• Development and Reproduction
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• v.1 no.2
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• pp.173-180
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• 1997

This study has been conducted to investigate the molting behavior and the effects of rearing temperature and day length on molting in the behavior and the effects of rearing temperature and day length on molting in the giant freshwater prawn, Macrobrachium rosenbergii reared in the laboratory. The results obtained were summarized as follow: 1. After pre-spawning molting, the protopodites of 1st, 2nd, 3rd, and 4th except 5th pleopod bore new breeding setae which conserve eggs in the brooding chamber and the basis of 3rd, 4th, and 5th pereiopods bore new breeding dresses which transport the ovulated eggs into the brooding chamber. 2. Adult females reared in 27.5-$29.4^{\circ}C$ molted 10-12 times per year at interval of 27-35 days, of which four or six moltings were common molting for growth and another four or five moltings were pre-spawning molting for spwaning and brooding. In winter season, pre-spawning molting did not happen to most of adult females in spite of the same temperature. 3. Duration of intermolt cycle was 31-38 days and 26-30 days at 25.3- $26.5^{\circ}C$ and 28.7- $30.4^{\circ}C$ of rearing temperature, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.4
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• pp.380-386
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• 2009

Molting and growth of the snow crab, Chionoecetes opilio was investigated using samples captured in the East Sea from July 2002 to June 2004. Individuals over 40 mm carapace width (CW) molted once a year from July to October. Annual molt stage of C. opilio can be divided into four stages; premolt stage, molting stage, postmolt stage and intennolt stage. The relationship between CW and chela height (CH) can be expressed as Y=-82lnCW+73.1129lnCH+166. They were separated into two groups based on the equation, that is, one group having a negative value (below 70 mm in CW) and other group having a positive value (over 130 mm in CW). Carapace width at 50% terminal molt ($CW_{50%}$) of males was estimated to be 105 mm. The Gompertz growth equation estimated from a non-linear method was $CW=118.99e^{-6.296e^{-0.3062t}}$ for females and $CW=156368e^{-6.6619e^{-0.2626t}}$ for males.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.6
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• pp.801-806
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• 2013

Spiny lebbeid shrimp Lebbeus groenlandicus larvae were reared in the laboratory to estimate the energy budget from the zoeal to the post-larval stage. Energy expended by larvae on growth and respiration was determined from values for feeding, growth, molting, and metabolism. We calculated that 16.22 J were used for growth throughout all larval stages. Energy loss during molting was estimated as 1.03 J, and energy used for respiration was estimated as 1.31 J. Energy taken in by feeding was estimated as 77.16 J, while the sum of energies expended in excretion and egestion was 58.61 J. Larvae were estimated to assimilate 24.6% of ingested food as energy and to use ~85% of the assimilated energy for somatic growth. Gross growth efficiency ($K_1$) and net growth efficiency ($K_2$) were shown to be ~22% and 93%, respectively. Maintenance costs of respiration were estimated as ~9.7% of assimilated energy.

• Fisheries and Aquatic Sciences
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• v.17 no.1
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• pp.115-121
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• 2014

Eyestalk ablation (ESA) is commonly used in aquaculture to stimulate ovarian maturation in crustaceans, and methyl farnesoate (MF) affects crustacean molting and reproduction. To investigate the physiological effects of ESA and MF treatments on the shrimp Litopenaeus vannamei, we compared the effects of single eyestalk removal and MF injections. The ESA group had the lowest survival rate (50%), and individuals in the $0.1{\mu}g$ and $1.0{\mu}g$ MF-treated groups had survival rates of 80 and 73.3%, respectively. Conversely, molting numbers were highest in the ESA group, and similar to those of the 1.0-${\mu}g$ MF group. To investigate shrimp growth, we measured body weight during the experimental period and found that individuals in the ESA and $1.0{\mu}g$ MF groups showed significant increases in body weight. Furthermore, to investigate the effects of ESA and MF treatments on gonadal maturation, the gonad somatic index (GSI) was calculated after the experiment. All treated groups (ESA and MF) had higher GSI values than the control group, but the ESA and $1.0{\mu}g$ MF groups were not significantly different. Using histological ovary analysis, we determined that all treated groups showed indications of the previtellogenic stage, unlike the control group (immature stage). These results suggest that the high-MF-concentration treatment produced effects similar to those of ESA with respect to molting number, growth, and ovarian maturation.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.6
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• pp.807-812
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• 2013

The energy budget of the larvae of pandalid shrimp, Pandalopsis japonica, reared in the laboratory from zoea to post-larva was investigated. Energy used during the growth of the shrimp larvae was calculated daily for feeding, growth, molting, and metabolism. The total energy used was 16.2 J for the entire larval stage. Molting energy loss was estimated at a total 1.03 J. Energy used for respiration was estimated at a total of 1.85 J. The intake energy by feeding reached a total of 77.69 J. The total sum of energies used by excretion and egestion was 58.61 J. Larvae assimilated 24.57% of ingested food and used 84.91% for somatic growth. The gross growth efficiency ($K_1$) was 22.19% for the entire larval stage, and the net growth efficiency ($K_2$) was 90.31%. Maintenance costs were estimated at 9.69% of assimilated energy for the entire larval stage.

