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。     

河口近海桡足类休眠卵生态学研究进展

桡足类是水域生态系统的关键类群,在物质循环、能量流动和信息传递中起着重要作用.休眠卵是桡足类的重要生存策略,在抵抗不利环境、维持种群延续等方面起着重要作用.本文综述了河口近海桡足类休眠卵种类组成及其分布、休眠卵存活时间、休眠卵萌发率和沉积物中休眠卵丰度以及对水体的潜在补充量及其影响因素等.对河口近海桡足类休眠卵生态学研究提出了展望,以期为相关研究提供新的思路.     

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.     

珠江口桂山岛海域桡足类休眠卵对浮游种群的潜在补充及其影响因素

于2011年7月和2012年8月分2个航次采集珠江口桂山岛海域表层沉积物,首次研究珠江口海域桡足类的休眠卵潜在补充量。结果显示:该海域桡足类休眠卵呈不均匀分布,2011年7月沉积物休眠卵潜在补充量介于1.7×105—1.0×107卵/m3之间,平均值为2.1×106卵/m3;2012年8月沉积物休眠卵潜在补充量介于8.9×104—4.3×106卵/m3之间。呈现防波堤外深水区防波堤内养殖区防波堤外浅水区的分布格局。统计分析显示桡足类休眠卵潜在补充量和沉积物含水率呈极显著正相关(P0.01),和水深呈显著正相关(P0.05),表明水深和沉积物含水量是影响桡足类休眠卵潜在补充量的重要因素。休眠卵不同冷藏时间萌发结果发现:萌发持续时间介于10—36d之间,休眠卵萌发类型均为同步萌发型。萌发休眠卵种类为刺尾纺锤水蚤(Acartia spinicauda)和瘦尾胸刺水蚤(Centropages tenuiremis),表明沉积物中休眠卵是上述两种桡足类水体种群的重要补充。筛绢网孔径50—200μm之间休眠卵萌发量占总萌发量的93%,表明采用50μm和200μm筛绢网来分离桡足类休眠卵具有较好的代表性。     

新安江水域(屯溪段)轮虫的种群增长研究

应用群体培养法对采自新安江水域(屯溪段)的萼花臂尾轮虫在4种不同温度(15℃、20℃、25℃和30℃)下的种群动态进行研究。结果表明,温度对轮虫的种群增长率和休眠卵产量均有显著影响(P<0.05)。随着培养温度的升高,轮虫的种群增长率逐渐增大;休眠卵产量在15℃时最小,其余温度下无显著差异。轮虫的总雌体密度在25℃最大,15℃最小;4温度下,雄体和产雄卵的混交雌体的生产量15℃下最小,25℃下最大;而产休眠卵的混交雌体的生产量在15℃下最小,20℃下最大。温度对轮虫的平均混交雌体百分率和平均混交雌体受精率均无显著影响。     

Subgeneric differences in head shield and ephippia ultrastructure within the genus Bosmina Baird (Crustacea,Cladocera)

Seven samples of roach (Rutilus rutilus L.) fromthe Austrian section of the Danube river, the Drauriver and lake Wallersee were examined to studypossible population genetic effects of anthropogenichabitat modification and subdivision. Geneticvariability was assessed using electrophoreticvariation of 11 enzyme systems coded by 14 gene loci.Genetic variation of roach was remarkably high, andwas mainly located within samples while differencesbetween them were weak. Morphometric analyses ofconventional external measurements revealedconsiderable morphological variation within samples.Significant differences between samples mainlyinvolved body depth and fin size, but did not allowadaptive ecomorphological interpretations in severalcases. The comparison of morphological and geneticvariation showed no significant correlations but waslimited by the narrow range of heterozygosityestimates.     

