Editing Artificial reef (section)

==Purposes==
[[File:Snorkeling Reef.JPG|thumb|Artificial reefs can help increase biodiversity in an area.]]
Artificial reef structures (ARs) have a variety of intended uses, ranging from the protection, enhancement and restoration of marine ecosystems<ref name="Bracho-Villavicencio"/> to the support of human activities like fishing, recreational diving and surfing.<ref name="Seaman"/> Artificial reefs can be used as active restoration tools to mitigate environmental damage and habitat loss, restore degraded ecosystems such as kelp forests and coral reefs, and promote biodiversity.<ref name="Bracho-Villavicencio"/><ref name="Seaman"/>
In fisheries management, artificial reefs may be intended to increase production of species of recreational and commercial interest,<ref name="Bracho-Villavicencio"/> enhance fishing yield,<ref name="Paxton"/> and support recreational, artisanal or commercial fisheries. They may be designed to protect [[benthic]] habitats from illegal trawling and restore fish stocks.<ref name="Seaman"/>
They may be placed to protect against coastal erosion.<ref name="Bracho-Villavicencio"/>
They may also be developed to support eco-tourism, promote recreational activities like scuba diving and surfing, and mitigate tourism pressure on corals.<ref name="Seaman"/>

The design and construction of an artificial reef may be very different depending on its proposed location and intended goals. A reef that is designed for one purpose may be unsuitable for others. Early attempts to create artificial reefs frequently failed, or at best, met with mixed results.<ref name="Blacka"/><ref name="Black"/><ref name="Baine"/> More recent reviews of work from 1990–2020 suggest that a correctly implemented artificial reef, designed to fit its target ecosystem, can be useful as a tool for the restoration of marine ecosystems. Reviewers call for better before/after and control comparisons of artificial and natural reefs, increased monitoring of reefs over their lifespan, and attention to the spatial orientation, complexity, and shape of reef substrate, among others.<ref name="Bracho-Villavicencio"/><ref name="Paxton">{{cite journal |last1=Paxton |first1=Avery B. |last2=Shertzer |first2=Kyle W. |last3=Bacheler |first3=Nathan M. |last4=Kellison |first4=G. Todd |last5=Riley |first5=Kenneth L. |last6=Taylor |first6=J. Christopher |title=Meta-Analysis Reveals Artificial Reefs Can Be Effective Tools for Fish Community Enhancement but Are Not One-Size-Fits-All |journal=Frontiers in Marine Science |date=7 May 2020 |volume=7 |doi=10.3389/fmars.2020.00282 |doi-access=free }}</ref><ref name="Seaman">{{cite journal |last1=Seaman |first1=William |title=Artificial habitats and the restoration of degraded marine ecosystems and fisheries |journal=Hydrobiologia |date=1 April 2007 |volume=580 |issue=1 |pages=143–155 |doi=10.1007/s10750-006-0457-9 |s2cid=2331696 |url=https://link.springer.com/article/10.1007/s10750-006-0457-9 |language=en |issn=1573-5117|url-access=subscription }}</ref>

===Artificial reef communities===
[[File:Sarcastic fringehead in plastic tube.JPG|thumb|Human-created objects provide hiding places for marine life, like this [[Sarcastic fringehead]]|alt=]]
On artificial reef structures intended for ecosystem enhancement, reef communities tend to develop in more or less predictable stages. First, where an ocean current encounters a vertical structure, it can create a [[plankton]]-rich upwelling that provides a reliable feeding spot for small fish such as [[sardine]]s and [[minnow]]s, which draw in [[pelagic]] [[predator]]s such as [[tuna]] and [[sharks]]. Next come creatures seeking protection from the ocean's lethal openness—hole and crevice dwellers such as [[grouper]], [[Lutjanidae|snapper]], [[squirrelfish]], [[eel]]s and [[triggerfish]]. Opportunistic predators such as [[Carangidae|jack]] and [[barracuda]] also appear. Over months and years the reef structure becomes encrusted with [[algae]], [[tunicates]], hard and soft [[coral]]s and [[sponge]]s.<ref name=ng211/>

