Isolation of amoebae and Pseudomonas and Legionella spp. from eyewash stations.

Forty eyewash units were sampled for protozoa, bacteria, and fungi. Total heterotrophic bacterial counts on nutrient agar and R2A agar (Difco Laboratories, Detroit, Mich.) ranged from 0 to 10(5) CFU/ml, with Pseudomonas spp. being the most frequently isolated. Total counts of 10(4) and 10(8) cells per ml were obtained with the acridine orange staining procedure. All samples were examined for Legionella spp. by direct fluorescent-antibody staining and by culturing on buffered charcoal-yeast extract agar containing alpha-ketoglutarate and glycine and supplemented with cycloheximide, vancomycin, and polymyxin B. DNA-DNA hybridization was used to confirm identification of the Legionella isolates. Legionellae were detected in 35 of 40 (87.5%) samples by direct fluorescent-antibody staining, with 3 samples yielding both Legionella spp. and amoebae. Amoebae identified as Hartmannella, Vahlkampfia, Acanthamoeba, and Cochliopodium spp. were detected in 19 of 40 (47:5%) samples. Sabouraud dextrose agar was used to obtain a crude estimate of viable fungal populations, pH, hardness, and ammonia, alkalinity, chlorine, copper, and iron contents were recorded for all water samples collected from eyewash stations; 33% of the samples had greater than or equal to 10 mg of CO2 per liter. It is concluded that eyewash stations not regularly flushed and/or cleaned and used to flush traumatized eye tissue may be a source of infection and can contaminate laboratory environments via aerosol transmission.     

Examination of microbial contaminants of emergency showers and eyewash stations

To evaluate the effects of regular flushing, water from fifty emergency eyewash and shower stations was cultured for the presence of potentially pathogenic protozoa, heterotrophic bacteria, and Legionella species. This study also provided the opportunity to evaluate a commercially available molecular assay for the direct detection of Legionella sp in environmental samples. The Perkin Elmer Legionella EnviroAmp polymerase chain reaction (PCR) kit and culture on buffered charcoal yeast extract agar were used to detect Legionella species in water samples. Chemical and physical parameters of station water measured included: pH, hardness, alkalinity, turbidity, conductivity, total chlorine and assimilable organic carbon. Protozoal isolates were identified by classical identification methods, and isolates from the stations were identified as Hartmannella sp, Vexillifera sp, Vahlkampfia sp, Acanthamoeba sp, and Vanella sp. Heterotrophic plate counts ranged from 10² to 10⁶ CFU ml⁻¹ and acridine orange total counts ranged from 10³ to 10⁶ cells ml⁻¹ after regular flushing. PCR and gene probe analysis showed that 89% of the stations (eyewash and shower) were positive for Legionella species by PCR, while 6% of the samples were culture positive. These results indicate that routine flushing alone is not sufficient to control microbial contamination and disinfection must also be included in a routine maintenance program. In addition, regular maintenance, disinfection, and monitoring of emergency eyewash and shower stations is important in preventing potential secondary microbial infections by either direct inoculation or aerosol transmission. Received 02 September 1997/ Accepted in revised form 29 November 1997     

Development and evaluation of a Taqman duplex real-time PCR quantification method for reliable enumeration of Legionella pneumophila in water samples

This study describes the development and evaluation of a specific Legionella pneumophila Taqman duplex real-time PCR (qPCR) for fast and reliable quantification of this human pathogen in suspected man-made water systems. The qPCR assay was 100% specific for all L. pneumophila serogroups 1-15 with a sensitivity of 60 genome units/l and an amplification efficiency of 98%. Amplification inhibitors were detected via an exogenous internal positive control, which was amplified simultaneously with L. pneumophila DNA using its own primer and probe set. Mean recovery rates of the qPCR assay for tap water and cooling circuit water, spiked with a known number L. pneumophila bacteria, were 93.0% and 56.3%, respectively. Additionally, by using the Ultraclean Soil DNA isolation kit, we were able to remove amplification inhibitors ubiquitously present in cooling water. The practical value of our qPCR assay was evaluated through analysis of 30 water samples from showers, taps, eyewash stations, fire sprinklers and recirculation loops with qPCR and traditional culture. In conclusion, the described L. pneumophila Taqman duplex real-time assay proved to be specific, sensitive and reproducible. This makes it a promising method complementing the current time-consuming culture standard method.     

