阿哈湖深层水中微生物和硫酸还原菌数量及群落结构空间变化

采用荧光原位杂交法分析了贵州阿哈湖深层水环境中总微生物、真细菌和硫酸盐还原菌数量。结果表明:该湖水中微生物总量为1.6×107个.L-1,真细菌占微生物总量的52.9%,且微生物总量和真细菌数量垂直变化无明显差异。随着水体深度的增加,活性微生物数量增加,且微生物的群落结构更加复杂。阿哈湖深层水体中有一定数量的硫酸盐还原菌存在。     

湖水含盐量和Cu2+浓度变化对Kinneret湖浮游植物的影响

通过人为改变湖水中的Cu^2 浓度和含盐量的方法,Cu^2 浓度和含盐量变化对Kinneret湖水中浮游植物可能造成的影响进行了分析。结果表明,湖水Cu^2 浓度增加会抑制Kinneret湖水中藻类等浮游植物的生长。这对改善湖水水质来7说是非常有利的,但高的Cu^2 浓度对农作物生长和人类健康是有害的,在另一方面,对含盐量较低的约旦河水来说,适当增加Cu^2 浓度则有利于藻类的生长。Kinneret湖中浮游植物的年平均生物量随湖水含盐量的下降而有增加的趋势,特别是当含盐量低于200μ左右时,浮游植物中蓝藻占的比例会升高,这对作为饮用水资源的Kinneret湖水来说是不利的,由此可见,适当控制和维持Kinneret湖水Cu^2 浓度和含盐量对湖水水质保护具有重要的意义。     

我国某些鱼类对达里湖碳酸盐型半咸水的适应能力

本文根据作者1975-1978年在达里湖的鱼类驯养工作中室外、室内的试验结果,并参照河北、内蒙古等省、自治区几个内陆性湖泊近年来水质变化过程和放养鱼类的效果,对梭鱼、鲢、鳙、草鱼、鲤、丁鱥、鲤鲫杂交种、青海湖裸鲤(湟鱼)、鲫、雅罗鱼、麦穗鱼、条鳅等十数种鱼对湖水的适应能力作了评述。对碳酸盐型半咸水湖水,梭鱼、鲢、鳙、草鱼最为敏感,在达里湖水中几小时即死亡;鲤、丁鱥等适应能力较强,在湖水中可活10天以上;条鳅、雅罗鱼和鲫鱼适应性很强,可在湖中繁殖发育。其中又以条鳅对高碱度的水耐力最强。水生植物光合作用使pH升高,易造成鲫鱼大批死亡。达里湖盐度5．5%,总碱度44．5毫克当量／升,pH9．30-9．56,已接近鲫鱼的适应极限;当碱度上升到73毫克当量／升,盐度9．08%(查干诺尔),pH9．6时,雅罗鱼也难于适应;湟鱼因来自氯化钠占主要成分的青海湖,它对碳酸盐含量高的达里湖水的适应能力比雅罗鱼、鲫鱼都强。     

贵州高原湖泊细菌和病毒分布特征及影响因素

应用SYBR Green Ⅰ荧光显微镜计数法,研究了贵州阿哈湖和百花湖细菌和病毒丰度的垂直分布特征,探讨了它们与温度、pH、溶解氧(DO)、电导率和溶解有机碳(DOC)之间的关系.两湖DOC的浓度范围为1.48～2.96 mg·L-1,细菌丰度为(3.32～16.6)×106个·ml-1,病毒丰度为(1.87～12.5)×107个·ml-1,病毒丰度与细菌丰度的比值(VBR)变化范围为4.09～12.77,平均值均为百花湖(BH)>阿哈湖入湖区(AHB)>阿哈湖湖心区(AHA).细菌和病毒丰度由湖水表层至底层呈减少趋势.两湖细菌丰度均与温度、pH、DO呈显著正相关,与电导率呈显著负相关,且与病毒丰度呈极显著性正相关.阿哈湖细菌丰度与DOC显著正相关.在阿哈湖湖心区,病毒丰度与DOC呈显著正相关.在阿哈湖入湖区,病毒丰度与DOC无相关性.百花湖中,细菌、病毒丰度均与DOC无相关性.     

