Artificial reef

An opportunity artificial reef is built from objects that were intended for other purposes,[4] such as sinking oil rigs (through the Rigs-to-Reefs program), scuttling ships, or by deploying rubble or construction debris.

Green artificial reefs incorporate renewable and organic materials such as vegetable fibres and seashells to improve sustainability and reduce energy consumption, pollution, and greenhouse gas emissions.

Artificial reefs generally provide hard surfaces where algae and invertebrates such as barnacles, corals, and oysters attach and spaces where different sizes of fishes can hide.

More recently, refuse such as old refrigerators, shopping carts, ditched cars and out-of-service vending machines replaced the logs in ad hoc reefs.

Officially sanctioned projects have incorporated decommissioned ships, subway cars, battle tanks, armored personnel carriers, oil drilling rigs and beehive-like reef balls.

[21][22] Artificial reef structures (ARs) have a variety of intended uses, ranging from the protection, enhancement and restoration of marine ecosystems[6] to the support of human activities like fishing, recreational diving and surfing.

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 sardines and minnows, which draw in pelagic predators such as tuna and sharks.

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.

Coastal vegetation ecosystems (mangrove, salt marsh, and seagrass), algal beds, and phytoplankton have been identified as potential carbon sinks.

Near Juehua Island, M-shaped artificial reefs improved hydrodynamic conditions for creating a carbon sink, but local marine species had limited availability.

[35] 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.

[56] The construction of artificial surfing reefs has involved a variety of structures including concrete, rock, and geotextile bags filled with sand.

[63] 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.

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.

[83] In 2008, at Palmyra Atoll south of Hawaii, iron leaching from a shipwreck led to increases in algae and a sea anemone called a corallimorph, smothering existing coral to create a "black reef".

[88] Some researchers, such as James Bohnsack, a biologist with the National Marine Fisheries Service (NMFS), have argued that the amount of biomass found on artificial reefs is attracted away from nearby areas rather than developing there.

[92] On the Osborne Reef off the coast of Fort Lauderdale, Florida, storms broke the nylon straps holding the original tire bundles together.

[110][111][112] In the United States, best practices for preparing vessels for use in artificial reefs include assuming that divers may access all locations, removing potential hazards to divers, removing all polluting or toxic materials, including PCBs (in compliance with applicable water quality standards for class III ocean waters), and clearing debris and floatables.

Cremated remains are mixed with concrete and either encased in columns or molded into sea-star, brain-coral, 15 feet (4.6 m) castings of lions or other shapes before entering the water.

[120] The world's largest artificial reef was created by sinking of the 44,000 ton aircraft carrier USS Oriskany off the coast of Pensacola, Florida, in 2006.

[126] In 1970, the Georgia Department of Natural Resources (DNR) began building a network of artificial reefs to provide habitats for game fish.

It contains a variety of different debris, including New York City subway cars, M-60 tanks formerly used by the United States Army, and concrete culverts.

[130] She is lying on her starboard side at a depth of 160 ft (49 m)[131] USCGC Spar was scuttled in June 2004 by Captain Tim Mullane in 108 feet (33 m) of water, 30 miles (48 km) off Morehead City, North Carolina, where she serves as an artificial reef.

[135] In the late 2000s, the New York City Transit Authority decided to retire an outdated fleet of subway cars to make room for new R142 and R142A trains.

Each car was stripped, decontaminated, loaded on a barge, and sunk in the Atlantic Ocean off the coast of Delaware, Virginia, South Carolina, Georgia, and Florida.

In September 2007, the NYCTA approved a further contract with Weeks Marine worth $6 million, to send 1,600 of its retired subway cars to be used as artificial reefs.

[145][146] On Curaçao, Secore International has created 12 artificial reefs using the cost-effective technique with small tetrapod-shaped concrete structures, seeded with coral larvae.

[158][159][160] In 2013, more than 70 concrete blocks were sunk by the government of Gibraltar (independent of Eric Shaw's trust), each one square meter in size with protruding metal bars.

The diving centre Temple Adventures built a Temple-shaped structure in 2015 at a depth of 18 metres (59 ft), using recycled materials such as concrete, rocks, trees, palms, and iron bars.

[172] Following a gas explosion that occurred on 3 February 1995, the Libyan-owned motor tanker Um El Faroud was scuttled off the coast of Malta as an artificial reef.