Billions of tons of carbon are buried underneath the Earth's surface. Studying deep life can tell us about the origins of life on our planet and perhaps even the potential for life elsewhere.
A species of bacteria that survives on hydrogenImage: Greg Wanger/Gordon Southam
Advertisement
We have long known that there is life under our feet, but now scientists have actually measured it.
Visible only through a microscope, unicellular microbes that live underneath the Earth's surface account for between 15 and 23 billion tons of carbon — that's hundreds of times more than the amount of carbon in all the humans on Earth combined. This new knowledge is the result of a 10-year international collaboration initiative of the Deep Carbon Observatory.
DW talked to Antje Boetius, a marine biologist from the University of Bremen in northern Germany and the director of Alfred Wegener Institute, who was one of the German scientists involved in the project.
Deutsche Welle: The Deep Carbon Observatory united geologists, chemists, physicists and biologists from all over the world. What was the role of German scientists there?
Antje Boetius: Our main task was to reveal the role of the deep biosphere — the life that lives hundreds of meters below the surface of the Earth and the ocean floor. There is a strong interest in research in this field around Bremen and Bremerhaven [in northern Germany], where I work. Our molecular geochemists and microbiologists made significant progress together with the international team to reveal how life deeply buried under the surface of the ocean interacts with carbon and energy sources found underground.
Prof. Dr. Antje BoetiusImage: Alfred-Wegener-Institut/Kerstin Rolfes
What methods did you use to obtain and analyze data for the project?
Our main contributions to the Deep Carbon Observatory were our expeditions to extreme environments [drilling deep underneath ocean floors], as well as our development of new molecular methods we combined these to unravel the diversity of unicellular life, mainly bacteria and archaea[both forms of microbes]. Even if they cannot be cultivated in the lab, they can still be classified by their chemical signatures, sorted into ecological types, and potentially used to identify new branches of life.
In this project you focus mainly on carbon. Why is measuring carbon so important?
Our life on Earth is comprised of carbon. It is the backbone of the molecular building blocks of life. Carbon fluxes, both in the past and today, are crucial because they directly impact energy flow, the climate and life on Earth. Carbon is a very abundant molecule on Earth.
There are huge carbon deposits on land and in the sea that have a huge impact on the climate and all life on Earth, including us. Today, when we are concerned about our overuse of fossil fuels and rapid climate change, it's important to understand that for 4.6 billion years of life on Earth it is exactly this balance between buried carbon and oxidized carbon [CO2] that has explained the diversification and distribution of life, as well as mass extinctions.
These archaea were originally found living in sulfidic springs in GermanyImage: Medical University of Graz, Austria
What is special about deep carbon in particular?
Deeply buried carbon is the largest source of carbon on Earth. Any processes that interact with it, mobilize it, or make it available to microbes change the balance of carbon and, subsequently, our climate. What is particularly special is that solving one of the greatest mysteries about deep life — where it sources its energy from — may allow us to solve another great mystery: the emergence of life on Earth and the possibility of life in outer space.
What is the life source for organisms deep under the Earth's surface?
This was one of biggest questions for us during these past 10 years. Now we are much better informed. We have found many pathways for energy flow, and we can confirm that there are full food web cycles deep underground. For example, there are microbes that use methane as an energy source without oxygen; they can burn the methane with their enzymes and take energy from the methane molecule.
In answering the question of just how deep underground the building blocks of life are formed, hopefully we can eventually understand what formed life on Earth.
Will it also tell us where we can find life outside Earth?
We had some meetings and conferences where astrobiologists were really fascinated by our findings. Progress with this question has also influenced the way new missions are planned. For example, the Mars mission now tries to drill into the planet's surface to find out what is happening with the carbon underneath the surface.
Did any new questions arise from the research?
What we are still trying to establish is the limit of life. We couldn't find the limit with regard to pressure: we can go to the deepest trenches on Earth and even drill many kilometers down into the seafloor and there will still be life. So we found that pressure does not play a big role.
But temperature does. Currently, the record for the hottest temperature that can be survived on Earth is held by a strain of bacteria that can survive at a temperature of 122 degrees Celsius (251 degrees Fahrenheit). But we are still not sure that's the limit.
We still want to know: at what temperature does life cease to be possible? For me, it is really intriguing that we inhabit this planet and we don't know the limits of life and its distribution on Earth.
Top 10 newly discovered species for 2018
From a majestic tree to a rare great ape and a tiny ocean dweller, the College of Environmental Science and Forestry just released its top 10 animals, plants and microbes recently discovered around the globe.
