The term "offshore oil platform," probably doesn't conjure images of healthy, vibrant ecosystems. But just as they thrive in shipwrecks, marine organisms love glomming onto the underwater portions of oil rigs, transforming them into artificial reefs. That's why some industry leaders and environmentalists—in a rare instance of solidarity—believe the solution to the world's thousands of dead and dying oil rigs is actually quite simple: Just let 'em be.
Rigs-to-reefs is a decades-old notion that's generated a flurry of excitement in recent months, ever since a study published in PNAS demonstrated that oil platforms off the coast of California are the most productive marine habitats in the world by a factor of ten. Techno-reefing the ocean would seem a win-win for energy companies and the environment. Unsurprisingly, the issue is far more complex than it sounds.
"Habitat value is only one of many factors that must be considered when making rig-to-reef decisions," writes the Decommissioning Ecology Group (DEG), whose members hail from the University of Technology Sydney and Deakin University, in a letter to PNAS last week. "We argue that a holistic approach should be taken to decommissioning decisions for oil platforms."
In other words, ecosystems are complicated things, not to be messed with lightly.
The oil and gas infrastructure that feeds our fuel-hungry lives is growing old. There are currently over 7,500 offshore oil structures worldwide, of which an estimated 85% will become obsolete within the next decade. All told, hauling said rigs to shore and stripping their parts would amount to something like 40 billion US dollars—a cost that industry isn't too keen to eat.
It'd seem fortuitous, then, that ecologists have discovered steel beams also make stellar marine habitats. The rigs-to-reefs concept is best established in the Gulf of Mexico, where, since the 1980s, more than 200 decommissioned structures have been transformed into thriving reefs. (Locals can testify to that: oil rig fishing is said to be some of the best in the world).
Particularly promising is a techno-reef's ability to provide safe nurseries—beyond the reach of commercial trawlers—for a range of pelagic fish. Indeed, the authors of the recent PNAS study attribute the productivity of Californian oilrigs primarily to their importance as a haven for juvenile rockfish.
"This is a very fecund habitat for a number of species," study co-author Milton Love told me. "If you remove the rigs, you've removed the nursery."
So, techno-reefs offer clear benefits in at least a few locales. Could reefing be a simple, cost effective way of putting dying rigs across the world out to pasture? It's a nice idea, but, as Ashley Fowler from DEG explains, there are a host of additional factors that need to be considered when decommissioning a rig.
"In addition to fish recruitment, you have to consider the carbon cost or savings, future navigational hazards, commercial fishing access and the financial cost," Fowler told me in an email. (These factors, and a score of others, are fleshed out in a study Fowler's team published in early 2014.)
What's more, the ecological benefits of artificial reefs aren't necessarily clear-cut. Even if techno-reefs increase marine productivity overall, the species attracted to rigs may compete with, and displace, native communities. Techno-reefs could act as stepping stones for invasive species, in the same way that land invasives often thrive in human-altered habitats. The possibility simply hasn't been explored.
"Considerable research of platform communities, and their interaction with natural communities, is required to ensure that rigs-to-reefs programs proceed in an ecologically-sustainable manner," Fowler said.
Despite issue's complexity, the prospect of these oceanic eyesores reaping ecological benefits is exciting, and we're sure to hear more about it. In the future, reefing may become a mainstay not only of the oil industry, but offshore wind and wave energy as well. Now, if we could only find a way to rebuild marine ecosystems while generating renewable energy, that'd most certainly be a win for the world.