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Determining Value

Geographic Frame of Reference
Designated Sites and Features
Biodiversity Value
  Assigning value to habitats
  Assigning value to species
Potential Value
Secondary or Supporting Value
Social and Economic Value
Injurious and Legally Controlled Species


4.1 This chapter provides guidance on how to assign values to ecological features, including those that have been designated for their nature conservation interest. A suite of marine protected areas is currently evolving and absence of designated areas should not be taken to indicate a lack of value. Knowledge of marine biodiversity is rapidly increasing and our understanding of their status will therefore develop further. Consequently, the values that can be assigned to them must be expected to change.

4.2 These Guidelines encourage an approach that involves analysis of those values that can be attached to ecological features within the study area, these values include:

i. biodiversity and ecosystem services;

ii. social/community; and

iii. economic.

Legal requirements for the protection of biodiversity need to be considered separately from value. Ecological features that are important for social/community or economic reasons should be identified as part of the assessment of the socio-economic or community effects of a project e.g. tourism and recreation.

4.3 The value that is attached to an ecological feature influences:

  • whether, as part of screening, potentially affected ecological features are considered sufficiently valuable that there could be a significant effect that would trigger an EIA;
  • whether, as part of scoping, ecological features are considered for inclusion in the EcIA - this is influenced by their value in relation to a ‘threshold’ level of value that should be defined during scoping;
  • what mitigation or compensation measures are appropriate (this is described in more detail in Chapter 6); and
  • legal and policy implications of a project (see Chapter 7 for guidance on how this applies).

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Geographic Frame of Reference

4.4 In the EcIA Guidance (Terrestrial, Freshwater and Coastal 20061), IEEM advocates an approach to the valuation of ecological features using a geographical framework. Typically a table is developed indicating geographical categories (e.g. international, through to local) together with criteria and examples of how to place a site – defined by its ecological attributes - into these categories. It is generally straightforward to evaluate sites designated for their international or national importance, but for sites of local value, criteria may not be defined.

4.5 In the marine environment it is more difficult to define the geographical framework precisely and to accommodate all factors that should influence the definition of value, e.g. size or conservation status of populations or the quality of habitats. Furthermore, the value of a population or a habitat area may change depending on the country in which it is being assessed; this is a particular issue for trans-boundary impacts.

4.6 Where possible the value or potential value of an ecological resource or feature should be determined within a defined geographical context. The following frame of reference should be adapted to meet local circumstances:

  • International;
  • National;
  • Regional;
  • River Basin District;
  • Coastal cell;
  • County, District or local/parish (where coastal); and/or
  • within zone of influence only (which might be the project site or a larger area).

4.7 Professional judgement and consensus through peer review will be critical in defining the geographical framework. It should be based on available guidance and information, together with advice from experts familiar with the project’s location and/or the distribution and status of the ecological features being considered. The assumptions on which that judgement is based should be clearly set out in the EcIA Report. Subsequent sections provide guidance to determine those key considerations to take into account when applying professional judgement to assign values to ecological features.

4.8 In some EIAs or other integrated assessments, the ecologist may be required to use other approaches to assign levels of value (in order to be consistent across different technical subjects). In such cases, it is often helpful for the prescribed terms to reflect the geographical scale that is set out above, so that the legal and policy consequences of any significant impact can be clearly understood.

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Designated Sites and Features

Designated Sites

4.9 Although marine environmental protection is not currently as well developed as its terrestrial counterpart, some sites have already been assigned a level of nature conservation value through designation. A list of these for Britain can be found on the Protected Sites Designations Directory29 and for Ireland on the NPWS30 web site. The reasons for designation and the conservation objectives that are set out for them need to be clearly taken into account in EcIA.

4.10 Internationally important sites include SACs, SPAs and Ramsar sites. In the UK candidate SACs, potential SPAs and proposed Ramsar sites should be given the same consideration as designated sites in accordance with country specific policies and supporting guidance.

4.11 The World Heritage Convention31 (adopted by UNESCO in 1972) was ratified by the UK in 1984. The Convention provides for the identification, protection, conservation and presentation of cultural and natural sites of ‘outstanding universal value’, and requires a list to be established under the management of an inter-governmental World Heritage Committee. World Heritage Sites (WHS) that are included in this List may therefore be of international importance for their biodiversity. Some World Heritage Sites, such as the Giant’s Causeway, Dorset and East Devon Coast, and St Kilda, may be designated for their other natural features (e.g. geodiversity) or for their cultural heritage with no direct implications for their biodiversity value. Where this is the case, their biodiversity value should be determined on the basis of any other designations or features.

