Assessment of in-combination effects during operation and maintenance
EMF from subsea electrical cabling
633 There is potential for in-combination effects from EMFs from subsea electrical cabling impacts to Annex II diadromous fish during the operation and maintenance phase of the Proposed Development with activities associated with the following projects:
- Tier 2:
– Inch Cape Offshore Wind Farm;
– Neart na Gaoithe Offshore Wind Farm;
– Seagreen 1;
– Seagreen 1A Project;
– Seagreen 1A Export Cable Corridor;
– Eastern Link 1;
– Eastern Link 2.
- Tier 3:
– Cambois connection.
634 Whilst any in-combination effects are predicted to be of long-term duration, continuous and not reversible during the operation of the relevant projects, they are also predicted to be of local spatial extent. Diadromous fish species have been assessed as having low sensitivity and high recoverability from EMF from electrical subsea cabling impacts. This can be concluded as EMF effects are confined to the close vicinity of cables. Diadromous fish species are pelagic, swimming in the water column and therefore less likely to interact with emitted EMF from subsea cables. While the sediments in which cables are buried will not reduce the strength of EMF, the burial of cables does increase the distance between cables and diadromous fish, with greater attenuation of EMFs with greater distance from the cable, thereby reducing the effect of EMFs on diadromous fish. The sensitivity of diadromous fish species is predicted to be low with high recoverability. There is, however, currently no information on the impact that this project will have on diadromous fish, however effects of EMF from the Cambois connection are likely to be similar in magnitude and extent as that discussed for the Proposed Development and the other projects considered in the in combination assessment as set out above.
635 Therefore, it can be concluded that there is no risk of an Adverse Effect on Integrity on the River Tay SAC as a result of EMF impacts with respect to the Proposed Development acting in-combination with Tier 2 or Tier 3 projects.
Colonisation of foundations, scour protection and cable protection
636 The introduction of hard substrate into areas of predominantly soft sediments has the potential to alter community composition and biodiversity. This impact is only relevant to the operation and maintenance phase as it takes time for colonisation to establish post construction. The presence of the following projects has the potential to lead to in-combination effects arising from the colonisation of hard structures:
- Tier 2:
– Inch Cape Offshore Wind Farm;
– Neart na Gaoithe Offshore Wind Farm;
– Seagreen 1;
– Seagreen 1A Project;
– Seagreen 1A Export Cable Corridor;
– Eastern Link 1; and
– Eastern Link 2.
- Tier 3:
– Cambois connection.
637 The assessment of effects on diadromous fish from the Proposed Development alone concluded that Annex II diadromous fish species have low vulnerability, high recoverability, and therefore low sensitivity to colonisation of foundations, scour protection and cable protection. This is because, diadromous fish are only likely to interact with the Proposed Development when passing through the area during migrations to and from rivers located on the east coast of Scotland. In most cases, it is expected that diadromous fish are unlikely to utilise the increase in hard substrate from the Proposed Development for feeding or shelter opportunities. Whilst there is potential for increased predation of diadromous fish by marine mammal species attracted to offshore wind farm structures, again impacts on diadromous fish are not anticipated to be significant given diadromous fish spend little time in coastal waters and are unlikely to spend time foraging around wind turbines foundations and therefore are at low risk from increased predation.
638 Whilst the in-combination effect is predicted to be of long-term duration and continuous, it is predicted to be of local spatial extent, of high reversibility and diadromous fish species are assessed as having low sensitivity to the effect.
639 Therefore, it can be concluded that there is no risk of an Adverse Effect on Integrity on the River Tweed SAC as a result of colonisation of foundations, scour protection and cable protection impacts with respect to the Proposed Development acting in-combination with Tier 2 or Tier 3 projects.
Site conclusion
640 In conclusion, with reference to the conservation objectives set for the Annex II diadromous fish features of this site and the information presented sections 12.3, 12.4 and 12.5.4, it can be concluded beyond all reasonable scientific doubt that there will be no Adverse Effect on Integrity on the River Tay SAC in respect of the sea lamprey, river lamprey and Atlantic salmon qualifying interests.
