How does deforestation affect coral reefs?

The world's coral reefs are being damaged by harmful runoff, which new research shows is being caused by the clearing of forests. Preventing soil erosion may help protect the reefs, which shield coastlines from ocean waves, draw tourists with their brilliant colors and provide a habitat for fish.

For centuries, humans around the world have been clearing away forests to make room for livestock, farming, and other uses. Scientists say that when the forest cover is lost, soil washes away into rivers that flow into the oceans and, they believe, onto coral reefs.

That runoff adds nutrients to the ocean water. It's essentially too much of a good thing, and scientists have long suspected it can kill the coral. Runoff also clouds the water, blocking light from reaching the reef.