More corals again: hope for the Great Barrier Reef

Australian researchers have found the greatest coral growth on the Great Barrier Reef in 36 years. The reef appears to be recovering. However, the spreading coral species is very sensitive.

Two researchers glide past colorful fish and corals in their neoprene suits. One diver holds a long yellow tape measure in his hand and measures the reef. The other takes photos with an underwater camera. Mike Emslie and his colleagues studied the Great Barrier Reef in Australia for almost a year.

“In the north and center of the Great Barrier Reef, we’ve seen the strongest increase in hard corals in 36 years, since records began, explains Emslie. He is a scientist at the Australian Institute of Marine Sciences. In the south, however, the crown-of-thorns starfish has prevented regeneration. “He likes to eat hard corals,” says Emslie.

“Good News for the Reef”

Nevertheless, the researcher is very satisfied with the result: “This is really good news for the reef”. It shows that it is still a strong, resilient system and capable of recovering from disruptions.

Disruptions such as coral bleaching, which have happened four times in the past seven years. If the water is too warm for a longer period of time, the corals reject the algae they otherwise live with. As a result, they lose their color. Bleached corals are extremely stressed but are still alive and able to recover.

“We always knew the reef could recover,” says Emslie. The surprising thing is that despite the last two major coral bleaching events in 2020 and this year 2022, it has continued its uptrend. “I think this suggests that not all bleaching events are created equal.”

Hard corals are prone to waves

However, the scientists see that the disturbances occur more frequently and last longer. What they don’t know is the long-term effects of bleaching. The reef is on the mend but definitely not healthy yet, said Zoe Richards, a coral researcher at Curtin University in Perth, Australia.

According to the researcher, the world natural heritage has recovered thanks in particular to the fast-growing Acropora corals. They are like weeds. These fast-growing corals have an up and down cycle of sorts. They just boom. Then suddenly there are very many, but a single hurricane or bleach can wipe them all out.

The Acropora corals are particularly susceptible to waves because of their long, branched growth habit. In a strong wind or tropical cyclone, they could easily break. There are also minor threats such as poor water quality, shipping or the coral-eating starfish. But the biggest problem is climate change, rising water temperatures and, as a result, coral bleaching.

More pressure on the government

“There’s no denying that,” says Richards. She wishes for the healthy Great Barrier Reef back that she saw as a child. She is therefore happy that the parties that want to do something about global warming in Australia were able to gain ground in the last election. We urgently need these changes. “The news that the reef is recovering is positive, showing that there is still hope. But it’s no reason to take our foot off the pedal and stop putting pressure on the government.”

It has an interest in the reef recovering itself. UNESCO has repeatedly threatened to put the Great Barrier Reef on the Red List of World Heritage Sites in Danger.