Stopping direct sunlight exposure to help stop coral bleaching is an awesome idea.
Have to nitpick though, umbrellas protect you from falling water, parasols block light.
Though I suspect "scientists deploy parasols for coral" sounds a little too much like the reef is on vacation
https://www.etymonline.com/word/umbrella
Though I suspect "scientists deploy parasols for coral" sounds a little too much like the reef is on vacation