4.12 The Man and the Biosphere Programme (UNESCO 1977) was established to promote an interdisciplinary approach to research, training and communications in ecosystem conservation and rational use of natural resources. Sites designated by UNESCO as Biosphere Reserves (Braunton Burrows, North Norfolk Coast, Dyfi Estuary, Taynish, North Bull Island) are of international importance for the conservation of biodiversity31.

4.13 Nationally important sites are designated as SSSIs in England, Scotland and Wales or as ASSIs in Northern Ireland. They may also be Marine Nature Reserves e.g. Lundy, Skomer and Strangford Lough. However, recent legislation establish the framework for designating UK Marine Protected Area (MPA)32 network consisting of SACs, SPAs, and Marine Conservation Zones, the latter replacing the existing Marine Nature Reserves.

4.14 Lough Hyne in the Republic of Ireland was designated Europe’s first Marine Nature Reserve in 1981. To date only 75 raised bogs and 73 blanket bogs have been given legal protection. In addition, there are 630 proposed NHAs (pNHAs), which were published on a non-statutory basis in 1995, but have not since been statutorily proposed or designated.  Prior to statutory designation, pNHAs are subject only to limited protection.  Any Marine Protected Areas would be designated as Natural Heritage Areas (NHAs).

4.15 In the UK, Local Authorities and The Wildlife Trusts have identified sites that are recognised as of importance at regional/county, district/borough levels. These are recognised on Local Plans and Local Development Frameworks under a variety of names, which are now generally referred to collectively as Local Sites33. The Irish Wildlife Trust manages a network of reserves around the county which it aspires to expand in the future in order to protect more and more of Ireland’s wildlife and habitats. 

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4.16 Where an ecological feature has value at more than one level, its overriding value is that of the highest level. For example, a site designated as a MPA or SPA for internationally important features and as an SSSI for nationally important features should be considered as being internationally important. The features for which the site has been designated at each level may differ and should be valued accordingly. Features of the site that are not the reasons for its designation(s) should be assessed and valued according to their intrinsic value. In the marine environment, features of Natura 2000 sites are set out within the guidance issued by the statutory nature conservation agencies as required in Britain under Regulation 33 of the Habitat Regulations. In Ireland the features are set out on the NPWS Marine SAC web pages.

4.17 It is possible that ecologists undertaking EcIAs may identify areas that are not currently designated, (see Potential Value 4.29 et seq.) but that they consider would meet the criteria for designation in a particular geographical context, e.g. coral reefs, sub-tidal reefs or populations of waterfowl such as divers and sea duck. The discovery of significant new features, species, or habitats could have a significant bearing on the project’s initially perceived ecological impact, which may need reassessment and effective communication of the new values to the developer and project team, after confirmation with the statutory agencies.

4.18 Following the precautionary principle, and the forthcoming implementation of the Environmental Liability Directive (2004/35/EC), if a feature meets criteria for designation at a particular level then it should be treated in the same way as designated features in terms of potential impact etc. If this is the case, the ecologist should discuss their findings with the relevant designating authority. If it is agreed that the site merits designation this should be reflected in the assessment. Whether or not agreement can be reached, the features and issues must be explained fully in the EcIA.

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Biodiversity Value

4.19 There are various characteristics that can be used to identify ecological features likely to be important in terms of biodiversity. These include:

  • naturalness;
  • animal or plant species, subspecies or varieties that are rare or uncommon, either internationally, nationally or more locally and which may be seasonally transient;
  • priority Biodiversity Action Plan (BAP) habitat or species;
  • ecosystems and their component parts, which provide the habitats required by the above species, populations and/or assemblages;
  • endemic species or locally distinct sub-populations of a species;
  • habitat diversity, connectivity and/or synergistic associations (e.g. inshore nurseries for offshore fish stocks and high water roosts for wading birds that normally feed on the mudflats);
  • notably large populations of animals or concentrations of animals considered uncommon or threatened in a wider context;
  • plant communities (and their associated animals) that are considered to be typical of valued natural/semi-natural vegetation types e.g. saltmarsh, vegetated shingle communities, Zostera beds; these will include examples of naturally species-poor communities;
  • species on the edge of their range, particularly where their distribution is changing as a result of global trends and climate change;
  • species-rich assemblages of plants or animals, or assemblages that whilst species-poor are unusual e.g. subtidal Sabellaria alveolata reefs;
  • typical assemblages that are characteristic of homogenous habitats; and
  • vulnerability to invasive alien species.

