Inferences concerning climatic change from a deeply frozen lake on Rundfjeld,Ellesmere Island,Arctic Canada

A small lake on top of Rundfjeld, central Ellesmere Island, at an elevation of approximately 830 m, is frozen to the bottom, and the thickness of lake ice present is at least 5.45 m. Under present climatic conditions the lake does not thaw to the bottom, even during the warmest summers; i.e., 3 to 4 m of ice still floored the deepest part of the lake in mid-August 1987. A radiocarbon age determination via accelerator mass spectrometry (AMS) on a sample of the filamentous green alga Mougeotia sp., recovered from the lake ice at a depth below 4 m, gave 5730±70 BP (TO-530). The date indicates that the lake was probably completely open for an unspecified period of time during the warmest part of the Hypsithermal Interval. This situation is in agreement with data derived from a variety of other sources in Ellesmere Island and adjacent Greenland.     

Naphthalene Degradation Kinetics of Micrococcus sp., Isolated from Activated Sludge

Biodegradation of naphthalene by Micrococcus sp., isolated from the effluent of an activated sludge plant, was studied. The effects of pH (5–8), glucose concentration (100–1000 mg/L) and inoculum concentrations (1–5%) on the growth and naphthalene degradation potential of Micrococcus sp. were investigated. Maximum naphthalene degradation and subsequent high microbial growth were observed at optimum pH (pH 7), glucose concentration (500 mg/L) and inoculum concentration (3%). To investigate the maximum naphthalene tolerance potential of Micrococcus sp., very high concentrations of naphthalene (500–5000 mg/L) were used in the presence of non‐ionic surfactants. The examined surfactants (Triton X‐100 and Tween‐80) increased the bioavailability of naphthalene to the microbes and Complete naphthalene degradation by Micrococcus sp. was observed at an initial naphthalene concentration of 500 mg/L. However, the degradation potential decreases as the naphthalene concentration increases. Very high naphthalene concentrations also affected the growth of microbes and the corresponding substrate inhibition kinetics was described using four models (Haldane, Webb, Edward and Aiba). Based on correlation coefficient and percentage error values, all four substrate kinetic models were able to describe the dynamic behavior of naphthalene biodegradation by Micrococcus sp.     

原绿球藻生态条件的研究

原绿球藻(prochlorococcus sp.)是一种海水单细胞藻类,个体小(平均长径0.8μm,宽0.5μm),生长繁殖迅速,是水产养殖中一种新的理想生物饵料。笔者在实验室条件下.研究了温度、光照和营养盐成分(氮、磷、铁单因子试验和氮、磷、铁正交试验)对这种原绿球藻生长繁殖的影响,以确定该藻的最适生态条件。单因子试验结果表明:原绿球藻适宜生长的温度为10～30℃.最适温度为25～30℃;适宜生长的光照范围为20～200μmol/m~2s.最适光照为20～40μmol/m~2s;适宜生长的N、P、Fe含量浓度分别为0～30 mg/L、0～3.0 mg/L、0～1.0 mg/L,最适浓度分别为N-5～30 mg/L、P—0.5～1.5 mg/L、Fe—0.6～1.0mg/L。正交试验结果表明:Fe对藻的生长影响极显著,N对藻的生长影响显著,P作用不显著。N和P交互作用显著,N和Fe、P和Fe交互作用不显著。最优水平组合为N-30mg/L、P—1.5mg/ L、Fe-0.8mg/L。     

有机磷农药对扁藻的联合毒性研究

采用水生毒理联合效应相加指数法，比较了久效磷、辛硫磷、敌敌畏以及对硫磷的单剂和混合剂对扁藻的急性毒性和联合毒性。结果表明：久效磷和辛硫磷的联合毒性为协同作用；久效磷和敌敌畏的联合毒性为拮抗作用；久效磷和敌敌畏和对硫磷的48h联合毒性为协同作用，72h、96h则为拮抗作用。     

Late-Quaternary diminution and abundance of prehistoric bison (Bison sp.) in eastern Washington state, U.S.A.

Bison (Bison spp.) occurred in eastern Washington state during the late Quaternary. This area is considered to be peripheral to the center of this taxon's natural range. Bison in the plains east of the Rocky Mountains, the heart of this range, underwent diminution during the late Quaternary, and apparently also did so in other, peripheral areas. A ratio diagram of measurement data derived from eight zooarchaeological collections of bison remains recovered from eastern Washington, in combination with the presence of both sexes and all age classes of individuals, indicate that local bison may have also undergone diminution there. There are, however, a relative paucity of bison remains during the middle Holocene and an apparent 2000-year absence of bison from eastern Washington at this time. As a result, the hypothesis that bison became smaller elsewhere and then immigrated to eastern Washington cannot be falsified. Both the diminution and the fluctuating abundance of bison appear to be responses to forage quality and quantity.     

重金属胁迫对塔胞藻细胞密度及叶绿素荧光特性的影响

采用调制式叶绿素荧光仪测定了重金属(Cu2+、Zn2+、Cd2+)胁迫(24h、48h、72h和96h)对塔胞藻叶绿素荧光特性的影响.测定的主要参数有:PSII的原初光能转化效率(Fv/Fm)、PSII的潜在活性(Fv/Fo)、PSII的实际光能转化效率(Yield)、相对表现电子传递效率(rETR)、光化学淬灭(qP...     

