At first glance, the inky Antarctic waters lying beneath nearly 2,500 feet of solid ice don't seem like a hospitable place for fish – or anything else – to make their home. But that's exactly what a team of scientists discovered.
The research team was drilling in the Ross Ice Shelf, a glacier the size of France off the coast of Antarctica, to investigate stability of the Whillans Ice Stream, a major glacier that flows into the shelf. To explore the waters below, the researchers employed Deep-SCINI, a remotely operated vehicle designed to travel through narrow fissures in the ice.
When Deep-SCINI reached the ocean floor it saw a shadow, then the body that cast it.
“I’m surprised. I’ve worked in this area for my whole career,” Ross Powell, a veteran Northern Illinois University glacial geologist who co-led the expedition with two other scientists, told Scientific American. “You get the picture of these areas having very little food, being desolate, not supporting much life.”
The fish was the length of a butter knife, had bulb-eyes and its internal organs shown through its pinkish translucent body. Throughout the day Deep-SCINI encountered between 20 and 30 animals, including black and orange fish, dozens of crustaceans, and other marine invertebrates.
One has to wonder how these fish survive in such an extreme and closed environment, one in which the nearest shaft of sunlight is at the edge of the shelf, some 500 miles away.
“We have to ask what they’re eating,” Brent Christner, a microbiologist from Louisiana State University, told Scientific American. “Food is in short supply and any energy gained is hard-won. This is a tough place to live.”
There are several theories.
The ecosystem could be powered by plankton, grown in the sunlit waters of the Ross Sea and then swept under the ice, but scientists predict that it would take 6 to 7 years for plankton to travel that far under the Ross Ice Shelf. Alternatively, in the absence of sunlight, life could be powered by chemical energy, such as ammonium from the Earth’s interior.
The latter seems more likely, since a few years ago an ecosystem fueled by ammonium was discovered in a subglacial lake, but the only lifeforms were microbes.
Christner believes that the water and mud samples they collected will be able to help answer the many questions that remain.
While this situation is unexpected, extremophiles – organisms that live in environments that would kill most lifeforms – are not. Even under the most extreme pressures and temperatures, scientists almost always find traces of life.
The impossibly harsh environment in which life still manages to thrive gives hope to the idea of finding life in other unlikely places, such as Jupiter's moon, Europa, which, like Antarctica, is thought to have liquid water locked beneath its icy crust.