• Journal of Aquaculture
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• v.12 no.1
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• pp.31-38
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• 1999

The dietary value and fatty acids composition for the hatched neonates from the resting eggs of marine roofers, Brachionus plicatilis and B. rotundiformis were compared with that for mass-cultured rotifers (control) by feeding them to larvae of flounder (Paralichthy olivaceus) and parrot fish (Oplegnathus fasciatus). Resting eggs were mass-produced in $1~4m^3$tanks by feeding Chlorella sp. and baker's yeast. The B. plicatilis and B. rotundiformis eggs were preserved at $5^{\circ}C$ in darkness for 3 and 5 months, respectively, and hatched at $28^{\circ}C$ under continuous light. The hatched neonates from the resting eggs and mass-cultured rotifer, which was used as a rontrol were fed to fish larvaes. The growth and survival rates of parrot fish larvae fed on the neonates from the resting eggs of B. rotundiformis were similar to those of fish larvae fed on the control rotifer. And the growth and survival rates of the flounder larvae with neonates from the resting eggs of B. plicatilis were similar or higher than those fed the control rotifer. Also the fatty acids composition of the neonates from the resting eggs of B. plicatilis and B. rotundiformis were similar to those from the control rotifers. This results showed that the hatched neonates from resting eggs of rotifer could be used as an effective diet for flounder and parrot fish larvae.

• Korean Journal of Ichthyology
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• v.36 no.1
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• pp.1-9
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• 2024

This study investigated the early life history of the Boleophthalmus pectinirostris living in the southern coastal Yeoja-man and compared the results with the same Gobiidae fishes. The brood stork used in the study were captured with bare hands in the tidal flats of Beolgyo-eup, Jeollanam-do, in June 2015. The amount of spawning was 411~11,688, and the eggs were short oval and the size was 1.40×0.72 mm. The time of hatched took 91 hours and 35 minutes at a water temperature of 25~27℃. Newly hatching larvae, the yolk sac had a total length of 3.02~3.31 (average 3.17±0.08, n=30) mm and did not eat rotifer. 4 days after hatching, the total length was 3.31~3.52 (3.43±0.07, n=30) mm, and as the mouth and anus opened, the fish transitioned to the preflexion larvae and fed. 14 days after hatching, the total length was 5.06~5.25 (5.16±0.06, n=30) mm, and the distal end of the vertebra was completely bent at 45° and the transitioned to the postflexion larvae. 41 days after hatching, the total length was 14.3~16.8 (15.4±0.85 mm, n=30), and the number of fins reached an integer of 5 first dorsal fins, 26~27 second dorsal fins, 24~27 anal fins, and 6 ventral fins, and the transitioned to the juveniles. As a result of the study, star-shaped melanophore were deposited from the front of the pectoral fin to the base of the caudal fin, which distinguished them in form from other postflexion larvae of Gobiidae fishes.

• Development and Reproduction
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• v.6 no.1
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• pp.37-44
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• 2002

First sexual maturity, sex ratio, spawning frequency, deposition of the egg capsules and fecundity of the female Rapana venosa(Valenciennes) inhabited in the artificially closed slag deposit area, Gwangyang Bay were investigated by histologicai and visual observations for natural living resource management. The rate of individuals reaching the first sexual maturity was 51.6％ in females measuring 7.1~8.0 cm in shell height, and 100％ in those > 10.1 cm. The total number of egg capsules per individual and the mean number of eggs in an egg capsule were 192~382 and 500, respectively. However, the number of eggs per individual and sizes of egg capsules under lower salinity and deficient food conditions in the closed slag deposit area were smaller than those under the optimum salinity and sufficient food conditions in the open regions. Fecundities of the species were approximately from 96,000 to 191,000 eggs/individual with two to low broods(spawning frequencies) during the spawning season. The duration of development in egg capsules was 18~19 days at about 18~2$0^{\circ}C$. R. venosa is a species whose embryos hatch as veliger larvae, not juvenile snail. The sex ratio of female : male was not significantly different from 1 : 1($\chi$$^2$= 0.23, p>0.05).

