Climate Watch: Corals Battling Heatwaves to Survive

Marine heatwaves are projected to be more intense and prolonged, with the equatorial Pacific seeing an increase in annual mean marine heatwave duration from around 30 days today to 100 days at 1.5°C of warming.
20 Mar 2022 14:35
Climate Watch: Corals Battling Heatwaves to Survive
The coral planting team from Conservation International Fiji. Picture: Kelera Sovasiga

Out in the crystal turquoise waters of Kabara in the Lau Group lie pristine layers of corals. But for how long will these corals survive in an increasingly hot world.

A summary of findings from the United Nations Intergovernmental Panel on Climate Change’s (IPCC) Sixth Assessment Report (AR6) on the Physical Science Basis prepared by the Australian National University Institute for Energy, Climate and Disaster Solutions maintained that marine heatwaves would continue to increase in frequency, duration, and intensity irrespective of future warming.

Over the rest of the 21st century, the projected rate of ocean warming could double in a very low-emission scenario and be up to eight times higher in a very high-emission scenario relative to the current rate of warming.

Marine heatwaves are projected to be more intense and prolonged, with the equatorial Pacific seeing an increase in annual mean marine heatwave duration from around 30 days today to 100 days at 1.5°C of warming.

This would double at 2.0°C of warming, reaching 200 days in average duration. The summary said marine heatwaves contribute to coral bleaching events in the Pacific and changes in marine productivity and the location of fish populations that are essential to food security and local economies.

Initiatives like the Lau Seascape are working directly with communities to turn the tide. According to the Lau Seascape Initiative, around 80 per cent of the Lau corals are vibrant and healthy.

However, a number of coral nurseries set up by Conservation International Fiji during their December visit were affected by the tsunami caused by the Tongan volcanic eruption in January.

The island of Kabara also felt the aftershock.


For Laseini Labati, it was the first time to accompany the team from Conservation International Fiji as they revisited nearby coral sites.

The project has been part of the Lau Seascape Initiative to protect and rehabilitate reefs and corals.

“It’s one thing to just admire the beauty of healthy corals, it’s another to know the importance of maintenance  and protecting it for the sake of our future generations,” Mr Labati said.

“It takes a lot of hard work replacing dead corals and making oral racks or frames that will help new corals grow.”

Mr Labati is from the village of Tokalau.

Over the years, the changing weather patterns have somehow contributed to the state of corals and the nearby reefs, Mr Labati said.

“When we were small, we would cool off in the sea because the water temperature would be cold. But now, it has become very warm, at times hot and I know this affects the growth of the corals.”

Mr Labati is thankful to Conservation International Fiji for replacing bleached corals with healthier ones.


Since 2013, Conservation International Fiji has been working with the Masi ni Vanua o Lau to lay the foundations for successful interventions across the province.

Conservation International Fiji Technical Assistant, Livai Tubuitama, said three coral racks were set up in Kabara, but unfortunately, because of the tsunami waves from the volcanic eruption in Tonga, two racks were washed ashore.

“One coral rack would have 500 coral plants so the two coral racks that were damaged by the Tongan eruption had a total of 1000 coral plants,” Mr Tubuitama said.

“The third coral rack that was still underwater had a 40 per cent survival rate.”

The vanua of Lau is grounded in values of respect and collaborative participation to achieve sustain- able regenerative resources by 2030 for current and future generations and to overcome challenges with the guidance of the Almighty God.

Lau Provincial Conservation Officer, Viliame Driti, said the coral initiatives have been established for the purpose of food security for the Lau group’s pledge to the government of 200,000 corals from 2018 to 2022.

“Managing coral nursery is not easy,” Mr Driti said.

“There is a depletion of resources due to overfishing and other activities hence resources are not man- aged wisely so this trip has been both an awareness and implementation project that will help food security and raise the standard of living,”

Villagers were advised on the importance of corals and its nurseries that included the damages of throwing boat anchors on coral tips.

“We need to find better ways to protect our corals in a way that will not damage corals and not affect the livelihoods of villagers who depend on marine resources,” he said.

The team also visited Ogea Island and found a 75 per cent survival rate with the two nurseries that were already setup in December last year.

On Thursday, the team visited the sites in Fulaga and received positive feedback as the coral racks were healthy.

53-year-old Qeleyasi Tokasa of Muanaicake, Fulaga, said she had gone fishing on Wednesday and came past the coral nursery.

“I know the nursery was doing its job because I saw a lot of different fishes feeding on the corals,” Ms Tokasa said.

“I did not want to disturb it because of the different marine species surrounding it and it looked healthy.”

Yesterday, the team were in Moce Island and went out to Marine protected areas to place two coral nurseries. They will plant at least 1000 coral fragments.

The coral planting team (from left) Lau Provincial Conservation Officer Viliame Driti, and GIS Officer Kalesi Nadalo in Kabara. Photo: Kelera Sovasiga

The coral planting team (from left) Lau Provincial Conservation Officer Viliame Driti,
and GIS Officer Kalesi Nadalo in Kabara. Photo: Kelera Sovasiga



  • Coral tips are taken from corals, and it is cable tied to frames or racks.
  • It is then put back out in the ocean to help it regrow.
  • After a few months, the team will return for live counts and assess the coral racks and its growth.

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