Some parts of the Great Barrier Reef have recorded the highest amount of coral cover in the last 36 years — since the Australian Institute of Marine Sciences began monitoring it.
This is stated in the report of the institute, which was made public on August 4.
A study of 87 reefs found that between August 2021 and May 2022, the average hard coral cover in the upper and central parts of the reef increased by about one-third. This is rare good news for the reef, which suffered its sixth mass bleaching in March.
The instituteʼs director general, Dr Paul Hardisty, said the results in the northern and central regions were a sign that the reef could still recover from mass bleaching and an invasion of coral-eating starfish. However, he stressed that the loss of coral cover in other parts of the reef shows that it may still be affected by climate change.
Mike Emslie, head of the monitoring program team, said the increase in coral cover was caused by fast-growing Acropora corals — their colonies form the basis of reef formation. However, they are also sensitive to heat and are loved by starfish.
Australian Marine Conservation Society Great Barrier Reef campaigner Cherry Muddle warned that while the report was a sign of progress, the reef remained at risk.
According to the Great Barrier Reef Marine Park Authority (GBRMPA), four of the six cases of mass bleaching of the reef have occurred since 2016. The most recent occurred in March 2022, when bleaching affected 91% of surveyed reefs. This is much more common than before when about a quarter of surveyed reefs in 2020 showed signs of severe bleaching.
The discoloration is the result of higher than normal water temperatures causing a stress response in corals. However, this yearʼs coral bleaching was the first to occur during La Niña, a weather phenomenon typically characterized by cooler-than-normal temperatures in the equatorial Pacific.
- Coral reefs are among the most endangered ocean ecosystems: they are vulnerable to pollution, rising sea temperatures, and changes in the chemical composition of water caused by emissions of carbon dioxide dissolved in it. Scientists predict that 70% to 90% of all living coral will disappear within the next 20 years. According to UNESCO, only about 20% of the ocean floor has been mapped to date.