镜湖不同湖区沉积物中轮虫休眠卵萌发的比较研究

实验室内对镜湖沉积物中的轮虫休眠卵进行了萌发,共孵出轮虫47种,隶属于10科19属;其中大湖区沉积物中萌发出的轮虫40种,小湖区41种,两湖区共同种类34种.每毫升大湖区沉积物中休眠卵萌发出的轮虫平均数量为(1.1±0.1)个,显著高于小湖区的(0.4±0.0)个.在两湖区沉积物中,以3种孵化方式所萌发出的平均密度超过4.0ind./200mL的轮虫种类总计有6种,它们是多须伪前翼轮虫(Proalides tentaculates)、裂痕龟纹轮虫(Anuraeopsis fissa)、螺形龟甲轮虫(Keratella cochlearis)、裂足臂尾轮虫(Brachionus diversicornis)、臂三肢轮虫(Filinia brachiata)和萼花臂尾轮虫(Brachionus calyciflorus);其中前三种轮虫为两湖区所共有.共有的3种轮虫的孵出情况在两湖区沉积物间也存在着差异.在小湖区沉积物中,3种孵化方式下孵出的平均密度大于0.05ind./200mL的轮虫属是臂尾轮属、伪前翼轮属、龟甲轮属和龟纹轮属,而大湖区沉积物中孵出的平均密度较高的轮虫属还包括三肢轮属、巨头轮属(Cephalodella)和异尾轮属(Trichocerca);水体营养程度较高的大湖区沉积物中孵出的臂尾轮属、伪前翼轮属和龟甲轮属轮虫的密度均高于营养程度较低的小湖区.     

养鱼池轮虫休眠卵分布和萌发的研究

东北地区部分鱼场养鱼池底泥中轮虫的休眠卵,表层(0—5厘米)数量每平方米为1．2—503万个,个别池塘高达1,573万个,其中完全暴露于泥表面的数量约占1—2％。休眠卵数量差别和池塘环境条件关系密切;各泥层中的轮虫休眠卵数量呈“V”形垂直分布的趋势。萼花臂尾轮虫和角突臂尾轮虫的休眠卵在水温10-40℃;pH4．5-11．5;溶氧0．3毫克／升以上和盐度8．5%以下的条件下可以萌发。10℃为其发育的生物学零度。根据轮虫休眠卵分布和它的环境条件的关系,以及萌发的生态条件,阐述了在养鱼池中增殖轮虫所应采取的措施及其理论根据。     

轮虫休眠卵形成和萌发的生态机理研究进展

休眠卵的形成是单巢目轮虫生殖行为中最显着的特征之一。作为一系列有性生殖过程的产物,休眠卵具有抵抗外界不良环境、易于扩散和通过重组产生遗传多样性等特点。轮虫休眠卯是轮虫集约化培养的重要种源,通过轮虫快速的孤雌生殖在短时间内大量繁殖,使得轮虫作为鲜活饵料为水产经济动物的苗种生产起到了极其重要的作用。但是在生产实践中,利用孤雌生殖批量培养轮虫常会因难以预测的种群突然崩溃而造成水产经济动物苗种生产的重大损失。       

淡水轮虫休眠卵的研究进展

本文综述了温度、休眠卵形态、光照条件和休眠卵贮存条件等因子对轮虫休眠卵萌发的影响, 以及休眠卵萌发型式差异的生态学意义。温度骤变可以诱导休眠卵萌发, 光照条件对休眠卵萌发率的影响存在种间差异, 母体轮虫的食物和休眠卵贮存条件影响其萌发率。     

武汉东湖若干种轮虫休眠卵的形态观察

休眠卵是轮虫在恶劣生态条件下形成的滞育结构。本研究用光学显微镜和扫描电子显微镜对东湖14种轮虫休眠卵形态进行了观察,其中关于尾突臂尾轮虫（Brachionuscaudatus,Barrois＆Daday）、方形臂尾轮虫（Bquadridentatus,hermann）、中型晶囊轮虫（Asplanchnaintermedia,Hudson）、顶生三肢轮虫（Filiniaterminalis,Plate）的休眠卵的形态特征尚未见过报道。这些休眠卵一般卵壳较厚,颜色较深,壳表面有纹饰。不同种轮虫的休眠卵形态、壳饰各不相同,具种的特异性,但在某些轮虫,即使同一种中休眠卵形态有时亦存在较大的差异。     

