Chance Discovery Offers Hope for Coral Reefs: Bleached Corals Can Heal by Fusing With Healthy Neighbours

Some of science’s most useful discoveries arrive by accident, and a recent one in a Stanford University laboratory may point towards a new way of helping the world’s threatened coral reefs. A few days after marine biologist Stephen Palumbi placed a piece of bleached coral in a tank alongside healthy coral from the same colony, he noticed that the bleached fragment had toppled over and come to rest against its healthy neighbour. More surprisingly, the pale fragment had begun to regain its colour.

As Palumbi and his colleagues reported last week, the two pieces of coral had fused together. Because the fragments were genetically identical — effectively two parts of the same organism — their tissues merged, allowing the microscopic algae that live inside healthy coral to flow across into the bleached fragment and recolonise it.

Why the algae matter

Corals are animals, built from individual polyps, but much of their survival depends on a partnership with photosynthetic algae known as symbionts. The algae give corals their colour and supply them with food. When water becomes too warm or too cold, or when corals are stressed by pollution or prolonged exposure to air, they expel the algae and turn white — the phenomenon known as bleaching. A bleached coral is not immediately dead, but without its symbionts it loses a vital food source, and its immunity and reproduction suffer.

The Stanford observation suggests that physical contact with a healthy, genetically matching neighbour can restart that partnership. It is a small finding with potentially large implications: if damaged corals can be healed by fusing them with healthy stock from the same colony, reef restoration projects might one day use the technique to nurse bleached areas back to life rather than simply replanting and hoping.

Serendipity, hobbyists and hope

The discovery also carries a couple of quieter lessons. Amateur aquarists had apparently suspected for some time that corals could behave this way, a reminder that careful observation outside professional laboratories can feed real science. And at a moment when bleaching events linked to warming oceans dominate reef headlines, the result offers something rarer: a mechanism of recovery. Fusion will not, on its own, save reefs from rising temperatures, but it gives researchers a new process to study — and perhaps, eventually, to put to work.

Source: Financial Times