南极海冰耐盐细菌NJ82的分子鉴定及其耐盐性初步研究

从129株南极海冰细菌筛选到1株耐盐细菌NJ82, 该菌最适生长盐度是12%, 能够耐受最高盐度为18%。对该菌株进行16S rRNA基因序列的同源性和系统发育分析, 结果表明：菌株NJ82属于Pseudoalteromonas属。从总蛋白质、脯氨酸、丙二醛(MDA)含量及膜透性变化等方面对高盐的适应性进行初步探讨。结果表明, 当盐度介于3.3%~12.0％时, 随着盐度升高, 菌株的蛋白质和脯氨酸含量呈快速增加趋势, 而MDA含量和膜透性变化幅度不大; 随着盐度进一步升高, 蛋白质含量呈下降趋势, 脯氨酸变化幅度不大; 而MDA含量升高和膜透性变化都达到极显著水平(P<0.01)。这些重要生理参数的变化将有助于了解海冰细菌在高盐环境下的适应机制。     

南极海冰耐盐细菌NJ82的分子鉴定及其耐盐性初步研究

从129株南极海冰细菌筛选到1株耐盐细菌NJ82,该菌最适生长盐度是12%,能够耐受最高盐度为18%.对该菌株进行 16S rRNA 基因序列的同源性和系统发育分析,结果表明:菌株NJ82 属于 Pseudoalteromonas 属.从总蛋白质、脯氨酸、丙二醛(MDA)含量及膜透性变化等方面对高盐的适应性进行初步探讨.结果表明,当盐度介于3.3%～12.0%时,随着盐度升高,菌株的蛋白质和脯氨酸含量呈快速增加趋势,而 MDA 含量和膜透性变化幅度不大;随着盐度进一步升高,蛋白质含量呈下降趋势,脯氨酸变化幅度不大;而 MDA 含量升高和膜透性变化都达到极显著水平(P＜0.01).这些重要生理参数的变化将有助于了解海冰细菌在高盐环境下的适应机制.     

黄河三角洲不同生态型芦苇对盐度适应生理的研究Ⅰ.渗透调节物质及其贡献

山东省黄河三角洲分布４种不同生态型芦苇——淡水沼泽芦苇、咸水沼泽芦苇、低盐草甸芦苇和高盐草甸芦苇。１９９４年与１９９５年的８～９月份对不同生境生态型芦苇的生长情况、群落组成及优势度进行观测,并测定４种不同生态型芦苇的有机和无机渗透剂以及渗透势和渗透调节能力。结果表明：不同生态型芦苇的多度、盖度、植株高度、叶片含水量和渗透势均随生境盐度的增大而降低;低盐度下的芦苇其渗透剂以Ｋ＋和可溶性糖为主,高盐度下以Ｎａ＋、Ｃｌ－为主;芦苇根部Ｎａ＋含量大于叶片,其渗透调节能力也高于叶片;植物体的Ｎａ／Ｋ比值随生境盐度而变化,而高盐度下Ｎａ／Ｋ比为１左右;在渗透调节中有机和无机渗透剂的贡献随生境盐度而变化,有机渗透剂贡献随生境盐度增大而减少,无机渗透剂贡献则随盐度增加而增大。上述结果证明芦苇是一种应性较强的植物,从抗盐机理考虑可以认为它是一种假盐生植物。     

武汉东湖磷细菌种群结构的研究

对东湖磷细菌种群结构研究结果表明,至少有芽孢杆菌属,微球菌属,不动细菌属,气单胞菌属,产碱杆菌属,贝内克氏菌属,无色杆菌属,短杆菌属,肠杆菌属,黄杆菌尾,微杆菌 ,假单胞菌属,沙雷氏菌属,黄单胞菌属和发酵单胞菌属15个属的不同菌株以其对有机磷,无机磷化合物的分解能力推动着湖泊中磷的循环,其中以芽孢杆菌属和微球菌属居于明显的优势。磷细菌在湖泊中的分布随水质的污染程度和磷化合物含量的不同而表现有明显的判别：在数量上,湖泥高于湖水,污染较重的I站高于水质较好的II站,在调查期间,有机磷细菌数在多数情况下亦高于无机磷细菌,在种群结构上,1站湖水中种类最多,Ⅲ站次之,II站最少。     