枯水期鄱阳湖子湖轮虫休眠卵空间分布特征

为了研究枯水期鄱阳湖子湖泊轮虫休眠卵空间分布的差异, 于2015年1月份, 在鄱阳湖南矶山湿地自然保护区的南深湖和白沙湖2个子湖泊进行取样调查。研究发现, 不同生境类型中轮虫休眠卵的密度具有显著差异(P<0.05), 轮虫休眠卵的分布具有明显的梯度性, 在洲滩植被区、泥滩区和积水区中轮虫休眠卵的密度逐渐减少。南深湖植被区中轮虫休眠卵的密度最高, 为(3.34±1.28) ind./cm3, 茭白中密度高达5.45 ind./cm3。不同水生植被生境中轮虫休眠卵的密度趋势为: 挺水植物>洲滩植物>浮叶植物>沉水植物。不同水深区轮虫休眠卵的分布不具有明确的规律性。此外, 研究还发现轮虫休眠卵的密度与底泥的软硬程度具有一定相关性, 泥质越软, 轮虫休眠卵的密度越低。     

萼花臂尾轮虫休眠卵萌发的研究

报道了萼花臂尾轮虫休眠卵的低温贮存时间、萌发温度、光照、孵化液等因子对其萌发的影响．休眠卵萌发率随低温贮存时间的延长而提高,以贮存30～50d作用最显著．在10～30℃温度范围内．萌发率随温度的升高而增加,超过30℃时,萌发率则有所下降．光对休眠卵的萌发是一非必需条件。把休眠卵从不新鲜的孵化液转移到新鲜的孵化液中能刺激其萌发．     

不同培养条件下萼花臂尾轮虫休眠卵的萌发

为确定萼花臂尾轮虫休眠卵的最适形成条件 ,或为提高特定培养条件下形成的休眠卵的萌发率 ,对不同温度、食物、光照和 pH条件下萼花臂尾轮虫形成的休眠卵进行了萌发研究。发现不同培养条件下形成的休眠卵在不同萌发条件下的萌发历时均为实验开始后的第 1～ 7天 ,萌发率高峰均出现在第 1～ 3天。在萌发温度为15℃～ 30℃范围内 ,2 0℃下形成的休眠卵在 2 0℃的萌发温度下累积萌发率最高 ,为 5 2 5 0± 6 89% ;母体以小球藻为食物时 ,其所产休眠卵的平均累积萌发率为 2 7 92 % ,显著大于以斜生栅藻或蛋白核小球藻和斜生栅藻所组成的混合藻为食物时 ;休眠卵形成和萌发时的光照条件对其累积萌发率无显著的影响 ;pH6 5和 7 5条件下形成的休眠卵的累积萌发率较高 ,分别为 32 5 0± 7 0 7%和 38 75± 15 5 3%。本研究和已报道的研究结果表明 :不同培养条件下形成的休眠卵在不同条件下萌发时均呈同步萌发型式 ;2 0℃和pH7 5分别是武汉东湖萼花臂尾轮虫休眠卵形成的最适温度和最适 pH条件。     

环境因子对萼花臂尾轮虫休眠卵萌发率的影响

萼花臂尾轮虫（Ｂｒａｃｈｉｏｕｎｕｓ ｃａｌｙｃｉｆｌｏｒｕｓ Ｐａｌｌａｓ）休眠卵在不同萌发条件下累积萌发率的结果显示,保存在休眠卵形成的原液中,温度为２０℃～３０℃时萌发率均较高,３０℃时用过滤湖水萌发时的萌发率最高（６５％）,保存在无机培养中的休虎卵,用曝气自来水萌发时最主,用湖水次之,无机液萌发效果较差;２０℃和２５℃时三种萌发液中的萌发率接近,母体投喂小球藻形成的休眠卵的累积萌发率高于投     

影响培养轮虫的因素及对策

简述了水生浮动物轮虫的形态结构、繁殖和生活史,以及培养轮虫的意义,阐明了在轮虫的培养中,温度,pH值,饵料的种类及密度,光照,氨和二氧化氮等因素,对轮虫卵和种群生长的影响及其对策,结合当前水产养殖现状,对培养轮虫的发展前景谈了几点想法。     

Hatching of cladoceran resting eggs: temperature and photoperiod

Summary 1. We identified temperature and photoperiod conditions under which the hatching of 45 cladoceran species could be elicited. Identification of appropriate hatching cues is of primary importance for the exploration of the ties between active and diapausing stages.
2. Incubation temperature affected the hatching success of resting eggs isolated from Danish, Belgian/Dutch and Spanish sediments. In general, most hatchlings and species were retrieved at 15 °C. Danish and Belgian/Dutch resting eggs hatched more successfully under a long day photoperiod than in continuous illumination.
3. Most species could be retrieved after incubation of resting eggs isolated from a limited amount of sediment (0.4 kg) under a single, well chosen combination of temperature and photoperiod. Processing additional sediment samples under seven more incubation regimes only allowed detection of 21% (Spain) to 34% (Denmark) more species.
4. The incubation period for resting eggs to hatch was strongly influenced by incubation temperature. Our results show that hatching experiments aimed at assessing cladoceran species richness and conducted at 15 °C should be continued for a period of at least 2 weeks, after which a random subset of hatchlings (e.g. n  = 100) can be selected from the total hatchling assemblage.     

