- For offshore socio-economics and tourism receptors, all potential impacts have been considered within the inter-related assessment.
-
Table 20.9
Open ▸
lists the inter-related effects (Proposed Development lifetime effects) that are predicted to arise during the construction, operation and maintenance phase, and decommissioning of the Proposed Development and also the inter-related effects (receptor-led effects) that are predicted to arise for offshore socio-economics and tourism receptors.
Table 20.9: Summary of Likely Significant Potential Inter-Related Effects for Offshore Socio-Economics and Tourism from Individual Effects Occurring across the Construction, Operation and Maintenance and Decommissioning Phases of the Proposed Development and from Multiple Effects Interacting Across all Phases (Receptor-led Effects)
- These inter-related effects as described above are not anticipated to interact in such a way as to result in combined effects of greater significance than the assessments presented for each individual phases. Therefore, these inter-related effects would not be significant in EIA terms.
- For physical processes, the following potential impacts have been considered within the inter-related assessment:
- increased SSCs and associated deposition on physical features; and
- changes to tidal currents, wave climate, littoral currents and sediment transport.
-
Table 20.10
Open ▸
lists the inter-related effects (Proposed Development lifetime effects) that are predicted to arise during the construction, operation and maintenance, and decommissioning of the Proposed Development and also the inter-related effects (receptor-led effects) that are predicted to arise for physical processes receptors.
- As previously noted, effects on physical processes also have the potential to have secondary effects on other receptors and these effects are fully considered in the topic-specific chapters. These receptors and effects are:
- benthic subtidal and intertidal ecology:
- increased SSC; and
- sediment deposition.
- fish and shellfish ecology:
- increased SSC; and
- sediment deposition.
- changes to tidal current and wave climate;
- increased SSC; and
- sediment deposition.
- infrastructure and other users:
- increased SSC; and
- changes to tidal current and wave climate.
Table 20.10: Summary of Likely Significant Potential Inter-Related Effects on the environment for Physical Processes from Individual Effects Occurring across the Construction, Operation and Maintenance and Decommissioning Phases of the Proposed Development and from Multiple Effects Interacting Across all Phases (Receptor-led Effects)
- These inter-related effects as described above are not anticipated to interact in such a way as to result in combined effects of greater significance than the assessments presented for each individual phases. Therefore, these inter-related effects would not be significant in EIA terms.
- For water quality, the following potential impacts have been considered within the inter-related effects assessment:
- increased risk of introduction and spread of INNS;
- accidental release of lubricants, chemicals or similar;
- operational painting and cleaning of marine growth; and
- deterioration of bathing water quality from offshore export cables landfall works.
-
Table 20.11
Open ▸
lists the inter-related effects (project lifetime effects) that are predicted to arise during the construction, operation and maintenance phase, and decommissioning of the Proposed Development and also the inter-related effects (receptor-led effects) that are predicted to arise for water quality receptors.
- As noted above, effects on water quality also have the potential to have secondary effects on other receptors and these effects are fully considered in the topic-specific chapters. These receptors and effects are:
- benthic, subtidal and intertidal ecology:
- the potential temporary (construction phase), long term (operation and maintenance phase) and permanent (decommissioning (and post-decommissioning) phase) change in community composition from the introduction and spread of INNS resulting in direct effects on benthic, subtidal and intertidal ecology of minor adverse significance (volume 2, chapter 8);
- the accidental release of lubricants, chemicals or similar (construction, operation and maintenance and decommissioning phases), resulting in direct effects on benthic, subtidal and intertidal ecology of minor adverse significance;
- operational painting and cleaning of marine growth (operation and maintenance phase) may have similar impact as accidental release of lubricants, chemicals or similar, resulting in direct effects on benthic, subtidal and intertidal ecology of minor adverse significance; and
- effects of the offshore export cables crossing the intertidal area have been scoped out as this will be achieved via trenchless techniques, and has therefore not been taken forward for assessment.