Fish species diversity as indicator of pollution in Ikpoba River, Benin City, Nigeria

The composition and distribution of fish in the Ikpoba reservoir were investigated. A total of fifty-seven species of fish belonging to thirty-nine genera and twenty-three families were recorded. Of these, 46 species were recorded at the upstream station, 35 at the reservoir, 24 at the slope and 32 at the downstream station. The percentage compositions were 81%, 61%, 42% and 56% respectively. There were 21 ubiquitous species while the distribution of the other species showed variability indicating effects of habitat condition. Species diversity indices showed that the upstream section was richer, more diverse with species more evenly distributed than the other stations. Heavy metal analysis of the dominant fish species showed higher mean levels than the background levels. Metal contamination factor and bioaccumulation quotient were variable in the fishes and in the stations but followed a ranked order of 3 > 2 > 4 > 1 by station. Comparison of stations using ANOVA revealed a significant difference (P < 0.05) between the upstream and the slope stations.     

Endogenic development of sediments in a eutrophic lake

Sedimentation in the Gouet reservoir (France), measured for 2 years at 8 stations, was maximal during summer, when river inputs were minimal. Physical and chemical conditions in the deposits indicate that the endogenous part of sedimentation was about 70% and resulted from significant diatom production. The high sedimentation rate on the bottom was favoured by the funnel morphology of the reservoir, the chronic lack of oxygen in the water column, and the repeated copper sulfate treatment. The former river meanders of the reservoir were the preferential deposit sites.     

Studies on the hydrochemistry of Kangimi reservoir, Kaduna State, Nigeria

The physicochemical characteristics of Kangimi reservoir were investigated monthly at two stations of the reservoir between July 1998 and September 1999. This was done to determine if acceptable water quality standards are being maintained in the reservoir and to assess if the water could maintain a thriving fishery. All the physicochemical parameters investigated fell within the range of allowable standards for potable waters according to the World Health Organization ( WHO, 1993 ). Alkalinity, conductivity, nitrate‐nitrogen and phosphate phosphorus showed significantly higher (P < 0.05) values during the rains, which was associated with surface runoff, whereas dissolved oxygen, hardness, transparency and chlorophyll‐a showed significantly higher values (P < 0.05) during the dry season. The reservoir was indicated to be oligotrophic. The biological significance of these findings are discussed.     

Zooplankton community of Bakreswar reservoir: Assessment and visualization of distribution pattern using self-organizing maps

Self-organizing maps, otherwise known as Kohonen-maps, are one form of unsupervised artificial neural networks that can produce two-dimensional plots from multidimensional data. This tool is especially useful in community pattern analyses and has been previously used in spatial pattern analysis with different perspectives. The present study aims to find zooplankton's community pattern in the Bakreswar reservoir ecosystem. Bakreswar reservoir is a freshwater ecosystem in the Birbhum district of West Bengal, India. The reservoir is primarily used to supply freshwater to the Bakreswar thermal power plant. However, the local villages around the reservoir depend on it for drinking water and fishing sustenance. The data used in this study was collected over two years from three different stations. Thus, in addition to describing the spatial pattern of community distribution of zooplankton groups, the temporal variation was also studied. It is observed in the study that the four major groups of zooplankton – Copepoda, Cladocera, Ostracoda, and Rotifera – react differently to the different environmental attributes. Primarily directed by the physical environmental factors, the effect of the chemical factors on the patterning is also evident from the study. Copepods are the dominant group in the system, closely followed by cladocerans and rotifers. But this observation changes at different stations and throughout the study period. The temperature profiles of the reservoir primarily direct the occurrence of ostracods and rotifers, whereas cladocerans and copepods are inclined more towards a chemical factor directive. Rotifers are dominant in the monsoon, whereas the post-monsoon and winter seasons show an increased presence of copepods and cladocerans. The overall observation that the reservoir's water quality is good, and the trophic structure is healthy is in accordance with previous studies as well.     

