• 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.12 no.1
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• pp.31-38
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• 1999

The dietary value and fatty acids composition for the hatched neonates from the resting eggs of marine roofers, Brachionus plicatilis and B. rotundiformis were compared with that for mass-cultured rotifers (control) by feeding them to larvae of flounder (Paralichthy olivaceus) and parrot fish (Oplegnathus fasciatus). Resting eggs were mass-produced in $1~4m^3$tanks by feeding Chlorella sp. and baker's yeast. The B. plicatilis and B. rotundiformis eggs were preserved at $5^{\circ}C$ in darkness for 3 and 5 months, respectively, and hatched at $28^{\circ}C$ under continuous light. The hatched neonates from the resting eggs and mass-cultured rotifer, which was used as a rontrol were fed to fish larvaes. The growth and survival rates of parrot fish larvae fed on the neonates from the resting eggs of B. rotundiformis were similar to those of fish larvae fed on the control rotifer. And the growth and survival rates of the flounder larvae with neonates from the resting eggs of B. plicatilis were similar or higher than those fed the control rotifer. Also the fatty acids composition of the neonates from the resting eggs of B. plicatilis and B. rotundiformis were similar to those from the control rotifers. This results showed that the hatched neonates from resting eggs of rotifer could be used as an effective diet for flounder and parrot fish larvae.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.6
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• pp.658-664
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• 2011

Rotifers of the genus Brachionus are commonly used as a live food for larval fish, and rotifers of different sizes are preferred according the mouth size of the fish. Rotifer species vary in size, and individual size can depend on the temperature and salinity of the rearing environment. We investigated the effects of temperature and salinity for two species, B. plicatilis (250-300 ${\mu}m$) and B. rotundiformis (100-220 ${\mu}m$). Two strains of B. plicatilis (CCUMP 36 and 48) and two strains of B. rotundiformis (CCUMP 51 and 56) were received from the Culture Collection of Useful Marine Plankton (CCUMP) at Pukyong National University and cultured with the green alga, Nannochloris oculata (KMMCC 16) from the Korea Marine Microalgal Culture Center (KMMCC). The growth and size of rotifers were examined at three water temperatures ($16^{\circ}C$, $24^{\circ}C$, $32^{\circ}C$) and four salinities (20 psu, 25 psu, 30 psu, 35 psu) under continuous light (40 ${\mu}molm^{-2}s^{-1}$). The maximum density and growth rate of B. rotundiformis were greater than those of B. plicatilis. The lorica length of B. plicatilis ranged from 215.4 to 269.7 ${\mu}m$ and from 154.9 to 206.6 ${\mu}m$ for B. rotundiformis, depending on strain, temperature and salinity. Rotifers were smaller when cultured at high temperatures, regardless of salinity. B. rotundiformis preferred higher salinity than B. plicatilis. The results demonstrated that the size of rotifers could be controlled to some extent by temperature and salinity.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.1
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• pp.66-69
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• 2000

The common harpacticoida copepod species Tigriopus japnnicus was often obseued in the mass culture of marine rotifer tanks of sea farming stations. In this study, we investigated the co-existing effect of T. iaponicus to the rotifer Brachionus rotundiformis population growth. The culture conditions as temperature, salinity, culture volume, photo period, culture period and observation interval were 25{\circ}C, 22ppt, 40ml, 12L:12D, 16 deys$ and every two days during the experimental period, respectively. Nannochloropsis oculata was used as the food for the two testing organisms. After counting the growth of rotifer and copepod, they were transferred to new culture tank with N. oculata at the density of $7{times}10^5\;cells/ml$. The population growth of B. rotundiformis was suppressed by T. japonicus when these two organisms were mix-cultured comparing to single culture of B. rotundiformis. But population growth of T, japomcus was not affected by the presence of B. rotundiformis. The interspecific relationships of prey-predation and food competition were not observed in the combination culture of rotifer B. rotundiformis and copepod T japonicus.

• 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.

