A Study of Benthic Communities in Some Saline Lakes in Saskatchewan and Alberta,Canada

The spring benthos of 22 lakes ranging from 1–88 gl⁻¹ salinity contained 58 species of macroinvertebrates, but only 23 species occurred in waters >3 gl⁻¹. The amphipod Hyalella azteca and the chironomids Procladius freemani, Chironomus nr. muratensis and Cryptochironomus spp. were important at lower salinities (1–12 gl⁻¹) whereas the chironomids Tanypus nubifer, Cricotopus ornatus and Chironomus nr. annularis dominated at moderate salinities (5–30 gl⁻¹) and dolichopodid and ephyrid dipterans were the only species in hypersaline lakes (>50 gl⁻¹). Diversity decreased significantly with increased salinity. Mean dry biomass ranged from 0–9.12 gm⁻², showing little correlation with salinity, though hyposaline lakes often had elevated values and hypersaline lakes very low values. Shallow lakes (<5 m) had significantly lower standing crops. There were long term changes in biomass (over 45 years) in some lakes due to cultural eutrophication or secular changes in salinity. Chironomids were by far the dominant contributors to biomass at salinities to 50 gl⁻¹, above which dolichopodid and ephyrid dipterans dominated. The lakes were classified into four groups—subsaline, hyposaline, shallow hypo-mesosaline and hypersaline, reflecting the importance of salinity and also relative depth as major controlling factors.     

A Study of the Chromatiaceae in a Saline Meromictic Lake in Saskatchewan,Canada

Lamprocystis roseopersicina was found to be the dominant phototrophic bacterium in meromictic Deadmoose Lake. Using carbon-14 it was determined that phototrophic bacteria fixed 14.3 g C m⁻² year⁻¹, 17.1 % of the total limnetic primary production. Experiments indicated low light intensities (X = 8.87 × 10⁻² cal cm⁻²hr⁻¹) to be the most important factor limiting bacterial production. Lamprocystis was shown to be capable of photoorganoheterotrophic uptake of glucose.     

The Saline Lakes of Saskatchewan I. Background and Rationale for Saline Lakes Research

The historical background and utilization of southern Saskatchewan is described. The utilization of the saline lakes is discussed and the rationale for studying them is outlined.     

A Comparative Study of Primary Production and Related Factors in Four Saline Lakes in Victoria,Australia

The purpose of the study was to compare the primary plankton productivities of lakes of different salinities and to determine the causative factors involved in their production rates. Four lakes (specific conductivity —mS cm⁻¹ at 18°C) were initially chosen: Coragulac (9), Red Rock (25), Corangamite (38), Pink (250). Sampling and production measurements were made every two to three weeks. Three lakes were dominated by specific phytoplankton blooms: Red Rock (Anabaena spiroides), Corangamite (Nodularia spumigena). Pink (Dunaliella salina). Coragulac Lake had more diverse populations. Red Rock Tarn had some of the highest production values ever recorded. Extremely high soluble phosphate and inorganic carbon concentrations were the most important causative factors. Pink Lake had very low production rates. High salinity and low nutrient concentrations were limiting factors. The other lakes were intermediate in production and nutrient levels. Zooplankton populations were also determined.     

Bacterial Communities of Three Saline Meromictic Lakes in Central Asia

Meromictic lakes located in landlocked steppes of central Asia (~2500 km inland) have unique geophysiochemical characteristics compared to other meromictic lakes. To characterize their bacteria and elucidate relationships between those bacteria and surrounding environments, water samples were collected from three saline meromictic lakes (Lakes Shira, Shunet and Oigon) in the border between Siberia and the West Mongolia, near the center of Asia. Based on in-depth tag pyrosequencing, bacterial communities were highly variable and dissimilar among lakes and between oxic and anoxic layers within individual lakes. Proteobacteria, Bacteroidetes, Cyanobacteria, Actinobacteria and Firmicutes were the most abundant phyla, whereas three genera of purple sulfur bacteria (a novel genus, Thiocapsa and Halochromatium) were predominant bacterial components in the anoxic layer of Lake Shira (~20.6% of relative abundance), Lake Shunet (~27.1%) and Lake Oigon (~9.25%), respectively. However, few known green sulfur bacteria were detected. Notably, 3.94% of all sequencing reads were classified into 19 candidate divisions, which was especially high (23.12%) in the anoxic layer of Lake Shunet. Furthermore, several hydro-parameters (temperature, pH, dissolved oxygen, H₂S and salinity) were associated (P< 0.05) with variations in dominant bacterial groups. In conclusion, based on highly variable bacterial composition in water layers or lakes, we inferred that the meromictic ecosystem was characterized by high diversity and heterogenous niches.     

