DNA fragments reveal the variety of species in rivers

November 8, 2018, Ecole Polytechnique Federale de Lausanne
DNA fragments reveal the variety of species in rivers
Credit: Pixabay

Bits of genetic material in rivers make it possible to detect the organisms living in them – without having to collect these and examine them under the microscope. Researchers at Eawag, the ETH and the EPFL have now developed a computer model that, with the help of single DNA measurements, even simulates exactly where and how often the species are present in bodies of water.

Every living thing leaves behind tiny traces of its , for example in the form of dead skin cells or excrement. If one now takes water samples and decodes the environmental DNA (also known as eDNA) therein, one knows which species cavort in which waters. One thus discovers that literally fall through the net during normal testing. To be sure, this concept of eDNA has long been known. But: "Until now one could determine from eDNA whether a species is present or not. But how this species is distributed in the whole ecosystem was unknown," says Luca Carraro. He is now an Eawag researcher, after finishing his doctorate in environmental hydrology this summer at the EPFL.

Together with researchers at Eawag, the ETH and the EPFL, he has succeeded in reconstructing the extensive presence of from selective eDNA measurements. For the first time, Carraro and his colleagues have used the method to determine the biomass distribution of a bryozoan (Fredericella sultana) and its parasite (Tetracapsuloides bryosalmonae) in the Wigger – a prealpine Swiss river. The parasite causes the dreaded fish disease PKD, which carries off thousands of trout every year in Switzerland.

Computer model takes into account hydrology and ecology

Credit: Ecole Polytechnique Federale de Lausanne

In order to determine as exactly as possible the distribution of the organisms, the researchers developed a computer model based on hydrological and ecological concepts in river networks. Genetic material measurements are fed into the and take into account the transport and decomposition of the eDNA fragments along the river, as well as local environmental factors. "This method will make it possible to monitor biodiversity all over the world simply and inexpensively. This was not possible up to now with conventional methods," claims co-author and Eawag research group leader Hanna Hartikainen.

Explore further: eDNA emerges as powerful tool for tracking threatened river herring in Chesapeake Bay

Related Stories

Tracking a parasite that's ravaging fish

October 24, 2017

In Switzerland – not to mention the rest of Europe and the United States – freshwater fish are falling victim to a deadly disease that is rampant in the summer and dormant in the winter. It is caused by a parasite that ...

Pond water reveals tropical frogs

August 29, 2018

Globally, there are almost 7,000 species of frogs, the majority of which occur in the tropics. In order to systematically survey their distribution and detect population trends, experts until recently had to stake out the ...

Sampling rivers for genes rather than organisms

December 11, 2014

Effective environmental management depends on a detailed knowledge of the distribution of species. But taxonomists are in short supply, and some species can be difficult to identify, even for experts. Eawag, in collaboration ...

eDNA analysis—a key to uncovering rare marine species

June 15, 2018

The days of searching the oceans around the world to find and study rare and endangered marine animals are not over. However, an emerging tool that can be used with just a sample of seawater may help scientists learn more ...

Recommended for you

The powerful meteor that no one saw (except satellites)

March 19, 2019

At precisely 11:48 am on December 18, 2018, a large space rock heading straight for Earth at a speed of 19 miles per second exploded into a vast ball of fire as it entered the atmosphere, 15.9 miles above the Bering Sea.

Revealing the rules behind virus scaffold construction

March 19, 2019

A team of researchers including Northwestern Engineering faculty has expanded the understanding of how virus shells self-assemble, an important step toward developing techniques that use viruses as vehicles to deliver targeted ...

OSIRIS-REx reveals asteroid Bennu has big surprises

March 19, 2019

A NASA spacecraft that will return a sample of a near-Earth asteroid named Bennu to Earth in 2023 made the first-ever close-up observations of particle plumes erupting from an asteroid's surface. Bennu also revealed itself ...

Nanoscale Lamb wave-driven motors in nonliquid environments

March 19, 2019

Light driven movement is challenging in nonliquid environments as micro-sized objects can experience strong dry adhesion to contact surfaces and resist movement. In a recent study, Jinsheng Lu and co-workers at the College ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.