eDNA is latest twist in Green Lake’s own version of NCIS


Water samples are collected and then analyzed for environmental DNA to detect the presence of aquatic invasive species. submitted photo

By Jennifer Fjelsted

Seems like every time you turn on the television you see some new crime show where the hero catches the bad guy using DNA.

But DNA can be used for more than catching criminals.

It also can be used to detect aquatic invasive species in our waterways before they are ever even seen.

This kind of detection science is done through eDNA sampling (environmental DNA).

Before the use of DNA, investigators had to rely on a collection of clues and eyewitness reports to know the who, what, when and where of a crime.

Likewise, scientists also used to rely solely on eyewitnesses in the case of detecting invasive plants and animals in our waterways. In addition to completing a report, a sample also had to be collected and filed.

All this meant many hours of work, especially if the target organism was very small or few in numbers.

eDNA testing turns weeks or months of work into a few hours.

We don’t need eyewitnesses. All we need is a sample of water and/or sediment and we can test if a certain species was on the scene; even if they were never seen.

While establishing an invasive specie’s presence in a body of water still requires a physical specimen, eDNA enables researchers to know of the organism’s presence long before an actual sighting and, therefore, allows for early development of targeted surveillance and management.

The use of eDNA is not science fiction; it is science fact used today for early detection of target species and monitoring of water quality.

Everything in the environment gives off particles of its DNA. By collecting water, DNA can be extracted from those samples to detect pollutants that could be harmful to the lake environment (as well as to humans) and to determine the presence (or absence) of invasive plants and animals.

Additionally, it also can indicate a lack of presence of a native species, which signals to environmental scientists that there could be a potential decline in water quality.

This summer, The Green Lake Association (GLA), in partnership with the Wisconsin Department of Natural Resources, conducted an eDNA investigation on Big Green Lake.

Samples of sediment and water were collected so that scientists could analyze the eDNA samples for New Zealand Mud Snails to see whether Green Lake has been invaded by this traveling mollusk.

The snail, found in other nearby lakes, is small and easily can hitch a ride on boats and gear. With no natural predators, its populations can quickly multiply and they can out compete native organisms for food, disrupting the natural ecosystem.

Results from this sampling will be back this fall.

In addition to the eDNA sampling, the Green Lake Association will be assisting with taking sediment samples and plankton net tows to monitor for the presence for Spiny Water Flea (SWF), an invasive invertebrate found in lakes less than two hours away.

In Madison, SWF is found in the highest densities in the world. “We’re being as pro-active as possible when it comes to invasive species. Yes, we have to monitor and control the ones we already have, but there are plenty of other species that we want to keep a close eye out for and prevent their arrival if possible,” said Stephanie Prellwitz, GLA executive director.

These monitoring methods and the highly accurate analysis of eDNA will help with the prevention and management of invasive species and help to protect the lake we all love.

With monitoring techniques like eDNA sampling, the Green Lake Association, and its partners, can respond to problems early when remediation is a lot easier and often more successful.

This important work is made possible by the continuing support of our members and contributors who care about the future of Green Lake.

Remember, you don’t have to be Agent Gibbs from NCIS to investigate invasive species.

If you see anything unusual the next time you’re enjoying the lake, reach out to us here at the Green Lake Association (920-294-6480) and we’ll help you crack the case.

Jennifer Fjelsted is the communication and project manager for the Green Lake Association, a local not-for-profit that works to improve water quality for Green Lake.

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