Super greenhouse: Deep water saved stressed corals

The mega-greenhouse effect 200 million years ago caused a prehistoric heat crisis

The oldest reef corals of the Jurassic period from southern France. © C. Radke / MfN
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200 million years ago, a mega greenhouse effect caused by giant volcanoes led to one of the largest mass extinctions in the history of the earth. Especially coral reefs disappeared almost completely. Only a single reef survived this primeval heat crisis. Why, has now studied an international research team - with surprising results.

Countless research results prove the dangers of today's greenhouse effect on coral reefs: Global warming and ocean acidification threaten the reefs worldwide.

Mega-greenhouse effect 200 million years ago

A similar but much more dramatic scenario occurred 200 million years ago at the end of the Triassic period. The giant continent of Pangea began to disintegrate, with gigantic amounts of lava exploding in the fissures between North America and Africa, pumping vast quantities of CO2 into the atmosphere. The result: a mega-greenhouse effect, which led to global warming, ocean acidification and massive species extinctions in the seas.

Coral reefs suffered one of the worst crises in their history, far worse than the meteor impact that extinguished the dinosaurs 65 million years ago. The great and highly diverse reef systems of the Triassic era disappeared abruptly. Only in southern France has a reef survived. Why?

Stressed Corals: Irregular growth marks suggest fluctuating

Reef in southern France examined

To investigate this question, an international team of scientists took a close look at the reef. Conclusion of the researchers around Professor Wolfgang Kießling of the Museum of Natural History Berlin: It grew in deeper water, at that time already relatively high latitude, and near the region where the reefs of the Triassic were already concentrated. Contrary to previous assumptions, it was not distant oceanic islands but deeper rip-off areas that served as refuges for stressed reefs. display

The corals that survived in Europe formed the basis for the later diversification, but only 15 million years later, it gained momentum. The reef crisis at the end of the Triassic period illustrates, according to the scientists, what devastating effects an extreme greenhouse effect can have on ecosystems and where the chances of survival are greatest.

(idw - Museum of Natural History - Leibniz Institute for Evolutionary and Biodiversity Research at the Humboldt University Berlin, 01.10.2009 - DLO)