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Cyanobacterial diversity and activity in modern conical microbialites
1Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA. tbosak@mit.edu
Geobiology
|June 21, 2012
Summary
Modern conical microbialites host diverse cyanobacteria, with unicellular types more active in nutrient-rich areas. Diffusion limitation likely shapes microbialite cone growth, mirroring ancient stromatolite formation.
Area of Science:
- Microbiology
- Geology
- Biogeochemistry
Background:
- Modern conical microbialites resemble ancient stromatolites, but cyanobacterial communities and growth dynamics are poorly understood.
- Cyanobacteria are key in microbialite formation, yet their specific roles in modern conical structures require detailed investigation.
Purpose of the Study:
- To analyze cyanobacterial diversity and activity in modern conical microbialites from Yellowstone National Park.
- To compare cyanobacterial communities and their carbon assimilation in cone tips versus surrounding mats.
- To elucidate the factors influencing the development and persistence of conical microbialite morphology.
Main Methods:
- 16S rRNA gene sequencing to determine cyanobacterial diversity in microbialites from 14 thermal ponds.
- High-resolution mapping of labeled carbon to assess cyanobacterial activity.
- Spatial analysis of cyanobacterial density and degradation within cone tips and mats.
Main Results:
- Cones and mats harbor similar cyanobacteria (Subsection I unicellular, Subsection III filamentous), varying across ponds and years.
- Unicellular cyanobacteria show higher diversity and faster nutrient response in mats compared to filamentous types.
- Active cyanobacteria are densest below 50 μm in cone tips; mat cyanobacteria are less dense and more degraded/encrusted.
Conclusions:
- Diffusion limitation significantly influences the development and persistence of conical microbialite shapes.
- Cyanobacterial community structure and activity patterns provide insights into microbialite formation.
- These findings suggest similar growth mechanisms for modern microbialites and ancient conical stromatolites.
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