The return of fragile corals to the Great Barrier Reef



Parts of Australia’s beleaguered Great Barrier Reef now have the highest levels of coral cover in decades, a government report said Thursday, suggesting the aquatic wonder could survive if given the chance.

According to the Australian Institute of Marine Science, coral cover has increased markedly in parts of the vast UNESCO heritage site over the past year, reaching levels not seen in 36 years of monitoring.

Scientists who surveyed 87 sites said the northern and central parts of the reef have recovered from damage faster than some expected, largely thanks to fast-growing acropora, a branching coral that supports thousands of marine species.

“These latest results show that the reef can still recover during periods free from intense waves,” said Paul Hardisty, director general of the Australian Institute of Marine Sciences.

But Hardisty does not announce victory at all, but warns that gains can be easily canceled out by cyclones, new bleaching events or outbreaks of a crown of thorns.

He pointed to a turn in the fate of the southern part of the reef, which a year ago seemed to be on the mend, but now again fell into disrepair.

“This shows how vulnerable the reef is to continued acute and severe disturbances that are occurring more frequently and lasting longer,” he said.

Coral coverage has increased by 36 percent in areas controlled on the northern part of the reef, up from 27 percent in 2021.

But the picture was less encouraging as the scientists moved south, with a smaller increase in cover in the central reef and a marked decrease in coral cover in the south.

The spread of coral-killing crown-of-thorns starfish has also caused damage.

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Only tough lobbying by the Australian government prevented UNESCO from designating the reef as “at risk” – a potentially devastating blow to the country’s multi-billion dollar tourism industry.

Many fear that the accelerated rate of damage could lead to the complete destruction of the reef.

Marine scientist Terry Hughes said it was “good news” that corals are recovering, but warned that species that promote recovery are very vulnerable to ocean warming.

He added that replacing the large, old, slow-growing corals that defined the reef is likely “no longer possible.” Instead, we are seeing a partial assembly of fast-growing overgrown corals before the next disruption.”

Zoe Richards, researcher Coral Conservation and Research Group at Curtin University also warned against being too optimistic.

“This recovery trend is driven by a handful of Acropora species, which often grow in a boom-and-bust pattern,” she said. “This means that the next heat stress event could easily destroy these coral communities again.”

“We are already finding evidence that each mass bleaching event leads to local extinctions of rarer species, so the short-term success of a handful of fast-growing coral species masks the whole story of largely hidden biodiversity loss.”

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