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  • 1
    Electronic Resource
    Electronic Resource
    The influence of environmental factors on seasonal changes in bacterial cell volume in two prairie saline lakes (1993)
    Springer
    Microbial ecology 26 (1993), S. 9-20 
    Details
    ISSN: 1432-184X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Bacterial biovolumes of hypertrophic Humboldt Lake (total dissolved solids = 3.3 g liter-1; 6 m deep) and oligotrophic Redberry Lake (total dissolved solids = 20.9 g liter-1; 17 m deep), Saskatchewan, were measured concurrently with a variety of environmental variables to identify the major factors correlated with volume changes. There was no difference (P 〉 0.05) in mean bacterial volume between Redberry Lake (0.084 ± 0.034 μm3 SD) and Humboldt Lake (0.083 ± 0.021 μm3 SD). Statistical analyses suggested there were marked differences in the factors associated with the pronounced seasonality of bacterial cell volumes in these two lakes. Variance in bacterial volume in the epilimnion of Redberry Lake was best explained by a multivariate regression model which included ciliate abundance and chlorophyll concentration (r 2 = 0.96). The model accounting for changes in hypolimnetic bacterial volume included ciliate numbers and primary production (r 2 = 0.94), of the measured variables. Bacterial volume in Humboldt Lake was most highly correlated with primary production (r 2 = 0.59). Bacterial production (estimated as the rate of thymidine incorporation into DNA) and growth (thymidine incorporation rate normalized to cell numbers) were not correlated to cell volume, with the exception of cocci volume in Humboldt Lake.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00166025
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  • 2
    Electronic Resource
    Electronic Resource
    The effect of catchment geochemistry and geomorphology on the productivity of a tropical African montane lake (Little Connemara Dam No. 3, Rhodesia) (1977)
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 7 (1977), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SUMMARY. An extensive limnological study of a tropical African montane lake (Little Connemara Dam No. 3) was undertaken in 1975 to explain the discrepancy between the high nutrient content of the bottom muds and the oligotrophic status of the water column. Little Connemara Dam (No. 3) lies in a small dolerite catchment. The dolerite is strongly jointed allowing considerable water movement and it weathers easily under high rainfall. A number of homes are built in the small catchment.The results of the study showed that the majority of the nutrients were being flushed into the lake from septic tanks via underground streams. As the dolerite weathers, large amounts of iron and manganese, but little calcium or carbonate, are released. The PO4-P in the water column is complexed with the Fe and Mn allowing only small concentrations for use by algae. Nitrogen enters the lake mainly as particulate nitrogen but is not significantly converted to soluble combined forms of nitrogen at the low pH values (6.2—6.7) found in the lake. Bioassay experiments indicated that combined forms of nitrogen limited phytoplankton growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2427.1977.tb01653.x
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  • 3
    Electronic Resource
    Electronic Resource
    Response of plankton communities to whole-lake Ca(OH)2 and CaCO3 additions in eutrophic hardwater lakes (2001)
    Oxford UK : Blackwell Science Ltd
    Freshwater biology 46 (2001), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. The impact of whole-lake lime (slaked lime, Ca(OH)2, and/or calcite, CaCO3) addition on plankton communities was evaluated in eutrophic hardwater lakes on the North American Boreal Plain.2. Two lakes received a single treatment of lime (Ca(OH)2 at 74 or 107 mg L–1), two lakes received multiple treatments with Ca(OH)2 and/or CaCO3 (5–78 mg L–1), and four lakes were untreated and served as reference systems.3. Over the long-term (〉 1 year), phytoplankton biomass was reduced in multiple-dose lakes, but not in single-dose lakes. Cyanobacteria typically dominated the algal community in the years before, during and after lime treatment in both single- and multiple-dose lakes.4. In the single-dose lakes, randomized intervention analysis showed no significant change in the biomass of zooplankton after lime addition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2427.2001.00793.x
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  • 4
    Electronic Resource
    Electronic Resource
