李 靜, 戴 曦, 孫 穎, 舒婷婷, 劉正文, 陳非洲,*, 盧文軒

(1. 中國(guó)科學(xué)院南京地理與湖泊研究所湖泊與環(huán)境國(guó)家重點(diǎn)實(shí)驗(yàn)室， 南京 210008； 2. 安徽省農(nóng)業(yè)科學(xué)院水產(chǎn)研究所， 合肥 230031)

太湖浮游纖毛蟲(chóng)群落結(jié)構(gòu)及其與環(huán)境因子的關(guān)系

李 靜1,2, 戴 曦1, 孫 穎1, 舒婷婷1, 劉正文1, 陳非洲1,*, 盧文軒2

(1. 中國(guó)科學(xué)院南京地理與湖泊研究所湖泊與環(huán)境國(guó)家重點(diǎn)實(shí)驗(yàn)室， 南京 210008； 2. 安徽省農(nóng)業(yè)科學(xué)院水產(chǎn)研究所， 合肥 230031)

用定量蛋白銀染色法，對(duì)太湖浮游纖毛蟲(chóng)進(jìn)行定性和定量研究，同時(shí)用多元統(tǒng)計(jì)方法分析生物和非生物因子對(duì)其影響。在全湖設(shè)置32個(gè)點(diǎn)位進(jìn)行季度采樣，共檢出117種纖毛蟲(chóng)，隸屬于3綱、15目、78屬，其中95種鑒定到種的水平。纖毛蟲(chóng)平均豐度27 170 個(gè)/L(1 500 — 139 150 個(gè)/L)，平均生物量600.6 μg/L(16.7 — 8736.0 μg/L)，以寡毛目、前口目、盾纖目、緣毛目和鉤刺目為主。優(yōu)勢(shì)種包括：浮游藤壺蟲(chóng)、趣尾毛蟲(chóng)、頂口睥睨蟲(chóng)、銀灰膜袋蟲(chóng)、水生鐘蟲(chóng)復(fù)合種、鐘形鐘蟲(chóng)、杯鈴殼蟲(chóng)、雙叉彈跳蟲(chóng)、大彈跳蟲(chóng)、短列裂隙蟲(chóng)、小裂隙蟲(chóng)、圓筒狀似鈴殼蟲(chóng)。纖毛蟲(chóng)群落結(jié)構(gòu)空間異質(zhì)性較高，豐度上呈現(xiàn)從南向北、從敞水區(qū)向沿岸河口區(qū)逐漸增加的趨勢(shì)；北部湖區(qū)以小個(gè)體的寡毛目、盾纖目、前口目為主，而南部主要以大個(gè)體的寡毛目為主；從功能攝食類群上看，北部各點(diǎn)以食菌種類為主，而南部以食藻種類居多。該類群季節(jié)變化明顯，于夏季出現(xiàn)豐度峰值，生物量是冬、夏季顯著高于春、秋季。通過(guò)CCA多元分析發(fā)現(xiàn)，太湖纖毛蟲(chóng)群落結(jié)構(gòu)差異主要與水體營(yíng)養(yǎng)水平、橈足類數(shù)量和pH值等有關(guān)，且在不同季節(jié)由不同的環(huán)境因子調(diào)控。

定量蛋白銀法；太湖；浮游纖毛蟲(chóng)；生物多樣性；時(shí)空分布；多元分析

因纖毛蟲(chóng)個(gè)體較小而形狀多樣、操作不易、細(xì)胞易破裂等原因，對(duì)其生態(tài)學(xué)研究一直較為欠缺。太湖作為大型富營(yíng)養(yǎng)化淺水湖泊，生境復(fù)雜[5]。鑒于以往對(duì)太湖浮游纖毛蟲(chóng)的生態(tài)學(xué)研究不多[6- 7]，對(duì)太湖浮游纖毛蟲(chóng)的種類組成及其時(shí)空分布知之甚少，本研究首次利用定量蛋白銀法，對(duì)太湖水體中浮游纖毛蟲(chóng)的生物多樣性、群落空間分布格局、季節(jié)性演替規(guī)律及其影響因子進(jìn)行了研究。