12.5.5 River Dee SAC
European site information
642 At its closest point, the River Dee SAC is located 79.78 km from the Proposed Development array area and 106.57 km from the Proposed Development export cable corridor. The entire length of the River Dee is designated as an SAC due to its importance for salmon, freshwater pearl mussel, and otter (note that otter were screened out in the Berwick Bank Wind Farm Onshore HRA Screening Report (SSE Renewables, 2021b). The river rises in the Cairngorms and flows through southern Aberdeenshire to reach the North Sea at Aberdeen. The site covers an area of 2334.48 ha and is designated for Annex II species including Atlantic salmon and freshwater pearl mussel.
643 Further information on this European site is presented in appendix A.
Conservation objectives
644 Conservation objectives for the River Dee SAC have been developed by NatureScot as part of a Conservation Advice Package (NatureScot, 2020). Conservation objectives for all qualifying features are:
- to ensure that the qualifying features of the River Dee SAC are in favourable condition and make an appropriate contribution to achieving favourable conservation status; and
- to ensure that the integrity of the River Dee SAC is restored by meeting objectives 2a, 2b, 2c for each qualifying feature (and 2d for freshwater pearl mussel).
645 Conservation objectives for freshwater pearl mussel are as follows:
- 2a. Restore the population of freshwater pearl mussel as a viable component of the site;
- 2b. Restore the distribution of freshwater pearl mussel throughout the site;
- 2c. Restore the habitats supporting freshwater pearl mussel within the site and availability of food; and
- 2d. Restore the distribution and viability of freshwater pearl mussel host species and their supporting habitats.
646 Conservation objectives for Atlantic salmon are as follows:
- 2a. Restore the population of Atlantic salmon, including range of genetic types, as a viable component of the site;
- 2b. Restore the distribution of Atlantic salmon throughout the site; and
- 2c. Restore the habitats supporting Atlantic salmon within the site and availability of food.
647 The condition of freshwater pearl mussel at the site was assessed in 2014 and Atlantic salmon condition was assessed in 2011 (NatureScot, 2020). The outcomes of these feature condition assessments were as follows:
- Freshwater pearl mussel: unfavourable declining; and
- Atlantic salmon: favourable maintained.
648 Freshwater pearl mussel has been assessed through NatureScot’s site condition monitoring programme as being in unfavourable condition at River Dee SAC due to the low number and density of freshwater pearl mussels present, low levels of juvenile recruitment, water flow, river morphology, presence of filamentous algae and water quality.
Features and effects for assessment
649 Table 12.20 Open ▸ summarises the LSEs that were identified for the Annex II diadromous fish feature, and dependent species (i.e. freshwater pearl mussel) of the River Dee SAC and the features and effects which have been considered in the assessment of Adverse Effects on Integrity for this site.
Table 12.20: Summary of Features and Effects Considered in the Assessment of Adverse Effects on Integrity for the River Dee SAC
Construction and decommissioning
Injury and/or disturbance from underwater noise and vibration
Atlantic salmon
650 Atlantic salmon which are a Group 2 fish in terms of hearing sensitivity have relatively low sensitivity to underwater noise. The results of project specific modelling, as discussed in paragraphs 283 to 287, indicates that injury and/or mortality to Atlantic salmon can be expected for individuals within approximately 228 m of the piling.
651 A temporary hearing impairment (i.e. TTS), from which animals will recover, was predicted to occur out to a maximum range of 4,161 m for Group 2 fish from piling operations. For concurrent piling, whilst mortality and recoverable injury ranges were unchanged (i.e. 228 m for Group 2 fish) TTS ranges for Group 2 fish may be increased to up to 7.1 km from the piling location for the maximum energy scenario. However, as discussed in paragraph 286, the risk of fish injury will be considerably lower due to hammer energies being considerably lower than the absolute maximum modelled. Additionally, the expected fleeing behaviour of fish from the area affected when exposed to high levels of noise and the soft start procedure, which will be employed for all piling, mean that fish will have sufficient time to vacate the areas where injury may occur prior to noise levels reaching that level.
