• Korean Journal of Environmental Biology
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• v.27 no.3
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• pp.285-291
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• 2009

The effects of water temperature on oxygen consumption (OC) of starry flounder Platichthys stellatus reared in seawater (SW) and freshwater (FW) was performed in closed water-recirculating system containing respiratory chamber. Fish acclimated in separate indoor tanks with SW (nine of fish used, $263.0{\pm}40.4$ g) or FW (nine of fish used, $265.8{\pm}34.8$ g) were sampled. The OC of starry flounder at $15^{\circ}C,\;20^{\circ}C$ and $25^{\circ}C$ were $74.4{\pm}17.0,\;85.9{\pm}15.8,\;98.3{\pm}11.4\;mg\;O_2\;kg^{-1}hr^{-1}$ in SW and $46.7{\pm}12.0,\;63.3{\pm}7.5,\;82.6{\pm}5.3\;mg\;O_2\;kg^{-1}hr^{-1}$ in FW, respectively, showing a linear increase in OC with water temperature. The OC of fish reared in both SW and FW clear diel rhythm, with lower values at daytime and higher values in the night, in accordance with light (09:00~21:00 hr) and dark (21:00~09:00 hr) phases of the diel cycle (12L : 12D) in water temperature at $15^{\circ}C$ and $20^{\circ}C$. However OC of fish reared in both SW and FW showed unclear diel rhythm with light and dark phases of the diel cycle in water temperature at $25^{\circ}C$. Starry flounder reared in FW had higher ventilation rates than those in SW, but SW had higher OC per breath than those in FW.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.4
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• pp.412-420
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• 1995

Oxygen consumption (OC), ammonia nitrogen (AN ) excretion and body composition were measured to study the effects of energy/protein ratio (EPR) on the utilization of protein and energy in juvenile rockfish, Sebastes schiegeli. Juvenile rockfish were divided into three groups that they fed three isocaloric diets (3,5kcal/g) containing 30 (I), 40 (II) or $50\%$ crude protein (III). EPR of the three experimental diets were 11.5 (I), 8.7 (II) and 7.0kcal/g III), respectively. Juvenile rockfish (wet wt. 2.9-3.1g) were cultured in 501 aquaria with the constant environmental condition of $20-24^{\circ}C$ water temperature and $34\%o$ salinity. For 24 hr after feeding the diets, juvenile rockfish fed diet III had a higher OC than did the fish from groups fed diets I and II, and average OC of the fish fed diets I, II and III were $0,93\pm0.02^a,\;0.92\pm0.02^a\;and\;1.03\pm0.03^bml\;O_2/g/h$, respectively. AN responses of juvenile rockfish to increasing levels of dietary protein (decreasing dietary EPR) were significantly different among three groups in which dietary protein at elevated levels increased the excretion of AN for 24 hr after feeding the diets. Average AN excretion of the fish fed diets I, II and III were $9.14\pm0.39^a,\;12.41\pm 0.53^a\;and\;14.89\pm0.55^c\;{\mu}g\;N/g/h$ respectively. The body protein content of the fish fed diet II for 59 days was significantly higher than that of the fish fed the other diets. But, there were no significant differences between three groups in body lipid, carbohydrate and ash contents. These results indicate that EPR of 9.7kcal/g (diet II) could be a optimum EPR in juvenile rockfish diet.

• Journal of Aquaculture
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• v.11 no.3
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• pp.391-400
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• 1998