1 材料和方法

1.1 點(diǎn)位布置和樣品采集

在太湖共設(shè)置32個(gè)采樣點(diǎn)(圖1)，這采樣點(diǎn)分布在太湖斷面(三縱三橫)和主要入湖河口。分別于2009年2月、5月、8月和11月進(jìn)行取樣，代表太湖冬、春、夏、秋四個(gè)季節(jié)的情況。采樣時(shí)，用2.5升采水器采集表層(水下50 cm)、中層和底層(底泥界面以上50 cm)的混合水。水體透明度用Secchi盤(pán)現(xiàn)場(chǎng)測(cè)定，pH值等指標(biāo)用YSI 6600水質(zhì)分析儀現(xiàn)場(chǎng)測(cè)定。纖毛蟲(chóng)樣品是將1 L混合水倒入白色塑料瓶，用波恩氏液固定(終濃度5%)，靜置48 h，吸去上清液，濃縮至50 mL備用。浮游甲殼動(dòng)物樣品是取混合水7.5 L，用63 μm網(wǎng)過(guò)濾濃縮，用福爾馬林保存(終濃度4%)；輪蟲(chóng)樣品是取混合水1 L，經(jīng)魯哥試劑固定(終濃度1%)沉淀后，吸除上清液，濃縮至50 mL保存。將剩余混合水樣裝入干凈的塑料容器中，放入保溫箱，并盡快帶回實(shí)驗(yàn)室以測(cè)定分析其他水化學(xué)指標(biāo)。

圖1 太湖32個(gè)采樣點(diǎn)位置Fig.1 Location of 32 sampling sites in Lake Taihu

1.2 樣品分析

非生物因子 總磷(TP)、總氮(TN)、硝態(tài)氮(NO3-N)、亞硝態(tài)氮(NO2-N)、氨態(tài)氮(NH4-N)、葉綠素a濃度(Chl a)、總?cè)芙馓?TDC)和總懸浮質(zhì)(TSS)測(cè)定方法參照金相燦和屠清瑛[8]。

生物因子 纖毛蟲(chóng)樣品用定量蛋白銀法[9]處理：從均勻混合的50 mL濃縮樣品中吸取0.5—2 mL不等水樣過(guò)濾，經(jīng)瓊脂包埋、蛋白銀染色、異丙醇和二甲苯梯度脫水、樹(shù)膠封片、風(fēng)干等步驟完成制片。將標(biāo)本置于顯微鏡(Olympus BX51，日本)下觀察，結(jié)合活體觀察結(jié)果進(jìn)行纖毛蟲(chóng)的鑒定分析。其鑒定和食性區(qū)分主要參照Foissner等[10]、Lynn[11]及其它相關(guān)文獻(xiàn)。生物量的計(jì)算主要參照Foissner等[10]，個(gè)別沒(méi)有生物量數(shù)據(jù)的種類則單獨(dú)計(jì)算：挑出一般不少于10只個(gè)體，測(cè)量蟲(chóng)體長(zhǎng)度、寬度和厚度，按照近似幾何體體積計(jì)算公式計(jì)算體積，假定蟲(chóng)體比重為1[12]，從而得出該種類單位個(gè)體平均生物量值。輪蟲(chóng)和浮游甲殼動(dòng)物的鑒定參考王家楫[13]，蔣燮志和堵南山[14]以及沈嘉瑞等[15]，生物量計(jì)算參照Dumont[16]與章宗涉和黃祥飛[12]。除纖毛蟲(chóng)以外的生物和非生物因子數(shù)據(jù)由中國(guó)科學(xué)院太湖湖泊生態(tài)系統(tǒng)研究站提供。

1.3 數(shù)據(jù)分析

用ArcGIS 9.2軟件模擬纖毛蟲(chóng)的空間分布。纖毛蟲(chóng)豐度和生物量差異用獨(dú)立樣本t-檢驗(yàn)以及one-way ANOVA來(lái)分析。利用CANOCO 4.5軟件進(jìn)行CCA分析，分析前將環(huán)境因子數(shù)據(jù)進(jìn)行l(wèi)og10(X+1)轉(zhuǎn)化，使其無(wú)量綱化且提高分布的正態(tài)性。纖毛蟲(chóng)數(shù)據(jù)矩陣由挑出的優(yōu)勢(shì)種組成[17]，分析前進(jìn)行平方根轉(zhuǎn)換，

