It is well-known that offshore oil platforms become major habitats for fish. Their support structures rise hundreds of feet through the water column and basically create a prefabricated reef for marine life. Many of these platforms will soon be decommissioned and government agencies are considering the consequences to undersea life when this happens.
Researchers at the University of California Santa Barbara have looked at how various decommissioning scenarios would affect undersea ecosystems. They found that completely removing a platform could reduce fish biomass by an average of 95%. In contrast, removing just the top part of the rig could keep losses to around 10%.
California is looking at several possibilities for decommissioning 27 oil platforms off of its coast. The three options are: leave the platform in place, remove all of it, or remove just the top part of it. Each option entails its own economic and ecological consequences.
The research team studied the size and composition of fish communities at 24 platforms and created models for each of the decommissioning scenarios. The partial removal approach involved stripping away all structures within 26 meters of the surface. This number would eliminate the need for a lighted buoy where the support structure remained according to U.S. Coast Guard guidelines.
For the 24 structures studied, leaving them entirely in place would support over 29,000 kilograms of fish biomass. Removing just the top 26 meters would support nearly 28,000 kilograms. Removing the platforms entirely would support only 500 kilograms of fish biomass.
As California weighs how to decommission its oil platforms, studies like this will be critical to making informed decisions.
Photo, posted June 4, 2019, courtesy of Flickr.