万方数据第21卷第12期生态 学报Vn1.21.No. 122001年12月 ACTAECOLOGICA SINICADec. .2001海洋纤毛虫巨大拟阿脑虫的实验生态学研究N.捕食竞争对种群生长的影响张绍丽,马洪钢,许恒龙,宋微波‘〔青岛海洋大学海水养殖教育部重点实验室.青岛266003)摘要作为系列研究的第四部分,就浦食竞争、食物等因素与海洋纤毛虫一巨大拟阿脑虫戈纤创1,盾纤目)种群生长的关系进行了探讨结果显示单独或棍合培养的纤毛虫对细菌生长均有很强的抑制作用在竟争者存在时巨大拟阿脑虫和扇形游仆虫的种群牛长均受到了不同程度的制约而维待较为稳定的共存状态。实验表明. 45纤类纤毛虫作为高效的食菌者对于维持一个健康的养殖环境具有积极意义关锐词:巨大拟阿脑虫;竟争种群生长;细菌On experimental ecology of the marine ciliate Paranophrys magnaN:effects of competition on population growthZHANG Shao-Li, MA Hong-Gang, XU Heng-Long, SONG Wei-Bo (7h, Key r.-baL tMar-1- of the Ed aca-a ,bf-isiry, Orean (lmversity of Qamgdao,Qrsrgdao 266003, China). Acni Emlogica Sinica2001,21(12):2039-2044Abstract: The scuticociliate Paranophrya magna horror, 1972 is commonly found in av ariety。「rttarmtwatersespecially in mariculiure biotope. The effects of different initial population density, temperaturesalinityand pHon the population growth have been studied using experimental methodsInp11们ousreportsAs the fourth part of this series, the present paper deals with the effects of the competitorhypotrichous ciliate) and food on the population growth of尸aranophrye magna.The experiment was divided into four treatments; 1) the medium without any ciliate as a control,:2the medium inoculated with Paranophrys magna台只Paranophrys-treatment; 3) with Euplutes洲Euplotes-treatment and 4) the medium nioculatedwith both Pa,mamphrvs magna and Enp1wra u,-协mtxmg一treatment). Each treatment was carried out as three independent replicates. All work w-performed m room temperature with initial density of 30 ind. /ml of ciliates. During experiments-, thedensity of cells was recorded periodically with counting slide, while the density of bacteria was uses-dwith the globulimeier. According to the fornmla lank=lnFr I rt. the increasing rate of populaitons wascalculated with regression analysis based on the method of least square.I n control treatment, the population growth turned into exponential growth phase in a few hours dueto high temperature and concentrations of organic, materials. During equilibrium phase the density ofbacteria remained].02,X101 ind. /nil. The medium turned turbid as the density of bacteria was amplifiedI n Paranophrys-treatment. the natural rate of population growth of ciliates was- isgnificantly lowerthan that of bacteria due to shortage of food from 0t o 1 day. As the density of bacteria nicrease小themaximum density of ciliates reached 2. 