The MarESA approach is summarised below. Detailed guidance on the application of the MarESA approach is provided in Tyler-Walters et al. (2018).
The 'concept' of sensitivity has been developed over many decades and applied in coastal and marine habitats. Numerous approaches have been developed, applied at a range of spatial scales, and to a variety of management questions (see Roberts et al., 2010).
The most common approaches define 'sensitivity' as a product of:
the likelihood of damage (termed intolerance or resistance) due to a pressure;
the rate of (or time taken for) recovery (termed recoverability, or resilience) once the pressure has abated or been removed.
Or in other words "a species (population) is defined as very sensitive when it is easily adversely affected by human activity (e.g. low resistance) and recovery is only achieved after a prolonged period, if at all (e.g. low resilience or recoverability)" (OSPAR, 2008; Laffoley et al., 2000).
Sensitivity is an inherent characteristic determined by the biology/ecology of the feature (species or habitat) in question. But it is a 'relative' concept as it depends on the degree (expressed as magnitude, extent, frequency or duration) of the effect on the feature. Therefore, sensitivity assessment uses a variety of standardized thresholds, categories and ranks to ensure that the assessments of ‘relative’ sensitivity compare ‘like with like’. These are:
Common terms used in sensitivity assessment are defined in Table 1.
Term |
Definition |
Sources |
---|---|---|
Sensitivity |
The intolerance of a species or habitat to damage from an external factor and the time taken for its subsequent recovery. |
Laffoley et al. (2000); Tyler-Walters & Hiscock (2005). |
|
The likelihood of change when a pressure is applied to a feature (receptor) and is a function of the ability of the feature to tolerate or resist change (resistance) and its ability to recover from impact (resilience). |
Tillin et al. (2010), Tillin & Hull (2003), Tillin & Tyler-Walters (2014) |
Resistance (Intolerance) |
Resistance characteristics indicate whether a receptor can absorb disturbance or stress without changing character. |
Holling (1973) |
Resilience (Recoverability) |
The ability of a receptor to recover from disturbance or stress. |
Holling (1973) |
Vulnerability |
Vulnerability is a measure of the degree of exposure of a receptor to a pressure to which it is sensitive. |
Based on Hiscock et al. 1999; Oakwood Environmental Ltd (2002). |
Pressure |
The mechanism through which an activity has an effect on any part of the ecosystem. The nature of the pressure is determined by activity type, intensity and distribution. |
Robinson et al. (2008) |
Exposure |
The action of a pressure on a receptor, with regard to the extent, magnitude and duration of the pressure. |
Robinson et al. (2008) |
Sensitivity assessment involves a detailed literature review and compilation of the evidence on the effect of a given pressure on the feature (species or habitat) in question, at the pressure benchmark level of effect, on a pressure by pressure basis (Figure 1). The sensitivity assessment process 'identifies elements of the feature' that are important for the structure and functioning of the community or characteristic of the habitat, based on the literature review. Clearly, where the feature under assessment is a single species, that species is assessed.
Habitat sensitivity assessment assumes that the sensitivity of a habitat is dependent on the physical nature of the habitat, and the sensitivity of the species that make up the community present. In practice, communities can be composed of many tens or hundreds of species. Therefore, the species identified as important for the structure and functioning of the community or characteristic of the habitat are used to focus the assessment (Figure 1). However, wherever possible, all component species of the habitat are considered in the sensitivity assessment.
The sensitivity assessment process results in species and or habitats (features) ranked by relative sensitivity. The evidence used in the assessment is documented throughout. This resultant 'evidence base' is the ultimate source of information for the application of the sensitivity assessments to management and planning decisions.
Sensitivity assessment routinely indicates the confidence in the assessment, based on the quality of the evidence used and its applicability to the assessment of the likely effects of a pressure on a given feature (species or habitat).
Sensitivity assessments need to be applied carefully by trained marine biologists, for the following reasons.
The MB0102 sensitivity assessment methodology was developed to create a pressure vs. feature sensitivity matrix to support MCZ management (Tillin et al. 2010). Due to the project MB0102 timescales, the approach relied on expert judgement to create sensitivity assessments at two workshops. The Tillin et al. (2010) methodology was modified by Tillin and Hull (2012-2013), who introduced a detailed evaluation and audit trail of evidence on which to base the sensitivity assessments. The revised methodology (henceforth termed MarESA) was subsequently applied to Ecological Groups based on species characteristic of offshore, circalittoral biotopes (Tillin and Tyler-Walters, 2014) and to biogenic habitats, that is, seagrass (d’Avack et al. 2014), Mytilus edulis beds (Mainwaring et al. 2014) and Sabellaria spinulosa reefs (Gibb et al. 2014). Note - the MarESA approach supercedes and replaces the MarLIN approach.
