Answer:
Coral reef bleaching
Explanation:
The correct answer would be coral bleaching.
Coral bleaching is generally define as the change in color that results from the expulsion of green symbiotic algae from the tissues of the coral.
The expulsion of symbiotic algae from the tissue of coral is usually caused by a change in stressor factors of ocean water such as light, temperature, nutrient.
When the temperature of ocean water increases as a result of global warming, the vibrant color of corals may be lost because the change in stress condition usually leads to the degradation of the algal pigments or outright expulsion of the symbiotic algae from the tissue of the corals. When this happens, it leaves the coral tissues completely white and they are said to have been bleached.