Lack of nutrients stalled rebound of marine life post-Permian extinction | Science News

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Lack of nutrients stalled rebound of marine life post-Permian extinction

Hot seas altered nitrogen cycle, delaying recovery by millions of years

By
7:00am, August 22, 2016
 Ellesmere Island

LONG DELAY  A lack of nutrients may have delayed the recovery of marine ecosystems following the Permian extinction. On northern Ellesmere Island in the Canadian Arctic, light-colored ocean sediments deposited after the extinction (bottom foreground) contain few nutrients; darker sediments that formed later (middle background along slope) are nutrient rich.

Out-of-reach nutrients could help explain why life on Earth took so long to bounce back from the worst extinction of all time.

Analyzing the chemical changes that followed the Permian extinction 252 million years ago, geologists propose that hot sea surface temperatures led to conditions that trapped nitrogen far below the ocean’s sunlit, life-filled layers. The resulting deficiency of the key nutrient helps explain why marine ecosystems took 5 million to 9 million years to recover, millions of years longer than for other mass extinctions, the researchers propose online August 5 in Geology.

“It’s equivalent to a farm,” says study coauthor Stephen Grasby, a geochemist at the Geological Survey of Canada in Calgary. “If you’re not throwing fertilizer on the field, the soil becomes nutrient limited and you get less and less plant growth.”

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