• Biomedical Science Letters
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• v.24 no.2
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• pp.125-129
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• 2018

Megaselia scalaris, also known as the scuttle fly, has a humpbacked morphology and was categorized as an insect undergoing complete metamorphosis. Megaselia scalaris was reported to be found in diverse environments. Recently, the scuttle fly has been a focus of studies by forensic scientists, geneticists, and developmental biologists. However, detailed research into scuttle fly development is still unclear. Therefore, the current study has been performed to elucidate the development of Megaselia scalaris. The scuttle fly undergoes four distinct stages of development: egg, larva, pupa and adult fly. After mating, the scuttle fly eggs hatch within one day and become larvae. The newly generated larvae go through 1, 2, and 3 instar stages within a period of 5~10 days. The instar stage 1 takes 1~2 days, instar stage 2 takes 1~2 days, and instar stage 3 takes 3~5 days. Depending on the environmental temperature, the pupae stage takes approximately 10~15 days to complete. The pupa stage can be divided into five sub-stages: 1~3 days, 4~6 days, 7~9 days, 10~12 days and 13~15 days. After molting, the newly formed adult scuttle fly can fly after one day. The morphological characteristics of the scuttle fly during each stage of development was detailed within this study.

• Environmental Analysis Health and Toxicology
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• v.24 no.1
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• pp.1-8
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• 2009

In this study, we obtained the fertilized eggs from goldfish(Carassius auratus) and observed normal developmental stage(from fertilized eggs to larvae) in non-exposed groups. Goldfish embryos at 3 h postfertilization(hpf) were statically exposed for 1 h to either dimethylsufoxide(DMSO, 0.1%, v/v) or TCDD($0.5{\mu}g/L$). Toxicity and morphological changes were characterized from 3 to 120 h postfertilization(hpf). Egg mortality($0{\sim}48$ hpf) and hatching ratio($72{\sim}83$ hpf) in TCDD-exposed group were significantly different from control groups. However, pericardial edema was first observed at 72 hpf, followed by the onset of yolk sac edema and mortality. In addition, goldfish embryos-larvae exposed to TCDD significantly increased TCDD-related gene such as CYP1A($24{\sim}72$ hpf) and AhR2(72 hpf). This is the first study about in-depth characterization of TCDD-induced developmental toxicity in goldfish(Carassius auratus).

• Journal of Fisheries and Marine Sciences Education
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• v.26 no.6
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• pp.1209-1216
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• 2014

This feeding experiment was conducted to investigate the effects of slurry type diet on growth performance and survival rate of growing leptocephalus, eel larva. We need to find new materials of diets for rearing eel larvae. Test diets were formulated with the eggs of the shark, fish soluble concentrate, soybean peptide and fish protein hydrolysate. Fish (average length 6 mm) were fed 3 slurry type diet(A, B and C) based on shark egg for 5 times per day. During feeding experiment, survival rates were significantly different among 3 slurry type diets. Total protein, lipid, moisture, ash and free amino acids contents were analyzed for slurry type diets. Leptocephalus fed the C slurry type diet was grown up to $38.0{\pm}9mm$ at 150 days. But all leptocephalus fed B slurry type diet were died at 100 days, reaching $16.4{\pm}8mm$. This results suggest that basic information for diet development of eel leptocephalus.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.5
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• pp.644-650
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• 2023

We examined the effects of serotonin on the spawning response, sperm motility, and D-shaped larva production in Eastern Gooeyduck clam Panopea sp. based on the sperm densities at fertilization and washing after mixing the eggs and sperm. The highest spawning induction was found showed in females and males injected with 1 mL of 2 mM serotonin. The spawning responses in females and males were higher at concentrations greater than 1 mM and 0.75 mM, respectively. Regarding the activities of sperm in sea water after serotonin injection, the sperm showed activity at >90.0% until 120 mins. We also examined the effects of sperm concentration at the fertilization and washing times after mixing the eggs and sperm. We confirmed that washing within 1 minute at a concentration of 1,500 sperms/mL or less can prevent egg destruction by polyspermy and secure a large number of D-phase larvae. These results should be useful for developing the aquaculture process for Eastern Gooeyduck clam, Panopea sp.

