“The vent fluid chemistry has profound effects on ocean water and offers a rare glimpse into microbial life that may have lived in places like these since the first oceans formed 3.8 billion years ago,” says McDermott. “The whole system is dependent on chemical energy rather than sunlight.”
At her Lehigh lab, McDermott examines the samples for clues about the chemical energy that makes life possible. She is most interested in how the chemicals are being formed: biotically, from living or once-living materials, or abiotically, in the absence of life.
“There is a lot of chemical potential in the vents to form organic molecules, containing carbon and hydrogen, either abiotically or biotically through microbial activity,” says McDermott. “Are these molecules found in the absence of life? The transition between abiotic to biotic interests me most.”
She wants to know: which molecules are here because of the living material that was already present and which, if any, developed from nonliving material?
The answer to that question is the “holy grail” of her field: defining abiotic pathways to create organic molecules, derived in the absence of the life. Such molecules, termed “probiotic chemistry” are an important precursor step along the pathway to form the complicated molecules that make up living things.
Has any evidence of such prebiotic molecules been found in hydrothermal vents on earth or elsewhere?
“There is strong evidence for the abiotic production of methane, hydrocarbons and a simple organic acid in hydrothermal vent settings,” says McDermott. “But as for more complex molecules, not yet. They are either absent, in low abundance, or have yet to be discovered.”
Nereid Under-Ice: a one-of-a-kind underwater robot
The hydrothermal vents at the Karasik Seamount of Gakkel Ridge are around 3,100 meters (more than 10,000 feet) below the ocean’s surface.
There is only one remotely operated vehicle (ROV) capable of navigating ice-covered water and sampling vents that far down: the Nereid Under-Ice.
A highly specialized underwater robot, Woods Hole Oceanographic Institution’s Nereid Under-Ice is built to travel up to 40 kilometers (25 miles) laterally underwater while still receiving control signals and transmitting data, including high-definition video, back to operators located on a ship via a hair-thin fiber-optic tether. The vehicle can dive up to 2,000 meters (6,500 feet) beneath the surface to sample or survey the ice-water interface, the mid-water or the seafloor. Last year’s Arctic trip was the second successful expedition for this deep-sea submarine to the Arctic sea floor.
The Polarstern team also used a conductivity temperature depth (CTD) rosette, which senses and determines the properties of sea water by measuring temperature, salinity and density.