Asteroid Impacts Could Help out Underground Life
Baku, April 19 (AZERTAC). An incoming asteroid is trouble whether you`re a dinosaur or a Bruce Willis fan. But microbes living deep underground may actually welcome the news, according to a recent study of an ancient impact in the United States` Chesapeake Bay. A biological census of the subsurface life forms suggests that impacts create new niches for these deep dwellers to spread into.
In the last couple of decades, biologists have come to realize that the biosphere doesn`t stop at the surface. A large fraction of the Earth`s biomass is lurking down below. Several drilling projects have brought up evidence of hearty little microbes thriving in deep rock sediments. Some eat organic scraps that seep down from our world, while others derive energy through chemical reactions with iron and sulfur.
Although it`s hardly paradise, this netherworld has one thing going for it: it`s fairly peaceful. There`s no night or day, no winter or summer. No global warming or ice ages to worry about. Only the occasional earthquake or asteroid impact is really going to shake things up.
We typically think that crust-shattering asteroids or comets have only detrimental effects on life, but the opposite may be true for subterranean microbes. An impact will sterilize some of the rock with heat, but it will also make other areas more habitable.
"Impacts can fracture the rocks in the deep surface, which will allow fluids and nutrients to flow in," said Charles Cockell from the University of Edinburgh in Scotland.
Cockell and his colleagues decided to look at the subsurface life beneath one of the largest impact craters on Earth, the 53-mile-wide (85 kilometer) crater in the Chesapeake Bay along the U.S. East Coast. Their results, reported in a recent paper in the journal Astrobiology, suggest that the underground biosphere is still adapting to the 35-million-year-old impact. But it does appear that some microbes took advantage of the cataclysm to settle down deeper in the underworld.
The researchers showed that this variation, or patchiness in the microbial distribution, was not because of some lack of nutrients. In fact, they found an abundance of sulfate and organic carbon throughout the drill core. The implication seems to be that 35 million years hasn`t been enough time for the microbes to fill in the churned up rock from the impact.
The conclusion seems to be that the impact actually benefitted the microbes by enlarging the area where they could roam. The resulting fissures and cracks let in water and other nutrients into this deep rock, which made these areas more hospitable for deep-Earth dwellers.
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