen peroxide scavenging, respectively. Percentage metal chelating activity was 81.2%. Enzymatic extracts of Alcalase and Ultraflow showed remarkable scavenging activities on DPPH radical (86.5% and 57.2%, respectively), and superoxide anion scavenging activities were 45.3% and 41.4% from Kojizyme and Viscozyme extracts, respectively. Extract of Protomex revealed 24.8% activity on hydrogen peroxide and Neutase showed 30.8% on hydroxyl radical scavenging effects. Celluclast and Viscozyme extracts showed 33.2% and 32.1% activities on nitric oxide scavenging, respectively, while Alcalase showed 61.5% on metal chelating. This species contains higher lipids among the biochemical compounds and higher metal chelating activities from both 80% methanolic and enzymatic extracts.

• 한국해양학회지
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• 제22권4호
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• pp.257-270
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• 1987

Fouling communities developing in Jinhae Harbor and Masan Bay were studied by slide and panel immersion test during the period from Dec., 1982 to Nov., 1983. The total viable count of bacteria was estimated more than 1.7${\times}$ 10$\^$4/CFU/$\textrm{cm}^2$ after 15 days of immersion and 46 taxa of benthic diatoms were classified in micro-community. Progressional change of fouling communities was clearly shown and dominant diatom species are Licmophora flavellata, Navicula grevillei, and Nitzschia closterium Major macrofouling organisms are Mytilus edulis, Balanus amphitrite amphitrite, Hydroides ezoensis, and Celleporina sp. Wet weight production of macrofouling organisms exceeds 500g/100cm$\^$2/ after 5months of immersion. Regional defferences in community development are clearly shown in two study areas, and mainly due to the disparities of physicochemical stability and nutritional status of ambient water. Seasonality of larvae and the growth rate are the important factors in fouling community development. Overall process of community development is as follow : bacteria and diatoms-multicellular algae-barnacle, mussels and polychaete-sponge, anemone and ascidian.

• 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.

• Korean Journal of Fisheries and Aquatic Sciences
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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.

• Korean Journal of Ecology and Environment
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• 제56권4호
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• pp.414-419
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• 2023

Aquatic ecosystem is composed of various organic and inorganic matters. Its health is essential for sustaining its members such as vegetations, mammals, birds, fishes and invertebrates. Samcheonpo stream is one of candidate streams in Sacheon area of ecological restoration. For this reason, this study conducted to build up a data base for future comparison. The results shows that biodiversity of Epilithic Diatoms and Invertebrates is below average which means that human impacts such as artificial structures and activities have been negatively related to stream health. Consequently, we suggest several key factors when ecological restoration is performed in the stream.

• Journal of Ecology and Environment
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• 제37권4호
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• pp.245-255
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• 2014

To collect the diatom species belonging to the genus Hantzschia, bottom sediments were collected from 32 sampling sites in 23 sand-flat areas in the intertidal zone and river reaches of Nakdong River estuary, Korea. The sand sediments contained a total of 19 species of genus Hantzschia, Hantzschia amphioxys (Ehrenberg) Grunow, H. amphioxys f. capitata O. Muller, H. baltica Simonsen, H. distinctepunctata (Hustedt) Hustedt, H. elegantula (Østrup) Witkowski et al., H. longiareolata Garcia-Baptista, H. marina (Donkin) Grunow, H. pseudomarina Hustedt, H. virgata (Roper) Grunow, H. virgata var. gracilis Hustedt, H. virgata var. kariana Grunow, H. virgata var. leptocephala Østrup and H. weyprechtii Grunow, including six unconfirmed species. Eleven Hantzschia species are reported as new to Korea. Hantzschia virgata, its infraspecies, and neighboring speceis showed large morphological variations within a single species or among the closely related species. Hantzschia amphioxys, H. distinctepunctata, and H. virgata var. leptocephala prefer freshwater habitats in the upper reaches of the river, while others occurred mainly in the sand flats composed of coarse sand in the intertidal area. In the estuarine sediments, the Hantzschia taxa are classified to be typical sand-attached forms.

• Korean Journal of Ecology and Environment
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• 제35권2호통권98호
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• pp.141-144
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• 2002

The construction of river mouth dam has prevented seawater from backwarding to upstream in Kum river estuary since 1990. Field observation on environmental factors, and zooplankton and phytoplankton dynamics have been carried out three times with two month interval in the summer and autumn in 2000 at three selected stations in Kum river estuary. Blockade of seawater flowing backward to upstream caused sharp contrast of zooplankton fauna and phytoplankton flora between upstream and downstream of the river mouth dam. Freshwater cladocerans i.e., Bosmina longisrostris and Daphnia galeata dominated in the upstream, and marine copepods of Acartia omorii and Paracalanus crassirostris occurred abundantly in downstream of the dam. Freshwater diatoms did not distributed in the downstream of the dam except Melosira varians, while marine diatom of Cylidrotheca closterium occurred in benthic waters bath in upstream and downstream of the dam. The construction of the river mouth dam seems to play an ecological role to blockade the input of marine organism into the upstream in Kum river estuary.

• Journal of the Korean Society of Marine Environment & Safety
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• 제24권7호
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• pp.898-906
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• 2018

To investigate the effect of yellow dust on phytoplankton, a field survey and physiological experiments were carried out in the waters near Taean Peninsula from April 22 to 26, 2006, when yellow dust occurred. Phytoplankton populations during the yellow dust period were in the range of $26{\sim}290{\times}10^3cells{\cdot}L^{-1}$, a somewhat low standing crop. An increase in diatoms (a main taxonomic group), especially benthic diatoms such as Paralia sulcate, a typical species for active mixed sea water areas, was also remarkable. In addition, the Chl-a concentration after yellow dust exceeded the Chl-a concentration change range according to the tide before yellow dust. As the concentration of yellow sand increased in a yellow sand treatment experiment, primary productivity decreased, and the maximum assimilation number showed the same tendency. In the 48h culture experiment, primary productivity of the test group was lower than that of the control group at the early stage (T0) of yellow sand treatment, but after 48 hours (T48), the test group showed higher primary productivity than the control group. In particular, the primary productivity of the test group significantly increased to 321 % after 48 hours. Therefore, strong physical environment accompanied by yellow dust may temporarily inhibit the growth of phytoplankton in the waters adjacent to China in the early stage of yellow dust, but the formation of stable water mass has also been identified as a potential factor promoting the growth of phytoplankton.