eDNA Communication Strategies- Resource Manager's eDNA Toolbox

“No surprises” is crucial for effective communication and management. This encourages teamwork and trust among experts, decision makers, and other interested parties. eDNA workflows that intentionally consider a no surprise policy should increase the likelihood that detection data will be valuable to natural resource management.^[17]

Operations and communications plans should be jointly developed by eDNA scientists, decision makers, and interested parties before starting any eDNA sampling. Plans should include:

• definitions of critical terms like what is a negative, positive, or inconclusive eDNA sample and site.
• the risk tolerance profile of the decision-maker.
• the spatial and temporal detection patterns that would trigger a decision point (Figure 2).

Multiple examples of eDNA detection decision trees exist and can be modified as needed to meet the needs of the entities involved.^[1][15] Plans should:

• describe the end-to-end sequence of information flow from lab experts to decision makers to the public (Figure 1).
• include a jointly developed and signed document, such as a RACI (Responsible, Accountable, Consulted, Informed) chart or checklist, that clarifies roles of all relevant individuals and parties. This will help to ensure agreement in how to continue before eDNA data are already in hand, and to lessen the chance for unplanned surprises.^[17]

Flow of eDNA results 

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The diagram to the right is an example of the general flow of eDNA results and how the information is passed internally before being made available to external clients. 

Detection decision points

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The flowchart to the right provides an example of important detection decisions involved during eDNA analysis. Please click on the image for further information on the steps involved.

Detection workflow

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The flowchart to the right is an example of an eDNA sample detection workflow and the steps involved. The thresholds shown in this diagram are for example purposes only. Please click on the image for further information.

False positives and false negatives

Environmental DNA is a powerful monitoring tool; however, it's not perfect.  Errors can result during eDNA analysis, especially during the sample collection and laboratory analysis stages. Terms that are important to understand are false positives and false negatives. 

• False Positives site – refers to the detection of a species’ DNA in an environment, despite the species physical absence in the environment. Mismatches between the presence of target species’ eDNA in a site and the presence of the target organism can be caused by several factors. These include eDNA flowing into a site from elsewhere, being stirred up from old deposits preserved in the sediment, species moving in and out of the area, and unintended transfer of DNA by humans or wildlife.
• False Positives sample – refers to the detection of a species’ DNA in a sample, despite the DNA’s absence in the sample. These instances are usually associated with non-target amplification or contamination.
• False Negatives – refers to the failure to detect a species’ DNA at a sample or site despite the species or its DNA being present in the sample or site.

False positives can negatively impact eDNA detections, but there are ways to reduce the likelihood of contamination. Many times, false detections come from environmental factors as well as methodological mistakes.^[16] It’s important to establish strict protocols in the lab and the field when sampling to reduce the chance of contamination. Using multiple PCR replicates can help reduce false negatives.  It’s recommended to use Minimum Information for Publication of Quantitative Real-Time PCR Experiments (MIQE) guidelines and best practices in laboratories for PCR experiments to reduce and to alert to false-positive errors.^[3][6]