England’s biggest eDNA species survey captures a decade of Great Crested Newt data
13th May 2024
The country’s largest single species survey using eDNA (environmental DNA) techniques is entering its 10th year, with annual monitoring of nearly 400 ponds – from the Scottish borders to the South of England.
Run by Freshwater Habitats Trust, the PondNet eDNA Survey for Great Crested Newts monitors short- and long-term changes in the national status of this protected species, helping to track population trends and understand the drivers for change.
DNA monitoring involves collecting a water sample and analysing it for traces of DNA to identify which freshwater species are living in the waterbody. eDNA is DNA that is released into the water by plants and animals from their skin, faeces, mucous, hair, eggs and sperm, or when they die.
Each year, between 1st May and 30th June, Freshwater Habitats Trust uses this cutting-edge technique to identify the presence of Great Crested Newt. The charity conducts the surveys during the newt breeding season as this is when these amphibians, which spend most of their lives on dry land, return to ponds to breed.
The survey focuses on 130 1km squares across the country. In each of these squares, Freshwater Habitats Trust staff and volunteers collect water samples from each of the ponds in the square, which are then analysed in a laboratory. The national wildlife conservation charity provides Natural England with the results, helping the Government to fulfil its legal obligation to monitor the species, set out in the Habitats Directive. The results have been used to identify key pressures on newt populations. They also provide a baseline against which to assess the effectiveness of conservation initiatives for this species.
eDNA monitoring can identify very small amounts of DNA and a single water sample taken at any time during the newt breeding season is almost certain to detect the species when it is present. Freshwater Habitats Trust research has shown eDNA monitoring to deliver a 99.3% rate of detection on a single visit.
Find out more about the PondNet eDNA surveys
Freshwater Habitats Trust played a pioneering role in testing the potential for eDNA monitoring to survey Great Crested Newts in ponds and originally tested the technique in 2013. The charity then launched the PondNet eDNA Survey for Great Crested Newt in 2015 and has continued to run the surveys each year, with funding from Defra and Natural England.
Freshwater Habitats Trust Technical Director Dr Naomi Ewald said: “Large, long-term data sets are the key to tracking changes in species populations. Therefore, it’s vital that we keep carrying out these annual surveys.
“We started the PondNet eDNA Great Crested Newt Surveys because Natural England asked us for information on how priority species that rely on ponds were faring. At that time, eDNA monitoring techniques were just emerging but looked very exciting. Our initial tests revealed how much more cost effective and practical this method was than traditional monitoring techniques.
- Dr Naomi Ewald at PondNet eDNA survey site near Norwich, Norfolk.
“As we enter the 10th year of our annual survey we’re building a picture of the fluctuations in Great Crested Newt populations. Our results so far show that, in some years, including 2022, these amphibians are absent from many of the ponds. Over time, we can build a picture to help identify the local and national drivers for these changes and inform conservation for the species.
“Importantly, our monitoring work has so far shown that squares with more ponds are much more likely to support Great Crested Newts, and provide stability over time. In addition, squares with fewer ponds are hit much harder during years when numbers are declining – with newts often not returning. This highlights the importance of this protected species having access to a network of clean water ponds.”
View the PondNet eDNA survey maps
- Great Crested Newt. Copyright David Orchard.