The use of environmental DNA test for Great crested newt licensing purposes
This guidance updates NRW’s position on the use of eDNA as a survey technique for Great Crested Newts (GCN). It does not change any recommendations regarding usage of other ‘traditional’ survey methods which may also be required to support conclusions. Overall survey strategies should therefore follow existing published guidance (Great Crested Newt Mitigation Guidelines, 2001) and incorporate any additional method specific guidance notes published by relevant public bodies.
NRW guidance
Natural Resources Wales (NRW) accepts eDNA test results as evidence of presence of GCN in support of our assessment of licence or planning applications. However, this technique alone may not be suitable for the purposes of evidencing the absence of GCN in all circumstances. Use of eDNA surveys is not a mandatory requirement for any application.
When using eDNA survey techniques to support either a planning or licence application we advise you consider the following:
1. Use of eDNA is recognised as one of several acceptable survey techniques for GCN. We will accept the usage of this technique if samples are undertaken in strict accordance with this guidance together with the instructions of the particular testing kit. We advise that all samples are collected by suitably trained and experienced GCN surveyors in accordance with biosecurity protocols.
2. The eDNA technique can occasionally yield both false positives and false negatives due to a number of factors including environmental degradation or contamination. Evidence suggests eDNA only remains detectable within the water for up to three weeks as environmental factors such as UV degrades DNA.. Owing to lower numbers or the absence of adult newts being present in waterbodies at other times, we consider there to be a higher risk of false negative results for samples collected outside of this time period. Therefore:
- NRW currently recommends eDNA sampling is undertaken between 15 April and 30 June. (NRW is actively reviewing the recommended window for eDNA sampling based on results of Welsh population monitoring).
- Negative results from eDNA samples taken outside 15 April to 30 June will not normally be accepted to confirm absence of GCN in isolation and further surveys using traditional survey methods will be required unless proposed works are of a lower risk i.e. carried out over a shorter duration and minor impacts are temporary in nature.
- Equally, unless proposed works are of a lower risk, should a negative result be obtained for a waterbody within 500 metres of a known GCN record, or within a landscape of high waterbody density (i.e. five or more ponds per square kilometre), further surveys using traditional methodologies will also be required to evidence absence of GCN, regardless of when eDNA sampling was undertaken.
- Positive results from samples taken outside of the optimum time period will be accepted as confirming presence without additional survey.
3. Results of eDNA surveys will not provide abundance and population size class assessments. Should a population size class assessment be required for the proposed development or project then traditional survey methods, undertaken in accordance with current recommendations within the Great Crested Newt Mitigation Guidelines, 2001 will normally be required. Reporting of traditional survey techniques must be included with submitted documentation.
4. The reporting of eDNA results must include the information specified in this checklist:
| Ref. | Requirement | Provided? |
|---|---|---|
| A | Declarations that published advice and testing kit specific instructions have been strictly followed | Yes/No |
| B | Declarations that only licensed or suitably experienced GCN surveyors have taken the samples | Yes/No |
| C | Copies of laboratory results as supplied by the analysis company | Yes/No |
| D | Information clearly detailing all referenced water bodies which were sampled | Yes/No |
| E | Dates that samples were taken | Yes/No |
| F | The relevant survey figures | Yes/No |
| G | The results (presence or absence) in tabular form including information on all water bodies surveyed and sampling methodologies employed | Yes/No |
| H | Numbering/references of waterbodies applied consistently throughout submitted documentation. This includes environmental statements and management plans | Yes/No |
| I | Evidence that companies used for eDNA analysis are suitably accredited and demonstrate a satisfactory level of performance | Yes/No |
5. Applicants must ensure they retain or have access to all results from eDNA surveys when used to support a licence application for at least 12 months following the date of the first licence return - date of which will be set out in any licence granted.
6. eDNA can also be used for post-development monitoring surveys if the only information required for licence reporting purposes is presence or absence, and provided samples are collected between 15 April and 30 June. However, most post-development monitoring will require additional survey effort (e.g. abundance information), which eDNA alone cannot provide.
7. During any eDNA sampling works, surveyors should be aware of factors affecting false negatives when collecting water samples, including environmental conditions such as low water quality, and species longevity / behaviour (meaning female newts do not necessarily breed every year). As a result, an indeterminate eDNA result should not normally be taken as a negative.