• The Korean Journal of Malacology
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• v.21 no.1
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• pp.65-70
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• 2005

The purpose of this study is to determine the appropriate substrate for larval settlement and spat growth in the purple clam, Saxidomus purpuratus in laboratory culture. Larvae were reared with 3 different types of sediments (mud, sand, and mixed) for 46 days in settlement experiment, and settled spats were further grown in 3 types of sediments for 36 weeks in growth experiment. The density of settled spats in muddy sediments was more than 2 times higher than those in mixed or sandy sediments. But, the average size of settled spats in muddy sediments was smaller than those in mixed or sandy sediments. After 36 weeks of growth period, growth rate decreased as shell length increased. When shell length was less than 2 mm, growth rate in mixed sediments was significantly higher than that in sandy sediments. When shell length was more than 2 mm, there was no significant difference in growth rate among different substrates. Sediment type affected growth rate only when the spats were relatively small (less than 2 mm). Muddy sediments seems better for larval settlement, while mixed sediments is best for spat growth. We suggest the laboratory procedure for enhancing seedling production of S. purpuratus.

• Korean Journal of Environmental Biology
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• v.39 no.4
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• pp.536-541
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• 2021

Pantala flavescens is a dominant Odonata species in the rice fields in Korea. To determine the effects of different temperatures on its larval growth and emergence, field and laboratory experiments were conducted. Larval growth was also monitored in mono-cropping and double-cropping rice fields. The growth of larvae was monitored every week by measuring the head width. In the field experiment, no difference was found in larval growth and emergence between the control temperature and +1.9℃ of the control temperature. The larval growth was greater at 23℃ than at 20℃ laboratory temperatures, and no emergence was recorded at either temperature after eight weeks of monitoring. There was a quadratic relationship between larval growth and temperature in an incubator at five temperature regimes of 15, 20, 25, 30, and 35℃. Midseason water drainage caused the extinction of the existing individuals and newly hatched larvae dominated after re-watering in the rice fields. Larval size was greater in double-cropping fields than in mono-cropping fields in late July but the tendency was reversed in early August. The results of this study suggest that temperature warming will directly promote the larval growth of P. flavescens and indirectly influence seasonal growth via changes in water management in rice fields.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.45 no.4
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• pp.251-259
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• 2009

Swimming crabs, Portunus trituberculatus(Miers) are commercially important off the coasts of Korea, Japan and China. Harvest of swimming crabs has been fluctuated along their distribution ranges. Fluctuations in the interannual harvest of swimming crabs may be correlated with the survival rate during the larval period. The survival rates, intermolt periods, and growth of larval swimming crabs were investigated in the laboratory. Larval swimming crabs are released and undergo development from April to August off the western coast of Korea in the Yellow Sea. Sea surface temperatures off the western coast of Korea during the larval season were used for the laboratory experiments, and ranged from 22 to 26${^{\circ}C}$. Larvae were individually cultured at four different temperatures, 22${^{\circ}C}$, 24${^{\circ}C}$, 26${^{\circ}C}$, and 28${^{\circ}C}$. Zoea molted to megalopa at all temperatures and developed to the first crab stage at 24${^{\circ}C}$, 26${^{\circ}C}$, and 28${^{\circ}C}$. Survival rates from zoea I to the first crab stage increased with increasing temperatures. Intermolt period and the growth rate of the mean carapace length were inversely correlated with temperature. Our research helps understand the changes in survival rate and growth of larval swimming crabs resulting from changing oceanic temperatures. Further, our study suggests that the fluctuations in fishery harvest of swimming crabs off the coast of Korea may be related to changes in larval survival affected by changing ocean conditions.

• Journal of Aquaculture
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• v.20 no.3
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• pp.194-198
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• 2007

Reproductive traits of Palaemon gravieri such as embryo size, number of embryo (fecundity), incubation period, larval development mode, larval development period, larval survival and larval growth were described and compared to analyze the correlation among those traits. Embryo volume is a primary factor determining other ensuing reproductive features. Egg volume was $0.042mm^3$ in the first developmental stage. Embryo volume in P. gravieri was comparatively small which is indicative of great number of embryo (y = 3.0161x + 0.0185 $R^2$ = 0.74 positive isometric relationship) and relatively long incubation period. Larvae survived from zoea 1 to post-larvae and it took 45 days at $22^{\circ}C$. Survival rate of the larvae was rather great in the early stage and thereafter steadily decreased. Daily growth rate of larvae in P. gravieri at $22^{\circ}C$ was 0.0195 mm on average. They grew steadily as time went by. Incubation period was between 10-14 days at $22^{\circ}C$. Larval development mode was almost complete planktotrophic. PNR (point of no return) appeared to be the third day on average. Survival rate of larvae without feeding declined rapidly between 3 and 4 days. Larval development period and stage frequency were 23-30 days and 11 stages which imply prolonged larval period and high mortality. The pattern of brood production followed fast successive parturial pattern. Most ovigerous female had mature ovary when they performed parturial molt soon after hatching (larval release).

