With more than 1300 energy-related structures (oil and gas platforms, wind turbines, cables) in the North Sea, we need to understand the role these man-made structures (MMS) play in the marine ecosystem. Current decommissioning regulations prohibit leaving installations in place, which means complete removal when no longer in production. The effect these MMS have on marine ecosystems is largely unknown, and may be positive or negative. As we start to consider how best to decommission structures, it is important to understand the impact these structures have on the seabed.
The North Sea is covered by sandy and muddy sediments, and recent work under the NERC Shelf Seas Biogeochemistry programme established that a significant proportion of carbon ('blue carbon') is stored in these shelf sediments. These sediments are also important for nutrient cycling, and provide a habitat for many species (such as commercial fish species).The presence and installation of MMS provides protection of the seabed from other human activities, such as trawling and dredging, protecting the seabed from physical disturbance and hence provide an unofficial 'Marine Protected Area' (MPA).
The hydrocarbon (oil and gas) extraction activity at many MMS influences local species biodiversity, particularly changing the composition of micro-organisms which degrade the hydrocarbons within the sediments. Whilst the stability of these sediments and their ability to store carbon is uncertain, the decommissioning and physical removal of MMS is likely to disrupt these long term carbon stores, releasing carbon into the seawater, and affect seabed services such as nutrient cycling. Current Oslo-Paris (OSPAR) regulations advocate complete removal of MMS, and the shelf sediments may be exposed to additional hydrocarbon contaminants either via oil seeps/pipeline leaks or resuspension of oily drill cuttings during removal. The disturbance and wider impact of removal of all MMS is relatively unknown.
FuECoMMS addresses this knowledge gap through novel technologies (Autonomous Underwater Vehicles) and environmental DNA 'eDNA', with modelling of environmental data alongside data from industry (INSITE Interactive and our industry partners) to identify the role of MMS on key marine ecosystem processes. The project includes fieldwork to sample around MMS to measure the changes in carbon storage and biodiversity within the sediments. The project works closely with industry partners and stakeholders to ensure the outcomes are relevant and informative. Recent news reports on UK decommissioning decisions have drawn attention among other European oil nations on what is environmentally acceptable, and the outputs of this project are expected to have international interest and direct policy relevance for future decommissioning.