Algae: A key player in mass extinctions?

CLEMSON, S.C., Oct. 21 (UPI) -- U.S. scientists say although supervolcanoes and meteors are usually blamed for mass extinctions, algae may be behind the world's great species annihilations.

Clemson University research James Castle and Professor John Robers said anywhere there is water, there can be toxic algae 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.

The researchers say they believe 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 said nutrient-rich fallout from a volcano eruption or meteor impact lands in the water and becomes food for algae. The algae explode in population, releasing chemicals that can act as anything from skin irritants to potent neurotoxins, he said. Plants on land then can pick up the compounds in their roots, and pass them on to herbivorous animals.

Castle and Rodgers said if their theory is correct, it answers a lot of questions about how species became extinct in the ancient world. It also raises concerns for how today's algae might damage the ecosystem in a warmer world.

The research was presented this week in Portland, Ore., during the annual meeting of the Geological Society of America.