Management Measures Tool for Marine Energy

Accessing Management Measures that Support Deployment of Wave and Tidal Energy Devices

As the marine renewable energy (MRE) industry moves beyond deployment of individual wave and tidal energy devices towards arrays, certain risks of MRE devices on the marine environment are not well understood and have led to onerous monitoring requirements placed on device developers. In consultation with the research and regulatory communities, it was agreed that applying a set of robust management measures could act as safeguards for marine animals and habitats until available monitoring data allows for determining the level of risk from MRE devices. At that point, measures could be dialed back or removed, if warranted.

A workshop was held in May 2017 with researchers, regulators, and developers to create the basis for the tool shown here. More information on the workshop and input for the tool can be found here.

In addition to the searchable tool below, the information below can be downloaded here. The download file includes additional details not shown below, including comments from stakeholders on past experience, cost of management measures, and when a management measure is needed.

View the instructions document for more in-depth details and examples on how to use the Management Measure Tool for Marine Energy.

^{Last updated September 2022}

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Technology	Project Phase	Stressor	Receptor	Management Measure	Implications of Measure	Advantages	Challenges	Project Documents
Tidal	Operation & Maintenance	Changes in water flow The potential wider or secondary effects on protected or sensitive sub-littoral seabed due to removal or alteration of energy flow arising from devices and moorings or support structures.	Benthic All receptors	Design feature Site selection.		Minimises significance of interaction	N/A	ScottishPower Renewables 2012
Wave, Tidal	Operation & Maintenance	EMF Impacts of electromagnetic fields from subsea cables on sensitive species.	Benthic Benthic invertebrates	Design feature Bundle cables together to reduce field vectors.	Reduces the level of EMF to surrounding water column and therefore any potential effects, however there is potential for less redundancy in the system together with potential commercial and technical feasibility issues.	Reduce the level of EMF to surrounding water column and therefore any potential effects	Less redundancy in system. Potential commercial and technical feasibility issues.	MeyGen 2012
Wave, Tidal	Installation, Decommissioning	Habitat Loss Direct loss of protected or sensitive sub-littoral seabed communities due to the presence of devices and associated moorings or support structures on the seabed.	Benthic Benthic invertebrates, demersal fish	Mitigation Use of locally sourced materials, for cable protection, of the same type as the habitat to be disturbed by cable installation.	Minimize impact on biodiversity/ ecosystem.	Lost seabed is replaced with same material. Minimises habitat loss.	N/A	Tidal Lagoon Power 2017
Tidal	Operation & Maintenance	Changes in water flow The potential wider or secondary effects on protected or sensitive sub-littoral seabed due to removal or alteration of energy flow arising from devices and moorings or support structures.	Birds All receptors	Monitoring Installation of ADCPs and turbulence sensors to better understand the baseline tidal flow conditions and hence the change in tidal flow due to presence of the device(s)		Reduce scientific uncertainty	N/A	Tidal Energy Ltd 2008, Aquatera 2017
Wave, Tidal	Installation	Collision risk Potential barrier to movement due to the physical presence of devices and associated moorings / support structures, cables and electrical equipment.	Birds Birds	Monitoring Array instalation carried out in phases	Allows close monitoring to observe any unexpected effects			GlaxoSmithKlineMontrose 2012
Wave, Tidal	Operation & Maintenance	Entrapment Potential risk of entrapment within device chambers and mooring arrays.	Birds All receptors	Mitigation Regular ROV/ drop down camera surveys to establish occurrence of entrapment		Early detection of entrapment	Additional cost.
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Vessel disturbance Potential for disturbance from project vessels.	Birds Shore-nesting birds	Mitigation Avoidance of sensitive shore nesting areas during sensitive periods with appropriate clearance distance.	Reduces potential effects and is a relatively low cost measure.	Reduces potential effects. Relatively low-cost measure.	N/A	OpenHydro and SSE Group 2013, Orbital Marine Power 2014, Foubister 2005, Xodus Group 2019, Magallanes Renovables 2020, Royal Haskoning and Sea Generation (Kyle Rhea) Ltd. 2013, ScottishPower Renewables 2012, Orbital Marine Power 2014, Aquatera 2017, The Marine Institute 2016, THETIS Energy 2009, Orbital Marine Power 2018
Tidal	Operation & Maintenance	Changes in water flow The potential wider or secondary effects on protected or sensitive sub-littoral seabed due to removal or alteration of energy flow arising from devices and moorings or support structures.	Fish All receptors	Design feature Site selection.		Minimises significance of interaction	N/A	ScottishPower Renewables 2012
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Displacement Potential displacement of essential activities due to the presence of devices and associated moorings / support structures.	Fish All receptors	Design feature Array/ mooring configuration designed to avoid migratory routes or other important sites		Minimises risk of development creating displacement by avoiding migratory routes or other important sites	May be inconsistent with optimal layout of the development for exploitation of the energy source Can be a costly measure when scaling up to larger arrays	Aquamarine Power Ltd 2011, Davison and Mallows 2005
Wave, Tidal	Operation & Maintenance	EMF Impacts of electromagnetic fields from subsea cables on sensitive species.	Fish Elasmobranchs	Design feature Bundle cables together to reduce field vectors.	Reduce the level of EMF to surrounding water column and therefore any potential effects. Could result in there being less redundancy in the system and potential commercial and technical feasibility issues.	Reduce the level of EMF to surrounding water column and therefore any potential effects	Less redundancy in system. Potential commercial and technical feasibility issues. Greater costs associated with not laying direct cable paths	MeyGen 2012
Wave, Tidal	Installation, Decommissioning	Habitat Loss Direct loss of protected or sensitive sub-littoral seabed communities due to the presence of devices and associated moorings or support structures on the seabed.	Fish Demersal fish	Design feature Micrositing of offshore infrastructure to avoid sensitive habitats and minimise footprint.	This could reduce/remove effects on sensitive habitats and is a relatively low cost measure.	This could reduce/remove effects on sensitive habitats. Low cost measure at single device or small-scale array.	N/A	Foubister 2005, Royal Haskoning and Sea Generation (Kyle Rhea) Ltd. 2013, ScottishPower Renewables 2012, Laminaria 2018, The Marine Institute 2016