97X 10' ind, /nd and the natural rate of population growth remained3. 22士()04fi/d after one day. With the increasing of density of ciliates. the growth of bacteria was基金项目:国家自然科学基金(N.. 39970098)及教育部骨干教师基金资助项目・通讯作者收藕日期:2000-07-10:修订日期:2001-02-03作者简介;张绍丽(1976一,.女,山东萃县人.硕十。主要从事原生动物十态学研究万方数据1040生态学报21卷inhibited by ciliates and the density decreased to 6.42X 10' ind. /ml. After the growth of ciliates came intoequilibrium phase. the density of bacteria leveled off steadily at a lower value as 2/3 of that in rentaltreatment.I n Euplotes-treatment. the interrelation of growth between ciliates and bacteria was ismilar to that inParanophr.ys-treatment , however, the density of Euplotes vaunus decreased to a lower value as 1110 ofthat of Parauophrys magna. the maximum value reached 2328 ind. /ml and the natural rate of populationgrowth remained 1. 57士0. 002/d. In the same way as in Parauophrys-treatment, the growth of bacteriawas also inhibited by ciliates.I n mixing一treatment, the growth of the two species of ciliates developed nito the exponential growthphase after 24 hours. During thus phase the increasing of density of Puraucphrys magna lasted for 1 day,then the maximum density reached 900ind. /ml and the natural rate of population growth remained 1. 79-。.(121/d. while the growth of Euplotes menus lasted for 1. 5 about days, then the maximum d<nsityreached]175ind./nil and the naturalrate of population growth increased to 2. 10士0. 046/d. hwaobvious that the density of Euplotesvaaa- remained higher than that of Parauophrys mugsa ir.ihttreatment.I t was revealed that there was adifference between mixing culture and non mixing culture onhtpopulation growth of the two ciliates. The maximum density of the former was only about 3'/-n of that mthe latter (870 vs. 29679 ind. /rol and the natural rate of population growth decreased to about I/2 duringexponential growth phase, while the population growth of Euplotes vaunus was inhibietd at a lower degreeThe natural rates of population growth of the two species ciliates were different among all the treatments(Paraaophrys with single culture>Eupiate, with mixing culture))Parauophryx with mixingculture 户Euplotes with single culture). Compared with control, the population growth of bacteria wereinhi卜iceddifferent degree m other three treatments (mixing treatment)Parauophrys-treatment>Euplot厂vestment ).The results also indicate that the population growth of both ciliated protozoa. Paran叻h- magna andEuplares ,s-ua were inhibited by the ocmpetition and that their densities dropped to a steady and lowerlevel when two species were cultured otgether. 