The Tragedy of the Karama Dam Project/Jordan

The Karama Dam, with a capacity of 55 Mio m³, was constructed in 1995 on Wadi Mallaha in the Jordan Valley area in order to store water for irrigational uses. The dam was constructed in spite of experts' warnings that this dam geologically, hydrogeologically, seismically, and from the points of view of salinity of its water, its management and the water resources to fill it is totally irrelevant, and that the dam will fail to fulfill its purposes. Now after 9 years of its construction the dam fails to collect water because there are no sources available to fill it. The water the farmers were deprived of to partially fill the dam to demonstrate its success became in the dam reservoir highly saline (20 000 μS/cm). Reservoir bottom collapses due to dissolution of salts took place and large water amounts were lost to the underground. Not a single drop of water from the dam has been of any use for any purpose until now. Equipment to pump water for irrigational uses has been corroding, and the government is paying the depreciation, capital, and running cost of a fiasco project.     

太湖梅梁湾与五里湖浮游植物群落的比较

富营养化和风浪是影响大型浅水湖泊浮游植物群落的重要因素,本文于2003年10月至2004年9月对太湖梅梁湾和五里湖理化环境因子(水温、透明度值、悬浮质浓度和氮、磷营养盐浓度)和浮游植物群落进行了逐月监测,通过对两个湖区理化因子和浮游植物群落结构在周年内季节变化的比较研究,探讨富营养化程度以及风浪对浮游植物群落结构的影响,结果为:(1)梅梁湾由于受风浪影响悬浮物含量较高,五里湖则富营养化水平更高.(2)周年内五里湖浮游植物平均生物量(6.85 mg/L)高于梅梁湾的平均生物量(4.99 mg/L),两个湖区都呈现夏秋高峰、冬季低谷的变化特征.梅梁湾浮游植物群落季节演替的模式基本为:冬季硅藻(小环藻属Cyclotella spp.)和隐藻(隐藻属Cryptomonas spp.)-春季绿藻(细丝藻属Planctonema sp.)-夏季绿藻(绿球藻目Chlorococcales种类)和蓝藻(微囊藻属Microcystis spp.和浮游蓝丝藻属Planktothrix spp.)-初秋蓝藻(微囊藻属)和硅藻(浮游直链硅藻Aulacoseira spp.)-秋季隐藻(隐藻属).五里湖的季节演替模式没有梅梁湾明显,全年隐藻(隐藻属)都占优势,在此基础上,秋冬季硅藻(小环藻属和浮游直链硅藻属)占优势,裸藻(裸藻属Euglena spp.)在冬春季占优势,绿藻(绿球藻目种类和团藻目衣藻属Chlamydomonas spp.)在整个春季和初夏的优势地位在夏季被蓝藻(微囊藻属和浮游蓝丝藻属)所取代.群落构成的差异是浮游植物对两个湖区不同风浪条件和富营养化水平的响应结果.(3)通过与PEG(Plankton Ecology Group)模式的比较,梅梁湾和五里湖浮游植物群落的季节演替主要受水温、光照、营养盐(氮、磷)浓度和浮游动物牧食等因子的影响,因此,大型富营养化浅水湖泊浮游植物群落演替规律需要进一步的研究.     

抚仙湖、洱海、滇池浮游藻类功能群1960s以来演变特征

作为主要的初级生产者,浮游植物在水生生态系统中扮演着重要的角色,浮游植物的时空分布反映了生态环境的变化.依据浮游植物的形态、生理、生态特点而定义的浮游藻类功能群对藻类的耐受性和敏感性进行了描述,因而浮游藻类功能群的组成是生境特征的良好指示者.对1960s至今抚仙湖、洱海、滇池3个高原湖泊的浮游藻类组成进行分析,并首次将功能群理论运用到这3个湖泊.结果表明,3个湖泊的浮游藻类优势功能群组成在近50～60年间发生了明显的改变:抚仙湖的浮游藻类优势功能群演变过程为C、X2、Lo、F、P(1960s)-H1、C、P(1980s)-P、C、T(1990s)-T(2000年以后);洱海的浮游藻类优势功能群演变过程为J、Lo、MP、C、H1(1960s)-C、H1(1980s)-C、H1(1990s)-C、H1、M(2000年以后);滇池的浮游藻类优势功能群演变过程为J、N、P、MP、Lo(1960s)-J、P、MP、M(1980s)-J、M(1990s)-M(2000年以后).抚仙湖、洱海、滇池水体内的藻类功能群演替趋势特征,即耐低温物种的减少以及喜营养物种的增加,表明3个高原湖泊在近几十年可能受到了气候变暖和营养程度增加的影响.     

