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30th November 2021

The impact of shadow flicker or pulsating shadow effect, caused by wind turbine blades, on Atlantic salmon (Salmo salar)

As the need for onshore wind energy expands, such climate adaptation measures may have unintended and potentially significant influences on how fish respond when situated next to rivers or streams. The aim of this project was to examine evidence of potential impacts of shadow flicker, from wind turbine blades, on Atlantic salmon in the context of species conservation management and climate mitigation strategy in Scotland. Our current understanding of the possible effects of shadow flicker on Atlantic salmon was investigated by reviewing the available literature (peer-reviewed and grey from national and international sources) for existing studies of a similar or relevant nature. Various databases and web-based search engines were used to identify these studies, relevant information was extracted and summarised, and potential impacts across the salmon’s lifecycle identified. There was no direct evidence available, either from laboratory experiments or studies of wild fish, that describe the effects of shadow flicker on Atlantic salmon or any other fish species. Based on the available literature, and our expert opinion, there is currently insufficient evidence to support or refute any biological or ecological impact of shadow flicker on Atlantic salmon. The review has highlighted a lack of basic understanding of the role light patterns may play for Atlantic salmon in rivers and further research is recommended. At present there is no evidence to support any change to related policy guidance. However, under the precautionary principle, some advice for best practice might be advised to prevent shadow flicker being cast on river surfaces. Where appropriate, potential mitigation methods were identified that could reduce any impacts on Atlantic salmon should impacts of shadow flicker on fish be demonstrated in the future.

21st October 2021

Performance metrics from the past 5 years of CREW

Performance metrics from the past 5 years of CREW
Performance metrics for the past 5 years of CREW
21st October 2021

Scottish One Health AMR Register (SOHAR)

SOHAR report front cover

Living within a viral pandemic has brought home the importance of our relationship with microbes. Yet we are in the midst of another microbial risk that threatens to have a much larger impact on our lives. Microbes (bacteria, viruses, fungi or protists) that cause disease in humans, animals or plants are normally treated with antimicrobial drugs to control their numbers. Drug use has become routine since Alexander Fleming’s famous discovery of penicillin, in public health, veterinary practice and crop protection. Since all microbes are living entities, they adapt and evolve, generating resistance to the drugs, to overcome their function. The unintended consequence from misuse or dissemination of the pharmaceuticals has led to widespread resistance, even in microbes that were previously benign. Antimicrobial resistant (AMR) microbes are transmitted through the same pathways as pathogenic (harmful) microbes, whether in indoor or outdoor environments. Combined with the low level of development of novel drugs to treat AMR microbes, this has left us in a critical state.

To address this problem, the World Health Organisation (WHO) developed a coordinated global response, enabling countries to develop National Action Plans to combat AMR. The action plans are built on five principles to improve awareness and understanding of the problem, strengthen the scientific evidence-base, reduce the incidence of human infections with AMR microbes, optimise pharmaceutical use in human and animal health, and invest in new diagnostics, vaccines and interventions. To understand how the action plans are addressed nationally, it is necessary to record the breadth and scope of relevant activities. Therefore, this project aimed to determine activities relating to AMR research associated with Scotland that had taken place in the past five years, and to relate them to the UK National Action Plan (2019-2024). It generated a register of activities: the Scottish One Health AMR register (SOHAR).

Outcomes: The project identified a large number of AMR-related activities, principally related to animal and human health. The lowest representation related to transmission from food or wildlife, with representation for transmission from the environment and water mid-range. A proportion of activities related to the social sciences. Mapping the activities to the UK action plan revealed a strength for Scottish-associated research related to AMR in animals, for laboratory capacity and surveillance of AMR in animals and understanding AMR spread between humans, animals and the environment. Another strong area was in lowering the burden of human infection, by turning research into practice for effective infection prevention and control (IPC). Areas with limited representation were in the translational pipeline for end-user application, although this could reflect how the data was collected. Overall, the register has the potential to deliver multiple impacts allowing stakeholders and organisations to identify the strengths, or areas that need to be addressed in more detail. The report recommends continuance of the register and accessibility in the public domain.

15th September 2021

The epidemiology and disease burden potential relating to private water supplies in Scotland

Epidemiology PWS

Around 3.3% of Scotland’s population (182,516 people) are served by private water supplies (PWS) together with transient visitors such as tourists. This project sought to develop an understanding of the epidemiology and disease burden contribution of PWS in Scotland on the public health of the populations (indigenous and transient) exposed to the PWS. The project report comprises a risk profile to provide current knowledge about the risks of gastrointestinal pathogens associated with private water supplies in Scotland. This is supplemented with preliminary work looking at the linkage of human gastrointestinal illness with private water supply microbiological failures and the scoping out of a quantitative microbiological risk assessment approach for PWS in Scotland. 

