Regardless, being that the buoy and how it measures temperature is a constant, if surface temperatures are trending upwards, then the water temperature is increasing. Not all corals are 90ft below the surface, some are in 5-20 ft and will be impacted.I would think the designers of temperature-measuring buoys would take that effect into account and ensure there is adequate thermal insulation between the probe and the rest of the buoy, or even build in some kind of temperature compensation to account for that heat transfer. We would really have to understand how these buoys measure the water temperature to know how accurate the reported measurements are.