Marine scientists surveying coral reefs off WA's northern coast are concerned some may not recover from a recent coral bleaching event.

Researchers from the Australian Institute of Marine Science (AIMS) say Scott Reef, off the Kimberley coast, has been extensively damaged.

Last summer, the north Australian coast experienced one of the worst coral bleaching events in recent history.

Global warming and an El Nino weather system caused unusually high water temperatures, turning the coral white.

This month, scientists returned to the Kimberley reefs to see if they had survived.

Marine scientist James Gilmour said they were shocked at what they saw at Scott Reef.

"This was devastating for all of us," he said.

"We confirmed that in fact most of the corals that we had seen that bleached were in fact dead this time — so much of the reef was dead and now covered in algae, which was a great shock to us."



The reef has bounced back from bleaching events in the past, but this time, the damage may be terminal

"We've seen a couple of smaller bleachings at Scott Reef and now this very severe one again, so over 20 years I've largely watched the reef recover and now I've seen it impact again, and I wonder whether or not I'm going to see it recover in my lifetime," Dr Gilmour said.

However, he said Ashmore Reef had fared better.

"I'm happy to say that when we went to Ashmore Reef there was very little sign of bleaching ... and that's a really good news story for us in Western Australia," he said.

Dr Gilmour said there was a strong correlation between increased temperatures and bleaching.

"We've been studying this for 20 years and we do know that coral bleaching is real and we do know that temperatures are rising, so what we need to is a consensus among everyone that this is a real pressure and we need to set about making all possible attempts to reduce the heating of the world's oceans," he said.