• The Korean Journal of Malacology
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• v.28 no.2
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• pp.137-143
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• 2012

This study was done to examine the effect of several diets (Phytoplankton = PHY, Shellfish Diet 1800 = INS, Oil type = OTE, Powder type = PTE) on growth, survival rate and biochemical composition of scallop juvenile Patinopecten yessoensis. The highest survival rate were observed in PTE + PHY (90%). The highest shell length and shell height was observed in PHY and PTE + PHY diet (P > 0.05). The growth with PTE and OTE diet was the lowest in shell length and shell height (P < 0.05). On the other hand, the shell width and meat weight were highest in PHY and PTE + PHY, while the lowest in PTE and OTE (P < 0.05). The content of fatty acids such as DHA and n-3 PUFA levels was significantly higher in the juvenile fed on PTE + PHY than in those fed on PHY and INS alone. Also, the total protein ranged 55.5 to 65.2% in PHY + INS, while 44.8%, 47.9% in PTE and OTE respectively. The RNA and DNA contents were the highest in PHY and PTE + PHY, while the lowest in PTE and OTE (P < 0.05). RNA/DNA ratio significantly higher in juvenile with PHY + INS than those with PTE and OTE alone (P < 0.05). The combination of PTE + PHY could improve the growth and survival of scallop juvenile. Our results suggested that PTE could partially replace live algae in bivalve laval rearing.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.19 no.4
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• pp.287-301
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• 2014

In order to understand environment condition and phytoplankton community before and after coastal upwelling, the influences of upwelling events on phytoplankton community were studied at 18 stations located the Southern part of East Sea, Korea from May to August 2013. The surface water masses showed low temperature and high salinity due to upwelling events at coastal stations (A1, B1, C1). Correlation between temperature and nutrients (DIP, r=-0.218, p<0.01; DIN, r=-0.306, p<0.01; silicate, r=-0.274, p<0.01) was significantly negative. This result could be explained that nutrients were supplied to surface water by the upwelling of bottom water. Phytoplankton communities were composed of 186 species. Phytoplankton abundance were relatively high in May (C1, $726{\times}10^3cells\;L^{-1}$) and July (A1, $539{\times}10^3cells\;L^{-1}$). Total chlorophyll a and micro-size fraction ($&gt;20{\mu}m$) increased at coastal stations in July and August, while phytoplankton abundance and total chl. a was much low in June. Dominant species in June was Pseudo-nitzschia spp. of which the cell size was $309{\mu}m^3$. Cell size of Pseudo-nitzschia spp. was smaller than dominant species in other period. Therefore, the increase in total chloro-phyll a and the size of phytoplankton was resulted in the sufficient supply of nutrients. In contrast, these tendencies were not observed at outside stations. These results suggested that coastal upwelling was an important influencing factor to determine the species composition and standing stock of phytoplankton community in the coastal waters of the Southern part of East Sea, Korea.

• The Korean Journal of Malacology
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• v.27 no.4
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• pp.359-369
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• 2011

Twelve species of food microalgae were investigated to clarify the digestion index of Crassostrea gigas larvae using epifluorescence microscopy to choose an appropriate diet for artificial seed production in hatchery. An experiment was conducted using 1 (D shaped stage), 4 (Early umbo stage), 8 (umbo stage) and 12 (Full grown stage) days old larvae. larvae were stocked in 1 L flasks at 5 individuals/mL and fed $10{\times}10^4$ algal cells/mL of each species individually. Prior to larvae were fed for 3 h and then were observed under the microscope to detect ingestion; larvae were then sieved and replaced in 1 L flasks containing filtered seawater and were observed after 3, 5 and 8 h to analyse the digestion index. Values of digestion indices were specific for each alga. No evidence for the ingestion of Thalassiosira weissflogii was evident at all larval development stages tested. Digestion indices of others microalgae were 0.8-99.7% at 4 stage of larval development stages: Chlorella ellipsoidea (0.8-5.4%), Nannochloris oculata (1.4-5.0%), Isochrysis galbana (99.1-99.5%), Pavlova lutheri (99.1-99.5%), I. aff. galbana (99.4-99.5%), Cheatoceros calcitrans (0.0-99.2%), C. gracilis (0.0-99.7%), C. simplex (0.0-95.9%), Phaeodactylum tricornutum (0.0-99.6%), Tetraselmis tetrathele (0.0-99.7%) and Dunaliella tertiolecta (0.0-99.6%), respectively. Therefore, it is assumed that food microalgae showing the high digestion such as I. galbana should be supplied to the early umbo stage larvae, and then after the umbo larval stage, the mixed microalgae with diatoms and light green algae should be supplied to the full grown stage larvae to increase the digestion of their larvae.

