Artificial reef: Difference between revisions
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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. |
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. |
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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. |
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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 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. |
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Revision as of 19:09, 2 March 2007
An artificial reef is a man-made, underwater structure, typically built for the purpose of promoting marine life in areas of generally featureless bottom. Artificial reefs may also serve to improve hydrodynamics for surfing or to control beach erosion.
Artificial reefs can be built in a number of different methods. Many reefs are built by deploying existing materials in order to create a reef. This can be done by scuttling ships to create artificial reefs (such as the USS Oriskany), or by deploying rubble, tires, or construction debris. Other artificial reefs are purpose built (e.g. ASR or reef balls) from PVC and/or concrete. Regardless of construction method, artificial reefs are generally designed to provide hard surfaces to which algae and invertebrates such as barnacles, corals, and oysters attach; the accumulation of attached marine life in turn provides intricate structure and food for assemblages of fish.
History
The construction of artificial reefs is thousands of years old, although the historic usages were related to sea power rather than aquaculture. Ancient Persians blocked the mouth of the Tigris River to thwart Indian pirates by building an artificial reef,[1] and during the First Punic War the Romans built a reef across the mouth of the Carthaginian harbor in Sicily to trap the enemy ships within.[2] within and assist in driving the Carthaginians from the island.
The use of artificial reefs to increase fish yields or for algaculture also has a long history. During the 1600s reefs of building rubble and rocks were used in Japan to grow kelp,[3] while the earliest recorded construction of artificial reef in the United States is from 1830s when logs from huts were used off the coast of South Carolina to improve fishing.[4]
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.
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. 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.
Footnotes
- ^ Thomas Wayne Williams, A Case Study of Artificial Reef Decision-Making in the Florida Keys, Virginia Commonwealth University [1] Last accessed 20 December 2006
- ^ Ron Hess, Denis Rushworth, Michael V. Hynes, John E. Peters, Disposal Options for Ships, Chapter 5, "Reefing," Rand Corporation, [2] Last accessed 20 December 2006
- ^ Fisheries Technologies for Developing Countries, National Academies Press [3] Last accessed 20 December 2006
- ^ Gulf States Marine Fisheries Commission, GUIDELINES FOR MARINE ARTIFICIAL REEF MATERIALS, [4] Last accessed 20 December 2006
See also
- Osborne Reef, a failed artificial reef constructed of old tires