Operation and maintenance phase
  1. Colonisation of hard structures during the operation and maintenance phase of the Proposed Development within the Firth of Forth Banks Complex MPA may occur due to the presence of wind turbines/OSP-Offshore convertor station platform foundations and cable, cable crossing and scour protection. Table 1.46   Open ▸ details the components of the Proposed Development which will contribute to the colonisation of hard structures within the MPA. Full details of why the suction caisson jacket foundations and the smaller wind turbines represent the maximum design scenario for habitat creation are presented in annex A.
  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):

 

Table 1.46:
Extent of Habitat Creation within the Firth of Forth Banks Complex MPA During the Operation and Maintenance Phase

Table 1.46: Extent of Habitat Creation within the Firth of Forth Banks Complex MPA During the Operation and Maintenance Phase

1 For the purposes of replicating the calculations in this table, 31.33% is calculated as 316.5 km2/1010.2 km2 (i.e. overlap between Proposed Development array area / total Proposed Development array area).

2 For the purposes of replicating the calculations in this table, 13.08% is calculated as 114.08 km/872 km (i.e. proportion of total length of offshore export cables that could occur within the part of the Proposed Development export cable corridor that overlaps with the MPA).

 

Table 1.47:
Summary of the Extent of Hard Structures for Colonisation Within the Firth of Forth Banks Complex MPA (as a Whole, and for the Component Sites) During the Operation and Maintenance Phase

 Table 1.47: Summary of the Extent of Hard Structures for Colonisation 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 30.81% of the 2.71 km2 total on the basis of the overlap with the Scalp and Wee Bankie (see paragraph 170).

2 Calculated as 69.19% of the 2.71 km2 total on the basis of the overlap with the Berwick Bank (see paragraph 188).

 

