• Journal of Aquaculture
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• v.21 no.1
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• pp.47-53
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• 2008

The purpose of this study was to suggest that selecting method of rotifer with high activity of digestive enzymes for the enrichment effect of rotifer and the increasing of digestive enzymes of fish larvae. the populations assayed the activities of the digestive enzymes were randomly selected out of several population communities cultured with freshwater condensed Chlorella. The relationship with the population density and the growth rate of selected populations was shown to RD=5865 SGR-350.08(P<0.001). The relationships with fecundity of the growth rate and the population density were shown to F=-36.147 SGR+61.652(P<0.05) and F=-0.0085 RD+66.38(P<0.001), respectively. The relationships of the growth rate and the individual activities of digestive enzymes in rotifer were assayed to Amyl=-1.6482 SGR+3.2498(P<0.05), TAP=-0.8115 SGR+1.1361(P<0.001) and TGL+0.0055 SGR+0.0079(P=0.239), respectively. But in TG-lipase was not related significantly with the growth rate. Also the relationships of the fecundity and the individual activities of digestive enzymes in rotifer were shown to Amyl=0.0296 F+1.0981(P<0.001), TAP=0.0252 F+0.0975(P<0.001) and TGL=-6E-06 F+0.0113(P=0.915), respectively. But in TG-lipase was not related significantly with the fecundity. And the relationships with the specific activity of TG-lipase of the fecundity, the growth rate and the population density were TGL=-0.024 F+0.2332(P=0.132), TGL=0.1267 SGR+0.005(P<0.01) and TGL=0.0002 F-0.0594(P<0.001), respectively. In this case, specific activity of TG-lipase was shown the significant relationship with the population density and the growth rate, but it was not related significantly with fecundity. Therefore, Because a population shown the high activity of digestive enzymes for increasing a lipid enrichment effect of a rotifers and receiving the many exogenous digestive enzymes to fish larvae was the population of high fecundity than the population of high rotifer density, to select the population of a high fecundity was suggested to benefit than a high growth rate for fish larvae.

• Journal of Aquaculture
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• v.7 no.4
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• pp.225-237
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• 1994

Survival and growth rates of flounder larvae fed rotifers and Artemia nauplii enriched by various bio-enrichment techniques were investigated. Enriched materials used in the study were $12\omega-yeast$, 2 commercial emulsified oil and microparticulated products. $\omega-yeast$ were added with one kinds of oils (cuttlefish liver oil, sardine oil, Alaska pollock liver oil, linseed oil) at the level of $5\%,\;15\%\;and\;25\%$. The results are as follows: 1. The growth rate of rotifers cultured with $\omega-yeast$ added $15\%$ cuttlefish liver oil was the best among 12 kinds of $\omega-yeast$ and this performance was almost the same with that of rotifers fed on Chlorella. 2. Survival and growth rates of flounder larvae fed on rotifers and Artemia nauplii enriched with $\omega-yeast$ and the other commercial products were higher than that those of larvae cultured with only Chlorella and non-enriched Artemia. The optimum contents of the cuttlefish liver oil in $\omega-yeast$ for rotifers and Artemia enrichment were $15\%\;and\;25\%$, respectively. 3. Optimum enrichment time and supply amount of $\omega-yeast$ for Artemia nauplii were 6 hr., 1.5 g/g cyst, respectively.

• Journal of Aquaculture
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• v.18 no.4
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• pp.245-251
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• 2005

This study was investigated the condition of their maximum activity to assay the enzymes of rotifer, Brachionus rotundiformis의 $\alpha$-amylase, total alkaline Protease, trypsin and TG-lipase activities of rotifer were higher and more sensitive in phosphate-NaOH buffer than Tris-HCl buffer. $\alpha$-amylase, trypsin and TG-lipase activities were appeared the maximum at pH 8.0, and total alkaline protease activity showed the maximum activity at pH 7.0. $\alpha$-amylase activity showed the highest activity at $40^{\circ}C$, and total alkaline protease and trypsin activities were assayed the highest at $55{\~}60^{\circ}C$. However, TG-lipase activity was appeared the highest at $25{\~}30^{\circ}C$. The optimum substrate concentration of enzyme activity of a-amylase, total alkaline protease, rypsin and TG-lipase were $3.5\%$ starch, $\0.6%$ azo-casein, $87.5{\mu}M$ BApNA and 81.2 mM olive oil, respectively. The optimum reaction time of enzyme activity of $\alpha$-amylase, total alkaline protease, trypsin and TG-lipase were increased up to 40, 60, 30 and 25 min., respectively. The data obtained in this study could be used for the digestive enzyme research of rotifer, B. rotundiformis.

