Operation and maintenance phase
  1. Alteration of seabed habitat arising from effects on physical processes during the operation and maintenance phase of the Proposed Development in the Firth of Forth Banks Complex MPA may occur as a result of the presence of wind turbine/OSP-Offshore convertor station platform foundations as well as cable protection for cables and cable crossings. Full detail on the project envelope assumptions and maximum design scenario with respect to foundation and cable installation as well as seabed clearance are provided in section 1.4.
  2. This assessment is equivalent to the following pressures identified by JNCC's Advice on Operations for the Firth of Forth Banks Complex MPA for ‘Renewable Energy: offshore wind’ and ‘Power cables: laying burial and protection’ (JNCC, 2018c):

Offshore subtidal sands and gravels

  1. Paragraph 397 describes the magnitude of the alteration of seabed habitat arising from effects of physical processes. The sensitivity of this feature to the impact is dependent upon the species present (FeAST, 2013a). The MarESA finds that both the biotopes with biological components associated with this protected feature are not sensitive to this impact due to the moderately strong water flows that they experience as a result of this high energy baseline environment. Changes in water flow may alter the topography of the habitat and may cause some shifts in abundance. However, a change at the pressure benchmark (increase or decrease) is unlikely to affect biotopes that occur in mid-range flows and biotope resistance is therefore high.
  2. Based on the information presented above, the following can be concluded with respect to the physical and biological attributes of the protected features of the Firth of Forth Banks Complex MPA:
  • The extent and distribution of offshore subtidal sands and gravels is unlikely to change as a result of the alteration of seabed habitat arising from changes to physical processes impact due to the small magnitude and scale of the impact. The extent and distribution are determined by the prevailing hydrodynamic regime which modelling found to be insignificantly affected. Any changes will be highly localised to within the immediate vicinity (i.e. within 200 m) of wind turbine/OSP-Offshore convertor station platform foundations which is unlikely to change the overall extent and distribution of this large-scale feature within the Firth of Forth Banks Complex MPA. This is consistent with the ‘conserve’ objective of the extent and distribution attribute for this feature.
  • The hydrodynamic regime of the site is expected to be insignificantly affected by this impact due to the small magnitude of the impact. As a result of this, the other physical attribute which rely on the hydrodynamic regime for to maintain their distribution and structure, fine scale topography and sediment composition will experience limited changes, only within the immediate vicinity (i.e. within 200 m) of wind turbines where the magnitude of change is greatest however this will not impact upon the overall distribution and structure of these attributes of the protected feature across the Firth of Forth Banks Complex MPA. This is consistent with the ‘conserve’ objective of the supporting processes attribute for this feature.
  • The key influential species which define this feature are not sensitive to these pressures, as discussed in paragraph 399. The high energy hydrodynamic regime which defined this protected features ensures that the species which have colonised it are resilient to natural variation in regime and therefore will have a high resilience to the small scale changes which characterise this impact, any potential alteration of habitat will be in the immediate vicinity (i.e. within 200 m) of the infrastructure which may cause species to move out of this zone if possible shifting distribution however this will shift back following decommissioning.
  • The reasoning above also applies to the characteristic communities which occupy this protected feature. The community relies upon the specific sediment composition of the protected feature which will be largely maintained throughout the operation and maintenance phase. The limited zone of influence associated with this impact and the low magnitude of change helps support the natural reliance which is exhibited by the communities of this feature.
  • In relation to the functions of this protected feature, the limited extent of the influence of this impact largely protects the climate regulation function of the sediments in this feature. Additionally, the preservation of the hydrodynamic regime of the site ensure that the productivity of the feature is maintained. The nutritional value of the site as a spawning ground for commercial valuable is largely preserved by a combination of the above reasoning, the continues productivity of the site ensuring food for spawning species and the limited extent of the impact which ensures the majority of the sands and gravels which these species prefer are still available to carry out this function. This is consistent with the ‘recover’ objective of the structure and function attribute for this feature.
    1. Volume 2, chapter 8 of the Offshore EIA Report concluded that due to the limited extent and overall magnitude of the impact of alteration of seabed habitat arising from effects of physical processes, and the relatively small proportion of the protected features to be affected during operation and maintenance, the magnitude of the impact on the features of the Firth of Forth Banks Complex MPA was low. The offshore subtidal sands and gravels protected feature of the Firth of Forth Banks Complex MPA is considered to be of low vulnerability, high recoverability and national importance and therefore was considered to have a negligible sensitivity. Therefore, the significance of effect was considered to be negligible adverse significance.
    2. Based on the information presented here, it can be concluded that alteration of seabed habitat arising from effects of physical processes during the Proposed Development operation and maintenance phase will not lead to a significant risk of hindering the achievement of the overall conservation objective for the offshore subtidal sands and gravels feature of the Firth of Forth Banks Complex MPA (i.e. “recover to favourable condition”) for the following reasons:
  • The alteration of seabed habitat arising from changes to physical processes is predicted to affect a small proportion of the offshore subtidal sands and gravels feature during the operation and maintenance phase, such that the extent and distribution of the protected feature will remain stable; and
  • The structures and functions, quality, and the composition of characteristic communities will remain in (or recover to) a condition which is healthy and not deteriorating. The impact on the seabed will be limited in spatial scale, only in the immediate vicinity (i.e. within 200 m) of wind turbines and will revert to baseline conditions following decommissioning. The key and influential species are predicted to shift their distribution due to these changes in conditions. These communities will be supported by an undisturbed hydrodynamic regime which will continue to form the fine scale features of the MPA.