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Vessel disturbance Potential for disturbance from project vessels.	Fish Basking shark, large fish	Mitigation Reduce speed and maintain steady course when animal is sighted.	Reduces potential effects and is a relatively low cost measure.	Reduces potential effects. Relatively low-cost measure.	N/A	Aquatera Ltd 2011, Magallanes Renovables 2020, European Marine Energy Centre (EMEC) 2020, SSE Group 2011, Magallanes Renovables 2020, Royal Haskoning 2012, Aquatera 2017, Federal Energy Regulatory Commission (FERC) 2020
Wave, Tidal	Operation & Maintenance	Changes in sediment dynamics The potential wider or secondary effects (siltation changes or smothering) on protected or sensitive littoral habitat due to devices and associated moorings, support structures or landfall cables.	Habitat Benthic species	Design feature Micrositing of landfall cables and infrastructure to minimise the impact on sensitive habitats and species. Best practice techniques for cable installation, burial and protection.	n/a	N/A	N/A	Orbital Marine Power 2014, Craig 2008, OpenHydro and SSE Group 2013, DP Energy Ltd. 2013, South West of England Regional Development Agency (SWDRA) 2006, SSE Group 2011, ScottishPower Renewables 2012, DP Energy Ltd. 2017, Laminaria 2018, Sustainable Energy Authority of Ireland (SEAI) 2011, Tidal Lagoon Power 2017
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Marine Non-Native Species (MNNS) Potential for introduction of MNNS which can have an adverse impact on the native species at the site.	Habitat All receptors	Mitigation Establish and implement a Biofouling Management Plan.	Reduce/remove risk of transfer and settlement of non-native species.	Reduce/remove risk of transfer of non-native species.	Lack of industry specific guidance.	European Marine Energy Centre (EMEC) 2014, Xodus Group 2019, Orbital Marine Power 2018
Tidal	Operation & Maintenance	Collision risk Potential for collision with turbine blades.	Marine Mammals Marine Mammals	Mitigation, Design feature Install a 'detect and deter' system using a combination of active sonar and acoustic deterrent device (ADD).	This could reduce likelihood of collision with moving blades although the efficacy of ADDs in these environments is unknown and habituation to ADDs is known to occur in other industries....Read more This could reduce likelihood of collision with moving blades although the efficacy of ADDs in these environments is unknown and habituation to ADDs is known to occur in other industries. Could enable a route through the consenting process. This measure is expensive to implement and it is still unknown if deterrent systems will help reduce risk. There are also questions around the effects of ADDs on sensitive species. Their addition adds another noise impact which must also be considered in any project assessments. Would rely on well proven and reliable 'detect and deter' systems. Also, mitigation against collision may prevent discovering whether or not it is a real issue. Further research around ADDs which deter specific groups or species, is underway. This could be useful in deterring specific sensitive species or species groups, at a particular site. For example, University of St Andrews is seveloping an ADD which deter seals, but which don't effect cetaceans. Read less	This could reduce likelihood of collision with moving blades although the efficacy of ADDs in these environments is unknown	This is expensive to implement and it is unknown if deterrent systems will help reduce risk. Effects of ADDs on sensitive species. Detection systems are currently insufficient to detect animals (in particular at array scale).	Harrison et al. 2015, Orbital Marine Power 2010, Keenan et al. 2011, Aquamarine Power Ltd 2011, THETIS Energy 2009
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Contamination Potential for oil spill incident resulting from the influence of unfavourable weather conditions.	Marine Mammals All receptors	Mitigation Vessel activities to occur in suitable weather conditions	Reduces the chance for oil spill to the environment			MeyGen 2012, The Marine Institute 2016, ScottishPower Renewables 2012
Tidal	Operation & Maintenance	Changes in water flow The potential wider or secondary effects on protected or sensitive sub-littoral seabed due to removal or alteration of energy flow arising from devices and moorings or support structures.	Reptiles All receptors	Monitoring Modelling to predict the interaction between changes in tidal flow, flux and turbulence structure and animals.		Reduces scientific uncertainty so appropriate management measures can be employed	Limited management measures available to minimise interaction despite modelling to fully predict interaction
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Marine Non-Native Species (MNNS) Potential for introduction of MNNS which can have an adverse impact on the native species at the site.	Marine Mammals All receptors	Compliance Compliance with all relevant guidance (including IMO guidelines) regarding ballast water management and transfer of non-native species.	Reduces/removes risk of transfer and settlement of non-native species.	Reduce/remove risk of transfer and settlement of non-native species.	N/A	McPherson 2015, MeyGen 2012, Davison and Mallows 2005, Royal Haskoning and Sea Generation (Kyle Rhea) Ltd. 2013, Magallanes Renovables 2020, Federal Energy Regulatory Commission (FERC) 2020
Tidal	Operation & Maintenance	Changes in water flow The potential wider or secondary effects on protected or sensitive sub-littoral seabed due to removal or alteration of energy flow arising from devices and moorings or support structures.	Habitat All receptors	Design feature Site selection.		Minimises significance of interaction	N/A	ScottishPower Renewables 2012
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Contamination Potential for accidental or unplanned events which could lead to contamination of the marine environment.	Reptiles All receptors	Mitigation Material selection - lubricants, coolants, hydraulic fluids etc. selected with low ecotoxicity levels and biodegradable.	Reduces/removes risk of contamination from materials which may have escaped structure. Although, use of lower toxicity materials may compromise performance, or impact other technical issues (e.g. fluid changes).	Reduces/removes risk of pollution from materials which may have escaped structure.	Use of lower toxicity materials may compromise performance, or impact other technical issues (e.g. fluid changes.)	Foubister 2005, MeyGen 2012, Xodus AURORA 2010, The Marine Institute 2016, THETIS Energy 2009
Wave, Tidal	Operation & Maintenance	Habitat creation The introduction of infrastructure and artificial substrates will provide habitat and artificial refuges.	Reptiles All receptors	Monitoring Monitor near-field behaviours.	Informs understanding of potential positive impacts from colonisation and use of the project infrastructure which could benefit future project applications. However, there is a cost implication associated with monitoring.	Reduces scientific uncertainty around collision risk, displacement and other impacts. Increased value/ fecundity of commercially important species.	This type of monitoring can be expensive and difficult to deliver in practice. May require additional licensing (e.g. echosounders).
