On July 20th, 2008, scientists from the Center of Marine Environmental Sciences (MARUM) at Bremen University and their Japanese colleagues published an article on microbial life deep beneath the seafloor.
The researchers show that - expressed in terms of carbon mass - this so-called deep biosphere contains about 90 billion tons of microbial organisms. That corresponds to about one tenth of the amount of carbon stored globally in tropical rainforests. Applying novel methods, the German-Japanese team concluded that about 87 percent of the deep biosphere consists of Archaea. This is in stark contrast to former reports, which suggested that Bacteria dominate the subseafloor ecosystem.
A team led by Prof. Kai-Uwe Hinrichs investigated sediment samples from several hundred meters beneath the seafloor. The sediment cores were retrieved in the Atlantic and the Pacific Oceans as well as in the Black Sea, most of them well below the ocean floor during expeditions of the Integrated Ocean Drilling Program (IODP). The scientists pursued two main objectives: "We wanted to find out which microorganisms can be found in the seafloor, and how many of them are living down there", states biogeochemist Kai-Uwe Hinrichs.
For quite a long time, scientists believed that the extreme conditions such as high pressure, lack of oxygen, low supply of nutrients and energy would make deep sub-seafloor environments inhabitable for any life form. But now they know better: Sea-going expeditions have proven the existence of the deep biosphere. "In general, life at and below the seafloor is dominated by minute monocellular organisms. According to our analyses, Bacteria dominate the upper ten centimeters of the seafloor. Below this level, Archaea appear to take over the major fraction of the biomass pool", says MARUM researcher Julius Lipp, who has just completed his PhD on this subject.
According to Lipp, Archaea make up at least 87 percent of organisms that colonize the deep biosphere. "These subsurface Archaea can be viewed as starvelings. Compared to Bacteria, Archaea appear to be better adapted to the extreme, chronic deficiency of energy that characterizes this habitat - a consequence of the only food being stable, fossil remnants of plants that were pre-digested by generations of other microorganisms"", says Lipp.
Next to Bacteria, Archaea represent one of three domains in the systematics of life. Both groups can be identified by fat-like molecules, so-called lipids that make up their cell membranes. To date, estimations of the deep biosphere biomass range from about 60 to 300 billion tons of carbon. "Our measurements determined by entirely independent means are with 90 billion tons of carbon right in this bracket", says Prof. Hinrichs, head of the Organic Geochemistry Group at MARUM and the Department of Geosciences, Bremen University. The authors of the Nature paper assume that about 200 million cubic kilometers of mud below the ocean floor are inhabited by microorganisms - a volume roughly corresponding to a 600 kilometer-long cube.
Because all current techniques aimed at detecting biomass in the deep biosphere arrive at different conclusions regarding its quantity and composition, Prof. Hinrichs has initiated an international "ring experiment". Currently, his colleagues in German, European, US-American, and Japanese laboratories are investigating standardized sediment samples from the seafloor with different methods. Moreover, they want to find out whether identical methods applied in different labs lead to dissimilar results. The aim is to gain a more reliable picture of life in the deep biosphere. In September, the researchers involved in the experiment will present and discuss their findings at MARUM. "All participants hope that this experiment will shed a bit more light on the dark deep biosphere" Hinrichs states.
Further information/interviews/photos:Yasmin Khalil
Yasmin Khalil | idw
Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery
20.01.2017 | GSI Helmholtzzentrum für Schwerionenforschung GmbH
Seeking structure with metagenome sequences
20.01.2017 | DOE/Joint Genome Institute
An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...
Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
19.01.2017 | Event News
10.01.2017 | Event News
09.01.2017 | Event News
20.01.2017 | Awards Funding
20.01.2017 | Materials Sciences
20.01.2017 | Life Sciences