Shelf banks and mounds

  1. Paragraph 397 describes the magnitude of the alteration of seabed habitat arising from changes to physical processes. The biotopes associated with this feature are the same as those described in offshore subtidal sands and gravels therefore the sensitivity of these biotopes to the impact is the same as described in paragraph 399.
  2. Based on the information presented above, the following can be concluded with respect to the physical and biological attributes of the protected features of the Firth of Forth Banks Complex MPA:
  • The extent and distribution of this protected feature is based on the prevailing hydrodynamic regime which is not expected to change across the Firth of Forth Banks Complex MPA. They are expected in the immediate vicinity (i.e. within 200 m) of infrastructure. This limits the scale of the impact and ensures that the majority of the feature is maintained across the MPA. This is consistent with the ‘conserve’ objective of the extent and distribution attribute for this feature.
  • The supporting processes, the tidal currents, and overall littoral currents, which create this feature within the Firth of Forth Banks Complex MPA will be minimally affected by this impact and only within the immediate vicinity (i.e. within 200 m) of the infrastructure enabling the maintenance of these processes across the large majority of this feature.
  • The physical nature of this large-scale seabed feature is created and maintained by the strong currents and mobile sediments which characterise the wider MPA environment. The maintenance of the hydrodynamic regime of the MPA and the limited scale of the change in sediment transport, ensuring the necessary sands and gravels can be delivered to the feature, support the processes which maintain the physical nature of this feature. This is consistent with the ‘conserve’ objective of the supporting processes attribute for this feature.
  • The function of this feature is very similar to that of offshore subtidal sands and gravels with the effect of this impact discussed in paragraph 400. This is consistent with the ‘conserve’ objective of the structure and function attribute for this feature.
    1. Volume 2, chapter 8 of the Offshore EIA Report concluded that due to the limited extent of the alteration of seabed habitat arising from effects of physical processes impact, and the minor proportion of the protected features to be affected during operation and maintenance phase, the magnitude of the impact on the features of the Firth of Forth Banks Complex MPA was low. The shelf banks and mounds protected feature of the Firth of Forth Banks Complex MPA is considered to be of low vulnerability, high recoverability and national importance and therefore was considered to have a negligible sensitivity. Therefore, the significance of effect was considered to be negligible adverse significance.
    2. Based on the information presented here, it can be concluded that alteration of seabed habitat arising from effects of physical processes during the Proposed Development operation and maintenance phase will not lead to a significant risk of hindering the achievement of the overall conservation objective for this feature of the Firth of Forth Banks Complex MPA (i.e. “maintain in favourable condition”) for the following reasons:
  • While the alteration of seabed habitat arising from effects of physical processes is predicted to affect a high limited area of the habitat feature during the operation and maintenance phase the extent and distribution of the protected feature remaining stable;
  • The function will remain in a condition which is healthy and not deteriorating. The limited extent of the change and the maintenance of the physical nature of the feature will ensure that it continues to support its characteristic biological communities and their use of the site for feeding, courtship, spawning, or use as nursery ground; and
  • The supporting processes which enable the formation of these large features and create the necessary environmental conditions to enable its structure and function will be maintained.

Ocean quahog aggregations

  1. Paragraph 397 describes the magnitude of the alteration of seabed habitat arising from effects of physical processes. The MarESA suggests that ocean quahogs are not sensitive to changes to tidal currents and wave exposure changes due to the range of water flow regimes they are found in as a result of their preference for a range of sediment types (Tyler-Walters and Sabatini, 2017). They are however vulnerable to severe storm events which can damage them or wash them into unfavourable habitats. The FeAST tool however concludes that they have a low sensitivity to tidal current change depending on whether the flow is increased or decreased and to what magnitude. A sustained increase could damage larva or juveniles and prevent them from settling, impacting upon recruitment. Decreases in flow could reduce food availability through suspension feeding, therefore ocean quahogs would have to switch to deposit feeding. The FeAST tool also suggests that ocean quahog have a medium sensitivity to wave exposure change as strong wave action may cause changes to the substrate. An increase in wave exposure could also damage or cause the withdrawal of the siphons, which reduces their ability to feed, and growth could be compromised as well as potentially causing physical damage.
  2. Based on the information presented above, the following can be concluded with respect to the physical and biological attributes of the protected features of the Firth of Forth Banks Complex MPA:
  • The extent and distribution of ocean quahog aggregations is determined by the availability of suitable habitat such as that provided by the offshore subtidal sands and gravels feature within the Firth of Forth Banks Complex MPA. The conservation of this feature is discussed in paragraph 400, which also applied the conservation of the supporting habitats of this feature. This is consistent with the ‘conserve’ objective of the extent and distribution attribute for this feature.
  • The hydrodynamic regime of the site will be conserved at its pre-construction baseline across the majority of the MPA, with the exception of within 200 m of the infrastructure where the peak flow is redirected, and sediment transport and residual currents changes by a maximum of ±15%. This is consistent with the ‘conserve’ objective of the supporting processes attribute for this feature.
  • The structure of the ocean quahog aggregations feature across the MPA is currently unknown (JNCC, 2018b). Based on the site-specific surveys undertaken for the Proposed Development, the ocean quahog individuals recorded were mostly juveniles with a few mature specimens. The low magnitude of the changes to these physical processes and the resulting limited extent of the effects will reduce the potential for wide scale change. This ensures ocean quahog at all stages of their life cycle will have the opportunity to move out of this environment if it does not suit them, maintaining their population structure throughout the MPA. This is consistent with the ‘conserve’ objective of the structure and function attribute for this feature.
  • The function of ocean quahog aggregations is yet to be determined (JNCC, 2018b) however through the maintenance of the other attributes of this feature, described above, many of the potential functions can continue. For examples maintaining the population structure ensure individuals are still available for scientific study and as a prey species across the MPA. This is consistent with the ‘conserve’ objective of the structure and function attribute for this feature.
    1. Volume 2, chapter 8 of the Offshore EIA Report concluded that due to the limited extent of the alteration of seabed habitat arising from effects of physical processes impact, and the minor proportion of the protected features to be affected during operation and maintenance, the magnitude of the impact on the features of the Firth of Forth Banks Complex MPA was low. The ocean quahog protected feature of the Firth of Forth Banks Complex MPA is considered to be of low vulnerability, high recoverability and national importance and therefore was considered to have a low sensitivity. Therefore, the significance of effect was considered to be negligible adverse significance.
    2. Based on the information presented here, it can be concluded that alteration of seabed habitat arising from effects of physical processes during the Proposed Development operation and maintenance phase will not lead to a significant risk of hindering the achievement of the overall conservation objective for the ocean quahog aggregations feature of the Firth of Forth Banks Complex MPA (i.e. “recover to favourable condition”) for the following reasons:
  • Alteration of seabed habitat arising from changes to physical processes is predicted to affect only a small proportion of supporting habitat for ocean quahog during the operation and maintenance phase, thus ensuring that the quality and quantity of ocean quahog habitat is maintained. Whilst some ocean quahog individuals may be directly affected by localised and minor changes to physical processes as a result of the presence of offshore wind farm infrastructure, this is predicted to be to an extent that will not affect the composition of its population in terms of number, age and sex ratio or its ability to thrive in the future.

