Coral bleachings devastate Bali reefs as sea temperatures rise

BONDALEM, Indonesia — Indonesian conservationist Nyoman Sugiarto has been working for 16 years to preserve coral on the reefs of Bali, but the frequency of mass coral bleachings he says is now devastating.

Ninety per cent of the corals Sugiarto had nurtured on the reefs near his village in Bondalem, in northern shore of Bali, 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 he was told that 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, the US National Oceanic and Atmospheric Administration (NOAA) said more than 54 per cent 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.

Indonesia has roughly 5.1 million hectares of coral reefs and accounts for 18 per cent of the world's total, data from the country's tourism ministry showed.

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 Centre.

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

While Indonesia's corals are more resilient and