    Seasonal and diel changes of dissolved oxygen in a hypertrophic prairie lake (2005)
    Oxford, UK : Blackwell Science Pty
    Lakes & reservoirs 10 (2005), S. 0 
    Details
    ISSN: 1440-1770
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geography
    Notes: Humboldt Lake, a hypertrophic prairie lake typical of many found on the Great Plains of North America, is usually ice-covered from early November to about mid-May. The lake is an important recreational fishery, now mainly stocked with walleye. It has a high potential risk of experiencing fish kills because of the very large cyanobacterial blooms that develop in it, the high rates of algal and bacterial production and the high concentrations of ammonia (NH3-N) and dissolved organic matter. Following the collapse of cyanobacterial blooms, shallow prairie lakes are known to undergo periods of anoxia that can lead to summer fish kills. In some of the lakes, anoxia forms during the long period of ice cover, causing winter fish kills. Two years of seasonal and diel data (total phosphorus, dissolved oxygen (DO), NH3-N and chlorophyll-a concentrations, and bacterial production) were analysed in this study to assess why significant fish kills did not occur during this period or during the ≈ 30 years of records from Saskatchewan Environment. Humboldt Lake did not become anaerobic, either following the collapse of the cyanobacterial bloom or under ice cover, indicating that the oxygen (O2) influx (strong mixing) and production processes were greater than the microbial and chemical O2 demands, both over seasonal and diel time scales. Several published risk threshold criteria to predict the probability of summer and/or winter fish kills were applied in this study. The threshold criteria of maximum summer chlorophyll and maximum winter NH3-N concentrations indicated that a summer fish kill was unlikely to occur in this hypertrophic prairie lake, provided its water quality remained similar to that during this study. Similarly, the threshold criteria of initial DO storage before ice cover and the rate of O2 depletion under ice cover also indicated a winter fish kill was unlikely. However, recent development in the watershed might have resulted in significant water quality deterioration and the winter fish kill that occurred in 2005.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1440-1770.2005.00273.x
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  • 5
    Electronic Resource
    Electronic Resource
    The significance of autotrophic and heterotrophic picoplankton in hypertrophic ecosystems (1997)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology ecology 24 (1997), S. 0 
    Details
    ISSN: 1574-6941
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Hypertrophic aquatic ecosystems are biologically important because they represent an environment where homeostatic mechanisms are strongly reduced and extreme oscillations occur in physical and chemical parameters as well as in the growth of many planktonic organisms. Hypertrophic lakes may represent not only the ultimate state of eutrophication, but also systems where abundance and production of picoplanktonic organisms (0.2–2 μm in diameter) may theoretically be greatest. In this review we examined the microbial ecology literature for studies on hypertrophic lakes and assessed the significance of heterotrophic bacteria (BACT) and autotrophic picoplankton (APP). Our main conclusions are as follows: (a) The relative contribution of APP to total phytoplankton biomass is strongly reduced in hypertrophic systems. (b) The absolute abundance and biomass of APP are highly variable among these systems; depending mainly on differences in light quality and quantity, the existence of nitrogen limitation and presence of pollutants. (c) The abundance of BACT does not increase as rapidly as algal biomass with increasing trophy. (d) A clear dichotomy exists between lakes dominated by Microcystis where bacterial biomass and production are relatively low, and Planktothrix-dominated lakes where bacterial biomass and production are high. (e) Bacterial production per unit biomass tends to increase from oligotrophic to hypertrophic systems supporting the previous hypothesis that bacteria do not play a lesser role in lake metabolism at the upper end of the trophic scale. In general, however, our knowledge of the microbial ecology of hypertrophic systems has advanced very little since the 1980s, largely because most studies of these systems have focused on their remediation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6941.1997.tb00436.x
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  • 6