• Development and Reproduction
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• v.16 no.2
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• pp.107-112
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• 2012

Early growth, the rate of yolk sac absorption, and nucleus size in liver parenchymal cells were correlated with the nutritional status of first feeding larval haddock, Melanogrammus aeglefinus. Larvae that successfully began exogenous feeding maintained high growth rates, delayed yolk sac resorption, and had larger hepatocyte nuclear sizes than starved larvae. At 10 days post hatch (DPH) the cumulative mortality in the starved larval haddock group was 100%. The area of the hepatocyte nuclei in starved larvae gradually decreased, reaching its lowest value by 9 DPH. Our results support the current practice of providing the first food supply at 3 DPH. Hepatocyte nuclear size can be used to assess larval haddock nutrition status, and may be a good criterion for assessing the success of transition from endogenous to exogenous feeding.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.4
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• pp.378-383
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• 2001

Larvae of Metapenaeopsis dalei (Rathbun) were successfully spawned and reared in the laboratory under controlled conditions. The experiments were designed to examine effects of salinity (20, 25, 30 and 35), temperature (21, 24 and $27^{\circ}C$ ) and food (five items) on larval development, survival and growth, Salinity affected larval survival, from $\%$ at 20, to $60\%$ at 35 (protozoea 1 to first postlarva), The highest survival rate was obtained at $35\%_{\circ}$. Temperature affected larval survival, from $46\%$ at $27^{\circ}C$ to $54\%$ at $21^{\circ}C$(protozoea 1 to first postlarva). The highest survival rate was obtained at $24^{\circ}C$. Mortality was the highest from protozoea 1 to protozoea 3, but decreased considerably for all temperatures once the mysis stage was reached. Larval growth was affected by different of food items. Phytoplankton (Isochrysis galbana) was the optimum food for the larval survival and the growth from protozoea 3 to first postlarva.

• Korean Journal of Environmental Biology
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• v.23 no.2 s.58
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• pp.114-119
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• 2005

Larval survivorships, growth rates, developmental rates, and emergence rates of Cloeon dipterum were studied under four constant temperatures $(10^{\circ}C,\; 15^{\circ}C,\;20^{\circ}C,\;and\;25^{\circ}C)$ in the laboratory. Larval mortalities were relatively higher during the initial one-week period, but those tend to be stabilized as the experiments proceed. Judging from the growth and develop-mental rates, estimated optimal temperature for larval growth and development lies between $20^{\circ}C\;and\;25^{\circ}C$. Estimated larval period for emergence is less than 100 days.

• Fisheries and Aquatic Sciences
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• v.8 no.2
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• pp.90-96
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• 2005

The larvae of Palaemon gravieri were reared in the laboratory at three different temperature regimes ($15^{\circ}C,\;20^{\circ}C,\;and\;25^{\circ}C$) with the salinity ranges (28-32 psu) to understand how temperature and body size influence survival rate, and growth components (molt increment and intermolt period). The optimum temperature for the highest survival rate was $25^{\circ}C$. The intermolt periods consistently increased with an increase in size and instar number; however, the molt increments at successive instars generally decreased with an increase in size and instar number. The shortest intermolt period and the highest larval growth rate both occurred at $25^{\circ}C$. Thus, the optimum temperature for larval survival and growth rate was found to be $25^{\circ}C$ which was the temperature at which the larvae actually appear in nature.

• Korean Journal of Environment and Ecology
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• v.25 no.5
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• pp.666-672
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• 2011

This study examined the different growth rate of larval salamander Hynobius leechii by the predation risk. We collected salamander's eggs from Mountain Inwang. Eggs were treated by two different conditions: (1) cue - which had a predation risk three times a day; (2) no cue - which had no predation risk. Predation risk was conducted by using chemical cue from Chinese minnows. The chemical cue treatment started from the next day after the collection and ended one week after the hatching. Between the first week and the second week after the hatching we fed salamander larvae with tubifex ad. libitium. After the treatment phase, we measured snout - vent length of the each larva on the first week and the second week after the hatching. The results showed that there was a significant difference in the growth rate by the predation risk. From these results we found that predation risk can cause the different growth rate to the larval salamander and these changes could be affect their mortality.

• Korean Journal of Environmental Biology
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• v.22 no.3
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• pp.369-375
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• 2004

This experiment was studied to obtain basic environmental effects and biological information on the early growth of larval mitten crab (Eriocheir sinensis). Mitten crabs were maintained for each larval stage with solutions containing 0.1, 0.2, and 0.3 ppm of cadmium (Cd) and mercury (Hg). The relationship between survival rate of mitten crabs and metal content in the growth chamber showed a positive correlations. However, it showed a significant difference in the 96 $hr- LC^{50}$ values of Cd and Hg for the E. sinensis larvae from the first zoea larva to juvenile. Hg was more toxic to E. sinensis larval than Cd. When Cd and Hg are released into the water, they enter E. sinensis larval and are biological magnified. These results of survival rate and bioaccumulation are very important when considering the survival of the mitten crab.