1. Introduction

1. RPS was commissioned by Berwick Bank Wind Farm Limited (BBWFL), a wholly owned subsidiary of SSE Renewables (SSER) Limited (hereafter ‘the Applicant’) to undertake a benthic subtidal and intertidal ecology characterisation of the Berwick Bank Wind Farm (hereafter referred to as “the Proposed Development”), and surrounding area to inform the Environmental Impact Assessment (EIA) Report. The Proposed Development array area is located in the outer Firth of Forth and Firth of Tay, 37.8 km east of the Scottish Borders coastline (St Abb’s Head) and 47.6 km to the East Lothian coastline from the nearest boundary. It covers an area of approximately 1,178.1 km2. Up to eight export cables will connect the Proposed Development to the mainland, via a cable landfall. The export cables which form part of the Proposed Development will make landfall on the East Lothian coast, specifically at Skateraw Harbour (hereafter referred to as the ‘Skateraw landfall’). From here, the Project will connect to a Scottish Power Energy Networks (SPEN) Transmission 400kV Grid Substation located at Branxton, which is located southeast of Torness Power station.
2. This Benthic Subtidal and Intertidal Ecology Technical Report provides an up-to-date benthic subtidal and intertidal ecology baseline characterisation for the Proposed Development using the most recent desktop data and site-specific survey data.
3. This report is structured as follows:

• section 2 - study area;
• section 3 – methodology and baseline characterisation, including details of desk-based sources and site-specific survey data; and
• section 4 – summary, including identification of Important Ecological Features (IEFs).

2. Study Area

4. For the purposes of the benthic subtidal and intertidal ecology assessment, two study areas have been defined:

• The Proposed Development benthic subtidal and intertidal ecology study area has been defined with reference to the Proposed Development boundary that existed prior to the boundary refinement in June 2022. As the refinements resulted in a reduction of the Proposed Development array area, the benthic subtidal and intertidal ecology study area is considered to remain representative and presents a conservative baseline against which the benthic and subtidal ecology assessment is undertaken. The Proposed Development benthic subtidal and intertidal ecology study area has not therefore been realigned to the current Proposed Development boundary. This includes intertidal habitats within the Proposed Development export cable corridor (between Mean Low Water Springs (MLWS) and Mean High Water Springs (MHWS) mark). It is the area within which the site specific benthic subtidal and intertidal surveys were undertaken ( Figure 2.1   Open ▸ ). Data collected from areas outside the Proposed Development benthic subtidal and intertidal ecology study area were analysed and included in the baseline characterisation as they provide further context to the data collected within the Proposed Development benthic subtidal and intertidal ecology study area.
• The regional benthic subtidal and intertidal ecology study area encompasses the wider northern North Sea habitats and includes the neighbouring consented offshore wind farms (and their associated export cable corridors) and designated sites ( Figure 2.1   Open ▸ ). It has been characterised by desktop data and provides a wider context to the site-specific data.

Figure 2.1:  Benthic Subtidal and Intertidal Ecology Study Areas

3. Baseline

3.1. Methodology

5. A desktop review has been undertaken to inform the baseline for benthic subtidal and intertidal ecology, including a review of a number of academic reports, reports from surveys undertaken to support other project consents and surveys to support the designation of Marine Protection Areas (MPAs) for offshore habitats located in the vicinity of the Proposed Development ( Table 3.1   Open ▸ ). These provide further context to the site-specific surveys ( Table 3.2   Open ▸ ).
6. A benthic subtidal survey and a benthic intertidal survey have been undertaken to characterise the Proposed Development benthic subtidal and intertidal ecology study area for the purposes of informing the benthic subtidal and intertidal ecology EIA Report (volume 2, chapter 8). The subtidal ecology survey consisted of grab sampling, drop down video (DDV) sampling and epibenthic trawls. Analysis of results included multivariate and univariate statistical analyses as well as descriptions of the raw data. Data collection and analysis to inform various site-selection options resulted in areas being analysed that ultimately did not fall within the Proposed Development, however they have been included to provide further context.
7. The intertidal survey involved a Phase 1 walkover and sediment sampling at the proposed landfall location. Detailed notes were taken along with waypoint locations at habitat changes and photographs of the habitats. These were reviewed to provide a biotope map of the proposed landfall location.
8. Detailed methodologies for each survey are presented in section 3.4.

3.2. Desktop Study

9. Information on benthic subtidal and intertidal ecology within the regional benthic subtidal and intertidal ecology study area and the Proposed Development benthic subtidal and intertidal ecology study area was collected through a detailed desktop review of existing studies and datasets. These are summarised in Table 3.1   Open ▸ .

