Deep sub-seafloor prokaryotes stimulated at interfaces over geological time
R John Parkes1, Gordon Webster, Barry A Cragg
1School of Earth, Ocean and Planetary Sciences, Cardiff University, Main Building, Park Place, Cardiff CF10 3YE, UK. j.parkes@earth.cf.ac.uk
Nature
|July 22, 2005
Summary
Deep within the ocean
Area of Science:
- Marine microbiology
- Geochemistry
- Deep biosphere research
Background:
- The sub-seafloor biosphere represents Earth's largest prokaryotic habitat.
- Prokaryotes in this environment exhibit exceptionally low metabolic rates.
- Understanding deep prokaryotic activity is crucial for comprehending global biogeochemical cycles.
Purpose of the Study:
- To investigate prokaryotic activity and biodiversity in deep sub-seafloor environments.
- To identify factors stimulating prokaryotic processes at geochemical and sedimentary interfaces.
- To assess the long-term activity of deep sedimentary prokaryotes.
Main Methods:
- Sampling and analysis of sub-seafloor environments at Pacific Ocean margin and open ocean sites.
- Quantification of prokaryotic numbers and activity rates at various depths.
- Analysis of high-molecular-mass DNA to assess prokaryotic viability and biodiversity.
- Correlation of prokaryotic community changes with geochemical and sedimentary data.
Main Results:
- Deep subsurface stimulation of prokaryotic processes was observed at both margin and open ocean sites.
- At the margin site, a 13-fold increase in prokaryote numbers and high activity rates were noted at 90 m depth.
- Biodiversity changes were coupled to geochemistry, with a distinct community shift at the 90-m interface.
- In the open ocean, increased prokaryotic numbers and activity correlated with ancient diatom-rich sediments.
- Deep sedimentary prokaryotes demonstrated high activity and changing diversity over geological timescales.
Conclusions:
- Deep sedimentary prokaryotes can exhibit significant metabolic activity.
- Prokaryotic diversity in the sub-seafloor is dynamic and influenced by geochemical and sedimentary interfaces.
- Prokaryotic life persists and remains active in deep sub-seafloor environments over geological time.
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