Image: picture-alliance/Sunbin Huang/Mingyi Tian/ESF International Institute for Species Exploration/dpa
Isolated population of rare great apes found in Indonesia
Orangutans are the only great apes in Asia. In 2001, the orangutans of Sumatra and Borneo were recognized as two distinct species. Now, researchers have found a third: the Tapanuli orangutan, which lives in the southern range of Sumatran orangutans, in Batang Toru. They are, in fact, the most imperiled great apes in the world. Only an estimated 800 individuals exist in a fragmented habitat.
Majestic tree found in the Atlantic forest in Brazil
Towering up to 40 meters (130 feet) high and weighing an estimated 56,000 kilos (62 tons), this majestic tree, named Dinizia jueirana-facao, was found in the Atlantic forest in northern Espirito Santo, Brazil. Large in dimensions, the tree is limited in numbers – only 25 of the trees exist, making it a critically endangered species.
Image: picture-alliance/ESF International Institute for Species Exploration/Gwilym P. Lewis
Beetle that looks like part of an ant found in Costa Rica
This tiny beetle is called Nymphister kronaueri and lives among ants in Costa Rica. The beetle is only 1.5 millimeters long (0.05 inches) and its body is the precise size, shape and color of the abdomen of a worker ant. When the nomadic ants move to a new location, the beetle travels along, using its mouthparts to grab onto the abdomen of its host, letting the ant do all the walking.
Image: picture-alliance/ESF International Institute for Species Exploration/D. Kronauer
Deepest fish in the sea found in the Western Pacific Ocean
The dark abyss of the Mariana Trench in the western Pacific contains the deepest spot in the world's oceans. And that's where the pseudoliparis swirei was found, a small, tadpole-like fish that belongs to the snailfish family and measures 12 centimeters (4 inches) in length. It's the deepest-dwelling fish ever recorded, captured at depths of between 6,800 and 7,900 meters (22,000 and 26,000 feet).
Image: ESF International Institute for Species Exploration/Mackenzie Gerringer
Plant that partners with a fungus found in Japan
Most plants capture solar energy to feed themselves via photosynthesis. A few, like the newly discovered S. sugimotoi, get their sustenance from other organisms. In this case, the plant is symbiotic with a fungus, which it derives nutrition from without harming it. Its delicate pink blossoms only appear during a short flowering peroid, on Japan's Ishigaki Island.
Image: picture-alliance/ESF International Institute for Species Exploration/Takaomi Sugimoto
Bright amphipod found in the chilly waters of the Antarctic Ocean
This invertebrate, about 5 centimeters (2 inches) in length, was spotted in the glacial waters of the Southern Ocean encircling Antarctica. It's an amphipod called Epimeria quasimodo, in reference to its somewhat humped back. It has incredible spines and vivid colors and its crested adornments are reminiscent of mythological dragons.
Image: picture-alliance/ESF International Institute for Species Exploration/Cédric d’Udekem d’Acoz
Bacterium that looks like hair found on the Canary Islands
When a submarine volcano erupted off the coast of El Hierro in the Canary Islands, it wiped out much of the existing marine ecosystem. But scientists have found the first colonizers of this deposited area: Thiolava veneris, a new species of proteobacteria producing long, hair-like structures composed of bacterial cells within a sheath and forming a massive white mat.
Image: picture-alliance/ESF International Institute for Species Exploration/Miquel Canals
Fossil of a marsupial lion found in Australia
Scientists recovered fossils in Queensland, Australia to a previously unknown lion-like marsupial that roamed Australia's open forest in the late Oligocene age, which ended about 23 million years ago. It was about the size of a Siberian husky dog and spent part of its time in trees. Its teeth suggest it was not completely reliant on meat but was, rather, an omnivore.
Image: picture-alliance/ESF International Institute for Species Exploration/Peter Schouten
Unicellular organism found in an aquarium in California
This single-celled protist was discovered on a brain coral in an aquarium in San Diego, California, USA. The geographic origin of the species in the wild is not known. It's called ancoracysta twistan and is a predatory flagellate that uses its whip-like flagella to propel itself, and unusual harpoon-like organelles to immobilize other protists on which it feeds.
Image: ESF International Institute for Species Exploration/ Denis V. Tiknonenkov
Cave-dwelling beetle found in China
A new species of troglobitic beetle adapted to life in the permanent darkness of caves was discovered in a cave in Du'an, Guangxi Province, China. Called Xuedytes bellus, the beetle only grows to about 9 millimeters (half an inch) in length and is striking in the dramatic elongation of its head and the body segment immediately behind the head.
Image: picture-alliance/Sunbin Huang/Mingyi Tian/ESF International Institute for Species Exploration/dpa
