As an intensifying heatwave grips much of the country, scientists turn their eye towards the ocean as rising temperatures put one of the most diverse marine ecosystems at risk of death. WATCH NIGHTLINE EPISODES: abc.go.com/shows/nightline ALSO AVAILABLE ON HULU: hulu.tv/2wSmSrZ #nightline #gingerzee #coralreef #florida #heatwave #weather #abcnews