Offshore subtidal sands and gravels

  1. On the basis of the assumptions outlined in paragraph 191, and for the purposes of this assessment, it is assumed that all of the potential new habitat creation occurring within the MPA will occur within this feature which would equate to 2.72 km2 of new hard habitat within this protected feature and affecting 0.13% of the total area of the feature ( Table 1.47   Open ▸ ). This can be broken down as up to 0.84 km2 within Scalp and Wee Bankie (0.04% of the total area of this feature in the MPA), and up to 1.88 km2 within the Berwick Bank part of the MPA (0.09% of the total area of this feature in the MPA).
  2. Colonisation of wind turbine/OSP-Offshore convertor station platform foundations, associated scour protection and cable protection for cables and cable crossings may have indirect adverse effects on the baseline communities and habitats due to increased predation on and competition with the existing soft sediment species. These effects are difficult to predict, especially as monitoring to date has focused on the colonisation and aggregation of species close to the foundations rather than broad scale studies.
  3. The biotopes which characterise this offshore subtidal sands and gravel feature (i.e. SS.SSa.CFiSa.ApriBatPo and SS.SSa.CFiSa.EpusOborApri; see paragraph 203) are predominantly soft sediment communities and the introduction of new hard substrate will represent a shift from the baseline conditions from soft substrate areas (i.e. sands and gravels) to hard substrate in the areas where infrastructure is present. This may produce some potentially beneficial effects, for example the likely increase in biodiversity and individual abundance of reef species and total number of species over time, as has been observed at the monopile foundations installed at Lysekil research site (a test site for offshore wind-based research, north of Gothenburg, Sweden) (Bender et al., 2020). Species which are typical of rocky and intertidal habitats are likely to be the ones to colonise the new hard substrate.
  4. Studies have also shown that there is potential for reef effects to occur in association with the hard structures such as wind turbine foundations and scour/cable protection for foundations, cables and cable crossings. The structural complexity of the substrate may provide refuge as well as increasing feeding opportunities for larger and more mobile species. The presence of mobile benthic organisms is thought to be dependent on sufficient food sources, cover of epibenthic communities and appropriate habitat with shelter opportunities to hide from predators (Langhamer, and Wilhelmsson, 2009). A study by Lefaible et al. (2019) identified that jacket foundations had higher densities and diversity (species richness) of species in closer vicinity of the wind turbines compared to a control and a monopile foundation. A study by Mavraki et al. (2020) of gravity-based foundation in the Belgian part of the North Sea found that higher food web complexity was associated with zones where high accumulation of organic material such as soft substrate or scour protection, suggesting potential reef effect benefits from the presence of the hard structures.
  5. The reef effect may be enhanced by the deposition of fouling material on the seabed. An investigation conducted at the research platform Forschungsplattformen in Nord- und Ostsee 1 FINO 1 in the south-western German Bight in the North Sea reported that yearly, 878,000 single shell halves from Mytilus edulis sink onto the seabed from the FINO 1 platform, thereby greatly extending the reef effects created by the construction of the offshore platform structure (Krone et al., 2013). Removal of marine growth from the wind turbine foundations may also cause debris to fall within the vicinity of the wind turbine foundation. It is likely that seaweed/algal material would disperse into the water column, with heavier material (e.g. mussels) being deposited within 10 m to 15 m of the foundation. This material has the potential to change the prevailing sediment type in the immediate vicinity of the wind turbines, and therefore extending the reef effect.
  6. Some studies however have shown that the installation and operation of offshore wind farms have no significant impact on the wider soft sediment environments beyond the immediate impact of the loss of habitat. De Backer et al. (2021) found that eight to nine years after the installation of C-power and Belwind offshore wind farms (offshore Belgium) that the soft sediment epibenthos underwent no drastic changes; and the species originally inhabiting the sandy bottom were still present and remained dominant in both wind farms. The most recent benthic post-construction monitoring data of wind turbine foundations from Beatrice offshore wind farm (APEM, 2021) found foundation colonisation of wind turbines has resulted in zonation on the foundation itself but had little influence on the sedimentary habitat below. In the immediate vicinity of the jacket foundation legs mobile species were present such as hermit crab Pagurus bernhardus, flatfish and the common sea urchin Echinus esculentus, which suggests the availability of food although no biological material was recorded on the seabed (this material may have been rapidly consumed or relocated due to tidal currents) (APEM, 2021). Additionally, some species frequently found on the foundation legs, e.g. dead man’s fingers Alcyonium digitatum and the keelworm Spirobranchus triqueter, could also be found on the sedimentary habitat such as sublittoral coarse sediment (APEM, 2021).
  7. In conclusion the installation of hard structures will result in the loss of some sedimentary habitat directly below it and with a small radius around it, however the remaining sedimentary habitat will not be continually degraded and will largely remain unchanged as a result of the introduction and colonisation of hard substrate. There may be some benefits for species which prefer hard substrates as a result of the reef effect, but this is unlikely to affect species which inhabit the offshore subtidal sands and gravels. As outlined in Table 1.59   Open ▸ , the Applicant is committed to engaging in discussions with Marine Scotland and the SNCBs to identify, and input to, strategic benthic monitoring of the colonisation of hard structures and impacts to surrounding soft sediments across wind farms off the east coast of Scotland, if available and proposed by Marine Scotland in order to validate the predictions of this assessment.
  8. The infrastructure resulting in the colonisation of hard substrates will remain in place throughout the operation and maintenance period of up to up to 35 years.
  9. The physical attributes extent and distribution, hydrodynamic regime and fine scale topography are not applicable to this impact because they cannot be affected by the introduction of a new biological community.
  10. Based on the information presented above, the following can be concluded with respect to the relevant physical attributes of the protected features of the Firth of Forth Banks Complex MPA:
