There are currently more than 7,500 offshore oil platforms actively probing the earth’s crust for black gold. Their relatively minimal appearance at the surface belies the shear magnitude of human construction beneath the waves. Oil platforms are among the world’s tallest man-made structures. Compliant tower platforms reach up to 900 meters in depth (in contrast, the tallest building is 828 meters). these rigs are not permanent structures. As the wells run dry and sea water corrodes steel jackets, the wells are capped and rigs decommissioned. At least 6500 offshore platforms are slated for decommission by 2025, which begs the question, what do we do with inactive oil platforms?
The now defunct Minerals Management Service devised a seemingly ideal solution; one that would save the oil companies huge amounts of money, pass responsibility of the decaying rigs onto state and federal governments, and create huge amounts of habitat for deep-sea organisms. Instead of removing oil platforms, the Rigs-to-reefs program would knock them over, or leave them standing where they are, creating artificial reefs. Everybody wins, especially oil companies.
On paper, the principles behind using oil platforms as artificial reefs appears sound. We know that fish aggregate around artificial reefs, that hard substrate will be rapidly colonized by invertebrate communities, and that the communities that accumulate around active rigs can be rich in biodiversity. With so many rigs going offline in the next 15 years, it’s hard to argue against their conversion into reef habitat. In the deep Gulf of Mexico, loss of hard substrate has disrupted community dynamics, and the addition of new structures might provide valuable stepping stones for dispersal.
Other artificial reef project have been successful. The Alabama coastline has nearly 20,000 artificial reefs. These reefs, mostly made of concrete, but also old ships, discarded construction equipment, and industrial detritus aggregate fish and have been cited as a major component in snapper and grouper recovery. Artificial reefs are not all good news. Although they provide a boost to fish habitat and subsequent income from fisheries and tourism (including fishing and diving), they also alter community composition and fisheries induced selection.
All of this is compounded by the fact that oil platforms are not pristine environments. While the most obvious and imminent ecologic disruption comes from leaking oil, as we saw during the Deep Water Horizon Disaster that began last April, long term ecosystem damage in the area immediately surrounding the rig is primarily due to the leaching of heavy metals, such as those found in drilling mud, and anti-fouling chemicals. This means that for an artificial reef to be effective, the structure must first be removed from the water and decontaminated, a prospect that will remove the economic benefit to the oil company.
In Louisiana and Texas, inshore rigs-to-reefs programs transfer responsibility for management to the state, absolving oil companies of the heavy cost of clean-up and leaving state tax-payers with the bill. Only 100 rigs have been converted under this program, which is notably unpopular among most stakeholders, oil companies excepted.
There are further questions regarding whether these reefs actually boost fish populations, or act as fish aggregating devices, leaving populations open to continuous fisheries pressure.
The idea to use old oil platforms as artificial reefs is not a bad one, and I can certainly see scenarios in which it could be done effectively. In the current climate of offshore exploration, where accountability is low and shirking responsibility is the name of the game, providing an additional avenue for oil companies to cut corners seems ill advised. Once sunk, there is no practical proposal for long term monitoring and no plan for clean-up if it turns out that these reefs are harmful to the native ecosystem. The deep Gulf of Mexico has always be hard surface limited, and the ecosystem benefits of a rig-reef are low compared to the potential for damage.
If you interested in the type of science/industry cooperative efforts that could provide the rigorous, robust data sets that would be needed to properly evaluate a rig-to-reef program, check out the SERPENT Project.
Macreadie, P., Fowler, A., & Booth, D. (2011). Rigs-to-reefs: will the deep sea benefit from artificial habitat? Frontiers in Ecology and the Environment DOI: 10.1890/100112
Mason B (2003). Doubts swirl around plan to use rigs as reefs. Nature, 425 (6961) PMID: 14586435