Units

1. Introduction

1. NatureScot provided feedback on the Ossian Array Environmental Impact Assessment (EIA) Scoping Report (Ossian Offshore Wind Farm Limited (OWFL), 2023) as part of the Scoping consultation detailed within the formal Scoping Opinion provided on the 14 June 2023 (Marine Directorate – Licensing Operations Team (MD-LOT), 2023).
2. NatureScot recommended undertaking additional data collection to inform the environmental baseline for both benthic subtidal ecology and fish and shellfish ecology. Collection and analysis of environmental Deoxyribonucleic Acid (eDNA) samples to support baseline characterisation within both the Array and along the Proposed offshore export cable corridor (which is subject to a separate Application) was proposed. This approach was recommended to support characterisation of cryptic or scarce species, Scottish Priority Marine Feature (PMF) species and prey fish species.
3. This Note outlines Ossian OWFL’s proposed approach to address feedback regarding the recommendation to incorporate eDNA data into the baseline characterisation for the Array EIA Report.
4. The Ossian Array is located off the east coast of Scotland, approximately 80 km south-east of Aberdeen from the nearest point ( Figure 1.1   Open ▸ ).

Figure 1.1 Location of the Ossian Array

2. Baseline Characterisation Approach

2.1. Benthic Subtidal Ecology

5. A combination of desktop data sources and site-specific survey data from the Array have been used to characterise the benthic subtidal ecology baseline environment within the Array.
6. The established baseline for the Array as presented in the Ossian Array EIA Scoping Report (Ossian OWFL, 2023) is accepted by MD-LOT, NatureScot and other stakeholders. This baseline will be further developed for the Array EIA Report through desktop study.
7. Literature sources were used to support designing the benthic subtidal ecology site-specific survey, and the survey scope of work (SoW) was submitted to MD-LOT on 20 December 2021 for review. The survey SoW included standard acquisition methods:

• drop-down camera (stills images and video);
• grab sampling for sediment biology (standard macrofaunal taxonomy) and physico-chemistry; and
• epibenthic beam trawling.

8. Feedback from MD-LOT, including responses from NatureScot and Marine Scotland Science (MSS), on the benthic subtidal survey SoW was received via email on 24 January 2022 (MD-LOT, pers. comms. 2022), with the following comments raised:

• “The proposed methodology follows standard protocols for benthic surveys and analysis.”
• “The review of existing benthic data is comprehensive. Very few of the existing data points fall directly within E1 (east), but they will give regional context.”
• “The number and distribution of sampling locations (Figure 4.2) look appropriate for the size of the site (including a 2 km buffer).”
• “There is no overlap with any Nature Conservation MPAs [Marine Protected Areas].”
• “In section 5.3.1 Habitats/Species of Conservation Importance – we advise that they should also consider for further assessment any Priority Marine Features identified in the drop-down video footage. If the PMFs are sensitive to damage/disturbance, grab samples should be avoided at that location, as proposed for Annex 1 features.”

9. The following gaps were noted in the benthic subtidal survey SoW by MD-LOT as part of their review, although it was acknowledged that these were likely to come later in the project programme:

• geophysical surveys which will be used to inform the benthic surveys;
• benthic surveys of the Proposed offshore export cable corridor(s); and
• intertidal surveys at the Proposed landfall location(s).

10. Based on the above feedback on the benthic subtidal survey SoW, the approach to the site-specific survey was considered accepted by MD-LOT, noting the absence of reference to eDNA.
11. During survey execution in the Ossian Array this advice was actioned, whereby the geophysical survey data was acquired prior to benthic sampling, to enable benthic site selection to be informed by the geophysical return (i.e. the side scan sonar and multibeam echosounder/bathymetric data).

2.2. Fish and Shellfish Ecology

12. A detailed review of desktop data sources has been used to characterise the fish and shellfish ecology baseline environment for the Array EIA Report, with the inclusion of site-specific benthic subtidal ecology survey results to support the following elements:

• substrate suitability assessment for herring Clupea harengus spawning and for sandeel Ammodytidae spp., based on particle size analysis (PSA) results;
• contextual habitat information to support general fish and shellfish assemblage characterisation;
• opportunistic observations of fish and shellfish species in both grab samples and underwater stills images and video footage; and
• fish and shellfish catches from epibenthic beam trawls.

13. Desktop data sources used for baseline characterisation for the Ossian Array EIA Scoping Report (Ossian OWFL, 2023) include regional scientific and stock assessment surveys, surveys undertaken for other offshore wind projects within the project region, off the coast of the Firth of Forth, and published literature regarding species ecology, including spawning and nursery ecology.
14. The use of desktop data covering a broad number of years, which demonstrates relative consistency year-to-year, is considered sufficient to provide a robust characterisation, in combination with site-specific substrate suitability classification for key species.
15. The feedback received from MD-LOT (including responses from NatureScot and MSS) on the SoW for the site-specific benthic subtidal ecology survey (i.e. not as part of the Scoping Opinion for the Ossian Array EIA Scoping Report; Ossian OWFL, 2023) is outlined in section 2.1, and the SoW was considered accepted by MD-LOT. The incorporation of eDNA sampling was not recommended by MD-LOT at the time of review of the survey SoW.
16. The established baseline for the Array presented in the Ossian Array EIA Scoping Report (Ossian OWFL, 2023) is accepted by MD-LOT, NatureScot and other stakeholders, in line with the Scoping Opinion (MD-LOT, 2023).