Scientists from Aarhus university in Denmark have discovered enormous energy reserves hidden within the ocean’s crust. The study published in the journal Science reveals that there is life in the deepest parts of the ocean, driven and sustained by the energy of chemical reactions.
Dr. Mark Lever, a scientist at the Center for Geomicrobiology at Aarhus, shows evidence that sunlight is as important for photosynthetic organisms as chemical energy is for organisms inhibiting the deep sea.
He points out that most of the oceanic crust is covered by layers of mud and it is far from the continental plates, hence why this study is the first to find evidence that there is life at such depth.
Most ecosystems are based on hydrogen, however the team of scientists was able to identify other forms of life too. Lever explains that the hydrogen-based microorganisms produce organic matter, which creates a perfect environment for other organisms in the basalt. The main supply of energy comes from methane production, reducing sulfate or breaking down of organic carbon.
Lever was able to analyse samples from the oceanic crust, looking for sulphur reducing and methane producing microorganisms. Interestingly, these organisms he found are not typical for seawater.
Because of the basaltic veins, the water at such depth is chemically different from usual seawater, and therefore the microorganisms found there are much different too.
Various DNA analysis of rock samples collected during their fieldwork indicate that the microorganisms are methane-producing. The scientists provided proofs that the carbon isotopes have not been introduced by dead plankton, but they have been formed within the oceanic crust. In addition, the team established that microbial cycling of sulfur has taken place in some of the samples.
To avoid sampling of microbial contaminants, the team developed special sampling methods. These were developed together with geologists, microbiologists and geochemists from different international institutes.
A main conclusion of the study is that basalt and ocean chemistry are determined and influenced by various microbes. Energy forces, which control life at such depth are much different from what we are used to observe.
Dr. Lever suggests that chemical energy forces might also sustain life on other planets, where carbon dioxide, light and oxygen are not readily available. He is also determined to establish the role of oceanic crust in the global carbon cycle.