Table 3.1: Summary of Key Desktop Reports

3.2.1.    Regional Benthic Subtidal and Intertidal Ecology Study Area

Subtidal sediments

10. The seabed sediments of the regional benthic subtidal and intertidal ecology study area have been recorded as being dominated by circalittoral sand with patches of circalittoral coarse sediment, which is characteristic of the North Sea (EMODnet, 2019). The EMODnet (European Marine Observation and Data Network) broad-scale seabed habitat map for Europe (EUSeaMap) and the Marine Scotland National Marine Plan Interactive (NMPI) map present the European Nature Information System (EUNIS) habitat classifications for the northern North Sea ( Figure 3.1   Open ▸ ). The most common sediment types noted in the regional benthic subtidal and intertidal ecology study area were deep circalittoral sand, followed by deep circalittoral coarse sediment and deep circalittoral mud ( Figure 3.1   Open ▸ ), all identified as low energy habitats by EMODnet, 2019. Based on the EUSeaMap data, regions of higher topography and those associated with the bank complexes within the Firth of Forth approaches were dominated by deep circalittoral coarse sediments whereas those in deeper water and in the flanks of the banks were dominated by deep circalittoral sands ( Figure 3.1   Open ▸ ). Finer sediments were recorded in the nearshore areas of the regional benthic subtidal and intertidal ecology study area. There were large areas of circalittoral fine sand or circalittoral muddy sand, deep circalittoral mud and circalittoral sandy mud recorded at the entrance to the Firth of Forth and Firth of Tay. Further inshore, these fine sediments give way to moderate energy circalittoral rock, mixed and coarse sediments ( Figure 3.1   Open ▸ ; EMODnet, 2019).
11. The Firth of Forth Banks Complex (FFBC) MPA has been strongly influenced by water currents with a mosaic of different types of sand and gravels, which create a unique range of habitats (JNCC, 2021a). Although these sediments were found to be relatively common around Scotland, the dynamic currents in the Firth of Forth Banks area influence the distribution of the sands and gravels (JNCC, 2014a). Axelsson et al. (2014) analysis of the video and still photography from surveys within the FFBC MPA undertaken in 2011 as part of the Scottish MPA Project, reported three broad habitat types: soft sediments with ripples; mixed sediment; and coarse sediments with some rocky outcrops. Gravelly sand sediments were more frequently recorded towards the north of the FFBC MPA with gravelly muddy sands and mixed sediments present to the south and west of the FFBC MPA (Axelsson et al., 2014). Acoustic data from surveys within the FFBC MPA undertaken in 2011 as part of the same project, reported sandy gravel, sand, gravelly sand and slightly gravelly sand in the approaches to the Firth of Forth and Wee Bankie to Gourdon areas (Sotheran and Crawford-Avis, 2013).
12. The Wee Bankie moraine formation feature of the FFBC MPA occurs within the regional benthic subtidal and intertidal ecology study area. A large proportion of the Wee Bankie moraine formation can be found within the Wee Bankie (including Scalp Bank) part of the FFBC MPA and is considered to be a Key Geodiversity Area in Scotland’s seas. This formation comprised a series of prominent (20 m high) submarine glacial ridges, composed of poorly sorted sediments (boulders, gravels, sands and clays) (JNCC, 2020a). Brooks et al. (2013) regarded the moraine geodiversity features as being scientifically important due to their key role in improving our understanding of the glacial retreat history of the last British Irish ice sheet.
13. The surveys conducted in 2011 to support the EIA benthic baseline characterisation for what were known at the time as the Seagreen Alpha/Bravo offshore wind farms (located immediately to the north of the Proposed Development array area, Figure 3.2   Open ▸ ) also provided an overview of the sedimentary habitats present within the regional benthic subtidal and intertidal ecology study area. In 2018, the Seagreen Alpha and Bravo projects were combined to form Seagreen in the same sea-area, which now comprises the Seagreen 1 and Seagreen Project 1A. This report refers to the superseded Seagreen (Alpha) and (Bravo) projects which were under development when the survey data was collected. The sediments present across the Seagreen (Alpha) array area ranged from cobbles with sand and gravelly sand in the west, to sandy gravel in the east. There was a greater predominance of fine sediments recorded across the Seagreen (Bravo) array compared with Seagreen (Alpha) array area, with sediments ranging from slightly gravelly sand in the west, sandy gravel in the central section and gravelly sand in the east of the Seagreen (Bravo) offshore wind farm. The majority of the seabed across both the Seagreen (Alpha and Bravo) array areas was level or undulating with occasional linear sediment waves (Seagreen, 2012).
14. The baseline characterisation surveys for the nearby Inch Cape offshore wind farm array area (Inch Cape Offshore Limited, 2011) reported the sediments to be characterised primarily by circalittoral sands and gravelly sands, with smaller areas of muddy mixed sediment.
15. The nearshore subtidal zone from North Berwick in Lothian to Flamborough Head in the East Riding of Yorkshire has been studied as part of the MNCR. Seabed sediments recorded in the nearshore subtidal zone of the regional benthic subtidal and intertidal ecology study area were sublittoral muddy sands, sublittoral fine sand, circalittoral rock and small areas of circalittoral mixed sediments (Brazier et al., 1998). The sediments recorded in the nearshore subtidal zone near the proposed landfall location were kelp forest with red algae and mobile sand shores (Brazier et al., 1998). The coastline at the Skateraw proposed landfall has experienced small amounts of accretion across the last 100 years (The Scottish Government, 2017).

Figure 3.1:  Benthic Habitats (EMODNet, 2019) within the Regional Benthic Subtidal and Intertidal Ecology Study Area

Subtidal benthic ecology

16. Cooper and Barry (2017) described the results of a baseline assessment of the UK’s subtidal macrobenthic infauna, with a particular focus around sites and regions of marine aggregate dredging. Although aggregates were the focus of the study, a “big data” approach was taken, collating data from across UK waters from various industries including offshore wind farms, oil and gas, nuclear and port and harbour sectors. This also included samples from the Neart na Gaoithe wind farm, within the regional benthic subtidal and intertidal ecology study area. Benthic infaunal communities were reported to be mainly polychaete and bivalve rich communities.
17. The northern North Sea contains a variety of benthic ecology habitats but is mainly characterised by polychaete dominated communities (Spionidae, Glyceridae, Terebellidae, Capitellidae, Phyllodocidae and Nemertea), sparse faunal communities (Nephtyidae, Spionidae, Opheliidae) and diverse faunal communities (including the polychaetes: Spionidae, Nephtyidae, Lumbrineridae, Oweniidae, Cirratulidae, Capitellidae, Ampharetidae, the echinoderm Amphiuridae, the bivalve Semelidae and Nemertea) (Cooper and Barry, 2017).
18. The MNCR study of the nearshore subtidal zone from North Berwick in Lothian to Flamborough Head in Yorkshire recorded nearshore seabed habitats in the regional benthic subtidal and intertidal ecology study area. Five seabed habitats were recorded (Brazier et al., 1998):

