Parts of Great Barrier Reef show highest coral cover seen in 36 years

Two-thirds of the Great Barrier Reef in Australia recorded the highest amount of coral cover in nearly four decades, though the reef is still vulnerable to climate change and mass bleaching, a monitoring group said Thursday.

The northern and central parts of the UNESCO world heritage-listed reef have experienced some recovery while the southern region has seen a loss of coral cover due to crown-of-thorns starfish outbreaks, according to a report by the Australian Institute of Marine Science, a government agency.

AIMS CEO Paul Hardisty said that while the coral in the north and central regions was a sign the reef could recover from disturbances, the loss of coral in the southern region demonstrated how the reef is still vulnerable to “continued acute and severe disturbances that are occurring more often and are longer-lasting.”

The Great Barrier Reef has suffered from widespread and severe bleaching because of rising ocean temperatures. The reef was hit especially hard in 2016 and 2017 by underwater heat waves that prompted bleaching events. This year, it’s suffering a sixth mass bleaching due to heat stress caused by climate change.

“Every summer the Reef is at risk of temperature stress, bleaching and potentially mortality and our understanding of how the ecosystem responds to that is still developing,” Hardisty said in a media release.

“The 2020 and 2022 bleaching events, while extensive, didn’t reach the intensity of the 2016 and 2017 events and, as a result, we have seen less mortality,” Hardisty said. “These latest results demonstrate the Reef can still recover in periods free of intense disturbances.”

The report comes after UNESCO last year proposed adding the Great Barrier Reef to a list of world heritage sites that are in danger. A meeting to discuss the future of the reef was supposed to be held in Russia in June but was canceled after the invasion of Ukraine.

On the central and northern regions, hard coral cover reached 33% and 36% this year, respectively, the highest level recorded in the past 36 years of monitoring, the report said. Meanwhile, regionwide hard coral cover on reefs in the southern area fell to 34% this year, compared with 38% in the year prior.