Coral bleachings devastate Bali reefs as sea temperatures rise

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Nyoman Sugiarto, a 51-year-old conservationist, dives underwater to check on the health of corals living on an artificial substrate he planted in June in Bondalem village, Buleleng regency, Bali, Indonesia. (REUTERS/Yuddy Cahya Budiman/File Photo)
Fish swim near recovering coral reefs in June after bleaching in late December 2023 due to extreme weather, in Bondalem village, Buleleng regency, Bali, Indonesia. (REUTERS/Yuddy Cahya Budiman/File Photo)
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Indonesian conservationist Nyoman Sugiarto has been working 16 years to preserve coral on the reefs of Bali, but the frequency of mass coral bleachings he says is now devastating.

Ninety percent of the corals Sugiarto had nurtured on the reefs lost their colour last December.

“It was all white. We were shocked and of course, it also negatively affected the coral we planted. It’s not just the natural ones,” 51-year-old Sugiarto told Reuters.

When Sugiarto began coral conservation projects in 2008 coral could retain the living algae which gives it colour for 10 to 20 years.

Yet, the coral reefs off Bondalem were bleached in less than 10 years, he says, blaming warmer sea temperatures triggered by climate change.

Coral bleaching occurs when coral expels the colourful algae living in its tissues. Without the algae the coral becomes pale and vulnerable to starvation, disease or death.

In April, NOAA said more than 54% of the reef areas in the world’s oceans are experiencing bleaching-level heat stress, the fourth global bleaching event in the last three decades.

Coral bleaching in Bali in late 2023 was mainly caused by rising sea temperatures caused by the El Nino phenomenon that hit Indonesia, said Marthen Welly, a marine conservation adviser at the Coral Triangle Center.

Indonesia experienced the most severe dry season last year since 2019 due to the El Nino.

While Indonesia’s corals are more resilient and tend to recover faster, Marthen said it will not be enough to withstand the rising ocean temperature.

“It’s predicted that the coral bleaching will occur more often, between one or two years with the current temperature,” he said, quoting the latest research by the Great Barrier Reef Marine Park Authority a

However, Sugiarto says he will continue his campaign to conserve corals.

“We have the obligation to guard the sustainability of underwater life especially corals,” he said.