Anthropogenic climate change and human expansion into species-rich habitats have led to a decline in global biodiversity, but quantifying the extent of this decline is complex.
Ecologists are increasingly using traces of genetic material left in the environment by living organisms — known as environmental DNA (eDNA) — to catalog and monitor biodiversity. These samples allow researchers to determine which species are found in a particular area.
Marine eDNA is relatively easy to obtain from water samples. However, achieving this in terrestrial habitats such as forests is not an easy task.
Scientists from the Swiss Federal Institute of Technology in Zurich (ETH Zurich, Germany) and the Swiss Federal Research Institute (WSL) have developed a drone that can autonomously land on tree branches to collect these samples.
“eDNA studies are revolutionizing biodiversity monitoring because they are non-invasive and multiple species, even the elusive ones, can be detected from a single environmental sample, be it water, soil or air,” Mintchev Stefano told SINC. , Professor of Environmental Robotics at ETH Zurich and WSL and co-author of the study published in the journal Science Robotics.
The expert emphasizes that “taking samples is one of the most tedious and expensive parts of the workflow. Drones can automate the extraction of eDNA and get important information in more places and with less effort. This drone is the first robot designed to autonomously collect terrestrial eDNA”.
They tested it on a total of seven tree species in the botanical gardens around the Federal Research Institute. In the samples they found DNA from 21 different groups of organisms, including birds, mammals and insects. “This is encouraging because it shows that the harvesting technique works,” says Mintchev.
A robot with the balance of a bird
It is an encapsulated drone with four wings that contains an adhesive outer layer to capture the trees’ eDNA. But not all branches are the same as they vary in thickness and elasticity. Also, they bend and bounce when an item lands on them, making it difficult to sample. Because of this, scientists built force sensors into their robot to help it sit down and balance.
“Our drone controls its propellers based on the stiffness of each branch. It’s a similar process to birds, which often use their tails and wings to land on very flexible branches,” Mintchev explains.
With all these accessories, the scientists propose this drone as a solution to increase biodiversity in terrestrial ecosystems that are difficult to access, such as B. treetops to measure.
A racing robot
This research is a proof of concept that opens up the possibility of monitoring biodiversity in forests, which has previously required significant effort and expense.
The researchers want to further improve the device in order to prepare it for a competition (XPRIZE Rainforest) whose goal is to discover as many different species as possible in 24 hours in 100 hectares of rainforest in Singapore.
During tests in Switzerland, the drone collected material from seven trees in three days; in Singapore, it must be able to fly and collect samples from ten times as many trees in a single day. For this, the collection device must be more powerful and be mobilized faster.
Additionally, collecting samples in a natural forest poses even more difficult challenges. Frequent rain washes eDNA off surfaces, and wind and clouds make drone operations difficult. “We are very curious to see whether our sampling method will also prove itself under extreme conditions in the tropics,” says Mintchev.