Panel Discussion, continued...
Back to the Archae, the water coming out of some of those black smokers you said gets up to 400° C. So I'm trying to visualize the habitat here. What if these bacteria can't get out. They obviously can't be in that black smoker alive, it's too hot. Are they attached to other things with substrate or are they free in the water column near those smokers?
George Somero: What we'd like to do - this is a thought experiment, maybe MBARI can do this because they've got the bucks and the technicians - is make a miniature submarine. Remember that movie Fantastic Voyage where I think was it Racquel Welch was floating through this bozo's bloodstream? ...in a white wetsuit! And look to see what kind of subterranean chambers are there. One of the most interesting bits of videotape I've seen from the vent site was from the site where they had this tube worm barbecue and a new vent appeared. I think it was called a snow blower where out of the rock it looked like one of these air popcorn poppers. There was an amazing pulsing of white flocked bacterial stuff from an undersea chamber. It was probably akin to a hemostat where you have a continuous generation of bacteria in some wonderfully optimal growth condition occurring with the right mixing of the oxygen and the sulfide occurring beneath the sea floor. To my knowledge, no one has developed technology to use a small ROV to get down underneath that basaltic floor of the ocean and see what's going on.
Because you probably would have the same types of thermal gradients that you see in your black smoker chimneys going from 400° C to 2° C over a distance that's shorter than the length of this table, it's probable that most of the bacterial growth is occurring in some of those chambers down there. What you'll get coming out on the surface is a trivial fraction of the total bacterial growth. People have put sampling devices with titanium filters right into the hottest black smoke or water, and they have never found evidence for bacteria or any kind of life, in this water. There was an artifactual study published in Nature saying that black smoker bacteria could go to 250° C. That, as I said, was an artifact. I think the world record so far is 113° C.
Bruce Robison: There has been speculation that the rocks in ridge regions like this contain bacteria, the Archaebacteria, in fantastic numbers. It has been speculated, and I should point out that this is speculation by a geologist, that the biomass of bacteria in rocks in ridge crest situations may be larger than the biomass on the rest of the planet. Most biologists I know aren't willing to go that far. Again, this is a geologist who was speculating, but it appears that when venting activity takes place and begins to nova somewhere, the snow blower effect that George mentioned is indeed a significant feature and all these bacteria are blown out of the rocks. Whether they are interstitial or living within cracks and crevices isn't really certain. But it seems there is a significant number of bacteria there that can be propagated by release from the rocks.
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