'I he maximum population density and the natural rate ofnicrease during the exponential phase in Paran叻hrys magna was only 870 ind. /ml, .17 9 ind. /ml whennixed with Euplute, rannus while the value, were 29670 led. /ml. 3. 22 ind. /ml when cultured alone. Theresults support the viewpoint that there is a negative correlativity between size and increasing ra.e ofpopulation in cliiate protozoa (Fenchel. 1968).f 'he growth of bacteria was inhibited strongly when ciliates were cultured etiher individually ormixed. The density of bacteria dropped sharply at beginning of exponential growth and decreased ifnally toa lower level during experiments. As effective predators, ciliates used might be very helpful formaintaining the quality of aquiculwre watersKey words: Paranophrys magna; competition; population growth: bacteria文童编号1000-0933(2001)12-2039 06中圈分类号Q959文献标识码A盾纤类纤毛虫是广泛生存于各类水环境、 尤其在富营养化水体中常见多发的原生动物。该类纤毛虫个体较小几普遍以细菌和有机碎屑为食,同时又常常被大型纤毛虫及其他微型浮游动物所摄食,因Ml在M级生产力向较高营养级传递的过程中起着重要的枢纽作用「,】。人们还发现盾纤类的少数种类可兼性寄主在海水养殖体内,而引起宿主的死亡,,」迄今为止,国内外对该类纤毛虫的研究多限于形态分类学描述和一此有关摄食习性等方面的研 万方数据12期张绍丽等:海洋纤毛虫一巨大拟阿脑虫的实验生态学研究‘_0011究.对其种群动力学及生态学功能的了解仍不多有关该类纤毛虫在水体内尤其是高密度的集约化养殖(含育苗〕水体中的功能与作用则在争议之中(但通常被归人危害类群中),而作为食菌者.他们对养殖环境的贞献作用无疑被忽视了因此,探讨其个体及种群生态学对于评估盾纤类纤毛虫在水域生态系中的作用是十分必要的 本研究所涉之巨大拟阿脑虫是一在海水及富营养的养殖水体中较常见的盾纤类纤毛虫在体系列研究的前丫部分中探讨了初始种群密度及食物、温度、盐度及PIl值等环境因子对其种群生长的影响以及纤毛虫对环境胁迫的应答反应等问题。作为系列研究的第四部分.本文就捕食竟争者〔扇形游仆虫)、食物与其种群生长的关系进行了探讨-I材料与方法1. 1纤毛虫种群的维持及驯化培养实验用纤毛虫(巨大拟阿脑虫,尸aranaphryl magna BorTOr.19了2,以下简称拟阿脑虫夕于1998年5月采白青岛郊区一育蟹池,盐度20虫体分离后在室温卜以煮沸消毒海水(盐度2()为培养液建立纯培养,米粒繁殆的细菌为饵料将拟阿脑虫接种于高盐度海水培养液中,以缓慢过渡方式进行驯化,使其在盐度约为30的培养液中 正常生长繁殖。用于与拟阿脑虫共试验的扇形游仆虫(Eup( otr, vanrtas,以下简称游仆虫)采自青岛近郊一对虾育苗场,盐度29}维持培养方法及条件同前。1.2培养液培养用海水经煮沸消毒后用滤纸过滤.盆度”。50m1海水.I」加人15滴25giI的ff肉浸音悬液作为细菌培养基,作为纤毛虫生长繁殖的饵料1-3实验方案实验共设4组见空白对照组(培养液中无纤毛虫)②拟阿脑虫实验组‘培养液一拟阿脑虫〕;(J游仆虫实验组(培养液十游仆虫);粉混合培养实验组(培养液+拟阿脑虫f游仆虫)各实验组中纤毛虫的初始密度均为30 ind. /ml,定期用计数板和血球计数板测定纤毛虫及细菌的种群密度每组分别设3个平行,室温(22'-24C)培养。1.4纤毛虫种群自然增长率的计算方法根据公式InNi- InNo十,t (Ni为经过时间t后的种群密度,N为种群初始密度),增长率以最小二乘法回归分析得出以时间为横坐标,因变量是纤毛虫密度(个体%.U的自然对数,其斜率即种群自然增长率:、,J:2结果空白组细菌的生长情况见图1.由于培养基有机质浓度及培养温度较高以至种群牛长在数小时之内便 迅速进人r指数增长期,平衡期细菌密度约为1.02X 1(1" ind. /ml一个可明显观察到的现象是在3个实验组墙养过程中, 细菌的大量繁m使培f掖首先由清澈变得浑浊随着纤毛虫的活动和摄食,培养液从纤毛虫种群指数增长期的末期〔约Id后〕开始逐渐出现絮状沉淀而重新变得清澈起来拟阿脑虫实验组中纤毛虫及细菌的数量变化见图 2图中显示了前者对后者的明确影响。从其种群生长合曲线可以明显分为3个时期忿停滞期在培养(i -1d畏日.