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Contamination Potential for accidental or unplanned events which could lead to contamination of the marine environment.	Benthic All receptors	Design feature Physical Containment systems including bulk heads, closed circuit systems, pressure relief systems.	Reduces risk of contamination escaping from structure.	Reduces risk of pollution escaping from structure.	N/A	Foubister 2005, MeyGen 2012, Royal Haskoning and Sea Generation (Kyle Rhea) Ltd. 2013, Magallanes Renovables 2020, Sustainable Energy Authority of Ireland (SEAI) 2011, Tidal Lagoon Power 2017, The Marine Institute 2016, Aquamarine Power Ltd 2011
Wave, Tidal	Operation & Maintenance	EMF Impacts of electromagnetic fields from landfall cables on sensitive species.	Benthic Benthic invertebrates	Design feature Use of 3-phase cables instead of DC cables.	n/a
Wave, Tidal	Installation, Decommissioning	Habitat Loss Seabed habitat disturbance/loss or changes to seabed habitat	Benthic Benthic invertebrates, demersal fish	Mitigation Adherence to vessel anchor and device anchor/mooring plans.	Minimize impact on biodiversity/ ecosystem.			Xodus Group 2019, Federal Energy Regulatory Commission (FERC) 2020
Tidal	Operation & Maintenance	Changes in water flow The potential wider or secondary effects on protected or sensitive sub-littoral seabed due to removal or alteration of energy flow arising from devices and moorings or support structures.	Birds All receptors	Design feature Design structures to minimise effect on turbulence structure.		Minimises change in turbulence structure and hence potential interaction	Can present financial/ logistical/ design challenges to technology developer to alter design of device/ moorings	Aquamarine Power Ltd 2011, Davison and Mallows 2005, Tidal Energy Ltd 2008
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Contamination Potential for accidental or unplanned events which could lead to contamination of the marine environment.	Birds All receptors	Design feature Physical Containment systems including bulk heads, closed circuit systems, pressure relief systems.	Reduces risk of contamination escaping from structure.	Reduces risk of pollution escaping from structure.	N/A	Foubister 2005, MeyGen 2012, Royal Haskoning and Sea Generation (Kyle Rhea) Ltd. 2013, Magallanes Renovables 2020, Sustainable Energy Authority of Ireland (SEAI) 2011, The Marine Institute 2016, THETIS Energy 2009
Wave, Tidal	Operation & Maintenance	Entanglement Potential for marine animals to become entangled in lost fishing gear or other equipment trapped on infrastructure.	Birds Diving birds	Mitigation Fisheries management: Agreement with fishermen not to fish near to the device, warning of the dangers of losing equipment.	Reduces potential for entanglement of fishing gear in mooring lines and thus potential for entanglement of marine animals.			Xodus Group 2019
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Vessel disturbance Potential for disturbance from project vessels.	Birds Birds on water	Mitigation Vessel speed limitation to and from site.		Reduces potential effects. Relatively low-cost measure.	N/A	SIMEC Atlantis Energy Ltd 2011, OpenHydro and SSE Group 2013
Tidal	Operation & Maintenance	Changes in water flow Modifications to prey distribution and abundance (to include for other receptors) resulting in changes to foraging behaviour.	Fish All receptors	Design feature Site selection.		Minimises significance of interaction	N/A	ScottishPower Renewables 2012
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Contamination Potential for accidental or unplanned events which could lead to contamination of the marine environment.	Fish All receptors	Mitigation Where rock placement is used, ensure clean rock is used.	Reduces/removes risk of contamination from materials.	Reduces/removes risk of pollution from materials	N/A
Wave, Tidal	Operation & Maintenance	EMF Impacts of electromagnetic fields from subsea cables on sensitive species.	Fish Migratory fish	Design feature Bury or HDD cables where possible and viable.	Reduces the level of EMF to surrounding water column and therefore any potential effects. Reduces 'snagging risk' for vessels. Potential for adverse impacts on surrounding benthic habitats and sensitive species, e.g. from smothering. This measure forms part of normal project design.	Reduce the level of EMF to surrounding water column and therefore any potential effects. Reduces 'snagging risk' for vessels.	The implication of this measure may have an impact on surrounding benthic habitats and sensitive species. Can be very challenging or impossible at sites where seabed tends to be rocky. Additional expense to the project. Permanent damage to seabed. Reduced possibility of ever decommissioning.	Sustainable Energy Authority of Ireland (SEAI) 2011, Tidal Lagoon Power 2017, Federal Energy Regulatory Commission (FERC) 2020
Wave, Tidal	Installation, Decommissioning	Habitat Loss Direct loss of protected or sensitive sub-littoral seabed communities due to the presence of devices and associated moorings or support structures on the seabed.	Fish Demersal fish	Design feature Site selection to avoid sensitive or protected sub-littoral seabed communities.		This could reduce/remove effects on sensitive habitats.	N/A	ScottishPower Renewables 2012
Wave, Tidal	Operation & Maintenance	Vessel disturbance Potential for disturbance from project vessels.	Fish Basking shark, large fish	Mitigation Use smaller vessels for maintenance purposes.	Reduces potential effects and is a relatively low cost measure.			Aquatera Ltd 2011, Laminaria 2018
Tidal	Operation & Maintenance	Changes in water flow The potential wider or secondary effects (siltation changes or smothering) on protected or sensitive littoral habitat due to changes in tidal flow around devices and associated moorings, support structures or landfall cables.	Habitat Benthic invertebrates	Monitoring Pre and post installation monitoring of sensitive benthic communities, based on visual surveys.	n/a	Reduce scientific uncertainty	Interpretation of data for statistical purposes may not have power to detect change generated by impact. May require correlation with detailed Computational Fluid Dynamics studies and physical flow measurements.	Orbital Marine Power 2014, European Marine Energy Centre (EMEC) 2011, Davison and Mallows 2005, ScottishPower Renewables 2010, The Marine Institute 2016, Orbital Marine Power 2018
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Marine Non-Native Species (MNNS) Potential for introduction of MNNS which can have an adverse impact on the native species at the site.	Habitat All receptors	Mitigation, Compliance Adhere to appropriate measures when jettisoning ballast water.	Reduce/remove risk of transfer and settlement of non-native species.	Reduce/remove risk of transfer of non-native species.	N/A	Sustainable Energy Authority of Ireland (SEAI) 2011
Wave, Tidal	Operation & Maintenance	Lighting Potential for lighting to adversely affect nocturnal and migratory species.	Marine Mammals All receptors	Design feature Consider type, colour and use of lighting during design and consultation with navigational stakeholders.	A targeted lighting plan may have the potential to reduce impacts on sensitive species but navigational safety takes precedence.	If sensitive species are known to use or migrate near to the project site.	A targeted lighting plan may have the potential to reduce impacts on sensitive species but navigational interests need to be considered at all times	DP Energy Ltd. 2013, European Marine Energy Centre (EMEC) 2014, Tidal Lagoon Power 2017
Wave, Tidal	Operation & Maintenance	Contamination Potential for oil/hydraulic spill incident resulting from the maintenance activities	Marine Mammals All receptors	Mitigation All maintenance activities involving oil/hydraulic fluid treatments will be carried out on-shore	Reduces the chance for oil spill to the environment			Foubister 2005
Tidal	Operation & Maintenance	Changes in water flow The potential wider or secondary effects on protected or sensitive sub-littoral seabed due to removal or alteration of energy flow arising from devices and moorings or support structures.	Reptiles All receptors	Design feature Site selection.		Minimises significance of interaction	N/A	ScottishPower Renewables 2012
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Marine Non-Native Species (MNNS) Potential for introduction of MNNS which can have an adverse impact on the native species at the site.	Marine Mammals All receptors	Monitoring Monitoring and reporting of MNNS.	Reduces/removes risk of transfer of non-native species.
