• Journal of Environmental Science International
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• v.31 no.11
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• pp.989-992
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• 2022

This study was conducted to investigate the efficacy of larval stages of three species, namely, Tenebrio molitor, Protaetia brevitarsis seulensis, and Ptecticus tenebrifer larvae, in degrading poultry manure, specially, broiler and duck manure. The survival rates of larvae were also noted. For the experiment, T. molitor (n=300), P. brevitarsis seulensis (n=60), and P. tenebrifer (n=300) hatched larvae were randomly divided into six groups with three replicates. The degaradation efficacy tests were then performed for 30 days in a laboratory. The test groups were as follows: T1, 110 g broiler manure + T. molitor larvae (n=50); T2, 110 g duck manure + T. molitor larvae (n=50); T3, 125 g broiler manure + P. brevitarsis seulensis larvae (n=10); T4, 125 g duck manure + P. brevitarsis seulensis larvae (n=10); T5, 105 g broiler manure + P. tenebrifer larvae (n=50); and T6, 105 g duck manure + P. tenebrifer larvae (n=50). The groups showed significant efficacy in degrading broiler and duck manure (p<0.05). The highest survival rates were recorded for T. molitor larvae in both manure types [T1 (92.67%) and T2 (50%)], followed by P. brevitarsis seulensis larvae (T4, 40%) and P. tenebrifer larvae (T6, 14.67%) in duck manure. Next, the survival rates of P. brevitarsis seulensis (T3) and Ptecticus tenebrifer larvae (T5) in broiler manure were 0%. In conclusion, these results point to the feasibility of using insect larvae to degrade broiler and duck manure.

• Journal of Environmental Science International
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• v.31 no.11
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• pp.993-997
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• 2022

This study was conducted to evaluate the structure and composition (i.e., pH, moisture, total-N, pathogens, and volatile fatty acids) of broiler and duck manure treated with larvae of three insect larvae, namely, Tenebrio molitor, Protaetia brevitarsis seulensis, and Ptecticus tenebrifer. Hatched Tenebrio molitor (n=300), Protaetia brevitarsis seulensis (n=60), and Ptecticus tenebrifer (n=300) were used in this study; specially, the larvae were divided into six treatments with three replicates. The treatments were as follows: T1: 110 g broiler manure + Tenebrio molitor larvae (n=50), T2: 110 g duck manure + Tenebrio molitor larvae (n=50), T3: 125 g broiler manure + Protaetia brevitarsis seulensis larvae (n=10), T4: 125 g duck manure + Protaetia brevitarsis seulensis larvae (n=10), T5: 105 g broiler manure + Ptecticus tenebrifer larvae (n=50), and T6: 105 g duck manure + Ptecticus tenebrifer larvae (n=50). For all the larval treatments, the following results were observed: The moisture content of the duck manure treat with three insect larvae was higher than that of the broiler manure (p<0.05), whereas broiler manure had a higher pH (p<0.05). In addition, the total nitrogen content of broiler manure was higher than that of duck manure (p<0.05). However, the insect larvae did not significantly affect pathogens (E.coli and Salmonella) and the volatile fatty acids (p>0.05). In conclusion, the use of the three insect larvae to create organic nitrogen compost using poultry manure is feasible.

• Development and Reproduction
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• v.25 no.1
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• pp.33-41
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• 2021

This study was carried out to observe the development of the autonomous skeletal development of the Favonigobius gymnauchen. Total length (TL) of larvae 3 days after hatching (DAH) were mean TL of 3.34 mm, with a line-shaped parasphenoid ossification in the cranium and basioccipital ossification in the back. The 10 DAH larvae had a mean TL of 5.20 mm, with the number of caudal vertebrae increasing to 15. The urostyle and two hypural bones in the lower part also began to ossify. The 23 DAH juveniles had a mean TL of 8.47 mm. The pectoral girdle's skeleton was completed as the scapula and coracoid were ossified. The pelvic girdle also fully supported the ventral fin as its ossification was completed. Favonigobius gymnauchen and Tridentiger obscurus showed similar characteristics in terms of the anus location of hatched larvae, number of myotomes, and melanophore distribution during the morphological development of the larvae and juveniles. However, this study confirmed differences in the development of the vertebrae and urostyle bone.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.1
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• pp.44-53
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• 2023

In this study, the morphological development and early life cycle of larvae and juvenile Rhinogobius brunneus found in Wicheon, Nakdong River, Korea, were investigated. The fertilized eggs were 2.20×0.68 mm (long×short) in diameter. The eggs began hatching approximately 104 h after fertilization at water temperatures of 17.3-20.5℃ (mean 18.9±1.6℃). The newly hatched yolk-sac larvae were 3.71±0.06 mm in total length (TL), with an unopened anus. Three days after hatching, the preflexion larvae were 4.37±0.16 mm in TL with yolk absorption. Twenty days after hatching, the flexion larvae were 6.50±0.22 mm in TL and the tip of the notochord was bent upward. Twenty-seven days after hatching, the postflexion larvae were 11.8±0.63 mm in TL, and the tip of the urostyle was bent at 45°. Forty days after hatching, individuals measured 18.5±0.93 mm in TL and were considered as juveniles as the number of fins became constant for each part. All the postflexion larvae had detached fins. Additionally, the melanophore was observed to be distributed on the head, centrum of the body, and dorsal fin, and there was a difference in the morphology from the water stream.

