BBC: The UK's largest tropical reef has been devastated in the global bleaching event now under way.
Up to 85% of the corals in the Chagos Marine Reserve of the British Indian Ocean Territory are estimated to have been damaged or killed in the event.
Scientists say the conditions there are worse than in 1998 - the last major bleaching occurrence.
The problem is caused by anomalously warm water, which prompts the coral polyps to eject their symbiotic algae.
This drains them of their colour...