• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.5
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• pp.469-475
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• 2002

The rotating biological contactor (RBC) was tested for treatment of aquacultural water in a pilot-scale recirculating aquaculture system. Performance of RBC on the treatment of nitrogen source such as total ammonia nitrogen (TAN), nitrite nitrogen and nitrate nitrogen and chemical oxygen demand (CODcr.) was evaluated. A system was stocked with nile tilapia at an initial rearing densities of $5\%$ and $7\%$ over 30 days. As increasing rearing density from $5\%$ to $7\%$, the TAN removal rates was increased from $39.4 g/m^3{\cdot}day$ to $86.0 g/m^3{\cdot}day$. But TAN removal efficiency was decreased from $24.5\%$ to $16.0\%$. The removal rate of $COD_Cr$ was higher than TAN. The RBC as an aerator was also evaluated for increasing dissolved oxygen concentration. For $5\%$ and $7\%$ of rearing density, the average aeration rate were $280 g/m^3{\cdot}day$ and $255 g/m^3{\cdot}day$, respectively.

• The Korean Journal of Malacology
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• v.26 no.4
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• pp.297-302
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• 2010

Water temperature, salinity and density on egg development of the sunray surf clam, Mactra chinensis were investigated for artificial seedling production. The required time from fertilization to D-shaped larvae were 33.8 hours in $18^{\circ}C$, 20.6 hours in $23^{\circ}C$, 18.2 hours in $28^{\circ}C$ and 15.0 hours in $33^{\circ}C$. The development duration was reduced with increasing temperature. The relationships between temperature and the required time from egg to each developmental stage were described as follows: 2-cell, 1/h = 0.1051WT - 1.4782; 8-cell, 1/h = 0.037WT - 0.3686; gastrula, 1/h = 0.008WT - 0.0521; trochophore, 1/h = 0.0041WT - 0.0235; D-shaped larva, 1/h = 0.0024WT - 0.0102. Biological minimum temperature for the egg development was estimated to be $8.0^{\circ}C$ in average. The possible range of temperature for the development of D-shaped larvae was $18-28^{\circ}C$ and optimum of water temperature for the development of egg was $23^{\circ}C$. The possible range of salinity for the development of D-shaped larvae was 20-35 psu and optimum of salinity for the development of egg was 30-35 psu over 25 psu at least. The density of fertilized egg was below 40 per 1 ml in rearing seawater for elevating the development rate from fertilized egg to D-shaped larva.

• Korean Journal of Poultry Science
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• v.48 no.2
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• pp.91-100
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• 2021

The study determined the effects of stock density (SD) and energy level (EL) on growth performance, serum biochemistry, and meat quality in Korean native chickens. A total of 240 chickens were randomly assigned to one of the four treatments including two stock density (low, 14, and high, 16 chickens per m²) and two energy level (low, 2,950, 3,000, 3050 ME kcal/kg, and high 3,150, 3,200, 3,250 ME kcal/kg, for starter, grower, and finisher, respectively). During the whole period of the experiment, the chickens were fed ad libitum. The greater final body weight and weight gain were achieved in chickens fed high energy diet, whereas the final body weight and weight gain were significantly reduced in high-density treatment compared with the low density. Chickens in low-density groups had a higher feed intake compared with high-density treatment, however, the energy level did not affect the feed intake. An improved overall feed conversion ratio was detected in the high energy treatment. There was a significant interaction between stock density and energy level on cholesterol concentration. The concentration of aspartate transaminase in serum was increased by higher stock density. There was a significant treatment interaction on IgM levels. Moreover, the carcass rate was significantly increased in the high energy level treatment. Based on the findings, we suggest that rearing chickens in low density with high dietary energy levels could be beneficial by improving the growth performance.

• Journal of Aquaculture
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• v.18 no.4
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• pp.260-266
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• 2005

In order to obtain the aquaculture fundamental data far resources enhancelnent of the Protothaca jedoensis, the egg development and larva growth were investigated at different conditions such as water temperature, phytoplankton and density. Water temperature, at which P. jedoensis egg successfully completed development, ranged from $15{\~}30^{\circ}C$. The required time from fertilization to D-shaped larva was 39.7 hours at $15^{\circ}C$, 31.2 hours at $20^{\circ}C$, 26.8 hours at $25^{\circ}C$ and 26.2 hours at $30^{\circ}C$ P. jedoensis. In regard to water temporature, growth and survival rates of larvae were high at $30^{\circ}C$. In growth and survival rates of larvae with various rearing densities, the highest aver-age growth and survival rates were 4${\~}$6 ind./ml When larvae were fed mixed phytoplankton, such as Isochrysis galbana, Pavlova lutheri and Chaetoceros calcitrans, their growth and survival rates were the high among the groups. In growth and survival rates of larvae with various rearing food concentrations, the highest average growth and survival rates were $218{\mu}m$, and $45\%$ at the food concentration of $1{\times}10^4$ cells/ml, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.1
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• pp.21-26
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• 2002

The behavior of the biological water treatment process on start-up operation was evaluated in the integrated recirculating aquaculture system consisting of a double drain type rearing tank ($2.5 m^3$), a sedimentation tank, a floating bead filter, a foam separator and a rotating biological contactor. A system was stocked with nile tilapia (Oreochromis niloticus) at an initial rearing density of $2\%$ for 2 weeks for acclimated rotating biological contactor. The total ammonia nitrogen (TAN) level increased to $13.6 g/m^3$ on day 4 after adding feed and was decreased to $0.3 g/m^3$ on day 7. The total suspended solid was completely removed during overall experimental period.

