In the near-field of seabed infrastructure, forces on the seabed will be dominated by the local flow amplification. In the far-field, the cumulative effect of flow amplification and climate-driven changes can still influence seabed mobility and sediment composition significantly enough to modulate habitat suitability. Some animals might be affected negatively from such changes, but some positively.
In our ECOWind-ACCELERATE project (2022-26), we are assessing the combined impacts of climate change and large offshore windfarms on the rate and nature of seabed sediment transport over various spatial and temporal scales. Via a multi-proxy study using concurrent information on physical and biological processes in the marine environment, large flume laboratory experiments and models under different climate predictions, we will map how the stresses on the bed will be modified by 2050 and by 2100 and how the distribution of seabed habitats and biodiversity will change. We are establishing how deep-diving seabirds use the seabed exactly across different habitats, and we will use that fine-scale relationship to establish impacts on these seabirds.

We are strengthening capability and confidence in modelling approaches, e.g. UKCP18-ORCA1/4 to help simulate bed stress under sea level rise and changing tides, and TELEMAC-TOMAWAC-SISYPHE to quantify the combined impact on seabed mobility from modified flows around windfarms and from climate change. We can thus provide advice on e.g. (1) what aspects of future climate (like storm wave height) will impact seabed stresses (and thus habitat suitability) over which time scales, (2) what observations serve best to understand impact (like mean time-averaged flow vs turbulent kinetic energy), (3) what species are best/worst suited for using deep-learning methods in large video datasets.

In summary, via quantified impacts on benthic habitats and predator foraging success we will deliver a robust and unified evidence base behind efficient habitats regulation assessments, strategic compensation advice and seabed monitoring approaches. We want to provide the context within which recovery of features and ecosystem services can be promoted, and in which marine net gain may happen at the same time as future climate change-adaptive and resilient offshore structures are designed.

Plain-language Summary:
New large infrastructure like windfarms and tidal lagoons will be built on the seabed as part of an accelerated schedule to switch away from fossil fuels and to protect our coastlines. When natural currents in the sea deviate around such seabed infrastructure, it can change the shape and composition of the seabed (i.e. more gravelly, sandy or muddy). This happens both near the infrastructure and far away from it. The seabed is important for fishing, carbon storage, aggregates and coastal protection. It also is the home to little fish that are eaten by larger animals like marine mammals and seabirds that dive to the seabed for their food. It is therefore important that we assess what the impact is from changes to the seabed in the future and we started a 4-year ECOWind-ACCELERATE research project in 2022 to address these issues. The knowledge we generate can help the design of renewable energy infrastructure in such a way that animals that use the seabed can benefit.