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Vessel disturbance Potential for disturbance from project vessels.	Marine Mammals Marine Mammals	Mitigation Care will be taken to avoid splitting up groups and mothers and young.	Reduces potential effects and is a relatively low cost measure.	Reduces potential effects. Relatively low-cost measure.	N/A	European Marine Energy Centre (EMEC) 2020, Magallanes Renovables 2020, Aquatera 2017, Orbital Marine Power 2018
Wave, Tidal	Operation & Maintenance	Habitat creation The introduction of infrastructure and artificial substrates will provide potential roosting habitat.	Habitat Roosting birds	Monitoring Monitor use of device as a roosting platform.	Reduces scientific uncertainty around collision risk, displacement and other impacts, however this type of monitoring can be expensive.	Reduces scientific uncertainty around collision risk, displacement and other impacts. Monitoring is relatively inexpensive to carry out.	Data mortgage (concept of generating data more quickly than it can be analysed)
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Marine Non-Native Species (MNNS) Potential for introduction of MNNS which can have an adverse impact on the native species at the site.	Reptiles All receptors	Compliance Compliance with all relevant guidance (including IMO guidelines) regarding ballast water management and transfer of non-native species.	Reduces/removes risk of transfer and settlement of non-native species.	Reduce/remove risk of transfer and settlement of non-native species.	N/A	MeyGen 2012, Federal Energy Regulatory Commission (FERC) 2020
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Contamination Potential for accidental or unplanned events which could lead to contamination of the marine environment.	Benthic All receptors	Mitigation Material selection - lubricants, coolants, hydraulic fluids etc. selected with low ecotoxicity levels and biodegradable.	Reduces/removes risk of contamination from materials which may have escaped structure. However, use of lower toxicity may compromise performance, or impact other technical issues (e.g. fluid changes).	Reduces/removes risk of pollution from materials which may have escaped structure.	Use of lower toxicity materials may compromise performance, or impact other technical issues (e.g. fluid changes.)	Foubister 2005, MeyGen 2012, Xodus AURORA 2010, Foubister 2005, Davison and Mallows 2005, The Marine Institute 2016, THETIS Energy 2009
Wave, Tidal	Operation & Maintenance	EMF Impacts of electromagnetic fields from subsea cables on sensitive species.	Benthic Benthic invertebrates	Design feature Bury or HDD cables where possible and viable.	Reduces the level of EMF to surrounding water column and therefore any potential effects, however the implementation of this measure may have an impact on surrounding benthic habitats and sensitive species....Read more Reduces the level of EMF to surrounding water column and therefore any potential effects, however the implementation of this measure may have an impact on surrounding benthic habitats and sensitive species. Also reduces 'snagging risk' for vessels. This measure forms part of normal project design. Read less	Reduce the level of EMF to surrounding water column and therefore any potential effects. Reduces 'snagging risk' for vessels.	The implication of this measure may have an impact on surrounding benthic habitats and sensitive species. Uncertainty around the effect of EMF on benthic species. Hence uncertainty around the need for and efficacy of this measure. Can be very challenging or impossible at sites where seabed tends to be rocky. Additional expense to the project. Permanent damage to seabed. Reduced possibility of ever decommissioning.	Sustainable Energy Authority of Ireland (SEAI) 2011, Federal Energy Regulatory Commission (FERC) 2020
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Marine Non-Native Species (MNNS) Potential for introduction of MNNS which can have an adverse impact on the native species at the site.	Benthic All receptors	Mitigation Establish and implement a Biofouling Management Plan.	Reduce/remove risk of transfer of non-native species.	Reduce/remove risk of transfer of non-native species.	Lack of industry specific guidance.	European Marine Energy Centre (EMEC) 2014, Xodus Group 2019, RSK Group 2012
Tidal	Operation & Maintenance	Changes in water flow The potential wider or secondary effects on protected or sensitive sub-littoral seabed due to removal or alteration of energy flow arising from devices and moorings or support structures.	Birds All receptors	Monitoring Modelling to predict the interaction between changes in tidal flow, flux and turbulence structure and animals.		Reduces scientific uncertainty so appropriate management measures can be employed	Limited management measures available to minimise interaction despite modelling to fully predict interaction
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Contamination Potential for accidental or unplanned events which could lead to contamination of the marine environment.	Birds All receptors	Mitigation Material selection - lubricants, coolants, hydraulic fluids etc. selected with low ecotoxicity levels and biodegradable.	Reduces/removes risk of contamination from materials which may have escaped structure. However, use of lower toxicity may compromise performance, or impact other technical issues (e.g. fluid changes).	Reduces/removes risk of pollution from materials which may have escaped structure.	Use of lower toxicity materials may compromise performance, or impact other technical issues (e.g. fluid changes.)	MeyGen 2012, Foubister 2005, Xodus AURORA 2010, Davison and Mallows 2005, The Marine Institute 2016, THETIS Energy 2009
Wave, Tidal	Operation & Maintenance	Habitat creation The introduction of infrastructure and artificial substrates will provide habitat and artificial refuges.	Birds All receptors	Monitoring Monitor near-field behaviours.	Informs understanding of potential positive impacts from colonisation and use of the project infrastructure which could benefit future project applications, however there is a cost implication associated with monitoring.	Reduces scientific uncertainty around collision risk, displacement and other impacts. Increased value/ fecundity of commercially important species.	This type of monitoring can be expensive and difficult to deliver in practice. May require additional licensing (e.g. echosounders).	MeyGen 2012, Tidal Lagoon Power 2017
