Indicators: Environmental DNA

What is eDNA? 

DNA or deoxyribonucleic acid is the molecule that carries genetic information. Environmental DNA, or eDNA, is genetic material that can be found in the environment and can be present in sediment, water and the air as whole cells, extracellular DNA or whole organisms. For example, eDNA in could come from organisms shedding pieces of themselves into the environment around them (by their waste, saliva, shedding hair and skin cells, etc.).  This eDNA can be collected from a number of substrates (water, soil, rocks, woody debris) and tested in a laboratory which would provide information on which species may be present.  

Why is eDNA important? 

Knowing the organisms found in an area can give clues about the condition of the environment because some types of organisms can only survive in high quality areas (like a “canary in a coal mine”) while others can withstand poor conditions more easily. The traditional methods used to gather information like this are visual observations in the field and the collection and preservation of organisms for identification in a laboratory. As science and technology have advanced, new methods have been discovered to gain this information. One of these methods uses eDNA. The use of eDNA has proven to be useful for scientists as it is can be less time consuming and less damaging to the environment. Testing water samples for eDNA for example can in some cases be faster and less expensive than traditional methods and can identify which native, invasive or endangered species are present.  

What does eDNA tell us about the condition of water? 

eDNA provide a “snapshot” of information about the different types of organisms that may be found at or near a site of interest. Biologists are often interested in measuring biodiversity which is the different varieties of life present in an area. Higher biodiversity usually means a more environmentally stable conditions that can benefit both aquatic life and humans.  

There are also different approaches to using eDNA, depending on the type of information needed. For example, scientists can identify the entire community of organisms within a sample (called “metagenomics”), or they may look for individual species by searching for a specific DNA sequence in the sample (called “eDNA barcoding”). No matter which techniques are used, eDNA can provide a great deal of information that can help to manage water resources in the United States. 

The National Aquatic Resource Surveys have begun to collect eDNA data to supplement survey work to help provide more comprehensive data on the biodiversity at a site and may enhance the ability to develop biological condition estimates for our waterbodies. This supports the mission to assess the status of and changes in quality of the nation’s waters and to produce even better data for the public, decision makers and other water quality programs.  

How is this indicator used in NARS? 

Environmental DNA is a research indicator in the National Lakes Assessment.