崇明岛河道纤毛虫原生动物群落结构及对水环境的指示

浮游纤毛虫原生动物是真核微型生物的重要类群,在微食物环中扮演着物质和能量转换的关键角色,可作为水环境质量的指示生物。但传统沉降计数法对纤毛虫的鉴定分辨率较低,常造成多样性被低估。为此本研究在2020年7月2021年5月期间利用可获得更高分类分辨率的定量蛋白银法(QPS),对崇明岛河道浮游纤毛虫的多样性和群落结构进行调查,同时用多元统计方法分析环境因子对其影响,并筛选潜在指示种。结果共检出纤毛虫131种,隶属于3纲11目,其中寡毛目相对丰度最高,是全年优势类群。Shannon-Wiener指数为1.53±0.06(范围为0.16~2.62),Pielou指数为0.75±0.02(范围为0.18~1.00),Margalef指数为1.07±0.06(范围为0.13~2.98),呈现明显的季节变化,与硝酸盐和叶绿素a浓度均呈显著相关。ANOSIM检验发现4个季节的纤毛虫群落结构差异极显著,存在明显演替过程。dbRDA分析显示,营养盐、叶绿素a、溶解氧和降水量是影响全年纤毛虫群落结构变化的主要环境因子,盐度对其无显著影响;而各季节纤毛虫群落结构的异质性也均与水质指标呈显著相关,盐度仅在秋季对纤毛虫群落结构有显著影响。12种纤毛虫对群落结构的累积贡献率达90%以上,以食藻性和杂食性种类为主,它们与富营养化指标显著相关。优势种中奇异海游虫(Pelagostrombidium mirabile)和透明裂隙虫(Rimostrombidium hyalinum)不易受盐度影响,可作为崇明岛水质状况的潜在指示生物。

太湖浮游纤毛虫群落结构及其与环境因子的关系

用定量蛋白银染色法,对太湖浮游纤毛虫进行定性和定量研究,同时用多元统计方法分析生物和非生物因子对其影响。在全湖设置32个点位进行季度采样,共检出117种纤毛虫,隶属于3纲、15目、78属,其中95种鉴定到种的水平。纤毛虫平均丰度27 170个/L(1 500—139 150个/L),平均生物量600.6μg/L(16.7—8736.0μg/L),以寡毛目、前口目、盾纤目、缘毛目和钩刺目为主。优势种包括:浮游藤壶虫、趣尾毛虫、顶口睥睨虫、银灰膜袋虫、水生钟虫复合种、钟形钟虫、杯铃壳虫、双叉弹跳虫、大弹跳虫、短列裂隙虫、小裂隙虫、圆筒状似铃壳虫。纤毛虫群落结构空间异质性较高,丰度上呈现从南向北、从敞水区向沿岸河口区逐渐增加的趋势;北部湖区以小个体的寡毛目、盾纤目、前口目为主,而南部主要以大个体的寡毛目为主;从功能摄食类群上看,北部各点以食菌种类为主,而南部以食藻种类居多。该类群季节变化明显,于夏季出现丰度峰值,生物量是冬、夏季显著高于春、秋季。通过CCA多元分析发现,太湖纤毛虫群落结构差异主要与水体营养水平、桡足类数量和pH值等有关,且在不同季节由不同的环境因子调控。

夏季蓝藻水华期间太湖河口区和敞水区纤毛虫群落组成及水平分布

在太湖北部主要河口区及敞水区域采集纤毛虫样品,并用定量蛋白银法进行分析。河口区设10个采样点,敞水区设14个采样点。调查中共检出3纲15目60属的105种纤毛虫,种类最多的是钩刺目(21种),其次是寡毛目(20种)。纤毛虫优势种及其在河口区和敞水区占总丰度比例分别为:寡毛目的双叉弹跳虫Halteria bifurcate Tamar(12.3%、18.1%)、大弹跳虫H.grandinella Dujardin(12.3%、10.9%)、短列裂隙虫Rimostrombidium brachykinetum Krainer(8.0%、13.4%)、圆筒状似铃壳虫Tintinnopsis cylindrata Kofoid&Campbell(11.8%、4.5%)、盾纤目的银灰膜袋虫Cyclidium glaucoma Müller(3.1%、10.8%)。其他常见种类还有:前口目的趣尾毛虫Urotricha farcta Claparède&Lachmann、寡毛目的杯铃壳虫Codonella cratera Leidy、小裂隙虫R.humile Penard、奇异急游虫Strombidium mirabile Penard、小筒壳虫Tintinnidium pusillum Entz、缘毛目的水生钟虫复合种Vorticella aquadulcis complex和钟形钟虫V.campanula Ehrenberg。河口区和敞水区纤毛虫平均丰度分别为31407 cells/L(范围1 600—80 900 cells/L)和18618 cells/L(范围1225—36000 cells/L),平均生物量分别为1322.6μg/L(范围44.6—3119.7μg/L)和543.6μg/L(范围44.0—1570.4μg/L)。两个区域的优势类群相似,均以寡毛目、前口目、盾纤目和缘毛目为主。但河口区纤毛虫生物多样性(种类丰富度、Simpson多样性指数、Margalef多样性指数、Shannon多样性指数)显著高于敞水区的(P<0.05)。统计分析发现,食藻种类与叶绿素a含量之间无显著相关,而食菌种类的丰度和叶绿素a含量呈显著正相关关系(P<0.001)。由此推测,纤毛虫群落结构的空间差异可能与水华暴发程度有较大关系。

