• Ecology and Resilient Infrastructure
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• v.2 no.3
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• pp.224-236
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• 2015

We conducted the algicidal activity screening tests using 10 L microcosm to investigate the possibility of the field application of naphthoquinone derivative Nq 4-6 compound as an algicide. We determined its application range to assess its algicidal effects on the phytoplankton and to evaluate the response of the planktonic community and the water environment to this chemical. From results of the microcosm experiments, Nq 4-6 compound showed high algicidal activity on the centric diatoms such as Stephanodiscus hantzschii and Cyclotella meneghiniana, but it had no effect on other phytoplankton. The abundance of S. hantzschii continuously increased in the control, but its cell density decreased 1 day after the Nq 4-6 treatment. In particular, Nq 4-6 showed algicidal activity of 94.4% against S. hantzschii 7 days after the treatment. The dominance index of phytoplankton community was lower in the treatment than in the control. The diversity index, richness index and evenness index of phytoplankton community was higher in the treatment. Environmental factors and biological factors did not show specific changes after the Nq 4-6 compound treatment. Therefore, the results of this study demonstrates that Nq 4-6 is an effective agent for the control of S. hantzschii blooms, and that the microcosm tests play a crucial role when assessing field application.

• Economic and Environmental Geology
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• v.34 no.2
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• pp.217-226
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• 2001

Stable isotope, paleoceanographic and sedimentological analyses were carried out along the core Ml5612 from the Mid-Atlantic Ridge. Distinct negative ${\delta}^{18}O anomalies punctuate the planktonic isotope records and correlate with the Heinrich-IRD cvents. The IRD layer in the corc contains varying amounts of quartz, K-feldspar, plagioclase, calcite, dolomite and mica, in which detrital carbonate contributes between I and 13% (except H3 and H6). Anomalies are strongest in the N. pachydenna (sin.) isotope record. Systematic changes in the ${\delta}^{18}O offset of G. hul/aides and G. inJlata signify variations in mid-latitude thermocline structure. In conjunction with negative benthic ${\delta}^{13}C anomalies, the data document a stronger contribution of a ${\delta}^{13}C depleted, nutrient-rich water mass during the IRD events. The ${\delta}^{13}C amplitude of > 1 $\textperthousand$ between 25 and 57 ka indicates changes between northern source (NADW) and southern source (AABW) water masses at this site. The IRD layers in the core Ml56l2 are correlative with those from the core S075-26KL and DSDP 609. The IRD layers from the Portuguese margin arc coeval with HI, H2 and H4 of the open North Atlantic. This similarity (and/or synchronicity in both regions may have been resulted from common changes in a North Atlantic thermohaline switch.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.6
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• pp.4328-4334
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• 2015

We determined a method to determine marine planktonic organism viability using Evan's blue, Aniline blue, and 5-choromethyfluorescein diacetate (CMFDA). The Evan's blue and Aniline blue methods produced bright blue light for dead phytoplankton and zooplankton and were the best dyes to detect dead cells. The staining efficiency of Evan's blue and Aniline blue were ${\geq}90%$ of the original field sample. However, it was difficult to test the efficiency of a ship's ballast water treatment system because detection of living cells. In contrast, the CMFDA method, which is based on measuring cell esterase activity using a fluorimetric stain, was the best dye to detect live cells of almost all phytoplankton species, and staining efficiency was 70%. The CMFDA method is similar to the fluorescein diacetate (FDA) staining method. Therefore, we estimated viability of phytoplankton species using a double-staining method by combining CMFDA and FDA to determine optimum staining efficiency. As a result, the frequency of dying cells based on the double-staining method was 95%, which was significantly higher than that of single CMDFA staining. Our results suggest that a CMDFA + FDA assay is more effective to determine survival of marine plankton and that this method was applicable to investigate the efficacy of a ship's ballast water treatment system.

• Food Science of Animal Resources
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• v.30 no.3
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• pp.479-486
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• 2010

Tolerance against heat, sanitizers, and antibiotics of 112 Cronobacter isolates classified by desiccation was determined to permit effective biocontrol in powdered foods. The isolates were classified into three groups: dry-tolerant (n=37), dry-sensitive (n=7), and dry-intermediate (n=68). The strains that were highly tolerant to drying also showed high heat tolerance that they seemed to have high tolerance to heat after dry stress in powdered foods like infant formula. Sodium hypochlorite and benzalkonium chloride concentrations necessary to achieve a 5-log reduction in viable counts (CFU/mL) were 15-25 ppm and 5-15 ppm, respectively. However, there was little difference of the efficacy of these sanitizers between dry-sensitive and -tolerant strains for planktonic cells suspended in 3% albumin. The minimal inhibition concentration (MIC) of $\beta$-lactam ampicillin was 64-128 ppm for 90% of the strains. The isolates were consistently sensitive to kanamycin and naldixic acid (MIC=4 ppm). Dry-tolerant strains displayed more antibiotic resistance than dry-sensitive strains. The results indicate that dry-tolerant Cronobacter isolates often possess heat and antibiotic resistance, indicated the need for potent sterilization treatments of powdered foods.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.4
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• pp.525-533
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• 1999