近年來(lái)，伊犁州食品藥品監(jiān)督管理局堅(jiān)持“四個(gè)最嚴(yán)”，落實(shí)“四有兩責(zé)”，深入推進(jìn)監(jiān)管體制改革，不斷完善監(jiān)管制度機(jī)制，有效加強(qiáng)監(jiān)管能力建設(shè)，各項(xiàng)工作取得了新成效。2015年榮獲自治區(qū)成立60周年慶?；顒?dòng)食品藥品安全保障工作先進(jìn)集體。

2 結(jié)果

2.1 太湖環(huán)境因子

太湖環(huán)境因子時(shí)空差異明顯(表1)?？偟?、總磷、總?cè)芙馓己腿~綠素a含量季節(jié)差異顯著(P<0.05)。從空間來(lái)看，以總氮、總磷和葉綠素a濃度代表營(yíng)養(yǎng)水平，北部高于南部，近河口區(qū)的采樣點(diǎn)一般高于敞水區(qū)?？偟涂偭拙?8號(hào)點(diǎn)最低(總氮1.2 mg/L，總磷0.03 mg/L)，而接近河口的16號(hào)點(diǎn)(總氮5.8 mg/L，總磷0.31 mg/L)和10號(hào)點(diǎn)(總氮5.8 mg/L，總磷0.26 mg/L)均較高?？?cè)芙馓己腿~綠素a含量空間差異顯著(P<0.05)。后生浮游動(dòng)物以輪蟲(chóng)數(shù)量最多，最高達(dá)1 290 個(gè)/L，優(yōu)勢(shì)種有角突臂尾輪蟲(chóng)Brachionusangularis、萼花臂尾輪蟲(chóng)B.calyciflorus、多肢輪屬Polyarthra、螺形龜甲輪蟲(chóng)Keratellacochlearis、矩形龜甲輪蟲(chóng)K.quadrata。輪蟲(chóng)豐度空間差異顯著(P<0.01)，但是季節(jié)差異不明顯。枝角類和橈足類主要分布在竺山灣和梅梁灣，其他點(diǎn)豐度顯著較低(P<0.001)。枝角類于5月和8月大量出現(xiàn)，5月全湖平均豐度為90.9 個(gè)/L，梅梁灣平均豐度達(dá)305 個(gè)/L，以象鼻溞Bosminasp.和盔形溞Daphniagaleata為優(yōu)勢(shì)種；8月全湖枝角類平均豐度為34.8 個(gè)/L，以象鼻溞、角突網(wǎng)紋溞Ceriodaphniacornuta和秀體溞Diaphanosomasp.最多。橈足類在8月豐度最高，平均豐度為35.8 個(gè)/L，4個(gè)月份平均豐度21.1 個(gè)/L，優(yōu)勢(shì)種有中華窄腹劍水蚤L(zhǎng)imnoithonasinensis、湯匙華哲水蚤Sinocalanusdorrii、中劍水蚤Mesocyclopspp.等。

2.2 太湖浮游纖毛蟲(chóng)群落結(jié)構(gòu)

共檢出117種纖毛蟲(chóng)，隸屬于3綱、15目、78屬，其中95種鑒定到種的水平，18種到屬的水平。15個(gè)目分別為：動(dòng)基片綱的鉤刺目、前口目、腎形目、管口目、吸管目、籃管目、側(cè)口目、合膜目、核殘跡目；多膜綱的寡毛目、腹毛目、異毛目；寡膜綱的緣毛目、膜口目和盾纖目。其中食菌、主食藻、營(yíng)混合營(yíng)養(yǎng)種類分別為39、25和15種，雜食和肉食性的分別有11

表1 太湖采樣點(diǎn)四個(gè)季節(jié)理化因子(表中數(shù)值為平均值及其范圍)

