Coral Reefs

The Importance of Coral Reefs

Coral reefs are a precious resource in the ocean because of their beauty and biodiversity. Coral reefs provide shelter for a wide variety of marine life, they provide humans with recreation, they are a valuable source of organisms for potential medicines, they create sand for beaches, and serve as a buffer for shorelines. Coral reefs are built by millions of coral polyps, small colonial animals resembling overturned jellyfish that use excess carbon dioxide in the water from the atmosphere and turn it into limestone.

The Variety of Coral Reefs

Coral reefs can be found in both shallow and deep waters and are classified into 3 categories:

Hard corals

Soft corals

Sea fans

In 1999, a deep coral reef 60 m below the surface was discovered by the United States Geological Survey (USGS) Center for Coastal and Wetland Studies near Pulley Ridge, an underwater barrier island west of the Dry Tortugas National Park off the southern coast of Florida. The Pulley Ridge reef absorbs more light by increasing surface area and growing flat rather than the usual vertical growth seen in shallower coral reefs. Other deep water reefs include the Darwin Mounds and the Mingulay reef complex. More is known about shallow water coral reefs in tropical zones than deep-water reefs discovered recently, however much research into these unique ecosystems is being conducted.

Tropical Coral Reefs

Tropical Coral reefs are biotic reefs formed in tropical waters by live organisms such as calcareous algae (including red algae) and corals. In contrast, abiotic reefs are formed by the deposit of sand and other materials in shallow water. Organisms responsible for building tropical (biotic) coral reefs can only grow at 20-28°C, so although coral reefs live in all oceans, most are found between the Tropic of Capricorn and the Tropic of Cancer. The best growing habitat for coral reefs is a clear-water photic zone less than 50 m deep where light shines down and microscopic algae can best provide photosynthesis for the corals.

The wide array of coral reef forms includes the Apron reef, the Fringing reef, the Barrier reef, the Patch reef, the Ribbon reef, the Table reef and the Atoll reef. The Apron and Fringe reef both reach down and out from the shore point or peninsula although the Apron reef is typically not as steep as the Fringe reef. Barrier reefs, like the Great Barrier Reef, are separated from the shore by lagoons. An Atoll reef surrounds a lagoon in a circular or uninterrupted fashion and is different from the others because there is no island in the middle.

A Critical Situation

Coral reefs are extremely sensitive to changes in light, temperature (bleaching), overfishing, damaging fishing practices, pollution, and excess sediment from development and erosion. Reefs in Southeast Asia are most at risk of damage due to these factors. Human activity is one of the greatest threats to coral reefs, particularly the destruction of mangrove forests that naturally absorb sediment and nutrients that can suffocate coral reefs with silt and algae blooms.

Former coral reef in the Florida Keys, USA. Destruction most likely due to massive former bleaching events caused by warmer surface waters, nutrient-overload from sewage and overfishing.

Cyanide fishing in the Indonesian and Philippine coral reefs of South Asia stuns and injures valuable fish. Although 85% of the world’s aquarium fish are captured with this destructive method, they suffer a 90% mortality rate usually several weeks after they have been poisoned by cyanide. Unfortunately, fishermen in developing countries depend on reef fish for income to provide for their families; however illegal fishing practices and overfishing is depleting fish stocks in these areas rapidly threatening the livelihood of these local populations. Fishermen hit the coral reefs with crowbars to shake out stunned fish and they also even fish with dynamite, which often destroys every living thing on the reef. Many reefs once teeming with life are now wastelands that even the most vigorous conservation efforts can’t begin to restore.

With approximately 85,470 sq kms of tropical coral reefs, Indonesia hosts about 33% of the total coral in the world and 25% of all fish species. However, in 2000 it was reported that over 70% of the coral reefs are in bad to fair condition due to fishing practices, out of control tourism, and long periods of bleaching. Coral reefs in the Philippines were found to be 77% less productive from 1966-1986 while the national population doubled in size. If the destruction continues, we will lose about 70% of the world’s reefs within 25-40 years.