达赉湖水域变化对水鸟群落的影响

内蒙古达赉湖国家级自然保护区是东北亚鸟类迁徙的重要停歇地和繁殖地,被列入拉姆萨尔"国际重要湿地"。近10年来,达赉湖面积急剧减少,造成湿地环境变化,从而可能对水鸟群落结构产生影响。本文分析了达赉湖2004—2013年湖水面积变化对水鸟群落结构的影响,主要研究结果如下:湖水面积与水鸟多样性及均匀度指数呈显著负相关,与雁形目全年平均多样性指数呈不显著负相关,与鸻形目全年平均多样性指数呈显著负相关,与鹳形目全年平均多样性指数呈不显著正相关。对湖水面积与重点保护物种数量的相关性分析表明,2004年到2011年湖水面积下降期间,灰鹤Grus grus、蓑羽鹤Anthropoides virgo、大天鹅Cygnus cygnus、小天鹅C.columbianus及遗鸥Larus relictus的种群数量均有所增加,而丹顶鹤G.japonensis、白枕鹤G.vipio及疣鼻天鹅C.olor的种群数量则在下降。随着内蒙古东北部暖干化气候的持续,湖水面积的继续缩减可能引起大面积沙化,进而影响水鸟的停留和繁殖,因此有必要对该地区水鸟群落与湖泊动态的关系进行长期监测。     

青海柴达木盆地东部不同盐度湖泊四季现生介形虫的分布特征及其环境指示意义

2014年我们对柴达木盆地东部盐度各异的四个湖泊,可鲁克湖、托素湖、尕海和小柴旦湖,分四季进行现生介形虫调查研究,探索柴达木盆地现生介形虫在盐度不同的水体中的分布规律,并分析了不同介形虫属种与其生存环境间的相互关系。结果表明,在所调查的4个湖泊中共分布有介形虫5属11种,其中在半咸水的托素湖中只分布有2个种,Eucypris inflata为优势属种,在四季均有产出,但在春、夏、秋三个季节13℃—20℃的温度范围内丰度巨大,而另一属种E.rischtanica只在春季有少量出现。可鲁克湖中虽然介形虫属种分布较多,共计4属8种,但全部是单壳,没有发现现生活体;尕海及小柴旦湖水盐度过高,不适宜介形虫的生长发育。     

Decreased salinity effects in Lake Kinneret (Israel)

Kinneret is the only freshwater lake in Israel. It currently supplies about 30% of national water demands. Most pumped water is for drinking, and water quality is of major concern. During 1970–1987 temporal changes were observed in the lake ecosystem: decrease of salinity, decrease of total N (TN) and increase of total P (TP) mass contents, decline of TN/TP ratio, increase of phytoplankton biomass and increase of algal photosynthetic specific activity. It is suggested that because of decrease in salinity carbonic anhydrase activities in algal cells and nitrifying bacteria were enhanced. The increase of NO₃ flux through nitrification consequently enhanced denitrification and nitrogen losses in lake waters. These increased N losses together with P increase, as reflected by the decline of TN/TP ratio might be a slight shift from the present both P and N deficiencies to a higher level of N limitation in the Kinneret ecosystem. This This may cause changes in phytoplankton community structure possibly without changing primary production levels but deteriorate water quality.     

Ephemeral saline lakes on the Canadian prairies: their classification and management for emergent macrophyte growth

At two ephemeral saline lakes in Saskatchewan, changes in the physical and chemical features of water and sediments at various basin positions were monitored during a wet-dry cycle in 1978 and 1979. Water salinity fluctuated widely in response to changes in water volume and mass of solute in the water. When basins were dry, the soluble salt content of sediments 0–10 cm deep was higher than sediments 50–60 cm deep and sediments in the lake centre were more saline than at the shoreline. Upon reflooding, there was a large immediate decrease in sediment salinity at the 0–10 cm depth, such that this layer was less saline than sediments 50–60 cm deep. Sediments in the lake centre remained more saline than at the shoreline.Classification of lake salinity is necessary to assess the potential of a lake for emergent production. The large variances in ephemeral lake salinity due to water volume changes indicate that classification should be based upon the water volume-salinity cycle of these lakes rather than the salinity of any single water or sediment sample. Water management efforts to lower salinities, to improve these wetlands for emergent growth, should be aimed at reducing the salinity regime of the littoral zone. Flushing, dilution and drying and reflooding techniques are discussed as methods to decrease salinity.     