Wee Bankie key geodiversity area (moraines)

  1. Paragraph 397 describes the magnitude of the alteration of seabed habitat arising from changes to physical processes. Based on the information presented above, the following can be concluded with respect to the physical and biological attributes of the moraines protected feature of the Firth of Forth Banks Complex MPA:
  • The extent and distribution of this protected feature will be minimally affected by this impact due to its limited area of influence, only in the vicinity of infrastructure such as wind turbine/OSP-Offshore convertor station platform foundations. The processes which currently determine the structure and function of other protected features within the MPA do determine the extent and distribution of this feature as a relic, therefore this disruption to processes such as tidal and wave current is unlikely to change the extent and distribution of this feature. This is consistent with the ‘conserve’ objective of the structure and function attribute for this feature.
  • The structure of this feature, submarine ridges formed of glacial till, will be minimally affected by this impact due to its limited extent, as described above. Should changes to conditions result in the erosion, deposition or change in sediment structure the feature could not recover as the glacial processes which form this feature are no longer active, however due to the low magnitude of the changes predicted (deemed to be negligible in volume 2, chapter 7 of the Offshore EIA Report) there is not expectation of damage to the structure of this large-scale feature. This is consistent with the ‘conserve’ objective of the structure and function attribute for this feature.
  • The functions of the feature will experience minimal disruption due to the limited area of effect from the impact. This will ensure that the undisturbed feature will remain available for scientific study. Additionally, as this impact will not change the sediment types provided as a result of this feature, its function as a prominent and important habitat within the Firth of Forth Banks Complex MPA will be maintained. This is consistent with the ‘conserve’ objective of the structure and function attribute for this feature.
    1. Based on the information presented here, it can be concluded that alteration of seabed habitat arising from effects of physical processes during the Proposed Development operation and maintenance will not lead to a significant risk of hindering the achievement of the overall conservation objective for the Wee Bankie Key Geodiversity Area feature of the Firth of Forth Banks Complex MPA (i.e. “maintain in favourable condition”) for the following reasons:
  • The alteration of seabed habitat arising from changes to physical processes is predicted to affect a very small area of the Proposed Development (only within 200 m of wind turbine/OSP-Offshore convertor station platform foundations and cable protection for cables and cable crossings) and therefore a very small proportion of the protected feature within the MPA during the operation and maintenance phase. Therefore, its extent, component elements and integrity as a relict feature will be maintained;
  • The structure and function will remain largely unimpaired by the activities as only a small proportion of the feature will be affected; and
  • The surface of the feature will remain sufficiently unobscured as a result of changes to physical processes during the operation and maintenance phase.

Impacts to Benthic Invertebrates from EMF

Operation and maintenance phase
  1. The impact to benthic invertebrates from EMF during the operation and maintenance phase of the Proposed Development in the Firth of Forth Banks Complex MPA may occur as a result of the presence of inter-array, interconnector and offshore export cables leading to localised EMF.
  2. This assessment is equivalent to the following pressures identified by JNCC's Advice on Operations for the Firth of Forth Banks Complex MPA for ‘Renewable Energy: offshore wind’ and ‘Power cables: laying burial and protection’ (JNCC, 2018c):
  • Electromagnetic changes.
    1. Table 1.50   Open ▸ presents the maximum design scenario for cables within the Firth of Forth Banks Complex MPA during the operation and maintenance phase.

 

Table 1.50:
Summary of the Extent of Cables within the Firth of Forth Banks Complex MPA (as a Whole, and for the Component Sites) during the Operation and Maintenance Phase

Table 1.50: Summary of the Extent of Cables within the Firth of Forth Banks Complex MPA (as a Whole, and for the Component Sites) during the Operation and Maintenance Phase

1 Calculated as sum of 30.81% of the 1,225 km of inter-array cables and 94 km of interconnector cables.2 Calculated as 14.26 km multiplied by 8, for the eight planned offshore export cables.

3 Calculated as 30.81% of the 413 km2 total on the basis of the overlap with the Scalp and Wee Bankie (see paragraph 188).

4 Calculated as 69.19% of the 413 km2 total on the basis of the overlap with the Berwick Bank (see paragraph 188).

 

  1. On the basis of the assumptions outlined in paragraph 189, there may be up to 527 km of active cable within the Firth of Forth Banks Complex MPA during the operation and maintenance phase. Of this total, up to 127 km may occur within the Scalp and Wee Bankie section of the MPA and up to 400 km within the Berwick Bank part of the MPA. This assessment considers the effects of cables active during the operation and maintenance phase, which could result in the emittance of a detectable EMF, on the attributes and targets for the offshore subtidal sand and gravels and ocean quahog aggregations therefore the assessment has been subdivided according to these feature types.
  2. EMF comprise both the electrical fields, measured in volts per metre (V/m), and the magnetic fields, measured in microtesla (µT) or milligauss (mG). Background measurements of the magnetic field are approximately 50 μT in the North Sea, and the naturally occurring electric field in the North Sea is approximately 25 μV/m (Tasker et al., 2010). It is common practice to block the direct electrical field using conductive sheathing, meaning that the only EMFs that are emitted into the marine environment are the magnetic field (B) and the resultant induced electrical field (iE). It is generally considered impractical to assume that cables can be buried at depths that will reduce the magnitude of the B field, and hence the sediment-sea water interface iE field, to below that at which these fields could be detected by certain marine organisms on or close to the seabed (Gill et al., 2005; Gill et al., 2009). By burying a cable, the magnetic field at the seabed is reduced due to the distance between the cable and the seabed surface as a result of field decay with distance from the cable (CSA, 2019).
  3. A variety of design and installation factors affect EMF levels in the vicinity of the cables. These include current flow, distance between cables, cable insulation, number of conductors, configuration of cable and burial depth. The flow of electricity associated with an alternating current (AC) cable (proposed for the Proposed Development) changes direction (as per the frequency of the AC transmission) and creates a constantly varying electric field in the surrounding marine environment (Huang, 2005).
  4. The strength of the magnetic field (and consequently, induced electrical fields) decreases rapidly horizontally and vertically with distance from source. A recent study conducted by CSA (2019) found that inter-array and offshore export cables buried between depths of 1 m to 2 m reduces the magnetic field at the seabed surface four-fold. For cables that are unburied and instead protected by thick concrete mattresses or rock berms, the field levels were found to be similar to buried cables.
  5. CSA (2019) investigated the link relationship between voltage, current, and burial depth, the results of which are presented in Table 1.51   Open ▸ which shows the magnetic and induced electric field levels expected directly over the undersea power cables and at distance from the cable for varying cable types. Directly above the cable, EMF levels decrease as you move away from the seafloor to 1 m above the cable, while as you move laterally away from the cable, at distances greater than 3 m), the magnetic fields at the seafloor and at 1 m above the seafloor are comparable.

