Why eDNA Matters
eDNA refers to the genetic material (nuclear, mitochondrial or chloroplast DNA) that is released by an organism (as gametes, dead skin cells, feces, urine, mucous, etc.) to its environment and can be collected from that environment using water, sediment, or soil sampling.
The application of eDNA testing is particularly advantageous for aquatic and semiaquatic species, as DNA shed from the target organism is transported through the aquatic environment, improving the ability to detect the target species.
eDNA testing enables more informed decision-making about biodiversity and ecosystem health due to its enhanced sensitivity over conventional methods. These methods are time and labour-intensive, subject to observer bias, and limited in ability to confirm distribution for cryptic species or those with low population abundance (endangered and early stage of invasive species).
eDNA testing is quickly becoming a reliable and robust technique that complements traditional environmental monitoring. It should be recognized that traditional survey techniques still have select advantages to eDNA testing, the most relevant of which may be their ability to distinguish live species and the different life stages of those species. Further, standards for eDNA testing across laboratories are not yet established but need to be carefully considered, creating maximum utility of this evolving technique.
Setting the Standard in Canada
Mérieux NutriSciences is proud to be the first laboratory in Canada to be accredited for eDNA testing by the Standards Council of Canada to rigorous ISO 17025 standards. We are committed to working closely with the eDNA community to develop consensus-based standards to better interpret eDNA results.
Advantages of environmental DNA Testing
eDNA testing has several advantages when compared to conventional survey methods:
- Improved sensitivity
- Time savings
- Cost-effective
- Less invasive
- Permit and license not required
- Reduced observer bias
- Improved field safety
- Accurate
- Retroactive testing
- Expanded window of surveying
Environmental DNA Testing Protocol
Several methodologies for detecting eDNA exist. Most use quantitative polymerase chain reaction (qPCR), also known as real-time PCR, to detect a target species. This method is highly sensitive and allows for the amplification and visualization of trace amounts of DNA using fluorescent dyes.
Due to the nature of environmental DNA, its low abundance, environmental variability, and fluctuating release rates, eDNA assay results are qualitative (detect/non-detect), not quantitative.
Mérieux NutriSciences has licensed the IntegritE-DNA™ method from the University of Victoria Industry Partnerships, developed in the laboratory of Dr. Caren Helbing.
Step-by-Step Protocol
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Sample Collection, Filtration, and Preservation
Ensures optimal recovery and conservation of eDNA. -
eDNA Extraction
Retrieves DNA from the collected sample. -
IntegritE-DNA™ qPCR Assay
Validates DNA quality and checks for PCR inhibitors to avoid false negatives. -
Species-Specific eTarget qPCR Assay
Confirms the presence of target species DNA. Each sample is tested with eight replicates for robust statistical power. Positive and negative controls are included to validate the test performance.
Each extracted eDNA sample provides enough volume for 4–5 species-specific eTarget qPCR assays. This allows for multi-species detection from a single extract, reducing overall costs by avoiding additional collection, extraction, and integrity testing.