- fish and shellfish ecology:
- the accidental release of lubricants, chemicals or similar (construction, operation and maintenance and decommissioning phases), resulting in direct effects on fish and shellfish ecology of minor adverse significance (volume 2, chapter 9); and
- operational painting and cleaning of marine growth (operation and maintenance phase) may have similar impact as accidental release of lubricants, chemicals or similar, resulting in direct effects on fish and shellfish ecology of minor adverse significance.
- socio-economics and tourism:
- water sports including diving, windsurfing, sailing and paddleboarding are popular in the area. Within the water quality study area, North Berwick and Tantallon are popular for kayaking, and Belhaven for surfing. Recreational fishing takes place at Dunbar and North Berwick, which lie within the water quality study area, and from which recreational fishing trips are commonplace; and
- assessment of the potential effects of the Proposed Development upon socio-economics and tourism (volume 2, chapter 18) concluded a negligible to low adverse significance upon recreational water users.
Table 20.11: Summary of Likely Significant Inter-Related Effects on the Environment from Individual Effects Occurring Across the Construction, Operation and Maintenance and Decommissioning Phases of the Proposed Development and from Multiple Effects Interacting Across All Phases (Receptor-led Effects)
- These inter-related effects as described above are not anticipated to interact in such a way as to result in combined effects of greater significance than the assessments presented for each individual phases. Therefore, these inter-related effects would not be significant in EIA terms.
- For benthic subtidal and intertidal ecology, the following likely significant effects have been considered within the inter-related assessment:
- temporary and long-term habitat loss/disturbance;
- increased suspended sediment concentrations and associated sediment deposition;
- impacts to benthic invertebrates due to EMF;
- increased risk of introduction and spread of INNS; and
- alteration of seabed habitats arising from effects of physical processes.
-
Table 20.12
Open ▸
lists the inter-related effects (Proposed Development lifetime effects) that are predicted to arise during the construction, operation, and maintenance phase, and decommissioning of the Proposed Development and also the inter-related effects (receptor-led effects) that are predicted to arise for benthic subtidal and intertidal ecology receptors.
- As noted above, effects on benthic subtidal and intertidal ecology also have the potential to have secondary effects on other receptors and these effects are fully considered in the topic specific chapters. These receptors and effects are:
- fish and shellfish ecology
- temporary (during construction, operation and maintenance and decommissioning phases), long- term (during operation and maintenance phase only) and permanent habitat alteration (post-decommissioning) habitat loss resulting in indirect effects on fish ecology of negligible to moderate adverse significance (volume 2, chapter 9);
- changes in fish and shellfish communities affecting prey availability (during construction, operation and maintenance and decommissioning phases); and
- changes in habitat or abundance and distribution of prey across all project phases resulting in indirect effects on ornithological receptors of negligible to minor significance (volume 2, chapter 11).
Table 20.12: Summary of Likely Significant Inter-Related Effects on the Environment for Benthic Subtidal and Intertidal Ecology from Individual Effects Occurring across the Construction, Operation and Maintenance and Decommissioning Phases of the Proposed Development and from Multiple Effects Interacting Across all Phases (Receptor-led Effects)
- These inter-related effects as described above are not anticipated to interact in such a way as to result in combined effects of greater significance than the assessments presented for each individual phases. Therefore, these inter-related effects would not be significant in EIA terms.
- For fish and shellfish ecology, the following potential impacts have been considered within the inter-related assessment:
- temporary and long term subtidal habitat loss/disturbance;
- increased suspended sediment concentrations and associated sediment deposition;
- EMF from underwater electrical cabling;
- injury and/or disturbance to fish and shellfish from underwater noise and vibration; and
- colonisation of foundations, scour protection and cable protection.
-
Table 20.13
Open ▸
lists the inter-related effects (Proposed Development lifetime effects) that are predicted to arise during the construction, operation and maintenance phase, and decommissioning of the Proposed Development and also the inter-related effects (receptor-led effects) that are predicted to arise for marine mammal and offshore ornithology receptors.
- As noted above, effects on fish and shellfish ecology also have the potential to have secondary effects on other receptors and these effects are fully considered in the topic-specific chapters. These receptors and effects are:
- marine mammals;
- changes in the fish and shellfish community resulting from impacts during construction, operation and maintenance, and decommissioning may lead to loss of prey resources for marine mammals resulting in effects of imperceptible significance volume 2, chapter 10.
