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 (called "designed artificial reefs") for use as marine benthic habitat are used. Objects that have been used for the creation of artificial reefs include tires, cars, aircraft, demolition spoil, military tanks, Reef Balls, oil rigs, and architectural debris. 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. However, the object vary in their ability to produce marine life verses attracting life from nearby natural reefs. Generally, objects that produce the most are complex, stable, with large surface areas, and with features that enhance marine growth (rough, non-toxic surfaces). Durability (how long they last) is also an important feature since reefs can take many years to develop into rich communities.
Artificial reefs enhance the diversity of marine life in the midst of barren sea beds, providing a venue for eco-tourist SCUBA divers and reducing overuse of natural reefs.
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[edit] Designed Artificial Reefs
In recent years, the trend in artificial reef development has been toward designed artificial reefs which are materials specifically designed to function as reefs. Leading the way has been the Reef Ball Foundation with the introduction of Reef Balls in 1993. Designed systems can be modified to achieve a variety of end use goals. These include coral reef rehabilitation, fishery enhancement, snorkeling and diving trails, beach erosion protection, surfing enhancement, fish spawning sites, planters for mangrove replanting, enhancement of lobster fisheries, creation of oyster reefs, estuary rehabilitation, and even exotic uses such as deep water oculina coral replanting. Image: [1] Designed systems overcome the problems associated with "materials of opportunity" such as stability in storms, durability, biological fit, lack of potential pollution problems, availability, and reduction in artificial reef costs.
Due to the biological designs, designed reef also overcome the "attraction verses production" argument of materials used in the past. Reefs can now be designed to produce fish rather than just attract them from nearby natural reefs.
Designed reefs have been developed specifically for coral reef rehabilitation. They are much more sophisticated than materials of opportunity with specialized surface textures, and include features such as coral planting attachment points, specialized pH neutral surfaces (such as neutralized concrete, ceramics or mineral accretion surfaces), holes to create currents for corals, and materials other than iron, which can cause algae to overgrow coral.
Other designed systems enhance surfing, control erosion on beaches, create aquaculture opportunities for lobster, create oyster beds, or are used for a large variety of other specialized needs.
[edit] 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: stabilizing 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.
[edit] Mineral accretion
Artificial surfaces are being "grown" using a process called mineral accretion. In mineral accretion, a low voltage current is applied 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 a technique called the Biorock® Process using mineral accretion for Reef Restoration, Mariculture, and Shore Protection.
[edit] Reef Ball Designed Artificial Reefs
The Reef Ball Foundation is the world's leading designed artificial reef manufacturer [citation needed] and has built over 3,500 reefs in over 50 countries deploying worldwide over 1/2 a million modules. "Reef Balls" are also used as the basis for coral propagation and planting projects where coral reefs are re-grown on coral reefs. The Reef Ball Foundation is a publicly supported non-profit organization and assists governments, NGOs, schools and private organizations in the planning, manufacturing, deployment and monitoring of designed artificial reefs. See www.reefball.org for more information.
The Reef Beach Company [www.reefbeach.com] uses Reef Balls to build submerged breakwaters to protect beaches from erosion.
Eternal Reefs [www.eternalreefs.com] uses Reef Balls as memorial reefs with human cremains added to the modules and deployed as artificial reefs.
[edit] Notable artificial reefs
The largest sunken ship 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. In order to be sunk, the EPA had to issue a special permit to allow the disposal of a large amount of PCBs that could not be removed from the ship. PCBs are known to cause a large variety of human and animal health problems.
The world's largest coral propagation and planting project using artificial reefs was in Antigua [2]
In Canada, the Artificial Reef Society of British Columbia has sunk seven ships (mostly former Canadian warships) and one Boeing 737 since 1991.
In Malaysia, over 5000 Reef Balls were used around protected turtle nesting islands to deter netting and has successfully increased turtle nesting numbers.
In Campeeche Mexico, over 4000 Reef Balls have been deployed by local fishing communities to enhance fishery resources.
In Tampa Bay, Reef Balls are used under docks, in front of sea walls, and as a sumberged breakwater to create oyster reefs.
In Thailand, Reef Balls planted with corals were used after the Tsumani to help restore tourism in Phuket.
In Indonesia, PT Newmont empowered locals to restore thousands of coral heads using Reef Balls to offset damages from mining operations.
[edit] See also
- Osborne Reef, a failed artificial reef constructed of old tires
[edit] External links
- [3] Reef Ball Foundation
- [4] The Reef Beach Company
- [5] Eternal Reefs
- 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
