• Asian-Australasian Journal of Animal Sciences
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• v.23 no.5
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• pp.588-597
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• 2010

We investigated the effect of quercetin on growth and plasma cholesterol level and the effects of quercetin pretreatment (Diet 1, 0%; Diet 2, 0.25%; and Diet 3, 0.5% quercetin) for 30 and 60 days on oxidative stress induced by hypo-osmotic conditions (17.5, 8.75, and 4 psu) in olive flounder. The weights of flounder were higher with Diet 3 than with Diet 1 and 2, which indicated that a high concentration (Diet 3) of quercetin was very effective in growth. Total cholesterol levels were lower with Diets 2 and 3 than with Diet 1, leading us to hypothesize that quercetin removed low-density lipoproteins from circulation and thereby reduced total cholesterol. To understand the antioxidant role of quercetin, we measured the mRNA expression and activities of superoxide dismutase (SOD) and catalase (CAT) and the $H_2O_2$ concentration in quercetin-treated flounder exposed to osmotic stress. The $H_2O_2$ concentration and the SOD and CAT expression and activity levels were lower in flounder fed with Diets 2 and 3 than with Diet 1, suggesting that quercetin directly scavenges reactive oxygen species to reduce oxidative stress. Furthermore, the plasma lysozyme activity and osmolality were higher with Diets 2 and 3 than with Diet 1, indicating that quercetin increases immune function and helps to maintain physiological homeostasis. Plasma cortisol was lower with Diets 2 and 3 than with Diet 1, suggesting the quercetin protects against stress. These results indicate that quercetin has hypocholesterolemic and antioxidant effects, increases immune function, and acts to maintain physiological homeostasis.

• Atmosphere
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• v.16 no.3
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• pp.203-213
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• 2006

The objective of this paper is to investigate the effects of physical parameterization on the simulation of a snowfall event over Korea caused by air-mass transformation by using the PSU/NCAR MM5. A heavy snowfall event over Korea during 3-5 January 2003 is selected. In addition to the control experiments employing simple-ice microphysics scheme, MRF PBL scheme, and original surface layer process, three consequent physics sensitivity experiments are performed. Each experiment exchanges microphysics (Reisner Graupel), boundary layer (YSU PBL) schemes, and revised surface layer process with a reduced thermal roughness length for the control run. The control run reproduces an overall pattern of snowfall over Korea, but with a high bias by a factor of about 2. As revealed in the previous studies, the cloud microphysics and PBL parameterizations do not show a significant sensitivity for the case of snowfall. A more sophisticated cloud processes does not reveal a discernible effect on the simulated snowfall. Further, high bias in snowfall is exaggerated when a more realistic PBL scheme is employed. On the other hand, it is found that the revised surface layer process plays a role in improving the prediction of snowfall by reducing it. Thus, it is found that a realistic design of surface layer physics in mesoscale models is an important factor to the reduction of systematic bias of the snowfall over Korea that is caused by air-mass transformation over the Yellow sea.

• Ocean and Polar Research
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• v.38 no.4
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• pp.259-270
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• 2016

Sea Surface Salinity (SSS) observations from the Aquarius satellite in the East Sea show large systematic biases mainly caused by the surrounding lands and Radio Frequency Interferences (RFI) along the descending orbits on which the satellite travels from the Asian continent to the East Sea. To develop a technique for correcting the systematic biases unique to the East Sea, the least square regression between in situ observations of salinity and the reanalyzed salinities by HYCOM is first performed. Then monthly mean reanalyzed salinities fitted to the in situ salinities are compared with monthly mean Aquarius salinities to calculate mean biases in $1^{\circ}{\times}1^{\circ}$ boxes. Mean biases in winter (December-March) are found to be considerably larger than those in other seasons possibly caused by the inadequate correction of surface roughness in the sea surrounded by the land, and thus the mean bias corrections are performed using two bias tables. Large negative biases are found in the area near the coast of Japan and in the areas with islands. In the northern East Sea, data sets using the ascending orbit only (SCIA) are chosen for correction because of large RFI errors on the descending orbit (SCID). Resulting mean biases between the reanalysis salinities fitted to in situ observations and the bias corrected Aquarius salinities are less than 0.2 psu in all areas. The corrected mean salinity distributions in March and September demonstrate marked improvements when compared with mean salinities from the World Ocean Atlas (WOA [2005-2012]). In September, salinity distributions based on the corrected Aquarius and on the WOA (2005-2012) show similar distributions of Changjiang Diluted Water (CDW) in the East Sea.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.spc1
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• pp.180-188
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• 2006

