Artificial reef
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An artificial reef is a man-made, underwater structure, typically built for the purpose of promoting marine life in areas of generally featureless bottom. Ships may be scuttled to create artificial reefs, but a large variety of objects, including structures purposely built for use as marine benthic habitat are used. Objects that have been used for the creation of artificial reefs include cars, aircraft, demolition spoil, military tanks, and oil rigs. All of these provide hard surfaces to which algae and invertebrates such as barnacles, tunicates, corals, sponges, and oysters attach; the accumulation of attached marine life in turn provides intricate structure and food for communities of fishes. Marine life fairly rapidly establishes on and around these submerged structures. Barracuda, for example, establish rapidly around newly sunk vessels.
Artificial reefs enhance the diversity of marine life in the midst of barren sea beds, providing a venue for ecotourist SCUBA divers, reducing overuse of historically valuable wrecks. A variety of such features constitute the destination of submarine tours off Waikiki in the Hawaiian Islands.
Artificial Surfing Reefs
The term "artificial reef" is really a misnomer since these artificial structures are not actually reefs. However, reefs have been created for surfing purposes, with the world's first such man-made reef at Cables Beach, Perth, Western Australia. This reef was constructed of large granite rocks placed in a pyramidal shape to form an appropriate breaking wave form that would suit surfers. An artificial reef constructed of over 400 massive, geotextile bags (each one larger than a bus) filled with sand was constructed in 2000 at Narrowneck on the Gold Coast of Queensland, Australia. This artificial reef had two objectives: stabilising beach nourishment and improving surfing conditions.
Artificial surfing reefs typically resemble a "submerged breakwater", and proponents have suggested additional benefits beyond improving surfing conditions. In Hawaii and California, long stretches of coast are subject to powerful waves that crash directly onshore. An artificial reef situated 150-300 yards offshore would not only create surfing opportunities but, by dissipating wave energy before it strikes the shore, create safer swimming areas and reduce coastal erosion.
Construction of artificial surfing reefs is a relatively new technology and, worldwide, nations as diverse as England and New Zealand are discussing building their first projects. However, opposition from environmentalists has slowed approvals. Many environmentalists argue against coastal modification on multiple grounds, including the notion that coastlines are best left in their natural state. In part because of arguments for environmental protection, many nations have enacted extensive regulations restricting the alteration of coastal ecosystems.
In United States, in particular, complex coastal permitting requirements combined with environmental opposition provide a major obstacle to building surfing reefs. As of February 2006, the only reef built in the U. S. specifically for surfing purposes is "Pratte's Reef" in southern California. Artificial reefs built for enhancement of marine habitat face far less environmental opposition, in part because they are located in much deeper water some distance offshore. A number of such man-made reefs exist off of Florida and in Hawaii.
In November 2005, ASR, a company that builds artificial surfing reefs, began construction of a reef at Mount Maunganui, New Zealand. By that December, the site was already producing rideable waves.
Mineral accretion
Artificial surfaces are being "grown" using a process called mineral accretion: applying a low voltage current to a metallic structure to cause limestone to accrete or build on the surface, upon which coral planulae can attach and grow. This greatly speeds the coral growth process on artificial surfaces. The voltage is low enough that it can be generated by floating solar panels or from wave motion. A coalition of scientists known as the Global Coral Reef Alliance (GCRA) has been developing the technique.Notable Artificial Reefs
The world's largest artificial reef is located 24 miles off the coast of Pensacola, Florida, and is composed of the warship USS Oriskany, which was sunk with controlled charges on May 17, 2006.External links
- [Artificial Reef Consortium] (UK)
- [Artificial Reef Society of British Columbia]
- [Cables Beach surfing reef] Perth, Australia
- [California Artificial Reef Enhancement Program] (CARE)
- [Florida Fisheries] – Album of Photos of Artificial Reefs
- [Global Coral Reef Alliance] (GCRA)
- [Mount Maunganui Reef] Website describing New Zealand's first artificial surfing reef
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