Prevalence and distribution of Aeromonas hydrophila in the United States.

The abundance of Aeromonas hydrophila was measured in 147 natural aquatic habitats in 30 states and Puerto Rico. Viable cell counts were used to estimate density at all sites by using Rimler-Shotts medium, a differential presumptive medium for A. hydrophila. Temperature, pH, conductivity, salinity, and turbidity were measured simultaneously with water sample collection. The density of A. hydrophila was higher in lotic than in lentic systems. Saline systems had higher densities of A. hydrophila than did freshwater systems. A. hydrophila could not be isolated from extremely saline, thermal, or polluted waters, even though it was found over wide ranges of salinity, conductivity, temperature, pH, and turbidity. Of the water quality parameters measured, only conductivity was significantly regressed with density of A. hydrophila.     

Field and laboratory studies on water conditions affecting the potency of VectoBac (Bacillus thuringiensis serotype H-14) against larvae of the blackfly, Simulium damnosum

River water conditions that might influence the efficacy of VectoBac, a formulation of the microbial insecticide Bacillus thuringiensis H-14 Berliner against Simulium damnosum sensu lato Theobald (Diptera: Simuliidae) larvae were investigated. A standard formulation was assayed 130 times over 15 months using a mini-gutter system at a field station beside the River Pra in Ghana. The lethal concentration (LC) values, river temperature, conductivity, turbidity and pH were analysed using univariate and multivariate statistics to identify which of these parameters influenced its performance. River temperature, conductivity and turbidity (in that order) were identified as having direct effects on the potency of VectoBac. Water temperature and conductivity were negatively correlated, whereas turbidity and pH were positively correlated with LC values. Analyses of river water samples revealed that despite observed differences in total solids, sodium and potassium cations and chloride concentrations, all the parameters measured did not differ significantly between wet and dry seasons. A simple method for rearing S. damnosum s.l. in the laboratory was then adopted to study the effect of conductivity on potency of VectoBac under controlled conditions. Increasing the conductivity of the water medium up to 3,000 microS enhanced potency by about 42%, whereas increasing that of the insecticide alone raised it by 37%. The results obtained suggest that for effective use of VectoBac for blackfly control in West Africa, river temperature, conductivity and turbidity should be taken into consideration, perhaps by only selecting rivers with optimal conditions for treatment. The laboratory-based system developed for assaying the product overcomes the vagaries associated with field conditions and also the demand for huge logistic requirements of the mini-gutter system, which has to be sited near rivers.     

Impact of flood events on dolphin occupancy patterns

The aim of this study was to assess potential impacts of water quality changes associated with floods on the occupancy of Indo‐Pacific bottlenose dolphins (Tursiops aduncus) in two subtropical estuaries in Australia. Boat‐based surveys were conducted in the Clarence River estuary (CR) and Richmond River estuaries (RR) over 3 yr. Principal components analysis (PCA) showed that when the dolphins were absent from the estuaries, three water quality components were extracted in the CR and two components in the RR. The PCA¹ component included high loadings for salinity, turbidity, and pH for the CR (46%); and salinity, turbidity, pH, and dissolved oxygen (DO) for the RR (51%). Randomization tests showed that dolphins abandoned both estuaries at times of lower salinity, and during periods of higher turbidity and of lower levels of pH and dissolved oxygen in the RR that were associated with floods. The time until dolphins returned to the estuary postflood depended on the length and severity of the flood, but generally dolphins were observed in waters with salinity levels above 29‰. Their delayed return postflood could be for their physiological health, or because their prey returned to the estuaries under these higher salinity conditions, or more likely a combination of both factors.     

