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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.
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.

Contents

History

Artificial surfing reefs

Mineral accretion

Environmental concerns

Footnotes

See also

External links

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]
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]
In the early 1970's, a series of thousands of disused vehicle tires were dumped off the coast of Fort Lauderdale, Florida to form an artificial reef. See Fort Lauderdale tire reef.

Artificial surfing reefs

Artificial surfing reefs have been created for surfing, coastal protection, habitat enhancement and coastal research. The world's first attempt was made in El Sugundo, Los Angles. The next attempt was at Cables Stations 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. Initially the structure produced some exceptional surfing conditions, however settlement of the geotexile sandbags, as well as huge differeces between the design and final reef shape means that the surfing has only been moderately improved.
In November 2005, ASR, a company that designs and builds patented artificial surfing reefs, began construction of a reef at Mount Maunganui, New Zealand. By that December, the site was already producing intermittent rideable yet far from perfect waves (www.mountreef.co.nz). The reef project gained consent to be built in 1998. The specific purpose of the reef from the resource consent application was:
"The purpose of the proposed reef is to enable University (Waikato) staff and post-graduate students to field test wave dynmaics on the artficial reef and in addition to monitoring the associated effects of the artficial reef on the coastal marine environemnt. It will also provide a facility for the afvanced education of those students undertaking this research. This is a five year research programme"
The following is also a extract from The Surfermag proving the Mount Reef is a huge success
http://surfermag.com/features/onlineexclusives/stfrancisrejuvenate/
"If Dr. Mead’s other projects are anything to go by, the surfers in St. Francis Bay are in for a real treat. “In good conditions the right will be a very good barreling wave,” he says, adding that, “If you look at the Mt. Reef project in New Zealand, once it was completed we’ve seen 50 meter long barrel rides on that wave. And we are looking at probably a 100 meter long wave in St. Francis, so there will be a section in that which will be a high quality wave for competent to expert surfers.” "
There has been a lot of media and internet discusion on the Mount reef, often critical. However, the origins of the reef project were as a coastal research experiment by the Coastal Marine Group of the University of Waikato.
Artificial surfing reefs typically resemble a "submerged breakwater", and proponents have suggested additional benefits beyond improving surfing conditions. Evidence is emerging that much more costly research is needed to be able to complete such surfing reefs and demonstrate the overall benefits mooted.
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 may not only create surfing opportunities but, by dissipating wave energy before it strikes the shore, create safer swimming areas and reduce coastal erosion. This is the demonstrated theory but it also has been shown that up to 70% of all artificial reefs have caused, not prevented erosion. Very competent, experienced and qualified coastal engineering advice that uses the well researched and universally accepted principles of coastal geomorphology is required to ensure a certain outcome. All requiring an exhausting costly process of interogation and testing by many of a greater range of expertise and qualification than has been thought up to now of being necessary.
A "wave" of enthusiasm fueled by a "mass debate" amongst those searching for a new stimulating product that appeals to surfers has seen the mooting of a artificial "artificial reef " industry. A hallmark being we are doing it because it "will be good for surfing when its finished". The idea of multi-purpose is added to rightly engage all of community but one has to realise that with such expenditure, results have to be overwhelmingly evident to all.
A compendium of newspaper reports in New Zealand is disturbing to say the least in the way that community money has been spent with the results being -"more money is needed." (taranki times).
Anyone thinking to spend a lot of money investigating this type of construction would do very well to be fully advised from all that is available in the published liturature, particularly well researched public newspaper articles that examine from a very unbiased point of view the fundamentals and progress of these projects. (Taranki Times)
Construction of artificial surfing reefs is a relatively new technology and, worldwide, nations as diverse as England , New Zealand, Sth Africa and USA are embarking upon planning and building their first projects. In South Africa a set of scandelous allegations were made in a publication noted for its type of journalism. The allegations however seemed to have some relevance to the way that things were happening too fast for the comfort of many. (noseweek #89,#91)
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. This however is a flawed argument as sea level rise of 3mm per year is taking us into uncharted territory and the very things that everybody want to see protected will be vulnerable due to 0.800x80=64 metres (Bruun rule) beach recession through to 2100. Whilst there is some distracting debate on the causes of Global Warming there is no doubt that ice is melting and sea level rising due to thermal expansion and melting ice. One glacier (jacobshavon) in Greenland is reported as being responsible for 4% of all sea level rise at the moment.
Conservationists and others concerned with environmental damage are correct though, in making sure that the process is not driven by commercial interests that have more regard to short term "self-gratification" than long term sustainable coastal assets/amentity. In this they are allied with the mainstream global coastal engineers and scientists. As usual, one has to question the motives of those that are intent on driving change quickly. That applys to any form of commerce and marketing thus the eternal term - "caviat emptor" .

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.

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.

Environmental concerns

The multi-million-dollar cleanup of Osborne Reef, a tire dump near Fort Lauderdale, Florida, has prompted questions about the risks of creating artificial reefs. In Florida, the tires posed a particular threat after breaking free from their restraints. The tires then migrated shoreward and ran into a living reef tract, climbed up its slope and killed everything in their path. According to The Ocean Conservancy, a Washington-based environmental group, the Florida reef may be an indication that the benefits of artificial reefs need to be re-examined. Jack Sobel, a senior scientist at the group, has said "There's little evidence that artificial reefs have a net benefit."Florida Raises Ill-Fated Artificial Reefs

Footnotes

1. Thomas Wayne Williams, ''A Case Study of Artificial Reef Decision-Making in the Florida Keys'', Virginia Commonwealth
University [1] Last accessed 20 December 2006
2. 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
3. ''Fisheries Technologies for Developing Countries'', National Academies Press [3] Last accessed 20 December 2006
4. 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

External links

★ Artificial Reef Society of British Columbia

★ Cables Beach surfing reef Perth, Australia

★ California Artificial Reef Enhancement Program (CARE)

★ The Reef Ball Foundation

★ Plans for Europe's First Artificial Reef Bournemouth UK

★ The Global Coral Reef Alliance

★ Biorock Process