Project: Linking biogeochemistry and microbial community dynamics in deep-sea hydrothermal plumes

Description from NSF award abstract:
Deep-sea hydrothermal vent plumes are globally distributed along the 60,000-km mid-ocean ridge system and are hot spots of microbial biogeochemistry in the deep oceans. These plumes play host to important interactions between microbial communities and hydrothermal inputs; hydrothermal energy sources stimulate enhanced microbial activity and productivity, and microorganisms mediate the flux of elements and energy from deep-sea hydrothermal vents into the oceans. This hydrothermal flux is a significant source of two key micronutrients, iron and manganese, for the oceans. Despite this importance, microbial communities in deep sea-hydrothermal plumes have been understudied relative to those inhabiting near-vent and subsurface environments. The overall goal of this project is to reveal the microbial community dynamics responsible for enhanced microbial activities and mediation of geochemical processes that has been observed in deep-sea hydrothermal plumes. This research project is focused on plumes in the Guaymas Basin (Gulf of California), where previous results showed dramatic enhancement of microbial activity and enzymatic manganese (II) oxidation relative to the ambient deep sea. Cutting-edge DNA sequencing technologies will be utilized to characterize the microbial diversity, metabolic potential and physiological state of plume versus background communities through metagenomics and metatranscriptomics. The specific objectives are:
(1) to utilize hundreds of thousands of rRNA gene sequences available from DNA and RNA to compare community structure and population-specific activity in plumes versus background;
(2) to reconstruct composite genomes from the most abundant deep-sea microbial populations and evaluate their metabolic capabilities and nutritional needs; and
(3) to quantitatively compare gene content and expression profiles in plume and background, with a focus on uncovering metabolic shifts towards chemolithoautotrophy.

Overall, results are expected to shed light on the nature of microbial players and processes in plumes: is plume biogeochemistry mediated by indigenous deep-sea microorganisms that have been stimulated by hydrothermal inputs, or by plume-specific groups that were entrained from near-vent environments?