Life found in the sediments of an Antarctic subglacial lake for the first time

Video: What Lies Beneath: NASA Antarctic Sub Goes Subglacial

NASA / JPL February 28, 2013: When researcher Alberto Behar from NASA’s Jet Propulsion Laboratory in Pasadena, Calif., joined an international Antarctic expedition last month on a trek to investigate a subglacial lake, he brought with him a unique instrument designed and funded by NASA to help the researchers study one of the last unexplored aquatic environments on Earth.

Called the Micro-Submersible Lake Exploration Device, the instrument was a small robotic sub about the size and shape of a baseball bat. Designed to expand the range of extreme environments accessible by humans while minimally disturbing the environment, the sub was equipped with hydrological chemical sensors and a high-resolution imaging system. The instruments and cameras characterize the geology, hydrology and chemical characteristics of the sub’s surroundings. Behar supervised a team of students from Arizona State University, Tempe, in designing, developing, testing and operating the first-of-its-kind sub.

“This is the first instrument ever to explore a subglacial lake outside of a borehole,” Behar said. “It’s able to take us places that are inaccessible by any other instruments in existence.”

The sub was deployed by the U.S. team of the international Whillans Ice Stream Subglacial Access Research Drilling (WISSARD) project. The project’s objective was to access subglacial Lake Whillans, located more than 2,000 feet (610 meters) below sea level, deep within West Antarctica’s Ross Ice Shelf, nearly 700 miles (about 1,125 kilometers) from the U.S. McMurdo Station. The 20-square-mile (50-square-kilometer) lake is totally devoid of sunlight and has a temperature of 31 degrees Fahrenheit (minus 0.5 degrees Celsius). It is part of a vast Antarctic subglacial aquatic system that covers an area about the size of the continental United States.

The WISSARD team included researchers from eight U.S. universities and two collaborating international institutions. They used specialized tools to get clean samples of subglacial lake water and sediments, survey the lake floor with video and characterize the biological, chemical and physical properties of the lake and its surroundings. Their research is designed to gain insights into subglacial biology, climate history and modern ice sheet behavior.

The instrument consists of a “mothership” connected to a deployment device that houses the submarine. The sub is designed to operate at depths of up to three-quarters of a mile (1.2 kilometers) and within a range of 0.6 miles (1 kilometer) from the bottom of the borehole that was drilled through the ice to reach the lake. It transmits real-time high-resolution imagery, salinity, temperature and depth measurements to the surface via fiber-optic cables.

In a race against time and the elements to access the lake before the end of the current Antarctic field season, the WISSARD team spent three days in January drilling a 2,600-foot-deep (800-meters), 20-inch-wide (50-centimeters) borehole into the lake, which they reached on Jan. 28.

Like Alice down the rabbit hole, the sub was then sent down the borehole, where it was initially used to guide drilling operations. When the instrument finally reached the lake, the team used its imagery to survey the lake floor. The data enabled the team to verify that the rest of the project’s instruments could be safely deployed into the lake. The WISSARD team was then able to proceed with its next phase: collecting lake water samples to search for microbial life.

And that search has apparently paid off. Earlier this month, the team reported that the lake water did indeed contain living bacteria, a discovery that might hold important implications for the search for life elsewhere in the universe.

Life found in the sediments of an Antarctic subglacial lake for the first time

Via EurekAlert / September 10, 2013: Evidence of diverse life forms dating back nearly a hundred thousand years has been found in subglacial lake sediments by a group of British scientists.

Key Findings

• DNA of the microbes survived throughout the millennia
• Surprising high biomass and diversity was found
• One DNA sequence was related to the most ancient organisms known on Earth
• Life can exist and potentially thrive in extreme environments

The possibility that extreme life forms might exist in the cold and dark lakes hidden kilometres beneath the Antarctic ice sheet has fascinated scientists for decades.

However, direct sampling of these lakes in the interior of Antarctica continues to present major technological challenges. Recognising this, scientists from the British Antarctic Survey (BAS), and the Universities of Northumbria and Edinburgh have been searching around the retreating margins of the ice sheet for subglacial lakes that are becoming exposed for the first time since they were buried more than 100,000 years ago.

This is because parts of the ice sheet are melting and retreating at unprecedented rates as the temperature rises at the poles.

The group targeted Lake Hodgson on the Antarctic Peninsula which was covered by more than 400 m of ice at the end of the last Ice Age, but is now considered to be an emerging subglacial lake, with a thin covering of just 3-4 metres of ice.

Drilling through the ice they used clean coring techniques to delve into the sediments at the bottom of the lake which is 93 metres deep and approximately 1.5 km long by 1.5 km wide.

The lake was thought to be a harsh environment for any form of life but the layers of mud at the bottom of the lake represent a time capsule storing the DNA of the microbes which have lived there throughout the millennia. The top few centimetres of the core contained current and recent organisms which inhabit the lake but once the core reached 3.2 m deep the microbes found most likely date back nearly 100,000 years.

Lead author David Pearce, who was at BAS and is now at the University of Northumbria, says,

“What was surprising was the high biomass and diversity we found. This is the first time microbes have been identified living in the sediments of a subglacial Antarctic lake and indicates that life can exist and potentially thrive in environments we would consider too extreme.

“The fact these organisms have survived in such a unique environment could mean they have developed in unique ways which could lead to exciting discoveries for us. This is the early stage and we now need to do more work to further investigate these life forms.”

Some of the life discovered was in the form of Fossil DNA showing that many different types of bacteria live there, including a range of extremophiles which are species adapted to the most extreme environments. These use a variety of chemical methods to sustain life both with and without oxygen.

One DNA sequence was related to the most ancient organisms known on Earth and parts of the DNA in twenty three percent has not been previously described. Many of the species are likely to be new to science making clean exploration of the remote lakes isolated under the deeper parts of the ice sheet even more pressing.

Scientists believe organisms living in subglacial lakes could hold clues for how life might survive on other planets.

Late last year a British expedition to drill into Lake Ellsworth was called off after technical difficulties. A US expedition sampled a subglacial environment near the edge of the ice sheet but has yet to report its findings, and a Russian led project has sampled ice near the surface of a subglacial lake and has reported finding signs of life. ###

The paper, Preliminary Analysis of Life within a Former Subglacial Lake Sediment in Antarctica has been published online in the Journal ‘Diversity‘ as part of a special issue on Microbial Ecology and Diversity.

Related

• Panspermia
• Cryobiology