We’ve written before about mass extinction theories that pop up from time to time. See: Cause of Mass Extinctions Discovered? suggesting that solar system “bounces” are to blame; and then there was Constipated Dinosaurs, Abortion, and Darwin, which is too convoluted for a brief summary.
Now we have another theory. At the website of the Geological Society of America, we read Killer algae a key player in mass extinctions. Here are some excerpts, with bold added by us:
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.
We wouldn’t want that paragraph to escape your notice. A “sudden warming in the water” might kill us all. Let’s read on:
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.
Stromatolites are very interesting structures. We continue:
“If you go through theories of mass extinctions, there are always some unanswered questions,” Castle says. “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.
This is plausible — the problem starts at the bottom of the food chain. Here’s a link to the abstract of the paper by Castle and Rodgers.
One more excerpt:
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.
The connection with global warming is conveniently stylish, but it also makes sense. We’ll think about it.
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