Effect of different densities of live and dead Chlorella vulgaris on the population growth of rotifers Brachionus calyciflorus and Brachionus patulus (Rotifera)

In order to maintain rotifer populations during periods of low algal production, it is necessary to offer alternate diets, some of which include forms of preserved algae. The present work is based on the effect of live and dead Chlorella vulgaris on the population growth of Brachionus calyciflorus and Brachionus patulus. The experimental design consisted of three algal levels (0.5 x 10(6), 1.5 x 10(6) and 4.5 x 10(6) cells ml-1) offered in three forms (living, frozen and heat-killed). The maximal population density values for B. calyciflorus ranged from 55 +/- 1 ind. ml-1 (at 0.5 x 10(6) cells ml-1) to 471 +/- 72 ind. ml-1 (at 4.5 x 10(6) cells ml-1) with live Chlorella, but was much lower (6 +/- 1 to 26 +/- 6 ind. ml-1) with frozen or heat-killed alga under comparable food levels. However, the maximum population density of B. patulus under live or or heat-killed Chlorella was similar at comparable algal levels but when offered frozen algae it was four times less. The highest mean peak population density was 1,277 +/- 83 ind. ml-1 under 4.5 x 10(6) cells ml-1. The rate of population increase for B. calyciflorus varied from 0.50 to 0.79 using live Chlorella, but under comparable conditions, this range was lower (0.21 to 0.31) for B. patulus. Results have been discussed in light of possible application for aquaculture.     

Effect of three food types on the population growth of Brachionus calyciflorus and Brachionus patulus (Rotifera: Brachionidae).

We compared the population growth of B. calyciflorus and B. patulus using the green alga Chlorella vulgaris, baker's yeast Saccharomyces cerevisiae or their mixture in equal proportions as food. Food was offered once every 24 h in two concentrations (low: 1 x 10(6) and high: 3 x 10(6) cells ml-1) separately for each species. The experiments were terminated after 15 days. In general, at any food type or concentration, B. patulus reached a higher population density. A diet of Chlorella alone supported a higher population growth of both rotifer species than yeast alone. B. calyciflorus and B. patulus achieved highest population densities (103 +/- 8 ind. ml-1 and 296 +/- 20 ind. ml-1, respectively) on a diet of Chlorella at 3 x 10(6) cells ml-1. When cultured using the mixture of Chlorella and yeast, the maximal population densities of B. calyciflorus were lower than those grown on Chlorella. Under similar conditions, the maximal abundance values of B. patulus were comparable in both food types. Regardless of food type and density the rate of population increase per day (r) for B. calyciflorus varied from 0.13 +/- 0.03 to 0.63 +/- 0.04. These values for B. patulus ranged from 0.19 +/- 0.01 to 0.37 +/- 0.01. The results indicated that even though Chlorella was a superior food for the tested rotifers, yeast can be effectively used at low concentrations to supplement algal requirements in rotifer culture systems.     

食物种类对萼花臂尾轮虫种群增长率的影响

在短期慢性观测过程中,食物类型可能是造成萼花臂尾轮虫(Brachionuscalyciflorus)种群繁殖率变化的一种原因。共观测了分别单独投喂10种不同绿藻对轮虫种群增长率的影响。为验证藻青菌是藻类饵料(如绿藻Scenedesmus)有价值的佐剂这一假说,还用蓝细菌单独投喂或与斜生栅藻(Scenedesmusobliquus)混合投喂轮虫进行实验观测。结果发现食物种类对萼花臂尾轮虫种群增长率影响显著。斜生栅藻组获得最大种群增长(1.6/d),而Desmodesmus组增长率最低(0.3/d)。以占斜生栅藻组最大增长的百分率来表示,其它几种绿藻组种群增长由高到低依次为:Desmodesmussubspicatus88%,小球藻(Chlorellavulgaris)83%,单壳缝藻(Monoraphidiumminutum)77%,D.quadricauda74%,S.falcatus71%,S.acuminatus69%,S.pectinatus64%,莱茵衣藻(Chlamydomonasreinhardtii)57%,D.abundans19%。轮虫增长率的差异不能用藻类饵料的大小差异来解释。蓝细菌(Microcystisaeruginosa)和(Synechococcuselongates)不论是单独投喂还是与优良藻类饵料(斜生栅藻)混合投喂都对萼花臂尾轮虫种群增长有抑制作用。这种副作用似乎与微囊藻素无关。该结果不支持无毒蓝细菌可作为与其他绿藻饵料配合使用的优良佐剂这一假说。本研究所观察到的生长变化显示了饵料种类对萼花臂尾轮虫种群增长的影响,也预示了对毒性实验结果的影响     