和10種；其余17種主要以鞭毛蟲(chóng)或其他資源為食(含食性未明者)。纖毛蟲(chóng)平均豐度和生物量分別為：27 170 個(gè)/L(1 500 — 139 150 個(gè)/L)、600.6 μg/L(16.7 — 8736.0 μg/L)。寡毛目、前口目、盾纖目、緣毛目和鉤刺目最多，其平均豐度占總豐度的比例分別為12 451 個(gè)/L(45.9%)、9 264 個(gè)/L(34.1%)、3209個(gè)/L(11.8%)、975 個(gè)/L(3.6%)、710 個(gè)/L(2.6%)。優(yōu)勢(shì)種主要有：浮游藤壺蟲(chóng)Balanionplanctonicum、小射纖蟲(chóng)Actinobolinasmalli、趣尾毛蟲(chóng)Urotrichafarcta、頂口睥睨蟲(chóng)Askenasiaacrostomia、銀灰膜袋蟲(chóng)Cyclidiumglaucoma、水生鐘蟲(chóng)復(fù)合種Vorticellaaquadulciscomplex、鐘形鐘蟲(chóng)V.campanula、杯鈴殼蟲(chóng)Codonellacratera、雙叉彈跳蟲(chóng)Halteriabifurcata、大彈跳蟲(chóng)H.grandinella、短列裂隙蟲(chóng)Rimostrombidiumbrachykinetum、小裂隙蟲(chóng)R.humile、透明裂隙蟲(chóng)R.hyalinum、湖泊裂隙蟲(chóng)R.lacustris、綠急游蟲(chóng)Strombidiumviride、小筒殼蟲(chóng)Tintinnidiumpusillum、筒殼蟲(chóng)一種Tintinnidiumsp.、圓筒狀似鈴殼蟲(chóng)Tintinnopsiscylindrata、似鈴殼蟲(chóng)一種Tintinnopsissp.。

纖毛蟲(chóng)群落存在明顯的季節(jié)演替，且空間異質(zhì)性較高(圖2—圖4)。豐度上，2、5、8、11月平均值分別為24 925、18 328、45 837、19 589 個(gè)/L， 2月與5、11月的無(wú)顯著差異，三者均顯著低于8月的(P﹤0.05)；生物量上，2、5、8、11月平均值分別為972.0、452.9、715.0、262.5 μg/L，其中2月和8月的顯著高于5月和11月的(P﹤0.05)。2月，北部以小個(gè)體的盾纖目纖毛蟲(chóng)為主，南部以大個(gè)體的寡毛目為主。功能攝食類群上北部以食菌種類為主，如銀灰膜袋蟲(chóng)，而南部以食藻的居多，如圓筒狀似鈴殼蟲(chóng)。5月主要種類是寡毛目和前口目，2月北部占優(yōu)勢(shì)的盾纖類在本月數(shù)量不多。本月以食藻種類為主，營(yíng)混合營(yíng)養(yǎng)的種類，如雙叉彈跳蟲(chóng)也數(shù)量較多。8月以前口目和寡毛目為主，其中浮游藤壺蟲(chóng)占總豐度的20.4%。營(yíng)混合營(yíng)養(yǎng)的雙叉彈跳蟲(chóng)和綠色游跳蟲(chóng)Pelagohalteriaviridis也大量出現(xiàn)。11月豐度分布大致呈現(xiàn)從北向南逐漸減少的趨勢(shì)，最大值在北部近河口的6號(hào)點(diǎn)，該點(diǎn)生物量也最高。寡毛目纖毛蟲(chóng)是全湖各點(diǎn)主要類群，盾纖目在6、10、16、17號(hào)點(diǎn)所占比重較大，而前口目則在以上4點(diǎn)之外的點(diǎn)位大量出現(xiàn)。食菌和食藻種類共同占據(jù)了纖毛蟲(chóng)的大部分，營(yíng)混合營(yíng)養(yǎng)的纖毛蟲(chóng)比例較5月和8月大大降低，其他食性的所占比例均較小。

