Sea water around a coral reef warms well above its usual range. What happens to the corals?

1. Shallow water corals live in mutualism with photosynthetic single celled algae. 2. Those algae supply most of the nutrition and energy the coral needs. 3. Corals evolved at the upper limit of ocean temperature, so they have little margin left. 4. Excess warmth makes the coral expel the algae, and the colony loses its color. 5. That loss of color is called bleaching. 6. If the loss lasts, both the algae and the coral animals die. 7. Corals are fixed in place, so moving to cooler water is not an option for them. 8. Rising carbon dioxide adds a second problem by lowering pH and hindering calcification. _Source: OpenStax Biology 1e (CC BY 4.0), Chs 44 and 46, section 44.4 Aquatic Biomes_