(Reuters) -More than four-fifths of the world's coral reef areas have been affected by devastating mass bleaching spurred by record-high ocean temperatures, turning many once-colourful reefs a ghostly pale hue, scientific authorities said on Wednesday.
Bleaching is triggered by anomalies in water temperature that cause corals to expel the colorful algae living in their tissues. Without the algae's help in delivering nutrients to the corals, the corals cannot survive.
