• ALGAE
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• v.19 no.2
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• pp.145-148
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• 2004

As a result of the 2-year monthly monitoring of the phytoplankton community at 3 stations in Mankyeong Estuary, Korea, we learned that cyan bacterial species of the genus Anabaena occurred at most sampling points with huge salinity differences (0.1-32.5 psu). We isolated several clones of Anabaena spp. from the monitoring stations, and screen out two euryhaline and nitrogen-fixing Anabaena clones, CB-MAL21 and CB-MAL22. The two clones were grown under various environmental gradients such as temperature (20, 30, 35 and 40$^{\circ}C$), salinity (0, 2, 5, 15 and 30psu), and $PO_4^{3-}$-P concentration (0, 1.6, 8.0, 40 and 200 ${\mu}M$M). Growth of CB-MAL21 and CB-MAL22 was measured by daily monitoring of chlorophyll fluorescence from each experimental culture for more than three serial transfers. Both the two experimental clones did not grow at 0psu. Maximal growth rates of the two clones were markedly reduced at lower $PO_4^{3-}$-P concentrations showing negligible growth at 0 and 1.6 ${\mu}M$M. However, growth of CB-MAL21 was not affected by low $NO_3^--$ concentration in culture media, showing the nitrogen-fixing ability. Maximum biomass yields of the two clones decreased dramatically at 35 and 40$^{\circ}C$. Optimal growth conditions for the two experimental clones were determined to be 20-30$^{\circ}C$, 40 ${\mu}M$M $PO_4^{3-}$-P, and wide salinity range from 5.0 to over 30psu. Best growth of CB-MAL21 was shown at (20$^{\circ}C$-15psu), which is less saline and cooler condition than those (i.e., 30$^{\circ}C$-30psu) for the best growth of CB-MAL22. The euryhaline and nitrogen-fixing CB-MAL21 strain thus can be a candidate laboratory culture for the future cyan bacterial marine biotechnology in temperate coastal waters.

• ALGAE
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• v.32 no.4
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• pp.275-284
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• 2017

Microcystis aeruginosa causes harmful algal blooms in the Nakdong River of Korea. We studied the effect of different concentrations and ratios of ammonium ($NH_4{^+}$), nitrate ($NO_3{^-}$), and phosphate ($PO{_4}^{3-}$) on growth of this species in BG-11 medium: each nutrient alone, $NO_3{^-}:NH_4{^+}$ ratio, the N : P ratio with fixed total N (TN), and the N : P ratio with fixed total P (TP). The single nutrient experiments indicated that M. aeruginosa had the highest growth rate at $NH_4{^+}$ and $NO_3{^-}$ concentrations of $500{\mu}M$, and at a $PO{_4}^{3-}$ concentration of $5{\mu}M$. The $NO_3{^-}:NH_4{^+}$ ratio experiments showed that M. aeruginosa had the highest growth rate at a ratio of 1 : 1 when TN was $100{\mu}M$ and $250{\mu}M$, and the lowest growth rate at a ratio of 1 : 1 when the TN was $500{\mu}M$. The N : P ratio with fixed TN experiments indicated that M. aeruginosa had the highest growth rates at 50 : 1, 20 : 1, and 100 : 1 ratios when the TN was 100, 250, and $500{\mu}M$, respectively. In contrast, the N : P ratio with fixed TP experiments showed that M. aeruginosa had the highest growth rates at 200 : 1 ratio at all tested TP concentrations. In conclusion, our results imply that the $NO_3{^-}:NH_4{^+}$ ratio and the $PO{_4}^{3-}$ concentration affect the early stage of growth of M. aeruginosa. In particular, our results suggest that the maximum growth of M. aeruginosa is not simply affected by the $NO_3{^-}:NH_4{^+}$ ratio and the N : P ratio, but is determined by the TN concentration if a certain minimum $PO{_4}^{3-}$ concentration is present.

• Fisheries and Aquatic Sciences
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• v.4 no.2
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• pp.75-83
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• 2001