• Korean Journal of Environmental Biology
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• v.32 no.1
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• pp.35-48
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• 2014

In order to estimate the effect of additional nutrients on phytoplankton growth and horizontal phytoplankton community distribution during the autumn season in 2010 and 2011, we investigated the abiotic and biotic factors of surface and bottom waters at 20 stations of inner and offshore areas in Gwangyang Bay, Korea. Also, nutrient additional experiments were conducted to assess additional nutrient effects on phytoplankton assemblage using the surface water. In both years, the total nutrients were high at the enclosed inner bay and the mouth of Seomjin River, whereas it was low at the St.15~20 where in influenced by the surface warm water current from offshore of the bay. On the other hand, nano- and pico-sized Chl. a were gradually increased towards the outer bay and their trends were significant in 2011 than in 2010. The cryptophyta species occupied more than 85% of total phytoplankton assembleges in 2010, whereas their abundance in 2011 remainds to be 1/10 levels of 2010. Following the cryptophata species, the diatom Chaetoceros spp. and Skeletonema-like spp. were found to be dominant species. Further the biosaasy experimental results shows that the phytoplankton biomass in the +N and +NP treatments was higher compared to control and +P treatments and its trend was significant at St.8 and St.20 where nutrient concentration were low. Based on the bioassay and field survey, providing the high nutrients may have stimulated to phytoplankton growth such as S. costatum-like spp.. In particular, opportunistic micro-algae such as Cryptomonas spp. were able to achieve the high biomass under the relatively mid nutrient condition from bottom after break down of seasonal stratification in the Gwangyang Bay.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.10 no.4
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• pp.189-197
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• 1977

In present study, the effects of various factors including the solvent concentration, extraction time and temperature, the ratio of sample vs extraction solvent, (w/v) and pH upon the extractability of the NaCl and alcohol soluble proteins of marine algae were investigated. Eight species of fresh algae, the major ones in consumption as food, namely Porphyra suborbiculata, Undarie pinnatifida, Hizikia fusiforme, Sargassum, fulvellum, Enteromorpha linza, Sargassum kjellmanianum, Codium coarctatum, and Ulva pertusa were used for the extraction of NaCl soluble protein and dried materials of four species, Perphyra suborbiculata, Undaria pinnatifida, Enteromorpha linza and Sargassum fulvellum were used for the extraction of alcohol soluble protein. The frozen and mascerated samples were prepared by the same method described in previous paper (Ryu, 1977). And the dried materials were moistened with alcohol solution before freezing. The effect of solvent concentration on the extractability of NaCl soluble protein differed from species. The extractability of Undaria Pinnatifide, Hizikia fusiforme, Perphyra suborbiculata, Enteromorpha linza, and Ulva pertusa reached maxima at 0.25M NaCl solution while the 1.0M for Sargassum fulvellum, Saygassum kjellmanianum and Codium coarctatum. In case of alcohol soluble proteins, it was shown at $20\%$ ethanol solution for Porphyra suborbiculata, Undaria pinnatifida, Enteromorpha linza, and Sargassum fulvellum. Variation of the ratio of sample vs solvent gave slight effect upon the extractability, but the ratio of 1:30(w/v) seemed most efficient for the extraction of NaCl soluble proteins and 100 ml solvent added to 1 g dried sample was effective in case of alcohol soluble proteins. Extraction time has a minimal effect upon the extraction of alcohol soluble protein, and approximately 21 to $43\%$ of algal protein was extracted within 1 hour. But in case of NaCl soluble protein extraction, the effect of time revealed differently from species to species resulting in that the extraction for 1 hour gave a maximum extractability in Ulva pertusa and Enteromorpha linza, 2 hours in Porphyra suborbiculata, Codium coarctatum and 3 hours in Undaria pinnatifica, Hizikia susiforme, Sargassum fulvellum and Sargassum kjellmanianum. When the NaCl soluble protein of Undaria pinnatifida and Enteromopha linza was extracted at various temperature, the most effective extraction temperature was $40^{\circ}C$ while the temperature was $50^{\circ}C$ for Undaria pinnatifida and $60^{\circ}C$ for Hixikia fusiforme, Sargassum fulvellum, Sargassum kjellmanianum and Codium coarctatum. Bus in case of alcohol soluble extraction, the optimum temperature was $30^{\circ}C$ for Enteromorpha linza and $40^{\circ}C$ for Undaria pinnatifida, Sargassum fulvellum and Porphyra suborbiculata. In the effect of pH on extractability, the maximum extractability of NaCl soluble proteins was obtained at pH 7to 8 and pH 8 to 9 for alcohol soluble protein.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.8 no.4
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• pp.401-410
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• 2003

