Ordovician mass extinction second wave - deep sea anoxia

In summary: The paper discusses a theory that oxygen levels in the deep ocean caused the second "wave" of mass extinction. The paper also has a link to the code, data sets, and support files.
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https://www.nature.com/articles/s41561-021-00843-9
Popular science version:
https://scitechdaily.com/uncovering...s-behind-Earth's-first-major-mass-extinction/

Nature paper discusses causes of the second "wave" of mass extinction at the end of the Ordovician (~445mya)
Really cool aspect - the page has a link to the code, data sets, and support files. Yes!
Models using sediment data show, using iodine as an oxygen proxy:
Shallow warmer waters seem to have stayed at then current oxygen levels, but models show that ocean currents apparently changed. This caused deep sea deposits to show anoxic conditions in sediments formed deep in ocean basins. Which would kill off eucaryotic organisms.

The term vertical decoupling refers to lost flow from shallow waters into deeper waters. The Earth's modern global conveyor belt currents have vertical coupling:
https://www.noaa.gov/education/resource-collections/ocean-coasts/ocean-currents (lots of pictures for tl;dr folks).
There are also links for primary and secondary schools - see "Adopt a drifter program"

Thermohaline circulation drives the "global conveyor belt". This moves warmer surface water with oxygen down into lower depths.
The main claim in the paper is that the movement of oxygenated water into the depths turned off.
Conveyor Belt details:
https://oceanservice.noaa.gov/education/tutorial_currents/05conveyor2.html
 
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1. What caused the Ordovician mass extinction second wave?

The second wave of the Ordovician mass extinction was caused by a combination of factors, including a series of intense glaciations, changes in sea level, and a decrease in oxygen levels in the deep sea.

2. How did deep sea anoxia contribute to the extinction event?

Deep sea anoxia, or the lack of oxygen in the deep sea, played a significant role in the Ordovician mass extinction. It is believed that changes in ocean circulation and nutrient availability led to widespread anoxia, which in turn caused the extinction of many deep sea species.

3. When did the second wave of the Ordovician mass extinction occur?

The second wave of the Ordovician mass extinction occurred approximately 450 million years ago, during the Late Ordovician period.

4. Did any species survive the Ordovician mass extinction second wave?

Yes, some species did survive the Ordovician mass extinction second wave. However, it is estimated that around 85% of all marine species went extinct during this event.

5. How long did it take for the ecosystem to recover after the Ordovician mass extinction?

The recovery of the ecosystem after the Ordovician mass extinction was a gradual process that took millions of years. It is believed that it took around 30 million years for biodiversity levels to return to pre-extinction levels.

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