Just as the world’s zoos breed critically endangered animals in captivity to repopulate the wild, scientists are building a global effort to freeze corals for reef restoration.

For decades, conservationists have tried to repopulate dead reefs with corals reared elsewhere.

Artificial reef stars have been added to damaged coral reefs in Sulawesi, Indonesia. A new study shows that within just four years, restored reefs are thriving as much as healthy reefs.

Deeper ocean habitats (30-150 metres) are a key feeding ground for critically endangered hawksbill turtles.

"This discovery offers the opportunity of assessing reef biodiversity, at global scale, from orbit."

"This is the first time that a non-algae microbe has been shown to influence the ability of corals to survive a heat-stress event."

Artificial reefs are structures that humans put in place underwater that create habitat for sea life. A new study shows for the first time how much of the US ocean floor they cover.