Three beaches of the Seogwang-ri coast in the western part of Wu Island, Jeju-do, are solely composed of rhodoliths (red algal nodules). The beach sediments are coarse sand to granule in size and they show the banded distribution according to size. Commonly the larger pebble-sized rhodoliths are concentrated near the rocky coast, resulting from the transportation of the nodules from shallow marine environments by intermittent typhoons. Based on the internal texture of the rhodoliths, it appears that crustose red algae, Lithophyllum sp., is the main contributor for the formation of the rhodolith. The coarse sand to granule-sized grains show that they started to grow from the nucleus as rhodoliths, but the surface was severely eroded by waves. However, the pebble to cobble-sized grains exhibit the complete growth pattern of rhodoliths and sometimes contain other calcareous skeletons. It is common that encrusting red algae are intergrown with encrusting bryozoan. The surface morphology of rhodolith tends to change from the concentric to domal shape towards the outer part. This suggests that the rhodolith grew to a certain stage by rolling, but it grew in more quiet condition without rolling as it became larger. Aragonite and calcite cements can be found in the pores within rhodoliths (conceptacle, intraskeletal pore in bryozoan, and boring), and this means that shallow marine cementation has occurred during their growth. Growth of numerous rhodoliths in shallow marine environment near the Seogwang-ri coast indicates that this area has suitable oceanographic conditions for their growth such as warm water temperature (about 19$^{\circ}C$ in average) and clear water condition due to the lack of terrestrial input of volcanoclastic sediments. Fast tidal current and high wave energy in the shallow water setting can provide suitable conditions enough for their rolling and growth. Typhoons passing this area every summer also influence on the growth of rhodoliths.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.3
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• pp.271-275
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• 1999

The chemical and gelling properties of porphyran from Porphra yezoensis collected from Buan and Wido in Korea at different months of the year were studied. Crude porphyran was prepared by hot-water extraction and further purified by cetylpyridinium chloride precipitation, Crude porphyran and porphyran were modified by alkali treatment to eliminate sulfate. The yields of alkali-modified crude porphyran (AMCP) and porphyran(AMP) were between $4.9\~10.9\%$ and $4.0\~6.7\%$ of the dried algae weight and were maximum in February for Buan and January for Wido, respectively. Gel strength of AMCP were highest in February ($790g/cm^2$) for Buan and January ($740 g/cm^2$) for Wido. Alkali modification increased 3,6-anhydro galactose content and the molar ratio of galactose and 3,6-anhydrogalactose of AMCP and AMP showed 1 : 0,8$\~$1.1. GLC and FT-IR measurement of AMP showed that most of sulfate residues were combined to C-6 of galactose, Thus, results of this study suggest that crude porphyran extracted from Porphra yezoensis produces an agar of a reasonably good quality after alkali treatment.