[[File:Manta ray Biorock reef.jpg|thumb|right|alt=|A newly constructed [[electrified reef]] set up by [[Gili Eco Trust]] in [[Indonesia]].]]
An [[electrified reef]] is an artificial reef where a small low voltage electric charge is applied to a sub-sea metallic structures that causes [[limestone]] to precipitate onto a metal frame onto which [[planula|coral planulae]] can then attach and grow; the process also speeds up post-attachment growth.<ref name=GCRA>{{cite web|url=http://www.globalcoral.org/wp-content/uploads/2013/11/BIOROCK_TECHNOLOGY_july1114.pdf |publisher=Global Coral Reef Alliance |title=Biorock Benefits |date=July 2014 |access-date=5 April 2015}}</ref><ref name="Goldberg">{{cite news |last1=Goldberg |first1=Lee |title=Artificial Reefs Built from Sun and Seawater Will Protect the Isle of Man |url=https://www.electronicdesign.com/technologies/power/whitepaper/21243917/electronic-design-artificial-reefs-built-from-sun-and-seawater-will-protect-the-isle-of-man |work=Electronic Design |date=9 June 2022}}</ref>

3D printing technology has been employed both to create molds to optimize the environment for target species,<ref name="Ramos">{{cite book |last1=Ramos |first1=Jorge H. P. |title=Impact of Artificial Reefs on the Environment and Communities |date= 2022 |publisher=IGI Global |isbn=978-1-6684-2346-2 |url=https://books.google.com/books?id=0V1wEAAAQBAJ&pg=PA210 |language=en}}</ref><ref name="3Dreef">{{cite news |title=3D printing technology to aid coral growth in Maldives |url=https://maldivesindependent.com/environment/3d-printing-technology-to-aid-coral-growth-in-maldives-140073 |access-date=16 June 2023 |work=Maldives Independent |date=12 August 2018}}</ref> and to directly create cast ceramic and concrete artificial reefs. Work has also been done to develop environmentally friendly materials.<ref name="Koslow">{{cite news |last1=Koslow |first1=Tyler |title=3D Printing Used to Revive the Coral Reefs of Monaco |url=https://3dprintingindustry.com/news/3d-printing-used-to-revive-the-coral-reefs-ocean-eco-system-of-monaco-60807/ |work=3D Printing Industry |date=26 October 2015}}</ref> For example, Archireef has designed 3D-printed terracotta Reef Tiles, which are nontoxic, biodegradable, and have a pH-level that is compatible with coral. The tiles are small enough to be handled and installed by a diver. An installation in Hong Kong reported a 95 percent coral survival rate after three years, more than four times the survival rate of more traditional restoration methods.<ref name="Boyani">{{cite news |last1=Boyani |first1=Sally |title=These artificial reefs are combating coral degradation |url=https://wired.me/technology/artificial-reefs-coral-degradation/ |work=WIRED Middle East |date=11 September 2023}}</ref>

Restoration and mitigation actions on artificial reefs can include activities such as coral transplantation, larval resettlement, and gardening.<ref name="Bracho-Villavicencio">{{cite journal |last1=Bracho-Villavicencio |first1=Carolina |last2=Matthews-Cascon |first2=Helena |last3=Rossi |first3=Sergio |title=Artificial Reefs around the World: A Review of the State of the Art and a Meta-Analysis of Its Effectiveness for the Restoration of Marine Ecosystems |journal=Environments |date=July 2023 |volume=10 |issue=7 |pages=121 |doi=10.3390/environments10070121 |language=en |issn=2076-3298 |doi-access=free }}</ref>
For example, the [[Coral Restoration Foundation]] in the Florida Keys raises keystone species such as elkhorn ([[Acropora palmata]]) and staghorn ([[Acropora cervicornis]]) in coral tree nurseries and replants the corals onto degrading coral reefs.<ref name="Roberson">{{cite news |last1=Roberson |first1=Julia |title=Restoring Endangered Coral Reefs |url=https://oceanconservancy.org/blog/2016/07/28/restoring-endangered-coral-reefs-2/ |work=Ocean Conservancy |date=July 28, 2016}}</ref> Application of such technologies to artificial reefs could help to restore marine ecosystems. A 2023 review article states: "The implementation of artificial reefs to restore marine ecosystems can be well done, investing resources in studies specifically aimed at determining the appropriate characteristics of ARs for each location."<ref name="Bracho-Villavicencio"/>

