Søren Nøhr Thomsen (SNT). eDNA
Søren Nøht Thomsen maps the nature enclosing the particular place and registers animals and plants in the area using eDNA
Meet our employees

Using eDNA as a weapon on the hunt for the garlic toad

The North Sea houting, European weather loach, spadefoot toad, European crayfish, and freshwater pearl mussel are not exactly species with whom all Danes are familiar. But consulting biologist at NIRAS, Søren Nøhr Thomsen, is. He is actually quite familiar with them. By using clever methods such as eDNA, Søren can map species like these in aquatic environments and thereby create a foundation for us to better protect their habitats.

When projects that can effect the surrounding natural environment are in the pipeline, MSc (Biology) Søren Nøhr Thomsen is called to assist. Søren maps the nature enclosing the particular place and registers animals and plants in the area. This way, the project manager will know which specific considerations need to be taken into account when a highway, golf course or residential area is being constructed.

Biology has always been Søren’s big passion. The study of how different elements in nature correlate to one another has fascinated Søren for as long as he can remember, drawing him towards lakes and creeks especially. Studying biology was therefore the obvious choice for him.

Today, Søren spends his daily life working for NIRAS where he is a part of Environment West in Aalborg. The combination of field and desk work really appeals to Søren, who especially loves to immerse himself in studying new methods and techniques. eDNA is an area that is really taking off in the industry at the moment. In this field, Søren and his colleague Martin Hesselsøe in Aalborg are two of the country’s leading experts. 

Tattletales in the water environment

eDNA is an acronym for Environmental DNA, and is a relatively new method designed to detect species in aquatic environments. When an organism resides in water, it releases a DNA trace to its surroundings. This trace could consist of skin particles, feces, scales, etc.. By using this method, a water sample can thus show whether a particular organism exists in a given water environment - even if it is not possible to catch it and prove its presence the conventional way.

eDNA can thereby identify the often rare and protected species. As an example Søren mentions the spadefoot toad, which can be very difficult to find with traditional research methods. If taken correctly and with the right equipment, an eDNA water sample will give an instant and unequivocal result.

Aside from being an excellent, time saving supplement to the traditional methods, eDNA also has the advantage that a technician can take the samples without having any specific knowledge about the particular species.

Søren is very excited about the innovative work and method surrounding eDNA:

It is fun to do atypical field work that simultaneously tests and reviews new techniques. It is rarely possible to plan everything from the office – you have to act according to the situation and adapt to the particular conditions.

Søren Nøhr Thomsen, biologist at NIRAS

New opportunities to map the garlic toad

In addition to projects where Søren and his colleagues use eDNA as a supplement to conventional methods, they also work towards expanding our knowledge about the method in its entirety. Søren is working on developing and testing advanced methods, which can be used for filtration.

Additionally, Søren is on the hunt for the rare spadefoot toad – also known as the garlic toad. The spadefoot toad is a protected species in all of the EU and is considered one of Denmark’s rarest toads. It got its nickname “the garlic toad” because of the secretion it releases when it is threatened, which has a distinct smell of garlic. The spadefoot toad is difficult to find with conventional methods. The only thing we know for sure is that its population is declining across the country. The species is therefore often a focus point when building and construction projects are planned near their habitats. This was for example the case in a summerhouse and golfing area where NIRAS mapped the geological spread of the spadefoot toad with eDNA for Syddjurs municipality.

“We know a lot about the biology of the spadefoot toad, but not enough about its geological spread in Denmark. That is something we hope eDNA samples can tell us more about in the future”, Søren says excitedly about the project. He is joyous about all the opportunities and knowledge that the eDNA method entails.