Sulfate reduction rates and some aspects of the limnology of four lakes and a fjord in the Vestfold Hills,Antarctica

Sulfate reduction rates were measured in waters and sediments from four antarctic lakes and an antarctic fjord basin by a radiometric technique. There was generally a linear correlation between the period of incubation and sulfate reduced; the average of the correlation coefficients was 0.76 ± 0.1. The rates at 6 °C were very low (0.0–1.1 µmol kg^–1 d^–1) when compared to most other marine and non-marine environments for which sulfate reduction rates have been reported. Lactate and acetate did not stimulate sulfate reduction. Temperatures of the sediments selected from the different sites varied from –0.4 to 4.5 °C and the chloride and sulfate concentrations of the sediments varied from 0.19 to 0.83 mol kg^–1 and 0.04 to 41.01 mmol kg^–1 respectively. Sulfate reduction rates did not correlate with the chlorosity of sediment porewaters.     

Seasonal changes in the chemistry and biology of a meromictic lake (Big Soda Lake,Nevada, U.S.A.)

Big Soda Lake is an alkaline, saline lake with a permanent chemocline at 34.5 m and a mixolimnion that undergoes seasonal changes in temperature structure. During the period of thermal stratification, from summer through fall, the epilimnion has low concentrations of dissolved inorganic nutrients (N, Si) and CH₄, and low biomass of phytoplankton (chlorophyll a ca. 1 mgm ^-3). Dissolved oxygen disappears near the compensation depth for algal photosynthesis (ca. 20 m). Surface water is transparent so that light is present in the anoxic hypolimnion, and a dense plate of purple sulfur photosynthetic bacteria (Ectothiorhodospira vacuolata) is present just below 20 m (Bchl a ca. 200 mgm^-3). Concentrations of N H₄ ⁺, Si, and CH₄ are higher in the hypolimnion than in the epilimnion. As the mixolimnion becomes isothermal in winter, oxygen is mixed down to 28 m. Nutrients (NH₄ ⁺, Si) and CH₄ are released from the hypolimnion and mix to the surface, and a diatom bloom develops in the upper 20 m (chlorophyll a > 40 mgm^-3). The deeper mixing of oxygen and enhanced light attenuation by phytoplankton uncouple the anoxic zone and photic zone, and the plate of photosynthetic bacteria disappears (Bchl a ca.10mgm^-3). Hence, seasonal changes in temperature distribution and mixing create conditions such that the primary producer community is alternately dominated by phytoplankton and photosynthetic bacteria: the phytoplankton may be nutrient-limited during periods of stratification and the photosynthetic bacteria are light-limited during periods of mixing.     

Diversity of Carbon Monoxide-Oxidizing Bacteria in Five Lakes on the Qinghai-Tibet Plateau,China

