• Journal of the Korean Society for Marine Environment & Energy
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• v.14 no.2
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• pp.130-137
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• 2011

To improve sediment quality in eutrophic coastal areas using benthic microalgae, we examined the effects of temperature and salinity on the growth of benthic microalgae Achnanthes sp., Amphora sp., Navicula sp. and Nitzschia sp. isolated from Sujeong Bay, Korea, using batch cultures. The maximum growth rates were obtained under the combined temperature and salinity conditions of $25^{\circ}C$ and 25 psu for Achnanthes sp. (0.60 /day), $15^{\circ}C$ and 25 psu for Amphora sp. (0.56 /day), $20^{\circ}C$ and 30 psu for Navicula sp. (0.53 /day), $20^{\circ}C$ and 25 psu for Nitzschia sp. (0.48 /day). Considering these results of temperature and salinity conditions required for optimum growth (${\geq}$ 70% of maximum specific growth rate), Amphora sp. Navicula sp. and Nitzschia sp. were characterized as eurythermal and euryhaline species, while Achnanthes sp., which exhibited extremely low survival at low temperature. In conclusion, Amphora sp., Navicula sp. and Nitzschia sp. may be useful species for phytoremediation, to control eutrophication and hypoxic water and thus improve environmental conditions of polluted coastal areas.

• Journal of Environmental Science International
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• v.21 no.1
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• pp.105-111
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• 2012

The effects of substrate size on the growth of microphytobenthos Achnanthes sp., Amphora sp., Navicula sp. and Nitzschia sp. were examined using glass beads in order for phytoremediation in the benthic layer of coastal waters. The glass beads used in this study were 0.09~0.15 mm (G.B 1), 0.25~0.50 mm (G.B 2), 0.75~1.00 mm (G.B 3) and 1.25~1.65 mm (G.B 4). No addition of glass bead used as control. The specific growth rate and maximum cell density of four microphytobenthos species were increasing with decreasing size of glass beads. Moreover, the control experiment without added attachment substrates showed the lowest specific growth rate and maximum cell density. Therefore, the suitable attachment substrates for mass culture of microphytobenthos seems to be important in order for phytoremediation using microphytobenthos.

• ALGAE
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• v.29 no.2
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• pp.57-73
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• 2014

Amphora Ehrenberg ex Kutzing sensu lato is a common and widespread benthic diatom genus with a taxonomy that has been under continual revision, particularly based on molecular analyses. Although Amphora species have been studied using modern microscopy in recent years, there has not been much progress on molecular characterization of the species, especially in Asia. In this study of Amphora, sampling was carried out from September 2009 to August 2010 in Korean coastal waters. The morphological and molecular characteristics of eight Amphora sensu lato were examined: Amphora marina, A. proteus, Halamphora costata, H. coffeaeformis, H. eunotia, H. holsatica, H. terroris, and Halamphora sp. Based on previous accounts, morphology suggested that A. marina and A. proteus belong to the subgenus Amphora Cleve, which have smooth girdle bands and rather coarse and very distinct areolae on the valve. The other species, H. coffeaeformis, H. costata, H. eunotia, H. holsatica, H. terroris, and Halamphora sp. belong to the subgenus Halamphora Cleve, which was recently elevated to generic status by Levkov 2009, have plicate girdle bands, puncta which do not form straight longitudinal lines, valves which have a narrow ventral portion and apices that are generally rostrate-capitate and recurved. In agreement with analysis based on morphological characteristics, phylogenetic analysis based on small subunit rDNA suggested that the eight Amphora sensu lato species were not a monophyletic group as the morphological classification. Also, the results of molecular work and statistical analysis on all these Amphora sensu lato combined with phylogenic analysis on our geographically representative samples give strong evidence that Halamphora Levkov is independent of Amphora Cleve. Furthermore, in this study, Amphora terroris was transferred Halamphora as Halamphora terroris (Ehrenberg) Wang comb. nov. and Amphora marina was recorded for the first time in Korea.

