• Korean Journal of Fisheries and Aquatic Sciences
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• v.26 no.6
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• pp.511-518
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• 1993

The lifespan and fecundity of three types(ultra small, small and large) rotifer, Brachionus plicatilis, were investigated. Generally, the lifespan and fecundity of three types rotifer were better at $25{\sim}27^{\circ}C$ than at $20{\sim}22^{\circ}C$, and this phenomenon was more distinct in the ultra small and the small type rotifers. With regard to salinity, while the ultra small and the large type rotifer prefer.ed low salinity(16ppt) to high salinity(32ppt), fecundity of the small type rotifer was higher at high salinity(32ppt) than at low salinity(16ppt). Suitable food organisms were Tetraselmis tetrathele and Chlorella ellipsoidea for the three types rotifer. Tetraselmis tetrathele was more adequate for the ultra small and large type rotifer as live food. However, Chlorella ellipsoidea showed better dietary value for the small type rotifer.

• Fisheries and Aquatic Sciences
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• v.8 no.2
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• pp.70-75
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• 2005

We investigated the effects of salinity and three food species of microalgae on the growth of three types of the rotifer Brachionus plicatilis, with the aim of improving mass culture of rotifers in hatcheries. Three types (large, small, and ultra-small) of the rotifer were cultured at 16 ppt and 32 ppt salinity with the green algae Chlorella ellipsoidea, Nannochloris oculata, or Tetraselmis tetrathele. The maximum density and specific growth rate were compared for each rotifer type. Ultra-small rotifers grew significantly faster at 16 ppt salinity than at 32 ppt, and C. ellipsoidea and T. tetrathele promoted significantly higher growth than did N. oculata. However, small rotifers grew significantly better at 32 ppt salinity than at 16 ppt, and small rotifers fed on N. oculata achieved the highest density at 1,185 individuals/ml. Large rotifers grew faster at 16 ppt salinity than at 32 ppt, with a diet of T. tetrathele resulting in the fastest growth. Each type of rotifer thrived under different regimens of microalgae and salinity.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.4
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• pp.354-359
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• 2009

The productivity of ultra-small rotifer, Synchaeta kitina was investigated at the exchange rate of culture water (10, 20, 30, 40 and 50%) and initial inoculation densities (250, 600 and 900 inds. per mL) in semi-continuous culture. Also, the possibility of mass culture was investigated in a 100 L culture tank. Tetraselmis suecica was used as the feed for S. kitina in all experiments. The production of S. kitina increased with an increase in exchange rate of culture water. The highest production ($82.0{\times}10^5$ inds.) was achieved at 40% exchange rate of culture water. The production of S. kitina increased with an increase of initial inoculation density during the first week and the highest total production ($17.4{\times}10^6$ inds.) was achieved at 900 inds. per mL of initial inoculation density. However, on the second week, all treatments were not significantly different in total production (P>0.05). During the two weeks, total production of S. kitina at 900 inds. per mL of initial inoculation density was higher than at 600 inds. of initial inoculation density, but there was no significant difference (P>0.05). In the 100 L culture tank, density of S. kitina was kept from 516 to 890 inds. per mL and S. kitina was daily harvested $15.5{\times}10^6$ to $26.7{\times}10^6$ during the experimental period. The production cost for 100 million rotifers in semi-continuous culture was 63,656 won. The results from this study indicate that the optimal exchange rate of culture water and initial inoculation density for the semi-continuous culture of ultra-small rotifer, S. kitina are 40% and 600 inds. per mL, respectively.

• Journal of Aquaculture
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• v.21 no.2
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• pp.70-75
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• 2008

We investigated the optimum salinity and temperature conditions for mass culture of ultra-small rotifer Synchaeta kitina. In the salinity experiment of ranging within 5 and 30 psu, the population growth of S. kitina increased continuously up to 20 psu, and then decreased over 20 psu. Their maximum density showed 390.1 inds./mL at 5 psu. A pre-reproductive phase was shortened in low salinity than high salinity. Also, the maximum offsprings and maximum lifespan and lifespan of the female were 13.4 inds. and 5.9 days, respctively at 5 psu. In the temperature experiments of ranging within 16 and $32^{\circ}C$, the population growth of S. kitina increased continuously up to $24^{\circ}C$, and then decreased over $24^{\circ}C$. The highest maximum density showed 492.8 inds./mL at $16^{\circ}C$. Their offsprings increased significantly with temperature decrease, and the maximum number of offsprings per female was 9.2 females. at $16^{\circ}C$. Their lifespan increased with temperatures decrease and the longest lifespan was to 5.5 days at $16^{\circ}C$. From these results, we conclude that the optimum culture conditions of S. kitina is 5 psu and $16^{\circ}C$.

• Journal of Aquaculture
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• v.9 no.3
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• pp.187-194
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• 1996

Sixteen strains of marine rotifer, Braohionus plicatilis were isolated from salt pond, estuary and lagoon. Among 16 strains, 2 strains were large (L)-type and the others were small (S) or ultra small (US)-type. Four strains of fresh water rotifer, B. calyciflorus were isolated from commercial fish ponds. The size of lorica and resting egg were measured. In B. plicatilis, the range of lorica length from S-type and S-type were $244.3{\~}255.3\;{\mu}m$ and $131.0{\~}165.8\;{\mu}m$, respectively. The major axis of resting egg in the marine rotifer were $93.7\~116.4\;{\mu}m$ for S-type and $142.4{\~}145.5\;{mu}m$ for L-type, respectively. In freshwater rotifer, B. calyciflorus, the size range of lorica and major axis of resting egg were $211.8\~229.9\;{\mu}m$ and $126.8\~140.2\;{mu}m$, respectively. The size of freshwater rotifer was larger than that of S-type marine rotifer, but smaller than that of L-type one. Growth and formation of resting egg of B. plicatilis were different among the strains. The maximum density of S-type and L-type rotifer was 753.3 inds./ml for H-S strain and 220 inds./ml for O-L strain, respectively. The largest production of resting egg of S-type and L-type rotifer were 86.7 inds./ml for YY-S strain and 45.8 inds./ml for O-L strain, respectively.

• Journal of Aquaculture
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• v.21 no.2
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• pp.76-81
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• 2008

We investigated the food-effect for ultra-small rotifer Synchaeta kitina cultured under a individual and community by several diets: 3 single trials(Tetraselmis suecica, TET; Isochrysis galbana, ISO; Marine Chlorella ellipsoidea, CHL) and 3 trials with a mixture of 2 species. The rotifer was cultured on the different feeding concentrations. In the individual cultures, the maximum number of offsprings and maximum lifespan of the female investigated to 5.8 inds. and 12.7 days in TET trial, respectively. Values of the developmental phases of the rotifer fed with T. suecica were higher than those of trials without T. suecica. Also it approached faster to maturation level. In the community cultures, the maximum density of TET+CHL trial elevated up to 1,569 inds./mL. But, CHL and ISO showed a poor growth rate and maximum density. The offsprings of the female increased continuously when fed by T. suecica trial, up to $10{\times}10^3$ cells/ind./day. As the quantity of supplied diet was lowered their lifespan were decreased. But, the maximum density and growth rate in the community cultures showed the highest value in the $10{\times}10^3$ cells/ind./day. The efficient food for mass culture of S. kitina was T. suecica, and optimum concentration of their food was 10,000 cells for an individual.