eDNA

The U.S. Fish and Wildlife Service currently processes eDNA samples at the Whitney Genetics Lab in Onalaska, Wisconsin. eDNA results from current monitoring efforts can now be found at http://www.fws.gov/midwest/fisheries/eDNA.html.


What is Environmental DNA?

Most of us have seen television shows where crime labs compare a person's DNA sample to DNA found at the crime scene. This gives investigators a clue as to whether or not a particular person may have been at that location at some point. While that type of DNA testing can track a genetic sample to a particular person, there are limitations on what a DNA sample can tell investigators. For example, they may not be able to tell how long a sample has been at a location or how it got there. DNA is found in certain genetic material like hair, skin and bodily fluids.

In much the same way, the Army Corps of Engineers and others have been using environmental DNA, commonly referred to as eDNA, as a surveillance tool to try to find out if DNA from bighead or silver carp is present in certain waterways. eDNA is one of the many surveillance tools used by Asian Carp Regional Coordinating Committee (ACRCC) to monitor and track Asian carp in certain waterways. However, much like the DNA comparisons used to solve crimes, there are also limitations on what eDNA can tell researchers about Asian carp.

eDNA has been used as an early detection surveillance tool since 2009. It provides information about whether Asian carp DNA is present in water samples. What it doesn't tell researchers is if the genetic material came from a live or dead fish, one fish or several, or if the eDNA may have been transported from other sources (e.g., navigation vessels or fish-eating birds). Due to the two-week sample processing time, eDNA cannot yet provide precise, real-time, information about where Asian carp might be.

So if eDNA can't answer all these questions, why use it? Asian carp are notoriously difficult to find in waterways if the population is very low. The eDNA technique is much more sensitive than other standard fishery sampling gear, and is useful for early Asian carp DNA detection and to identify distribution patterns of DNA when the fish are low in abundance. A positive eDNA result tells researchers if Asian carp genetic material is present in an area, then that area may be a good place to use other sampling tools, such as netting, to look for signs of live Asian carp. It is important to note though, that despite over two years of eDNA sampling, hundreds of hours of monitoring efforts and tons of fish harvested, only one Asian carp has been captured in the Chicago Area Waterways above the electric barriers in the Chicago Sanitary and Ship Canal.

At present, eDNA evidence cannot verify whether live Asian carp are present. Released fall of 2011, the Environmental DNA (eDNA) Independent External Peer Review (IEPR), conducted by objective panelists with technical expertise in genetics and population ecology, confirmed eDNA sampling and testing methodology is sound for detecting silver and bighead carp DNA but cannot indicate the source of Asian carp DNA (information on the size, gender, number and age of individuals present and cannot distinguish between pure silver or bighead carp and their hybrids). To view the current USACE sampling results, please visit: http://www.lrc.usace.army.mil/AsianCarp/eDNA.htm

Quality Assurance Project Plan

The Quality Assurance Project Plan (QAPP) for the Environmental DNA (eDNA) Monitoring of Invasive Asian Carp in the Chicago Area Waterway System (CAWS) outlines the detailed procedures for the planning, collection, filtering, processing and reporting of eDNA samples and will be refined periodically. This document, which has undergone a technical review by scientists at Argonne National Laboratory, is the result of collaboration between USACE biologists and geneticists and builds upon the initial protocols developed by researchers at the University of Notre Dame. Download the plan here.

The Environmental DNA (eDNA) Independent External Peer Review (IEPR) confirmed eDNA sampling and testing methodology is sound for detecting silver and bighead carp DNA but cannot indicate the source of Asian carp DNA. To learn more about the U.S. Army Corp of Engineers'completed peer review reports, please visit: http://www.usace.army.mil/Portals/2/docs/civilworks/Project%20Planning/eDNA_response.pdf

 

Introducing ECALS.

In late 2011, the ACRCC funded a study to better understand eDNA. This study is being referred to as the eDNA Calibration Study, or ECALS.

Learn more about ECALS»


Environmental DNA Frequently Asked Questions

What is environmental DNA, or eDNA?
Environmental DNA (eDNA) is the genetic material of an organism that is found in the environment. Organisms, like Asian carp, release DNA into the environment in the form of secretions (slime), feces, and urine. These substances and the DNA within them slowly degrade in the environment, but can be collected in water samples if caught soon enough.

What is eDNA testing and how does it work?
eDNA testing was developed to improve monitoring of invasive species. All fish, including Asian carp, release DNA into the environment. The potential presence of individual species can be detected by collecting water samples in the field and filtering them in the lab. DNA is extracted from the water samples and identified using genetic markers that are unique to bighead and silver carp.

eDNA testing is useful as a potential early indicator of Asian carp presence. However, as there remain many uncertainties about what a positive eDNA sample indicates, its usefulness is limited, and there are many other tools we are employing to ensure we are tracking and combating the advancement of Asian carp.

A positive eDNA hit does not necessarily indicate the presence of a live carp. At present, eDNA evidence cannot verify whether live Asian carp are present, whether the DNA may have come from a dead fish, or whether water containing Asian carp DNA may have been transported from other sources, such as bilge water. The USACE Engineering Research and Development Center plans to undertake studies to refine the use of eDNA and enhance its utility in this effort. To view the USACE sampling results, please visit: http://www.lrc.usace.army.mil/AsianCarp/eDNA.htm.

For more information on eDNA testing visit http://www.lrc.usace.army.mil/pao/eDNA_FactSheet_20090918.pdf

Has Asian carp DNA been found in the Chicago Area Waterway System (CAWS)?
Yes, since testing began in summer 2009, Asian carp eDNA has been detected in multiple portions of the CAWS. Maps showing eDNA detections are available at: http://www.lrc.usace.army.mil/AsianCarp/eDNA.htm.

What does it mean to find eDNA of an Asian carp?
Positive eDNA detection means that Asian carp eDNA was detected in a water sample. A positive eDNA hit does not necessarily indicate the presence of a live carp. At present, eDNA evidence cannot verify whether live Asian carp are present, whether the DNA may have come from a dead fish, or whether water containing Asian carp DNA may have been transported from other sources, such as bilge water. The USACE Engineering Research and Development Center plans to undertake studies to refine the use of eDNA and enhance its utility in this effort.

eDNA testing is useful as a potential early indicator of Asian carp presence. However, as there remain many uncertainties about what a positive eDNA sample indicates, its usefulness is limited, and there are many other tools we are employing to ensure we are tracking and combating the advancement of Asian carp. This comprehensive approach includes electro-fishing, netting, the operation of electric barriers, and the construction of fencing to prevent carp from crossing between waterways, among dozens of other measures.

How can eDNA help in the fight to keep Asian carp out of the Great Lakes?
Because Asian carp release DNA into the environment, and scientific sampling can detect and identify species-specific organisms (both the bighead and silver carp in this case), eDNA is being used to indirectly observe the possible presence of Asian carp. Locating eDNA of the Asian carp is therefore being used as an early detection tool to identify possible Asian carp locations and inform managers and scientists of the possible presence of Asian carp. It is being used as a basis to take aggressive management actions, despite the capture of only one live Asian carp above the electric barrier.

Why have no actual Asian carp been found in the areas where eDNA testing has identified them?
A positive eDNA hit does not necessarily indicate the presence of a live carp. At present, eDNA evidence cannot verify whether live Asian carp are present, whether the DNA may have come from a dead fish, or whether water containing Asian carp DNA may have been transported from other sources, such as bilge water. If there are Asian carp in the CAWS, they are in low enough numbers that they may avoid detection when traditional fishing/sampling gear is used.

 

Asian Carp Regional Coordinating Committee