In the Korea Strait total of 96 copepod taxa (40 genera) were identified from the seasonal and vertically stratified samples. Species richness was the highest in fall and the abundance was the highest in spring. Spatial differences were not significant within each season, but was meaningful among seasons. The water column layers of high abundances were near bottom in spring, and surface in summer and fall. Species association of copepods was examined by the cluster analysis. There are the two different results on the timing of the intrusion of East Sea Cold Water to the Korea Strait in the deeper layer based on physical data [in winter (Lee et al., 1938) vs in summer (Cho and Kim (1998)]. This study based on the distributional characteristics of copepods supported Cho and Kim (1998)'s result. Although sea water temperatures was one of major controlling factors of the copepod distribution in this strait, biological interrelation among the species such as common or exclusive exploitation of the habitat was also responsible for the observed distributional patterns.

• The Journal of the Korean dental association
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• v.57 no.10
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• pp.560-568
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• 2019

Purpose: This study evaluated the antibacterial effects of curcuma, ginger, and finger root extracts in water-soluble powder on planktonic Streptococcus mutans(S.mutans), which is known to cause dental caries, in order to confirm whether these extracts could perform as photosensitizers for the effects of photodynamic therapy (PDT). Methods: This study used the strain of streptococcus mutans ATCC 25175 distributed by the Korean Collection for Type Cultures of the Korea Research Institute of Bioscience & Biotechnology. Commercial edible curcuma, ginger and finger root were used as the natural extracts for the use of photosensitizer. To extract organic solvent, 3 g of each powder was mixed in $30m{\ell}$ of dimethyl sulfoxide (DMSO, VWR, Germany) before extraction. $1.8m{\ell}$ of the photosensitizer solution, manufactured in the concentrations of 5, 0.5, and $0.05mg/m{\ell}$, was mixed with $0.2m{\ell}$ of the S. mutans culture medium that had been cultured for 2 days. To induce the photodynamic reaction, Qraycam (AIOBIO, Seoul, Korea) equipped with 405 nm LED was used to expose light for 5 minutes to irradiate 59 nW energy for 300 seconds. Results: Compared with the case with no light, a higher photodynamic therapeutic effect was confirmed with $0.05mg/m{\ell}$ curcuma powder extract, the concentration of $0.5mg/m{\ell}$ and LED light of 405 nm wavelength (p=0.000, p=0.003). $0.05mg/m{\ell}$ of curcuma powder extract and the concentration of $0.5mg/m{\ell}$ showed 100% antibacterial effect when exposed to light, whereas the concentration of $5mg/m{\ell}$ showed 11.95% antibacterial effect. When exposed to light, $0.05mg/m{\ell}$ of ginger powder extract showed an antibacterial effect which didn't statistically decrease. The concentrations of $0.5mg/m{\ell}$ and $5mg/m{\ell}$ did not show any antibacterial effects. As a result of examining any photodynamic therapeutic effects of finger root powder extract on S. mutans, no statistically significant effect was found. Conclusion: The curcuma powder extract is expected to perform as a photosensitizer. Even though belonging to the same ginger family, ginger powder and finger root powder seem difficult to perform as photosensitizer.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.15 no.1
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• pp.1-7
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• 2010

We were successfully reared young marine ornamental larva fish in a unique process of microalgae blooming culture tank. The marine fish larva was grown and survived in this method. Generally, we called this method as natural mixed culture. Observed planktonic microalgae were 34 species with 19 diatoms (Detonula pumila, Nitzschia sp., Fragilaria oceanica, Chaetoceros curvisetus, Stephanodiscus sp., Chaetoceros decipies, Chaetoceros sp., Thalassiosira rotula, Eucampia zodiacus, Diploneis splendica, Nitzschia longissima, Surirella cuneata, Asterionella glacialis, Nitzschia spp., Chaetoceros debile, Thalassionema nitzschioides, Nitzschia closterium, Skeletonema costatum and Licmophora sp.), 14 flagellates (Euglena, sp., Gonyaulax sp., Pyramimonas sp., Protoperidinium sp., Eutreptia sp., Parapedinella sp., unidentified micrc-flagellate, Gyrodinium sp., Scrippsiell trochoidea, Gymnodinium sanguineum, Chrysochromulina sp., Gymnodinium sp., Prorocentrum triestinum and Micromonas sp.) and 1 ciliate (Mesodinium rubrum) in this culture tank. Dominant microalgae were Chrysochromulina sp. during the larval rearing periods. Blooming condition maintained continuously and stably from 10 to 60 days in this microcosm.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.15 no.4
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• pp.176-183
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• 2010

