Marine life persists even when hydrothermal sea vents go dormant and their blazing warmth transforms to frigid cold, a new study has revealed.
A team led by USC microbiologist Katrina Edwards found that the microbes that thrive on hot fluid methane and sulphur spewed by active hydrothermal vents are supplanted, once the vents go cold, by microbes that feed on the solid iron and sulphur that make up the vents themselves.
These findings – based on samples collected for Edwards by US Navy deep sea submersible Alvin (famed for its exploration of the Titanic in 1986) – provide a rare example of ecological succession in microbes.
Ecological succession is the biological phenomenon whereby one form of life takes the place of another as conditions in an area change – a phenomenon well-documented in plants and animals.
Scientists have long known that active vents provided the heat and nutrients necessary to maintain microbes. But dormant vents – lacking a flow of hot, nutrient-rich water – were thought to be devoid of life.
Hydrothermal vents are formed on the ocean floor with the motion of tectonic plates. Where the sea floor becomes thin, the hot magma below the surface creates a fissure that spews geothermally heated water – reaching temperatures of more than 400 degree C.
After a (geologically) brief time of actively venting into the ocean, the same sea floor spreading that brought them into being shuffles them away from the hotspot. The vents grow cold and dormant.
“Hydrothermal vents are really ephemeral in nature,” said Edwards, professor of biological sciences at the USC Dornsife College of Letters, Arts and Sciences.
Microbial communities on sea floor vents have been studied since the vents themselves were first discovered in the late 1970s. Until recently, little attention had been paid to them once they stopped venting, though.
USC graduate researcher Jason Sylvan said he would like to take samples on vents of various ages to catalogue exactly how the succession from one population of microbes to the next occurs.
The study has been published in mBio.