- one key stressor has been identified for offshore and intertidal ornithology. The assessment considers the overall effects on foraging seabirds from potential changes in prey communities that could be caused by disturbance, habitat loss, SSC, and therefore, in this respect, has taken an ecosystem-based approach. The assessment of effects, however, demonstrated that due to the high mobility of foraging seabirds and their ability to exploit different prey species, and the small scale of potential changes in context of wider available habitat, the changes to fish prey communities are unlikely to have a significant effect on foraging seabirds; and
- changes in the fish and shellfish community resulting from impacts during construction, operation and maintenance, and decommissioning may affect commercial fisheries receptors by effects on target species, however as noted in this chapter, there are negligible or minor effects on fish and shellfish receptors therefore negligible or minor effects are predicted for commercial fisheries, which are not significant in EIA terms.
Table 20.13: Summary of Potential Inter-Related Effects for Fish and Shellfish Ecology from Individual Effects Occurring across the Construction, Operation and Maintenance and Decommissioning Phases of the Proposed Development and from Multiple Effects Interacting Across all Phases (Receptor-led Effects)
- These inter-related effects as described above are not anticipated to interact in such a way as to result in combined effects of greater significance than the assessments presented for each individual phases. Therefore, these inter-related effects would not be significant in EIA terms.
- For marine mammals, the following potential impacts have been considered within the inter-related assessment:
- injury and disturbance from elevated underwater noise during piling (fixed foundations);
- injury and disturbance to marine mammals from elevated underwater noise during site investigation surveys;
- injury and disturbance to marine mammals from elevated underwater noise during Unexploded Ordnance (UXO) clearance;
- injury and disturbance to marine mammals from elevated underwater noise due to vessel use and other activities;
- increased potential to experience injury by marine mammals due to collision with vessels; and
- changes in fish and shellfish communities affecting prey availability.
-
Table 20.14
Open ▸
lists the inter-related effects that are predicted to arise during the construction, operation and maintenance, and decommissioning phases of the Proposed Development.
Table 20.14
Open ▸
also lists the inter-related effects where stressors may combine to lead to greater effects on marine mammal receptors (receptor-led effects).
- There are no identified effects on marine mammal receptors that have the potential to have secondary effects on other receptors.
Table 20.14: Summary of Likely Significant Inter-Related Effects for Marine Mammals from Individual Effects Occurring across the Construction, Operation and Maintenance and Decommissioning Phases of the Proposed Development and from Multiple Effects Interacting Across all Phases (Receptor-led Effects)
- These inter-related effects as described above are not anticipated to interact in such a way as to result in combined effects of greater significance than the assessments presented for each individual phases. Therefore, these inter-related effects would not be significant in EIA terms.
Stressor 1. Injury or disturbance from elevated underwater noise:
- During the pre-construction phase activities resulting in elevated underwater noise include UXO clearance, site investigation surveys and vessel movements. These activities are likely to result in disturbance to marine mammals which may be additive if activities are synchronised as it could lead to a larger area disturbed at any one time. Disturbance is likely to occur as short term, localised events for each activity. For example, UXO clearance would result in no more than 14 single events with disturbance occurring mainly during mitigation (ADDs and soft start) rather than the UXO clearance event itself which would be no more than seconds for each. There is also a small potential that animals could experience injury during UXO clearance (due to an accidental a high order detonation). Site investigation surveys are likely to occur over a total duration of up to three months whilst disturbance during vessel activity will occur intermittently throughout this phase with timings linked to the pre-construction activities.
- During the construction phase, activities resulting in elevated underwater noise include pile-driving, other construction activities and vessel movements. Since injury to marine mammals will be mitigated through an MMMP, the key focus is on disturbance effects. Disturbance could occur intermittently on a total of 372 days (within a 52-month piling period) during the construction phase of 96 months. Other construction activities (e.g. drilling and cable laying) and vessel movements would occur intermittently within the 96 months construction phase. When piling occurs the disturbance effects are likely to be greater than for any of the other activities contributing to elevated underwater noise so there is less likely to be an additive or synergistic effect during piling. There may, however, be an additive effect spatially where two or more noise-producing activities occur in different parts of the Proposed Development area, or temporally due to ongoing disturbance from activities throughout the construction phase (e.g. if they occur consecutively).