We examined the effect of salt marsh vegetation on the benthic environment in macro-tidal flats at Donggeomdo, Ganghwa, on the west coast of Korea. Nine stations were established along a transect across the tidal flats, including salt marsh, and field sampling was conducted monthly from July 1997 to June 1998. During the study period, environmental parameters fluctuated as follows: salinity, 15.0 to 28.2 psu, exposure time, 613 to 702 hr/m, inundation time, 28 to 117 hr/m, sediment organic carbon, 0.71 to 1.34%, nitrogen, 0.07 to 0.16%, sulfur from 0.07 to 0.22%, mean grain size from 6.3 to $6.9{\phi}$, water content from 19.4 to 44.4%, water temperature from 4.4 to $20.4^{\circ}C$ and temperature of the surface sediments, 2.7 to $31.1^{\circ}C$, in total, seven halophyte species were sampled and found to be vertically distributed across the tidal levels. Carer scabrifolia, Suaeda maritima, Limonium tetragonum and Phragmites communis dominated the upper zone of the salt marsh, Juncus haenkei, Triglochin maritimum and P. communis dominated the middle zone, and Suaeda japonica predominated in the lower area. Principal component analysis (PCA) and non-metric multi-dimensional scaling revealed that the zonation of halophytes was related to environmental variables such as salinity and exposure time. The halophyte communities were likely related to the organic content of the surface sediment.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.2
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• pp.131-138
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• 2010

This study determined the optimum microalgae species and concentration for the brackish water flea, Diaphanosoma celebensis, in individual and community cultures by feeding it several different diets. Six single trials (Tetraselmis suecica, Isochrysis galbana, marine Chlorella ellipsoidea, freshwater Chlorella vulgaris, Scenedesmus sp., Selenastrum sp.) were conducted at 10 psu and $30^{\circ}C$. The community and individual cultures of the water flea were performed in 1-L beakers and 3-mL vessels (12-well culture plates), respectively. In the community cultures, the maximum density and specific growth rate were highest for water fleas fed T. suecica, reaching 60.0 individuals (ind.)/mL and 0.40, respectively. In the individual cultures, the most offspring and greatest life span of females were 56.9 ind. and 24.3 days, respectively, in the T. suecica trial. By contrast, diets of Scenedesmus sp. and Selenastrum sp. resulted in poor growth rates. In the T. suecica experiments examining a range of 10 to $200\times10^3$ cells/indl. the specific growth rate of the water flea tended to increase with the amount of supplement, while the life span decreased. The maximum density and number of offspring of females was highest at 53.5 ind./mL and 38.8 ind. respectively, at 40,000 cells/ind. These results suggest that the best microalgae species for the mass culture of D. celebensis is T. suecica and the optimum concentration is 40,000 cells per individual.

• Journal of fish pathology
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• v.28 no.1
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• pp.53-62
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• 2015

Here, we report the physiological changes and growth in disk abalone, Haliotis discus discus, in relation to dietary supplementation with citrus pomace (CP) 6%, Ecklonia cava residue (ECR) 6%, and CP + ECR (3% + 3%). The composition and nutrient content, survival rate and growth rate were measured 0, 4, 8 and 12 weeks after feeding the supplemented diets of CP and/or ECR. Moreover, the experiment of low salinity stress (25psu) for environmental resistance was examined for a period of 48 hours after feeding the supplemented diets for 12 weeks. The activities of superoxide dismutase (SOD), catalase (CAT), lysozymes, respiratory burst, and phenoloxidase were measured. The moisture content and crude protein condition of the body were increased with the addition of ECR only (P<0.05). We observed higher levels of survival in the experimental group compared with the control group. Moreover, the growth disk abalone that were fed a diet containing ECR was higher compared with the control group. However, the growth of abalone fed a diet containing CP was similar to the control group. With a rearing condition of low salinity stress, survival rate and lysozyme activity were increased in the ECR group compared with the control group. Dietary ECR reduced the level of CAT activity to approximately 30% of the control, however the level of CAT activity in the ECR group was similar to the start level of the previous stress. These results suggest that dietary ECR gives rise to an enhanced immunity in disk abalone, as a result of the decrease in CAT and lysozyme activity in particular. Accordingly, the growth and survival rate were increased by feeding an ECR-supplemented diet in the rearing of disk abalone, Haliotis discus discus.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.38 no.3
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• pp.172-183
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• 2005