 

Table 1.51:
Typical EMF Levels over AC Undersea Power Cables from Offshore Wind Energy Projects (CSA, 2019)

Table 1.51: Typical EMF Levels over AC Undersea Power Cables from Offshore Wind Energy Projects (CSA, 2019)

 

Offshore subtidal sands and gravels

  1. On the basis of the assumptions outlined in paragraph 190, all of the cables within the MPA (i.e. 527 km) could occur entirely within the offshore subtidal sands and gravels feature of the MPA. EMF would only be emitted during the operation and maintenance phase of the Proposed Development, covering a 35-year period, when the Proposed Development is producing and exporting electricity. Prior to or after the operation phase there is no risk of EMF.
  2. Gill and Desender (2020) summarised current research on the impact of EMF emissions on organisms and also acknowledged that relatively little is known about the effects of EMF on invertebrates such as those common in benthic communities. This is supported by a recent evaluation of knowledge of the impacts of EMF on invertebrates which concluded, globally, no direct impact on survival has been identified in the literature (Hervé, 2021). Furthermore, the methods to assess benthic invertebrates are variable therefore creating the same variability in results, as well as, in some cases, contradiction (Hutchinson et al., 2020b). Some studies found that benthic communities which grow along cable routes were generally similar to those in the nearby area (Gill and Desender, 2020). These communities however are not exposed to the maximum EMF emissions due to cable burial creating a physical distance between the cable and the seabed surface, although the EMF which reaches the surface is measurable at biologically relevant scales at the seabed and in the water column (Hutchinson et al., 2020b).
  3. Experimental evidence has demonstrated that exposure to EMF did not change the distribution of the ragworm Hediste diversicolor (Jakubowska et al., 2019). Experimental evidence has however demonstrated magnetoreception in marine molluscs and arthropods and biogenic magnetite has been known to occur in marine molluscs for over five decades (Normandeau, 2011). Magneto-receptive and electro-receptive species have evolved to respond to small changes in the Earth’s geomagnetic fields and bioelectric fields making the presence of an EMF more perceivable to receptive species (Hutchinson et al., 2020b). Reported sensitivities to electric fields for invertebrates range from around 3 mV/cm to 20 mV/cm (Steullet et al., 2007).
  4. Normandeau (2011) summarises that despite these sensitivities no direct evidence of impacts to invertebrates from undersea cable EMFs exists. What is known about invertebrate sensitivities to EMF does provide some guidance for considering potential impacts. Potential impacts would depend on the sensory capabilities of a species, the life functions that its magnetic or electric sensory systems support, and the natural history characteristics of the species. Life functions supported by the electric and magnetic sense indicate that species capable of detecting magnetic fields face potential impacts different from those that detect electric fields.
  5. Research regarding the impact of EMF on invertebrates still has a number of knowledge gaps which hinder our ability to fully understand the effects. Hervé (2021) identifies that establishing the impact on groups such as Molluscs is highly underdeveloped, the impact on species relative to the strength of the EMF as well as the impact of different types of cable are key knowledge gaps.
  6. Based on the information presented above, the following can be concluded with respect to the physical attributes of the protected features of the Firth of Forth Banks Complex MPA:
  • The impact of EMF will not result in any physical changes to the offshore subtidal sands and gravels feature including on extent and distribution, water quality, sediment composition, hydrodynamic regime and the supporting processes which contribute to the latter physical attributes of this feature. The presence of EMF is unable to affect the deposition or dynamics of the sediments within the MPA beyond the initial installation of the cables (this impact is assessed starting in paragraph 199).
    1. Offshore subtidal sands and gravels biotopes were identified in the site-specific benthic surveys (volume 2, chapter 8 of the Offshore EIA Report, and included Abra prismatica, Bathyporeia elegans and polychaetes in circalittoral fine sand (SS.SSa.CFiSa.ApriBatPo) and Echinocyamus pusillus, Ophelia borealis and Abra prismatica in circalittoral fine sand (SS.SSa.CFiSa.EpusOborApri). The Marlin database shows that these biotopes currently do not have any evidence to support any conclusions being made regarding their sensitivity to electromagnetic changes. Paragraphs 422 to 425, however, suggest that benthic invertebrates as a whole have been found to be unaffected by EMF when they have been tested, although they do also highlight that this is subject is under-researched.
    2. Based on the information presented above, the following can be concluded with respect to the ecological attributes of the offshore subtidal sands and gravels feature of the Firth of Forth Banks Complex MPA:
  • With respect to the key influential species that have an important role in determining the structure and function of the offshore subtidal sands and gravels feature, current research would suggest that the presence of EMF, should it be detectable, would not prevent these species from performing their ecological role.
  • The presence and spatial distribution of the characteristic communities will be maintained across the Firth of Forth Banks Complex MPA. As discussed in paragraph 422, benthic communities have been found to grow along cable corridors which are similar to those of the surrounding environment which would support the conclusion that characteristic communities are likely to maintain their distribution. Should any species not yet known to be sensitive to EMF be affected the impact is likely to be highly localised and limited in extent by the burial of the cables (as demonstrated in Table 1.51   Open ▸ ). As part of the designed in measures, detailed in Table 1.36   Open ▸ , cable burial depth will be monitored to ensure that only the declared amount of new habitat is created. This measure will also ensure that EMF remains dampened by burial throughout the operation and maintenance phase.
  • The function of the offshore subtidal sands and gravel feature, which is defined by its biological productivity, nutrition provision and climate regulation, will be maintained throughout the operation period of the Proposed Development. EMF is unlikely to impact the communities found within the Firth of Forth Banks Complex MPA as well as the larger physical conditions found within the feature therefore the function of the feature is highly likely to be preserved. Should changes along the cable corridors occur they are likely to be highly localised due to the burial of the cable reducing the levels of EMF and therefore limiting the response of any sensitive species.
    1. Volume 2, chapter 8 of the Offshore EIA Report concluded that due to the temporary, reversible and continuous nature of the impact of EMF on benthic invertebrates during operation and maintenance is negligible in regard to the subtidal sands and gravel feature. The offshore subtidal sands and gravels protected feature of the Firth of Forth Banks Complex MPA is considered to be of low vulnerability, high recoverability and national importance and therefore was considered to have a low sensitivity. Therefore, the significance of effect was considered to be negligible adverse significance, which is not significant in EIA terms.
    2. Based on the information presented here, it can be concluded that temporary habitat disturbance during the Proposed Development construction phase will not lead to a significant risk of hindering the achievement of the overall conservation objectives (i.e. “recover to favourable condition”) for this feature of the Firth of Forth Banks Complex MPA for the following reasons:
  • The of EMF on benthic invertebrates is predicted to have a negligible effect on the offshore subtidal sands and gravels feature during the operation and maintenance phase, the extent and distribution of the protected feature will remain stable following the operation and maintenance phase; and
  • The structures and functions, quality, and the composition of characteristic communities will remain in a condition which is healthy and not deteriorating. The key and influential species are not predicted to be affected, with no change to characteristic communities throughout the operation and maintenance phase; as supported by current research in this field. These communities will be supported by an undisturbed hydrodynamic regime which will continue to form the fine scale features of the MPA.

