• Journal of Aquaculture
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• v.15 no.2
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• pp.79-86
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• 2002

This study is the first attempt to understand the feeding physiology of a sea-urchin larva on a red-tide dinoflagellate. Fifteen day old larvae of S. intermedius capture C. polykrikoides cells by localized reversal of ciliary beats. No failure to transporte the algal cells from theciliated band to mouth and no rejection at the mouth suggest that C. polykrikoides has no feeding deterrence to S. intermedius larvae. The trend obtained for the clearance rate of S. intermedius larvae is similar to that of other sea urchin larvae. Thus, the clearance rate decreased as the algal concentration increased. Maximum clearance rate of S. intermedius on C. polykrikoides was 17.7 $\mu l$/larva/hr. Ingestion rate rapidly increased at lower algal concentrations and saturated at higher concentrations. There was no inhibition in ingestion rate at the highest prey concentration of ca. 3000 cells/ml. Maximum ingestion rate of S. intermedius on C. polykrikoides was 131 ngC/larva/d, which is higher than that reported for the larvae of the mussel Mytilus gal-lotrovincialis, but lower than that of the ciliate Strombidinopsis sp. The grazing rate, calculated by combining the field data on algal abundances with experimental data on ingestion rate, suggests that due to its low abundance, sea urchin Iarva has no significant grazing impact on C. polykrikoides population.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2002.05a
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• pp.500-501
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• 2002

• Proceedings of the Korean Aquaculture Society Conference
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• 2002.08a
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• pp.165-166
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• 2002

• Environmental Analysis Health and Toxicology
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• v.22 no.3
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• pp.211-218
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• 2007

Even though some standard developmental bioassay protocols for environmental assessment using sea urchins have already been described, there have not been many attempts to apply and modify these protocols with Korean species. Therefore, there is a strong need to establish standard bioassay protocols using sea urchins commonly found in Korea. Prior to developing a new protocol, it is essential to know the optimal conditions for the bioassay procedures. We investigated the optimal conditions (temperature, salinity, and embryo density) of the sea urchin Strongylocentrotus intermedius. The ideal temperature for developmental bioassay of S. intermedius was determined to be $15^{\circ}C$ and the time required for the embryo to become pluteus larva was 72 hr. The optimal range of salinity for the embryo toxicity using S. intermedius was between 30 to 32 psu, which is similar to the range found in the natural habitats of adult populations. The optimum density of embryos at the beginning of bioassays was 100 embryos/mL. When the assays were carried out at higher densities, the proportion of normally developed larvae decreased significantly.

• Journal of Aquaculture
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• v.8 no.4
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• pp.317-326
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• 1995

In order to evaluate three species of diatoms as the live food sources for rearing larvae of sea urchin, Strongylocentrotus intermedius, six different feed experiments were conducted for 35 days. We measured sizes, survival rates on elapsed day after hatching and required days of each larval stages of sea urchin in the different feeding experiments. Sizes of the larvae of sea urchin cultured with Isochrysis + Chaetoceros, Isochrysis, Chaetoceros and Pavlova were $735{\mu}m$, $718{\mu}m$, $701{\mu}m$ and $642{\mu}m$, respectively. The highest daily growth rates of the larvae of sea urchin showed Isochrysis within 6 armed and Chaetoceros after 6 armed. Survival rates of the larvae of sea urchin cultured with Chaetoceros, Isochrysis + Chaetoceros, Isochrysis and Pavlova were $37.2\%,\;35.0\%,\;32.4\%,\;and\;18.4\%$, respectively. The required days from fertilization to the 8 armed (Senior) stage in the larvae of sea urchin, fed Chaetoceros, Isochrysis, Paviova, chaetocerost+pavlova, pavloua + Isochrysis and Isochrvsis + chaetoceros were 24, 27, 33, 28, 30 and 25 days, respectively.

• Journal of Aquaculture
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• v.16 no.2
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• pp.94-98
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• 2003

Effect of temperature (5, 10, 15, 18, 21$^{\circ}C$) on pre-and post-embryonic development of the sea urchin Strongylocentrotus intermedius was studied. The egg, which measured 122.5 ${\mu}{\textrm}{m}$, became globular. At 18$^{\circ}C$, it attained 4 celled stage at 3 hours after fertilization, hatched after 15 hours, 4-armed larval stage after 3 days and 8- armed larval stage after 20 days. The relationships between temperature (WT) and time (1, hour) required for each of the selected developmental stages are: Hatching: 1/t=0.0036WT+0.0088 Pyramid: 1/t=0.0014Wl-0.0016 4- armed: 1/t=0.0009WT-0.0020 6- armed: 1/t=0.0004WT-0.0005 8-armed : 1/t=0.0002WT+0.0002 Biological minimum temperature for the egg and larval development is calculated as 1.61$^{\circ}C$.

• Journal of Aquaculture
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• v.16 no.3
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• pp.129-134
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• 2003

Spawning induction and early growth of the sea urchin, Strongylocentrotus intermedius were studied with the purpose of artificial seedling production. Gonadosomatic index(GSI) of the sea urchin showed the highest value in October, and rapidly decreased in December. It means that October and November is the peak of spawning season of the sea urchin in the latitude. Spawning induction by injection of potassium chloride solution in October has showed 44.0~100.0% reaction rate, and were produced 6,300$\times$10$^4$ eggs. Spawned eggs have shown the fertilization rate of 92.3~98.2% and the hatching rate of 78.2~87.0%. The metamorphosis of larvae after hatching in the seawater temperature of 13.7~17.1$^{\circ}C$ resulted in early eight-armed larvae in 13 days and late eight-armed larvae in 20 days. The collection of progenies was possible in 24~25 days after hatching and collection rate was 18.5~26.1% (mean 22.3%). Test diameter immediately after collection had a mean 350 ${\mu}{\textrm}{m}$. Survival rate and test diameter of juvenile sea urchin after collection were 58.5%, 1.32 mm in 30 days, 27.7%, 3.82 mm in 92 days and 15.6%, 11.70 mm in 181 days, respectively.