=== Carbon sequestration ===
[[File:Artificialreef.JPG|thumb|Constructing an artificial reef using [[Concrete masonry unit|concrete breeze blocks]]<ref>{{cite web | last=Aspinall | first=Richard | title=From concrete to coral: breeze blocks make a splash regenerating reefs | website=The Guardian | date=2016-09-20 | url=http://www.theguardian.com/science/blog/2016/sep/20/from-concrete-to-coral-breeze-blocks-make-a-splash-regenerating-reefs | access-date=2021-01-04}}</ref>]]
There is interest in the possibility that artificial reefs can be used to support [[carbon sequestration]] and counter [[climate change]]. Coastal vegetation ecosystems (mangrove, salt marsh, and seagrass), algal beds, and phytoplankton have been identified as potential [[carbon sinks]]. It is hoped that increasing biomass at artificial reefs can provide another form of [[blue carbon]] storage.<ref name="Shu"/><ref name="Jiang">{{cite news |last1=Jiang |first1=Yifan |title=What makes China's 'blue carbon' plans different? |url=https://chinadialogueocean.net/en/fisheries/18729-what-makes-chinas-blue-carbon-plans-different/ |work=China Dialogue Ocean |date=23 September 2021}}</ref>

RGV Reef, a 1,650-acre artificial reef created in 2017 in the Gulf of Mexico off the coast of Texas, is being studied to assess its potential for carbon capture.<ref name="Curtis">{{cite web |title=Carbon Capture Research Begins at Largest Artificial Reef in Texas |url=https://rgvreef.org/first-of-its-kind-study-could-be-a-gamechanger-in-dealing-with-climate-changer/ |website=RGV Reef|date= October 19, 2022 }}</ref> Another study area is located off Juehua Island in the [[Bohai Sea]]. Biological, physical, social and technological factors must all be considered in calculating carbon capture flow in aquatic systems. Near Juehua Island, M-shaped artificial reefs improved hydrodynamic conditions for creating a carbon sink, but local marine species had limited availability. Development of active marine management strategies and the introduction of appropriate biological species were suggested as ways to increase carbon capture potential.<ref name="Shu">{{cite journal |last1=Shu |first1=Anping |last2=Zhang |first2=Ziru |last3=Wang |first3=Le |last4=Sun |first4=Tao |last5=Yang |first5=Wei |last6=Zhu |first6=Jiapin |last7=Qin |first7=Jiping |last8=Zhu |first8=Fuyang |title=Effects of typical artificial reefs on hydrodynamic characteristics and carbon sequestration potential in the offshore of Juehua Island, Bohai Sea |journal=Frontiers in Environmental Science |date=2022 |volume=10 |doi=10.3389/fenvs.2022.979930 |issn=2296-665X |doi-access=free }}</ref>