两品系萼花臂尾轮虫摄食强度的比较研究

对广州和芜湖两品系萼花臂尾轮虫的摄食强度及其与食物浓度、食物种类和培养时间之间的关系进行了比较研究.结果表明,食物浓度、食物种类和培养时间均对轮虫滤水率和摄食率有显著影响.两品系轮虫滤水率和摄食率均随培养时间的延长而减小;20 h内,两品系轮虫的总滤水率均与食物浓度呈曲线相关,而两品系轮虫总摄食率均与食物浓度呈直线相关.广州和芜湖两品系轮虫均在以小球藻为食物时有较大的滤水率,分别为0.0029±0.0001和0.0039±0.0008ml·ind.^-1·h^-1;广州品系轮虫以小球藻为食物时的摄食率(0.3992×10⁴±0.00850×⁴ cell·ind.-1·h^-1)显著地大于以栅藻为食物时的摄食率(0.170×⁴±0.0370×⁴ cell·ind.^-1·h^-1),而它们均与以混合藻为食物时的摄食率无显著差异;芜湖品系轮虫摄食率不受食物种类影响.轮虫滤水率和摄食率因食物浓度、食物种类和培养时间的不同而在品系间存在着差异.     

种群起始密度对萼花臂尾轮虫休眠卵形成的影响

应用群体累积培养法,研究了种群起始密度对萼花臂尾轮虫休眠卵的形成及之相关的混交雌体百分率和受精率的影响,结果表明,在连续１１ｄ的培养中,轮虫休眠卵的产量和形成效率以及种群中的平均混交雌体百分率以种群起始密度为１．０－１０．０ｉｎｄ．ｍｌ＾－１组最大,２０．０ｉｎｄ．ｍｌ＾－１组次之,５０．０ｉｎｄ．ｍｌ＾－１组最小,各组间的平均混交雌体受精率则无显著差异,对轮虫休卢卵最大形成效率及其出现的时间以及     

A study of the freshwater rotifer Brachionus calyciflorus in Pekanbaru, Riau, Indonesia

Brachionus calyciflorus is one of freshwaterrotifers found in fish ponds in Pekanbaru, Riau,Indonesia. Its density varied depending on that ofphytoplankton. Maximum of 2.5 ×10³ ind. l^–1 was found in ponds fertilised with animal wastes.The fecundity and population growth of B.calyciflorus was studied. Results indicated that the fecundity of amictic females was higher thanthat of unfertilized mictic females. During their life span, amictic and mictic females produced29.7 and 12.5 eggs per female, respectively. In the mass culture of 500 ml media, the highestdensity of female and male rotifers was 975.8 and 9.6 ind. ml^–1, respectively. During 8 days cultureperiod, they also produced eggs as many as 124.2 ml^–1.Human and animal wastespromoted the growth of phytoplankton as food forrotifers in the pond. A laboratory study confirms this. The best growth of B. calyciflorus at a density of 109 ind. ml^–1 was found at 0.5 g l^–1 of humanexcreta. A high density of B. calyciflorus (542ind. ml^–1) was also found in semi-continuous culturewith chicken excreta.     