• SS.SMx.CMx.MysThyMx/SS.SMu.CSaMu.AfilMysAnit: Sublittoral muddy sand with echinoderms;
• IR.MIR.KR.Lhyp.Ft: Kelp forest with red algae;
• LS.LSa.MoSa.AmSco: Mobile sand shores with amphipods and polychaetes;
• SS.SSa.IFiSa.NcirBat: Sublittoral fine sand with polychaetes and bivalves; and
• CR.MCR.EcCr.FaAlCr.Bri: Circalittoral rock with brittlestars and hydroids.
  19. Analysis was undertaken on the data from seabed acoustic surveys that were carried out in 2013 to contribute to the evidence base for the presence and extent of MPA search features in Scottish waters (Southeran and Crawford-Avis, 2013). Phase 1 of the MPA search project surveys included the approaches to the Firth of Forth which overlaps with the regional benthic subtidal and intertidal ecology study area. Habitats ranged from sand sediments to coarse and mixed sediments in the inshore regions, and back to sand sediments in the offshore region. The biotope SS.SSa.CMuSa Circalittoral muddy sand was recorded in the nearshore subtidal area close to St. Andrews with circalittoral rock habitats, CR.HCR.XFa Mixed faunal turf communities/CR.MCR.EcCr Echinoderms and crustose communities recorded in the nearshore subtidal area off Craighead. SS.SSa.OSa Offshore subtidal sand was recorded across the approaches to the Firth of Forth and the Wee Bankie to Gourdon areas however it was more frequently recorded in the regions further offshore. SS.SCS.OSC Offshore circalittoral coarse sediment was also recorded across the approaches to the Firth of Forth and Wee Bankie to Gourdon areas. SS.SMx.CMx Circalittoral mixed sediments and SS.SMx.OMx Offshore mixed sediments were recorded in areas further inshore. Occasional patches of circalittoral rock were also recorded across the approaches to the Firth of Forth and Wee Bankie to Gourdon areas (Southeran and Crawford-Avis, 2013).
  20. The following biotopes were reported within the regional benthic subtidal and intertidal ecology study area (Southeran and Crawford-Avis, 2013):
• kelp with cushion fauna and/or foliose red seaweeds: IR.HIR.KFaR.FoR.Dic Foliose red seaweeds with dense Dictyota dichotoma and/or Dictyopteris membranacea on exposed lower infralittoral rock/IR.HIR.KFaR.LhypRVt Laminaria hyperborea and red seaweeds on exposed vertical rock;
• mixed faunal turf communities on circalittoral rock: CR.HCR.XFa.FluCoAs.X Flustra foliacea and colonial ascidians on tide-swept exposed circalittoral mixed substrata/CR.HCR.XFa.FluCoAs.SmAs Flustra foliacea, small solitary and colonial ascidians on tide-swept circalittoral bedrock or boulders/CR.HCR.XFa.FluCoAs Flustra foliacea and colonial ascidians on tide-swept moderately wave-exposed circalittoral rock;
• circalittoral coarse sediment: SS.SCS.CCS.PomB Pomatoceros triqueter with barnacles and bryozoan crusts on unstable circalittoral cobbles and pebbles/SS.SCS.CCS;
• deep circalittoral coarse sediment: SS.SCS.OCS/SS.SCS.OCS.(PoGintBy)/SS.SCS.OCS.(Sbom);
• circalittoral muddy sand: SS.SSa.CMuSa.AalbNuc Abra alba and Nucula nitidosa in circalittoral muddy sand or slightly mixed sediment/SS.SSa.CMuSa;
• deep circalittoral sand: SS.SSa.OSa/SS.SSa.OSa.(Sbom);
• circalittoral mixed sediments: SS.SMx.CMx.OphMx Ophiothrix fragilis and/or Ophiocomina nigra brittlestar beds on sublittoral mixed sediment/SS.SMx.CMx.(FluHyd)/SS.SMx.CMx.MysThyMx Mysella bidentata and Thyasira spp. in circalittoral muddy mixed sediment/SS.SBR.PoR.SspiMx Sabellaria spinulosa on stable circalittoral mixed sediment;
• deep circalittoral mixed sediments: SS.SMx.OMx.(PoGintBy);
• SS.SBR.SMus.ModMx: Modiolus beds on open coast circalittoral mixed sediment;
• CR.MCR.EcCr.FaAlCr.Adig Alcyonium digitatum, Pomatoceros triqueter, algal and bryozoan crusts on wave-exposed circalittoral rock/CR.MCR.EcCr.FaAlCr.Flu Flustra foliacea on slightly scoured silty circalittoral rock; and
• SS.SMu.CFiMu.SpnMeg: Seapens and burrowing megafauna in circalittoral fine mud.
  21. Phase 2 of the MPA Project survey focused on the data from seabed acoustic surveys on the eastern approaches to the Firth of Forth, the western tip of which overlaps with the regional benthic subtidal and intertidal study area (Southeran and Crawford-Avis, 2014). The following biotopes were reported within the eastern approaches to the Firth of Forth area:
• SS.SCS.CCS: Circalittoral coarse sediment/deep circalittoral coarse sediment;
• SS.SSa.CMuSa: Circalittoral muddy sand; and
• SS.SSa.OSa: Deep circalittoral sand.
  22. With regards to protected species, the National Biodiversity Network (NBN) Atlas and the SeaSearch database include records of Sabellaria spp. and ocean quahog Arctica islandica in the regional benthic subtidal and intertidal ecology study area (NBN, 2021). NatureScot publications have been searched to understand the presence of Scottish PMFs in the regional benthic subtidal and intertidal ecology study area. Tyler-Walters et al., (2016) reported blue mussel (Mytilus edulis) and horse mussel (Modiolus modiolus) beds, burrowed mud, kelp beds, ocean quahog A. islandica aggregations, maerl or coarse shell gravel with burrowing sea cucumbers, seagrass beds and offshore subtidal sands and gravels within the regional benthic subtidal and intertidal ecology study area.
  23. S. spinulosa has been recorded within the regional benthic subtidal and intertidal ecology study area. S. spinulosa records in Scotland are limited to Lue Bay, the Solway Firth and the North Sea of Rattray Head. There are very few records of S. spinulosa from Scotland and even fewer extant records of reefs. This is thought to be due to low sampling effort to date and therefore it is expected that more records of species and reefs will be made as the offshore industry progresses in the region (Pearce and Kimber, 2020).