热带富营养化湖泊中浮游植物的脂肪酸组成与分布

星湖位于广东省．是一个热带地区的湖泊．本文测定和分析了该湖的两个子湖仙女湖和中心湖浮游植物群落的脂肪酸组成,探讨了浮游植物群落特征与脂肪酸组成之间的关系．两个子湖的富营养化程度较高,其中中心湖更严重．仙女湖的浮游植物群落以蓝藻为主导,而在中心湖则蓝藻或金藻占优势．浮游植物样品中检测到的脂肪酸碳链长为16碳到22碳．其中饱和脂肪酸和单不饱和脂肪酸种类较少,均有3种;而高不饱和脂肪酸的种类相对较多．两个子湖的脂肪酸均以饱和脂肪酸为主,高不饱和脂肪酸浓度相对较低．对于单一的脂肪酸种类来说,C16：0浓度最高,其浓度与蓝藻数量有很高的相关性(R^2=0．955,P=0．001),表明样品中的C16：0主要来源于蓝藻．而富含EPA(二十碳五烯酸)的硅藻和隐藻生物量高时其浮游植物的EPA浓度也较高;在中心湖中高浓度的DHA(二十二碳六烯酸)主要来源于金藻总之．两个子湖泊的脂肪酸组成与浮游植物群落结构特征基本一致．     

太湖、琵琶湖中水平扩散系数的探讨

根据１９９２年和１９９３年在太湖和日本琵琶湖观测到的长序列湖流资料,依据Ｔａｙｌｏｒ扩散理论计算了太湖和琵琶湖中的水平扩散系数,计算结果与通过浓度扩散方程计算基本一致。     

Zooplankton community structure and ecology of the tropical-highland Lake Hayq, Ethiopia

Lake Hayq, a highland lake in Ethiopia, was stocked with Tilapia fish (Oreochromis niloticus) in late 1970s, offering an opportunity to study the effect of fish predation in a natural lake. Since 1930s, some limnological surveys have been done sporadically documenting a change in zooplankton composition including the disappearance of cladocerans, hypothesizing the stocked planktivorous fish could be a cause. Nevertheless, no detailed research was conducted to identify potential effects of fish stocking predominantly due to its remote location. The article presents data about zooplankton composition, abundance and biomass done between October 2007 and January 2009 on short-time intervals including the underlying limnological variables. The zooplankton community was depauperate comprising two copepods, three cladocerans, and six rotifers taxa, as typical for tropical lakes. Total mean standing biomass of all crustacean zooplankton was 237 mg dry mass m⁻³, which gave Lake Hayq an intermediate position when compared with other tropical lakes. Of copepods, Thermocyclops ethiopiensis was almost an exclusive species, and its temporal variation was influenced by food supply and water temperature. We refute the hypothesis that Tilapia was the cause for the seasonal disappearance of cladocerans, and attribute it to the adverse effect of episodic mixing. Nevertheless, the planktivorous fish probably plays a key role in structuring the cladocerans in particular the large-sized Daphnia magna. In January 2008, we observed a massive planktivorous fish mortality that triggered high algal biomass, which was later grazed by large-sized D. magna demonstrating the trophic cascade hypothesis in a natural ecosystem.     

武汉后湖浮游植物现存量与生产量季节变动的初步研究

根据1990年5月—1991年4月武汉后湖浮游植物种类组成、现存量和生产量的周年资料分析,绿藻、硅藻、蓝藻为优势类群;现存量和生产量高低次序依次为:秋、冬、夏、春。并以浮游植物群落生态作为主要依据对后湖的营养状态进行了综合评价。     

Effects of Salinity and Mangrove Detritus on Desorption of Metals from Brackish Water Desorption of Metals from Brackish Water and Shrimp

