Nova: Season 48, Episode 7

48 - 7: Reef Rescue

Coral reefs are not just beautiful; they are also home to over a quarter of all marine life and are crucial to human societies around the globe. But as the climate changes and oceanic heatwaves become commonplace, corals are bleaching, and reefs are dying off. Now, marine biologists worldwide are teaming up to counteract this catastrophe with a technique called assisted evolution. Follow scientists as they attempt to crossbreed heat-resistant corals and even transplant corals' algae in a race to save the coral reefs from extinction.