Coral reefs protect coastlines from storms and erosion. They are also are a source of food and new medicines. Over half a billion people depend on reefs for food, income, and protection. People should not destroy nor harm them.
Do they catch storms? Or how they protect in detail?
If there is no water, no algae. Algal cells contain chlorophyll which enables 'em to photosynthesize, i.e., using sunlight to convert carbon dioxide into cellular material.