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  • 1
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    In:  http://aquaticcommons.org/id/eprint/15633 | 8 | 2014-11-13 21:43:17 | 15633
    Publication Date: 2021-07-09
    Description: Fluctuations in primary productivity at two subalpine lakes reveal both meteorological and biological influences. At Castle Lake, California, large-scale climate events such as the El Niño/Southern Oscillation affect total annual production and, combined with human fishing activity, modify the seasonal pattern of productivity. At Lake Tahoe, California-Nevada, local spring weather conditions modulate annual production and its seasonality by determining the depth of mixing and resulting internal nutrient load. Climatic conditions also contribute to deviations from the long-term trend in productivity by increasing the incidence of forest fires and through anomalous external nutrient loads during precipitation extremes. A 3-year cycle in productivity of as yet unknown origin has also been detected at Lake Tahoe.
    Keywords: Atmospheric Sciences ; Ecology ; Limnology ; PACLIM
    Repository Name: AquaDocs
    Type: conference_item
    Format: application/pdf
    Format: application/pdf
    Format: 71-80
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Water Resources Association 17 (1981), S. 0 
    ISSN: 1752-1688
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: : The fate and effect of sodium chloride applied to Californian highways in the Lake Tahoe, Truckee River, and Yuba River watersheds were studied over a period of 14 months in 1974–75. Chloride levels in streams below major freeways were found to be elevated during the winter. The high chloride levels occurred after the application of salt to roads, decreasing as the time from application increases. Small lakes receiving runoff from major highways were also enriched with chloride. Several of these lakes displayed a temporary chemocline, which was sufficiently strong to stabilize a temperature inversion in one lake.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SUMMARY. 1. The influence of temperature on in vivo photosynthetic and in vitro respiratory electron transport system (ETS) activity was determined over the season for the 3 m (warm-water) and a 20m (cold-water) phytoplankton communities in Castle Lake. The optimum temperature of photosynthesis at 3 m (X̄=20.8°C) was significantly higher than the average optimum at 20 m (X̄=14.8°C).2. Seasonally, the photosynthetic temperature optimum increased when the blue-green alga Chroococcus limneticus Lemm. was present. The temperature characteristics of this organism were maintained even after it had settled into the cold water of the hypolimnion.3. Temperature optima were not significantly different in experiments conducted under limiting or saturating photosynthetic photon flux densities (PPFD).4. Short-term (1 h) preincubations with dissolved inorganic nitrogen (DIN) (≃80 μg NH4NO3-N l−1) had little effect on the temperature characteristics of photosynthesis while the longer (〉24 h) incubations provided by a whole-lake epilimnetic DIN addition (≃75 μg NH4NO3- N l−1) significantly lowered the photosynthetic temperature optimum to 12.5°C. Once this epilimnetic DIN was depleted the optimum roseto25°C, a value higher than that present before the enrichment, which coincided with the growth of C limneticus.5. Respiratory ETS activity usually began to inactivate between 19 and 20°C. However, when C. limneticus was abundant the inactivation temperature was often greater ihan 25°C.6. The average energy of activation (E) and Q10 value for the 3 m community (15.9 kcal mol−1 and 2.6 respectively) were significantly higher than those at 20 m (14.2 kcal mol−1 and 2.4 respectively). Seasonally, the highest E and Q10 values of ETS activity occurred during the late-summer bloom of C. limneticus.7. These results demonstrate that the epilimnetic and hypolimnetic phytoplankton communities in Castle Lake are physiologically distinct with regards to their temperature characteristics.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. A series of experiments examined growth of Daphnia magna on three algal diets (Rhodomonas minuta, Scenedesmus acutus and Synechococcus sp.) at varying physiological states [nitrogen and phosphorus (P) limitations] to test whether variation in algal fatty acid and/or elemental composition can predict Daphnia growth.2. These algae differed widely in their essential fatty acid (EFA) composition while phosphorus (P) or nitrogen limitation had only a small influence on their ω3-polyunsaturated fatty acid (PUFA) content.3. Individually, algal ω3-PUFA content explained 69% of the variation in the normalised growth of D. magna, while algal phosphorus content explained 11% of the variation. Quantitative models for D. magna growth used both algal ω3-PUFA content and algal C : P ratio as food quality indices. Together, algal ω3-PUFA content and C : P ratio explained 70% of the variation in the normalised growth rate of D. magna.4. Our results indicate that EFA influenced algal food quality much more strongly than P. The EFA and mineral P impacts appear to be independent.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of agricultural and food chemistry 26 (1978), S. 1230-1234 