652 As discussed in paragraph 268, pre-construction UXO clearance may also lead to injury and/or disturbance to sea lamprey. Detonation of UXO would represent a short term (i.e. seconds) increase in underwater noise which will be elevated to levels which may result in injury or behavioural effects on fish. The results of project specific modelling, discussed in paragraphs 288 to 289, indicate that mortality/mortal injury for all fish would occur within a range of 30-45 m from the source following low order detonation (the dominant method of UXO detonation). Higher order detonations may also occur if low order is not successful or unintentionally as part of the low order process. In this case mortality would occur within 410-680 m of the noise source.
653 However, due to the nature of diadromous fish species such as Atlantic salmon being highly mobile and tending to only utilise the environment within the Proposed Development fish and shellfish ecology study area to pass through during migration, significant mortality of Atlantic salmon is not expected.
654 Additionally, available evidence on Atlantic salmon migration patterns from and to Scottish rivers (detailed in section 12.2.5) suggests that Atlantic salmon smolts migrating from rivers take advantage of east flowing currents and cross the North Sea relatively rapidly. Therefore, it is likely that whilst migrating salmon moving to and from the River Dee will pass through the Proposed Development fish and shellfish ecology study area, either in their outward or inward migration, this migration will be rapid, reducing the potential for interaction with the Proposed Development fish and shellfish ecology study area.
655 In contrast, behavioural effects (including startle response, disruption of feeding or avoidance of an area) in response to piling are expected over much larger ranges of 10 km to 20 km, as discussed in paragraphs 296 to 300. Due to the distance between the Proposed Development array area and the coast, these behavioural impacts are unlikely to cause barrier effects between the Proposed Development fish and shellfish ecology study area and the migration routes of Atlantic salmon along the east coast of Scotland, due to the relatively small area around piling events where noise levels are high enough to cause behavioural responses (as shown in Figure 12.1 Open ▸ and Figure 12.2 Open ▸ ).
Freshwater pearl mussel
657 As adult freshwater pearl mussel are confined to freshwater habitats there is no pathway for direct effects to this species during construction and decommissioning as a result of underwater noise impacts.
658 There is potential indirect adverse effects on the larval stage of freshwater pearl mussel if there are adverse effects on the individual salmon (their host species for the first year of their life) to which they are attached. The assessment for Atlantic salmon above in paragraphs 650 to 656 concluded that underwater noise will not lead to significant adverse effects on the population, distribution and supporting habitats of Atlantic salmon, therefore, there will be no significant indirect effects to freshwater pearl mussel. The population of freshwater pearl mussel will be maintained as a viable component of the site, the extent and distribution of freshwater pearl mussel and its natural habitat will not be reduced, and the structure and function of freshwater pearl mussel habitat will be unaffected. Therefore, there will be no significant adverse effects on the qualifying Annex II diadromous fish feature, freshwater pearl mussel of the River Dee SAC as a result of underwater noise impacts during the construction and decommissioning phase.
Conclusion
659 The assessment has concluded that there is no direct spatial overlap between the Proposed Development and the River Dee SAC, so the extent and distribution and structure and function of supporting habitats of the qualifying species will not be reduced. Similarly, the supporting processes on which the habitats of the qualifying species rely will be unaffected. Given the relatively low sensitivity of the qualifying species to underwater noise impacts, the low probability of individuals being present within the ZoI of underwater noise impacts at the time of piling and UXO activities, and the use of soft start procedures allowing individuals to flee areas where they may be exposed to noise levels that would lead to injury, the populations and the distribution of the qualifying species will be maintained.
660 Therefore, it can be concluded that there is no risk of an Adverse Effect on Integrity on the River Dee SAC as a result of underwater noise impacts with respect to construction and decommissioning of the Proposed Development acting alone.
Increased suspended sediment and associated sediment deposition
Atlantic salmon
661 As detailed in section 12.3.2, increases in SSC and associated sediment deposition during the construction and decommissioning phases have the potential to cause behavioural responses (avoidance) in Atlantic salmon. This in turn has the potential to result in barriers to migration.
