Co-registered Geochemistry and Metatranscriptomics Reveal Unexpected Distributions of Microbial Activity within a...

Area of Science:

• Marine microbiology
• Deep-sea ecosystems
• Hydrothermal vent biogeochemistry

Background:

• Microbial activity at diffuse flow hydrothermal vents is extensively studied, yet niche diversity remains unclear.
• Understanding microbial adaptations to varying physical and geochemical conditions is crucial for deep-sea ecosystem research.

Purpose of the Study:

• To investigate microbial niche diversity in diffuse flow hydrothermal vents.
• To correlate microbial activity with specific physical and geochemical conditions.
• To identify previously overlooked productive habitats within deep-sea vent fields.

Main Methods:

• Co-registered metatranscriptomic and geochemical data collection from ASHES vent field, Juan de Fuca Ridge.
• Analysis of microbial populations across diverse fluid regimes (cool, warm, and hydrothermal).
• Metabolic activity assessment, including carbon fixation, of dominant microbial groups.

Main Results:

• Gammaproteobacteria dominated microbial activity in cool and warm fluids, indicating a broad tolerance to chemical conditions.
• Epsilonproteobacteria were primarily active only in the warmest, most hydrothermally influenced flows.
• Significant microbial metabolic activity, including carbon fixation, was observed in intra-field water, suggesting a highly productive habitat.

Conclusions:

• Gammaproteobacteria act as generalists in hydrothermal vents, thriving across a wider range of geochemical conditions than Epsilonproteobacteria.
• Diffuse flow fields represent significant, underappreciated primary production sites in the deep sea.
• These findings emphasize the global importance of deep-sea biogeochemical cycling in previously overlooked habitats.