• The Korean Journal of Malacology
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• v.21 no.2 s.34
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• pp.107-111
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• 2005

In the present study, the fecundation and fertilization behaviors of the trumpet shell, Charonia fampas sauliae were observed from November 2003 to March 2004. Female has multiple fecundation and multiple fertilization, and the fertilization continued for two days. The fertilized female stayed with the egg mass to protect the eggs, and the fecundation was made during the fertilization. The highest survival rate of egg capsule was 60% at $15^{\circ}C$. Charonia lampas sauliae fed with Chaetoceros calcitrans, Isochysis galbana, and Pavlova lutheri. Growth and survival rates of C. lampas sauliae in the conditions of various water temperature were observed. The highest survival rate was 23% at $15^{\circ}C$ reared for 60 days. The growth was presented in the $15^{\circ}C$ group, with shell length from $408{\pm}21.52{\mu}m\;to\;625{\pm}19.76{\mu}m$ during the experiment.

• The Korean Journal of Malacology
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• v.28 no.1
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• pp.7-12
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• 2012

The effect of water temperature on spawning induction, larval development, spat settling and its growth of the cockle shell, Fulvia mutica, were investigated to obtain the basic data for effective seed production. The eggs, which were randomly divided into 6 groups of water temperatures of 14, 17, 20, 23, 26 and $29^{\circ}C$, were transferred into 1 L beaker, respectively. The relationships between the water temperature and the required time (1/h, hour) by each egg developmental stage were calculated. Biological minimum water temperature and the cumulative water temperature until egg development of the veliger stage were calculated to be $0.1^{\circ}C$ and $397.3^{\circ}C$, respectively. The optimal water temperature for developmental bioassay of F. mutica was clarified to be $23^{\circ}C$. The required time for the embryo to become veliger larvae was 20 hours at $23^{\circ}C$.

• Environmental Engineering Research
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• v.19 no.4
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• pp.375-380
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• 2014

Macro fouling due to blue mussels (Mytilus edulis) has affected negatively on the operation efficiency and eventual system failure of offshore structures and coastal power stations. A certain range of chlorine (0.05, 0.1, 0.3, 0.5, 0.7 and 1.0 mg/L) was applied on the mussel larvae to identify the survival rate with respect to various exposure times under laboratory condition. The ciliary movement of the larvae was used to check their survival. The 1.0 mg/L of chlorine shows to 97% of larvae mortality whereas 0.7 mg/L of chlorine shows only 16% of larvae mortality. Minimum exposure times for 100% larvae mortality ranged from 300 to 20 min for increasing concentrations of chlorine (0.05~1.0 mg/L). It was found that 1 mg/L of chlorine was 4 times more efficient than 0.7 mg/L of that, and 15 times more than 0.05 mg/L of chlorine dose. Data collected and analyzed here will help plant operators to optimize chlorine dosage and its scheduling.

• The Korean Journal of Malacology
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• v.25 no.1
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• pp.35-40
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• 2009

The trumpet shell Charonia sauliae is an endangered and valuable species with potential for aquaculture. For artificial propagation of C. sauliae, the effects of three different food microalgae on the development, growth, and survival rate of the larvae and spat were investigated. For the larval feeding experiments, we utilized six microalgae species as food sources, namely Pavlova lutheri, Tetraselmis suecica, Nannochloris oculata, Isochrysis galbana, Chaetoceros calcitrans, and Phaeodactylum tricornutum; for the larval and spat growth and survival experiments, we utilized T. suecica, C. calcitrans, and P. tricornutum. The results showed that the temporal digestion index (TDI) for the veliger larvae was significantly different for C. sauliae fed the different microalgae species (p < 0.05), that the T. suecica, C. calcitrans, and P. tricornutum cultivars were better suited for larval consumption (p < 0.05), and that the growth and survival of the larvae and spat were significantly influenced by food type, specifically P. tricornutum (p < 0.05). Further research is needed to evaluate the effects of other microalgae species, different algal concentrations, and biochemical composition on the growth and survival of C. sauliae.

• Animal cells and systems
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• v.3 no.4
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• pp.375-383
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• 1999

Gonadal development, gametogenesis, reproductive cycle, and first sexual maturity of Reishia clavigera were investigated monthly from July 1998 to June 1999 through cytological and histological observations. R. clavigera had separate sexes, and was an internal fertilizer. The ma1e penis was located near the two tentacles. The ovary and testis were composed of a great number of oogenic lobules and spermatogenic tubules, respectively. The size of ripe oocyte ranged from 130 to 140 ${\mu}$m in diameter. The peripheral cytoplasm of the germinal vesicle of the ripe oocyte in many cases were surrounded by smaller yolk granules, while the eccentric cytoplasm was occupied with larger ones. The reproductive cycle of R. clavigera could be classified into five successive stages: early active, late active, ripe, spawning, and recovery. Spawning of females occurred from early July to August when the seawater reached above 24.8$^{\circ}C$. Spawning of males occurred from early June to August in the water above 22.8$^{\circ}C$. Minimum size for sexual maturity of both sexes was above 10.0 mm in shell height. Each egg capsule was a cylinder or spindle in shape, 4-6 mm in length and 1-2 mm in width. Colors of newly spawned egg capsules showed yellowish white or pale yellow, while those with veliger larvae showed pale black, and released larvae or dead egg capsules showed black violet. The fecundity in an egg capsule ranged from 70 to 91 eggs (mean＝80.28 eggs).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.24 no.6
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• pp.472-482
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• 1991

