Unfortunately human impact has not been a good thing for coral reefs. Not all damage to coral reefs can be blamed on humans though. Tropical storms cause substantial damage to coral reefs. Some take up to 50 years to completely rebuild the damage and be fully restored. Other natural disasters like volcanos and coastal landslides can also greatly effect coral reefs. Even natural outbreaks like the crown-of-thorns sea star that devours coral colonies can significantly diminish a coral reef ecosystems. Sadly though, most of the damage to the worlds coral reefs have been human related.

Pollution, silt from drainage, over-fishing, and careless destruction has drastically reduced the coral reefs of the world. Some fishermen in the Pacific and Indian Oceans dynamite reefs. The stunned fish float to the surface where they are scooped up into the fishing boat. This has enormous destructive consequences for the coral reefs. In the Philippines fisherman use bleach or sodium cyanide squirted from plastic bottles to paralyze exotic fish to catch for commercial sale to hobbyists. This sodium cyanide is very toxic to the coral and the small fish around it. Some fish die instantly; up to 80% of the rest will die from the effects of the poison within a few weeks. The aquarium industry annually sells 200 million dollars worth of live caught marine stock worldwide. The biggest market is the United States.

Apart from over fishing coral reefs, substantial damage is done by pollution. Coral reefs can tolerate up to a certain amount of foreign elements, but if no member of the reef can break it down then it becomes pollution. This pollution dumped from boats or land sewage drains stimulates algae growth. The algae overwhelm the coral reef not allowing enough light to pass through the water. The over fishing reduces populations of herbivorous fish, which further promotes the algae bloom.

Farming and logging near coral reefs has also proven to be damaging. The silt runoff from cleared land can cause coral to be substantially weakened or even die. The canals built to supply Miami and surrounding cities with water has been demonstrated to be devastating to the Everglades (by draining the water out of it) and the coral reefs around the Florida Keys (by producing increased amounts of silt deposited in the reefs). See Figure 4 The coral reefs around the Florida Keys are in great danger of being completely destroyed if we do not take action.

Coral reefs are even mined for construction material and fragments of coral sold for aquariums and souvenirs. Deep sea precious corals like pink, gold, and black corals are harvested to make jewelry. Even good minded visitors can break a tip off a Elkhorn coral with their fin and cause years of damage.
All of these stresses put together weaken the coral and make it very prone to deceases like Aspergillosis and White plague II which have recently been discovered in the Florida Keys.

Besides all of this, preservation of the coral reef environment is a possibility. Select coral reefs sanctuaries can be closed down form exploitation by making them underwater parks to be used for research and better understanding of coral reef ecosystem. Scientist need time to study coral reefs so we can further understand them, time they may not have if we are not careful. Even if you don’t ever visit a reef you can help protect the by practicing the three “R’s” reduce, reuse, and recycle.