• Journal of Aquaculture
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• v.11 no.4
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• pp.449-455
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• 1998

The small size food organism(under the size 150${\mu}m$) is needed as food for early stage of marine fish larvae of small mouse (e.g the group of grouper). This study was investigated to develop a method for copepod Apocyclops sp. culture in combination with the rotifer B. rachionus for stable culture of copepod species and harvest of various size food organisms. The culture conditions as temperature, salinity, culture volume, photo period, culture preiod and observation interval were 25${\circ}C$, 22ppt, 40ml, all dark except to observation time, 16 days and every two day during the experimental period, respectively. The Tetraselmis suecica was used as the food for the two testing orgtanisms. After every two day counting, theses two organisms were transferred to fresh culture tanks with Tetraselmis suecica of $7{\times}10^5$cells/ml. In the mixed culture of B. rotundiformis and A. sp., growth of rotifer was suppressed by mixed culture with A. sp. whereas the growth of copepod Apocyclops was promoted in the mixed culture with rotifer B. rotundiformis (the maximum density was 22 individuals/ml through the 16 culture days). Moreover, the number of copepod nauplius were promoted about 2 times in the mixed culture compared to the numbers in single species culture. With this combination culture, the havested two food organisms of variable sizes. This size variation of food organisms was useful tools for larval rearing of small mouse marine fish larvae and next step food organism size of post hatched larvae.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.5
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• pp.501-508
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• 1994

This study was undertaken to get basic data for the cold-waterless transportation of live fish. The optimal cold temperature of plaice, Paralichthy olivaceus was determined by checking the changes of dissolved oxygen and ammonia in the sea water and the survival times during storage at various temperatures. After determination of optimal temperature for transportation, the changes of serum components and muscle components of live plaice were also carried out during storage at cold($5^{\circ}C$)-waterless conditions and the recovery conditions($10\%$ density at $15^{\circ}C$). At higher storage temperature, decreases in dissolved oxygen and the increases in ammonia in seawater were observed. In addition, the survival time was short at low temperature($0^{\circ}C\;and\;3^{\circ}C$). Almost all of the serum components(hemoglobin, glucose, LDH, GOT and GPT) of live plaice gradually increased during storage in cold-waterless conditions, and then those values decreased to the initial levels after $3{\sim}10hrs$ storage in conditions of recovery. The concentration of ATP in the muscle steadily decreased during storage in cold-waterless conditions. The contents of ADP and IMP seemed to be directly related to the extent of ATP breakdown. ADP and IMP thus showed a gradual increase during storage. The level of lactate in the muscles gradually increased during these storage times, also. On the other hand, the levels of those components in the muscle entirely recovered to their original levels within $3{\sim}6hrs$ storage after they were returned to conditions of recovery. The ratio of ATP to the ATP and its related compounds${ATP/(ATP+ADP+AMP+IMP){\times}100}$ in the muscle showed $45\%$ after 18hrs storage in cold-waterless conditions. Otherwise, ratios returned to their original levels within $3{\sim}6hrs$ of storage in recovery conditions.

• Korean Journal of Ecology and Environment
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• v.57 no.1
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• pp.39-50
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• 2024

In ecosystems within limited resources, interspecific competition is inevitable, often leading to the competitive exclusion of inferior species. This study aims to provide foundational information for the conservation and restoration management of Microphysogobio rapidus by evaluating species' ecological response to biological factors within its habitat. To understand this relationship, we collected food web organisms from site where M. rapidus coexist with Microphysogobio yaluensis, a specie ecologically similar to M. rapidus, and evaluated the trophic levels (TL), isotopic niche space (INS), and the overlap of INS among fishes within the habitat using stable isotope analysis. Our analysis revealed that the M. rapidus exhibited a higher TL than M. yaluensis, with TL of 2.6 and 2.4, respectively. M. yaluensis exhibited a broad INS, significantly influencing the feeding characteristics of most fish. Conversely, M. rapidus showed a narrow INS and asymmetric feeding relationships with other species, in habitats with high competition levels. This feeding characteristics of M. rapidus indicate that the increase in competitors sharing the similar resources lead to a decrease in available resources and, consequently, is expected to result in a decrease in their density.