- Activities resulting in elevated underwater noise during the operation and maintenance phase include vessel activity and geophysical surveys. These activities are likely to result in disturbance to marine mammals which may be additive if activities are synchronised as it could lead to a larger area disturbed at any one time. Disturbance is likely to occur as short term, localised events for each activity and there may be an additive effect spatially where two or more noise-producing activities occur in different parts of the Proposed Development area, or temporally due to ongoing disturbance from activities throughout the operation and maintenance phase (e.g. if they occur consecutively).
- Vessel movements associated with decommissioning activities will result in elevated underwater noise which could lead to disturbance to marine mammals. Disturbance is likely to occur as short term, localised events and there may be an additive effect spatially where vessels are operating in different parts of the Proposed Development area, or temporally due to ongoing disturbance throughout the decommissioning phase.
- Marine mammal receptors will experience ongoing disturbance due to elevations in underwater noise from different sources at all phases of the Proposed Development. The sensitivity of key species will be linked to their ability to tolerate the stressor such that their ability to function normally (forage, reproduce, communicate, avoid predators, etc) is not impeded. The assessment - which adopted a highly precautionary approach - has demonstrated that for all impacts, considered in isolation, the residual effects will not be significant (after implementation of mitigation) as either the spatial scale is very localised or where larger scale effects do occur (i.e. during piling) these will be highly reversible with animals returning to baseline levels rapidly. After implementation of appropriate mitigation there is, however, potentially a small residual number of harbour porpoise Phocoena phocoena that could experience auditory injury during UXO clearance activities and would represent only a very small proportion of the North Sea MU population. There are, however, uncertainties as to how all activities interact to contribute to an additive effect from underwater noise as a stressor. In a Before-After-Control-Impact design (BACI) study looking at foraging activity of harbour porpoise between baseline periods and different construction phases of the Beatrice and Moray East Offshore Wind Farms, Benhemma-Le-Gall et al., (2021) found an eight to 17% decline in porpoise occurrence in the impacted area during pile-driving and other construction activities with probability of detection negatively related to levels of vessel intensity and background noise.
- To some extent it is anticipated that animals will acclimatise to or compensate for such increases in underwater noise. For example, Graham et al. (2019) demonstrated acclimatisation by showing that the proportional response of harbour porpoise to piling noise decreased over the piling phase; from the first pile to the last pile the proportion of animals disturbed at a received level of 160 dB re 1 µPa decreased from 91.5% to 49.2%. Kastelein et al. (2019) suggest that harbour porpoise (a species with high daily energy requirements) may be able to compensate for period of disturbance as they can dramatically increase their food intake in a period following fasting within out any detriment to their health. In the Moray Firth, harbour porpoises displaced during wind farm construction of Beatrice and Moray East Offshore Wind Farms increased their buzzing activity, potentially compensating for lost foraging opportunities (although there may be an additional energetic cost from the fleeing and distance travelled to compensate for) (Benhemma-Le Gall et al., 2021).
Stressor 2. Injury due to collisions with vessels:
- This stressor is associated with vessel movement, the impact of which was assessed from different types of vessels and at different phases of the Proposed Development. Over the lifetime of the Proposed Development there will be a longer term risk to marine mammal receptors however, with designed-in measures in place the potential of experiencing injury is likely to be reduced and therefore it is not anticipated that an additive effect will occur. In addition, as mentioned in volume 2, chapter 10, Table 10.65, to some extent the noise from the vessels themselves would act antagonistically with this impact by deterring animals away from vessels and thereby further reducing the risk of injury due to collision. Furthermore, marine mammals in this area are already accustomed to high level of vessel activity. Buckstaff (2004) demonstrated that bottlenose dolphins increased their rate of whistle production at the onset of a vessel approach and then decreased production during and after it had passed. Increased whistle production may be a tactic to reduce signal degradation to ensure that information is being communicated in noisy environment, but it also demonstrates that animals are aware of approaching vessel from a distance. Findings of this study also corroborated previous research of Nowacek et al. (2001) who found that bottlenose dolphins swim in tighter groups during vessel approaches and that if the vessel is loud enough to be detected by an animal, the likelihood of collision decreases.
