Lake home to thousands of microbe species.
An international team of scientists has discovered microbial life in harvested water and sediment samples from the subglacial Lake Whillans in Antarctica. Since the discovery, more testing has revealed over 4,000 species of microbes capable of surviving under 800 metres of ice without sunlight for 120,000 years.
Chemoautotrophs are a first step in the food chain of the complex ecosystem. Unlike autotrophs at the surface which transform sunlight and carbon dioxide into energy necessary for growth, these organisms derive energy from the breakdown of minerals present in the water. These minerals include nitrites, iron, and sulfur compounds. The chemoautotrophs, on the other hand, provide an energy source for microbes on the next tier of the lake’s food chain, and so on, forming a complex web of life that can exist without access to sunlight.
Lake Whillans is one of many subglacial lakes in Antarctica. Eight hundred metres under the ice, the lake measures approximately 60 square kilometres in area and two metres in depth. Below the Antarctic ice, the combination of geothermal heat, pressure and insulation maintains an extensive network of liquid water.
The lake itself presents an exciting area of discovery despite the challenges of reaching its remote location. After years of planning, the Whillans Ice Stream Subglacial Access Research Drilling (WISSARD), funded by the National Science Foundation, succeeded in collecting uncontaminated samples from Lake Whillans using a hot water drill.
The risk of contamination hindered the efforts of British scientists working at a different subglacial lake, making the WISSARD team the first to uncover the secrets held below the Antarctic ice sheets.
The hot water drill used to collect uncontaminated samples from the subglacial lakes is a feat of engineering, given the harsh climate conditions of Lake Whillans, located less than 640 kilometres from the South Pole. The drill uses a water filtration system that incorporates super-fine filters and ultraviolet light, followed by a system that heats the water to roughly 90 degrees Celsius. The hot water is the driving force that allows the drill to bore through roughly 800 metres of ice. A specialized canister is then lowered down to the lake in order to collect samples.
The striking similarities between Lake Whillans and the environment of extraterrestrial bodies make this discovery especially significant to the search for life beyond Earth. For example, Europa, an ice-covered moon of Jupiter, may also contain subglacial water reserves capable of supporting thriving ecosystems.