This study is to investigate biochemical compositions of two species of marine microalgae, Chlorella ellipsoidea of Chlorophyta and Tetraselmis suecica of Prasinophyta, and to assess their potential antimicrobial activities. Crude protein, lipid and carbohydrate for C. ellipsoidea were $43.15\%$, $12.63\%$ and $13.09\%$, respectively, and those for T. suecica were $44.95\%$, $4.80\%$ and $24.05\%$, respectively. The major amino acids of the two micro algae were aspartic acid, glutamic acid, glycine, alanine, valine, leucine, lysine and proline, and no significant difference between the amino acid compositions of both micro algae was observed. The major sugars for both microalgae were glucose, galactose and mannose, and glucose contents showed the highest level, $58.70\%$ for C. ellipsoidea and$57.86\%$ for T. suecica. The major mineral contents of both micro algae for 100g were Ca (3,114mg in C. ellipoidea and 3,389mg in T. suecica) and followed by Na (2,881mg), K (548mg) and Mg (545mg) for C. ellipsoidea and Na (1,832 mg), Mg (1,510mg) and K (548mg) for T. suecica. In the content of ATP-related compound, hypoxanthine in C. ellipsoidea and IMP in T. suecica were absolutely dominant compounds. The highest content of fatty acid in C. ellipsoidea was 20:4, $27.15\%$ and that in T. suecica was 18:3 (w-6), $18.10\%$. In case of physiologically important polyunsaturated fatty acids like eicosapentaenoic acid (20: 5) and docosahexaenoic acid (22: 6), both microalgae possessed just trace amounts but was rich in arachidonic acid (20: 4). Vitamin content in both microalgae was significantly high in choline and inositol. In antimicrobial activity by water- and fat-soluble fraction of the micro algae, hexane extract in the fat-soluble fraction of C. elliposidea inhibited the growth of Bacillus subtilis by $96\%$ bactericidal activity and tetrachlorocarbon extract of T. suecica indicated relatively excellent antimicrobial activity $(81\%\;bactericidal\;activity)$ against Escherichia coli. Hot water extract among water-soluble fraction of both micro algae almost suppressed the growth of Staphylococcus aureus by $96\%$ bactericidal activity.

• Ocean and Polar Research
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• v.40 no.2
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• pp.69-75
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• 2018

We investigated the effects of environmental variations on the growth and survival rate of Stichopus japonicus to determine the optimum environmental conditions for its growth. Literature studies and a 12 month-long diver survey were carried out to understand the habitat, ecology and size of the surveyed area. Based on the collected data, we suggested optimum habitat conditions for releasing S. japonicus. Experiments on releasing S. japonicus were conducted in the breakwater of the Hwagye fishing cooperative in Hwagey-ri, Namhae-un, Gyeongsangnam-do, Korea. To implement the experiments, we divided the surveyed area into 4 sub-areas with different characteristics: (1) sand and silt zone; (2) artificial sea cucumber bank zone; (3) artificial rock bank zone; and (4) marine algae zone. The experiment lasted for 12 months. We released 32,000 sea cucumbers over $120m^2$ of each of the sand and silt zone, artificial rock bank zone and marine algae zone and released 6,000 sea cucumbers over $120m^2$ of the artificial sea cucumber bank zone. The average density of the released sea cucumbers from day 30 to day 360 after the releasing was conducted was the highest in the artificial sea cucumber bank zone ($23.7animal/m^2$), which was followed by artificial rock bank zone ($2.0animal/m^2$), marine algae zone ($1.9animal/m^2$) and sand and silt zone ($0.8animal/m^2$). The analysis on growth showed that the initial average weight of 2.3 g increased on day 360 after the releasing to 12.5 g in the artificial sea cucumber rank zone, 20.2 g in the sand and silt zone, 23.3 g in the artificial rock bank zone and 22.9 g in the marine algae zone. Results from the experiment along with the literature analysis suggest the following optimum habitat conditions: $10-15^{\circ}C$ water temperature; 28-34 psu salinity; 5-10 m water depth; 0.2-0.5 m/s velocity; rock, stone and muddy sand as substrate; and less than 20% mud in the substrate.

• Korean Journal of Ecology and Environment
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• v.41 no.4
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• pp.554-562
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• 2008

To evaluate the limitation for epiphytic and planktonic algal growth, acid extractable inorganic phosphorus (AP), implying the luxury uptake phosphorus, was measured in five reed zones of Lake Biwa. The AP in epiphytic substances was 0.7 to 1.4 mg P surface stem $m^{-2}$ in summer and 1.2 to 2.8 mg P $m^{-2}$ in winter. On the other hand, the amount in planktonic substances was 1.4 to 5.7 mg P m -3 and 0.8 to 5.4 mg P $m^{-3}$ in both seasons. Contribution of AP in the epiphytic and planktonic phosphorus was 23 to 31% and 8 to 27% in summer, and 17 to 22% and 9 to 17% in winter. It suggests that in summer both epiphytic and planktonic algae had been luxuriously taken up phosphate into cells. The weight ratios of C : N : P were averaged 79 : 20 : 1 for the epiphytic substances and 81 : 12 : 1 for the particulate substances. On the other hand, the ratios without the luxurious phosphorus were 93 : 24 : 1 and 103 : 15 : 1, showing much higher values than the Redfield ratio. High ratio in the epiphytic substances indicates that the phosphorus is the limiting parameter, rather than nitrogen, regulating the growth of epiphytic algal populations.