In the Caribbean, researchers have found that the placement of [[breeze blocks]] as artificial reefs near tropical [[seagrass meadows]] can create a positive feedback loop. The reef structures attracted fish by providing shelter, and the fish in turn fertilized the seagrass and increased its productivity, providing both food and shelter. The combination of seagrass and reef structures provided added protection from fish nets as well as increasing biomass in the seagrass meadow.<ref name="Ashworth">{{cite web |last1=Ashworth |first1=James |title=Artificial reefs in seagrass meadows could help protect against climate change |website=phys.org |date=July 26, 2023 |url=https://phys.org/news/2023-07-artificial-reefs-seagrass-meadows-climate.html |language=en}}</ref><ref name="Esquivel">{{cite journal |last1=Esquivel |first1=Kenzo E. |last2=Hesselbarth |first2=Maximilian H. K. |last3=Allgeier |first3=Jacob E. |title=Mechanistic support for increased primary production around artificial reefs |journal=Ecological Applications |date=September 2022 |volume=32 |issue=6 |pages=e2617 |doi=10.1002/eap.2617 |pmid=35368128 |bibcode=2022EcoAp..32E2617E |hdl=2027.42/174782 |s2cid=247937506 |url=https://doi.org/10.1002/eap.2617 |language=en |issn=1051-0761|hdl-access=free }}</ref><ref name="Andskog">{{cite journal |last1=Andskog |first1=Mona A. |last2=Layman |first2=Craig |last3=Allgeier |first3=Jacob E. |title=Seagrass production around artificial reefs is resistant to human stressors |journal=Proceedings of the Royal Society B: Biological Sciences |date=26 July 2023 |volume=290 |issue=2003 |doi=10.1098/rspb.2023.0803|pmid=37491960 |pmc=10369039 }}</ref> Estimates suggest that Caribbean seagrass beds can provide substantial pools for global carbon.<ref name="Shayka">{{cite journal |last1=Shayka |first1=Bridget F. |last2=Hesselbarth |first2=Maximilian H. K. |last3=Schill |first3=Steven R. |last4=Currie |first4=William S. |last5=Allgeier |first5=Jacob E. |title=The natural capital of seagrass beds in the Caribbean: evaluating their ecosystem services and blue carbon trade potential |journal=Biology Letters |date=June 2023 |volume=19 |issue=6 |doi=10.1098/rsbl.2023.0075|pmid=37340807 |s2cid=259204507 |pmc=10282569 }}</ref>

===Erosion prevention===
[[File:Oyster reef in the bay made from oyster castles, about 60% complete (22620795960).jpg|thumb|Oyster castle reef, Gandy's Beach shoreline protection project<ref name="Bredes">{{cite journal |last1=Bredes |first1=Amy L. |last2=Miller |first2=Jon K. |last3=Kerr |first3=Laura |last4=Brown |first4=Dana Rose |title=Observations of Wave Height Amplification Behind an Oyster Castle Breakwater System in a High-Energy Environment: Gandys Beach, NJ |journal=Frontiers in Built Environment |date=2022 |volume=8 |doi=10.3389/fbuil.2022.884795 |issn=2297-3362 |doi-access=free }}</ref>]]

Some artificial reefs are used to prevent [[coastal erosion]].<ref name="Brandon">{{cite magazine |last1=Brandon |first1=Elissaveta M. |title=To Fight Coastal Erosion, Design a Bespoke Artificial Reef |url=https://www.wired.com/story/reefy-modular-reef-costal-erosion/ |magazine=Wired |date=March 28, 2023}}</ref><ref name="Cusick">{{cite news |last1=Cusick |first1=Daniel |title='Reef Balls' Gain Traction for Shoreline Protection |url=https://www.scientificamerican.com/article/reef-balls-gain-traction-for-shoreline-protection/ |work=Scientific American |date=May 17, 2022 |language=en}}</ref>
Geometric and hydrodynamic properties of reefs are particularly important in determining their ability to mitigate coastal erosion.<ref name="Escudero">{{cite journal |last1=Escudero |first1=Mireille |last2=Reguero |first2=Borja G. |last3=Mendoza |first3=Edgar |last4=Secaira |first4=Fernando |last5=Silva |first5=Rodolfo |title=Coral Reef Geometry and Hydrodynamics in Beach Erosion Control in North Quintana Roo, Mexico |journal=Frontiers in Marine Science |date=2021 |volume=8 |doi=10.3389/fmars.2021.684732 |issn=2296-7745 |doi-access=free }}</ref><ref name="Kim">{{cite journal |last1=Kim |first1=Taeyoon |last2=Baek |first2=Seungil |last3=Kwon |first3=Yongju |last4=Lee |first4=Jooyong |last5=Cha |first5=Sung Min |last6=Kwon |first6=Soonchul |title=Improved Coastal Erosion Prevention Using a Hybrid Method with an Artificial Coral Reef: Large-Scale 3D Hydraulic Experiment |journal=Water |date=October 2020 |volume=12 |issue=10 |pages=2801 |doi=10.3390/w12102801 |language=en |issn=2073-4441 |doi-access=free }}</ref>
Artificial reefs to prevent erosion can be designed to act in multiple ways. Some are designed to force [[water waves|waves]] to deposit their energy offshore rather than directly on the coastline.