    Electronic Resource
    Electronic Resource
    Seasonal patterns of total and energy reserve lipids of dominant zooplanktonic crustaceans from a hyper-eutrophic lake (1992)
    Springer
    Oecologia 90 (1992), S. 560-571 
    Details
    ISSN: 1432-1939
    Keywords: Lipids ; Energy reserves ; Aphanizomenon ; Zooplankton ; Eutrophy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Seasonal patterns of lipid reserves and lipid classes of dominant zooplankton in a hyper-eutrophic lake were examined in relation to algal food resources. Triacylglycerol was the principle lipid energy reserve in all five species examined. During the height of the yearlyAphanizomenon flos-aquae bloom, lipid levels of the principle herbivores (Daphnia pulex andLeptodiaptomus sicilis) and an omnivore (Diacyclops bicuspidatus thomasi), were at their lowest concentration, suggesting that this cyanobacterium is nutritionally inadequate. As the cyanobacterial bloom began to collapse, bacterial numbers increased rapidly. The increase in bacterial numbers coincided with a large increase in areal lipid energy reserves ofDiaphanosoma leuchtenbergianum andChydorus sphaericus. Examination of seasonal patterns in the biomass of different algal species suggested thatRhodomonas minuta andCryptomonas erosa played a key role in nutrition, lipid deposition, and reproduction ofD. pulex andL. sicilis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01875451
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  • 7
    Electronic Resource
    Electronic Resource
    Labile dissolved organic carbon and water temperature as regulators of heterotrophic bacterial activity and production in the lakes of Sub-Antarctic Marion Island (1991)
    Springer
    Polar biology 11 (1991), S. 403-413 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The objectives of the 3 year study were to determine the relationship between bacterial numbers and phytoplankton standing crops (chlorophyll a) in sub-antarctic Marion Island lakes (33) and to determine the relative importance of labile dissolved organic carbon and water temperature as regulators of heterotrophic bacterial activity and production. Bacterial activity (the incorporation and respiration rates of 14C-labelled substrates) and production (the rate of [methyl-3H]thymidine incorporation into DNA) were measured in oligotrophic Lava Lake and Gentoo Lake, an elephant seal wallow. Samples were incubated under ambient conditions as well as at increased temperature and with additions of labile dissolved organic carbon (DOC). Bacterial numbers ranged from 2.13 × 105 cell ml−1 to 15.17 × 106 cells ml−1 in the lake survey. The chlorophyll range was 0.18 to 〉75 μg 1−1. Bacterial numbers were not correlated to chlorophyll concentration in waters where the chlorophyll content was ≤ 5 μg 1−1 but were correlated in waters with larger algal contents. Heterotrophic bacterial activity and production, which were similar to rates recorded for equivalent lower latitude systems, were higher in Gentoo Lake than in Lava Lake. As a result of qualitative and quantitative differences in the DOC pools, DOC was the stronger regulator of bacterial activity and production in Lava Lake, while temperature was the stronger factor in Gentoo Lake.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00239693
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  • 8
    Electronic Resource
    Electronic Resource
    Vertical diffusion and nutrient transport in a tropical lake (Lake McIlwaine, Rhodesia) (1978)
    Springer
    Hydrobiologia 59 (1978), S. 213-221 
    Details
    ISSN: 1573-5117
    Keywords: tropical lake ; vertical diffusion ; nutrient transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Measurements of the vertical temperature in tropical Lake McIlwaine were used to calculate the time-averaged (≃ 6 months) vertical diffusivity coefficient (Kz) in the metalimnion and hypolimnion. The mean value of Kz (0.21 cm2 s−1) was correlated with the lake surface area. The mass transport rates of PO4-P and NH4-N, upward from the hypolimnion to the metalimnion, were calculated using Kz and measured values of the nutrient concentration gradients. During a period of 4.5 months when the water was stably stratified, PO4-P was transported upward at a mean rate of 42 kg day−1 and NH4-N at a mean rate of 162 kg day−1 over the entire lake.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00036500
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  • 9
    Electronic Resource
    Electronic Resource
    Seasonal changes in the dissolved free amino acid and DOC concentrations in a hypertrophic African reservoir and its inflowing rivers (1990)