枯水季节赣江近岸水洼与浅滩中浮游动物的群落差异

为探究水洼与邻近浅滩中浮游动物群落是否存在差异, 于2015年1月22日和3月1日, 选择赣江南昌段的3个水洼和邻近浅滩采集浮游动物, 对浮游动物的物种组成、密度、生物量、多样性指数和群落结构进行比较研究。通过单因子方差分析(One-way ANOVA)检验水洼与浅滩中水环境因子及浮游动物密度和生物量的差异。使用非度量多维尺度分析(Non-metric multi-dimensional scaling, NMDS)和群落相似性分析(Analysis of similarity, ANOSIM)对暂时性水洼及邻近浅滩的浮游动物群落进行排序。1月和3月共发现浮游动物44种, 轮虫有30种, 占总捕获数的68%。枝角类和桡足类各有7种, 分别占总捕获数的16%。相对重要性指数(Index of relative importance, IRI)大于1000的优势物种有5种, 分别为汤匙华哲水蚤Sinocalanus dorrii、长肢多肢轮虫Polyarthra dolichoptera、桡足类无节幼体Copepod nauplii、角突臂尾轮虫Brachionus angularis和长圆疣毛轮虫Synchaeta oblonga。单因子方差分析表明, 1月份水洼的水深、电导率和总氮含量显著高于浅滩(P<0.05), 浅滩的水温、pH、溶解氧、浊度和总磷含量略高于水洼。3月份水洼的水深、pH和总氮含量略高于浅滩, 浅滩的溶解氧、浊度和总磷含量较水洼高, 水温和电导率在2种水体中非常接近。1月份水洼中浮游动物的密度(7.90 ind./L)和生物量(7.78 μg/L)均低于浅滩(9.34 ind./L, 19.03 μg/L), 3月份水洼中浮游动物的密度(24.27 ind./L)和生物量(332.14 μg/L)均高于浅滩(22.86 ind./L, 146.10 μg/L)。浅滩中浮游动物的多样性指数(H′)、均匀度指数(J)和物种丰富度指数(D)均大于水洼。非度量多维尺度分析和群落相似性分析表明, 仅1月份水洼与浅滩的浮游动物群落结构具有边缘显著差异(P=0.067), 可大致划分为2个: 水洼群落和浅滩群落。3月份由于水位上涨, 研究的水洼与赣江河道处于连通或半连通状态, 2种生境中浮游动物群落结构无显著差异(P=0.313)。斯皮尔曼相关分析(Spearman correlation coefficient)发现水深和溶解氧是导致水洼和浅滩中浮游动物密度差异的主要环境因子。2种生境中浮游动物的密度与pH、电导率、总氮和总磷均具有显著相关性(P<0.05)。     

Aeromonas hydrophila: Ecology and Toxigenicity of Isolates from an Estuary

A microbiological survey of Aeromonas hydrophila in Chesapeake Bay and its tributaries showed that this species is ubiquitous, occurring in numbers ranging from <0.3/l to 5 × 10³/ml in the water column and ca. 4.6 × 10²/g in sediment. It was recovered from water samples collected at several locations in Chesapeake Bay representing various salinity regimes, but the numbers of A. hydrophila in higher salinity water, i.e. 15^O/OO, were low. Results of stepwise multiple linear regression analysis showed that concentrations of A. hydrophila were correlated with total, aerobic, viable, heterotrophic, bacterial counts, and, in addition, were inversely related to salinity and to concentration of dissolved oxygen. Seasonal occurrence was recorded, with fewer strains of A. hydrophila encountered during the winter months. The potential pathogenicity of A. hydrophila strains isolated from Chesapeake Bay was estimated by testing selected isolates for toxigenicity, using the Y-1 adrenal cell assay. Of 116 isolates tested, 83 (71%) produced a cytotoxic response, a characteristic found to be correlated with the lysine decarboxylase and Voges-Proskauer reactions. Eight of 11 strains tested, which elicited fluid accumulation in the rabbit ligated ileal loop assay, also provoked a cytotoxic reaction in the Y-l adrenal cell assay. Results of the study indicate that large numbers of toxigenic A. hydrophila can be found in an estuary and such strains may be pathogenic for man and/or animals.     

Characteristics of Anopheles arabiensis larval habitats in Tubu village,Botswana

Documented information on the ecology of larval habitats in Botswana is lacking but is critical for larval control programs. Therefore, this study determined the characteristics of these habitats and the influences of biotic and abiotic factors in Tubu village, Botswana. Eight water bodies were sampled between January and December, 2013. The aquatic vegetation and invertebrate species present were characterized. Water parameters measured were turbidity (NTU), conductivity (μS/cm), oxygen (mg/l), and pH. Larval densities of Anopheles arabiensis mosquitoes and their correlation with abiotic factors were determined. Larval breeding was associated with ‘short’ aquatic vegetation, a variety of habitats fed by both rainfall and flood waters and sites with predators and competitors. The monthly mean (± SE_mean) larval density was 8.16±1.33. The monthly mean (±SE_mean) pH, conductivity, oxygen, and turbidity were 7.65±0.13, 1152.834±69.171, 5.59±1.33, and 323.421±33.801, respectively. There was a significant negative correlation between larval density and conductivity (r = ‐0.839; p < 0.01), while a significant positive correlation occurred between turbidity and larval density (r = 0.685; p < 0.05). Oxygen (r = 0.140; p > 0.05) and pH (r = 0.252; p > 0.05) were not correlated with larval density. Floods and diversified breeding sites contributed to prolonged and prolific larval breeding. ‘Short’ aquatic vegetation and predator‐infested waters offered suitable environments for larval breeding. Turbidity and conductivity were good indicators for potential breeding places and can be used as early warning indices for predicting larval production levels.     

