The location of the field, including the tents/labs at Subglacial Lake Whillans in Antarctica.Researchers have found that microbes living in Antarctica's ice-covered lakes are eating crushed rocks. The little creatures are flourishing.Subglacial lakes, which are freshwater bodies, are often found in Antarctica. They are trapped between the Earth's crust or bedrock and thick sheets of thick ice, sometimes many miles thick. These lakes are home to a variety of microbes that eat nutrients from the water. Researchers were not able to determine the source of these nutrients until now.As their water levels drop and rise, subglacial lakes naturally erode. Researchers have now replicated this erosion in the laboratory by crushing sediment samples from Lake Whillans, a subglacial lake that covers 23 miles (60 kilometers) and is buried under 2,600 feet (800 metres) of Antarctica ice. This study revealed how essential chemicals are needed to sustain microbes.Related: View photos of this Antarctica subglacial LakeBeatriz Gill Olivas (a glaciologist at Bristol University in the U.K.) said that the study was completely different from any other studies on subglacial lake. While previous studies focused on how erosion of bedrock can produce gases in subglacial environments. Our study looked further at how erosion could release biologically valuable nutrient sources to water.She said that the discovery could have "exciting consequences" for studying how microbial life might develop in other parts of the universe.Constructing sedimentLake Whillans is subject to filling and draining. It is called a high standing when it is full. When it drains, the lake is called a low stand. Low and high stands are only 13 feet (4 metres) apart. High stands can reach depths of 39 feet (12 meters), while low stands drop to 26 feet (8m) in low stands. Gill Olivas stated that the ice stream, a corridor of rapid flow within the ice sheets, comes into direct contact at low stands. She said, "There might be some erosion."Gill Olivas stated that Lake Whillans is part of a larger hydrological network, and erosion in adjacent areas could lead to chemicals entering the larger lake.Researchers reproduced the process of erosion by crushing sediment from Lake Whillans, and then leaving them in water at 32°F (0°C), mimicking the conditions in the lake.Researchers analyzed sediment samples taken from the Whillans Ice Stream Subglacial Research Drilling project. To drill through thick ice sheets, scientists used a hot water drill. After that, they collected samples using a sterilized corer.The photo was taken from a separate project that involved drilling another subglacial lake. (Image credit to Billy Collins/University of BristolChemicals for saleResearchers submerged the crushed rocks for more than 40 days. Then they analyzed the water to determine which chemicals were released from the sediment. The researchers found many different chemicals, including hydrogen, methane and carbon dioxide.Most of these chemicals are released immediately from sediment when it is crushed.Gill Olivas stated that during crushing, sediments are broken down into smaller particles. Fluid inclusions are microscopic bubbles that can be found in minerals and can be cracked open to release liquids and gases trapped within them.She added that gases trapped in individual sediment grains are also released into water.Others were however created as a result of the reaction of certain minerals with water molecules.Microbial communitiesOne group of microbes called methanotrophs use methane to generate energy for growth. Methanogens create energy by converting carbon dioxide and hydrogen into methane. There are also specialized bacteria living in the lake that convert ammonium to nitrogen and then to nitrate. This process is called nitrification.Subglacial lakes often contain compounds that are highly reducing and oxidizing. This means they can easily give or take electrons in chemical reactions. This is also known as a "redox gradient". This allows elements with multiple oxidation states (e.g. iron or sulfur) to be recycled by allowing them easy access to electrons. These elements can be oxidized by specialized microbes called chemolithotrophs to generate energy.Researchers found that for every chemical in the lake, there is a group microbes that can use it to generate energy.Extraterrestrial lifeResearchers searching for extraterrestrial life could find these findings useful. Underground lakes and frozen seas are common in the universe, including in our solar system.Gill Olivas stated that Antarctica's lakes can serve as a proxy for extreme environments on other planet systems. They provide a valuable insight into how microbes might survive in different environments.In essence, erosion is a process where there is ice on sediments or rocks and liquid water. This can provide nutrients and energy for microbial life.Gill Olivas stated that it was impossible to say whether these processes would be able to sustain exoplanetary microbes. It does however provide some insight into how microbes on icy moons and planets might survive.The study was published in Communications Earth & Environment online on June 29, 2009.Original publication on Live Science