Sensitivity assessment involves the following stages:
In order to assess sensitivity, elements of the features must be selected as the basis of the assessment. The assessment of sensitivity should be guided by the presence of key structural or functional species/assemblages and/or those that characterize the biotope groups. The species (or assemblages) which are regarded as key structural or functional species should be identified and a full audit trail provided. The types of species that should be identified for the habitat assessments are provided in Table 2. Physical and chemical characteristics are also considered where these structure the community.
Category |
Description |
---|---|
Key structural species |
The species provides a distinct habitat that supports an associated community. Loss/degradation of this species population would result in loss/degradation of the associated community. |
Key functional species |
Species that maintain community structure and function through interactions with other members of that community (for example through predation, or grazing). Loss/degradation of this species population would result in rapid, cascading changes in the community. |
Important characteristic species |
Species characteristic of the biotope (dominant, and frequent) and important for the classification of the habitat. Loss/degradation of these species populations may result in changes in habitat classification. |
The resistance and resilience of the feature are assessed against each pressure using the available evidence. A standard list of pressures, pressure descriptions and 'benchmark' levels of each pressure have been developed. The benchmarks are designed to provide a ‘standard’ level of pressure against which to assess resistance/resilience. The assessment scales used for resistance and resilience are given in Tables 3 and 4 respectively.
Resistance |
Description |
---|---|
None |
Key functional, structural, characterizing species severely decline and/or physicochemical parameters are also affected e.g. removal of habitats causing a change in habitat type. A severe decline/reduction relates to the loss of 75% of the extent, density or abundance of the selected species or habitat component e.g. loss of 75% substratum (where this can be sensibly applied). |
Low |
Significant mortality of key and characterizing species with some effects on the physicochemical character of habitat. A significant decline/reduction relates to the loss of 25-75% of the extent, density, or abundance of the selected species or habitat component e.g. loss of 25-75% of the substratum. |
Medium |
Some mortality of species (can be significant where these are not keystone structural/functional and characterizing species) without change to habitats relates to the loss of <25% of the species or habitat component. |
High |
No significant effects on the physicochemical character of the habitat and no effect on the population viability of key/characterizing species but may affect feeding, respiration and reproduction rates. |
Resilience |
Description |
---|---|
Very Low |
Negligible or prolonged recovery possible; at least 25 years to recover structure and function |
Low |
Full recovery within 10-25 years |
Medium |
Full recovery within 2-10 years |
High |
Full recovery within 2 years |
‘Full recovery’ is envisaged as a return to the state of the habitat that existed prior to impact. However, this does not necessarily mean that every component species has returned to its prior condition, abundance or extent but that the relevant functional components are present and the habitat is structurally and functionally recognizable as the initial habitat of interest.
The resistance and resilience scores are combined, as follows, to give an overall sensitivity score as shown in Table 5.
|
Resistance |
|||
---|---|---|---|---|
Resilience |
None |
Low |
Medium |
High |
Very Low |
High |
High |
Medium |
Low |
Low |
High |
High |
Medium |
Low |
Medium |
Medium |
Medium |
Medium |
Low |
High |
Medium |
Low |
Low |
Not sensitive |
Not sensitive - is recorded where the habitat or species has a ‘High’ resistance (and hence is likely to recover quickly i.e. a ‘High’ resilience) at the benchmark level of pressure. In the text, this is denoted by the phrase 'Not sensitive at the benchmark level'. It should be noted that the species or habitat might be sensitive at pressure levels higher than the benchmark (i.e. where the pressure is of greater intensity, magnitude, or duration).
The following terms are used to explain if a sensitivity assessment is not possible.
Not relevant (NR) – is recorded where the evidence suggests that there is no direct interaction between the pressure and the habitat (biotope) or species. ‘Not relevant’ is also used to denote interactions that are unlikely to occur at present or in future and to denote interactions that are literally ‘not relevant’, for example, deep mud habitats are not exposed to changes in emersion.
No evidence (NEv) – is recorded where there is not enough evidence to assess the sensitivity of the specific feature/pressure combination, there is no suitable proxy information regarding the habitat (biotope) or species on which to base decisions, and expert judgement alone does not allow an assessment to be made with any confidence. For example, some species have a limited distribution (e.g. a few or only one location) so that even basic physical, chemical, or biological tolerances cannot be inferred. An assessment of ‘No evidence’ does not mean that there is no information available for a feature but that the evidence does not support an assessment.
