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# Reefs are getting softer
- URL: https://sn.olafwrieden.com/klimakrise-veraendert-korallenpopulation/
- Published: 2021-01-14T12:46:01.000Z
- Updated: 2026-09-10T20:15:46.000Z
- Description: Research into the past suggests climate change could favour softer corals and sea anemones over reef-building corals. Save Nemo calls for every square centimetre of reef to be protected.
- Author: Olaf Wrieden
- Tags: News, #archive-import

The climate crisis is changing coral populations. Save Nemo: fighting for every square centimetre.

## Surviving a changing climate

Once again, a changing climate threatens the survival of corals. As this January 2021 report described it, the polyps had experienced major climatic and chemical changes repeatedly over some 750 million years of existence. Marine biologist Andrea Quattrini of the National Museum of Natural History in Washington and her team were examining how past environmental changes affected corals and sea anemones, both of which belong to the anthozoans.

The findings, presented in the journal *Nature Ecology & Evolution*, offered clues to what could happen to anthozoans as the climate continued to change. The report’s good news was that these cnidarians would not disappear altogether. The bad news was that individual species would. “Earlier changes in the climate had natural causes—and nature was given time to recover,” said Save Nemo board member Diemo Niemann. He added: “But what is happening today is the result of human wrongdoing—and this time nature is not being given time to recover. We as humanity must rethink our approach—immediately! That is why we fight for every square centimetre of reef.”

The marine biologists studied hundreds of kinds of anthozoans from around the world, analysing their genetic material. Comparing this with fossil evidence revealed how anthozoans had evolved over millions of years. The original report described stony corals as having 1,300 different genera. Their skeletons consist mainly of aragonite, a form of calcium carbonate that the cnidarians produce from minerals they extract from the water. The report described the softer skeletons of black corals and gorgonians as consisting of proteins and calcite. Sea anemones have no skeleton at all.

Climate change is primarily a threat to stony corals. They are threatened both by rising water temperatures and by increasingly acidic oceans: aragonite dissolves as oceans acidify. As the report explained, the consequence is that stony coral skeletons dissolve or, at best, stop growing.

This is not a new phenomenon: the Earth experienced such periods in the past. At those times, there were even more species of anthozoans—but primarily sea anemones and corals with skeletons made of proteins and calcite, which are more stable than aragonite in acidic water. These were not the corals that build reefs.

Given the climate crisis, the report anticipated a similar shift among anthozoans. “Soft” anthozoans were already being seen colonising the skeletons of dead stony corals. In the Caribbean, for example, dense forests of gorgonians were growing in places previously occupied by stony corals. The expected outcome was that anthozoans would adapt to the changed environmental conditions and survive, while many stony corals would probably become extinct.

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*Originally published in German on 15 January 2021\.* [*Read the archived original*](https://web.archive.org/web/20251017105822/https://save-nemo.org/klimakrise-veraendert-korallenpopulation/)*.*