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Can Monster DNA Be Misleading?

Contamination, transported DNA and lab errors can make a species appear present when the lake evidence is weaker than it looks.

On this page

  • How contamination enters samples
  • Why DNA can travel from elsewhere
  • What checks make a claim stronger
Preview for Can Monster DNA Be Misleading?

Introduction

Environmental DNA (eDNA) is often presented as a powerful new way to test lake-monster claims because it can detect genetic traces left behind by animals in the water. However, a surprising DNA match is not automatically evidence that an unusual creature lives in a lake. One of the most important lessons from eDNA research is that positive detections can arise from contamination, transported genetic material, laboratory mistakes, or misinterpretation of what a DNA signal actually means. Researchers therefore distinguish between detecting DNA and proving that a living population is present. In cryptozoological investigations, where extraordinary claims may rest on very limited evidence, understanding false positives is as important as understanding successful detections.[BES Journals+2Wiley Online Library]besjournals.onlinelibrary.wiley.com2041 210X.12595BES JournalsCritical considerations for the application of environmental…by CS Goldberg · 2016 · Cited by 1438 — Critical consideratio…False Positives illustration 1

Can Monster DNA Be Misleading?

A common misunderstanding is that eDNA works like a biological photograph. In reality, it detects fragments of genetic material that have entered the environment. Those fragments can reveal that DNA from a species reached a location, but they do not always prove that a living animal is currently inhabiting the sampled water.[Natural History Museum]nhm.ac.ukIf someone tested a sample of the water, these pieces of DNA could indicate the recent…Read more…

Researchers studying eDNA often separate two different problems:

  • A false-positive test, where contamination or analytical error creates an incorrect DNA detection.
  • A false-positive inference, where the DNA is genuinely present in the sample but the conclusion that a living animal occupies the lake is incorrect.[Wiley Online Library+2PubMed Central]onlinelibrary.wiley.comOnline Library What do you mean by false positive?Darling - 2021by JA Darling · 2021 · Cited by 128 — The term false positive is often misused in eDNA research and natural resource manage…

This distinction matters greatly for lake-monster investigations. Even if an unexpected DNA sequence appears in a sample, investigators must determine whether it reflects a resident animal, transported material, contamination, or a technical artefact before treating it as evidence for an unknown creature.[BES Journals]besjournals.onlinelibrary.wiley.com2041 210X.12595BES JournalsCritical considerations for the application of environmental…by CS Goldberg · 2016 · Cited by 1438 — Critical consideratio…

How Contamination Enters Samples

Environmental DNA surveys involve many stages: collecting water, filtering it, extracting DNA, amplifying genetic markers, sequencing them, and comparing the results with reference databases. Contamination can occur at almost any step.[BES Journals]besjournals.onlinelibrary.wiley.com2041 210X.12595BES JournalsCritical considerations for the application of environmental…by CS Goldberg · 2016 · Cited by 1438 — Critical consideratio…

Field contamination

Loch Ness monster might just be a giant eel

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Laboratory contamination

DNA laboratories face a similar challenge. Modern genetic techniques are extremely sensitive, meaning tiny amounts of stray DNA can sometimes be amplified. Cross-contamination between samples, aerosolised DNA from previous experiments, or carry-over from positive controls can generate detections that appear genuine unless careful safeguards are in place.[BES Journals+2Nature]besjournals.onlinelibrary.wiley.com2041 210X.12595BES JournalsCritical considerations for the application of environmental…by CS Goldberg · 2016 · Cited by 1438 — Critical consideratio…

Because cryptozoological claims often focus on rare or unexpected sequences, contamination can be particularly misleading. A trace signal that appears exciting may actually be the kind of low-level contamination that rigorous controls are designed to identify and eliminate.[BES Journals]besjournals.onlinelibrary.wiley.com2041 210X.12595BES JournalsCritical considerations for the application of environmental…by CS Goldberg · 2016 · Cited by 1438 — Critical consideratio…

Why DNA Can Travel From Elsewhere

Not all misleading detections result from mistakes. Sometimes the DNA is genuinely present in the sample but arrived from somewhere else.