Not assessed (NA) – is recorded where the available evidence is extremely limited, poorly understood, or completely absent. As a result, the pressure/feature combination is excluded from the assessment. This approach is applied to the 'contaminant' pressures and ‘litter’.
Project MB0102 (Tillin et al. 2010) provided a single confidence score based on the robustness of the underlying evidence and was developed for assessments based on expert judgement. The approach developed by Tillin and Hull (2012-2013 Reports I-VII) was adapted for subsequent use for pressure-sensitivity assessments prepared by the project team for JNCC (Tillin and Tyler-Walters, 2014, d’Avack et al. 2014).
This approach assesses confidence in the evidence for three categories, the quality of the evidence or information used, the degree to which evidence is applicable to the assessment and the degree of agreement between evidence types (Table 6). The confidence assessment categories for resistance and resilience are combined to give an overall confidence score for the confidence category (i.e. quality of information sources, the applicability of evidence and the degree of concordance) for each individual feature/pressure assessment, using Table 7.
Confidence level |
Quality of evidence (information sources) |
Applicability of evidence |
Degree of concordance (agreement between studies) |
---|---|---|---|
High (H) |
Based on peer reviewed papers (observational or experimental) or grey literature reports by established agencies (give number) on the feature (habitat, its component species, or species of interest). |
Assessment based on the same pressures acting on the same type of feature ( habitat, its component species, or species of interest) in the UK |
Agree on the direction and magnitude (of impact or recovery) |
Medium (M) |
Based on some peer reviewed papers but relies heavily on grey literature or expert judgement on the feature ( habitat, its component species, or species of interest) or similar features |
Assessment based on similar pressures on the feature (habitat, its component species, or species of interest) in other areas. |
Agree on direction but not magnitude (of impact or recovery) |
Low (L) |
Based on expert judgement |
Assessment based on proxies for pressures e.g. natural disturbance events |
Do not agree on the direction or magnitude (of impact or recovery) |
|
Resistance confidence score |
||
---|---|---|---|
Resilience confidence score |
Low |
Medium |
High |
Low |
Low |
Low |
Low |
Medium |
Low |
Medium |
Medium |
High |
Low |
Medium |
High |
So that the basis of the sensitivity assessment is transparent and repeatable the evidence base and justification for the sensitivity assessments are recorded. A complete and accurate account of the evidence that was used to make the assessments is presented for each sensitivity assessment in the form of the literature review and a sensitivity matrix that records a summary of the assessment, the sensitivity scores and the confidence levels.
The resultant sensitivity reviews are subject to quality assurance by the MarLIN Editor and, wherever possible, subject to peer review by one or more independent experts.
The MarESA approach to sensitivity assessment is a development of the MarLIN approach based on new scales and benchmarks introduced by the MB0102 project and subsequent refinement of the approach (see Tyler-Walters & Hiscock, 2005; Tillin et al., 2010; Tillin & Hull, 2013; Tillin & Tyler-Walters, 2014). It represents an ongoing evolution of the sensitivity assessment process.
The approaches share the following.
The approaches differ in the following.
Points 2, 4, and 5 above mean that the MarLIN and MarESA sensitivity assessment ranks are not directly comparable. However, the documented 'evidence base' remains the basis for all the assessments and their application in a management or decision-making context.
Note all MarLIN reports are available under publications.
d’Avack, E.A.S., Tillin, H., Jackson, E.L. & Tyler-Walters, H., 2014. Assessing the sensitivity of seagrass bed biotopes to pressures associated with marine activities. Joint Nature Conservation Committee, JNCC Report No. 505, Peterborough, 83 pp.
Gibb, N., Tillin, H.M., Pearce, B. & Tyler-Walters, H., 2014. Assessing the sensitivity of Sabellaria spinulosa to pressures associated with marine activities. Joint Nature Conservation Committee. JNCC report No. 504, Peterborough, 67 pp.
Hiscock, K, Jackson, A. & Lear, D., 1999. Assessing seabed species and ecosystem sensitivities: existing approaches and development, October 1999 edition. Report to the Department of Environment, Transport and the Regions from the Marine Life Information Network (MarLIN). Marine Biological Association of the United Kingdom, Plymouth. [MarLIN Report No. 1.]
Holling C.S., 1973. Resilience and stability of ecological systems. Annual Review of Ecology and Systematics, 4(1), 1-23.
Holt, T.J., Jones, D. R., Hawkins, S.J. & Hartnoll, R.G., 1997. The sensitivity of marine communities to man-induced change. Nature Conservation and the Irish Sea seminar. 6th February 1997, pp. 6-23. Irish Sea Forum, Liverpool, Seminar Report No. 15.