Exchange potentials of phosphorus between sediments and water coupled to alkaline phosphatase activity and environmental factors in an oligo-mesotrophic reservoir

We investigated the exchange potentials of phosphates at the water-sediment interface together with in situ benthic-chamber fractionated alkaline phosphatase activity and bacteria estimates during September and October 1998 at two stations: station 1, which received immediately the urban inputs from the Taounate city, and station 2, located in the centre of the Sahela reservoir (Morocco). The results showed that low oxygenation enhanced both the bacterial abundance and the alkaline phosphatase activity. Size-fractionated (0.65-100 microm) bacteria attached to dead organic matter together with algae and zooplankton contributed strongly (78%) to the total alkaline phosphatase synthesis in the two sampled stations, suggesting that attachment to organic particles stimulated phosphatase activities. The appearance of anoxic conditions and the decrease of pH supported the dissolution of particulate phosphorus and the release of soluble reactive phosphorus. This latter, together with persisting discharges of organic matter, sewage, and olive mill waste will exacerbate the eutrophication of the reservoir.     

基于多水文改变指标评价东江流域河流流态变化及其对生物多样性的影响

新丰江、枫树坝和白盆珠3座大型水库的建立对东江流域河道流量和河流流态过程有了较大改变,威胁河道下游生态系统的健康。基于广义指标生态剩余和生态赤字评价了东江流域受水库影响后流域生态需水需求目标总的盈余和缺失变化过程,基于IHA32指标计算的Do和DHRAM评价了水库对下游河段河流水文过程总的改变程度以及威胁河道生态系统健康的风险性大小,并进一步分析了对河道生物多样性的影响。研究结果如下:(1)水库对流量历时曲线(FDC)有显著影响,曲线上部下降,尾部上升,尤其体现在秋季和冬季。降水对年与夏季生态剩余影响较大,水库对各季节生态剩余和生态赤字均有较大影响:秋季和冬季生态赤字几乎为0,生态剩余显著增加。生态剩余和生态赤字与大部分IHA中32个指标具有很强的相关性,可作为衡量东江流域年和季节径流变化的生态指标。(2)龙川、河源、岭下和博罗4站点总体改变程度分别为58.48%、54.04%、54.32%和52.47%。河流流态变化导致总季节生态剩余增加并维持在较高水平,进一步引起河流生物多样性下降,并维持在较低水平。龙川和河源两站河流流态的变化对河流生态系统造成了高风险性影响,岭下和博罗两站则为中等风险。     

Long-term (30 years) dynamics of Chironomidae (Diptera) fauna in the Kuibyshev water reservoir associated with eutrophication processes

Benthos investigations were carried out in the channel and flood-plain of the Kuibyshev water reservoir during 1958–1985. Hydrobiological monitoring data obtained at 12–16 stations in all Deeps excluding littoral areas are discussed. In 1987–1900 benthofauna distribution was also studied at the Priplotinny Deep. An increase of the reservoir trophic state is reported. The observed trend was an increase of the total benthos biomass. Changes in both species and trophic structure of the chironomid community due to the eutrophication problem are discussed.     