• Korean journal of applied entomology
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• v.58 no.4
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• pp.381-387
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• 2019

From 2017 to 2019, the ovipositional and the developmental characteristics of Gampsocleis ussuriensis Adelung in the Buan area of Jeonbuk Province were examined. G. ussuriensis were mostly found in the weeded areas around the reservoir, where the adults first appeared in mid-July, showed up where by the early September, and overwintered in eggs. Nymphs appeared in early April to mid-July the next year. The nymphs hatched from early April and adults appeared after molting five times. The ovipositional period of G. ussuriensis was approximately 58 days. The total number of eggs per female was 124. The mean longevity of adults was 95.6 days for females and 84.8 days for males. Ovipositional mats were best with mixed Masato and Coco-Pitt at a ratio of 7:3. Developmental period of G. ussuriensis nymphs was 64.1 days at 24℃ and was longer than at different temperatures. The higher the temperature, the shorter the developmental period. The survival rate of nymphs was the best at 32℃ in 77.8%. The higher the density while rearing, the lower the survival rate, and the faster the development and molting velocity.

• Journal of Aquaculture
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• v.3 no.1
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• pp.89-125
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• 1990

In order to improve top shell seed production techniques spawning and larvae rearing were done in rearing tanks. Growth of young top shell in the nursing ground were also investigated. For induced spawning, top shells were maintained in still water during night time. Then they were treated with ultra violet iradiated sea water after dried up in air for 60 minutes. Spawning rate were 10 to $39.77\%$. It was found that young top shells moved in the growing grounds from nursing grounds when they reached approximately 30-40mm in shell heignt. Among main food algae for top shell in the natural growing grounds, sea mustard were melted away during June. Therefore, presence of another food algae such as Ecklonia cava or Sargassum spp. seems to be the main limiting factor for survival of top shell during summer. The tolerance of top shells ranging from 30mm to 60mm to low density of seawater for were tested at the temperature between 29.5 and $31.4^{\circ}C$. Hundred percent mortality occoured in 20, 55 and 90 hours after first stocking at the specific gravity of 1.010, 1.015, and 1.020, respectively.

• The Korean Journal of Malacology
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• v.19 no.2
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• pp.143-152
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• 2003

Water temperature during the culturing period was 10.4-25.5$^{\circ}C$ and there was a little difference between rearing sites. Salinity (25.00-31.17 psu) and DO (over 6.13 mg/l) showed reasonable condition for the growth of bay scallop. Concentrations of chlorophyll-a were ranged 1.69-7.40 $^{\mu}$g/l, and they fluctuated monthly in the every sampling site. During the growing period from June to October, dominant phytoplankton species were Ceratium sp. in Nammeon and Hoejin, Chaetoceros sp. in Dolsan. Density of phytoplankton was high in July, August and October, but it was low in September and November. When young bay scallops were cultured for 185 days in Nammyeon, Hoejin and Dolsan, shell heights were grown for 0.19 mm/day, 0.18 mm/day and 0.16 mm/day, respectively, and total weights were increased 0.16 g/day, 0.16 g/day and 0.13 g/day, respectively. Daily growth rates of shell height were 0.606%, 0.581% and 0.549%, and daily growth rates of total weight were 1.972%, 1.857% and 1.746%, respectively. Maximum predicted values of shell height calculated by von Bertalanffy growth model were 52.62 mm, 51.74 mm and 48.91 mm, respectively. Survival rate was the highest in Nammyeon (87.0%), but the rates in Hoejin and Dolsan sharply decreased after November.

• Journal of Aquaculture
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• v.22 no.1
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• pp.118-121
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• 2009

This experiment was conducted to evaluate the effects of different substrates in rearing tank on growth and body composition of juvenile sea cucumber Apostichophus japonicus. Sea cucumber (average weight 3.6) were randomly distributed at a density of 10 juvenile per tank into nine tanks providing three different substrates including free-substrates, sand and wave-shaped plastic sheet as (shelter). Juveniles were fed with a commercial feed once in every 2 days for 8 weeks. At the end of the experiment, survival of sea cucumber was not affected by the presence of substrates (P>0.05). Weight gain and specific growth rate of sea cucumber reared in the tanks with sand were significantly higher than those of sea cucumber reared in the tanks with shelter and without substrate (P<0.05). Crude protein and crude lipid of whole body in sea cucumber reared in free-substrate tanks were significantly higher than those of juvenile reared in the tanks with other substrates (P<0.05). Higher ash content was obtained in sea cucumber reared in the tanks with sand compared to that of juvenile reared in the tanks with other substrates (P<0.05). The results of this study suggest that growth and proximate composition of whole body of sea cucumber was significantly affected by substrates. Among materials tested, sand may be a proper substrate for sea cucumber culture.

• Journal of Marine Life Science
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• v.5 no.2
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• pp.51-57
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• 2020

Disinfection and maintenance of rearing water in aquaculture is an essential element for the prevention of fish diseases. This is especially important in recirculating aquaculture systems (RAS) in which fish are reared at high density using recycled water. In this study, tilapia was reared in two different RAS (one with plasma generator - PW system, another without plasma generator - No PW system). In plasma treated group, UVT% of water was improved clearly, and the number of heterotrophic bacteria decreased significantly after 40 days. Total weight gain of tilapia in PW system was significantly higher, and other growth indicators were also relatively higher although not statistically significant. In addition, the fish in PW system had a 100% survival rate, and there were no histological differences between fish from both systems. Fish did not seem to be affected by the toxicity of ROS. In conclusion, it is expected that plasma water can effectively deactivate fish pathogens and improve the quality of rearing water.