Ocean quahog aggregations

  1. On the basis of the assumptions outlined in paragraph 190, and for the purposes of this assessment, it is assumed that all of the temporary habitat disturbance predicted within the MPA (i.e. 527 km) could occur entirely within supporting habitat for ocean quahog aggregations ( Table 1.50   Open ▸ ). EMF would only be emitted during the operation and maintenance phase of the Proposed Development, covering a 35-year period, when the Proposed Development is producing and exporting electricity. Prior to or after the operation phase there is no risk of EMF.
  2. An overview of the findings of current research on the impact of EMF on benthic invertebrates can be found in paragraphs 422 to 425. Ocean quahogs have not specifically been assessed for this impact and the Marlin database identified this species as having on evidence to support a conclusion its sensitivity to electromagnetic changes.
  3. Based on the information presented above, the following can be concluded with respect to the physical attributes of the ocean quahog aggregations feature of the Firth of Forth Banks Complex MPA:
  • The impact of EMF is unable to impact physical attributes of this feature such as substrate type as it has no influence on the hydrodynamic regime and other supporting processes.
  • The structure of ocean quahog refers to the densities and ages classes of individuals from a population within a site. Within the MPA, average density of ocean quahog is lower than documented averages from the northern North Sea (JNCC, 2018b). The population structure of the site is currently unknown, although the baseline surveys conducted for the Proposed Development EIA found one juvenile (size of 0.2 cm and estimated to be less than a year old) and one adult (size of 11 cm and an estimated age of 193 years; paragraph 182) within the part of the Proposed Development array area that overlaps with the MPA. For the population to recover, the conservation objectives seek to encourage recruitment and preserve juveniles already in the MPA. Current research on this impact indicates that the population structure of ocean quahogs within the Firth of Forth Banks Complex MPA is highly unlikely to change as a result of this impact, due to the limited amount of EMF which they will be exposed to as a result of burial ( Table 1.51   Open ▸ ). As part of the designed in measures, detailed in Table 1.36   Open ▸ , cable burial depth will be monitored to ensure that only the declared amount of new habitat is created. This measure will also ensure that EMF remains dampened by burial throughout the operation and maintenance phase.
    1. The ecological attributes which characterise the ocean quahog aggregations protected features have not been assessed for the impact of EMF in current research.
    2. Based on the information presented above, the following can be concluded with respect to the ecological attributes of the protected features of the Firth of Forth Banks Complex MPA:
  • Ocean quahog aggregations are thought to play a role in carbon cycling and nutrient transport within the MPA (although there is currently no direct evidence) as well as acting as direct records of climate and environmental change. Current research, which has a number of knowledge gaps, indicates that ocean quahogs are likely to be affected by EMF and therefore changes to their ability to perform their ecological function is unlikely to occur.
  • As mentioned in the discussion of the physical attribute of the site (paragraph 433) the hydrodynamic regime of the MPA will not be impact by EMF. The stability of these conditions will continue to provide the same sediment type and volume to the MPA enabling the maintenance of the supporting habitats of ocean quahog aggregations. This is consistent with the ‘conserve’ objective of the structure and function attribute for this feature.
    1. Volume 2, chapter 8 of the Offshore EIA Report concluded that due to the temporary, reversible, and continuous nature of the impact of EMF on ocean quahogs results in the magnitude of the impact on the features of the Firth of Forth Banks Complex MPA to be negligible. The ocean quahog protected feature of the Firth of Forth Banks Complex MPA is considered to be of low vulnerability, high recoverability and national importance and therefore was considered to have a low sensitivity. Therefore, the significance of effect was considered to be negligible adverse significance, which is not significant in EIA terms.
    2. Based on the information presented here, it can be concluded that the impact of EMF during the Proposed Development operation and maintenance phase will not lead to a significant risk of hindering the achievement of the overall conservation objective for the ocean quahog aggregations feature of the Firth of Forth Banks Complex MPA (i.e. “recover to favourable condition”) for the following reasons:
  • The impact of EMF on ocean quahogs is unlikely to affect ocean quahog during the operation and maintenance phase, with the quality and quantity of ocean quahog habitat to be maintained throughout. Ocean quahog individuals are unlikely to be affected by EMF, this is predicted to not affect the composition of its population in terms of number, age and sex ratio or its ability to thrive in the future.