• Journal of Bio-Environment Control
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• v.33 no.1
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• pp.55-62
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• 2024

This study aimed to compare the nutrient uptake rate, growth and yield of strawberry grown under the aquaponic and hydroponic systems in a plant factory. For aquaculture, 12 of fish (Cyprinus carpio cv. Koi) were raised in an aquaponics tank (W 0.7 m × L 1.5 m × H 0.45 m, 472.5 L) filled with 367.5L of water at a density of 5.44 kg·m^-3. The 30 seedlings of strawberry were planted in ports filled with perlite substrate and then were placed on the bed (W 0.7 m × L 1.5 m × H 0.22 m) at the top of the aquaponics system, and the 30 seedlings were planted in net-pots and then placed on the holes of acrylic plates (140 cm × 60 cm, Ø80 mm) on the bed (W 0.7 m × L 1.5 m × H 0.22 m) at the deep flow technique (DFT)- hydroponics. The pH and EC of the aquaponic solution was ranged from 4.3 to 6.9 and 0.32 to 1.14 dS·m^-1, respectively, while those of hydroponics were ranged from 5.1 to 7.5 and 1.0-1.8 dS·m^-1, respectively. The NO₃-N and NH₄-N concentration of the aquaponic solution were higher about 3.6 and 2.2 me·L^-1 than those of the standard hydroponic solution for strawberry cultivation. The P, Ca, Mg, and S ions in the aquaponic solution were also higher about 0.76, 3.1, 0.8, and 0.9 me·L^-1 than those of standard hydroponic solution, respectively, while the K and Fe were lower about 0.8 me·L^-1 and 0.5 mg·L^-1, respectively. The mineral contents of the strawberry leaves grown on aquaponics did not differ from that of hydroponics, and K content in the leaves were in an appropriate range. Uptake rates of T-N and P between the 58 and 98 days after transplant (DAT) were 1.5 and 1.9-fold higher in the aquaponics than those of hydroponics, respectively with no significant difference in the uptake rate of K. The crown diameter, plant height, and leaf length and width in the 98 DAT were significantly higher in aquaponics. The number of fruits per plant was significantly higher in aquaponics than those in hydroponics, and the fresh and dry weights of fruit and length and width of fruit were significantly higher in hydroponics. The results suggest that plants in aquaponics continuously utilize fertilizer components of solid particles from fish and feed wastes.

• Journal of Aquaculture
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• v.9 no.3
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• pp.187-194
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• 1996

Sixteen strains of marine rotifer, Braohionus plicatilis were isolated from salt pond, estuary and lagoon. Among 16 strains, 2 strains were large (L)-type and the others were small (S) or ultra small (US)-type. Four strains of fresh water rotifer, B. calyciflorus were isolated from commercial fish ponds. The size of lorica and resting egg were measured. In B. plicatilis, the range of lorica length from S-type and S-type were $244.3{\~}255.3\;{\mu}m$ and $131.0{\~}165.8\;{\mu}m$, respectively. The major axis of resting egg in the marine rotifer were $93.7\~116.4\;{\mu}m$ for S-type and $142.4{\~}145.5\;{mu}m$ for L-type, respectively. In freshwater rotifer, B. calyciflorus, the size range of lorica and major axis of resting egg were $211.8\~229.9\;{\mu}m$ and $126.8\~140.2\;{mu}m$, respectively. The size of freshwater rotifer was larger than that of S-type marine rotifer, but smaller than that of L-type one. Growth and formation of resting egg of B. plicatilis were different among the strains. The maximum density of S-type and L-type rotifer was 753.3 inds./ml for H-S strain and 220 inds./ml for O-L strain, respectively. The largest production of resting egg of S-type and L-type rotifer were 86.7 inds./ml for YY-S strain and 45.8 inds./ml for O-L strain, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.2
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• pp.148-152
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• 2000

To provide basic information on the integumentary system of the blenny, Pholis nebulosa, ultrastructures of epidermal and dermal layer were examined by means of the light and transmission electron microscope. The skin of the blenny consisted of epidermal and dermal layer. Epidermal layer consisted of supporting cell and unicellular gland. The supporting cells were classified into superficial cell, intermediated cell and basal cell, and the gland cells were classified into mucous secretory cell and club cell. The cytoplasm of supporting cells was divided into cortex and medullar part. In the cortex and medullar part, microfilaments and cell organelles were well developed, respectively. Superficial cell of epidermal layer was cuboidal and contained nucleus of horseshoe shape. Intermediated cell had a nucleus of irregular form and the electron density was higher than the other supporting cells, Basal cell was columnar, but nucleus was situated in the upper cytoplasm. Cell organelles of the basal cell were poor than the other supporting cells, but membrane interdigitations were well developed. The cytoplasm of mucous secretory cell had a well-developed ovoid secretory granules, which reacted to red with AB-PAS reaction. The club cell had a we31-developed round secretory granules and endoplasmic reticulum. figment cells were classified into two type. The one contained pigment granules of electron dense, and the other contained reflecting platelets. The cytoplasm of fibrocyte had n well developed rough endoplasmic reticulum.