Carbon monoxide-oxidizing (COX) bacteria play an important role in controlling the flux of carbon monoxide among natural reservoirs, and thus studying their diversity in natural environments is of great significance to understanding the carbon cycle. In this study, the COX bacterial diversity was investigated in five lakes (Erhai Lake, Gahai Lake1, Gahai Lake2, Xiaochaidan Lake, Lake Chaka) on the Qinghai-Tibet Plateau and its correlation with environmental variables of the lakes was explored. Phylogenetic analyses showed that the CO-oxidizers were dominated by Proteobacteria and Actinobacteria in the Qinghai-Tibet Plateau lakes, and their relative abundance varied with salinity: in the freshwater Erhai Lake, the COX bacteria in the water were dominated by the Betaproteobacteria, in contrast to the Actinobacteridae dominance in the sediment; in the saline and hypersaline lakes of Gahai Lake1, Gahai Lake2 and Xiaochaidan Lake, alphaproteobacterial COX bacteria were dominant in the water, whereas Actinobacteridae and alphaproteobacterial COX bacteria were dominant in the sediment. In the hypersaline Lake Chaka, an unknown COX bacterial clade and alphaproteobacterial COX bacteria were dominant in the water and sediment, respectively. Statistical analyses showed that salinity, pH, and major ions (e.g., K⁺, Na⁺, Ca²⁺, Mg²⁺, SO₄ ^2-, and Cl^-) were important factors affecting the COX bacterial community compositions in the investigated lakes. Overall, our results provided insights into the COX bacterial diversity in Qinghai-Tibetan lakes.     

The Saline Lakes of Saskatchewan III. Chemical Characterization

The salinity of Saskatchewan saline lakes varies up to 342%₀. Highly saline lakes are widely distributed. Some reach saturation at high summer temperatures but salt precipitation occurs on cooling. Saline lakes tend to increase in salinity with time but the greatest changes occur in the shallow more saline lakes. The lakes are dominated by sodium, magnesium and sulphate. The cation sequences are dominated by sodium or magnesium while calcium and potassium are proportionally much smaller. Chloride or bicarbonate-carbonate are secondary to sulphate among the anions. Ion sequences tend to be characteristic of certain physiographic regions. Lake types were magnesium (sodium) sulphate, sodium sulphate and sodium (magnesium) sulphate in order of abundance of lakes. Phosphorus and ammonia were high in concentration but nitrate and silica were scarce. The lakes were all alkaline between pH 7.8 and 9.8. The evolution of closed saline lakes is briefly discussed.     

Seasonal Changes in the Structure of the Anoxygenic Phototrophic Bacterial Community in Lake Mogilnoe,a Relict Lake on Kil'din Island in the Barents Sea

An anaerobic phototrophic bacterial community in Lake Mogilnoe, a relict lake on Kil'din Island in the Barents Sea, was studied in June 1999 and September 2001. Irrespective of the season, the upper layer of the anaerobic zone of this lake had a specific species composition of sulfur phototrophic bacteria, which were dominated by the brown-colored green sulfur bacterium Chlorobium phaeovibrioides. The maximum number of sulfur phototrophic bacteria was observed in June 1999 at a depth of 9 m, which corresponded to a concentration of bacteriochlorophyll (Bchl) e equal to 4.6 mg/l. In September 2001, the maximum concentration of this pigment (3.4 mg/l) was found at a depth of 10 m. In both seasons, the concentration of Bchl a did not exceed 3 μg/l. Purple sulfur bacteria were low in number, which can be explained by their poor adaptation to the hydrochemical and optical conditions of the Lake Mogilnoe water. In June 1999, the water contained a considerable number of Pelodictyon phaeum microcolonies and Prosthecochloris phaeoasteroides cell chains, which was not the case in September 2001. A 16S rDNA-based phylogenetic analysis of pure cultures of phototrophic bacteria isolated from the lake water confirmed that the bacterial community is dominated by Chl. phaeovibrioides and showed the presence of three minor species, Thiocystis gelatinosa, Thiocapsa sp., and Thiorhodococcus sp., the last of which is specific to Lake Mogilnoe.     