662 The results of project specific modelling summarised in section 12.3.2, indicate that increases in SSC are predicted to be temporary, short-lived and at levels well below those naturally experienced in estuarine environments. Additionally, Atlantic salmon are expected to have some tolerance to naturally high SSC, given their migration routes typically pass through estuarine habitats which have background SSC which are considerably higher than those expected in the offshore areas of the Proposed Development northern North Sea fish and shellfish ecology study area. As such, no barriers to the migratory patterns of Atlantic salmon are expected.
663 The population of Atlantic salmon will be maintained as a viable component of the site and the extent and distribution of Atlantic salmon will not be reduced. The Proposed Development does not overlap with the River Dee SAC so the extent and distribution and the structure and function of Atlantic salmon habitat will be unaffected. Therefore, there will be no significant adverse effects on the qualifying Annex II diadromous fish feature, Atlantic salmon of the River Dee SAC as a result of increased SSC and sediment deposition impacts during the construction and decommissioning phases.
Freshwater pearl mussel
664 As adult freshwater pearl mussel are confined to freshwater habitats there is no pathway for direct effects to this species during construction and decommissioning as a result of increased SSC and sediment deposition.
665 There is potential for indirect adverse effects on the larval stage of freshwater pearl mussel if there are adverse effects on the individual salmon (their host species for the first year of their life) to which they are attached. The assessment for Atlantic salmon above concluded that increases in SSC and associated sediment deposition will not lead to significant adverse effects on the population, distribution and supporting habitats of Atlantic salmon, therefore there will be no significant indirect effects to freshwater pearl mussel. The population of freshwater pearl mussel will be maintained as a viable component of the site, the extent and distribution of freshwater pearl mussel and its natural habitat will not be reduced, and the structure and function of freshwater pearl mussel habitat will be unaffected. Therefore, there will be no significant adverse effects on the freshwater pearl mussel feature of the River Dee SAC as a result of increased SSC and sediment deposition impacts during the construction and decommissioning phase.
Conclusion
666 The assessment has concluded that there is no direct spatial overlap between the Proposed Development and the River Dee SAC, and so the extent and distribution and structure and function of supporting habitats of the qualifying species will not be reduced. Similarly, the supporting processes on which the habitats of the qualifying species will not be reduced. Given that any increases in SSC are predicted to be temporary, short lived and lower than estuarine levels, there will be no barriers to the migration of the qualifying species. As such, the population and the distribution of the qualifying species will be maintained.
667 Therefore, it can be concluded that there is no risk of an Adverse Effect on Integrity on the River Dee SAC as a result from increased SSC and sediment deposition with respect to the construction and decommissioning of the Proposed Development acting alone.
Operation and maintenance
EMF from subsea electrical cabling
Atlantic salmon
668 As discussed in section 12.4.1, the emission of localised EMFs from the operation of inter-array, interconnector and offshore export cables could potentially interfere with the navigation of diadromous fish species such as Atlantic salmon. However, impacts related to EMF are predicted to be of local spatial extent (i.e. within a few metres of buried cables). Given that Atlantic salmon is a pelagic species, it is unlikely to swim at depths sufficient to detect levels of EMF that would cause behavioural changes during migration. Whilst research shows that undersea power cables can result in altered patterns of salmonid behaviour, these changes are temporary and do not interfere with migration success or population health. Atlantic salmon is therefore deemed to have low sensitivity to, and high recoverability from, EMF.
669 The population of Atlantic salmon will be maintained as a viable component of the site and the extent and distribution of Atlantic salmon will not be reduced. The Proposed Development does not overlap with the River Dee SAC so the extent and distribution and the structure and function of Atlantic salmon habitat will be unaffected. Therefore, there will be no significant adverse effects on the qualifying Annex II diadromous fish feature, Atlantic salmon of the River Dee SAC as a result of EMF from subsea electrical cabling impacts during the operation and maintenance phase.
Freshwater pearl mussel
670 As adult freshwater pearl mussel are confined to freshwater habitats there is no pathway for direct effects to this species during the operation and maintenance phase as a result of EMF.