Phytoplankton structure in two contrasting cascade reservoirs (Paranapanema River,Southeast Brazil)

A series of eleven reservoirs was constructed in the Paranapanema River, southeast Brazil, for hydropower production. The phytoplankton structure and its relations with the environmental variables were studied in two of these reservoirs: a large upstream located storage system (high water retention time) and a small run-of-river system (short water retention time). The samples were collected quarterly for two consecutive years, at four sampling stations in each reservoir. Higher phytoplankton richness was observed in the semi-lotic compartments. Higher values of diversities were observed in the upper region of the run-of-river reservoir, under the influence of the larger storage reservoir discharges, and lower values were observed in deeper layers of this same reservoir. The pronounced variation on seasonal rain precipitation and operational water releases, retention time and quota had major influence in the phytoplankton assemblages. The influence of other environmental variables was also indicated by a canonical correlation analysis. Chlamydophyceae, Dinophyceae, Zygnemaphyceae, Chrysophyceae, Chlorophyceae, Bacillariophyceae and Cyanobacteria were positively correlated with higher transparency and depth; Euglenophyceae with temperature and Cryptophyceae with total phosphorus, dissolved oxygen, conductivity, turbidity, total nitrogen and total suspended solids. The influence of the storage reservoir on the phytoplankton of the downstream run-of-river reservoir was more evident in the dry period. During the rainy period the lateral tributaries effects seems to have a higher influence, especially on the smaller studied reservoir.     

Effects of headwater impoundment and channelization on invertebrate drift

The construction of a flood control impoundment on Twitty's Creek added large numbers of organisms of limnetic origin to the stream ecosystem. However, the number of limnetic organisms per unit volume of water decreased rapidly as the distance downstream from the reservoir increased and, during most sampling periods, made up an insignificant portion of the total drift biomass at 7.2 km downstream. Factors favoring the extended downstream drift of limnetic organisms were high stream discharge and low water temperature.Several taxa of benthic organisms had much lower drift rates in the station immediately below the dam than at other stations and several taxa commonly taken at other stations were not captured immediately below the reservoir outfall. One possible explanation is that these organisms may have longer drift recruitment distances than the distance from the reservoir outfall to the sample location.A comparison of drift densities of organisms of benthic origin and benthic standing crop densities in channeled and unchanneled streams revealed that drift densities were higher in channeled streams than in unchanneled streams for most taxa of invertebrates. In addition, channeled streams appeared to have lower benthic standing crops than unchanneled streams for most taxa of invertebrates.In stream sections impacted by either channelization or the Twitty Lake outfall, the energy dynamics of the stream ecosystems were altered by increased density of drifting invertebrates. From the standpoint of increasing food availability to the fish fauna of the stream, these changes would appear to benefit drift feeding species and negatively impact bottom feeding species.     

Spatial and temporal patterns of temperature,alkalinity, dissolved oxygen and conductivity in an oligo-mesotrophic,deep-storage reservoir in central Texas

Impoundment behavior was determined for alkalinity, temperature, dissolved oxygen, and conductivity from stations located along the length of a bottom-draining, oligo-mesotrophic, hardwater, deep-storage reservoir located in central Texas. The epilimnion deepened the length of the reservoir throughout the summer as a result of drawdown. Bicarbonate alkalinity and conductivity exhibited both longitudinal and vertical stratification. Alkalinity and conductivity in the epilimnion decreased from the riverine reach downreservoir to the dam. This longitudinal progression was attributed to inflow and photosynthetically induced epilimnetic decalcification.Hypolimnetic anoxic conditions first occurred in the sedimentation zone in the upreservoir and riverine reaches and then developed in a downreservoir pattern as summer progressed as a result of drawdown. Alkalinity and conductivity in the hypolimnion increased during anoxic conditions and consequently increased in a downreservoir progression.     