河南南阳不同生境土壤重金属含量及其对拟水狼蛛生物学特性的影响

为了探明重金属含量对拟水狼蛛Pirata subpiraticus生物学特性的影响, 本研究于2008年7月在河南南阳地区5种不同生境下, 共采集50份土壤样本和150头拟水狼蛛样本, 采用原子吸收光谱法测定了5种不同生境下雌拟水狼蛛体内重金属含量, 并测定了雌蛛头胸甲宽、体重、卵袋重量、卵数目和卵体积等生物学指标。结果表明：不同样点拟水狼蛛重金属含量与土壤重金属含量显著正相关, 4个重金属污染区与宝天曼自然保护区（Baotianman, BTM）拟水狼蛛体内Cd、Cu和Zn的含量差异极显著(P<0.001), 桐柏铜矿（Tongbai Tongkuang, TBTK）和南阳油田(Nanyang Youtian, NYYT) 的Pb含量与BTM的差异极显著(P<0.001), 主成分分析表明Cd、Cu和Zn是反应重金属污染的主要指标。在重金属胁迫下, 4个重金属污染区与保护区的拟水狼蛛头胸甲宽、雌体重量、卵袋重量、卵数目和卵体积差异均达到极显著（P<0.001）或显著水平（P<0.05）, 主成分分析表明背胸甲宽、卵袋重量和卵体积是重要生物学指标。 拟水狼蛛的背胸甲宽、卵袋重量和卵的体积与重金属含量显著相关, 重金属含量高的地方拟水狼蛛背胸甲宽较小, 雌性体重、卵袋重量和卵数目较小, 卵的体积大, 因此说明拟水狼蛛处在逆环境中时, 动物为保持总的繁殖力不变的前提下, 后代个体的大小与数目间满足某种平衡, 即达到协同进化的目的, 拟水狼蛛可以作为重金属污染的监测指示生物。     

Preservation of resting eggs of the euryhaline rotifer Brachionus plicatilis O. F. Müller by canning

Recent research has indicated that the hatchability of mass-producedrotifer (Brachionus plicatilis) resting eggs (stored in sea water in thedark at 4°C) gradually decreases due to bacterialinfection of the porous egg surface. We investigated whether lyophilizationas well as a canning treatment could solve the problem of bacterialinfection of resting eggs. The canning method preserves eggs in a dry form,after lyophilization at –40°C. The resting eggs werepacked in cans under various pressures: 21, 34, 48, 61, 75, 88 and 101 kPa.The viability of the canned resting eggs was tested by hatching experimentsdone 6 and 12 months after canning and storage at 5°C.When partial pressures were less than 88 kPa, percent hatching after 6months ranged between 16 and 20%, similar to that of uncanned eggs(19% hatching), but significantly lower (9 and 11%, P <0.01) at 88 and 101 kpa. Even after 12 months, percent hatching remained at35% when canning was at 61 kpa. Lyophilization and canning at partialpressure lower than 88 kPa could therefore preserve resting eggs, andhatchability was maintained. Canned eggs that were treated with NaClO (1 mgl^–1) or NFS-Na (5 mg l^–1) showed a significantlyhigher percent hatching (68% and 80%, respectively, each P<0.05) than untreated eggs.     

镜湖沉积物中轮虫休眠卵的原位萌发

将2004年春季采于芜湖市镜湖的沉积物样品在不同季节进行原位萌发发现,除冬季未见有轮虫孵出外,其余3个季节共孵出轮虫39种,隶属于7科19属;大湖区每200ml沉积物中休眠卵萌发出的轮虫数量平均为212.2个±48.9个,显著高于小湖区的39.1个±10.3个。大湖区沉积物在夏季萌发出的小巨头轮虫(Cephalodella exigua)、大肚须足轮虫(Euchlanis dilatata)和壶状臂尾轮虫(Brachionus urceolaris)、秋季萌发出的裂足臂尾轮虫(B.diversicornis)和角突臂尾轮虫(B.angularis)以及春季萌发出的暗小异尾轮虫(Trichocerca pusilla)和等刺异尾轮虫(T.similis)分别占各季节总萌发数的51.1%、19.7%、15.7%、14.7%、11.1%、38.4%和23.7%,小湖区沉积物在夏季萌发出的多须伪前翼轮虫(Proalides tentaculates)和暗小异尾轮虫、秋季萌发出的裂痕龟纹轮虫(Anuraeopsis fissa)、尖趾单趾轮虫(Monostyla closterocerca)和大肚须足轮虫以及春季萌发出的尖趾单趾轮虫、盘状鞍甲轮虫(Lepadella patella)和暗小异尾轮虫分别占各季节总萌发数的53.9%、31.6%、18%、17%、13%、31%、24.1%和17.2%。各季节萌发出的轮虫与同季节水体中存在的轮虫种类及数量间存在的较大差异表明,那些常年存在于水体中的轮虫所产的休眠卵的萌发对其种群增长的直接贡献可能不大;而那些每年都要从水体中消失一段时间的轮虫所产的休眠卵的萌发在其种群重建中的作用可能因种类的不同而异。     