  • The sediment composition of the offshore subtidal sands and gravels has the potential to impacted in a limited capacity by the deposition of encrusted material, either through natural processes or scheduled cleaning of infrastructure such as wind turbine/OSP-Offshore convertor station platform foundations. This effect would be highly localised and would not produce enough material to change the overall sediment composition in the vicinity of the wind turbine/OSP-Offshore convertor station platform foundations. This is supported by evidence from Block Island wind farm in the United States of America, where monitoring found no strong gradients of change in sediment grain size within 30-90 m of the wind turbines (Hutchinson et al., 2020a). It is likely that seaweed/algal material released during maintenance/cleaning of the wind turbine/OSP-Offshore convertor station platform foundations would disperse into the water column, with heavier material (e.g. mussels) being deposited within 10-15 m of the foundation (Vattenfall Wind Power Ltd, 2018). An investigation conducted at the research platform Forschungsplattformen in Nord- und Ostsee 1 FINO 1 in the south-western German Bight in the North Sea reported that blue mussels Mytilus edulis were one of the dominant colonising species (Krone et al., 2013) and the deposition of their shells on the seabed under the platform provides a secondary substrate for the attachment of other epifaunal species (Norling and Kautsky, 2007). In the long term, the production of shell debris may have indirect effects on benthic ecology by leading to coarser, shell-dominated sediment and enriched structure diversity. The extent to which Mytilus colonisation and subsequent indirect effects may occur is highly dependent on the nature of the structures installed and site-specific effects (e.g. structures further offshore, outside the mussels’ range may be colonised less strongly). Any fine material generated as a result of the use of high-pressure jet washing to remove the encrusting fauna into the marine environment may result in a short‐term increase in suspended organic material in the water. This material would be expected to be rapidly dispersed on the following tides and under the prevailing hydrodynamic conditions. Overall, this level of deposition is unlikely to have an impact on the sediment composition very far beyond the immediate vicinity of the infrastructure. This is consistent with the ‘recover’ objective of the structure and function attribute for this feature.
    1. Based on the information presented above, the following can be concluded with respect to the biological attributes of the protected features of the Firth of Forth Banks Complex MPA:
  • The key influential species of this protected feature are unlikely to be affected by the biological communities which will colonise the hard structures of the Proposed Development. This is because the communities which will colonise the hard structures will be adapted to hard substrates and therefore unlikely to colonise the sedimentary habitat which is occupied by the key and influential species, this is supported by the examples provided in paragraphs 339 and 342 which provide evidence to support the prediction that soft sediment species are not affected by the colonising communities at offshore wind farms (De Backer et al., 2021; APEM, 2021). Whilst some reef effects may result in expansion of taxa normally associated with hard substrates colonising areas of subtidal coarse sediment or subtidal sand, these effects are likely to be limited to the immediate vicinity of offshore structures and will not result in changes to the species composition of communities associated with the offshore subtidal sands and gravels feature across the wider MPA. This is consistent with the ‘recover’ objective of the structure and function attribute for this feature.
  • As above the characteristic communities within this protected feature will be adapted to the sands and gravels of the feature, resulting in no cross over of habitat and therefore competition between them and the colonising communities. Some studies have also shown minor increases in the prevalence of some epifaunal species around offshore wind farm infrastructure as they can provide shelter and food to surrounding communities (Langhamer and Wilhelmsson, 2009) which could benefit species such as squat lobster Galathea intermedia and sea spider Callipallene brevirostris. This is consistent with the ‘recover’ objective of the structure and function attribute for this feature.
  • The function of this protected feature is unlikely to be affected by the colonisation of hard structures. As there is no impact on the physical attribute of this feature it is unlikely that the climate regulation function and productivity of the feature will be negatively affected. Addressing the features function as a spawning ground for fish such as plaice and sandeels, the productivity of the site is maintained through the undisturbed hydrodynamic regime and the sediment composition will only be negligibly impacted in the vicinity (within 200 m where change to littoral currents is expected to be 5% of the baseline) of the infrastructure from the deposition of encrusted material however as mentioned above (paragraph 346) that will not change the composition of sediment far beyond the immediate vicinity of the infrastructure where fouling deposition may occur. Therefore, the vast majority (>99%) of the offshore sands and gravels feature will be maintained and will remain suitable for spawning. 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 highly limited nature of the colonisation of hard substrate impact 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 high vulnerability, low recoverability and national importance and therefore was considered to have a high sensitivity. Therefore, the significance of effect was considered to be minor adverse significance.
    2. Based on the information presented here, it can be concluded that colonisation of hard substrate during the Proposed Development operation and maintenance 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:
  • Colonisation of hard substrate will not impact upon the extent and distribution of the protected feature and will therefore remain stable during the operation and maintenance 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. Seabed sediment will experience a small influx of deposited encrusted material, but the composition will not change. The key and influential species and their communities are not predicted to be affected other than potentially in the immediate vicinity of the wind turbine/OSP-Offshore convertor station platform foundations and scour protection and will therefore maintain their overall distribution and structure. 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 potential habitat creation occurring within the MPA (i.e. 2.72 km2) may occur within supporting habitat for ocean quahog aggregations ( Table 1.43   Open ▸ ), affecting 0.13% of the ocean quahog aggregations feature ( Table 1.47   Open ▸ ).
  2. The sensitivity of ocean quahog aggregations to the colonisation of hard structures is as discussed in paragraph 342. Studies suggests that the hard substrate adapted species which colonise offshore wind farm infrastructure will not have an impact on the soft sediment environment below and around them (De Backer et al., 2021; APEM, 2021).
  3. The infrastructure resulting in the colonisation of hard substrates will remain in place throughout the operation and maintenance period of up to up to 35 years.
  4. 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:
Decommissioning phase
  1. The maximum design scenario for the extent of habitat creation arising from the introduction of new hard structures within the Firth of Forth Banks Complex MPA which will persist following the decommissioning phase of the Proposed Development amounts to a total of up to 1.87 km2 or 0.09% of the total area of the MPA. As outlined in
  2. Table 1.48   Open ▸ , this comprises scour and some cable protection for cables and cable crossings only, as the maximum design scenario assumes that all foundations will be removed during decommissioning. Of this habitat creation, up to 0.58 km2 may persist post-decommissioning within the Scalp and Wee Bankie section which equates to 0.03% of the total area of the MPA (or 0.07% of the area of Scalp and Wee Bankie) and 1.29 km2 within the Berwick Bank part of the MPA which equates to 0.06% of the total area of the MPA (or 0.24% of the area of Berwick Bank) (see Table 1.49   Open ▸ ).
  3. These effects are considered in the decommissioning phase as it takes time for organisms to colonise a structure post-installation and structures which are left in situ during and after decommissioning (i.e. scour and cable protection for cables and cable crossings) will continue to provide potential habitat for colonising species. Cable protection for cables and cable crossings will be fully removed where it is possible and appropriate to do so noting this will depend on the type of protection used and condition of the protection at the time of removal. All cables will be removed where it is possible and appropriate to do so. As it is difficult to determine the proportion of cable protection which will be removed it has been assumed as a maximum design scenario that all cable protection will remain in situ.

