• The Korean Journal of Malacology
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• v.17 no.1
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• pp.35-44
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• 2001

This research was conducted to develop seedling production techniques in flat oyster, Ostrea dense lamellosa. The cultivation of larvae, artificial spat and spats collection in natural conditions rate were examined. In the mass culture tank (3 tons), average growth rates of the D Shape larvae of initial shell length (153.4 ㎛) and shell height (153.4 ㎛) were 202.6% and 212.9% at 16 days and 227.1%, 241.8% at 20 days, respectively. Instantaneous death and survival rate of the larvae were 0.160 and 54.8% at 16 days and 0.057 and 43.2% at 20 days, respectively. Collection rate of flat oyster from bottom using various collectors with oyster shell, scallop shell, ark shell and PVC plates were 32.9%, 24.1%, 16.8% and 10.0%, respectively. and the greatest collecting rate was 131.9 individuals/shell (32.9%) in laid collectors on the bottom. The collecting rate of the oyster larvae were better in laid collectors on the bottom 83.8 individuals/collection than in the suspended string 54.2 individuals/collection. in all collecting substrates. Early spats settled on collectors were grew to 2.38 $\pm$ 0.97 ㎜ in shell length and 2.16 $\pm$ 0.86 ㎜ In shell height at 26 days. The spats were grew to 28.58 $\pm$ 2.39 ㎜ in shell length and 31.65 $\pm$ 2.03 ㎜ in shell height during the 4 month mid-term cultivation. In the period of cultivation, the mean number of spats attached to collectors were 10.3 individuals at oyster shells, 5.8 scallop shells, 4.0 ark shells and 1.5 PVC plates, respectively.

• The Korean Journal of Malacology
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• v.19 no.2
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• pp.133-142
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• 2003

For the effective seedling production of flat oyster, Ostrea denselamellosa, dietary value of live food, densities, water temperature and salinity on growth and survival rate of the larvae were examined. In rearing larvae by feeding them phytoplankton diets, the optimal survival rate and growth rate of larvae were found using a mixed phytoplankton diet which was mixed with Isochrysis galbana, Chaetoceros calcitrans and Chlorella sp. The highest growth and survival rates of the larvae were 208.4% and 38.8% with the phytoplankton diet. In growth and survival rates of larvae with various rearing densities, the highest survival and growth rates were 228.1% and 29.0% at the density of 2 individuals/ml. In observing rearing experiments of the flat oyster larvae under various temperature conditions, average growth rates of the larvae in respect to shell length were 202.2%, 240.4%, 250.6% and 121.3% in natural water temperatures (18-22$^{\circ}C$), 24$^{\circ}C$, 28$^{\circ}C$ and 32 $^{\circ}C$, respectively. And average survival rates of the larvae were 16.0%, 32.0%, 13.0% and 0% in natural water temperatures (18-22$^{\circ}C$), 24$^{\circ}C$, 28$^{\circ}C$ and 32$^{\circ}C$, respectively. In rearing at various salinities, the highest growth rates of the larvae in shell length was 240.0% at 30.0 psu and the highest survival rate was 31.0% at 25 psu.

• The Korean Journal of Malacology
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• v.25 no.1
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• pp.41-49
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• 2009

Random amplified polymorphic DNA (RAPD) marker and sequence analyses of the internal transcribed spacer (ITS) region of ribosomal DNA were used to assess phylogenetic relationships of four Korean oyster species. The average number of species-specific markers identified from five universal rice primers (URPs) by RAPD-PCR was 1.8 for Crassostrea gigas, 3.2 for C. nippona, 3.6 for C. ariakensis, and 4.6 for Ostrea denselamellosa. The length of the ITS (ITS1-5.8S-ITS2) region ranged from 1,001 to 1,206 bp (ITS1, 426-518 bp; 5.8S, 157 bp; and ITS2, 418-536 bp), while the GC content ranged from 55.5-61.1% (ITS1, 56.8-61.8%; 5.8S, 56-57.3%; and ITS2, 54.1-62.2%). A phylogenetic analysis of the oysters based on our RAPD, ITS1, and ITS2 sequence data revealed a close relationship between C. gigas and C. nippona and a distant relationship between the genera Crassostrea and Ostrea. Our results indicated that RAPD and ITS sequence analysis was a useful tool for the elucidation of phylogenetic relationships and for the selection of species-specific markers in Korean oysters.