According to recent findings published in Science, a study has suggested that chemosynthetic microbes are creating their energy in the depths of the ocean, directly from the rocky layers of the sea bed. Whereas most of life on Earth’s surface depends on the sun for its energy, these microbes seem to be subsisting on energy from chemical reactions, void of light from the sun.
Ecologist Mark Lever of Aarhus University in Denmark led the study, which was the first of its kind to determine that there was microscopic life within the rocks of the oceanic floor. In the year 2004, Lever accompanied the crew of JOIDES Resolution, a drilling vessel which penetrated nearly 300 meters of sediment beneath the ocean floor and an additional 300 meters into the basalt layer of the earth’s crust to help conduct the study.
Essentially, the sediment layer that rests atop the crust beneath the sea serves as a “blanket,” keeping the crust at a cozy temperature of 64°C. It also prevents seawater from directly contacting the rock. Rather, seawater flows horizontally through the sediment over a very long period of time, estimated to about 10,000 years old. Samples have shown that the water filtered through this sediment is distinct compared to typical seawater.
After retrieving rock samples which had no chance of being contaminated by surface microbes, Lever and his colleagues searched for chemical traces and DNA that would suggest methane or sulfur metabolism which are the keys to life for anaerobic lifeforms. While the genes found could easily be from fossilized life, and dating by geologists could suggest that the materials were produced thousands or millions of years ago, further analysis has suggested that there are active microbial lifeforms living within the basalt rocks, subsisting off of the chemical reactions there.
This is big news for more than just marine biologists: Understanding the roles and functions of this hidden biosphere will be a crucial piece to the puzzle of life beneath the ocean as well as life on Earth as a whole.