The deepest part of the ocean still teems with life, according to a new study about the bottom of the Mariana Trench.
The information comes from a study done by an international team of scientists and published in the journal Nature Geoscience. In the study, the scientists found that the very bottom of the Mariana Trench still teems with microbial life.
The trench is the lowest place on Earth at seven miles below the surface of the ocean. It was once thought to be a dead zone with an environment too hostile to support life. But, despite the low oxygen levels and the pressure from seven miles of water, the study shows that creatures may even be able to cope in the trench.
Dr. Robert Turnewitsch, one of the paper’s authors who works with the Scottish Association for Marine Science, stated, “The deepest parts of the deep sea are certainly not dead zones.” The scientists made their discovery after sending a remote-controlled submersible down into the Mariana Trench in 2010.
The sub collected samples of the sediment caked on the ocean’s floor. The scientists performed an analysis of the levels of oxygen in the samples, which revealed the presence of microbes. Life in the deep ocean cannot be sustained by sunlight, which is not strong enough to filter through seven miles of water.
Instead, the organisms and creatures living in the deepest spots on Earth must rely on the organic matter that snows down from above. The particles’ nutrients tend to get degraded by microbes as they make their way down. Because of this, only about one or two percent of the ocean’s organic matter production actually reaches the average ocean depth of 12,150 feet.
The Mariana Trench lies at the bottom of the central west Pacific Ocean. If it were above land, the massive trench would put the Grand Canyon to shame. Instead, it remains a vastly unexplored area of the ocean. Researchers analyzed the samples from 36,000 feet under the surface and found a microbial community thought to be twice as active as that of a nearby 19,700-foot sit just 35 miles south.
Researcher Ronnie Glud, a biogeochemist at the Southern Danish University in Odense, Denmark, commented on the find, explaining, “In the most remote, inhospitable places, you can actually have higher activity than their surroundings.” One explanation for the difference in microbial life and organic compounds could be that the Mariana Trench acts as a natural trap for sediments floating down to the bottom of the ocean.
Since it is essentially just a large hold, it will fill up with things like organic compounds that get “blown in” by the ocean’s current. Glud likened the concept to a hold in a garden, which will fill up with water and leaves that blow into it from higher elevations. Another explanation is that the Mariana Trench is part of a subduction zone where one tectonic plate is slowly moving underneath another. This action creates earthquakes that trigger mudslides and transport new material into the trench.
Following their finds at the deepest known place on Earth, the scientists will analyze other trenches to see if bacterial activity is also relatively high there.
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