Desorption and bioaccumulation of Cd, Zn, and Pb were studied using naturally contaminated sediment from a brackish water pond in the Sunderban Biosphere Reserve in India. Pattern of desorption of the metals from the sediment and bioaccumulation in fingerlings of the teleost Oreochromis mossambicusand postlarvae of the shrimp Penaeus monodon were studied as a function of salinity and loading of detritus of a mangrove plant. Effects of both salinity and loading of detritus on bioaccumulation of the metals were studied under two conditions: either the animals were allowed free access to the sediment or access was denied. Ninety‐six hour experiments showed that desorption of Cd and Pb from sediment into water increased with salinity of the medium while desorption of Zn decreased. Salinity of the medium also had a significant effect on the bioaccumulation of metals by fish; Cd and Pb accumulation decreased in saline medium while the accumulation of Zn increased. Conditions of access to sediment had no effect on the bioaccumulation of metals by fish; effect of interaction between salinity and access condition was also insignificant. The access conditions, however, significantly influenced accumulation of metal by the shrimp postlarvae. The effect of interaction between salinity and access condition was insignificant in influencing the bioaccumulation of all metals except Zn. The accumulation of Zn increased as a function of the salinity of the medium when shrimp postlarvae were allowed access to the sediment. Desorption of metals from sediment to water were below detection limits when detritus of a mangrove plant was added to the medium. Both the level of detritus and the conditions of access influenced accumulation of metals by fish, but the effect of interaction between the two factors were found to be insignificant. Shrimp postlarvae showed net accumulation only of Pb in the presence of detritus and the accumulation of Pb increased when the larvae were separated from the sediment. The results are important in understanding the mobility of metals between solid and aqueous phases in brackish water environments that experience periodic fluctuations in salinity and fluxes of organic load in the form of mangrove detritus.     

湖北省西凉湖浮游动物群落周年动态变化及其与环境因子的关系

2007年11月至2008年10月对西凉湖浮游动物进行了4次调查,共检出浮游动物224种,其中原生动物112种,轮虫90种,枝角类15种,桡足类7种.秋季浮游动物物种数最多,为111种,冬季最少,为75种,春季和夏季分别为107种和88种.冬季浮游动物丰度最高,为126731 ind./L,春季最低,为71356ind...     

Phytoplankton dynamics and cyanobacterial dominance in Murchison Bay of Lake Victoria (Uganda) in relation to environmental conditions

Murchison Bay is a shallow embayment in the north-western part of Lake Victoria, strongly influenced by urban pollution from the Ugandan capital Kampala. Two stations, representing the semi-enclosed innermost part of the bay and the wider outer part of the bay, were sampled in the period from April 2003 to March 2004, in order to assess the phytoplankton community and the nutrient status in the bay. Murchison Bay was highly eutrophic with average concentrations (n=25) of total phosphorous >90 μg L⁻¹ and total nitrogen >1100 μg L⁻¹ in the inner part of the bay. The phytoplankton community was dominated by a variety of cyanobacterial species and diatoms. Cyanobacteria were dominant in the whole bay, whereas diatoms were more abundant in the outer part of the bay. Moreover, the proportion of N-fixing species like Anabaena sp. was higher in the outer part of the bay, whereas species like Microcystis sp. were more abundant in the inner part of the bay. The phytoplankton community, especially in the outer part of the bay, may be influenced by light limitation. Low NO₃-N concentrations in the bay may also indicate a possible N-limitation, thus favouring growth of N-fixing cyanobacteria. The open bay is, however, a complex system, and additional environmental factors and loss processes most likely affect the phytoplankton community.     

东太湖浮游植物与浮游动物群落的嵌套性及其互作网络的季节特征

浮游生物主要由浮游植物和浮游动物组成,是湖泊生态系统的重要组分.嵌套性结构及物种间的互作关系对群落的分布格局、功能乃至稳定性都具有重要意义,然而到目前为止,我们对此仍知之甚少.为此,本研究以东太湖为研究区域,在2019-2020年期间进行了春、夏、秋、冬季的观测调查,根据浮游生物群落的组成和多样性特征,结合群落分布矩阵和二分网模型研究浮游生物的嵌套性格局及其互作关系,并探讨其驱动机制.结果显示:(1)在时间上,春、秋、冬季水体的理化特征较为相似,但与夏季的水质差异显著.在空间上,西南部区域的综合污染指数显著高于东北部;(2)环境异质性使得浮游植物呈现出明显的嵌套性分布,即秋、冬季群落是春、夏季群落的子集.然而,浮游动物并未呈现该分布特征;(3)浮游生物的互作关系具有明显的季节特征:冬季的互作网络组成最简单,物种竞争最激烈,物种的特异性关系、物种脆弱性和一般性最小,说明浮游生物群落的稳定性在冬季最弱.综上所述,水环境的时空差异性造成的生态位分离可能是造成浮游生物嵌套性及其互作网络季节性变化的主要机制.     

