• Bulletin of the Korean Chemical Society
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• v.29 no.6
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• pp.1179-1184
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• 2008

Commercial nanometer sized silver is widely used for its antibacterial effect; however, nanoparticles may also have ecotoxicological effects after being discharged into water. Nanometer sized silver can flow into aquatic environments, where it can exert a variety of physiologically effects in living organisms, including fish. The present study aimed to investigate the effect of nanometer sized silver on the development of zebrafish embryos, analyze the properties of commercial nanometer sized silver and define the toxicity relationship between embryogenesis and hatched flies. The commercial nanometer sized silver was analyzed in the $Ag^+$ ion form. The hatch rate decreased in the nano-silver exposed groups (10 and 20 ppt); furthermore, the hatched flies had an abnormal notochord, weak heart beat, damaged eyes and curved tail. The expression of the Sel N1 gene decreased in the nano-silver exposed groups, and the catalase activities of the exposed groups increased relative to those in the control group. Therefore, the $Ag^+$ ions in commercial nanometer sized silver could accumulate in aquatic environments and seriously damage the development of zebrafish embryos.

• The Korean Journal of Soil Zoology
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• v.5 no.2
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• pp.119-123
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• 2000

Effect of fluctuating temperatures on the development of the immature beet armyworm, Spodoptera exigua (H bner), was analyzed. At constant rearing temperature regimes, the estimated developmental threshold temperatures were varied among stages and instars, but had an average 13$^{\circ}C$ from egg hatch to adult emergence. Based on the 13$^{\circ}C$ threshold temperature, we set up three different rearing temperature regimes having the same day-degrees. Two fluctuating temperature regimes changed significantly the developmenta1 period expected by the constant rearing temperature regime. Under the same thermophase temperature (25$^{\circ}C$), the thermocycling regime with the higher cryophase temperature (10$^{\circ}C$) decelerated the developmental rate probably by lowering temperature limit thor development, but that with the lower cryophase temperature (5$^{\circ}C$) gave a negative developmental effect.

• Journal of Aquaculture
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• v.20 no.4
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• pp.265-269
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• 2007

We studied the effects of temperature on the egg development and larvae of Takifugu pardalis. The larvae hatched 135-480 hr after fertilization in $13^{\circ}C-24^{\circ}C$ and 32 ppt. The higher the temperature the earlier the larvae hatch within $13^{\circ}C-24^{\circ}C$. The maximum hatching rate was made in $15^{\circ}C$ and 32 ppt. The higher the temperature the larger the newly hatched larvae. The larvae hatched in $24^{\circ}C$ were ca. 3.35 mm in total length. Occurrence of the deformed larvae was lower in $13^{\circ}C-18^{\circ}C$ regime and higher over $21^{\circ}C$ regime.

• Development and Reproduction
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• v.19 no.4
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• pp.189-196
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• 2015

This study was examined the ovogenesis of Ussurian bullhead, Leiocassis ussuriensis and the morphological development of its larvae and juveniles and to use the results as basic information for the preservation of species and resource enhancement. For artificial egg collection, human chorionic gonadotropin (HCG) was injected at a rate of 10 IU per gram of fish weight. During breeding period, water temperature maintained at $24.5{\sim}26.5^{\circ}C$ (mean $25.0{\pm}0.05^{\circ}C$). The process of ovogenesis reached the two-cell stage in 50 minutes after fertilization. In 73 hours of fertilization the movement of the embryoid body became active state and the larvae began to hatch from the tail through the oolemma. Length of prelarvae were 6.33~6.50 mm long (mean $6.40{\pm}0.06mm$) just after hatching having yolk with their mouth not opened. After thirty eight days of hatching, juveniles were 30.6~32.5 mm long (mean $31.5{\pm}0.65mm$). The color was dark yellowish brown throughout the entire body, and the number of caudal fin rays developed to thirty six perfectly.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.3
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• pp.274-282
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• 2019

Female Siberian sturgeon Acipenser baerii were crossed with male Russian sturgeon A. gueldenstaedtii and the development, ontogenetic behavior, and phototactic characteristics of the resultant hybrid prolarvae were examined. The fertilization rate of the hybrid group was similar to that of Siberian sturgeon (the maternal species), and the overall developmental characteristics of hybrid embryos were not significantly different from those of either parental species. The time window from first hatch to the completion of hatching was wider in Russian sturgeon than in Siberian and hybrid sturgeon groups. The prolarval viability of the hybrid group was similar to that of the maternal species, and significantly higher than that of the paternal species. Hybrid prolarvae displayed ontogenetic behavioral patterns that were quite similar to those of Siberian sturgeon. In an illumination preference test, hybrid prolarvae displayed significant positive phototaxis, similar to the maternal species, and clearly distinct from the negative phototactic character of the paternal species. Taken together, our data indicate that the prolarval traits of hybrid sturgeon from this cross more closely resemble those of the maternal than the paternal species.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.29 no.1
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• pp.1-8
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• 1996

The effects of temperature and salinity on hatching rate of fertilized egg were examined to develop the method for the efficient seed production in fleshy shrimp, Penaeus chinensis. At the temperature ranging from $20^{\circ}C\;to\;24^{\circ}C$, the hatching rate increased with temperature and the highest hatching rate $(95.5\%)$ occurred at $24^{\circ}C$. But, with the temperature above $26^{\circ}C$, the hatching rate decreased suddenly, and at $30^{\circ}C$, the egg did not hatch at all. The hatching rate increased with salinity within the range of $20\%_{\circ}\;to\;31\%_{\circ}$ and the highest hatching rate $(95.5\%)$ occurred at $31\%_{\circ}$. However, with the salinity above $31\%_{\circ}$, the rate decreased abruptly, and it was only $25.5\%\;at\;40\%_{\circ}$. The hatching speed of egg was the fastest at $24^{\circ}C$. The hatching rate at $24^{\circ}C$ with the salinity of $31\%_{\circ}\;was\;30.5\%$ within 18hrs of the hatching experiment and it attained to $95.5\%$ within 48hrs of the hatching experiment. At $24^{\circ}C$, the hatching rate with the salinity of $30\~31\%_{\circ}$ is 1,2 times higher than that of egg with the salinity of $33\~35\%_{\circ}$.

