Biology Earth

Mariana Trench: Deepest ocean ‘teems with microbes’ + Life on Enceladus?

An international team of scientists published a finding in the journal Nature Geoscience that the very bottom of the Mariana Trench, which lies almost 11km (7 miles) down in the Pacific Ocean, has high levels of microbial activity.

In the western Pacific Ocean about 200 kilometres (124 mi) east of the Mariana Islands; it is the deepest trench in the world. It is a crescent-shaped trough in the Earth’s crust averaging about 2,550 km (1,580 mi) long and 69 km (43 mi) wide. … At the bottom of the trench the water column above exerts a pressure of 1,086 bars (15,750 psi), more than 1,000 times the standard atmospheric pressure at sea level. The temperature at the bottom is 1 to 4 °C (34 to 39 °F).

via Wikipedia

It doesn’t sound very hospitable to life, does it?

The underwater canyon was once thought to be too hostile an environment for life to exist.

But this study adds to a growing body of evidence that a range of creatures can cope with the near-freezing temperatures, immense pressures and complete darkness.

Dr Robert Turnewitsch, one of the authors of the paper from the Scottish Association for Marine Science, said: “The deepest parts of the deep sea are certainly not dead zones.”

In 2010, the scientists sent an unmanned submersible down into the vast underwater canyon, where it collected samples of the murky sediment that cakes the sea floor.

An analysis of the levels of oxygen in the sample revealed the presence of a large number of microbes.

Dr Turnewitsch explained: “These microbes, they respire as we do. And this oxygen consumption is an indirect measurement of the activity of the community.”

Surprisingly, these primitive, single-celled organisms were twice as active at the bottom of the trench than they were at a nearby 6km-deep (four miles) site.They were feasting on a plentiful supply of dead plants and creatures that had drifted down from the sea surface, the decomposing matter becoming trapped within the steep walls of the trench.

“The amount of food down there and also the relative freshness of the material is surprisingly high – it seems to be surprisingly nutritious,” said Dr Turnewitsch.

The level of material found at the bottom of the trench was so high that it suggests the Mariana Trench – which is in an area of the ocean known as the Hadal zone – could play a key part in the carbon cycle and therefore in regulating the planet’s climate. …

via BBC News – Mariana Trench: Deepest ocean ‘teems with microbes’.

This brings up the exciting possibility of microbial life being found in the solar system. one candidate is a moon of Saturn. From carefully observed data, scientists believe that Enceladus has a global ocean of water about 16 to 19 miles under its floating ice shell. It also has methane in its atmosphere which can be produced by microorganisms.

European collaboration of scientists have shown that certain lifeforms can survive under Enceladus-like conditions. … microbes could explain why there is methane in the atmosphere of Enceladus.


It seems most likely that when we do discover life on another planet, it will be microscopic life, but it is fun to imagine large creatures as well in the dark ocean world of Enceladus.

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Fred Killer
Fred Killer

7 miles deep is hard to even imagine. To put it in perspective, at 6 feet above sea level, the… Read more »

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