Growth Response of Soda Lake Bacterial Communities to Simulated Rainfall

Moderately saline soda lakes harbor extremely abundant and fast growing bacterial communities. An interesting phenomenon of an explosive bacterial growth in shallow soda lakes in Eastern Austria after dilution with rainwater, concomitantly with a significant decrease in temperature was observed in a former study. In the present study, we tried to identify the factors being responsible for this enhanced bacterial growth in laboratory batch cultures. Three experiments were performed with water taken from two different lakes at different seasons. Natural soda lake water was diluted with distilled water, artificial lake water, sterile filtered soda lake water, and grazer-free water to test (1) for the influence of compatible solutes released to the environment and reduced salt stress after osmotic down-shock, (2) for the influence of nutrients, which may be washed in from the dry areas of the lake bottom after rainfall and (3) for the decrease of grazing pressure due to dilution. The potential influence of (4) viruses was indirectly deduced. The response of the bacterial community to the manipulations was measured by changes in bacterial numbers, the incorporation of ³H-leucine and the concomitant determination of the amount of ³H-leucine uptaking bacteria by microautoradiography. The influence of the environmental factors enhancing bacterial growth after a simulated rainfall event showed variations between the lakes and over the seasons. The addition of nutrients was, in all experiments, the main factor triggering bacterial growth. The decrease in grazing pressure and viral lysis after dilution was of significant importance in two of three experiments. In the experiment with the highest salinity, we could show that either compatible solutes released after osmotic down-shock and used as a source of nutrients for the soda lake bacterial populations or reduced salt stress were most probably responsible for the observed marked enhancement of bacterial growth.     

Effect of Physical Factors on Bacterial Distribution in the Jordan River Mouth Area in Israel

The Jordan River mouth is an area of complicated hydrography and variable and vulnerable ecology. It has changeable water and sediment regimes, for example, large spatial gradients of biological, chemical, physical, and hydrological characteristics. The Jordan River enters Lake Kinneret in the north and carries with it sewage from the Upper Galilee; thus the river is the major source of enteric bacteria in the lake. This research is based on theoretical analysis as well as on biological-hydrodynamical measurements along a discharging free, turbulent jet flow. Three components of velocities were recorded downstream from the exit cross-section for a distance of 700 m, and the mean streamwise velocity turbulence intensity and the turbulence scale were calculated. The measuring devices were an original three-dimensional velocity-fluctuation meter. Results of these measurements show that the Jordan River flows through the whole transect until it reaches the crest of a bar. After this, there is a separated exponential flow from the bottom and upper layers for ~100m after the bar. Fecal coliforms, Escherichia coli, and Klebsiella spp. were enumerated as colony-forming units from samples taken along the Jordan River path as it entered Lake Kinneret. Bacterial numbers were similar in surface and bottom waters in front of the bar. Behind the bar, however, there was a sharp decrease of bacterial numbers in the surface water, probably because of photooxidative stress. Despite the more protective environment of the bottom waters, the numbers here also decreased, indicating that the bar is a physical barrier for bacterial distribution. Furthermore, we found a significant effect of the flow velocity of Jordan River water on the bacterial distribution in Lake Kinneret. When the velocity is high, bacteria are distributed over a longer distance, regardless of their numbers in Jordan River mouth.     

Influence of temperature and body weight on mosquito predation by the dragonfly nymph Mesogomphus lineatus

Population densities, migrations and food composition of Echinogammarus veneris in Lake Kinneret were studied during march–September 1976. Migrations are affected by changes of water level and littoral currents. Peridinium was abundant in the gut content during its blooming period in the lake while cladocerans, benthic copepods, rotifers and other algae were abundantly found in other months. Metabolic parameters that were calculated for the gammarid population indicated that its contribution to the carbon-flow system in Lake Kinneret is negligible in comparison with nematodes, molluscans or planktonic copepods and cladocerans.     

Do Patterns of Bacterial Diversity along Salinity Gradients Differ from Those Observed for Macroorganisms?