This study was performed to investigate the effects of environmental parameters on the growth of Pacific oyster, Crassostrea gigas at old suspended culturing grounds of Korsung Bay and newly deveoped bottom, culturing grounds of Haenam region located in southern coast of Korea. The Kosung Bay was semiclosed and water exchange occurred through the small mouth and the current speed was very slow as the value of below 0.5kn. Haenam was opened and littoral zone. Current speed of the surroundings of this Bay about to 5.0knand transparency was low with the mean depth of 1.2m by the resuspension of the sediments. Water temperature and salinity regimes were suitable for oysters at those sites, however the mean value of those parameters and seasonal fluctuations was high at Kosung. The mean concentration of dissolved oxygen in survey area was above $5.0mg/\ell$. In Kosung, however, it was decreasing in June and showed the minimum with the concentration of $4.0mg/\ell$ in August at the bottom layer and recovered in September. Eutrophication parameters such as COD were 1.44 mg/l at this location. This mean value was higher than that of the Haenam Bay's $0.96mg/\ell$. The men value of chlorophyll-$\alpha$ at Haenam was two times higher than the other sites. Growth of shell height and meat weight of oysters at Kosung Bay were higher and the fatness was lower compared to thost of Haenam. As a result, absolute growth of oysters was high at Kosung and allometric growth, such as fatness, was good at Haenam. Low water temperature and frequent exposure of oysters to the air during ebb tide may retard the shell growth. On the other hand, relatively high food availability was profitable for the fatness at haenam site.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.10
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• pp.1555-1564
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• 2014

This study investigated the effects of combined treatment of immersion liquids (adjusted pH 4.5 with Citrus junos concentrate (CL), pH 5.5 with Prunus mume concentrate (PL), or no pH adjustment, pH 6.5, control) and high hydrostatic pressure (HHP, 450 MPa) on shelf-life and quality of mackerel. In this study, we measured changes in viable cell counts, pH level, volatile basic nitrogen, thiobarbituric acid reactive substances, color analysis, volatile organic compounds, and sensory evaluation of mackerel at $4^{\circ}C$ for 20 days. CL/HHP and PL/HHP treatments reduced viable cell counts by 3 log cycles during storage compared to the control. Mackerel treated with CL/HHP and PL/HHP showed significantly lower TBARS and VBN levels as compared to the control. After combined treatment, lightness and whiteness increased but redness decreased. VOCs tests showed that contents of alcohol, acid, and ketones in mackerel fillet treated with CL/HHP and PL/HHP were relatively reduced. Especially, CL/HHP and PL/HHP suppressed production of sulfur. In the sensory evaluation, aroma, taste, salinity, hardness, and springiness of mackerel treated with combined HHP showed higher scores than the control. These results suggest that immersion liquids and HHP treatments may increase shelf-life of mackerel and maintain quality during storage at $4^{\circ}C$.

• Weed & Turfgrass Science
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• v.6 no.3
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• pp.222-234
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• 2017

Green tides, which was mainly caused by Ulva spp., have been increasing in severity and frequency globally, and have negatively affected on marine ecosystems. This study was conducted to investigate effects of various physical and chemical factors on the death of Ulva australis (ULAUS) and to consider a practical measures useful for alleviating Ulva bloom. Soaking of ULAUS thalli in pure water for 8 hr didn't induce a death, but incubation in 1.0-1.5% salinity for 7 d inhibited sporulation by about 70%. Desiccation gave rise to a serious damage when more than 40-50% of initial fresh weight was lost. ULAUS growth was sensitive to temperature and seriously inhibited from more than $30^{\circ}C$. At $35^{\circ}C$, $40^{\circ}C$, $45^{\circ}C$ and $50^{\circ}C$, treatment time required for 90-95% death of ULAUS thalli was 1 d, 10 min, 30 sec, and 1 sec, repectively. ULAUS growth was seriously inhibited at lower than pH 6.0 and completely dead at pH 4.0. Several compounds for ULAUS control was selected and the chemcals causing a rapid death were oxidants such as hydrogen peroxide and sodium percarbonate. Taken together, our results suggest that low salinities, dryness, pH, high temp. and compounds could be selected for Ulva bloom control, and high temperature and compounds seems to be useful for a development of practical control methods.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.19 no.1
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• pp.53-65
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• 2014