• Korean Journal of Environmental Biology
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• v.17 no.1
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• pp.1-9
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• 1999

Numerous observations revealed strong evidence of increased middle ultraviolet radiation or UV-B (280 ~ 320 nm) at the earth's surface resulting from stratospheric ozone depletion. UV is the waveband of electromagnetic radiation which is strongly absorbed by nucleic acids and proteins, thus causing damage to living systems. It has been recorded in the East Sea, Korea that solar UV-B impinging on the ocean surface penetrates seawater to significant depths. Recent researches showed that exposure to UV-B for as short as 2h at the ambient level (2.0 Wm$^{-2}$) decreased macroalgal growth and photosynthesis and destroyed photosynthetic pigments. These may suggest that UV-B could be an important environmental factor to determine algal survival and distribution. Some adaptive mechanisms to protect macroalgae from UV-damage have been found, which include photoreactivation and formation of UV-absorbing pigments. Post-illumination of visible light mitigated UV-induced damage in laminarian young sporophytes with blue the most effective waveband. The existence of UV-B absorbing pigments has been recognized in the green alga, Ulva pertusa and the red alga, Pachymeniopsis sp., which is likely to exert protective function for photosynthetic pigments inside the thalli from UV-damage. Further studies are however needed to confirm that these mechanisms are of general occurrence in seaweeds. Macroalgae together with phytoplankton are the primary producers to incorporate about 100 Gt of carbons per year, and provide half of the total biomass on the earth. UV-driven reduction in macroalgal biomass, if any, would therefore cause deleterious effects on marine ecosystem. The ultimate impacts of increasing UV-B flux due to ozone destruction are still unknown, but the impression from UV studies made so far seems to highlight the importance of setting up long-term monitoring system for us to be able to predict and detect the onset of large -scale deterioration in aquatic ecosystem.

• Korean Journal of Microbiology
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• v.52 no.1
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• pp.40-48
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• 2016

This study mainly focused on isolation of marine algicidal bacteria associated with phytoplankton blooms and characterization of algicidal activity against harmful algae. Harmful algal blooms (HABs) found naturally in surface waters have caused many environmental problems worldwide. In this study, forty bacterial strains that have capability of inhibiting harmful algal growth were isolated from Masan Bay, Jinhae Bay, Dol Island, Jangmok Bay, and the Tongyeong Sea, Republic of Korea. The bacteria were screened furthermore for the characteristics on algicidal activities against Cochlodinium polykrikoides, Chattonella marina, Skeletonema costatum, Heterosigma akashiwo, Heterocapsa triquetra, Prorocentrum minimum, and Scrippsiella trochoidea. As a result, the algicidal bacteria that were screened from double over layer agar and microscopic counts tests belonged to genera Pseudomonas, Vibrio, Bacillus, Pseudoalteromonas, Ruegeria, Joostella, Marinomonas, Stakelama, Porphyrobacter, and Albirhodobacter. One of the most important HAB species is Co. polykrikoides and the strongest algicidal activity against the dinoflagellate was 94.00% after 6 h treatment with 10% bacterial culture filtrate. In this study, Marinomonas sp. M Jin 1-8, Stakelama sp. ZB Yeonmyeong 1-11 & 1-13, Porphyrobacter sp. M Yeonmyeong 2-22, and Albirhodobacter sp. 6-R Jin 6-1 were found to be as new genera of bacteria having anti-algal activity. These results suggest that these bacteria might play an important role in controlling phytoplankton blooms.

• Membrane Journal
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• v.25 no.2
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• pp.132-143
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• 2015

Water is an essential resource for humans, but fresh water becomes scarce due to population growth and contamination of limited resources. Membrane technology has been widely used for water treatment, and forward osmosis is a process which does not need high hydraulic pressure for the operation. However, there are needs for (1) development of novel draw solutes causing low internal concentration polarization and reverse salt flux for high water flux, and (2) development of economic recovery method of the draw solutes in the diluted draw solution. Previous researches on the draw solute include $NaHCO_3$ which can be regenerated by about $60^{\circ}C$ heating, sucrose which can make potable water without additional process, and magnetic nanoparticles which can be regenerated by external magnetic field. Using the principles of forward osmosis process, sea water desalination, wastewater treatment, refinement of proteins, energy generation using pressure retarded osmosis process, preparation of diluted fertilizer, and growing algae for biofuel can be conducted. This paper summarizes characteristics of ideal draw solutes, recovery method of the draw solutes, and various application examples.