Stressor 3: Changes in prey communities:
- The assessment considers overall effect on fish and shellfish communities from multiple stressors (i.e. habitat loss, SSC, underwater noise, EMF etc) and therefore, in this respect, has taken an ecosystem-based approach. For some, stressors (e.g. underwater noise the effects on fish and shellfish) will be over the same timescales as marine mammals whilst for others, such as temporary habitat loss, timescales may be different (e.g. low mobility or sessile species may recover slowly). The assessment of effects, however, demonstrated that due to high mobility of marine mammals and ability to exploit different prey species, and small scale of potential changes in context of wider available habitat, the changes to fish and shellfish communities are unlikely to have an effect even from multiple stressors.
Multiple stressors: inter-related effect of all stressors
- Arrigo et al. (2020) studied synergistic interactions among growing stressors to an Arctic ecosystem and found that synergistic interactions amplify adverse stressor effects and the impact of synergy is predicted to increase with the magnitude of stressors. Findings of this study suggest that although large organisms at higher trophic levels, such as marine mammals, tend to be generally negatively impacted by increasing stressor interaction strength, the variability in the response to stressor is small and therefore reduces the probability of population collapse.
- For stressor 1 (increase in underwater noise), the potential for marine mammals to forage in different habitats and to compensate for reduced foraging time was discussed. The ability of displaced animals will therefore depend on the availability of prey resources in the habitat to which the animals are displaced. Studies have shown that for small, localised marine mammal populations with high site fidelity, there may be biological risks posed by displacement (Forney et al., 2017). Namely, due to the importance of the areas for survival, (i.e. high resource availability), animals may be highly motivated to remain in an area despite adverse impacts (Rolland et al., 2012). Thus, the inter-related effects of underwater noise and changes in fish and shellfish prey resources needs to be considered. Impacts on fish and shellfish prey resources (stressor 2) were predicted to be localised and short-term and therefore unlikely to contribute to an inter-related effect where animals are displaced beyond the boundaries of the Proposed Development area. Within the boundaries of the Proposed Development there may, however, be short term inter-related effects of noise disturbance and reduced fish and shellfish prey resources. For example, for animals remaining in proximity to the Proposed Development a disruption in foraging may not be easy to compensate for where there are shifts in the species composition or localised reductions of fish and shellfish communities. Gordon et al. (2003) suggested that it might be possible that damaged or disoriented prey could attract marine mammals to an area of impact, providing short term feeding opportunities but increasing levels of exposure, however, there have as yet been no attempts to investigate such indirect effects on marine mammals.
- The assessment has described only potential adverse effects but there is also potential for some beneficial effects on marine mammal receptors. The introduction of hard substrates in offshore wind farms can lead to the establishment of new species and new fauna communities which may in turn attract marine mammals (Lindeboom et al., 2011; Raoux et al., 2017; Fowler et al., 2018). Thus, even where there is potential for an inter-related effect between ongoing vessel noise during the operation and maintenance phase this may be compensated for, to some extent, by an increase in available prey resources. Russell et al. (2014) demonstrated that harbour seals and grey seals Halichoerus grypus moved between hard structures at two operational wind farms and used space-state models to predict where animals were remaining at these locations to actively forage and where they were travelling to the next foundation structure. Lindeboom et al. (2011) studied the ecological effects of the Offshore Wind Farm Egmond aan Zee and reported that even though the fish community was highly dynamic in time and space and only minor effects upon fish assemblages were observed during the operation and maintenance phase, some fish species, such as cod, positively benefited from the 'shelter' within the wind farm due to reduced fishing activity and the new hard substratum with associated fauna. Increased echolocation activity of harbour porpoise within the wind farm may be correlated with presence of additional food sources, suggesting that more harbour porpoises were found within the wind farm area compared to the reference areas due to increased food availability (Lindeboom et al., 2011).