• Fisheries and Aquatic Sciences
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• v.2 no.1
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• pp.78-84
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• 1999

Ultrastructural changes in the cuticle of Paleamon serrifer associated with the intermolt cycle were examined and quantified as changes in the cuticular thickness. The cuticular thickness in each zoea stage increased with time elapsed after molting. The cuticle in the premolt stage was about 1.5 and 3 times thicker than that in the postmolt and intermolt stage, respectively. The cuticle in the premolt stage, including the molting space, was more than 5 times as thick as in the postmolt stage. In addition, newly hatched larvae were individually reared in the laboratory and body length for each specimen was measured frequently until the end of zoea VI. An average increase in body length between one zoea stage and the next is about $10\%$ of the length of the previous stage. Within individual zoea stages, the premolt stage had a body length some 0.3% longer than that of the postmolt stage, indicating a growth rate of about 0.03 mm/d.

• Journal of Aquaculture
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• v.10 no.3
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• pp.289-300
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• 1997

Energy budget of mysid shrimp, Neomysis intermedia in Lake Kyongpo was determined at constant temperature (2$0^{\circ}C$). Energy used by reared mysids were calculated from data on feeding, growth, molting, reproduction, and metabolism. The Energy used by growth of juvenile and adult were 6.87 cal in females of 8.55mm in length, and 5.67 cal in males of 7.53mm in length, respectively. Molting losses were estimated to be 0.46 cal in females and 0.38 cal in males from juvenile to adult. Energy used in respiration were estimated to be 48.48 cal in females and 36.45 cal in males from juvenile to adult. The energy intakes from feeding were 84.15 cal in females and 67.09 cal in males from juvenile to adult. Energy losses by excretion were 10.36 cal in females and 6.46 cal in males. Thus, females assimilated 86.65% and males 81.99% of assimilated energy in somatic growth. The gross growth efficiencies (k1) showed 8.71% for females and 9.02% for males and the net growth efficiencies (k2) showed 10.05% for females and 12.36% for males. Maintenance costs were estimated at 66.48% of assimilated energy in females and 66.26% in males. Molting losses among the energy assimilated from juvenile to adult were estimated to be 0.63% in males and 0.69% in females.

• Korean Journal of Ecology and Environment
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• v.37 no.1 s.106
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• pp.96-101
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• 2004

The effects of the ecdysteroid agonist tebufenozide on the larvae of Chironomus flaviplumus and Chironomus riparius were tested in the laboratory. Employing a static exposure setup, chironomids were subjected to various tebufenozide concentrations. In the most treatments it reach-ed a statistically significant difference from the control condition. As the concentration of tebufenozide was increased, a relatively larger proportion of the observed mortality was associated with the metamorphosis and molting process. The larval mortality of C. riparius was high in C. flaviplumus during over 30 ${\mu}g\;L^{-1}$ treatments. In terms of development, the effects of tebufenozide were delayed growth stage in relatively lower concentration such as 10 ${\mu}g\;L^{-1}$ tebufenozide treatments. The rates of succeed adult through the molting process were various in treated concentrations or/and the species.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.10a
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• pp.317-318
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• 2001

In crustacea the molting cycle is the most important physiological process affecting growth, behaviour, reproduction and population dynamics through their life span. Particularly molt cycle is closely related to reproductive cycle, and it is important to determine the successive stages of molt cycle to understand reproductive phenomena including ovarian cycle and the development of the embryos in the marsupium. (omitted)

• Korean Journal of Environmental Biology
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• v.21 no.3
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• pp.286-291
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• 2003

We investigated the effects of molting-hormone insecticide tebufenozide on D7 (the day of hatching from egg) larvae of the midge Chironomus riparius in growth developments. D7 instar larvae were exposed test concentrations were chosen control, 10${\mu}g \;L^{-1}$, 30${\mu}g \;L^{-1}$, 60${\mu}g \;L^{-1}$ and 100${\mu}g \;L^{-1}$ of tebufenozide. In general, dead larvae showed 16% on the next day after insecticide treatments (D12), and observed 44% from D12 to D16 in this exposed days. Dead larvae of C. riparius was abruptly increased on D12 and also continuously increased along the days in 10${\mu}g \;L^{-1}$ treatments. The converged day was from D12 to D16 at move 30${\mu}g \;L^{-1}$ treatments in this study. Therefore, dead larvae obviously increased along these concentrations of tebufenozide. In control condition,78% of the test individuals have grown the pupae. But the larvae have developed the pupa stage from 5% to 17% of the test organism in 10${\mu}g \;L^{-1}$ and 30${\mu}g \;L^{-1}$ treatments. And 75% of the test individuals was arrived the adult through the molting process in control condition. While the other condition was rarely observed the adult. Usually, the emerged period of the test individuals was gathered the D26-D29 in control. The dead pupa showed from D19 to D20 in 30${\mu}g \;L^{-1}$ treatments, D32 in control and D33 in 10${\mu}g \;L^{-1}$ treatments. The observed periods of dead pupa were D32-D34 in control and D33-D37 in 10${\mu}g \;L^{-1}$ treatments. Consequently, due to molting hormone disruption, development of midge was postponed relatively low concentration such as 10 treatments of tebufenozide.