Ionic content as a factor influencing turbidity in two floodplain lakes after a flood

The relationship between ionic content, measured as electrical conductivity, and turbidity resulting from inorganic suspensoids was investigated experimentally on the Ponogolo river floodplain. Turbid floodwaters were mixed in various proportions with clear lake water of high conductivity and settling rates determined. For the conductivity range 215–1084 μS cm⁻¹ there was an increase in the maximum settling rate from 3.3–20.6% h⁻¹. These data were compared with observations made, in a turbid lake of low conductivity and a clear water lake of high conductivity, during and after a flood. The importance of lake morphology, flushing and conductivity as determinants of turbidity and light attenuation in the floodplain lakes is discussed. The relevance of these observations to the understanding of turbidity in other systems is considered.     

Comparative studies on Aeromonas strains isolated from Lakes Balaton (Hungary) and Fertó/Neusiedlersee (Hungary)

Ecological and comparative taxonomic investigations were carried out on 49 Aeromonas strains isolated from water samples of two moderately alkaline lakes of Hungary, Lake Balaton and Lake Fertó/Neusiedlersee together with 3 authentic strains of Aeromonas hydrophila. Five phena were created at greater than 92% similarity value using the UPGMA method with the Jaccard coefficient. Strains isolated from Lake Balaton were determined as A. hydrophila, while strains originated from Lake Fertó were identified as A. hydrophila and A. sobria. The Fertó isolates of A. hydrophila grew only at higher salt concentration (5% NaCl). This might be an adaptation to the higher salt contents in the water of Lake Fertó. However, no specific differences were detected in their behaviour against alkaline pH values. The wide range of their degradative enzymes indicate that aeromonads can play an important role in nutrient cycling.     

Application of ribotyping for differentiating aeromonads isolated from clinical and environmental sources.

We have investigated the usefulness of ribotyping for the differentiation of aeromonads isolated from five patients with gastroenteritis and from the source water, treatment plant, and distribution system of a small public water supply. Aeromonas hydrophila and Aeromonas caviae were isolated from fecal specimens preserved in Cary-Blair transport medium by using blood ampicillin agar or alkaline peptone water (pH 8.4) subcultured to blood ampicillin agar plates. A. hydrophila, Aeromonas sobria, and A. caviae were isolated from duplicate 100-ml water samples by the membrane filter technique by using ampicillin dextrin agar for quantitative determination of growth and alkaline peptone water enrichment for detection of the presence or absence of aeromonads below the detection limit of the membrane filter method. In addition, free chlorine residuals and pH values were determined for all water samples and heterotrophic plate counts and total and fecal coliform analyses were performed on them. Ribotyping patterns of aeromonads recovered from well 1, detention basin, sand filter, softener, and distribution samples were compared with those of the five clinical isolates. All patient strains were unique; however, identical ribotypes of A. hydrophila and A. sobria isolated from multiple sites in the water system indicated colonization of a well, sand filters, and the softener, with the potential for sporadic contamination of distribution water. Plant operational deficiencies were noted and corrected. Ribotyping can effectively differentiate otherwise indistinguishable strains of bacteria, thus providing a powerful tool for investigation of waterborne diseases and bacteriological problems within water treatment plants and distribution systems.     

Application of ribotyping for differentiating aeromonads isolated from clinical and environmental sources.

