Genetic Traces Reveal River Residents
1,072 Species in a Bucket of Water
- 26.08.2026
Can DNA traces in just two litres of water reveal how a river’s biodiversity changes over the course of a year? A study by the University of Duisburg-Essen using the River Lippe as an example shows how biodiversity in freshwater ecosystems can be monitored comprehensively, efficiently and at comparatively low cost. The results have now been published in the journal Ecological Indicators.
Till-Hendrik Macher and Robin Schütz, both doctoral researchers in biology at the University of Duisburg-Essen at the time of the study, visited the restored mouth of the River Lippe near Wesel every two weeks for a year, filtering two water samples on each occasion – 26 sampling events and 52 samples in total. Across these samples, they detected a total of 1,072 species: 40 fish and lamprey species, 41 bird and 26 mammal species, 425 freshwater and 350 terrestrial invertebrates, as well as 190 diatom species. By comparison, the Global Biodiversity Information Facility (GBIF) lists a total of 1,029 species for the same location, based on records accumulated over more than 130 years.
Conventional monitoring methods involve identifying individual organisms using nets, forceps, magnifying glasses and microscopes. DNA metabarcoding, by contrast, can identify species from the genetic information they leave behind in environmental samples.
“With two litres of water per sampling event, we detected 1,072 species across the tree of life – from diatoms and mayflies to beavers,” says Till-Hendrik Macher, first author of the study, who now conducts research at Trier University. “And we were able to show that our data actually reflect the biology of the River Lippe rather than merely DNA that happened to be washed into the river,” adds Robin Schütz, who now works as a scientist at the German Federal Agency for Nature Conservation. “Winter-spawning fish such as burbot and northern pike, for example, showed their eDNA peaks in winter, while the greater white-fronted goose peaked precisely during its wintering period.” The study found that the seasonal patterns detected by eDNA largely reflected species-specific biological processes.
The approach is also economically attractive, as the demand for this kind of biodiversity data is growing. Both the Kunming-Montreal Global Biodiversity Framework (GBF) and national and European reporting requirements call for a spatial and temporal density of biodiversity data that is difficult to achieve using conventional methods alone.
Effective and cost-efficient
Using Macher and Schütz’s approach, analysing all 52 samples cost around €12,000. A comparable conventional survey of the same groups of organisms over the course of a year would cost around €70,000 – roughly six times as much. Overall, the study found eDNA monitoring to be highly cost-effective, providing substantially more biodiversity information than many conventional surveys at a fraction of the cost.
Under the EU Water Framework Directive, an average of 1.71 of the four biological quality elements – fish, invertebrates, microalgae and aquatic plants – are currently assessed per river, while only a small proportion of water bodies are evaluated using all four. Combining one conventional survey with three eDNA-based sampling events would cover all four biological quality elements at around 115 per cent of the current budget.
“The calculation shows the potential of combining the two approaches,” says Florian Leese, head of the Aquatic Ecosystem Research group at UDE. “Environmental DNA does not provide information on biomass or the number of individuals, so we will continue to need other methods as well to obtain a complete picture.”
* The research was conducted as part of the GeDNA and TrendDNA projects, funded by the German Environment Agency (funding code 3719242040, project number 156318), in cooperation with Emschergenossenschaft and Lippeverband (EGLV).
Original publication: Macher T-H, Schütz R, Arle J, Beermann AJ, Haase P, Koschorreck J, Krehenwinkel H, Mora D, Sinclair JS, Zimmermann J, Leese F (2026): eDNA metabarcoding provides scalable and continuous biodiversity monitoring across the tree of life. Ecological Indicators 190, 115316. https://doi.org/10.1016/j.ecolind.2026.115316 (open access).
Picture:
Robin Schütz collecting samples at the mouth of the River Lippe.
Further information:
Prof. Dr. Florian Leese, Aquatic Ecosystem Research, T.+49 201 183-4053, florian.leese@uni-due.de