1.7.2.    Cumulative Effects Assessment

  1. The Cumulative Effects Assessment (CEA) considers the impact associated with the Proposed Development on the Firth of Forth Banks Complex MPA together with other relevant plans, projects and activities. The projects selected as relevant to the CEA for this MPA Assessment are based upon the results of a screening exercise (see volume 3, appendix 6.3 of the Offshore EIA Report). Each project or plan has been considered on a case-by-case basis for screening in or out of this MPA Assessment based upon data confidence, effect-receptor pathways and the spatial/temporal scales involved.
  2. In undertaking the CEA for the Proposed Development, it is important to bear in mind that other projects and plans under consideration will have differing potential for proceeding to an operational stage and hence a differing potential to ultimately contribute to a cumulative impact alongside the Proposed Development. Therefore, a tiered approach has be adopted. This provides a framework for placing relative weight upon the potential for each project/plan to be included in the CEA to ultimately be realised, based upon the project/plan’s current stage of maturity and certainty in the projects’ parameters. The tiered approach which will be utilised within the Proposed Development CEA employs the following tiers:
  • tier 1 assessment – Proposed Development (Berwick Bank Wind Farm offshore) with Berwick Bank Wind Farm onshore;
  • tier 2 assessment – All plans/projects assessed under Tier 1, plus projects which became operational since baseline characterisation, those under construction, those with consent and those for which an application for consent has been submitted but not yet determined;
  • tier 3 assessment – All plans/projects assessed under Tier 2, plus those projects which are in scoping or which have a Scoping Opinion; and
  • tier 4 assessment – All plans/projects assessed under Tier 3, which are reasonably foreseeable, plus those projects likely to come forward where an AfL has been granted.
    1. The specific projects scoped into the CEA for the MPA Assessment, are outlined in Table 1.52   Open ▸ and shown in Figure 1.16   Open ▸ .

 

Table 1.52:
List of Other Projects and Plans Considered Within the CEA for the MPA Assessment

Table 1.52: List of Other Projects and Plans Considered Within the CEA for the MPA Assessment

 


Figure 1.16:
Other Projects/Plans Screened into the Cumulative Effects Assessment for the MPA Assessment

Figure 1.16: Other Projects/Plans Screened into the Cumulative Effects Assessment for the MPA Assessment

  1. Within the Firth of Forth Banks Complex MPA, and over the lifetime of the Proposed Development, four projects overlap both spatially and temporally: Seagreen 1; Seagreen 1A Project; Seagreen 1A Export Cable Corridor; and the Cambois connection. These four projects have been considered within the cumulative assessment for additive effects (i.e. temporary habitat disturbance, long term habitat loss, and colonisation of hard structures).
  2. Seagreen 1 and the Seagreen 1A Project, together, overlap with 152,800 km2 of the Firth of Forth Banks Complex MPA which is 7.17% of the MPAs total area (Marine Scotland, 2014b). The Seagreen 1A Export Cable Corridor overlaps with 81.84 km2 of the Firth of Forth Banks Complex MPA which is 3.8% of the MPAs total area (Seagreen Wind Energy Ltd., 2021). The Cambois connection will have up to four cables, each up to potentially 63 km, within the MPA (i.e. a total of up to 252 km of cable).
  3. The neighbouring projects of Inch Cape offshore wind farm and Neart na Gaoithe offshore wind farm do not spatially overlap with the Firth of Forth Banks Complex MPA (located 1.24 km and 3.22 km from the Firth of Forth Banks Complex MPA, respectively). They do, however, have the potential to overlap temporally with the Proposed Development and have therefore been considered within the cumulative assessment for synergistic/interactive effects (i.e. increased SSC and alteration of seabed habitat resulting from changes in physical processes).
  4. A description of the significance of cumulative effects upon features of the MPA arising from each identified impact within the Firth of Forth Banks Complex MPA is given below.

Temporary Habitat Disturbance

Tier 2

Construction phase
  1. The construction phase of the Proposed Development temporally overlaps with the construction phase of Seagreen 1A Project and the operation and maintenance phase of the Seagreen 1A Project and Seagreen 1, and the operation and maintenance phase only of the Seagreen 1A Export Cable Corridor (construction of this project is due to complete in June 2024 which is before the earliest construction start date for the Proposed Development of February 2025).
  2. Table 1.53   Open ▸ shows that cumulative temporary habitat disturbance of up to 29.28 km2 may occur within the Firth of Forth Banks Complex MPA as a result of Tier 2 projects, equating to 1.37% of the total area of the MPA as a result of the construction of the Proposed Development and the construction of the Seagreen 1. The temporary habitat disturbance values for Seagreen 1A Project are a combination of the values for Seagreen 1A Project and Seagreen 1 because they were consented together and the MPA Assessment for these projects, undertaken by Marine Scotland, does not provide a breakdown of the proportion of each impact which can be attributed to each project (Marine Scotland, 2014b). Additionally these values are composed of disturbance within both the Scalp and Wee Bankie and Montrose Bank components of the MPA. The Proposed Development does not coincide with Montrose Bank therefore there will be no cumulative impact with Seagreen 1 within this part of the MPA. Individual disturbance values for each MPA section are not provided in the Seagreen 1 (including Seagreen 1A Project) MPA Assessment (Marine Scotland, 2014b). As a result, it is not possible to apportion and combine with the numbers from the Proposed Development to get a specific value for the disturbance in Scalp and Wee Bankie, therefore the actual value for disturbance will be less than the value proposed.
  3. With regards to the Seagreen 1A Export Cable Corridor, the MPA Assessment by the developers of the project (Seagreen Wind Energy Ltd., 2021) states that submarine cables generally do not require high levels of routine maintenance other than confirming that there are no areas of exposure or significant movements indicative of external influence. Some level of maintenance activities may be required (e.g. repair and reburial), however these are not quantified in the application documents, although it is states that they are expected to be less than installation and anticipated to be minimal (Seagreen Wind Energy Ltd., 2021).