The effects of El Niño during 1998 and 2004 are an example of the natural factors that influence the growth of coral reefs. During this El Niño, sea temperatures rose and the many coral reefs were bleached or obliterated. Coral bleaching occurs when the single-celled algae vital for coral reef survival and known as symbiotic zooxanthellae are rejected from the coral, soft corals, some sponges and even Tridacna clams. The pigment containing organisms are lost as temperature or stress level due to increased light reaches intolerable levels. As temperatures return to normal, some reefs can recover within several weeks or months. However, equilibrium may not be restored due to global warming and the bleaching effect exposes corals to white and black band diseases. There is some evidence that global warming may actually add to the productivity of an ecosystem through an increase in carbon dioxide and higher temperatures, though the validity of this evidence remains to be seen.

Massive coral bleaching occurred in the Great Barrier Reef of Australia between 1998 and 2002 and in reefs in the Indian Ocean, the Maldives, Sri Lanka, Kenya, Tanzania, and the Seychelles. Most areas in the Great Barrier Reef rebounded with little damage but in some areas approximately 90% of the coral has vanished. The reefs in the Indian Ocean suffered the most damage and 90% of the coral reefs were lost in the remaining five locations. In Indonesia the damage is less extensive but more diversity is lost in an area significantly more difficult to restore.

Conservation and Restoration

Part of the problem with the coral reefs in Indonesia was the move made in 1991 to delocalize power in the Indonesian and Philippine governments. The result was a lack of funding and national support for protection of the South Asian reefs. More recently, conservation efforts have included roping off Marine Protected Areas (MPAs), research and implementation of electrolysis as stimulant for growth, moving reefs to new places and cutting back on harmful fishing practices—all expensive and time consuming endeavors estimated to cost over $100 million dollars. MPAs have been established in regions like Indonesia so that sustainable fisheries can be managed and ecologically important habitats will be protected with a social and biological objective. Laws similar to those found in national parks have been developed to prohibit illegal harvesting of fishes. The hope is that by designating MPAs, coral reefs will be restored, areas will become more beautiful, diversity of life will not be lost and communities will have a sustainable source of income in fishing and tourism. Work is being done to effectively manage MPAs and scientists have found that co-management, the collaboration of local, provincial and national parties, is an effective management strategy. As with many organizations, MPAs will have to overcome challenges that include finding participants, streamlining viewpoints about how effective certain ideas will be and raising enough money to implement change.

An international and non-profit organization called the Marine Aquarium Council or MAC was created to make the aquarium fish trade more responsible and sustainable through education and to limit harmful fishing practices. By avoiding stock depletion, adding more governmental regulation of reefs, managing reefs better, learning how to take care of fish and food once it is caught and creating a reliable data record, the MAC hopes to avoid a ban on the aquarium industry with a loss of income to the locals and a boom in illegal fishing. Among those involved in the project are researchers, conservationists and industry operators, all who would like to find a sustainable way to meet industry demands through education in the form of international standards and certification plans. MAC hopes that consumers, collectors and retailers will begin to realize how important it is to them and others to sustain their most valuable natural resource—the coral reef.

Other conservation efforts by various organizations include the intricate process of growing coral and coral reefs, a fragile organism that is sensitive to any environmental or biological change. Coral can be grown using a process known as mineral accretion where limestone is stimulated to collect on metal by a safe low voltage current, providing a nice place for baby coral to latch on and grow. The voltage itself can be provided using solar panels or energy from wave action. Scientists active in the Global Coral Reef Alliance (GCRA) grow coral reefs and will even show others the technique. To learn more and view pictures of the restoration effort visit http://www.globalcoral.org.

» Coral Reef Conservation groups
» Marine Aquarium Council
» Wikipedia.org: Global warming
» Global Coral Reef Alliance

The Ocean / NEXT: The Open Ocean »

Feedback? | [Edit Content]

Site Map

The Ocean/Marine Science: Marine Life 101 | Tools & Methods | Relevant Journals | MarineBio Downloads

~ Sharing the wonders of the ocean to inspire education, research and a sea ethic ~
MarineBio.org, Inc. is a US 501(c)(3) tax exempt organization.
All memberships and contributions are fully tax deductible in the United States.
© 1998-2008 Copyright & Terms of Use. All Rights Reserved. Privacy Policy.
Chain Catshark in logo copyright © Richard Ellis.

~~~~~~~~~~

~~~~~~~~~~