A Comparison of in Situ and Satellite-Based Water Temperature Data over Tropical Coral Reefs: Implications for Ecological Forecasting of Coral Bleaching

Thermally-driven coral bleaching is a significant contributor to the global decline of coral reefs on which many coastal populations and economies depend, and bleaching forecast models provide valuable guidance to reef managers for implementing monitoring and mitigation activities. Due to the general lack of in situ observations on the world's reefs, bleaching models rely on satellite estimates of sea surface temperature (SST) as a proxy for subsurface water temperatures. However, the accuracy of satellite-based SST in near-shore, shallow (< 30 m) reef zones is uncertain. A number of oceanographic factors may introduce bias that can affect the reliability of ecological forecasts at sub-regional scales. To assess this possibility, a series of water temperature profiles were established on coral reefs around Little Cayman Island to collect simultaneous surface and subsurface temperature data. Data from these profiles are compared to observations from a nearby Coral Reef Early Warning System (CREWS) scientific data buoy as well as satellite observations of SST. This paper details the degree of agreement between the three data sources, evaluates reasons for any discrepancies, and discusses steps toward data integration that can better inform ecological forecasting models for coral bleaching.