We have investigated the usefulness of ribotyping for the differentiation of aeromonads isolated from five patients with gastroenteritis and from the source water, treatment plant, and distribution system of a small public water supply. Aeromonas hydrophila and Aeromonas caviae were isolated from fecal specimens preserved in Cary-Blair transport medium by using blood ampicillin agar or alkaline peptone water (pH 8.4) subcultured to blood ampicillin agar plates. A. hydrophila, Aeromonas sobria, and A. caviae were isolated from duplicate 100-ml water samples by the membrane filter technique by using ampicillin dextrin agar for quantitative determination of growth and alkaline peptone water enrichment for detection of the presence or absence of aeromonads below the detection limit of the membrane filter method. In addition, free chlorine residuals and pH values were determined for all water samples and heterotrophic plate counts and total and fecal coliform analyses were performed on them. Ribotyping patterns of aeromonads recovered from well 1, detention basin, sand filter, softener, and distribution samples were compared with those of the five clinical isolates. All patient strains were unique; however, identical ribotypes of A. hydrophila and A. sobria isolated from multiple sites in the water system indicated colonization of a well, sand filters, and the softener, with the potential for sporadic contamination of distribution water. Plant operational deficiencies were noted and corrected. Ribotyping can effectively differentiate otherwise indistinguishable strains of bacteria, thus providing a powerful tool for investigation of waterborne diseases and bacteriological problems within water treatment plants and distribution systems.     

Seed Banks in Arid Wetlands with Contrasting Flooding,Salinity and Turbidity Regimes

Aquatic plant communities in arid zone wetlands underpin diverse fauna populations and ecosystem functions yet are relatively poorly known. Erratic flooding, drying, salinity and turbidity regimes contribute to habitat complexity, creating high spatial and temporal variability that supports high biodiversity. We compared seed bank density, species richness and community composition of aquatic plants (submergent, floating-leaved and emergent) among nine Australian arid zone wetlands. Germinable seed banks from wetlands within the Paroo and Bulloo River catchments were examined at nested scales (site, wetland, wetland type) using natural flooding and salinity regimes as factors with nondormant seed density and species richness as response variables. Salinity explained most of the variance in seed density (95%) and species richness (68%), with flooding accounting for 5% of variance in seed density and 32% in species richness. Salinity-flooding interactions were significant but explained only a trivial portion of the variance (<1%). Mean seed densities in wetlands ranged from 40 to 18,760 m⁻² and were highest in wetlands with intermediate levels of salinity and flooding. Variability of densities was high (CVs 0.61–2.66), particularly in saline temporary and fresh permanent wetlands. Below salinities of c. 30 g l⁻¹ TDS, seed density was negatively correlated to turbidity and connectivity. Total species richness of wetlands (6–27) was negatively correlated to salinity, pH and riverine connectivity. A total of 40 species germinated, comprising submergent (15 species), floating-leaved or amphibious (17 species), emergent (6 species) and terrestrial (6 species) groups. Charophytes were particularly important with 10 species (five Chara spp., four Nitella spp. and Lamprothamnium macropogon), accounting for 68% of total abundance. Saline temporary wetlands were dominated by Ruppia tuberosa, Lamprothamnium macropogon and Lepilaena preissii. Variable flooding and drying regimes profoundly altered water quality including salinity and turbidity, producing distinctive aquatic plant communities as reflected by their seed banks. This reinforces the importance of hydrology in shaping aquatic biological communities in arid systems.     

Enumeration of Aeromonas hydrophila from domestic wastewater treatment plants and surface waters

Influents, effluents and sludges from sewage purification plants and surface water samples were examined quantitatively for Aeromonas hydrophila on the mA medium of Rippey and Cabelli. Between 10(4) and 10(6)/ml A. hydrophila were found in domestic wastewaters. On the average 99.975% were removed by activated sludge and 98.25% by trickling filters. Only 20.9% of A. hydrophila end up in the primary sludge, which contained up to 10(7)/g dry sludge. After 3 months, anaerobically (methane) fermented and partially dried sludge from trickling filters contained more than 10(6) A. hydrophila/g dry sludge. Surface water receiving raw sewage contained several hundreds of A. hydrophila/ml, comparable with the numbers found in effluent waters, while surface receiving no municipal wastewater and destined for the preparation of drinking water contained only small and negligible numbers. It was concluded that A. hydrophila was omnipresent in surface water.     