 

Table 1.48:
Extent of Habitat Creation within the Firth of Forth Banks Complex MPA During the Decommissioning Phase

Table 1.48: Extent of Habitat Creation within the Firth of Forth Banks Complex MPA During the Decommissioning Phase

1 For the purposes of replicating the calculations in this table, 31.33% is calculated as 316.5 km2/1010.2 km2 (i.e. overlap between Proposed Development array area / total Proposed Development array area).

2 For the purposes of replicating the calculations in this table, 13.08% is calculated as 114.08 km/872 km (i.e. proportion of total length of offshore export cables that could occur within the part of the Proposed Development export cable corridor that overlaps with the MPA).

 

Table 1.49:
Summary of the Extent of Hard Structures for Colonisation Within the Firth of Forth Banks Complex MPA (as a Whole, and for the Component Sites) Following the Decommissioning Phase

Table 1.49: Summary of the Extent of Hard Structures for Colonisation Within the Firth of Forth Banks Complex MPA (as a Whole, and for the Component Sites) Following the Decommissioning Phase

1 Calculated as 30.81% of the 1.87 km2 total on the basis of the overlap with the Scalp and Wee Bankie (see paragraph 170).

2 Calculated as 69.19% of the 1.87 km2 total on the basis of the overlap with the Berwick Bank (see paragraph 188).

 

  1. The risk associated with the decommissioning phase is reduced compared to the operation and maintenance phase assessment (by the equivalent of 0.05% of the total area of the MPA) as the maximum design scenario assumes that the wind turbine/OSP-Offshore convertor station platform foundations, which span the water column, will be removed which will result in a reduction in hard structures available for colonisation.