• Journal of Life Science
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• v.19 no.10
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• pp.1410-1416
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• 2009

The present study aims to examine the effect of turbid water on fishes in streams which branch into a turbid water area (Yeongyang-gun) and a non-turbid water area (Cheongsong-gun), and finally flow into the Imha reservoir. In a comparison of water quality, the chemical status of the water showed higher pH, DO and SS in the turbid water area than in the non-turbid water area. Also, high density of clay minerals such as vermiculite (V) and illite (I), which is from clay mineral leakage during rainfall, was detected in turbid water, resulting in an increase of turbidity. Fishes inhabiting the turbid water showed irregular spaces in gill lamella, cell separation, edema, and clubbing in epithelial tissues. Also, the gill surface showed roughness and plenty of muddy debris substances inside the gills. The Bowman's space was expanded because of contraction of the glomerulus in the Bowman's space of the kidney tissues. Antioxidant enzymes such as SOD, CAT, GPX, and GST showed higher activities in the specific tissues, muscles and kidney, of fishes living in turbid water than in the non-turbid area. We suggested that; first, the antioxidant activities were increased due to removal of harmful radicals generated in fish bodies in the turbid water area, second, long-time exposure of these histological changes in the tissues might have induced secondary lesion accompanying the inaccurate physiological constancy of fishes.

• Korean Journal of Environmental Biology
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• v.30 no.4
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• pp.355-361
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• 2012

Genus of Gambierdiscus, Ostrepsis, Prorocentrum, Coolia and Amphidinium are epiphytic ciguatoxin-producing armored dinoflagellate, often attached on macroalgae. These organisms are the primary causative agent of ciguatera fish poisoning which occurs in tropical and subtropical regions. However, regardless of the fact that population of epiphytic dinoflagellates have expanded to such temperate areas from sub-trophic and trophic areas, monitoring of the epiphytic dinoflagellates was greatly lacked in coastal water of Korean Peninsula. This study was performed in the Korean Peninsula in November, 2011. Cell densities of Gambierdiscus spp. on macroalgae ranged from zero to 10 cells $g^{-1}$ and the maximum density was recorded at St.18 (Pohang guryongpo). The abundance of Ostreopsis spp. was highest on macro-algaes Chondrus ocellatus, Lomentaria catenata and Plocamium telfairiae (140 cells $g^{-1}$). The maximum abundance of Prorocentrum, Coolia and Amphidinium were 52, 3 and 1 cells $g^{-1}$, respectively. Of these, Prorocentrum lima was observed at most stations of East Sea. Therefore, our results suggest that the epiphytic armored dinoflagellates may have adapted to Korean coastal water of temperate areas (i.e., East Sea) and those abundances may be related to the macroalgal species.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.3
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• pp.257-261
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• 2000

Integumentary system of the polychaete, Perinezeis aibuhitensis was consisted cuticular, epidermal and dermal layers. Excretory pores opened in cuticular layer, which is covered with epicuticular projections. The hemidesmosomes were observed between supporting cell and basal area of cuticular layer. The epidermal layer was consisted supporting cells and unicellular glands. Supporting cell was relatively larger than the other neighbouring cells, and the nucleus had one to two nucleolus. Cytoplasm of the supporting cell had well-developed intracellular organs such as tonofilaments, mitochondria, rough endoplasmic reticula, free ribosomes and pigment granules of electron dense. The gland cells were reacted with blue in AB-PAS, and classified into the three types such as ${\alpha},\;{\beta}\;and\;{\gamma}$ from the transmission electron microscopic observation. Type ${\alpha}$ gland cell was ovoid and the cytoplasm had well-developed tonofilaments and membrane bounded secretory granules of $0.8{\~}1.5 {\mu}m$ in diameter. Type ${\beta}$ gland cell had a large vacuole and secretory granules of $0.5{\~}0.8 {\mu}m$, which scattered evenly in the cytoplasm. Type ${\gamma}$ gland cell had well-developed endoplasmic reticulum, Golgi auparatus and secretory granules of $0.2{\~}0.3 {\mu}m$ in diameter. The electron density of this granules was the highest among the granules.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.2A
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• pp.123-130
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• 2012

A cooling system is indispensable for the fossil and nuclear power plants which produce electricity by rotating the turbines with hot steam. A cycle of the typical cooling system includes pumping of seawater at the intake pump house, exchange of heat at the condenser, and discharge of hot water to the sea. The cooling type of the nuclear power plants in Korea recently evolves from the conventional surface intake/discharge systems to the submerged intake/discharge systems that minimize effectively an intake temperature rise of the existing plants and that are beneficial to the marine environment by reducing the high temperature region with an intensive dilution due to a high velocity jet and density differential at the mixing zone. It is highly anticipated that the future nuclear power plants in Korea will accommodate the submerged cooling system in credit of supplying the lower temperature water in the summer season. This study investigates the approach flow patterns at the velocity caps and discharge flow patterns from diffusers using the 3-D computational fluid dynamics code of $FLOW-3D^{(R)}$. The approach flow test has been conducted at the velocity caps with and without a cap. The discharge flow from the diffuser was simulated for the single-port diffuser and multi-ports diffuser. The flow characteristics to the velocity cap with a cap demonstrate that fish entrainment can significantly be minimized on account of the low vertical flow component around the cap. The flow pattern around the diffuser is well agreed with the schematic diagram by Jirka and Harleman.