eDNA analysis for great crested newts

All samples must be taken in accordance with the Natural England Technical Advice Note. However, for simplicity, we have replicated the sampling method and included it within the eDNA Protocol sent out within every kit.

According to the technical advice note samples taken between 15 April to 30 June can be used for GCN eDNA analysis. Please note that we have had confirmation from Natural England that they would be willing to consider eDNA results from samples taken outside of this period so long as there is documented evidence that the GCN are still active. Similarly, Natural England would expect consultants and others to advise against eDNA surveys when GCN are no longer active in ponds, even if it is before 30 June.

• Super fast-track: 2 working days
• Fast track: 3–5-working days (we averaged 3.3 days in 2025)
• Standard analysis: 7–10 working days (we averaged 6.0 days in 2025)
• Non-priority: up to 1 month (this option is for clients who do not require their results quickly)

There are three reasons as to why sediment should be avoided:

1. It is possible for DNA to persist within the sediment for longer than it would if it was floating in the water which could lead to a false-positive result i.e., in this case GCN not recently present but present a long time ago
2. In some cases, sediment can cause inhibition of the PCR analysis used to detect GCN eDNA within samples that could lead to an indeterminate result.
3. In some cases, sediment can interfere with the DNA extraction procedure, which can lead to an indeterminate result.

Upon sample receipt, we score your samples according to quality: good, low sediment, medium sediment, high sediment, white precipitate and presence of algae. Please try to avoid sediment.

Algae can make the DNA extraction more difficult to perform, so if it can be avoided then this is helpful.

Important info regarding out of season testing

Sometimes samples contain a white precipitate that makes recovering eDNA very difficult. This precipitate can be present in such high amounts that it interferes with the eDNA extraction process meaning that we cannot recover the degradation control (nor most likely the eDNA itself) at sufficient levels for the control to be within the acceptable limits for the assay. Therefore, we have to classify these types of samples as indeterminate.

We have started investigating the water chemistry of some of these water bodies to identify what types of ponds may cause this problem and thus whether they should be avoided or not.

The technical advice note states that kits should be used within about two weeks of receipt. However, Natural England has agreed that from 2018 onwards kits will have a shelf life of three months.

You will need 1 kit per pond (for up to 1 hectare in size).

In terms of larger ponds/lakes the only guidelines we have for GCN analysis using eDNA is that we can use a single kit for an area of up 1 hectare, if a lake is larger than this then you need to use multiple kits i.e., one kit per hectare.

We have carried out analysis on 2 lakes where 2 kits had to be used and we advised our client to use one kit to sample one half of the circumference of the lake and the second for the other half of the circumference, when they got back to the lab we analysed each kit separately.

In doing it this way if there were GCN present in a small area then any eDNA present will then not be diluted as much as it would should the whole lake be sampled into each kit.

All samples are processed as follows (Natural England Technical Advice Note):

• The DNA is extracted and stored before a polymerase chain reaction (PCR) test at -20°C
• All samples are tested for inhibition using a real-time PCR assay, if inhibition is found then the sample is diluted 1 in 2 for subsequent analysis
• All samples are tested for degradation using a real-time PCR assay
• All samples are tested for presence of GCN DNA again using a real-time PCR assay

Even is a sample is found to be degraded it is still analysed for GCN DNA as about 15% are found to be positive for GCN DNA (2025 figures).

For an example, please see eDNA results letter example document.

• A positive result means that great crested newts are present in the water or have been present in the water in the recent past (eDNA degrades over around 7-21 days).
• A negative result means that DNA from the great crested newt has not been detected in your sample.
• On rare occasions an inconclusive result will be issued. This occurs where the DNA from the great crested newt has not been detected, but the controls have indicated that the sample has been degraded or the PCR inhibited in some way. This may be because of undefined components in the water chemistry or owing to the presence of high levels of sediment or algae in your sample. A re-test could be performed but a fresh sample would need to be obtained. If water chemistry was the cause of the indeterminate, a re-test would likely also return an inconclusive result. We have performed re-tests on samples that have had high sediment content on the first collection and low sediment content (through improved sample collection) on the re-test.
• Sediment content of each sample is visually recorded and reported on the results document.
• Inhibition results will be noted on the results document.
• Degradation results will be noted on the results document. If the result is recorded as evidence of decay (meaning that the degradation control was outside of accepted limits) or evidence of residual inhibition (meaning that the PCR reaction was inhibited) any negative result will be recorded as indeterminate.

• Kit only – £30 (available on request)
• 2 day turnaround – £310
• 3–5 day turnaround – £248
• 7–10 day turnaround – £170
• Non-priority – £144
• Return courier charges – £30 (up to 25 kits per box, no charge for outward delivery)

These are the prices for the kit itself (everything required to collect the water sample), the analysis, and the return of the results. All prices are ex-VAT.

Additional one-way return couriering can be purchase at the cost of £30 per additional courier trip e.g. if you wanted to return samples as different times.

According to the NE technical advice note, once collected we can store the samples for up to one month before analysis. We keep the samples at 4°C before DNA extraction and analysis. We recommend storing samples in a fridge before returning them to our laboratories. Samples will not degrade if stored at ambient temperature for a few days during transport.

We will perform testing outside of the survey window (15 April to 30 June) on the understanding that the results will not be acceptable to Natural England. If a negative result is obtained, a further eDNA analysis (or full traditional survey if you choose to do so) will need to be performed during the survey window. A positive result at this time will allow for accurate forward planning for the next survey season in terms of budget, project risk, and time to completion.

We have been able to detect GCN all year round in a couple of ponds with known good populations, this suggests that the larval stage is also detectible using the eDNA analysis (Rees et al, 2017). A study undertaken at the Durrell Institute of Conservation and Ecology also agrees with this finding (Buxton et al, 2017)

We can redistribute large numbers of unused kits to other clients at the end of the season. You will not be charged for unused kits that are returned to us by the 15 June in the season they were ordered.

If kits are returned after this date, we may not be able to redistribute to other clients, and you would be charged for them at £30 per kit (we do not charge for unused analysis).

If you wish to return unused kits to us after the 15 June for disposal/recycling, please return them to our laboratories alongside your pond samples or contact us for a collection at edna@adas.co.uk.

If you would like to test your samples for additional species (up to three additional species) that we have available species-specific tests for, please let us know at edna@adas.co.uk. Each additional species test will be performed in 12 replicates (as per GCN) and will be charged at £100 per additional species.

Please contact us if you are interested in a mass sequencing approach to detect multiple species within water bodies at the same time. We also offer bat speciation testing from guano samples, this test can also be used for various other species including otter, mink, water vole etc.

Orders can be adjusted or cancelled prior to dispatch of kits, please contact eDNA@adas.co.uk. Once kits have been dispatched to you, extra/unused kits will need to be returned by 15 June or they will be charged at £30 per kit.

For credit card orders a VAT receipt should have been sent to you at the time of ordering if you wish another copy to be sent, please email us at eDNA@adas.co.uk and this will be re-issued to you.

Please let us know if you do not receive your kits on your requested date as we can track the parcels progress. On rare occasions, kits have not been delivered due to e.g., the supply of incorrect address details and no one being present to accept delivery.

For further help, you can contact edna@adas.co.uk.