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The sensitivity and confidence scoring followed the methodology from Tillen et al., (2010) as detailed in the following tables.
Table 5.2: Suggested resistance scale for sensitivity matrix (adapted from Hall et al 2008 and MarLIN)
| Tolerance (Resistance) | Description |
|---|
| None |
Key functional, structural, characterising species severely decline and/or physico-chemical parameters are also affected e.g. removal of habitat causing 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 element e.g. loss of 75% substratum (where this can be sensibly applied). |
| Low |
Significant mortality of key and characterising species with some effects on physico-chemical 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 element e.g. loss of 25-75% substratum |
| Medium |
Some mortality of species (can be significant where these are not keystone structural /functional and characterising species) without change to habitat type. The ‘some mortality’ referred to in Table 2 for medium resistance relates to the loss of 25% of the species or element. |
| High |
No significant effects to the physico-chemical character of habitat and no effect on population viability of key/characterising species but may affect feeding, respiration and reproduction rates. |
Table 5.3: Resilience scale for sensitivity matrix
| Recovery (Resilience) | Description |
|---|
| None |
Negligible or prolonged recovery possible; at least 25 years to recover structure and function |
| Low |
Full recovery within 10-25 years |
| Medium |
Full recovery between 2- 10 years |
| High |
Full recovery within 2 years |
Table 5.4: Combining resistance and resilience scores to categorise sensitivity
| Tolerance | | | |
|---|
| Recovery | 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 Sensitivie |
Sensitivity Scores and definitions
| Name | Description |
|---|
| High | A feature is assessed as having high sensitivity where the pressure causes severe or significant mortality of a species population (most individuals killed). Habitat features are highly sensitive where the pressure causes severe or significant mortality of key functional or structural species or those that characterise the habitat, and/or causes changes in the habitat such that environmental conditions are changed (e.g. the habitat type is changed). If recovery is possible, the feature is anticipated to take 10 years to recover from the impacts caused by the pressure. |
| Medium | Features with medium sensitivity are those characterised by medium resistance and no to low recovery or no to low resistance and medium to high recovery. |
| Low | Features with low sensitivity are those with high resistance or where recovery from any impacts caused by pressure is rapid, so that the feature is recovered within two years from cessation of pressure causing activity |
| Sensitive | Not enough information is available to complete one of the sensitivity assessment stages to give a final score, but due to concern over potential impacts on feature it has been assessed as sensitive. |
| Not Sensitive | There is a good level of evidence to suggest that although the feature may be exposed it is not considered to be sensitive to the pressure (i.e. where tolerance to the pressure is high where there is no significant mortality of individuals or changes to the habitat, and where recovery from any impact is complete within 2 years). |
| Not Exposed | Although the feature may be sensitive to the pressure, the activity exerting that pressure does not spatially overlap with the known distribution of the feature. |
| Not Assessed | There is no evidence available with which to undertake a sensitivity assessment or the pressure definition/benchmark is not applicable to the feature. |
| * | An asterisk is used to denote an underlaying range of sensitivites for habitat features (e.g. due to the feature including species with a range of different sensitivities to a pressure) OR for species it denotes a sensitivity within certain key areas for that species - explained further in evidence. |
Table 5.5: Confidence assessment categories for evidence
| Evidence |
Confidence Definition |
| Low Confidence - Evidence (LE) |
There is limited or no specific or suitable proxy information on the sensitivity of the feature to the relevant pressure. The assessment is based largely on expert judgement. |
| Medium Confidence Evidence (ME) |
There is some specific evidence or good proxy information on the sensitivity of the feature to the relevant pressure. |
| High Confidence- Evidence (HE) |
There is good information on the sensitivity of the feature to the relevant pressure. The assessment is well supported by the scientific literature. |
Table 5.6: Combined confidence assessments
|
Tolerance |
|
|
| Recovery |
Low |
Medium |
High |
| Low |
Low |
Low |
Low |
| Medium |
Low |
Medium |
Medium |
| High |
Low |
Medium |
High |