Page 5 - Impact Summer 2021

ROV JASON HEADS FOR THE SEAFLOOR.
“WHAT HAPPENS WHEN THE HEAT
STOPS?”
HOT TO COLD
Hydrothermal vents were discovered about 40 years ago, and scientists are still asking questions about the complex and alien ecosystems they support. An experiment Jones is involved in, called Hot2Cold Vents, asks “what happens when the heat stops?”
Because the tectonic plates are constantly moving, a mound will eventually move off of its geothermal energy source. At the rate of a few inches per year, this can take decades to thousands of years. What will happen to the microbes and the rest of the ecosystem when the vent fluids are no longer supplying the rocks with chemical energy?
In 2019, on a previous research cruise, Jones and her collaborators set this process in motion on a faster timescale by removing rock samples from an active hot vent and letting them cool. They brought some samples to the surface to analyze, and left some rocks on the seafloor to cool gradually. This cruise was an opportunity to go back and collect those rocks, which have been detached from the vent for two years.
While exploring with ROV Jason, Jones was fortunate enough to discover some naturally deceased vents as well. These “old, dead sites” can shed light on the changes that active vents will eventually undergo.
BACK ON LAND
Back on land, Jones is preparing her seafloor samples to be run on a synchrotron, an instrument that uses X-rays to characterize the mineral composition of the rocks she’s collected.
“We can use these X-ray techniques to get a microbe’s-eye view of the world,” she said. Because the seafloor microbes harness energy from the rocks, they leave behind chemical signatures of their presence. Those minute changes can be detected by the synchrotron.
Jones now has rock samples from active hydrothermal vents, her two-year-old cooled samples, and the naturally inactive sites she discovered. By looking at this array of rocks, she’ll begin to understand the progression of these microbes through the chemical changes preserved inside.
JONES SAILED ON ROGER REVELLE, A GLOBAL CLASS OCEANOGRAPHIC RESEARCH VESSEL.
ROSE JONES AND TONER LAB COLLEAGUE ADRIAN WACKETT CONDUCT LAB WORK ON THE SHIP.