d in the lake samples.
This is where the rock-eating comes in. Iron and sulfides could get into the water from rocks ground up when the glacial ice rubs against the bedrock of the continent. “In a sense the microbes ‘eat rock’—although in practice they attach to the mineral particles and help them dissolve,” writes Martyn Tranter, a glaciologist at the University of Bristol, in a companion Nature editorial. The ammonium is likely produced by bacteria that eat dead microbes in the lake.
There’s still a host of unanswered questions about the residents of Lake Whillans and how they contribute to the ecosystem of the Southern Ocean. Further investigation might reveal the role these subglacial creatures play in larger chemical and biological cycles on Earth. Meanwhile, other researchers are excited about the implications for extraterrestrial oceans.
“The fact that the concentration and diversity of life detected in this subglacial lake exists means there is a very good sign for the existence of life on Europa, even if the details are different,” says Cynthia Phillips, a planetary geologist at the SETI Institute in California. Lake Whillans isn’t an identical twin to the icy oceans thought to exist under the Jupiter moon’s icy crust. Europa’s surface is probably more than six miles thick, and its oceans extend 31 miles beyond that. We also don’t yet know whether Europa’s oceans come with a handy, nutrient rich layer of marine sediment. But Lake Whillans’ ecosystem is still the closest thing we’ve seen to the alien microbes that might be swimming in oceans far, far away.