Other reefs are designed to hold [[sediment]] on beaches by trapping the sediment. Reefs are generally custom-designed for each unique zone.<ref name="Morang">{{cite journal |last1=Morang |first1=Andrew |last2=Waters |first2=Jeffrey P. |last3=Stauble |first3=Donald K. |title=Performance of Submerged Prefabricated Structures to Improve Sand Retention at Beach Nourishment Projects |journal=Journal of Coastal Research |date=1 November 2014 |volume=30 |issue=6 |pages=1140–1156 |doi=10.2112/JCOASTRES-D-13-00137.1 |s2cid=128833800 |url=https://doi.org/10.2112/JCOASTRES-D-13-00137.1|url-access=subscription }}</ref><ref name="Blacka"/><ref name="Black"/> Some are designed to support customizable habitat for local target species as well.<ref name="Brandon"/>

===Artificial surfing reefs===
{{Main|Multi-purpose reef}}
[[File:Mega sand container.jpg|thumb|Mega sand container with a by then unprecedented size of 20 m (length) × 4.80 m (diameter) as presented in 1999 on an open day for the public at the construction site for the Gold Coast artificial reef.]]
Some types of artificial reefs, such as surfing reefs, do not have ecosystem enhancement as a major goal. Hoppy's Reef was an early but unsuccessful attempt to create a surfing reef, off [[Hermosa Beach, California]] (1971).<ref>{{cite web |title=Hoppy's Reef |url=https://raisedwaterresearch.com/spot/artificial-reef/us/california/hoppys-reef/ |website=Raised Waves}}</ref> Artificial surfing reefs have been created at
Cable Station Reef ([[Perth]], [[Western Australia]], 1999)<ref name="Bancroft">{{cite book |last1=Bancroft |first1=Stacey |title=Performance Monitoring of the Cable Station Artificial Surfing Reef |date=1999 |publisher=The University of Western Australia |url=http://joas.free.fr/studies/bei/g2s/bancroft_thesis.pdf}}</ref><ref name="BMT">{{cite web |author=BMT Western Australia Pty Ltd |title=Middleton Beach Artificial Surf Reef Environmental Impact Assessment |date=14 September 2018 |url=https://www.epa.wa.gov.au/sites/default/files/Referral_Documentation/Environmental%20Impact%20Assessment_0.pdf |pages=10–17 }}</ref><ref>{{cite web |title=Cables Reef |url=https://raisedwaterresearch.com/spot/artificial-reef/australia/western-australia/cables-reef/ |website=Raised Waves}}</ref>
[[Narrow Neck, Queensland|Narrowneck Reef]] ([[Gold Coast, Queensland]], 2000)<ref name="Jackson">{{cite journal |last1=Jackson |first1=Angus |last2=Tomlinson |first2=Rodger |last3=Corbett |first3=Bobbie |last4=Strauss |first4=Darrell |title=Long Term Performance of a Submerged Coastal Control Structure: A Case Study of the Narrowneck Multi-Functional Artificial Reef |journal=Coastal Engineering Proceedings |date=14 December 2012 |volume=1 |issue=33 |pages=54 |doi=10.9753/icce.v33.structures.54 |url=https://icce-ojs-tamu.tdl.org/icce/article/view/6956 |language=en |issn=2156-1028|doi-access=free }}</ref><ref name="Black">{{cite journal |last1=Black |first1=Kerry |title=Artificial Surfing Reefs for Erosion Control and Amenity: Theory and Application |journal=Journal of Coastal Research |date=2001 |pages=1–14 |jstor=25736269 |url=https://www.jstor.org/stable/25736269 |issn=0749-0208}}</ref><ref>{{cite web |title=Narrowneck |url=https://raisedwaterresearch.com/spot/artificial-reef/australia/queensland/narrowneck/ |website=Raised Water}}</ref>
[[Chevron Reef]], also known as Pratte's Reef ([[El Segundo, California]], 2000, removed 2008).<ref name="Chevron">{{cite web |title=Pratte's Reef |url=https://raisedwaterresearch.com/spot/artificial-reef/us/california/prattes-reef/ |website=Raised Water |access-date=15 August 2023}}</ref><ref name="Leidersdorf">{{cite journal |last1=Leidersdorf |first1=Craig B. |last2=Richmond |first2=Brady |last3=Nelsen |first3=Chad E. |title=The Life and Death of North America's First Man-Made Surfing Reef |journal=Conference on Coastal Engineering Practice 2011 |date=30 August 2011 |pages=212–225 |doi=10.1061/41190(422)18|isbn=9780784411902 }}</ref>
and [[Boscombe Surf Reef]] (Dorset, England, 2009, closed 2011).<ref name="Rendle">{{cite book |last1=Rendle |first1=Emma Jane |title=The Environmental, Social and Economic Impacts of an Artificial Surf Reef – The UK Experience |date=2015 |publisher=Plymouth University |url=https://www.researchgate.net/publication/308695589}}</ref>