一 叮之内由干其饵料不足种群生长明显低于细菌生长目通。 二咐一一r-一一,z;指数增长期随着细的密度的增加,纤毛虫食物逐勺强 二身石 叶渐丰足.纤毛虫种群在经伪了Id的停滞期之后,迅速‘艾州叶石丫一仆生长繁殖起来最大种群密度高达2. 97X 10' ind. /ml.枯吕曰药拟阿脑虫在这一时期的种群自然增长率为3. 2?士t留钮刀怡祥。046/d:随着纤毛虫数量的增加,对细菌的摄食强度男。z 3 a s 6培养时间CWture irme(a)加大使细菌的生长与对照组相比,尚在指数增长期就被抑制,最大密度仅为6. 42x 10'ind. /ml,相当于对照空白对照组细菌的生长曲线组不足2i3的数W(图3):(3i平衡期iFg. I Gr即纤毛虫种群进人owth -- of hncrena mc .. -,l group万方数据Z0JZ生学报21卷一一一平衡期后.对细菌的摄食强度稳定.细菌的数星也相继稳定下来吕口景日4nr11f ̄巨人拟阿脑虫。云二Pse,ul飞‘Lse于细菌宫品居伪 sed矛0飞口Lse驹,(工 丈 侧1se2佗L加乙se非aoE二 、 0『七忍 枯勺之,L0esse禽即匕..2 熊u尸 合0『厂 ̄dol‘气Lse娜民se /}侧x6} ・ Vxt}A*mHm创崔丫4.se翻‘.0卜 1-口眺七11 宜Jo热 铂‘t留又 籍云 凿利口2月 粗二0只切 t口a召 0R.l5l-iICti11ure itme (d)粗貌。一3 4居CWturebmdd) 图2拟阿脑虫实验组中纤毛虫和细菌的生长曲线 图3拟阿脑虫实验组与空白组细菌数览的变化比较Fi g. 2 Growt h nine n1 eiliare xnd haeteriz Fig. 3 Conipanaon of ba,terl a grc wth betweenm expenmevtal group of P. ;,agnn experimental di" rnmml group游仆虫实验组中, 纤毛虫及细菌数量变化见图刁,两者的关系与前组类似.但游仆虫的个体数量仅为拟阿脑虫的约1/10最大种群密度为2328 ind. /ml种群自然增长率为1. 57士0. f102/d该实验组中对细菌种群牛长的抑制(图5)与拟阿脑虫实验组〔图3)也十分相似。(1月扮:)32050震 ̄扇形游仆虫 吕,知畜 目P (|-oL『, a1澳片lo 川母...心 x若七 |d)刁1;6言210500/侧口℃。『。川d 产|dool引于实脸组‘J知。 ̄侧xJ卜对照组了替吕禽q如丫℃引租怡枯,|引0 as LOL52.20.53.03.54.00思合节日禽昌q习恤。』蜡1.0 1.5 2.0 25 30 3.5培养时间Cnl mre time(d)P翁0.5 培养时间Cw}c time(d)图1游仆虫实验组中纤毛虫和细m的生长曲线图5游仆虫实验组与空白组细菌数1i1的变化比较Fi g. 4 Growt卜carne of cli- and barterizFi g. 5 Comparison of bacrena growth betweenm cxpevmcntal group of E. vanxus expenmental group of E. v,amius and control group 图6及图7显示r混合培养实验组内各纤毛虫及细菌的数量变化,两种纤毛虫均在1d之后进人指效增长期.拟阿脑虫种群在指数增长期持续了id,最大种群密度约为900ind./ml,种群白然增长率为1. 79 I。021/d;游仆虫种群则持续了I- 5d最大种群密度约为1175ind./nd.种群自然增长率为2. 1。二0. 046 Id,此组实验还显示.游仆虫密度始终大于拟阿脑虫为 (班14001月拐 苟1200已勺[1兰石尸一一、吧二 ‘日)』0 1侧01000云招滔节崔.1800 ,睑£d石。t弓 600氏;日uo400 于扇形游仆虫超畜户l苟于巨大拟阿脑虫如七 200性皿昌玄1。兮禽£d0;月2 3 4 5吉子妞。培养时间Culture timed)孟」 4Culture timed)图G混合培养实验组中纤毛虫的生长曲线Fi g. 6 Growth curve of cliiates图Fig混合培养实验组中细菌的生长曲线了 Gr(,wt卜rurvv ofb改della川m experimental group of mixed cultureexpenmental group司mixed ruhure万方数据I2期张绍丽等:海洋纤毛虫—巨大拟阿脑虫的实脸生态学研究氏川八、亏图8和图9分别显示了混合培养组中拟阿脑虫和游仆虫种群牛长情况同单独培养日 」的差异前者的最大种群密度仅为单独培养时的约3涌(870tnd. /m1 ;29670 ind. /ml〕指数增长期的种群白然增长率也比单独培养时卜降了近一半(1.79/d.3.22/d);相对而台游仆虫的种群生长受抑制的程度较小同对照织相比, :,个实验组中细菌的数量均受到不同程度的抑制〔图10),其中在混合培养组中受抑制程度最大,依次为拟阿脑虫和游仆虫实验组。(一‘ ̄勺(三卿一视合培养组}。-又七 0 ̄单独培养组)1 自。二聚合培养组 侧1月祀 马独培莽组髓薄)七侧书知日昌05嘴ao山尽丫禽旧翻勺宕/厂一勺一 ̄‘哥一d,缺嘴0留。邂11巴绷国d0‘。籍1 2 3状0.0一一代一 ̄2于 ̄二二弓二一培养时间Culture time(d)口培养时间C.t nira eme(d) 图8拟阿脑虫实验组与混合招养组中 图9游仆虫实验组与混合培养组中游仆虫的拟阿脑虫的种群生长比较 种群牛长比较 Fig. 8 Cuniperisuo of growth between experimentalFig. 