- Inter-related effects between underwater noise and collision risk have been discussed previously and it is considered likely that marine mammals will move away from moving vessels in response to engine noise therefore reducing the risk of collision (classed as an antagonistic interaction). Alternatively, marine mammals may tolerate and persist in a highly stressed state (as a result of injury caused by underwater noise) while the vessels are approaching (Muto et al. 2018) and/or become habituated to vessel noise, not moving away from the vessel (McWhinnie et al., 2018), which would result in a synergistic interaction (Weilgart, 2011). Subsequently, the outcome will depend on the degree of habituation and a number of acoustical properties that allow an approaching vessel to be detected by a marine mammal species (Gerstein et al., 2005). However, with designed-in measures in place it is likely that any risk of injury from collision with vessels will be negligible.
- Evidence for the potential long-term effects of wind farms on marine mammals, related to all potential stressors, comes from monitoring programmes comparing baseline levels of abundance to construction and post-construction (operation and maintenance) phases. It is not common to prescribe impact monitoring studies with regard to marine mammals as a part of licence conditions in the UK and therefore data is sparse.
- At Scroby Sands Offshore Wind Farm, off the coast of Norfolk, aerial survey haul-out counts were conducted before, during and after the construction phases in order to monitor harbour and grey seal counts at haul-out site, located less than two kilometres away from the offshore wind farm array (Skeate and Perrow 2008; Skeate et al., 2012). Studies reported a decline in harbour seal numbers during construction, with numbers remaining lower over several subsequent years. However, the numbers of grey seals increased dramatically year after year throughout the construction and early operation and maintenance phase. It has been suggested that it is possible that changes in harbour seal numbers may be linked to rapid colonisation of competing grey seal (Skeate et al., 2012). Regional changes in patterns of haul-out use by harbour seals in the Wash coincided with the construction of the Scroby Sands Offshore Wind Farm, however, such changes in harbour seal number could have been part of wider regional dynamics (Verfuss et al., 2016).
- As a part of marine mammal monitoring at Robin Rigg Offshore Wind Farm, boat-based surveys for cetaceans were conducted before, during, and after construction (Walls et al., 2013). Data suggested that harbour porpoise were displaced from the wind farm site during the construction phase and operation and maintenance phase when compared to the pre-construction numbers. However, because there was only one year of pre-construction survey, natural variation cannot be ruled out as the reason for the observed change, especially since control survey locations, outside of the wind farm also appeared to experience declines in harbour porpoise density (Verfuss et al., 2016).
- With the expansion of offshore wind farms, post-construction monitoring programmes are being executed at various developments in Europe. A study on short-term effects of the construction of wind turbines on harbour porpoises at Horns Rev Offshore Wind Farm showed a decrease in porpoise acoustic activity within the wind farm at the onset of piling operations and subsequent recovery to higher levels a few hours after each piling operation was completed (Tougaard, et al., 2003). Another study at Horns Rev has shown that over the entire construction phase there was a negligible change in the abundance of harbour porpoise in the wind farm area compared to reference areas (Teilmann et al., 2008). Teilmann et al., (2008) also reported that during the operation and maintenance phase porpoise activity was higher in both the wind farm and reference area compared to baseline levels. At Nysted Offshore Wind Farm, initially during construction and the first two years of operation there were lower acoustic detections of harbour porpoises in the wind farm area with recovery starting to occur within two years after the end of construction suggesting that animals were gradually habituating and returning to the wind farm area (Teilman et al., 2008).
- Simulations of the response of harbour porpoise to wind farm construction undertaken by Nabe-Nielsen et al. (2011) suggested that wind farms already existing off Danish coast do not have impact on porpoise population dynamics and that the that construction of new wind farms is not expected to cause any changes in the long-term dynamics of the population. Similarly, various studies investigated possible interactions between seals and Danish offshore wind farms (Nysted Wind Farm, Rødsand II) and found that although there was a temporary reduction in the number of seals hauled out during construction operations (i.e. piling), there was no long-term effect on haul-out behaviour trends (Edren et al., 2010; McConnell et al., 2012).
