Improved performance of an intensive rotifer culture system by using a nitrifying inoculum (ABIL)

Abstract A dense nitrifying culture (ABIL) has been examined for its capacity to stimulate rotifer growth in a labscale culture system. The nitrifiers were applied in different ways. When ABIL was added directly to rotifer batch cultures, it gave rise to significantly higher population densities (factor 1.5–2.5 higher, P  < 0.05). The nitrifiers were subsequently examined for their capacity to enhance the start-up of bioreactors, commonly installed in aquaculture rearing tanks. Of the different carrier materials used in these bioreactors, i.e. CaCO₃, gravel and a PVC matrix (Bionet), CaCO₃ gave by far the best results. In a third set of experiments, effectively nitrifying bioreactor systems were connected to rotifer culture tanks and operated over a period of up to 10 days. It was demonstrated that the ABIL inoculated CaCO₃-based bioreactor allowed excellent rotifer growth reaching rotifer densities up to 5500 rotifers per mL. Moreover, a new system in which the ABIL culture was recirculated through hollow fibres was developed and demonstrated to be effective for supporting rotifer growth up to 3500 rotifers per mL. Overall, the use of the dense nitrifying culture either in seed batch cultures, conventional bioreactors or hollow fibre bioreactor systems in support of rotifer cultures was demonstrated to be effective for improving the water quality and the rotifer growth.     

Lutein enrichment of the rotifer Brachionus sp. using freeze‐dried Muriellopsis sp. cells

Rotifers, used in aquaculture as feed for early larval stages, are poor in carotenoids compared with copepods, the natural most common prey item of marine fish larvae. A minimal sufficient level of carotenoids in fish larvae may be essential for a correct development. The freshwater microalga Muriellopsis sp. has been identified as a potential source of the carotenoid lutein with possible application in aquaculture. Lutein is a potent antioxidant, with potentially beneficial effects as a carotenoid for fish larvae. This study describes the lutein enrichment of the rotifer Brachionus sp. when incubated with homogeneously dispersed suspensions of freeze‐dried, lutein‐rich Muriellopsis sp. in seawater. A short enrichment time (2 or 2.5 h) resulted in a higher lutein content of the rotifers than a long enrichment time (13.5 or 24 h). Although the concentration of lutein in enriched rotifers, 0.06–0.16 mg (g dry weight)^?1 was low compared with its content in Muriellopsis sp. [about 3 mg (g dry weight)^?1], it was in the range reported for natural copepod populations. Therefore, we conclude that freeze‐dried biomass of Muriellopsis sp. can be used to enrich rotifers with lutein, providing an adequate level of this carotenoid for marine fish larvae.     

褶皱臂尾轮虫培养若干问题探讨

本文就轮虫生产性培养过程中接种密度、投饵量、水质、轮虫生长和营养强化等方面的问题进行探讨,认为:接种密度在用单胞藻培养时应为10～30个/ml,用酵母培养时20～50个/ml;酵母投喂量0 3～0 35g/百万,投喂量不宜过大;酵母投喂的轮虫使用前2d最好用单细胞藻类强化。     

Growth hormone-like substance in the rotifer Brachionus plicatilis

ABSTRACT:   A growth hormone (GH)-like substance was extracted from the rotifer Brachionus plicatilis and subsequently purified by gel filtration and ion exchange chromatography. The GH-like substance had a molecular weight of approximately 28 kDa and had cross-reactivity with salmon GH antibody. In vivo bioassay showed a higher intrinsic rate of increase and net reproduction rate of B. plicatilis treated with the GH-like substance.     

