Environmental DNA (eDNA) surveys involve detecting species from the trace amounts of DNA they shed into their environment. Water, soil or air can be sampled and analysed using species-specific markers to infer the presence of a target species in the environment. eDNA surveys have been shown to be highly sensitive and, in many instances, provide improved detection capabilities at a lower cost than traditional sampling methods (Jerde et al. 2011; Dejean et al. 2012). The potential application of eDNA for detecting particularly low-density populations, such as recent incursions or confirming eradications, is widely promoted (Dejean et al. 2011; Rees et al. 2014). In this study, we investigate the capacity for eDNA to detect an invasive freshwater fish present at extremely low densities. We focus on the species-specific detection of European carp, Cyprinus carpio, from Lake Sorell in Tasmania. The large (~51.6 km2) lake contains the last known population of C. carpio in the state and has been the focus of a control program to contain and eradicate the invader. We present the results of our eDNA survey to detect the remaining C. carpio individuals and outline some of the factors influencing eDNA detection sensitivities. We indicate the conditions under which eDNA surveys may provide the greatest benefit for detecting species at extremely low densities.
Dejean T, Valentini A, Duparc A, Pellier-Cuit S, Pompanon F, Taberlet P, Miaud C (2011) PLoS ONE, 6:e23398.
Dejean T, Valentini A, Miquel C, Taberlet P, Bellemain E, Miaud C (2012) Journal of Applied Ecology, 49:953-959.
Jerde CL, Mahon AR, Chadderton WL, Lodge DM (2011) Conservation Letters, 4:150-157.
Rees HC, Maddison BC, Middleditch DJ, Patmore JRM, Gough KC (2014) Journal of Applied Ecology, 51:1450-1459.