• Korean Journal of Ichthyology
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• v.34 no.2
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• pp.86-95
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• 2022

Egg development and morphological change of larvae and juvenile of the Roughscale sole, Clidoderma asperrimum, were investigated in the present study. Adult fishes were collected on the East Sea, Korea, from 2017 to 2018 and reared in a circular water tank (Ø 6×1 m) at water temperature of 12.8±1.9℃. Fertilized eggs ranged from 1.42 to 1.59 mm (mean 1.51±0.04 mm, n=50) in diameter. The eggs were spherical in shape, transparent, floating and colorless. The egg yolk was separated from the egg membrane 60 mins post-fertilization (PF), and an embryo was formed in 62 hrs PF. More than 50% of the eggs hatched within 144 hrs PF in the range of 10.2~11℃(mean 10.8℃). The size of the newly hatched larvae were 4.22~4.64 mm (mean 4.53±0.16 mm) in total length (TL), their mouth and anus were not open yet. At 10 days after hatching, the preflexion larvae reached 5.88~6.62 mm (mean 6.31±0.33 mm) in TL, and the yolk absorption was completed and the mouth began to open. At 55 days after hatching the larvae reached to flexion larvae stage and they were 10.4~13.3 mm (mean 12.7±1.3 mm) in TL, and the tip of notochord was bent upward. At 120 days after hatching the larvae reached to juvenile stage and they were 35.3~40.5 mm (mean 39.5±2.4 mm) in TL. Their all fins had completed set of the fin-rays (D. 79~94: A. 63~75) and the juveniles adopted a benthic life.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.4
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• pp.479-485
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• 2020

We evaluated the hatchability of fertilized eggs from six hybrid combinations of highly valued grouper species inhabiting temperate and warm waters, with the goal of establishing a novel hybrid with enhanced growth and viability during the culturing period in the temperate waters of Korea. Hybrid combinations with red-spotted grouper females exhibited high hatchability with high a fertilization and hatching rate of fertilized eggs and a low deformity rate of hatched larvae. Conversely, hybrid combinations with kelp grouper females had very low hatching rates and very high deformity rates; commercial production of seed from such crosses would be difficult without improving hatchability. The hatchabilities of convict grouper ♀×giant grouper ♂ and kelp grouper ♀×red-spotted grouper ♂ were lower than those of maternal purebreds, but these two hybrid combinations were expected to produce potentially large quantities of hatched larvae. In the above evaluation, promising hybrid combinations were identified for commercial production of seed. For these hybrids to contribute to the development of Korea's mariculture industry, mass production of fertilized eggs and seeds is necessary, along with the development of advanced rearing techniques, such as the identification of a suitable rearing temperature.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.16 no.4
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• pp.395-400
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• 1983

Rock trout, Agrammus agrammus(Temminck et Schlegel) is commonly found at the coast of Korean waters. Mature adult of the rock trout were collected at the shore of Dongbaeksom in Pusan during the period from Nov. 18 to Nov. 25, 1983 through know the early developmental characters. The authors carried out the artificial insemination in the laboratory on Nov. 24, 1982, and roared the eggs and the hatched larvae. The eggs of this species are demersal and adhesive, and their diameter were varied within 1.92-2.14mm. The color of yolk is light blue in the early developmental stage, and then turned to orange before hatching out. The yolk contained numerous tiny oil globules. Hatchig toot plnace in ca. 463 hours after insemination at $11.8-17.9^{\circ}C$ of water temperature. The newly hatched larvae were elongate in share and 6.55-8.20 mm in total length with 12+26=48 myomers. Many branched melanophores were distributed on the supra-orbital, dorsal double body contour, and peritoneal, and also under the notochord of the tail.

