Using environmental DNA to determine how hydropower affects biodiversity in rivers
Author: Juliet Landrø

Using environmental DNA to determine how hydropower affects biodiversity in rivers

Researchers from HydroCen have taken over 400 DNA samples from Norwegian rivers. The aim is to analyze as many as 800 samples nationally to investigate how various forms of hydropower affect species living in the river. Ultimately, the goal is to help the hydropower industry produce more sustainable renewable energy.

As Norwegian rivers cascade through the landscape, a multitude of insects live their lives in these clear waters. Many are so small that you may never have considered their very existence, and some species are most likely to be discovered. How does hydropower impact them? 

Nobody knows.

What we do know is that both EU rules and Norwegian laws require us to take care of them as part of natural biodiversity. If power companies show that they take this into account, they can also create an advantage in the so-called “EU taxonomy”, the new system the EU has introduced for companies to document sustainability.

Environmental DNA revolutionizes mapping of species

Benthic fauna are small animals that live on the river bed. They are, among other things, food for larger species such as fish and birds. Without them we wouldn’t have fish in our rivers. In the past, it has been almost impossible to monitor all of them because they are so tiny and hard to tell apart. But with new technology, scientists believe they can detect more species and distinguish them from each other.

– It is very likely that we will find species that have never been found in Norway before, says NINA-researcher Frode Fossøy.

He is one of the world’s leading experts on environmental DNA (eDNA) and project manager in HydroCen. In collaboration with Hafslund Eco, Vattenfall, Å Energi and the Norwegian Environment Agency a multitude of rivers will be examined to find out if different forms of hydropower operation affect how many species live in the river.

With environmental DNA they can find hundreds of species using a small water sample.


The samples of environmental DNA were collected by filtrating water from rivers all over Norway. Photo: Sonja Kristina Norum Johansen

Investigate developed and protected rivers

Hydropower accounts for 16 percent of the world’s renewable energy production, and has the unique property that it can produce electricity exactly when it is needed, on the contrary to wind and solar power.The water stored in the huge reservoirs can be used at any time, which typically leads to low water in the river downstream of the dam when there is low demand for power, but quickly increases to high water flows when people need a lot of power.

Today, we know a lot about how changes in water flow affect salmon, and what we can do to improve the conditions for this one species, but we know little about how much these changes affect the biological diversity in the river. 

– We will use environmental DNA to see if there is a difference between the species diversity in rivers with large flow changes and those with more regular flows, says Fossøy.

To assess the condition, they will compare with undeveloped, protected rivers in the vicinity. This research is even more relevant recently due to the electricity price debates. Both the development of pumped storage production, the pumping of water back into reservoirs when the price is low, and development of protected rivers have been suggested in the energy debate.

– We don’t know much about the total biodiversity in protected rivers, so it will also be very interesting to see if biodiversity there really is higher than in developed rivers, says Fossøy.

Climate change also affects rivers

It is not only hydropower that can affect biodiversity in watercourses. Climate change, pollution and several other factors cancontribute to decreasing the number of species in a watercourse. Until now it has been more or less impossible to map rivers at such a detailed level, because it has been too expensive and too difficult. This knowledge can be revolutionized with DNA. The same water sample can be used to find bacteria, algae, insects, crustaceans, fish and mammals.

– By using environmental DNA, we have a much better opportunity to get an overview of the species diversity in our rivers, at a much lower cost, says Fossøy.

Models of actual water flow

The flow of water in both regulated and non-regulated rivers varies greatly throughout the season and annually. The same type of regulation could also cause large differences in water flow in different rivers. Therefore, the researchers will use hydrological data in collaboration with experts from SINTEF to look at variation in the water flow the past three years. 

– A lot of data is publicly available, but we will also get valuable contributions from our partners from the hydropower industry, says Fossøy.

The purpose of this modeling is to be able to link variation in water flow to biodiversity, both for different forms of regulation and for non-regulated rivers. This way, the researchers will be able to distinguish between the effect of different types of regulation and the effect of different forms of operation.

– We want to see how water flow alone affects species diversity in the rivers, so that we can help the hydropower industry to optimize operations in the most sustainable way possible, says Fossøy.


Frode Fossøy, NINA


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ArtikkelforfatterJuliet Landrø

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