Corals have recovered from storms and bleaching events to reach record levels in most of Australia’s Great Barrier Reef, according to a study. In the north and middle of the reef, coral abundance is higher than at any time since monitoring began 36 years ago.
The new corals are particularly vulnerable, meaning progress could be quickly reversed by climate change and other threats, officials said.
According to the BBC, the Australian Institute of Marine Sciences (AIMS) surveys the reef every year with divers slowly pulled by a boat, as well as from the air, to check its condition.
The Great Barrier Reef has caused many problems over time
After the fourth mass bleaching event in six years was confirmed in March, AIMS had major concerns ahead of this year’s survey.
“In the 36 years we have been monitoring the condition of the Great Barrier Reef, we have never seen a bleaching event this severe,” said executive director Paul Hardisty.
Bleaching occurs when corals, stressed by high water temperatures, expel the algae that live inside them and give them color and life.
As of 2016, only two mass bleaching events have been recorded.
The causes of bleaching phenomena
This year’s bleaching was the first to occur during a La Niña, a weather phenomenon that normally brings cooler water temperatures.
These recent results show that the reef can recover when conditions allow, Dr. Hardisty says, but “acute and severe disturbances” are becoming more frequent and prolonged.
The reef has also been affected by starfish that eat coral and tropical cyclones that create damaging waves.
Much of the new coral growth, a species called Acropora, is particularly vulnerable to threats to the reef, according to Dr. Mike Emslie of AIMS.
The Great Barrier Reef has been a World Heritage Site for 40 years because of its “enormous scientific and intrinsic importance” as one of the world’s richest ecosystems.
The Great Barrier Reef Marine Park Authority, which manages the reef, says the outlook for the reef is “very poor” due to climate change.
UNESCO, the scientific and cultural organization of UN, says not enough is being done to protect the reef.