Coral Reefs Are In Danger

Some of the factors which are endangering the world's coral reefs.

The coral reefs of our oceans are under siege. By some estimates, at the current rate of destruction, 70 percent of reefs will be lost within a single generation. There is no one culprit to blame for this devastation, but humans must assume part of the responsibility.

Coral is a living organism, created through a cooperative alliance of coral polyps, a tiny animal that filters rock fragments from the surrounding water and single-celled plants that dwell within the polyps. The plants generate many of the nutrients the corals need to live and capture calcium from the seawater, which the polyps use to build their limestone shells.

Coral reefs are home to over 25 percent of all marine life and among the world's most delicate ecosystems. But, corals thrive only in clean, clear, shallow tropical waters and those conditions are getting more rare. Scientists are still learning how to best manage these fragile, yet beautiful living organisms. Major threats to coral include:

Fishing with cyanide and explosives: Commercial fishing fleets have long used cyanide in the ocean. Cyanide fishing is a method which uses poison to stun and disorient fish before scooping them up. Still alive, the fish are sold for the tropical aquarium trade or for live fish restaurants in Hong Kong and other Far Eastern cities. Dinner is selected while it's swimming in the tank. Unfortunately, the trade is highly profitable, since a live fish is worth much more than a dead one.

However, the cyanide kills the coral polyps, the symbiotic algae and other creatures in the vicinity. Adding to the damage, fishermen often break the coral apart with crowbars to reach hiding fish. Cyanide fishing is practiced across Southeast Asia, especially in the Philippines, where tons of cyanide is squirted into the reefs every year. As the reefs in the Philippines die off, this disreputable trade is moving out across the South Pacific.

Other fisherman prepare bombs using material such as potassium nitrate (a common fertilizer) to cause large explosions which kill all the fish in the surrounding area and reduce the nearby coral to lifeless rubble.

Sedimentation: Increased construction along coasts, inshore building, mining, farming upstream or logging in tropical forests all cause soil to erode and rush downstream into the ocean and onto coral reefs. This silt, dirt and sand can make the water cloudy or muddy, smothering the coral which can't get enough light to survive.

Mangrove trees and seagrasses which normally act as filters for sediment are being rapidly lost. This leads to an increase in the amount of sediment which reaches the reefs. Mangrove forests are often cut for firewood or removed to create open beaches, and they are destroyed by prawn harvesters to open areas to create artificial prawn farms. It's estimated more than half the mangroves that once covered the world's tropical coastlines have been destroyed.

Careless Recreation: Another on-going source of reef destruction are the boats that carry tourists and divers. The Belize Wall, for example, near Ambergris Cay, now has only 50 percent live coral due to anchor damage from irresponsible dive masters. When individuals kick, grab, or walk on coral, they contribute to the death of the reef. Heedless scuba divers gather live coral as souvenirs of their dive adventure. At least one cruise ship destroyed a section of coral by dragging it's anchor chain across a large portion.

Global Warming: Scientists believe the biggest threat to the reefs may be global climate change, causing sea temperatures to rise. When temperatures in the ocean get too high, coral polyps lose the symbiotic algae inside them, causing them to turn white, a condition known as "bleaching." It's theorized the corals do not have the genetic ability to acclimatize rapidly enough to rising water temperatures.

There has been an unprecedented increase in the amount of coral bleaching during the last twenty years, which have been some of the warmest years in history. After bleaching, seaweed will move in and make it more difficult for the coral to re-establish themselves. Although some bleached reefs do return to normal, it's a lengthy process.

Other Man-Made Threats: Construction projects to build sea walls or piers, for example, may help the tourist trade in tropical destinations, but the consequences often endanger coral reefs. Human run-off in the form of sewage and fertilizers are dumped into coastal waters, as are chemicals and petroleum products. Over-fishing compounds other reef stresses, by removing creatures that ordinarily feed on algae and clean the reefs.

Trash, created by humans and carelessly tossed out by humans, has negative impact. Ocean currents deposit the refuse hundreds, even thousands of miles from their point of origin. One recent clean-up effort on an atoll called French Frigate Shoals, netted 8.25 tons of debris including abandoned fishing nets, plastic bottles, golf balls and just plain garbage. This costly effort took numerous divers and support personnel, plus a full month to complete. Such debris seriously interferes with the health of the reefs and harms all the sea creatures.

Often the most attractive and the most economically valuable reefs are those found in developing countries. These countries, however, are struggling with major challenges such as wide-spread poverty, building roads and handling sewage disposal or even government instability. Under such difficult circumstances, protecting their coral reefs may not seem like a high priority. Or, the fast tourist buck wins out over long-term considerations, usually to the detriment of the coral reefs.

As an integral part of our oceans, coral reefs deserve our protection, but it's not a simple matter. Unfortunately, there's political inertia, a lack of funding and little awareness. When you take a dive, snorkel or swimming vacation, be part of the solution, not part of the problem. Choose tour operators carefully and beware of live fish restaurants. Think long and hard before buying coral jewelry.

There are several organizations now striving to protect and preserve these jewels of the sea. The Coral Reef Alliance is working to save coral through a number of educational programs. The International Coral Reef Initiative is another such group, as is the Planetary Coral Reef Foundation.

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