Excessively high global temperatures can cause strong negative physiological responses in corals such as bleaching, disease, and mortality. Marine heatwaves can also threaten the life of other coral reef organisms, including fish.

Satellite measured temperature available 
Sea surface temperature (SST) measured from a satellite is essential for describing marine environments. Such measurement data is widely used today but has a relatively low spatial resolution. However, the NASA ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) instrument aboard the International Space Station has a much higher spatial resolution but is not validated for thermo measurements over reef environments.

Correlation study on data from space and in-situ
Temperature data from ECOSTRESS would be a great resource for the coral reef research community and would support adaptive management, especially so for the design of marine protected areas. Researchers from King Abdullah University of Science and Technology, Saudi Arabia, Coral Reef Alliance, University of Miami, and University of South Florida, USA, recently published a study evaluating the correlation between the different water temperature data sources - both from space and the field.

Water temperature measured at two reef sites in the Red Sea
21 Star-Oddi DST CTD loggers were deployed at two reef sites in the Saudi Red Sea to measure temperature for three years (see Fig 1.). Six loggers were distributed between 4.3 m and 9.7 m water depth and measured data from June 2021 to March 2023 at a 30-min recording interval. At the second site, 15 loggers were distributed between 4.0 m and 7.9 m water depth and provided data from July 2022 to August 2023 at 10-min intervals. GPS fixed the positions of the loggers to within 5 m, thereby allowing for a straightforward comparison of the in-situ and remote sensing data. 

Compared data shows the advantage of new space temperature measurements
Data from all 21 loggers were combined into one master dataset and compared with temperature datasets from space (low resolution SST and high resolution ECOSTRESS). Both orbital platforms correlated strongly with the CTD logger recordings, but only ECOSTRESS data was detailed enough to construct thermal microclimate maps with the dynamic temperature fluctuations in the reefs.

In the ECOSTRESS data there was a systematic bias to cooler temperatures by 1.02°C-1.03°C as compared to the in-situ loggers, which is consistent with prior studies using ECOSTRESS over water. Regardless, the researchers conclude that ECOSTRESS represents a significant advancement in the capability to monitor heat stress on reefs from space.  

The paper was published in the journal Coral Reefs in February 2025, and can be found here 

Picture: Red Sea Development company