• Journal of the Korean Society of Environmental Restoration Technology
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• v.27 no.3
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• pp.19-28
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• 2024

The purpose of this study is to investigate the habitat of Luciola unmunsana to understand the status of land snails, which are the larvae prey, and to evaluate the effects of larval feeding preferences and prey size for the restoration of the L. unmunsana habitat as a basis for future restoration projects. The research methods included field surveys of the habitat and laboratory experiments on feeding preferences using three types of land snails (Allopeas clavulinum kyotoense, Euphaedusa fusaniana, Pupinella rufa) observed in the habitat. Field surveys of 13 L. unmunsana habitat sites revealed a total of 24 land snail species. The experimental results regarding the larvae prey were analyzed for statistical significance of feeding preferences using Chi-square tests and independent sample t-tests. Consequently, larvae showed the highest preference for A. c. kyotoense, with statistically significant differences in feeding preferences (p<0.05). Also, statistically significant differences were observed in the size between the land snails that were eaten as prey and those that were not eaten. This research can deepen the understanding of the feeding preferences of L. unmunsana larvae and provide practical guidelines for the effective conservation and restoration strategies of the firefly habitat.

• Journal of Ecology and Environment
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• v.48 no.3
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• pp.214-221
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• 2024

Background: To identify and avoid predators, amphibians rely on chemical cues. Onychodactylus koreanus undergo two to three years of the larval stage in mountainous streams, where they encounter various predators. We aimed to identify the potential predators of O. koreanus larvae based on their antipredator responses to predator odors. Additionally, we examined whether the response was innate or can be strengthened by predator olfactory learning. Results: In Experiment 1, O. koreanus larvae exhibited a substantial antipredator response to Chinese minnow (Rhynchocypris oxycephalus) odor but not to Korean freshwater crayfish (Cambaroides similis) odor. In Experiment 2, O. koreanus larvae, who did not previously expose to R. oxycephalus odor, demonstrated a substantial antipredator response to it. Experiment 3 indicated that predator olfactory learning of R. oxycephalus did not enhance the antipredator response of the larvae. Conclusions: Rhynchocypris oxycephalus could prey on O. koreanus larvae, whose antipredator response to R. oxycephalus odor is innate and not enhanced by olfactory learning. Further investigation into the olfactory system of this species may provide insights into the life cycle of O. koreanus, uncovering hidden underground breeding sites and unknown breeding periods.

• Korean Journal of Ichthyology
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• v.2 no.2
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• pp.138-148
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• 1990

The influence of starvation on morphological change of the red sea bream larvae was examined at Song-ji fish hatchery, Tongyong-Gun, Kyongnam Provice in July 1988. The results obtained are as follows: 1) The larvae of red sea bream began to feed on rotifers in 2 days after hatching. In case of non-feeding, all of the larvae died in 5 days after hatching and the larvae which feeding delayed 1 and 2 days from normal first feeding schedule also died 100 in 6 days after hatching. 2) With the exhaustion of the yolk, the total length, body length, myotome height and gut height of unfed larvae decreased. 3) The ratio of height to myotome height in unfed larvae has declined most rapidly compare to other demensions while starving. At 5 days after hatching, the ratios of these of starving larvae and fed larvae were 0.306 and 0.010, respectively. 4) The morphology of starving larvae at 6 days after hatching are characterized as sharpened jaw, projected edge of lower part of clavicle and slender gut.

• Korean Journal of Ichthyology
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• v.9 no.1
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• pp.15-21
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• 1997

The influence of delayed(1, 2, 3, 4 days) feeding and starvation on morphological change and survival rate of the spotted sea bass larvae was examined at the KORDI laboratories which located at Poryong Power Plant, Poryong-gun, Chungchongnam-do in November, 1996. 1. The larvae of spotted sea bass began to feed on rotifers at 5 days after hatching. In case of non-feeding, all of the larvae died at 9 days after hatching. The larvae which fed 1 day after the normal first feeding schedule(1 day delayed) grew normally and 2 days delayed groups showed 5.3% in survival rate at 9 days after hatching. In case of non-feeding and 3 or 4 days delayed groups, all of the larvae died between 9 and 10 days after hatching. 2. In case of non-feeding, total length of the larvae decreased gradually. 3. The percente ratio of gut height and mytome height to standard length in starved larvae has declined most rapidly compare to other demensions during the non-feeding period. The percente ratio of gut height to mytome height had also difference between unfed and fed larvae. At 9 days after hatching, the ratio of that between fed and unfed larvae were 84.5 % and 52.4 %, respectively. 4. The morphology of starving larvae were characterized as sharpened jaw, projected edge of lower part of clavicle and bending trunk with slenger gut.

