THE PROBLEM: Offshore windfarms will be developed at an accelerated schedule under fast-track plans to switch away from fossil fuels. With ever larger offshore windfarms, and the cumulative effects of climate change, we thus urgently need to understand the way the seabed is modified in response and how such changes affect the wider marine ecosystem.
When natural currents in the sea deviate around the wind turbines or anchors, the forces acting on the bed enhance, making sediments move and stay in suspension. This reduces the clarity of the water and changes the shape and sediment composition of the seabed, with impacts stretching far beyond the object. The seabed supports ecosystems that deliver a wide range of services incl. fishing, carbon storage, aggregates and coastal protection. The climate crisis will stretch impacts even further and into coastal zones, as future storm waves and rising sea levels will alter the ways energy from the sea is transferred to the seabed. All these changes combined can have wide-reaching impacts for organisms that live on or in the seabed, potentially changing biodiversity (species richness) and the delivery of some of these ecosystem services. The impacts at the seabed extend through the food chain to the water column and beyond as seabed dwelling fish are consumed by seabirds and cetaceans. Aggregations of fish can be strongly associated to particular seabed properties. If displacement or mortality occurs amongst these important prey species, this has knock-on effects for the deep-diving predators that cannot afford to be less efficient in foraging for food, like the seabirds that are protected by legislation. During this pivotal time of energy transition and national security, it is of crucial importance to better understand and unlock the potential of the marine environment for a renewable energy transition with added benefits to the ecosystem.

AIM: This proposal sets out a strategy to assess the seabed response to the combination of accelerated windfarm expansion and accelerated climate change, and to quantify the implications for (1) biodiversity, (2) ecosystem services, (3) habitats, and (4) interactions between seabird populations and their food.
We ultimately seek to help identify opportunities that benefit the conservation of species and increase biodiversity around windfarms. We will help windfarm developers design their monitoring strategies long beyond the life-span of our project.

SUMMARY OF METHODS AND OUTPUTS: Via a multi-proxy study using observations, laboratory experiments and models, we will assess and map, under different climate predictions, how the stresses on the bed will be modified by 2050, how the distribution of seabed habitats and biodiversity will change, and how that drives changes to ecosystem services and the foraging success of deep-diving seabirds. We will design relevant scenarios, where we consider offshore windfarm size, scour mitigation strategies, predator behaviour and the ecosystem's vulnerability to change due to the combined effect of accelerated windfarm expansion and climate change. We will use the Eastern Irish Sea area as case study, as it is the home of a variety of seabird species with specific predator-prey relationships, of diverse seabed types and of considerable windfarm expansion nearby existing windfarms. To help all developers of windfarms in the UK, UK-scale maps will be made of the vulnerability of the seabed to change, and a new seabird vulnerability index will be developed. Our quantification of how these processes from seabed to seabirds interact can directly inform/feed into existing and future decision support tools. We will provide a tool where stakeholders can run their own simulations anywhere around the UK and for any given model/data resolution to quantify uncertainty levels of bed stress caused by windfarms, with cascading effects of uncertainty in habitat and biodiversity distribution and ecosystem services.