2.3 太湖浮游纖毛蟲(chóng)群落結(jié)構(gòu)與環(huán)境因子的關(guān)系

利用向前引入法，最終篩選出4個(gè)與2月纖毛蟲(chóng)群落顯著相關(guān)的環(huán)境因子(圖5)。第一軸與總氮、總?cè)芙馓?、硝酸鹽氮、葉綠素a濃度相關(guān)性較高，解釋的物種變異百分?jǐn)?shù)為27.8%，前兩軸共解釋了33.1%；第一軸解釋的物種-環(huán)境關(guān)系變異百分?jǐn)?shù)為71.5%，前兩軸共解釋了85.2%。5月，第一軸與pH值相關(guān)性較高，第二軸與氨態(tài)氮和硝酸鹽氮相關(guān)性較高，而橈足類與第一和第二軸均相近。前兩軸共解釋了物種變異百分?jǐn)?shù)的18.6%，物種-環(huán)境關(guān)系變異百分?jǐn)?shù)的71.8%。與5月類似，8月的浮游纖毛蟲(chóng)群落結(jié)構(gòu)與橈足類、營(yíng)養(yǎng)水平和生境異質(zhì)性(總固體懸浮物)相關(guān)性高。前兩軸共解釋物種變異百分?jǐn)?shù)的23.6%，物種-環(huán)境關(guān)系變異百分?jǐn)?shù)的65.1%。第一軸與亞硝酸鹽氮和總固體懸浮物相關(guān)性較高，而第二軸主要由硝酸鹽氮和橈足類共同負(fù)責(zé)。11月的環(huán)境因子中，總?cè)芙馓己蜆镒泐愶@著影響浮游纖毛蟲(chóng)群落組成，但前兩軸解釋的物種變異數(shù)不足15%，表明本月浮游纖毛蟲(chóng)群落結(jié)構(gòu)由多種因子共同決定。

圖2 2009年太湖浮游纖毛蟲(chóng)豐度時(shí)空分布Fig.2 Spatial and temporal distribution of ciliate abundance in Lake Taihu in 2009

圖3 纖毛蟲(chóng)生物量的時(shí)空分布Fig.3 Spatial and temporal distribution of ciliate biomass

圖4 纖毛蟲(chóng)功能攝食類群時(shí)空分布Fig.4 Spatial and temporal distribution of different functional feeding groups of ciliates

圖5 太湖浮游纖毛蟲(chóng)群落結(jié)構(gòu)與環(huán)境因子的CCA分析圖Fig.5 CCA analysis of relationship between ciliate community structure and explanatory environmental factors in Lake Taihu

3 討論

纖毛蟲(chóng)個(gè)體較小而形狀多變、一些常見(jiàn)種類個(gè)體相似度較高而不易區(qū)分，故鑒定時(shí)多借助各種染色方法。然而染色后的樣品一般無(wú)法再進(jìn)行定性分析。因此，在纖毛蟲(chóng)生態(tài)學(xué)研究中，往往是定性分析和定量分析分別進(jìn)行的。但是這樣不僅耗時(shí)而且得到的數(shù)據(jù)也易出現(xiàn)偏差。定量蛋白銀方法的引入可以同時(shí)滿足定性和定量分析需求[9]。Pfister等[18]利用該法和一系列傳統(tǒng)觀察方法，對(duì)多種淡水浮游原生動(dòng)物做了對(duì)比分析和研究，發(fā)現(xiàn)定量蛋白銀法因其對(duì)豐度的精確估算和對(duì)大多數(shù)種類的準(zhǔn)確鑒定而有著突出優(yōu)勢(shì)。

有研究報(bào)道稱，用氯化汞、Lugol′s液、福爾馬林、戊二醛和Champy-Da Fano分別保存纖毛蟲(chóng)樣品3、6、9個(gè)月后，其總數(shù)量分別減少了7.2%、16.4%、30.7%[19]。由此可見(jiàn)，用傳統(tǒng)的保存方法長(zhǎng)期保存纖毛蟲(chóng)樣品會(huì)造成其豐度和生物量的大量損失，不利于后續(xù)研究。而用定量蛋白銀法，可以及時(shí)將纖毛蟲(chóng)樣品制成標(biāo)本，從而能防止細(xì)胞破裂，達(dá)到長(zhǎng)期完整保存樣品的目的。但是該法也有其不足之處，比如對(duì)累枝蟲(chóng)Epistylis和部分鐘蟲(chóng)Vorticella的物種鑒定時(shí)，結(jié)合顯微鏡活體觀察，往往可取得更快捷有效的結(jié)果。雖然目前在淡水湖泊纖毛蟲(chóng)生態(tài)學(xué)研究中應(yīng)用該法的報(bào)道還不是很多，但因其有上述優(yōu)點(diǎn)，定量蛋白銀法正被越來(lái)越多的原生生物學(xué)家們所采用。