The construction of artificial surfing reefs has involved a variety of structures including concrete, rock, and geotextile bags filled with sand. Life expectancy of such materials varies widely. Geotextile structures have been found to degrade more quickly than anticipated under ocean conditions.<ref name="Borrero">{{cite journal |last1=Borrero |first1=Jose Carlos |last2=Mead |first2=Shaw T. |last3=Moores |first3=Andrew |title=Stability considerations and case studies of submerged structures constructed from large, sand filled, geotextile containers |journal=Coastal Engineering Proceedings |date=2010 |volume=1 |issue=32 |pages=60 |doi=10.9753/icce.v32.structures.60 |url=https://icce-ojs-tamu.tdl.org/icce/article/view/1172 |language=en |issn=2156-1028|doi-access=free }}</ref> Some analysts argue that they are fundamentally flawed.<ref name="Gegan">{{cite news |last1=Gegan |first1=Cooper |title=Why Have Most Artificial Reefs Never Really Worked? |url=https://www.theinertia.com/surf/why-have-most-artificial-reefs-never-really-worked/ |work=The Inertia |date=26 May 2023}}</ref> While use of stone blocks has raised concerns about possible safety hazards for surfers,<ref name="Blacka"/> it has been suggested that using stone may be structurally preferable.<ref name="Gegan"/>

In addition to improving surfing conditions, objectives of building an artificial surfing reef or [[multi-purpose reef]] have included stabilizing beachfront, coastal protection and coastal research. Habitat enhancement is sometimes considered as well.<ref name="Loomis">{{cite book |last1=Loomis |first1=Michael |title=Review of artificial surfing reefs and their effectiveness as recreation areas, marine habitats and erosion control devices |date=2003 |publisher=Nova Southeastern University Oceanographic Center |url=https://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&doi=094e801343153e9107f2c522e6e21b242f1bcfba}}</ref>
<ref name="Black"/> However, different materials are preferred for the construction of artificial surfing reefs and the development of reefs for ecosystem enhancement.<ref name="Blacka"/>

A 2012 review of artificial reefs indicated that artificial surfing reefs performed poorly in terms of their intended purpose and successfulness, rarely achieving primary or secondary objectives of "Surfing Enhancement".<ref name="Blacka"/>
For Pratte's reef, woven polypropylene bags were used in a first phase, and woven polyester bags in a second stage<ref name="Blacka"/> filling an area of approximately 1600 cubic meters.<ref name="redux">{{cite web |title=Pratt's Reef Redux |url=https://www.surfline.com/templates/article_html.cfm?n=6&id=20360&p=1 |website=Surfline}}</ref> The area involved was too small to be successful. Even after doubling the original budget, the materials used degraded rapidly, and the resulting remediation cost more than the installation.<ref name="Blacka"/>  Mount Reef at [[Mount Maunganui]] in New Zealand used more durable containers and a volume of around 6,000 cubic meters of sand. Although somewhat successful in creating waves, it too deteriorated and had to be removed.<ref name="redux"/><ref name="Maunganui">{{cite web |title=Mount Maunganui |url=https://raisedwaterresearch.com/spot/artificial-reef/new-zealand/north-island/mount-maunganui/ |website=Raised Water}}</ref> The Narrowneck Reef was much larger, at least 60,000 cubic meters, and was somewhat successful in its primary objective of shoreline stabilization, but less so in improving surfing.<ref name="Blacka"/>

