• Journal of Aquaculture
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• v.11 no.4
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• pp.565-572
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• 1998

Survival rate of larval red spotted grouper, Epinephelus akaara is very low, because mouth size of the larvae is too small to eat normal sizes of rotifers. In order to enhance larval survival, optimal culture conditions for larvae using different live foods and water temperatures were studied. Bigger live food produced larger size of rotifer, when the rotifer was cultured with three different live foods such as Tetraselmis tetrathele, marine Chlorella and Nannochloris oculata. Also, the size of rotifer produced was temperature-dependent showing that higher water temperature induced smaller rotifer. Survial rate of the larvae increased with the increase of water temperature up to $29{\circ}C$. Also, higher larval survials were found at the food density of 15 to 20 individuals per milliliter. The larvae fed L-type or small individuals of L-type rotifer died all within a week, although the larvae fed S-type or small individuals of S-type one survived successfully during this period. The size of small individuals of S-type rotifer collected through fine net became larger in a few hours within larval culture tank. Survival rate of grouper larvae with initial stocking density of 40 thousands in 6-ton concrete tank was 6.3% in 10 days and 0.2% in 53 days after hatching, respectively. Total length of the larvae reached around 29.5 mm in 53days after hatching.

• 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.

• Journal of Aquaculture
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• v.10 no.2
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• pp.219-225
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• 1997

The growth and size variation of rotifer (Brachionus plicatils) were examined at the various water temepratures ranging form 18 to $36^{\circ}C$, and under continuous light condition. Either Chlorella ellipsoidea or $\omega$-yeast were fed to rotifer as a food organism. Compared to large-type rotifer fed of $\omega$-yeast, those fed on C. ellipsoildea generally showed higher growth at 7th after starting culture under the water temperaure of less than $30^{\circ}C$. Above such temperature, the large-type rotifer fed on $\omega$-yeast showed higher growth rather than those fed on C. ellipsoidea and the maximum cell number reached 1,420 ind./m$\ell$ at $36^{\circ}C$, whereas when the small-type rotifer was fed on $\omega$-teast, its maximum cell number was to be 1,669 ind./m$\ell$at $34^{\circ}C$. The striking decrease in size was found in large-type rotifer which was to be $112.1\mu m$m(initial : 202.0${\mu}{\textrm}{m}$) when they were fed on C. ellipsoidea at $34^{\circ}C$ for 5 days after starting culture. A great increase in size from the initial of 157.0 to $201.3\mu m$mwas show in small-type rotifer fed on $\omega$-yeast at $20^{\circ}C$,for 5 days. The present results demonstrated that size variation of rotifer could be controlled by changing culture temperature.

• 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 Fisheries and Marine Sciences Education
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• v.26 no.6
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• pp.1315-1321
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• 2014

We investigated the optimum salinity and temperature conditions for the mass culture of small rotifer, Proales similis. In the salinity experiment ranging from 1, 5, 10, 15, 20, 25 and 33‰, growth tended to decrease with salinity increase. Most agreeable salinity for rotifer growth was 1‰ in which maximum density and specific growth rate (SGR) were obtained. In the temperature experiments ranging from 15, 20, 25, 30 and $35^{\circ}C$, continuous growth of rotifer populations was found up to $35^{\circ}C$. The highest maximum density (2,060 inds./mL) of rotifer was observed at $25^{\circ}C$ in given temperature regime. Also, the SGR of females showed increasing tendencies with the increase of temperature. These results suggest that the optimum salinity and temperature for mass culture of P. similis may be 1‰ and $25^{\circ}C$, respectively.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.2
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• pp.315-322
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• 2016

This study determined the optimum microalgae species and concentration for growth of small rotifer Proales similis, in community cultures by feeding it several different foods. Four single trials (Tetraselmis suecica, TET; Isochrysis galbana, ISO; Nannochloropsis oculata, NAN; freshwater Chlorella vulgaris, CHL) were conducted at 5 psu and $25^{\circ}C$. The maximum density and specific growth rate (SRG) were highest for rotifer fed CHL reaching 1,075 individuals (inds.)/mL and 0.83 respectively. By contrast, other foods of ISO, NAN and TET resulted in poor growth rates and maximum density. In the freshwater C. vulgaris experiments examining a range of 0.05 to $8.8mg/10^4rotifers$, the growth of rotifer tended to decrease with the amount of supplement. The maximum density and SGR of females was highest at 910 inds./mL and 0.55 respectively, at $0.05mg/10^4rotifers$. These results suggest that the best microalgae species for the culture of P. similis is freshwater C. vulgaris and the optimum concentration is $0.05mg/10^4rotifers$.

• 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.8 no.1
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• pp.59-67
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• 1995

Growth rate, first reproductive age, life span and total offspring numbers were measured to study the effects of water temperature and salinity on the propagation of rotifer, Brachionus plicatilis. Three types of rotifer, Large (L), Small (S) and Thailand Small (TS)-types, were cultured in the $4\times4$ factorial culture conditions with four different salinities (5, 15, 25 and $35\%o$) at each of four different water temperatures (15, 20, 25 and $29^{\circ}C$). The results are as follows; Under the 4 different salinity gradients %$(5\%o,\;15\%o,\;25\%o,\;and\;35\%o)\;at\;29^{\circ}C$, the mean growth rates of L, Sand TS-type were 0.60, 0.84 and 0.96, respectively. The first reproductive age of three types rotifer appeared to be early at high water temperature. The total offspring numbers of the three types were higher at $25^{\circ}C\;and\;29^{\circ}C$, with the maximum value of 28.3 on the average at $29^{\circ}C$ for TS-type, and the minimum value at $15^{\circ}C$ for S-type. Life span decreased with high water temperature and increased with low water temperature. L-type and TS-type rotifer showed the longest life span of 13.5 days on the average at $15^{\circ}C$, and S-type showed shortest 6.2 days on the average at $29^{\circ}C$.

• Journal of Fisheries and Marine Sciences Education
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• v.25 no.5
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• pp.1205-1213
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• 2013

We investigated the optimum salinity and temperature conditions for the mass culture of small rotifer, Keratella sp.. In the salinity experiment ranging from 0-34‰, the population growth of Keratella sp. drastically increased continuously up to 15‰, and then slightly increased over 20‰. Their maximum density reached 1,007 inds./mL at 0‰. A pre-reproductive phase was shorter in low salinity than in high salinity. The highest number of offspring per female (10.2 inds.) and lifespan of the female (10.7 days) were obtained at 0‰, but there were no significant differences compared to those at 5‰. In the temperature experiments ranging from 16-$32^{\circ}C$, the highest maximum density (1,766 inds./mL) was shown at $24^{\circ}C$. The number of offspring per female significantly increased with increasing temperature, and the highest number of offspring per female was 10.4 inds. at $24^{\circ}C$. The lifespan of female increased with decreasing temperature and the longest lifespan was 12.8 days at $16^{\circ}C$.