Scientists have stepped in as environmental matchmakers by breeding baby coral on the Great Barrier Reef in a move that could have worldwide significance.

Coral eggs and sperm were collected from Heron Island's reef during last November's coral spawning to produce more than a million larvae.

The larvae were returned to the wild and placed onto reef patches in underwater mesh tents, with 100 surviving and growing successfully.

A diver inspects coral bleaching at the Great Barrier Reef, Heron Island. Credit:XL Catlin Seaview Survey

Lead project researcher and Southern Cross University professor Peter Harrison, who discovered mass coral spawning in the 1980s, says the "results are very promising".