AS MUCH as half the Great Barrier Reef may have died in the back-to-back bleachings over the past two years.
Bleaching on a coral reef in Great Barrier Reef. Picture: ARC Centre of Excellence for Coral Reef Studies/AFP
But the head of the authority in charge of the reef says the actual extent of damage is tricky to calculate because some parts are growing well.
The Great Barrier Reef Marine Park Authority believes about 30 per cent of coral, in the reef’s northern part, died last year in bleaching caused by warmer ocean waters, chairman Russell Reichelt told a Senate committee on Monday.
Surveys after this year’s bleaching are still being done but initial observations suggest 20 per cent of coral — mainly in the central area of the 344,000 sq km reef — is dead.
“Don’t think of these figures as the net amount of coral on the Barrier Reef because there are quite big movements upwards as well as downward,”
Dr Reichelt told the senators at an estimates hearing in Canberra.
The southern part of the reef had grown by about 40 per cent in recent years because it hadn’t been hit by cyclones or bleaching — but it was likely it would suffer from those in the future.
A diver examines bleaching on a coral reef on Orpheus Island. Picture: Greg Torda/AFPSource:AFP
Dr Reichelt said the bigger picture question was the coral’s resilience in the face of bleachings, tropical storms and other threats such as the crown of thorns invasions.
“It depends on the frequency of these major impacts and the concern is the frequency could well be increasing and the recovery time will be insufficient,”
he said.
“If the recovery time is very short, there won’t be a lot of coral.”
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