David Mills

The health of the Great Barrier Reef has shown historic signs of regrowth,thanks to a year without major disturbances caused by weather events like heatwaves and tropical cyclones（旋風(fēng)）.In an average year,the reef could be hit by three or four cyclones,but in 2021 no cyclones came on to the reef itself.

A total of 127 reefs were surveyed,with 69 showing increases in hard coral cover.The signs of regrowth were apparent（明顯的）in the northern,central and southern parts of the 2,300 kilometers long reef.Coral cover was at 27 percent in the north,26 percent in the centre and 39 percent in the south.

The clear message from this year's survey is that coral recovery can take place,and is taking place,in the right conditions.This year's report comes after the 2020 study,which found“encouraging”signs of coral growth in the central and southern parts of the Great Barrier Reef and coverage in the northern region.Of 86 monitored（監(jiān)控的）reefs,two thirds were showing signs of modest growth in 2020.The good news came with a note of caution,however,because the lack of destructive weather was unusual.

There is some encouraging news in this report—and another good year would help continue recovery—but we also have to accept the increasing probability of extreme weather events.

Indeed,the researchers also expressed doubt whether the coral variety leading the regrowth could withstand（承受）such threats.Lead researcher Dr Mike Emslie,from the Australian Institute of Marine Science (AIMS),warned that much of the coral growth they saw in 2021 came from Acropora corals,which are“fast to grow (but) often the first to go”as they are quite vulnerable.

“The Great Barrier Reef is under continual pressure.We will see disturbances in the years ahead,”Dr Mike Emslie said.