Marine renewable developments in Scottish waters: review of benthic ecological surveying

1 Introduction

1.1 Background

The pace of development in the offshore wind, wave, and tidal sectors in Scotland, referred to here as Marine Renewable Energy (MRE), has increased significantly in recent years. This is especially the case in the offshore wind sector with the ScotWind and Innovation and Targeted Oil and Gas (INTOG) leasing rounds now completed. This increased development activity is likely to continue to meet Scottish and wider UK decarbonisation targets. The Scottish Government’s policy is to ensure that planning and consenting decisions are informed by sound evidence and make reasonable efforts to address any gaps in knowledge in line with the National Marine Plan (Scottish Government, 2015). This has led the Scottish Marine Energy Research (ScotMER) programme to commission a review of benthic baseline and monitoring survey tools, techniques and designs, in the context of marine and offshore renewables, and to provide recommendations for such surveying in Scottish waters.

Consequently, this report provides a detailed appraisal of possible seabed ecology surveying options. It also recommends how best to plan seabed ecology surveys for the overall sequence of characterisation and monitoring activities at each stage of Marine Renewable Energy Developments (MREDs). These recommendations are supported by descriptions and examples of good practice and tools which can be applied. The rational as to why these approaches have been adopted and showcased is also given.

Scotland has a rich marine geodiversity and biodiversity that are intrinsically linked to the unique physical characteristics and processes that occur within the marine environment. These features and patterns have some similarities to the other parts of the UK but are also distinctive and, in several cases, are quite different. The equipment and methods employed elsewhere are therefore not necessarily suitable for the inshore and offshore waters around Scotland.

To date there has been less offshore wind development around Scotland than elsewhere in the UK. Conversely, although at much smaller scale, there has been more wave and tidal development in Scotland. This situation is however rapidly changing, particularly for offshore wind, with the ScotWind and INTOG leasing rounds meaning an expansion of future offshore wind capacity in Scottish waters. Offshore wind has therefore already become the dominant MRE activity and will likely continue as the leading sector over the coming decades.

As this development process takes place much will be learned, further experience gained, and ambient conditions may will change. Consequently, the key issues of today may be different to those of the future. In addition, as well as the new, innovative techniques for monitoring benthic species and habitats that have recently become available, more new techniques may be developed in the future. Regular reviews of the recommendations and guidance provided will be necessary to ensure that the approaches remain appropriate and fit for purpose.

This guidance is intended to be used to make recommendations for best practice only.

1.2 Aims and objectives

The overarching goal of this report is to review possible seabed ecology surveying options and to recommend a standard approach to benthic monitoring at MRE sites in Scotland. This work will help ensure that benthic environmental assessments for planned and future offshore wind, wave and tidal developments, as well as linked infrastructure, can be based on agreed principles and recommendations using the best available evidence. This will be applicable to all stages and sectors of MREDs and is designed to be effective and adaptive to the diversity and uniqueness of Scotland’s marine waters.

The specific objectives of this work were:

• To review existing benthic ecological survey guidance, peer reviewed literature, grey literature and survey techniques currently employed at MRE sites in the UK and internationally.
• To review and assess new and emerging survey technologies and analytical techniques that could be applied to MREDs, including an assessment of relative costs, limitations, data quality, survey efficiencies and logistics.
• To provide recommendations for scientifically robust, cost-effective monitoring approaches with appropriate powers to detect change.

The findings from these investigations were then considered in the context of certain specific priority surveying objectives to provide an assessment of the most effective methods and sampling designs to meet the different requirements. The priority surveying objectives addressed were:

• Determining the extent, distribution and condition of benthic species and habitats;
• Monitoring changes in diversity and community composition over time at different spatial scales;
• Measuring potential habitat recovery and enhancement at different stages of MRE development;
• Quantifying potential habitat enrichment from enhanced biomass growth on hard structures;
• Identifying metrics and strategies to combine approaches and address multiple objectives; and
• To identify opportunities for such approaches to contribute towards predictive habitat models and demonstrate how these can be applied to case studies in Scottish waters.

1.3 Approach

The approach taken in this study is set out below. There were three main stages: context and scoping; cataloguing; and strategic planning recommendations (See Figure 1.1).

The context and scoping stage considered the key factors that could influence the planning and execution of seabed ecological survey work. The key context factors were the distinctive Scottish marine conditions, established practices and experience as well as published guidance and other literature. The key scoping factors included specification of the development, potential impacts, habitat presence and sensitivity, and the operational context.

The cataloguing stage consisted of two main streams. The first was associated with the various sampling tools, techniques and methods that can be applied to ecological surveying of the seabed. The second was associated with the characteristics of the different project activities.

The aim of the strategy planning and recommendations stage was to bring the scoping and cataloguing information together at both strategic and project-specific levels, creating an overall framework within which to decide upon the most appropriate surveying approach. The project-specific level considered how the various surveying tools and techniques could be collated into a coherent plan, which could be followed through each stage of the project lifecycle. These approaches generated a high-level set of recommendations about how to plan and implement a programme of seabed ecology surveys for MREDs.

In addition to the above, stakeholder engagement was employed to collate the views of developers, researchers, and Statutory Nature Conservation Bodies (SNCB).