It is widely accepted that biodiversity is lower in more extreme environments. In this study, we sought to determine whether this trend, well documented for macroorganisms, also holds at the microbial level for bacteria. We used denaturing gradient gel electrophoresis (DGGE) with phylum-specific primers to quantify the taxon richness (i.e., the DGGE band numbers) of the bacterioplankton communities of 32 pristine Tibetan lakes that represent a broad salinity range (freshwater to hypersaline). For the lakes investigated, salinity was found to be the environmental variable with the strongest influence on the bacterial community composition. We found that the bacterial taxon richness in freshwater habitats increased with increasing salinity up to a value of 1‰. In saline systems (systems with >1‰ salinity), the expected decrease of taxon richness along a gradient of further increasing salinity was not observed. These patterns were consistently observed for two sets of samples taken in two different years. A comparison of 16S rRNA gene clone libraries revealed that the bacterial community of the lake with the highest salinity was characterized by a higher recent accelerated diversification than the community of a freshwater lake, whereas the phylogenetic diversity in the hypersaline lake was lower than that in the freshwater lake. These results suggest that different evolutionary forces may act on bacterial populations in freshwater and hypersaline lakes on the Tibetan Plateau, potentially resulting in different community structures and diversity patterns.     

Microbial diversity in water and sediment of Lake Chaka, an athalassohaline lake in northwestern China

We employed culture-dependent and -independent techniques to study microbial diversity in Lake Chaka, a unique hypersaline lake (32.5% salinity) in northwest China. It is situated at 3,214 m above sea level in a dry climate. The average water depth is 2 to 3 cm. Halophilic isolates were obtained from the lake water, and halotolerant isolates were obtained from the shallow sediment. The isolates exhibited resistance to UV and gamma radiation. Microbial abundance in the sediments ranged from 10(8) cells/g at the water-sediment interface to 10(7) cells/g at a sediment depth of 42 cm. A major change in the bacterial community composition was observed across the interface. In the lake water, clone sequences affiliated with the Bacteroidetes were the most abundant, whereas in the sediments, sequences related to low G+C gram-positive bacteria were predominant. A similar change was also present in the archaeal community. While all archaeal clone sequences in the lake water belonged to the Halobacteriales, the majority of the sequences in the sediments were related to those previously obtained from methanogenic soils and sediments. The observed changes in the microbial community structure across the water-sediment interface were correlated with a decrease in salinity from the lake water (32.5%) to the sediments (approximately 4%). Across the interface, the redox state also changed from oxic to anoxic and may also have contributed to the observed shift in the microbial community.     

微囊藻毒素与自然水体中细菌VIVIFORM状态的相关性

细菌VIVIFORM状态是直接关系到自然水体水质评价和环境保护的生态现象 ,其形成机理相当复杂 ,但环境胁迫是主要诱因。通过人为改变湖水中的微囊藻毒素 (MC LR)水平 ,对水体中蓝藻毒素与细菌VIVIFORM状态之间的相关性进行了分析。结果表明 ,较高的毒素水平对水体中细菌种群总量没有明显的影响 ,但能刺激VIVIFORM细菌转化成可培养状态 ,从而证实了自然水体中蓝藻毒素与水细菌VIVIFORM状态之间存在直接的相关性。     

Microbial Diversity in Water and Sediment of Lake Chaka, an Athalassohaline Lake in Northwestern China

We employed culture-dependent and -independent techniques to study microbial diversity in Lake Chaka, a unique hypersaline lake (32.5% salinity) in northwest China. It is situated at 3,214 m above sea level in a dry climate. The average water depth is 2 to 3 cm. Halophilic isolates were obtained from the lake water, and halotolerant isolates were obtained from the shallow sediment. The isolates exhibited resistance to UV and gamma radiation. Microbial abundance in the sediments ranged from 10⁸ cells/g at the water-sediment interface to 10⁷ cells/g at a sediment depth of 42 cm. A major change in the bacterial community composition was observed across the interface. In the lake water, clone sequences affiliated with the Bacteroidetes were the most abundant, whereas in the sediments, sequences related to low G+C gram-positive bacteria were predominant. A similar change was also present in the archaeal community. While all archaeal clone sequences in the lake water belonged to the Halobacteriales, the majority of the sequences in the sediments were related to those previously obtained from methanogenic soils and sediments. The observed changes in the microbial community structure across the water-sediment interface were correlated with a decrease in salinity from the lake water (32.5%) to the sediments (approximately 4%). Across the interface, the redox state also changed from oxic to anoxic and may also have contributed to the observed shift in the microbial community.     

Water Quality Quantification: Basics and Implementation

Quantitative estimation of water quality and its relationships with management activities is a necessary step in efficient water resources management. However, water quality is typically defined in abstract terms and management activities are rarely quantified with respect to their impact on lake water quality. Here we show by demonstration of systems for Lake Kinneret, Israel and the Naroch Lakes of Belarus how water quality can be quantified in relation to lake management activities to be a part of sustainable management.