eDNA offers a non-invasive, cost-effective, and highly sensitive approach for detecting biodiversity. It can reveal the presence of rare, cryptic, elusive or hard-to-observe species without needing to catch, handle or directly observe them, making it a powerful complementary tool for biodiversity monitoring, environmental management and conservation.
Yes and no. While there are often correlations between eDNA signal strength and factors like biomass or abundance, standard eDNA approaches (such as broad-scale metabarcoding) are not yet reliable for estimating exact numbers. However, some targeted methods, such as species-specific quantitative PCR (qPCR), can provide more precise estimates of abundance or biomass for target species.
eDNA can also help identify patterns and trends over time and across locations. For example, it can be used to detect seasonal changes in species occurrence, compare biodiversity between sites or monitor changes associated with management actions and environmental conditions (e.g. inside and outside a marine park).
eDNA can detect a wide range of organisms, from microbes to large vertebrates, as long as their DNA is present in the environment and matches reference databases. The type of assay used will determine which groups of organisms are targeted for detection.
The length of time eDNA remains detectable varies considerably depending on environmental conditions such as temperature, sunlight, microbial activity, water flow, soil characteristics and habitat type. In many cases, eDNA persists from a few hours to several days, although it can remain detectable for longer under certain conditions.
In marine environments, for example, eDNA typically lasts from a few hours to a few days, and sometimes up to a week or more in colder or deeper waters.
Because eDNA degrades over time, it is generally considered a snapshot of recent biological activity. This makes it a valuable tool for understanding which organisms have been present in an area recently and for monitoring changes in biodiversity across time and space.
A species may not appear in your search results because it was not detected in the available samples, the species is not targeted by the assay used, or reference DNA sequences are unavailable or incomplete.
Not necessarily. eDNA can move through the environment, particularly in aquatic systems. A detection indicates that DNA from a species was present in the sampled environment, but interpretation should consider local conditions and sampling context.
A non-detection does not necessarily mean a species is absent from an area. It simply means that the species was not detected in the sample analysed. There are many reasons why a species may not be detected, including low abundance, limited sampling effort, environmental conditions, the availability of reference DNA sequences and the laboratory and analytical methods used.