9 Comparison of E. varsnee. growth betweengrunp(,mly尸. dna)g- the group with two apcacaexperimental group(only E. V,-,,, ),,d group with twospecies 在小同实验组中两种纤毛虫的种群自然增长率的比较见图11,大小依次为单独培养的拟阿脑虫(3. 22(1月.唱一(0.046/d)>混合培养组中的游仆虫{2. 10-0. 046/考竺吕d)>混合培养组的拟阿脑虫门.79上。.021/d)>单独L,二o』l。培养的游仆虫((1. 57x0. 002/d)x之)侧贵.3讨论生.『眺目已有研究表明. 纤毛虫在水环境中是细菌最有效耸目粗勺,的摄食者之一’刁’门,纤毛虫与异养鞭毛虫等原生动物界已。d 一起通过取食细的将初级生产力向较高营养级传递培养时间Culture time(d)在污水处理系统中也是利用了纤毛虫对细菌的摄食习图104个实验组中细菌种群生长的比较 性来达到净化污水的目的.同时对细菌的捕食又可防Fig. 10 Comparison of population growth of止细菌种群的之化.从而更有利十提高降解速度「i.n。在bact eria among four experimental groups海水养殖环境中,通常为大家所接受的观点是,一定数量的微生物存在是无害的.但当细菌数量过大时" 1R[1必须加以控制。在生产实践中,这一人为控制表现为在对危险”闹值的主观认定后而(盲目地!)子以大剂量的抗牛素使用。但近年来许多实践又表明,在未经人工千涉的小的闭合环境中{如对虾育苗水体内).特定类群的纤毛虫〔食菌者)的出现往往标志着水体向良好的健康状况转化,而且这种良好的水况往往叮以构成一有益而稳定的状态由十盾纤类大多是嗜污性的. 极易在富营养水体中发展成优势类群,因此长期以来一直被笼统地视为养殖或育苗环境中的危害类群但近年来的研究表明,除极少数兼性寄生种外,绝大多数盾纤类对养殖动物井无明显的“危害”而作为食菌者,盾纤类本身是高效率的食的者,其在多污水休中的繁盛自身足由十水体过富的后发性结果而非导致水休恶化的原因.换言之,食菌类纤毛虫〔包括盾纤类)更可能是促进和维持(而非破坏)水体健康的有益因子。在本研究中, 3个实验组都清楚地表明了这两种纤毛虫对细菌大量繁殖的有效抑制作用由十纤毛虫的摄食,使细菌数量在指数生长期开始不久便急剧下降,而最终维持在一个较低的水平。万方数据Z011本文研究结果支持P ],hcre的报道即纤毛虫的体积与种群增长率呈负相关关系”本实验所用游仆虫一引的虫体为8。一110x52一7印。,拟阿脑虫的体积较小,芝。卜一。侧大小约为46 -100X 14^-42Pm.在单独培养时‘一〔索拟阿脑-山‘x。)£虫的种群自然增长率比游仆虫的要局得多釜』0么.阴本实验同时还揭示r纤毛虫种间的竞争关系。扇 挤}巴簇『形游仆虫在海水生态系,I:是一较易大鳍发生的常见种皿自枯}.类,在与巨大拟阿脑虫的混合培养中,它作为后者的食簿之纤毛虫种群Ciliates population物竞争者而逐渐占据了优势从图8和图11可以看出拟阿脑虫种群的生长同单独培养时相比,受到了很 图I不同纤毛虫种群的种群自然增长率大的抑制.种群自然增长率甚至不及体积比它大许多Fi g. I I Natural rates of -ni ryas, of的游仆虫,在种群数量卜与单独培养时的情况相比更di fferent ciliate populaton,是有大幅的下降(E一P)-E:混合培养组的游仆虫种群Pnpulati,", }d E,anus m mixed culutre: (E) -E单独培养的游仆虫种群 在混合培养实验组巾.巨大拟阿脑虫的种群生长Ctl:a,c popnleuon in ezpcnmcn,al group of P. runn,".,.虽然受到很大抑制,但因体积小,繁殖速度较快,故种(E一Fir-P ,混合培养组的拟阿脑虫种群Pupu1ztmn of群自然增长率仍比扇形游仆虫单独培养时为高。P. magna h: mixed culutre,(P)P:单独培养的拟阴脑虫种群Ciliate: populationm expcnmcmal group成尸由图11结果显不, 扇形游仆虫在竞争者存在的清magna况卜种群自然增长率竞争比单独培养时还高从竞争抑制这角度来看似乎不合理但山图9可看出.游仆虫在单独培养时种群指数增长期持续了约i6h在有拟阿脑虫存在的情况下仅仅待续了2411.因此前者单独培养时在种群数量上远大于混合培养组(2328i,,d. /tnl >l17bipd. /rnl〕可见对有限饵料的竟争对纤毛虫的抑制影响是很明显的。作者认为对于游仆虫在竞争者存在的情况下种群自然增长率比单独培养时高的这一现象,可以视作纤毛虫在索饵竞价条件下的种一适者生存”的策略但目前还无法明了为何此现象在巨大拟阿脑虫没有出现。可能的解释是(I)小同种类纤毛虫的摄食速率有差异,巨人拟阿脑虫的摄食速率可能小于扇形游仆虫,因而在竞争中逐渐失大优势(2)在葡底生活的游仆虫存在时.拟阿脑虫主要是以悬游在水体中的形式存在,而细菌主要丛集在底质卜,饵料的相对股乏限制r拟阿脑虫的繁殖速度。但是,这些假设还有待于进一步的证据来验证参考文献宋微波等.原生动物学专论一青岛:青岛海洋大学出版社1999. 1一8宋微波魏军.二种危害竹纤卜虫的形态学研究.水生生物学报1998.22(4):361'--565.3〕徐奢V).宋微波.海洋贝类几种危害竹纤巨虫的研究中国水产料学,1999.6(2)别一4ir,.31 A C. 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