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Vessel disturbance Potential for disturbance from project vessels.	Birds Birds on water	Mitigation Vessel transit route: defining routes to avoid sensitive sites and to only disturb one route.	Reduces potential effects and is a relatively low cost measure.	Reduces potential effects. Relatively low-cost measure. This is measurable and definable.	N/A	OpenHydro and SSE Group 2013, DP Energy Ltd. 2013, European Marine Energy Centre (EMEC) 2020, Royal Haskoning and Sea Generation (Kyle Rhea) Ltd. 2013, SSE Group 2011, SIMEC Atlantis Energy Ltd 2011, Aquatera 2017, Davison and Mallows 2005, Orbital Marine Power 2018
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Changes in sediment dynamics Reduced visibility impacting prey detection and obstruction avoidance.	Fish All receptors	Mitigation Best practice methodologies to reduce resuspension of sediment during cable burial or device foundation / mooring installation.	n/a	N/A	N/A	Foubister 2005, Sustainable Energy Authority of Ireland (SEAI) 2011, Tidal Lagoon Power 2017, The Marine Institute 2016, Federal Energy Regulatory Commission (FERC) 2020, THETIS Energy 2009
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Contamination Potential for accidental or unplanned events which could lead to contamination of the marine environment.	Fish All receptors	Compliance Management: Establish and implement a Contamination Control Plan / Ship Oil Contamination Emergency Plans (SOPEPs). Compliance with International Maritime Organization (IMO) and Maritime Coastguard Agency (MCA) codes for the prevention of contamination.	Reduces risk of any contamination event and ensures that contingency plans are in place. Demonstrates compliance with environmental management systems.	Reduces risk of any pollution event and ensures that contingency plans are in place. Demonstrates compliance with environmental management systems.	N/A	Foubister 2005, GlaxoSmithKlineMontrose 2012, MeyGen 2012, DP Energy Ltd. 2013, Foubister 2005, Davison and Mallows 2005, Royal Haskoning and Sea Generation (Kyle Rhea) Ltd. 2013, The Marine Institute 2016, Federal Energy Regulatory Commission (FERC) 2020
Wave, Tidal	Installation	EMF Impacts of electromagnetic fields from subsea cables on sensitive species.	Fish Migratory fish	Design feature Micrositing of offshore infrastructure to avoid sensitive habitats and minimise footprint.	This could reduce/remove effects on sensitive habitats and is a relatively low cost measure.			DP Energy Ltd. 2013, ScottishPower Renewables 2012, Laminaria 2018, Tidal Lagoon Power 2017, The Marine Institute 2016
Wave, Tidal	Installation, Decommissioning	Habitat Loss Direct loss of protected or sensitive sub-littoral seabed communities due to the presence of devices and associated moorings or support structures on the seabed.	Fish Demersal fish	Design feature Minimise footprint of anchors / foundations.	This could reduce effects on sensitive habitats, however may impact technical considerations.	This could reduce effects on sensitive habitats	May impact technical considerations.	Aquatera Ltd 2011, Xodus Group 2019, Federal Energy Regulatory Commission (FERC) 2020
Wave, Tidal	Installation	Barrier to movement Potential barrier to movement due to the physical presence of devices and associated moorings / support structures, cables and electrical equipment.	Marine Mammals All receptors	Design feature Site selection to avoid sensitive routes/areas.		Minimises risk of development acting as a barrier to movement by avoiding migratory routes or other important sites	N/A	ScottishPower Renewables 2012
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Contamination Potential for accidental or unplanned events which could lead to contamination of the marine environment.	Habitat All receptors	Design feature Physical Containment systems including bulk heads, closed circuit systems, pressure relief systems.	Reduces risk of contamination escaping from structure.	Reduces risk of pollution escaping from structure.	N/A	Foubister 2005, MeyGen 2012, South West of England Regional Development Agency (SWDRA) 2006, Magallanes Renovables 2020, Sustainable Energy Authority of Ireland (SEAI) 2011, The Marine Institute 2016
Wave, Tidal	Operation & Maintenance	Displacement Potential displacement of essential activities due to the presence of devices and associated moorings / support structures.	Marine Mammals All receptors	Design feature Site selection (taking into account cumulative impact of other developments).		Minimises risk of development causing displacement by avoiding migratory routes or other important sites	N/A	ScottishPower Renewables 2012
Wave, Tidal	Operation & Maintenance	Lighting Potential for light from installation vessels to adversely affect nocturnal and migratory species.	Marine Mammals All receptors	Monitoring Monitoring effects on animals.		Reduce scientific uncertainty	Can be difficult to detect change as a result of interaction as opposed to natural variability
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Vessel disturbance Potential for disturbance from project vessels.	Marine Mammals Marine Mammals	Mitigation Vessel speed limitation to and from site.		Reduces potential effects. Relatively low-cost measure.	N/A	Aquamarine Power Ltd 2011, SIMEC Atlantis Energy Ltd 2011
Wave, Tidal	Operation & Maintenance	Displacement Potential displacement of essential activities due to the presence of devices and associated moorings / support structures.	Reptiles All receptors	Design feature Site selection (taking into account cumulative impact of other developments).		Minimises risk of development causing displacement by avoiding migratory routes or other important sites	N/A
Wave, Tidal	Installation, Decommissioning	Underwater noise The potential effects from underwater noise generated during installation/ construction (excluding piling).	Marine Mammals Marine Mammals	Mitigation Avoid/limit 'noisy works' within close proximity to sensitive sites i.e. known seal haul outs during sensitive periods, defining appropriate clearance distances where necessary.	This could reduce potential effects on sensitive species during sensitive periods, however may could increase project construction timescales e.g. if continuous drilling time is restricted or specific periods need to be avoided.	This could reduce potential effects on sensitive species during sensitive periods.	This could increase project construction timescales e.g. if continuous drilling time is restricted or specific periods need to be avoided	Orbital Marine Power 2014, Xodus AURORA 2010, Aquatera Ltd 2011, European Marine Energy Centre (EMEC) 2014, Davison and Mallows 2005, Xodus Group 2019, ScottishPower Renewables 2012, McGrath 2013, Aquatera 2017, The Marine Institute 2016, Federal Energy Regulatory Commission (FERC) 2020, DP Energy Ltd. 2017