本次調(diào)查中，纖毛蟲(chóng)種類數(shù)和豐度與以往太湖的研究結(jié)果差異較大[6- 7, 20]。究其原因，除采樣范圍、采樣頻次、水體環(huán)境較以往不同外，還可能與分析方法有關(guān)。在染色制片后，發(fā)現(xiàn)了大量的前口類纖毛蟲(chóng)，如浮游藤壺蟲(chóng)和尾毛蟲(chóng)，這些種類在未經(jīng)染色的情況下，在低倍顯微鏡觀察時(shí)易與相似的盾纖類纖毛蟲(chóng)混淆。在這些制片中還發(fā)現(xiàn)了大量個(gè)體較小(小于20 μm)的種類，如短列裂隙蟲(chóng)和雙叉彈跳蟲(chóng)，這些種類在鏡檢時(shí)易被忽略且與屬內(nèi)其他種類易混淆。另外，20世紀(jì)80年代以后，太湖水體富營(yíng)養(yǎng)化加劇，這與纖毛蟲(chóng)豐度的提高可能也有關(guān)系[21]。本研究中太湖浮游纖毛蟲(chóng)豐度和生物量與國(guó)外一些亞熱帶富營(yíng)養(yǎng)湖泊的纖毛蟲(chóng)狀況相近[22- 23]。

寡毛目(如急游蟲(chóng)、俠盜蟲(chóng)、彈跳蟲(chóng))，鉤刺目(如睥睨蟲(chóng)、櫛毛蟲(chóng))和盾纖目(如膜袋蟲(chóng))是淡水湖泊浮游纖毛蟲(chóng)群落的典型優(yōu)勢(shì)類群[24]。一般隨著營(yíng)養(yǎng)水平增加，3個(gè)目纖毛蟲(chóng)數(shù)量均有提高，但是優(yōu)勢(shì)度有明顯變化。寡毛目通常是寡營(yíng)養(yǎng)湖泊中的絕對(duì)優(yōu)勢(shì)種，隨著湖泊營(yíng)養(yǎng)水平提高，盾纖目纖毛蟲(chóng)取代寡毛類成為優(yōu)勢(shì)種[25]。在太湖北部近河口區(qū)，水體營(yíng)養(yǎng)水平相對(duì)較高，該湖區(qū)的盾纖目纖毛蟲(chóng)也相對(duì)較多。鉤刺目纖毛蟲(chóng)優(yōu)勢(shì)度與湖泊營(yíng)養(yǎng)水平無(wú)明顯關(guān)系，可能與水體溫度的季節(jié)變化有關(guān)。另外，在富養(yǎng)化湖泊中，前口目(如尾毛蟲(chóng)，板殼蟲(chóng)，浮游藤壺蟲(chóng))和緣毛目纖毛蟲(chóng)(如鐘蟲(chóng)和累枝蟲(chóng))也是重要的優(yōu)勢(shì)類群[24]。但是本研究中，前口目纖毛蟲(chóng)在營(yíng)養(yǎng)水平過(guò)高的水域中反而數(shù)量降低，這可能與其捕食者的數(shù)量和盾纖目纖毛蟲(chóng)的資源競(jìng)爭(zhēng)有關(guān)[25]。

在寡營(yíng)養(yǎng)湖泊中，纖毛蟲(chóng)最大豐度和生物量一般出現(xiàn)在秋季[24]；中營(yíng)養(yǎng)湖泊中，纖毛蟲(chóng)豐度和生物量一般有兩個(gè)峰值，在溫帶和亞熱帶湖泊中這種峰值一般出現(xiàn)在春季和秋季；而在富養(yǎng)化湖泊中，纖毛蟲(chóng)數(shù)量和生物量峰值一般出現(xiàn)在夏季[26]。太湖各湖區(qū)，浮游纖毛蟲(chóng)數(shù)量和生物量峰值一般也是出現(xiàn)在夏季。很多學(xué)者認(rèn)為這種季節(jié)動(dòng)態(tài)主要是由其食物資源的變動(dòng)造成的[27]。太湖夏、秋季由于水華頻繁暴發(fā)，可食的藻類(主要是隱藻)減少，故而食藻的纖毛蟲(chóng)大量減少；而由于藍(lán)藻碎屑大量存在、細(xì)菌數(shù)量激增等原因，攝食細(xì)菌的、營(yíng)混合營(yíng)養(yǎng)方式的以及其他食性的纖毛蟲(chóng)大大增加[28]。