Several projects in Australia have used stone to augment existing sites.<ref name="Gegan"/> Cable Station Reef added limestone rocks to an existing reef.<ref>{{cite news |title=Cables Reef Study |url=https://www.surfer.com/features/cablesreef |work=Surfer |date=Oct 11, 2010 |language=en}}</ref> At Burkitts Reef on the Woongarra Coast, large boulders were broken down to fill gaps in an existing boulder and gravel reef.<ref>{{cite web |title=Burkitts Reef |url=https://raisedwaterresearch.com/spot/artificial-reef/australia/queensland/burkitts-reef/ |website=Raised Water}}</ref> At Palm Beach Reef on the Gold Coast of Australia, stone boulders were used to adapt the shape of an existing breakwater and protect added sand.<ref>{{cite web |title=Palm Beach Reef |url=https://raisedwaterresearch.com/spot/artificial-reef/australia/queensland/palm-beach-reef/ |website=Raised Water}}</ref> Another artificial stone reef, located in [[Borth]], [[Wales]], was designed primarily for coastal protection.<ref name="BMT"/><ref name="Gegan"/><ref name="Borth">{{cite news |title=Borth coastal defence and surfing reef opens |url=https://www.bbc.com/news/uk-wales-mid-wales-17286596 |work=BBC News |date=8 March 2012}}</ref>

A major issue is that changes occurring in the lee of submerged reef structures are complex, not well understood, and difficult to model and predict. As of 2012, existing prototypes have been characterized as "trial or experimental only", and predictive models have not achieved "accuracy or reliability", although it has been hoped that "ongoing construction and monitoring of submerged constructed reefs (SCRs) will result in a better understanding of the processes and refined methods for predicting shoreline response".<ref name="Blacka">{{cite book |last1=Blacka |first1=M J |last2=Shand |first2=T D |last3=Carley |first3=J T |last4=Mariani |first4=A |title=A Review of Artificial Reefs for Coastal Protection in NSW WRL Technical Report 2012/08 June 2013 |date=2013 |publisher=Water Research Laboratory |location=Manly Vale, NSW |url=https://www.wrl.unsw.edu.au/sites/wrl/files/uploads/Publications/WRL-TR2012-08-Final-June-Artificial-Reefs.pdf}}</ref> Even in cases which were initially seen as successful, subsequent changes and deterioration of structures have led to poor outcomes.<ref name="Blacka"/>

Surfers' expectations of artificial reefs, particularly "an expectation by the general public of consistent, quality waves during a wide range of environmental conditions" have also led to disappointment.<ref name="Blacka"/><ref name="Mull">{{cite news |last1=Mull |first1=Jeff |title=Pipe Dreams |url=https://www.surfer.com/features/pipe-dreams-artificial-reef |work=Surfer |date=June 2, 2014 |language=en}}</ref>
Surfing science is a relatively new field.<ref name="Scarfe">{{cite journal |last1=Scarfe |first1=Bradley E. |last2=Healy |first2=Terry R. |last3=Rennie |first3=Hamish G. |title=Research-Based Surfing Literature for Coastal Management and the Science of Surfing – A Review |journal=Journal of Coastal Research |date=May 2009 |volume=253 |pages=539–557 |doi=10.2112/07-0958.1 |language=en |issn=0749-0208|doi-access=free }}</ref>
The ability to achieve consistency of surfing waves in a range of conditions in natural environments generally requires wave pre-conditioning or large scale breaking
features or both. The scale of early artificial surfing reefs was too small to achieve such consistency.<ref name="Blacka"/><ref name="Mead">{{cite book |last1=Mead |first1=Shaw |last2=Borrero |first2=Jose |chapter=Surf science and multi-purpose reefs |title=Marine and Coastal Resource Management |date=27 September 2017 |pages=288–311 |doi=10.4324/9780203127087-16|isbn=9780203127087 }}</ref>

