Environmental DNA monitoring

Also known as eDNA, Environmental DNA (eDNA), Airborne eDNA

Environmental DNA (eDNA) monitoring detects species from traces of DNA shed into water, soil or air, so surveyors do not have to catch or see the animals. It is used as a survey method for great crested newts in England, but false positives, false negatives and unreliable abundance estimates limit its use.

Pilot and early commercialDemonstratedReviewed 21 Oct 2026
AI illustration · Illustrative scene, not a photograph of the specific device or experiment.

In plain language

Environmental DNA, or eDNA, is genetic material that living things leave behind. Animals shed skin cells, hair, slime and waste, and these traces can carry their DNA into the water, soil or air around them. Scientists collect a sample, extract the DNA and check it for the genetic signature of particular species.

This means a survey can show that a species is probably present, sometimes without ever meeting the animal. For great crested newts, a pond-dwelling amphibian, a water sample test is an accepted alternative to some traditional surveys in England. The method is not perfect, though. Tests can give false alarms, can miss animals that are there, and cannot yet reliably say how many animals there are. Sampling from air is at an early research stage.

Technical explanation

A common water test filters or precipitates DNA from a sample, then amplifies a short target sequence using quantitative PCR (qPCR), which records whether each replicate reaction is positive. Metabarcoding amplifies a broader gene region from many species at once and reads the sequences on a high-throughput sequencer, so it can detect many species in one sample. In a study that screened 532 eDNA samples for great crested newts, qPCR detected the species in about 50% of ponds when one positive replicate out of 12 was enough, and in 32% when at least four were needed. Metabarcoding detected them in 34% of ponds without a detection threshold and in 28% with a threshold of 0.028% of reads. The authors state that unthresholded metabarcoding matched stringent qPCR, while qPCR detected more newts overall (Harper et al., 2018).

Error rates matter because every positive or negative result is a probability, not a certainty. A modelling study of a national English dataset estimated that about 20% of ponds were occupied (posterior mean 0.198). It estimated a sample-level false-negative rate of 5.2% at the field stage, with a credible interval of 0.1% to 25.1%, and a false-positive rate of 2% per qPCR replicate in the laboratory. Because labs run many replicates, the probability that at least one replicate returns a false positive reached about 24% with 12 replicates, so single-replicate positive calls are unreliable (Buxton et al., 2022).

Quantification is the weakest part of the method. In controlled tanks with three fish species, eDNA concentration had a moderate-to-high, nonlinear relationship with fish biomass, with partial adjusted R-squared values of about 0.42 to 0.62 (Talarico et al., 2026). The authors call for validation in natural systems. Airborne sampling is newer. A zoo study detected 49 vertebrate species from air filters using metabarcoding, with higher detection odds for animals nearer the sampler and for those with greater biomass (Lynggaard et al., 2022). A 2026 review notes that air sampling generally needs more labour and time than soil or water sampling, and that airborne eDNA largely reflects local species, although pollen and spores can carry DNA from more distant species (Zhao and Andermann, 2026).

What the evidence says

Each statement is typed by the strength of its evidence and linked to the source that supports it.

Demonstrated Shown in a published experiment, test or shipping product.

In a study that screened 532 eDNA samples for great crested newts, targeted qPCR detected the species in about 50% of ponds when one positive replicate out of 12 was enough, and in 32% when at least four positive replicates were required.

Sources: [2] · Abstract · medium confidence

Metabarcoding detected great crested newts in about 34% of ponds without a detection threshold and in about 28% with a threshold of 0.028% of reads.

Sources: [2] · Abstract · medium confidence

A national analysis of English pond eDNA data estimated that about 20% of ponds were occupied by newts (posterior mean 0.198), with a sample-level false-negative rate of 5.2% (credible interval 0.1% to 25.1%) at the field stage.

Sources: [3] · Abstract and Discussion

False positives occur at both stages of the national analysis, at about 1.5% of field water samples and 2% of qPCR replicates in the laboratory, and with 12 replicates the probability that at least one replicate returns a false positive is about 24%.

Sources: [3] · Abstract and Discussion · medium confidence

In May 2023 Natural England published an evidence review of the great crested newt eDNA protocol in its 2014 technical advice note (WC1067 Appendix 5). The review set out to compare ethanol precipitation with filtration, and Natural England concluded that more evidence was required before any change. The summary page does not report the comparative results.

Sources: [4] · Summary of findings

Air sampling at Copenhagen Zoo detected 49 vertebrate species (30 mammals, 13 birds, 4 fish, 1 amphibian and 1 reptile), and detection odds were higher for animals closer to the sampler and for animals with greater biomass.

Sources: [5] · Abstract · medium confidence

Air sampling generally needs more labour and time than soil or water sampling, and airborne eDNA largely reflects local species, although pollen and spores can carry DNA from more distant species.

Sources: [6] · Stated limitations (air)

In controlled tanks with three fish species, eDNA concentration had a moderate-to-high, nonlinear relationship with fish biomass, with partial adjusted R-squared values of about 0.42 to 0.62, and the authors call for validation in natural systems.

Sources: [7] · Abstract and results · medium confidence

Proposed A design or plan that has not yet been built or tested.

Thomsen and Willerslev describe environmental DNA as an efficient, non-invasive and easy-to-standardise sampling approach for biodiversity monitoring.