• Korean Journal of Ichthyology
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• v.31 no.1
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• pp.23-29
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• 2019

The embryonic development and hatchability of the artificially fertilized eggs of convict grouper (Hyporthodus septemfasciatus) ♀${\times}$giant grouper (Epinephelus lanceolatus) ♂ (CGGG) were compared to those of the maternal pure species (convict grouper ♀${\times}$♂, CG) to establish a novel grouper hybrid for aquaculture industry. The fertilized eggs were divided into nine 5-L beakers (3,000~5,000 eggs/beaker) filled with UV sterilized seawater and incubated at a temperature range of $23.5{\sim}24.8^{\circ}C$ (32.1~32.8 psu). The percentages of fertilization and hatching of CGGG were $69.4{\pm}1.5%$ and $59.0{\pm}5.1%$, respectively and were significantly lower than those of CG (p<0.05). The CGGG proceeded normal embryonic development similar to that of CG, but showed an irregular cleavage, immature embryonic body and spinal deformity in hatched larvae. The incubation time from fertilization to hatching of CGGG was 31 hrs, which was approximately 2 hrs slower than that of CG. Our study provided the possibility of mass production of grouper hybrid CGGG larvae.

• Korean Journal of Veterinary Research
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• v.33 no.1
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• pp.109-117
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• 1993

This paper dealt with the situation and the hatch rate of bot's eggs on the equine hairs in Cheju horse with the species grouping of the bot flies of equine(genus Gasterophilus). The prevalence and infection dynamics of Gasterophilus spp. larvae was also evaluated in the equine alimentary canal submitted in this laboratory for the necropsy or from the abattoir. Samples including Gasterophilus spp. larvae, bot's flies and its eggs, which were collected from the alimentary canal and equine hairs, respectively, were studied and classified by morphology. The morphologic feature of the spines of Gasterophilus larvae were studied by scanning electron microscope. 1. Gasterophilus intestinalis larvae concentrated in the nonglandular portions of the stomach. The infection of second-, and third stage larvae were common in November, and from January to October, respectively. Gasterophilus nasalis larvae were commonly identified on the gastric pylorus and upper portion of duodenum. Second stage larvae were found from October to December, and 3rd stage larvae, from January to September. 2. The hatch rate of laid eggs of Gasterophilus intestinalis was 28.4%, and that of Gasterophilus nasalis was 79.5%. The hatch rate of Gasterophilus intestinalis eggs was highest(62.5%) in December. The hatch rate of laid eggs were higher in the region of scapula(64.0%) and limbs(62.5%) than on the maned hairs. The eggs of Gasterophilus nasalis were completely hatched by October. 3. Eight hundred five Cheju horses examined in this study were infected with the eggs of Gasterophilus spp. Gasterophilus intestinalis eggs on the body regions from sixty horses were recognized in phalangeal (14.4%), in abdominal(13.8%), metacarpal, brachial and cervical regions. Gasterophilus nasalis eggs were uncommon and recognized in submandibular regions(1.4%). 4. In conclusion, the infection of imago, larvae and eggs of both Gasterophilus intestinalis and Gasterophilus nasalis were indentified in cheju horse.

• Journal of Aquaculture
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• v.9 no.1
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• pp.43-55
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• 1996

The experiment was performed to evaluate the possibility of utilizing underground sea water for the seed production of tiger puffer, Takifugu rubripes. For this purpose, the effects of 6 different salinities (3.5, 7.0, 14.0, 20.0, 27.0, $33.0\%_{\circ}$) were determined based on the hatching rate of fertilized eggs, survival rate and the amount of food consumed by hatched larvae, where as the effects of 3 different salinities (20.0, 27.0, $33.0\%_{\circ}$) were also examined with rearing tiger puffer juvenile ($4.29{\pm}0.50$ cm in total length) for 50 days in the closed recirculating water system. As a results, either the hatching or the survival rate of more than $70.0\%$ were obtained from the fertilized eggs reared at the salinity of 27.0 to $33.0\%_{\circ}$, the early hatched larvae at 27.0 to $33.0\%_{\circ}$, and the 10-day-old larvae at 20 to $33.0\%_{\circ}$. At three different salinities, the survival rate of 20-day- and 30-day-old larvae turned out to be $89.0\%$ and $92.5\%$, respectively. The salinity for maximum food intake thus appeared to be from 27.0 to $33.0\%_{\circ}$. In this condition, 20-day-old hatched larvae consumed $323\~342$ Artemia nauplii and 30-day-old hatched larvae ate $1,559\~1,5791$ A. nauplii. The highest growth rate of fingerlings were observed at the salinity $27\%$ and followed by 33.0 and $20.0\%_{\circ}$, respectively. The relationship between the days of rearing (X) and the total length (Y) of the fingerlings were as follows : $33.0\%_{\circ}$ group : Y=0.107X-2.532 (r=0.982) $27.0\%_{\circ}$ group : Y=0.116X-3.195 (r=0.975) $20.0\%_{\circ}$ group : Y=0.116X-2.693 (r=0.987) The slopes of regression line estimated from $27.0\%_{\circ}$ and $33.0\%_{\circ}$ groups were significantly different from that of $20.0\%_{\circ}$ group.