Elongation and mat formation of <Emphasis Type="Italic">Chara aspera</Emphasis> under different light and salinity conditions

Former laboratory results indicate that shoot elongation at low light intensities of Chara aspera is absent already at 10 psu which is within the physiologically optimal salinity range for brackish water populations. To investigate if similar restrictions occur in the field, density and morphology of C. aspera were compared between three freshwater and three brackish water sites along its depth range. The lower depth limit of C. aspera varied considerably among sites (30–600 cm) related to turbidity. Light availability at the lower depth limit corresponded to about 15% of surface irradiance in freshwater and brackish water with lower salinity (3.4 psu). Total length increased and fresh weight:length ratio decreased with depth at these sites indicating shoot elongation related to lower light availability. Due to shoot elongation, light availability was far higher at the upper parts of the shoot than at the bottom in the turbid sites. Light availability at the lower depth limit was higher (about 40%) at two sites with higher salinity (7–8 psu), where no shoot elongation was observed at the lower depth limit. Instead, the plants were stunted and often covered with filamentous algae or shaded by other rooted submerged macrophytes indicating competitive disadvantages of C. aspera at higher salinities. As growth in high densities (mat formation) exposes the plants to severe self-shading, it is suggested that shoot elongation is a prerequisite to mat formation. Dense vegetation of C. aspera was found only in freshwater and brackish water with lower salinity. Single, richly branched plants occurred in clearwater sites with higher salinity. C. aspera was not found in “double stress” environments with both high turbidity and high salinity: We asume that the species is a poor competitor under these conditions. Our results indicate that morphological differences between freshwater and brackish water populations of C. aspera are at least partly explained by salinity rather than genetic differences.     

黄河三角洲滨海滩涂不同密度柽柳林的土壤盐碱与养分特征

为探讨黄河三角洲滨海滩涂不同密度柽柳林的土壤盐碱和养分特征,明确不同密度柽柳林的“盐谷”及“肥岛”效应,以黄河三角洲山东省滨州市北海新区滨海滩涂的低密度（1100 株/hm2）、中密度（4100 株/hm2）和高密度（7100 株/hm2）柽柳林为研究对象,测定分析不同密度柽柳林及柽柳植株周边不同位置的土壤pH、电导率、速效氮、速效磷、速效钾、有机碳等指标。结果表明：（1）土壤电导率随林分密度增大表现为逐渐减小,在中、高密度柽柳林,土壤电导率分别比低密度降低28.39%、55.74%;随距离柽柳植株远近不同,中、高密度柽柳林土壤电导率表现为根部<冠幅中心<冠幅边缘<株间空地,即中、高密度柽柳林出现“盐谷”效应,而低密度林分未出现。（2）土壤速效氮、速效磷和有机碳含量随林分密度增大表现出先增大后减小,在中、高密度柽柳林,柽柳植株周边不同位置的速效氮、速效磷和有机碳含量存在显著差异（P<0.05）,表现为根部>冠幅中心>冠幅边缘>株间空地,而低密度柽柳林差异不显著（P>0.05）;即中、高密度柽柳林出现“肥岛”效应,而低密度林分未出现。（3）中密度柽柳林在养分含量、养分富集率方面高于高密度,在盐分富集率方面低于高密度,具有更强的“肥岛”、“盐谷”效应。（4）不同密度柽柳林以及柽柳植株周边不同位置的土壤pH差异均不显著（P>0.05）。林分密度显著影响土壤盐分及养分含量,中密度柽柳林具有显著提高土壤肥力的作用,高密度次之,而低密度较差。不同密度柽柳林的降盐作用表现为中、高密度较好,低密度较差。基于柽柳林改良土壤盐碱与养分的作用,建议黄河三角洲滨海滩涂柽柳合理的初植密度为4100 株/hm2。     

Physicochemical differences between fragments of plasma membrane and endoplasmic reticulum

Specific turbidities, densities, and refractive indices of fragments of plasma membrane (PM) and endoplasmic reticulum (ER) from Ehrlich ascites carcinoma have been measured. A spherical shell model of specified dimensions and refractive index was established for PM fragments. The ionic composition of the dispersion medium was varied systematically. Increases in Γ/2 caused increases in the turbidity of both PM and ER suspensions, the greatest effects being observed with Ca²⁺ and Mg²⁺. In the case of PM this effect is attributable mainly to aggregation, whereas "structural" changes account for most of the turbidity increase with ER. The pH was also varied systematically to obtain pH- density and turbidity profiles and to establish the isoelectric pH of the two membrane types (PM—3.6; ER—4.35). Turbidity was maximum at "isoelectric" pH, which corresponds in each case to the region of minimum charge on the particle surfaces. Both PM and ER show large increases of density at the "isoelectric" pH, but only ER shows substantial structurally based turbidity increase under these conditions. Both PM and ER show operation of electrostatic attractions near "isoelectric" pH. PM has been shown to have ionically distinctive inner and outer surfaces while ER shows no such dissymmetry. The necessary theoretical background for interpretation of turbidity and density measurements is included, as well as a discussion of the limitations of our conclusions and the biological importance of our results.     

