Great Barrier Reef 2024 survey showing corals struggling to recover from 2023 weather
New data shows the northern Great Barrier Reef is struggling to recover from the extreme floods, cyclones and bleaching events of 2023.
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New data shows the northern Great Barrier Reef is struggling to recover from the extreme floods, cyclones and bleaching events of 2023.
Initial results from this year’s Australian Institute of Marine Science’s routine survey show that coral cover in the Cairns region has declined by 30 per cent and reefs between Cooktown and Lizard Island have experienced their highest level of annual decline in 39 years.
AIMS’ long-term monitoring program leader Dr Mike Emslie said the loss reflects the extremes of last year.
“During February and March 2024, all the reefs we recently surveyed in this north Queensland region were subjected to levels of climate change-driven heat stress that cause bleaching,” Dr Emslie said.
“The heat stress got so high in some areas that mortality is not a surprising outcome.
“Tropical Cyclones Jasper and Kirrily also exposed many to wave heights likely to cause damage to corals, generally greater than 4m.”
Inner and mid-shelf reefs in the Cooktown-Lizard Island sector bore the brunt of the impacts from bleaching, with one inner shelf reef losing almost three-quarters of its pre-summer hard coral cover.
The outer shelf reefs surveyed escaped with little to no coral loss, likely due to the make-up of the coral communities.
Scientists believe the effects of upwellings of cooler oceanic water may also have been a factor.
Australian Marine Conservation Society’s’ campaign manager Dr Lissa Schindler said these preliminary results show a reef that was not bouncing back.
“The survival rate of the coral that AIMS has surveyed so far paints a grim picture for the Great Barrier Reef, and we’re still waiting on results from the southern regions, where heat stress was at an all-time high,” Dr Schindler said.
“Our Great Barrier Reef is enduring more frequent and intense bleaching events, one after another with insufficient time to recover, which can take more than a decade,” she said.
Despite the concerning results the data also found that this year’s decline was not felt equally across the reef.
“We saw mortality from coral bleaching that was variable within reefs. Some areas were more impacted by heat stress in the top few metres compared to corals deeper down the reef slope which were largely unaffected,” Dr Emslie said.
“Mortality was most common in the table acropora corals. This fast-growing coral has been partly responsible for the recent recovery on the Reef but is also susceptible to the kind of disturbance events we’ve seen this summer.
“Other coral types, such as branching Acropora were less affected, while massive corals – like porites – were least affected. This points to the variability and dynamics on coral reefs.”
On Thursday the reef will undergo one of nature’s most impressive feats.
Millions of corals will spawn into the water in an epic synchronisation showcasing the reefs resilience and capacity to renew.
But Richard Leck, head of oceans for World Wide Fund for Nature-Australia said its resilience was being tested.
“The Great Barrier Reef can bounce back but there are limits to its resilience,” he said.
“It can’t get repeatedly hammered like this. We are fast approaching a tipping point. We only need to look overseas to places like the Caribbean to know what happens if we cross that line,” Mr Leck said.
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Originally published as Great Barrier Reef 2024 survey showing corals struggling to recover from 2023 weather
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