Environmental DNA researchers refer to this as the problem of allochthonous, or externally transported, DNA. Genetic material can move through waterways, enter lakes from inflowing rivers, or arrive via animals that carry biological material between habitats.[BES Journals]besjournals.onlinelibrary.wiley.com2041 210X.12595BES JournalsCritical considerations for the application of environmental…by CS Goldberg · 2016 · Cited by 1438 — Critical consideratio…

Examples discussed in the scientific literature include:<div class="content-enhancement content-enhancement--insight-grid" markdown="1">

  • Predator faeces containing DNA from prey species.
  • Birds transporting biological material between water bodies.
  • Water movement carrying DNA downstream from its original source.
  • Human activities transporting organisms or biological material between locations.[BES Journals]besjournals.onlinelibrary.wiley.com2041 210x.70328ballast water, transport) or naturally…</div>

For lake-monster searches, this means that an unexpected sequence does not necessarily indicate a large unknown animal living in the lake itself. The DNA may have originated elsewhere and been transported into the sampling area. The rarer and more surprising the detection, the more carefully this possibility must be examined.[BES Journals]besjournals.onlinelibrary.wiley.com2041 210X.12595BES JournalsCritical considerations for the application of environmental…by CS Goldberg · 2016 · Cited by 1438 — Critical consideratio…False Positives illustration 2

The Database Problem: When a Match Is Not What It Seems

Another route to false confidence comes from species identification itself.

After sequencing, researchers compare DNA fragments against reference databases. The quality of the identification depends on how complete those databases are and how distinctive the recovered DNA fragment is. Short fragments may match multiple related species, while some organisms remain poorly represented in reference collections.[BES Journals]besjournals.onlinelibrary.wiley.com2041 210X.12595BES JournalsCritical considerations for the application of environmental…by CS Goldberg · 2016 · Cited by 1438 — Critical consideratio…

In a cryptozoological context, an unusual sequence may sometimes reflect:<div class="content-enhancement content-enhancement--example" markdown="1">

  • An incomplete reference database.
  • A degraded DNA fragment that cannot be identified precisely.
  • Similarity between closely related species.

Neil Gemmell - Environmental DNA for Biodiversity, Biosecurity, Global Health and Monster Hunting

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What the Loch Ness Example Actually Shows

The Loch Ness eDNA survey illustrates both the strengths and limits of the method.

How to Control Contamination in PCR lab

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What Checks Make a Claim Stronger?

Because contamination and misleading detections are well-known risks, researchers use several safeguards before accepting an unexpected result.

A stronger claim usually includes:<div class="content-enhancement content-enhancement--insight-grid" markdown="1">

  • Multiple independent samples producing the same result.
  • Negative controls showing no contamination.
  • Replicate laboratory analyses.
  • DNA detections across different locations and times.
  • Genetic markers that uniquely identify the organism.
  • Independent confirmation from additional methods where possible.[Wiley Online Library+3bvna+3BES Journals]bvna.comConfidence in Your Environmental DNA StudyNegative control samples should be included in the field and filtering steps to assess for…</div>

Researchers also increasingly use statistical models that explicitly account for false-positive and false-negative detections rather than assuming every result is correct. These approaches help estimate how likely an apparent detection is to represent a real biological signal.[Nature]nature.comOptimising sampling and analysis protocols in…by A Buxton · 2021 · Cited by 89 — Here we analyse a large qPCR based eDNA data se…False Positives illustration 3

Why Caution Matters More for Extraordinary Claims

Environmental DNA has become one of the most promising scientific tools available to cryptozoology because it can test biological claims directly rather than relying solely on sightings and photographs. Yet its sensitivity creates a paradox: the same technology that can detect rare organisms can also detect contamination, transported DNA, and analytical noise.[BES Journals]besjournals.onlinelibrary.wiley.com2041 210X.12595BES JournalsCritical considerations for the application of environmental…by CS Goldberg · 2016 · Cited by 1438 — Critical consideratio…

As a result, the most convincing eDNA evidence for an unusual lake inhabitant would not be a single surprising sequence. It would be a repeatable pattern observed across independent samples, supported by strong controls, consistent through time, and robust against alternative explanations. Until those checks are satisfied, an unexpected DNA match is best viewed as a lead to investigate rather than proof that a lake monster has been found.[BES Journals+2Wiley Online Library]besjournals.onlinelibrary.wiley.com2041 210X.12595BES JournalsCritical considerations for the application of environmental…by CS Goldberg · 2016 · Cited by 1438 — Critical consideratio…

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Endnotes

1. Source: besjournals.onlinelibrary.wiley.com
Title: 2041 210X.12595
Link:https://besjournals.onlinelibrary.wiley.com/doi/10.1111/2041-210X.12595

<summary>Source snippet</summary><p>BES JournalsCritical considerations for the application of environmental…by CS Goldberg · 2016 · Cited by 1438 — Critical consideratio…</p>

2. Source: onlinelibrary.wiley.com
Title: Online Library What do you mean by false positive?
Link:https://onlinelibrary.wiley.com/doi/full/10.1002/edn3.194

