Science & technology

Coral Clones Heal Bleached Twins in Just Seven Weeks

Can algae transplants rescue bleached reefs or is cutting emissions fast the only solution?

8 hours ago·Updated 1 hour ago

Coral Clones Heal Bleached Twins in Just Seven Weeks

Story

Above: A mostly dead reef at Cheeca Rocks in Islamorada, Florida, on Oct. 5, 2023, Image credit: Alie Skowronski/Miami Herald/Tribune News Service/Getty Images

The Facts

Bleached corals regained full health within about seven weeks after contact with healthy genetically identical clones, according to a Stanford University study published last Wednesday in Science Advances. Researchers described it as the fastest documented recovery.
ScienceDaily
Gizmodo
The study grew out of a chance 2025 observation by coauthor Steve Palumbi, who saw two fragments from one colony — one bleached, one healthy — touching in a tank as color returned. Lead author Danny Collins had been studying how contact spreads coral disease.
Good News Network
The New York Times
Collins assembled 10 pairs of Pocillopora damicornis fragments, each joining a healthy piece with a bleached one from the same colony. Five pairs touched and five sat a few millimeters apart; the touching bleached fragments recovered while the separated ones died.
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Science
Microscopy showed that tissues of the genetically identical corals fused, forming channels that carried symbiotic algae and nutrients into the bleached fragment. About one week of contact, and in some cases five days, was enough for full recovery.
Good News Network
Discover Wildlife
Algae inside the bleached fragments doubled roughly every four days during the second week of contact, up to 10 times faster than rates recorded in wild corals. One fragment reached complete polyp recovery after four weeks, according to the researchers.
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The Microbiologist
The authors said the approach cannot yet be applied at reef scale because every bleached coral would need a healthy, genetically identical partner. Bleaching occurs when high water temperatures lead to the coral ejecting algae which supply the coral with nutrients.
ScienceDaily
Discover Wildlife
The New York Times

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The Spin

Narrative A

Bleached corals that looked doomed have been brought back by passing the algae they lost from healthy neighbors, a sign that nature’s own biology can be put to work. Warming is locked in and emissions pledges keep slipping, so the realistic path is learning to help species survive the heat. Money and talent put into rescue tools will save more reef than another round of targets.

Anthropocene Magazine

Issues in Science and Technology

The Breakthrough Institute

Narrative B

A coral that recovers in a tank will bleach again in the next heat wave on a warming ocean. The method needs a healthy twin for every sick coral, which no reef can supply, and it was shown on a handful of fragments in a lab. Restoration can help individual colonies, but whether reefs survive is decided by how fast emissions fall, and every rescue story makes that easier to ignore.