Upon sample receipt, we score your samples according to quality: good, low sediment, medium sediment, high sediment, white precipitate, and presence of algae. Please see the following link for examples. Please try to avoid sediment.
Sometimes samples contain a white precipitate which we have found makes the recovery of 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 type of samples as indeterminate.
We have started investigating the water chemistry of some of these water bodies in an effort to identify what types of pond may cause this problem and thus whether they should be avoided or not.
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. 1 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.
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 due to undefined components in the water chemistry or may be due 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 then a re-test would most likely also return an inconclusive result. We have successfully performed re-tests on samples which 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 in the appendix to the results document.
Degradation results will be noted in the appendix to 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.
According to the NE technical advice note once collected we can store the samples for up to 1 month prior to analysis. We keep these samples at 4°C (in the fridge) prior to DNA extraction and analysis and recommend that if possible samples are stored in a fridge prior to their being returned to our laboratories. Samples will be fine if they are stored at ambient temperature for a few days e.g. during the transport process.
Unfortunately if you have ordered more kits than you require we will be unable to refund these unless the order is amended prior to the kits being sent out to you (in this case please email eDNA@adas.co.uk for advice and see our refund policy within our eDNA Terms and Conditions document).
Please note that we do have a kit only ordering option where analysis can be arranged once your samples have been collected. If you wish to return the unused kits to us for disposal or redistribution to charitable organisations then please return them to our laboratories alongside your pond samples.
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.