eDNA detection of Cipangopaludina chinensis in the UK, 2022: Pevensey Levels, Sussex and Southampton Common, Hampshire.
Abstract
Based on eDNA and manual survey data carried out in 2021 and 2022 at the Pevensey Levels, Sussex, Natural England has erected four coffer dams in the main colonised ditch and side ditches to prevent further spread of the invasive snail Cipangopaludina chinensis. A concern is if C. chinensis spreads from this original source then there is the risk of disruption to the diverse and extensive freshwater ditch ecosystems on the Pevensey Levels, a habitat for many rare invertebrate species including rare freshwater Mollusca such as the Little Whirlpool Ram's-horn Snail Anisus vorticulus. Water samples taken by Natural England and ADAS staff in August 2022 confirmed the continued presence of C. chinensis within the ditch system albeit in fewer sites than in 2021. Notably C. chinensis DNA was not found in or around the coffer dam erected between sites 9 and 11 but was found within side ditch H and at site 4 to J (where it has not previously been found). C. chinensis has also recently been found at Southampton Common SSSI, Hampshire. The site contains two large artificial lakes that support nationally important breeding assemblages of amphibians. In January 2022, reports were received that the shells of C. chinensis had been found, likely when the boating lake was drained. A manual survey in August 2022 confirmed the presence of C. chinensis and eDNA analysis found that 6 out of the 7 sites sampled were positive for C. chinensis DNA.