13th September 2021

Aerosol/droplet sampling of wastewater for SARS-CoV-2

Aerosol Report Front Cover

Since the onset of the COVID-19 pandemic in early 2020 - caused by the spread of the SARS-CoV-2 virus - scientists, engineers and epidemiologists have grappled with obtaining information about the extent of the prevalence of infected people in the community in different settings. Understanding community prevalence is an essential component of the fight against the virus, and plays a major role in informing public health officials and help Governments plan for the inevitable waves of infection.  Wastewater based epidemiology (WBE), in which the extent of infection in a community can be assessed by sampling and identifying viral RNA in wastewater, has been implemented in Scotland, rest of UK and elsewhere to help provide epidemiology data. This has been very successful in the main, however, the resolution of the system tends to be at wastewater treatment plant (WWTP) catchment level or major sewer lines leading to the WWTP.

In some cases it may be necessary to assess the level of infection close to the source so that data can be obtained at a building or building complex level. This project, led by Prof. Michael Gormley (Heriot Watt University) and sponsored by CREW, sought to investigate and prove the concept of detecting viral RNA in aerosols and droplets found in building sanitary plumbing systems (SPS). The hypothesis tested was that when a toilet (which contains faeces, urine, or vomit of a person infected with SARS-CoV-2) is flushed, the virus will be present in the aerosols and droplets generated within the system, and then be carried in the airstreams. Sampling the airstreams will capture the aerosols and droplets which can then the tested for the presence of viral RNA.

Findings: The research was carried out on a dedicated 2-storey SPS test rig with the capability to flush micro-organisms and detect their transport across two floors of a building.  The research demonstrated that viral RNA can be detected using bioaerosol sampling methods within a building’s sanitary plumbing system and so very near-source sampling is possible. The work also identified some practical implications for WBE in this setting, for example, sampling aerosols from SPS is influenced by environmental and water chemistry conditions, e.g. relative humidity and dissolved salts within the system.  It was also discovered that the most effective location to detect viral RNA is near the base of the vertical stack or from the horizontal collection drain at the bottom of the vertical stack, just before it connects with the main sewer using passive methods, thus greatly simplifying sampling. This proof of concept investigation has established effective very near-source sampling techniques in a laboratory setting and the next phase will be to test in live buildings which is already underway.

8th September 2021

Phosphorus recycling possibilities considering catchment and local agricultural system benefits: a review and regional Scottish case study

P Flows Report_Front Cover

This project was developed to downscale aspects of Scotland’s country-scale phosphorus (P) mass balance by looking at potential for regional recycling. The research firstly examined the background context of P sustainability in terms of recycled P sources, usage opportunities and constraints via a literature review. Secondly a case study, with a waterbody to regional basis, was developed to examine coupling that region’s P-rich resources from wastes with the local agricultural land for goals to both offset the raw imported resource of chemical phosphate fertiliser and limit P pollution of waters. Factors such as material availability, compositions, costs and transport were examined alongside the spatial distribution of agricultural land, crop usage constraints and basic environmental pollution risks.

Initial case study selection of a waterbody with P water quality failure led to examining a rural catchment bordering a city with extensive availability of current and potential recyclable P in excess of the catchment farmland. The inventories of available materials within municipal wastewater and commercial digestate sectors were complex to assemble. To effectively utilise the recycled P masses materials as fertiliser replacement not exceeding crop requirements it was necessary to go beyond the catchment bounds to a larger region of increased planning complexity (in terms of road transport distances, multiple planning boundaries). Simplifications were necessary in the assessment of swapping environmental risks between chemical and recycled P fertiliser forms, since practical tools and models are not yet available across diverse material compositions, soil and crop management combinations.

Phase I Climate Change Impact Assessment: Evaluating evidence-based changes in management strategy to steer adaptive responses for mitigating climate change impacts on water quality in Scottish standing waters

Scotland’s water environment is facing a climate crisis. This changing climate is already impacting on many standing waters across Scotland in the wake of the warmest decade (2011-2020) on record. There is an urgent need for collaborative environmental leadership to up the scale, pace and impact of fit for purpose climate mitigation strategies to safeguard the integrity, biodiversity, and sustainable use of Scottish standing waters now and in future.

The vision is that through this project Scotland will receive the evidence-base it needs to help steer the formation, prioritisation, and implementation of adaptive responses by key stakeholder organisations, for example through policy-based to nature-based solutions and coordinated management practices, to mitigate climate-driven risks and impacts these could have on the water quality of Scottish standing waters under different climate scenarios.




Project Scope

The overall aim of Phase I is to produce an evidence-base which addresses the urgent need to assess and understand climate change impacts on the water quality of Scottish standing waters[1]. This evidence-base will be used to inform and serve the collaborative development of mitigation strategies in Phase II for realising impact at multiple scales.