Holt, T.J., Jones, D.R., Hawkins, S.J. & Hartnoll, R.G., 1995. The sensitivity of marine communities to man-induced change - a scoping report. Countryside Council for Wales, Bangor, CCW Contract Science Report, No. 65.
Laffoley, D.A., Connor, D.W., Tasker, M.L. & Bines, T., 2000. Nationally important seascapes, habitats and species. A recommended approach to their identification, conservation and protection, pp. 17. Peterborough: English Nature.
Mainwaring, K., Tillin, H. & Tyler-Walters, H., 2014. Assessing the sensitivity of blue mussel beds to pressures associated with human activities. Joint Nature Conservation Committee, JNCC Report No. 506., Peterborough, 96 pp.
McMath, A., Cooke, A., Jones, M., Emblow, C.S., Wyn, G., Roberts, S., Costello, M.J., Cook, B. & Sides, E.M., 2000. Sensitivity mapping of inshore marine biotopes in the southern Irish Sea (SensMap): Final report. Report by the Countryside Council for Wales (CCW), Ecological Consultancy Services Ltd (Ecoserve), Dchas, the Heritage Service, 116 pp. [Maritime Ireland /Wales INTERREG Reference no. 21014001].
Oakwood Environmental Ltd, 2002. Development of a methodology for the assessment of cumulative effects of marine activities using Liverpool Bay as a case study. CCW Contract Science Report No 522.
OSPAR, 2003. Annex V to the OSPAR Convention. Criteria for the Identification of Species and Habitats in need of Protection and their Method of Application (The Texel-Faial Criteria). OSPAR 03/17/1-E. 13 pp.
OSPAR, 2008. OSPAR List of Threatened and/or Declining Species and Habitats (Reference Number: 2008-6). OSPAR Convention For The Protection Of The Marine Environment Of The North-East Atlantic <http://www.jncc.gov.uk/pdf/08-06e_OSPAR%20List%20species%20and%20habitats.pdf>
Roberts, C., Smith, C., H., T. & Tyler-Walters, H., 2010. Review of existing approaches to evaluate marine habitat vulnerability to commercial fishing activities. Report to the Environment Agency from the Marine Life Information Network and ABP Marine Environmental Research Ltd. Environment Agency Evidence Report: SC080016/R3. Environment Agency, Peterborough <http://publications.environment-agency.gov.uk/PDF/SCHO1110BTEQ-E-E.pdf>
Robinson, L.A., Rogers S. & Frid, C.L.J. 2008. A marine assessment and monitoring framework for application by UKMMAS and OSPAR - Assessment of Pressures and Impacts. Phase II: Application for regional assessments. JNCC Contract No: C-08-0007-0027. UKMMAS, 2010. Charting Progress 2.
Tillin, H. & Tyler-Walters, H., 2014. Assessing the sensitivity of subtidal sedimentary habitats to pressures associated with marine activities. Phase 2 Report – Literature review and sensitivity assessments for ecological groups for circalittoral and offshore Level 5 biotopes. JNCC Report No. 512B, 260 pp.
Tillin, H.M., Hull, S.C. & Tyler-Walters, H., 2010. Development of a sensitivity matrix (pressures-MCZ/MPA features). Report to the Department of the Environment, Food and Rural Affairs from ABPmer, Southampton and the Marine Life Information Network (MarLIN) Plymouth: Marine Biological Association of the UK., Defra Contract no. MB0102 Task 3A, Report no. 22., London, 145 pp. <http://randd.defra.gov.uk/Default.aspx?Menu=Menu&Module=More&Location=None&Completed=0&ProjectID=16368>
Tyler-Walters, H. & Hiscock, K., 2005. Impact of human activities on benthic biotopes and species. Report to Department for Environment, Food and Rural Affairs from the Marine Life Information Network (MarLIN), contract no. CDEP 84/5/244. Marine Biological Association of the UK, Plymouth. [View final report]
Tyler-Walters, H., Hiscock, K., Lear, D.B. & Jackson, A., 2001. Identifying species and ecosystem sensitivities. Report to the Department for Environment, Food and Rural Affairs from the Marine Life Information Network (MarLIN), Marine Biological Association of the United Kingdom, Plymouth. Contract CW0826.
Tyler-Walters, H. & Jackson, A. 1999. Assessing seabed species and ecosystems sensitivities. Rationale and user guide, January 2000 edition. Report to English Nature, Scottish Natural Heritage and the Department of the Environment Transport and the Regions from the Marine Life Information Network (MarLIN). Plymouth, Marine Biological Association of the UK. (MarLIN Report No. 4.).