Difficult to access, the bottom of the oceans remains today largely unknown while it shelters the largest ecosystem of the planet, within the oceanic crust, under marine sediments. An unexplored environment that an international drilling program is beginning to reveal.
Thecover more than 70% of the surface of the Globe. Yet knowledge of remains limited. The great depths and the high pressures make their exploration difficult. The ocean are mostly composed of can house organisms in large numbers: they would house one third of the total of the .
But this would only be the tip of the iceberg: theseare based on an composed of basaltic rocks coming from the cooling of the that interferes between two divergent . Part of this crust would be habitable by . This zone would have a ten times greater than that of the sediments! Yet, it remains almost unexplored and therefore unknown to science.
The International Ocean Drilling Program (), in which France is actively involved, has decided to tackle this problem. An expedition named ” ” took place during the months of September to November 2011, on the ship . The objective of this mission was to put in place the necessary equipment for the realization of the scientific experiments. The study site is located in the area called ” North Pond” , on the west side of the .
Oceanic crust, the largest ecosystem
Two experimental devices (called Cork for Circulation Obviation Retrofit Kits ) were embedded in the ocean floor, at a depth of 4,400 meters, thanks to drilling done from the ship. They contain many devices measuring pressure, temperature and analyzingand . In life of 10 years, they will be used to study the biological activity of sediments and underlying for at least 5 years. In addition, samples of and sediments were collected during the setting up of the laboratories .
This video presents the Corks set up by the Mid-Atlantic Ridge Microbiology Expedition in the second half of 2011. The results will provide valuable information on the biological communities living in the oceanic crust. © OceanLeadership, Youtube
In concrete terms, future experiences should provide answers to three questions:
- What is the nature of the microbial of the ?
- What is the origin of the biological communities encountered?
- What is their role in the weathering of the oceanic crust?
Many valuable insights into the nature and extent of life of the oceanic crust are expected to be available soon, which will help to better understand the functioning of the world’s largest. Scientists also hope to understand the role of on the of oceans and on oceanic crusts during training. The results are therefore eagerly awaited.