In order to estimate the effect of nutrients addition for phytoplankton growth and community compositons in spring and summer season, we investigated the abiotic and biotic factors of surface and bottom waters at 20 stations of inner and offshore areas in Gwangyang Bay, Korea. Nutrient additional experiments were also conducted to identify any additional nutrient effects on phytoplankton assemblage using the surface water for the assay. Bacillariophyceae occupied more than 90% of total phytoplankton assembleges. Of these, diatom Eucampia zodiacus and Skeletonema costatum-like species was mainly dominated in spring and summer, respectively. Here, we can offer the season why the two diatom population densities were maintained at high levels in both seasons. First, light transparency of spring season in the euphotic zone was greatly improved in the bay. This improvement is one of important factor as tigger of increase in E. zodiacus population. Second, low salinity and high nutrient sources supplied by Seomjin River discharge are a main cue for strong bottom-up effects on S. costatum-like species during the summer rainy season. Based on the algal bio-assays, although maximum growth rate of phytoplankton communities at inner bay (St.8) were similar to those of outer bay (St.20), half-saturation constant ($K_s$) for phosphate at outer bay was slightly lower than those of inner bay. This implied that adapted cells in low nutrient condition of outer bay may have enough grown even the low phosphate and they also have a competitive advantage against other algal species under low nutrient condition. In particular, efficiency of N (+) addition in summer season was higher compared to control and P added experiments. In the bay, silicon was not a major limiting factor for phytoplankton growth, whereas nitrogen (N) was considered as a limiting factor during spring and summer. Therefore, a sufficient silicate supply form water mixing Si recycled from diatom decomposition and river water is favorable form maintaining diatom ecosystems in Gwangyang Bay.

• Korean Journal of Ecology and Environment
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• v.41 no.spc
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• pp.68-76
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• 2008

This study examined the inhibition effects of a freshwater bivalve (Unio douglasiae) and a submerged plant (Potamogeton crispus) on the cyanobacterial bloom (Oscillatoria sp.). The experiment were conducted in aquarium $(50cm{\times}65cm{\times}120cm)$ with lake sediments in the bottom of the aquarium in 10 cm thick. Before the experiments, artificial cyanobacterial bloom was induced with the addition of lake sediment and CB medium. Total 12 transparent acrylic cylinders (${\Phi}19cm$, height 40 cm) were placed in the aquarium, and within which bivalves and plants were placed in various conditions such as the control (C), plant addition (P:5 stems), mussel addition (U:2 individuals), and both mussel and plant addition (PU: the same quantity as used in each treatment). The experiment was conducted in triplicate during 7 days. pH, dissolved oxygen (DO), electric conductivity (EC), salinity, cyanobacterial cell density, chlorophyll-${\alpha}$ concentration, and mussel filtering rate were monitored daily. At the end of the experiment, total phosphorus (TP), total nitrogen (TN), and plant height and weight were measured. Overall, a large degree of cyanobacterial growth inhibition appeared in both P and U treatments, and the effect was highest in the U treatment, followed by P and PU. The combined treatment of both U and P did not show any synergic effects compared to the effect in separated treatment. In all enclosures of the treatments chlorophyll-${alpha}$ (Chl-${alpha}$) concentration decreased until 36 hours after the additions of the plants and mussels. In contrast, Chl-${alpha}$ concentrations increased in PU enclosures after 36 hours. The same trend was shown in the cell density of Oscillatoria. pH and DO gradually decreased until 120 and 144 hours, respectively, in the P and PU enclosures. TP concentration increased in the mussel enclosures (U and PU), while TN concentration largely decreased in the plant enclosures (P and PU). Our results suggest that applied bivalve (Unio) and submerged plant (Potamogeton) seemed to have a potential effect on the growth inhibition of cyanobacteria, but their combined application may have an antagonistic effect to diminish the degree of the inhibition.

