The major current threat to coral reefs is population growth in coastal areas. With increasing numbers of people come all the problems of development, such as increased garbage and sewage in coastal waters.
Corals are also under attack in other ways.
Cyan ide and dynamite used by local villagers to catch fish can be disastrous for reefs. In many places, because reefs are made of cement-like calcium compounds, reefs are actually mined to provide construction materials for buildings. Even the millions of tourists who visit reefs to snorkel and admire their beauty take their toll. People sta nding on corals can harm them and boat anchors can cause terrible damage. The additional hazard of global warming may push the most vulnerable reefs over the brink of extinction.