PICRC Collaborates on Study on Satellite-Measured Temperatures in Palau’s Reefs

Ocean heat waves driven by climate change pose a serious threat to coral reef health worldwide, causing coral bleaching and mortality events in many regions. Given the economic, ecological, and cultural importance of these marine ecosystems, significant research efforts are underway to better understand, predict, and mitigate the impacts of climate change on coral reefs.

As part of these efforts, satellite-derived sea surface temperature data are commonly used to assess the risk of heat stress and bleaching in reefs across different regions of the world, helping to inform the implementation of appropriate conservation measures. But how accurate are satellite-derived temperature data when compared to in situ measurements?

This question was addressed in Palau by a study led by PhD student Marilla Lippert (Florida State University), in collaboration with researchers from Stanford University, the University of Washington, Claremont McKenna College, the University of Maine, and local researcher Victor Nestor from the Palau International Coral Reef Center (PICRC).

After collecting temperature measurements at 87 barrier reef locations across the northern, western, and southern regions of Palau using in-water temperature loggers, researchers compared these in situ data with satellite-derived temperature records for the same areas. The results showed that satellites provide relatively accurate estimates of average nighttime temperatures but are less reliable for other metrics, such as thermal maxima, diurnal temperature range, and heat accumulation—parameters that are essential for assessing coral heat stress and bleaching risk.

The study concluded that satellite-derived temperature measurements are a key tool for monitoring ocean temperatures at a global scale; however, they cannot replace in situ studies when precise, site-specific data are required—for example, in the design of local reef management and restoration strategies. Through PICRC’s collaboration with international universities, as well as with local and international partners, this five-year project was undertaken to generate meaningful scientific data to support informed reef management in Palau.

The full study, “Satellite-derived temperature measures miss key physiologically relevant thermal trends on Palauan reefs,” is available open access at: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0341926