Corals under pressure: Charité researches the resilience of reefs

Brain City Berlin

Anyone who has ever been diving may have seen them: coral reefs are home to around a quarter of all marine life and protect coastlines from storm surges. Yet climate change is threatening their existence: rising water temperatures and the increasing acidification of the oceans are putting reefs under enormous pressure. Researchers at Charité – Universitätsmedizin Berlin are working together with the University of Haifa to better understand how resilient corals are to these changes.

Teeth and corals: A surprising connection

The project is based at the Charité Institute of Dentistry, Oral and Maxillofacial Surgery in Wilmersdorf, which may come as a surprise. The connection becomes clear when you consider that coral skeletons and teeth share the same basic principle: both are mineralised tissues that grow in nature. The institute's expertise in analysing bone structures can be directly applied to the study of coral skeletons.

Since 2020, marine biologists at the University of Haifa have been collecting coral larvae from the Red Sea and raising them in aquariums under controlled conditions. Some grow under today's acidity levels, others under a higher acid content that simulates the state of the oceans projected for the end of the 21st century if greenhouse gas emissions do not fall significantly.

X-rays into the skeleton

To understand how more acidic water alters the structure of coral skeletons, the Berlin researchers are using X-ray technology at the Helmholtz Institute in Adlershof. The method makes it possible to trace chemical elements within the material and create three-dimensional models of mineralisation. In doing so, the researchers made a surprising discovery: acidic water changes not only the outer areas of the growing skeleton, but also its interior.

Corals raised under elevated acidity developed smaller skeletons than those grown under present-day conditions. At the same time, they developed denser skeletal regions. This greater density could mean that the animals are more resilient to acid and heat than previously assumed.

What the findings mean

The results could help explain why corals have survived periods of extreme heat and cold throughout Earth's history. They suggest that corals possess a degree of adaptability that could help them weather the climate crisis. That is not cause for reassurance, however: the coral ecosystem is far too complex to predict with precision today just how severely the climate crisis will affect reefs by the end of the 21st century. The research coming out of Brain City Berlin is making an important contribution to answering that question, piece by piece.

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