671 There is potential that adverse effects to host species such as Atlantic salmon could lead to indirect effects to freshwater pearl mussel. The assessment for Atlantic salmon above concluded that EMF will not lead to adverse effects on the population, distribution and supporting habitats of Atlantic salmon, therefore there will be no significant indirect effects to freshwater pearl mussel. The population of freshwater pearl mussel will be maintained as a viable component of the site, the extent and distribution of freshwater pearl mussel and its natural habitat will not be reduced, and the structure and function of freshwater pearl mussel habitat will be unaffected. Therefore, there will be no significant adverse effects on the qualifying Annex II diadromous fish feature, freshwater pearl mussel of the River Dee SAC as a result of EMF from subsea electrical cabling impacts during the construction and decommissioning phase.
Conclusion
672 The assessment has concluded that there is no direct spatial overlap between the Proposed Development and the River Dee SAC, and so the extent and distribution and structure and function of the supporting habitats of the qualifying species will not be reduced. Similarly, the supporting processes on which the habitats of the qualifying species rely will be unaffected. Given any impacts from EMF will be localised and transient and the predicted low sensitivity of the qualifying species to this impact, the population and distribution of the qualifying species will be maintained. Therefore, it can be concluded that there is no risk of an Adverse Effect on the Integrity of the River Dee SAC as a result of EMF impacts with respect to the operation and maintenance of the Proposed Development acting alone.
Colonisation of foundations, scour protection and cable protection
Atlantic salmon
673 As discussed in section 12.4.2, colonisation of foundations, scour protection and cable protection, has the potential to result in increased predation on diadromous fish species by marine mammal species within offshore wind farms. It is not certain exactly to what extent seals utilise offshore wind developments (as discussed in paragraph 346) and therefore effects may be site specific. Assuming that seals do utilise offshore wind developments as foraging areas, Atlantic salmon may be impacted by the increased predation in an area where predation was lower prior to development.
674 It is, however, unlikely that this would result in significant predation on Atlantic salmon. Research has shown that Atlantic salmon smolts spend little time in the coastal waters, and instead quickly make their way to feeding grounds in the north. Due to the evidence that Atlantic salmon tend not to forage in the coastal waters of Scotland (see paragraph 347), it is unlikely that they will spend time foraging around wind turbine foundations and therefore are at low risk of impact from increased predation from seals and other predators.
675 The population of Atlantic salmon will be maintained as a viable component of the site and the extent and distribution of Atlantic salmon will not be reduced, and the structure and function of Atlantic salmon habitat will be unaffected. Therefore, there will be no significant adverse effects on the qualifying Annex II diadromous fish feature, Atlantic salmon of the River Dee SAC as a result of colonisation of foundation, scour protection and cable protection impacts during the operation and maintenance phase.
Freshwater pearl mussel
676 As adult freshwater pearl mussel are confined to freshwater habitats there is no pathway for direct effects to this species during the operation and maintenance phase as a result of colonisation of hard structures.
677 There is potential that adverse effects to the populations of host species such as Atlantic salmon could lead to indirect effects to freshwater pearl mussel. The assessment for Atlantic salmon above concluded that colonisation of structures will not lead to increased predation and therefore, there will be no significant indirect effects to freshwater pearl mussel. The population of freshwater pearl mussel will be maintained as a viable component of the site, the extent and distribution of freshwater pearl mussel and its natural habitat will not be reduced, and the structure and function of freshwater pearl mussel habitat will be unaffected. Therefore, there will be no significant adverse effects on the qualifying freshwater pearl mussel feature of the River Dee SAC as a result of colonisation of foundation, scour protection and cable protection impacts during the construction and decommissioning phase.
