Airborne DNA could revolutionize our ability to monitor animal biodiversity
Two independent research groups detect the presence of animals by collecting DNA from the air.
Two new studies published today (January 6, 2022) in the journal Current biology show that environmental DNA (eDNA) taken from the air can be used to detect a wide range of animal species and offer a new non-invasive approach to monitoring biodiversity.
The findings were made by two groups of independent researchers, one based in Denmark, the other based in the UK and Canada. Both research groups set out to test whether airborne eDNA could be used to detect terrestrial animal species. To do this, the research teams took air samples from two European zoos, Hamerton Zoo Park in the UK and Copenhagen Zoo in Denmark.
The UK study was led by Assistant Professor Elizabeth Clare of York University, Canada, then a senior lecturer at Queen Mary University of London, while the Danish study was led by Associate Professor Kristine Bohmann from the Globe Institute of the University of Copenhagen.
Each team used a different method of filtering airborne eDNA, but both managed to detect the presence of numerous animal species within and beyond the boundaries of the two zoos.
Bohmann’s team took air samples using three different air sampling devices; a commercial water-based vacuum cleaner and two blower fans with filters attached – the smaller of these two was the size of a golf ball. They took air samples from three locations: the okapi stable, the Rainforest House, and outside between the outdoor enclosures.
Clare’s team used sensitive filters attached to vacuum pumps to collect more than 70 air samples from different locations around the zoo, both inside the animals’ sleeping areas and outside in the general environment of the zoo.
The results of both studies exceeded their expectations.
“When we analyzed the collected samples, we were able to identify the DNA of 25 different species of animals, such as tigers, lemurs and dingoes, 17 of which were known zoo species. We were even able to collect the eDNA from animals that were hundreds of meters from where we were testing without a significant drop in concentration, and even outside of sealed buildings. Animals were inside, but their DNA leaked. escaped,” Clare explains.
“We were amazed when we saw the results,” says Bohmann. “In just 40 samples, we detected 49 species covering mammals, birds, amphibians, reptiles and fish. In the Rainforest House, we even detected the guppies in the pond, the two-toed sloth and the boa. When sampling the air in a single outdoor site, we detected many animals with access to an outdoor enclosure in this part of the zoo, for example kea, ostrich and rhinoceros.
Many of the species detected were kept in zoos, but remarkably, both teams also detected species in areas surrounding the zoo. The Eurasian hedgehog, endangered in the UK, has been detected outside Hamerton Zoo, UK, while the water vole and red squirrel have been detected around Copenhagen Zoo. The two teams also detected the presence of food for animals in the zoo, such as chicken, cow, horse and fish. The wide range of species detected shows the potential that airborne eDNA could be used to detect and monitor terrestrial animal species in the wild. This would ultimately support global conservation efforts.
“The non-invasive nature of this approach makes it particularly useful for observing vulnerable or endangered species as well as those found in hard-to-reach environments, such as caves and burrows. ‘be visible so we know they’re in the area if we can detect traces of their DNA, literally out of thin air,” says Clare. “Air sampling could revolutionize terrestrial biomonitoring and offer new opportunities to track the composition of animal communities as well as to detect the invasion of non-native species.”
Living organisms release DNA into their surrounding environment when they interact with them, and in recent years eDNA has become an important tool for species detection in a wide range of habitats. For example, eDNA analysis of water samples is commonly used to map species in aquatic environments. However, while air surrounds everything on earth, it is only now that airborne eDNA has been explored for animal monitoring.
One of the main things when demonstrating a new type of eDNA sample is to ensure that the results are reliable because eDNA analyzes are very sensitive and prone to contamination.
“Air is a difficult substrate to work with because air surrounds everything, which means the risk of contamination is high. We wanted to make sure that the species we detected came from the zoo and not from the laboratory for example. to make sure we didn’t have any contaminating DNA floating around in the lab air, we took some air inside the lab and sequenced that as well,” says Dr Christina Lynggaard, who is part of of the Danish team.
For these first studies, it is essential to be able to reproduce the work. The teams had no knowledge of each other’s work until the end of the studies, but were delighted with the parallel nature of the experiments. Clare and Bohmann agree that having two research teams independently demonstrate that airborne eDNA can be used to monitor a range of animal species greatly enhances the strength of their work and clearly shows the potential of the technique.
“We didn’t think sucking animal DNA into the air would work,” adds Bohmann, “it was high-risk, high-reward science with the potential to push the boundaries of vertebrate biomonitoring. It is clear that the sky is not the limit.
Using airborne eDNA sampling in natural environments will require further research to unlock its full potential, but both research teams believe it could transform the way researchers study and monitor animal biodiversity.
“Measuring Biodiversity from Airborne DNA AND Airborne Environmental DNA for Terrestrial Vertebrate Community Monitoring” by Elizabeth L. Clare, Chloe K. Economou, Frances J. Bennett, Caitlin E. Dyer, Katherine Adams, Benjamin McRobie, Rosie Drinkwater and Joanne E Littlefair, January 6, 2022, Current biology.
“Airborne Environmental DNA for Terrestrial Vertebrate Community Monitoring” by Christina Lynggaard, Mads Frost Bertelsen, Casper V. Jensen, Matthew S. Johnson, Tobias Guldberg Frøslev, Morten Tange Olsen, and Kristine Bohmann, January 6, 2022, Current biology.