 

Table 1.53:
Cumulative Temporary Habitat Disturbance Within the Firth of Forth Banks Complex MPA for the Proposed Development and Other Tier 2 Projects Included in the Cumulative Assessment

Table 1.53: Cumulative Temporary Habitat Disturbance Within the Firth of Forth Banks Complex MPA for the Proposed Development and Other Tier 2 Projects Included in the Cumulative Assessment

 

  1. Activities resulting in temporary habitat disturbance will occur intermittently throughout construction period of up to up to 96 months, with only a proportion of the total maximum area of temporary habitat disturbance occurring at any one time. The same can be assumed for the construction of the Seagreen 1A Project, the construction period of which will be nearing the final stages of completion as the Proposed Development enters its construction phase. As such, only a small proportion of the Seagreen 1A Project’s temporary habitat disturbance within the MPA will contribute to the cumulative impact.
  2. There is no spatial overlap between the Proposed Development and Seagreen 1A Project, or Seagreen 1A Export Cable Corridor ( Figure 1.16   Open ▸ ), therefore there will be no repeat disturbance to the same areas of seabed within any part of the MPA as a result of these projects. This will support the recovery processes for the ecological communities affected by temporary habitat disturbance as recovery will not be delayed by further physical disturbance and the recovery timescales described for the projects alone will apply.
  3. Furthermore, the MPA assessment undertaken for Seagreen 1 and the Seagreen 1A Project, together, concluded that the shelf banks and mounds large-scale features and the Wee Bankie Key Geodiversity Area (Moraines) were unlikely to be adversely affected by the project due to the small scale of the impact footprints in relation to these large-scale features (Marine Scotland, 2014b). As such, the JNCC concluded that the Seagreen 1 and the Seagreen 1A Project, together, were only capable of affecting, other than insignificantly, the ocean quahog aggregations and offshore subtidal sand and gravel protected features of the Firth of Forth Banks Complex MPA. For the Seagreen 1A Export Cable Corridor, Scottish ministers also concluded that the temporary habitat disturbance impacts of this project were not considered likely to affect any features of the Firth of Forth Banks Complex MPA including the shelf banks and mounds feature and the Wee Bankie Key Geodiversity Area (Moraines) feature (Marine Scotland, 2021). The shelf banks and mounds and the Wee Bankie Key Geodiversity Area (Moraines) designated features have, therefore, not been considered in relation to the cumulative temporary habitat disturbance.

Offshore subtidal sands and gravels

  1. The sensitivity of this protected feature and its associated communities to this impact is detailed in paragraph 200 to 201 and 203 to 204. The offshore subtidal sands and gravels feature extends across the entirety of the Firth of Forth Banks Complex MPA (JNCC, 2018b), therefore, for the purposes of this assessment, it has been assumed all of the cumulative temporary habitat disturbance could occur within the offshore subtidal sands and gravels feature. The extent of cumulative habitat disturbance to the offshore subtidal sands and gravels feature is therefore predicted to be up to 29.28 km2, which equates to 1.37% of the total extent of this feature within the MPA (0.21% more of the MPA affected cumulatively compared to the Proposed Development alone). As the construction periods for both projects are only scheduled to overlap temporally for one year, only a small proportion of the total habitat disturbance described in Table 1.53   Open ▸ will occur cumulatively within the MPA.
  2. Based on the information presented above, the following can be concluded with respect to the physical and biological attributes of the protected features of the Firth of Forth Banks Complex MPA:
  • The extent and distribution of the offshore subtidal sands and gravels protected feature would be impacted in much the same way as the project alone assessment (paragraph 202). The magnitude of the cumulative impact is increased slightly from the project alone however habitat disturbance from the construction of the Seagreen 1A Project will only overlap for a year with the construction of the Proposed Development and in addition there will be no spatial overlap and so no repeat disturbance to the same areas of this feature within the MPA (paragraph 448). Additionally, all of the construction activities for both projects will occur intermittently, will be highly localised and will be reversible once the activities cease, reducing the scale and intensity of this impact. This is consistent with the ‘conserve’ objective of the extent and distribution attribute for this feature.
  • As discussed in paragraph 202, temporary habitat disturbance is unlikely to have any impact upon physical attributes such as fine scale topography as it relies upon the hydrodynamic regime which will not be changed by this impact. This is due to the localised scale of this impact, with effects focussed on discrete locations such as the installation site of a wind turbine foundation or the installation corridor for a cable. The predicted cumulative disturbance of the seabed will not impact upon the dominant hydrodynamic regime, which is governed by much larger oceanic scale processes, which in turn creates the fine scale topographic features such as sand ripples which characterise this protected feature. This is consistent with the ‘recover’ objective of the structure and function attribute for this feature.
  • The sediment composition of the protected feature will be minimally impacted upon by cumulative temporary habitat disturbance due to the temporary, intermittent, and localised nature of the impact. Despite the small increase in the cumulative extent of the feature affected, the activities are of a similar nature for both projects and will involve only discrete areas and no further movement of seabed material beyond that needed for the Proposed Development which was modelled to have a limited and temporary effect, returning to the baseline in a few tidal cycles. Overall, the sediment composition of the protected feature won’t be affected by this impact due to its localised and temporary nature. This is supported by the recent study (RPS, 2019) which reviewed the effects of cable installation on subtidal sediments and habitats. This study showed that sandy sediments recover quickly following cable installation, with trenches infilling quickly following cable installation and little or no evidence of disturbance in the years following cable installation (RPS, 2019). It also presented evidence that remnant cable trenches in coarse and mixed sediments were conspicuous for several years after installation. However, these shallow depressions were of limited depth (i.e. tens of centimetres) relative to the surrounding seabed, over a horizontal distance of several metres and therefore did not represent a large shift from the baseline environment (RPS, 2019). It has been reported that benthic communities associated with soft sediments (e.g. muds, sands and gravels) readily recover into areas if the sediment type is reflective of the baseline environment (RPS, 2019). This is consistent with the ‘recover’ objective of the structure and function attribute for this feature.
  • With respect to the key influential species, with 1.37% of the offshore subtidal sands and gravels feature being disturbed during the construction phase of the Proposed Development. This would temporarily reduce the extent of the habitat however the communities are likely to recover (paragraph 205), with recovery of disturbed populations within a matter of years after construction. Key influential species have exhibited some tolerance to the pressures of temporary habitat disturbance. Additionally, the disturbance associated with the construction of Seagreen 1A Project and the maintenance of Seagreen 1A Export Cable Corridor do not spatially overlap with the Proposed Development. As the impacts associated with each project are highly localised, disturbance will not overlap and there will be no repeat disturbance to the same areas. Overall, the impact upon key influential species will be minimal and recovery of affected communities is predicted to occur following the cessation of construction activities. This is consistent with the ‘recover’ objective of the structure and function attribute for this feature.
  • The impact of cumulative temporary habitat disturbance on the presence and spatial distribution of characteristic communities within the offshore subtidal sands and gravels protected feature will marginally increase compared to the Proposed Development alone. The area of cumulative temporary impact is predicted to affect up to 1.37% of this feature within the MPA. The cumulative activities will all be highly localised and only impact discrete areas of the feature, communities outside the installation sites will not be impacted allowing swift recolonisation by species nearby. As described in paragraph 205, the communities will have some resistance to these impacts and the extent of the impact will limited by its localised nature. Additionally, the temporary and short-term nature of the cumulative impact will enable re-population by the characteristic communities, particularly as the physical characteristics of the protected feature, such as the sediment composition which they rely upon, will be largely unaffected. This is consistent with the ‘recover’ objective of the structure and function attribute for this feature.
  • The overall function of this protected feature will remain unchanged as a result of these cumulative impact of temporary habitat disturbance as the activities involve the same kind of disturbance as the project alone assessment. As a result, the impact on function is as described in paragraph 205. This is consistent with the ‘recover’ objective of the structure and function attribute for this feature.
    1. Based on the information presented here, it can be concluded that cumulative temporary habitat disturbance during the Proposed Development construction phase will not lead to a significant risk of hindering the achievement of the overall conservation objective (i.e. “recover to favourable condition”) for this feature of the Firth of Forth Banks Complex MPA for the following reasons:
  • The cumulative temporary habitat loss/disturbance is predicted to affect a small proportion of the total extent of the offshore subtidal sands and gravels feature within the MPA (1.37%). This disturbance will occur intermittently during the construction phase and the habitats will recover such that the extent and distribution of the protected feature will remain stable following the construction phase; and
  • The structures and functions, quality, and the composition of characteristic communities will remain in (or recover to) a condition which is healthy and not deteriorating. Recovery of the seabed sediment will occur in the months following seabed preparation, foundation installation and cable installation, with complete recovery within the areas affected within a few years. The key and influential species are predicted to recolonise disturbed sediment, with full recovery of characteristic communities within months to years of construction; as supported by analogous studies from the aggregates, and offshore wind industry. These communities will be supported by an undisturbed hydrodynamic regime which will continue to form the fine scale features of the MPA.