Conclusion
678 The assessment has concluded that there is no direct spatial overlap between the Proposed Development and the River Dee SAC, and so the extent and distribution and structure and function of the supporting habitats of the qualifying species will not be reduced. Similarly, the supporting processes on which the habitats of the qualifying species rely will be unaffected. Given the limited interaction between the qualifying species and the Proposed Development significant predation in relation the colonisation of foundations, scour protection and cable protection impact are not expected therefore the population and distribution of the qualifying species will be maintained. Therefore, it can be concluded that there is no risk of an Adverse Effect on Integrity on the River Dee SAC from colonisation of foundations, scour protection and cable protection impacts with respect to operation and maintenance of the Proposed Development acting alone.
Effects in-combination
679 An assessment of in-combination effects upon the qualifying Annex II diadromous fish species of the Tweed Estuary SAC arising from each identified impact is presented in section 12.5.1. Since the results are generic to diadromous fish species and therefore the results of the assessments for each impact apply to the other SACs, full details of the in-combination assessments are not repeated here for the River Dee SAC. The in-combination effects conclusions for the River Dee SAC are summarised below.
Assessment of in-combination effects during construction and decommissioning
Injury and/or disturbance from underwater noise and vibration
680 There is potential for in-combination effects from injury and/or disturbance from underwater noise and vibration to Annex II diadromous fish during the construction phase of the Proposed Development with activities associated with the following projects:
- Tier 2:
– Inch Cape Offshore Wind Farm; and
– Seagreen 1A Project.
- Tier 3:
– There is no information provided regarding UXO clearance for the Cambois connection therefore no meaningful assessment can be made at this time.
681 As discussed in section 12.5.1, effects in-combination, these projects include similar construction activities as those described for the Proposed Development alone in section 12.3.1, including piling to install wind turbine and OSP/Offshore convertor station platform foundations.
682 Neither Inch Cape Offshore Wind Farm nor Seagreen Alpha/Bravo Offshore Wind Farm EIA Reports predicted significant effects on fish and shellfish receptors. Any effects were predicted to be temporary and reversible following cessation of piling activities. Additionally, the injury ranges reported are likely to be conservative as soft start measures will be implemented as part of the Inch Cape Offshore Wind Farm and Seagreen 1A Project construction programmes, which will reduce the risk of injury considerably. Due to the limited range over which injury effects may occur due to piling activities (i.e. tens to hundreds of metres), mitigation to minimise the potential for injury and the minor overlap in construction phases of the Proposed Development and Inch Cape Offshore Wind Farm and Seagreen 1A Project, in-combination effects are not predicted to result in effects of greater significance than as assessed for the Proposed Development alone.
683 The in-combination effect is predicted to be of regional spatial extent, short term duration and intermittent and of high reversibility and diadromous fish species are assessed as having low sensitivity to the effect.
684 Therefore, it can be concluded that there is no risk of an Adverse Effect on Integrity on the River Dee SAC as a result of injury and/or disturbance from underwater noise and vibration with respect to the Proposed Development acting in-combination with Tier 2 projects.
Increased suspended sediment concentrations and associated sediment deposition
685 There is potential for in-combination effects from increased SSC and associated sediment deposition impacts to Annex II diadromous fish during the construction phase of the Proposed Development with activities associated with the following projects:
- Tier 2:
– Inch Cape Offshore Wind Farm (construction phase);
– Seagreen 1A Project (construction phase);
– Seagreen 1 (operation and maintenance phase);
– Seagreen 1A Export Cable (operation and maintenance phase);
– Neart na Gaoithe Offshore Wind Farm (operation and maintenance phase);
– Eastern Link 1 (construction phase);
– Eastern Link 2 (construction phase); and
– Eyemouth disposal site.
- Tier 3:
– Cambois connection (construction and operation and maintenance phases).
686 Any increases in SSC and associated sediment deposition for the Proposed Development alone has been assessed as being of local spatial extent, short term duration with high reversibility of any changes to the baseline. Whilst there may be some temporal overlap between the construction phase of the Proposed Development and the projects listed above, any impacts from increased SSC and associated sediment deposition from these projects will also be of limited spatial extent, short-term duration and they are unlikely to interact with the sediment plumes of the Proposed Development.
687 The in-combination effect is predicted to be of local spatial extent, short term duration and intermittent and of high reversibility and diadromous fish species are assessed as having low sensitivity to the effect. As such, there will be no effect on the ability of diadromous fish to migrate to and from the relevant SACs considered within this RIAA.
