• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.5
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• pp.524-532
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• 2022

We investigated the effects of taurine-enriched rotifers on larval growth and swim bladder inflation of yellowtail Seriola quinqueradiata. Rotifers were enriched with a commercial taurine supplement at two levels (0 and 800 mg/L). The larvae (initial notochord length=3.98±0.24 mm) were fed the enriched rotifers in triplicate from two days post-hatch for five days. The average taurine contents of the taurine non-enriched and enriched rotifers were 0.35±0.01 and 4.77±0.05 mg/g dry matter, respectively. The weight gain and specific growth rate of the fish fed enriched rotifers with the taurine supplement at 800 mg/L significantly improved compared with those of fish fed rotifers without taurine enrichment (P<0.05). The swim bladder inflation rate of larvae fed taurine enriched rotifers significantly (P<0.05). The results of the present study indicate that yellowtail larvae benefit from taurine concentrations compared with those typically reported to feed on non-taurine supplemented rotifers. Furthermore, taurine-enriched food for fish larval effectively improved the growth performance and swim bladder inflation of yellowtail larvae.

• Journal of Species Research
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• v.11 no.3
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• pp.174-179
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• 2022

In this study, we identified two marine synchaetid rotifers, Synchaeta grimpei Remane, 1929 and S. vorax Rousselet, 1902, in Korea, which are the first synchaetid rotifers collected from a marine environment in the country. Prior to this study, all six synchaetids recorded in Korea were collected from freshwater environments. The morphological characteristics of both species are consistent with those recorded in previous studies of each species. Synchaeta grimpei is distinguished from other synchaetid rotifers by its cone-shaped body, wide and flat apical field, indistinct auricles, and long foot with two separated small toes. The morphological characteristics of Korean S. vorax specimens were most similar to the original description of Rousselet (1902), with its slender and cylindrical trunk shape, strongly convex apical field, and short foot with two small, separated toes. The rami of the Korean S. vorax specimen contained one frontal hook and several distinct and large teeth. Here, we provide the morphological diagnoses of the two synchaetid rotifers and the sequences of the partial mitochondrial cytochrome c oxidase subunit I (COI) of the two species.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.6
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• pp.606-613
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• 2003

This study investigated the effects of food type (condensed freshwater Chlorella, dried Chlorella, dried Spirulina, dried Schizochytrium, baker's yeast and $\omega-yeast$) and amount, and supplementation of vitamin $B_{12}$ on the growth of freshwater rotifer (Brachionus calyciflorus) in high density culture. Growth of rotifers fed condensed freshwater Chlorella was the highest and its density ranged $7.65-8.14{\times}10^3\;inds./mL.$ The primary lipid acids of rotifers fed condensed freshwater Chloyella were linoleic and linolenic, and their amount ($\%$ of total fatty acids) were $48.8\%\;and\;26.8\%,$ respectively. This suggests that condensed freshwater Chlorella would be an effective diet for high quality and quantity rotifers, which in turn serve as live food for freshwater fish larvae. Growth rate of rotifers with Chlorella supplementation increased as amount of supplementation increased up to 1.5 and 2.5 mg at 28 and $32^{\circ}C$, respectively. However, undissolved ammonia toxicity and packing volume of Chlorella in culture medium, reached the optimal conditions for the stable and effective cultivation of rotifers when amount of condensed freshwater Chlorella was 1.5 mg in dry weight per 1,000 rotifers at $28^{\circ}C\;and\;32^{\circ}C$ Growth of rotifers in condensed freshwater Chlorella with vitamin $B_{12}$ supplementation was significantly higher than that of rotifers without supplementation. However, no significant difference was found among the different concentrations of vitamin $B_{12}.$ Therefore, vitamin $B_{12}$ could improve the growth of rotifers (B. calyciflorus).

• Fisheries and Aquatic Sciences
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• v.8 no.4
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• pp.235-242
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• 2005

Baker's yeast, Saccharomyces cerevisiae, has been widely used as a food organism for rotifers used in the larval production of marine fish. However, the nutritional value of the yeast is relatively poor compared with that of the marine alga Chlorella. We examined the nutritional value of another yeast, Candida utilis, and whether its food value could be increased through manipulation such as a cell wall treatment. Candida utilis and S. cerevisiae and their manipulated varieties were assessed with regard to the growth and nutrition of the rotifer Brachianus plicatilis. Larvae of the flounder Paralichthys alivaceus were cultured with rotifers fed on the yeast species, and the dietary value of the rotifers for the larvae was examined. Rotifers that were fed C. utilis grew faster than those provided with S. cerevisiae. Rotifers grew slightly faster on manipulated yeast than on non-manipulated yeast varieties. Of the two yeast species, C. utilis had better dietary value for rotifers. Flounder larvae cultured with rotifers that had fed on C. utilis displayed better growth and survival ($\%$) than did those cultured with rotifers that had fed on S. cerevisiae. Although the manipulated variety of C. utilis was better than the non-manipulated variety in terms of rotifer growth, the flounder larvae survived ($\%$) and grew better when they were fed rotifers that had eaten non-manipulated C. utilis. However, the nutritional value of this yeast species was still lower than that of Chlorella.

• Journal of Species Research
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• v.7 no.4
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• pp.333-339
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• 2018

Rotifers collected from Duung and Gyeongpo wetlands in Korea were investigated. Five species belonging to five genera in four families of monogonont rotifers were identified: Cephalodella ventripes (Dixon-Nuttall), Dicranophorus grandis (Ehrenberg), Lecane undulata Hauer, Taphrocampa selenura Gosse, and Testudinella emarginula (Stenroos). All these species are new to the Korean fauna, even though they have very wide or cosmopolitan distributions. The present study is the first report on the genus Taphrocampa Gosse from Korea. The taxonomy and distribution of each new Korean record are briefly discussed here. The diagnostic characteristics, photomicrographs and the deposition of voucher specimen are provided for each new Korean record.

