Evaluating the effects of man-made structures on macro-benthic ecological functioning in the North Sea

The sustainable development of the marine environment has resulted in the introduction of man-made structures (MMS) in the North Sea. These structures range from oil and gas platforms, buoys, wrecks to wind turbines, offering additional artificial habitat over predominantly soft-sediment areas. The expected effects from MMS in shallow shelf seas will modify benthic communities over various spatial and temporal scales with repercussions for overall ecosystem functioning. Research on large offshore structures have identified a suite of unique effects ranging from biodiversity changes with repercussions on local ecosystem functioning to the provision of habitat for fouling communities, acting as stepping stones and many other ecological modifications. Consequently, MMS might induce structural, functional and process-driven changes, which are different from those expected in natural soft bottom benthic systems. This study considers soft-sediment and introduced hard-substrate epifouling communities. The combination of these systems provides a unique ecological opportunity to ascertain biodiversity changes triggered by loss and gain of species provided by the addition of MMS. To date, our current understanding of how ecological functioning might be modified by the addition of these MMSs is still in its infancy. Our current analysis aimed at evaluating functional changes with a combination of biological traits analysis and energy flow changes calculated via modelled secondary production. Further, our study compared the different types of introduced MMS among the natural soft sediment communities, disentangling how the ecological functioning of the macrobenthos may be altered by the introduction of these structures, which provides improved concepts for current monitoring assessments.