轮虫培养过程中生长及环境变化特征分析

通过1000ml烧杯、5L全自动生物反应器、常规的大池（5m^3）以及加处臭氧和生物过滤装置的大池（约5m^3）这四种培养系统,对在轮虫培养过程中轮虫的生长特征,以及pH、溶氧、氨氮及亚硝态氮等水质参数变化特征进行了较系统的探讨,研究结果可为轮虫密度培养工艺及培养系统的优化奠定基础。     

不同饵料对褶皱臂尾轮虫种群生长繁殖的影响↑（*）

用３种饵料、４个组合培养褶皱臂尾轮虫,研究饵料对轮虫种群生长、繁殖的影响。结果表明：用光合细菌和鲜酵母混合为饵组,轮虫的最高培养密度达到了１８２０ｍＬ－１,高于其它３组;轮虫的日平均增殖率为０．４３５１,比光合细菌组和鲜酵母组分别增加了６．４％和２５．０％。对轮虫生长、繁殖有明显的促进作用。     

Low-temperature preservation (at 4 °C) of marine rotifer Brachionus

Mass production of rotifers is essential as live food during the larval rearing season, but a major problem of rotifer culture is unpredictable culture collapse. If mass‐produced rotifers could be kept alive at low temperature for an extended period of time, they could be supplied as live food to cultured marine fish larvae without interruption. Four experiments were performed to test this possibility in six strains of Brachionus plicatilis O. F. Müller and eight strains of Brachionus rotundiformis Tschugunoff. The results showed that: (1) B. rotundiformis strains were less tolerant to 4 °C than B. plicatilis strains. Among the B. rotundiformis strains, the strains known as SS type were the most susceptible and showed the lowest survival. (2) Exchange of culture media during the incubation at 4 °C in B. plicatilis and B. rotundiformis resulted in higher survival than not changing the culture media, but there were no differences in the regression slope with or without changing the culture media. (3) Acclimation at 15 °C for 96 h for B. plicatilis and B. rotundiformis before transfer to 4 °C resulted in higher survival rates than acclimation at 10 °C. (4) The combination of frequent exchange of culture media and acclimation significantly improved the survival of B. plicatilis and B. rotundiformis compared with controls that were maintained at 4 °C without exchange of the culture media. Large‐scale trials using B. plicatilis (Kamiura strain) cultured in 30‐L tanks were conducted in a hatchery at a density of 2000–20 000 individuals mL^?1. Rotifers were transferred directly from 25 °C to 4 °C. About 50% of the rotifers at 20 000 individuals mL^?1 survived after 14 days at 4 °C. These preserved rotifers could be cultured at 20 °C, recovering within 4 days.     

n_3多价不饱和脂肪酸营养强化轮虫技术研究

通过甲酯型，乙酯型，脂肪酸型和甘油酯型化学型式ｎ－３多价不饱和脂肪酸的营养强化饵料对轮虫的营养强化试验，观察了营养强化过程中轮虫生理生态变化，测定了轮虫体内ＥＰＡ，ＤＨＡ的含量。结果表明：不论是哪种化学型式的营养强化饵料，营养强强效果均好于微绿球藻强经对照组，轮虫中ＥＰＡ，ＤＨＡ含量明显提高，并在强化１２ｈ达到最高峰。     

不同脂肪源对褶皱臂尾轮虫脂类和脂肪酸组成的影

以褶皱臂尾轮虫（Brachionus plicatilis)为实验动物并设计不同脂肪源饵料，分别为：面包酵母Saccharomyces cerevisice（对照组），微绿球藻Nannochlorpisis oculata(A)，5%大豆磷脂 5%鱼油 90%面包酵母（C）。结果表明：（1）接受不同脂肪源的轮虫的脂肪酸组成显著不同，尤其是高度不饱和脂肪酸（HUFA，20C）含量存在显著差异，说明饵料中HUFA含量对轮虫体内相应脂肪酸的含量有显著影响。投喂饵料C使轮虫的脂类HUFA水平得到了强化，提高了轮虫的营养价值。（2）轮虫脂类的HUFA水平不仅由饵料中脂类的相应脂肪酸组成决定，而且轮虫脂类HUFA的提高和强化效果与饵料中HUFA的化学形态密切相关。甘油三酯型饵料HUFA的强化轮虫效果高于磷脂型的HUFA。（3）将富含HUFA的鱼油直接添加在干性饵料如面包酵母中，而不是通过对鲁油乳化后直接强化轮虫，同样能取得良好的强化效果，且操作简便、不易污染水质，适用于轮虫的规模生产。     

