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Those who know me well know that I have a thing for fungi, and notably for marine mycology.
In 1998, I convened an AGU Spring Meeting
session on yeasts and fungi in the marine environment. One of the participants was Dr. Hideto Takami of Jamstec, who
informed us about all sorts of organisms retrieved by Kaiko from the bottom of the Mariana Trench, including molds.
That led to this page. Years later, when I wanted to remove it, I discovered that there were quite a few links to it. So
I decided not to delete it. It may not contain any news for earth scientists, but
enough for physicists and anyone else.
WHERE
The Mariana Trench is located north of New Guinea. About 250 miles (400 km) SW of Guam, which is part of the
beautiful Mariana Islands. The Mariana Islands are the closest
Pacific island chain to Japan (approximately 2,400 km from Tokyo). The island chain is 750 km long and Guam
(U.S. Territory) is the southernmost island. The Guinness Book of Records cites the Northern Marianas as
having the most equitable climate in the world, with an average year-round temperature of 85 degrees
Fahrenheit (high twenties in °C).
The Japanese submersible Kaiko - sampling mud at the bottom of the Mariana Trench.
(Photograph courtesy and copyright Dr. Hideto Takami, JAMSTEC.)
WHAT
The Mariana Trench is the deepest point on the Earth's surface.
That may make people think of it as a pin hole, but the trench is more than 1,500 miles long (about
2400 kilometers) and on average 44 miles wide (nearly 70 kilometers).
The trench contains several deep sections - called deeps or basins - and the deepest of them all is the
so-called Challenger Deep. It is located at about 11°22'N, 142°25'E. Some of the pictures
on these pages show sediment samples being taken from the bottom of the Challenger Deep.
If you scan the literature, you will find various numbers for the depth of the Mariana Trench:
In 1957, the R/V Vitiaz measured a depth of 10.990 m. This was later corrected to 11.034 m.
The bathyscaphe Trieste determined the depth as 10.911 m, in 1960.
A survey carried out in 1984 concluded that the depth was 10.924 m at 11°22.4'N, 142°35.5'E
The R/V Hakuho Maru recorded a depth of 10.550 m in 1992 and that was later corrected to 10.933 m.
Kaiko recorded depths of 10.898 m during dives in 1995 and 1996.
A study decribed in a 2003 paper measured a depth of 10.744 m
at 11°22.927'N, 142°26.258'E, but the authors of this article say that
their calculation was not as accurate as that of the 1984 survey.
How do they do this? Well, it is a
bit like listening for an echo in a large cave, or counting the seconds between a flash of lightning and the following
thunder. You need to know how fast the sound travels to be able to calculate the distance. So what matters here is the
velocity of sound in water. It varies with certain factors and one of them is depth. Pressure compresses the water and
makes it denser.
The depth of the Challenger Deep boils down to:
About 36,000 feet below sea level;
Which is about 6.8 miles down;
And that equals about 11,000 meters;
Or 11 km.
That makes the Mariana Trench quite a few feet deeper
than Mount Everest is high. If you look at other web sites and articles, you will also
find several numbers for how high Mount Everest is. NASA currently gives it as
29,035 ft. or 8850 meters.
HOW
Pressure in the oceans increases with depth (hydrostatic pressure; hydro means water and static is something like standing).
There are fishes and other organisms that live near the bottom of the Mariana Trench. At about 1,100 atmospheres
pressure. How can organisms live at such depths? How do these organisms cope with such high pressures?
The Mariana Trench biology section tells you more about it.
Kaiko
(pdf file, at JApan Marine Science & TEchnology Center)
Jason
(Woods Hole Oceanographic Institution, Massachusetts)
Ocean Planet -
A Smithsonian Institution Traveling Exhibition
Tour under the Pacific Ocean,
based on real data. Submerge near Hawaii, move to Japan, and dive to the ocean's deepest point
between Japan and New Guinea (NASA)
A new world depth record of 35,800 feet was set in 1960,
when the bathyscaph Trieste descended
to the bottom of the Mariana Trench. The bathyscaph was designed by scientist Auguste Piccard.
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