• 한국해양학회지
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• v.26 no.1
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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.

• Preventive Nutrition and Food Science
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• v.13 no.3
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• pp.166-175
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• 2008

In this study, we focused on natural water-soluble antioxidants from the Jeju benthic diatoms, Achnanthes longipes, Navicula sp. and Amphora coffeaeformis. They were prepared by enzymatic digestion using five carbohydrases (Viscozyme, Celluclast, AMG, Termamyl and Ultraflo) and five proteases (Protamex, Kojizyme, Neutrase, Flavourzyme and Alcalase) and their potential antioxidant activity was assessed. Among the enzymatic digests, Neutrase digest from A. coffeaeformis exhibited the highest effect in DPPH radical scavenging. Flavourzyme (48.7%), Viscozyme (47.4%) and Celluclast (45.7%) digests from Navicula sp. exhibited higher $O^{{\cdot}-}_2$ radical scavenging activity. Viscozyme digest from A. coffeaeformis (45.9%) possessed the highest effects in hydroxyl radical scavenging. Termamyl (89.3%) and Protamex (88.8%) digests from A. coffeaeformis had strong metal chelating activity. Lipid peroxidation was significantly inhibited in Termamyl and Kojizyme digests from A. longipes, AMG and Termamyl digests from Navicula sp. and Kojizyme digest from A. coffeaeformisi. These data suggest that enzymatic digests of the Jeju benthic diatoms might be valuable sources of antioxidant which can be applied in food and pharmaceutical industry.

• ALGAE
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• v.24 no.1
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• pp.47-55
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• 2009

Recently, interest in plant-derived food additives has developed natural antioxidants, in order to alternate syn-thetic antioxidants with several disadvantages. In the present study, different organic fractions from solvent parti-tions of 80% methanol extract from Jeju benthic diatoms, Achnanthes longipes, Navicula sp. and Amphora coffeaeformis was assessed for their potential antioxidant effects. Among the solvent fractions tested, n-hexane (80.4%) and 80% methanol extract (76.6%) from A. longipes, chloroform (63.2%) from Navicula sp. and n-hexane (67.4%) from A. cof-feaeformis were effective in DPPH free radical scavenging. Fractions of chloroform (53.4%) and n-hexane (53.1%) from A. longipes exhibited higher activities on $H_2O_2$ scavengin. Fraction of n-Hexane from A. longipes exhibited the highest hydroxyl radical scavenging activity and NO. scavenging activity (56.5% and 75.6%, respectively). Aqueous residue from A. coffeaeformis (75.6%) showed the highest metal chelating effect. chloroform and ethyl acetate frac-tion of all the diatoms exhibited significant antioxidant activities in lipid peroxidation inhibitory activity. In particu-lar, both chloroform and the ethyl ecetate fraction from A. longipes and A. coffeaeformis exhibited lipid peroxidation inhibitory activity significantly higher than that of $\alpha$- tocopherol. These data suggest that the Jeju benthic diatoms tested are rich in hydrophilic and hydrophobic antioxidative compounds with different antioxidative properties that can be applied in food industry.

• Korean Journal of Environment and Ecology
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• v.29 no.6
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• pp.884-894
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• 2015