镜湖常见臂尾轮虫(Brachionus)种群周年动态及生活史对策

对镜湖臂尾轮虫种群的周年动态进行了研究,测量和分析了它们的个体大小、卵大小和相对卵大小及其与水温和叶绿素a浓度等生态因子间的关系。结果表明,镜湖常见的7种臂尾轮虫中,仅萼花臂尾轮虫(Brachionus calyciflorus)、角突臂尾轮虫(B.angularis)、裂足臂尾轮虫(B.diversicornis)和剪形臂尾轮虫(B.forficula)的种群密度和出现频率较高;前两者种群密度高峰期均出现在2~3月份,4月份后均较低;后两者种群密度在6~9月份较高,而在10月份后很快下降。除剪形臂尾轮虫外,其它3种臂尾轮虫的个体体积均与水温间具有显著的相关性,平均卵体积均与各自的平均被甲长度呈显著的正相关关系。角突臂尾轮虫和萼花臂尾轮虫个体大小与水体叶绿素a浓度间呈显著的负相关关系,它们的卵体积分别与水温和叶绿素a浓度之间具有显著的负相关性,且水温是影响它们卵体积的主要因子。4种臂尾轮虫中,仅角突臂尾轮虫的相对卵体积与水温间表现出显著的正相关关系。     

Hatching and viability of rotifer diapausing eggs collected from pond sediments

1. Planktonic rotifers inhabiting variable environments produce diapausing eggs that accumulate in the sediment of lakes and ponds, forming egg banks that may withstand adverse periods. A common assumption in zooplankton diapausing egg bank studies is to count as viable all eggs in the sediment that look healthy. This assumption should be challenged by asking how effectively ‘healthy‐looking’ eggs represent viable eggs. 2. In this study, viability of more than 1100 ‘healthy‐looking’ diapausing eggs belonging to the Brachionus plicatilis species complex was assessed in a laboratory hatching experiment. Eggs were collected at different depths from sediment cores obtained from 15 ponds located in coastal and inland areas of Eastern Spain. 3. Only approximately one half of the ‘healthy‐looking’ diapausing eggs hatched after incubation in experimental conditions. Almost all the hatchlings (99.4%) survived to maturity. The proportion of ‘healthy‐looking’ diapausing eggs that hatched varied among areas and among ponds within area, and substantially declined with sediment depth. Most of the hatchlings (88%) were obtained from the uppermost 2 cm of sediment. ‘Healthy‐looking’ eggs from upper sediment layers hatched after significantly shorter incubation times than eggs recovered from deeper layers. 4. Both decreased hatching success and increased incubation time for hatching with sediment depth suggest that older ‘healthy‐looking’ eggs are less responsive to hatching stimuli and could become unviable. However, the strong correlation found between the number of ‘healthy‐looking’ eggs and the number of hatchlings indicates that the abundance of ‘healthy‐looking’ eggs is a good index of egg bank viability.     

镜湖长三肢轮虫的有性生殖

2004年5—11月,对芜湖市镜湖大、小湖区水体中长三肢轮虫(Filinia longiseta)的有性生殖及其与种群密度、水温、水体透明度、水体叶绿素a含量和轮虫总密度等环境因子间的关系进行了研究.结果表明:当水温低于22℃或水体透明度大于一定值(小湖区SD>95cm,大湖区SD>100cm)时,长三肢轮虫不进行有性生殖;而当其本身的种群密度达到一定值(小湖区种群密度>122ind·L-1,大湖区种群密度>113ind·L-1)时才进行有性生殖.长三肢轮虫的混交雌体密度仅与其本身的种群密度以及水体中轮虫总密度之间呈正相关关系(P<0·01),而与水温、叶绿素a含量、水体透明度之间均无明显的相关关系;长三肢轮虫种群的混交率和受精率与水温、水体透明度、叶绿素a含量、轮虫总密度和长三肢轮虫种群密度之间也无明显的相关性.长三肢轮虫的有性生殖发生在种群增长的早期阶段,混交雌体以间断的、多循环的方式产生;最大混交率与最大种群密度同时出现,但最大受精率出现在种群即将消失时.     