Habitat Use by Migrant Shorebirds in Saline Lakes of the Southern Great Plains

Abstract Shorebirds migrating through the Southern Great Plains of North America use saline lakes as stopovers to rest and replenish energy reserves. To understand how availability of invertebrates, salinity, freshwater springs, vegetation, and water influence the value of saline lakes as migration stopovers, we compared lakes used and not used by migrant shorebirds. Shorebirds used lakes that had freshwater springs, mudflats and standing water, sparse vegetation (≤1% cover), low to moderate salinities (x = 30.87 g/L), and mean invertebrate biomass of 0.79 g/m². Lakes that were not used were generally dry or had hypersaline water (x = 82.56 g/L), lacked flowing springs and vegetation, and had few or no invertebrates (x = 0.007 g/m²). Our results suggest that reduced spring flows and increased salinity negatively affect availability of shorebird habitats and aquatic invertebrates. We recommend preservation of the freshwater springs discharging in the saline lakes. Because the springs are discharged from the Ogallala aquifer, which is recharged through the playa wetlands, the entire complex of wetlands in the Great Plains and the Ogallala aquifer should be managed as an integral system.     

Seasonal changes in the structure of the anoxygenic photosynthetic bacterial community in Lake Shunet,Khakassia

Seasonal studies of the anoxygenic phototrophic bacterial community of the water column of the saline eutrophic meromictic Lake Shunet (Khakassia) were performed in 2002 (June) and 2003 (February–March and August). From the redox zone down, the lake water was of dark green color. Green sulfur bacteria predominated in every season. The maximum number of green sulfur bacteria was 10⁷ cells/ml in summer and 10⁶ cells/ml in winter. A multi-syringe stratification sampler was applied for the study of the fine vertical distribution of phototrophs in August 2003; the sampling was performed every 5 cm. A 5-cm-thick pink-colored water layer inhabited by purple sulfur bacteria was shown to be located above the layer of green bacteria. The species composition and ratio of purple bacterial species depended on the sampling depth and on the season. In summer, the number of purple sulfur bacteria in the layer of pink water was 1.6 × 10⁸ cells/ml. Their number in winter was 3 × 10⁵ cells/ml. In the upper oxygen-containing layer of the chemocline the cells of purple nonsulfur bacteria were detected in summer. The maximum number of nonsulfur purple bacteria, 5 × 10² cells/ml, was recorded in August 2003. According to the results of the phylogenetic analysis of pure cultures of the isolated phototrophic bacteria, which were based on 16S rDNA sequencing, green sulfur bacteria were close to Prosthecochloris vibrioformis, purple sulfur bacteria, to Thiocapsa and Halochromatium species, and purple nonsulfur bacteria, to Rhodovulum euryhalinum and Pinkicyclus mahoneyensis.     

The Distribution of Mercury in the Sediments of Eight Saskatchewan Lakes

Eight lakes located in the southern half of Saskatchewan were sampled in May and June, 1987, to determine the concentration and spatial distribution of mercury in their surface sediments. Katepwa and Buffalo Pound lakes had maximum total mercury sediment concentrations of 0.158 and 0.100 μg · g⁻¹ dry weight respectively, while in the other six lakes the mercury concentration was never greater than 0.04 μg · g⁻¹ dw. Despite this difference in mercury concentration in the sediments of the lakes, walleye sampled from them have high mercury concentrations exceeding 0.5 μ · g⁻¹ (wet weight).     

Anoxygenic phototrophic bacterial community of Lake Shira (Khakassia)

The anoxygenic phototrophic bacterial community of the brackish meromictic Lake Shira (Khakassia) was investigated in August 2001, July 2002, and February–March 2003. In all the periods of investigation, the prevailing microorganisms were purple sulfur bacteria similar to Lamprocystis purpurea in morphology and pigment composition. Their highest number (3 × 10⁵ cells/ml) was recorded in July 2002 at the depth of 15 m. According to 16S rRNA gene analysis, the strain of purple sulfur bacteria isolated in 2001 and designated ShAm01 exhibited 98.6% similarity to the type strain of Thiocapsa roseopersicina and 97.1–94.4% similarity to the type strains of Tca. pendens, Tca. litoralis, and Tca. rosea. The minor microorganisms of the anoxygenic phototrophic bacterial community within the period of investigation were nonsulfur purple bacteria phylogenetically close to Rhodovulum strictum (98.3% similarity, strain ShRb01), Ahrensia kielensis (of 93.9% similarity, strain ShRb02), Rhodomicrobium vannieli (of 99.7% similarity, strain ShRmc01), and green sulfur bacteria, phylogenetically close to Chlorobium limicola (of 98.7% similarity, strain ShCl03).     