在培养基和食料中添加铅和镉对轮虫种群动态的影响

由于工业活动的影响,墨西哥水体环境中的重金属浓度在上升.浮游动物,尤其是轮虫类,由于对环境变化十分敏感而且是淡水中的常见组成部分,因此被广泛用于生态毒理试验以确定水质标准.在不同的胁迫途径下(如通过培养基或食料),重金属的毒性是不同的.在本研究中,通过在轮虫Brachionus rubens的培养基和食料中添加重金属这两种途径,我们评估了镉和铅的效应.对于这两种重金属,均采用将轮虫置于含0.5×106个/ml绿藻的培养基中或每天喂食经5倍于LC50值的金属处理(1,2和4h)的绿藻.对于在培养基中添加镉,使用了三个毒性水平(0.1,0.2和0.4 mg/L),铅的浓度分别为0.005,0.010 和0.015 mg/L.基于LC50的数据,B.rubens对铅的敏感性要比镉高24倍.镉浓度为0.4 mg/L时,培养基中加入镉造成B.rubens的生长趋缓.而喂食经不同时间处理的绿藻后,轮虫的密度随着食料在重金属中处理时间的延长而减小.培养基中或食料中添加铅时,轮虫种群生长的的趋势与在镉处理下的情况类似.随着培养基中重金属浓度的增加,每天种群增长率(r值)会减小.在培养基和食料处理两种不同途径下,r值会在0.33(对照)到0.02 d-1(经重金属处理)间变化[动物学报 51(1)46-52,2005].     

基于 rDNA ITS 1序列探讨臂尾轮属轮虫的系统发生关系

本文通过对剪形臂尾轮虫、矩形臂尾轮虫、十指臂尾轮虫、红臂尾轮虫、角突臂尾轮虫、双棘臂尾轮虫、裂足臂尾轮虫和萼花臂尾轮虫等八种臂尾轮虫rDNAITS 1序列分析,并以西氏晶囊轮虫为外群,使用PAUP和贝叶斯软件分别构建臂尾轮属轮虫系统发生树( MP树、NJ树、ML树和贝叶斯树) ,以探讨臂尾轮属的系统发生关系,并解决其中的一些分类问题。结果表明:本研究所涉及的轮虫rDNAITS 1平均序列差异百分比较高,为29 %;海水和淡水臂尾轮虫被明显分为不同的进化枝;除双棘臂尾轮虫外,在淡水臂尾轮虫中具有三对前棘刺且营附着生活的种类与前棘刺少于三对且营浮游生活的种类聚在不同支系中,这与以形态特征为主所进行的系统发生研究结果基本一致;所有的系统树均支持将十指臂尾轮虫作为一个独立的支系分离出来,裂足臂尾轮虫应归入臂尾轮属。     

Impact of turbulence and turbidity on the grazing rate of the rotifer Brachionus calyciflorus (Pallas)

The impact of turbulence and turbidity on Brachionus calyciflorus grazing rate was determined in short feeding periods (10 min), using labelled Chlorella pyrenoïdosa. The response to water motion of B. calyciflorus depends on it physiological state: the grazing rate of recently fed amictic females stomach green (with one or two eggs) is significantly reduced in agitated environments compared with non-agitated environments. In contrast, the grazing rate of starved amictic females is not reduced by water motion, whatever its velocity (V1=0.18 m s?1 and V2=0.22 m s?1). In the presence of suspended particles (3–6-μm silica beads), a larger reduction in grazing rate is observed in agitated water at any water velocity (V1=0.18 m s?1 or V2=0.22 m s?1), than in stagnant water. A synergy between turbulence and turbidity is unfavourable to feeding of rotifers.     

食物种类和浓度对红臂尾轮虫种群增长、个体大小及卵大小的影响

采用群体累积培养法,研究了藻类食物的种类和浓度对红臂尾轮虫种群增长、个体大小及卵大小的影响．结果表明,藻种类和浓度对红臂尾轮虫种群增长率、个体体积及卵体积均有极显著影响．不同食堕种空中,种群增长率以小球藻组最小,栅藻组最大;个体体积以小球藻组最小,栅藻组和混合藻组问无显著差异．种群增长率(Y,d^-1)与食物浓度(X,×10^6cells·ml^-1)间呈曲线相关,两者间的关系符合方程：y＝-0．0040x^2+0．0409X+0．4471。在所研究的食物浓度范围内,当浓度分别高于或低于6．0×10^cells·m1^-1和3．0×10^6cells·ml^-1时,轮虫个体体积和卵体积均分别呈减小的趋势。     

