20. Inter-Related Effects

20.1. Introduction

  1. This chapter of the Array Environmental Impact Assessment (EIA) Report presents the assessment of the likely significant effects (LSE1) (as per the “EIA Regulations”) on the environment in relation to inter-related effects as a result of the Ossian Array which is the subject of this application (hereafter referred to as “the Array”). Specifically, this chapter assesses the inter-related effects during the construction, operation and maintenance, and decommissioning phases.
  2. The assessments presented within this chapter have been informed by the individual chapters relevant assessment of effects and conclusions and their associated appendices in this Array EIA Report including:
  • volume 2, chapter 7: Physical Processes;
  • volume 2, chapter 8: Benthic Subtidal Ecology;
  • volume 2, chapter 9: Fish and Shellfish Ecology;
  • volume 2, chapter 10: Marine Mammals;
  • volume 2, chapter 11: Offshore Ornithology;
  • volume 2, chapter 12: Commercial Fisheries;
  • volume 2, chapter 13: Shipping and Navigation;
  • volume 2, chapter 14: Aviation, Military and Communications;
  • volume 2, chapter 15: Infrastructure and Other Users;
  • volume 2, chapter 18: Socio-Economics; and
  • volume 2, chapter 19: Marine Archaeology.

20.2. Purpose of the Chapter

  1. The Array EIA Report provides the Scottish Ministers, statutory and non-statutory stakeholders with adequate information to determine the LSE1 of the Array on the receiving environment. This is further outlined in volume 1, chapter 1.
  2. The purpose of this Inter-Related Effects Array EIA Report chapter is to describe:
  • the receptor groups considered within the inter-related effects assessment;
  • the potential for effects on receptor groups across the three key phases of the Array (construction, operation and maintenance and decommissioning);
  • the potential for multiple effects on a receptor group, as presented within the topic specific chapter, to interact to create inter-related effects; and
  • the inter-related effects across different trophic levels of the ecosystem, affecting the environment.
  1. This chapter follows the ecosystem-based approach, which is defined as “a strategy for the integrated management of land, water and living resources that promotes conservation and sustainable use in an equitable way” (Convention on Biological Diversity (CBD), 2023). The purpose of the ecosystem-based approach is to assess how the Array may interact at the ecosystem level, affecting the environment. This has been carried out following stakeholder advice received during the Scoping process (MD-LOT, 2023)

20.3. Study Area

  1. Due to the differing spatial extent of effects experienced by different offshore receptors, the study area for potential inter-related effects varies according to topic and receptor. The likely significant inter-related effects assessed in Part One of this chapter are, therefore, also limited to the study area defined in each of the topic specific chapters outlined in section 20.1.
  2. As the largest study area relates to offshore ornithology, this is the maximum limit of the inter-related effects study area.

20.4. Policy and Legislative Context

  1. Volume 1, chapter 2 of the Array EIA Report presents the policy and legislation of relevance to renewable energy infrastructure.
  2. Of relevance to the inter-related effects chapter, Article 3(1) for the EIA Directive requires that the interaction between the environmental factors (e.g. human health, biodiversity, land, soil, water, air and climate etc) must be identified, described and assessed in the Array EIA Report. Under the EIA Regulations, there is a requirement to consider inter-relationships between topics that may lead to environmental effects. Other than this, there is no policy relevant to inter-related effects in Scotland, thus this chapter has been compiled following advice from stakeholders as detailed in Table 20.1   Open ▸ .

20.5. Consultation

  1. Table 20.1   Open ▸ presents a summary of the key issues raised during consultation activities undertaken to date specific to inter-related effects for the Array and in the Ossian Array Scoping Opinion (Marine Directorate – Licensing Operations Team (MD-LOT), 2023) along with how these have these have been considered in the development of this Array EIA Report chapter. Further detail is presented within volume 1, chapter 5.
Table 20.1:
Summary of Issues Raised During Consultation and Scoping Opinion Representations Relevant to Inter-Related Effects

Table 20.1: Summary of Issues Raised During Consultation and Scoping Opinion Representations Relevant to Inter-Related Effects