To examine the relationship between microphytobenthos biomass and the condition index of Ruditapes philippinarum (manila clam), field observations were conducted seasonally at the tidal flats of Jeongsanpo and Hwangdo, Taean, Korea from February to November, 2012. A total of 122 species of microphytobenthos were identified over the study period with 85 species (30-45 species in season) at Jeongsanpo and 92 species (32-57 species) at Hwangdo. Chlorophyll a concentrations and cell number of microphytobenthos were $79.75mg/m^2$ and $3,255cells/cm^2$ at Jeongsanpo, and $151.50mg/m^2$ and $15,943cells/cm^2$ at Hwangdo, respectively. The dominant species were slightly different: Cylindrotheca closterium, Fallacia forcipata, Fogedia sp., Gyrosigma sp., and Navicula sp. at Jeongsanpo and C. closterium, Detonula pumila, Diploneis sp., Navicula sp. and Merismopedia sp. at Hwangdo tidal flat. Paralia sulcata was the representative species based on cell number at the two study sites. The number of microphytobenthos identified from the digestive organs of manila clams seasonally varied from 18 to 31 species at Jeongsanpo and dominant genus were Amphora, Navicula, Nitzschia and Paralia sulcata. At Hwangdo, the species number of microphytobenthos found in the digestive organs of manila clams were in the range of between 19 and 25 species in season and the dominant genus were Actinocyclus, Amphora, Coscinodiscus, Diploneis, Gyrosigma, Navicula, and Diploneis. The condition index of manila clams were greater at Hwangdo (0.57) than at Jeongsanpo (0.42). Present results could support that the condition index of manila clams is positively correlated with the species richness and chlorophyll a contents of microphytobenthos.

• 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.

• ALGAE
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• v.17 no.2
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• pp.117-125
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• 2002

Five microalgal species isolated from the Jeju coast and four microalgal stock strains in hatchery were cultured in order to investigate their adapation to extreme changes in environmental factors such as salinity, water temperatue, adn nutrients. In case of salinity variation, Nitzschia sp. of Bacillariophyceae, Isochrysis galbana of Haptophyceae and Tetraselmis gracilis of Prasinophyceae showed optimum growth at the low salinity of 20 and 25 psu. Amphora coffeaeformis and Chetoceros simplex of Bacillariophyceae, and Pavlova lutheri of Haptophyceae adapted well at the relatively high salinities of 30 and 35 psu. However Phaeodactylum tricornutum of Bacillariophyceae and Chlorella sp. of Chlorophyceae showed euryhaline property In case of water temperature variation, most of all the species studied wer inhibited at 10℃. C. simplex, Nitzschia sp., p. tricornutum, Chlorella sp. and T. gracilis grew well at above 20℃. A. coffeaeformis, I. galbana and P. lutheri adapted also at the high temperature of 30℃. Each microalgal strain showed different growth rates and its maximum biomass. Generally microalgal populations from the Jeju coast grow well in relatively high salinity and high water temperature. Their growth were inhibited at low water temperature, but not likely affected at low salinity. This study indicates that the microalgal populations could not be affected by abnormally low salinity phenomena, which have happened occasionally around the west Jeju coast in summer and have led macrobenthic animals to mass mortality.

• The Korean Journal of Malacology
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• v.29 no.3
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• pp.197-205
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• 2013

Even though seedling production of Haliotis discus hannai has fully developed, the culture of benthic diatom as a live food for larvae is still a barrier to solve in commercial hatchery. The farmer depends on mixed microalgae which are non-selectively attached on the plate by flowing of natural seawater. The adequate diatom on the plate for the larvae in terms of quality and quantity is always significant bottleneck in the hatchery. In this study, two benthic diatom species, Caloneis schroederi and Rhaphoneis sp. were separately cultured in mass and inoculated to four tons' settlement tank of the larvae. And the larvae and the spats were cultured for nineteen and nine weeks, respectively. The result on seedling production of H. discus hannai with this method was compared to that of the farmer's traditional method as a control. With regard to variation of species composition of benthic diatom on the plate, C. schroederi and Rhaphoneis sp. were dominant for first three weeks after inoculation. But the diverse diatoms mainly, Navicula, Amphora, Cylindrotheca, Licmophora, Pleurosigma began to attache on the plate from the 4th week. The larvae attached 2.5 times more in C. schroederi tank than in the control tank. The final total biomass of the seeds in Rhaphoneis sp. tank was 3.2 times more than that of the control tank. The retared-spats in the seedling production also showed significantly higher growth and survival in the spat fed Rhaphoneis sp. or C. schroederi than those in the control group. We suggest that C. schroederi is proper for settlement of the larvae and Rhaphoneis sp. is appropriate for the growth of the larvae and spats in the commercial hatchery of H. discus hannai.