Relics to Reefs: Taking Recycling to New Depths

The bridge of the U.S. Coast Guard Cutter Duane intentionally sunk in 1987 off Key Largo to create an artificial reef at 120 feet. Credit: David Doubilet

Subway cars, shipping vessels, oil rigs, tanks, cement pipes, and piles of volcanic rock. These are some of the odd materials that rest on the sea floor, put there deliberately to serve as artificial reefs. The goal of these massive efforts, which included the sinking of the USNS Gen. Hoyt S. Vandenberg in 2009, is to turn these bare metal and stone surfaces into colorful reefs, full of fish, algae and other underwater creatures. And it works – if you sink it, they will come. But why?

Space is limited

While the ocean is huge, hard surfaces in the photic zone (where sufficient light can penetrate to support photosynthesis) are rare. Like a new apartment building in Manhattan, open space is colonized almost as soon as it becomes available. Algae and the larvae of sessile (fixed in place) invertebrates like barnacles, bryzoans, and sponges settle in virtually overnight. Larger crustaceans follow, as do fish, making the reefs popular sites for diving and fishing. Enhanced sport fishing is the primary reason that most coastal states cite for the creation of artificial reefs. In some areas, reefs are used as a mitigation measures, to make up for damage caused by power companies onshore or oil drilling. Proponents say that the man-made structures provide the means to bring back depleted fish stocks or encourage the growth of algae forests and groves.

The Attraction-Production Debate

There’s debate in the research community about whether artificial reefs create new habitat or lure fish from natural reefs. It’s an open question, but many states and the federal government have been encouraging reef development and deployment for decades, with little sign of slowing down. Some scientists fear that trash disposal, fishing, and diving interests may be superseding environmental considerations, and could cause harm in the long run. A 1997 review of the literature on artificial reefs found numerous studies that showed that reef construction could have negative effects on natural reef fish populations, and few that demonstrated that reefs increase fish productivity. Some research suggests that reefs only enhance fish production where habitat is limited. This could be true in places where it has been impact or destroyed by human activities. But overfishing is a more common cause of plummeting fish populations, and concentrating fish in smaller areas only makes them easier to catch.

The largest artificial reef in U.S. waters lies offshore of San Clemente, CA. It was built to mitigate damage caused by the massive San Onofre Nuclear Generating Station. The project was twenty years in the planning, and finally got underway (underwater) in 2008. Initial studies suggest that the reef is meeting its goals for kelp production, but it has fallen short of expected fish production, so far.

Onward and Downward

This hasn’t stopped the drive for more and bigger reefs. In 2008 – 2009 the State of Maryland (my home) teamed up with New York, New Jersey, and Delaware to sink hundreds of subway cars off their mid-Atlantic shores. The rationale was economic with little thought given to the environmental impacts: recreational fishing and diving contribute more than $1 billion annually to the Maryland economy. “Our top priority so far has been to raise the funds to do this,” says Martin Gary, a fisheries ecologist with the Maryland Department of Natural Resources. “We are just beginning to put a monitoring plan in place.”

This M60 is one of a hundred tanks sunk in 1994 in a 1,200-square-mile zone of artificial reefs off the coast of Alabama. Photograph by David Doubilet.

The inspiration for this article and the wonderful photos come from “Relics to Reefs,” an article by Stephen Harrigan in the February 2011 issue of National Geographic magazine, on newsstands January 25.

More of Doubilet’s phenomenal reef photos, including a series showing the sinking of the USNS Gen. Hoyt S. Vandenberg, can be found in this gallery.

For more on the sinking of the Vandenberg, check out: Artificial reefs of the Florida Keys.

This month’s National Geography also includes a wonderful article about the eerie ruins and relics that lie under Paris. You can check that out here.

February 2011 issue of National Geographic magazine, on newsstands January 25






Grossman, Gary et al. (1997). Do Artificial Reefs Increase Regional Fish Production? A Review of Existing Data Fisheries 22: 17-23, doi: 10.1577/1548-8446(1997)022<0017:DARIRF>2.0.CO;2

Sisson, Paul. “San Ononfre: Kelp canopy now visible over Edison’s new artificial reef” North County Times Posted: 18 Aug. 2010 8:42 PM, Accessed: February 4, 2011, 10:23 AM <;

Interlandi, Jeneen. “Are artificial reefs good for the environment?” Newsweek 20 June, 2008, Accessed: February 4, 2011, 09:58 AM <;


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