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Question (Bell): What types of biomass measuring techniques have been tried, which work best, and what are some of the confounding factors involved in working with these crusts? Answer: Several methods have been tried. Biomass can be quantified in direct counts using quantitative counting chambers (such as hemacytometer) and fluorescence microscopy. This gives some indication of numbers and kinds of organisms, although only the common cyanobacterial and diatom species can be identified with confidence. Obtaining biovolume estimates can be done with this method but is very laborious. Another direct method is chlorophyll a determination. This is the easiest and fastest method, but has the drawback that lichen phycobionts...
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We used microsensors to characterize physicochemical microenvironments and photosynthesis occurring immediately after water saturation in two desert soil crusts from southeastern Utah, which were formed by the cyanobacteria Microcoleus vaginatus Gomont, Nostoc spp., and Scytonema sp. The light fields within the crusts presented steep vertical gradients in magnitude and spectral composition. Near-surface light-trapping zones were formed due to the scattering nature of the sand particles, but strong light attenuation resulted in euphotic zones only ca. 1 mm deep, which were progressively enriched in longer wavelengths with depth. Rates of gross photosynthesis (3.4a??9.4 mmol O2A?ma??2A?ha??1) and dark respiration...
Categories: Publication; Types: Citation; Tags: Journal of Phycology
We used microsensors to characterize physicochemical microenvironments and photosynthesis occurring immediately after water saturation in two desert soil crusts from southeastern Utah, which were formed by the cyanobacteria Microcoleus vaginatus Gomont, Nostoc spp., and Scytonema sp. The light fields within the crusts presented steep vertical gradients in magnitude and spectral composition. Near-surface light-trapping zones were formed due to the scattering nature of the sand particles, but strong light attenuation resulted in euphotic zones only ca. 1 mm deep, which were progressively enriched in longer wavelengths with depth. Rates of gross photosynthesis (3.4?9.4 mmol O2�m?2�h?1) and dark respiration (0.81?3.1...
Question (Bell): What types of biomass measuring techniques have been tried, which work best, and what are some of the confounding factors involved in working with these crusts? Answer: Several methods have been tried. Biomass can be quantified in direct counts using quantitative counting chambers (such as hemacytometer) and fluorescence microscopy. This gives some indication of numbers and kinds of organisms, although only the common cyanobacterial and diatom species can be identified with confidence. Obtaining biovolume estimates can be done with this method but is very laborious. Another direct method is chlorophyll a determination. This is the easiest and fastest method, but has the drawback that lichen phycobionts...
The photosynthetic characteristics of the terrestrial cyanobacterium, Nostoc flagelliforme, after complete recovery by rewetting, was investigated to see whether it could use bicarbonate as the external inorganic carbon source when submerged. The photosynthesis?pH relationship and high pH compensation point suggested that the terrestrial alga could use bicarbonate to photosynthesize when submerged. The photosynthetic oxygen evolution rates were significantly inhibited in Na+-free and Na++ Li+ media but were not affected by the absence of Cl?, implying that the bicarbonate uptake was associated with Na+/ HCO3? symport rather than Cl?/HCO3? exchange system. Published in Journal of Phycology, volume 37, issue 5, on...
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Specific growth rate of Cryptomonas ovata var. palustris Pringsheim was measured in batch culture at 14 light-temperature combinations. Both the maximum growth rate (μm) and optimum light intensity (Iopt) fit an empirical function that increases exponentially with temperature up to an optimum (Topt), then declines rapidly as temperature exceeds Topt. Incorporation of these functions into Steele's growth equation gives a good estimate of specific growth rate over a wide range of temperature and light intensity. Rates of phosphate, ammonium and nitrate uptake were measured separately at 16 combinations of irradiance and temperature and following a spike addition of all starved cells initially took up nutrient at a...
Categories: Publication; Types: Citation; Tags: Journal of Phycology
We describe a population of colonial cyanobacteria (waterwarts) that develops as the dominant primary producer in a bottom-fed, O2-poor, warm spring in the Cuatro Ci�negas karstic region of the Mexican Chihuahuan Desert. The centimeter-sized waterwarts were suspended within a central, conically shaped, 6-m deep well by upwelling waters. Waterwarts were built by an Aphanothece-like unicellular cyanobacterium and supported a community of epiphytic filamentous cyanobacteria and diatoms but were free of heterotrophic bacteria inside. Sequence analysis of 16S rRNA genes revealed that this cyanobacterium is only distantly related to several strains of other unicellular cyanobacteria (Merismopedia, Cyanothece, Microcystis)....
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Three cyanobacteria (Microcystis aeruginosa Kutz. emend. Elenkin, Merismopedia tenuissima Lemmermann, and Oscillatoria sp.) and one diatom (Aulacoseira granulata var. angustissima O. Mull. emend. Simonsen) were isolated from the tidal freshwater Potomac River and maintained at 23??C and 40 ??mol photons??m-2??s-1 on a 16:8 L:D cycle in unialgal culture. Photosynthetic parameters were determined in nutrient-replete cultures growing exponentially at 15, 20, 25, and 30??C by incubation with 14C at six light levels. P(B)(max) was strongly correlated with temperature over the entire range for the cyanobacteria and from 15 to 25??C for Aulacoseira, with Q10 ranging from 1.79 to 2.67. The ?? values demonstrated a less...
Categories: Publication; Types: Citation; Tags: Journal of Phycology
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Spatial distributional patterns of benthic diatoms and their relation to current velocity were investigated in an unshaded cobble-bottom reach of White Creek (Washington County, NY). On 27 August 1999, diatoms were sampled and current velocity and depth were measured on a regular square sampling grid with a grain size of 0.01 m2, interval of 0.5 m, and extent of 16 m2. The relative abundance of the 18 common diatom species enumerated in the 81 samples was subjected to detrended correspondence analysis (DCA). The first axis (DCA1) explained 51% of the variance in diatom data and separated the samples according to current regimes. The spatial autocorrelation of DCA1 sample scores in deposition and erosion regions...
Categories: Publication; Types: Citation; Tags: Journal of Phycology