- These examples of monitoring studies suggest that, despite the potential effects from multiple stressors associated with offshore wind farms, marine mammals can quickly recover and return to the impacted area. Therefore, these inter-related effects would not be significant in EIA terms.
- For offshore and intertidal ornithology, the following potential impacts have been considered within the inter-related assessment:
- disturbance and displacement from increased vessel activity and other construction/decommissioning activity
- temporary and long-term subtidal habitat loss/disturbance;
- increased suspended sediment concentrations; and
- disturbance and loss of seabed habitat arising from cable installation/removal within the Outer Firth of Forth and St Andrews Bay Complex SPA
- In addition volume 3, appendix 20.1, outlines potential interactions on ornithological receptors which could contribute to an ecosystem assessment.
-
Table 20.15
Open ▸
lists the inter-related effects (Proposed Development lifetime effects) that are predicted to arise during the construction, operation and maintenance phase, and decommissioning of the Proposed Development.
-
Table 20.15
Open ▸
also lists the inter-related effects where stressors may combine to lead to greater effects on offshore and intertidal ornithology receptors (receptor-led effects).
- One key stressor has been identified for offshore and intertidal ornithology. The assessment considers the overall effects on foraging seabirds from potential changes in prey communities that could be caused by disturbance, habitat loss, SSC, and therefore, in this respect, has taken an ecosystem-based approach. The assessment of effects, however, demonstrated that due to the high mobility of foraging seabirds and their ability to exploit different prey species, and the small scale of potential changes in context of wider available habitat, the changes to fish prey communities are unlikely to have a significant effect on foraging seabirds. Further discussion is presented in volume 3, appendix 20.1.
Table 20.15: Summary of Potential Inter-Related Effects for Offshore and Intertidal Ornithology from Individual Effects Occurring across the Construction, Operation and Maintenance and Decommissioning Phases of the Proposed Development and from Multiple Effects Interacting Across all Phases (Receptor-led Effects)
Table 20.15: Summary of Potential Inter-Related Effects for Offshore and Intertidal Ornithology from Individual Effects Occurring across the Construction, Operation and Maintenance and Decommissioning Phases of the Proposed Development and from Multiple Effects Interacting Across all Phases (Receptor-led Effects)
Table 20.15: Summary of Potential Inter-Related Effects for Offshore and Intertidal Ornithology from Individual Effects Occurring across the Construction, Operation and Maintenance and Decommissioning Phases of the Proposed Development and from Multiple Effects Interacting Across all Phases (Receptor-led Effects)
- The assessment of potential inter-related effects on seabirds from the impacts outlined above considered that due to the high mobility of foraging seabirds and their ability to exploit different prey species, and the small scale of potential changes in the context of wider available habitat, these effects are not anticipated to interact in such a way as to result in a significant effect on foraging seabirds. For further information on foraging seabirds see paragraph 256 onwards. Overall, it is concluded that these inter-related effects would not be significant in EIA terms.
20.7. Part Two: Ecosystem Effects Assessment
- An ecosystem is a community of living (biotic) organisms existing in conjunction with the non-living (abiotic) components of their environment, interacting as a system. In the marine ecosystem biotic components include plankton, seaweed, benthic communities, fish, seabirds and marine mammals and the abiotic components include air, salt water, seabed sediments and rock. These biotic and abiotic components are linked together through nutrient cycles and energy flows (LibreTexts, 2022).
- Biodiversity, the variety of life on Earth, is the key indicator of the health of an ecosystem. A wide variety of species will cope better with external pressures than a limited number of species in large populations. Even if certain species are affected by climate change or human activities, the ecosystem as a whole may adapt and survive (European Commission, 2022).
- The purpose of this ecosystem-based assessment is to qualitatively assess the potential impacts of the Proposed Development at the ecosystem level, to better understand how predator – prey relationships could be altered and how this could impact the functioning of the ecosystem. Whilst not included in the 2020 Berwick Bank Wind Farm Scoping Opinion (MS-LOT, 2021), the 2020 Berwick Bank Wind Farm Offshore Scoping Report (SSER, 2020) included a description of the need to address effects at an ecosystem level: “Increasingly there is a need to understand potential impacts holistically at a wider ecosystem scale rather than via the standard set of discrete individual receptor assessments. This assessment should focus on potential impacts across key trophic levels particularly in relation to the availability of prey species. This will enable a better understanding of the consequences (positive or negative) of any potential changes in prey distribution and abundance from the development of the wind farm on seabird and marine mammal (and other top predator) interests and what influence this may have on population level impacts.”
