In a Stanford University laboratory, a bleached fragment of the coral Pocillopora damicornis suddenly began to regain its color — all it took was light contact with a genetically identical healthy neighbor. Researchers led by Danny Collins watched as the tissues fused, forming a kind of bridge across which symbiotic algae of the family Symbiodiniaceae flowed into the depleted organism.
The experiment revealed a striking difference: all the bleached fragments that came into contact with healthy ones fully recovered within seven to eight weeks. Those that remained a few millimeters apart died. Just five to seven days of contact were enough to set the process in motion — after that, the coral managed on its own, and the algae's rate of reproduction turned out to be ten times higher than under natural conditions.
Corals are colonies of genetically identical polyps living in symbiosis with microscopic algae. Under heat stress, they expel these partners, losing their color and their source of energy. The new discovery reveals a hidden mechanism of mutual aid within the colony: healthy parts literally "feed" the afflicted ones.
The results, published in Science Advances, offer hope for developing new methods of reef restoration. However, the method works only between clones, which limits its application in the wild, where colonies are often damaged in their entirety. The study underscores how fragile and at the same time how resilient these ecosystems are.
The discovery is a reminder that even in a seemingly hopeless situation, nature preserves resources for recovery — if conditions allow. For reefs, this means that reducing heat stress remains the key condition for their survival.