===Recreational dive sites===
[[File:Musa 3 (13752182883).jpg| thumb | right | Statue by [[Jason deCaires Taylor]], [[Museo Subacuático de Arte]] ]]
[[File:EDP ArtReef by Vhils, Lisboa 01.jpg|thumb|right|Artwork for the creation of Artreef, Albufeira]]
Thousands of popular [[wreck diving]] sites throughout the world are shipwrecks sunk as artificial reefs.<ref>{{cite web|title=Wrecks and Obstructions Database|url=http://www.nauticalcharts.noaa.gov/hsd/wrecks_and_obstructions.html|website=NOAA|access-date=2016-03-08|archive-date=2021-07-23|archive-url=https://web.archive.org/web/20210723033310/https://www.nauticalcharts.noaa.gov/hsd/wrecks_and_obstructions.html|url-status=dead}}</ref> Some of these wrecks were [[Sinking ships for wreck diving sites|sunk deliberately to attract divers]]. The {{USS|Spiegel Grove}} and {{USS|Oriskany|CV-34|6}} in [[Florida]], {{USS|Indra|ARL-37|6}} and {{USS|Aeolus|ARC-3|6}} in North Carolina, and {{ship||Bianca C.|ship|2}} in [[Grenada]] draw thousands of divers annually.<ref>{{cite web|last1=Gerken|first1=Michael|title=Top 10 Wreck Dives of North Carolina|url=http://www.scubadiving.com/photos/top-10-wreck-dives-north-carolina|website=Scuba Diving|access-date=8 March 2016}}</ref>

In other areas, dive sites have been developed in collaboration with artists as artworks.
For example, the [[Museo Subacuático de Arte]] in the [[Cancún National Marine Park]] contains hundreds of life-size statues, offering divers an alternative to sensitive coral reefs in the region. Each statue is made from a plaster mold of a living person, using a PH neutral "marine cement", by [[Jason deCaires Taylor]].<ref name="Perdomo">{{cite news |last1=Perdomo |first1=Gabriela |title=Mexico's underwater art museum sinks sculptures beneath the sea |url=https://macleans.ca/culture/is-art-better-down-where-its-wetter/ |access-date=6 July 2023 |work=Macleans |date=6 March 2012}}</ref>

In Lisbon, 13 artworks by Alexandre Farto ([[Vhils]]) will be placed in an artificial reef off the coast of [[Albufeira]] as of June 2024. The works are made from parts of decommissioned power stations.<ref name="Romano">{{cite news |last1=Romano |first1=Verónica |title=Taking the plunge to see Portugal's unique underwater exhibition |url=https://www.euronews.com/culture/2023/03/26/taking-the-plunge-to-see-art-a-unique-underwater-exhibition-in-portugal |access-date=6 July 2023 |work=euronews |date=26 March 2023 |language=en}}</ref>

A study in Barbados showed a marked variation in diver satisfaction with artificial reef diving experiences. Novice divers tended to be more satisfied than more experienced divers, who had a strong preference for natural reefs and large shipwrecks.
<ref>{{cite journal|title=The Relationship between Diver Experience Levels and Perceptions of Attractiveness of Artificial Reefs – Examination of a Potential Management Tool |first1=Anne E. |last1=Kirkbride-Smith |first2=Philip M. |last2=Wheeler |first3=Magnus L. |last3=Johnson |date=23 July 2013 |doi=10.1371/journal.pone.0068899 |journal=PLOS ONE |volume=8 |issue=7 |pages=e68899 |pmid=23894372 |pmc=3720904 |bibcode=2013PLoSO...868899K |doi-access=free }}</ref>