New Hypothesis for Cause of Mass Extinction Events: Toxic Oceans

April 2, 2015 4:15 PM

Toxic, Oxygen-Depleted Oceans May Have Caused a Mass Extinction Event Changes in the ocean may have pushed some species over the edge 200 million years ago. Scientists have discovered that oxygen-depleted toxic oceans had a key role in a mass extinction event during that time.

Naturally, the Daily Mail is jumping from there to Could fossil fuels trigger a mass extinction? Toxic oceans that wiped out species 200 million years ago are now reappearing

However, here is another article that sounds less histrionic and makes the same basic suggestion.

posted by Michele in California (11 comments total)

Why didn't sharks die off then?
posted by Renoroc at 5:30 PM on April 2, 2015 [2 favorites]

Because that's how badass they are - even a mass extinction couldn't kill them.
posted by kokaku at 5:33 PM on April 2, 2015 [3 favorites]

Sharks survived by retreating to the safety of their tornadoes. We, too, must learn to survive inside tornadoes for years at a time if humanity is to outlast the coming changes.
posted by Behemoth at 5:36 PM on April 2, 2015 [27 favorites]

I haven't had a chance to read the actual pub yet, but anoxic oceans + extinction events is not a new finding, which is what the article seems to be suggesting. OAE's (oceanic anoxic events) appear all throughout the geologic record and are already linked to extinctions, particularly at the Cenomanian-Turonian boundary 91.5 m.y.a.

Just glancing through this, (to me) the main news is more the data about the presence of green sulfur bacteria as there's some debate over anoxic events cause and effect wise (ideas about preservation versus plankton production). The bacteria show that the upper ocean was truly anoxic and sulfuric.

Renoroc - the Borelli event - the one at the Turonian boundary - killed off very large species like Ichthyosaurs. So anoxic oceans can kill large vertebrates if, for example, it affects what they eat in the food chain. Sharks may have benefited from their demise.
posted by barchan at 5:39 PM on April 2, 2015 [7 favorites]

Sharks lay their eggs near those deep smoker vents, and have for millions of years. They have a method.
posted by Oyéah at 5:56 PM on April 2, 2015 [2 favorites]

Sharks are viviparous, aren't they? Sort of?
posted by clockzero at 6:57 PM on April 2, 2015 [1 favorite]

"They' had a viewing means down by one of the smokers where the worms come out of the sea floor, all among the worms were shark eggs, safely nested. The scientist called a frend working on a dig up in Oregon of what was an ancient sea floor, and there in fossil form were millions of year old, fossilized shark eggs, among the fossilized worms. They have some well established method of surviving change.
posted by Oyéah at 7:21 PM on April 2, 2015 [2 favorites]

Sharks are viviparous, aren't they? Sort of?

Depends on the shark.
posted by ROU_Xenophobe at 7:50 PM on April 2, 2015 [4 favorites]

https://www.google.com/url?q=http://articles.latimes.com/2006/jul/30/local/la-me-ocean30jul30&sa=U&ei=7QUeVZOsKZLfoAT6y4GICw&ved=0CBAQFjAC&usg=AFQjCNHNBzfm4gl9F13fRFvguSLp7uP9kQ

This is feom a series of articles in the LA Times about changes in the oceans. Agricultiral chemicals are at work also.
posted by Oyéah at 8:18 PM on April 2, 2015

Reminds me of H.M. Hoover's "Children of Morrow" where the backstory has "the death of the Seas", causing the extinction of nearly all animal life- including pretty much all of humanity. I'm beginning to think Hoover was an optimist.
posted by happyroach at 9:49 PM on April 2, 2015

For our sake, hopefully it also killed off the gigantic, super-intelligent Triassic Kraken.
posted by vanar sena at 12:32 AM on April 3, 2015 [3 favorites]