Use the passage from "Diving to Rescue Coral Reefs" to answer the question.
One great partnership is between corals and microscopic algae called zooxanthellae (pronounced zo-zan-thell-ee). Together, the algae and the coral build the reef. Zooxanthellae live in the coral’s soft tissue, where they are protected and receive the sunlight they need to grow. In turn, the zooxanthellae provide the coral with oxygen and essential nutrients.
The zooxanthellae give the corals their rainbow of colors. The ghostlike corals Michele and Howard found in Fiji had lost their zooxanthellae and turned white. Scientists call this bleaching. Unless the zooxanthellae are replaced, the corals will die within a short time.
Why is bleaching a sign that corals will die?
