Allan Pentecost

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In situ measurements of ultraviolet (UV) irradiance, carbon fixation, and scytonemin pigmentation were made on Scytonema populations from contrasting localities in England. Significant negative correlations were obtained between the following variate pairs: pigmentation and UV irradiance; pigmentation and carbon fixation rate. A significant positive(More)
Phototrophic thermal ecosystems consist of microbial mats whose composition is largely determined by water temperature, dissolved oxygen, sulfide and pH. Mats exposed to sunlight consist of an upper zone of phototrophic bacteria and cyanobacteria and an undermat of heterotrophic bacteria. There is little or no net accumulation of reduced carbon and a(More)
Hardwater streams often contain deposits of calcium carbonate (travertine, tufa) supporting well-defined communities of cyanobacteria. Deposition of carbonate crusts is inhibited by moderate levels (c.100 μg/l) of dissolved orthophosphate phosphorus that can result in their loss, along with their cyanobacteria. Thirteen English cyanobacterium crust(More)
Cyanobacteria were sampled along two vertical and two horizontal transects in the littoral of Devoke Water, English Lake District. Profiles of cyanobacterium diversity and abundance showed that both attained a maximum close to the water line, but declined rapidly 20-40 cm above it. The distribution of individual species with height together with species and(More)
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