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Earth Science

Algae First To Recover After Asteroid Strike 86

pickens writes "The asteroid that impacted earth 65 million years ago killed off dinosaurs, but microalgae bounced back from the global extinction in about 100 years or less. Julio Sepúlveda, a geochemist at MIT, studied the molecular remains of microorganisms by extracting organic residues from rocks dated to the K-T extinction (in this research referred to as Cretaceous-Paleogene), and his results show that the ocean algae community greatly shrunk in size but only for about a century. 'We found that primary production in this part of the ocean recovered extremely rapidly after the impact,' says Julio Sepúlveda. Algae leave certain signatures of organic compounds and isotopes of carbon and nitrogen; bacteria leave different signatures. In the earliest layers after the asteroid impact, the researchers found much evidence for bacteria but little for algae, suggesting that right after the impact, algae production was greatly reduced. But the chemical signs of algae start to increase immediately above this layer. A full recovery of the ocean ecosystem probably took about a million years, but the quick rebound of photosynthesizing algae seems to confirm models that suggest the impact delivered a swift, abrupt blow to the Earth's environment."
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Algae First To Recover After Asteroid Strike

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  • by eldavojohn ( 898314 ) * <> on Monday October 05, 2009 @07:35AM (#29643003) Journal
    You may want to welcome them already. Recent research [] shows now that phytoplankton were/are consumers of poisonous ammonia in our oceans. And they produced out of it what plants crave. 'Lytes! No wait, I mean Nitrogen. I'm not a biologist but this latest research seems to imply that our designation of bacterial nitrifiers as most important to the nitrogen cycle is wrong and should be given to Archaea []. From that research:

    The new experiments show that the organism can survive on a mere whiff of ammonia - 10 nanomolar concentration, equivalent to a teaspoon of ammonia salt in 10 million gallons of water. In the deep ocean there is no light and little carbon, so this trace amount of ammonia is the organism's only source of energy.

    So I wouldn't be surprised that phytoplankton would be the first to recover after an asteroid strike. Not much needed for them to survive. Apparently if all of this is true, a lot of ecology is going to be rewritten. Exciting times if you're in that field I guess.

  • by Anonymous Coward on Monday October 05, 2009 @09:33AM (#29644073)

    Pro Tip:

    Close the lid when you aren't using it. Keeps the sun out, and the algae dead.

  • Re:Asteroid? Really? (Score:1, Informative)

    by Anonymous Coward on Monday October 05, 2009 @10:58AM (#29645375)

    You can believe all you want, but I believe that if I step out in front of a moving bus, it's the physics of the situation that will determine the outcome, not my personal belief about it.

    All ideas in science are effectively theories. Differentiating between "fact" and "theory" is a bit pointless, given that there is an element of interpretation in the most elementary of observations. It's my personal belief that everything about our perceptions of the world is effectively a "theory" in some sense, but that's just my personal take on it. Most people draw a line between the easily verifiable stuff ("facts") versus the more challenging stuff ("theories").

    That being said, the evidence in support of the theory of a massive asteroid impact about 65 million years ago is pretty hard to dispute scientifically. Most current arguments center on whether the impact that produced the ~300km-diameter impact crater on the Yucatan Peninsula of Mexico was the sole cause, or whether other factors were involved in the mass extinction. The jury is still out on that part. The question of whether an impact occurred at all, and the approximate age of it (~65Ma), is all but settled as far as the great majority of scientists are concerned. Like any good scientific theory, it's testable, and it could be shown to be wrong (e.g., even "Newton's Laws" are wrong in detail compared to the "theory of relativity"), but it is pretty hard to argue with a gigantic hole in the ground that matches in so many ways the expectations of a large impact. It is sandwiched in the time between when dinosaurs and many other creatures were present (the Cretaceous Period) and when they were extinct (the Paleogene/Tertiary). Even if you want to quibble about the age (65 million years ago), you have to explain what is there and why it coincides with the extinction.

    The theory that the Earth is about 7 to 10 thousand years old and that the Earth experienced a global flood was scientifically considered in the 1700s -- it's the hypothesis that scientists of this era started with -- and it was thoroughly negated and abandoned by most scientists by about the 1830s. It just didn't work. You can, of course, continue to believe it for as long as you like, and I will respect your right to believe it, but please don't claim that there is any valid scientific reason for believing it, because there isn't. Scientifically it is on par with phlogiston as an explanation for burning.

    Even though the theory of an Earth age of 10000 years or less has been dead in the scientific realm for well over 100 years, it still receives some attention in the realm of philosophy or religious belief. In the scientific realm the only circumstances it isn't negated are scenarios like a created Earth with all the evidence installed to look like it is enormously older, which makes a nice philosophical discussion but isn't scientifically testable at all (i.e. the reason that particular version isn't negated is because it can't be).

    In summary, I see your point, because the impact-triggered K/T mass extinction interpretation is indeed a theory, but it is a very strongly supported one. It is therefore ridiculous to place the negated "10k Earth/global flood theory" on par given the HUGE disparity in scientific evidence that bears on these theories. The only reason someone could do that is if they think what happened yesterday is unknowable or untestable scientifically unless someone was there to witness it -- that we can't really know anything about the past, so they are both equally unknowable theories. That's a popular one among people who still believe "young Earth" theories, however, that rationale doesn't work for crime investigation, so why should it be any different for scientific work? The evidence bears witness and is scientifically testable just fine.

    This isn't a question of imposing belief or telling other people how to think, it is a question of the basis for a belief -- the ingredients that go into what is eventually a personal decis

  • Re:Scalpel, please (Score:3, Informative)

    by Convector ( 897502 ) on Monday October 05, 2009 @12:07PM (#29646517)
    What they're saying is that it takes algae 100 years to recover from this kind of event, no matter how long ago that actually happened. If the impact were to happen right now, it would take 100 years to recover. If it happened 65 Mya, it takes 100 years to recover. We just don't know the start and end times that well, so they can't say the recovery was done by 65.0001 Mya. Another example is the formation of the solar system. The half life of Al-26 is only about 0.7 million years. So we know the majority of the Al-26 was gone by 5 My after the formation of CAIs' (commonly taken as age 0 for the solar system). We just don't know that date very well. It's about 4.6 Gya, but we can't say that the Al-26 was gone by 4.595 Gya. We may know that this impact crater on Mars is 10 My younger than another, but don't know either date well enough to say impact A happened at 4.11 Gya and impact B happened at 4.10 Gya. Could be 4.15 and 4.14, for example, but we know the spacing.

Anyone can hold the helm when the sea is calm. -- Publius Syrus