Population dynamics of Bythotrephes cederstroemii in south-east Lake Michigan 1995–1998

1. Population characteristics (density, size, reproductive patterns) of the predatory cladoceran Bythotrephes cederstroemii in south-east Lake Michigan were monitored at an offshore station (110 m) in 1995–98 and at a nearshore station (45 m) in 1997–98.
2. The mean density of B. cederstroemii at the offshore station was generally highest in July–September (145–914 m⁻²) and at the nearshore station in October–November (168–1625 m⁻²). In 1995 and 1998, density was also high at the offshore station in November (211–284 m⁻²). Fish predation may limit B. cederstroemii in nearshore regions in the summer. The maximum annual densities of B. cederstroemii for 1995–98 were generally similar to those reported from the late 1980s, when the species arrived in Lake Michigan.
3. Body size increased rapidly each year to a maximum in August. Thereafter, body size declined and converged for stage-2 and 3 individuals, suggesting food scarcity or size-selective fish predation was affecting large individuals.
4. Most reproduction occurred asexually (90%), and by stage 2 or 3 females (99%). Asexual brood size was highest when B. cederstroemii first appeared each year, and decreased in August, when larger neonates were produced. There appeared to be differences in reproductive mode for stage 2 and 3 females, with a higher percentage of stage 2 females reproducing sexually.     

斜生栅藻密度对新安江萼花臂尾轮虫种群动态的影响

以浓度分别为1.0×106、2.0×106、4.0×106和8.0×106cells·mL-1的斜生栅藻(Scenedesmus obliquus)为轮虫食物,在25℃下,应用群体累积培养和单个体培养法研究了食物浓度对采自新安江水域(屯溪段)的萼花臂尾轮虫的种群动态影响。结果表明:食物浓度对轮虫的种群增长率和休眠卵产量均有显著的影响,均表现为低食物浓度下(≤4.0×106cells·mL-1)萼花臂尾轮虫的种群增长率和休眠卵产量较小且无差异,高食物浓度下(8.0×106cells·mL-1)轮虫的种群增长率和休眠卵产量较大;食物浓度对轮虫的混交雌体百分率和受精率无显著影响;在食物浓度为4.0×106cells·mL-1时萼花臂尾轮虫的净生殖率最大,世代时间最长,而其内禀增长率在食物浓度为1.0×106cells·mL-1时最小;在食物浓度为8.0×106cells·mL-1时平均寿命和生命期望最长。     

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.     

Resting eggs of the marine rotifer Brachionus plicatilis Müller: development,and effect of irradiation on hatching

Diapause and hatching of Brachionus plicatilis Müller resting eggs were examined through histological and optical approaches. Compound microscope observations on 1% toluidine blue-stained embryo sections suggests that the total number of nuclei in an embryo during the internal diapause period increased from 22 on Day 2 to 39 (each n = 1) on Day 6. The outer layer of embryo membrane gradually thickens from 1.2 (Day 0) to 4.0 µm (Day 8) (each n = 10).Resting eggs that have completed maturation and are in the external diapause period require light for hatching. The threshold of light (halogen lamp) intensity for hatching was estimated to be 4400 lux for 30 min. Hatching rate decreased with longer wavelength irradiation (mercury lamp). Irradiation at more than 350 nm caused 1–25% hatching, but it reached 50–60% at 250–310 nm light. The addition of hydrogen peroxide or prostaglandins (E ₁, E ₂ or F ₂) caused resting egg hatching even in darkness. The production of peroxide in seawater caused by light as well as the oxidation of fatty acid to prostaglandins inside the embryo is a possible mechanism of resting egg hatching.     