除食物資源等因素的調(diào)節(jié)作用外，后生浮游動(dòng)物對(duì)纖毛蟲(chóng)群落結(jié)構(gòu)也有很大影響，包括直接的捕食作用、機(jī)械干擾作用和間接的競(jìng)爭(zhēng)作用，而且這些作用因浮游動(dòng)物和纖毛蟲(chóng)種類不同而不同[2, 29- 31]。本次調(diào)查中，橈足類對(duì)纖毛蟲(chóng)有明顯的抑制作用，而輪蟲(chóng)對(duì)纖毛蟲(chóng)則沒(méi)有明顯的作用。在室內(nèi)培養(yǎng)實(shí)驗(yàn)中輪蟲(chóng)可有效捕食大多纖毛蟲(chóng)，但在野外實(shí)驗(yàn)和調(diào)查中很難發(fā)現(xiàn)輪蟲(chóng)對(duì)纖毛蟲(chóng)的捕食控制作用[22]。不管在室內(nèi)培養(yǎng)還是在野外調(diào)查中，均發(fā)現(xiàn)輪蟲(chóng)和纖毛蟲(chóng)存在營(yíng)養(yǎng)競(jìng)爭(zhēng)[32- 33]。McCarthy等[33]在對(duì)太湖的調(diào)查中發(fā)現(xiàn)，因?yàn)楣灿迷孱愂澄镔Y源，纖毛蟲(chóng)和輪蟲(chóng)的總生物量與浮游植物總生物量的比值始終保持相對(duì)一致，這與本研究的結(jié)果一致。與輪蟲(chóng)不同，橈足類對(duì)纖毛蟲(chóng)數(shù)量有絕對(duì)的控制作用[31]。Archbold 和Berger[34]發(fā)現(xiàn)劍水蚤Cyclopsvernalis可以通過(guò)捕食有效控制大彈跳蟲(chóng)的數(shù)量。Hansen[35]也在該湖發(fā)現(xiàn)橈足類對(duì)寡毛類纖毛蟲(chóng)有明顯抑制作用。在本次調(diào)查中未發(fā)現(xiàn)太湖枝角類對(duì)纖毛蟲(chóng)總數(shù)量有明顯的控制作用。這可能是因?yàn)檎{(diào)查期間枝角類以小型種類為主，如盤(pán)腸溞Chydorus和象鼻溞Bosmina，這與前人的工作是相吻合的。例如，Ventel?等[36]，Wickham和Gilbert[37]均發(fā)現(xiàn)富養(yǎng)化湖泊中，小型枝角類不會(huì)抑制纖毛蟲(chóng)生長(zhǎng)速率和數(shù)量。

致謝: 太湖生態(tài)系統(tǒng)監(jiān)測(cè)站提供太湖2009年理化數(shù)據(jù)。呂志均、錢(qián)榮樹(shù)、蔡永久、姚思鵬、于謹(jǐn)磊、章銘協(xié)助采集樣品。中國(guó)科學(xué)院青島海洋研究所代仁海、孟昭翠、李承春和李玉紅在定量蛋白銀制片中提供幫助，特此致謝。

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Community structure of planktonic ciliates and its relationship to environmental variables in Lake Taihu

LI Jing1,2, DAI Xi1, SUN Ying1, SHU Tingting1, LIU Zhengwen1, CHEN Feizhou1,*, LU Wenxuan2

1StateKeyLaboratoryofLakeScienceandEnvironment,NanjingInstituteofGeographyandLimnology,ChineseAcademyofSciences,Nanjing, 210008,China2FisheriesResearchInstituteofAnhuiAcademyofAgriculturalSciences,Hefei, 230031,China

