Turning Oil Rigs into Diveable Reefs

When an offshore well stops producing oil, what should be done with the rig? One option is to haul it ashore, break it up and recycle it. That's expensive, costing up to $200 million just to remove one deepwater oil platform. But there is an alternative: Just leave it where it is. Of course, that's what you'd expect a greedy oil firm to do, right? Dirty the ocean to save the expense. But surprise: The cheap option -- leaving it there -- may actually be the environmentally-friendly one, an option supported by nearly all divers who have had the chance to dive oil rigs. And some environmentalists, but not all, agree.

For starters, it takes a lot of energy to move an oil rig. The ships needed to shift one would emit an average of 29,400 tons of carbon dioxide. And moving a rig disturbs the organisms that have attached themselves to its underside, or jacket. Far better to turn old rigs into reefs -- where fish congregate in great numbers and coral sprouts -- and that's what the federal government is telling many coastal states with offshore oil rigs to do.

"Reefing" involves bringing a platform's above-water parts ashore and cropping the lower parts to leave at least 85 feet of clearance (a good depth for divers) -- deep enough for ships to pass over, shallow enough for photosynthesis to nourish organisms on its upper reaches. Oil-rig reefs may shelter and feed up to eight tons of fish. In 2009, Shell moved a jacket in the Gulf of Mexico six miles away. The fish followed.

More than 490 platforms in U.S. waters have become reefs in the past 30 years, and some are now excellent big-fish dive sites (see Undercurrent's September feature on MV Spree liveaboard diving in the Texas Flower Gardens Marine Preserve). The Federal Bureau of Safety and Environmental Enforcement created a "Rigs-to-Reefs" policy to convince states to issue reefing permits. The big benefit for states: Oil firms typically hand over half the money they save by reefing. Mississippi pocketed an average of $625,000 for each of the 12 permits it has issued. Louisiana's take has averaged $270,000 per reefing -- and the state has issued 336 permits.

Currently, less than a tenth of America's decommissioned oil and gas platforms are reefed, but that share is likely to grow. Quenton Dokken, CEO of the nonprofit Gulf of Mexico Foundation, believes that within five years, oil firms will be reefing one of every four offshore rigs. "Gulf states, particularly Louisiana and Texas, are making a big push to streamline the permitting process."

Enter the Environmentalists

And then there's California. Big savings are possible in its deep waters offshore. In 2010, California's then-governor Arnold Schwarzenegger signed a law allowing reefing, with estimates that reefing the state's 27 platforms could save $2 billion. The California Ocean Science Trust advised state lawmakers that platforms increase marine life and should not all be removed.

Enter the environmentalists. In four years, not one platform off California has been reefed, and the odds look bleak, due to major public opposition. The Environmental Defense Center in Santa Barbara, a group that files anti-development lawsuits, advocates the complete removal of oil platforms. Linda Krop, its chief counsel, says that abandoned structures might damage anchors, rob natural reefs of fish and even leach poisons. However, she does acknowledge the environmental damage associated with complete rig removal.

Greenpeace makes a different argument. John Hocevar, its head of ocean campaigns, concedes that in some locations reefed platforms, if non-toxic, may increase marine life. "But they should be banned anyway, because they save the oil firms money, and, therefore, encourage them to drill more." That's bizarre logic, we think, unlikely to convince many.

Hocevar is one of 25 people who recently launched a campaign to stop rigs-to-reef programs in the Gulf of Mexico. The diverse group, which includes representatives of the Sierra Club, the Ocean Foundation, the Sea Turtle Conservancy and the United Commercial Fisherman's Association, submitted a letter to U.S. Interior Secretary Sally Jewell in July, asking her to require oil companies to remove rigs rather than convert them to reefs.

Their campaign coincides with the publication of a new book titled Bring Back the Gulf by Richard Charter, a senior fellow of the Ocean Foundation, and Dee Von Quirolo, a marine conservation consultant in Florida. They argue that there is no scientific consensus that reefed platforms and jackets contribute to maintaining fish stocks "or otherwise achieve overarching fisheries management goals." Instead, they write, "these artificial underwater structures aggregate fish, thereby contributing to over-fishing. It also is apparent that they fail to equal or rival natural coral reefs in biological diversity."