    ISSN: 1520-5118
    Source: ACS Legacy Archives
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Water Resources Association 38 (2002), S. 0 
    ISSN: 1752-1688
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: : The sampling of streams and estimation of total loads of nitrogen, phosphorus, and suspended sediment play an important role in efforts to control the eutrophication of Lake Tahoe. We used a Monte Carlo procedure to test the precision and bias of four methods of calculating total constituent loads for nitrate-nitrogen, soluble reactive phosphorus, particulate phosphorus, total phosphorus, and suspended sediment in one major tributary of the lake. The methods tested were two forms of the Beale's Ratio Estimator, the Period Weighted Sample, and the Rating Curve. Intensive sampling in 1985 (a dry year) and 1986 (a wet year) provided a basis for estimating loads by the “worked record” method for comparison with estimates based on resampling actual data at the lower intensity that characterizes the present monitoring program. The results show that: (1) the Period Weighted Sample method was superior to the other methods for all constituents for 1985; and (2) for total phosphorus, particulate phosphorus, and suspended sediment, the Rating Curve gave the best results in 1986. Modification of the present sampling program and load calculation methods may be necessary to improve the precision and reduce the bias of estimates of total phosphorus loads in basin streams.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The factors that regulate energy transfer between primary producers and consumers in aquatic ecosystems have been investigated for more than 50 years (refs 1,2,3). Among all levels of the food web (plants, herbivores, carnivores), the plant–animal interface ...
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Determining the factors that control food web interactions is a key issue in ecology. The empirical relationship between nutrient loading (total phosphorus) and phytoplankton standing stock (chlorophyll a) in lakes was described about 30 years ago and is central for managing surface water ...
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Water Resources Association 26 (1990), S. 0 
    ISSN: 1752-1688
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: Atmospheric scientists have predicted that large-scale climatic changes will result from increasing levels of tropospheric CO2 We have investigated the potential effects of climate change on the primary productivity of Castle Lake, a mountain lake in Northern California. Annual algal productivity was modeled empirically using 25 years of limnological data in order to establish predictive relationships between productivity and the climatic variables of accumulated snow depth and precipitation. The outputs of monthly temperature and precipitation from three general circulation models (GCMs) of doubled atmospheric CO2 were then used in the regression model to predict annual algal productivity. In all cases, the GCM scenarios predicted increased algal productivity for Castle Lake under cenditions of doubled atmospheric CO2The primary cause of enhanced productivity was the increased length of the growing season resulting from earlier spring ice-out.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The symbiotic fern Azolla filiculoides var. rubra, which contains a blue-green nitrogen fixing alga Anabaena azollae, fixed 164 Kg N·ha-1·ann-1 in the littoral zone of a small eutrophic lake. Associated planktonic Anabaena spp. blooms, dominated by Anabaena spiroides, fixed 29.5Kg N·ha-1·ann-1. Nitrogen fixation in both organisms was not obviously related to ambient dissolved inorganic nitrogen levels. By comparing 15N−N2 and acetylene reduction techniques, we determined a ratio of 3 moles C2H2 reduced to 1 mole of N2 fixed. Combining this with results from one diurnal investigation, it was estimated that 24% of the total daily fixation by Azolla occurred at night. Highest nitrogen fixation rates in Azolla occurred when plant density was lowest. Nitrogen fixation by planktonic Anabaena spp. generally paralleled changes in biomass. Frond breakage due to wind caused a decrease in Azolla nitrogen fixation and growth which was followed by a bloom of planktonic Anabaena spp. A second Anabaena spp. bloom was instrumental in the summer decline of Azolla. Maximum growth and nitrogen fixation of both organisms did not occur simultaneously. If physical disruption to the Azolla mat does not occur, it is likely that growth of the population would continue throughout the year.
    Type of Medium: Electronic Resource
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