Research questions to be answered through this project:

  • Is there evidence of a causal link between climate change impacts and water quality issues in Scottish standing waters at national, regional, and local scales?
  • What are the main types of climate-driven water quality impacts identified in Scottish standing waters, under current and projected climate change scenarios?
  • Which areas, locations, and types of Scottish standing waters are currently most to least at risk in terms of water quality issues from climate change impacts at national, regional, and local scales?
  • Which areas, locations, and types of Scottish standing waters will likely experience exacerbated water quality risks under projected climate change scenarios?
  • What factors contribute to the risk of water quality issues from climate change impacts in Scottish standing waters at national, regional, and local scales?
  • What factors need to be considered for mitigating climate-driven risks to water quality in Scottish standing waters, under current and projected climate change scenarios?

[1] For the purpose of this project proposal Scottish standing waters will include lochs, reservoirs, and other locally important still waters. Using the criteria in Annex 1 of the SSSI site selection guidelines (2018) we would not expect this project scope to cover standing waters which are temporary or less than 1ha in area or 1m in depth (we recognise the value of ponds and pools however they are likely to be functionally and biologically distinctive with different data/evidence/tools available; canals are recognised as important but also excluded from this project scope as they are considered slow moving waters).

Project Objectives

Objective 1. Use Phase I to establish and deliver a preliminary evidence-base to evaluate the extent to which:

1.1 Climate change impacts are driving a current and future risk of water quality issues in Scottish standing waters with assessment undertaken at national, regional, and local scales.

1.2 Climate change impacts on water quality in Scottish standing waters are mediated through catchment management practices, in-lake processes, and other interacting factors (e.g. prevailing weather; hydrological extremes) in current and projected climate change scenarios.


Objective 2. Apply expert opinion, best available data, and combined outputs from Objective 1. to answer these 6 key strategic water research questions through this project:

2.1 Drivers and Impacts:

  • Is there evidence of a causal link between climate change impacts and water quality issues in Scottish standing waters at national, regional, and local scales?
  • What are the main types of climate-driven water quality impacts identified in Scottish standing waters, under current and projected climate change scenarios?

2.2 Risk:

  • Which areas, locations, and types of Scottish standing waters are currently most to least at risk in terms of water quality issues from climate change impacts at national, regional, and local scales?
  • Which areas, locations, and types of Scottish standing waters will likely experience exacerbated water quality risks under projected climate change scenarios?

2.3 Factors:

  • What factors contribute to the risk of water quality issues from climate change impacts in Scottish standing waters at national, regional, and local scales?
  • What factors need to be considered for mitigating climate-driven risks to water quality in Scottish standing waters, under current and projected climate change scenarios?
Contact Pauline Lang
27th August 2021

Dynamic Coast - Coastal Erosion in Scotland

CREW - Dynamic Coast


Coastal erosion is widely acknowledged to be a cross cutting issue affecting disparate interests (infrastructure, cultural and natural heritage, port facilities etc.) and
a coordinated approach to align effort across sectors is essential.

The Dynamic Coast was commissioned by CREW to provide the strategic evidence base on the extent of coastal erosion in Scotland. This will support the Scottish Government and the Scottish Public Sector decision-making and indicate areas of highest coastal erosion risk, where a more detailed evidence base may be required. The initial research published in 2017 by CREW, provided businesses and communities with readily interpretable evidence and modelling, based rates. This 2021 publication updates and supersedes the 2017 work, by including increased extents of eroding shoreline and the latest climate change projections on sea level rise, with an aim to help society become ‘sea level wise’ by planning now for our changing climate.   

There is international recognition that, for many countries, some of the first and most obvious effects of climate change will be through increased erosion and flood impacts on the coastline. Governments and organisations around the world are undertaking risk assessments to inform and shape new flexible adaptive approaches to better manage these growing risks. Many European partners and fellow UK administrations are searching for more sustainable approaches to address anticipated changes to our coastal assets. As relative sea level continues to rise, and storm impacts increase, many are questioning the assumption that existing artificial coastal defences should be raised and extended. The United Nations Intergovernmental Panel on Climate Change (IPCC) anticipates that the default management approach on the coast will become ‘avoidance and adaptation’ rather than the current ‘hold-the line’ via artificial defences. But where, when and how might  adaptation be implemented?

Given the lifespan of Scoland’s coastal infrastructure and other assets, together with the IPCC projections of anticipate climate change, the most appropriate route forward is by framing proposals within the precautionary principle, supported by a robust evidence-base of past changes and modelling of anticipated future changes, checked against appropriate coastal monitoring.  

For more information, please visit and read the research summary and synopsis below.

