Explorers are racing to reach the deepest part of the ocean. (Photo: BBC)
Renewed interest grows in the ocean's deepest waters
Monday, February 27, 2012, 23:50 (GMT + 9)
The ocean’s deepest depths are divided into several zones. Scientists are becoming increasingly interested in the bottom layers and their native marine life.
The Sunlight or Epipelagic zone (200-1,000m) is the warmest (12C-20C) and where most ocean life occurs. Next is the Midnight or Bathypelagic zone (1,000-4,000m), where bioluminescence generated by marine wildlife is the only source of light.
The Lower Midnight or Abyssal zone (4,000-6,000m) is where most of the ocean floor is found, with the average depth being 4,267m.
Finally, there is the region known as the Trenches or Hadal zone, defined as depths of 6,000m or deeper. Although food is scarce and temperatures are just above freezing here, new life exists, Rebecca Morelle of BBC News reports.
Click here to see detailed illustrations.
Only two explorers have ventured down there, 11km (7 mi) deep to the floor of the Pacific Ocean's Mariana Trench, a cavernous and narrow crack in the ocean floor and the lowest in the planet’s waters. The explorers include US oceanographer Don Walsh, the only man alive who has reached the staggering depth of 10,994m (36,069 ft) -- the deepest known point in the oceans known as Challenger Deep.
Now, a new wave of explorers is getting ready to dive to Challenger Deep to discover its scientific potential.
"Trenches are becoming much more focused in the scientific community," said geologist Jim Gardner from the US Centre for Coastal and Ocean Mapping (CCOM).
Researchers believe that the more than 20 trenches like the Mariana around the world, most of which are in the Pacific Ocean, are formed at the border of two tectonic plates, where extremely heavy oceanic crust drops underneath lighter continental plate during a process called subduction. These seismically active regions could be central to some earthquakes, scientists claim.
In addition, Dr Alan Jamieson, from Oceanlab at the University of Aberdeen, has found a remarkable array of life, from amphipods (prawn-like animals measuring up to more than 30cm in length) to bright pink, gelatinous fish. He is now analysing these animals’ physiology to reveal how they can survive in a place where the pressure is 1,000 times heavier than at sea level, the temperature is just above freezing and light is nowhere to be seen.
He is also interested in what happens when these animals die because, as the organic matter from dead marine wildlife falls to the bottom of the sea, it is hemmed in by the precipitous walls of the trench. A recent study affirmed that this process leads to greater carbon accumulations at the bottom of trenches than in other parts of the ocean, in turn suggesting that the deep sea might play a more decisive role in the carbon cycle and the Earth's climate than previously thought.
By Natalia Real