As the famous Princess Bride quote goes: “There’s a big difference between mostly dead and all dead.”
Now, some corals thought to have been killed by heat stress are showing signs of life, surprising scientists.
According to Phys.org, the discovery was made by Diego K. Kersting from the Freie University of Berlin and the University of Barcelona while diving in the Spanish Mediterranean.
Corals are not plants, like many people think, but animals that form the ocean’s vital coral reefs – which are colonies made up of individual “polyps” – when they excrete calcium carbonate to form their exoskeletons.
Kersting and his co-author Cristina Linares have been studying the reef-building coral Cladocora caespitosa for several years and have written papers documenting “recurring warming-related mass mortalities” among the corals, according to Phys.org. But now, in a hopeful sign, they’ve spotted life:
“At some point, we saw living polyps in these colonies, which we thought were completely dead,” said Kersting.
Corals have been decimated by temperature increases in recent years, according to Phys.org:
“Heat waves kill these animals—by either essentially roasting them alive or causing them to eject the symbiotic algae that live within them and provide them nutrients, thus leading to coral bleaching.”
Now, according to the new discovery, scientists have found that a percentage of corals have managed to survive heatwaves in their environments by, essentially, making tactical retreats and then regrowing their structures when conditions improved.
“But the researchers found that in 38 percent of the impacted colonies, the polyps had devised a survival strategy: shrinking their dimensions, partly abandoning their original skeleton, and gradually, over a period of several years, growing back and starting a new skeleton,” according to Phys.org. “They were then able to gradually re-colonize dead areas through budding.”
However, Kersting said that while the discovery raises the possibility that corals in other regions may be employing a similar survival strategy, and provides a sliver of hope, the endangered corals cannot face the growing impact of climate change alone because temperatures are simply rising too quickly.
“They actually need help from us. We need to stop climate change, because it’s not going to be enough,” he warns.