March 16, 2010

Examining marine life 250 million years ago

Benoit Beauchamp

The talk, on March 17 at 4 p.m. in ES 162, will focus on Beauchamp’s work examining Arctic Ocean marine life at the end of the Permian Era some 250 million years ago. This period is famous for its mass extinction event that wiped out 95 percent of all marine species and close to all terrestrial life.

The massive die off was precipitated by the sudden explosion of volcanoes in Siberia, which pushed CO₂ levels to 30 times what they are today. Carbon dioxide was absorbed into the world’s oceans, which became increasingly acidic. Organisms with shells composed of calcium carbonate could not survive in the acidic soup and as they died, silica sponges began to flourish.

“It was the tipping point. The big extinction wiped the slate clean and reset the evolutionary clock,” says Beauchamp. For the next 8 million years, only a few life forms survived in the hostile, super-heated, carbon dioxide-rich atmosphere.

While levels of atmospheric CO₂ are nowhere near as high as they were 250 million years ago, scientists are already measuring changes in marine pH levels.

“The ocean is slightly basic, but the pH level has come down,” he says. This means that organisms with protective shells, such as krill and clams, will have difficulty building and maintaining shells—just as they did during the great Permian die-off.

Beauchamp points out this could have enormous implications for the entire ocean. “You start playing with the base of the food chain and the ramifications are daunting.”