The July letter, which Charter and Quirolo also signed, urges Jewell to require the Department of Interior to stick to its policy of "requiring full decommissioning of spent oil and gas structures at the end of their useful economic life." The letter stated that the rigs' deteriorating metal structures "invites more ecosystem damage rather than restoring it as originally envisioned."

In Bring Back the Gulf, the authors consider the corals, sponges and sea life clinging to the structures to be biofouling communities of organisms that encourage the proliferation of nonnative invasive species and aggregation of fish, which leads to overfishing. They say there is adequate structure in the Gulf to support fish populations and that because existing rigs already make up five percent of all gulf habitat, there is no need to create more.

But Greg Stunz, professor of marine biology at Texas A&M University in Corpus Christi, disagrees, saying there is much science, including his own research, that clearly shows rigs are productive islands on an otherwise barren gulf floor. "They also support higher biomass than natural reefs, he told the Corpus Christi Caller-Times. "And we've found that fish grow much faster on artificial reefs. We've compared the performance of natural versus artificial, and we've found that artificial reefs provide recruitment for young snappers as well as anglers."

The Interior Department had said earlier last summer that it would be reviewing regulations about the decommissioning and related liability issues of old offshore oil infrastructure.

Meanwhile, the debate is likely to intensify. In the Gulf of Mexico, some 400 platforms are now being decommissioned every year. Divers and many fishermen want more to be reefed. On the flip side, shrimpers complain that reefs prevent them from dragging nets across the ocean floor (which, we think, may be a good thing, given the destruction from such practices). In California, oil companies must decide soon if they wish to turn redundant rigs into reefs. Until 2017, they can keep 45 percent of the savings. After that, the figure falls to 35 percent until 2023, when it drops to just 20 percent.

Richer than South Pacific Reefs

Perhaps a new study, published in the Proceedings of the National Academy of Sciences, will change opponents' minds. Apparently fish are turning the underwater portions of rigs into the equivalent of apartment towers. Biology researcher Jeremy Claisse of Occidental College led a team that surveyed 16 rigs annually over a 15-year period and found that they hosted 10 times the amount of fish as other natural marine environments around the world, such as reefs and estuaries. (Divers who have ever finned around a decommissioned rig are always astonished at the big fish and schools they encounter.) The California rigs even had seven times the aquatic population of the rich ecosystems in reefs in the South Pacific.

The main reason: Because the rig superstructures stretch all the way from the surface to the sea floor, they provide a huge area that becomes the undersea equivalent of a tall building. That allows it to attract fish that prefer habitats at a wide variety of depths. "The platform structures support a diverse community of invertebrates that, along with floating resources like plankton, provide the base of the food web supporting fish associated with the platform," Claisse says.

His team counted the fish and recorded their size, then calculated the weight of fish that were supported by each square meter of sea floor in the area of the rig. They compared the data to similar surveys of seven rocky reefs, and to studies on fish abundance in other natural habitats. But even the natural habitat with the greatest fish density -- a coral reef in French Polynesia -- was nowhere near as populated as the oil rigs. Then the team tried to compensate by only counting things near the ocean floor, but even then, the oil rigs were more productive than natural habitats, though not by such an extreme margin.

The vertical structure may also give the oil rigs' appeal to many species of rockfish. As they age, these fish tend to move to greater depths, but in the case of many oil rigs, they can do so without ever leaving the habitat. Combined with lower levels of predators than what was observed at natural reefs in the same area, this makes the environment around a rig very appealing for many species of fish. Claisse told New Scientist that the study shows that man-made structures actually can enhance natural habitats. But it's not necessary for them to be oil rigs. "In the future, it might be a good idea to figure out what features help fish to flourish, and then build them into renewable energy installations, such as wind and wave energy stations."

So while reefing is a new policy, it seems to be eco-friendly, and it pays for itself. How novel, especially these days, for something that so many disparate groups -- from oil companies and state legislatures to divers and marine life -- could agree on and benefit from.

-- Vanessa Richardson