Two questions sound alike and are not.
What fraction of the coral-covered area is bleached? Points answer this directly: points on bleached tissue, divided by points on coral.
What fraction of colonies are bleached? Points do not answer this at all. Points sample area, so one enormous colony contributes many and a small one contributes few or none. A reef where a single huge colony has bleached and thirty small ones have not reads as heavily affected by area and barely affected by colony.
Neither is wrong. They answer different questions, and much published monitoring reports the second one. You report the first.
The other measurement is made a different way: a diver matches individual colonies against a standard hue chart, in the water, and records how many are affected. CoralWatch, run from the University of Queensland, has been doing exactly that for over twenty years across more than eighty countries. Their Coral Health Chart is a standardized set of coral hues whose squares correspond to symbiont concentration, developed against real corals rather than chosen for convenience.
You finish this course unusually well placed to contribute to it. You have a documented station. You know why area and prevalence are different questions, which most volunteers never learn. And you have spent a course laying a standard reference in every frame, so you know what one is for.
That contribution is a separate activity from your Site Entry —
their survey, their format, their database, and not merged into your
condition figures. It is worth doing, and it is the most direct way to
put what this course taught you onto a question it cannot answer. See
coralwatch.org.