• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.10a
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• pp.277-278
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• 2001

최근 경제적이고 안정적인 rotifer 배양방법으로 담수산 농축 Chlorella를 이용한 rotifer 고밀도 배양이 수행되었고 이러한 배양방법은 rotifer의 양적 확보에 매우 효과적인 것으로 나타났다. 이처럼 고밀도 배양에 이용되는 담수산 농축 Chlorella는 무균 발효조에서 배양되기 때문에 가격이 매우 싸고, 세포내 rotifer 성장에 많은 영향을 미치는 B$_{12}$함량이 매우 풍부하다. (중략)

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.2
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• pp.160-163
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• 2001

This study was performed to investigate the effect of vitamin $B_{12}$ addition on the production and hatching rate of resting egg of freshwater rotifer, Brachionus calyciflorus. Different concentrations of vitamin $B_{12}$ was added into concentrated freshwater Chlorella before fed to rotifer and rotifer was cultured in 250 mL flask. The maximum density of rotifer was 138 inds./mL at 6 ppm and it increased with an increase of vitamin $B_{12}$ addition. Mixis rate and fertilization rate of rotifer were $63.0\%$ and $89.6\%$, respectively, at 6.0 ppm. The production of resting eggs per mL was 231 eggs/mL at 1.5 ppm, but there was no significant difference among vitamin $B_{12}$ addition levels. The highest production of resting eggs per 10,000 rotifers and Chlorella dry weight (g) were 11,289 eggs and 121,252 eggs, respectively, at the 6 ppm. The hatching rate of resting egg was not significantly different among vitamin $B_{12}$ addition levels, but significantly higher than the control (without addition of vitamin $B_{12}$ ). These results showed that vitamin $B_{12}$ addition could affect production and hatching rate of resting egg of freshwater rotifer, B. calyciflorus.

• Fisheries and Aquatic Sciences
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• v.14 no.4
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• pp.333-337
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• 2011

A new and a unique Brachionus rotifer was found in Hwajinpo coastal lagoon in Gangwon Province, South Korea. This Brachionus certainly originated from the wild rather than from aquaculture stations because Hwajinpo coastal lagoon has been under rigorous control as a military protected area and therefore could not have been contaminated by aquaculture stations. The new strain was identified as Brachionus rotundiformis based upon its morphological characteristics. The parthenogenetic female of this new rotifer strain typically shows characters similar to those of B. rotundiformis, such as the pot shape of the body, rounded dorsal plate compared with flattened ventral plate, elliptical mictic egg, four frontal spines, six pointed occipital spines, non-nodal foot, two toes, trophi typical of the Brachionus genus with five uncus plates resembling comb teeth, one wide symmetrical manubrium and ramus, and no stiffened spine as is seen in freshwater Brachionus rotifers. Moreover, its lorica was rather small in size compared with other common rotifer strains that serve as live-food organisms (Guam, Thai, and Bali strains). This new and unique Korean brackish rotifer, a B. rotundiformis strain, was therefore named the National Fisheries Research and Development Institute (NFRDI) $N^{\circ}1$ rotifer strain.

• Journal of Aquaculture
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• v.2 no.2
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• pp.91-106
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• 1989

Chlorella has been used as a very useful food for rearing rotifer which is an important live food for early stages of fish and crustancean larvae. But Chlorella does not grow well in higher or lower temperature such as during summer or winter season in this country. Therefore, cooling or heating facilities are needed for Chlorella culture during summer or winter, but it costs too much for the commercial scale fish farmers. To solve this problem, the growth rates of 34 different species of phytoplanktons were examined at the various levels of temperatures, salinites and light intensities to select suitable species as the food for rotifers for summer and that for winter. After the suitable species were selected, growth comparisons of rotifer groups which were fed the selected species of phytoplanktons against rotifer group fed Chlorella as a control were done. Fatty acid compositions of the selected phytoplanktons and rotifer groups which were fed these selected phytoplanktons were examined. It was revealed that Nannnochioris oculata was optimum for rotifers in summer season and Phaeodactylum tricornutum was suitable for that in winter season. The optimum temperature, salinity and light intensity for former phytoplankton were $28^{\circ}C$, $33\%_{\circ}$ and 5,000 lux and those for later were $10^{\circ}C$, $30\%_{\circ}$ and 8,000 lux, respectively. In the higher temperature condition, the growth of N. oculata fed rotifer group was better than Chlorella ellipsoidea fed group. In the lower temperature condition, however, the growth of Chlorella fed rotifer group was slightly better than P. tricornutum fed group. Between two selected phytoplanktons, N. oculata has the highest content of linolenic acid (18 : 3 $\omega$ - 3, $\omega$ - 6) which is essential fatty acid for marine fish larvae. A rotifer group which was fed this plankton also showed the highest linolenic acid content among the other rotifer groups.

