Our relationship with the ocean is decidedly complicated. We rely on it for food but allow oil-filled vessels to sail through it. We look to it for energy but inadvertently pollute it, either with toxins or noise.

Think about structures like decommissioned oil rigs and shipwrecks that dot the ocean floor. These man-made structures don't belong there — in fact, their initial presence was incredibly disruptive. But over time, they become a part of the ecosystem. Not only has life adopted to their presence, but the structures themselves are giving back to the environment.

In fact, these man-made structures could represent a unique conservation opportunity, helping marine life become more resilient to climate change and habitat loss by creating new and bigger neighborhoods, according to study published in Scientific Reports.

Part of their world

Looking at ocean rigs and shipwrecks in the North Sea, researchers from the University of Edinburgh used computer modeling to determine how marine life might use these abandoned structures and vessels as a way to flourish. Researchers used the cold-water, slow-growing coral Lophelia pertusa as their example for the study. Using network theory metrics, they sought to determine the extent to which L. pertusa established itself on these man-made structures and whether or not larvae from coral already established on the structures could spread to areas with naturally occurring populations.

Researchers found that, "North Sea oil and gas installations have the strong potential to form highly inter-connected regional network of anthropogenic coral ecosystems capable of supplying larvae to natural populations downstream." A web of larvae between closely connected rigs was predicted as was "long-range dispersal" of the larvae from the rigs.

Lophelia pertusa coral grows in the ocean Researchers used Lophelia pertusa (pictured) to study the flow of marine life among offshore oil rigs. (Photo: NOAA Photo Library/Wikimedia Commons)

Some structures would even act as bridges between other structures and natural populations, providing a "stepping stone" of sorts in the event of slow ocean currents. This, the researchers write, is an important aspect of the structures, especially as the "Atlantic's ocean conveyor belt, the Atlantic Meridional Overturning Circulation, is expected to slow and could push the [North Atlantic Oscillation] into record lows that would reduce connections and cut off larvae to natural coral ecosystems and [marine protected areas]."

As a result of the modeled importance that these structures play in the life cycle and survival of this one coral species, researchers suggest that we shouldn't be so quick to remove them from the ocean, especially the more established ones.

"We need to think very carefully about the best strategies to remove these platforms, bearing in mind the key role they may now play in the North Sea ecosystem," Lea-Anne Henry, a professor at the University of Edinburgh's school of geosciences, said in a statement.

The study was funded in part by the joint industry project Influence of Structures In The Ecosystem (INSITE), an initiative sponsored by eight energy companies to study the decommissioning of offshore structures and pipelines. An independent scientific advisory board reviews and selects research projects INSITE provides funding for. This particular study was part of INSITE's Appraisal of Network Connectivity between North Sea subsea oil and gas platforms (ANChor) project. The study also received funding from the European Union's Horizon 2020 program.

How can oil rigs be good for marine life?
Decommissioned structures provide a surprising opportunity for growth.