30th July 2021

Slender Naiad (Najas Flexilis) Habitat - Site Prioritisation

The Slender Naiad (Najas flexilis) is a rare submerged, rooted aquatic plant, typically found in clear-water, lowland lakes. Within the UK sites it is now currently found only in Scotland, with its strongholds historically in Argyll, the Hebrides and Perthshire. Its mainland sites are under increasing threat, primarily from nutrient pollution and competition from invasive non-native species. To help stem the decline of the Slender Naiad and hopefully restore its populations, a research programme was set up and funded by CREW, and carried out by the UK Centre for Ecology & Hydrology in collaboration with the University of Stirling. In the first phase of this project, Gunn and Carvalho (2020), with the support of a number of aquatic plant experts, reviewed the available information on the habitat requirements of the Slender Naiad (

In the second phase of this project, the phase one findings were used to identify lochs in Scotland with suitable habitat for Slender Naiad. It could either be present at these sites yet unrecorded, or they would be lochs to be prioritised for its re-introduction. Suitable sites were first identified using water quality (alkalinity and nutrient) data. Applying a combination of thresholds for alkalinity and nutrient concentrations produced an initial list of 4092 potentially suitable lochs across Scotland. To refine this list, a novel method was developed to use existing data on other aquatic plants to identify habitat suitability. This process was carried out by evaluating a set of 80 “associated” aquatic plant species that have previously been recorded at known Slender Naiad sites. For each of these 80 species an “Indicator Value” score was calculated based on their occupancy and fidelity at sites with, and without, the Slender Naiad. Application of this methodology generated a shorter list of 867 potentially suitable lochs. Further prioritisation of sites on the mainland and sites within 60 km of an existing Slender Naiad sites produced a final short-list of 156 lochs as priority sites for further conservation action.

Of the top 20 ranked sites from the short-list of 156 lochs, the majority occur in Argyll, Dumfries, Galloway, and Stirlingshire, all close to known existing Slender Naiad sites. Additional criteria that could also be used to rank the priority list of sites for further investigations, such as connectivity to other lochs or absence of invasive non-native species in the area, were also highlighted.

It is quite possible that the Slender Naiad may already be present at some of these selected priority sites but may have been missed previously if the site was not surveyed sufficiently, or was previously surveyed too early in the summer season. It is recommended that field surveys be undertaken to first check whether the listed priority lochs hold undiscovered Slender Naiad populations and check the environmental quality (water quality and absence of invasive species). Because of the difficulties in surveying rare submerged aquatic plants, we also recommend sampling loch sediments to check if the seeds of Slender Naiad are present. If it is confirmed through site survey that the slender Naiad is not present, and that these lochs still meet the species’ environmental requirements, then these would be strong candidates for either the re-introduction of the Slender Naiad.

The impact of shadow flicker or pulsating shadow effect, caused by wind turbine blades, on Atlantic salmon (Salmo salar)

A review of the available literature relating to the impact of shadow flicker on freshwater fish, with a particular focus on Atlantic salmon in rivers. This may, depending on the evidence delivered, inform policy in relation to the placement of wind turbines in areas adjacent to rivers in the Scottish context.

Onshore windfarms have become a common sight within the Scottish countryside and may impact freshwater environments and the fish that they support in a number of ways. These include changes to water quality caused during construction and drainage, or damage to vulnerable freshwater habitats (such as gravels used by fish for spawning) during stream and river crossings. The issue of shadow flicker or pulsating shadow effects is a potential impact which has not been investigated with regard to the placement of onshore wind turbines but has been raised in respect to its potential impact in offshore installations. New turbines and the installation of larger turbines during the repowering of established sites, may have the potential to impact Atlantic salmon (Salmo salar). A species which is already undergoing significant declines throughout its natural range, and a feature within Special Areas of Conservation (SACs), may be adversely impacted by shadow flicker. This literature review will inform regulators and others as to whether this is an issue, whether it is not, or whether more targeted research is needed. It cuts across a range of policy areas, including renewable energy, climate change and conservation of features within designated sites and wider fisheries management.


Project Objectives

• Review the current literature on ‘shadow flicker’ on freshwater fish with a particular focus on Atlantic salmon; 

• Use examples from the literature to provide insights into the actual biological impact that these may have on Atlantic salmon in rivers; and 

• Suggest ways in which this issue, should it be shown to be significant, can be mitigated or used to inform wind turbine placement near rivers.


Research Questions to be answered through this project:

1.  What are the potential biological and ecological impacts/responses of shadow flicker on Atlantic salmon at an individual level at each life stage within a river system?

2.  Do Atlantic salmon habituate to repeated disturbance and may that increase susceptibility to other pressures, such as predation risk?

3. Can the impact of flicker be extrapolated to the whole Atlantic salmon population of an affected river?

4. Are there ways in which this issue can be successfully mitigated?





Contact Pauline Lang


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