Given the success of the method with Great Crested Newt there may well be a case for assessing the ability of eDNA to:
(a) detect other amphibians: this was originally costed in the project proposal and it may still be valuable to assess the effectiveness of surveys of other amphibian species. It is technically practical to test for the presence of all widespread native amphibians using an eDNA test which costs approximately 50% per sample more than the single species Great Crested Newt test.
(b) Other vertebrates: it may be valuable to test the potential to detect fish for which methods are also rapidly developing. There are reporting needs for relatively widespread protected species (e.g. Atlantic salmon) and for endangered species (e.g. Arctic Charr) which may be enhanced or made more cost-effective with eDNA. Thomsen et al. (2012) demonstrated that eDNA could be used to detect aquatic mammals: species such as Water Vole and Water Shrew which are comparatively cryptic may be amenable to eDNA survey methods.
(c) Other protected species: There are a number of protected invertebrates where methodological challenges of survey work, or the need to avoid disturbance, could make eDNA survey work attractive if it were reliable possible to detect the species. For example, distribution data on the Pearl Mussel (which often has small and difficult to find populations), the Southern Damselfly (where larval surveys to locate breeding sites could damage the habitat) and the Little Whirlpool Ram’s-horn Snail (where very large networks of ditch sites make searching for the species time consuming) might all potentially be enhanced by eDNA methods. The same would potentially be true for many BAP species for which there are national reporting requirements.
(d) Non-native species: eDNA methods have already been identified as potentially valuable for locating populations of cryptic non-native species (e.g. Bullfrog). For example, cryptic non-native fish which may be released into pond systems may be more easily surveyed by eDNA than traditional fish survey methods which are labour intensive.