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Coral Reefs Under Threat
Corals may look like solid rock, but they are actually alive and extremely fragile. They are also in great danger. One of the major threats to the reefs is pollution from sewage and industrial chemicals, which kills the animals of the reefs. Another threat is runoff, or loose dirt from construction and deforested areas, which chokes coral with sediment. Whole reefs are sometimes intentionally poisoned or blasted with dynamite to collect animals for food or aquariums. Global warming may pose one of the most direct dangers to corals. Even the slightest temperature change in the water can hurt the algae that feed the coral polyps. When these algae disappear, the corals' white calcium skeletons are exposed. This "coral bleaching" makes the reef appear ghostly white. Without these algae, the corals cannot survive. Coral reefs are an important part of the ocean ecosystem, but they are disappearing quickly. And coral reefs grow so slowly—about an inch a year—they could be gone in a few decades.