• The Korean Journal of Malacology
• /
• v.30 no.4
• /
• pp.303-309
• /
• 2014

The development of Japanese geoduck, Panopea japonica, grown under culture conditions, has been examined through the morphological characteristics in fertilized egg, larvae and juvenile. Gametes were stripped from ripe broodstock and placed into two separate containers. Eggs were washed through a $40{\mu}m$ sieve and fertilized with dilute sperm solution. Developing larvae were maintained at $19{\pm}1^{\circ}C$. Fertilized eggs with $81.6{\mu}m$ diameter developed to trochophores within 14 h and to D-stage larvae ($116{\mu}m$ shell length) within 27 h. Larvae were spontaneously settled at shell length of $311{\mu}m$ after 20 days. The hatching from fertilized eggs and larval rearing were normally available in $18.5-21.5^{\circ}C$, and the growth was good in a cashmilon substrate, as well as sand. After rearing of day 108 from metamorphosis, the shell length of juvenile P. japonica reached 13 mm, and growth rate of shell length of the juvenile was $117.5{\mu}m/d$.

• The Korean Journal of Malacology
• /
• v.31 no.4
• /
• pp.263-266
• /
• 2015

This study was performed to determine the effect of water temperature condition on survival rate and growth of juvenile geoduck (Panopea japonica). Panopea japonica juveniles were bred for 6 weeks at 12, 15, 18, 21, 24 and $27^{\circ}C$ on incubator. Juveniles median lethal times (LT50) were 29 hours in $27^{\circ}C$, 14.5 day in $24^{\circ}C$, 37.4 day in $21^{\circ}C$. Survival rate of water temperature 12, 15 and $18^{\circ}C$ showed a high survival rate in 95.0%, 95.0% and 93.3% at 6 weeks. As a result of culturing for 6 weeks at 12, 15, 18, 21 and $24^{\circ}C$, a daily growth of shell length and total weight was 0.10 mm, 0.12 mm, 0.13 mm, 0.16 mm and 0.14 mm, and 2.21 mg, 2.65 mg, 2.84 mg, 3.13 mg and 2.93 mg. Juvenile shell length and total weight have significantly increased at $15-21^{\circ}C$. However, mortality rate has significantly increased at more than $21^{\circ}C$. As a result, appropriate water temperature for juveniles culturing considered $15-18^{\circ}C$.

• Journal of fish pathology
• /
• v.33 no.2
• /
• pp.127-138
• /
• 2020

We attempted to isolate and identify potentially pathogenic bacteria from geoduck clam (Panopea japonica) larvae, juvenile and adult, focusing on Vibrios. The isolates were identified by molecular approach and biochemical characterization. In particular, we applied MLSA (multilocus sequence analysis) to the isolated Vibrios for clear identification and phylogenetic relationships, by combining 16s rDNA and several houskeeping genes (pyrH, recA, rpoA). We obtained 141 isolates; 10 from healthy adults, 52 from moribund adults with blisters and 79 from larvae. 46 from the moribund adults and 39 from the larvae were identified as Vibrio species, while the rest of these samples and all the isolates from healthy adult were identified as marine general bacteria. Among Vibrio species, Vibrio splendidus was the most frequently identified from the moribund adults and clustered with the known V. splendidus in GenBank by MLSA. However, it was still unclear that V. splendidus was the cause of blisters because the artificial infection experiment was not conducted and V. splendidus was isolated also from the larvae. Further studies are necessary to clarify the etiological agent of the blisters found in geoduck clam in this study.