• 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 the Korea Academia-Industrial cooperation Society
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• v.20 no.10
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• pp.62-67
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• 2019

We studied the effect of several sex-related steroid hormones (serotonin, progesterone and ${\beta}$-estradiol) for 6 days on the induction of sexual reproduction for the mass production of resting eggs in the marine rotifer Brachionus rotundiformis. The highest mix rate of 20.6% appeared with the ${\beta}$-estradiol ($E_2$) treatment on the third day. The number of resting eggs was highest with $E_2$ treatment, followed by that of the serotonin treatment group. In addition, we investigated the effect of the hormones on the expression pattern of the genes related to sexual reproduction in the rotifer. NrbP, SRY, Cyclin and MrpmB genes were up-regulated with all the hormone treatments. As a result, ${\beta}$-estradiol was more effective than the other hormone treatments to produce resting eggs in B. rotundiformis. We suggest that the sexual reproduction-related genes in the rotifer are the NrbP, SRY, Cyclin and MrpmB genes. Further study is required to determine the optimum concentration of $E_2$ for the effective production of resting eggs in the rotifer.

• Journal of Life Science
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• v.22 no.4
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• pp.486-491
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• 2012

Myostatin (MSTN), a member of the transforming growth factor (TGF)-beta family, is a potent negative regulator of skeletal muscle growth and maintenance. The MSTN prodomain inhibits MSTN biological activity. The rotifer Brachionus rotundiformis is an excellent primary live feed for fish larvae in aquaculture; however, it is not known whether the rotifer expresses MSTN and the MSTN prodomain along with its activity. The objective of this study was to examine the effects of recombinant MSTN prodomains. Individual cultures of the rotifer B. rotundiformis were carried out to determine the effect of recombinant MSTN prodomains (pMALc2x-poMSTNpro and pMALc2x-sMSTNpro) on the pre-reproductive phase, reproductive phase, post-reproductive phase, offspring, lifespan, fecundity, and male ratio. In addition, a population culture of the rotifer was performed to confirm the effects of pMALc2x-poMSTNpro and pMALc2x-sMSTNpro on population growth. The results showed that the rotifer treated with pMALc2x-pMSTNpro had a reduced pre-reproductive phase at higher concentrations (1, 2, and 4 ${\mu}g/ml$) compared to the non-treated control group. Moreover, the pMALc2xsMSTNpro treated rotifer effectively decreased the pre-reproductive phase at a lower concentration (0.25 ${\mu}g/ml$) compared to the pMALc2x-pMSTNpro treated and control group. Interestingly, pMALc2x-poMSTNpro and pMALc2x-sMSTNpro significantly increased the population of $B.$ $rotundiformis$.

• Journal of Aquaculture
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• v.11 no.4
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• pp.449-455
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• 1998

The small size food organism(under the size 150${\mu}m$) is needed as food for early stage of marine fish larvae of small mouse (e.g the group of grouper). This study was investigated to develop a method for copepod Apocyclops sp. culture in combination with the rotifer B. rachionus for stable culture of copepod species and harvest of various size food organisms. The culture conditions as temperature, salinity, culture volume, photo period, culture preiod and observation interval were 25${\circ}C$, 22ppt, 40ml, all dark except to observation time, 16 days and every two day during the experimental period, respectively. The Tetraselmis suecica was used as the food for the two testing orgtanisms. After every two day counting, theses two organisms were transferred to fresh culture tanks with Tetraselmis suecica of $7{\times}10^5$cells/ml. In the mixed culture of B. rotundiformis and A. sp., growth of rotifer was suppressed by mixed culture with A. sp. whereas the growth of copepod Apocyclops was promoted in the mixed culture with rotifer B. rotundiformis (the maximum density was 22 individuals/ml through the 16 culture days). Moreover, the number of copepod nauplius were promoted about 2 times in the mixed culture compared to the numbers in single species culture. With this combination culture, the havested two food organisms of variable sizes. This size variation of food organisms was useful tools for larval rearing of small mouse marine fish larvae and next step food organism size of post hatched larvae.

• Journal of Aquaculture
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• v.20 no.3
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• pp.168-172
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• 2007

Two zooplankton species Brachionus rotundiformis (rotifera) and Tigriopus japonicus (copepoda; harpacticoida) were commonly used as live food organisms in the marine larval rearing centers. The combination culture method of two live food organisms (B. rotundiformis and T. japonicus) was well known as very valuable for stable and mass cultures. In this study, we investigated the effects of photoperiod exchanges on the growth and interspecific relationship in the combination culture of two species. The results showed that, photoperiod condition can change copepod (and rotifer) density under the two species combination cultures. There is 200% higher maximum rotifer density on the 24L:0D photoperiod culture condition compare to 12L:12D condition. However, maximum density of copepod is observed highest on the 0L:24D photoperiod culture condition. In addition, it's differ in the culture densities of nauplii, copepodites and female carrying eggs on the each three photoperiod types.