• 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.

• Korean Journal of Ecology and Environment
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• v.54 no.4
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• pp.390-397
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• 2021

The time series data of rotifer community focusing on the species number and total density were collected from 29 reservoirs located at Jeonnam Province from 2008 to 2016 quarterly. The reservoirs had similar weather condition during the study period, but their sizes and water qualities were different. To analyze the temporal dynamics of rotifer community, the medians, ranges, outliers and coefficient of variation (CV) value of rotifer species number and abundance were compared. For the temporal trend analysis, time series of each reservoir data were compared and clustered using the dynamic time warping function of the R package "dtwclust". Small-sized reservoirs showed higher variability in rotifer abundance with more frequent outliers than large-sized reservoirs. On the other hand, apparent pattern was not observed for the rotifer species number. For the temporal pattern of rotifer density, COD, phytoplankton abundance fluctuation, and cladoceran abundance fluctuation have been suggested as potential factor affecting the rotifer abundance dynamics.

• The Korean Journal of Ecology
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• v.22 no.6
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• pp.337-342
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• 1999

Rotifer grazing rates in both species and community levels on bacteria and phytoplankton were determined by using representative models (fluorescent beads: 0.75$\mu m$ for bacteria and 10 $\mu m$ for phytoplankton) at biweekly intervals. One-year study at the lower part of the Nakdong River (Mulgum) indicated that the seasonal pattern of rotifer biomass was similar to that of total zooplankton biomass. Total mean biomass of rotifers was significantly higher than that of other groups (rotifers, 148$\pm $327 $\mu g$C/l; cladoceran. 25$\pm 69$$\mu g$C/l; copepodids. 58$\pm 159$$\mu g$C/l). For laboratory grazing experiments. mean specific filtering rate (SFR: $ml\cdot \; l^{-1}\cdot \; day^{-1}$) for rotifers varied from 0.001 to 0.726, and > 90% individuals of rotifer species took up fluorescent microspheres. The high SFRs were achieved by Brachionus angularis, B. calyciflorus, and Filinia longiseta. Community filtering rates (CFRs, $ml\cdot \; l^{-1}\cdot \; day^{-1}$) varied in the range from 2 ~ 1,670. Rotifer filtering rates on phytoplankton were much higher than bacterial filtering rates, especially in the late growing season (May. June, and November). Rotifers appear to be important in transferring both bacterial and phytoplankton carbon to higher trophic levels at the lower Nakdong River.

• 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.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2002.10a
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• pp.199-200
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• 2002

관상어 초기자어 사육은 rotifer 개발 전 단계의 달걀 노른자를 갈아서 먹이는 방법에서 벗어나지 못하고, 반죽사료를 제작하여 공급하는 방식을 취하고 있는 실정이다. 그렇지만, 해산 어류의 자치어는 rotifer의 먹이생물로서의 가치가 밝혀진 이후 종묘생산에 있어서 없어서는 안될 정도로 중요한 위치를 차지하고 있다. 이에 해수산 종묘생산에서는 다양한 연구가 수행되고 있는데, 그 분야로는 먹이공급횟수, rotifer 공급밀도, 배합사료의 이용, 일일 섭식량(Gatesoupe and Robin, 1992) 및 소화시간(복소, 1997)등이 있다. (중략)

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.05a
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• pp.361-362
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• 2001

어류의 초기 먹이생물로 이용되는 rotifer의 배양은 국내에서 대부분 어류종묘를 생산하는 시기는 물론이고 초기먹이생물이 불필요한 시기에도 차기의 잠재적 수요를 위하여 연중 유지되고 있다. 현재와 같은 살아 있는 상태의 rotifer를 분양 또는 공급하는 것은 계속 배양상태를 유지해야 하는 번거로움과 함께 높은 생산원가를 감수해야 하고, 또 수요가 일시에 증가하는 어류 종묘 생산기에는 적기에 필요량을 확보하기가 어려워 수요공급의 불균형을 초래한다. (중략)

• Journal of Marine Bioscience and Biotechnology
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• v.9 no.2
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• pp.30-34
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• 2017

Microorganisms are contained filtered sea water that is why we often observed co-existing copepod species in the large-scale rotifer culture tanks. In this study, we investigated about taxonomical study of co-existing copepods in Brachionus rotifer mass culture tanks of several seafarming centers at Jeju-do and Pusan, Korea by microscope. Also, we counted number of copeods and density in 10 mL of cultured sea water and distinguished growing patterns and sex. As results, we can identified 4 species copepods, 2 species of Tisbe, 1 species of Tigriopus and 1 species of Apocyclops.