eDNA Captured Along With Particulate Matter Reflects Local Biodiversity

The increasing loss of biodiversity and the rising incidence of species extinction is a severe threat to global ecosystems. However, measuring those losses on a global scale has been impossible, owing in large part to a lack of the necessary infrastructure.

However, according to a new study published on June 5^th, 2023, in the journal Current Biology, a major source of such data already exists in the form of environmental DNA (eDNA), which has been accidentally accumulated in filters by thousands of ambient air quality monitoring stations around the world for decades.

One of the biggest challenges in biodiversity is monitoring at landscape scales—and our data suggest this could be addressed using the already existing networks of air quality monitoring stations, which are regulated by many public and private operators. These networks have existed for decades, but we have not really considered the ecological value of the samples they collect.”

Elizabeth Clare, York University

“Existing and established air quality networks are potentially a huge untapped source of biodiversity data. These networks continually sample particulate matter and we now have the ability to make use of this in a whole new way,” says Andrew Brown, National Physical Laboratory (NPL), Teddington, UK.

While air quality monitoring stations have a long history, techniques for capturing and analyzing eDNA from the air have just recently been discovered. Two previous investigations, both published in Current Biology (one by Clare and co-workers), demonstrated that it was able to identify species in a zoo by sampling the air.

After reading about those findings, study co-author James Allerton, National Physical Laboratory (NPL), Teddington, UK, and his NPL colleagues began to examine if filters used to collect air quality data may have relevance for collecting DNA and approached Littlefair and Clare.

Investigators including Clare, Allerton, and Brown, as well as Nina Garrett from York University Toronto and first author Joanne Littlefair from the Queen Mary University of London, investigated whether airborne eDNA containing information about the local plant, insect, and other animal life is caught on filters as a by-product of regularly operating air quality monitoring networks designed to monitor heavy metals and other pollutants in the atmosphere.

They discovered an extraordinary record of biodiversity trapped on filters after isolating and amplifying DNA from filters sampled at monitoring stations in two locations in the UK.

Their research recovered eDNA from approximately 180 distinct plants, insects, mammals, fungi, birds, amphibians, and other groups. According to them, the species list includes “charismatic species such as badgers, dormice, little owls, and smooth newts, species of special conservation interest such as hedgehogs and songbirds, trees including ash, linden, pine, willow, and oak, plants like yarrows, mallows, daisy, nettles, and grasses, arable crops such as wheat, soybean, and cabbage.”

They also claim that the filters contained DNA from 34 different bird species. Longer sample times captured a greater number of vertebrate species, likely because more mammals and birds frequented the area over time.

According to the researchers' results, air quality monitoring networks have been consistently capturing local biodiversity data in a systematic manner and on continental scales for many years, but “the ecological significance of these samples has gone unnoticed.”

Samples are stored for decades in some places, implying that samples capturing ecological data throughout time already exist. The researchers claim that with very minor changes to present air quality monitoring protocols, these samples may be used for extensive monitoring of terrestrial biodiversity, relying fully on an already operational network.

The most important finding, to my mind, is the demonstration that aerosol samplers typically used in national networks for ambient air quality monitoring can also collect eDNA. One can infer that such networks—for all their years of operation and in other countries around the world—must have been inadvertently picking up eDNA from the very air we breathe.”

James Allerton, Study Co-Author, National Physical Laboratory

Littlefair notes, “The potential of this cannot be overstated. It could be an absolute gamechanger for tracking and monitoring biodiversity. Almost every country has some kind of air pollution monitoring system or network, either government owned or private, and in many cases both. This could solve a global problem of how to measure biodiversity at a massive scale.”

The group is now operating to preserve as many samples as possible with eDNA in mind. Although the samples have already been gathered, they warn it will take a global effort to fully exploit the biological information contained in them.