20.6. Data Sources

  1. The baseline environments for the receptor groups considered in section 20.8 of this chapter are specific to each receptor group and are, therefore, set out in the detail in the relevant topic chapters (see section 20.1).
  2. This chapter draws on the conclusions made within the technical chapters for the assessment of impacts acting in isolation on the receptor groups. The relevant sections drawn upon in this inter-related effects assessment are presented in the Array EIA Report in volume 2, chapters 7 to 19 (excluding volume 2, chapter 16).
  3. It should be noted that the inter-related effects impact assessment assesses the LSE1 from the Array only as set out in volume 2, chapters 7 to 20, and not those from other projects other than the Proposed offshore export cable. Inter-related effects from other projects are considered in the cumulative effects sections of the relevant chapters (volume 2, chapters 7 to 20).
  4. Specific guidance relevant to the approach to the assessment in each part of this chapter has been stated in section 20.7.

20.7. Assessment Methodology

  1. NatureScot highlighted that “increasingly there is a need to understand potential impacts holistically at a wider ecosystem scale in addition to the standard set of discrete individual receptor assessments. ( Table 20.1   Open ▸ ) In response, the assessment presented in this chapter has been split into two parts, Part One: Receptor Based Inter-Related Effects Assessment outlines the assessment required as part of the EIA Regulations, and Part Two: Ecosystem Effects Assessment looks to address the request from NatureScot for a wider ecosystem scale assessment.

20.7.1. Part One: Inter-Related Effects Assessment Method

  1. The following sections present the approach used for the inter-related effects assessment of the Array. For the purpose of this assessment, the following definition has been used for the term inter-related effect:
  • an “Inter-Related Effect” is when there are multiple effects upon the receptor arising from the Array, occurring either where a single effect acts upon a receptor over time to produce a potential additive effect or where a number of separate effects, such as underwater noise and habitat loss, affect a single receptor, for example marine mammals.
  1. Table 20.2   Open ▸ presents full definitions of the terms used in this assessment.

 

Table 20.2:
Definitions of Array Lifetime and Receptor-Led Inter-Related Effects

Table 20.2: Definitions of Array Lifetime and Receptor-Led Inter-Related Effects

 

                        Approach to assessment

  1. The following guidance documents have been followed relating to the assessment of inter-related effects:
  • The Guidelines for the Assessment of Indirect and Cumulative Impacts as well as Impact Interactions (EC, 1999); and
  • Institute of Environmental Management and Assessment (IEMA) Environmental Impact Assessment Guide to Shaping Quality Development (IEMA, 2016).
  1. The approach for assessing the potential inter-related effects on each receptor or receptor group follows the steps summarised in Table 20.3   Open ▸ and outlined.

 

Table 20.3:
Staged Approach to Assessing Inter-Related Effects

Table 20.3: Staged Approach to Assessing Inter-Related Effects

 

                        Stage 1: Topic specific assessment
  1. The first stage of the assessment of inter-related effects is presented in each of the Array EIA Report topic chapters and comprises the individual assessments of effects on receptors across the construction, operation and maintenance and decommissioning phases of the Array.
                        Stage 2: Identification of receptor
  1. The second stage involved a review of the assessments undertaken in the topic specific chapters to identify the ‘receptor groups’ requiring assessment within this chapter. The term ‘receptor group’ is used to highlight that, for the purposes of the assessment, the potentially sensitive receptors have been grouped together e.g. marine mammals. The use of a ‘receptor group’ approach has been agreed with stakeholders via the Ossian Array Scoping Opinion (MD-LOT, 2023). The receptor groups assessed can be broadly categorised as those relating to the physical environment, the biological environment and the human environment, as follows (see paragraph 2 for references to chapters):
  • physical environment:

–           physical processes.

  • biological environment:

–           benthic subtidal ecology;

–           fish and shellfish ecology;

–           marine mammals; and

–           offshore ornithology.

  • human environment

–           commercial fisheries;

–           shipping and navigation;

–           aviation, military and communications;

–           infrastructure and other users;

–           socio-economics; and

–           marine archaeology.

