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Metabolic capability and phylogenetic diversity of Mono Lake during a bloom of the eukaryotic phototroph Picocystis sp. strain ML

October 17, 2018
Algal blooms in lakes are often associated with anthropogenic eutrophication; however, they can occur without the human introduction of nutrients to a lake. A rare bloom of the alga Picocystis sp. strain ML occurred in the spring of 2016 at Mono Lake, a hyperalkaline lake in California, which was also at the apex of a multiyear-long drought. These conditions presented a unique sampling opportunity to investigate microbiological dynamics and potential metabolic function during an intense natural algal bloom. We conducted a comprehensive molecular analysis along a depth transect near the center of the lake from the surface to a depth of 25 m in June 2016. Across sampled depths, rRNA gene sequencing revealed that Picocystis-associated chloroplasts were found at 40 to 50% relative abundance, greater than values recorded previously. Despite high relative abundances of the photosynthetic oxygenic algal genus Picocystis, oxygen declined below detectable limits below a depth of 15 m, corresponding with an increase in microorganisms known to be anaerobic. In contrast to previously sampled years, both metagenomic and metatranscriptomic data suggested a depletion of anaerobic sulfate-reducing microorganisms throughout the lake's water column. Transcripts associated with photosystem I and II were expressed at both 2 m and 25 m, suggesting that limited oxygen production could occur at extremely low light levels at depth within the lake. Blooms of Picocystis appear to correspond with a loss of microbial activity such as sulfate reduction within Mono Lake, yet microorganisms may survive within the sediment to repopulate the lake water column as the bloom subsides.
Publication Year 2018
Title Metabolic capability and phylogenetic diversity of Mono Lake during a bloom of the eukaryotic phototroph Picocystis sp. strain ML
DOI 10.1128/AEM.01171-18
Authors Blake W. Stamps, Heather S Nunn, Victoria Petryshyn, Ronald S. Oremland, Laurence G. Miller, Michael R. Rosen, Kohen Bauer, Katherine J. Thompson, Elise M. Tookmanian, Anna R. Waldeck, Sean J Lloyd, Hope A Johnson, Bradley S. Stevenson, William M Berelson, Frank A Corsetti, John R. Spear
Publication Type Article
Publication Subtype Journal Article
Series Title Applied and Environmental Microbiology
Index ID 70233589
Record Source USGS Publications Warehouse
USGS Organization WMA - Earth System Processes Division