Metabarcoding of sediment eDNA communities at the Hywind Scotland OWF – A pilot study

Environmental impact assessment and regular environmental monitoring of marine life are prerequisites for the construction, operation, and decommissioning of offshore wind farms (OWFs). Molecular methods such as metagenomics, quantitative PCR or metabarcoding, are increasingly being considered as a possible complement or alternative to currently used marine baseline and monitoring methods, both for pelagic (open water) and benthic (seafloor) organism studies. Metabarcoding is one such molecular method that uses DNA sequence differences between species in specific so-called marker genes to identify organism biodiversity in a bulk specimen sample containing multiple animals, or environmental sample from water or sediment. While a simplification, a list of unique gene sequence variants (variously referred to as ASVs or OTUs in the literature) in a metabarcoding dataset can be conceptually considered similar to different species in a classical species list. The following report is an assessment of the performance of such metabarcoding data – directly from DNA in sediment samples – in sediment impact monitoring as a complement to the current standard using species lists based on identification of >1 mm softbottom macrofauna. While recent eDNA studies have become more numerous, cumulative experience in particular habitats is still low: Thus this report should be considered an exploratory pilot study.