In order to understand the temporal variations and species composition of tintinnids, at two stations of the Korea Strait, this study was carried out from January to December 2007 (n=17). Fifty-one species from 22 genera were encountered: 27 neritic species (9 genera) and 24 oceanic species (14 genera). The species composition was different between two stations, and neritic species frequently appeared at St. 1, while oceanic species more frequently appeared at St. 2. According to the frequency in appearance of species, the most dominant species were neritic species such as Stenosemella nivalis and S. pacifica, that appeared in all seasons. Also, Acanthostomella norvegica, Amphorellopsis acuta, Epilpocyloides ralumensis, Protorhabdonella curta and other many oceanic species appeared intensively during the low salinity (${\leqq}33\;psu$) and high water temperature (${\geqq}24^{\circ}C$) period (July~October). The abundance of tintinnids ranged from 0 to 1,845 cells $L^{-1}$. It was higher in the seasons (summer and autumn) of low salinity and high water temperature than in other seasons. The abundance was relatively higher at St. 1 than at St. 2. On the basis of correlation and multiple regression analyses, the tintinnid abundance was not correlated with chi-a, but significantly correlated with water temperature and salinity, suggesting to be the primary abiotic factors influencing the abundance. This study suggests that the complex hydrographic conditions of the study area might influence the temporal distribution and species composition of tintinnids.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.4
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• pp.308-319
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• 2008

Temporal variations in plankton assemblages and environmental factors in Asan Bay and their relationships were examined with the data collected from February till early June, 2005. Seawater temperatures showed typical pattern of temporal change observed in temperate waters. Salinity variation was minor. Phytoplankton biomass showed two peaks, one in February only in the inner part of the bay and the other in May in the whole bay. Phytoplankton succession was clearly shown with the increase of seawater temperatures. Diatom (Bacillariophyceae) dominated in February, diatom and cryptomonads (Cryptophyceae) prevailed in May, and dinoflagellates (Dinophyceae) was most abundant in June. Spring bloom in Asan Bay occurred about one month earlier than those observed in temperate seas. Among the inorganic nutrients (N, P and Si), only silicate concentration showed a significant negative correlation with phytoplankton biomass, indicating the sink of this nutrient in the bay to be the uptake by phytoplankton. Nitrate concentration seemed to be a limiting factor in this bay during the study period. Mesozooplankton abundances showed a significant positive correlation with seawater temperatures and a significant negative correlation with phytoplankton biomass. Increase of mesozooplankton abundance followed phytoplankton increase with the time lag of about two months. This increase of zooplankton seemed to be the result of increased seawater temperatures and food.

• Korean Journal of Environmental Biology
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• v.28 no.2
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• pp.69-78
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• 2010

The distributions of planktonic and periphytic algae were studied from April 2003 to February 2004 at Gwangju Stream. A total of 274 species, belongs to 8 classes, 19 orders, 6 suborders, 35 families, 4 subfamilies, 79 genera, was identified as algal flora of Gwangju Stream. The most diverse phytoplankton flora was observed at Bangrim bridge and Yangdong market sites with 137 species, and followed by Yuchon bridge site (118 species). The richness of phytoplankton fluctuated throughout the studied period from all the sampled sites. The precipitation was a major factor affected the richness of phytoplankton. The diatoms predominated the phytoplankton of Gwangju Stream with 57.7~77.0% of total phytoplankton. The maximum cells of phytoplankton was observed at Yuchon bridge site with 23,792 cells $mL^{-1}$ in August 2003, and minimum at Jeungsimsa site with 82 cells $mL^{-1}$ in April 2003. The periphyton of Gwangju Stream was predominated by the diatoms. In February 2004, all the periphyton of Yuchon bridge site were diatoms. Other sites also showed the predominance of diatoms throughout the studied period. The standing crops of phytoplankton were highly correlated with chlorophyll-a concentration with R=0.795. TN and TP also showed high relationships with phytoplankton standing crops in Yangdong market site with R=0.796 and R=0.760, respectively. The rains of 7-days ago showed high relationships with phytoplankton standing crop at Dongsan tower site with R=0.810. However, other climatic factors showed no clear relationships with phytoplankton cells.