Trash or Treasure? Considerations for Future Ecological Research to Inform Oil and Gas Decommissioning

Numerous oil and gas (O&G) installations worldwide will need to be decommissioned in the near future. Complete removal of subsea structures is often the default approach although some regions retain structures under rigs-to-reefs programs. Here, we reviewed the published literature to understand the status of global research on decommissioning, and specifically identify gaps in ecological knowledge. We estimated the frequency of different research categories (i.e., themes, and spatial/temporal scales), and tested the assumption that the number of papers across the categories of each research aspect was even in distribution. However, the frequency of studies focusing on biodiversity at a local (≤100 km2) scale (relative to regional and oceanic and pan-oceanic scales) were significantly higher; while other theme categories (e.g., eco-toxicology, connectivity, structural-integrity, restoration and other) were significantly lower than expected. Temporally, ≤1-year studies were more frequent than multi-year studies, but these frequencies did not significantly deviate from the assumed distribution of equal frequencies. We propose that further research be carried out to evaluate the benefits of both retention and removal of structures. Ecological research on decommissioning should extend its focus beyond biodiversity, to include eco-toxicology, structural-integrity, connectivity at larger spatial and temporal scales. This would provide a more holistic assessment of ecological impacts to inform sustainable and equitable development choices in multiple Blue Economy sectors, as we transition from offshore O&G to marine renewables.