Supplementary eDNA analyses at the Hywind Tampen FOWF

Abstract

The Hywind Tampen Offshore Floating Wind Park is a floating OWF (FOWF) situated in deep-water on the Norwegian Shelf in the Northern North Sea. On behalf of Equinor, in 2023-2024, NORCE Climate and Environment conducted an environmental DNA survey of surface (20 m) and bottom water samples from sampling stations upstream, inside, downstream and some distance away from the FOWF to assess fish (MiFish-U) and plankton (18S V1-V2) communities for potential impact (Hestetun et al., 2024). Study results revealed differences in community composition over time and with depth but could not detect impact – negative or positive – from the construction and operation of the FOWF itself. The study used fish capture and ROV data from IMR-conducted surveys in the area to ground truth completeness of the data. While the MiFish-U primer set was able to detect the vast majority of fish species reported in the fish capture and ROV studies, and detect some additional species, elasmobranchs (sharks and skates) were missing from the eDNA data. This technical note contains a re-sequencing of the Hestetun et al. (2024) samples using a combination of MiFish-U and MiFish-E primer sets, MiFish-E being a modification of the MiFish-U primer set specifically designed to detect elasmobranchs. The goal of this analysis was to assess the ability of this approach to get a more comprehensive overview of local fish communities also including elasmobranch species. In addition, new analyses of bottom water fish communities were made removing dominating and pelagic species to see if this revealed further information on differences in demersal fish composition between sampling stations.

Supplementary eDNA analyses at the Hywind Tampen FOWF