More than any other species humans have landscaped the Earth, altering it to suit our needs. What may be less obvious is we are also landscaping the oceans – and have been doing so for a very long time. Historical artefacts suggest that artisanal fisheries in the Mediterranean Sea and Australia were utilizing discarded rocks as fish aggregation devices around 3,000 years ago. The first recorded modern artificial reef came from Japan 500 years ago, where rubble and rocks were used to grow kelp. 180 years ago, logs were placed in coastal waters around South Carolina as fish aggregation devices. Today artificial reefs can be found throughout the world, very often placed – if not created – to fill a specific purpose. At Australia’s Cable Station Beach an artificial surf reef created by modifying an existing limestone reef with granite rock, has resulted in surfable waves an average of 130 days of the year. Artist Jason deCaires Taylor created some 450 cement-cast figures for The Silent Evolution at the underwater museum MUSA (Museo Subacuático de Arte) off Cancún Mexico, with the idea of drawing people away from fragile reefs. Off the south-eastern Iberian Peninsula, anti-trawling reefs have been placed around sensitive seagrass beds to reduce the impact of illegal bottom trawling. To tackle the problem of coastal erosion in Portugal, researchers have suggested that artificial reefs designed to either dissipate wave energy or rotate waves to reduce longshore currents could prove useful tools.
Artificial reefs come in a variety of shapes, sizes, and materials. Reef restoration projects typically use limestone boulders or concrete/ceramic structures, often textured, shaped, and interlaced with cavities in such a way as to provide a heterogeneous reef-scape to mimic the preferred habitat of a number of different species. Not all reefs are purpose-built. Florida USA is home to the two largest artificial reefs in the world, both created from the sinking of decommissioned vessels (USS Oriskany and USHS Vandenburg). Rigs-to-reefs programs convert defunct offshore oil and gas platforms into artificial reefs for conservation and fishery purposes as well as reduce rig decommissioning costs. In well-managed jurisdictions, placing artificial reefs is no simple task. Many factors need to be taken into account, such as the stability of the environment they are to be placed in, and the impact of the reef to the physical processes as well as the organisms residing in the area in which it is to be placed, and of course any human uses of the area…
The full article was published in – and can be read in – The Marine Professional, a publication of the Institute of Marine Engineering, Science & Technology (IMarEST).
Image: Coral Will Not Be Denied. Credit Oblivious Dude/Flickr (CC BY-NC-ND 2.0)