The Structure of the Phytoplankton Community and the Dynamics of its Biomass in the Lake Jaisamand,Rajasthan

Phytoplankton in the lake Jaisamand consists of 52 taxa, out of which 25 belong to Chlorophyceae, 12 to Bacillariophyceae, 2 to Euglenophyceae, 1 to Xanthophyceae and 12 to Myxophyceae. The highest phytoplankton density occurred in July, i.e. in the beginning of monsoon, and the lowest in November. The dominant Chlorophyceae were Spirogyra elliptica, Closterium and Hydrodictyon. Navicula lanceolata, Pinnularia viridis and Synedra ulna were dominant amongst Diatoms. Xanthophyceae was represented by a single species of the genus Botryococcus and Euglenophyceae by Phacus longicauda and Euglena viridis. The dominant Myxophyceae were Microcystis aeruginosa and M. flosaquae. Under the stratified conditions, the near bottom waters got depleted of phytoplankton. The overall trend in the quality and quantity of phytoplankton indicated that temperature and nutrients had an influence on the rate of plankton production.     

Seasonal Variation in Primary Productivity and its Interrelationship with Chlorophyll in the Lake Jaisamand (Rajasthan,India)

Lake Jaisamand near Udaipur (Rajasthan) is one of the oldest man-made lakes in India. The primary productivity of the lake showed a bimodal pattern with a first peak of a higher magnitude in July (7.605 g/m₂d C) and the second of a lower magnitude (5.851 g/m₂ dC) in December. The minimum production was 2.455 g/m₂ dC in November. The chlorophyll values were high during low water levels of summer and low during monsoon months when the water level rises, thereby dispersing the phytoplankton biomass and decreasing its density per unit of water volume. From the results obtained it appears that beside temperature and transparency, the trophogenic area and seasonal water level fluctuations have a considerable influence on the primary productivity in this lake. Based on annual production rates and chlorophyll values lake Jaisamand could be regarded as an eutrophic waterbody.     

滆湖水生植物生物量、演替规律及合理利用

用五种不同的方法估算了滆湖水生植物的生物量,比较分析了全湖断面生物量和群丛生物量.分三个方面对滆湖水生植物的演替规律进行了讨论,对草型湖泊水生植物的合理利用进行了探讨.初步提出了草型湖泊估算渔产潜力的公式.在分析引起水生植物生物量变化的原因的基础上,提出了若干合理利用植物资源的建议.     

滆湖水生植物生物量、演替规律及合理利用

用五种不同的方法估算了滆湖水生植物的生物量,比较分析了全湖断面生物量和群丛生物量．分三个方面对滆湖水生植物的演替规律进行了讨论,对草型湖泊水生植物的合理利用进行了探讨．初步提出了草型湖泊估算渔产潜力的公式．在分析引起水生植物生物量变化的原因的基础上,提出了若干合理利用植物资源的建议．     

惠州西湖浮游动物及其与水质的关系

通过对惠州西湖五个子湖的浮游动物情况进行调查,共检出浮游动物55种,其中轮虫38种,枝角类10种,桡足类7种,主要优势种为广生多肢轮虫（Polyarthra trigla）、长三肢轮虫（Filinia longiseta）、裂足臂尾轮虫（Brachionus diversicorn＆）、剪形臂尾轮虫（B.forficula）、角突臂尾轮虫（B.angularis）、萼花臂尾轮虫（B.calyciflorus）、前节晶囊轮虫（Asplanchna priodonta）、刺盖异尾轮虫（T.capucina）、微型裸腹潘（Moina micrura）、温中剑水蚤（Mesocyclops thermocyclopoides）等,多为富营养化指示种,各子湖浮游动物检出丰度处于147.3到726.1 ind／L之间,其中轮虫丰度占据优势,浮游动物趋向小型化,结合浮游动物丰度与水质指标进行相关分析结果表明,浮游动物的分布情况与水体水质特征关系密切。     

Population Dynamics,Biomass and Biomass Production of Eudiaptomus gracilis (G. O. SARS) in Two Water Areas of Differing Trophic State of Lake Balaton (Hungary)

Population dynamics and production of Eudiaptomus gracilis (G. O. Sars) were investigated in two basins of differing water quality of Lake Balaton from February through December, 1977. One of the basins (Keszthely) is considered to be hypertrophic. the other (Tihany) moderately eutrophic. Plankton samples were collected at weekly intervals. The fecundity was 9.61 ± 3.39 at Tihany, and 16.53 ± 3.60 at Keszthely. The difference between the two basins was significant (P<0.1%). At Tihany the average number of eggs per m³ was lower by 36% relative to Keszthety. The number of nauplii differed only a little between the two basins with the exception of April, when at Tihany the amount of individuals was nearly two times as great as at Keszthely. In the case of younger copepodites (Stages I … III) the difference in individual numbers between the two areas of water was marked from February to June, while in other periods it proved to be small. At Tihany, the number of young copepodites was greater by 8%, on the average, than at Keszthely. The amount of larger copepodites (IV … V) relative to the total number of younger individuals of the population was by 63% resp. 77% smaller at Tihany and Keszthely. In the whole period of these studies the number of adults was less by 44% at Keszthely than at Tihany. Their amount relative to that of nauplii was smaller by 6% at Tihany and by 45% at Keszthely. At Tihany, the population biomass was at a constant high level during winter and spring (40 to 50 mg/m³), in summer values being lower (15 … 35 mg/m³). In the Keszthely-Basin biomass showed more extreme changes, reaching a peak as high as 40 … 43 mg/m³ in April and November, but hardly exceeding 6 mg during July–August. During the period of investigation, total biomass in the Tihany-Basin was 342 mg/m³, at Keszthely 204 mg/m³. Net biomass production-two methods for estimation having been used – was higher in the Tihany-Basin (17.25 and 33.83 KJ/m²), while in the Keszthely-Basin it was considerably lower (13.06 and 9.50 KJ/m²).     