巢湖的开发与治理概况

巢湖是我国五大淡水湖之一,湖泊水面面积784km~2,位于安徽省中部。巢湖及其流域是长江下游北岸的一条主要水系,流域面积14200km~2。行政区划包括巢湖、六安两地区及合肥市,计有九县二市,人口530万人。耕地44×104hm~2,其中江淮分水岭以南丘陵地区26×104hm~2,沿江滨湖圩区18×10~4hm~2。是安徽省粮油、水禽、鱼类的主要产地之一,在全省经济发展中占有重要的位置。 建国后,在国家的大力支持下,巢湖流域进行了大规模的水利建设。长江大堤全面加固,巢湖闸、裕汐闸先后建成,控制了江洪倒灌,初步解除了江洪的威胁。但在流域治理中,尚有以下两个关键问题没有得到解决:一是巢湖洪水出路少,全流域排水出路仅有裕汐河一处,     

Effects of Anthropogenic Estrogens Nonylphenol and 17α‐Ethinylestradiol in Aquatic Model Ecosystems

Microcosm tests were conducted to investigate the effects of the estrogenic substances nonylphenol (NP) and 17α‐ethinylestradiol (EE) on aquatic ecosystems. Maximum concentrations of 9 to 120 μg L^—1 NP resp. 49 to 724 ng L^—1 EE were induced by controlled release. The controlled release method allows the establishment of a continuous concentration course. The microcosms proved to run robustly with abiotic conditions close to natural. They developed biocenosis with similar characteristics as in natural ecosystems and, considering their given level of complexity, they can be used to describe possible risks for the environment. Both tested chemicals unveiled the potential to affect the plankton communities in the tested concentration range. NP exposure caused a reduction of Cladocera and Copepoda abundances and disturbed the phytoplankton structure. A NOEC_community of 30 μg L^—1 was calculated. In the first EE study, a flood in the lake where the microcosm water was collected caused additional stress and thereby a high variability, both between the microcosms and in each microcosm over time. Probably therefore the only effect found was a reduction of Copepoda abundance. In a second EE study Cladocera and Copepoda abundances were reduced, from which the phytoplankton benefited. Although a final interpretation is difficult for results of microcosm tests, there are indications that the found effects of EE and perhaps also NP may be caused at least partially by endocrine disruptive activity.     

山西晋阳湖浮游藻类分布的时空格局及水质分析

对山西晋阳湖的浮游藻类进行了研究,共发现156种及11变种,隶属于5门,25科,67属.其中以绿藻门种类最多,达29属57种4变种;硅藻门次之,17属34种6变种;蓝藻门和裸藻门分别为15属32种1变种和5属31种,黄藻门最少,只有1属2种.秋季浮游藻类种类最多,冬季最少.浮游藻类细胞密度变化范围为2.84×10~6-2.30×10~9 cells/L,平均细胞密度为4.86×10~8 cells/L.每个季节水体的浮游植物细胞密度均已达到富营养化水平.多样性指数、均匀度指数均较低,而优势度很高,说明水体处于富营养状态,污染严重.     

Factors affecting seasonal patterns in epilimnion zooplankton community in one of the largest man-made lakes in Africa (Lake Nasser, Egypt)

The objective of the study was to determine which factors regulate zooplankton organisms along Lake Nasser. Temperature, pH, DO, conductivity, turbidity, nutrients, and zooplankton abundance were measured. Twenty-three species of zooplankton were recorded in Lake Nasser included in Copepoda, Cladocera and Rotifera. Copepoda represented the main bulk of the community. The lowest standing stock of zooplankton was noticed during spring due to the highest fish predation during this season associated with the lowest turbidity. Big difference in temperature in Lake Nasser along the year round is considered as a controlling factor related to range of tolerance of species. The oscillation of the lake water level and the different factors affect the standing stock of zooplankton in the lake. Thus, continuous monitoring of Lake Nasser biota should be undertaken to follow the changes in the ecosystem.     

Zooplankton response to the lake restoration in the drinking-water source in Meiliang Bay of subtropical eutrophic Lake Taihu, China

A 3-year ecological engineering project was carried out from 2003 to 2005 in the drinking water source in Meiliang Bay, Lake Taihu, China. The project area was divided into three zones: Zone C (outside the area), Zone B (pelagic part within the area) and Zone A (littoral part within the area). The community composition, density and biomass of zooplankton were studied as a part in the lake restoration study. Also, the abundance, biomass and composition of fish in the engineering area were annually analyzed in the littoral zone (Zone A). The average density of cladocerans decreased from the outer part to the inner part of the lake, i.e., from Zone C to Zone A, while the average density of copepod did not significantly vary among the 3 zones. The average densities of rotifer and ciliate increased from Zone C to Zone A. RDA analysis indicated that Microcystis biomass more impacted the zooplankton compositions after temperature. In Zone A, many planktivorous fishes, e.g., Coilia nasus, Hemiculter leucisculus, Pseudorasbora parva, dominated the fish community, which caused a marked decrease in the abundance of cladocerans, especially large-sized cladoceran Daphnia galeata and Daphnia obtusa. Our results suggested that both fish predation and other environmental factors such as the Microcystis bloom greatly affected the zooplankton community during the restoration of subtropical eutrophic lakes.     