Zooplankton Seasonal Abundance of South AmericanSaline Shallow Lakes

The central provinces of Argentina are characterized by the presence of a high number of shallow lakes, located in endorheic basins, many of which have elevated salinities as well as eutrophic or hypereutrophic condition. The zooplankton of four saline shallow lakes of the province of La Pampa was studied on a monthly basis during a 2‐year period to determine its temporal and spatial variation. The surface of these shallow lakes (<2.5 m depth) varied between 56.8 and 215.9 ha, and some have from 8.4 to 20.8 g · l^–1. The more saline lakes have “clear” water and the less saline lakes “turbid” water. Fishes, Jenynsia multidentata , were present in only two lakes during the last two months of the studied period. The zooplankton was composed of 17 taxa of Rotifera, 5 taxa of Cladocera and 4 taxa of Copepoda. The low diversity and the faunistic composition are characteristic of saline environments. Although the studied lakes share 38% of the species, the faunistic similarity was higher between the two least saline lakes. The lowest diversity was found in the two most saline lakes. All four shallow lakes were characterized by their very high zooplankton density, especially in the least saline lakes (<80000 ind · l^–1). The abundance is significantly correlated with the water transparency but not with salinity. The zooplankton temporal variation was characterized by the alternation of macro‐ and microzooplankton, probably regulated by competition and intrazooplanktonic predation. In each lake, the spatial abundance distribution of the macro‐ and microzooplankton was homogeneous. It was related to the shallow depht of the lakes and their polymictic condition. The Scheffer model on alternative states in shallow lakes acknowledges that it cannot be applied to saline lakes because Daphnia , the main responsible for the clear water state, is not tolerant to high salinity. Our study shows that the most saline lakes, where the halophylic Daphnia menucoensis is abundant, have also the most clear waters. Another difference that we found with regards to the mentioned model is that, in turbid lakes, it could not have had a top‐down control on macrozooplankton exerted by fishes because in these lakes fishes were practically absent. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The Saline Lakes of Saskatchewan IV. Primary Production by Phytoplankton in Selected Saline Ecosystems

Primary production by phytoplankton, efficiency of photosynthesis, and chlorophyll-a concentrations were determined for seven saline lakes that varied widely in ionic concentration and composition. The investigations were done during the summer months of 1972 and 1973. Productivity ranged from 0.001 to 11.135 g C m⁻³ day⁻¹ and 0.053 to 7.968 g C m⁻² day⁻¹. Highest productivities were measured in two lakes that supported blooms of Aphanizomenon flos-aquae and Nodularia spumigena, respectively. Species of Cyanophyceae, Bacillariophyceae and Chlorophyceae dominated the phytoplankton of the study lakes. Active chlorophyll-a ranged from 0.01 to 116 mg m⁻³. Integral photosynthetic efficiency estimates were <1% except during phytoplankton blooms when they were considerably higher. The overall range of 0.03 to 3.8% is concordant with estimates for other lacustrine ecosystems. The extinction of light caused by photo-synthetic processes, or in situ efficiency, was <1% in the trophogenic zone for most lakes but, it was considerably higher during blooms. In situ efficiencies invariably increased with depth in ail lakes.     

Microbiological and Isotopic-Geochemical Investigations of Meromictic Lakes in Khakasia in Winter