用于浮游纤毛虫定量研究的蛋白银染色法

报导了一种经过改进的用于浮游纤毛虫定量研究的蛋白银染色方法．对不同定量方法所得结果的比较和统计学处理表明：该方法与传统的沉淀法在所得数据上没有差异．与文献报道的定量染色法相比，不仅保留了蛋白银染色法的优点，而且克服了前人方法中的缺陷。

微波辐射加速Bodian蛋白银染色

用微波促进Bodian′s蛋白银染色显示体外培养的神经元及神经突起,大大缩短了孵育的时间,染色过程只需数分钟,方法简便,可达到与常规染色方法相同的结果。

Simultaneous enumeration of diatom,protozoa and meiobenthos from marine sediments using Ludox-QPS method

The Ludox-QPS method is a newly developed technique,which combines the Ludox HS 40 density centrifugation and quantitative protargol stain,to enumerate marine ciliates with good taxonomic resolution.We tested the method for simultaneous enumeration of diatoms,protozoa and meiobenthos and compared its extraction efficiency for meiobenthos with that of the routine Ludox-TM centrifugation and a modified protocol using Ludox HS 40.We conducted the evaluation with a sample size of 8.3 ml each from sandy,muddy-sand and muddy sediments collected from the intertidal area of the Yellow Sea in summer 2006 and spring 2007.The Ludox-QPS method not only produced high extraction efficiencies of 97±1.3% for diatoms and 97.6±0.8% for ciliates,indicating a reliable enumeration for eukaryotic microbenthos,but also produced excellent extraction efficiencies of on average 97.3% for total meiobenthos,97.9% for nematodes and 97.8% for copepods from sands,muddy sands and mud.By contrast,the routine Ludox-TM centrifugation obtained only about 74% of total meiobenthos abundance with one extraction cycle,and the modified Ludox HS 40 centrifugation yielded on average 93% of total meiobenthos:89.4±2.0% from sands,93±4.1% from muddy sands and 97.1±3.0% from mud.Apart from the sediment type,sample volume was another important factor affecting the extraction efficiency for meiobenthos.The extraction rate was increased to about 96.4% when using the same modified Ludox centrifugation for a 4 ml sediment sample.Besides the excellent extraction efficiency,the Ludox-QPS method obtained higher abundances of meiobenthos,in particular nematodes,than the routine Ludox centrifugation,which frequently resulted in an uncertain loss of small meiobenthos during the sieving process.Statistical analyses demonstrated that there were no significant differences between the meiobenthos communities revealed by the Ludox-QPS method and the modified Ludox HS 40 centrifugation,showing the high efficiency of the Ludox-QPS method for simultaneous enumeration of diatom,protozoa and meiobenthos.Moreover,the comparatively high taxonomic resolution of the method,especially for diatoms and ciliates,makes it feasible to investigate microbial ecology at community level.

土壤原生动物研究方法

原生动物是土壤中形态和功能多样性高且占绝对优势的微型真核生物,在维持土壤生产力和生态系统功能上起着重要作用。随着研究方法的不断改进和创新,对土壤原生动物生态功能的认识已逐步加深。但缺乏统一且有效的定量分析方法仍是土壤原生动物生态学研究中的主要问题。本文综述相关的定量、定性以及群落结构与功能的研究方法,并着重介绍新技术方法,包括土壤定量蛋白银法、分子指纹图谱分析、同位素示踪技术,以及环境宏基因组学技术等。

Spatial distribution of planktonic ciliates in the western Pacifc Ocean: along the transect from Shenzhen (China) to Pohnpei (Micronesia)

Planktonic ciliates have been recognized as major consumers of nano-and picoplankton in pelagic ecosystems,playing pivotal roles in the transfer of matter and energy in the microbial loop.However,due to the difculties in identifcation,the species composition of ciliate assemblages,especially for the small,fragile,and naked species that usually dominate the ciliate communities in the oceanic waters,remains largely unknown.In the present study,22 stations along the transect from Shenzhen(China)to Pohnpei(Micronesia)were sampled for the enumeration of picoplankton and nanofagellates.In addition,pigment analysis of major phytoplankton groups along with the measurements of environmental variables including temperature,salinity,and nutrients were also carried out.Ciliates were identifed at species level using quantitative protargol stain to reveal the species composition and their distribution patterns from of-shore to open ocean.Ciliate abundance was positively correlated with phosphate,silicate,and pico-sized pigmented eukaryotes(PPEs),whereas the biomass was closely related with PPEs,heterotrophic nanofagellates,and chlorophytes.The combination of silicate and pigmented nanofagellates was identifed as the major factor driving the ciliate community composition.The close relationship between silicate and ciliate abundance and community structure needs further validation based on more data collected from oceanic waters.Our study showed the necessity of using techniques that can reveal the community composition at higher taxonomic resolutions in future studies on ciliates.