Seagreen Alpha/Bravo offshore wind farm

24. The Seagreen Alpha/Bravo baseline characterisation surveys conducted in 2011 comprised infaunal grab sampling, beam trawl sampling and DDV sampling. The benthic habitats mapped for the EIA characterisation were divided into the following benthic community classes for each site:

Seagreen (Alpha) wind farm:

• western area: ‘Sabellaria’ (SS.SBR.PoR.SspiMx), ‘sparse polychaetes and bivalves’ (SS.SCS.ICS.MoeVen) and ‘faunal turf’ (SS.SMX.CMx.FluHyd); and
• central and eastern areas: dominated by the sabellid polychaete classes, ‘dense Chone’ (SS.SMx.OMx.(Chone)) and ‘sparse Chone’.

Seagreen (Bravo) wind farm:

• western half: ‘Sabellaria’, ‘rich polychaetes and bivalves’ and ‘epifauna with polychaetes’ (SS.SMx.OMx.PoVen); and
• eastern half: ‘dense Chone’ and ‘rich polychaetes’ (SS.SMx.OMx.PoVen).
  25. There was a clear divide between the two areas however ‘polychaete and bivalve’ habitats were also present in the most northern part of the eastern section of Seagreen (Bravo). There was also a patch of raised sandy gravel characterised by the brittlestar ‘Ophiothrix spp.’ (SS.SMx.CMx.OphMx) habitats located on or near the boundary between the western, central and eastern areas of Seagreen (Bravo).
  26. The number of species and individuals within the Seagreen (Bravo) wind farm site was generally lower than within the Seagreen (Alpha) wind farm site, which was likely to be a result of a predominance of finer sediments in the Seagreen (Bravo) wind farm site. Epifauna and encrusting fauna were common where the sediment contained gravel, shell or cobble. The distribution of epifauna was related to sediment type, with sandy gravels and gravelly sands supporting rich epifauna while gravelly sands were low in epifauna (Seagreen, 2012).
  27. High species richness was recorded in association with areas of Sabellaria habitat, although there was no evidence from the DDV surveys of extensive or well developed aggregations of Sabellaria within the Seagreen (Alpha) or Seagreen (Bravo) wind farm survey areas (Seagreen, 2012).
  28. Pre-construction benthic monitoring and Annex I reef surveys within the Seagreen array areas and export cable corridor were undertaken in 2020. Benthic habitats were recorded as circalittoral mixed sediments, SS.SMx.CMx.FluHyd and SS.SMx.CMx.OphMx, with patches of moderate energy circalittoral rock and circalittoral coarse sediment (APEM, 2020). The Annex I reef assessment reported that biogenic reefs (e.g. Annex 1 Sabellaria) were not present at any locations. Patches of medium resemblance stony reef were recorded among larger areas of cobble and sand in the export cable corridor, close to the Seagreen array area and within the north-east of the Seagreen array area. Patches of low resemblance stony reef were recorded in the export cable corridor, close to the Seagreen array area and within the north-east and central areas of the Seagreen array area (APEM, 2020). This is in line with the habitats mapped in the baseline characterisation presented in the Environmental Statement (Seagreen, 2012).
  29. A benthic validation survey was undertaken in 2020 and 2021 to support the marine licence application for an additional export cable corridor for Seagreen Project 1A ( Figure 3.2   Open ▸ ). The benthic subtidal survey comprised grab and DDV sampling and was undertaken to the north and north-west of the Proposed Development array area and around the subtidal areas off North Berwick. Sediments recorded ranged from sand to mixed sediments with sample stations closer to the coast containing a higher percentage of mud and those further offshore containing a higher percentage of sand. The Seagreen (Alpha) benthic validation survey recorded sandy mud biotopes (SS.SMu.CSaMu and SS.SMu.CSaMu.AfilMysAnit Amphiura filiformis, Mysella bidentata and Abra nitida in circalittoral sandy mud) across the mid-section of the export cable corridor survey area. Mixed sediment biotopes (SS.SMx.OMx.PoVen Polychaete-rich deep Venus community in offshore mixed sediments and SS.SMx.OMx.OphMx) were recorded in the furthest offshore samples within the export cable corridor survey area. The inshore sections of the export cable corridor survey area were dominated by muddy sediment biotopes (SS.SMu.CFiMu.SpnMeg and SS.SMu.ISaMu.MelMagThy Melinna palmata with Magelona spp. and Thyasira spp. in infralittoral sandy mud). The Seagreen (Alpha) benthic validation survey recorded SS.SMu.CSaMu.AfilMysAnit, SS.SMu.CSaMu, SS.SMx.OMx.PoVen and SS.SMx.OMx.OphMx overlapping with the north-west corner of the Proposed Development array area ( Figure 3.2   Open ▸ ). No Annex I reefs were recorded during the Seagreen (Alpha) benthic validation surveys.