Ocean quahog aggregations

  1. The sensitivity of the ocean quahog aggregations feature to this impact is as detailed in paragraphs 218 to 221. Suitable habitat for the ocean quahog aggregations feature extends across the entirety of the Firth of Forth Banks Complex MPA (JNCC, 2018b), therefore for the purpose of this assessment it can be assumed all of the cumulative temporary habitat disturbance will occur within this feature. The extent of cumulative habitat disturbance to ocean quahog aggregations habitat is therefore predicted to be up to 29.28 km2, which equates to 1.37% of the total extent of this feature within the MPA.
  2. The following can be concluded with respect to the physical and biological attributes of this protected features of the Firth of Forth Banks Complex MPA:
  • The extent and distribution of the ocean quahog aggregation feature within the Firth of Forth Banks Complex MPA is predicted to experience a small increase in the temporary habitat disturbance as a result of the cumulative projects. This impact will be highly localised resulting in temporary disturbance in discrete non-overlapping areas of the MPA over short periods, with the level of disturbance reducing, and largely ceasing (except for localised maintenance works), after the completion of the construction phases of all projects which will allow for recovery of the population. This is consistent with the ‘conserve’ objective of the extent and distribution attribute for this feature.
  • The structure of the ocean quahog aggregations feature within the Firth of Forth Banks Complex MPA is currently unknown (JNCC, 2018b) however aggregations must still be conserved where they are found, and settlement encouraged. The temporary and intermittent nature of the cumulative impact of temporary habitat disturbance will enable recovery after the activities have concluded. Additionally, the localised nature of the impact ensures that the disturbance is minimal, thus ensuring the long term survival of ocean quahog at all stages of their lifecycle. The additional impact of the construction of Seagreen 1A Project as well as the maintenance of the Seagreen 1A Export Cable Corridor and Seagreen 1 does not change the nature of this impact and only results in a small increase in the extent of the disturbance impact. Mortality of all individuals impacted is not predicted and some individuals not directly impacted by installation equipment, such as cable installation tools, could be reasonably expected to survive. It should be noted that whilst the assessment for impacts associated with cable installation assume a width of disturbance to the seabed (e.g. up to 15 m), the actual width of the trench (i.e. where most direct impacts will occur) will likely be much smaller than this for all projects. The temporary, localised and intermittent nature of the habitat disturbance will ensure minimal impacts to larva and juveniles, and after construction is completed, conditions will return to the baseline and recovery of any individuals affected, and their supporting habitats, will occur. As noted in paragraph 309, a likely reduction in fishing pressure in the immediate vicinity of the wind turbines within the MPA will likely aid the recovery of the ocean quahog population within the MPA. This is consistent with the ‘conserve’ objective of the structure and function attribute for this feature.
  • Temporary habitat disturbance will not impact upon the hydrodynamic regime as it is driven by oceanic scale processes which will not be affected by temporary habitat loss within the Firth of Forth Banks Complex MPA (paragraph 223 and 452). This is consistent with the ‘conserve’ objective of the supporting processes attribute for this feature.
  • The stability of the hydrodynamic conditions also ensures that the supporting sedimentary offshore subtidal sands and gravels habitat, that the ocean quahog aggregations rely on, is maintained for their use throughout the MPA. This is consistent with the ‘conserve’ objective of the structure and function attribute for this feature.
  • The physical and biological attributes of this feature are largely conserved throughout the operation and maintenance phase of the Proposed Development, with the addition of the cumulative projects. The effects of this impact on the function of this protected feature are therefore the same as described in paragraph 225. This is consistent with the ‘conserve’ objective of the structure and function attribute for this feature.
    1. Based on the information presented here, it can be concluded that cumulative temporary habitat disturbance during the Proposed Development construction phase will not lead to a significant risk of hindering the achievement of the overall conservation objective for the ocean quahog aggregations feature of the Firth of Forth Banks Complex MPA (i.e. “recover to favourable condition”) for the following reasons:
  • Cumulative temporary habitat disturbance is predicted to affect a small proportion (1.37%) of supporting habitat for ocean quahog intermittently during the construction phase, these but habitats are predicted to recover such that the quality and quantity of ocean quahog habitat is maintained. Whilst some ocean quahog individuals may be directly affected by the construction activities, this is predicted to be to an extent that will not affect the composition of its population in terms of number, age and sex ratio or its ability to thrive in the future and a likely reduction in fishing pressure in the immediate vicinity of the wind turbines will potentially aid the recovery of the ocean quahog population within the MPA.