- This section provides a summary of the abiotic and biotic components of the marine ecosystem within the Proposed Development array area and Proposed Development export cable corridor.
- The Proposed Development will be located in the central North Sea, a shallow continental shelf sea, approximately 47.6 km offshore of the East Lothian coastline and 37.8 km from the Scottish Borders coastline at St. Abbs. The bathymetry of the Proposed Development array area is influenced by the presence of Marr Bank and the northern extent of the Berwick Bank. These two bank features are defined as Shelf Banks and Mounds. A maximum seabed depth is recorded at two locations where deep channels cut into the seabed east and west of the central point of the Proposed Development array area (68.5 m Lowest Astronomical Tide (LAT)). The shallowest area is observed in the west of the Proposed Development array area (33.4 m LAT). The average seabed depth across the array area is 51.7 m below LAT.
- The seafloor morphology within the Proposed Development array area and export cable corridor is very varied.
Table 20.16
Open ▸
summaries the types of morphological features present within the Proposed Development.
Table 20.16: Seafloor Morphology Within the Proposed Development Array Area and Export Cable Corridor
- Most of the seabed within the Proposed Development array area is ‘featureless’, with the exception of the southern and north-western extents which are dominated by megaripples, sand waves, ribbons and bars. Boulders are also prevalent across the array area and are either represented as isolated boulders or as clusters.
- Seabed sediments present within the Proposed Development are summarised in
Table 20.17
Open ▸
.
Table 20.17: Seabed Sediments within the Proposed Development
- The benthic communities within the Proposed Development array area and Proposed Development export cable corridor are characterised by echinoderms (sea urchins and brittle stars), bivalves and polychaetes in both the Proposed Development array area and Proposed Development export cable corridor, both exhibiting similar diverse communities. The predominantly sand and coarse sediment habitats within the Proposed Development are typical of, and widespread throughout, the UK and in the northern North Sea. The muddy sediments in the central section of the Proposed Development export cable corridor are characterised by communities of sea pens and burrowing megafauna. Additionally, both the Proposed Development Array area and Proposed Development export cable corridor overlap with the Firth of Forth Banks Complex marine protected area which is designated for ocean quahog, offshore subtidal sand and gravels, shelf banks and mounds, moraines representative of the Wee Bankie Key Geodiversity Area (volume 2, chapter 8).
-
Table 20.18
Open ▸
provides a summary of the seven main broad subtidal habitats present within the Proposed Development area.
Table 20.18: Broad Subtidal Habitat Types
- The other species groups which are part of the biotic components of the ecosystem include fish, seabirds and marine mammals. These groups are considered further in the following sections 20.7.4, 0, 20.7.8, 20.7.9 and 20.7.10.
- Trophic levels describe the hierarchal levels which organisms occupy in the food web. Primary producers, such as phytoplankton and seaweed, form the lowest trophic levels in marine food webs. They are consumed by primary consumers (herbivores) such as zooplankton, some crustaceans (e.g. copepods) and molluscs (e.g. clams, snails, mussels). Secondary consumers (carnivores or omnivores) such as fish larvae, Atlantic herring Clupea harengus (hereafter herring) and lesser sandeel Ammodytes marinus (hereafter ‘sandeel’), and some crustaceans (e.g. crabs, shrimp) feed on primary consumers and primary producers. These species support tertiary consumers (carnivores), including some fish species, and cephalopods (e.g. octopus and squid species). Seabirds, along with marine mammals, large marine fish and elasmobranchs (sharks, skates and rays), are the top predators of the natural marine food web. An example of a marine food web which illustrates the interactions between the different trophic levels is presented in
Figure 20.1
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Figure 20.1: Significant Interactions Modelled Between Functional Groups and Drivers (From Lynam et al., 2017)