4.20 Consultation with local specialists and the local community, as well as with SNCOs and national specialists, can be crucial for identifying less obvious but important ecological features.

4.21 The relative importance of different ecological features, resources, and functions may also change in response to changing conditions. For example, sea level rise may squeeze habitats against a fixed landward boundary (coastal squeeze), thus increasing their rarity.

4.22 The following sections explain in more detail how the relative value and importance of ecological features and resources can be determined.

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Assigning Value to Habitats

4.23 The value of areas of habitat and their biotopes should be measured against published selection criteria where available. For example, Annex III of the EC Habitats Directive sets out the criteria for selecting sites eligible for identification as sites of Community importance and designation as SAC. JNCC have published a Report on the identification of nationally important marine features in the Irish Sea35.

4.24 Habitat Action Plans (HAPs) have been developed for numerous habitats as part of the UK Biodiversity Action Plan (BAP) and of other BAPs, (e.g. local BAPs and organisational BAPs). There is a recently revised Marine Local Biodiversity Action Plan Guidance Manual for England BAP36 that offers considerable refinement to previous BAP listings. The approach to targeting actions differs according to the devolved administrations; those habitats considered to be particularly vulnerable are identified as ‘priority habitats’.

4.25 For further information on HAPs see the UK BAP web site37, the Welsh Biodiversity Partnership web site38 or in Ireland the Heritage Council list of LBAPs39.

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Assigning Value to Species

4.26 This part of the guidance deals with species that need to be assessed because they are of biodiversity value rather than because they are legally protected (although some species may fit in both categories). Legally protected species are discussed in Chapter 7.

4.27 In assigning value to a species, it is necessary to consider its distribution40,41 and status, including trends based on available historical records. A sessile, long-lived species can generally be assumed to occur regularly on a site, even after just one recent reliable record. However, records over a longer period, for example five years, may be needed for mobile species. The occurrence of species that are not typical of the habitat from which they have been recorded should be investigated in greater detail. It will be necessary to discuss the period over which data are needed with the relevant SNCO if there is a likelihood of there being an impact on a population or group of national or international importance.

4.28 The valuation of populations should make use of any relevant published evaluation criteria. For example, the Marine Life Information Network MarLIN42 holds spatially and time-series based marine biological information of relevance to the evaluation of species. There are also established criteria for defining nationally and internationally important populations of waterfowl43, and BAP habitats and species that are also of national importance.

4.29 Rarity is an important consideration because of its relationship with threat and vulnerability. Some species are inherently rare and it is therefore necessary to look at rarity in the context of status. A species that is rare and declining may be assigned a higher level of importance than one that is rare but known to be stable. Other rarity-related evaluation criteria include the need to protect populations where a country holds a large or significant proportion of an international species, e.g. a European population.

4.30 In common with habitats, Species Action Plans (SAPs) can be useful in identifying types of projects or impacts that should be considered for particular species.

4.31 Lists giving the current status of species (e.g. Birds of Conservation Concern44) can contribute to the understanding of the value of populations. Such lists need to be interpreted with caution as species may be in decline for different reasons and common species can also have high value.

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Potential Value

4.32 At present, understanding and conservation of the marine environment is less well developed than in terrestrial environments. Therefore, it is important to bear in mind the possibility that new and important ecological features will be identified during the course of EcIA (see Chapter 4 - 4.14 and 4.15). If this happens it is possible that designation(s) will be required and the implications of these should be given due consideration. Furthermore, degraded areas, e.g. areas of seabed damaged by bottom trawling, may lie in strategically important places that fit within the broader objectives for the conservation of biodiversity arising from the Convention on Biological Diversity (CBD). This means that the wider objectives of the Birds and Habitats Directives, as well as the CBD, will have a bearing upon the value of localities outside existing or proposed designated areas. See Chapter 4 - 4.16 to 4.18.

