Great crested newt eDNA: choosing an accredited laboratory

Choosing a great crested newt eDNA laboratory is not a question of finding the lowest quote. Natural England's method requires analysis by a laboratory that takes part in, and passes, the annual proficiency testing scheme for great crested newt eDNA, and a result from a laboratory outside that scheme can be challenged by a case officer or by the authority's ecological adviser. Ask for the current proficiency evidence before the samples leave site, not after the result arrives.

The method itself comes from the Natural England commissioned research that validated eDNA sampling for this species, and every part of it is prescriptive: when you sample, how many subsamples, what preservative, how quickly the kit reaches the laboratory and how many replicate reactions are run. Deviate and the result is worth little.

What eDNA testing can and cannot establish

The test answers one question. Is great crested newt DNA present in this waterbody at the time of sampling. It does not tell you how many animals are present, whether the pond supports breeding, which life stages are using it, or how the terrestrial habitat around it is used.

That matters because the population size class assessment, which drives mitigation design and licensing, cannot be derived from eDNA at all. Size class needs the conventional survey suite across multiple visits, with a proportion of those visits falling in the peak part of the season. If your scheme will need a European protected species mitigation licence, eDNA answers the screening question and then the conventional survey programme starts.

A positive result is usually accepted without argument. A negative result is accepted for that season and that pond, and it does not establish absence in a later year. Reviewers should read a negative alongside the habitat suitability appraisal rather than on its own.

The sampling window and why it is fixed

Sampling runs from 15 April to 30 June inclusive. The window exists because DNA shed by adults and larvae is reliably detectable during the breeding period and falls away outside it, so a sample taken in July carries a real risk of a false negative even where animals are present.

There is no discretion to extend it. An ecologist asked in early July whether the survey can still be done should say no, and offer the alternative: presence or absence by conventional methods, which has its own earlier window, or waiting for the following spring. A Protected Species Survey is one of the report types where a suitably licensed ecologist is legally required under the Wildlife and Countryside Act 1981 and the Conservation of Habitats and Species Regulations 2017, and a draft prepared without that competence is a starting point for the licensed ecologist rather than a substitute for one.

Programme accordingly. A project that reaches the ecology chapter in August has lost a year for newts unless a district level licensing route is available, and that route has its own timing and cost rules.

Laboratory analysis and the accreditation expected

Three things distinguish an acceptable laboratory.

Participation in the annual Natural England proficiency test for great crested newt eDNA, with a current pass. This is the requirement that carries weight with authorities, and it is specific to this analyte rather than a general statement of quality.

An accredited quality system, commonly ISO/IEC 17025 accreditation held through the United Kingdom Accreditation Service for the relevant test scope. Accreditation and proficiency testing are not the same thing and one does not imply the other, so check both.

A reporting format that gives the working alongside the verdict. The report should state the date of receipt, the condition of the samples on arrival, the number of replicate reactions run, how many amplified, the results of the inhibition and degradation controls and the outcome of the positive and negative controls. A one-line certificate saying negative is not a defensible report.

Ask two further questions. What is the turnaround from receipt, and what happens if the degradation control fails. A failed control means the sample cannot be interpreted, and if that is discovered on 2 July the season is gone.

Sampling technique and chain of custody

The sampling protocol takes twenty subsamples spread around the accessible margin of the waterbody, combined into a single kit and mixed with the preservative supplied. The point of spreading the subsamples is that eDNA is patchy, and clustering them at one corner biases the result.

Practical discipline matters more than equipment. Fresh gloves and a fresh sampling ladle for each pond, no wading before sampling, sampling before any other survey activity disturbs the sediment, and separate kits kept apart in transit. Cross-contamination between an occupied pond and an unoccupied one produces a false positive that is impossible to unpick later.

Record the chain of custody as you go: sampler name, date and time, waterbody reference and grid coordinates, weather, water temperature where taken, storage between site and dispatch, courier and consignment reference, and the date of receipt at the laboratory. Reviewers should expect to see that table in the appendix. Its absence is the most common reason for asking an applicant to resample.

No licence is needed to collect a water sample, because nothing is handled, disturbed or caught. Competence still is. The sampler should be an ecologist who can identify the waterbody's suitability, spot when the margin is inaccessible and record the habitat context, and the survey report should say who did it and what their experience is. The professional reviewers listed in the professional directory are the right people to check that a submitted report meets the standard.

Negative results and residual risk

A negative eDNA result reduces risk. It does not eliminate it.

Consider the pond that was dry in May, the pond just outside the red line that was not sampled because access was refused, the ditch that holds water only in winter and the garden pond 180 metres away on a neighbouring property. All of these can support a population whose terrestrial range crosses the site, and all of them are routinely missed because the sampling covered only the ponds inside the boundary.

The defensible approach is to appraise every waterbody within a sensible radius, sample those you can, and explain in writing why any unsampled waterbody was excluded and what the consequence is. Where access is refused, say so and set out the precautionary position. A Preliminary Ecological Appraisal is where that reasoning belongs, and councils usually expect a suitably qualified author for it with professional review strongly advised.

Where conventional survey is still required

Bottle trapping, torch counting, netting and egg searching remain necessary in three situations. Where a size class assessment is needed to design mitigation or support a licence application. Where a negative eDNA result sits uncomfortably against strongly suitable habitat and known nearby records. And where the authority or the licensing body asks for it, which happens on schemes with substantial habitat loss.

Those surveys have their own window, starting earlier in the spring and requiring several visits with a share of them in the peak weeks, so a decision to move from eDNA to conventional survey has to be taken quickly once a result comes back. Waiting until the planning consultee response arrives in September wastes the season.

For the wider question of how long any ecological survey result remains usable, the note on checking whether a survey is still valid sets out the practical rules, and the note on what competent person means in planning legislation covers the statutory language behind these competence requirements.

This is general guidance, not legal advice; check the position with your local planning authority, Natural England or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval. For specialist technical reports, qualified professional input may be required.