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| Robert Karl Stonjek... |
 Posted: Mon Oct 19, 2009 7:53 pm |
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Killer algae a key player in mass extinctions
October 19th, 2009 in Space & Earth / Earth Sciences
Algae, not asteroids, were the key to the end of the dinosaurs, say two
Clemson University researchers. Geologist James W. Castle and
ecotoxicologist John H. Rodgers have published findings that toxin producing
algae were a deadly factor in mass extinctions millions of years ago.
Supervolcanoes and cosmic impacts get all the terrible glory for causing
mass extinctions, but a new theory suggests lowly algae may be the killer
behind the world's great species annihilations.
Today, just about anywhere there is water, there can be toxic algae. The
microscopic plants usually exist in small concentrations, but a sudden
warming in the water or an injection of dust or sediment from land can
trigger a bloom that kills thousands of fish, poisons shellfish, or even
humans.
James Castle and John Rodgers of Clemson University think the same thing
happened during the five largest mass extinctions in Earth's history. Each
time a large die off occurred, they found a spike in the number of fossil
algae mats called stromatolites strewn around the planet. Castle will be
presenting the research on Monday, 19 October at the annual meeting of the
Geological Society of American in Portland, Oregon.
"If you go through theories of mass extinctions, there are always some
unanswered questions," Castle said. "For example, an impact - how does that
cause species to go extinct? Is it climate change, dust in the atmosphere?
It's probably not going to kill off all these species on its own."
But as the nutrient-rich fallout from the disaster lands in the water, it
becomes food for algae. They explode in population, releasing chemicals that
can act as anything from skin irritants to potent neurotoxins. Plants on
land can pick up the compounds in their roots, and pass them on to
herbivorous animals.
If the theory is right, it answers a lot of questions about how species died
off in the ancient world. It also raises concerns for how today's algae may
damage the ecosystem in a warmer world.
"Algae growth is favored by warmer temperatures," Castle said. "You get
accelerated metabolism and reproduction of these organisms, and the effect
appears to be enhanced for species of toxin-producing cyanobacteria."
He added that toxic algae in the United States appear to be migrating slowly
northward through the country's ponds and lakes, and along the coast as
temperatures creep upward. Their expanding range portends a host of problems
for fish and wildlife, but also for humans, as algae increasingly invade
reservoirs and other sources of drinking water.
More information: View abstract at
http://gsa.confex.com/gsa/2009AM/finalprogram/abstract_163685.htm
Source: Geological Society of America
http://www.physorg.com/news175179438.html
Posted by
Robert Karl Stonjek |
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| Lorentz... |
| Posted: Wed Oct 21, 2009 6:47 am |
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On Oct 20, 1:53=A0am, "Robert Karl Stonjek" <rston... at (no spam) bigpond.net.au>
wrote:
[quote]Killer algae a key player in mass extinctions
October 19th, 2009 in Space & Earth / Earth Sciences
Algae, not asteroids, were the key to the end of the dinosaurs, say two
Clemson University researchers.
According to these researchers, as stated later in the article,[/quote]
the asteroid was the key to the end of the dinosaurs. The asteroid
impact led to the algal bloom that killed the dinosaurs. What these
two are proposing is an extra killing mechanism.
I think the lead in is misleading. Generally, what is considered a
"key cause" is the first event in a causal chain, regardless of how
many causes follow it.
Consider dinosaurs durring the entire Mesozoic era that precedes
the asteroid impact. Algae were present every day of every year during
the entire Mesozoic era. There were probably algal blooms in different
areas throughout the Mesozoic, too. However, dinosaurs didn't go
extinct until the end of the Mesozoic.
The fact that dinosaurs and algae lived in relative balance over
this time indicates that algae can't be "key" to dinosaur extinction.
They can be part of the dinosaur extinction. However, something has to
kick them up in importance before you can call algal blooms a key.
[quote]Geologist James W. Castle and
ecotoxicologist John H. Rodgers have published findings that toxin produc=
ing
algae were a deadly factor in mass extinctions millions of years ago.
Supervolcanoes and cosmic impacts get all the terrible glory for causing
mass extinctions, but a new theory suggests lowly algae may be the killer
behind the world's great species annihilations.
Again, whoever prepared this article is misleading the reader.
"If you go through theories of mass extinctions, there are always some
unanswered questions," Castle said. "For example, an impact - how does th=
at
cause species to go extinct? Is it climate change, dust in the atmosphere=
?
It's probably not going to kill off all these species on its own."
See, they are not claiming that spontaneous algal blooms wipe[/quote]
out organisms at random times. Each of the five extinctions had to
have a "key" cause. The fact is that algal blooms are correlated with
each. However, it was not proved that the algal blooms was a
contributing cause of the extinction. Maybe when all other organisms
are dead, then the algae run amok.
Never the less, the algae could have killed many of the species
in the "mass extinction." Just maybe the algae are responsible for the
entire extinction. The lowly algae killed the great dinosaurs!
However, something had to trigger this monster algae bloom. It would
be whatever caused the algal bloom that is key. |
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