Some 420 million years ago, 23% of all marine life went extinct. Referred to as Lau/Kozlowskii extinction by scientists, this mass extinction is amongst the ten most dramatic extinctions that the earth has ever faced. Yet for years, scientists didn’t know what lead to it and what implications it might have.
Now, a new study done by researchers from Florida State University seems to have an answer: rapid and extensive depletion of oxygen in oceans. This is not very different from what our modern oceans are going through. Their findings have been published in the science journal Geology.
As modern-day oceans are stripped of their oxygen due to pollution and global warming, the findings of what happened 420 million years ago could be a precursor to what is happening now. Observations of modern oceans suggest the ongoing significant and widespread deoxygenation can cause greater stress on marine organisms that require oxygen. This may even be the initial steps to another marine mass extinction, the Science Daily quoted one of the study’s co-author Jeremy Owens as saying. He is an assistant professor in the department of earth, ocean and atmospheric science at the Florida State University.
For the study, researchers used sophisticated geochemical methods to measure thallium isotopes, sulphur isotopes, and manganese concentrations in Latvia and Sweden. Other mass extinctions have been linked to large-scale, life-threatening events like meteor impacts or volcanic eruptions. This is one of the pioneering studies on Lau/Kozlowskii extinction has been studied, and scientists have now constructed a step-by-step timeline of what happened.
The deoxygenation of the ocean was followed by more toxic conditions with higher sulphide content in the water. They can now relate this to the subsequent changes in global carbon cycle of modern times. The scientists part of the study concludes that events from even 420 million years ago have important lessons to be learnt in today’s context.
