When the small paint the big picture: Using microbes to identify a hydrothermal habitat at the Chilean Triple Junction.

The deep sea of Southern Chile remains largely unknown yet hosts one of the few spots on the planet where hydrothermal vent and cold seep habitats may co-occur. The Chilean Triple Junction was recently discovered to host warm sediment at 2900 meters water depth in close proximity to a methane seep. While this may present a model system to study cross vent and seep synergies, there were no obvious surface manifestations of the underlying hydrothermal activity. This begs the question whether the community present was impacted by the warm fluid and associated chemoautotrophic energy. Here we answer that question through analysis of the microbial community structure. Using Amplicon based 16s rRNA analysis of the top 20cm of sediment, we found a total of 3,300 operational taxonomic units within the 119,000 bacterial and archaeal sequence recovered. The most abundant fraction of bacteria throughout the sediment column were proteobacteria with gammaproteobacteria dominant at the surface and deltaproteobacteria becoming more dominant at depth. Similarly, Crenarchaea were more abundant at the surface and Euryarchaea increasing in prevalence with increasing depth. In addition to mesophilic species, a diversity of bacteria and archaea related to methane cycling were found, including methanotrophic bacteria, ANME-1 archaea and deltaproteobacteria that are often associated with the anaerobic oxidation of methane. These lineages were most abundant below 6 cm below seafloor (cmbsf) with the ANME sequence present at 14-16 cmbsf. In comparison to the macrofaunal community structure, which was merely suggestive of hydrothermal influence, the microbial community presented the most conclusive evidence that the warm temperatures and abundant methane in this habitat had biological implications. When combining our new understanding of both the metazoan and microbial communities at this location, we can now place this warm-mud community from an unexplored region of the globe in our understanding of reducing habitat biogeography. Further study may provide insight into the evolutionary connections among reducing habitats utilizing this site.

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First Name: 
Andrew
Last Name: 
Thurber
Telephone: 
5417378251
Affiliation: 
Oregon State University
First Name: 
Fredrick
Last Name: 
Colwell
Affiliation: 
OSU
First Name: 
Erick
Last Name: 
Dowell
Affiliation: 
OSU/ UNC Chapel Hill
First Name: 
Lisa
Last Name: 
Levin
Affiliation: 
Scripps Institution of Oceanography
First Name: 
Donna
Last Name: 
Blackman
Affiliation: 
Scripps Institution of Oceanography
First Name: 
Chris
Last Name: 
German
Affiliation: 
WHOI
Choose keywords that are most applicable to your abstract. (Three maximum.): 
Biogeography
Distribution and abundance
Microbiology
Abstract ID: 
CBE5-183