Offshore subtidal sands and gravels

  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 hard substrate which could remain in the MPA post-decommissioning (i.e. 1.87 km2 resulting from the continued presence of scour and cable protection for cables and cable crossings) would occur within this feature, affecting 0.09% of this protected feature.
  2. Despite the decrease in amount of hard infrastructure compared to the operation and maintenance phase, the overarching risks associated with this impact are as described in paragraphs 334 et seq., involving a physical change to the seabed type. The effects on the offshore subtidal sands and gravels protected feature are as described in paragraphs 339 to 347.
  3. Volume 2, chapter 8 of the Offshore EIA Report concluded that due to the highly limited nature of the colonisation of hard substrate impact 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 high vulnerability, low recoverability and national importance and therefore was considered to have a high sensitivity. Therefore, the significance of effect was considered to be minor adverse significance.
  4. Based on the information presented in paragraphs 337 to 349, it can be concluded that the impact of habitat creation and the colonisation of structures (i.e. scour and cable protection for foundations, cables and cable crossings) persisting post-decommissioning will not lead to a significant risk of hindering the achievement of the conservation objectives (i.e. “recover to favourable condition”) for this feature of the Firth of Forth Banks Complex MPA for the reasons presented in paragraph 349.

Ocean quahog aggregations

  1. On the basis of the assumptions outlined in paragraph 190, and for the purpose of this assessment, it is assumed that all of the hard substrate which could remain in the MPA post-decommissioning (i.e. 1.87 km2 resulting from the continued presence of scour and cable protection for foundations, cables and cable crossings) will occur within supporting habitat for this feature, affecting 0.09% of the supporting habitat for this protected feature.
  2. Despite the decrease in amount of hard infrastructure compared to the operation and maintenance phase, the overarching risks associated with this impact are as described in paragraphs 334 et seq., involving a physical change to the seabed type. The effects on supporting habitat for this protected feature are as described in paragraphs 351 to 353.
  3. Volume 2, chapter 8 of the Offshore EIA Report concluded that due to the limited nature of the impact of colonisation of hard structures, 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 high vulnerability, low recoverability and national importance and therefore was considered to have a high sensitivity. Therefore, the significance of effect was considered to be of minor adverse significance.
  4. Based on the information presented in paragraphs 350 to 355, it can be concluded that the impact of habitat creation and the colonisation of structures (i.e. scour and cable protection for foundations, cables and cable crossings) persisting post-decommissioning will not lead to a significant risk of hindering the achievement of the conservation objectives (i.e. “recover to favourable condition”) for this feature of the Firth of Forth Banks Complex MPA for the reasons presented in paragraph 355.

Increased Risk of Introduction and Spread of INNS

Construction and operation and maintenance phase
  1. Increased risk of introduction and spread of INNS in subtidal habitat may occur within the Firth of Forth Banks Complex MPA during the construction and operation and maintenance phase as a result of the creation of hard substrates such as wind turbine/OSP-Offshore convertor station platform foundations, cable, and scour protection, as well as vessel trips for construction and maintenance. The maximum design scenario for increased risk of introduction and spread of INNS within the Firth of Forth Banks Complex MPA is the same as for colonisation of hard substrate ( Table 1.46   Open ▸ ), and also includes up to 11,484 vessel round trips during construction and 2,324 vessel round trips per year (81,350 over the 35 year lifetime) over the operation and maintenance phase.
  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):
  • Introduction or spread of non-indigenous species.
    1. The assumptions used to determine the proportion of new hard substrate available for colonisation which occurs within the Firth of Forth Banks Complex MPA is stated in paragraph 189.
    2. The extent of habitat creation which may increase the risk of introduction and spread of INNS within the Firth of Forth Banks Complex MPA is the same as detailed in paragraph 336.