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Vessel disturbance Potential for disturbance from project vessels.	Marine Mammals Basking shark, seals	Mitigation Employ an MMO during periods when noisy operations are likely to cause disturbance i.e., all operations using a DP vessel				SIMEC Atlantis Energy Ltd 2011, Orbital Marine Power 2010, Minesto 2016, Foubister 2005, European Marine Energy Centre (EMEC) 2014, Xodus Group 2019, Magallanes Renovables 2020, MeyGen 2012, DP Energy Ltd. 2013, Sustainable Energy Authority of Ireland (SEAI) 2011, The Marine Institute 2016, Federal Energy Regulatory Commission (FERC) 2020, THETIS Energy 2009, Davison and Mallows 2005
Wave, Tidal	Operation & Maintenance	Habitat creation The introduction of infrastructure and artificial substrates may generate additional habitat diversity.	Habitat Benthic species	Monitoring Structure colonization and biofouling surveys.	Informs understanding of potential for increased prey availability and ecological diversity which could benefit future project applications, however there is a cost implication associated with monitoring.	Informs understanding of potential for increased prey availability and ecological diversity.	Cost associated with monitoring.	Craig 2008
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Marine Non-Native Species (MNNS) Potential for introduction of MNNS which can have an adverse impact on the native species at the site.	Reptiles All receptors	Mitigation Establish and implement a Biofouling Management Plan.	Reduces/removes risk of transfer and settlement of non-native species.	Reduce/remove risk of transfer of non-native species.	Lack of industry specific guidance.	European Marine Energy Centre (EMEC) 2014, Royal Haskoning 2012
Wave, Tidal	Installation	Barrier to movement Potential barrier to movement due to the physical presence of devices and associated moorings / support structures, cables and electrical equipment.	Benthic All receptors	Design feature Site selection to avoid sensitive routes/areas.		Minimises risk of development acting as a barrier to movement by avoiding migratory routes or other important sites	N/A	Argyll Tidal Limited 2013, OpenHydro and SSE Group 2013
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Contamination Potential for accidental or unplanned events which could lead to contamination of the marine environment.	Benthic All receptors	Mitigation Where rock placement is used, ensure clean rock is used.	Reduces/removes risk of contamination from materials.	Reduces/removes risk of pollution from materials	N/A
Wave, Tidal	Operation & Maintenance	EMF Impacts of electromagnetic fields from landfall cables on sensitive species.	Benthic Benthic invertebrates	Design feature Lay cables in natural crevices.	n/a			MeyGen 2012
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Marine Non-Native Species (MNNS) Potential for introduction of MNNS which can have an adverse impact on the native species at the site.	Benthic All receptors	Compliance Adhere to appropriate measures when jettisoning ballast water.	Reduce/remove risk of transfer of non-native species.	Reduce/remove risk of transfer of non-native species.	N/A	Sustainable Energy Authority of Ireland (SEAI) 2011
Tidal	Operation & Maintenance	Changes in water flow The potential wider or secondary effects on protected or sensitive sub-littoral seabed due to removal or alteration of energy flow arising from devices and moorings or support structures.	Birds All receptors	Design feature Site selection.		Minimises significance of interaction	N/A	ScottishPower Renewables 2012
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Contamination Potential for accidental or unplanned events which could lead to contamination of the marine environment.	Birds All receptors	Mitigation Where rock placement is used, ensure clean rock is used.	Reduces/removes risk of contamination from materials.	Reduces/removes risk of pollution from materials	N/A
Wave, Tidal	Operation & Maintenance	Habitat creation The introduction of infrastructure and artificial substrates will provide potential roosting habitat.	Birds Roosting birds	Monitoring Monitor use of device as a roosting platform.	Reduces scientific uncertainty around collision risk, displacement and other impacts, however this type of monitoring can be expensive.	Reduces scientific uncertainty around collision risk, displacement and other impacts. Monitoring is relatively inexpensive to carry out.	Data mortgage (concept of generating data more quickly than it can be analysed)	DP Energy Ltd. 2013, Orbital Marine Power 2018
Wave, Tidal	Installation	Barrier to movement Potential barrier to movement due to the physical presence of devices and associated moorings / support structures, cables and electrical equipment.	Fish All receptors	Design feature Site selection to avoid sensitive routes/areas.		Minimises risk of development acting as a barrier to movement by avoiding migratory routes or other important sites	N/A	ScottishPower Renewables 2012
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Changes in sediment dynamics Sediment disturbance disrupting water clarity that results in smothering of fish spawning grounds.	Fish All receptors	Mitigation Best practice methodologies to reduce resuspension of sediment during cable burial or device foundation / mooring installation.	n/a	N/A	N/A	Sustainable Energy Authority of Ireland (SEAI) 2011, Tidal Lagoon Power 2017, The Marine Institute 2016, Federal Energy Regulatory Commission (FERC) 2020, THETIS Energy 2009
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Contamination Potential for oil spill incident resulting from the influence of unfavourable weather conditions.	Fish All receptors	Mitigation Vessel activities to occur in suitable weather conditions	Reduces the chance for oil spill to the environment			MeyGen 2012, The Marine Institute 2016, ScottishPower Renewables 2012
Wave, Tidal	Operation & Maintenance	EMF Impacts of electromagnetic fields from landfall cables on sensitive species.	Fish Demersal fish	Design feature Install cable protection/ armour.	Higher levels of insulation reduces the level of EMF to surrounding water column and therefore any potential effects.			DP Energy Ltd. 2013, Foubister 2005, Federal Energy Regulatory Commission (FERC) 2020
Wave, Tidal	Installation, Decommissioning	Habitat Loss Direct loss of protected or sensitive sub-littoral seabed communities due to the presence of devices and associated moorings or support structures on the seabed.	Fish Demersal fish	Design feature Cable protection management measures to ensure that any rock placement that is required will be kept to a minimum to reduce seabed disturbance.	This could reduce effects on sensitive habitats.	This could reduce effects on sensitive habitats	Additional cost.
