Abstract
Many deep-sea hydrothermal vent systems are regularly impacted by volcanic eruptions, leaving fresh basalt where abundant animal and microbial communities once thrived. After an eruption, microbial biofilms are often the first visible evidence of biotic re-colonization. The present study is the first to investigate microbial colonization of newly exposed basalt surfaces in the context of vent fluid chemistry over an extended period of time (4–293 days) by deploying basalt blocks within an established diffuse-flow vent at the 9°50′ N vent field on the East Pacific Rise. Additionally, samples obtained after a recent eruption at the same vent field allowed for comparison between experimental results and those from natural microbial re-colonization. Over 9 months, the community changed from being composed almost exclusively of Epsilonproteobacteria to a more diverse assemblage, corresponding with a potential expansion of metabolic capabilities. The process of biofilm formation appears to generate similar surface-associated communities within and across sites by selecting for a subset of fluid-associated microbes, via species sorting. Furthermore, the high incidence of shared operational taxonomic units over time and across different vent sites suggests that the microbial communities colonizing new surfaces at diffuse-flow vent sites might follow a predictable successional pattern.
Highlights
Microbes form the basis of the highly productive deep-sea hydrothermal vent ecosystems and serve as partners in symbiotic relationships or as food for fauna (Lutz and Kennish, 1993)
The dissolved sulfide concentrations ranged from 10 to 100 μM and the mean value of dissolved sulfide was in the range of 20–30 μM
We studied bacterial diversity on basalt surfaces at diffuse flow vent sites (Figure 1) using a combination of full-length Sanger sequencing of 16S rRNA clones and 454-pyrosequencing of the hypervariable V4 region of 16S rRNA (V4 tags)
Summary
Microbes form the basis of the highly productive deep-sea hydrothermal vent ecosystems and serve as partners in symbiotic relationships or as food for fauna (Lutz and Kennish, 1993). These metabolically versatile chemosynthetic microbes harness chemical disequilibria created by the mixing of reduced hydrothermal fluids with oxygenated deep-sea water either above or below the seafloor (Baross and Hoffman, 1985; Jannasch and Mottl, 1985; Nakagawa and Takai, 2008). There are multiple sites of fluid venting, separated by meters to 100s of meters, including both focused-flow and diffuse-flow vent sites. At diffuse-flow sites, seawater mixes with hydrothermal fluid within the ocean crust, and is released as warm fluids (typically < 50◦C) through cracks in the seafloor
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