A model evaluating the contribution of environmental factors to the production of resting eggs in the rotifer Brachionus plicatilis

The production of resting eggs by the rotifer Brachionus plicatilis was tested at four salinities (9, 18, 27 and 36\%) and six concentrations of the alga Chlorella stigmatophora (0.25, 0.5, 1.0, 2.0, 4.0 and 6.0 × 10⁶ cells ml^–1). The results indicated that resting eggs were produced only at two salinities (9\% and 18\%) and that their number was affected by the amount of food provided. A model consisting of two generalized linear sub-models was built to evaluate the contribution of each of the tested food concentrations at the two salinities. The sub-models were used to distinguish between two different components of resting egg production: one related to the presence or absence of resting egg production, and the other to the number of resting eggs produced, given that production had occurred. Besides indicating the best combination of salinity and food concentration for obtaining large numbers of resting eggs, they revealed the contribution of internal population factors that were not controlled in the course of the experiment. The model identified the positive contribution of the relative number of females to males, and the negative association between high rotifer densities and the production of resting eggs. The results of the present study help in defining the optimal conditions for mass production of resting eggs, which are of potential importance in aquaculture.Deceased, September 1991.     

Daily timing of hatching of a rotifer,Keratella cochlearis

Groups of Keratella cochlearis f. tecta were collected over a complete diel period from a shallow pool. Observed in the laboratory, the hatchings of the field-produced eggs were not significantly periodic.     

镜湖夏秋季节裂足臂尾轮虫卵率变化及影响因素

调查了安徽省芜湖市镜湖中裂足臂尾轮虫的卵率,分析了卵率与种群密度、食物资源、潜在捕食者和竞争者、水温、水体透明度、溶氧、pH以及氨氮浓度等之间的关系。结果表明,大湖区中,裂足臂尾轮虫的卵率在0.095-1.073间变动,均值为0.293;卵率与种群密度和透明度呈显著的负相关(r值分别为-0.346和-0.329),与总叶绿素a含量和直径小于25μm的藻类叶绿素a含量均呈显著的正相关(r值分别为0.457和0.417);异尾轮虫密度对裂足臂尾轮虫卵率的影响具有明显的时滞效应(r=0.382);在晶囊轮虫密度高峰期,其密度是影响卵率的最主要因素(R2=0.5074)。小湖区中,裂足臂尾轮虫的卵率在0.0471-0.5455间变动,均值为0.194;卵率只与总叶绿素a含量呈显著的正相关(r=0.356)。研究结果提示影响裂足臂尾轮虫卵率的因素具有时空异质性。     

上海崇明岛明珠湖轮虫群落结构

根据2008年1-12月上海市崇明岛明珠湖的综合调查资料,分析了明珠湖轮虫的数量分布、群落特征、种类组成、优势种及物种多样性.结果表明：本次调查共鉴定出轮虫27种,隶属于8科11属,优势种包括刺簇多肢轮虫、暗小异尾轮虫、萼花臂尾轮虫、未定名的旋轮属1种和剪形臂尾轮虫;轮虫生物密度的年均值为（1505.42±1304.63） ind·L^-1,生物量年均值为（2.012±2.146） mg·L^-1;明珠湖轮虫的Shannon-Wiener多样性指数、丰富度指数和均匀度指数均较低,优势种的优势度指数较大,反映出明珠湖轮虫群落结构不稳定;其富营养种数/贫营养种数（E/O）的比值为1.61±1.46,臂尾轮虫属（B）种数和异尾轮虫属（T）种数的比值（Q_B/T）为1.23±0.84.影响明珠湖轮虫生态特征分布的主要因子是水温;目前明珠湖水质呈轻度富营养化.     

Magnetic characterization of Daphnia resting eggs

This study characterized the magnetic materials found within Daphnia resting eggs by measuring static magnetization with a superconducting quantum interference device (SQUID) magnetometer, after forming two types of conditions, each of which consists of zero-field cooling (ZFC) and field cooling (FC). Magnetic ions, such as Fe(3+), contained in Daphnia resting eggs existed as (1) paramagnetic and superparamagnetic particles, demonstrated by a magnetization and temperature dependence of the magnetic moments under an applied magnetic field after ZFC and FC, and (2) ferromagnetic particles with definite magnetic moments, the content of which was estimated to be very low, demonstrated by the Moskowitz test. Conventionally, biomagnets have been directly detected by transmission electron microscopes (TEM). As demonstrated in this study, it is possible to nondestructively detect small biomagnets by magnetization measurement, especially after two types of ZFC and FC. This nondestructive method can be applied in detecting biomagnets in complex biological organisms.