Wave, Tidal	Installation	Barrier to movement Potential barrier to movement due to the physical presence of devices and associated moorings / support structures, cables and electrical equipment.	Marine Mammals All receptors	Design feature Array/ mooring configuration designed to avoid migratory routes or other important sites		Minimises risk of development acting as a barrier to movement by avoiding migratory routes or other important sites	May be inconsistent with optimal layout of the development for exploitation of the energy source. Can be a costly measure when scaling up to larger arrays.	Aquamarine Power Ltd 2011, Davison and Mallows 2005
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Contamination Potential for accidental or unplanned events which could lead to contamination of the marine environment.	Habitat All receptors	Mitigation Material selection - lubricants, coolants, hydraulic fluids etc. selected with low ecotoxicity levels and biodegradable.	Reduces/removes risk of contamination from materials which may have escaped structure. However, the use of lower toxicity materials may compromise performance, or impact other technical issue (e.g. fluuid changes).	Reduces/removes risk of pollution from materials which may have escaped structure.	Use of lower toxicity materials may compromise performance, or impact other technical issues (e.g. fluid changes.)	Foubister 2005, MeyGen 2012, Xodus AURORA 2010, The Marine Institute 2016, THETIS Energy 2009
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Displacement Potential displacement of essential activities due to the presence of devices and associated moorings / support structures.	Marine Mammals All receptors	Mitigation Timing of installation and decommissioning & marine operations to avoid times of particular sensitivity (e.g. breeding).		Minimises risk of development causing displacement by avoiding works during sensitive times	Can be disruptive and hence costly to developer	OpenHydro and SSE Group 2013, Aquatera Ltd 2011, Foubister 2005, Royal Haskoning and Sea Generation (Kyle Rhea) Ltd. 2013, SSE Group 2011, ScottishPower Renewables 2012, McGrath 2013, Orbital Marine Power 2014, The Marine Institute 2016, Federal Energy Regulatory Commission (FERC) 2020, THETIS Energy 2009, ScottishPower Renewables 2012
Tidal	Operation & Maintenance	Collision risk Potential for collision with turbine blades.	Marine Mammals Marine Mammals	Mitigation, Design feature Install acoustic deterrent devices (ADDs).	This could potentially reduce likelihood of collision with moving blades although the efficacy of ADDs in these environments is unknown. Constant deterring means habituation is likely. This is a simpler system than detect (efficiently) and deter, however would still be expensive to implement....Read more This could potentially reduce likelihood of collision with moving blades although the efficacy of ADDs in these environments is unknown. Constant deterring means habituation is likely. This is a simpler system than detect (efficiently) and deter, however would still be expensive to implement. It would also come with an additional noise impact which must also be considered in project assessments. Read less	This could reduce likelihood of collision with moving blades although the efficacy of ADDs in these environments is unknown	This is expensive to implement and it is unknown if deterrent systems will help reduce risk. Effects of ADDs on sensitive species. Detection systems are currently insufficient to detect animals (in particular at array scale).	Tidal Lagoon Power 2017, THETIS Energy 2009
Wave, Tidal	Installation	Contamination Accidental release of contaminants during installation including diesel fuel, oil hydraulic fluids, etc.	Habitat All receptors	Mitigation Best practice methodologies to reduce risk of accidental release of contaminants.	Reduces risk of contamination escaping from structure.			DP Energy Ltd. 2013
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Displacement Potential displacement of essential activities due to the presence of devices and associated moorings / support structures.	Reptiles All receptors	Mitigation Timing of installation and decommissioning & marine operations to avoid times of particular sensitivity (e.g. breeding).		Minimises risk of development causing displacement by avoiding works during sensitive times	Can be disruptive and hence costly to developer
Wave, Tidal	Operation & Maintenance	Underwater noise The potential effects from underwater noise generated by wave and tidal energy converters.	Marine Mammals Marine Mammals	Monitoring Measure noise generated by device(s) during operation to better understand the potential effects on sensitive species.	Measured noise levels can be correlated with threshold values of relevant species to determine impact and need for adaptive management measures, however this can be complex and costly to undertake this type of monitoring in high energy environments.	Measured noise levels can be correlated with threshold values of relevant species and baseline noise levels of the site to determine impact and need for adaptive management measures.	Can be complex and costly to undertake this type of monitoring in high energy environments. Data and analysis have requirement for acoustic experts.	SIMEC Atlantis Energy Ltd 2011, Aquamarine Power Ltd 2011, Orbital Marine Power 2014, Minesto 2016, Xodus AURORA 2010, European Marine Energy Centre (EMEC) 2019, ScottishPower Renewables 2010, Davison and Mallows 2005, McGrath 2013, Royal Haskoning 2012, Orbital Marine Power 2018
Wave, Tidal	Decommissioning	Vessel disturbance Potential for disturbance from project vessels.	Marine Mammals Cetaceans, seals	Mitigation Avoid sudden changes of speed	Reduces likelihood of any further disturbance to cetaceans in the vicinity			Orbital Marine Power 2018
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Contamination Potential for accidental or unplanned events which could lead to contamination of the marine environment.	Reptiles All receptors	Mitigation Where rock placement is used, ensure clean rock is used.	Reduces/removes risk of contamination from materials.	Reduces/removes risk of pollution from materials	N/A
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Marine Non-Native Species (MNNS) Potential for introduction of MNNS which can have an adverse impact on the native species at the site.	Reptiles All receptors	Mitigation, Compliance Adhere to appropriate measures when jettisoning ballast water.	Reduces/removes risk of transfer and settlement of non-native species.	Reduce/remove risk of transfer of non-native species.	N/A	Sustainable Energy Authority of Ireland (SEAI) 2011
Wave, Tidal	Installation	Barrier to movement Potential barrier to movement due to the physical presence of devices and associated moorings / support structures, cables and electrical equipment.	Benthic All receptors	Design feature Array/ mooring configuration designed to avoid migratory routes or other important sites		Minimises risk of development acting as a barrier to movement by avoiding migratory routes or other important sites	May be inconsistent with optimal layout of the development for exploitation of the energy source. Can be a costly measure when scaling up to larger arrays.	Aquamarine Power Ltd 2011, Davison and Mallows 2005
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Contamination Potential for accidental or unplanned events which could lead to contamination of the marine environment.	Benthic All receptors	Compliance Management: Establish and implement a Contamination Control Plan / Ship Oil Contamination Emergency Plans (SOPEPs). Compliance with International Maritime Organization (IMO) and Maritime Coastguard Agency (MCA) codes for the prevention of contamination.	Reduces risk of any contamination event and ensures that contingency plans are in place. Demonstrates compliance with environmental management systems.	Reduces risk of any pollution event and ensures that contingency plans are in place. Demonstrates compliance with environmental management systems.	N/A	Low 2012, Foubister 2005, GlaxoSmithKlineMontrose 2012, Royal Haskoning and Sea Generation (Kyle Rhea) Ltd. 2013, RSK Group 2012, Magallanes Renovables 2020, Sustainable Energy Authority of Ireland (SEAI) 2011, Tidal Lagoon Power 2017, The Marine Institute 2016, Federal Energy Regulatory Commission (FERC) 2020, Aquamarine Power Ltd 2011