To assess the macrobenthic community of oligohaline Youngam Lake, which is located at the Youngsan Watershed on the southwest part of Korea, macrobenthic fauna were collected at 45 stations during May, 2002. A total of 16 species of macrofauna were recorded with a mean density of 240 individuals per $m^2$ and a mean biomass of 7.07 g wet weight per $m^2$. Major dominant faunal groups were crustacean arthropods in terms of the number of species and abundance, and polychaete annelids in terms of biomass. The mean grain size was $5.7\;{\phi}$ which was dominated by silt fraction. The hydrological environment of the lake was characterised as an oligohaline environment with a mean surface water temperature of $17.8^{\circ}C$ and a mean salinity of 2.08 psu. The major dominant species were amphipods, Corophium sp. ($31\%$) and Jesogammarus sp. ($25\%$). Lowe. values of species diversity (H') with a mean of 0.81 (less than 1.0 from most stations) reflected the overall poor faunal diversity in this area. Multivariate analysis suggested that this benthic faunal community could be divided into four sub-regions such as the area from lake proper to water channel to the south, the stations located at the entrance and northern water channel, the stations near the dike, and the lake proper area. Freshwater and brackish water species which occurred in each station group were corresponded to the oligohaline salinity regime. Bottom hypoxia appeared in the entrance part of the lake between dyke and lake proper on May, which was resulted from stratification from spring season. These facts imply that marine macrobenthos were severely impacted by low salinity and a consequent hypoxia after embankment of the lake due to the restriction of water circulation.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.3
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• pp.296-302
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• 2013

The effects of temperature on spore release, growth and photosynthetic efficiency of Lithophyllum yessoense and Hildenbrandia rubra were examined. L. yessoense was collected at Galnam and H. rubra was collected at Gyeokpo, Korea. The experimental temperatures were different for spore release (10, 15, $20^{\circ}C$), sporeling growth (10, 15, 20, 25, $30^{\circ}C$) and photosynthetic efficiency (10, 15, 20, $25^{\circ}C$). All other culture conditions were the same: 34 psu, 12:12 LD and $50{\mu}mol$ photon $m^{-2}s^{-1}$. Spore liberation was maximal at $10^{\circ}C$ for L. yessoense and at $20^{\circ}C$ for H. rubra. After 14 days, the surface area of L. yessoense was 0.031 $mm^2$ at $25^{\circ}C$ and for H. rubra was 0.032 $mm^2$ at $20^{\circ}C$. Sporelings of L. yessoense were a dark-red color and grew in a round shape. In contrast, H. rubra was bright pink and changed from a round shape in the early growth stage to later become flabelliform. Photosynthetic efficiency was highest between $20-25^{\circ}C$ in both species. In conclusion, L. yessoense and H. rubra display different physiological features based on the optimal temperatures for spore release and sporling growth.

• Ocean and Polar Research
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• v.38 no.2
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• pp.161-169
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• 2016

The interannual variability of the water masses was analyzed from the CTD data measured in the tropical northwestern Pacific from 2006 to 2014. There are two typical water masses NPTW and NPIW that reveal the interannual variability in the survey area, in addition to two other water masses; the surface water mass TSW with a large seasonal variability and the deep water mass AACDW with a constant temperature-salinity characteristic at the depths deeper than 2,000 meters. In 2012 and 2014 NPTW was the most widely extended horizontally and thicker than 100 meters vertically, which was found over the entire survey area. However, NPTW was reduced and became much narrower in 2009 than in the other years. NPIW seemed to expand southwards from the north of $21^{\circ}N$ to $15^{\circ}N$ in 2008 and in 2012, which showed the salinity minimum in 2013 (< 34.15 psu). The sea surface height estimated by Absolute Dynamic Topography (ADT) approximately along $135^{\circ}E$ section showed the high peaks (> $1.45dyn{\cdot}m$) between $16^{\circ}N$ and $18^{\circ}N$ during the periods between 2007 and 2009 and between 2012 and 2013; the former peak lasted wider and longer in latitude and time (about three times) than the latter. The vertical section of the geostrophic currents in the upper 1,000 meters shows that there was a mesoscale pattern of repeated eastward and westward flows a few times in some years (2010 and 2014), which seemed to disappear in some other years (2008 and 2012); the former was closely related to the mesoscale eddies and the latter implied the pattern with the permanent currents. The persistent eastward flow between $17^{\circ}N$ and $19^{\circ}N$ seems to be related to the Subtropical Countercurrent (STCC).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.4
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• pp.411-419
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• 2018

This study investigated the survival rates and physiological responses of Korean rockfish, Sebastes schlegeli, in live fish containers ($8^{\circ}C$, 33 psu) for 18 days. The survival rate was 99% and 97% in the control and experimental groups, respectively. Hematocrit and hemoglobin did not differ significantly between the control and experimental groups. Glucose and cortisol rose immediately on the first day of containment, but both gradually normalized. Aspartate aminotransferase and alanine aminotransferase did not differ significantly between the two groups after recovery. $NH_3$ continued to rise after the first day, but decreased to a level not significantly different from that of the control group during the recovery period. Plasma ions and osmolality did not change abnormally. The hemocyte population was not significantly different from that of the control. The ratios of apoptotic and necrotic cells indicated no specific variation in hemocyte viability. The histological changes in the skin and gills were not significantly different from those seen in the control. The experimental data obtained in this study suggest that live fish containers may be used to transport Korean rockfish without significantly affecting their physiology or survival.