    Springer
    Hydrobiologia 199 (1990), S. 201-216 
    Details
    ISSN: 1573-5117
    Keywords: Microcystis ; dissolved organic carbon ; bacterial production ; chlorophyll ; primary production ; Hartbeespoort Dam ; DFAA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Dissolved free amino acid (DFAA) concentration and composition and dissolved organic carbon (DOC) concentration were measured over 16 months at three depths in hypertrophic Hartbeespoort Dam, South Africa and in its two perenially inflowing rivers. The range of DFAA concentrations in the reservoir and both rivers were similar with dominant DFAA consisting of serine, glycine, alanine and ornithine in all three systems. The range of DOC concentrations in the rivers was 1.5–11.1 mg l−1, the major river (Crocodile) having about twice the DOC concentration of the Magalies River. The DFAA/DOC ratios ranged between 0.02–1.1% in the Crocodile River and 0.13–3.7% in the Magalies River. DFAA and DOC concentrations were positively correlated to the Magalies River flow, but for the Crocodile River, which received domestic and industrial effluents, DOC was inversely correlated to flow. The source of DFAA in both rivers was mainly terrestrial, in contrast to the main DOC source in the Crocodile River which was the effluents. The DFAA load of the Crocodile River ranged between 0.22 and 208 kg C d−1. DOC (5.0–24.8mg l−1) in Hartbeespoort Dam generally decreased with depth but DFAA (15–4800 nmol l−1) concentration showed no clear trend. The DFAA/DOC ratios varied between 0.02 and 2.9%. DFAA concentrations were correlated (r = 0.3, n = 30, p = 0.04) with bacterial numbers at 0 and 10 m only while no significant correlations were found with bacterial production, chlorophyll a concentration and phytoplankton primary and EDOC (extracellular DOC) production at any depth. The rate of bacterial utilization of DFAA was low compared with data from other lakes. Diurnal phytoplankton production of DFAA in the euphotic zone of the whole lake was calculated to vary between 268 and 30 780 t C d−1 indicating autochthonous DFAA sources were dominant to allochthonous DFAA sources. The autochthonous production of DFAA was 〉 2 × gross bacterial production of the euphotic zone indicating that although DFAA concentrations were frequently 〈 10 μg C l−1, the rate of DFAA production exceeded bacterial requirements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00006353
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  • 10
    Electronic Resource
    Electronic Resource
    Seasonal variations of metabolically active bacteria in a hypertrophic lake (Hartbeespoort Dam, South Africa) (1988)
    Springer
    Hydrobiologia 160 (1988), S. 179-188 
    Details
    ISSN: 1573-5117
    Keywords: microbial activity ; nalidixic acid ; reservoir ; temperature ; primary production
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The number of metabolically active bacteria was measured with nalidixic acid over two annual cycles at three depths in the epilimnion of hypertrophic Hartbeespoort Dam, South Africa. Concurrent measurements were made of water temperature, DOC, phytoplankton production of dissolved (EDOC) and particulate organic carbon, chlorophyll a and the uptake of glucose (Vmax). The objective was to determine the dominant factors correlated to the number of metabolically active bacteria and the relationship between active bacterial numbers and heterotrophic activity. The number of active bacteria was usually highest at the surface and ranged between 0.70 and 6.82 x 106 cells ml−1. The dominant factors correlated to the number of bacteria at the surface were water temperature (r = 0.65, n = 54, p〈0.001), primary production (r = 0.53, n = 51, p〈0.001) and EDOC (r = 0.37, n = 45, p = 0.005). Surface Vmax for glucose ranged between 0.11 and 4.0 µgC 1−1 h−1 and was positively correlated to the number of active bacteria (r = 0.61, n = 53, p〈0.001). The specific activity index (10−12 µgC cell−1 h−1) varied between 80 and 2290 at the surface and was most strongly correlated to EDOC (r = 0.70, n = 48, p〈0.001). Relationships between active bacterial numbers, water temperature, phytoplankton activity and glucose uptake were also found at two additional depths within the epilimnion. These data suggest that bacterial populations in nutrient enriched lakes contain a large number of metabolically active cells with high individual activity as a result of enhanced phytoplankton growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00015481
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