• Food Science of Animal Resources
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• v.33 no.2
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• pp.244-250
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• 2013

The objective of this study was to investigate the effects of marinade condition (injection and tumbling process) on the physicochemical and sensory characteristics of marinade steak. The pH of marinade steaks was in the range of 5.26-5.51, with the highest level in the injection/tumbling (IT) treatment, while injection processes tended to result in higher pH levels (p<0.05). Salinity and sweetness contents were determined to be the highest in the IT treatment. Cooking loss was highest in the control (Immersion, 6 hr), but there were no significant differences between control and injection/tumbling, injection/ vacuum/tumbling (IVT), and vacuum/tumbling treatments. Hardness was in the range of 8.01-13.99 kg, with the lowest level observed for the IVT treatment, and the highest level observed for the control. However, there were no significant differences in hardness between injection process treatments and non-injection process treatments. Therefore, injection and tumbling processes have a similar effect on meat tenderness. In the sensory evaluation, there was a significant difference between the control, injection and tumbling process treatments in terms of tenderness, texture preference and taste. These results suggest that injection and tumbling processes improved tenderness, product yield and sensory preference in meat products.

• Journal of Life Science
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• v.23 no.12
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• pp.1454-1459
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• 2013

This study investigated the effects that water temperature and the administration of estradiol-17${\beta}$ (E2) had on the sex ratio and growth of the Japanese eel, Anguilla japonica. Glass eels (total length${\fallingdotseq}$6.5 cm) were differentiated into an E2 group and an E2-free group and then they were reared for about four months at three water temperature levels of $20^{\circ}C$, $24^{\circ}C$, and $28^{\circ}C$. The results showed that the young eels survived normally at the rearing water temperature of ${\geq}24^{\circ}C$, and grew to a mean size of 20 cm (total length). In the E2-free group, temperature was not found to increase the sex ratio (feminizing rates); however, the sex ratio of the E2-administrated group was found to be a little higher at a high temperature ($28^{\circ}C$). The growth of the E2 group was lower than the growth of the E2-free group at $24^{\circ}C$ and the E2 concentration levels in the plasma at $24^{\circ}C$ were found to be significant after the end of the E2 administration period (178 days). Therefore, we thought that long-term administration of E2 must be considered to be the reason for growth decline in spite of the prominent sex ratio effect. Our results indicate that temperature was not related to an increase in the feminizing rate (sex ratio) in the Japanese eel, Anguilla japonica, and other environmental factors (rearing density, salinity, etc.) that have the possibility of inducing ovarian differentiation must be investigated.

• The Korean Journal of Food And Nutrition
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• v.24 no.4
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• pp.753-760
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• 2011

This study was carried out to investigate the effects of various kinds of commercial salts, including Hanju salt, Deep sea water salt, $Salicornia$ $herbacea$ salt, Guwoon salt, Bamboo salt and salt replacement for the reduction of Na concentration in $kimchi$. The fermentative characteristics of these salts were determined during the fermentation at $10^{\circ}C$. $kimchi$ using a salt replacement and with $Salicornia$ $herbacea$ salt showed slow changes in their pH values. The use of salt replacement showed the lowest level(0.97%) of the retardation of $kimchi$ fermentation. For the preparation of $kimchi$ that used a low Na, chemical and microbial changes were investigated during the fermentation of process, examining preparations with both table salt and a salt replacement(CS-17). The salinity level of $kimchi$ prepared with table salt(control) and the salt replacement (CS-17) were 2.17~2.5% and 1.72~1.99% during fermentation, respectively. The Na contents of $kimchi$ with CS-17(562.5 mg%) showed a lower level than that with table salt(879.0 mg%). The growth of Leuconostoc sp. was highest ($1.5{\times}10^8$ cfu/g) in $kimchi$ with CS-17 at 6 day-fermentation, but the highest level($2.3{\times}10^7$ cfu/g) in $kimchi$ with table salt was at 7dayfermentation. The cells of $Lactobacillus$ sp. in the $kimchi$ prepared with CS-17 and table salt increased to $3.0{\times}10^8$ cfu/g and $6.0{\times}10^7$ cfu/g at 8day-fermentation, respectively. It was concluded that the use of CS-17 could reduce Na levels in $kimchi$ and mitigate over-maturation.