Many coastal communities also benefit from the tourism and fishing generated by coral reefs. Like tropical rainforests, the rich biodiversity of the coral reef ecosystem may serve as a source for unique chemicals with medicinal properties, just waiting to be explored and discovered. Coral itself can be used in human bone grafts. Sponges growing on reefs can provide virus-fighting agents. Endangered Coral Reefs For all their splendor and biodiversity, the world's coral reefs are endangered.
Fishermen stun tropical fish by squirting cyanide into the reefs.
This technique enables them to capture live fish for aquariums. In the process, the cyanide poisons both the reef and many of the invertebrate species living in its ecosystem. Sewage, fertilizers, and pesticides all originate on land and often run off into the ocean. Since coral reefs are close to the shoreline, they are exposed to these pollutants in high concentrations. Oil spills at sea generally occur close to shore, often when the tanker runs into rocks in the shallow waters.