Environmental DNA, or eDNA, explained
Biodiversity monitoring plays a key role in conservation and restoration projects. However, it isn’t simple. Traditional monitoring methods such as camera traps, visual searches, and aerial surveys, are usually time-consuming and costly. As the current nature and biodiversity crises evolve, monitoring and protecting species has never been more important and time-sensitive. In recent years, a new technology called environmental DNA has been developed to help make monitoring more efficient.
Environmental DNA, also known as eDNA, is all around us, just like DNA. Animals, like humans, leave their genetic traces wherever they go through skin, hair, and faeces, for example. By collecting and analysing samples of water, soil, and even air, we can identify species that have been in the area recently. eDNA provides highly sensitive and rapid results, indicating the presence of a range of species with just one sample. Besides that, it’s also a non-intrusive monitoring method that can be easily combined with and complement the traditional monitoring techniques mentioned previously.
It helps paint a complete, robust and more accurate picture of organisms that live in an area, especially those that are usually overlooked or too small to be visually identified, such as bacteria, microorganisms and small invertebrates. And by doing so, it also supports the understanding of the health of such an environment.
These DNA analyses can also help in invasive species control efforts, and identify travel corridors and changes in wildlife populations, elements which are vital to evaluate when assessing the success of restoration and conservation projects.
“In our field of work, environmental DNA is used as an important restoration monitoring tool because it collects the data needed in a rapid way that is accurate and not very intrusive”, says Carolina Pinto, River Restoration Manager at Thames21.
“This enables river scientists to assess the effectiveness of river restoration projects, for example. With this method, we can detect invasive fish species or even track the migration of fish through a catchment or waterbody. In addition, when comparing eDNA to traditional sampling methods, eDNA is cost-effective which enables us to carry out more extensive sampling, both temporarily and spatially. This data can then be consistently compared over time”, Carolina continues.
eDNA has been widely used in aquatic environments such as the deep sea, due to the inaccessibility of other types of monitoring there, and also in freshwater systems. The Natural History Museum’s GenePools project, for example, uses eDNA to analyse samples from ponds in urban areas to understand how effective gardens ponds are for wildlife.
At Thames21, some of our river restoration projects are also adopting this technology, such as the Rewilding the Rom project. It used eDNA both in its development phase and after completion. The methodology assessed the presence of Great Crested newts in the area prior to construction works starting, helping us make better-informed decisions about areas of work and necessary avoidance measures. After the major work on the site was finished, eDNA sampling sessions identified the presence of Smooth newt, Common toad and juvenile marsh frogs in the newly rewilded wetlands – a promising find.
As technology evolves and more monitoring tools become available, we can maximise conservation initiatives and better assess their impact in the environment, benefitting people and nature. We definitely need all the help and tools we can get to protect and restore nature before it’s too late.