Bottom of the South Pacific: 1,000 Times Less Lively

"The Most Lifeless Place in the Ocean Found"
LiveScience (June 22, 2009)

"Scientists have discovered what may be the least inhabited place in the ocean.

"The seafloor sediments in the middle of the South Pacific have fewer living cells than anywhere else measured, a new study found.

"Oceanographer Steven D'Hondt of the University of Rhode Island and colleagues took a boat out to the middle of the ocean and collected cores, or cylindrical samples of sediment, from the bottom of the sea about 2.5 to 3.7 miles (4 to 6 km) deep.

"They found about 1,000 living cells in each cubic centimeter of sediment — a tally that is roughly 1,000 times less than in other seafloor sediments...."

Before this, seafloor sediment samples had been taken fairly close to shore, where the water moved round, and there was a reasonable supply of nutrients. These samples were taken in a gyre in the South Pacific, where the water is relatively calm and the nutrients thinly spread.

"...The sparse microbes the scientists discovered appeared to be partially subsisting on hydrogen atoms released when radioactive elements at the bottom of the ocean decayed and broke apart water molecules.

"This somewhat rare process produces only small amounts of food. The other half of the microbes' diet comes from organic matter that drifts from the surface down to the depths of the ocean...."

If organisms can live on nothing but radioactive decay and the odd bit of organic debris, the damp sands of Mars might hold life: and we might find little critters in Europa and elsewhere.

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