Wave, Tidal	Installation	EMF Impacts of electromagnetic fields from landfall cables on sensitive species.	Benthic Benthic invertebrates	Design feature Micrositing of offshore infrastructure to avoid sensitive habitats and minimise footprint.	This could reduce/remove effects on sensitive habitats and can often be done with little additional cost.			ScottishPower Renewables 2012, Laminaria 2018, The Marine Institute 2016
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Marine Non-Native Species (MNNS) Potential for introduction of MNNS which can have an adverse impact on the native species at the site.	Benthic All receptors	Mitigation Source vessels locally.	Reduce/remove risk of transfer of non-native species.	Reduce/remove risk of transfer and settlement of non-native species.	N/A	MeyGen 2012, McPherson 2015, Magallanes Renovables 2020, Aquamarine Power Ltd 2011
Tidal	Operation & Maintenance	Changes in water flow Modifications to prey distribution and abundance (to include for other receptors) resulting in changes to foraging behaviour.	Birds Diving birds	Design feature Design structures to minimise effect on turbulence structure.		Minimises change in turbulence structure and hence potential interaction	Can present financial/ logistical/ design challenges to technology developer to alter design of device/ moorings	Aquamarine Power Ltd 2011, Davison and Mallows 2005, Tidal Energy Ltd 2008
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Contamination Potential for accidental or unplanned events which could lead to contamination of the marine environment.	Birds All receptors	Mitigation, Compliance Management: Establish and implement a Contamination Control Plan / Ship Oil Contamination Emergency Plans (SOPEPs). Compliance with International Maritime Organization (IMO) and Maritime Coastguard Agency (MCA) codes for the prevention of contamination.	Reduces risk of any contamination event and ensures that contingency plans are in place. Demonstrates compliance with environmental management systems.	Reduces risk of any pollution event and ensures that contingency plans are in place. Demonstrates compliance with environmental management systems.	N/A	Low 2012, MeyGen 2012, Orbital Marine Power 2010, GlaxoSmithKlineMontrose 2012, Foubister 2005, Davison and Mallows 2005, Xodus Group 2019, Royal Haskoning and Sea Generation (Kyle Rhea) Ltd. 2013, Magallanes Renovables 2020, McGrath 2013, Sustainable Energy Authority of Ireland (SEAI) 2011, The Marine Institute 2016, Federal Energy Regulatory Commission (FERC) 2020, THETIS Energy 2009
Wave, Tidal	Operation & Maintenance	Lighting Potential for lighting to adversely affect nocturnal and migratory species.	Birds Seabirds	Design feature Consider type, colour and use of lighting during design and consultation with navigational stakeholders.	A targeted lighting plan may have the potential to reduce impacts on sensitive species but navigational safety takes precedence.	A targeted lighting plan may have the potential to reduce impacts on sensitive species but navigational interests need to be considered at all times	Navigational safety considerations will take priority over implementation of ecological aspects	Royal Haskoning and Sea Generation (Kyle Rhea) Ltd. 2013
Wave, Tidal	Installation	Barrier to movement Potential barrier to movement due to the physical presence of devices and associated moorings / support structures, cables and electrical equipment.	Fish All receptors	Design feature Array/ mooring configuration designed to avoid migratory routes or other important sites		Minimises risk of development acting as a barrier to movement by avoiding migratory routes or other important sites	May be inconsistent with optimal layout of the development for exploitation of the energy source. Can be a costly measure when scaling up to larger arrays.	Aquamarine Power Ltd 2011, Davison and Mallows 2005
Tidal	Operation & Maintenance	Collision risk Potential for collision with turbine blades.	Fish Fish	Monitoring Environmental monitoring to detect collision events.	Helps to develop an understanding of avoidance behaviour, nature of interactions and outcome of collision events. However, there are cost implications assocaited with this level of monitoring.	Understand avoidance behaviour, nature of interactions and outcome of collision events.	Can be a high cost associated with this. Unclear how much monitoring will be required to fully understand this risk. Practicalities of monitoring; technology is not advanced enough yet to do this efficiently. Data mortgage (concept of generating data more quickly than it can be analysed) Power supply availability - hard-wired vs. battery; power is required for monitoring and power availability can present logistical, financial and technical challenges. Interaction between equipment - e.g. multibeam sonar/ ADCP/ echosounder; there can be interaction between monitoring equipment which can present challenges in monitoring. Certain equipment used such as PAM may actually effect behaviour themselves.	SIMEC Atlantis Energy Ltd 2011, GlaxoSmithKlineMontrose 2012, Orbital Marine Power 2014
Wave, Tidal	Operation & Maintenance	Displacement Potential displacement of essential activities due to the presence of devices and associated moorings / support structures.	Fish Basking shark, large fish	None identified None identified.	n/a
Wave, Tidal	Operation & Maintenance	EMF Impacts of electromagnetic fields from landfall cables on sensitive species.	Fish Demersal fish	Design feature Limit cable voltage.	n/a			MeyGen 2012
Wave, Tidal	Installation, Decommissioning	Direct loss of protected or sensitive sub-littoral seabed communities due to the presence of devices and associated moorings or support structures on the seabed.	Fish Demersal fish	Mitigation Use of locally sourced materials, for cable protection, of the same type as the habitat to be disturbed by cable installation.	Minimise impact on biodiversity/ ecosystem.	Lost seabed is replaced with same material. Minimises habitat loss.	N/A
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Barrier to movement Potential barrier to movement due to the physical presence of devices and associated moorings / support structures, cables and electrical equipment.	Marine Mammals All receptors	Mitigation Adherence to vessel management plan.		Minimises the potential interaction between animals and construction or maintenance vessels.	N/A	OpenHydro and SSE Group 2013, Aquatera 2017, ScottishPower Renewables 2010
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Contamination Potential for accidental or unplanned events which could lead to contamination of the marine environment.	Habitat All receptors	Mitigation Where rock placement is used, ensure clean rock is used.	Reduces/removes risk of contamination from materials.	Reduces/removes risk of pollution from materials	N/A
Wave, Tidal	Installation, Operation & Maintenance, Decommissioning	Displacement Potential displacement of essential activities due to the presence of devices and associated moorings / support structures.	Marine Mammals All receptors	Design feature Array/ mooring configuration designed to avoid migratory routes or other important sites		Minimises risk of development creating displacement by avoiding migratory routes or other important sites	May be inconsistent with optimal layout of the development for exploitation of the energy source Can be a costly measure when scaling up to larger arrays	Aquamarine Power Ltd 2011, Davison and Mallows 2005