Hawaiian Islands [source: SOEST]
The Loihi Seamount (summit at ~1000 m below surface) is a seismically active submarine volcano that represents an emerging Hawaiian island. Following several studies in the late 1980's that predicted hydrothermal venting based on enrichments of various gases and metals in the water column over Loihi, two hydrothermal fields were discovered by Dave Karl and colleagues.
Loihi bathymetry [credit: Brad Bailey]
Since these hydrothermal fields were discovered, it has been recognized that the geochemistry and biology of Loihi render this system distinct among known deep-sea hydrothermal environments.
For example, the vent fluids at Loihi are highly enriched in iron and carbon dioxide but are low in sulfide. Low oxygen and pH are important factors in supporting the high Fe concentrations, one of the hallmark geochemical features of Loihi. These chemical characteristics, manifested as gradients set up by venting fluids and weathering rocks make perfect environments for iron-oxidizing bacteria (FeOB) to thrive in.