• Research

PICRC conducts surveys to assess the bleaching event occurring in Palau

Researchers from the Palau International Coral Reef Center (PICRC) have conducted surveys at 80 sites to determine the extent of the 2022 coral bleaching event, after reports that the corals are turning white. 

“Both our observations and the reports from community members made it clear that a bleaching event is happening in Palau,” said PICRC researcher, Ikelau Otto.

Ms. Otto explained that corals need a delicate environment to survive with a steady temperature. If the water temperature gets too high for them, they start to stress. When they stress, they release symbiotic algae, which are necessary for their survival. The algae (also called zooxanthellae) are what gives corals their color, so when they release them, they turn white. Corals can recover if the conditions go back to normal. But if they stay like this for too long, there is an increased possibility of them dying.

In 1998, there was a mass bleaching all around the world. Palau’s reefs were heavily impacted. This event prompted the researchers in Palau to start to look at coral bleaching. They found that it took 12 years for the coral to recover. Then, in 2010 and 2020, there were other bleaching events in Palau. 

“While we might have had bleaching in the past, the issue is that we’re seeing it more and more frequently and the corals don’t have a chance to recover between them,” according to Ms. Otto.

In October, the researchers did a rapid assessment, where they chose a few sites around Palau to check the level of bleaching. Based on this initial assessment, they determined that it was significant, so they decided to do full coral bleaching surveys. 

The researchers visited 80 chosen sites to monitor the coral there and find out what percentage was bleaching. They are now analyzing the images. These surveys will help answer several long-term research questions such as how the coral in Palau respond to higher temperatures and bleaching, if there is evidence of adaptation, and whether some species of coral are more resilient than others.