• Korean journal of applied entomology
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• v.12 no.1
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• pp.29-32
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• 1973

This experiment has been carried out to establish the most effective rearing method of rice stemborer, Chilo suppressalis (Walker) on artificial diets under the aseptic condition. The results obtained were summarized as follows: 1. Semi·synthetic diet was giving better results in the weight of matured larvae (96.4mg), emerging rate$(96.7\%)$ and number of egg masses (2.6) than other diets studied. 2. Number of egg masses and hatching rate were significantly increased on the semi-synthetic diet and chemically defned diet, and it may be due to the choline chloride in the diets, 3. Rice seedling was used as a convenient food material. However, it requires more labours and causes more damages of larvae in replacement of fresh seedlings. 4. A different result in larval weight and pupation rate was observed between simplified diet no. 1 and diet added with chlorella. 5. Simplified diet resulted in low hatchability in the second generation, which may be due to the mulnutrition of the diet for adults. 6. The pupation rate was significantly decreased by infection of microorganisms on matured larvae.

• Development and Reproduction
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• v.12 no.2
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• pp.133-139
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• 2008

The eggs of Luciogobius grandis attached beneath the small stone were collected at Ocheon-dong, Yeosu-city from February to May, 2006. We carried them to the laboratory of Chonnam National University to investigate their development. The fertilized eggs were elliptical in shape (mean long axis: $2.06{\pm}0.23\;mm$; mean short axis: $0.74{\pm}0.04\;mm$) and transparent. There were filaments on the egg membrane. Their hatching was occurred at 120hrs 54mins after the morula stage at $18.4{\sim}21.0^{\circ}C$ (mean $19.4^{\circ}C$). The newly hatched larvae were $3.30{\pm}0.07\;mm$ (n=30) in total length (TL), with $34{\sim}36$ myotomes, and their mouth and auns were already open. Their melanophores were appeared over the gas globule, around the anus and a part of caudal peduncle. At 9 days after hatching, the larvae was $5.06{\pm}0.18\;mm$ (n=30) in TL and transformed to postlarval stage with yolk absorption. At 29 days after hatching, the larvae attained full fin ray count and reached the juvenile stage with $11.46{\pm}0.12\;mm$ (n=30) in TL.

• Development and Reproduction
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• v.12 no.3
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• pp.207-213
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• 2008

In order to monitor the developmental features of embryos, larvae, and juveniles of chub mackerel, Scomber japonicus, the fertilized eggs were obtained by artificial insemination. The fertilized eggs were spherical in shape and floated separately. Their membrane and yolk having 1 oil globule were transparent. The transparent eggs, having one oil drop in the yolk, were $0.94{\sim}1.02\;mm$ (mean, $0.95{\pm}0.03\;mm$) in diameter. The fertilized eggs started hatching at 51 hrs after fertilization in $20{\pm}0.5^{\circ}C$ water. The total length of the hatched larvae was $2.52{\sim}3.0\;mm$ (mean, $2.75{\pm}0.04\;mm$). At hatching, the larva, with the mouth and anus not opened yet, had yolk sack, $28{\sim}31$ myomeres and eyes with melanophore. Yolk completely 2 days after hatching and the total length of post-larvae $3.12{\sim}3.63\;mm$ (mean, $3.39{\pm}0.05\;mm$). At the 18 days after hatching, the tip of tail became curved at the end and the stems for pectoral, dorsal, and caudal fins appeared. Juveniles, having all firm rays, was $44.12{\sim}58.72\;mm$ (mean $55.95{\pm}6.74\;mm$) in TL 25 days after hatching.