Offshore subtidal sands and gravels

  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 potential increased risk of introduction and spread of INNS will occur within this feature ( Table 1.43   Open ▸ ). This would equate to the introduction of 2.72 km2 of new hard substrate affecting 0.13% of this protected feature (the breakdown between sections of the MPA is presented in paragraph 337). Additionally, there is the risk associated with up to 11,484 vessel round trips during construction and up to 81,350 vessel round trips over the operation and maintenance phase (approximately 2,324 trips per year).
  2. Activities resulting in a potential increased risk of introduction and spread of INNS will occur throughout the 96 months of the construction phase as well as the operation and maintenance period of up to 35 years. Vessel movements are likely to be concentrated on discrete locations within the Firth of Forth Banks Complex MPA, where cable or wind turbine construction/repair/investigation may be required. In both the construction phase and operation and maintenance phase, the vessel movement will occur in all sections of the MPA which overlap with the Proposed Development but will be specific to the location of infrastructure. It should be noted that the existing baseline of vessel activity includes commercial fishing, cargo vessels and tankers which are found in this area on a daily basis. As outlined in section 193, designed in measures including an Environmental Management Plan (EMP) (including an INNS management plan) (volume 3 appendix 6.2 of the Offshore EIA Report) and vessels complying with International Maritime Organisation (IMO) ballast water management guidelines (IMO, 2004) throughout all phases of the Proposed Development will ensure that the risk of potential introduction and spread of INNS will be minimised.
  3. The sedimentary and high energy nature of the environment is however thought to be challenging for most INNS with very few species able to colonise mobile sands due to the high levels of sediment disturbance (Tillin, 2016a; Tillin, 2016b). Additionally, as discussed in paragraph 347 any INNS which colonise the hard structures of the wind turbine/OSP-Offshore convertor station platform foundations are unlikely to spread on to the sand and gravels of the seabed as they are not adapted for this habitat. Where this does occur, any effects are likely to be limited to the immediate vicinity of offshore structures and will not result in changes to the species composition of communities associated with the offshore subtidal sands and gravels feature across the wider MPA. Recent monitoring from Beatrice offshore wind farm, off of the north-western coast of Scotland, found no evidence of INNS colonisation on foundations (APEM, 2021).
  4. The characteristic biotopes of this protected feature (SS.SSa.CFiSa.EpusOborApri and SS.SSa.CFiSa.ApriBatPo) are most at risk from the introduction of slipper limpet Crepidula fornicata as this species can form dense carpets which can smother other species and prevent larva from settling (Tillin, 2016a; Tillin, 2016b). The long term presence of slipper limpets can also lead to the aggregation of suspended silt, faeces and pseudo-faeces altering the benthic habitat leading to a change in the dominant biotopes (Tillin, 2016a; Tillin, 2016b). Slipper limpets have been recorded, but only once, in the wider Firth of Forth/South-eastern Scotland region (NBN Atlas). This species spreads through ballast water transfer and hull fouling; however as mentioned in paragraph 373 and see section 193 designed in measures will be implemented to minimise the risk from these sources.
  5. Based on the information presented above, the following can be concluded with respect to the physical and biological attributes of the offshore subtidal sands and gravels feature of the Firth of Forth Banks Complex MPA:

Ocean quahog aggregations

  1. On the basis of the assumptions outlined in paragraph 190, and for the purpose of this assessment it is assumed that the increased risk of the introduction and spread of INNS will occur within this feature ( Table 1.43   Open ▸ ). This would equate to the introduction of up to 2.72 km2 of new hard substrate, affecting 0.13% of this protected feature (the breakdown between sections of the MPA is presented in paragraph 337). Additionally there is the risk associated with up to 11,484 vessel round trips during construction and up to 81,350 vessel round trips over the operation and maintenance phase (approximately 2,324 vessel round trips per year).
  2. Paragraphs 373 and 374 detail the nature of the impact in relation to vessel movement and the physical environment. Neither the FeAST or the MarESA provides evidence to justify the sensitivity of ocean quahogs to increased risk of introduction and spread of INNS. The biological characteristics of ocean quahog, such as the length of time taken to reach sexual maturity (~5 to 11 years; Thorarinsdóttir, 1999), make them vulnerable to potentially faster growing and spreading INNS which could out compete them in their own habitat.
  3. 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:
Decommissioning phase
  1. Increased risk of the introduction and spread of INNS in subtidal habitat may occur within the Firth of Forth Banks Complex MPA during the decommissioning phase as a result of the presence of structures left in situ such as cable, and scour protection, as well as vessel trips for decommissioning. The maximum design scenario for the area affected by increased risk of introduction and spread of INNS within the Firth of Forth Banks Complex MPA is the same as for colonisation of hard substrate persisting post-decommissioning (paragraph 336 and Table 1.46   Open ▸ ), but also includes up to 11,484 vessel round trips during the decommissioning phase.
  2. The risk associated with the decommissioning phase is reduced compared to the operation and maintenance phase as most of the hard structures, including the wind turbine/OSP-Offshore convertor station platform foundations which span the water column, will be removed which will result in a reduction in hard structures available to INNS. However, as previously noted (paragraphs 368 to 383), these structures do not pose a serious risk to the protected feature within the Firth of Forth Banks Complex MPA as the species which are likely to colonise the structures would not be adapted to the sedimentary habitat which dominates the MPA. Additionally, this phase represents a larger number of vessel round trip over a shorter amount of time (should it be similar in time scale to the construction phase, although this is not confirmed), however these trips will be intermittent and have a precise focus on the removal of infrastructure as well as following the procedures described as part of the designed in measures for the Proposed Development ( Table 1.36   Open ▸ ).

Offshore subtidal sands and gravels

  1. On the basis of the assumptions outlined in paragraph 190, and for the purposes of this assessment, it is assumed that all the activities and infrastructure resulting in increased risk of introduction and spread of INNS will occur within this feature which would affect 0.09% of this protected feature, along with the risk associated with up to 11,484 vessel round trips.
  2. Despite the increase in vessel trips and decrease in amount of hard infrastructure the risks associated with this impact remain the same as described in paragraph 376 as the designed in measures (see Table 1.36   Open ▸ ) which will be implemented to reduce the risk (i.e. an EMP (including an INNS management plan) (volume 3, appendix 6.2 of the Offshore EIA Report) and vessels complying with IMO ballast water management guidelines), will remain in place.
  3. The conclusion reached by volume 2, chapter 8 of the Offshore EIA Report for the decommissioning phase is the same as was reached for the operation and maintenance phase (paragraph 377).
  4. Based on the information presented here, it can be concluded that increasing the risk of introduction and spread of INNS during the Proposed Development decommissioning phase will not lead to a significant risk of hindering the achievement of the conservation objectives (i.e. “recover to favourable condition”) for this feature of the Firth of Forth Banks Complex MPA for the same reasons presented in paragraph 378.

Ocean quahog aggregations

  1. On the basis of the assumptions outlined in paragraph 190, and for the purpose of this assessment it is assumed that all the activities and infrastructure resulting in increased risk of introduction and spread of INNS will occur within this feature which would affect 0.09% of this protected feature, along with the risk associated with up to 11,484 vessel round trips.
  2. Despite the increase in vessel trips and decrease in amount of hard infrastructure the risks associated with this impact remain the same as described in paragraph 373 as the designed in measures (see section 193) which will be implemented to reduce the risk (i.e. an EMP (including an INNS management plan) (volume 3, appendix 6.2 of the Offshore EIA Report) and vessels complying with IMO ballast water management guidelines), will remain in place.
  3. The conclusion reached by volume 2, chapter 8 of the Offshore EIA Report for the decommissioning phase is the same as was reached for the operation and maintenance phase (paragraph 381).
  4. Based on the information presented here, it can be concluded that increasing the risk of introduction and spread of INNS during the Proposed Development decommissioning phase will not lead to a significant risk of hindering the achievement of the conservation objectives (i.e. “recover to favourable condition”) for this feature of the Firth of Forth Banks Complex MPA for the same reasons presented in paragraph 383.

Alteration of Seabed Habitat Arising from Effects of Physical Processes