• Korean journal of applied entomology
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• v.53 no.3
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• pp.311-315
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• 2014

Lantern fly(Lycorma delicatula) is a major invasive pest that causes withering symptom of agricultural crops by sucking tree sap and sooty mold symptom by producing honeydew. This study was conducted to investigate the occurrence pattern of lantern fly in grape orchards in Gyeonggi area and the effect of winter temperature on L. delicatula egg survival during 2010 to 2013. In Gyeonggi areas, overwintered L. delicatula eggs began to hatch from early May and nymphs peaked in mid May. Adults emerged from late July and laid eggs until early November. The survival of L. delicatula eggs during overwintering was largely affected by winter temperatures. The relationship between the number of days below a threshold temperature (x) in January and the survival rate of overwintering L. delicatula eggs (y) was using linear regression model. The best model selected by the lowest RSS (residual sum of square) between predicted and actual survival was y = -1.0486 x + 94.496 ($R^2=0.7067$) with $-11^{\circ}C$ of threshold temperature. These results should be helpful to conduct L. delicatula management programs, since the results provided relivable prediction for the winter survival of L. delicatula eggs and the phenology of egg hatch in the spring.

• International Journal of Industrial Entomology and Biomaterials
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• v.8 no.1
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• pp.73-76
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• 2004

The rate of oxygen consumption of the silkworm eggs was measured to set up the barometer for measuring the effect of egg chilling on diapause termination. In diapause eggs, $O_2$ uptake showed a maximum of 79.2 ${mu}ell$/mg eggs/hr, at one day after oviposition and then gradually decreased to 2.2${mu}ell$/mg eggs/hr at 9days. The rates of oxygen uptake of eggs raised immediately after HCl-treatment and reached to a maximal level of 484.5 ${mu}ell$/mg eggs/hr in 9-day-old eggs, which corresponds to 220 fold that of diapause eggs, and the hatching ability was also over 50％. In order to break diapause, eggs incubated at $25^{\circ}C$ for 30 days after oviposition had to be kept at least for 45 days at 5$^{\circ}C$, but chilled eggs for 90 days or longer hatched at 10 days as normal hatching periods. We also investigate periods which the value of $O_2$ uptake of eggs chilled during 15 to 120 days at 5$^{\circ}C$ reached at 200 ${mu}ell$/mg eggs/hr. As a result of that, $O_2$ uptake of eggs chilled during 15 to 45days were not reached at 200 ${mu}ell$/mg eggs/hr and longer the chilling durations are, the higher the rate of $O_2$ uptake is and the longer the chilling durations are, the shorter the periods up to hatching is. And also, hatch-ability increased rapidly as $O_2$ uptake reaches over 20/eggs/hr.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.4
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• pp.530-537
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• 2020

This study compared the survival rates, growth, and fatty acid content of larval Pacific cod Gadus macrocephalus fed with rotifers raised on different enrichment diets. We used four commercial rotifer enrichment products (one domestic, ER1, and three imported, ER2, ER3 and ER4). Twelve 200-L tanks were used, with three replicates per treatment. Larvae were fed rotifers 3 times daily at a rate of 5 rotifers/ml/feeding from 7 to 21 days post-hatch. At the end of the feeding trial, the survival rate and total length of larvae fed ER3 were greater than those of larvae fed ER1, ER2, or ER4. ER3 had the highest proportions of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and polyunsaturated acid (PUFA). Partially reflecting this composition, larvae fed ER3 had the highest proportions of DHA and PUFA. These results show a positive effect of rotifer DHA and PUFA proportions on the survival and growth rates of Pacific cod larvae.

• Environmental Analysis Health and Toxicology
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• v.24 no.2
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• pp.119-125
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• 2009

This study was carried out to investigate the toxic effect of WSF (water soluble fraction) in crude oil on the hatch, survival rate, abnormality and physiological activity of fertilized eggs and early larvae in Paralicthys olivaceus. The time required in hatching the fertilized eggs exposure to crude oil was 50.8${\sim}$53.2 hours both in control group and experimental group, showing no significant difference(p>0.05). The hatching rate in the control group was more than 80% in 1.9 ${\mu}g/mL$ WSF concentration, but hatching rate was less than 55.7% in below of 3.9 ${\mu}g/mL$ WSF concentration, showing significant difference (p<0.05). The survival rate on the 3rd day of early larval stage was 61.96% with 1.9 ${\mu}g/mL$ WSF, 11.1% with 3.9 ${\mu}g/mL$ WSF, and they all died with other concentration levels. The oxygen consumption rate in experimental groups was lower than control group. The heart rate (no./min) was 47.4${\sim}$52.8 before hatching and there was no significant difference between control group and experimental group, but heart rate reduced with the decrease of WSF concentration after hatching. The abnormality was 1.1% in the control group whereas 36.7% with 3.9${\mu}g/mL$ WSF, and abnormality was mostly comprised of incomplete spinal formation and spinal curvature. The results of this study suggest that even low concentration to WSF affects the early development of the flounder, Paralicthys olivaceus.