• Journal of Aquaculture
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• v.9 no.3
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• pp.195-203
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• 1996

Six strains (OKK, MOK, CHA, WON, 505 & PUA) of Korean rotifer, Brachionus plicatilis (S-type) were isolated from salt pond, and the resting egg production of these strains was investigated with the different salinities (10, 20, 30 put), Rotifer were cultured at $28^{\circ}C$ and 2,000 lux in 20 ml test tube with feeding Nannoohloris oculata. The maximum rotifer density was 2,050 inds./ml at 10 ppt for OKK strain, and MOK strain showed the highest specific growth rate (1.028) at 10 ppt. Mixis rate of CHA and WON strains increased with the lower salinity, while MOK strain increased the rate with salinity. PUA strain did not show the mixis rate even at the high rotifer density, and OKK strain showed the very low mixis rate ranging from 1.1 to $3.0\%$. Fertilization rate of CHA, MOK, SOS and WON strains was ranged from 10.4 to $68.8\%$, and OKK strain did not showed any fertilization rate. The highest production of resting egg in 20 ml test tube was 4,065 eggs at 10 ppt for WON strain. The results may suggest that the selection of rotifer strain and salinity are important factors for the mass production of resting egg.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.2
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• pp.156-159
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• 2001

The experiment was carried out to investigate the productivity of freshwater rotifer, Brachionus calyciflorus and marine rotifer, B. rotundiformis at various temperatures, initial inoculation and pH in a 5 L semi-continuous high density culture. Rotifers were fed by commercial condensed freshwater Chlorella. When pH was not controlled, average daily productions of freshwater and marine rotifers increased with temperature. The highest production, $44\times10^6$ rotifers, was achieved of B. calyciflorus at $32^{\circ}C$ and the possible production lasting period of B. calyciflorus was shorter than that of B. rotundiformis. Under the adjustment of pH at 7, the possible production lasting periods of B. calyciflorus and B. rotundiformis inoculated with 5,000 inds./mL were longer than those of rotifers inoculated with 10,000 inds./mL, and the daily production rate of the former was higher than that of the latter. The results from this study indicated that optimum density of the initial inoculation for the cultivation of B. calyciflorus and B. rotundiformis was 5,000 inds,/mL under the controlled conditions of pH 7 and at $32^{\circ}C$ in a semi-continuous high density culture, in terms of production rate and food cost aspects.

• Journal of Aquaculture
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• v.9 no.4
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• pp.453-459
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• 1996

Cellulase was purified from marine rotifer, Brachionus plicatilis, to homogeneity by using chromatographic methods. Purified enzyme is an endo-${\beta}$-1,4 glucanase and shows a strong hydrolytic activity against carboxymethyl (CM) -cellulose. The physicochemical parameters of enzyme activity were determined. The molecular weight of the purified protein was approximately 62 kDa as determined by SDS-polyacrylamide gel electrophoresis. The enzymatic capability to digest cellulose of Chlorella cell wall was compared with that of other well known cellulases from Thermomonospora fusca. Experiments involving Chlorella digestion indicated that CM-cellulase from marine rotifer, Brachionus plicatilis, could digest Chlorella very efficiently while cellulase purified from Thermomonospora fusca did not. From the result here, we propose that the cellulolytic system from marine rotifer is responsible for the hydrolysis of cellulosic wall of Chlorella, probing that rotifer digests Chlorella as a major live food.

• Journal of Fisheries and Marine Sciences Education
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• v.26 no.1
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• pp.1-9
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• 2014

One of freshwater rotifer (Brachionus calyciflorus) is very useful as a live food organism for early larval rearing of freshwater aquaculture industry. However, the knowledge about freshwater rotifer culture is scarce. On the other hand, marine rotifer culture as live food organisms is done, almost perfectly. In this study, I show to be benefit experimental results for successful freshwater larval rearing through the observation with microcosm structure in freshwater rotifer culture tanks.

• Fisheries and Aquatic Sciences
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• v.15 no.1
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• pp.57-62
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• 2012

Interspecific relationship between a euryhaline rotifer Brachionus rotundiformis and a cyclopoid copepod Apocyclops borneoensis was investigated in the laboratory culture. In a mixed culture of B. rotundiformis and A. borneoensis, population growth of B. rotundiformis was suppressed from day 10, while growth in a monoculture population continuously increased throughout the experimental period. However, the population growth of A. borneoensis in the mixed culture did not markedly differ from that in a monoculture population. Suppression of B. rotundiformis growth coincided with a decrease in the numbers of both non-egg-bearing and egg-bearing females, and increasing resting egg formation. Growth of A. borneoensis was not affected by the presence of the rotifer. However, relative growth index of ovisac bearing females in the mixed culture was 1.62 times higher than that in the monoculture. Presence of the copepod did not greatly reduce the food available to the rotifer population. The rotifer B. rotundiformis responded in a unique way, to stresses such as physical damage (filtering by A. borneoensis) with the production of many resting eggs to increase its chances of survival.

• Journal of Aquaculture
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• v.11 no.1
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• pp.91-97
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• 1998

This paper introduces to a simple culture method and growth of axenic (bacteria-free) rotifer Brachionus rotundiformis for seed stock of rotifer mass culture. This rotifer axenic culture method is based on the washing and transferring with sterilized sea water and modified antibiotic mixture AM9 solution. Population growth (final density on day 16) of axenic cultured rotifer were maintained with a high density and stable growth compared with the control of non-axenic culture (general culture style) through the 3 times-rerunning experiments (trial 1, 2 and 3). But the egg carrying rates of amictic females were not different between the axenic-and non-axenic culture condition. Although, rotifer density was higher in axenic culture, the food (Nannochloropsis oculata) was still remained unutilized than that of the non-axenic culture in third trial culture. These results suggest the possible existence of harmful bacteria for the rotifer population growth in the trial 1 and 3 of non-axenic culture compared to the trial 2. This axenic rotifer culture method is valuable for seed stock of the stable rotifer mass cultures.