Sucking DNA From Air Can Revolutionize How Researchers Track Biodiversity

Sampling DNA in the air may be a creative new way to measure biodiversity, two new studies find.

Researchers collected environmental DNA (eDNA) from the air at two zoos and used it to detect animal species. This new method is a non-invasive way to monitor the animals in an area.

Two groups of researchers—one based in Denmark, the other based in the United Kingdom and Canada—performed independent studies, testing whether airborne eDNA could measure terrestrial animals.

For their work, the researchers collected air samples from the Hamerton Zoo Park in the U.K. and the Copenhagen Zoo in Denmark.

“Both of the research groups who have papers linked in this journal have a long history of developing new techniques in the field of biodiversity monitoring using DNA,” says assistant professor Elizabeth Clare from York University, Canada, then a senior lecturer at the Queen Mary University of London, who led the U.K. study.

“My research group frequently conducts research with elusive animals in difficult environments. We have worked in the tropics, deserts, long distances from internet, mobile phone signals, or even reliable electricity,” Clare tells Treehugger.

“We frequently have to be creative in our efforts to conduct biodiversity research. Finding new ways we can collect information about the elusive animals we work with is our biggest motivation.”

The other researchers in the Environmental DNA Group at Globe Institute, University of Copenhagen, had been working with eDNA.

“Our group works with different aspects of environmental DNA, from the exploration of novel sample types to the analyses of these samples. One such novel sample type is air,” Christina Lynggaard, first author and postdoctoral fellow at the University of Copenhagen, tells Treehugger.

“Air surrounds everything and we set out to explore whether it is possible to filter animal DNA from air and use that to detect them. This, with the aim to help animal conservation efforts.” 

Collecting Air Samples

The usual ways to monitor animals include direct methods such as camera traps and in-person observation, or indirectly through feces or prints. However, these techniques require lots of fieldwork and the animals must actually be present.

If researchers use cameras, they have to know the right locations to place them and then sort through sometimes thousands of images to find photos of the animals they are tracking.

That’s why monitoring air would have so many advantages.

For their work, the two groups of researchers used different methods to filter airborne eDNA.

The team in Denmark collected air samples using a water-based vacuum and blower fans with filters. They collected samples in three places: the okapi enclosure, an indoor rainforest exhibit, and between outdoor enclosures.

The other researchers used filters on vacuum pumps to collect more than 70 air samples from around the zoo, including inside sleeping areas and outside in the zoo environment.

“One of the challenges we faced was to find an adequate air sampler, as we wanted to have a high airflow to increase the probability of finding the particles that we were interested in (vertebrate DNA), but at the same time retain many of these airborne particles,” Lynggaard says.

Another challenge was to avoid contamination in their samples because the air in the labs where the samples were processed could potentially contain contaminating particles.

“For this, we set up a completely new lab dedicated to this project. Here we employed very strict guidelines known from ancient DNA workflows and we even sampled the air in the lab to be sure we did not have any contaminating DNA in the air. We also employed different negative controls and importantly positive controls of species not known to be in the zoo or surrounding area,” says Lynggaard.

“This enabled us to trace whether there was any contamination between samples, simply because we would then see the positive control species appearing in our samples. We did not see this happening and we were therefore able to trust our results.” 

The results were published in two studies in the journal Current Biology.

Revolutionizing Biomonitoring

In both studies, the researchers detected animals from inside the zoos, as well as nearby wildlife. 

The U.K. team found DNA from 25 species of mammals and birds, including the Eurasian hedgehog, which has been declining in the U.K. The Copenhagen researchers detected 49 species including zoo animals (even a guppy in the tropical house) and local animals like squirrels, rats, and mice.

“The non-invasive nature of this approach makes it particularly valuable for observing vulnerable or endangered species as well as those in hard-to-reach environments, such as caves and burrows. They do not have to be visible for us to know they are in the area if we can pick up traces of their DNA, literally out of thin air,” says Clare.

“Air sampling could revolutionize terrestrial biomonitoring and provide new opportunities to track the composition of animal communities as well as detect invasion of nonnative species.”