• Journal of Aquaculture
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• v.10 no.4
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• pp.473-483
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• 1997

Yolk resorotion and commencement of external feeding in larvae of red spotted grouper, Epinepheus akaara were studied to understand the high mortality of larvae. Consumption of yolk was higher than that of oil globule for the first 24hs after hatching. The resorption rates of yolk and oil globule increased with the increase of temperature. The time yolk was comsumed up to 99% was 84hs after hatching in 23~$25^{\circ}C$,72hs at ~$27^{\circ}C$, and 60hs in 29~~$31^{\circ}C$, while the time for oil globule was 96hs in 23~$25^{\circ}C$, 84hs at $27^{\circ}C$, and 60hs in 29~$31^{\circ}C$. The relationship between mouth openning time (Y) and water temperature (X) was repersented as a linear regression, Y=-2.53X+118.4, (r2=0.89). In 72~96hs after hatching, upper jaw sizes of the larvae reached around 0.114 mm. By the time the larvae comsumed most of the yolk and oil globule, and started external feeding. The relationship between upper jaw length (Y) and total length (X) was represented as a linear regression, Y=0.139X-0.165, (r2=0.88). Rotifer was not found in the guts of larvae before 72hs after hatching at $28^{\circ}C$, when larvae resorbed their yolk and oil globule over 99%. But, at 96hs after hatching, about 33% of the larvae had the rotifer in their guts. Delayed feeding experiments revealed that the earlier food supply within 84hs after hatching showed the better survival rates for the larvae. The larvae fed at 96hs after hatching died all within 120hs.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.2
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• pp.220-228
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• 2019

To determine the horizontal and temporal distribution of common squid larvae, Todarodes pacificus (hereafter T. pacificus), we conducted surveys using an IKMT net (mesh size: $500{\mu}m$) with a Fisheries Research Vessel (FRV, TAMGU 21) in the southwestern part of the East Sea in summer (August and September) and autumn (November) 2015. A total of 228 larvae, ranging in mantle length (ML) from 1.4 mm to 21.9 mm, were collected at 35 stations over the research period. The monthly average mantle length of T. pacificus larvae did not differ significantly in August, September and November. (p > 0.05). Catch densities at positive stations ranged between 0.1 and $7.9inds./1,000m^3$ over the research period. Incidence rates of T. pacificus larvae were similar over three months, in the study area (62.9 % - 68.6 %). The 4 - 5 mm mantle length range had the highest frequency in size-frequency distributions for T. pacificus larvae. The larval survival temperature ($15-24^{\circ}C$) at positive stations for catch densities was located below a 20 m depth in August whereas it was located at the surface of the water in September and November. The survival temperature for larvae existed from the bottom to the surface of the water where larvae were sampled larvae in shallow sea areas. However, the larval survival temperature occurred in a shallower location than the upper layer of the thermocline in deep sea areas at a depth below 100 m.

• International Journal of Industrial Entomology and Biomaterials
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• v.8 no.1
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• pp.81-87
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• 2004

