Impact of an offshore wind farm on benthic microbial communities in the Irish Sea

Offshore windfarm construction is continuously increasing and yet data on the impacts of these renewable energy structures is limited, especially regarding benthic microbial communities. Many of these communities are key to the vital biogeochemical cycles that underpin the marine food webs and other important ecological processes. Here we use environmental DNA (eDNA) to assess a well-established offshore windfarm (Barrow) in the Irish Sea, to understand the impacts on sediment microorganisms. Sediment samples were collected along two increasing distance gradients from the centre of the site to 32km away. Initial results show significant decreases with increasing distance from the wind farm in 16S rRNA gene copy numbers for Archaea and Bacteria (~10 and 100-fold respectively), as well as an ~10-fold decrease in ITS copy numbers for Fungi. Functional genes associated with nitrogen cycling were also assessed and similar trends were seen. With increasing distance from the site, ammonia-oxidizing bacteria showed ~5- fold significant decreases in amoA gene copy numbers, whilst copy numbers for denitrification-associated functional genes (nirS, nirK, nosZ) showed ~10, 15 and 5-fold decreases respectively. The impact of operations from wind farms can be detected in benthic microbial communities in the surrounding environment, and the functional roles of these species make them key to understanding and predicting ecosystem function and response to impacts from wind energy structures. Further work will assess other biogeochemical functional genes, as well as heavy metal and nutrient concentrations. The latest findings will be discussed. Information on the impacts on benthic ecology from these ubiquitous energy structures is crucial to better manage the structures and their legacy in the marine environment.