• ALGAE
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• v.26 no.3
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• pp.253-263
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• 2011

Phenotypic plasticity was examined in the economically and ecologically important brown alga Ascophyllum nodosum in southwestern Nova Scotia, considering specifically how nutrient loading affected its vegetative and reproductive features. To determine this, we examined morphometric changes in A. nodosum from two sites receiving direct effluent impacts from a land-based finfish aquaculture facility and from two control sites, approximately 2 km away from the aquaculture facility in opposite directions. Fronds from test sites were significantly younger than from control sites (5 y vs. 8 y); however, fronds from farm sites were significantly larger (219 g vs. 90 g) because of their higher growth rates. Thalli from farm sites had greater reproductive potential, as shown by numbers of receptacle initials (797 initials vs. 281 initials). These results suggest limited nutrient inflows from land-based aquaculture may positively affect adjacent Ascophyllum populations by inducing higher growth rates. We conclude that the coordination of effluent management from land-based aquaculture with natural resource harvesting of A. nodosum may be beneficial. Further study is necessary to determine the limits of nutrient loading for this potentially beneficial outcome.

• Food Science and Biotechnology
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• v.17 no.5
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• pp.976-982
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• 2008

The 10 species of marine green algae was collected from Jejudo(Island) in Korea. Methanolic and aqueous extracts were prepared and screened for inhibition activities against tumor cell growth. Of the tested samples, the sea staghorn (Codium fragile) aqueous extract (CFAE) showed the highest activity on CT-26 cell growth. Therefore, CFAE was selected for further experiments and the possibility to induce apoptosis by the CFAE was investigated. Flow cytometric analysis revealed that it dose-dependently increased apoptotic cells with hypodiploid DNA contents in CT-26 cell line. These results indicated that CFAE can suppress the growth of CT-26 cells through apoptosis. The CFAE decreased the protein expression of anti-apoptotic Bcl-xL and led to the activation of caspase-3 and -7. A crude polysaccharide was separated from CFAE and it mainly constituted with 61.2% galactose and 30.5% arabinose as analyzed by high performance liquid chromatography (HPLC).

• Journal of Environmental Science International
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• v.13 no.9
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• pp.819-826
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• 2004

In order to elucidate the polycyclic aromatic hydrocarbon concentration and its origin in arctic area, four arctic brown algae (Laminaria saccharina, L. digita, Alaria esculenta, Desmarestia aculeata), one marine invertebrate (Echinoidea) and sediments were collected from Kongsfjorden in Spitsbergen from the late July to early August, 2003. In case of macroalgae, the young blade part above growth point and the old stipes and blades beneath growth point were separated and analyzed for polycyclic aromatic hydrocarbons (PAHs) in an attempt to check the mechanism of uptake in macroalgae to accumulate PAH. There was no difference in PAH concentrations between sampling sites (Stations B and C), species, and blades beneath and above growth point. PAH concentrations in all samples collected in this study were relatively higher than those reported in other areas of arctic. Especially, station C, which is known as an unpolluted area, showed 10 times higher PAH concentration (8,765 ng/g) in sediment than station A (694 ng/g) around harbor. In addition high PAH concentration, station C had very higher proportion of methylated PAH to parent PAH in sediment than station A. Source analysis using PAH isomer pair ratios as indicators showed that Kongsfjorden area seemed to be relatively contaminated with PAH derived from direct petroleum input.

• ALGAE
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• v.32 no.4
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• pp.337-347
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• 2017

Silvetia siliquosa is an ecologically and commercially important brown alga that is harvested from its natural habitats, but its population has recently been diminishing along the Korean coast. To develop new techniques for algal population restoration, we tested two newly developed transplantation methods (using polyethylene ropes and natural rock pieces) at two study sites, Gwanmaedo and Yeongsando, on the southwest coast of Korea, from May to November 2014. The transplants on polyethylene ropes showed significantly greater survival, maturity, and growth than those on natural rocks at both study sites. Newly recruited juveniles (<3 cm) of S. siliquosa increased remarkably from May to December near the transplants on polyethylene ropes and natural rocks.Therefore, we suggest that transplantation using polyethylene ropes is more effective than using natural rocks to restore the population of S. siliquosa in Korea.

• ALGAE
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• v.35 no.4
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• pp.375-388
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• 2020

Ocean acidification and warming, identified as environmental concerns likely to be affected by climate change, are crucial determinants of algal growth. The ichthyotoxic raphidophytes Chattonella species are responsible for huge economic losses and environmental impact worldwide. In this study, we investigated the impact of CO2 on the thermal performance curves (TPCs) of Chattonella marina and Chattonella ovata grown under temperatures ranging from 13 to 34℃ under ambient pCO2 (350 μatm) and elevated pCO2 (950 μatm). TPCs were comparable between the species or even between pCO2 levels. With the exception of the critical thermal minimum (CTmin) for C. ovata, CTmin for C. marina and the thermal optimum (Topt) and critical thermal maximum (CTmax) for both species did not change with elevation of pCO2 levels. While CO2 enrichment increased the maximum photosynthetic rates (Pmax) up to 125% at the Totp of 30℃, specific growth rates were not significantly different under elevated pCO2 for the two species. Overall, C. ovata is likely to benefit from climate change, potentially widening its range of thermal tolerance limit in highly acidic waters and contributing to prolonged phenology of future phytoplankton assemblages in coastal waters.