Asteroid that Killed the Dinosaurs Disrupted Ocean’s Ecological System

66 million years after the asteroid hit, our oceans pH levels give new evidence into the aftermath.

Scientists recently discovered that the ocean’s acidity levels are a direct result of the asteroid that decimated the dinosaur population. A newly-released study now confirms the theory many researchers had for years.

Researchers have already confirmed that a giant asteroid struck present-day Mexico 66 million years ago, which caused massive wildfires, tsunamis that reached all the way to present-day Illinois, and global cooling from the amount of sulfur that covered the sky. But they now know that the acidity levels in the oceans from the asteroid caused an ecological disruption, leading to 75% of life to be wiped out on land.

“For years, people suggested there would have been a decrease in ocean pH because the meteor impact hit sulphur-rich rocks and caused the raining-out of sulphuric acid. But until now no one had any direct evidence to show this happened,” said Yale University's Michael Henehan.

The study was released Monday, showing the results from the exploration of a Geulhemmerberg cave in the Netherlands, the Brazos River in Texas, deep-sea drill cores, and the Owl Creek in Mississippi. The results show that the ocean was not increasing in acidity prior to the asteroid hit, but increased significantly afterward, and would take millions of years to recover.

The Geulhemmerberg cave held fossilized remains of foraminifera, tiny plankton that grow shells and whose fossils record millions of years of data. The fossilized plankton were unable to grow their shells properly around the time of asteroid-impact, suggesting the ocean’s pH levels had dropped significantly, or acidified.

“In this cave, an especially thick layer of clay from the immediate aftermath of the impact accumulated, which is really quite rare,” said Henehan. “Because so much sediment was laid down there at once, it meant we could extract enough fossils to analyse, and we were able to capture the transition.”

Before recent discoveries, researchers thought that a volcanic eruption in present-day India could be to blame for the mass extinction. Although they did find that volcanoes were erupting 400,000 years before the asteroid, and could have killed off some species, they ultimately confirmed the asteroid was the primary cause.