Microbiological and isotopic-geochemical investigations of the brackish meromictic lakes Shira and Shunet were performed in the steppe region of Khakasia in winter. Measurements made with a submersed sensor demonstrated that one-meter ice transmits light in a quantity sufficient for oxygenic and anoxygenic photosynthesis. As in the summer season, in the community of phototrophic bacteria found in Lake Shira, the purple sulfur bacteria Amoebobacter purpureus dominated, whereas, in Lake Shunet, the green sulfur bacteria Pelodictyon luteolum were predominant. Photosynthetic production, measured using the radioisotopic method, was several times lower than that in summer. The rates of sulfate reduction and production and oxidation of methane in the water column and bottom sediments were also lower than those recorded in summer. The process of anaerobic methane oxidation in the sediments was an exception, being more intense in winter than in summer. The data from radioisotopic measurements of the rates of microbial processes correlate well with the results of determination of the isotopic composition of organic and mineral carbon (δ¹³C) and hydrogen sulfide and sulfate (δ³⁴S) and suggest considerable seasonal variations in the activity of the microbial community in the water bodies investigated.__________Translated from Mikrobiologiya, Vol. 74, No. 4, 2005, pp. 552–561.Original Russian Text Copyright © 2005 by Savvichev, Rusanov, Rogozin, Zakharova, Lunina, Bryantseva, Yusupov, Pimenov, Degermendzhi, Ivanov.     

Biological fractionation of stable carbon isotopes at the aerobic/anaerobic water interface of meromictic water bodies

Mass-spectrometric investigation of carbon isotope composition (δ¹³C) was carried out for suspended organic matter and dissolved mineral compounds for the water column of some meromictic water bodies differing in salinity and trophic state. As a rule, a more pronounced carbon isotope fractionation (resulting from the metabolism of phytoplankton and anoxygenic phototrophic bacteria) was revealed in the zones of enhanced oxygenic and anoxygenic photosynthesis. Carbon isotope fractionation at the border between oxidized and reduced waters depends both on the activity of microbial communities and on the dominant species of phototrophic microorganisms. Analysis of the distribution profiles of the isotopic composition of suspended organic matter and dissolved mineral carbon revealed active mineralization of the organic matter newly formed via anoxygenic photosynthesis in the monimolimnion by microbial communities, resulting in the release of isotopically light carbon dioxide. Mineral carbon in the anaerobic zones of highly productive meromictic water bodies is therefore enriched with the light ¹²C isotope.     

Sulfate reduction and methanogenesis in the Shira and Shunet meromictic lakes (Khakasia, Russia)

The biogeochemical and molecular biological study of the chemocline and sediments of saline meromictic lakes Shira and Shunet (Khakasia, Russia) was performed. A marked increase in the rates of sulfate reduction and methanogenesis was revealed at the medium depths of the chemocline. The rates of these processes in the bottom sediments decreased with depth. The numbers of the members of domains Bacteria, Archaea, and of sulfate-reducing bacteria (SRB) were determined by fluorescence in situ hybridization with rRNA specific oligonucleotide probes labeled with horseradish peroxidase and subsequent tyramide signal amplification. In the chemocline, both the total microbial numbers and those of Bacteria were shown to increase with depth. The archaea and SRB were present in almost equal numbers. In the lake sediments, a drastic decrease in microbial numbers with depth was revealed. SRB were found to prevail in the upper sediment layer and archaea in the lower one. This finding correlated with the measured rates of sulfate reduction and methanogenesis.     

The Saline Lakes of Saskatchewan II. Locale,Hydrography and other Physical Aspects

The geology and physiography, climate, soils and vegetation of the saline lakes region of southern Saskatchewan are briefly reviewed. The location and morphometry of 60 saline lakes was determined. Some of them are large (307 km²) but mean depths do not exceed 10 m and many are very shallow. Light penetration varied considerably from very turbid shallow lakes to Redberry Lake where the 1% light level was below 16.5 m. Light extinction coefficients for the entire water column of deeper lakes (7) varied from 0.256 to 2.558. Shallow lakes failed to stratify thermally but a dozen deeper lakes stratified for at least several months. Higher salinity tends to prolong stratification. Thermal stratification augmented chemical stratification in two meromictic lakes. Maximum temperature up to 30 °C in very saline shallow waters was recorded while temperatures as low as-3 °C occurred under the ice. Freezing was delayed and thawing accelerated in more saline lakes. Annual heat budgets varied from 3350 to 13,900 g cal cm-² in seven lakes. Oxygen concentration was reduced below thermoclines and was virtually absent below the ice in very shallow lakes and, at times, in a very productive lake.