Publication Abstract

At the end of its operating lifetime, offshore oil and gas (O&G) infrastructure in the North Sea is currently required to be decommissioned. However, there is strikingly limited empirical evidence for the environmental and ecological impacts of decommissioning O&G infrastructure on seabed fauna. This has limited our understandings of the most environmentally sound decommissioning strategy. We used industry monitoring surveys to assess benthic food webs in the short (within one year) and long (over five years) timescales before and after decommissioning and benthic recovery post−decommissioning. Benthic communities showed a simplification of food web structure in the short timescale but appeared signs of recovery post−decommissioning with positive effects on the total abundance and proportion of intermediate species. Benthic food webs had greater complexity in the long timescale after decommissioning with positive effects on the linkage density. However, benthic recovery post−decommissioning appeared incomplete for larger organisms higher up the food chain with negative effects on the individual mean body size and proportion of top predators. Our findings indicate that decommissioning O&G infrastructure has long−term impacts on benthos without full recovery over long timescale. We highlight the importance of industry collecting more extensive data to help evidence an environmentally sound decommissioning process.

Zelin Chen, Tom C. Cameron, Elena Couce^*, Clement Garcia^*, Natalie Hicks, Gareth E. Thomas, Murray S.A. Thompson^*, Corinne Whitby and Eoin J. O’Gorman