Inch Cape offshore wind farm

30. The Inch Cape wind farm is located 7.7 km to the west of the Proposed Development and within the regional benthic subtidal and intertidal ecology study area ( Figure 3.2   Open ▸ ). The baseline characterisation surveys for the Inch Cape wind farm showed that the array area was dominated by circalittoral sands and gravelly sands with areas of mixed sediment. The epifaunal surveys recorded epibenthic species that were typical for these sediments and included dead man’s fingers (Alcyonium digitatum), horned wrack (Flustra foliacea), brittlestar (Ophiothrix fragilis), hydroids (e.g. Hydrallmania falcata) and a number of small fish and mobile benthic invertebrates. The DDV survey recorded a number of similar species; the key species recorded were: A. digitatum, Pomatoceros triqueter, Munida rugosa, F. foliacea, and Asterias rubens. The brittlestar O. fragilis occurred in high densities, but only at two stations (Inch Cape Offshore Limited, 2011).
31. The dominating biotopes within the array were SS.SMx.CMx.MysThyMx covering 65% of the array area, SS.SCS.OCS covering 31% of the area and SS.SCS.CCS.MedLumVen Mediomastus fragilis, Lumbrineris spp. and venerid bivalves in circalittoral coarse sand or gravel covering 4% of the area (Inch Cape Offshore Limited, 2011). A number of reef forming polychaetes (i.e. Sabellaria) were recorded; however, no evidence of Annex I reef features were recorded.

Neart na Gaoithe offshore wind farm

32. The Neart na Gaoithe array area is approximately 16.3 km west of the Proposed Development and within the regional benthic subtidal and intertidal ecology study area ( Figure 3.2   Open ▸ ). The baseline characterisation surveys for the Neart na Gaoithe array area reported slightly gravelly sands with areas of coarser sediments (e.g. sandy gravels and gravelly sand). Analysis of the grab samples mainly characterised the array area as SS.SMu.CSaMu.AfilNten Amphiura filiformis and Nuculoma tenuis in circalittoral and offshore sandy mud and a mosaic of SS.SCS.CCS/SS.SSa.OSa. Small patches of SS.SMu.CSaMu.ThyNten were reported in the east, SS.SSa.CFiSa.ApriBatPo Abra prismatica, Bathyporeia elegans and polychaetes in circalittoral fine sand in the south and SS.SSa.OSa.OfusAfil Owenia fusiformis and Amphiura filiformis in offshore circalittoral sand or muddy sand in the north and west of the array area (EMU, 2010). No protected or rara species were recorded (EMU, 2010).
33. Analysis of the DDV data mainly characterised the array area as SS.SMu.CFiMu.SpnMeg with regular patches of SS.SMx.CMx throughout the array area. SS.SMx Sublittoral mixed sediments, SS.SMx.CMx.OphMx and CR.MCR.EcCr (on boulders) were also recorded in small patches in the array area (EMU, 2010).

Figure 3.2: Offshore Wind Farms in the Regional Benthic Subtidal and Intertidal Ecology Study Area

3.2.2.    Proposed Development Benthic Subtidal and Intertidal Study Area

Subtidal sediments

34. Based on the EUSeaMap data, seabed sediments of the Proposed Development benthic subtidal and intertidal ecology study area have been recorded as being dominated by low energy deep circalittoral sand and low energy deep circalittoral coarse sediment (EMODnet, 2019). Deep circalittoral sands have been recorded in the offshore section of the export cable corridor with sediments becoming more variable in the inshore section of the export cable corridor; circalittoral sand sediments grade into deep circalittoral muds, deep circalittoral mixed sediments and deep circalittoral coarse sediments with increasing proximity to the landfall. Discrete areas of faunal communities on deep low energy circalittoral rock have been recorded throughout the inshore regions of the export cable corridor ( Figure 3.1   Open ▸ ).
35. The Proposed Development benthic subtidal and intertidal ecology study area overlaps with the FFBC MPA, designated for offshore subtidal sands and gravels, shelf banks and mounds, and moraines representative of the Wee Bankie Key Geodiversity Area (JNCC, 2021a). The FFBC MPA comprises the large-scale morphological bank features Berwick, Scalp and Montrose Banks and the Wee Bankie ( Figure 3.1   Open ▸ ). The Proposed Development overlaps the Berwick Bank and the southern section of the Scalp Bank and Wee Bankie aspects of the FFBC MPA. Habitat maps (Sotheran and Crawford-Avis, 2013 and 2014) and biotope assignment of 2011 still and grab sample data (Axelsson et al., 2014; Pearce et al., 2014) reported offshore subtidal sand and gravel habitats in the FFBC MPA. Axelsson et al. (2014) reported gravelly muddy sands and sands within the area overlapping the Proposed Development array area. 

Subtidal benthic ecology

36. Cooper and Barry (2017) reported that the majority of benthic samples coinciding with the eastern section of the Proposed Development array area were characterised by benthic infaunal communities of polychaetes (Spionidae, Nephtyidae, Lumbrineridae, Oweniidae, Cirratulidae, Capitellidae and Ampharetidae), echinoderms (Amphiuridae) and nemerteans. The western section of the Proposed Development array area was characterised by the same communities, with the addition of a species poor group (Nephtyidae, Spionidae and Opheliidae). The other main community types recorded in the Proposed Development benthic subtidal and intertidal ecology study area were rich communities of polychaetes (Spionidae, Nephtyidae, Capitellidae, Cirratulidae, Oweniidae and Pholoidae), bivalve molluscs (Montacutinae, Semelidae and Nuculidae) and nemerteans as well as a second group, also rich in polychaetes (Spionidae, Terebellidae, Serpulidae, Syllidae, Capitellidae, Cirratulidae, Lumbrineridae, Sabellariidae and Glyceridae) and nemerteans (Cooper and Barry, 2017).
37. The NBN Atlas and the SeaSearch database have been searched for the presence of protected species in the Proposed Development benthic subtidal and intertidal ecology study area. The common star fish (Asterias rubens), dead man’s fingers (Alcyonium digitatum), the strawberry anemone (Urticina eques) and several hydroids (Ectopleura larynx, Nemertesia ramosa) were recorded within the west of the proposed Development array area (NBN, 2021).
38. Surveys of the area now designated as the FFBC MPA were undertaken by JNCC in 2011 for the MPA search project, with sediments and biotopes identified in Pearce et al. (2014). These sampling locations were also included in the Cooper and Barry (2017) dataset. Pearce et al. (2014) identified the following biotope classifications within the east of the Proposed Development array area from the benthic grab data:

