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A citizen scientist wears protective gloves and takes samples from a fresh water lake.

The LeDNA project will disperse hundreds of volunteers to sample environmental DNA from the world’s lakes.Credit: K. Deiner

In a first-of-its-kind project, researchers are tapping into the power of citizen science to collect DNA samples from hundreds of lakes worldwide. Not only will the resulting cache of environmental DNA (eDNA) be the largest ever gathered from an aquatic setting in a single day — it could yield a fuller picture of the state of biodiversity around the globe and improve scientists’ understanding of how species move about over time.

Scientists are increasingly using eDNA — which is shed by all organisms — to evaluate the presence of species in a given environment. Researchers have shown that it can be cheaply and efficiently extracted from water1, soil2, ice cores3 and filters from air-monitoring stations4. It has even been used to detect endangered species that haven’t been spotted for years, including a Brazilian frog species (putatively assigned to Megaelosia bocainensis) that researchers thought went extinct in the 1960s5.

Kristy Deiner, an environmental scientist at the Swiss Federal Institute of Technology (ETH) in Zurich who leads the massive lake project, says that eDNA represents a “paradigm shift” in how scientists monitor biodiversity. Deiner’s research group has already received applications from more than 500 people across 101 countries to participate in collecting eDNA from their local lakes and shipping the samples to ETH Zurich.

These global-scale projects are “really what the eDNA community needs”, says Philip Francis Thomsen, an environmental scientist at Aarhus University in Denmark and a volunteer for the lake project.

“By involving citizens, we not only increase the geographical scope of our sampling but also foster a sense of public ownership and awareness regarding global biodiversity issues,” says Cátia Lúcio Pereira, the project’s coordinator, who works with Deiner at ETH Zurich.

A boon for biodiversity

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Although eDNA is generally considered to be a boon for biodiversity monitoring, researchers recognize that it’s not perfect. For instance, DNA from a particular site might come from a species that just briefly passed through the region, rather than living there. And researchers don’t have a clear understanding of how factors such as microbial ingestion of the DNA, high temperatures and ultraviolet radiation degrade the genetic material once it has been shed, or how those factors might alter the list of species detected.

Deiner acknowledges the limitations, but says that eDNA-monitoring technology has come a long way since it was first used decades ago. She and her team have a plan to carefully handle the samples they receive, extract their genetic material and amplify the plant and animal DNA to detect the presence of species.

“We’re more fine-tuning things now,” Deiner says.

Sampling sites: World map showing the locations of potential sampling lakes for the LeDNA project.

Source: LeDNA.

Deiner also doesn’t necessarily see the transfer of eDNA from one region to another as a negative thing — it could even be used to her advantage. She began studying how eDNA moves in rivers about ten years ago. The genetic material, she suggests, could flow from soil, down rivers and into lakes, making these watery pools the ideal location to sample from to get an idea of the species diversity of an entire region, or catchment.

Her project — called LeDNA, which stands for lake eDNA — aims to prove that the eDNA from a lake represents not just lake-dwelling species, but also terrestrial animals that live along the rivers that feed into the lake and around the lake itself. It will also examine the differences in species richness between geographical regions, and try to decipher how species in various habitats might be interacting with one another.

Local sampling

Deiner’s research group recruited volunteers for LeDNA through a combination of social media, networking with other eDNA researchers and reaching out to citizen-science groups. The recruits will be assigned a lake near them from a curated list of 5,000 around the globe.

“We really worked hard to try and reach a lot of these areas so that the sample is truly a global effort,” Deiner says.

Although the team hasn’t finalized the lakes that it will sample, it hopes to include about 800, says Lúcio Pereira (see ‘Sampling sites’). The researchers also say that they have mostly finished their recruiting phase, although they still want more volunteers in Asia, North Africa and the Middle East.

Once assigned a lake, volunteers will receive instructions and a water-sampling filter. They will all aim to gather their samples on the same day — 22 May, which is the International Day for Biological Diversity — although there is a flexible two-week window for collection if they need it.

Francis Thomsen points out that hundreds of people taking samples might lead to issues with data quality, depending on how closely they each follow the set protocols sent to them. Sampling eDNA, however, is easier to standardize than other biodiversity-monitoring methods, in which surveyors typically have to locate and identify individual species in person, he says.

Lúcio Pereira says that the team recognizes the possible threat to data quality, but that the volunteers will all have identical sampling kits and in-depth training on the sampling protocol.

A perk of participating in the project, particularly for eDNA scientists, is that local partners will be able to use their data in their own research, as well as contribute to LeDNA publications. “What’s cool about this is it’s participatory,” says Rachel Meyer, director of the California eDNA programme, which is run by University of California researchers and matches volunteers with scientists to collect eDNA samples across the state. The data is there “if people want it”, she says, “and there’s plenty of incentive to want it”.

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