<summary>Source snippet</summary><p>Darling - 2021by JA Darling · 2021 · Cited by 128 — The term false positive is often misused in eDNA research and natural resource manage…</p>

3. Source: nature.com
Link:https://www.nature.com/articles/s41598-021-91166-7

<summary>Source snippet</summary><p>Optimising sampling and analysis protocols in…by A Buxton · 2021 · Cited by 89 — Here we analyse a large qPCR based eDNA data se…</p>

4. Source: bvna.com
Link:https://www.bvna.com/insight/confidence-your-environmental-dna-study

<summary>Source snippet</summary><p>Confidence in Your Environmental DNA StudyNegative control samples should be included in the field and filtering steps to assess for…</p>

5. Source: besjournals.onlinelibrary.wiley.com
Title: 2041 210x.70328
Link:https://besjournals.onlinelibrary.wiley.com/doi/10.1111/2041-210x.70328

<summary>Source snippet</summary><p>ballast water, transport) or naturally…</p>

6. Source: onlinelibrary.wiley.com
Link:https://onlinelibrary.wiley.com/doi/full/10.1002/edn3.124

<summary>Source snippet</summary><p>Wiley Online LibraryAccounting for false positive detections in occupancy…by R Tingley · 2021 · Cited by 33 — We investigated the like…</p>

7. Source: besjournals.onlinelibrary.wiley.com
Link:https://besjournals.onlinelibrary.wiley.com/doi/10.1111/2041-210X.12452

<summary>Source snippet</summary><p>false positives: synthetic oligonucleotide controls…by CC Wilson · 2016 · Cited by 50 — A significant risk associated with eDNA method…</p>

8. Source: nhm.ac.uk
Link:https://www.nhm.ac.uk/discover/what-is-environmental-dna-edna.html

<summary>Source snippet</summary><p>If someone tested a sample of the water, these pieces of DNA could indicate the recent…Read more…</p>

9. Source: pmc.ncbi.nlm.nih.gov
Title: Pub Med Central What do you mean by false positive
Link:https://pmc.ncbi.nlm.nih.gov/articles/PMC8941663/

<summary>Source snippet</summary><p>Misunderstandings regarding the term “false positive” present a significant hurdle to broad adoption of eDNA monitoring methods.Read more…</p>

10. Source: pubmed.ncbi.nlm.nih.gov
Link:https://pubmed.ncbi.nlm.nih.gov/32310337/

<summary>Source snippet</summary><p>A case study to detect vertebrates at arid zone waterholesby EM Furlan · 2020 · Cited by 72 — Here, we use data from an eDNA metaba…</p>

11. Source: otago.ac.nz
Title: first edna study of loch ness points to something fishy
Link:https://www.otago.ac.nz/news/newsroom/first-edna-study-of-loch-ness-points-to-something-fishy

<summary>Source snippet</summary><p>University of OtagoFirst eDNA Study Of Loch Ness Points To Something Fishy5 Sept 2019 — Eels are very plentiful in Loch Ness, with eel DN…</p>

12. Source: sciencefocus.com
Title: loch ness monster dna study reveals plausible explanation for sightings
Link:https://www.sciencefocus.com/news/loch-ness-monster-dna-study-reveals-plausible-explanation-for-sightings

<summary>Source snippet</summary><p>Science FocusLoch Ness Monster DNA study reveals 'plausible'…5 Sept 2019 — Loch Ness Monster DNA study reveals 'plausible' explanation…</p>

13. Source: sciencefocus.com
Title: loch ness monster how edna helps us discover what lurks beneath
Link:https://www.sciencefocus.com/nature/loch-ness-monster-how-edna-helps-us-discover-what-lurks-beneath

<summary>Source snippet</summary><p>Loch Ness Monster: how eDNA helps us discover what…5 Sept 2019 — Unfortunatley for Nessie-hunters and conspiracy theorists, the eDNA c…</p>

14. Source: pmc.ncbi.nlm.nih.gov
Link:https://pmc.ncbi.nlm.nih.gov/articles/PMC12393076/

<summary>Source snippet</summary><p>pump, no problem: evaluating passive eDNA sampling for…by PK Nichols · 2025 · Cited by 6 — In fact, false-negative detection rates (1…</p>

15. Source: pmc.ncbi.nlm.nih.gov
Link:https://pmc.ncbi.nlm.nih.gov/articles/PMC8083301/

<summary>Source snippet</summary><p>Promise and Pitfalls of Environmental DNA and RNA…by JA Farrell · 2021 · Cited by 87 — Continuous eDNA- or eRNA-based monitoring progr…</p>

