We know that the Chicxulub Impactor was responsible for the extinction of land-based dinosaurs when it hit Earth 66 million years ago. However, recent research has shown that the asteroid has also acidified the oceans and destroyed much of the underwater life.
It is the first direct proof that the din-destroying effect is also due to the immediate acidification of the water – enough to cause a mass extinction that should warn us today. Significant amounts of marine life have been eradicated from the Chicxulub asteroid, researchers say; It seems that there has not been a gradual increase in acidity due to volcanic activity, as previously thought.
"Our data argue against a gradual deterioration in environmental conditions 66 million years ago," says geochemist Michael Henehan. from the German GeoForschungsZentrum GFZ. "Before the impact, we could not detect increasing acidification of the oceans."
"The observed acidification of the oceans could easily have been the trigger for the mass extinction in the sea kingdom," says geologist Pincelli Hull from Yale University in Connecticut.
While scientists have for years suggested that the asteroid impact caused a decrease in the pH of the ocean (an increase in acidity) due to the explosion of sulphurous rocks and subsequent acid rain, it was the discovery of a particularly rich collection of fossils that have contributed to the confirmation.
In a cave in the Dutch town of Geulhemmerberg, the team studied samples from a thick fossil seam that left foraminifera ̵
"In this cave a particularly thick clay layer formed. The immediate consequences of the impact are very rare," says Henehan.
"Because so much sediment was deposited at one time, we were able to extract enough fossils for analysis and intercept the finds transition."
The impact on the food chain would have been tremendous and would have hit just about every other creature higher up the chain. Organisms such as foraminifera could no longer survive, the life forms that fed on them would also have been killed, and so on. The role of the ocean as a carbon sink would have been significantly reduced.
This study also answers several long-standing questions as to whether the asteroid impact killed life in the ocean almost completely or whether some species (of smaller plankton, for example) could survive. It's a bit of both, the new study says.
In other words, first a major species loss of up to 50 percent, followed by a transitional recovery period. This could give experts new clues as to how life in the sea began to blossom again – a process that took millions of years to complete.
The study is also of great relevance for us today: There may not be huge asteroids on the radar Increasing carbon dioxide emissions lead to a later increase in the acidity of the oceans.
As the foraminifer fossils show, the burning of coal, oil and gas causes a pH drop of over 66 million years ago, the researchers say, many different factors play a role.
"When the asteroid struck, the atmospheric CO2 was naturally much higher than it is today and the pH much higher," said environmental scientist Phil Williamson of the University of East Anglia in the UK, who was not involved in the study The Guardian . "In addition, large asteroid impacts cause a prolonged darkness."
"Yet, this study again warns that the global changes in ocean chemistry that we are currently driving can be highly undesirable and effectively irreversibly damaging the biology of the oceans."
The study was published in PNAS .