                        Stage 3: Identification of potential inter-related impacts on receptor groups
  1. Following the identification of receptor groups, the potential inter-related impacts on those receptor groups were identified via a review of the assessment sections for each relevant topic chapter. The judgement to which impacts may result in inter-related effects upon receptors associated with the Array was based on the professional judgement and experience of the project management team.
  2. It is important to recognise potential linkages between the topic-specific chapters, whereby effects and receptor groups assessed in each chapter have the potential for secondary effects on any number of other receptors. Examples include:
  • volume 2, chapter 8 addresses effects on benthic habitats and species arising from changes to the physical environment (as described in volume 2, chapter 7);
  • volume 2, chapters 8 and 9 addresses effects on fish and shellfish receptors arising from the impacts on benthic habitats;
  • volume 2, chapters 10 and 11 assess the effects on marine mammal and seabird receptors (respectively) arising from potential changes in benthic habitats and the distribution of fish, which from their principal prey (as described in volume 2, chapter 9);
  • volume 2, chapter 13 addresses effects on shipping and navigation receptors arising from potential impacts as a result of a combination of effects caused by marine mammal collision (as described in volume 2, chapter 10);
  • volume 2, chapter 14 assesses the effects on aviation and radar receptors arising from potential impacts on restriction of access to infrastructure by both helicopters and vessels (as described in volume 2, chapter 15); and
  • volume 2, chapter 15 asses the effects on infrastructure and other user receptors arising from potential impacts on aggregate resource as a result of potential increase in suspended sediment concentrations (SSCs) and deposition and effects on sediment transport pathways (as described in volume 2, chapter 7).
  1. Where such linked relationships arise these have been fully assessed within the individual topic chapters. This chapter on inter-related effects therefore summarises the consideration of these inter-related effects on linked receptors already set out in the topic specific chapters.
  2. It should be noted that this chapter does not consider that there are likely to be any cumulative receptor-led effects from offshore and onshore activities associated with the Array. This is primarily due to the uncertainty around the location of the offshore export cable and the location of landfall for the export cable in Lincolnshire (at a significant distance from the Array). The close proximity of the offshore export cable occurs where the cable exits the site and the cumulative interaction will be reduced as the cable moves further away from the Array. Furthermore, despite the uncertainty around the location of the offshore export cable and location of the landfall for export cable in Lincolnshire, with the designed in measures in place for the Array, the Applicant considers it to be unlikely that there will be any cumulative receptor-led effects from offshore and onshore activities associated with the Array. However, taking a precautionary approach, the Applicant has assessed the cumulative potential for inter-related effects with the Proposed offshore export cable in section 20.8.2. This will be further assessed in a separate EIA Report for the offshore and onshore export cable works, following the agreement of the landfall site, Proposed offshore export cable corridor(s) and Proposed onshore transmission infrastructure.
                        Stage 4: Assessment of inter-related effects on each receptor group
  1. Individual effects on each of the key receptor groups have been identified across the three Array phases (i.e. Array lifetime effects) as well as the interaction of multiple effects on a receptor (i.e. receptor-led effects), as defined in Table 20.2   Open ▸ .
  2. The significance of the individual effects is presented in the summary of effects, mitigation measures and monitoring tables for each receptor group within the relevant topic chapters (all conclusions for significance of effect defined in the topic chapters assume successful implementation of mitigation measures where appropriate). A descriptive assessment of the scope for these individual effects to interact to create a different or greater effect is then undertaken (section 20.8). This assessment incorporates qualitative and, where possible, quantitative assessments. Each topic-specific assessment, outlined in Table 20.4   Open ▸ to Table 20.14   Open ▸ , presents an assessment of the significance of effect to any such inter-related effect.
  3. The inter-related effects assessment presents and utilises the maximum significant adverse effects for the Array (i.e. the maximum design scenarios including successful implementation of measures adopted as part of the Array where appropriate), noting that individual effects may not be significant at the topic-specific level but could become significant when their inter-related effect is assessed. Effects of moderate significance or above are therefore considered important in the decision-making process, whilst effects of minor significance or less warrant little, if any, weight in the decision-making process. Effects of moderate significance or above may occur in only one phase of the lifetime of the Array (e.g. during the construction phase but not the operation and maintenance or decommissioning phases). Where this is the case, it has been made clear that, as a result, there will be no inter-related effects across the lifetime of the Array.