Minimal algal food requirements in the presence of protozoan prey for the rotifer Brachionus calyciflorus

As recent experiments demonstrated that protozoans support reproductionof the rotifer Brachionus calyciflorus only in the presenceof algal prey, we addressed the question of minimal algal foodrequirements in a mixed diet of algae and protozoans to ensurepositive growth of B. calyciflorus. In numerical response experiments,we determined the algal threshold concentration for zero populationgrowth of B. calyciflorus when feeding on a pure algal dietof Monoraphidium minutum, and on a mixed diet of M. minutumplus the ciliate Coleps sp. Under pure algal and under mixedfood conditions, a minimum amount of 0.3 µg carbon (C)ml^-1 M. minutum was needed to ensure zero population growthof B. calyciflorus. At lower algal concentrations, Coleps sp.was of low nutritional value. However, when offered in conjunctionwith a concentration of 0.8 µg C ml^-1 M. minutum, Colepssp. contributed equally to the reproductive success of B. calyciflorusas compared to a sole M. minutum diet. Overall, Coleps sp. canbe an adequate supplement in the diet of B. calyciflorus ifa sufficient amount of algal prey is available. However, attimes of low phytoplankton biomass, consumption of ciliatesdoes not necessarily confer a reproductive advantage for thisrotifer.     

Combined effects of food level and inoculation density on competition between Brachionus patulus (Rotifera) and the cladocerans Ceriodaphnia dubia and Moina macrocopa

Competition among cladocerans and rotifers is of considerable interest not only due to their close similarity in life history strategies, but also due to the considerable overlap they exhibit in their feeding habits. In tropical waterbodies, several genera of cladocerans, including Ceriodaphnia and Moina occur, simultaneously with rotifers. We tested over a period of 3 weeks the combined effects of food (0.5×10⁶ and 1.5×10⁶ cells ml^–1 of Chlorella) level and rotifer density on the competition between B. patulus and C. dubia and M. macrocopa using population growth experiments. For each cladoceran species we used 30 test jars of 50 ml capacity. The initial density of cladocerans was 0.2 ind ml^–1, while for B. patulus it was either 1 ind ml^–1 or 5 ind ml^–1. Neither the maximal population density nor the rate of population increase (r) of C. dubia was significantly affected by B. patulus. However, for M. macrocopa, both these variables were negatively affected by the rotifers. The combined effects of low food level and high initial density of B. patulus resulted in a 50% reduction in the peak population density of M. macrocopa. The population growth of B. patulus was negatively influenced by the presence of C. dubia and M. macrocopa. The results of the competition experiments conducted in the present study between cladocerans and rotifers suggest the existence of a more complex and delicate interaction than is generally thought.     

不同pH条件下5种臂尾轮虫（Brachionus）的生殖代价

研究了5种臂尾轮虫(萼花臂尾轮虫、方形臂尾轮虫、壶状臂尾轮虫、十指臂尾轮虫和角突臂尾轮虫)在不同pH条件下(pH 5, 6, 7, 8, 9, 10)当前繁殖(mx)与未来存活(lx 1)、未来生殖(mx 1)和残余生殖价(V*x)的相关关系.结果表明,5种臂尾轮虫存活代价的相关系数在初始几个日龄组表现为正相关或负相关,在随后的大部分日龄组中,均表现为负相关,直至整个生命周期.相对于存活代价,5种臂尾轮虫繁殖代价和残余生殖代价的相关系数的变化幅度较大,但整体趋势仍就是大部分呈现负相关.因此可以推断,轮虫在不同pH条件下存在存活代价、繁殖代价和残余生殖代价.mx与lx 1对日龄组的回归分析有100%回归关系显著,mx与mx 1有97%回归关系显著,而mx与V*x有93%回归关系显著.因此推断,轮虫在不同pH条件下存活代价、繁殖代价和残余生殖代价的负相关性随着日龄组的增加而逐步增加.结果还发现,某些种类的轮虫(方形臂尾轮虫、壶状臂尾轮虫和十指臂尾轮虫)在胁迫的pH(酸性或碱性)条件下,其存活代价、繁殖代价和残余生殖代价较适宜pH(中性)条件下更为显著.     

