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Algae First To Recover After Asteroid Strike
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."
There is lots of skepticism that the asteroid strike "killed off [the] dinosaurs." I saw a study where a microbiologist claims that many factors contributed to the death of the dinosaurs, but mostly it was disease, a competing lifeform that grew rampant well after the strike. I don't remember his name because it was a TV show, but I'm sure you can track it down.
In the meantime, this is all I have to offer from the Google:
http://blogs.discovermagazine.com/80beats/2009/04/29/new-study-casts-doubt-on-the-asteroid-strike-theory-of-dino-extinction/
At this point, because of the data we have available in the sediment record, the idea of the dinosaurs being destroyed by the asteroid strike is almost mythology. Keller's work has gone a long way to confirming that we still don't really understand exactly what happened.
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Toro
I wish journalists would be more diligent about actually citing the relevant paper from which the news releases are derived. If it is on the web, is it *that* hard for people to stick a link in there?
Anyhow, I haven't read the paper because I can't get the full article yet, but if some of the recovery they are interpreting after the Cretaceous is related to dinoflagellates (which can be detected as dinosteranes in organic geochemistry work), it wouldn't be surprising that they bounced back fairly quickly: A) many of them form highly resistant cysts as part of their life cycle, and those cysts can survive for years before "hatching" and going back to business as usual, B) many dinoflagellates are heterotrophic or mixotrophic -- i.e. they eat things or they eat things at the same time as using photosynthesis. As a result they could probably survive better than many other planktonic "algae" that are exclusively autotrophs (i.e. photosynthetic). This expectation is confirmed to some extent by the observation of relatively few dinoflagellate extinctions across the K/T boundary compared to many other planktonic organisms.
Hi, I'm a paleontologist. So, you actually are asking a very important question, but its a question that every scientist must answer practically every day. Why should we get paid to study what we life? Well, simply, we don't. There are plenty of great scientists out there who don't get grants or jobs because what they do isn't relevant to enough people. Maybe its relevant to 20 other people out there, but not enough of the general public. The mark of a bad scientist is a scientist who can't figure out a workable scientific project and sell public institutions (like NSF) on it. Good scientists, overall, only exist as long as they can find useful things to study.
But what makes paleontology relevant to our daily lives? The study of mass extinctions is really important: we can't do the experiment of killing 50% of the earth's biota or clouding the skies for ten years to see how life responds. But, as humans, we are radically altering ecosystems with negative effects which may not play out for thousands of years. We need to understand, having already killed off a massive number of species, how life on earth will respond. Furthermore, understanding the oceans, particularly unpreserved organisms like soft-bodied algae, is important to understanding the processes which control the atmospheric content and the supply of nutrients to larger sea creatures. For example, we know species richness recovery from the KT was delayed in some places for periods much longer than a century. Some thought that was due to a prolonged lack of food. Now we know that the algal production started up so quickly, we know that can't be due to a lack of food; maybe its something else (like a wrecked ecosystem structure).
If you need to know any reasons why understanding the past is important, look up the papers of Jeremy Jackson or David Jablonski. They'll set you straight.