Study Finds That Marine Life Thrives in Reefs Anchored by Offshore Oil Rigs

The oil rigs scattered along the southern California coast are not known for their aesthetic beauty. But hidden below the surface, the mass of pipes, girders and industrial functionality harbor something unexpected — stunning reefs teeming with fish and other ocean wildlife.

The platforms support thriving underwater ecosystems.

With the oil supply under the platforms dwindling, many of the platforms are coming to the end of their economic lifespan, raising an important question: What should be done with these structures that have become some of the most productive habitats for marine life?

Jeremy Claisse, an assistant professor of biological sciences at Cal Poly Pomona and a marine ecologist, has been working alongside the U.S. Bureau of Ocean Energy Management (BOEM) to determine the best course of action. BOEM, which works to protect the environment while ensuring the safe development of offshore energy and marine mineral resources, awarded Claisse and his colleagues a $100,000 grant to evaluate the structures as fish habitats.

Claisse does that by analyzing data collected by collaborators at the UC Santa Barbara Marine Science Institute and BOEM, which have used small submarines to survey the life surrounding the platforms since 1995.

He found that the rigs are 27 times more productive than natural rock reefs off the California coast. Because they are very tall and structurally complex, they provide an array of habitats for fish and invertebrates.

Once a rig stops operating, however, the task of either removing the platform structure entirely or leaving part of it in the water to continue functioning as a man-made reef is both technically challenging
and very expensive.

“One option is to remove the top portion of the structures to allow for boats to pass, while leaving the rest of the underwater structure to remain as fish habitat,” Claisse says. “This would save the oil companies money, with some of those savings contributing to a trust to fund marine research and conservation. Another option is to remove the platform altogether, which is what the oil companies originally agreed to do, but this would pretty much result in a complete loss of the fish and the habitat.”

With a $40,000 grant awarded in 2016 from the University of Southern California Sea Grant Program, Claisse will continue this research and also hire a master’s student to assist.

“We hope to provide more insight into what drives high rates of production for both natural and man-made reef habitats along our coastline,” he says.

The study may provide additional ways of modifying the structures to turn them into productive marine habitats and improve the life of the surrounding ocean.