You might not expect Lake Whillans to be a cradle for life, as it’s freezing cold and lies beneath 2,500 feet of Antarctic ice. But as a team of glaciologists recently reported, it is precisely those conditions that nurture microscopic organisms, which feast on the rock beneath the continent.
The 23-square-mile body of water was discovered from space in 2007 and has since become one of the primary resources for glaciologists and biologists eager to understand the ecosystems below Antarctica. These ecosystems are interconnected rivers and lakes that sit under the ice, filled with extremophiles that jive with the cold and pitch-black water. In subglacial Lake Whillans, the locals are mostly bacteria and archaea—not entirely surprising, given the harshness of the conditions. But how do the organisms get by without sunlight or much in the way of food? As the recent team of researchers report in Nature Earth & Environment, pulverized bedrock releases a bevy of compounds that make a healthy diet for such microbes.
“Although the study focused on samples obtained from a single subglacial lake, the results could have much wider implications,” said Beatriz Gill Olivas, lead author of the paper and a glaciologist at the University of Bristol in England, in a university press release. “Subglacial Lake Whillans is part of a large interconnected hydrological system, so erosion taking place upstream could represent a potential source of biologically important compounds to this and other lakes within the system that might harbor thriving communities of microbial life.”
“This is an elegantly done and unique study ... It is a great foundation for future work aimed at detecting organisms and evidence of their metabolisms that may be driven by the erosion of subglacial sediments,” said Trista Vick-Majors, a microbial ecologist at Michigan Technological University who was unaffiliated with the recent paper, in an email.
The organisms in Lake Whillans weren’t just eking out existence; previous research showed they had an abundance of nutrients to sift through, so much so that the lake provided 54 times the amount of carbon necessary to sustain life in an adjacent water body. Without any sunlight to speak of, previous teams suggested, the nutrients—namely nitrogen, iron, sulfur, and carbon compounds—could be derived from the lake sediments.
For want of a subglacial mortar and pestle, the team extracted sediment cores from the lakebed using a borer and ground them up in a lab environment, hoping to induce the sediments into the same sort of chemical reactions they engage in under Antarctica. They crushed the sediments and soaked them in frigid, anoxic water. Gill Olivas’s team found that the sediments could provide 25% of the methane required by microbes that rely on the compound, as well as ammonium, from which many organisms in the water could extract energy. In fact, a single hefty crushing event could supply 120% of the needed amount of ammonium, they said. The crushing sessions also turned up carbon dioxide and hydrogen, the latter of which is an essential part of the microbial diet.
“This research is exciting because it takes sediment from the incredible drilling of Subglacial Lake Whillans and shows that the glacial erosion could sustain microbial processes in a location 800m beneath the ice (with no light!),” said Jane Hart, a glaciologist at the University of Southampton in England who was unaffiliated with the recent paper, in an email. “This study indicates the life can survive in some of the most inhospitable of environments on Earth. Since subglacial erosion occurs beneath all glaciers (and subglacial water bodies are also common), the implication of this study is that there may be vast unexplored subglacial microbial ecosystems beneath other glaciers throughout the world.”
The implications aren’t merely terrestrial (erm, marine). The water under Antarctica is a welcome proxy for planetary scientists hoping to unpack the mysteries of icy moons like Jupiter’s Europa and Saturn’s Enceladus, which may have oceans beneath their icy crusts where similar compounds could exist.
This article was updated to include comments from Trista Vick-Majors and Jane Hart.