eDNA (“Environmental DNA”) analysis is a groundbreaking technique that makes it possible to study the prevalence of different species of organisms indirectly through the DNA they shed in the environment. When compared with the direct observation of living organisms, eDNA testing is less intrusive and has the potential to be far more efficient, as the presence of hundreds of species can be detected from a single sample.
How is eDNA testing performed?
Environmental DNA originates from sources like mucus, feces, hair, or dead skin cells, and it can be extracted from environmental samples including water, sediment, soil, and air. After extraction, polymerase chain reaction (PCR) is used to increase the abundance of DNA in the sample. The DNA is then sequenced and compared to a database of known DNA sequences to identify the species it originated from.
Which organisms can be studied?
The selection of organisms available for identification through eDNA analysis depends on the scope of the DNA database the laboratory has access to. Identifiable organisms are divided into different taxa, such as fungi, crustaceans, fish, insects, and mollusks. Within a taxon, it is possible to detect the presence of several species.
At present, commercial eDNA testing is most often focused on detecting the presence of a single or several target species through species-specific assays. Multiple-species metabarcoding techniques exist as well, and they are likely to become more accessible in the future.
Applications of eDNA analysis
The information that eDNA assays yield can be harnessed for multiple purposes in environmental research, in addition to which it can benefit companies and consultancy firms working on infrastructure projects or industries that may affect the environment.
Examples of eDNA testing applications include the following:
Assessing the effectiveness of conservation efforts by monitoring the presence of endangered species within a habitat.
Monitoring the spread of invasive species.
Evaluating soil quality by studying the prevalence of indicator species, such as microbes and fungi.
Gathering data for an environmental impact assessment before a large-scale infrastructure project, such as harbor, power plant, or highway construction, to minimize the harm to vulnerable species.
The advantages and limitations of eDNA testing
In ideal conditions, eDNA analysis is accurate and repeatable, and requires less expertise than observing and identifying species in nature. It also offers improved opportunities to capture data on rare species and small organisms, such as microbes and insects, that would be difficult to spot directly.
On the other hand, the method is still under development, and many of the potential uses have not yet been actualized. For example, current methods can identify the presence of different species and their relation to other species, but their abundance cannot be accurately deduced. In addition, gaps in reference libraries limit the array of organisms that can be studied.
Advances in method development are gradually addressing these issues, however, and the scope of eDNA testing is set to expand significantly in the upcoming years.
Need an analysis?
Measurlabs offers eDNA analyses for water, soil, and sediment samples. You can request a quote using the form below or at info@measurlabs.com. Please describe the objective of the analysis, the size of the investigated area, and the target species to help us evaluate the feasibility of the project and give a reliable price estimate.
Sources
BC Ministry of Environment: Environmental DNA Protocol for Freshwater Aquatic Ecosystems (PDF)
Finnish Environmental Institute’s Roadmap for implementing environmental DNA (eDNA) and other molecular monitoring methods in Finland – Vision and action plan for 2022–2025