Artificial Structures and the functioning of the North Sea EcoSyStem (ASSESS)

The presence of artificial structures (harbours, platforms and energy installations) in soft sediment environments changes the biodiversity, food-web complexity and resilience of communities. Data available on how this impacts the North Sea ecosystem carrying capacity are limited. The aim of the ASSESS project is to quantify these long-term changes, by assessing the food-web and ecological functioning of >20 year old artificial structures and surrounding seabeds. We will generate new data from field research and experiments and develop novel ecosystem models. This will allow better assessment of cumulative effects on the carrying capacity of the North Sea.


The aim of the ASSESS project is to quantify changes caused by the introduction of artificial hard substrates (AHS), by assessing the food web and ecological functioning of old (20-40 years) artificial structures and their effect on surrounding soft sediment. This will be done by generating new data from field research and experiments and developing novel ecosystem models.


Recent studies by WMR around 20-40 year old offshore oil and gas platforms showed that old AHS accommodate abundant, mostly suspension feeding communities, and increase local biodiversity and biomass. Suspension feeding communities on AHS will, however, also impact the wider marine environment by actively reducing the available primary producers through their grazing activities. This may have an impact on the entire food web, including attracted fish species, which take advantage of the increased food availability. This indicates that AHS has a significant effect on the local trophic structure from its basis to higher trophic levels. To date the knowledge of the impact of such old suspension feeding communities on the food-web and carrying capacity is very limited. Many new activities are proposed or being developed in the North Sea, together with a large upscaling of offshore wind industry. Together, these initiatives will change the communities in the North Sea and will affect the carrying capacity of the ecosystem. The magnitude of this change on a longer time scale of 20-40 years is unknown. Findings from the ASSESS project will help to better understand these effects and can aid in improving offshore energy designs.


Local food webs will be investigated on hard substrates, the seabed, the attracted fish and the water column. Oxygen consumption and filtration capacity of communities will be studied using respiration chambers and an experimental artificial hard substrate garden. Laboratory experiments will quantify effects of the increased biodiversity on benthic ecosystem functioning and carbon cycling. Finally, a dynamic ecosystem model and static average mass-flux model will be created, providing detailed descriptions of the entire food web.


All findings of the ASSESS project will become available via open access scientific publications and distributed via social media, conferences and workshops.