Temperature conditions enhancing resting egg production of the euryhaline rotifer Brachionus plicatilis O. F. Müller (Kamiura strain)

We examined the effect of low temperature treatment(12°C), followed by transfer to highertemperature (25°C), on resting egg formation ofthe rotifer Brachionus plicatilis, Kamiurastrain. This strain has been mass cultured as livefeed at Kamiura Station (Japan Sea FarmingAssociation) for 9 years at 20°C without theappearance of sexual reproductive stages.After preculture in 20 l of 27 seawater at 12°C for 0, 10, 20, and 30 days,rotifers were inoculated into 0.5 l mass cultures andcultured at 25°C for 7–9 days. The inoculationdensities were changed from 20 to 400 ind. ml^–1,depending on mixis rate. Condensed and frozen Nannochloropsis oculata was fed to rotifers at thefeeding rate of 0.14 µg (dry weight)rotifer^–1day^–1. The control was cultured at12°C for the entire 36 day experiment. No mixisappeared and no resting eggs were produced when thelow temperature treatment was 0 or 10 days. However,mixis rates reached 50-60% after 20 or 30 days ofexposure to 12°C. The number of resting eggsproduced in these treatments reached 25,500 about 13 times higher than the control. Our resultssuggest that low temperature stimulated mictic femaleproduction and the transfer to the high temperatureaccelerated resting egg formation. This method may beuseful for producing resting eggs of rotifer strainsthat lack sexual reproduction in the common culturecondition at larval rearing facilities.     

Fungal Parasites of the Cereal Cyst Nematode Heterodera avenae in Southern Sweden

Fungal parasites of the cereal cyst nematode Heterodera avenae were isolated from four sites in southern Sweden. In all, 15 different fungi were isolated from different stages of the nematode life cycle. Among the egg parasites, Verticillium chlamydosporium was common in young cysts on roots, whereas an unidentified species of Verticillium (Verticillium sp. 1) was the dominating species in cysts from soil, especially if the soll had been stored for 8-12 months. V. chlamydosporium was frequently isolated from eggs in cysts from soil, when analyzed shortly after sampling. Verticillium sp. 1 is distinct from V. chlamydosporium because it does not produce dichtyo-chlamydospores in the aerial mycelium and because it grows at 6 C where V. chlamydosporium fails to grow. Paecilomyces lilacinus, Microdochium bolleyi, Cylindrocarpon sp., and several nonsporulating fungi were also isolated from eggs in cysts from soil. Between 10 and 20% of the eggs in cysts collected in the field were infected with fungi. In a pot test between < 1 and 29%, with a mean of 13%, of females on roots became infected, always by Nematophthora gynophila. Resting spores of N. gynophila extracted directly from field soil, collected at the four sites, varied from 3 to 49 spores/gram of air dried soil.     

萼花臂尾轮虫交配行为和受精作用研究

萼花臂尾轮虫的交配行类在致可分为５个阶段,除雌雄性比为１：２和１３时混交雌体的受精率为１００％外,其余性比下混交雌体的受精率皆无显著的差异。可受精的混交雌体自分率和具有精能力的雄性百分率皆降年龄的增大而下降,的有的混交雌体在出生后的４ｈ内均易于受精,以后随着雌长（Ｘ,ｈ）的增加,可受精的混交雌体百分率（Ｙ,％）呈非线性下降,Ｙ＝１６６．６３８６－１７．８１３Ｘ＋０．４８３７Ｘ＾２,当岭长达１８ｈ时