Sources: [1] · Abstract · medium confidence

The authors state that unthresholded metabarcoding matched stringent qPCR for newt detection, that qPCR detected more newts overall, and that community-level metabarcoding can guide where species-specific surveys are used.

Sources: [2] · Abstract (conclusions) · medium confidence

Limitations and open problems

  • A positive result can be a false positive. In the English national dataset, false positives occurred at both the field and laboratory stages, and their chance grows with the number of replicates (Buxton et al., 2022).
  • A negative result can be a false negative. The same study estimated a 5.2% sample-level false-negative rate at the field stage (Buxton et al., 2022).
  • eDNA concentration is only moderate-to-high and nonlinear in relation to biomass in controlled tanks, and field validation is still needed (Talarico et al., 2026).
  • For great crested newts, qPCR detected more newts overall than metabarcoding, so metabarcoding is not a like-for-like replacement for a species-specific test (Harper et al., 2018).
  • Natural England's 2023 review (NECR476) of the 2014 great crested newt eDNA protocol (WC1067 Appendix 5) found that more evidence was needed before changing the protocol, so the rules may shift.

Possible future uses

Speculative

Ideas, not predictions. None of these has been demonstrated.

  • Air sampling near farms or ports to watch for invasive species or disease-carrying animals, if false-positive control becomes strong enough to act on the results.
  • Routine national networks of water and soil sampling that track biodiversity across whole regions.
  • Air sampling inside animal facilities or buildings to show which species are present, without trapping or disturbing them.

Product concepts: Invasive species eDNA kit

Timeline

  1. 2014Great crested newt eDNA field and laboratory methods, set out in technical advice note WC1067 Appendix 5, come into use from the 2014 survey season. Sources: [4]
  2. Mar 2015Thomsen and Willerslev publish a review in Biological Conservation on eDNA as a tool for monitoring past and present biodiversity. Sources: [1]
  3. 2018Harper and colleagues publish a comparison of eDNA metabarcoding and targeted qPCR for great crested newts in 532 eDNA samples. Sources: [2]
  4. Jan 2022Lynggaard and colleagues publish a study detecting vertebrate species from air filters at a zoo. Sources: [5]
  5. 18 May 2023Natural England publishes NECR476, an evidence review of great crested newt eDNA protocols, concluding that more evidence is needed before any change. Sources: [4]
  6. 23 Jan 2026Zhao and Andermann publish a review of eDNA substrates for terrestrial animal monitoring, including air sampling. Sources: [6]

Futures this could help bring about

AI illustration
How far away?

Tracking wildlife from DNA in water and air

Pilots · 1 of 5 steps done

Related breakthroughs

Glossary

Environmental DNA (eDNA)
DNA that organisms leave in their surroundings, such as water, soil or air, through skin, hair, slime or waste.
Quantitative PCR (qPCR)
A laboratory method that copies a short target DNA sequence and measures, reaction by reaction, whether it is present.
Metabarcoding
Amplifying a standard gene region from many species at once and identifying them by sequencing.
False negative
A test result that says a species is absent when it is actually present.

Sources

  1. review article
    Environmental DNA - An emerging tool in conservation for monitoring past and present biodiversity
    Philip Francis Thomsen, Eske Willerslev. Biological Conservation, Mar 2015. DOI: 10.1016/j.biocon.2014.11.019. Accessed 21 Oct 2026.
  2. peer reviewed paper
    Needle in a haystack? A comparison of eDNA metabarcoding and targeted qPCR for detection of the great crested newt (Triturus cristatus)
    Lynsey R. Harper, Lori Lawson Handley, Christoph Hahn et al.. Ecology and Evolution, 2018. DOI: 10.1002/ece3.4013. Accessed 21 Oct 2026.
  3. peer reviewed paper
    Reliability of environmental DNA surveys to detect pond occupancy by newts at a national scale
    A. Buxton, A. Diana, E. Matechou et al.. Scientific Reports, 2022. DOI: 10.1038/s41598-022-05442-1. Accessed 21 Oct 2026.
  4. government report
    An evidence review for great crested newt eDNA monitoring protocols (NECR476)
    Natural England, 18 May 2023. Accessed 21 Oct 2026.
  5. peer reviewed paper
    Airborne environmental DNA for terrestrial vertebrate community monitoring
    C. Lynggaard, M. F. Bertelsen, C. V. Jensen et al.. Current Biology, Jan 2022. DOI: 10.1016/j.cub.2021.12.014. Accessed 21 Oct 2026.
  6. review article
    Properties and Limitations of eDNA Substrates for Terrestrial Animal Monitoring
    Beilun Zhao, Tobias Andermann. Molecular Ecology Resources, 23 Jan 2026. DOI: 10.1111/1755-0998.70096. Accessed 21 Oct 2026.
  7. peer reviewed paper
    Controlled Experiments Reveal Moderate, Nonlinear Relationships Between eDNA Concentration and Fish Biomass in Three Freshwater Species of Monitoring Relevance
    Lorenzo Talarico, Gerardo Petrosino, Anna Rita Rossi et al.. Ecology and Evolution, Feb 2026. DOI: 10.1002/ece3.73129. Accessed 21 Oct 2026.

Revision history

3 changes since this profile was created.

Changes on 21 Oct 2026
Published on owner instruction (content loop iteration 7)fd22377
Sources and claims re-checked against originalsfbb434c
Initial profile drafted from primary sources7e66249