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Sediment Microbial Communities Influenced by Cool Hydrothermal Fluid Migration

Frontiers in Microbiology. 2018;9 DOI 10.3389/fmicb.2018.01249

 

Journal Homepage

Journal Title: Frontiers in Microbiology

ISSN: 1664-302X (Online)

Publisher: Frontiers Media S.A.

LCC Subject Category: Science: Microbiology

Country of publisher: Switzerland

Language of fulltext: English

Full-text formats available: PDF, HTML, ePUB, XML

 

AUTHORS


Laura A. Zinke (Marine and Environmental Biology Section, University of Southern California, Los Angeles, CA, United States)

Brandi Kiel Reese (Department of Life Sciences, Texas A&M University – Corpus Christi, Corpus Christi, TX, United States)

James McManus (Department of Geosciences, The University of Akron, Akron, OH, United States)

James McManus (Bigelow Laboratory for Ocean Sciences, East Boothbay, ME, United States)

Charles G. Wheat (Global Undersea Research Unit, University of Alaska Fairbanks, Moss Landing, CA, United States)

Beth N. Orcutt (Bigelow Laboratory for Ocean Sciences, East Boothbay, ME, United States)

Jan P. Amend (Marine and Environmental Biology Section, University of Southern California, Los Angeles, CA, United States)

Jan P. Amend (Department of Earth Sciences, University of Southern California, Los Angeles, CA, United States)

EDITORIAL INFORMATION

Blind peer review

Editorial Board

Instructions for authors

Time From Submission to Publication: 14 weeks

 

Abstract | Full Text

Cool hydrothermal systems (CHSs) are prevalent across the seafloor and discharge fluid volumes that rival oceanic input from rivers, yet the microbial ecology of these systems are poorly constrained. The Dorado Outcrop on the ridge flank of the Cocos Plate in the northeastern tropical Pacific Ocean is the first confirmed CHS, discharging minimally altered <15°C fluid from the shallow lithosphere through diffuse venting and seepage. In this paper, we characterize the resident sediment microbial communities influenced by cool hydrothermal advection, which is evident from nitrate and oxygen concentrations. 16S rRNA gene sequencing revealed that Thaumarchaea, Proteobacteria, and Planctomycetes were the most abundant phyla in all sediments across the system regardless of influence from seepage. Members of the Thaumarchaeota (Marine Group I), Alphaproteobacteria (Rhodospirillales), Nitrospirae, Nitrospina, Acidobacteria, and Gemmatimonadetes were enriched in the sediments influenced by CHS advection. Of the various geochemical parameters investigated, nitrate concentrations correlated best with microbial community structure, indicating structuring based on seepage of nitrate-rich fluids. A comparison of microbial communities from hydrothermal sediments, seafloor basalts, and local seawater at Dorado Outcrop showed differences that highlight the distinct niche space in CHS. Sediment microbial communities from Dorado Outcrop differ from those at previously characterized, warmer CHS sediment, but are similar to deep-sea sediment habitats with surficial ferromanganese nodules, such as the Clarion Clipperton Zone. We conclude that cool hydrothermal venting at seafloor outcrops can alter the local sedimentary oxidation–reduction pathways, which in turn influences the microbial communities within the fluid discharge affected sediment.