Membrane filter procedure for enumeration of Aeromonas hydrophila in fresh waters.

A membrane filter method (mA) for the enumeration of Aeromonas hydrophila in natural water samples was developed. The complex, primary medium employs trehalose as a fermentable carbohydrate and ampicillin and ethanol as selective inhibitors. After 20 h of incubation at 37 degrees C, an in situ mannitol fermentation test followed by an in situ oxidase test is used to further differentiate A. hydrophila from other aquatic and terrestrial microorganisms present in freshwaters. The primary medium decreases background microbial growth by about two orders of magnitude. The recoveries on mA medium from suspensions of A. hydrophila prepared from pure cultures and held for 24 h at 15 degrees C exceeded 95% of the recoveries on brain-heart infusion agar spread plates. The confirmation rate for colonies designated A. hydrophila was 98%, whereas 11% of the presumptively negative colonies were, in fact, A. hydrophila. Recoveries of A. hydrophila from fresh, surface water samples exceeded recoveries by the other methods examined.     

Membrane filter procedure for enumeration of Aeromonas hydrophila in fresh waters.

A membrane filter method (mA) for the enumeration of Aeromonas hydrophila in natural water samples was developed. The complex, primary medium employs trehalose as a fermentable carbohydrate and ampicillin and ethanol as selective inhibitors. After 20 h of incubation at 37 degrees C, an in situ mannitol fermentation test followed by an in situ oxidase test is used to further differentiate A. hydrophila from other aquatic and terrestrial microorganisms present in freshwaters. The primary medium decreases background microbial growth by about two orders of magnitude. The recoveries on mA medium from suspensions of A. hydrophila prepared from pure cultures and held for 24 h at 15 degrees C exceeded 95% of the recoveries on brain-heart infusion agar spread plates. The confirmation rate for colonies designated A. hydrophila was 98%, whereas 11% of the presumptively negative colonies were, in fact, A. hydrophila. Recoveries of A. hydrophila from fresh, surface water samples exceeded recoveries by the other methods examined.     

Enumeration of Aeromonas hydrophila from domestic wastewater treatment plants and surface waters

R. POFFÉ AND E. OP DE BEECK. 1991. Influents, effluents and sludges from sewage purification plants and surface water samples were examined quantitatively for Aeromonas hydrophila on the mA medium of Rippey and Cabelli. Between 10⁴ and 10⁶/ml A. hydrophila were found in domestic wastewaters. On the average 99.975% were removed by activated sludge and 98.25% by trickling filters. Only 20.9% of A. hydrophila end up in the primary sludge, which contained up to 10⁷/g dry sludge. After 3 months, anaerobically (methane) fermented and partially dried sludge from trickling filters contained more than 10⁶ A. hydrophila /g dry sludge. Surface water receiving raw sewage contained several hundreds of A. hydrophila /ml, comparable with the numbers found in effluent waters, while surface water receiving no municipal wastewater and destined for the preparation of drinking water contained only small and negligible numbers. It was concluded that A. hydrophila was omnipresent in surface water.     

Salinity tolerance in different cultivars of barley (Hordeum vulgare L.)

Seven barley(Hordeum vulgäre L.) cultivars tested varied greatly in their responses to root medium salinity (electrical conductivity of 3, 5, 10, 15 and 20 dS nr^-1)-lant growth was relatively more adversely affected than seed germination. Dry/fresh mass ratio increased at higher salinity levels in all barley cultivars indicating reduced water uptake. Higher K/Na ratio in plant shoots compared to that in the root medium solution indicated selective uptake of K that seems to be among processes involved in tolerance of cultivars to salinity stress.     

A comparative study of physico-chemical characteristics of river and lake water in Central India

The present paper deals with a comparative study of the physico-chemical characteristics of river and lake waters in Central India. The surface water has been analysed for pH, turbidity, conductivity, alkalinity, dissolved oxygen and chlorides. The results of analyses of river water have been compared with those from lake water.The study reveals that the lake water is highly turbid, rich in organic matter, contains more of chlorides and has a higher pH value as compared to river water.