As rising ocean temperatures threaten Pacific islands with coral bleaching, researchers at the Palau International Coral Reef Center (PICRC) believe that a model which predicts coral-bleaching can help to lessen the impacts on Palau’s reefs.

This past April, PICRC, in collaboration with Dr. Peter Houk of Guam and numerous Micronesian partners, published a groundbreaking model which predicts coral bleaching months in advance. PICRC researchers think that the model may give Palau the chance to put coral-restoration measures into action, to help reverse the seemingly irreversible problem of climate change.

The novel model is able forecast three to five months in advance the increase of sea-surface temperatures, which causes coral to bleach, and the increase of chlorophyll-a concentrations, associated with the coral-eating crown-of-thorns starfish. To do this it studies the interaction between the Pacific Decadal Oscillation and El Nino, which, in addition to its impact on coral reefs, is suspected to also have caused the mass disappearance of jellyfish from Jellyfish Lake in 2016.

Dr. Houk from the University of Guam Marine Laboratory developed the forecasting model using coral reef monitoring datasets from around the Micronesian region. These included surveys conducted between 2010 and 2016 at sites all around Palau’s archipelago, organized by PICRC.

Research conducted by PICRC shows that coral-bleaching and crown-of-thorns starfish have caused considerable damage to Palau’s reefs in past years.

“Global climate change and land development have resulted in mass bleaching and crown-of-thorns outbreaks for the past 3 decades in Palau,” said Marine Gouezo, who oversaw much of the research involved in the production of the model. “There was a crown-of-thorns outbreak in the 1970s and mass bleaching in 1998. It took 9 to 12 years for these reefs to recover.” 

Since coral reefs serve as food sources and habitats for much of the marine ecosystems, disturbance of corals affects the entire oceanic environment. Not only does this mean dwindling fish populations for food, but a reef which fails to recover could hurt tourism and coastal protection against erosion.

Despite how widespread the problems of coral-bleaching and crown-of-thorns starfish are, PICRC researchers say that the model can help Palau to implement timely preventative measures.

“The model could help to implement temporary management regulations to boost the recovery potential for reefs,” said Marine Gouezo. “For example, we know that good herbivory levels are key to early reef recovery, so depending on those levels at different locations, we could implement temporary fishing closures.”

The model could also give divers time to organize teams to control crown-of-thorns outbreaks, a technique that is used on the Great Barrier Reef in Australia.

But Marine points out that these are all only temporary solutions.

“The biggest challenge remains to curb greenhouse gas emissions,” said Marine. “But this is a global effort. Until this is addressed, the only way forward is to start implementing large-scale coral restoration actions.”

Dr. Yimnang Golbuu of PICRC, who co-authored the project, explained that long-term monitoring like that conducted by PICRC is essential in understanding the threats facing Pacific islands. “The data from the monitoring program has been used to report on the status of coral reefs in the Pacific, publications on recovery from bleaching, impacts of typhoons on our reefs and many more.”

He also stressed how important it is that scientists throughout the Pacific start talking about this. “Collaboration with other researchers around the region makes it possible to develop these models that can be applied throughout Micronesia. In science, partnership is critical in addressing these questions facing us.”

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