Seasonal distributions of zooplankton were investigated in Asan Bay, Korea. Labidocera euchaeta, Sagitta crassa, Calanus sinicus, Acartia omorii were dominant taxa throughout the year with seasonally varying percent compositions. Bivalve veliger larva (fall), Decapoda larva (spring and summer), and Paracalanus Parvus, Evadne tergestina (summer) were also dominated during contain period. The patterns of time dependent vertical distributions of one major taxon, A. omorii, showed seasonal differences, i.e., it showed the trends of normal vertical migration in winter and reversed vertical migration in spring. At surface layer day time abundances were equal or less than night time abundances in general.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.6
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• pp.625-631
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• 2003

The aim of the present study was to investigate the ecological relationship between female body size (=shell length) and fecundity in a Korean population of protandric hermaphrodite, Crepidula onyx Sowerby, using 6 reproductive variables (the number of capsules per brood, capsule size, the number of embryos per capsule, total number of embryos per brood, egg size, and larval size). The investigation was based on 32 females, 107 egg capsules, 263 eggs, and 250 veliger larvae sampled in January 2000, from Yangpo, the southeastern coast of Korea. All foregoing reproductive variables, except larval size, were significantly correlated with the female body size (p<0.001$\~0.01$). There was a significant increase both in the number of capsules per brood and the number of embryos per capsule with female body size (p<0.001). Consequently, the fecundity of the female C. onyx increased with female body size to over 14.65 mm (the minimum size of egg brooding in the present study). This investigation, therefore, provides additional evidence that female fecundity of protandric hermaphrodites is positively correlated with female body size.

• Proceedings of the Korean Aquaculture Society Conference
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• 2003.10a
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• pp.86-87
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• 2003

본 실험은 전복 종묘생산 시 먹이생물로 적합한 부착 규조를 파악하기 위하여 실시하였다. 부경대학교 한국해양 미세 조류 은행에서 보유한 부착 규조종 중, 해역, 크기, 부착력, 영양분석 결과를 고려하여, 11종의 부착 규조를 선택하였다. 각 부착 규조를 f/2 배지로 파판에 배양 한 후 평균 각장 7mm의 까막전복 치패를 대상으로 26일 간 먹이 효율을 조사하였다. 또 이 실험의 결과를 토대로 먹이 효율이 좋은 4종의 부착 규조를 선택하여 참전복 유생의 부착율과 먹이 효율을 조사하였다. 참전복 유생은 수정 후 56 시간이 지난 veliger유생을 이용하여 각 규조에 따른 유생의 부착율, 사망률, 변태율, 성장률을 측정하였다. 까막전복 치패를 대상으로 규조종별 먹이 효율을 실험한 결과, 생존율은 Caloneis schroder가 37.1%, Nitzchia sp. 35.0%, Navicula sp.가 31.4%로 대체로 높은 생존율을 보인 반면에, Navicula elegans이 6.4%, Cylidrotheca closterium.은 11.7%로 낮은 생존율을 보였다. 실험 종료후, 까막전복 각장의 성장을 측정한 결과, Cocconeis californica가 9.33 mm, Achnanthes sp.은 9.27 mm으로 대체로 높은 성장을 보였다. 이에 반해 Navicula elegans은 8.60 mm으로 낮은 성장을 보였다. 전복 전중과 육중은 Amphora sp.에서 각각 87.7mg, 35.2mg 으로 가장 높았으며, Cocconeis californica와 Achnanthes sp.에서도 대체적으로 높게 나타났다. Navicula elegans는 각장의 성장에서와 같이 가장 낮은 증육을 보였다. 규조 4종을 대상으로 한 참전복 유생의 부착율 에서는 수정 후 152시간 후 Cocconies califonica에서 47.3%로 가장 높은 반면, Caloneis schroder 에서 23.8%로 가장 낮았다. 실험 9일째 사망률은 Cocconeis californica에서 63.6%로 가장 낮게 나타났고, Nitzchia sp.에서 90.4%로 가장 높게 나타났다. 유생의 변태율은 Cocconeis californica에서 98.5%로 가장 높은 결과를 보였다. 유생의 일간 성장율 역시 Cocconeis californica에서 25.4 $\mu\textrm{m}$/day로 높았고, Nitzchia sp.에서 13.9 $\mu\textrm{m}$/day로 낮았다. 실험 24일째 참전복 유생의 최종 생존율은 변태율과 일간 성장률이 높았던, Cocconeis californica에서 7.8%로 가장 높게 나타났다.

• 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.

• Journal of Animal Reproduction and Biotechnology
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• v.34 no.4
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• pp.280-291
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• 2019

Potential utility of 14 candidate housekeeping genes as normalization reference for RT-qPCR analysis with developmental samples (fertilized eggs to late veliger larvae) in Pacific abalone Haliotis discus hannai was evaluated using four different statistical algorithms (geNorm, NormFinder, BestKeeper and comparative ΔCT method). Different algorithms identified different genes as the best candidates, and geometric mean-based final ranking from the most to the least stable expression was as follow: RPL5, RPL4, RPS18, RPL8, RPL7, UBE2, RPL7A, GAPDH, RPL36, PPIB, EF1A, ACTB and B-TU. The findings were further validated via relative quantification of metallothionein (MT) transcripts using the stable and unstable reference genes, and expression levels of MT were greatly influenced according to the choice of reference genes. In overall, our data suggest that RPL5 and RPS18, either singly or in combination, are appropriate for normalizing gene expression in developmental samples of this abalone species, whereas ACTB, B-TU and EF1A are less stable and not recommended. In addition, our findings propose that standard deviations in geometric ranking as well as geometric mean itself should also be taken into account for the final selection of reference gene(s). This study could be a useful basis to facilitate the generation of accurate and reliable RT-qPCR data with developmental samples in this abalone species.