Spatial and Seasonal Variation in a Reservoir Sedimentary Microbial Community as Determined by Phospholipid Analysis

Sediment samples were collected monthly from Acton Lake, a eutrophic reservoir located in an agricultural region of southwestern Ohio, from three stations (River, Middle, and Dam) during the period May 1995 through January 1997. Sedimentary microbial biomass and community structures from these stations were studied using phospholipid analysis. At the River and Middle stations, the water column remained aerobic throughout the year, whereas the water overlying the Dam station sediments became anaerobic during summer stratification. Sedimentary microbial biomass at the River and Middle stations, as measured by the phospholipid phosphate (PLP) method, ranged from 225 to 450 nmol PLP g?1 d.w. (dry weight). Sedimentary microbial biomass at the Dam station was typically greater and ranged from 500 to 1,500 nmol PLP g?1 d.w. Principal component analysis of phospholipid fatty acid (PLFA) profiles indicated that the sedimentary microbial communities at all three stations displayed seasonal patterns of change. Among these patterns of change was a shift from aerobic microorganisms during times of cold water to anaerobic microorganisms during times of warm water. The Dam station differed from the River and Middle stations in that sediments from this station had disproportionately more polyenoic fatty acids, whereas sediments from the River and Middle stations had disproportionately more bacterial fatty acids. These data suggest that the Dam station may be a depositional zone for microeukaryotic phytoplankton produced in the overlying water column. These findings have implications for the understanding of carbon flux in reservoirs and preservation of organic matter in aquatic systems.     

Dispersion of Anopheles gambiae s.l. in an urban zone of Ouagadougou (Burkina Faso)

Dispersion of Anopheles gambiae s.l. from larval breeding places was examined in the town of Ougadougou, Burkina Faso. A suitable study area was chosen, characterized by high concentration of larval breeding places along a water reservoir. Mosquito density per room was calculated from the results of pyrethrum spray catches carried out on a series of seven groups of collecting stations along a transect from 100 to 1050 m from the water reservoir area. High density and uniform distribution of houses and human host in the urban area appear associated with a remarkably low degree of dispersion since most of An. gambiae s.l. were collected within 200 m (males) or 300 m (females) from the breeding sites. Malaria transmission is consequently very focal in these conditions.     

Importance of the ratios of the forms of nutrients for assessment of the modern state of Rybinsk Reservoir

Various ratios of nutrient forms have been analyzed on the basis of the materials collected in Rybinsk Reservoir in the years 2001 to 2011. The analysis was used for assessment of the modern state of the reservoir. The total nitrogen (TN) to total phosphorus (TP) ratio is the most informative parameter. During the study period at all sampling stations, the average value of this ratio was 17.0. This value indicates the lack of limitation of development of phytoplankton by these nutrients. High values of the absolute concentration of nitrate nitrogen and its proportion in the total mineral nitrogen (which are important indicators of increasing eutrophication), as well as the percentage of inorganic phosphorus, were revealed in Volzhskii reach and the upper part of Sheksninskii reach of the reservoir. These values indicate the eutrophic state of the above areas of the reservoir.     

三峡水库蓄水后长江上游鱼类群聚沿河流-水库梯度的空间格局

研究对2005—2012年长江上游合江、木洞、万州和秭归江段的鱼类群聚结构进行了调查, 以分析三峡水库蓄水后长江上游鱼类群聚沿河流-水库梯度的空间格局。结果显示, 在三峡蓄水后, 在合江至秭归江段累计采集到土著鱼类368706尾, 合计132种, 隶属于17科, 其中鲤科鱼类为优势类群。沿河流-水库纵向梯度, 土著鱼类物种数下降而外来鱼类物种数增加。对应分析表明, 合江至秭归江段的鱼类群聚呈现出明显分化: 库区以上河段鱼类组成以流水性鱼类为主, 库区鱼类则以静水缓流型为主。指示物种分析进一步指出, 河流区鱼类以犁头鳅(Lepturichthys fimbriata)、红唇薄鳅(Leptobotia rubrilabris)、圆口铜鱼(Coreius guichenoti)、圆筒吻(Rhinogobio cylindricus)等22种鱼类为指示物种, 其功能群特征表现为偏好流水生境、生活史为均衡主义及食性为昆虫食性; 库区鱼类以宽口光唇鱼(Acrossocheilus monticolus)、宽鳍鱲(Zacco platypus)、鳊(Parabramis pekinensis)、鳙(Aristichthys nobilis)等16种鱼类为指示物种, 其功能群特征表现为偏好静水生境、食性为草食性或浮游食性。以上研究表明, 三峡水库蓄水导致的水环境变化是影响长江上游鱼类纵向格局的主要驱动力。建议相关管理部门根据不同河段鱼类群聚特征制定不同的渔业管理措施, 如保护土著鱼类资源、控制外来入侵鱼类。     