基于rDNA ITS序列分析莲塘湖萼花臂尾轮虫种群遗传结构的季节变化

对采自芜湖市莲塘湖水体中的萼花臂尾轮虫(Brachionus calyciflorus)夏季种群中的30个克隆(S1-S30)和秋季种群中的20个克隆(A1-A20)的rDNA ITS序列进行了分析;以十指臂尾轮虫B.patulus为外群,构建了50个克隆的NJ、MP和ME系统发生树。结果表明:三个系统树均支持将50个克隆分为两个支系;第一支系包括29个夏季采集的单元型(单元型S9除外)和1个秋季采集的单元型A2,第二个支系包括18个秋季采集的单元型(单元型A2除外)和1个夏季采集的单元型S9;两支系间ITS序列差异为5.1%-8.8%;它们应属于两个不同的姐妹种。夏季,莲塘湖水体中的萼花臂尾轮虫种复合体内以第一支系为主构成的姐妹种在相对丰度上占绝对优势,达29/30;而秋季则相反。上述结果表明:浅水湖泊中萼花臂尾轮虫种群密度的季节变动实际上主要在于各姐妹种相对丰度的季节变化;两姐妹种的种群遗传结构季节变化符合重叠模型。     

Population responses and fatty acid profiles of Brachionus calyciflorus (Rotifera) in relation to different thermal regimes

Diurnal temperature fluctuations affect ectothermic species more than endothermic taxa. We tested the effect of three fixed temperatures (20, 25 and 30 °C) and a 24 h variable (20–30 °C) on the population growth and fatty acid profiles of the common rotifer Brachionus calyciflorus. Depending on the temperature treatment, the peak population abundances of B. calyciflorus varied from 65 to 80 ind./ml, the lowest being on variable temperature range. The rate of population increase varied from 0.31 to 0.52 per day, highest being at 30 °C. There was a curvilinear relationship between the population density and the egg ratio (number of eggs/female) in all the tested temperature regimes. The egg ratio was higher (>0.6) for treatments involving fixed temperatures, but for variable temperature regime, the egg ratios were lower (<0.5). Temperature also induced changes in the fatty acid content of B. calyciflorus. While the total saturated fatty acids increased, both mono-unsaturated and poly-unsaturated fatty acids decreased with increasing temperature regime. These results have been interpreted in relation to the role of temperature (both intensity and mode of exposure) on the population growth characteristics of rotifers.     

三种甲壳纲浮游动物与萼花臂尾轮虫的种间关系

为研究隆线溞(Daphnia carinata)、锯缘真剑水蚤(Eucyclops serrulatus)及中华薄壳介(Dolerocypris sinensis)3种甲壳纲动物种群与萼花臂尾轮虫(Brachionus calyciflorus)种群的相互关系,作者分别将其以不同接种密度与萼花臂尾轮虫(接种密度为350 ind/L)进行混合培养。轮虫种群密度增长率自混合培养后的第3或4天开始下降,且随着甲壳纲动物接种密度的增加轮虫种群受到的抑制作用增大。当轮虫接种密度为350 ind/L时,3种甲壳纲动物的种群变化有所不同:(1)当隆线溞起始密度低于150 ind/L时,其种群生长受到轮虫的明显抑制;而当隆线溞起始密度达到350 ind/L时,其在混合培养与单独培养下的种群变化基本一致,这表明轮虫对隆线溞种群生长无抑制作用。(2)与隆线溞不同,锯缘真剑水蚤和中华薄壳介在混合培养下的种群数量持续增长。但与锯缘真剑水蚤相比,中华薄壳介在混合培养下的种群增长速度较慢。     