In order to investigate the effects of supplementary nutrients on silkworms, Bombyx mori, an experiment was conducted with ascorbic acid treatments. Dietary supplements of ascorbic acid 1, 2 and 3% were fed to silkworm larvae through 1st to 5th instar, The larvae were fed by mulberry loaves of Kokoso variety and the supplementary loaves were used once a day. These treatments resulted in a significant increase of biological parameters such as larval weight, the rate of food consumption and the approximate digestibility of the food. But the economical parameters such as cocoon weight and cocoon shell weight didnt show considerable difference compared to control. Dietary supplement of 2% ascorbic acid increased the larval weight by 7.8% and reached to 1.065g, which had the highest weight increase in the fourth day of 4th instar larvae. The percentage of daily weight increase in this group of larvae (79.01%) had significant difference compared with other treatments. The nutritional efficiency index in this group of larvae was better than others. Also the abundance of biochemical macromolecules such as glucose, cholesterol, triacylglycerol and urea in haemolymph of larvae fed by 2% ascorbic acid increased to become 29.75 (mg/㎗), 24 (mg/㎗), 75.4(mg/㎗) and 32.1(mg/㎗) respectively. But protein contents of haemolymph of larvae in each treatment were not significantly different. Since all the results achieved were not considerable either statistically or economically, this method could not be recommended to improve the sericultural parameters.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.1
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• pp.56-62
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• 2009

Feeding regimens was investigated for the growth and survival rate of juvenile Maroon clownfish (Premnas biaculeatus) in order to establish a seed production technique for this fish. Three types of feeding regimens were used, and growth and survival were highest under the following regimen: rotifer from day 0, Artemia from day 4, copepod from day 9 and artificial food from day 15, respectively (P<0.05). The average body lengths of the larvae were $6.76{\pm}0.55\;mm$, $7.63{\pm}0.50\;mm$ and $7.33{\pm}0.43\;mm$ in the Nannochloropsis oculata, Isochrysis galbana and control treatments conducted with 3 larvae/L, respectively (P<0.05). There were significant differences in larval growth between the treatments and controls conducted with 6 larvae/L and 9 larvae/L, respectively (P<0.05) but there was no significant difference between the N. oculata and I. galbana treatments (P>0.05). There were no significant differences in larval growth between the treatments at densities of 3-9 larvae/L (P>0.05). At highest density level, the larvae reared in I. galbana had the highest survival rate whereas survival was lowest in the control.

• Korean Journal of Ichthyology
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• v.5 no.2
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• pp.217-225
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• 1993

A study on the distribution and mortality of eggs and larvae of anchovy. Engraulis japonica, was carried out on the basis of data collected from ichthyoplankton survey in the southern coastal waters of Korea from June to August in 1990. Egg and larval distribution areas were shifted from the adjacent waters of Namhae Is, to the eastern waters of Goeje Is, while eggs and larvae were developed in June. However, high densities of eggs and larvae of anchovy and were found near Goeje Is. in July. Anchovy eggs and larvae were correlated significantly with zooplankton in July, and were not in June and August. It is likely that the low instantaneous mortality coefficients in eggs and high values in the larvae during June and high values in eggs and low values in the larvae during July were affected by the distribution pattern of zooplankton.

• The Korean Journal of Malacology
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• v.19 no.1
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• pp.33-40
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• 2003

To obtain the basic information on culture conditions for the larvae of Saxidomus purpuratus, experiments were conducted on the population from southern coast for (1) the success in fertilization and development from artificial fertilization among different months of a year, (2) the viability of sperms after exposure to seawater, (3) and the effects of temperature, salinity, and food organism on the survival and growth of larvae. Gametes obtained from dissection showed high rate of fertilization at all months. But the rate of development was higher only May-July. Developmental success seemed to be related with the quality of eggs at the time of fertilization. Developmental times for 2-cell, 4-cell, 8-cell, blastula, trochophore larva, and veliger larva at 20$^{\circ}C$ were 1.5, 2, 4, 18, 24, and 32 hr, respectively. Sperms could survive for more than 8 hr, however, actively swimming sperms could be found within 1 hr after exposure to seawater. It is recommended that sperms should be used for fertilization as soon as possible when they are exposed to seawater. At temperature of 35$^{\circ}C$, all the larvae died during 48 hr. Larval survival decreased when salinity was either lower than 20 psu or higher than 40 psu, and was 0% when salinity was 10 psu. Optimal range of temperature and salinity for rearing larvae of S. purpuratus were 20-25$^{\circ}C$ and 20-40 psu, respectively. Larvae grew from 111.5 to 235.3 ${\mu}$m during 21 days. Larvae fed mixed diets grew faster than unialgal diets. The fastest growth was observed when larvae were fed on the mixture of Isochrysis galbana and Nannochloris oculata.