• Animal Systematics, Evolution and Diversity
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• v.12 no.1
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• pp.53-59
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• 1996

The rotifers collected from various terrestrial habitats, such as mosses, lichens, dry detritus and temporary pools after rain were investigated. Five species and/or subspecies in two families of digonont rotifers were identified: Rotaria tardigrada, Macrotrachela quadricornifera quadricornifera, Macrotrachela quadricornifera scutellata, Adineta vaga minor, Adineta steineri. All these are new to Korean fauna. This is the first taxonomic study on the Korean digonont rotifers.

• Fisheries and Aquatic Sciences
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• v.15 no.3
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• pp.209-213
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• 2012

Members of the ciliate group of protozoans are often observed in mass cultures of rotifers. In particular, Euplotes and Vorticella are common contaminating species. In this study, I examined the effect of the ciliates Euplotes sp. and Vorticella sp. on the growth of the rotifer Brachionus rotundiformis by conducting inter-specific and tripartite-specific mixed-culture experiments. The growth of rotifers was suppressed in co-existence with Euplotes sp. compared with monocultures of rotifers. However, Vorticella sp. promoted rotifer growth. Moreover, Vorticella sp. improved the growth of rotifers suppressed by Euplotes sp. contaminants. In 5-L semi-mass cultures of rotifers, growth of the contaminating protozoan Euplotes sp. was heavily suppressed by Vorticella sp. The stable maintenance of the rotifer culture ecosystem can be achieved by manipulating the types of contaminating protozoan species.

• Fisheries and Aquatic Sciences
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• v.8 no.4
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• pp.201-206
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• 2005

Microalgae are widely used for mass culture of the rotifer Brachionus plicatilis in aquaculture. Since the nutritional value of the rotifer is closely related to its food, the nutritional value of its food should be known in detail. Chlorella ellipsoidea and Nannochloris oculata are re­presentative food organisms for rotifers that are easily cultured. Therefore, the nutritional values of these micro algae were examined for ultrasmall, small, and large rotifers and Artemia nauplii. Chlorella ellipsoidea contained seven times more total fatty acids than N. oculata. The three types of rotifer fed N. oculata contained more amino acids than those fed C. ellipsoidea. However, the total fatty acids of the rotifers fed each microalga species differed according to the type of rotifer. Newly hatched Artemia nauplii contained more protein and had a higher dry weight than those fed microalgae for 6 h. As with the rotifers, the Artemia nauplii fed N. oculata contained more protein and amino acids than those fed C. ellipsoidea, while the reverse was true for the total fatty acid content. Our results suggest that N. oculata is a good supply of protein, while C. ellipsoidea is a good source of lipids as food organisms for rotifers and Artemia nauplii in aquaculture.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.1
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• pp.7-12
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• 2004

This study investigated the possibility of salinity acclimation of freshwater rotifers (Brachionus calyciflorus) as live food for sweetfish (Plecoglossus altivelis) larvae, and also examined the optimal salinity for the growth of sweetfish. Freshwater rotifers cultured in 0 and 4 PSU and seawater rotifers (B. rotundiformis) cultured in 33 PSU were supplied to the larvae with four kinds of enrichment material (condensed freshwater Chlorella, $\omega-yeast,$ baker's yeast, Super Selco) and larval growth at 4 PSU was examined. Growth of the freshwater rotifers positively increased from 0 PSU to 6 PSU, but decreased when over 8 PSU was reached. Growth and survival of the sweet fish larvae reared in 0 PSU were significantly lower than those reared in either 4 PSU or 33 PSU. This indicated that the freshwater rotifers (B. calyciflorus) could be used as live food for sweetfish larvae reared in 4 PSU. The body weight of sweetfish larvae fed on freshwater rotifers enriched with Super Selco was the highest at 0.163 mg, but there was no significant difference in survival and body length of the fish fed with the other enrichment materials. The content of n-3 HUFA of the sweetfish larvae fed on the freshwater rotifers enriched with Super Selco and the condensed freshwater Chlorella was higher than that enriched with $\omega-yeast$ and baker's yeast. These results indicated that B. calyciflorus cultured with the condensed freshwater Chlorella could be used for the sweetfish larvae without enrichment, and the most efficient enrichment material for B. calyciflorus is Super Selco.

• Journal of Aquaculture
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• v.11 no.4
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• pp.437-447
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• 1998

In mass production of larval rockfish, Sebastes schlegeli, high mortality had been observed frequently. This may be the consequence of the low nutritional quality of the live feeds used. This experiment was designed to find out a suitable diet for the mass production of rockfish larvae. Three kinds of live feeds were tested ; plutei of sea urchin (Hemicentrotus pulcherrimus), L-type rotifers (Brachionus plicatiilis) and Artemia naupii. The latter two were enriched with ${\omega}$-yeast, Spirulina platensis and Super Selco before feeding to rockfish larvae. The sea urchin plutei caused to poor survival and growth rates for larval rockfish, and therefore, they were not seemed as proper feed for rockfish larvae. Enrichments of rotifers and Artemia nauplii with ${\omega}$-yeast, Spirulina platensis, or Super Selco improved survival and growth rate. But, rotifers enriched with Super Selco resulted in better rockfish larvae survival than those enriched with ${\omega}$-yeast. A sudden increase of mortality occurred around 11 days after birth. In this critical period, a shift feed such as Artemia nauplii had been supplemented with rotifers. After this critical transition period, the moratality gradually decreased by feeding Artemia nauplii enriched with PUFA. Feeding of mixed feed with rotifers and Artemia nauplii resulted in better larval survival and growth than those of each live food alone.