Environmental DNA
Environmental DNA (eDNA) is genomic DNA released into the environment derived from the skin cells, faeces, saliva, and urine of the organisms present within it. Freshwater species are constantly shedding eDNA into the surrounding water, meaning that only a water sample is required in the field to detect the presence of key species. My research has focused on the use of eDNA to detect and map the spread of invasive signal crayfish (Pacifastacus leniusculus), and the remaining endangered native white-clawed crayfish (Austropotamobius pallipes) strongholds in British rivers.
The American signal crayfish (P. leniusculus) (left) was introduced to the UK in the 1970s and has since become the most abundant crayfish species.
As a result, populations of the UK’s only native crayfish, the white-clawed crayfish (A. pallipes), have declined by 95% in some parts of England, with an overall decline of 80% across Europe. The rapid spread of P. leniusculus had also resulted in a steep decline of benthic macroinvertebrates and fishes.
Click HERE to read about how eDNA-based surveys can assess the success of recent endangered crayfish reintroductions and identify river stretches vulnerable to crayfish invasion.
Click HERE to read about my use of eDNA-based methods to detect the invasion front of an advancing signal crayfish population in headwater streams.