Monday, October 26, 2020

"Plankton Bloom Heralded Earth’s Greatest Extinction"

 This will be plankton week at the blog, with a cast of characters including the Pope and a Vancouver stock promoter.

But first, some history, from Hakai Magazine, September 15, 2015:

Nutrient runoff may have triggered a burst of marine life before death set in.

It’s been called the worst time in the history of life on Earth: during the “Great Dying,” 252 million years ago, at least 80 percent of all life went extinct in a geological blink of an eye. The end-Permian extinction was the worst of the five known mass extinctions, and many of the iconic marine creatures of the time—ammonites, trilobites, crinoids—plunged dramatically in population or went extinct.

But the end-Permian extinction wasn’t all about death. It was also about life—in the form of a giant plankton bloom that may have flourished as the ocean’s chemistry went haywire.

“People associate mass extinctions with a completely barren ocean,” says geochemist Martin Schobben. “I don’t think that is necessarily the case.”

For more than two decades, scientists have been piecing together a picture of what happened at the end of the Permian. During that time, the world’s oceans were starved of oxygen and poisoned with sulfur. Occasionally, they may have let out a giant belch of warming methane, even as enormous volcanic eruptions roared across Siberia.

Wanting to take a closer look at the environmental changes that were taking place around the time of the mass extinction, Schobben and his colleagues went to northwestern Iran. There, the scientists unearthed rocks that had once been sediment on the bottom of the Permian ocean.

Back in the laboratory, they ran geochemical tests on the rocks, hunting for signs of microbes that “breathe” sulfur instead of oxygen, like the bacteria and archaea that fill the modern Black Sea with hydrogen sulfide. And the scientists found evidence that these sulfur-loving microbes thrived during the end-Permian period....


Back tomorrow with some current events.