20.7.2. Part Two: Ecosystem Based Effects Assessment Method

  1. The purpose of the ecosystem-based assessment is to qualitatively assess the potential effects of the Array at the ecosystem level, to better understand how predator – prey relationships could be altered and how this could impact the functioning of the ecosystem.
  2. This structure of Part Two: Ecosystem Effects Assessment is as follows:
  • overview;
  • ecosystem baseline;
  • the marine food web;
  • the key predator species;
  • the key prey species;
  • how the food system works;
  • future ecosystem baseline;
  • existing pressures on prey species;
  • effects of the Array on prey species; and
  • effects of the Array on predator species.
  1. Information and conclusions from the relevant chapters of the Array EIA Report and their corresponding technical reports have been used to build up a picture of the marine ecosystem in the locality of the Array and inform the baseline for the ecosystem assessment. This information has also been used to inform the assessments within these sections to ultimately conclude whether the Array, and cumulatively with other plans and projects, is likely to result in changes to prey species which in turn will result in changes to predator species and therefore result in likely significant ecosystem effects.
  2. As new surveys and studies bridge knowledge gaps, we are developing a greater understanding of how offshore wind farms impact marine ecosystems. Details of two research programmes are provided below, the outcomes of which are and will be used to inform policy measures and provide guidance and recommendations on improving stakeholder confidence in the sustainable delivery of offshore wind farms. Furthermore, these projects are key to informing ecosystem assessment approach.

                        PrePARED Project

  1. Following guidance from the Scottish Ministers, detailed in Table 20.1   Open ▸ , the PrePARED project (PrePARED, 2022) has been used to assist in the understanding of predator-prey relationships in and around fixed offshore wind farms.
  2. Funded by the Offshore Wind Evidence and Change Programme and Crown Estate Scotland, the PrePARED project seeks to better understand how seabirds and marine mammals respond to offshore wind developments and the mechanisms underpinning their responses, particularly changes in prey distribution. An increased certainty on the magnitude of cumulative impacts will facilitate deployment of offshore wind farms at the pace and scale required to help meet the United Kingdom (UK) government’s renewable energy targets and reach net-zero emissions.
  3. At the time of writing this chapter, the 2022 Annual Report was the latest version available from PrePARED which summarises the first year of the five-year project (PrePARED, 2022). Part of the project activities included fish, seabird and marine mammal data collection in and around offshore wind farms in the Firth of Forth and Tay and the Moray Firth. Examples of tasks conducted as part of the project include:
  • surveying fine-scale fish response to offshore wind farms;
  • collating historical data to determine large-scale fish distribution;
  • collating historical data to develop seabird spatial distribution models;
  • designing acoustic telemetry arrays to track fish and marine mammal movement; and
  • collating historical data from various methods to develop marine mammal distribution models.

                        Ecological Consequences of Offshore Wind (ECOWind)

  1. The ECOWind research programme seeks to investigate all possible effects of offshore wind farms on marine biodiversity (ECOWind, 2024). ECOWind are currently undertaking four projects:
  • BOWIE

–           The BOWIE project will use a combination of environmental and social research to gain knowledge on the impact of wind expansion on seabed invertebrate and fish species, taking into consideration other pressures on the marine environment including construction noise and vibration, electromagnetic fields and elevated temperatures associated with cabling.

  • ECOWind ACCELERATE

–           The ECOWind ACCELERATE project will investigate the ecological implications of accelerated seabed mobility around windfarms. Scientists will be studying the combined impacts of climate change and offshore wind farms on seabed habitats and organisms and how baseline changes can cause affect the wider marine ecosystem around the UK.

  • ECOWINGS

–           The ECOWINGS project will investigate the cumulative effects of offshore wind on key seabird species, establishing pathways for strategic compensation to ensure net gain for seabird populations and the wider marine ecosystem.

  • PELAgIO

–           The PELAgIO project will investigate the impacts that offshore wind development can have on the marine food chain.