The meteorite that has become extinct only affects algae for a short time

The ancient stellar collision that many researchers believe caused the massive death of dinosaurs has also seriously affected the lives of marine life. But new research shows that microalgae - one of the leading production organisms in the ocean - have rapidly recovered globally in about 100 years.

Most of this research focused on the extinction of the Cretaceous - early Paleogene (KP) event, also known as the end of the Cretaceous - the Third Century (KT), in which includes mapping of the disappearance of bone or hard shell organisms.
'But there are many creatures in the ocean that don't leave hard fossils,' said Julio Sepúlveda from MIT.

Sepúlveda and his colleagues examined molecular fingerprints of microorganisms. They recently extracted some organic remnants from rocks dating to the KP extinction event. The results published in this week's issue of Science show that the oceanic algae community has significantly reduced in numbers but this only happened for a century.

Close-up of Fish Clay's rock. (Photo: J. Sepúlveda.)

'We found that the top producing organism in the ocean recovered extremely quickly after the impact of the collision,' Sepúlveda said.

The ocean ecosystem has fully recovered after about a million years, but the rapid recovery of photosynthetic algae shows that the collision has brought about sudden but early impacts on the Earth environment. .

Invisible life

The outstanding feature of the KP extinction event that took place 65 million years ago is the complete disappearance of bird dinosaurs. Although there is still much controversy surrounding the extent of the devastation this collision caused, the geological evidence shows that a meteorite crashed on the Yucatan Peninsula.

The collisions from the collision stained the sky for several years, stopping all photosynthesis activities across the planet.But algae and plants lacked the light to photosynthesize for a while - this is still a question that has not been solved. Fossil data does not give accurate information on this issue, so some scientists are looking for other biological clues.

Roger Summons, a member of the study's author group, said: 'We explore' invisible life '- microorganisms that do not appear in fossil data but have played a very important role. in ocean carbon metabolism. '

Fish Clay stone in Stevns Klint is a dark brown band running along the middle of the cliff surface. Below is chalk from the White Cretaceous, above is limestone from Paleogene century. (Photo: J. Sepúlveda.)

When marine organisms die, they will fall to the ocean floor, where most of their bodies are decomposed by bacteria and geochemical processes. But some biological debris is not biodegradable, especially in low oxygen areas.

These organic debris over time will accumulate into 'fossil fuels', such as oil and natural gas. In some cases, researchers can extract these molecular residues from ancient rocks and determine their chemical structure.

Summons said, 'The key is to understand the chemical composition of each organism.'
For example, plant algae produce a lot of lipids - especially sterols like cholesterol in the human body. In ocean sediments, sterol algae decomposes and produces sterane stains.

Sepúlveda and Summons and his colleagues used high-resolution mass spectrometry to extract sterane and biomarkers taken from Fish Clay - a layer about 40 cm thick in a beachside Steved cliff. Klint, Denmark.

The team discovered a large amount of sterane in the bottom of Fish Clay class - shortly after the meteorite impact. They saw this as evidence of massive algae death, a bad condition that lasted for about 100 years.

Ocean live

But does this rapid recovery happen to other species across the ocean? Previous studies have shown that life in the ocean floor has not recovered within a few million years.

Landscape of cliffs near the coast at Stevns Klint, Denmark. (Photo: R. Summons).

'Fish Clay rock signs seem to contradict the sign of the ocean,' said Henk Brinkhuis, a researcher from Utrecht University in the Netherlands. 'An explanation for this is that the tracks on the rock reflect the coastal environment, where conditions are relatively different from the deep ocean.'

However, another possibility is that the surface water layer actually recovers quickly, but for some reason less organic matter sinks into deeper water. This explanation is consistent with the hypothesis that in a meteorite collision, sunlight is obscured only for 10 years.

Steven D'Hondt from Rhode Island University said: ' When sunlight comes back, there won't be any reason to interfere with the activity of production organisms - these microorganisms only need a quantity. Very small nutrition and light to survive. '