• SS.SSa.OSa [Sbom]: Spiophanes bombyx aggregations in offshore sands; and
• SS.SMx.OMx.[PoGintBy]: Polychaete-rich Galathea community with encrusting bryozoans and other epifauna on offshore circalittoral mixed sediment.
  39. The biotopes presented within the west of the Proposed Development array area were the same, with the addition of the following biotopes:
• SS.SBR.PoR.SspiMx: Sabellaria spinulosa on stable circalittoral mixed sediment; and
• SS.SCS.OCS.[Sbom]: Spiophanes bombyx aggregations in offshore coarse sands.
  40. Analysis of seabed imagery from the MPA search project survey of the area now designated as the FFBC MPA reported that the habitats characterised by mixed sediment were dominated by varied fauna including ophiuroids (O. fragilis and O. nigra), F. foliacea or the bivalve M.modiolus (Axelsson et al., 2014). The habitats characterised by coarse sediments were dominated by soft coral Alcyonium digitata and ascidians. In general, many of the stations were transitions between two biotopes, usually soft sediment into mixed sediment. The SS.SSa.CMuSa biotope was the most widespread with CR.HCR.XFa.FluCoAs.X, SS.SMx.CMx, SS.SMx.CMx.(FluHyd) and SS.SMx.CMx.OphMx also commonly recorded.
  41. The biotopes recorded in the east of the Proposed Development array area were (Axelsson et al., 2014):
• SS.SMx.CMx;
• SS.SMx.CMx.[FluHyd]: Flustra foliacea and Hydrallmania falcata on tide-swept circalittoral mixed sediment; and
• CR.MCR.EcCr.FaAlCr.Adig.
  42. The biotopes recorded within the west of the Proposed Development array area were:
• SS.SSa.CMuSa;
• SS.SMu.CSaMu;
• SS.SMu.CFiMu.SpnMeg;
• SS.SMx.CMx.OphMx;
• SS.SBR.SMus.ModMx; and
• CR.HCR.XFa.FluCoAs.X.
  43. Analysis of acoustic data from the MPA search project survey of the area now designated as the FFBC MPA reported that biotopes within the east of the Proposed Development array area included SS.SSa.CMuSa, SS.SSa.OSa and circalittoral mixed sediments with one record of CR.MCR.EcCr (Southeran and Crawford-Avis, 2013).
  44. The biotopes reported with the west of the Proposed Development array area were dominated by SS.SCS.OSC with additional records of SS.SSa.OSa, and circalittoral and offshore mixed sediments (Southeran and Crawford-Avis, 2013).
  45. In summary, the different analyses of the surveys carried out to characterise the area around the Firth of Forth to identify MPA features in Scottish Waters reported similar results. They reported sand, mud with coarse and mixed sediment, and some areas of rock. Sandy and muddy sands were the most commonly recorded seabed habitats. Faunal communities were generally polychaete dominated however high energy hydrozoan/bryozoan, brittlestar and bivalve dominated communities were also recorded. Recorded biotopes of conservation importance included:
• SS.SMu.CFiMu.SpnMeg (OSPAR habitat);
• SS.SBR.PoR.SspiMx (characterising biotope of an Annex I habitat, OSPAR habitat); and
• SS.SBR.SMus.ModMx (characterising biotope of an Annex I habitat, OSPAR habitat, Scottish PMF).
  46. The abundance of S. spinulosa and the diversity of fauna present recorded in the MPA search project survey was indicative of S. spinulosa reef. However, no information regarding the topographical height, the extent and the longevity of the aggregation were recorded therefore no Annex I reef assessment was conducted.
  47. A subtidal DDV survey was conducted in the nearshore subtidal area of Torness Nuclear Power Station (within the regional benthic subtidal and intertidal ecology study area) in September 2014. The survey indicated that the shallow subtidal was dominated by the biotope IR.MIR.KR.Lhyp L. hyperborea and foliose red seaweeds on moderately exposed infralittoral rock. As water depth increased, the coverage of kelp reduced, and red seaweeds increased (IR.MIR.KR Kelp and red seaweeds (moderate energy infralittoral rock)). An area of rock occasionally covered by a veneer of coarse sand, and with patches of macroalgae attached could be seen marking the lower boundary of the infralittoral rock (IR.MIR Moderate energy infralittoral rock). Below this region, the deeper circalittoral bedrock was dominated by CR.MCR.EcCr.FaAlCr Faunal and algal crusts on exposed to moderately wave-exposed circalittoral rock with pink faunal crusts, Spirobranchus triqueter and the urchin, Echinus esculentus, interspersed with CR.MCR.EcCr, areas of rock with a sparse appearance due to increasing grazing by echinoderms (ABPmer, 2019).

Intertidal benthic ecology

48. The intertidal surveys undertaken at the initial proposed landfall locations for Neart na Gaoithe and for the Torness Nuclear Power Station cover the Skateraw Landfall and are broadly consistent with each other. The surveys recorded a high energy sandy beach with extensive areas of bedrock, and complex, seaweed dominated, rock habitats.