褶皱臂尾轮虫土池低盐度培育及其脂肪酸营养评价

2003年4～5月利用低盐度(12)河口水在上海崇明进行了轮虫土池培育实验,并对其脂肪酸营养进行了分析和评价。经过33d培养,结果表明,(1)只要管理得当,低盐度、自然水温(平均水温为18.2℃)条件,土池培育轮虫可以实现持续稳定供应,采收时间、每日采收量和亩总产量分别达到28～29d、9.2kg/667m2·d和259kg/667m2,最高密度可达45个/ml;(2)敌害生物和饵料条件是土池培育轮虫持续稳产的关键因素;(3)土池培育轮虫EPA、DHA、AA等HUFA含量高于酵母和微绿球藻培育的轮虫,因此土池培育轮虫的营养价值好,适用于海水苗种培育。     

Comparison of rotifer Brachionus plicatilis as a choice of live feed with dry feed in rearing Coregonus lavaretus fry

This experiment, designed for the first time in the Middle East region to sustain Coregonus lavaretus production, examined the efficacy of a live organism ( Brachionus plicatilis ), an artificial diet (48% crude protein) and a mixed feed for the first 3 month of rearing fry. Nine rearing cages were floated on the surface of a natural pond supplied with hyporheic-zone river water, each containing 150 numbers of white fish fry, where they were treated with each of the three diets in triplicates. The fry were fed eight times daily starting at the onset of exogenous feeding. Results showed that fry utilized live organisms more efficiently than the artificial and mixed diets. Rotifer-fed group consistently showed higher growth rate during the entire experiment. Length increment (29.6 mm), weight gain (572.3 mg) after 12 weeks of feeding were higher ( P  < 0.05) in this group. Also, their mean weekly specific growth rate (4.97% day⁻¹) was the highest and feed conversion rate (2.97) was the lowest among all treatments. Survival rates of the fry declined from 75% to 61.4%, from 74.3 to 45.8% and from 72.7 to 54.5% for live feed, mixed diet and artificial diet, respectively.     

两品系褶皱臂尾轮虫种群增长及投喂河蟹苗效果的研究

采用实验生态学方法对两品系褶皱臂尾轮虫(内蒙品系和盘锦品系)的种群增长和投喂蟹苗的效果进行了比较研究。结果表明,两品系轮虫的种群增长差异不显著,两者平均瞬时增长率分别为0.42 d-1和0.40 d-1。在投喂蟹苗的效果方面,褶皱臂尾轮虫内蒙品系好于盘锦品系。用内蒙品系轮虫投喂的蟹苗,幼体变态至大眼幼体的存活率为71.65%,用盘锦品系轮虫投喂的蟹苗,变态至大眼幼体的存活率为62.50%。     

几种单胞藻对褶皱臂尾轮虫的营养强化研究

利用气相色谱法测定了小球藻、牟氏角毛藻、球等鞭金藻和投喂不同藻类后12h的褶皱臂尾轮虫的脂肪酸含量。试验结果表明,不论是投喂单种藻类还是2种混合藻类,强化后的轮虫其体内的脂肪酸含量均发生了明显变化,其中单链脂肪酸及低度不饱和脂肪酸的含量在投喂前后没有变化,各种脂肪酸的含量界于未强化的轮虫和所投喂的单胞藻饵料含量之间。3种高度不饱和脂肪酸的含量,除了二十二碳六烯酸因在牟氏角毛藻中含量较低,在单独投喂牟氏角毛藻后的轮虫中未检测出外,其余均与其所投喂的单胞藻的脂肪酸一致;轮虫中被检出的3种高度不饱和脂肪酸的含量,在单种藻类试验组中均低于所投喂藻类的含量;在2种藻类混合试验组中界于2种单胞藻含量之间。混合藻类比单种藻类强化轮虫具有更加全面的营养效果。     