Rethinking rehabilitation: socio-ecology of tanks in Rajasthan,north-west India

In the arid and semi-arid Indian state of Rajasthan, tanks and ponds have been a mainstay of rural communities for centuries. This paper assesses a rehabilitation strategy proposed for 1200 large tanks. It argues that treating tanks only as flow irrigation systems is very likely to result in a flawed strategy. As the experience of NGOs work shows, Rajasthan's tanks belong more to the watershed development domain than to the irrigation domain and a strategy that views tanks as multi-use socio-ecological constructs, and which recognizes varied stakeholder groups is more likely to enhance the social value of tanks.     

Limnological Studies in a Subtropical System (Lake Sattal,India)

A limnological study was carried out in the subtropical Lake Sattal (Kumaun Himalaya) during 1979. The lake was thermally stratified during warm months and a low percentage saturation of dissolved oxygen occurred in the bottom waters. Two maxima of phytoplankton occurred in the Eastern basin in contrast to only one in the Western basin. The peak in the latter developed more than a month (October) after the second peak in the former (August). Bacillariophyceae contributed highest in the Western basin (43.2%) whereas the Dinophyceae had the least share in the Eastern basin (8.0%). Most of the dominant phytoplankters were: Synedra ulna, Fragilaria, Gymnodinium, Crucigenia and Closteridium siamensis. Interestingly, blue-green alga Nostoc, dominated for some time in autumn. A total of 12 genera of rotifers, 6 genera of cladocerans and 1 genus of copepods were found in Lake Sattal basins. Dominant zooplankters included Keratella, Cyclops, Anuraeopsis, Polyarthra and Trichocerca, and there is a high ratio of rotifers to copepods and cladocerans. On comparing the averaged values of both the basins, the Eastern basin showed a 64% larger population of zooplankton than the Western basin. A comparison is made with the plankton of the other subtropical lake-systems of this region.     

武汉市南湖大型底栖动物的群落结构

在分析企业环境行为类型及决策机制的基础上,认为内外环境因素的综合作用促成了企业环境行 为的发生．据此,通过相关性和主成分分析对太湖流域印染企业环境行为影响因素进行选择,并构建了环 境行为决策数量模型,结果表明：私营合资企业环保投入水平高于国有集体企业;中型企业环保投入高于小 型企业,此外,企业环境行为演变也受政府和经济环境制约．最后提出了优化企业环境行为的对策,即加快 企业改制,强化用地供应管理,改革排污费制度以及规划产业布局．     

千岛湖轮虫群落结构及水质生态学评价

研究了一大型深水湖泊——千岛湖轮虫的群落结构,包括种类组成、种群动态、现存量,并用轮虫污染指示种类、E/O值和QB/T值评价千岛湖水质和营养状况. 在一周年的研究中,共发现轮虫70种,污染指示轮虫41种,其中寡污-β中污带、β中污带和β-α中污带污染指示种类分别占总指示轮虫的41. 5%、36. 5%和22. 0%. 根据年平均密度,优势种分别为螺形龟甲轮虫(Keratella cochlearis)、等刺异尾轮虫(Trichocerca similis)和针簇多肢轮虫(Polyarthra trigla). 轮虫生物量的时空变化由晶囊轮虫属(Asplanchna)的轮虫决定,以5月份的Ⅰ站和Ⅱ站生物量较高. 轮虫的E/O值变幅为0. 29-0. 62,平均0. 46;QB/T值变幅为0. 17-1. 50,平均0. 68. 相关分析表明:E/O值和QB/T值与水体透明度之间分别呈显著和极显著的负相关关系,相关系数分别达0. 7182和0. 7747. 与大型浅水湖泊相比,千岛湖轮虫群落结构具有种类数较多、密度和生物量小、QB/T值低的特征. 根据指示生物法和生物指数法评价千岛湖水质和营养类型,千岛湖为寡污-β中污(贫-中营养型)水体,其中,Ⅰ站、Ⅱ站和Ⅴ站为β中污(中营养型),其余各站均为寡污-β中污(贫营养型)水体.     

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.     