刚毛藻对静态模拟刺参养殖池塘上覆水营养盐含量的影响

利用室内装置模拟的刺参养殖池塘上覆水,在温度为25℃,光照为(4000±200)lx条件下静态培养刚毛藻48 h,定时测定上覆水中总氮(TN)、氨态氮(NH_4~+-N)、硝态氮(NO_3~–-N)、亚硝态氮(NO_2~–-N)、总磷(TP)、活性磷(PO_4~(3–)-P)等营养盐含量,分析了氮磷营养盐含量的动态变化规律,探讨了刚毛藻生物量对沉积物-水界面营养盐含量变化的影响。结果表明,刚毛藻生物量对各营养盐含量的影响存在显著性差异(P0.05)。随着培养时间延长,上覆水中营养盐含量均呈现先增大后减小的趋势。上覆水中各营养盐含量在培养6～24 h时分别达到最大值,其中当刚毛藻生物量为0.5～4.5 g/L时,TN、NO_3~–-N、NO_2~–-N、NH_4~+-N、TP、PO_4~(3–)-P含量达到最大值。继续培养,上覆水中各营养盐的含量逐渐减小,其中生物量为8.5 g/L时刚毛藻对NO_3~–-N、NO_2~–-N的吸收效果最好;生物量为0.5 g/L时刚毛藻对NH_4~+-N、PO_4~(3–)-P吸收效果最好。因此,高生物量(8.5 g/L)刚毛藻可降低上覆水中NO_3~–-N、NO_2~–-N含量,但低生物量(0.5 g/L)刚毛藻能有效吸收上覆水中的NH_4~+-N、PO_4~(3–)-P。     

Artemia parthenogenetica in Lake Hayward, Western Australia. I. Interrupted recruitment into adult stages in response to seasonal limnology

Lake Hayward, Western Australia, is a pristine, monomictic coastal lake with a residual brine (depth=1.5 m) of 200 gL⁻¹: stratification in winter (May to October) followed the input of ground water and rain. The epilimnion had temperature ranges of 10–30°C, and salinity from 65–110 g L⁻¹. Maximum depth in winter was 2.4 m. The population structure of the brine shrimpArtemia parthenogenetica, the dominant metazoan grazer in Lake Hayward, was studied from September, 1989, to February, 1991. The L. Hayward population ofA. parthenogenetica is predominantly ovoviviparous with little recruitment into the adult population. Cyst production occurs in summer, and there was evidence for recruitment from cyst hatching in the winters of 1989 and 1990. Nauplii were continuously present throughout the study period. Nevertheless, recruitment through to adult stages as defined by the presence of gravid females occurred only twice: in October–December, 1989 and in December, 1990. Based on limited observations of long-term survival of laboratory cultures, we believe that the major mechanism controlling nauplius survival and recruitment ofArtemia in Lake Hayward is food quality and quantity.     

星洲银罗非鱼线粒体细胞色素b基因的序列分析

克隆并测定了星洲银罗非鱼(Oreochromis sp.)细胞色素b基因(cyt b)的全序列,得到全长1 141bp的序列用于分析,用MEGA4.0分析软件与GenBank中的线粒体DNA序列进行序列比较,显示星洲银罗非鱼与其他鱼类的cyt b基因的同源性较高,同源度介于83%~93%间;根据星洲银罗非鱼与莫桑比克罗非鱼、尼罗罗非鱼等12种鱼类的cyt b基因序列构建的系统进化树,初步确定尼罗罗非鱼、莫桑比克罗非鱼为星洲银罗非鱼的父母本。     

同时检测海洋贝类包纳米虫和派琴虫的双重TaqMan MGB探针实时荧光PCR方法

根据包纳米虫（Bonamia sp.）SSU rDNA和派琴虫（Perkinsus sp.）ITS rDNA的保守区序列,设计特异性引物和Taqman MGB探针,建立了同时检测上述两种贝类原虫的双重实时荧光PCR方法.该方法可检测到包纳米虫基因的446拷贝质粒,以及派琴虫基因的171拷贝质粒,具有较高的灵敏度.以10倍系列稀释的包纳米虫阳性标准品质粒和派琴虫阳性标准品质粒为模板,测得该方法的定量标准曲线相关系数分别为0.999和1.000,显示出很好的扩增效率.同时该方法与尼氏单孢子虫（Haplosporidium nelsoni）、沿岸单孢子虫（H.costale）等其他贝类原虫,以及副溶血性弧菌（Vibrio parahaemolyticus）、迟缓爱德华氏菌（Edwardsiella tarda）和鮰爱德华氏菌（E.ictaluri）等海水养殖常见致病菌之间无交叉反应,表现出较高的特异性.福建莆田的湄州湾、平海湾、兴化湾等地采集的296份贝类临床样本的检测证明,该方法是一种有效的快速检测鉴定上述2种贝类原虫的方法,具有良好的灵敏度和特异性,可广泛应用于海洋贝类原虫感染情况调查,以及贝类疫病检疫监控等领域.