688 Therefore, it can be concluded that there is no risk of an Adverse Effect on Integrity on the River Dee SAC as a result of increased SSC and associated sediment deposition impacts with respect to the Proposed Development acting in-combination with Tier 2 or Tier 3 projects.
Assessment of in-combination effects during operation and maintenance
EMF from subsea electrical cabling
689 There is potential for in-combination effects from EMFs from subsea electrical cabling impacts to Annex II diadromous fish during the operation and maintenance phase of the Proposed Development with activities associated with the following projects:
- Tier 2:
– Inch Cape Offshore Wind Farm;
– Neart na Gaoithe Offshore Wind Farm;
– Seagreen 1;
– Seagreen 1A Project;
– Seagreen 1A Export Cable Corridor;
– Eastern Link 1;
– Eastern Link 2.
- Tier 3:
– Cambois connection.
690 Whilst any in-combination effects are predicted to be of long-term duration, continuous and not reversible during the operation of the relevant projects, they are also predicted to be of local spatial extent. Diadromous fish species have been assessed as having low sensitivity and high recoverability from EMF from electrical subsea cabling impacts. This can be concluded as EMF effects are confined to the close vicinity of cables. Diadromous fish species are pelagic, swimming in the water column and therefore less likely to interact with emitted EMF from subsea cables. While the sediments in which cables are buried will not reduce the strength of EMF, the burial of cables does increase the distance between cables and diadromous fish, with greater attenuation of EMFs with greater distance from the cable, thereby reducing the effect of EMFs on diadromous fish. The sensitivity of diadromous fish species is predicted to be low with high recoverability. There is, however, currently no information on the impact that this project will have on diadromous fish, however effects of EMF from the Cambois connection are likely to be similar in magnitude and extent as that discussed for the Proposed Development and the other projects considered in the in combination assessment as set out above.
691 Therefore, it can be concluded that there is no risk of an Adverse Effect on Integrity on the River Dee SAC as a result of EMF impacts with respect to the Proposed Development acting in-combination with Tier 2 or Tier 3 projects.
Colonisation of foundation, scour protection and cable protection
692 The introduction of hard substrate into areas of predominantly soft sediments has the potential to alter community composition and biodiversity. This impact is only relevant to the operation and maintenance phase as it takes time for colonisation to establish post construction. The presence of the following projects has the potential to lead to in-combination effects arising from the colonisation of hard structures:
- Tier 2:
– Inch Cape Offshore Wind Farm;
– Neart na Gaoithe Offshore Wind Farm;
– Seagreen 1;
– Seagreen 1A Project;
– Seagreen 1A Export Cable Corridor;
– Eastern Link 1; and
– Eastern Link 2.
- Tier 3:
– Cambois connection.
693 The assessment of effects on diadromous fish from the Proposed Development alone concluded that Annex II diadromous fish species have low vulnerability, high recoverability, and therefore low sensitivity to colonisation of foundations, scour protection and cable protection. This is because, diadromous fish are only likely to interact with the Proposed Development when passing through the area during migrations to and from rivers located on the east coast of Scotland. In most cases, it is expected that diadromous fish are unlikely to utilise the increase in hard substrate from the Proposed Development for feeding or shelter opportunities. Whilst there is potential for increased predation of diadromous fish by marine mammal species attracted to offshore wind farm structures, again impacts on diadromous fish are not anticipated to be significant given diadromous fish spend little time in coastal waters and are unlikely to spend time foraging around wind turbines foundations and therefore are at low risk from increased predation.
694 Whilst the in-combination effect is predicted to be of long-term duration and continuous, it is predicted to be of local spatial extent, of high reversibility and diadromous fish species are assessed as having low sensitivity to the effect.
695 Therefore, it can be concluded that there is no risk of an Adverse Effect on Integrity on the River Dee SAC as a result of colonisation of foundations, scour protection and cable protection impacts with respect to the Proposed Development acting in-combination with Tier 2 or Tier 3 projects.