Zooplankton Community Structure of Çavuşcu and Eber Lakes in Central Anatolia Struktur von Zooplankton-Gemeinschaften im Çavuşcu Lake und im Eber Lake in Zentralanatolien

This research has been undertaken to determine the zooplanktonic fauna (Rotatoria, Crustacea) and their seasonal distribution in two lakes with different characters. Çavu?cu lake has a surface area of 1000 ha with a maximum depth of 4 m and is classified as an oligo-mesotrophic lake. Eber lake has a surface area of 5200…17000 ha with a maximum depth of 2.5 m and is classified as an eutrophic lake. Zooplankton samples have been collected seasonally between the period of 1990 to 1993 from three stations with a zooplankton net of 44 μm mesh size. From Çavu?cu lake totally 50 Rotifera, 2 Copepoda, and 7 Cladocera species; 49 phytoplankton genera and 5 macrophytes have been identified while, 37 Rotifera, 3 Copepoda, 5 Cladocera; 45 phytoplankton genera and 6 macrophytes have been identified from Eber lake. 13 new rotifer records for the Turkey were found, which were Brachionus diversicornis, Macrochaetus collinsi, Lecane stichaeta, Cephalodella sterea, Cephalodella auriculata, Trichocerca iernis, Encentrum saundersiae. Pompholyx complanata, Floscularia ringens, Conochilus natans, Filinia pejleri, Rotaria rotatoria, and Philodina megalotrocha.     

春秋两季鄱阳湖浮游动物的编目、数量分布与变动

分析鉴定了1999年春、秋两季,在鄱阳湖区8个断面24个采样站采得的水样．共观察到各类浮游动物共150种．其中轮虫动物物种最为丰富,为96种,占总种数的64．0％,且单位体积的数量亦呈明显优势,说明轮虫动物是该湖区浮游动物的优势类群;其次为原生动物．24个采样站中,原生动物、轮虫动物、枝角类、桡足类这四类浮游动物个体数量分布的差异极大,其中第10、12、13和23号站中的个体数量较高,超过100ind／L最大数量出现在13号站,个体数量高达1101．60ind／L鄱阳湖浮游动物的数量有明显的季节变动,尤属轮虫的变动最大．本次调查中轮虫和枝角类的数量春季大于秋季,而原生动物和桡足类则秋季大于春季．     

新疆布伦托海轮虫群落结构及其与环境因子的关系

本文于2006年秋至2008年夏,对新疆布伦托海轮虫的群落组成、时空分布及其与环境因子的相关性进行了系统的调查.结果表明,本次调查采集到布伦托海轮虫30种,主要优势种有针簇多枝轮虫(Polyarthra trigla)、长三肢轮虫(Filina longiseta)、奇异六腕轮虫(Hexarthra mira)、方形臂...     

南四湖底栖动物群落结构特征及其与环境因子的关系

为了解南四湖大型底栖动物群落结构特征及其与环境因子的关系,于2010年对南四湖15个采样点的底栖动物和生态环境进行4次调查研究.结果表明:共检出底栖动物23种,栖息密度和生物量为311.57 ind./m2和44.39 g/m2;群落物种优势度指数较高,优势种集中于羽摇蚊幼虫(Chironomus plumosus)和霍甫水丝蚓(Limnodrilus hoffmeisteri),分别占个体总数的77.45%和11.39%;水生植物生物量为1613 g/m2,盖度为33%,存在显著季节变化与空间差异,但底栖动物群落特征与之无显著相关性;南四湖水域主要污染物为氮,其次为磷,最后为高锰酸钾指数;2010年度除底栖动物物种数与水体CODMn含量呈显著负相关以及栖息密度与水体相关加权综合营养状态指数呈显著正相关外,其余底栖动物群落特征与水生植物、水质理化指标及营养状态间均未表现出显著相关性;依据底栖动物Goodnight-Whitley生物指数和水质相关加权综合营养状态指数评价结果,南四湖除局部区域受到严重的外源污染外,总体为清洁-中度营养类型.     

Zooplankton Size Structure in the Kolsay Mountain Lakes (Kungei Alatau,Southeastern Kazakhstan) and Its Relationships with Environmental Factors

Water Resources - The size structure of zooplankton in Kolsay Lakes was characterized with the use of the values of Clarke W-statistic, ?-Shannon–Weaver, and the average individual mass...     

To the Problem of Bioindication of Oil Pollution of Freshwater Limnic Ecosystems Using Zooplankton on the Example of Lake Samotlor (KhMAO)

Water Resources - It is shown that the presence of petroleum hydrocarbons in water may have both a depressing and a stimulating effect on the development of certain species of zooplankton. The...     

太湖水动力学三维数值试验研究——4.保守物质输移扩散

物质输移扩散规律是大型浅水湖泊水质变化机理研究的重要内容,对湖泊水环境的管理具有重要的现实意义,本文在太湖湖流三维模型研究成果的基础上,创建了太湖保守物质输移扩散三维数值模型,并用之模拟了1997年冬季1～2月太湖总磷含量的变化,计算结果表明,模型计算值与观测值吻合,本文所建的保守物质输移扩散模型,可用于冬季太湖营养盐含量时空变化的计算。