The old Florida guy in this video finds he can un-bleach his reef. Good for him! He's definitely onto something. What's going on?
My idea for coral bleaching is applicable more broadly to all ecosystems:
Deep water ocean temperature and salinity are much more stable than near tidal estuaries. Deep ocean species evolve to depend on that stability. Species evolving near tidal estuaries are adapted for instability. But, normally stable conditions can go unstable for natural reasons. For example 16th century multiple beached whales in Holland are explainable by infectious disease or red tide.
With the corals, I'd take it that the GBR (Great Barrier Reef) is strongly stable compared to anywhere around coastal Florida. My guess is that the Florida guy in the video has picked up a subspecies more tolerant of instability. Such would be much easier to find in Florida than on the GBR. Over the long haul, the GBR will repopulate because the sunlight and nutrients are still there. Life will invade it. It could repopulate rather quickly. Or rebuild with wholly different species like grasses and sea turtles.
What's going to be really exciting is when corn, rice, and wheat monocultures get hit by something new.