五种淡水轮虫种群增长参数的比较研究

在32℃培养条件下,实验研究了5种淡水常见浮游轮虫的种群增长参数。通过编制生命表计算其内禀增长率rm(h-1)、净生殖力(R0)和世代时间T(h)分别为:萼花臂尾轮虫-0.091、14.1和34.1;壶状臂尾轮虫-0.055、6.9和38.4;角突臂尾轮虫-0.035、4.9和50.9;臂尾水轮虫-0.038、4.3和46.1以及裂足臂尾轮虫-0.017、2.1和43.7。其中,萼花臂尾轮虫内禀增长率大,繁殖率高,可作为批量培养的首选种类。       

A model approach to the population dynamics of the rotifer Brachionus rubens in two-stage chemostat culture

Summary A model, based on energy-flow considerations, is presented which describes the population dynamics of Brachionus rubens in the second stage of a two-stage algalrotifer chemostat. The rotifers are foodlimited with substrate-inhibition occurring at high algal densities. The model shows two stable states: steady state with constant density of rotifers and washout of the animals. Which one of the stable states is reached depends on the initial conditions.Empirical data are in general agreement with the model. Deviations may be explained by the fact that the data underlying the model calculations are based on a different food alga (Chlorella vulgaris) than the one used in the experiments (Monoraphidium minutum).The observed population growth rate reaches a maximum value of 0.84 (1/day) at algal densities of 3–4. 10⁶ cells/ml. It decreases at higher algal densities. The egg ratio is related linearily to algal density without being reduced at high algal densities.This study is dedicated to the memory of Prof. Dr. Udo Halbach     

基于16S rDNA序列探讨十种臂尾轮虫的系统关系和分类地位

通过对角突臂尾轮虫、尾突臂尾轮虫、裂足臂尾轮虫、剪形臂尾轮虫、方形臂尾轮虫、壶状臂尾轮虫、红臂尾轮虫、镰肜臂尾轮虫、萼花臂尾轮虫和十指臂尾轮虫等十种臂尾轮虫和大肚须足轮虫的线粒体16s rDNA进行扩增和序列测序,结合Genebank 中十指臂尾轮虫的16S rDNA序列,使用MAGE软件构建了NJ(neighbor-joining method)树,使用mrbayes软件构建了贝叶斯树,探讨了十种臂尾轮虫之间的系统关系.结果表明,本研究所涉及的轮虫16S rDNA序列差异百分比均值为14.6%,可作为分子标记应用于轮虫属内种间系统关系研究;系统树均支持将十指臂尾轮虫、裂足臂尾轮虫隶属于臂尾轮属;壶状臂尾轮虫和红臂尾轮虫是两个独立的种.此外,还依据16S rDNA序列变异百分比推测了十种臂尾轮虫的分化时间.     

Population growth rates of two closely related rotifer species: effects of food quantity, particle size, and nutritional quality

SUMMARY. 1. The relationship between population growth rates and the concentrations of several algal species was determined in laboratory experiments with the rotifers Brachionus rubens and B. calyciflorus .
2. The effects of food quantity were well described by a modified Monod model with a threshold for zero population growth. The model parameters depended on particle size and nutritional quality of the food algae. Differences between the rotifer species were significant and reflected their varying food-size preferences.
3. For each rotifer species, thresholds were lowest for algae in the most readily ingested size range. The lowest thresholds were 0.07–0.09 mgC 1⁻¹ with algae of about 5 μm equivalent spherical diameter (ESD) for B. rubens , and 0.19 mgC 1⁻¹ with algae of about 10 μm ESD for B. calyciflorus .
4. Maximal growth rates ( r _max) were slightly below 0.8 day⁻¹ for both rotifers with most algal species. The highest r _max values for both rotifers were observed when Cyclotella meneghiniana was provided as food. With this alga, B. calyciflorus had a significantly higher r_max (1.02 day⁻¹) than B. rubens (0.838 day⁻¹).
5. From a comparison of the relationship between growth rates and ingestion rates, Chlamydomonas reinhardii appeared to be of low nutritional quality for B. rubens .
6. Egg ratios were related to growth rate and were not influenced by the algal food used. Egg development times and average mortality rates were estimated from the relationship between egg ratio and growth rate. B. calyciflorus appeared to have a high average mortality rate (0.383 day⁻¹) compared to B. rubens (0.083 day⁻¹).