4.33 EU Directives (Water Framework Directive and Marine Strategy Directive) focus more broadly upon functional values identified through the need to achieve ‘Good Ecological Status’, ‘Good Ecological Potential’ and ‘Good Environmental Status’. Consideration of potential value of areas beyond existing site boundaries therefore needs to take account of their contribution to ecosystem functions, a matter of considerable importance in the marine environment where discrete populations with free-living larvae are linked by the water matrix. Thus, consideration needs to be given to the possible value of a locality for restoration of particular features or attributes by changing existing pressures (e.g. extractive use). These issues are also pertinent in the context of the wider objectives of Article 10 of the Habitats Directive, Article 3 of the Birds Directive and to the BAP process, which also sets targets for restoration of habitats and species.

4.34 The potential to recreate or restore the condition of a habitat may also have a bearing upon its value; some are less straightforward to re-create or to restore than are others as specific conditions such as substrate type and physical processes are difficult to replicate. This is particularly important when the development of adaptive responses to climate change is considered. In the marine environment we know little about recreating habitats, but we do know that long-lived species are often under the greatest threat (e.g. fan shells Atrina fragilis and pink sea fan Eunicella verrucosa). Consequently the potential value of sites with appropriate characteristics for longer-lived species need to be given due consideration. In this respect, the potential value of limiting extractive use and the restoration of ecosystem function in association with a proposal may be of importance.

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Secondary or Supporting Value

4.35 Some features that are currently of no particular ecological interest in themselves may nevertheless perform an important ecological function, e.g. because they act as a buffer against negative impacts, or because they enable in some other way the effective conservation of a more valuable feature. For example, an area of low quality grassland might be included in a saltmarsh SSSI to allow the saltmarsh to migrate landward as a consequence of sea level rise.

4.36 It is also relevant to note that Article 10 of the Habitat Directive directs Member Statesto ‘endeavour, where they consider it necessary, in their land-use planning and development policies and, in particular, with a view to improving the ecological coherence of the Natura 2000 network, to encourage the management of features of the landscape which are of major importance for wild fauna and flora. Such features are those which, by virtue of their linear and continuous structure (such as rivers with their banks or the traditional systems for marking field boundaries) or their function as stepping stones (such as ponds or small woods), are essential for the migration, dispersal and genetic exchange of wild species. This terrestrial concept has yet to be defined for marine habitats, but as connectivity is very important for numerous marine species the spirit of this Article needs to be taken into account especially in relation to identifying areas as sources or sinks for eggs and larvae, water quality, critical habitats and migration patterns, e.g. for spawning and/or feeding.

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Social and Economic Value

4.37 Ecological features may have both social (e.g. aesthetic, recreational, educational) and economic (e.g. commercial fisheries, sport angling, diving, eco-tourism) values. Consequently, ecologists need to quantify the nature and magnitude of potential impacts to ecological features. This allows social scientists and economists to identify and assess any consequent socio-economic effects of activities such askelp harvesting on species and habitats that act as a tourism, research or educational resource.

4.38 Defra has published two documents An introductory guide to valuing ecosystem services and Securing a healthy natural environment: an action plan for embedding an ecosystems approach. The guide is a systematic approach to the assessment of impacts on the natural environment to ensure that the true value of ecosystems and the services provided are taken into account in policy decision-making. The action plan sets a new strategic direction for government policy on the natural environment with the intention of developing a more integrated approach focused on whole ecosystems that allows the value of ecosystem services to be fully reflected in decision-making. In Scotland, the Climate Change Act45 and Flooding Risk Management Act46 highlight the value of ‘Blue Carbon’ and Ecosystem Services that deliver carbon sequestration.

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Injurious and Legally Controlled Species

4.39 More than 65 species of marine alien species have been recorded in the waters round the British Isles. Some, such as the Chinese mitten crab Eriocheir sinensis, wireweed Sargassum muticum and Pacific oyster Crassostrea gigas are highly invasive. Warming of the seas has encouraged a northward movement of many species but it is unclear what the short and longer term outcomes for biodiversity will be. Marine developments may lead to the colonisation of new areas. If invasive species such as these are assessed as having ecological, social or commercial benefit/detriment, advice should be provided on the ecological and legal consequences of their presence, those circumstances that would precipitate their establishment and any preventative actions that can be taken. For example, a regular survey of marinas on the west coast of Scotland identified the presence of the carpet sea squirt, Didemnum vexillum, early enough for control action to be taken.

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