Neart Na Gaoithe offshore wind farm

49. The proposed landfall locations for the Neart na Gaoithe offshore wind farm included Skateraw beach. A Phase 1 intertidal walkover survey with sediment sampling was undertaken at each landfall site in 2009 (EMU, 2010).
50. The Skateraw proposed landfall for the Neart na Gaoithe offshore wind farm consisted of a high energy sandy beach with extensive areas of bedrock and a deep-water channel dissecting the site. Uneven cobbles/pebbles/gravel areas were present to the south of the channel, overlying bedrock. Artificially placed large clean boulders were located within the upper shore to the south of the landfall, grading into clean small boulders/cobbles. Interesting features included the ‘natural’ large, erratic boulders, particularly in the north of the landfall survey area; the superficial sand on rock areas with an associated red algae community either side of the Arenicola/Lanice sand area; and the numerous patches of rock overlain with a thin layer of barren sand south of the central water channel. The rocky habitats at Skateraw were very complex; much of the shore the rock was broken into various heights from the upper shore to the lower shore. On the north side of the channel, the upper shore area consisted of raised bare bedrock with patches of typical upper shore algal species, Pelvetia canaliculata and Fucus spiralis, LR.MLR.BF.PelB Pelvetia canaliculata and barnacles on moderately exposed littoral fringe rock. Below this area the horizontal surfaces were covered by LR.MLR.BFFvesB Fucus vesiculosus dominated communities on both the raised dry rock and the wet rock areas. LR.MLR.BF.Fser Fucus serratus dominated communities, were nearest to the deep-water channel, adjacent to the Laminaria digitata zone in the sublittoral fringe. The F. serratus dominated area was dissected by a wet area with a concentration of pools, LR.FLR.Rkp.Cor.Cor Coralline crusts and Corallina officinalis in shallow eulittoral rockpools. A large area of mussels on bedrock present to the north of the channel was assigned the biotope LR.HLR.MusB.MytB Mytilus edulis and barnacles on very exposed eulittoral rock. Adjacent to this, an area of rock overlain with superficial sediment and an associated red algae community, assigned as a biotope mosaic: LR.HLR.FR.Osm Osmundea pinnatifida on moderately exposed mid eulittoral rock and IR.MIR.KR.XFoR Dense foliose red seaweeds on silty moderately exposed infralittoral rock, occurred on either side of the lower shore Arenicola/Lanice sand area (EMU, 2010).
51. The soft sediments at Skateraw comprised fine sand, with differing proportions of fine-medium gravel. Sandy embayments in the upper shore were characterised by barren sand with the LS.LSa.St strandline debris biotope. Below this, mobile species-poor sand, dominated by the polychaete Scolelepis spp., LS.LSa.MoSa.AmSco.Sco Scolelepis spp. in littoral mobile sand, was present in the mid shore. In the lower shore, clean sand with Arenicola and scattered Lanice conchilega occurred, representative of the SS.SSa.IMuSa.ArelSa Arenicola marina in infralittoral fine sand or muddy sand biotope (EMU, 2010).

Torness Nuclear Power Station

52. The Skateraw proposed landfall is directly north of the Torness Nuclear Power Station. Phase 1 walkover surveys were carried out in 2014 for the Torness Nuclear Power Station, located to the north of the Skateraw proposed landfall (ABPmer, 2019). At the northern extent of the Skateraw proposed landfall, the intertidal area consisted mainly of exposed, high energy rock (LR.HLR.MusB.Sem.LitX Semibalanus balanoides and Littorina spp. on exposed to moderately exposed eulittoral boulders and cobbles, LR.LLR.F.Fves.FS Fucus vesiculosus on full salinity moderately exposed to sheltered mid eulittoral rock and LR.MLR.BF.Fser.Bo Fucus serratus and under-boulder fauna on exposed to moderately exposed lower eulittoral boulders), but also included characteristic species indicative of sheltered, low energy coastlines, such as the egg wrack Ascophyllum nodosum. F. vesiculosus observed on the more exposed aspects of the bedrock, lacked twin air bladders, which is indicative of a more exposed, high energy environment. The Skateraw beach was surrounded by moderate energy littoral rock (LR.LLR.F.Fves.FS, LR.MLR.BF.FvesB Fucus vesiculosus and barnacle mosaics on moderately exposed mid eulittoral rock, LR.MLR.BF.Fser.R Fucus serratus and red seaweeds on moderately exposed lower eulittoral rock and IF.MIR.KR.Ldig). A steeply angled shore was present at the Skateraw proposed landfall, with barren, well-drained sands in the upper and mid shore areas LS.LSa.MoSa.BarSa, and polychaete dominated sediments lower on the shore, LS.LSs.FiSa.Po Polychaetes in littoral fine sand (ABPmer, 2019).

