Parts of Australia’s Great Barrier Reef have highest coral cover in 36 years

Coral reefs can be seen from above on the Great Barrier Reef, located off the coast of Queensland near the town of Rockhampton, Australia November 15, 2018. REUTERS/David Gray

MELBOURNE, Aug 4 (Reuters) – Two-thirds of Australia’s Great Barrier Reef has shown the most amount of coral cover in 36 years, but the reef remains vulnerable to increasingly frequent mass bleaching, a report on Thursday official long-term monitoring program.

The recovery in the central and northern parts of the UNESCO-listed reef contrasts with the southern region, where there has been loss of coral cover due to outbreaks of crown-of-thorns starfish, said the Australian Institute of Marine Science (AIMS). in its annual report.

“This shows how vulnerable the reef is to ongoing acute and severe disturbances that are occurring more often and lasting longer,” AIMS chief executive Paul Hardisty said in a statement.

The report comes as UNESCO considers classifying the Great Barrier Reef as “endangered”, following a visit by UNESCO experts in March. The World Heritage Committee meeting where the fate of the reef was on the agenda was due to be held in Russia in June but was postponed.

In a key measure of reef health, AIMS defines hard coral cover of more than 30% as high, based on its long-term studies of the reef.

In the northern region, average hard coral cover increased to 36% in 2022 from a low of 13% in 2017, while in the central region hard coral cover increased to 33% from a low of 12% in 2019 – the highest levels recorded for both regions since the institute began monitoring the reef in 1985.

However, in the southern region, which generally has higher hard coral cover than the other two regions, coverage fell to 34% in 2022 from 38% a year earlier.

The recovery comes after the fourth mass laundering in seven years and the first at a La Nina event, but Hardisty said while significant, the laundering in 2020 and 2022 was not as damaging as in 2016 and 2017.

“These latest results demonstrate that the reef can still recover in periods without intense disturbances,” Hardisty said.

In contrast, cover growth was driven by Acropora corals, which AIMS says are particularly vulnerable to wave damage, heat stress and crown-of-thorns starfish.

“This means that large increases in hard coral cover can quickly be reversed by disturbances on reefs where Acropora corals predominate,” said AIMS monitoring program manager Mike Emslie.

Reporting by Sonali Paul; Editing by Stephen Coates

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