Dead Zones

In Ancient Oceans That Resembled Our Own, Mass Extinction Was Triggered By Oxygen Loss

by Zachary Boehm, Florida State University

Roughly 430 million years ago, during the Earth's Silurian Period, global oceans were experiencing changes that would seem eerily familiar today. Melting polar ice sheets meant sea levels were steadily rising, and ocean oxygen was falling fast around the world.

At around the same time, a global die-off known among scientists as the Ireviken extinction event devastated scores of ancient species. Eighty percent of conodonts, which resembled small eels, were wiped out, along with half of all trilobites, which scuttled along the seafloor like their distant, modern-day relative the horseshoe crab.

Now, for the first time, a Florida State University team of researchers has uncovered conclusive evidence linking the period's sea level rise and ocean oxygen depletion to the widespread decimation of marine species. Their work highlights a dramatic story about the urgent threat posed by reduced oxygen conditions to the rich tapestry of ocean life.

See Full Article at Source: https://phys.org/news/2019-03-ancient-oceans-resembled-oxygen-loss.html

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Gulf of Mexico ‘dead zone’ is the largest ever measured

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June outlook foretold New Jersey-sized area of low oxygen

Scientists have determined this year’s Gulf of Mexico “dead zone,” an area of low oxygen that can kill fish and marine life, is 8,776 square miles, an area about the size of New Jersey. It is the largest measured since dead zone mapping began there in 1985.

Read full article at source: http://www.noaa.gov/media-release/gulf-of-mexico-dead-zone-is-largest-ever-measured