eDNA, or environmental DNA is genetic material left by an organism into its environment. In the case of great crested newts, eDNA can be found in water samples collected from ponds. Newt DNA is released into the water via shed skin cells, mucus, sperm, eggs, faeces and from decomposing animals. Studies suggest that both the larval stage and adult stages are detectible using eDNA analysis (Rees et al, 2017; Buxton et al, 2017).
Newt eDNA can persist in water for several weeks, allowing us to test for its presence in water samples.