Corals create ‘sunscreen’ to protect from warming seas

SOME CORALS emit a “sunscreen” in the form of a dazzling colourful display to protect them from rising sea temperatures, according to new research.

Scientists at the University of Southampton believe that the corals emit the bright neon colours in a fight for survival.

The team from the university’s coral reef laboratory explained in a report, now published in the journal Current Biology, that many coral animals live in a fragile symbiosis with algae embedded in their cells.

A rise in water temperature of just 1C can result in this important relationship breaking down, causing the algae to be lost and leaving the coral’s limestone skeleton exposed through its transparent tissue. This, in turn, leads to the fatal condition known as coral bleaching.

But the study found that in mild or brief warming incidents, some coral produced a type of sunscreen that takes the form of the colourful display and encourages the algae to return in an “optical feedback loop”.

Dr Cecilia D’Angelo, lecturer of molecular coral biology at Southampton, said: “Bleaching is not always a death sentence for corals, the coral animal can still be alive.”

She said that if the stress event was mild enough, corals could reestablish the symbiosis with their algal partner.

But she added: “Unfortunately, recent episodes of global bleaching caused by unusually warm water have resulted in high coral mortality, leaving the world’s coral reefs struggling for survival.”