Production, disinfection and evaluation for aquaculture applications of rotifer resting eggs from Bohai Bay, P.R. of China

The dynamics of resting egg production of the rotifer Brachionus plicatilis originating from a wild population in the Tanggu Saltworks (P.R. China) was investigated. In the natural environment as well as in semi-controlled rearing conditions an increased resting egg production was noticed with declining food availability. Processed resting eggs had a hatching efficiency of 3 x 10 6 rotifers per gramme irrespective of their origin. Hatching started 22 h after the initiation of incubation and was completed after 36 h. Rotifers obtained from resting eggs could be further cultured on Culture Selco® and enriched with Super Selco®. The fatty acid profile of these rotifers were not divergent from reference rotifers (originating from the Laboratory of Aquaculture and Artemia Reference Centre) demonstrating that this strain was not catabolizing essential fatty acids and could be used for enrichment purposes. Storage of resting eggs at 4°C resulted in a 50% lower hatching after 1 year but remained stable during the next 2 years. The resting eggs used for storage could easily be disinfected without affecting their hatching characteristics. These results indicate that this material could be used as inocula for mass cultures of live food for commercial hatcheries.     

Enhancement of rotifer (Brachionus plicatilis) growth by using terrestrial lactic acid bacteria

One of the pathways for the entry of bacteria, both pathogenic and probiotic, into the larvae of fish hatcheries is via live prey. As a preventive measure against infections, live prey may be cultured, supplementing the food with probiotics. Some lactic acid bacteria (LAB) have been successfully used in the larviculture. In this study, the nutritional effect of seven terrestrial LAB has been studied regarding the growth of the rotifer Brachionus plicatilis. The cultures were carried out without partial renewal of the culture medium, feeding the rotifers on baker's yeast and adding some of the species of bacteria. In all cases, the addition of the bacteria increased both the specific maximum growth rate and the maximum density obtainable in the cultures. However, the best results were obtained with the addition of Lactococcus casei ssp. casei, Pediococcus acidilactici, or Lactobacillus lactis spp lactis. The rates of growth obtained with the individual or joint addition of these three bacteria were 8–13 times greater than those obtained with the control cultures after 4–5 days' culture. In this study, a series of kinetic models has been applied (logistic modified—Gompertz, logistic–logistic, and generalised logistic) which describes the experimental data, obtaining a set of parameters of biological significance which facilitate the optimisation of the use of these bacterial strains in the mass production of rotifers.     

东海原甲藻对褶皱臂尾轮虫实验种群动态的影响

采用生命表方法研究了不同密度东海原甲藻(Prorocentrum donghaiense)对褶皱臂尾轮虫(Brachionus plicatilis)生命周期中各发育阶段历时以及种群增长参数的影响。结果表明：东海原甲藻对褶皱臂尾轮虫的生长发育具有明显的影响,使轮虫的胚胎发育和繁殖前期延长,繁殖期、繁殖后期和平均寿命缩短,产卵量和繁殖率降低。随藻密度的增加,胚胎发育和繁殖前期分别从(18.33±7.26)h和(58.26±3.52)h增加到(24.29±4.86)h和(91.74±15.46)h,而繁殖后期则从(48.86±14.73)h缩短至(22.60±4.80)h。轮虫的净生殖率和内禀增长率均低于对照(P<0.05或P<0.01),反映了赤潮微藻对轮虫种群增长的影响。不同藻密度下轮虫能够维持一定的种群增长。赤潮藻和浮游动物关系的进一步研究对于我们了解其对海洋生态系统的影响和作用机制具有重要意义.