Man-made structures including rigs, pipelines, cables, renewable energy devices, and shipwrecks, offer hard substrate in the largely soft-sediment environment of the North Sea. These structures become colonised by sedentary organisms and non-migratory reef fish and form local ecosystems that attract larger predators including seals, birds and fish. It is possible that these structures form a system of interconnected hard substrate through three mechanisms:
- the ‘planktonic dispersal’ of the pelagic stages of organisms between the structures by ocean currents;
- ‘movement’ of mobile organisms.
- Changes to the overall arrangement of hard substrate areas through removal or addition of individual man-made structures which will affect the interconnectivity and could impact on the ecosystem.
In this project, network analysis will be used to assess if a network of hard substrate exists and the extent to which man-made structures in the North Sea contribute to an interconnected system of hard substrate. Connectivity will be assessed using models that simulate the drift of planktonic stages and using existing knowledge of mobile organisms. The effect of changes to man-made structures will be assessed for native and non-native species, different ages of structures, and relationships with both natural habitats and Marine Protected Areas will be investigated. The impact of removal of oil and gas infrastructure will then be assessed using network analysis and compared to existing man-made structures and natural substrate.