Coral on the Great Barrier Reef is showing early signs of bleaching, which has experts concerned as the Sunshine State is staring down the barrel of a long, hot summer.
A team of research scientists have documented pale and fully-bleached coral — which occurs when symbiotic algae inside hard coral is expelled — off the coast of Magnetic Island in Far North Queensland on Sunday.
They're concerned, as this could be the first signs of a "widespread" die-off at the World Heritage site.
If it proves true it would be the sixth mass bleaching event on the reef since 1998.
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Augustine Crosbie, PhD candidate at the ARC Centre of Excellence for Coral Reef Studies told 9news.com.au he's worried, as the signs of stress are being seen relatively early in summer.
"Currently there are only early signs of stress, however this is happening much earlier into summer than during past bleaching events," he said.
"It's also too early to make predictions on how bad it will be.
"(But) we still have a predicted long, hot summer ahead."
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Mr Crosbie explained coral can only tolerate a narrow temperature range, adding the ideal water temperature on the Great Barrier Reef should be between 22 - 30C.
The water temperature off Magnetic Island on Sunday was 31C.
"Prolonged temperature this high will lead to further coral bleaching," Mr Crosbie said.
"There have predictions from the Bureau of Meteorology (BoM) and the Great Barrier Reef Marine Park Authority (GBRMPA) that waters would reach temperatures 1 - 2C above average for many parts of the reef during December 2021 and January 2022.
"This could lead to widespread coral bleaching."
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The latest GBRMPA reef health report predicted Queensland water temperatures could reach "as high as 1.5C above average in parts of the central region" — especially around Townsville.
The government-run body said so far it has only received a few isolated reports of low-level coral bleaching.
The Great Barrier Reef has already seen five mass bleaching events; 1998, 2002, 2016, 2017 and 2020, with the 2016 bleaching described as "the largest on record".
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"In 2016, sea surface temperatures on the Great Barrier Reef were the hottest ever recorded (1.03 degrees Celsius above the 1961–1990 average); a marine heatwave that led to the largest recorded mass bleaching on the Great Barrier Reef," the GBRMPA stated on their website.
The government body said climate change is the main driver of bleaching events.
"Climate change, specifically temperature extremes, is the primary driver of coral degradation in the Region and has substantially altered the abundance and species composition of coral communities.