太湖藻类的卫星遥感监测

利用卫星遥感监测和计算机图像处理技术,调查了太湖梅染湖区灌空间分布和影响范围,并根据提取的遥感信息对藻华现象的气象成因作为实步分析。     

安徽菜子湖浮游植物群落结构的周年变化(2010年)

2010年对菜子湖浮游植物群落结构进行了调查和分析,结果显示:(1)共鉴定浮游植物8门110属285种,不同月份浮游植物的种类组成存在极显著差异,3月份种类数最多,173种,1月份最少,105种.优势度分析显示:蓝藻存在全年高峰;硅藻存在1、5、9、11月的高峰;黄藻存在1、3、5月的高峰;绿藻存在11月的高峰,隐藻存在5月份的高峰;金藻存在1月份的高峰.不同月份浮游植物的细胞密度亦存在极显著差异,7月份最高,为(66.13±8.58)×105cells/L,1月份最低,为(12.78±0.61)×105cells/L,夏、秋季较高,冬、春季较低;不同月份浮游植物的生物量差异极显著,9月份最高,为2.80±0.17 mg/L,5月份最低,为0.72±0.03 mg/L.(2)Margalef丰度指数为1.51～3、Shannon-Weaver多样性指数为1.41～3.01、Pielou均匀度指数为0.39～0.66,各指数表现为冬、春季节大于夏、秋季节,3月份最高,7月份最低.(3)聚类分析的结果显示,月份不同影响因素不同,菜子湖水域浮游植物按群落结构特征的分组不同.(4)2007年相比,2010年浮游植物物种数有明显下降,由340种下降到285种,细胞密度明显上升,由(5.91±0.90)×105cells/L上升到(33.81±10.10)×105cells/L,群落结构变化较大,贫营养型和固着型藻类都有所减少,富营养型藻类、丝状藻类和浮游性藻类增多.     

竞争捕食作用对千岛湖浮游动物群落结构的影响

竞争与捕食作用是调节湖泊和池塘等淡水生态系统结构的主要动力,并且影响着浮游动物的群落结构和种群动态变化.为了阐明生物因素对千岛湖浮游动物群落结构的影响,于2009-2010年对千岛湖浮游动物群落结构变化规律进行调查.利用Pearson相关性分析和多元逐步回归法分析生物因素对千岛湖中浮游动物群落结构的影响.对千岛湖1999、2004、2007-2010年的鲢鳙鱼生物量和浮游动物生物量的统计分析表明,1999年鲢鳙鱼的生物量约为2004、2007-2010年年平均生物量的1/5,而轮虫和桡足类生物量变化不大,枝角类中盔形溞密度下降.鲢鳙鱼放养后浮游植物密度下降,而大型浮游动物(如盔形溞)的密度变化趋势与浮游植物相一致,因此推断鲢鳙鱼的放养将对千岛湖浮游动物群落结构产生影响.     

太湖悬浮颗粒物细菌碱性磷酸酶编码基因的分布特征

颗粒态有机磷的碱性磷酸酶矿化是水生态系统磷循环的重要环节,对细菌碱性磷酸酶编码基因的解析有利于揭示浅水富营养化湖泊有机磷矿化的微生物驱动机制.本文以太湖不同生态类型湖区悬浮颗粒物为研究对象,运用荧光定量PCR技术,探究太湖水体中悬浮颗粒物细菌碱性磷酸酶phoX和phoD基因的时空分布特征,以及影响两类基因丰度的主要环境因子.结果表明：太湖不同生态类型湖区中phoD基因丰度是phoX基因的6~42倍,且二者均存在显著的时空分布差异.6月,河口区phoX（9.18×10⁴ copies/L）和phoD（1.88×10⁶ copies/L）基因丰度均最高,其次分别为草型区、湖心区和藻型区.与6月相比,9月各湖区phoD基因丰度显著降低,而phoX基因丰度在藻型区和草型区则有所升高.9月,草型区phoX基因丰度最高（5.70×10⁴ copies/L）,河口区最低（1.49×10⁴ copies/L）.水生植物对phoX和phoD基因丰度具有重要贡献.悬浮颗粒物细菌phoX基因丰度可能被低估.溶解氧、总氮和总磷是影响太湖phoX和phoD基因丰度的主要环境因子.