16. Source: pmc.ncbi.nlm.nih.gov
Link:https://pmc.ncbi.nlm.nih.gov/articles/PMC12831013/

<summary>Source snippet</summary><p>and Limitations of eDNA Substrates for Terrestrial…by B Zhao · 2026 · Cited by 7 — Environmental DNA (eDNA) constitutes a valuable too…</p>

17. Source: Wikipedia
Title: Environmental DNA
Link:https://en.wikipedia.org/wiki/Environmental_DNA

<summary>Source snippet</summary><p>Environmental DNAEnvironmental DNA or eDNA is DNA that is collected from a variety of environmental samples such as soil, sediment, fr…</p>

18. Source: iucn.org
Title: Environmental DNA
Link:https://iucn.org/resources/issues-brief/environmental-dna

<summary>Source snippet</summary><p>resourceEnvironmental DNA (eDNA) is defined as the genetic material left by organisms in the environment. It includes DNA from cells, tis…</p>

Additional References

19. Source: freshwaterhabitats.org.uk
Link:https://freshwaterhabitats.org.uk/advice-resources/survey-methods-hub/edna/

<summary>Source snippet</summary><p>About Environmental DNA (eDNA)eDNA for short is DNA that's released into the water by plants and animals in a host of ways: from their sk…</p>

20. Source: reddit.com
Link:https://www.reddit.com/r/Cryptozoology/comments/14b1rzp/so_3_years_ago_a_new_zealand_scientist_took_some/

<summary>Source snippet</summary><p>Discussion on Loch Ness eels and DNA findingsA New Zealand scientist took some E DNA in loch ness and found alot of eel DNA but eels in l…</p>

21. Source: env.go.jp
Link:https://www.env.go.jp/en/

22. Source: researchgate.net
Link:https://www.researchgate.net/figure/Sources-of-eDNA-false-positive-and-false-negative-detections-Errors-can-result-from_fig5_313849926

<summary>Source snippet</summary><p>Sources of eDNA false positive and false negative…False positive detections can result from (1) eDNA contamination of water samples, (…</p>

23. Source: facebook.com
Title: yesterday we heard the results of a large environmental dna or edna study in loc
Link:https://www.facebook.com/FishtheNess/posts/yesterday-we-heard-the-results-of-a-large-environmental-dna-or-edna-study-in-loc/2567990963260672/

<summary>Source snippet</summary><p>Ness District Salmon Fishery BoardSep 6, 2019 — They did a eDNA analysis of Loch Ness, and found eel DNA…. No monster DNA found in Loc…</p>

24. Source: youtube.com
Link:https://www.youtube.com/watch?v=vHGUbLhCyQs

<summary>Source snippet</summary><p>Loch Ness monster might just be a giant eelScotland's fabled Loch Ness monster could possibly be a giant eel scientist said on Thursday a…</p>

25. Source: researchgate.net
Title: (PDF) The Loch Ness Monster: If It’s Real, Could It Be an Eel?[16]
Link:https://www.researchgate.net/publication/390620130_The_Loch_Ness_Monster_If_It%27s_Real_Could_It_Be_an_Eel

<summary>Source snippet</summary><p>An environmental DNA (eDNA) study conducted at the loch. in 2018 detected extraordinary amounts of mitochondrial DNA. and nuclear DNA fro…</p>

26. Source: researchgate.net
Title: 405734229 Addressing false negatives and positives in eDNA studies
Link:https://www.researchgate.net/publication/405734229_Addressing_false_negatives_and_positives_in_eDNA_studies

<summary>Source snippet</summary><p>Addressing false negatives and positives in eDNA studies4 Jun 2026 — However, the implications of detection errors, specifically false po…</p>

27. Source: mba.ac.uk
Title: what is edna and why is it a game changer for ocean observation and conservation
Link:https://www.mba.ac.uk/what-is-edna-and-why-is-it-a-game-changer-for-ocean-observation-and-conservation/

<summary>Source snippet</summary><p>“We can now monitor marine biodiversity quickly, cost-effectively, and with minimal impact on…Read more…</p>

28. Source: theguardian.com
Title: loch ness monster could be a giant eel say scientists
Link:https://www.theguardian.com/science/2019/sep/05/loch-ness-monster-could-be-a-giant-eel-say-scientists

<summary>Source snippet</summary><p>Loch Ness monster could be a giant eel, say scientistsSep 5, 2019 — Loch Ness monster could be a giant eel, say scientists · The Loch Nes…</p>

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