Comparative study on macroinvertebrate communities along a reservoir cascade in Xiangxi River Basin

Three cascade reservoirs (Gudongkou Reservoir 1 (GR1), Gudongkou Reservoir 2 (GR2), and Xiangxi Bay of Three-Gorge Reservoir in Xiangxi River Basin, China were selected to investigate macroinvertebrate ecology in a cascade reservoir system. Principal Components Analysis (PCA) implied that water quality was degrading along the reservoir cascade. Non-metric Multidimensional Scaling (NMS) showed that sampling stations located in the lacustrine zone of a reservoir are representatives in comparing macroinvertebrate assemblages along the reservoir cascade. Oligochaetes were numerically dominant in both GR1 and Xiangxi Bay, and chironomids were dominant in GR2. A similar pattern was also exhibited in taxon composition. Benthic assemblages of the 3 reservoirs were all dominated by pollution-tolerant taxa in spite of their differences in water quality. Canonical Correspondence Analysis (CCA) disclosed that turbidity influenced the benthic assemblages significantly. Total organic carbon (TOC)/Turbidity was applied to determine the influence of organic matter on turbidity. The ratio in GR2 was the lowest among the 3 reservoirs, which implicated that the influence of organic matter on turbidity was smaller in GR2 than in the other 2 reservoirs, suggesting that inorganic matter contributed substantially to the turbidity of GR2.     

Toxicological and teratogenic assessment of bottom sediments from the Rybinsk Reservoir

The toxicity of bottom sediments (BSs) from different parts of the Rybinsk Reservoir has been determined by biotesting. Neither acute nor chronic toxicity are detected for ceriodaphnia Ceriodaphnia affinis Lillijeborg in tests with water extracts of sediments from all the investigated stations. The relative number of Chironomus riparius Meigen larvae with deformed mouth structures in the specimens exposed to the BSs of the reservoir is higher than in the control. Abnormalities of the mentum and mandibules (heavily chitinized structures) were the most often observed pathomorphological disturbances. The results of this study suggest that BSs from the stations located near the Cherepovets Industrial Complex (CIC) may be classified as contaminated.     

Comparative study on macroinvertebrate communities along a reservoir cascade in Xiangxi River Basin

Three cascade reservoirs (Gudongkou Reservoir 1 (GR1), Gudongkou Reservoir 2 (GR2), and Xiangxi Bay of Three-Gorge Reservoir in Xiangxi River Basin, China were selected to investigate macroinvertebrate ecology in a cascade reservoir system. Principal Components Analysis (PCA) implied that water quality was degrading along the reservoir cascade. Non-metric Multidimensional Scaling (NMS) showed that sampling stations located in the lacustrine zone of a reservoir are representatives in comparing macroinvertebrate assemblages along the reservoir cascade. Oligochaetes were numerically dominant in both GR1 and Xiangxi Bay, and chironomids were dominant in GR2. A similar pattern was also exhibited in taxon composition. Benthic assemblages of the 3 reservoirs were all dominated by pollution-tolerant taxa in spite of their differences in water quality. Canonical Correspondence Analysis (CCA) disclosed that turbidity influenced the benthic assemblages significantly. Total organic carbon (TOC)/Turbidity was applied to determine the influence of organic matter on turbidity. The ratio in GR2 was the lowest among the 3 reservoirs, which implicated that the influence of organic matter on turbidity was smaller in GR2 than in the other 2 reservoirs, suggesting that inorganic matter contributed substantially to the turbidity of GR2.