Ciliates, as a keystone microorganism in water bodies, link bacteria and phytoplankton and higher trophic levels. Accurate quantitative assessment of ciliates would lead to better predictions of material and energy flux through planktonic food web in lake systems. Ciliates were quarterly collected in 2009 at 32 sampling sites in shallow eutrophic Lake Taihu, fixed by Bouin′s solution, and stained by quantitative protargol stain (QPS). In this study, the distribution patterns of ciliate community compositions and functional groups were studied. The relationship between the ciliate community compositions and environmental variables including abiotic and biotic parameters was analyzed by canonical correspondence analysis (CCA). In the 128 samples, a total of 117 species belonging to 3 classes, 15 orders and 78 genera were found. Among the functional groups, 39 species are fallen into the bacterivorous group, represented by orders Scuticociliatida, Hymenostomatida, Peritrichida and Colpodida. Algivorous group had 25 species, mostly belonging to oligotrichids. The mixotrophic, omnivorous and predacious groups had 15, 11 and 10 species, respectively. The rest 17 species belong to the group mainly feeding on heterotrophic flagellates or are in the unclear position. The dominant species wereAskenasiaacrostomia,Balanionplanctonicum,Codonellacratera,Cyclidiumglaucoma,Halteriabifurcata,H.grandinella,Rimostrombidiumbrachykinetum,R.humile,Tintinnopsiscylindrata,Urotrichafarcta,Vorticellaaquadulciscomplex andV.campanula. Ciliate abundance ranged from 1 500 to 139 150 cells/L (mean 27 170 cells/L) and biomass from 16.7 to 8736.0 μg/L (mean 600.6 μg/L). Oligotrichids occupied 45.9% of total ciliate abundance, followed by prostomatids (34.1%), scuticociliatids (11.8%), peritrichids (3.6%) and haptorids (2.6%). The ciliate community compositions had a high heterogeneity and seasonal succession. Ciliate abundance was significantly higher in summer (August) than in other seasons. Their biomass was significantly higher in spring and autumn than in winter and summer. Generally, ciliate abundance had an increase tendency from the south part to north part of Lake Taihu, and from the pelagic area to the littoral. The small-sized species belonging to oligotrichids, scuticociliatids and prostomatids dominated the ciliate communities in the north part of Lake Taihu while the meso- and large-bodied oligotrichids species dominated in the south part. Among the functional groups, the mixotrophic taxa accounted for a substantial proportion of the ciliate assemblages in May and August. The bacterivorous and algivorous taxa dominated in the north and south parts of Lake Taihu, respectively. Unlike the above three groups, the omnivorous, predacious and the others groups only constituted a far smaller percentage of the total ciliate abundance. Results from CCA analysis showed that spatial variations of the ciliate community compositions were determined by difference factors among four seasons. The nitrogen, total dissolved carbon and chlorophyllacontent mainly determined the ciliate communities in winter. Copepod, pH, nitrate and ammonium controlled the ciliate communities in spring. The ciliate communities in summer were shaped by copepod, turbidity and dissolved nitrogen, Copepod and total dissolved carbon structured the ciliate communities in autumn. These results illustrated that both the trophic level and predation jointly shaped the ciliate community compositions in Lake Taihu.

quantitative protargol stain; Lake Taihu; ciliated plankton; biodiversity; temporal and spatial distribution; multivariate analysis

國(guó)家自然科學(xué)基金(31170440); 安徽省農(nóng)業(yè)科學(xué)院科技創(chuàng)新團(tuán)隊(duì)建設(shè)(11C0505); 安徽省農(nóng)業(yè)科學(xué)院院長(zhǎng)青年創(chuàng)新基金(13B0528)

2012- 12- 12; 網(wǎng)絡(luò)出版日期:2014- 03- 04

10.5846/stxb201212241852

*通訊作者Corresponding author.E-mail: feizhch@niglas.ac.cn

李靜, 戴曦, 孫穎, 舒婷婷, 劉正文, 陳非洲, 盧文軒.太湖浮游纖毛蟲(chóng)群落結(jié)構(gòu)及其與環(huán)境因子的關(guān)系.生態(tài)學(xué)報(bào),2014,34(16):4672- 4681.

Li J, Dai X, Sun Y, Shu T T, Liu Z W, Chen F Z, Lu W X.Community structure of planktonic ciliates and its relationship to environmental variables in Lake Taihu.Acta Ecologica Sinica,2014,34(16):4672- 4681.