What is eDNA?
Living organisms expel genetic material into their environment from their skin, feces, urine, blood, decaying body, or gametes (i.e. eggs or sperm), decaying plant matter, etc. eDNA can then be collected from environmental samples like water, soil, or air.
Surveys for eDNA in aquatic habitats for fish and amphibians have been widely documented in scientific literature in recent years. eDNA applications for early detection of aquatic invasive species are also rapidly emerging.
Benefits of eDNA
eDNA is very sensitive to detection of species and life stages that may otherwise be challenging to identify visually through physical survey efforts. As a result, eDNA provides a mechanism for efficient screening of waterbodies for species presence, which saves labor time in the field. Efficiently identifying aquatic invasive species in a waterbody is of utmost importance for early detection and ideally rapid response.
Sampling for eDNA uses a non-invasive sampling approach that involves collecting water to pick up traces of DNA without having to directly observe, handle, or capture the target species. The resulting data is useful for guiding management decisions. eDNA samples are also collected at varying locations throughout a waterbody, which can assist with spatial location of a detected species for any future physical survey efforts.
eDNA Sampling Methods
Water samples collected for eDNA analysis go through a few steps before usable results can be produced. Those steps are as follows:
- Sample collection
- Concentration
- DNA extraction
- Amplification
- Detection
For more information on those steps, please visit the US Geological Survey’s webpage for The Process of eDNA.
How does DCR Lakes and Ponds Program use eDNA?
The DCR Lakes and Ponds Program currently uses eDNA to confirm presence or absence of aquatic invasive species including zebra mussels, hydrilla, and snakehead fish. These species are not currently widely established in Massachusetts, so this eDNA sampling allows for a better understanding of where the species may be spreading. When there are positive eDNA detections for a particular species, this leads to field surveys by boat and SCUBA to confirm species presence and abundance. As eDNA sampling is also spatially located across a waterbody, the location of a positive sample is also useful in determining where the species may be present.