3.3. Designated Sites

53. Designated sites within one tidal excursion (12 km) of the Proposed Development array area and Proposed Development export cable corridor (therefore at the maximum range of the impacts of the Proposed Development) have been identified for benthic subtidal and intertidal ecology. On the basis of advice received from NatureScot, the Firth of Forth SSSI and the Berwickshire Coast (Intertidal) SSSI have been screened out on the basis of no spatial overlap. With regards to European sites, as per the Likely Significant Effects (LSE) Screening Report, only the Berwickshire and North Northumberland Coast Special Area of Conservation (SAC) is screened in.
54. The Proposed Development array area overlaps with the FFBC MPA and the Proposed Development export cable corridor overlaps, to a lesser extent with the FFBC MPA and with the Barns Ness Coast SSSI in the intertidal zone.
55. The FFBC MPA covers 2,130 km2 and is spilt into the three sections of Berwick Bank, Montrose Bank and Scalp Bank and Wee Bankie ( Figure 3.3   Open ▸ ). The FFBC MPA is designated for ocean quahog A. islandica aggregations, offshore subtidal sands and gravels, shelf banks and mounds, and moraines. The conservation objectives are to ensure that, subject to natural change, the integrity of the site is maintained or restored as appropriate, and that the site contributes to achieving the Favourable Conservation Status (FCS) of its qualifying features.
56. The Barns Ness Coast SSSI is located approximately 1 km east of Dunbar in East Lothian and covers an area of 2.5 km2. It is designated for lower carboniferous geological features, saltmarsh, sand dunes and shingle. Barns Ness beach had a sequence of sedimentary rocks which were formed during the Carboniferous geological period around 340 million years ago. Two major groups of sedimentary rocks were exposed on the coast: the limestone beds and a group consisting of sandstones, mudstones and occasional coal seams. An almost complete, though heavily faulted, section through the whole lower limestone group was exposed. The site was of importance as it demonstrates the succession of Lower Carboniferous Limestone, rich in fossils, and allows correlation between the Scottish Lower Carboniferous and the Lower Carboniferous of Northumbria (SNH, 2011a). These sediments, together with the marine and terrestrial fossils, provide a detailed picture of the changing Lower Carboniferous environment and the ancient ecology of the area (SNH, 2011b). Barns Ness Coast SSSI contained a variety of biological coastal habitats including shingle and sandy shores, sand dunes and a large area of mineral enriched dune grassland which all occur above MHWS and therefore were not considered further. The relevant objectives for management include: ‘to maintain the visibility of the geological features of interest’ and ‘to maintain recreational access within the area, particularly to the geological features of interest’. The 2000 site condition monitoring assessment of the ‘Lower Carboniferous Dinantian-Namurian’ feature found it to be in favourable condition. The extent, composition and structure of the rocks have been maintained, and they remain visible and accessible (SNH, 2011b).
57. The Berwickshire and North Northumberland Coast SAC is located 4.1 km south-east of the Proposed Development export cable corridor and covers an area of 652.26 km2 ( Figure 3.3   Open ▸ ). It is designated for the Annex I habitats: Mudflats and sandflats not covered by seawater at low tide, large shallow inlets and bays, reefs and submerged or partially submerged sea caves. The conservation objectives are to ensure that, subject to natural change, the integrity of the site is maintained or restored as appropriate, and that the site contributes to achieving the FCS of its qualifying features (JNCC, 2021c).

Figure 3.3:  Designated Sites with Benthic Habitat Features that Overlap with the Proposed Development Benthic Subtidal and Intertidal Ecology Study Area

3.4. Site Specific Subtidal Surveys

58. A benthic subtidal survey and a benthic intertidal survey were undertaken to characterise the Proposed Development benthic subtidal and intertidal ecology study area. A summary of these surveys is outlined in Table 3.2   Open ▸ with full detailed results presented in paragraphs 99 to 197.

Table 3.2: Summary of Surveys Undertaken to Inform Benthic Subtidal and Intertidal Ecology

3.4.1.    Methodology

Sample collection

59. The site-specific subtidal survey was undertaken across the Proposed Development benthic subtidal and intertidal ecology study area. As discussed in section 2, some benthic subtidal sampling was also undertaken in areas which, due to refinements to the boundary of the Proposed Development, extended beyond the boundary of Proposed Development benthic subtidal and intertidal ecology study area. This resulted in some subtidal sampling of areas to the north-west, south-west and south-east of the Proposed Development array area, and also the inshore area to the south of the Proposed Development export cable corridor (see Figure 3.4   Open ▸ ). The data collected from these areas were, however, analysed and included in the baseline characterisation as they provide further context to the data collected within the Proposed Development benthic subtidal and intertidal ecology study area. The subtidal survey combined DDV and 0.1 m2 mini Hamon grab sampling with epibenthic trawls. The sampling strategy was designed to adequately sample the area to provide data for baseline characterisation. The survey design was discussed and agreed with NatureScot, Marine Scotland Licensing Operations Team (MS-LOT) and Marine Scotland Science (MSS) during a meeting (30 June 2020) and via subsequent email correspondence (09 July 2020 with NatureScot and 15 July 2020 with MSS).
60. The benthic subtidal survey was undertaken by Ocean Ecology Ltd. (OEL) in September 2020. All sampling was conducted aboard the 22 m Category 2 survey vessel ‘MV Marshall Art’. The vessel mobilised from Hartlepool on the east coast of England and operated on a 24-hour operations basis, primarily from the port of Leith and Montrose due to proximity to the Proposed Development.

Grab sampling

61. The subtidal survey included 92 combined DDVs and 0.1 m2 mini Hamon grab sampling locations to ensure adequate data coverage for both infaunal and epifaunal communities at each location ( Figure 3.4   Open ▸ ). Day grab (with stainless steel jaws) samples for sediment chemistry were also collected at nine of the 92 combined DDV/grab sampling locations. DDV was deployed prior to the deployment of the grab at every combined grab/DDV sample location to determine whether Annex I reef was present, such that grab sampling could be avoided in these areas. A number of mini Hamon grab stations were removed from the scope following an initial review of the seabed imagery, see paragraph 70. All grab sample collection and processing was undertaken in line with version eight of the Regional Seabed Monitoring Programme (RSMP) protocol (Cooper and Mason, 2019).
62. Initial processing of all mini Hamon grab samples was undertaken aboard the survey vessel in line with the following methodology:

• Assessment of sample size and acceptability made.
• Photograph of sample with station details and scale bar taken.
• 10% of sample removed for subsequent Particle Size Analysis (PSA) analysis and transferred to labelled container.
• Sample emptied onto 1 mm sieve net laid over 4 mm sieve table and washed through using gentle rinsing with seawater hose.
• Remaining sample for sorting and identification backwashed into a suitably sized sample container using seawater and diluted 10 % formalin solution added to fix sample prior to laboratory analysis.
• Sample containers clearly labelled internally and externally with date, sample identification and project name.
  63. Initial processing of all Day grab samples was undertaken on board the survey vessel in line with the following methodology:
• Assessment of sample size and acceptability made.
• Photograph of drained sample showing undisturbed sediment surface with station details and scale bar taken.
  64. Sub samples were then taken from the surface of the sample while retained in the grab for sediment chemistry analysis.